Ebook Diagnostic imaging head and neck (2nd edition): Part 2

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Ebook Diagnostic imaging head and neck (2nd edition): Part 2

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(BQ) Part 2 book Diagnostic imaging head and neck presents the following contents: Sinonasal cavities and orbit (orbit, nose and sinus), skull base ( skull base and facial trauma, skull base lesions), temporal bone and CPA-IAC (introduction and overview, external auditory canal, middle ear mastoid,...).

Diagnostic Imaging Head and Neck Part IV - Sinonasal Cavities and Orbit Section - Nose and Sinus Introduction and Overview Sinonasal Overview > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Introduction and Overview > Sinonasal Overview Sinonasal Overview Michelle A Michel, MD Summary Thoughts: Sinus and Nose The anatomy of the sinonasal (SN) cavities is as unique as a person's fingerprints The nasal cavity (NC) is centrally located and is surrounded by the paranasal sinuses (PS) Because the SN region is comprised of air-filled spaces and complex bony architecture, CT is often the first-line imaging modality CT is used for determining the extent of disease and is also helpful for surgical planning and intraoperative guidance As in all regions of the H&N, information, such as patient demographics, presenting symptoms, and clinical exam findings, are critical for interpreting imaging studies of this area It is important to understand the drainage pathways of the PS as one can then predict patterns of disease based upon the point of an obstructing lesion Inflammatory disease is by far the most common pathology However, isolated inflammatory disease of the sphenoid sinus is unusual and should raise suspicion for other pathologies including neoplasm or cephaloceles, particularly if there is an associated bone defect Fortunately, malignancies of the SN cavities are rare They tend to present at an advanced stage and are often in close proximity to vital structures (orbit, cranial nerves, and skull base) These tumors are difficult to completely resect and are associated with high surgical morbidity Presurgical tumor mapping in such cases is best accomplished with multiplanar MR Imaging Approaches and Indications CT is the modality of choice for evaluation of inflammatory disease CT is more sensitive for detecting Ca++ in lesions (fibro-osseous lesions, inverted papilloma, esthesioneuroblastoma) and for evaluating changes in adjacent bone Coronal images best demonstrate the anatomy of the ostiomeatal unit (OMU) MR can be used as a complement to CT for evaluating complicated inflammatory or neoplastic disease MR is generally indicated for evaluation of complex inflammatory disease and neoplasms It is optimal for assessing extension beyond the SN cavities, evaluating perineural tumor spread, and differentiating tumor from postobstructed secretions Imaging Protocols Traditionally, ≤ mm direct coronal images are obtained prone and angled perpendicular to the palate With multidetector CT, coronal reformatted images can be generated from a thin slice axial data set acquired in the supine position This is advantageous as images are less degraded by motion artifact and dental amalgam can be avoided Axial images can often be used in image-guidance systems, obviating additional radiation for “treatment planning” CT prior to surgery Sagittal reformatted images are helpful for delineating frontal recess (FR) and the sphenoethmoid region anatomy MR imaging protocols generally include axial and coronal T1, STIR, and T1WI C+ images with fat suppression Angiography is rarely needed for diagnostic purposes but may be performed for intervention prior to resection of vascular neoplasms Imaging Anatomy The sinonasal region is comprised of the NC and the surrounding PS There are important anatomic relationships with surrounding compartments of the extracranial head and neck, including the anterior cranial fossa, orbits, pterygopalatine and infratemporal fossae, and oral cavity The SN cavities extend into the maxillary, frontal, sphenoid, and ethmoid bones Superiorly, the frontal sinuses border the anterior margin of the anterior cranial fossa The cribriform plate (CP) and fovea ethmoidalis form the borders between the superior NC and ethmoid, respectively The hard palate separates the NC from the oral cavity The NC communicates posteriorly with the nasopharynx via the choanae The orbits are separated from the ethmoid sinuses by the thin lamina papyracea and are separated from the maxillary sinuses by the orbital floors Posterior to the maxillary sinuses are the pterygopalatine fossae, which communicate superiorly with the orbital apices & laterally with masticator space The NC is centrally located and is divided in the midline by the nasal septum The bony septum is formed from the perpendicular plate of the ethmoid posterosuperiorly and vomer bone posteroinferiorly Anteriorly the septum is comprised of cartilage Paired superior, middle, and inferior turbinates project into the NC and their corresponding 841 Diagnostic Imaging Head and Neck meati exit inferior to each The middle turbinate has two attachments: 1) superiorly to the CP via the vertical lamella, and 2) posterolaterally to the lamina papyracea via the basal (ground) lamella The frontal sinuses are often asymmetric in size and are divided in the midline by an intersinus septum Inferomedially, the frontal sinus narrows toward its ostium, which drains into its FR The FR is formed by the walls of surrounding structures The drainage of the FR is determined by the insertion of the uncinate process Most often the uncinate inserts laterally onto the lamina papyracea and secretions drain into the middle meatus (MM) Less frequently, the uncinate inserts onto the anterior skull base or middle turbinate; FR secretions drain via the infundibulum into the MM Paired groups of 13-18 air cells form the ethmoid labyrinths These cells are divided into anterior and posterior groups by the basal lamella The anterior air cells drain into the anterior recess of the hiatus semilunaris and middle meatus via the ethmoid bulla The posterior air cells drain into the superior meatus and sphenoethmoidal recess (SER) The maxillary sinuses lie lateral to the NC and inferior to the orbits Each drains via its maxillary ostium into the infundibulum, then via the hiatus semilunaris into the MM The maxillary sinuses have lateral recesses and alveolar recesses inferiorly The sphenoid sinuses are asymmetric air cells in the body of the sphenoid bone Important surrounding structures include the maxillary division of CN5 in foramen rotundum laterally, the vidian nerve and artery in the vidian canal inferiorly, the optic nerves and sella superiorly, and the cavernous sinuses laterally The sphenoid sinuses drain via their ostia into the SER The OMU is a critical crossroads for drainage of the sinuses most affected by inflammatory disease (anterior ethmoid, maxillary, and frontal) Important components of the OMU include the ethmoid infundibulum, uncinate process, hiatus semilunaris, ethmoid bulla, and MM P.IV(1):3 Approaches to Imaging Issues of the Sinus and Nose Congenital lesions can be classified as those presenting with nasal obstruction vs nasal mass Lesions presenting with nasal obstruction and no mass include pyriform aperture stenosis and choanal atresia Frontonasal cephaloceles, dermoids, and extranasal gliomas present as extranasal masses Frontoethmoidal cephaloceles, intranasal gliomas, and nasolacrimal duct mucoceles present with an intranasal mass MR imaging can be very helpful for evaluating if there is a connection to the intracranial space Rhinosinusitis (RS) is the most common pathology of the SN region Acute RS is usually diagnosed clinically & does not require imaging Always look for an odontogenic source of sinusitis if isolated maxillary sinus disease is identified Because of the anatomy of the PS drainage pathways, predictable patterns of inflammatory disease exist based upon the point of obstruction For example, obstruction of the MM would lead to disease in the ipsilateral frontal, anterior ethmoid, & maxillary sinuses SER obstruction might lead to ipsilateral posterior ethmoid & sphenoid disease Although uncommon, there are several forms of SN fungal disease Mycetoma and allergic fungal sinusitis occur in immunocompetent patients and invasive fungal sinusitis (IFS) occurs in the immunocompromised or poorly controlled diabetics It is important to note that IFS may appear mass-like at imaging Granulomatous disease has a predilection for involving the nasal septum and turbinates There are a wide variety of neoplasms of the SN cavities Imaging features that favor a benignity include bone remodeling and well-defined margins vs bone destruction and infiltrative margins The site of origin may also be suggestive of histology For instance, osteomas most often arise in the frontal and ethmoid sinuses, juvenile angiofibromas (JAF) arise in the posterior NC at the sphenopalatine foramen, inverted papillomas often arise along the lateral nasal wall, and esthesioneuroblastoma (ENB) typically arises near the CP Squamous cell carcinoma is by far the most common SN malignancy and most often arises in the maxillary antrum The imaging features of adenocarcinomas can be nonspecific, but they have a predilection for the ethmoid region Three malignant neoplasms with a predilection for the NC include ENB, lymphoma, and melanoma Clinical Implications The anatomy of the SN cavities is complex and highly variable Technical advances, such as image guidance systems, have helped surgeons, particularly in the frontal & sphenoid sinuses It is important to note that studies have shown a poor correlation between symptoms of RS and CT findings The diagnosis of RS is a clinical one! Disease of the SN cavities often presents with nonspecific symptoms, such as nasal obstruction & discharge Additional symptoms, such as epistaxis, may be indicative of a vascular lesion (JAF or ENB) Pain may also be caused by mucoceles or neoplasms, while paresthesias can be linked to malignancies such as adenoid cystic carcinoma Clinically, lesions located within the NC can be evaluated with endoscopy Lesions involving the sinuses are difficult to evaluate with scopes, so imaging is essential for characterization & determination of disease extent Selected References Beale TJ et al: Imaging of the paranasal sinuses and nasal cavity: normal anatomy and clinically relevant anatomical variants Semin Ultrasound CT MR 30(1):2-16, 2009 842 Diagnostic Imaging Head and Neck Raghavan P et al: Magnetic resonance imaging of sinonasal malignancies Top Magn Reson Imaging 18(4):259-67, 2007 Aygun N et al: Imaging for functional endoscopic sinus surgery Otolaryngol Clin North Am 39(3):403-16, vii, 2006 Tables Differential Diagnosis of Sinonasal Lesion Congenital Benign tumors & tumor-like lesions Nasolacrimal duct mucocele Fibrous dysplasia Choanal atresia Osteoma Nasal glioma Ossifying fibroma Nasal dermal sinus Juvenile angiofibroma Frontoethmoidal Inverted papilloma cephalocele Pyriform aperture stenosis Hemangioma Infectious & inflammatory Nerve sheath tumor Acute rhinosinusitis Benign mixed tumor Chronic rhinosinusitis Malignant tumors Complications of Squamous cell carcinoma rhinosinusitis Allergic fungal sinusitis Esthesioneuroblastoma Mycetoma Invasive fungal sinusitis Sinonasal polyposis Solitary sinonasal polyp Mucocele Silent sinus syndrome Wegener granulomatosis Sarcoidosis Nasal cocaine necrosis Anatomic variations Sinus hypo- or hyperpneumatization Nasal septal deviation & spurs Frontal cells (types I-IV) Ethmoid region Agger nasi cell Infraorbital (Haller) cell Supraorbital ethmoid cell Large ethmoid bulla Sphenoethmoidal (Onodi) cell Asymmetric fovea ethmoidalis Medial or dehiscent lamina papyracea Adenocarcinoma Middle turbinate Melanoma Concha bullosa Non-Hodgkin lymphoma Paradoxical curvature Sinonasal undifferentiated sarcoma Hypoplasia Adenoid cystic carcinoma Uncinate process Chondrosarcoma Pneumatized Osteosarcoma Deviated Rhabdomyosarcoma Fusion to middle turbinate or skull base Metastasis Atelectatic (approximates orbital floor) P.IV(1):4 Image Gallery 843 Diagnostic Imaging Head and Neck (Top) Sagittal graphic demonstrates the osseous anatomy of the lateral nasal wall The superior turbinate & portions of the middle & inferior turbinates have been resected The superior, middle, & inferior meati drain inferior to their respective turbinates The ipsilateral frontal, anterior ethmoid, & maxillary sinuses ultimately drain into the middle meatus The nasolacrimal duct drains into the inferior meatus The sphenoid ostium is located along the anterior sphenoid sinus wall & drains into the SER (Bottom) Coronal graphic of magnified right sinonasal region shows the important structures around the ostiomeatal unit The vertically oriented uncinate process is bounded laterally by the ethmoid infundibulum, superiorly by the hiatus semilunaris, & medially by the middle meatus The ethmoid bulla is the dominant anterior ethmoid cell located superior to the uncinate The middle meatus drains beneath the middle turbinate P.IV(1):5 844 Diagnostic Imaging Head and Neck (Top) Sagittal graphic shows the frontal sinus drainage pathway The frontal sinus narrows inferiorly to its ostium Secretions drain through the ostium into the frontal recess (FR) The FR is not a true duct in that its walls are comprised of adjacent anatomy In the graphic, the FR is bounded anteriorly by an agger nasi cell & posteriorly by the ethmoid bulla Note that FR drainage may vary based upon the point of insertion of the uncinate process (Bottom) Coronal graphic shows the important anatomy surrounding the sphenoid sinuses The cavernous portions of the internal carotid arteries lie lateral & posterior to the sinuses At the orbital apex, the optic nerve can be seen traversing the optic canal Multiple cranial nerves pass through the superior orbital fissure into the orbit including CNs 3, 4, & as well as the ophthalmic division on CN5 The maxillary division of CN5 in foramen rotundum & the vidian nerve are positioned lateral & inferior to the sinus, respectively P.IV(1):6 Image Gallery 845 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows the paired frontal sinuses separated by the intersinus septum The most anterior ethmoid-type cells, the agger nasi, can be seen Notice the air-filled lacrimal sac on the left (Right) Coronal bone CT shows the medial & lateral lamellae of the cribriform plate forming the roof of the nasal cavity The fovea ethmoidalis forms the ethmoid sinus roof Note the patent frontal recesses leading to the middle meati (Left) Sagittal CT reconstruction shows the frontal sinus drainage pathway The sinus drains inferiorly into the frontal recess A frontal cell is anterior to the recess & the ethmoid bulla is posterior Note the middle & inferior turbinates (Right) Axial T1WI MR shows the paired maxillary sinuses lateral to the nasal cavity Note the inferior turbinates , midline nasal septum , & air-filled nasolacrimal ducts above the inferior meati 846 Diagnostic Imaging Head and Neck (Left) Sagittal CT reconstruction shows the nasolacrimal duct draining into the inferior meatus Note the pterygopalatine fossa posterior to the maxillary sinus (Right) Coronal bone CT at the level of the ostiomeatal units shows the uncinate processes , ethmoid bullae , & middle turbinates They are pneumatized as is the right inferior turbinate The middle meatus lies between the uncinate & middle turbinate A retention cyst blocks the left maxillary ostium P.IV(1):7 (Left) Sagittal CT reconstruction shows anterior & posterior ethmoid cells and the sphenoid sinus The lateral attachment of the middle turbinate (basal lamella) is seen Note the hiatus semilunaris The palate is noted inferiorly (Right) Axial bone CT shows the thin lamina papyracea separating the ethmoid air cells from the orbits The sphenoid sinuses are separated by an intersinus septum Note internal carotid arteries adjacent to the sinuses 847 Diagnostic Imaging Head and Neck (Left) Sagittal CT reconstruction shows the sphenoethmoidal recess bounded anteriorly by the most posterior ethmoid air cell & posteriorly by the sphenoid sinus A retention cyst is seen in the sphenoid sinus (Right) Coronal bone CT shows the sphenopalatine foramen connecting the nasal cavity to the pterygopalatine fossa (PPF) The inferior orbital fissure extends from the PPF to the orbital apex Note the planum sphenoidale above the sphenoid sinuses (Left) Sagittal CT reconstruction shows the sphenoid sinus ostium along the anterior wall of the sphenoid sinus An agger nasi cell & the basal lamella are also seen (Right) Coronal bone CT shows the important structures around the sphenoid sinuses The vidian canals are noted along the sinus floors & the foramen rotundum is located laterally The optic nerves lie medial to the anterior clinoids & the cavernous sinuses lie laterally Congenital Lesions Nasolacrimal Duct Mucocele > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Congenital Lesions > Nasolacrimal Duct Mucocele Nasolacrimal Duct Mucocele Michelle A Michel, MD Key Facts Terminology Synonym: Congenital dacryocystocele Imaging 848 Diagnostic Imaging Head and Neck Well-defined, cystic, unilateral or bilateral medial canthal mass in contiguity with enlarged bony NLD in newborn Absent or minimal wall enhancement (unless infected) Coronal/sagittal reformatted images show contiguity of cyst at lacrimal sac with NLD and inferior meatus Top Differential Diagnoses Orbital dermoid and epidermoid Dacryocystocele, acquired Pathology Tears & mucus accumulate in nasolacrimal duct with imperforate Hasner membrane (distal duct obstruction) Clinical Issues Proximal lesion: Small, round, bluish, medial canthal mass identified at birth or shortly thereafter Distal lesion: Nasal airway obstruction with respiratory distress if bilateral Most common abnormality of infant lacrimal apparatus Diagnostic Checklist Cross-sectional imaging evaluates extent of lesion along lacrimal apparatus & excludes other sinonasal causes of respiratory distress in newborn (Left) Axial bone CT in an infant shows well-circumscribed, low-density masses at the levels of the inferior meatus bilaterally consistent with nasolacrimal duct mucoceles Note the position of the lesions relative to the inferior turbinates (Right) Coronal T2WI MR in the same patient shows hyperintense signal in the mucoceles, not only at the inferior nasolacrimal ducts , but also at the level of the lacrimal sacs (Left) Axial CECT in an infant demonstrates a cystic mass with an enhancing rim in the medial right orbit consistent with a mucocele There is associated enlarged lacrimal sac fossa Note the normal left lacrimal sac fossa (Right) Axial CECT in the same patient shows extension of the mucocele inferiorly to the level of the inferior meatus The lesion obstructs the right nasal cavity at that level 849 Diagnostic Imaging Head and Neck P.IV(1):9 TERMINOLOGY Abbreviations Nasolacrimal duct (NLD) mucocele Synonyms Congenital dacryocystocele Definitions Cystic dilatation of nasolacrimal apparatus secondary to proximal ± distal obstruction of NLD IMAGING General Features Best diagnostic clue Well-defined, cystic, unilateral or bilateral medial canthal mass in contiguity with enlarged bony NLD in newborn Location Anywhere from lacrimal sac to inferior aspect of NLD at inferior meatus Size Variable; 5-10 mm intranasal or medial orbital component CT Findings NECT Hypodense, thin-walled cyst medial canthus ± inferior meatus Cyst(s) communicate with enlarged NLD CECT Minimal wall enhancement (unless infected) MR Findings T1WI Hypointense, well-circumscribed mass at medial canthus ± inferior meatus T2WI Typically hyperintense due to fluid content T1WI C+ No or minimal wall enhancement around cyst Imaging Recommendations Best imaging tool Thin section axial bone CT Fast & ↓ need for sedation Rules out choanal atresia as cause of airway obstruction Protocol advice Coronal/sagittal reformats show contiguity of lacrimal sac cyst with large NLD in nasolacrimal canal & extension into inferior meatus DIFFERENTIAL DIAGNOSIS Orbital Dermoid and Epidermoid Lateral > medial canthus 50% fat density/intensity with thin rim enhancement ± calcification Dacryocystocele Acquired lacrimal sac cyst PATHOLOGY General Features Etiology Tears & mucus accumulate in nasolacrimal duct with imperforate Hasner membrane (distal duct obstruction) Nasolacrimal sac distension vs anatomic variation compresses proximal valve CLINICAL ISSUES Presentation Most common signs/symptoms Principal presentation (proximal lesion) Small, round, bluish, medial canthal mass identified at birth or shortly thereafter Principal presentation (distal lesion) Nasal airway obstruction with respiratory distress if bilateral 850 Diagnostic Imaging Head and Neck Submucosal nasal cavity mass at inferior meatus Other signs/symptoms Tearing, crusting at medial canthus Preseptal cellulitis Clinical profile Infant with medial canthal mass ± nasal cavity mass Demographics Age Infancy; days to 10 weeks typically Gender M < F = 1:3 Epidemiology Most common abnormality of infant lacrimal apparatus 3rd most common etiology in neonatal nasal obstruction 1st = mucosal edema, 2nd = choanal atresia Unilateral > bilateral Natural History & Prognosis 90% simple distal obstructions (congenital dacryostenosis) resolve spontaneously by age Intervention recommended before infection occurs to prevent nasal airway obstruction, dacryocystitis, & permanent sequelae DIAGNOSTIC CHECKLIST Consider Cross-sectional imaging evaluates extent of lesion along lacrimal apparatus & excludes other sinonasal causes of respiratory distress in newborn SELECTED REFERENCES Cavazza S et al: Congenital dacryocystocele: diagnosis and treatment Acta Otorhinolaryngol Ital 28(6):298-301, 2008 Wong RK et al: Presentation and management of congenital dacryocystocele Pediatrics 122(5):e1108-12, 2008 Rand PK et al: Congenital nasolacrimal mucoceles: CT evaluation Radiology 173(3):691-4, 1989 Choanal Atresia > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Congenital Lesions > Choanal Atresia Choanal Atresia Michelle A Michel, MD Key Facts Terminology Congenital obstruction of posterior nasal apertures Imaging Unilateral or bilateral narrowing of posterior nasal cavity with membranous or osseous obstruction of choana Thickening of vomer Medial bowing of posterior maxilla Top Differential Diagnoses Choanal stenosis Pyriform aperture stenosis Nasolacrimal duct mucocele Nasal foreign body Pathology Unilateral CAt 1.6-2x as common as bilateral Bony-osseous (85-90%) Membranous (10-15%) Clinical Issues Bilateral CAt: Respiratory distress in newborn Unilateral CAt or stenosis: Chronic, purulent unilateral rhinorrhea with mild breathing obstruction Most common congenital abnormality of nasal cavity Isolated finding (25%) Associated with other anomalies (75%) Diagnostic Checklist Respiratory distress & nasal obstruction in newborn should be evaluated with thin section bone CT 851 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a newborn with unilateral choanal atresia on the left There is a membranous atresia and fluid layers in the left nasal cavity Note the associated thickening of the vomer posteriorly (Right) Axial bone CT in an infant in respiratory distress with bilateral membranous choanal atresia Note the soft tissue and fluid in the nasal cavities and the medialization of the maxillae (lateral nasal walls) posteriorly (Left) Axial NECT shows typical findings of unilateral choanal atresia There is soft tissue within the left nasal cavity with apparent narrowing of the left choana The contralateral nasal cavity is unremarkable (Right) Axial bone CT in the same patient shows the bony stenosis of the left choanal opening to better advantage The narrow opening is occluded by a membranous plug of tissue P.IV(1):11 TERMINOLOGY Abbreviations Choanal atresia (CAt) Definitions Congenital obstruction of posterior nasal apertures IMAGING General Features Best diagnostic clue Unilateral or bilateral narrowing of posterior nasal cavity with membranous or osseous obstruction of choana Location Choanal openings: Posterior nasal cavity & nasopharyngeal junction 852 Diagnostic Imaging Head and Neck Size Choanal opening in newborn < 0.34 cm; vomer > 0.23 cm Morphology Medial bowing of posterior maxilla (lateral nasal walls) Thickened vomer Bone ± soft tissue membrane/plug obstructs choana CT Findings Bone CT Bony plate or soft tissue occludes choanal opening(s) Soft tissue in membranous atresia may be thin/strand-like or thick/plug-like Thickening of vomer, which may be fused to maxilla Medial bowing of posterior maxilla Nasal cavity filled with air, soft tissue, fluid, hypertrophied inferior turbinates Imaging Recommendations Best imaging tool High-resolution unenhanced bone CT Protocol advice Suction secretions from nasal cavity prior to scanning Perform supine with gantry angled 5° cephalad to palate High-resolution, edge enhancement bone filters helpful in delineating bone margins in partially ossified skull base Multiplanar reformations as needed Sagittal usually best plane for this 3D reconstructions may be helpful for clinical decision making & surgical planning DIFFERENTIAL DIAGNOSIS Choanal Stenosis More common than true CAt Part of spectrum of “choanal dysplasia” from stenosis to atresia Axial bone CT appearance Posterior nasal airway narrowed but not completely occluded Pyriform Aperture Stenosis Narrowed anterior nasal passage Axial bone CT appearance Narrowing of anterior & inferior nasal passage Thickened anteromedial maxilla Anterior nasal septum may be thinned Single central megaincisor may be present Brain evaluation for holoprosencephaly important Nasolacrimal Duct Mucocele Bilobed cystic masses in both nasolacrimal fossae & inferior meati Nasal Foreign Body Older patient with choanal stenosis or unilateral CAt PATHOLOGY General Features Etiology Pathogenesis remains elusive and unproven Failure of perforation of oronasal membrane (normally perforates by 7th week of gestation) Bony CAt: Incomplete canalization of choanae Membranous CAt: Incomplete resorption of epithelial plugs Molecular mechanisms in retinoic acid receptor development recently described in CAt pathogenesis Genetics Chromosomal abnormalities, single gene defects, deformations, and teratogens implicated Associated with chromosome 18, 12, 22, XO abnormalities Familial form exists Associated abnormalities Syndromic associations CHARGE syndrome 853 Diagnostic Imaging Head and Neck Coloboma, Heart defect, Choanal atresia, Retarded growth and development, Genitourinary abnormalities, Ear defects Choanal atresia in 100% of patients with CHARGE Acrocephalosyndactyly Amniotic band syndrome Apert syndrome Craniosynostosis Gut malrotations Crouzon disease Cornelia de Lange syndrome Fetal alcohol syndrome DiGeorge syndrome Treacher-Collins syndrome Unilateral CAt 1.6-2x as common as bilateral Staging, Grading, & Classification Choanal atresia types Bony-osseous (85-90%) Membranous (10-15%) Gross Pathologic & Surgical Features Membranous soft tissue or bony plate occludes choanal opening P.IV(1):12 CLINICAL ISSUES Presentation Most common signs/symptoms Bilateral choanal atresia: Respiratory distress in newborn Infants are obligate nasal breathers up to months of age Aggravated by feeding Relieved by crying Unilateral choanal atresia or stenosis: Chronic, purulent unilateral rhinorrhea with mild breathing obstruction Other signs/symptoms Inability to pass nasogastric tube through nasal cavity beyond 3-4 cm despite aerated lungs on plain film Nasal stuffiness Grunting, snorting, low-pitched stridor Clinical profile Bilateral: Infant with respiratory distress Unilateral: Child/young adult with unilateral purulent rhinorrhea Demographics Age Bilateral atresia presents at birth Unilateral choanal atresia/stenosis may present in child/young adult Gender Incidence in males and females statistically equal Epidemiology CAt or choanal stenosis: Most common congenital abnormality of nasal cavity 1:5,000 to 8,000 live births CAt in isolation (25%) Unilateral cases more likely to be isolated CAt associated with other anomalies (75%) Bilateral cases more likely associated with specific disorders or multiple anomalies Natural History & Prognosis Bilateral CAt Diagnosed and treated in newborn period Unilateral CAt Not life-threatening May present later in childhood Prognosis excellent after surgical therapy 854 Diagnostic Imaging Head and Neck Some patients prone to re-stenosis Treatment Establish oral airway immediately to ensure proper breathing Membranous atresias may be perforated upon passage of NG tube Surgical treatment believed to be effective for alleviating respiratory symptoms Best surgical approach, use of endoscopic/laser-assisted techniques, adjuvant use of stents Use of antiproliferative agents debated Endoscopic approaches frequently used for simple membranous & bony atresias Minimizes traumatic injury leading to scarring & restenosis Bilateral bony atresias require transpalatal resection of vomer with choanal reconstruction Postoperative scar & incomplete resection of atresia plate best evaluated with bone CT DIAGNOSTIC CHECKLIST Consider Once airway is established, respiratory distress & nasal obstruction in newborn should be evaluated with thin section bone CT Image Interpretation Pearls Determine whether CAt unilateral or bilateral Look for associated anomalies in head & neck Reporting Tips Describe CAt as membranous or bony; unilateral or bilateral Comment on thickness of bony atresia plate SELECTED REFERENCES Aslan S et al: Comparison of nasal region dimensions in bilateral choanal atresia patients and normal controls: a computed tomographic analysis with clinical implications Int J Pediatr Otorhinolaryngol 73(2):329-35, 2009 Burrow TA et al: Characterization of congenital anomalies in individuals with choanal atresia Arch Otolaryngol Head Neck Surg 135(6):543-7, 2009 Corrales CE et al: Choanal atresia: current concepts and controversies Curr Opin Otolaryngol Head Neck Surg Epub ahead of print, 2009 Hengerer AS et al: Choanal atresia: embryologic analysis and evolution of treatment, a 30-year experience Laryngoscope 118(5):862-6, 2008 Petkovska L et al: CT evaluation of congenital choanal atresia: our experience and review of the literature Australas Radiol 51(3):236-9, 2007 Uslu H et al: Bilateral choanal atresia; evaluation with scintigraphy: case report Int J Pediatr Otorhinolaryngol 70(1):171-3, 2006 Samadi DS et al: Choanal atresia: a twenty-year review of medical comorbidities and surgical outcomes Laryngoscope 113(2):254-8, 2003 Shah RK et al: Paranasal sinus development: a radiographic study Laryngoscope 113(2):205-9, 2003 Triglia JM et al: [Choanal atresia: therapeutic management and results in a series of 58 children] Rev Laryngol Otol Rhinol (Bord) 124(3):139-43, 2003 10 Holzmann D et al: Unilateral choanal atresia: surgical technique and long-term results J Laryngol Otol 116(8):6014, 2002 11 Faust RA et al: Assessment of congenital bony nasal obstruction by 3-dimensional CT volume rendering Int J Pediatr Otorhinolaryngol 61(1):71-5, 2001 12 Vanzieleghem BD et al: Imaging studies in the diagnostic workup of neonatal nasal obstruction J Comput Assist Tomogr 25(4):540-9, 2001 13 Behar PM et al: Paranasal sinus development and choanal atresia Arch Otolaryngol Head Neck Surg 126(2):155-7, 2000 14 Lowe LH et al: Midface anomalies in children Radiographics 20(4):907-22; quiz 1106-7, 1112, 2000 15 Hsu CY et al: Congenital choanal atresia: computed tomographic and clinical findings Acta Paediatr Taiwan 40(1):13-7, 1999 16 Black CM et al: Potential pitfalls in the work-up and diagnosis of choanal atresia AJNR Am J Neuroradiol 19(2):326-9, 1998 P.IV(1):13 Image Gallery 855 Diagnostic Imaging Head and Neck (Left) Axial NECT shows the typical features of unilateral choanal atresia Fluid layers in the posterior nasal cavity on the left are due to a bony atresia There is thickening of the vomer (Right) Axial 3D reformatted image in the same patient shows the bony choanal atresia on the left with a widely patent choanal opening on the right Three dimensional images can be very helpful to the referring clinicians for surgical planning (Left) Axial bone CT in a newborn with complex nasal anomalies shows bilateral CAt with aplasia of the right nasal cavity There are fluid layers in the left nasal cavity & thickening of the vomer posteriorly (Right) More inferior axial bone CT in the same patient shows fluid layering in the left nasal cavity anterior to the absent choanal opening Note the absent right nasal cavity with the septum apposed to the lateral nasal wall Incidental persistent craniopharyngeal canal is noted 856 Diagnostic Imaging Head and Neck (Left) Sagittal reformatted bone CT in the same patient shows the nonpatent left choanal opening and the layering fluid in the left nasal cavity Incidental craniopharyngeal canal is shown (Right) Axial bone CT shows a membranous, unilateral choanal atresia on the right side with layering fluid in the right nasal cavity There are typical associated features, including thickening of the vomer and medialization of the posterior maxilla Nasal Glioma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Congenital Lesions > Nasal Glioma Nasal Glioma Michelle A Michel, MD Key Facts Terminology Developmental mass of dysplastic neurogenic tissue sequestered & isolated from subarachnoid space “Glioma” is a misnomer as this is nonneoplastic tissue Extranasal glioma (ENG), intranasal glioma (ING) Imaging Well-circumscribed, soft tissue mass at superior nasal dorsum (ENG) or within nasal cavity (ING) with no connection to brain Multiplanar MR May show pedicle of fibrous tissue (not brain parenchyma) between ING & intracranial cavity Better than CT for differentiating NG from cephalocele or dermoid Gyral structure of gray matter rarely visible Commonly shows hyperintensity related to gliosis Top Differential Diagnoses Frontoethmoidal cephalocele Nasal dermal sinus Sinonasal solitary polyp Pathology Similar spectrum of congenital anomalies as frontoethmoidal cephaloceles Does not contain CSF contiguous with subarachnoid or intraventricular spaces Rarely associated with other brain or systemic anomalies Clinical Issues Usually identified at birth ENG: 60%, ING: 30%, other sites: 10% Treatment of choice is complete surgical resection 857 Diagnostic Imaging Head and Neck (Left) Sagittal graphic of a nasal glioma shows a mass of dysplastic glial tissue along the nasal dorsum Notice the absence of a connection to the intracranial contents (Right) Sagittal T1WI MR of a newborn demonstrates a large intranasal glioma filling the right nasal cavity No connection to the intracranial cavity by CSF-filled meninges or brain parenchyma is appreciated, helping to distinguish this lesion from an cephalocele (Left) Coronal NECT shows a well-defined, somewhat polypoid soft tissue mass , consistent with an intranasal glioma, within the left nasal cavity The nasal septum is slightly deviated toward the right No definite connection to the frontal lobe parenchyma is appreciated (Right) Axial CECT shows a left-sided intranasal glioma widening the anterior nasal vault P.IV(1):15 TERMINOLOGY Abbreviations Nasal glioma (NG) Extranasal glioma (ENG), intranasal glioma (ING) Synonyms Nasal cerebral heterotopia, glial heterotopia Definitions Developmental mass of dysplastic neurogenic tissue sequestered & isolated from subarachnoid space “Glioma” is misnomer as this is nonneoplastic tissue Best thought of as cephalocele without intracranial connection to brain IMAGING 858 Diagnostic Imaging Head and Neck General Features Best diagnostic clue Well-circumscribed, soft tissue mass at superior nasal dorsum (ENG) or within nasal cavity (ING) with no connection to brain Location Most occur at bridge of nose or in & around nasal cavity Usually off midline; right > left side ENG: Mass along nasal dorsum Glabella most frequent location ENG may also be found at medial canthus May be found in nasopharynx, mouth, pterygopalatine fossa (very rare) ING: Nasal cavity mass May be attached to concha of middle turbinate, nasal septum, or lateral nasal wall Other sites: Ethmoid sinus, palate, middle ear, tonsil, & pharynx Size 1-3 cm in diameter Morphology Well-circumscribed round, ovoid, or polypoid mass CT Findings NECT ENG: Well-circumscribed soft tissue attenuation mass (isodense to brain) located at glabella Superficial to point of fusion of frontal and nasal bones (fonticulus frontalis) Nasal bones may be thinned ING: Soft tissue attenuation mass within nasal cavity Typically high in nasal vault Fibrous pedicle may extend toward skull base but not intracranially Defect in cribriform plate (10-30%) Calcification rare CECT Typically no significant enhancement If intrathecal contrast used Fails to document connection of lesion to subarachnoid space MR Findings T1WI Predominantly mixed to low signal intensity mass Gyral structure of gray matter rarely visible T2WI Commonly shows hyperintensity related to gliosis No CSF around lesion connecting to subarachnoid space T1WI C+ Dysplastic tissue typically does not enhance “Perceived” enhancement at periphery of intranasal lesions may actually represent adjacent nasal mucosa Imaging Recommendations Best imaging tool Multiplanar MR May show pedicle of fibrous tissue (not brain parenchyma) between ING & intracranial cavity MR better than CT for differentiating NG from cephalocele or dermoid Avoids radiation to radiosensitive eye lenses in young patients Protocol advice Thin section sagittal T1 and T2 MR are important sequences Preoperative thin section axial bone CT with coronal reformatted images may also help in surgical planning Bone only without enhancement DIFFERENTIAL DIAGNOSIS Frontoethmoidal Cephalocele Frontonasal (FN) & nasoethmoidal (NE) cephaloceles Clinical: Congenital mass on or around bridge of nose (FN) or within nasal cavity (NE) Imaging: MR imaging shows connection to intracranial brain parenchyma 859 Diagnostic Imaging Head and Neck Nasal Dermal Sinus Clinical: Pit on tip or bridge of nose Imaging Associated dermoid or epidermoid along course from tip of nose to foramen cecum, anterior to crista galli Single or multiple Possible intracranial connection via sinus tract Sinonasal Solitary Polyps Clinical: Polyp is less firm, more translucent that ING Unusual < years Imaging Typically inferolateral to middle turbinate (ING medial) Homogeneous ↑ T2 MR signal with thin enhancement of peripheral mucosa Orbital Dermoid and Epidermoid Clinical: Focal mass in medial orbit near nasolacrimal suture Imaging Dermoid: Fluid or fat density/signal intensity Epidermoid: Fluid density/signal P.IV(1):16 PATHOLOGY General Features Etiology Dysplastic, heterotopic neuroglial & fibrous tissue separated from brain during development of anterior skull or anterior skull base Similar spectrum of congenital anomalies as frontoethmoidal cephaloceles but does not contain CSF and is not contiguous with subarachnoid or intraventricular spaces ENG: Fonticulus frontalis (potential space prior to fusion of frontal & nasal bones) fuses prior to regression of dural diverticulum Dysplastic parenchyma sequestered over nasal bones/nasofrontal suture ING: Prenasal space (potential space prior to fusion of nasal bones with cartilaginous nasal capsule) fuses prior to regression of dural diverticulum Dysplastic parenchyma sequestered in nasal cavity Associated abnormalities Rarely associated with other brain or systemic anomalies Gross Pathologic & Surgical Features Firm, smooth mass Rarely recognized as brain tissue at surgery 10-30% attached to brain by a stalk of fibrous tissue through defect in or near cribriform plate Mixed extra-intranasal lesions connect through defect in nasal bone Microscopic Features Fibrous or gemistocytic astrocytes & neuroglial fibers Fibrous, vascularized connective tissue & sparse neurons Glial fibrillary acidic protein (GFAP) & S100 protein positive No mitotic features or bizarre nuclear forms CLINICAL ISSUES Presentation Most common signs/symptoms Extranasal glioma Congenital subcutaneous blue or red mass along nasal dorsum (glabella) Usually nonprogressive midfacial swelling Intranasal glioma Firm, polypoid submucosal nasal cavity mass Nasal obstruction & septal deviation may be present May be confused clinically with nasal polyp Other signs/symptoms No change in size with crying, Valsalva, or pressure on jugular vein (vs frontoethmoidal cephalocele) ENG: Capillary telangiectasia may cover 860 Diagnostic Imaging Head and Neck ING: Respiratory distress; epiphora; may protrude through nostril Clinical profile Firm mass at glabella (ENG) or within nasal cavity (ING) in a newborn Demographics Age Identified at birth or within 1st few years of life Epidemiology Very rare lesion ENG: 60%, ING: 30%, other sites: 10% Natural History & Prognosis Grows slowly in proportion to adjacent tissue or brain if attached by pedicle May deform nasal skeleton, maxilla, or orbit May become infected, resulting in meningitis Complete resection is curative 10% recurrence rate with incomplete resection Treatment Treatment of choice is complete surgical resection ENG without intracranial connection removed via external incision with stalk dissection ING without intracranial connection may be removed endoscopically Less postoperative deformity than with craniotomy Rare mixed gliomas (extranasal & intranasal components) best treated with combined intranasal and extracranial approach DIAGNOSTIC CHECKLIST Consider Most important to differentiate NG from cephalocele Document lack of connecting brain tissue &/or contiguous CSF space Image Interpretation Pearls Must evaluate images for connection to intracranial cavity through skull base defect (cephalocele) Combined use of thin section MR & bone CT accomplishes this task Focus imaging to fronto-ethmoid area SELECTED REFERENCES Husein OF et al: Neuroglial heterotopia causing neonatal airway obstruction: presentation, management, and literature review Eur J Pediatr 167(12):1351-5, 2008 Riffaud L et al: Glial heterotopia of the face J Pediatr Surg 43(12):e1-3, 2008 De Biasio P et al: Prenatal diagnosis of a nasal glioma in the mid trimester Ultrasound Obstet Gynecol 27(5):571-3, 2006 Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging Pediatr Radiol 36(7):647-62; quiz 726-7, 2006 Khanna G et al: Causes of facial swelling in pediatric patients: correlation of clinical and radiologic findings Radiographics 26(1):157-71, 2006 Huisman TA et al: Developmental nasal midline masses in children: neuroradiological evaluation Eur Radiol 14(2):243-9, 2004 Belden CJ et al: The developing anterior skull base: CT appearance from birth to years of age AJNR Am J Neuroradiol 18(5):811-8, 1997 Barkovich AJ et al: Congenital nasal masses: CT and MR imaging features in 16 cases AJNR Am J Neuroradiol 12(1):105-16, 1991 P.IV(1):17 Image Gallery 861 Diagnostic Imaging Head and Neck (Left) Sagittal CECT demonstrates a mildly enhancing soft tissue lesion in the nasal cavity consistent with intranasal glioma No connection is identified with what appears to be normal foramen cecum in a child of this age (Right) Sagittal T1WI C+ MR in the same patient shows diffuse, slightly heterogeneous enhancement throughout the glioma (Left) Coronal FLAIR MR shows mixed signal intensity within an intranasal glioma There is no connection to the left frontal lobe to suggest that a cephalocele is present (Right) Axial T2WI MR shows a well-circumscribed intranasal glioma It is slightly heterogeneous but similar in signal intensity to the brain parenchyma No surrounding CSF can be seen around this glioma, a finding that is more indicative of an cephalocele 862 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ MR shows central enhancement within a large extranasal glioma The lesion is located slightly off the midline Enhancement is uncommon in these lesions (Right) Axial T1WI C+ MR shows a well-defined extranasal glioma along the dorsum of the nose in the midline, with diffuse enhancement throughout the lesion This degree of enhancement is a rare feature of nasal gliomas Nasal Dermal Sinus > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Congenital Lesions > Nasal Dermal Sinus Nasal Dermal Sinus Michelle A Michel, MD Key Facts Terminology Defective embryogenesis of anterior neuropore resulting in any mixture of dermoid cyst, epidermoid cyst, &/or sinus tract in frontonasal region Imaging Midline location anywhere from nasal tip to anterior skull base at foramen cecum CT Bifid crista galli with large foramen cecum Fluid attenuation tract (sinus)/cyst or fat containing mass (dermoid) from nasal dorsum to skull base within nasal septum MR Fluid signal tract in septum from nasal dorsum to skull base (sinus) Focal low signal (epidermoid) or high signal (dermoid) mass found between tip of nose & apex of crista galli Top Differential Diagnoses Fatty marrow in crista galli Nonossified foramen cecum Frontoethmoidal cephalocele Nasal glioma Pathology Intracranial extension of nasal dermal sinus in 20% Associated craniofacial anomalies in 15% Clinical Issues Nasoglabellar mass (30%) Pit on skin of nasal bridge at osteocartilaginous nasal junction ± protruding hair 863 Diagnostic Imaging Head and Neck (Left) Lateral graphic depicts a nasal dermal sinus with dermoids An extracranial dermoid is present just below a cutaneous nasal pit An intracranial dermoid splits a bifid crista galli (Right) Coronal bone CT demonstrates a nasal dermoid/epidermoid at the skull base The low attenuation midline mass causes remodeling of the adjacent bone at the margins of the foramen cecum (Left) Sagittal T2WI MR in a 3-year-old boy with a bump on the tip of the nose shows a hyperintense sinus tract extending from the anterior skull base into the nasal septum The features are characteristic of a dermal sinus (Right) Axial NECT demonstrates a low-attenuation dermoid centered in the cartilaginous portion of the nasal septum The mass is slightly higher in attenuation than adjacent fat P.IV(1):19 TERMINOLOGY Abbreviations Nasal dermal sinus (NDS) Synonyms Nasal dermoid, nasal dermal cyst, anterior neuropore anomaly Definitions Defective embryogenesis of anterior neuropore resulting in any mixture of dermoid cyst, epidermoid cyst, &/or sinus tract in frontonasal region IMAGING General Features Best diagnostic clue CT 864 Diagnostic Imaging Head and Neck Bifid crista galli with large foramen cecum Fluid attenuation tract (sinus)/cyst or fat-containing mass (dermoid) from nasal dorsum to skull base within nasal septum MR Fluid signal tract in septum from nasal dorsum to skull base (sinus) Focal low signal (epidermoid) or high signal (dermoid) mass found between tip of nose & apex of crista galli Location Midline lesion anywhere from nasal tip to anterior skull base at foramen cecum Size mm to cm dermoid/epidermoid Morphology Ovoid mass ± tubular sinus tract CT Findings Bone CT Focal tract (sinus) or mass (dermoid or epidermoid) anywhere from nasal bridge to crista galli Fluid-density tract = sinus Fluid-density mass = epidermoid Fat-density mass = dermoid Signs of intracranial extension Large foramen cecum with bifid or deformed crista galli or cribriform plate MR Findings T1WI ↓ signal tract = sinus ↑ signal mass = dermoid ↓ signal mass = epidermoid T2WI ↑ signal in sinus, epidermoid, or dermoid Coronal plane shows septal lesions to best advantage DWI ↑ signal = epidermoid Susceptibility artifacts at skull base may obscure signal from epidermoid Imaging Recommendations Best imaging tool MR more sensitive for delineating sinus tract & characterizing epidermoid/dermoid lesions and intracranial extension Bone CT optimal for identifying skull base defect & crista galli deformity Protocol advice Imaging “sweet spot” is small & anterior Focus imaging from tip of nose to back of crista galli Inferior end of axial imaging is hard palate Contrast does not help with diagnosis CT Thin section (1-2 mm) bone & soft tissue axial & coronal CT MR Sagittal plane displays course of sinus tract from nasal dorsum to skull base Fat-suppressed images confirm fat presence in dermoids DWI imaging important additional sequence DIFFERENTIAL DIAGNOSIS Fatty Marrow in Crista Galli No nasoglabellar mass or pit on nose CT & MR otherwise normal Nonossified Foramen Cecum Closes postnatally in 1st years of life Crista galli not deformed or bifid Frontoethmoidal Cephalocele Bone dehiscence is larger, involving a broader area of midline cribriform plate or frontal bone Direct extension of meninges, subarachnoid space ± brain can be seen projecting into cephalocele on sagittal MR Nasal Glioma 865 Diagnostic Imaging Head and Neck Solid mass of dysplastic glial tissue separated from brain by subarachnoid space & meninges Most commonly projects extranasally onto paramedian bridge of nose Less commonly along anterior nasal septum off midline PATHOLOGY General Features Etiology Anterior neuropore anomaly = general term for anomalous anterior neuropore regression; main types Nasal dermal sinus Nasal glioma Anterior cephalocele Embryology-anatomy: Development of anterior neuropore in 4th gestational week Dural stalk passes from area of future foramen cecum to area of osteocartilaginous nasal junction, then normally regresses completely Failure of involution may leave neuroectodermal remnants along tract of dural stalk Dermoid or epidermoid alone or in association with nasal dermal sinus tract results P.IV(1):20 Genetics Familial clustering Associated abnormalities Intracranial extension of nasal dermal sinus seen in 20% Craniofacial anomalies (15%) Gross Pathologic & Surgical Features Sinus = tube of tissue can be followed through bones Epidermoid = well-defined cyst; dermoid = lobular, well-defined mass Microscopic Features Sinus = midline epithelial-lined tract Epidermoid cyst contain desquamated epithelium Dermoid cyst contains epithelium, keratin debris, skin adnexa CLINICAL ISSUES Presentation Most common signs/symptoms Nasoglabellar mass (30%) Pit on skin of nasal bridge at osteocartilaginous nasal junction ± protruding hair Other signs/symptoms Intermittent sebaceous material discharge from pit < 50% have broadening nasal root & bridge If nasal sinus tract present, recurrent meningitis may occur (rare) Clinical profile Child (mean age = 32 months) with nasal pit ± nasoglabellar mass Rarely presents in adult population Episode of meningitis may be 1st problem leading to diagnosis Demographics Age Newborn to years old Gender Males with dermal sinus more likely to have intracranial extension Epidemiology Congenital midline nasal lesions are rare (1 in 20,000-40,000 births) Nasal dermoids are most common Natural History & Prognosis 1-time problem when surgical correction is successful Untreated patients have nasal bridge broadening ± recurrent meningitis Treatment 80% require extracranial excision only Local procedure to remove pit Any associated dermoid or epidermoid also simultaneously removed from nasal bridge Open rhinoplasty vs transnasal endoscopic excision 866 Diagnostic Imaging Head and Neck 20% undergo combined extracranial & intracranial resection Biorbitofrontal nasal craniotomy approach Dermoid or epidermoid along with involved dura crista galli removed Primary closure of surgical margins of dura completed DIAGNOSTIC CHECKLIST Consider Nasoglabellar mass or pit on nose sends clinician in search of NDS with intracranial extension Focused thin section MR imaging key to radiologic diagnosis Axial coverage from cephalad margin of crista galli to hard palate Coronal coverage from tip of nose to crista galli Add bone CT if NDS with intracranial extension found on MR Image Interpretation Pearls If dermal sinus tract reaches dura of anterior cranial fossa → crista galli will be bifid & foramen cecum large If foramen cecum large but crista galli is not bifid and tract is not seen → foramen cecum is normal & not yet closed Beware! Foramen cecum closes postnatally in 1st years of life Do not overcall a “large foramen cecum” or unnecessary craniotomy may result Repeat imaging in 6-12 months to confirm foramen cecum closure good approach in difficult cases SELECTED REFERENCES Holzmann D et al: Surgical approaches for nasal dermal sinus cysts Rhinology 45(1):31-5, 2007 Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging Pediatr Radiol 36(7):647-62; quiz 726-7, 2006 Zapata S et al: Nasal dermoids Curr Opin Otolaryngol Head Neck Surg 14(6):406-11, 2006 Huisman TA et al: Developmental nasal midline masses in children: neuroradiological evaluation Eur Radiol 14(2):243-9, 2004 Vaghela HM et al: Nasal dermoid sinus cysts in adults J Laryngol Otol 118(12):955-62, 2004 Rahbar R et al: The presentation and management of nasal dermoid: a 30-year experience Arch Otolaryngol Head Neck Surg 129(4):464-71, 2003 Bloom DC et al: Imaging and surgical approach of nasal dermoids Int J Pediatr Otorhinolaryngol 62(2):111-22, 2002 Lowe LH et al: Midface anomalies in children Radiographics 20(4):907-22; quiz 1106-7, 1112, 2000 Castillo M: Congenital abnormalities of the nose: CT and MR findings AJR Am J Roentgenol 162(5):1211-7, 1994 10 Posnick JC et al: Nasal dermoid sinus cysts: an unusual presentation, computed tomographic scan findings, and surgical results Ann Plast Surg 32(5):519-23, 1994 11 MacGregor FB et al: Nasal dermoids: the significance of a midline punctum Arch Dis Child 68(3):418-9, 1993 12 Barkovich AJ et al: Congenital nasal masses: CT and MR imaging features in 16 cases AJNR Am J Neuroradiol 12(1):105-16, 1991 13 Paller AS et al: Nasal midline masses in infants and children Dermoids, encephaloceles, and gliomas Arch Dermatol 127(3):362-6, 1991 14 Wardinsky TD et al: Nasal dermoid sinus cysts: association with intracranial extension and multiple malformations Cleft Palate Craniofac J 28(1):87-95, 1991 P.IV(1):21 Image Gallery 867 Diagnostic Imaging Head and Neck (Left) Axial NECT shows a well-circumscribed mass consistent with a dermoid at the nasal tip The mass is slightly higher in attenuation than adjacent fat Dermoids were also seen in the septum and at the foramen cecum in this patient (Right) Sagittal T1WI MR in the same patient again shows the dermoid at the nasal tip Additional dermoids are noted in the nasal septum and at the skull base (Left) Axial PD FSE MR shows the typical features of a nasal dermal sinus tract within the nasal septum The sinus in this infant extended from the skull base to the nasal tip (Right) Coronal bone CT demonstrates the typical appearance of a dermoid lesion within the nasal septum The lesion is well defined and low in attenuation 868 Diagnostic Imaging Head and Neck (Left) Sagittal T1WI MR demonstrates a well-defined, less than cm hyperintense lesion within the midline nasal septum, consistent with a dermoid or epidermoid cyst No additional lesions were identified from the skull base to the nasal tip (Right) Coronal T2WI MR in an infant demonstrates the typical features of a dermal sinus that extended from the anterior skull base through the nasal septum toward the nasal tip with an associated dermal cyst at the tip of the nose Frontoethmoidal Cephalocele > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Congenital Lesions > Frontoethmoidal Cephalocele Frontoethmoidal Cephalocele Michelle A Michel, MD Key Facts Terminology Congenital herniation of meninges, CSF ± brain tissue through mesodermal defect in anterior skull/skull base Imaging Heterogeneous, mixed density mass (variable amounts CSF & parenchyma) extending intracranially through bony defect Midline frontal: Frontonasal type (FNCeph) Intranasal: Nasoethmoidal type (NECeph) Inferomedial orbital: Nasoorbital type (NOCeph) Top Differential Diagnoses Nasal glioma Orbital dermoid and epidermoid Nasal dermal sinus Nasolacrimal duct mucocele Pathology FNCeph: Protrudes through unobliterated fonticulus frontalis NECeph: Protrudes through foramen cecum into prenasal space NOCeph: Protrudes into inferomedial orbit through defect in lacrimal/frontal process of maxillary bones Clinical Issues Intracranial abnormalities in ˜ 80% F = 67%, M = 33% Most common in Southeast Asians Diagnostic Checklist Sagittal & coronal T1 & T2 MR images are optimal for showing contiguity of mass with intracranial contents 869 Diagnostic Imaging Head and Neck (Left) Sagittal graphic of a frontonasal cephalocele shows herniation of brain through a patent fonticulus frontalis between the frontal bones above and nasal bones below (Right) Nasoethmoidal cephalocele is depicted in sagittal graphic Notice the herniation of brain tissue into the nasal cavity through a patent foramen cecum Also note the crista galli is positioned posterior to the skull base defect (Left) Sagittal T1WI MR in a newborn with a clinically apparent mass on the midline forehead shows a frontonasal cephalocele protruding through the unfused frontal and nasal bones (Right) Coronal T2WI MR shows the typical appearance of a nasoethmoidal cephalocele The gliotic brain parenchyma herniating into the nasal cavity is hyperintense The cephalocele herniates through a skull base defect to the right of midline P.IV(1):23 TERMINOLOGY Abbreviations Frontoethmoidal cephalocele (FECeph) Frontonasal cephalocele (FNCeph) Nasoethmoidal cephalocele (NECeph) Naso-orbital cephalocele (NOCeph) Synonyms Sincipital cephalocele Definitions Congenital herniation of meninges, CSF ± brain tissue through mesodermal defect in anterior skull/skull base presenting as extranasal, intranasal, or medial orbital mass IMAGING 870 Diagnostic Imaging Head and Neck General Features Best diagnostic clue Midline frontal (FNCeph), intranasal (NECeph), or medial orbital (NOCeph) soft tissue mass contiguous with intracranial brain parenchyma extending through bony defect Location FNCeph: Anterior forehead at glabella-dorsum of nose NECeph: Superomedial nasal cavity 90% terminate intracranially at single midline defect at foramen cecum 10% terminate intracranially at paired openings at anterior cribriform plates separated by midline bony bridge NOCeph: Inferomedial orbit Size Variable 1-2 cm to larger than infant head Morphology Well circumscribed, round, globular CT Findings NECT Heterogeneous, mixed density mass (variable amounts CSF & parenchyma) extending intracranially through bony defect Bone CT FNCeph: Frontal bones displaced superiorly while nasal bones, frontal processes of maxillae pushed inferiorly NECeph: Nasal bone bowed anteriorly with tract through anterior ethmoid area Crista galli may be bifid or absent Deficient or absent cribriform plate CT myelogram Intrathecal contrast: Fills subarachnoid space & surrounds soft tissue extending through bony defect MR Findings T1WI Soft tissue mass with isointense signal to gray matter showing contiguity with intracranial parenchyma extending through bony defect T2WI Hyperintense CSF surrounds herniated soft tissue parenchyma Tissue may show ↑ signal due to gliosis T1WI C+ No abnormal enhancement noted within soft tissue Meninges may enhance if infection/inflammation of meninges present Imaging Recommendations Best imaging tool MR superior to CT for cephalocele evaluation Differentiates CSF-filled meningocele and parenchymal components Superior for showing other associated brain anomalies Protocol advice Thin (3 mm) multiplanar T1 & T2 MR Sagittal & coronal planes optimal for visualizing parenchymal herniation through defects Bone CT can provide important information about skull defects for surgical planning DIFFERENTIAL DIAGNOSIS Nasal Glioma Clinical: Soft tissue mass along dorsum of nose (extranasal type) or under nasal bones (intranasal type) Imaging: MR shows no connection between mass in intracranial contents Orbital Dermoid and Epidermoid Clinical: Focal mass in medial orbit without associated tract Imaging: Fat density/intensity if dermoid; fluid density/intensity if epidermoid Nasal Dermal Sinus Clinical: Pit on tip or bridge of nose Imaging: Midline sinus from tip of nose to skull base Dermoid or epidermoid may be seen anywhere along tract Possible intracranial connection via sinus tract; does not contain brain parenchyma 871 Diagnostic Imaging Head and Neck Nasolacrimal Duct Mucocele Clinical: Small, round, bluish, medial canthal mass identified at birth with submucosal nasal cavity mass at inferior meatus Imaging: Nasolacrimal duct dilatation may be present to inferior meatus No connection to skull base or brain parenchyma PATHOLOGY General Features Etiology Prior to 8th week of gestation, potential spaces present Fonticulus frontalis: Between frontal, nasal bones Prenasal space: Between nasal bones, developing cartilaginous nasal septum P.IV(1):24 Anterior neuropore runs in prenasal space, communicating with anterior cranial fossa via foramen cecum Dural diverticulum protruding through defects may fail to regress FNCeph: Protrudes through unobliterated fonticulus frontalis NECeph: Protrudes through foramen cecum into prenasal space NOCeph: Protrudes into inferomedial orbit through defect in lacrimal/frontal process of maxillary bones Genetics Sporadic occurrence Not linked to neural tube defects like occipital cephaloceles Siblings have 6% incidence of congenital CNS abnormalities Associated abnormalities Intracranial abnormalities (˜ 80%) Callosal hypogenesis & interhemispheric lipomas Microcephaly Aqueductal stenosis & hydrocephalus Midline craniofacial dysraphisms & hypertelorism Staging, Grading, & Classification types of sincipital cephaloceles Frontonasal (FNCeph) Nasoethmoidal (NECeph) Naso-orbital (NOCeph) Gross Pathologic & Surgical Features Well-defined meningeal-lined mass containing CSF ± brain tissue Microscopic Features Meningoencephalocele: CSF, brain tissue & meninges Meningocele: Meninges & CSF only Atretic cephalocele: Forme fruste of cephalocele with dura, fibrous tissue, & degenerated brain tissue Gliocele: Glial-lined CSF-filled cyst CLINICAL ISSUES Presentation Most common signs/symptoms Externally visible, firm midline forehead (FNCeph), intranasal (NECeph), or medial orbital (NOCeph) mass Other signs/symptoms Hypertelorism & orbital dystropia Hyperpigmentation of overlying skin Change in size with crying, Valsalva, jugular compression Seizures & mental retardation < 50% Clinical profile Newborn with mass on forehead, within nasal cavity, or along medial orbital margin Demographics Age Congenital lesion detected on prenatal ultrasound or presenting at birth Gender F = 67%, M = 33% 872 Diagnostic Imaging Head and Neck Ethnicity FECeph most common in Southeast Asians Epidemiology Cephaloceles are uncommon in Western countries in 4,000-5,000 live births in Southeast Asia FECeph account for 15% of all cephaloceles FNCeph (50-61%), NECeph (30-33%), NOCeph (6-10%) Natural History & Prognosis Present at birth; require surgical repair If untreated, may grow with child When CSF filled, may increase rapidly in size Hydrocephalus and presence of intracranial abnormalities are predictors of developmental delay/poor outcome Treatment Biopsy contraindicated: CSF leak, seizures, meningitis Complete surgical resection Combined plastic surgery & neurosurgery Herniated brain tissue is dysfunctional (no neuro deficits result) Meningeal & skull base defect repaired or CSF leak, meningitis, or recurrent herniation may result DIAGNOSTIC CHECKLIST Consider Sagittal & coronal T1 & T2 MR images are optimal for showing contiguity of mass with intracranial contents Bone CT used to evaluate size & location of bony defect prior to surgical repair Image Interpretation Pearls Determine location of lesion relative to nasal bones Above is FNCeph, below is NECeph Evaluate brain for presence of associated intracranial anomalies SELECTED REFERENCES Kumar A et al: Correction of frontonasoethmoidal encephalocele: the HULA procedure Plast Reconstr Surg 123(2):661-9, 2009 Arshad AR et al: Frontoethmoidal encephalocele: treatment and outcome J Craniofac Surg 19(1):175-83, 2008 Lo BW et al: Clinical predictors of developmental outcome in patients with cephaloceles J Neurosurg Pediatr 2(4):254-7, 2008 Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging Pediatr Radiol 36(7):647-62; quiz 726-7, 2006 Rahbar R et al: Nasal glioma and encephalocele: diagnosis and management Laryngoscope 113(12):2069-77, 2003 Rojvachiranonda N et al: Frontoethmoidal encephalomeningocele: new morphological findings and a new classification J Craniofac Surg 14(6):847-58, 2003 Lowe LH et al: Midface anomalies in children Radiographics 20(4):907-22; quiz 1106-7, 1112, 2000 Fitzpatrick E et al: Congenital midline nasal masses: dermoids, gliomas, and encephaloceles J La State Med Soc 148(3):93-6, 1996 Turgut M et al: Congenital nasal encephalocele: a review of 35 cases J Craniomaxillofac Surg 23(1):1-5, 1995 10 Barkovich AJ et al: Congenital nasal masses: CT and MR imaging features in 16 cases AJNR Am J Neuroradiol 12(1):105-16, 1991 P.IV(1):25 Image Gallery 873 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a newborn with a soft tissue mass in the midline of the forehead shows a large anterior skull defect through which a large frontonasal cephalocele protrudes (Right) Frontal projection 3D surface rendered CT in the same patient shows the clinical appearance of the large cephalocele between the eyes This frontonasal cephalocele protrudes through a patent fonticulus frontalis (Left) Coronal NECT shows a low-density mass in the left nasal cavity in a patient with a nasoethmoidal cephalocele The small defect in the skull base is somewhat difficult to appreciate on this soft tissue window image (Right) Sagittal T2WI FS MR in the same patient shows predominantly CSF signal intensity within the lesion No definite brain parenchyma is seen within the cephalocele on this image 874 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a 17 month old shows an expansile lesion in the superior nasal cavity and ethmoid region consistent with a nasoethmoidal-type cephalocele A large skull base defect was noted on coronal images (not shown) (Right) Sagittal T2WI FS MR in the same patient shows herniation of brain parenchyma and meninges through the defect in the anterior skull base in this case of a nasoethmoidal cephalocele Congenital Nasal Pyriform Aperture Stenosis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Congenital Lesions > Congenital Nasal Pyriform Aperture Stenosis Congenital Nasal Pyriform Aperture Stenosis Michelle A Michel, MD Key Facts Terminology Congenital narrowing of anterior bony nasal passageway Imaging Best tool: Bone CT in axial & coronal planes Medial deviation of anterior maxillae ± thickening of nasal processes Abnormal maxillary dentition: SMMCI (75%) Triangle-shaped palate Top Differential Diagnoses Nasolacrimal duct mucoceles Nasal choanal stenosis/atresia Pathology CNPAS without solitary central incisor almost always isolated anomaly Solitary maxillary central incisor in 75% of cases Associated with holoprosencephaly Clinical Issues Respiratory distress in newborn/infant Can mimic choanal atresia/stenosis Breathing problems may be triggered by URI Symptoms may be more pronounced with feeding CNPAS 1/5 to 1/3 as common as choanal atresia Nasal cavity eventually grows & obstruction is relieved Diagnostic Checklist Bone CT recommended for diagnosis or bony narrowing & dental abnormalities Brain MR recommended in cases of SMMCI to exclude midline brain anomalies 875 , Diagnostic Imaging Head and Neck (Left) Axial bone CT in a newborn shows the typical features of congenital nasal pyriform aperture stenosis There is overgrowth of the anterior maxillae with marked narrowing of the anterior nasal passages There is no associated choanal atresia (Right) Axial bone CT at the level of the palate in the same patient shows a classic associated finding in patients with pyriform aperture stenosis, a solitary median maxillary central incisor or “megaincisor” (Left) Axial bone CT in a newborn with respiratory distress demonstrates bilateral congenital nasal pyriform aperture stenosis The anterior and medial aspects of the maxillae are thickened causing the narrowing of the anterior nasal airway (Right) Coronal bone CT in the same patient demonstrates the narrowing of the anterior nasal airway bilaterally and the associated solitary maxillary central incisor P.IV(1):27 TERMINOLOGY Abbreviations Congenital nasal pyriform aperture stenosis (CNPAS) Definitions Congenital narrowing of anterior bony nasal passageway IMAGING General Features Best diagnostic clue Medialization and thickening of anterior maxillae with narrowing of nasal airway Location Most often bilateral Size 876 Diagnostic Imaging Head and Neck Pyriform aperture size in CNPAS PA width = 4.8-7.0 mm (13.4-15.6 mm is normal); < 11 mm in term infant diagnostic PA area = 0.2-0.4 cm2 (0.7-1.1 cm2 is normal) Imaging Recommendations Best imaging tool Bone CT in axial & coronal planes CT Findings Bone CT Narrowed bony nasal inlet Medial deviation of lateral wall of PA (anterior maxillae) ± thickening of nasal processes Triangle-shaped palate Bony ridge along oral surface of hard palate on coronal images Abnormal maxillary dentition may occur Fused or malaligned central & lateral incisors Solitary median maxillary central incisor (SMMCI) syndrome (75%) Posterior choanae normal in caliber DIFFERENTIAL DIAGNOSIS Nasolacrimal Duct Mucocele Obstruction of distal nasolacrimal ducts results in cysts at inferior meati that narrow anterior nasal cavity Cysts may rupture with nasogastric tube passage, relieving obstruction Bony aperture is normal Nasal Choanal Atresia Narrowing of posterior nasal passage by membrane or bone Anterior nasal passage normal in caliber PATHOLOGY General Features Etiology theories of pathogenesis Deficiency of primary palate derived from midline mesodermal tissue Embryologically, medial maxillary swelling forms structures of primary palate, including incisors Mesoderm thought to have inductive effect on forebrain, hence association of central megaincisor with holoprosencephaly Overgrowth or dysplasia of nasal processes of maxilla CNPAS without solitary central incisor almost is always isolated anomaly Associated abnormalities Upper teeth anomalies SMMCI syndrome (75% of CNPAS cases) Semilobar or alobar holoprosencephaly Endocrine dysfunction: Pituitary-adrenal axis CLINICAL ISSUES Presentation Most common signs/symptoms Respiratory distress Can mimic choanal atresia/stenosis Breathing problems may be triggered by upper respiratory infection further compromising narrowed airway Cyanosis Other signs/symptoms Symptoms may be more pronounced with feeding Nasogastric tube difficult to pass Demographics Age Newborns or infants in 1st few months of life Epidemiology Congenital airway obstruction affects in 5,000 infants CNPAS 1/5 to 1/3 as common as choanal atresia Natural History & Prognosis Excellent prognosis 877 Diagnostic Imaging Head and Neck Nasal cavity eventually grows & obstruction is relieved Treatment May be treated conservatively with special feeding techniques Surgical intervention in patients with persistent respiratory difficulty & poor weight gain DIAGNOSTIC CHECKLIST Image Interpretation Pearls Brain MR recommended in cases of solitary maxillary central incisor to exclude midline brain anomalies SELECTED REFERENCES Osovsky M et al: Congenital pyriform aperture stenosis Pediatr Radiol 37(1):97-9, 2007 Belden CJ et al: CT features of congenital nasal piriform aperture stenosis: initial experience Radiology 213(2):495501, 1999 Bignault A et al: Congenital nasal piriform aperture stenosis AJNR Am J Neuroradiol 15(5):877-8, 1994 Infectious and Inflammatory Lesions Acute Rhinosinusitis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Acute Rhinosinusitis Acute Rhinosinusitis Michelle A Michel, MD Key Facts Terminology Acute inflammation sinonasal mucosa lasting ≤ weeks Imaging ARS is clinical diagnosis Most common in ethmoid & maxillary sinuses CT: Confirms diagnosis; evaluates patients not responding to medical therapy; delineates anatomic variants Axial ≤ mm slice thickness with coronal & sagittal reconstructions Best sign: Air-fluid level ± bubbly or strandy-appearing secretions within sinus with mucosal thickening MR: Useful to evaluate for orbital or intracranial complications, fungal disease, neoplasm Top Differential Diagnoses “Pseudo” fluid level Post-traumatic blood level Postobstructive secretions Pathology Most cases follow viral upper respiratory infection (URI) May be caused by vasomotor dysfunction, associated with allergy, odontogenic disease, or barotrauma Predisposing systemic disorders: Allergies, immunoglobulin deficiency, immotile cilia syndrome, cystic fibrosis Clinical Issues Rhinosinusitis affects nearly 31 million in USA annually 878 Diagnostic Imaging Head and Neck (Left) Coronal bone CT in a patient with symptoms of acute rhinosinusitis shows bilateral maxillary sinus air-fluid levels with bubbly-appearing secretions on the right Note mucosal thickening occluding the left ethmoid infundibulum (Right) Coronal bone CT shows an air-fluid level in the left maxillary sinus in a patient with rhinorrhea and facial pain Note the lucency around the roots of a molar tooth with dehiscence of bone in this case of odontogenic sinusitis (Left) Axial T2WI MR shows thickened, edematous mucosa circumferentially in both maxillary sinuses Strandy mucosal secretions are noted on the right (Right) Axial T1WI C+ MR in the same patient demonstrates thin, linear enhancement of the inflamed mucosa No solid soft tissue enhancement is present that could be confused with neoplasm P.IV(1):29 TERMINOLOGY Abbreviations Acute rhinosinusitis (ARS) Acute bacterial rhinosinusitis (ABRS) Definitions Acute inflammatory process of sinonasal mucosa lasting ≤ weeks IMAGING General Features Best diagnostic clue Air-fluid level ± bubbly or strandy-appearing secretions within sinus with mucosal thickening Location Most common in ethmoid & maxillary sinuses Allergic sinusitis tends to be generalized ABRS affects sinuses asymmetrically Size Normal sinus lumen size No expansion (mucocele) or reduced volume (chronic rhinosinusitis) Radiographic Findings Radiography Mucosal thickening or opacification of sinus Air-fluid level in maxillary sinus Can be difficult to identify in other sinuses CT Findings CECT Enhancement of inflamed mucosa Central secretions not enhance Bone CT Air-fluid level, bubbly or strandy-appearing secretions Mucosal thickening 879 Diagnostic Imaging Head and Neck Inflammatory tissue obstructing drainage pathways of ostiomeatal complex (OMC) MR Findings T1WI Mucosal thickening isointense to other soft tissue Fluid signal layering within sinus ↑ signal with elevated protein content Air, cortical bone appear as signal voids T2WI ↑ signal fluid & edematous mucosa Secretions ↓ in signal with ↑ protein content/inspissation T1WI C+ Enhancement of inflamed peripheral mucosa Central secretions not enhance Imaging Recommendations Best imaging tool ARS is clinical diagnosis Radiographs inaccurate in assessing extent of inflammation Particularly in ethmoid, frontal, & sphenoid sinuses CT: Confirms diagnosis Evaluates patients not responding to medical therapy Delineates anatomic variants MR: Useful to evaluate for orbital or intracranial complications, fungal disease, neoplasm Protocol advice Bone CT Axial ≤ mm slice thickness with coronal, sagittal reconstructions to evaluate OMC and frontal recess, respectively Axial plane useful for evaluating sphenoid & posterior ethmoid regions, posterior wall of frontal sinus MR mm thick T1, T2, STIR sequences; axial & coronal planes Use fat suppression post-contrast DIFFERENTIAL DIAGNOSIS “Pseudo” Fluid Level Flaccid mucus retention cyst (MRC) mimics air-fluid level Fluid level not persistent through entire sinus; rounded edge usually found Post-Traumatic Blood Level Clinical history of recent facial injury Increased attenuation of layering fluid (blood) Associated sinus wall fractures Postobstructive Secretions Lesion obstructs sinus drainage pathway, trapping fluid MR differentiates tumor from obstructed secretions PATHOLOGY General Features Etiology Most cases of ARS follow viral upper respiratory infection (URI) URI mucosal swelling sinus outflow obstruction infection Symptoms > 10 days or worsening after 5-7 days suggest bacterial superinfection May be caused by vasomotor dysfunction or associated with allergy or barotrauma Other important cause: Odontogenic sinusitis (erosion of dental periapical granuloma or abscess into sinus) Genetics Cystic fibrosis (autosomal recessive disorder) predisposes to rhinosinusitis Associated abnormalities Structural abnormalities may narrow drainage pathways Anatomic variants of septum, uncinate process, middle turbinate, frontal recess, ethmoid sinuses Benign or malignant neoplasms 880 Diagnostic Imaging Head and Neck Predisposing systemic disorders: Allergies, immunoglobulin deficiency, immotile cilia syndrome, cystic fibrosis P.IV(1):30 Staging, Grading, & Classification Can be classified according to etiology: Viral, bacterial, vasomotor Gross Pathologic & Surgical Features Edematous, erythematous mucosa with ostial obstruction, purulent secretions Microscopic Features Tissue-invasive bacteria Luminal exudate of neutrophils, eosinophils CLINICAL ISSUES Presentation Most common signs/symptoms Symptoms: Nasal congestion & purulent discharge, facial pain/pressure, headache, olfactory dysfunction, fever, cough Signs: Facial swelling & erythema, nasal turbinate edema, nasal crusting, purulent nasal cavity/pharynx Other signs/symptoms Maxillary: Infraorbital, cheek, upper teeth, or gum pain Ethmoid: Lacrimal, periorbital, or temporal region tenderness Frontal: Headache localized to forehead, supraorbital region Sphenoid: Pain radiates to occiput ± skull vertex; infection near cavernous sinus may cause CN2-4, V1, V2, or CN6 dysfunction Clinical profile Pediatric or adult patient with nasal discharge & obstruction frequently following viral URI; lasting ≤ weeks Laboratory results Nasal cultures nonspecific, often contaminated with S aureus Endoscopic paranasal sinus aspiration more specific Demographics Age Typically follows viral URI in children Epidemiology Sinonasal inflammatory disease is ubiquitous 90% of patients with common cold have viral or bacterial RS Rhinosinusitis affects nearly 31 million patients in USA annually > billion physician office visits of viral & bacterial RS annually in USA Natural History & Prognosis Usually self limited if viral ABRS course may be shortened by medical therapy, surgical drainage If untreated, ABRS complications ensue Orbital cellulitis, subperiosteal abscess, meningitis, subdural empyema, brain abscess, venous sinus thrombosis Treatment Medical therapy Saline nasal sprays & irrigants, mucolytics Decongestants, antihistamines, antibiotics (amoxicillin) Topical steroids Surgical therapy More often performed for chronic RS Drainage procedures performed in acute disease (frontal and sphenoid) to prevent development of complications DIAGNOSTIC CHECKLIST Consider Bone CT to confirm diagnosis if in doubt & determine extent Use ≤ mm axial slices with coronal and sagittal reformations CT limitations Cannot differentiate viral from bacterial disease 881 Diagnostic Imaging Head and Neck High incidence of sinus mucosal abnormalities in asymptomatic patients Image Interpretation Pearls Fluid levels are most specific indicator in absence of recent nasal lavage or presence of NG tube Normal nasal mucosal cycle may be impossible to distinguish from ARS mucosal thickening on MR Look for signs of invasive fungal sinusitis if immunocompromised patient SELECTED REFERENCES Bayonne E et al: Intracranial complications of rhinosinusitis A review, typical imaging data and algorithm of management Rhinology 47(1):59-65, 2009 Madani G et al: Sinonasal inflammatory disease Semin Ultrasound CT MR 30(1):17-24, 2009 Saarakkala S et al: Comprehensive optimization process of paranasal sinus radiography Acta Radiol 2009 Apr;50(3):327-33 Erratum in: Acta Radiol 50(5):575, 2009 Pearlman AN et al: Review of current guidelines related to the diagnosis and treatment of rhinosinusitis Curr Opin Otolaryngol Head Neck Surg 16(3):226-30, 2008 Rosenfeld RM et al: Clinical practice guideline: adult sinusitis Otolaryngol Head Neck Surg 137(3 Suppl):S1-31, 2007 Triulzi F et al: Imaging techniques in the diagnosis and management of rhinosinusitis in children Pediatr Allergy Immunol 18 Suppl 18:46-9, 2007 Le Annie V et al: Making the call: the diagnosis of acute community-acquired bacterial sinusitis Am J Rhinol 20(6):658-61, 2006 Mafee MF et al: Imaging of rhinosinusitis and its complications: plain film, CT, and MRI Clin Rev Allergy Immunol 30(3):165-86, 2006 Anand VK: Epidemiology and economic impact of rhinosinusitis Ann Otol Rhinol Laryngol Suppl 193:3-5, 2004 10 Piccirillo JF: Clinical practice Acute bacterial sinusitis N Engl J Med 351(9):902-10, 2004 11 Vázquez E et al: Complicated acute pediatric bacterial sinusitis: Imaging updated approach Curr Probl Diagn Radiol 33(3):127-45, 2004 12 Zinreich SJ: Imaging for staging of rhinosinusitis Ann Otol Rhinol Laryngol Suppl 193:19-23, 2004 13 Kenny TJ et al: Prospective analysis of sinus symptoms and correlation with paranasal computed tomography scan Otolaryngol Head Neck Surg 125(1):40-3, 2001 P.IV(1):31 Image Gallery (Left) Coronal bone CT shows findings consistent with acute bilateral maxillary sinusitis Air-fluid levels and mucosal thickening bilaterally are seen Additional mucosal thickening is seen throughout the ethmoid sinuses (Right) Coronal bone CT shows an air-fluid level in the left sphenoid sinus consistent with acute inflammatory disease Mucosal thickening in the sphenoethmoidal recess and posterior nasal cavity is likely contributed to the sphenoid disease 882 Diagnostic Imaging Head and Neck (Left) Coronal T1WI C+ MR shows the typical features of maxillary sinusitis There is lobular mucosal thickening at the periphery of the right maxillary sinus that enhances avidly Trapped fluid is noted centrally within the sinus (Right) Coronal bone CT in a patient with bilateral maxillary sinusitis shows an air-fluid level on the right and mucosal thickening on the left The maxillary ostia are occluded bilaterally (Left) Coronal bone CT in a patient with symptoms of acute sinusitis shows bilateral maxillary air-fluid levels The left infundibulum is occluded by mucosal thickening Incidental note is made of a left concha bullosa This anatomic variant slightly narrows the left middle meatus (Right) Coronal bone CT in a patient with acute sphenoiditis demonstrates large left and smaller right sphenoid sinus air-fluid levels Chronic Rhinosinusitis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Chronic Rhinosinusitis Chronic Rhinosinusitis Michelle A Michel, MD Key Facts Terminology Group of disorders characterized by inflammation of nose & sinuses ≥ 12 consecutive weeks duration Imaging Bone CT is modality of choice Mucosal thickening or soft tissue opacification with thickening & sclerosis of bony walls Involved sinus normal or ↓ volume 883 Diagnostic Imaging Head and Neck Top Differential Diagnoses Fungal mycetoma Allergic fungal sinusitis Sinonasal polyposis Wegener granulomatosis Sarcoidosis Pathology Causes of CRS are numerous, disparate, & frequently overlapping Many factors & processes play a role in etiology of CRS Clinical Issues Often associated conditions, such as allergy, underlying anatomic variations Diagnostic Checklist Coronal sinus CT is study of choice for evaluating changes in bone & identifying anatomic variants that may predispose to recurrent disease There is lack of correlation between symptomatology & imaging findings (Left) Coronal bone CT shows findings of chronic left maxillary sinusitis The sinus is opacified, and there is thickening of the lateral sinus wall compared to the right side Mucosal thickening is also noted in other sinuses (Right) Axial bone CT in a cystic fibrosis patient shows bilateral maxillary sinus mucosal thickening with thickening of the sinus walls (osteitis) , consistent with chronic inflammatory disease (Left) Axial bone CT demonstrates marked chronic osteitis of the walls of both maxillary sinuses The volume of the sinuses is diminished, and there is patchy mucosal thickening Changes are noted from prior surgery with antrostomy defects (Right) Coronal bone CT in a patient with longstanding right maxillary inflammation shows prominent 884 Diagnostic Imaging Head and Neck calcifications P.IV(1):33 within the inspissated right maxillary sinus secretions Osteitis of the walls of the sinus is also present TERMINOLOGY Abbreviations Chronic rhinosinusitis (CRS) Synonyms Rhinosinusitis (RS) Definitions CRS: Group of disorders characterized by inflammation of nose & sinuses ≥ 12 consecutive weeks duration IMAGING General Features Best diagnostic clue Mucosal thickening or soft tissue opacification with thickening & sclerosis of bony walls Location Ethmoid sinus > maxillary sinus > frontal & sphenoid sinuses Size Involved sinus normal or ↓ volume No sinus expansion Morphology Normal morphology or concavity of walls (↓ sinus volume) Radiographic Findings Radiography Peripheral soft tissue thickening or opacification of sinus Sclerotic, thickened sinus walls Helpful for confirming diagnosis in symptomatic patients with equivocal physical exam findings Low sensitivity & specificity CT Findings CECT Enhancement of inflamed mucosa may be seen Contrast administration not necessary Bone CT Mucosal thickening or opacification of sinus without expansion of sinus Variable density of secretions Isodense to hyperdense depending on protein, water, fungal content Occasional calcification may be present Bony walls of sinus thickened & sclerotic MR Findings T1WI Thickened mucosa isointense to other soft tissue Variable signal of retained secretions depending on variable water & protein content ↑ protein:water ↑ T1 signal Bone thickening & sclerosis difficult to see with MR T2WI Mucosa typically hyperintense Retained secretions range from hyperintense (↑ water content) to hypointense (↓ water, desiccated) Thickened sinus walls evident on T2 MR T1WI C+ Mucosal enhancement typical Contrast administration not necessary Imaging Recommendations Best imaging tool Thin section axial bone CT with coronal reformatted images CT detects luminal sinus disease beyond what is seen endoscopically Protocol advice 1-1.25 mm thick axial CT in bone algorithm with coronal ± sagittal reformatted images 885 Diagnostic Imaging Head and Neck DIFFERENTIAL DIAGNOSIS Fungal Sinusitis, Mycetoma Sinus opacified Calcifications common Often seen in clinical setting of CRS Bony changes may mimic CRS Allergic Fungal Sinusitis Form of CRS in patients with asthma, allergy Involved sinuses opacified and expanded with central high-attenuation material Sinonasal Polyposis Multiple, variable density polypoid soft tissue masses in nasal cavity & sinuses Expansion, remodeling of bony walls may be present Acute Rhinosinusitis Clinical course of shorter duration often following viral URI Air-fluid levels & bubbly secretions in addition to mucosal thickening No bone changes Sinonasal Wegener Granulomatosis Nodular soft tissue thickening ± bone erosion Tends to affect nasal cavity > sinuses Involves septum and turbinates Sinonasal Sarcoidosis Nodular soft tissue thickening ± bone erosion Sinonasal involvement less common than Wegener Predilection for nasal cavity with septal involvement Turbinate involvement similar to Wegener PATHOLOGY General Features Etiology Unified understanding is still being sought Causes of CRS are numerous, disparate, & frequently overlapping Inflammation plays greater role than infection Biofilms (antibiotic resistant bacterial colonies) decrease antibiotic efficacy and release inflammatory mediators Many factors & processes play a role in etiology of CRS Systemic host factors: Allergic, immunodeficiency, genetic/congenital, mucociliary dysfunction, endocrine, neuromechanism P.IV(1):34 Local host factors: Anatomic variants, neoplastic, acquired mucociliary dysfunction Environmental: Microorganisms, noxious chemicals, medications, trauma, surgery Genetics Sporadic disease in most cases Genetics play role when underlying systemic disorder present Cystic fibrosis, primary ciliary dysmotility, immunodeficiency Associated abnormalities Asthma, allergy (> 50% of CRS patients) Dental disease (maxillary) Sinonasal polyposis Staging, Grading, & Classification Rhinosinusitis: clinical categories Acute, subacute, chronic, recurrent acute, acute exacerbation of CRS CRS may be bacterial, allergic, or fungal in nature Bacterial CRS Bacteria may initiate CRS, cause disease persistence, or exacerbate noninfectious inflammation Common organisms: Staphylococcus aureus, coag-negative Staphylococcus, anaerobic & gramnegative bacteria Allergic CRS 886 Diagnostic Imaging Head and Neck Cytokines & allergic mediators → nasal allergic inflammation → mucosal swelling → obstruction of ostia Allergic fungal sinusitis (AFS) Inflammatory response to presence of noninvasive fungal elements Gross Pathologic & Surgical Features Mucosal swelling, purulent discharge, polypoid changes, erythema Microscopic Features Mixed inflammatory infiltrate of lymphocytes, plasma cells, eosinophils, interleukin-8, and interferon-γ Changes in adjacent bone similar to osteomyelitis CLINICAL ISSUES Presentation Most common signs/symptoms Nasal obstruction, nasal discharge, hyposmia, anosmia Other signs/symptoms Facial pain & pressure, headache CRS definition: Sinonasal infection/inflammation > 12 weeks duration Nasal endoscopy & CT performed to quantify mucosal disease and target culturing Demographics Age All ages affected Epidemiology CRS results in 18-22 million office visits in USA annually Prevalence of CRS difficult to determine due to heterogeneity of disease & diagnostic imprecision Natural History & Prognosis Persistent, recurrent sinusitis often refractory to medical therapy Often associated conditions, such as allergy, underlying anatomic variations Patients with mucosal eosinophilia have poorer outcomes Nasal endoscopy best objective indicator of early recurrent disease Treatment Pharmacologic therapy: Antibiotics, antifungals, decongestants, antihistamines, topical steroids (allergic cases) Treatment of co-morbid conditions (inhalant sensitivities, polyps, infections, immune deficiencies) critical for treatment success of CRS Surgery reserved for cases recalcitrant to medical therapy Functional endoscopic sinus surgery (FESS) current surgical treatment of choice External approaches/sinus obliteration (frontal) reserved for cases of FESS failure or where FESS cannot be performed due to anatomic considerations DIAGNOSTIC CHECKLIST Consider Coronal sinus CT images study of choice in CRS Evaluates changes in bone & identifies anatomic variants that may predispose to recurrent disease Image Interpretation Pearls Mucosal thickening or opacification in nonexpanded sinus with associated bone thickening/sclerosis most consistent with CRS CT yields little information about etiology of mucosal changes Note: There is lack of correlation between symptomatology & imaging findings SELECTED REFERENCES Nair S: Correlation between symptoms and radiological findings in patients of chronic rhinosinusitis: a modified radiological typing system Rhinology 47(2):181-6, 2009 Smith WM et al: Regional variations in chronic rhinosinusitis, 2003-2006 Otolaryngol Head Neck Surg 141(3):34752, 2009 Bhattacharyya N: Relationship between mucosal inflammation, computed tomography, and symptomatology in chronic rhinosinusitis without polyposis Ann Otol Rhinol Laryngol 117(7):517-22, 2008 Bhattacharyya N et al: The accuracy of computed tomography in the diagnosis of chronic rhinosinusitis Laryngoscope 113(1):125-9, 2003 Hwang PH et al: Radiologic correlates of symptom-based diagnostic criteria for chronic rhinosinusitis Otolaryngol Head Neck Surg 128(4):489-96, 2003 Emanuel IA et al: Chronic rhinosinusitis: allergy and sinus computed tomography relationships Otolaryngol Head Neck Surg 123(6):687-91, 2000 887 Diagnostic Imaging Head and Neck Krouse JH: Computed tomography stage, allergy testing, and quality of life in patients with sinusitis Otolaryngol Head Neck Surg 123(4):389-92, 2000 P.IV(1):35 Image Gallery (Left) Axial T2WI MR in a patient with CRS shows opacification of the left maxillary sinus The central secretions are somewhat hypointense due to low water and high protein content Hyperintense inflamed mucosa is noted at the periphery (Right) Axial DWI MR in the same patient shows increased signal throughout the left maxillary sinus secretions suggesting restricted diffusion The restricted diffusion is greatest centrally (Left) Axial ADC image in the same patient confirms that restricted diffusion was the cause of the high signal on the DWI image Diminished signal on the ADC is noted in the secretions with high signal in the peripheral mucosa (Right) Axial bone CT in a patient with chronic frontal sinusitis shows mucosal thickening in both frontal sinuses There is marked thickening of the sinus walls, particularly on the left The changes on the left mimic fibrous dysplasia 888 Diagnostic Imaging Head and Neck (Left) Axial bone CT in Wegener granulomatosis patient shows typical changes of CRS involving maxillary sinuses Soft tissue opacifies the sinuses & nasal cavity There is prominent osteitis involving the sinus walls (Right) Coronal bone CT in a child with cystic fibrosis shows lobular mucosal thickening in both maxillary sinuses Fluid levels are present , suggesting acute infection superimposed on chronic inflammation Osteitis has not yet developed in this young patient Complications of Rhinosinusitis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Complications of Rhinosinusitis Complications of Rhinosinusitis Michelle A Michel, MD Key Facts Terminology Superficial complications: Osteomyelitis, subgaleal abscess (Pott puffy tumor) Orbital complications: Preseptal cellulitis/abscess, subperiosteal postseptal abscess (SPA), myositis of extraocular muscles, optic neuritis Intracranial complications: Meningitis, epidural abscess (EDA), subdural empyema (SDE), cerebritis, brain abscess, cavernous sinus thrombosis (CST) Imaging CECT for subperiosteal postseptal abscess Multiplanar post-gadolinium MR for intracranial complications Top Differential Diagnoses Of SPA: Orbital pseudotumor, extraconal neoplasm Of CST: Pseudotumor of cavernous sinus (Tolosa-Hunt), cavernous sinus neoplasm Of SDE: Subdural hygroma/hematoma Of cerebritis or cerebral abscess: Tumefactive MS, glioblastoma multiforme, solitary metastasis, radiation necrosis Pathology Intraorbital & intracranial complications more likely in ARS; superficial complications more common in CRS Orbital complication most often from ethmoiditis Intracranial complications most often from frontal sinusitis Clinical Issues Orbital complications more common in children Intracranial complications more common from adolescence to 2nd & 3rd decades Intracranial complications more common in males 889 Diagnostic Imaging Head and Neck (Left) Axial CECT in a child with right ethmoid and sphenoid sinusitis shows a low-density collection with a focus of air in the extraconal compartment of the right orbit The imaging features are characteristic of a subperiosteal abscess (Right) Coronal T1WI C+ FS MR in a patient with right frontal and ethmoid sinusitis shows a rim-enhancing collection in the extraconal space of the right orbit consistent with abscess There is slight inferior displacement of the globe (Left) Axial T2WI FS MR in a patient with frontal sinusitis shows abnormal increased signal within the inflamed sinus mucosa and within the soft tissues superficial to the frontal bone A focal high signal collection consistent with abscess is noted adjacent to the anterior sinus wall (Right) Axial T1WI C+ FS MR in the same patient shows enhancement and thickening of the soft tissues of the forehead over the abscess as well as dural enhancement P.IV(1):37 TERMINOLOGY Abbreviations Rhinosinusitis (RS), acute rhinosinusitis (ARS), chronic rhinosinusitis (CRS) Subperiosteal postseptal abscess (SPA), cavernous sinus thrombosis (CST), epidural abscess (EDA), subdural empyema (SDE) Definitions Complications of ARS or CRS may affect bone & overlying soft tissues, orbit, or intracranial cavity Superficial complications: Osteomyelitis, subgaleal abscess (Pott puffy tumor) Orbital complications: Preseptal cellulitis/abscess, SPA, myositis of extraocular muscles, optic neuritis Intracranial complications: Meningitis, epidural abscess, SDE, cerebritis, brain abscess, CST 890 Diagnostic Imaging Head and Neck IMAGING General Features Best diagnostic clue SPA: Peripherally enhancing, central low-density mass in medial extraconal space with surrounding infiltration of fat CST: Heterogeneously enhancing, enlarged cavernous sinus with enlarged or thrombosed superior ophthalmic vein (SOV) EDA & SDE: Extraaxial fluid collection in epidural or subdural space, respectively, with enhancing adjacent meninges Cerebral abscess: Ring-enhancing mass in parenchyma with uniformly thick walls, ↑ DWI, & surrounding edema Location SPA: Superomedial or medial extraconal space near medial rectus muscle secondary to ethmoiditis EDA & SDE: Subfrontal when related to frontal or ethmoid sinusitis; above planum sphenoidale from sphenoiditis Cerebral abscess: Most often in frontal lobes related to frontal sinusitis Subgaleal abscess: Soft tissues anterior to frontal sinuses Morphology SPA: Lentiform with base along lamina papyracea CST: Convex lateral margin of affected cavernous sinus EDA: Lenticular pus collection adjacent to infected sinus SDE: Crescentic pus collection conforming to shape of adjacent cerebrum Cerebritis: Ill-defined edema within brain Cerebral abscess: Round or ovoid parenchymal collection CT Findings CECT Subperiosteal postseptal abscess Peripherally enhancing, central low-attenuation collection in medial extraconal space (enhancement may be solid) Infiltration of surrounding fat with swelling of medial rectus ± dehiscence of lamina papyracea Cavernous sinus thrombosis Heterogeneous or ↓ enhancement in sinus compared to contralateral side Convex lateral margins (swollen) cavernous sinus Enlargement of SOV Subdural empyema Extraaxial subdural collection with low attenuation centrally & adjacent enhancing dura Cerebral abscess Ring-enhancing lesion with uniform wall & surrounding low-density edema Skull osteomyelitis/subgaleal abscess Focal bone lysis, sequestrum formation, reactive bone sclerosis Focal rim-enhancing fluid collection with subgaleal abscess MR Findings T1WI C+ Subperiosteal postseptal abscess Peripherally enhancing extraconal collection with low to intermediate T1 signal centrally & ↑ T2 signal centrally Cavernous sinus thrombosis Enlarged, heterogeneous enhancing cavernous sinus Enlarged or thrombosed SOV (absence of flow void) Extraocular muscles may be enlarged from venous engorgement Cavernous carotid may be narrowed Subdural empyema Extraaxial subdural collection with low T1 & high T2 signal centrally Adjacent enhancing dura Cerebritis Amorphous high signal area of brain on T2 or FLAIR No ring enhancement on T1 C+ sequences Cerebral abscess Ring-enhancing lesion with uniform wall thickness 891 Diagnostic Imaging Head and Neck Central ↓ T1/ADC & ↑ T2/DWI signal Rim may be ↓ T2 surrounded by ↑ T2 signal vasogenic edema Imaging Recommendations Best imaging tool CECT for subperiosteal postseptal abscess; post-gadolinium T1 MR for intracranial complications Protocol advice SPA: Thin section (1 mm) axial CT through sinuses/orbits post contrast with coronal reformats CST: Multiplanar gadolinium-enhanced MR; post contrast with fat suppression; thin slice axial and coronal through cavernous sinuses/orbits SDE/EDA/cerebritis/cerebral abscess: Multiplanar MR with gadolinium; fat suppression not necessary DIFFERENTIAL DIAGNOSIS DDx of Subperiosteal Postseptal Abscess Orbital idiopathic inflammatory pseudotumor Extraconal neoplasm P.IV(1):38 Orbital lymphoproliferative lesions Rhabdomyosarcoma DDx of Cavernous Sinus Thrombosis Skull base idiopathic inflammatory pseudotumor Cavernous sinus neoplasm Meningioma Sinonasal non-Hodgkin lymphoma Masticator space CNV3 perineural tumor DDx of Subdural Empyema Subdural hygroma Chronic subdural hematoma DDx of Cerebritis or Cerebral Abscess Cerebral contusion Multiple sclerosis Glioblastoma multiforme Radiation & chemotherapy effects on brain PATHOLOGY General Features Etiology Intraorbital & intracranial complications more likely in ARS; osseous complications more common in CRS Most complications result from bacterial infections; less likely fungal sources Sinocutaneous fistulae reported with CRS of frontal sinus SPA: Valveless ethmoidal veins allow access of ethmoid infection into orbit through thin lamina papyracea Due to ethmoid > sphenoid > frontal > maxillary sinusitis CST: Septic thrombophlebitis of ophthalmic veins Can spread from maxillary sinus via inferior ophthalmic vein or sphenoid sinus via pterygoid plexus Subgaleal abscess (Pott puffy tumor): Osteothrombophlebitis from frontal sinusitis Intracranial complications: Most often from frontal sinusitis because of emissary vein network (Behỗet plexus) connecting sinus mucosa with meninges Frontal > > sphenoid > ethmoid > maxillary Associated abnormalities Meningitis CLINICAL ISSUES Presentation Most common signs/symptoms SPA: Proptosis, chemosis, decreased visual acuity, limited ocular motility Subgaleal abscess: Forehead swelling CST: Extremely ill patients with retro-orbital pain, cranial nerve palsies, & signs of meningitis SDE/EDA: Headache, fever, signs of mass effect Cerebral abscess: Headache, seizure, focal deficits depending on location 892 Diagnostic Imaging Head and Neck Demographics Age Orbital complications of RS more common in children Intracranial complications more common from adolescence to 2nd & 3rd decades Gender Intracranial complications more common in males Epidemiology 3% of sinusitis patients experience preseptal or orbital inflammation Permanent ocular sequelae in 4.5% of sinogenic orbital infections 15-20% of optic neuritis due to posterior ethmoid & sphenoid sinusitis 3% of headaches related to sinusitis 3% of intracranial abscesses secondary to sinusitis Natural History & Prognosis Potential progression of orbital complications if untreated Periorbital cellulitis SPA CST meningitis SDE cerebral abscess Prognosis excellent with appropriate antibiotic therapy & surgical drainage Intracranial complications 50-80% mortality if not diagnosed and treated early Treatment Appropriate antibiotic therapy in all cases Surgical intervention for SPA (FESS), some SDE, and cerebral abscesses DIAGNOSTIC CHECKLIST Consider Imaging valuable in patients with uncertain diagnosis, deteriorating condition despite treatment Multiplanar MR imaging advantageous for evaluating intracranial complications Image Interpretation Pearls Can be difficult to distinguish SPA from phlegmon Compare size & shape of affected cavernous sinus to contralateral side to diagnose CST SELECTED REFERENCES Bayonne E et al: Intracranial complications of rhinosinusitis A review, typical imaging data and algorithm of management Rhinology 47(1):59-65, 2009 Coenraad S et al: Surgical or medical management of subperiosteal orbital abscess in children: a critical appraisal of the literature Rhinology 47(1):18-23, 2009 Mafee MF et al: Imaging of rhinosinusitis and its complications: plain film, CT, and MRI Clin Rev Allergy Immunol 30(3):165-86, 2006 Wong AM et al: Magnetic resonance imaging of carotid artery abnormalities in patients with sphenoid sinusitis Neuroradiology 46(1):54-9, 2004 Younis RT et al: The role of computed tomography and magnetic resonance imaging in patients with sinusitis with complications Laryngoscope 112(2):224-9, 2002 Eustis HS et al: MR imaging and CT of orbital infections and complications in acute rhinosinusitis Radiol Clin North Am 36(6):1165-83, xi, 1998 P.IV(1):39 Image Gallery 893 Diagnostic Imaging Head and Neck (Left) Coronal T1WI C+ MR demonstrates a subdural empyema in a left parafalcine location medial to the left frontal lobe There is linear enhancement of the surrounding inflamed dura Note the opacified sphenoid sinuses in this patient with pansinusitis (Right) Axial T2WI MR in the same patient shows abnormal increased signal in the left frontal lobe consistent with cerebritis, a 2nd intracranial complication from the patient's sinusitis (Left) Sagittal T1WI C+ MR shows opacification of the left frontal sinus with extensive dural thickening and enhancement over the frontal lobe A focal low signal collection consistent with a subdural empyema is also seen Subtle low T1 signal is appreciated within the frontal lobe parenchyma (Right) Axial FLAIR MR in the same patient confirms the abnormal signal in the parenchyma , consistent with cerebritis without abscess formation 894 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ MR in a patient with bilateral cavernous sinus thrombosis secondary to pansinusitis shows foci of nonenhancing thrombus in both cavernous sinuses Dural thickening is noted along the tentorium and along the left greater sphenoid wing (Right) Axial CECT in the same patient shows enlargement of both superior ophthalmic veins with absence of contrast in the entire vein on the right and posterior portion of the left vein Allergic Fungal Sinusitis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Allergic Fungal Sinusitis Allergic Fungal Sinusitis Michelle A Michel, MD Key Facts Terminology Severe form of CRS with production of eosinophilic mucin containing noninvasive fungal hyphae Imaging NECT Opacification & expansion of multiple sinuses with centrally hyperdense material Unilateral or bilateral (50/50); R > L MR imaging T1 signal variable depending on water, protein, & fungal content ↓ T2 signal due to dense fungal concretions & heavy metals (can mimic air) Peripheral inflamed mucosa enhances Top Differential Diagnoses Sinonasal polyposis Sinonasal solitary polyp Sinonasal mucocele Pathology Probable type 1, IgE-mediated immune response to fungal elements Often in association with sinonasal polyposis Clinical Issues Immunocompetent, nondiabetic patient with longstanding CRS, allergy ± polyposis history Most common in young adults Male predominance ↑ incidence in African-Americans Predilection for warm, humid climates Symptoms: Nasal obstruction, rhinorrhea Facial deformity, diplopia in severe cases from expansion 895 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows classic features of AFS, including opacification and expansion of multiple paranasal sinuses and the nasal cavity with centrally dense material Peripheral edematous mucosa is noted In this graphic, the involvement is unilateral (Right) Axial NECT shows the typical appearance of allergic fungal sinusitis with unilateral involvement The involved sinuses are expanded, and the material is centrally dense with a peripheral rim of low attenuation (Left) Axial T2WI MR in a patient with bilateral AFS shows diffuse hypointense signal within the involved ethmoid air cells There is mild sinus expansion with lateral bowing of the lamina papyracea On this T2 image alone, the AFS mimics normal sinus aeration (Right) Axial T1WI C+ MR in the same patient clearly shows that the ethmoid sinuses are not aerated but are opacified It is important to review all sequences in such cases P.IV(1):41 TERMINOLOGY Abbreviations Allergic fungal sinusitis (AFS) Synonyms Allergic fungal rhinosinusitis Definitions Severe form of chronic rhinosinusitis (CRS) with production of eosinophilic mucin containing noninvasive fungal hyphae IMAGING General Features 896 Diagnostic Imaging Head and Neck Best diagnostic clue Opacification & expansion of multiple sinuses with centrally hyperdense & peripherally hypodense material on NECT Location Involves multiple sinuses Ethmoid > maxillary > frontal > sphenoid Unilateral or bilateral (50/50); R > L CT Findings NECT ↑ attenuation material within opacified sinuses Hypodense rim of mucosa Expansion of sinus with bony remodeling May see bone erosion MR Findings T1WI Signal highly variable depending on water, protein, & fungal content Typically intermediate to high signal due to ↓ water content & ↑ protein content T2WI Hypointense signal centrally due to dense fungal concretions & heavy metals T1WI C+ Peripheral inflamed mucosa enhances Imaging Recommendations Best imaging tool Coronal NECT (direct or axial with reformat) with soft tissue & bone algorithm DIFFERENTIAL DIAGNOSIS Sinonasal Polyposis Involves nasal cavity and sinuses; not necessarily hyperdense Sinonasal Solitary Polyps Low-density lesion on CT; extends from antrum into nasal cavity into nasopharynx Sinonasal Mucocele Expansile lesion involving single sinus ↓ density on CT; ↑ T2 signal on MR Sinonasal Non-Hodgkin Lymphoma Centered in nasal cavity Homogeneous with ↑ density on NECT Bone destruction or remodeling PATHOLOGY General Features Etiology Probable type 1, IgE-mediated immune response to fungal elements Associated abnormalities Associated with sinonasal polyposis Gross Pathologic & Surgical Features Viscous brown or greenish-black mucous with peanut butter/cottage cheese consistency Microscopic Features Viscous, eosinophilic mucin with fungal hyphae No tissue invasion CLINICAL ISSUES Presentation Most common signs/symptoms Nasal obstruction, rhinorrhea Clinical profile Immunocompetent, nondiabetic patient with longstanding CRS, allergy ± polyposis history Demographics Age Primarily young adults (mean ≈ 30 years) Gender Male predominance Epidemiology 897 Diagnostic Imaging Head and Neck Asthma history in 40% ↑ incidence in African-Americans Predilection for warm, humid climates Natural History & Prognosis Slow, indolent course in face of CRS & allergy Treatment Topical & systemic antifungal agents, topical steroids, saline irrigation Surgical debridement + perioperative systemic steroids DIAGNOSTIC CHECKLIST Consider AFS if increased density in multiple sinuses with expansion Often concurrent sinonasal polyposis SELECTED REFERENCES Chakrabarti A et al: Fungal rhinosinusitis: a categorization and definitional schema addressing current controversies Laryngoscope 119(9):1809-18, 2009 Wise SK et al: Radiologic staging system for allergic fungal rhinosinusitis (AFRS) Otolaryngol Head Neck Surg 140(5):735-40, 2009 Aribandi M et al: Imaging features of invasive and noninvasive fungal sinusitis: a review Radiographics 27(5):128396, 2007 Mukherji SK et al: Allergic fungal sinusitis: CT findings Radiology 207(2):417-22, 1998 Mycetoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Mycetoma Mycetoma Michelle A Michel, MD Key Facts Terminology Fungus ball, aspergilloma Chronic, noninvasive form of fungal sinus infection in which material within sinonasal cavity is colonized by fungus Imaging Single paranasal sinus containing high-density material with fine, round-to-linear matrix calcifications Maxillary > sphenoid > > frontal > ethmoid sinuses Top Differential Diagnoses Chronic rhinosinusitis Allergic fungal sinusitis Mucocele Invasive fungal sinusitis Pathology Deficient mucociliary clearance mechanism → inadequate clearance of fungal organisms → fungus germinates & replicates → incites inflammatory response Clinical Issues Asymptomatic or mild sensation of pressure overlying sinuses Indolent course for up to years Most common in older female patients but may occur in all ages Diagnostic Checklist Do not mistake low T2 signal for air! Correlate T2 appearance with other sequences ± CT Be sure to look for any signs of invasive disease! 898 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows the classic features of a mycetoma within the right maxillary sinus The sinus is opacified but not expanded Mixed density material consistent with fungal elements and calcium deposits are present in the sinus (Right) Axial T2WI MR is slightly degraded by motion but shows a classic “fungus ball” in the left maxillary sinus The mycetoma is hypointense compared to inflamed mucosa at the periphery Thickening of the bony sinus walls is also noted (Left) Coronal CECT in a patient with a sphenoid sinus mycetoma demonstrates multiple foci of calcification within the fungus ball The sinus is opacified and there is no expansion (Right) Sagittal T1WI C+ MR in the same patient shows a somewhat lamellated appearance of the material within the mycetoma The signal varies from in the mycetoma hypointense to hyperintense from anterior to posterior Enhancement of inflamed mucosa is seen anteriorly P.IV(1):43 TERMINOLOGY Synonyms Fungus ball, aspergilloma Definitions Chronic, noninvasive form of fungal sinus infection in which material within sinonasal cavity is colonized by fungus IMAGING General Features Best diagnostic clue Single paranasal sinus containing high-density material with fine, round-to-linear matrix calcifications Location 899 Diagnostic Imaging Head and Neck Usually affects a single sinus Maxillary > sphenoid > > frontal > ethmoid sinuses Size Sinus typically normal, nonexpanded Morphology May conform to sinus shape or be ovoid (ball-shaped) within sinus lumen CT Findings CECT Thickened, inflamed mucosa at periphery of sinus may enhance Bone CT Opacification or focal mass within sinus lumen Central areas of high density ± calcification Thick, sclerotic bony sinus walls from chronic inflammation MR Findings T1WI Variable signal material in affected sinus Usually ↓ T1 signal due to absence of free water in thick, solid, mycetomatous mass T2WI Hypointense mass from macromolecular protein binding may be mistaken for air T1WI C+ Inflamed peripheral mucosa may enhance Imaging Recommendations Best imaging tool NECT features diagnostic in typical cases; better for detecting Ca++ DIFFERENTIAL DIAGNOSIS Chronic Rhinosinusitis Less likely to appear mass-like Ca++ less likely Allergic Fungal Sinusitis Atopic patient with multiple unilateral or pansinus involvement High-density (CT)/low T1/T2 (MR) material within expanded sinuses Sinonasal Mucocele Sinus opacified and expanded Frontal & ethmoid > > > maxillary & sphenoid Invasive Fungal Sinusitis Immunocompromised patient Bone destruction & soft tissue invasion Sinonasal Inverted Papilloma Mass in nasal cavity centered at middle meatus Convoluted, “cerebriform” architecture PATHOLOGY General Features Etiology Deficient mucociliary clearance mechanism → inadequate clearance of fungal organisms → fungus germinates & replicates → incites inflammatory response Saprophytic fungal growth within paranasal sinus Gross Pathologic & Surgical Features Thick, cheesy, semisolid lesion Microscopic Features Tightly packed fungal hyphae with no allergic mucin (compared to allergic fungal sinusitis) No tissue (mucosal, blood vessel, bone) invasion compared to acute invasive fungal sinusitis CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic or mild sensation of pressure overlying sinuses Clinical profile Immunocompetent, nonatopic, otherwise healthy patient with no or minimal symptoms Demographics Age 900 Diagnostic Imaging Head and Neck Most common in older patients but may occur in all ages Gender Female predilection Epidemiology Mycetoma & allergic fungal sinusitis are most common forms of fungal sinusitis Natural History & Prognosis Indolent course for up to years Treatment Surgical excision is treatment of choice & is curative SELECTED REFERENCES Robey AB et al: The changing face of paranasal sinus fungus balls Ann Otol Rhinol Laryngol 118(7):500-5, 2009 Daudia A et al: Advances in management of paranasal sinus aspergillosis J Laryngol Otol 122(4):331-5, 2008 Invasive Fungal Sinusitis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Invasive Fungal Sinusitis Invasive Fungal Sinusitis Michelle A Michel, MD Key Facts Terminology Acute invasive fungal rhinosinusitis (AIFRS): Rapidly progressive fungal sinus infection in immunocompromised patients that involves bone & adjacent soft tissues via vascular spread Imaging AIFRS: Most common in maxillary & ethmoid sinuses followed by sphenoid sinus CT: Sinus opacification with focal bone erosion, adjacent soft tissue infiltration MR: Superior for evaluating intraorbital & intracranial extension Top Differential Diagnoses Acute rhinosinusitis with complication Sinonasal Wegener granulomatosis Sinonasal squamous cell carcinoma Sinonasal non-Hodgkin lymphoma Pathology Present classification based upon International Society for Human and Animal Mycology Group, February 2008 Acute invasive (fulminant) FRS Granulomatous invasive FRS Chronic invasive FRS Clinical Issues AIFRS: Acute onset fever, painless nasal septal ulcer, sinusitis Can be rapidly progressive & fatal in days to weeks Orbital & intracranial involvement are most dreaded complications GIFRS: Enlarging cheek, orbit, or sinonasal mass CIFRS: Sinus pain, nasal discharge, epistaxis, fever, polyposis 901 Diagnostic Imaging Head and Neck (Left) Coronal NECT in a diabetic patient with mucormycosis infection shows extensive disease in the left maxillary sinus with intraorbital extension of infection through a defect in the infraorbital canal Low-attenuation abscesses are seen involving the lateral and inferior rectus muscles (Right) Axial T1WI C+ FS MR in the same patient shows additional extension of the invasive fungal infection in the premaxillary soft tissues and masticator space (Left) Axial T1WI C+ FS MR in an immunosuppressed transplant patient shows invasive fungal sinusitis involving the right ethmoid air cells There is extension of infection into the right orbit around the rectus muscles and at the orbital apex Intracranial extension via the superior orbital fissure is noted (Right) Coronal T2WI MR in the same patient shows hypointense signal , characteristic of fungal disease, in the superomedial aspect of the involved orbit P.IV(1):45 TERMINOLOGY Abbreviations Invasive fungal sinusitis (IFS) Acute invasive fungal rhinosinusitis (AIFRS) Granulomatous invasive fungal rhinosinusitis (GIFRS) Chronic invasive fungal rhinosinusitis (CIFRS) Definitions AIFRS: Rapidly progressive fungal sinus infection in immunocompromised patients that crosses mucosa to involve blood vessels, bone, soft tissues, orbit, intracranial cavities GIFRS: Rarely seen in USA; indolent but profuse fungal growth with noncaseating granulomas 902 Diagnostic Imaging Head and Neck CIFRS: Dense hyphal accumulation resembling mycetoma (from which it may arise), associated with orbital apex syndrome, diabetes mellitus, corticosteroid therapy IMAGING General Features Best diagnostic clue Sinus opacification with focal bone erosion, adjacent soft tissue infiltration Location AIFRS: Most common in maxillary & ethmoid sinuses followed by sphenoid sinus Spread from sinuses can extend in any direction CIFRS: Most common in ethmoid & sphenoid sinuses Morphology Ill-defined or mass-like soft tissue lesion CT Findings NECT Complete or partial soft tissue opacification of affected sinus; mucosal thickening Hyperattenuation of secretions suggests fungal infection; more typical of chronic than acute Focal areas of sinus wall erosion Bone erosion may be subtle as fungi extend along vessels Infiltration of adjacent fat and soft tissues Maxillary sinus: Perimaxillary fat infiltration (anterior, premaxillary, or retroantral fat) Can be present without bone destruction via perivascular channels May be due to edema from vascular congestion, tissue infiltration by fungal elements CECT Periantral soft tissues, adjacent musculature may enhance CTA May show arterial or venous narrowing/occlusion Pseudoaneurysm formation CTV: Better for confirming cavernous sinus thrombosis MR Findings T1WI Variable signal of material within involved sinus Depends on protein/water content, presence of fungal elements Diminished signal, similar to soft tissue, within periantral fat T2WI Variable signal of sinus secretions Fungal elements may cause hypointense T2 signal High signal edema in involved soft tissues may be seen with fat suppression T1WI C+ Enhancement of involved soft tissues Leptomeningeal enhancement MRA Vascular involvement (narrowing, dissection, thrombosis) Angiographic Findings Vascular involvement (narrowing, dissection, thrombosis, pseudoaneurysm formation) Imaging Recommendations Best imaging tool CECT with soft tissue & bone windows to evaluate bone erosion, soft tissue infiltration MR superior for evaluating intraorbital & intracranial extension Protocol advice Axial helical CECT ≤ mm slice thickness reconstructed in bone & soft tissue algorithm, coronal reconstructions T1 C+ FS MR images recommended to map disease spread beyond sinuses DIFFERENTIAL DIAGNOSIS Complicated Rhinosinusitis Patient may not be immunocompromised Bone erosion less likely Homogeneous air-fluid level, peripheral mucosal thickening in sinus Complications of subperiosteal postseptal abscess, cavernous sinus thrombosis, meningitis & cerebral abscess appear similar to AIFRS 903 Diagnostic Imaging Head and Neck Sinonasal Wegener Granulomatosis Usually involves nasal cavity (septum & turbinates) Less mass-like soft tissue, prominent bone erosion Orbit & skull base involvement possible Sinonasal Squamous Cell Carcinoma Typically immunocompetent patient Maxillary antrum most common site Solid mass with bone destruction Sinonasal Non-Hodgkin Lymphoma Solid, homogeneous mass in nasal cavity ↓ T2 signal due to ↑ N:C ratio could mimic fungus PATHOLOGY General Features Etiology AIFRS: Vascular & soft tissue invasion by fungi in patients with variety of predisposing conditions P.IV(1):46 Neutropenia/neutrophil dysfunction Uncontrolled diabetes mellitus Hematologic malignancy, aplastic anemia Hemochromatosis Chronic immunosuppressive therapy, post-transplantation/chemotherapy Spread from sinuses via vascular invasion Staging, Grading, & Classification Current classification based on International Society for Human & Animal Mycology Group, February 2008 Based on histopathologic finding of mucosal invasion Acute invasive (fulminant) FRS Granulomatous invasive FRS Chronic invasive FRS Gross Pathologic & Surgical Features AIFRS: Necrotic involved tissue, discoloration to presence of fungus Microscopic Features AIFRS Hyphal invasion of mucosa, submucosa, & blood vessels Prominent tissue infarction & neutrophilic infiltrates GIFRS Noncaseating granulomatous response with considerable fibrosis and scant hyphae Vasculitis, vascular proliferation, perivascular fibrosis Aspergillus flavus most common CIFRS Dense accumulation of hyphae with occasional vascular invasion Sparse inflammatory reaction > 50% Aspergillus fumigatus CLINICAL ISSUES Presentation Most common signs/symptoms AIFRS: Acute onset fever, painless nasal septal ulcer, sinusitis, & progression to headache/orbital symptoms GIFRS: Enlarging cheek, orbit, or sinonasal mass CIFRS: Sinus pain, nasal discharge, epistaxis, fever, polyposis Clinical profile AIFRS: Rapidly progressive (< weeks) invasive fungal infection in immunocompromised patient Spreads from sinuses via vascular invasion GIFRS: Immunocompetent host with > 12 week course of enlarging cheek, orbit, or sinonasal mass CIFRS: Slowly destructive process (> 12 weeks) seen in patients with AIDS, DM, or on corticosteroids Can be seen in immunocompetent patient Symptoms may take months/years to develop; may persist & recur Demographics 904 Diagnostic Imaging Head and Neck Age Typically in adults Epidemiology Diabetic or immunocompromised patients with predisposing conditions GIFRS: Seen primarily in Sudan, India, Pakistan, & Saudi Arabia Natural History & Prognosis AIFRS: Can be rapidly progressive & fatal in days to weeks without appropriate surgical-medical therapy Mortality (50-80%) Fair prognosis if limited to sinus & immediately adjacent tissues Orbital & intracranial involvement are most dreaded complications AIFRS of sphenoid sinus can lead to cavernous sinus thrombosis, carotid occlusion, mycotic aneurysm formation, cranial nerve dysfunction, cerebral infarction Treatment Radical debridement until histopathologically normal tissue reached Antifungal therapy with amphotericin B (Mucor species not sensitive to “azole” antifungals) Treat underlying condition responsible for immunocompromised state Reversal of these conditions may ↓ mortality to 18% DIAGNOSTIC CHECKLIST Consider AIFRS in diabetic/immunocompromised patient with maxillary disease, “dirty” periantral fat even if no bone erosion present Image Interpretation Pearls Do not confuse normal variability in volume of periantral fat or normal musculature with fat infiltration Evaluate orbit, intracranial cavities for involvement (leptomeningeal enhancement) Closely examine cavernous sinus, internal carotid artery in sphenoid AIFRS SELECTED REFERENCES Chakrabarti A et al: Fungal rhinosinusitis: a categorization and definitional schema addressing current controversies Laryngoscope 119(9):1809-18, 2009 Deshazo RD: Syndromes of invasive fungal sinusitis Med Mycol 47 Suppl 1:S309-14, 2009 Süslü AE et al: Acute invasive fungal rhinosinusitis: our experience with 19 patients Eur Arch Otorhinolaryngol 266(1):77-82, 2009 Epstein VA et al: Invasive fungal sinusitis and complications of rhinosinusitis Otolaryngol Clin North Am 41(3):497524, viii, 2008 Aribandi M et al: Imaging features of invasive and noninvasive fungal sinusitis: a review Radiographics 27(5):128396, 2007 Parikh SL et al: Invasive fungal sinusitis: a 15-year review from a single institution Am J Rhinol 18(2):75-81, 2004 Howells RC et al: Usefulness of computed tomography and magnetic resonance in fulminant invasive fungal rhinosinusitis Am J Rhinol 15(4): 255-61, 2001 Silverman CS et al: Periantral soft-tissue infiltration and its relevance to the early detection of invasive fungal sinusitis: CT and MR findings AJNR Am J Neuroradiol 19(2): 321-5, 1998 P.IV(1):47 Image Gallery 905 Diagnostic Imaging Head and Neck (Left) Axial CECT in a patient with invasive mucormycosis involving the left maxillary and ethmoid sinuses reveals thrombosis of the left cavernous sinus and cavernous internal carotid Note the normal enhancement within the right ICA (Right) Axial T1WI C+ FS MR in the same patient shows extensive left cavernous sinus involvement The intracranial internal carotid is occluded , and the vessel is engulfed by the invasive fungal disease in the left cavernous sinus (Left) Axial T1WI C+ MR shows a typical case of maxillary fungal sinusitis that has spread from the maxillary antrum to surrounding soft tissues Spread into the masticator space is noted with enhancement of the muscles of mastication (Right) Axial T2WI FS MR in the same patient shows hypointense signal characteristic of fungal material within the antrum Hyperintense signal is noted within the involved masticator space musculature 906 Diagnostic Imaging Head and Neck (Left) Axial CECT in a patient with mucormycosis shows circumferential soft tissue in the left maxillary sinus Destruction of the posterior wall of the sinus is noted medially, and there is infiltration of the retroantral fat consistent with fungal spread beyond the sinus (Right) Axial T1WI MR shows extensive fungal involvement of the left maxillary sinus The posterior sinus wall is eroded , with extension of infection into the left retromaxillary fat pad Sinonasal Polyposis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Sinonasal Polyposis Sinonasal Polyposis Michelle A Michel, MD Key Facts Terminology Nonneoplastic, inflammatory swelling of sinonasal mucosa that buckles to form “polyps” Imaging Involves nasal cavity & paranasal sinuses (vs retention cysts mainly within sinuses) Predominantly along lateral nasal wall & roof of nasal cavity Anterior > posterior Primarily mucoid or soft tissue density Remodeling of sinonasal bones common in severe cases MR imaging with gadolinium helpful for differentiating SNP from neoplasm & to assess extrasinus extent Top Differential Diagnoses Mucous retention cyst Allergic fungal sinusitis Solitary polyp Wegener granulomatosis Pathology Formal pathogenesis of SNP has not been clarified Chronic inflammation is major factor Associated with allergy, asthma, primary ciliary dyskinesia, aspirin sensitivity, & cystic fibrosis Clinical Issues Although not life threatening, chronic SNP unresponsive to therapy can be chronic, debilitating disease Medical therapy = treatment of choice Surgery reserved for symptomatic relief & correction of cosmetic deformities, orbital and intracranial involvement 907 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows the classic appearance of sinonasal polyposis with multiple lobular soft tissue masses involving the nasal cavity and paranasal sinuses In this case the involvement is diffuse & bilateral, without expansion (Right) Coronal bone CT in a patient with polyposis and new onset of acute sinusitis symptoms shows polyps in the nasal cavity occluding the middle meati Fluid levels consistent with acute inflammation are present in the maxillary sinuses (Left) Coronal T1WI MR shows multiple intermediate signal intensity polyps filling the nasal cavity, maxillary, & ethmoid sinuses Trapped secretions with high protein content (T1 shortening) are also noted (Right) Coronal T1WI C+ FS MR in the same patient shows enhancement of the inflamed mucosa at the periphery of the polyps There is slight expansion of the right maxillary sinus with elevation of the orbital floor P.IV(1):49 TERMINOLOGY Abbreviations Sinonasal polyposis (SNP) Synonyms Polyposis nasi; hypertrophic polypoid rhinosinusitis Definitions Nonneoplastic, inflammatory swelling of sinonasal mucosa that buckles to form “polyps” IMAGING General Features Best diagnostic clue Polypoid masses involving nasal cavity & paranasal sinuses mixed with chronic inflammatory secretions 908 Diagnostic Imaging Head and Neck Location Predominantly along lateral nasal wall (near middle meatus) & roof of nasal cavity & ethmoids Anterior sinonasal cavities > posterior Involves nasal cavity & paranasal sinuses (vs retention cysts mainly within sinuses) Usually multiple & bilateral; may be unilateral Size Variable; up to several cm Morphology Polypoid, lobular CT Findings NECT Primarily mucoid or soft tissue density May be hyperdense with ↑ protein, ↓ water content or colonization with fungal elements CECT Mucosal enhancement at periphery of polyps No central enhancement as in neoplasms Bone CT Multiple, polypoid, soft tissue masses within nasal cavity & paranasal sinuses Remodeling of sinonasal bones common in severe cases May have areas of bone erosion Other findings Ethmoid sinus remodeling with trabecular loss & convex lateral walls bulging into orbits Air-fluid levels may signal superinfection or merely trapped fluid Truncation of bulbous, bony, inferior portion of middle turbinates MR Findings T1WI Fresh mucus (high water content) is hypointense Bizarre mixture of layered signals seen in sinuses & nose Results from polyps mixed with various ages of mucus T2WI Fresh mucus is hyperintense Chronic, inspissated mucus can appear low signal (mimics air) T1WI C+ Thin mucosal enhancement between polypoid soft tissue lesions without central enhancement Imaging Recommendations Best imaging tool NECT in coronal plane is adequate for most cases Protocol advice If orbital or intracranial extension is suspected based on dehiscent bone on CT, enhanced MR imaging done to assess extrasinus extent MR imaging with gadolinium helpful for differentiating SNP from neoplasm in difficult cases DIFFERENTIAL DIAGNOSIS Sinonasal Retention Cyst Clinically asymptomatic or sinusitis history Lesions within sinuses with relative sparing of nasal cavity Difficult to distinguish from polyps based on density/signal intensity alone Fluid density/signal on CT/MR; no central enhancement Allergic Fungal Sinusitis (AFS) Atopic patient with multiple unilateral or pansinus involvement May mimic SNP; frequently seen in association with polyps CT shows high-density central material with low-density rim in expanded sinuses MR may show low signal on both T1 & T2 images Sinonasal Solitary Polyps Unilateral, solitary lesion Extends from antrum through widened infundibulum into nasal cavity Sinonasal Wegener Granulomatosis Multi-system granulomatous disease involving lung & kidney Nodular soft tissue most often involving septum, inferior turbinates, & lateral nasal wall Bony destruction (septal perforation) rather than remodeling 909 Diagnostic Imaging Head and Neck Sinonasal Sarcoidosis Multi-system granulomatous disease Nodular soft tissue most often involving septum & turbinates PATHOLOGY General Features Etiology Inflammatory swelling of unstable respiratory mucosa Formal pathogenesis of SNP has not been clarified; chronic persistent inflammation is major factor Principal hypothesis: Allergy & inflammation cause unstable mucosa with epithelial cell proliferation & morphologic changes Others factors implicated P.IV(1):50 Cytokines (IL-5, granulocyte-macrophage colony stimulating factor, tumor necrosis factor) Mechanical forces in areas of contact between opposing mucosal membranes Role of bacterial biofilms current area of investigation Genetics No causative chromosomal aberrations identified ↑ in cystic fibrosis patients (autosomal recessive) Associated abnormalities Associated with chronic rhinosinusitis (CRS), allergy, asthma, primary ciliary dyskinesia, aspirin sensitivity, & cystic fibrosis Polyposis & AFS are frequently seen in association (≈ 66% of cases) Gross Pathologic & Surgical Features Pinkish, fleshy, pedunculated polypoid sinonasal masses with glistening mucoid surface Microscopic Features Intact surface respiratory epithelium Underlying stroma is edematous with inflammatory cellular infiltrate & variable vascularity, glands & goblet cells Seromucinous glands usually absent Eosinophil-dominated inflammation with component of neutrophils & mast cells May show squamous, cartilaginous, or osseous metaplasia ± surface ulceration & granuloma formation Superinfecting bacteria include Pseudomonas aeruginosa, Bacteroides fragilis, Staphylococcus aureus CLINICAL ISSUES Presentation Most common signs/symptoms Progressive nasal stuffiness & obstruction Sensation of secretions that cannot be expelled Other signs/symptoms Rhinorrhea, facial pain, headaches, & anosmia Cosmetic deformity, hypertelorism in cases of “polypoid mucocele” Clinical profile Allergic patient with progressive nasal stuffiness Polyps identified with nasal endoscopy Demographics Age Most common in adults > 20 years Rare in children < years Epidemiology Frequency of polyps 1-2% of normal population 5% of extrinsic asthma patients 13% of intrinsic bronchial asthma patients 16% of “dental” sinusitis patients 20% of cystic fibrosis patients > 50% of aspirin intolerant patients Natural History & Prognosis Often waxing & waning; chronic, relentless disease 910 Diagnostic Imaging Head and Neck If left unattended, may become highly deforming in central facial region Although not life threatening, chronic SNP unresponsive to therapy can be chronic, debilitating disease Treatment Medical therapy = treatment of choice Topical & oral corticosteroids to reduce rhinitis symptoms, ↓ polyp size, & reduce recurrence Antibiotics when superinfected Surgery reserved for symptomatic relief & correction of cosmetic deformities, orbital and intracranial involvement Endoscopic polypectomy, FESS, or sphenoethmoidectomy Usually only temporary relief DIAGNOSTIC CHECKLIST Consider If density of expansile polyps is increased ± signal heterogeneous on MR, AFS in setting of polyposis is likely Image Interpretation Pearls Polyps occur in sinuses and nasal cavity Mucous retention cysts typically located in sinuses only Individual polyps cannot be differentiated from mucous retention cysts based on density or signal characteristics alone Do not be alarmed if areas of bone erosion are present in addition to remodeling If predominant pattern is aggressive-appearing bone destruction, must rule out malignancy or granulomatous disease SELECTED REFERENCES Blomqvist EH et al: A randomized prospective study comparing medical and medical-surgical treatment of nasal polyposis by CT Acta Otolaryngol 129(5):545-9, 2009 Pearlman AN et al: Relationships between severity of chronic rhinosinusitis and nasal polyposis, asthma, and atopy Am J Rhinol Allergy 23(2):145-8, 2009 Bonfils P et al: Evaluation of combined medical and surgical treatment in nasal polyposis - III Correlation between symptoms and CT scores before and after surgery for nasal polyposis Acta Otolaryngol 128(3):318-23, 2008 Corradini C et al: Hyperproliferation in nasal polyposis tissues is not associated with somatic genomic instability J Otolaryngol Head Neck Surg 37(4):510-4, 2008 Mladina R et al: Biofilm in nasal polyps Rhinology 46(4):302-7, 2008 Mortuaire G et al: Lund-Mackay score is predictive of bleeding in ethmoidectomy for nasal polyposis Rhinology 46(4):285-8, 2008 Konstantinidis I et al: Olfactory dysfunction in nasal polyposis: correlation with computed tomography findings ORL J Otorhinolaryngol Relat Spec 69(4):226-32, 2007 Gosepath J et al: Current concepts in therapy of chronic rhinosinusitis and nasal polyposis ORL J Otorhinolaryngol Relat Spec 67(3):125-36, 2005 Liang EY et al: Another CT sign of sinonasal polyposis: truncation of the bony middle turbinate Eur Radiol 6(4):5536, 1996 P.IV(1):51 Image Gallery 911 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows the typical features of sinonasal polyposis with multiple polypoid soft tissue lesions involving the nasal cavity Mucosal thickening is seen in the maxillary and left sphenoid sinuses (Right) Coronal bone CT shows increased density, expansile soft tissue in the right ethmoid sinuses with extension of polypoid soft tissue into the nasal cavity Trapped secretions are noted in the right maxillary sinus (Left) Coronal CECT in a patient with polyposis shows polyps involving the nasal cavity bilaterally Polypoid material also opacifies the ethmoid air cells The expansion with lateral remodeling of the lamina papyracea helps to differentiate polyps from mucosal thickening (Right) Axial T2WI MR in a severe case of polyposis shows multiple hyperintense polyps filling the nasal cavity and involving the medial portions of the maxillary sinuses 912 Diagnostic Imaging Head and Neck (Left) Axial T2WI FS MR demonstrates hypointense polyps filling and expanding the ethmoid and sphenoid sinuses On this sequence, the polyps mimic the hypointense signal of air-filled sinuses (Right) Sagittal T1WI C+ MR in the same patient shows enhancement in multiple nasal cavity polyps The sphenoid polyps show mixed signal intensity Note the marked thinning of the clival cortex Solitary Sinonasal Polyp > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Solitary Sinonasal Polyp Solitary Sinonasal Polyp Michelle A Michel, MD Key Facts Imaging Most common type is antrochoanal Polypoid mass extends from maxillary antrum → enlarged maxillary ostium or accessory ostium → nasal cavity Peripheral enhancement with no central enhancement Top Differential Diagnoses Intranasal glioma Nasoethmoidal cephalocele Juvenile angiofibroma Inverted papilloma Esthesioneuroblastoma Pathology Inflammatory polyp resulting from edematous hypertrophy of respiratory epithelium Postobstructive inflammatory disease is often present Greater when ACP exits antrum via natural ostium vs accessory ostium Clinical Issues 4-6% of all sinonasal polyps Most common in teenagers & young adults Typical symptoms: Unilateral nasal obstruction, worse on expiration Complete surgical removal of nasal & antral components is treatment of choice Diagnostic Checklist Begin imaging evaluation with coronal bone CT If bone CT or endoscopy appearance is atypical, consider MR with contrast to rule out neoplasm 913 Diagnostic Imaging Head and Neck (Left) Longitudinal oblique graphic shows an antrochoanal polyp extending from maxillary antrum through a posterior fontanelle into the nasal cavity Note the posterior extension of the polyp into the nasopharynx (Right) Coronal bone CT shows a typical antrochoanal polyp extending from the left maxillary antrum into the nasal cavity via a secondary ostium located posterior to the ostiomeatal complex (Left) Axial T2WI MR shows diffuse homogeneous hyperintense signal within an ACP The polyp extends into the nasal cavity via a secondary ostium A small amount of trapped secretions are noted lateral to the lesion (Right) Axial T1WI C+ MR in the same patient shows the antral , nasal , and nasopharyngeal components of the ACP Note that there is thin peripheral, but no central, enhancement of the lesion, which helps to distinguish it from a neoplasm P.IV(1):53 TERMINOLOGY Abbreviations Antrochoanal polyp (ACP) Synonyms Killian polyp Definitions ACP: Inflammatory polyp arising from maxillary sinus antrum, herniating through major or accessory ostium into nasal cavity ± prolapsing into nasopharynx Other solitary polyps named based upon site of origin → site of termination IMAGING 914 Diagnostic Imaging Head and Neck General Features Best diagnostic clue Dumbbell-shaped lesion with maxillary antral origin connected by narrow stalk from maxillary infundibulum/accessory ostium → nasal cavity Location Most common type: Antrochoanal polyp Solitary polypoid mass fills maxillary antrum, spills through enlarged maxillary ostium & infundibulum or accessory ostium into nasal cavity Large lesions extend through choana into nasopharyngeal airway Nasochoanal, sphenochoanal, frontochoanal, & ethmochoanal polyps are less common Size Typically large May reach cm in size Morphology Dumbbell-shaped polypoid mass Bulbous nasopharyngeal component in larger lesions Radiographic Findings Lateral radiography: Polypoid soft tissue density resting on nasal surface of soft palate surrounded by air CT Findings CECT Peripheral enhancement of surrounding mucosa with no central enhancement Bone CT Well-defined, dumbbell-shaped, low mucoid density mass Arises from maxillary antrum, extends through widened maxillary ostium or accessory ostium into ipsilateral nasal cavity Bone surrounding infundibulum/accessory ostium remodeled, not destroyed Stalk or midportion of dumbbell may be difficult to see on coronal sinus CT Large lesions extend into nasopharyngeal airway May have ↑ density centrally depending on chronicity ± fungal colonization MR Findings T1WI Low signal most common due to ↑ water content Variable signal intensity with chronicity T2WI High intensity polyp (near water intensity) T1WI C+ No enhancement of central portion of lesion Thin peripheral enhancement of mucosa Imaging Recommendations Best imaging tool If endoscopic examination clearly reveals ACP, unenhanced coronal bone CT alone may be sufficient Protocol advice Thin slice axial bone CT with coronal & sagittal reformats MR with contrast may be used in some cases to confirm polyp vs neoplasm DIFFERENTIAL DIAGNOSIS Nasal Glioma Intranasal type: Soft tissue mass in nasal cavity Maxillary antrum uninvolved except via secondary obstruction Tract through septum to skull base; rare in nasopharynx Frontoethmoid Cephalocele Nasoethmoidal type: Polypoid mass in nose Intracranial origin with connection to brain parenchyma Defect in cribriform plate Juvenile Angiofibroma Adolescent males with enhancing mass centered in posterior nasal cavity near sphenopalatine foramen Often extends into pterygopalatine fossa May obstruct maxillary sinus but only extends into this sinus when very large Sinonasal Inverted Papilloma Adult males with mass along lateral nasal wall near middle meatus 915 Diagnostic Imaging Head and Neck Often herniates into maxillary sinus causing ostiomeatal unit pattern of obstructive sinus opacification “Convoluted,” “cerebriform” architecture Esthesioneuroblastoma Diffusely enhancing mass in superior nasal cavity Aggressive, destructive lesion passes through cribriform plate into anterior cranial fossa Maxillary involvement unusual PATHOLOGY General Features Etiology Inflammatory polyp (retention cyst) of maxillary sinus resulting from edematous hypertrophy of respiratory epithelium rather than glandular distension Allergy & infection thought to play a role in etiology P.IV(1):54 ↓ lipoxygenase pathway products might be involved in pathogenesis Urokinase-type plasminogen activator and plasminogen activator may also have a role Passage of antral polyp into nose can occur via different routes Through maxillary infundibulum Through accessory ostium of maxillary sinus Sphenochoanal polyps route Sphenoid sinus → sphenoid ostium → sphenoethmoidal recess → choana → nasopharynx Associated abnormalities Postobstructive inflammatory disease Greater when ACP exits antrum via natural ostium vs accessory ostium Gross Pathologic & Surgical Features Glistening, pale, mucosa-covered, grape-like mass Superficially looks like any other nasal polyp Careful inspection reveals stalk leading laterally through maxillary sinus primary or accessory ostium Microscopic Features Edematous hypertrophy of respiratory epithelium of maxillary antrum No distention of mucous glands of sinus Loose mucoid stroma and mucous glands covered by respiratory epithelium Reactive atypical stromal cells or cysts may be seen Few inflammatory cells with no eosinophils CLINICAL ISSUES Presentation Most common signs/symptoms Unilateral nasal obstruction, worse on expiration When large, protrudes into nasopharyngeal airway May mimic nasopharyngeal tumor Other signs/symptoms Nasal discharge Mouth breathing, snoring with sleep apnea Cheek pain, sore throat, headache Clinical profile Teenager with unilateral nasal obstruction due to unilateral nasal polyp Rhinoscopic examination: Polyp occludes nasal airway Obstruction of nasopharynx may be clinically confused with primary nasopharyngeal tumor Demographics Age Most common in teenagers & young adults Mean age ≈ 10 years 2nd smaller group presents in 3rd-5th decades Gender Male > Female Epidemiology 4-6% of all sinonasal polyps Antrochoanal > > sphenochoanal > ethmochoanal polyp 916 Diagnostic Imaging Head and Neck Much more prevalent in pediatric population 40% of patients have allergies but no etiologic link to allergies Natural History & Prognosis Herniation of ACP into nasal cavity may take years to occur Surgical removal of both components creates a surgical cure If surgical removal of nasal portion of ACP is completed without removal of antral base, recurrence can be expected Mean time to recurrence: 45 months Treatment Complete surgical removal of nasal & antral components is treatment of choice Surgical procedures Intranasal avulsion, Caldwell-Luc antrostomy, & endoscopic removal through middle meatus Corticosteroids are ineffective DIAGNOSTIC CHECKLIST Consider Begin imaging evaluation with coronal bone CT If bone CT or endoscopy appearance is atypical, consider MR with contrast to rule out central enhancement (neoplasm) Image Interpretation Pearls Mucoid density/signal antrochoanal mass with thin rim of peripheral enhancement only is highly characteristic of ACP Do not mistake nasopharyngeal component for nasopharyngeal neoplasm Look for ipsilateral opacification of maxillary antrum even if stalk is difficult to see Differential diagnosis of ACP in atypical location on coronal sinus CT should include inverting papilloma SELECTED REFERENCES Frosini P et al: Antrochoanal polyp: analysis of 200 cases Acta Otorhinolaryngol Ital 29(1):21-6, 2009 Lee JY: Unilateral paranasal sinus diseases: analysis of the clinical characteristics, diagnosis, pathology, and computed tomography findings Acta Otolaryngol 128(6):621-6, 2008 Aydin O et al: Choanal polyps: an evaluation of 53 cases Am J Rhinol 21(2):164-8, 2007 Chung SK et al: Surgical, radiologic, and histologic findings of the antrochoanal polyp Am J Rhinol 16(2):71-6, 2002 Ozdek A et al: Antrochoanal polyps in children Int J Pediatr Otorhinolaryngol 65(3): 213-8, 2002 De Vuysere S et al: Sinochoanal polyp and its variant, the angiomatous polyp: MRI findings Eur Radiol 11(1): 55-8, 2001 Pruna X et al: Antrochoanal polyps in children: CT findings and differential diagnosis Eur Radiol 10(5):849-51, 2000 Weissman JL et al: Sphenochoanal polyps: evaluation with CT and MR imaging Radiology 178(1):145-8, 1991 Towbin R et al: Antrochoanal polyps AJR Am J Roentgenol 132(1):27-31, 1979 P.IV(1):55 Image Gallery (Left) Coronal bone CT shows an opacified left maxillary sinus The maxillary ostium is widened 917 , and a large Diagnostic Imaging Head and Neck solitary polyp extends through the ostium into the nasal cavity The polyp obstructs the middle meatus (Right) Sagittal T1WI MR shows a large intermediate signal polyp extending from the nasal cavity into the nasopharynx Note the high signal in the palate below the polyp The adenoidal tissue is slightly hyperintense compared to the polyp (Left) Axial bone CT shows the typical features of an ACP The right maxillary antrum is opacified , and there is a polypoid soft tissue mass extending into the nasal cavity Posteriorly the polyp protrudes through the choana into the nasopharynx (Right) Axial T2WI FS MR in a child shows a hyperintense ACP on the left The antral and nasopharyngeal components of the lesion are shown The ACP is hyperintense compared to the inferior turbinate (Left) Axial T2WI FS MR shows hyperintense signal throughout a large right ACP The right maxillary antrum is opacified, and the polyp extends through the nasal cavity into the nasopharynx Note the retention cyst in the left antrum (Right) Axial T1WI C+ FS MR shows a dumbbell-shaped nasochoanal polyp occluding the choanal openings and filling the nasopharynx Only peripheral enhancement is seen around the lesion Note the retention cysts in the maxillary antra Sinonasal Mucocele > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Sinonasal Mucocele Sinonasal Mucocele Michelle A Michel, MD Key Facts 918 Diagnostic Imaging Head and Neck Imaging Opacified, expanded sinus with smooth remodeling of walls May occur in septated sinuses & pneumatized anatomic variant air cells Frontal (60-65%) > ethmoid (25%) > maxillary (5-10%) > sphenoid (2-5%) CT: Thin section CT with coronal & sagittal reformat helpful for surgical planning and delineation of adjacent normal anatomy Low-density or soft tissue density opacification of sinus with expansion Bony sinus walls remodeled No central enhancement; ± minimal peripheral enhancement MR: Enhanced MR recommended for detection of intracranial involvement & identifying obstructing neoplasm as underlying cause High water content of mucous interior yields ↓ T1 signal, ↑ T2 signal Top Differential Diagnoses Allergic fungal sinusitis Sinonasal polyposis Sinonasal solitary polyps Pathology Results from obstruction of primary ostium of affected sinus Clinical Issues Most common expansile lesion of paranasal sinuses Slowly progressive symptoms that vary depending upon lesion location without signs of acute infection > 90% have ophthalmic symptoms & signs Surgical cure is goal & expected result when mucocele is present (Left) Coronal graphic shows a large left anterior ethmoid mucocele extending into the left frontal sinus The affected sinuses are expanded without evidence of aggressive bone destruction (Right) Coronal bone CT shows the typical features of a right ethmoid mucocele The sinus is opacified, and there is remodeling of the surrounding bony walls with erosion of the lamina papyracea Note the mass effect upon the orbit with lateralization of the globe 919 Diagnostic Imaging Head and Neck (Left) Axial FLAIR MR in a patient with proptosis and diplopia shows a homogeneous, expansile left ethmoid mucocele Note that the material within the mucocele is hyperintense compared to CSF This likely reflects the high protein content within the mucocele (Right) Sagittal T1 C+ MR in the same patient demonstrates increased T1 signal in the mucocele, likely related to elevated protein content There is no enhancement within the mucocele, only minimal peripheral enhancement P.IV(1):57 TERMINOLOGY Definitions Opacified, mucous-containing, expanded sinus, lined by respiratory epithelium, resulting from chronic major ostial obstruction From the Latin “muco” = mucus + Greek “kele” = tumor or “mucous tumor” IMAGING General Features Best diagnostic clue Opacified, expanded sinus with smooth remodeling of walls Location > 90% in frontal & ethmoid sinuses Frontal (60-65%) > ethmoid (25%) > maxillary (5-10%) > sphenoid (2-5%) May occur in septated sinuses & pneumatized anatomic variant air cells Ethmoid mucoceles have greatest potential for intraorbital extension Sphenoid mucoceles have greatest potential for intracranial extension Morphology Frontal mucocele: Expands anteriorly into skin of forehead or posteriorly into anterior cranial fossa Ethmoid mucocele: Thins & remodels lamina papyracea (lateral ethmoid air cell wall), bowing it into orbit Maxillary mucocele: Expands into ipsilateral nasal cavity, usually in area of secondary ostium of maxillary sinus or into premaxillary soft tissues Sphenoid sinus mucocele: Expands anterolaterally into posterior ethmoids & orbital apex Radiographic Findings Radiography Frontal & maxillary sinus mucocele can be suggested from plain film findings “Clouding” of expanded sinus with loss of normal mucoperiosteal line of sinus wall Ethmoid & sphenoid mucocele may be missed CT Findings CECT No central enhancement; ± minimal peripheral enhancement Thick peripheral enhancement raises suspicion of superinfection (mucopyocele) Bone CT Low-density or soft tissue density opacification of sinus with expansion 920 Diagnostic Imaging Head and Neck High-density areas related to desiccation of secretions or fungal colonization Bony sinus walls remodeled May be thinned, focally absent, or normal thickness MR Findings T1WI High water content of mucous interior yields ↓ T1 signal When protein content high, ↑ T1 signal T2WI High water content of mucous interior yields ↑ T2 signal When areas of inspissated mucus exist, may be very low signal T1WI C+ No central enhancement; ± minimal peripheral enhancement Thickened peripheral mucosa suggests infected mucocele (mucopyocele) If associated nodule of enhancement is seen, consider tumor obstruction of sinus with secondary mucocele MRS N-acetyl compounds (N-acetylglucosamine, N-acetylgalactosamine) may cause peak at 2.0 ppm, mimicking brain N-acetylaspartate Imaging Recommendations Best imaging tool Small mucocele may require only unenhanced coronal bone CT Larger mucocele with significant regional compression may benefit from enhanced MR with bone-only CT in axial and coronal planes Protocol advice Thin section CT with coronal & sagittal reformat helpful for surgical planning and delineation of adjacent normal anatomy Enhanced MR recommended for detection of intracranial involvement & identifying obstructing neoplasm as cause of mucocele DIFFERENTIAL DIAGNOSIS Allergic Fungal Sinusitis Typically expansile, especially if seen with polyps Involves multiple sinuses High central density on CT; mixed MR signal Sinonasal Polyposis Involves multiple sinuses and nasal cavity May have multiple small mucoceles associated Sinonasal Solitary Polyps “Dumbbell” cystic mass that fills maxillary antrum, herniates through sinus ostium into adjacent nasal cavity Slow-Growing Benign or Malignant Tumor May mimic mucocele when seen on bone/unenhanced CT Central, nodular enhancement on CT/MR differentiates from mucocele PATHOLOGY General Features Etiology Results from obstruction of primary ostium of affected sinus Obstruction from inflammation, trauma, functional endoscopic sinus surgery, or any spaceoccupying, sinonasal mass P.IV(1):58 Secretion of mucus into obstructed sinus creates mucocele Sinus expansion from pressure necrosis with slow erosion of inner surface of bony sinus wall matched by new bone formation on outer periosteal surface Associated abnormalities Obstructing mass at ostium may cause secondary mucocele Staging, Grading, & Classification types Internal: Herniation of cyst into submucosal tissue adjacent to sinus bony wall 921 Diagnostic Imaging Head and Neck External: Herniation of cyst through bony wall with extension into subcutaneous tissue or intracranial cavity Gross Pathologic & Surgical Features Mucocele lumen filled with thick mucoid or gelatinous secretions Microscopic Features Histologically indistinguishable from polyps & retention cysts Flattened, pseudostratified, ciliated columnar epithelium = mucous-secreting respiratory epithelium Squamous metaplasia can be seen in longstanding cases Retained mucous secretions are sterile Purulent exudate present in cases of mucopyocele Reactive bone formation or bony remodeling of adjacent sinus walls may be present CLINICAL ISSUES Presentation Most common signs/symptoms > 90% have ophthalmic signs & symptoms Principal presenting symptoms depend on site of involvement Frontal mucocele: Forehead bossing, proptosis, diplopia, and mass in superomedial orbit Ethmoid mucocele: Proptosis, blurred vision ± visual loss, periorbital swelling Maxillary mucocele: Nasal obstruction from medial projection with cheek pressure, rhinorrhea Sphenoid mucocele: Visual loss, oculomotor palsy, headache Other signs/symptoms Epiphora, decreased color vision, hypoglobus (downward displaced eye) If pain present, consider mucopyocele Clinical profile Slowly progressive symptoms that vary depending upon lesion location without signs of acute infection Diagnosis requires correlation between clinical, radiographic, and pathologic findings as diagnosis on histopathology alone can be difficult Demographics Age Most common in adults Occurs in all age groups In children, look for obstructing mass or underlying disorder (cystic fibrosis, immotile cilia syndrome) Epidemiology Most common expansile lesion of paranasal sinuses Although rare, sphenoid mucocele has highest complication rate due to proximity of vital structures Natural History & Prognosis Gradual, clinically silent enlargement over months to years Cranial neuropathy (CN2-6) may not recover following surgery if chronic at time of presentation Complications in untreated cases Include superimposed infection (mucopyocele), meningitis ± brain abscess Treatment Surgical cure is goal & expected result when mucocele is present Endoscopic sinus surgery Reserved for uncomplicated maxillary or ethmoid mucocele Most frontal mucoceles treated with osteoplastic flap ± obliteration Transfacial surgical approaches Reserved for deeper posterior ethmoid or sphenoid mucocele Transcranial surgical approach Reserved for mucoceles with intracranial extension or causing compression of bone structures with optic pathway neurological symptoms DIAGNOSTIC CHECKLIST Consider Extensive peripheral enhancement may suggest mucopyocele If central enhancement present, consider neoplasm Image Interpretation Pearls Look for thin peripheral rim of expanded bone No central enhancement on post-contrast CT or MR SELECTED REFERENCES Lee TJ et al: Extensive paranasal sinus mucoceles: a 15-year review of 82 cases Am J Otolaryngol 30(4):234-8, 2009 922 Diagnostic Imaging Head and Neck Herndon M et al: Presentation and management of extensive fronto-orbital-ethmoid mucoceles Am J Otolaryngol 28(3):145-7, 2007 Landsberg R et al: Magnetic resonance imaging—aided navigation in endoscopic sinus surgery of a bone-destructive sphenoclinoid mucocele Ann Otol Rhinol Laryngol 112(8):740-4, 2003 Lloyd G et al: Optimum imaging for mucoceles J Laryngol Otol 114(3): 233-6, 2000 Busaba NY et al: Maxillary sinus mucoceles: clinical presentation and long-term results of endoscopic surgical treatment Laryngoscope 109(9): 1446-9, 1999 Van Tassel P et al: Mucoceles of the paranasal sinuses: MR imaging with CT correlation AJR Am J Roentgenol 153(2):407-12, 1989 Hesselink JR et al: Evaluation of mucoceles of the paranasal sinuses with computed tomography Radiology 133(2):397-400, 1979 P.IV(1):59 Image Gallery (Left) Axial bone CT demonstrates a posterior ethmoid mucocele that extends into the sphenoid sinuses rather then into the orbit The bone surrounding the lesion is thinned and remodeled (Right) Coronal bone CT shows a large mucocele arising within the right maxillary sinus, an unusual location for a mucocele The lesion occludes the nasal airway Note the changes of chronic sinusitis of the left maxillary sinus with decreased volume and thickening of the walls (Left) Axial T2WI FS MR shows a large right frontal mucocele containing a fluid-fluid level with material of varying signal intensities This mucocele extended into the superficial soft tissues , causing swelling and edema (Right) 923 Diagnostic Imaging Head and Neck Axial T1WI C+ FS MR in the same patient shows superficial soft tissue swelling and enhancement over the ruptured mucocele There is also enhancement of the dura in the anterior fossa consistent with early meningeal inflammation (Left) Axial T1WI C+ FS MR shows a mucocele of the right maxillary sinus with erosion of the anterior wall and extension into the nasal cavity There is peripheral mucosal enhancement but no central enhancement This helps distinguish a mucocele from a neoplasm (Right) Axial T1WI MR demonstrates a large mucocele of the left sphenoid sinus The lesion is homogeneously hyperintense, likely related to highly proteinaceous contents Note the involvement of the lateral recess Silent Sinus Syndrome > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Silent Sinus Syndrome Silent Sinus Syndrome Michelle A Michel, MD Key Facts Terminology Painless involution of maxillary sinus after occlusion of infundibulum with associated enophthalmos a.k.a maxillary atelectasis with enophthalmos, “imploding antrum” Imaging Diminished volume of maxillary antrum with retraction (concavity) of all walls Increase in ipsilateral orbital volume with inferior position of orbital floor Lateralized uncinate & expanded middle meatus Opacification of affected sinus Top Differential Diagnoses Maxillary sinus hypoplasia Post-traumatic or surgical change Pathology Chronic antral obstruction & hypoventilation → stagnant mucus fills sinus → osteolysis thins bony walls → negative pressure retracts bony walls Clinical Issues Adult with painless enophthalmos or facial asymmetry ± diplopia Symptoms of chronic sinusitis are typically absent (“silent”) Disease progress halted after restoration of sinus drainage Diagnostic Checklist Look for extent of pneumatization into malar eminence & superior alveolus to differentiate SSS from hypoplasia SSS: Antrum fully pneumatized Sinus hypoplasia: Not fully pneumatized 924 Diagnostic Imaging Head and Neck (Left) Coronal bone CT in a patient with painless enophthalmos shows opacification of the right maxillary sinus with slight thickening of the lateral wall The orbital floor is inferior in position with increased orbital volume, which is characteristic of silent sinus syndrome (Right) Coronal NECT shows the typical features of SSS with decreased volume of the right maxillary sinus and inferior position of the orbital floor Increased density and chronic secretions are noted in the sinus (Left) Coronal bone CT shows the characteristic features of silent sinus syndrome The volume of the opacified right maxillary antrum is diminished The orbital floor is inferiorly positioned with increase in overall orbital volume, which leads to enophthalmos (Right) Coronal T1WI C+ MR in a patient with enophthalmos on the right side shows decreased volume of the maxillary sinus , which is opacified with inspissated material The orbital floor on that side is depressed P.IV(1):61 TERMINOLOGY Abbreviations Silent sinus syndrome (SSS) Synonyms Maxillary atelectasis with enophthalmos Imploding antrum Definitions Painless involution of maxillary sinus after occlusion of infundibulum with associated enophthalmos IMAGING General Features 925 Diagnostic Imaging Head and Neck Best diagnostic clue Retraction of maxillary sinus walls with diminished sinus volume Location Maxillary sinus Size Diminished volume of maxillary antrum Morphology Inward bowing of all or most antral walls CT Findings Bone CT Diminished volume of maxillary antrum with retraction (concavity) of all walls Compensatory increase in ipsilateral orbital volume with inferior position of orbital floor Near to complete opacification of affected sinus Lateralized uncinate & expanded middle meatus with variable retraction of middle turbinate & nasal septal deviation Demineralization of sinus walls MR Findings T1WI Opacified sinus with mixed signal contents & diminished volume Typically ↑ signal due to ↑ protein Prominence of inferior extraconal orbital fat T2WI Mixed signal central secretions with ↑ signal peripheral mucosa Imaging Recommendations Best imaging tool Coronal bone CT of sinuses DIFFERENTIAL DIAGNOSIS Maxillary Sinus Hypoplasia Incomplete pneumatization into malar eminence & maxillary alveolar ridge Sinus may be aerated Post-traumatic or Surgical Change Look for surgical changes or fractures Sinus may not have mucosal disease PATHOLOGY General Features Etiology Chronic antral obstruction with hypoventilation → stagnant mucus fills sinus → osteolysis thins & remodels bony walls → walls pulled into sinus by negative pressure Associated abnormalities Ipsilateral enophthalmos Gross Pathologic & Surgical Features Thin or absent orbital floor bone, mucoid material in maxillary sinus, edematous sinus mucosa Microscopic Features Similar to chronic sinusitis with inflammatory debris, but cultures typically negative CLINICAL ISSUES Presentation Most common signs/symptoms Eye asymmetry or “sagging,” diplopia, enophthalmos Symptoms of chronic rhinosinusitis (CRS) typically absent (i.e., “silent”) Other signs/symptoms Hypoglobus, malar depression, upper lid retraction, vague dental or facial pain Widened middle meatus with retracted uncinate process on nasal endoscopy Clinical profile Adult with painless enophthalmos or facial asymmetry ± diplopia with no history of prior trauma Demographics Age Adults: 25-75 years Treatment FESS & transconjunctival reconstruction of orbital floor 926 Diagnostic Imaging Head and Neck DIAGNOSTIC CHECKLIST Image Interpretation Pearls Look for extent of pneumatization into malar eminence & superior alveolus to differentiate SSS from hypoplasia SSS: Antrum fully pneumatized Sinus hypoplasia: Not fully pneumatized SELECTED REFERENCES Yousuf K et al: Silent sinus syndrome: case series and literature review J Otolaryngol Head Neck Surg 38(5):E110-3, 2009 Hourany R et al: Silent sinus syndrome: an acquired condition AJNR Am J Neuroradiol 26(9):2390-2, 2005 Illner A et al: The silent sinus syndrome: clinical and radiographic findings AJR Am J Roentgenol 178(2):503-6, 2002 Sinonasal Wegener Granulomatosis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Sinonasal Wegener Granulomatosis Sinonasal Wegener Granulomatosis Michelle A Michel, MD Key Facts Terminology Idiopathic necrotizing granulomatous vasculitis that preferentially involves upper & lower respiratory tracts, kidneys, skin, & joints Imaging Nodular soft tissue in nose with septal & nonseptal bone destruction Orbital invasion most common extrasinonasal H&N site Coronal bone CT is best tool for initial evaluation Top Differential Diagnoses Sinonasal sarcoidosis Nasal cocaine necrosis Chronic rhinosinusitis Invasive fungal sinusitis Sinonasal non-Hodgkin lymphoma Clinical Issues H&N involvement in 72-100% of WG patients Rhinologic symptoms in > 80% Symptoms mimic chronic rhinosinusitis (CRS) Nasal obstruction & epistaxis Diagnosis often delayed because symptoms mistaken for CRS Typically 40-60 years & M > F Generally indolent but may transition to fulminating disease Diagnostic Checklist Consult with clinician for history of other organ system involvement (WG vs sarcoidosis) or cocaine abuse Can be impossible to differentiate from sinonasal sarcoidosis or lymphoma on imaging 927 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows the classic features of sinonasal involvement by Wegener granulomatosis Nodular soft tissue is seen in the nasal cavity with an associated septal perforation (Right) Coronal bone CT shows extensive thickening and sclerosis of the maxillary sinus walls consistent with a chronic inflammatory process Soft tissue lines the nasal cavity, and the inferior turbinates have been destroyed by the granulomatous disease (Left) Coronal bone CT in a case with severe sinonasal Wegener disease shows extensive soft tissue thickening in the maxillary and ethmoid sinuses and nasal cavity The nasal septum , inferior and middle turbinates, and multiple ethmoid septations are destroyed (Right) Axial STIR MR shows hyperintense soft tissue filling the maxillary and sphenoid sinuses There is complete destruction of the nasal septum Thickening of the sinus walls is difficult to appreciate on the MR P.IV(1):63 TERMINOLOGY Abbreviations Wegener granulomatosis (WG) Definitions Idiopathic necrotizing granulomatous vasculitis that preferentially involves upper & lower respiratory tracts, kidneys, skin, & joints IMAGING General Features Best diagnostic clue Nodular soft tissue in nose with septal & nonseptal bone destruction Location Nasal cavity (septum > turbinates) > sinuses (maxillary > ethmoid > frontal > sphenoid) Other H&N sites Orbital invasion most common extrasinonasal site Nasopharynx, subglottic larynx, oral cavity, temporal bone, & salivary glands Morphology Ulcerative ± nodular disease CT Findings NECT Nodular soft tissue masses centered in nasal cavity with associated chronic paranasal sinus inflammatory changes Periantral soft tissue infiltration Orbital extension often 1st extrasinonasal site of invasion Less commonly involves infratemporal fossa, nasopharynx, skull base CECT Inflamed nodular masses & mucosa enhance Bone CT Nasal septal perforation common Punctate foci of bone demineralization 928 Diagnostic Imaging Head and Neck Along pathways of perforating arteries indicative of vasculitis Turbinates & lateral nasal wall destruction (uncinate process & medial wall maxillary sinus) May extend through hard palate leading to sinonasal-oral fistula Chronic obstruction & inflammation of adjacent sinuses may result in bone thickening & sclerosis MR Findings T1WI Low to intermediate signal nodular masses T2WI ↓ signal nodular masses (compared to inflamed mucosa = ↑ T2 signal) ↑ signal edema of soft tissues during acute exacerbations with extension into adjacent soft tissues T1WI C+ Homogeneous enhancement Meningeal thickening with enhancement < 5% (late finding in those with skull base invasion) Imaging Recommendations Best imaging tool Bone-only coronal sinus CT is best tool for initial evaluation Axial MDCT with reformats also very helpful for identifying bone erosion Protocol advice If orbital, deep facial, skull base, or meningeal involvement suspected from CT or clinical symptoms → enhanced, fat-saturated MR DIFFERENTIAL DIAGNOSIS Sinonasal Sarcoidosis Systemic granulomatous disease Sinonasal involvement less common than WG More common in African-Americans May be indistinguishable from WG on imaging Nasal Cocaine Necrosis Septal perforation with nasal inflammatory changes May be less nodular than WG Chronic Rhinosinusitis Symptoms of WG mimic chronic sinusitis Bone thickening & sclerosis not destruction No systemic disease Invasive Fungal Sinusitis Rapidly progressive sinonasal destructive process in immunocompromised patient Sinus > nasal cavity is site of origin; destroys any adjacent bone Sinonasal Non-Hodgkin Lymphoma Midline soft tissue mass with septal & nonseptal bone destruction or remodeling NK-T cell type lymphoma (a.k.a “lethal midline granuloma”) May exactly mimic WG on imaging PATHOLOGY General Features Etiology Autoimmune disease in which antineutrophil cytoplasmic antibodies (ANCA) target proteinase 3, primarily expressed in neutrophils Initiates inflammatory reaction leading to endothelial damage & necrotizing granulomatous vasculitis Associated abnormalities Secondary sinus bacterial infections common (e.g., Staphylococcus aureus) Other organ system involvement Lungs (95%), kidneys (85%), joints (65%) Intracranial abnormalities include meningeal enhancement & brain infarcts Gross Pathologic & Surgical Features Initial appearance: Diffuse mucosal ulcerations with crusting P.IV(1):64 Advanced disease: Septal perforation leads eventually to “saddle nose” deformity from underlying bony collapse Microscopic Features 929 Diagnostic Imaging Head and Neck Noncaseating, necrotizing, multinucleated & giant cell granulomas Acute ± chronic inflammatory cell infiltrate Fibrinoid necrosis of small- to medium-sized vessels CLINICAL ISSUES Presentation Most common signs/symptoms Nasal obstruction & epistaxis Symptoms mimic chronic rhinosinusitis Other signs/symptoms Pain, anosmia, purulent rhinorrhea Septal ulcerations & perforation can lead to “saddle nose” deformity Hoarseness (larynx), stridor (trachea), hearing loss & ear pain (T-bone) Constitutional symptoms: Fatigue, night sweats, weight loss Clinical profile Classic clinical triad Necrotizing granulomas of upper & lower respiratory tracts Necrotizing vasculitis of both arteries and veins Glomerulonephritis Diagnosis made by biopsy of affected area (nose, sinus, lung, kidney) Multiple biopsies may be inconclusive Nasal biopsies positive in approximately 40% Laboratory findings ↑ c-ANCA (85-98% specificity for Wegener) c-ANCA titers followed for disease response to therapy ↑ erythrocyte sedimentation rate (ESR) ↑ serum creatinine signals presence of renal WG Demographics Age Typically 40-60 years Gender M > F (except laryngeal form [M < F]) May be slightly more prevalent in women when presenting at younger age Epidemiology Rare disease H&N involvement in 72-100% Rhinologic symptoms in > 80% Natural History & Prognosis 3-year lag in diagnosis common because initially mistaken for chronic sinusitis Better prognosis if diagnosed at younger age Generally indolent disease “Limited disease,” localized to nose or orbit Treated appropriately, associated with good to excellent prognosis May transition to fulminating fatal disease Fulminant sinonasal disease may result in complete nasal destruction (autorhinectomy) Untreated, aggressive disease can be fatal secondary to renal failure or sepsis (major cause of morbidity & mortality) Long-term remissions have been achieved Length of remission difficult to predict Spontaneous remissions have been reported Treatment Medical treatments include immunosuppressive agents, cyclophosphamide, & other cytotoxic drugs Fulminant disease treated with high-dose prednisone followed by cyclophosphamide Surgery reserved for selected head & neck manifestations, such as “saddle nose” deformity & subglottic stenosis Surgical manipulation may exacerbate neo-osteogenesis in sinonasal cavities DIAGNOSTIC CHECKLIST Consider WG should be considered when destructive process centered in nasal cavity, particularly when septal perforation is present Consult with clinician for history of other organ system involvement (WG vs sarcoidosis) or cocaine abuse 930 Diagnostic Imaging Head and Neck Image Interpretation Pearls Can be impossible to differentiate from sinonasal sarcoidosis or lymphoma on imaging SELECTED REFERENCES Cannady SB et al: Sinonasal Wegener granulomatosis: a single-institution experience with 120 cases Laryngoscope 119(4):757-61, 2009 Fuchs HA et al: Granulomatous disorders of the nose and paranasal sinuses Curr Opin Otolaryngol Head Neck Surg 17(1):23-7, 2009 Grindler D et al: Computed tomography findings in sinonasal Wegener's granulomatosis Am J Rhinol Allergy 23(5):497-501, 2009 Erickson VR et al: Wegener's granulomatosis: current trends in diagnosis and management Curr Opin Otolaryngol Head Neck Surg 15(3):170-6, 2007 Srouji IA et al: Patterns of presentation and diagnosis of patients with Wegener's granulomatosis: ENT aspects J Laryngol Otol 121(7):653-8, 2007 Lohrmann C et al: Sinonasal computed tomography in patients with Wegener's granulomatosis J Comput Assist Tomogr 30(1):122-5, 2006 Benoudiba F et al: Sinonasal Wegener's granulomatosis: CT characteristics Neuroradiology 45(2): 95-9, 2003 Gubbels SP et al: Head and neck manifestations of Wegener's granulomatosis Otolaryngol Clin North Am 36(4): 685-705, 2003 Marsot-Dupuch K et al: Wegener granulomatosis involving the pterygopalatine fossa: an unusual case of trigeminal neuropathy AJNR Am J Neuroradiol 23(2): 312-5, 2002 10 Borges A et al: Midline destructive lesions of the sinonasal tract: simplified terminology based on histopathologic criteria AJNR Am J Neuroradiol 21(2): 331-6, 2000 11 Drake-Lee AB et al: A review of the role of radiology in non-healing granulomas of the nose and nasal sinuses Rhinology 27(4):231-6, 1989 12 Paling MR et al: Paranasal sinus obliteration in Wegener granulomatosis Radiology 144(3):539-43, 1982 P.IV(1):65 Image Gallery (Left) Axial bone CT shows extensive nodular soft tissue filling the nasal cavity with opacification of the maxillary sinuses A septal perforation is present, and there is thickening and sclerosis of the sinus walls , all findings consistent with Wegener granulomatosis (Right) Axial bone CT in an advanced case of WG shows destruction of the bony anatomy of the nasal cavity including the septum The maxillary sinuses are obliterated by thickened bone 931 Diagnostic Imaging Head and Neck (Left) Axial NECT shows destruction of the superior nasal septum, ethmoid septations, and the lamina papyracea bilaterally In this case there is bilateral orbital involvement by the granulomatous disease (Right) Coronal T1WI MR in the same patient again shows the loss of normal nasal anatomy and thickening of the maxillary walls The fat planes between the abnormal soft tissue and the medial rectus and superior oblique muscles are obscured (Left) Axial T1WI MR shows unilateral involvement of the right maxillary sinus with WG There is extension beyond the sinus lumen into the masticator space Note the replacement of the normal retroantral fat signal compared to the normal left side (Right) Axial T1WI FS MR in the same patient shows enhancement of the abnormal retroantral soft tissue and the pterygopalatine fossa Note the normal suppression of fat on the left Nasal Cocaine Necrosis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Infectious and Inflammatory Lesions > Nasal Cocaine Necrosis Nasal Cocaine Necrosis Michelle A Michel, MD Key Facts Terminology Destruction of osteocartilaginous structures of nose, sinuses, and palate induced by chronic inhalation of cocaine Imaging Perforation of osteocartilaginous nasal septum ± turbinates/palate without soft tissue mass 75% occur in quadrangular cartilage; 25% involve vomer-perpendicular ethmoidal lamina Thin section CT with multiplanar reformat recommended to fully delineate extent of bone destruction Top Differential Diagnoses 932 Diagnostic Imaging Head and Neck Traumatic nasal septal perforation Sinonasal Wegener granulomatosis Sinonasal sarcoidosis Sinonasal non-Hodgkin lymphoma Pathology Nasal septal destruction results from combined effects of chemical irritation, ischemic necrosis from vasoconstriction, & direct trauma from autoinstrumentation Clinical Issues Nasal obstruction & discharge are most common symptoms of acquired septal lesions Extension to inferior (68%), middle (44%), & superior (16%) turbinates in large study ˜ 1.75 million Americans ≥ 12 years old are regular (at least once per month) cocaine users Prevalence of cocaine-induced sinonasal complications ˜ 5% Septal perforation most common complication occurring in 4.8% of abusers (Left) Axial bone CT in a patient with a history of chronic cocaine inhalation shows a very large nasal septal perforation Scarring with adhesion formation is noted between the lateral nasal wall and septum posteriorly on the left (Right) Coronal CT reconstruction demonstrates a large defect in the nasal septum related to cocaine necrosis Note that the concha of the middle and inferior turbinates have been eroded and are absent (Left) Axial bone CT in a severe case of NCN shows complete erosion of the nasal septum The lateral nasal walls are also involved Extensive osteitis of the remaining antral walls is seen from chronic maxillary inflammation (Right) Coronal T1WI MR in the same patient again demonstrates the large nasal septal perforation as well as ethmoid involvement Inflamed, thickened mucosa lines the walls of the sinuses P.IV(1):67 933 Diagnostic Imaging Head and Neck TERMINOLOGY Abbreviations Nasal cocaine necrosis (NCN) Synonyms Cocaine-induced midline destructive lesions (CIMDL) Definitions Destruction of osteocartilaginous structures of nose, sinuses, and palate induced by chronic inhalation of cocaine IMAGING General Features Best diagnostic clue Perforation of osteocartilaginous nasal septum ± turbinates/palate without soft tissue mass Location Nasal septal mucosa and cartilage Imaging Recommendations Best imaging tool Bone CT optimal for evaluating extent of bone destruction CT Findings Bone CT Nasal septum erosion Erosion of portions of or both inferior turbinates in > 50% Bone destruction may extend to lateral nasal wall, palate, or orbit DIFFERENTIAL DIAGNOSIS Traumatic Nasal Septal Perforation Septal necrosis secondary to hematoma in cartilaginous septum leading to ischemia Rhinotillexomania (chronic nose picking) causes septal injury due to repetitive trauma/inflammation Imaging findings include septal perforation, absence of anterior/inferior septum Wegener Granulomatosis, Sinonasal Necrotizing granulomatous vasculitis Nodular soft tissue lesions Predilection for nasal septum and turbinates Sarcoidosis, Sinonasal Systemic granulomatous disease (less frequent sinonasal involvement than Wegener) Predilection for nasal septal & inferior turbinate involvement Non-Hodgkin Lymphoma, Sinonasal Predilection for nasal cavity site of origin with frequent destruction of septum Large soft tissue mass in nasal cavity Fungal Sinusitis, Invasive Occurs in immunocompromised population Maxillary and sphenoid sinuses more common location of origin than nasal cavity PATHOLOGY General Features Etiology Nasal septal destruction results from combined effects of chemical irritation, ischemic necrosis from vasoconstriction, & direct trauma from auto-instrumentation Perforation results with chronic (> months) of intranasal use Staging, Grading, & Classification Diagnosis can be made by identifying cocaine metabolites in urine Gross Pathologic & Surgical Features Atrophic, irritated mucosa with necrosis Microscopic Features Ranges from fibrosis with mild inflammation & necrosis to dense inflammatory infiltrate with extensive necrosis CLINICAL ISSUES Presentation Most common signs/symptoms Nasal obstruction & discharge are most common symptoms of acquired septal lesions Demographics Age 934 Diagnostic Imaging Head and Neck Adolescent to adult age groups Gender Males > females Epidemiology ˜ 1.75 million Americans ≥ 12 years old are regular (at least once per month) cocaine users Prevalence of cocaine-induced sinonasal complications ˜ 5% Natural History & Prognosis Continued intranasal cocaine use may result in disintegration of nasal cartilage and loss of structural integrity Chronic osteolytic sinusitis and erosion into orbits is a late complication DIAGNOSTIC CHECKLIST Consider Clinical history of cocaine use is key to diagnosis SELECTED REFERENCES Valencia MP et al: Congenital and acquired lesions of the nasal septum: a practical guide for differential diagnosis Radiographics 28(1):205-24; quiz 326, 2008 Westreich RW et al: Midline necrotizing nasal lesions: analysis of 18 cases emphasizing radiological and serological findings with algorithms for diagnosis and management Am J Rhinol 18(4):209-19, 2004 Trimarchi M et al: Sinonasal osteocartilaginous necrosis in cocaine abusers: experience in 25 patients Am J Rhinol 17(1):33-43, 2003 Benign Tumors and Tumor-like Lesions Sinonasal Fibrous Dysplasia > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Benign Tumors and Tumorlike Lesions > Sinonasal Fibrous Dysplasia Sinonasal Fibrous Dysplasia Michelle A Michel, MD Key Facts Terminology Fibro-osseous lesion in which normal medullary bone is replaced by weak osseous & fibrous tissue Imaging Classic appearance: “Ground-glass” density Density varies with amount of fibrous tissue (areas of soft tissue density) Variable enhancement of fibrous component Ill-defined expansion of diploic space Top Differential Diagnoses Ossifying fibroma Osteoma Neo-osteogenesis Pathology Etiology of FD remains obscure Can obstruct sinus → recurrent infection, mucocele formation forms of FD: Monostotic, polyostotic, & McCune-Albright syndrome Clinical Issues Many cases are asymptomatic Common symptoms: Painless swelling, sinus or nasal obstruction Monostotic form most common with H&N involvement in 25% Highest incidence 3-15 years Disease becomes quiescent with cessation of skeletal growth Diagnostic Checklist MR appearance can be somewhat confusing CT very helpful for problem solving in such cases 935 Diagnostic Imaging Head and Neck (Left) Axial bone CT demonstrates the classic features of fibrous dysplasia There is marked expansion of the left maxillary sinus walls with asymmetry of projection of the left cheek This case shows the typical “ground-glass” appearance of this entity Note the markedly decreased antral volume (Right) Coronal bone CT shows fibrous dysplasia involving the concha of the right inferior turbinate and lateral nasal wall The concha is markedly expanded with “ground-glass” density (Left) Coronal bone CT shows extensive fibrous dysplasia involving the orbit, crista galli , ethmoids, and middle turbinate on the right The nasal septum is deviated toward the left (Right) Axial T2WI MR in the same patient shows marked hypointense signal in the involved bones In this case, the lesion is homogeneous consistent with the “ground-glass” appearance on CT If more fibrous tissue were present, foci of higher long TR signal would be expected P.IV(1):69 TERMINOLOGY Abbreviations Fibrous dysplasia (FD) Synonyms Lichtenstein-Jaffe disease, leontiasis ossea, cherubism Definitions Fibro-osseous lesion in which normal medullary bone is replaced by weak osseous & fibrous tissue IMAGING General Features 936 Diagnostic Imaging Head and Neck Best diagnostic clue Ill-defined expansion of diploic space with “ground-glass” density Location Maxilla > mandible > frontal bone > ethmoid & sphenoid bones > T-bone Size Expansile Morphology Generally ill defined CT Findings CECT Variable enhancement of fibrous component Bone CT Classic appearance: “Ground-glass” density Density varies with amount of fibrous tissue (areas of soft tissue density) Expanded bone with rim of intact cortex MR Findings T1WI Expanded, intermediate signal diploic space Hypointense peripheral cortical bone T2WI Intermediate to hypointense “Ground-glass” = ↓ signal; fibrous tissue = intermediate to ↑ signal T1WI C+ Homogeneous or heterogeneous Fibrous component may enhance intensely Nuclear Medicine Findings PET Can be variably hot on FDG PET Imaging Recommendations Best imaging tool Bone algorithm CT DIFFERENTIAL DIAGNOSIS Sinonasal Ossifying Fibroma Solitary, well defined, expansile Mixed bone & soft tissue density Sinonasal Osteoma Solitary, well defined; projects into sinus lumen Densely ossified Neo-osteogenesis Slightly thickened, sclerotic sinus walls Near site of surgery or chronic inflammation PATHOLOGY General Features Etiology Etiology of FD remains obscure Developmental anomaly of mesenchymal precursor of bone in which normal medullary bone is replaced by weak osseous & fibrous tissue Genetics Cherubism: Autosomal dominant Associated abnormalities Can cause sinus obstruction → recurrent infection, mucocele formation, nasal airway obstruction Gross Pathologic & Surgical Features Tan-white to yellow, soft, rubbery, gritty or firm tissue Microscopic Features Immature (woven) poorly organized osseous component arises metaplastically from fibrous stroma CLINICAL ISSUES Presentation Most common signs/symptoms Painless swelling, sinus or nasal obstruction 937 Diagnostic Imaging Head and Neck Demographics Age 75% < 30 years Gender M < F in polyostotic form (1:3) Epidemiology Monostotic (70-80%): H&N involved in 25% Polyostotic (20-30%): Bones of H&N involved in ≥ 50% McCune-Albright syndrome (3-10%) Natural History & Prognosis Disease becomes quiescent with cessation of skeletal growth Malignant transformation (< 1%); > in polyostotic form Treatment Therapy delayed until after puberty Surgical excision if functional compromise, progressive deformity Radiation therapy not effective & ↑ risk of malignant transformation SELECTED REFERENCES MacDonald-Jankowski DS: Fibro-osseous lesions of the face and jaws Clin Radiol 2004 Jan;59(1):11-25 Review Erratum in: Clin Radiol 64(1):107, 2009 Cappabianca S et al: Maxillofacial fibrous dysplasia: personal experience with gadoliniumenhanced magnetic resonance imaging Radiol Med 113(8):1198-210, 2008 Sinonasal Osteoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Benign Tumors and Tumorlike Lesions > Sinonasal Osteoma Sinonasal Osteoma Michelle A Michel, MD Key Facts Terminology Benign, well-defined, slow-growing, bone-forming tumor Imaging Well-marginated, bone density lesion that arises from wall of paranasal sinus & protrudes into sinus lumen Location: Frontal & ethmoid > > > maxillary & sphenoid Larger osteomas may be associated with following findings Sinus opacification or mucocele formation from ostial obstruction Orbital mass effect from extraconal extension Pneumocephalus or intraparenchymal tension pneumatocele Brain abscess ± subdural empyema Top Differential Diagnoses Sinonasal fibrous dysplasia Sinonasal ossifying fibroma Sinonasal osteosarcoma Pathology If multiple osteomas are discovered, consider Gardner syndrome Clinical Issues Most common benign tumor of paranasal sinuses Usually asymptomatic, incidental finding Found in 1% of patients on radiographs & 3% on CT done for sinonasal symptoms < 5% of all osteomas are symptomatic Male:female ≈ 1.5-2.6:1 938 Diagnostic Imaging Head and Neck (Left) Coronal bone CT demonstrates the classic appearance of an “ivory” osteoma of the right frontal sinus The lesion is located medially but did not obstruct the frontal recess The sinus was otherwise well aerated (Right) Axial bone CT shows a well-defined, calcified mass within the right frontal sinus consistent with an osteoma Note that this osteoma is less dense than the compact osteoma in the previous image It has more of a “ground-glass” appearance (Left) Coronal bone CT shows a mixed calcified and soft tissue density mass involving the left ethmoid sinus and nasal cavity Using imaging alone, it would be difficult to distinguish this osteoma from other fibroosseous lesions (Right) Coronal T2WI MR in the same patient shows high signal in the more fibrous component of the lesion superiorly and low signal intensity in the ossified portions inferiorly P.IV(1):71 TERMINOLOGY Synonyms Hamartoma of bone Definitions Benign, well-defined, slow-growing, bone-forming tumor IMAGING General Features Best diagnostic clue Well-marginated, bone density lesion that arises from wall of paranasal sinus & protrudes into sinus lumen Location 939 Diagnostic Imaging Head and Neck Almost exclusively in craniofacial skeleton; paranasal sinuses most common Frontal & ethmoid > > > maxillary & sphenoid Extensive 2009 study concluded: 55% ethmoid, 37.5% frontal, 6% maxillary, 1.5% sphenoid Traditionally named for sinus lumen invaded by osteoma, not bone of origin (unlike cranial osteomas) May extend intracranially or into orbit Other areas of reported involvement Skull, maxilla, mandible, and T-bone (especially bony external auditory canal) Size Range from a few mm to several cm (typically 1.5-40 mm) Majority < 10 mm > 30 mm = “giant” osteoma Morphology Sessile or pedunculated, projecting off wall of sinus Radiographic Findings Radiography Well-defined bone density lesion within a sinus lumen ± associated inflammatory mucosal disease CT Findings CECT No appreciable enhancement due to high density of lesion Bone CT Homogeneous, well-defined, bone-based, high-density mass Non-“ivory-type” osteomas may contain areas of soft tissue density Larger osteoma may be associated with following findings Sinus opacification or mucocele formation from ostial obstruction Orbital mass effect from extraconal extension Pneumocephalus or intraparenchymal tension pneumatocele Brain abscess ± subdural empyema MR Findings T1WI Low signal on all sequences; often not seen Can be confused with air Central yellow marrow may be high signal T2WI Hypointense or follows marrow signal May have hypointense cortical rim Fibrous portions ↑ signal T1WI C+ No appreciable enhancement (except in fibrous areas) Intracranial complications (e.g., mucocele, abscess) better evaluated with contrast Imaging Recommendations Best imaging tool Thin slice bone CT without contrast DIFFERENTIAL DIAGNOSIS Sinonasal Fibrous Dysplasia Expansile lesion of bone typically with “ground-glass” matrix Small, old foci may mimic osteoma Sinonasal Ossifying Fibroma Thick, mature bony wall transitioning to immature woven bone centrally Most of center of lesion is low density on CT (fibroosseous) Sinonasal Osteosarcoma Bone-forming, invasive, malignant tumor of bone Periosteal elevation, permeative margins present Soft tissue component often present Osteoblastoma Uncommon in craniofacial skeleton Benign, but can have more aggressive imaging features (surrounding bone edema & periosteal reaction) PATHOLOGY General Features Etiology 940 Diagnostic Imaging Head and Neck Remains controversial Linked to trauma, infection, or abnormal embryologic development Occurs often at embryologic junction of cartilaginous ethmoid & membranous frontal bones supporting developmental source Some experts believe that osteoma is actually end-stage of fibroosseous lesion, not true benign neoplasm Genetics Usually sporadic, solitary lesions If multiple osteomas are discovered, consider Gardner syndrome (GS) = rare, autosomal dominant transmitted disorder Multiple craniofacial osteomas Intestinal colorectal polyposis progresses to adenocarcinoma Lesions of soft tissues: Fibromatosis, cutaneous epidermoid cysts, lipomas, & leiomyomas Clinically evident osteomas develop ≈ 17 years before GS diagnosis Associated abnormalities P.IV(1):72 ≈ 37% accompanied by pathologic sinonasal findings Focal obstruction & inflammation, generalized inflammation, polyposis Staging, Grading, & Classification Osteomas composed of dense, mature bone without fibrous stroma Ivory Compact Eburnated osteomas Osteomas composed of trabeculae of mature bone separated by fibrous stroma Mature Cancellous Spongy Spongious Mixed Gross Pathologic & Surgical Features Hard, pale, ossified mass within sinus lumen Rock hard, lobulated mass with ivory-like appearance protruding into sinus lumen Microscopic Features Ivory osteomas composed of dense, mature lamellar bone & little fibrous stroma Mature osteomas composed of large trabeculae of mature lamellar bone & more abundant fibrous stroma ± osteoblastic rimming Those with osteoblastoma-like features more aggressive CLINICAL ISSUES Presentation Most common signs/symptoms Usually asymptomatic, incidental finding Found incidentally in 1% of patients on radiographs and 3% on CT performed for sinonasal symptoms < 5% of all osteomas are symptomatic Other signs/symptoms Sinusitis related to obstruction of sinus ostium Headache, facial pain, swelling, or asymmetry Proptosis & diplopia from intraorbital extension Loss of visual acuity from sphenoethmoidal lesions compressing optic nerve Rarely, dizziness, meningitis or seizure from pneumocephalus, intracranial mucocele or abscess Clinical profile Asymptomatic adult with incidental finding of osteoma on CT performed for other sinonasal complaints Demographics Age Reported in all ages > 20 years old > 50% between 50-70 years Rare under age 10 941 Diagnostic Imaging Head and Neck Gender M:F ≈ 1.5-2.6:1 Epidemiology Very common lesion in general population (3% incidence) Most common primary bone tumor of craniofacial skeleton Almost all osteomas occur in craniofacial skeleton Most common benign tumor of paranasal sinuses Natural History & Prognosis Benign tumor, slowly increases in size by continuous bone formation (0.4-6 mm/year) Growth rate greatest at puberty with maximal skeletal growth Becomes symptomatic when large, obstructs sinus drainage, or extends intracranially or into orbit Degeneration into osteosarcoma has not been reported Prognosis is excellent Cure with complete resection, if necessary Treatment If asymptomatic, can treat with watchful waiting Complete surgical removal for following indications Unrelenting symptoms Located near frontal sinus ostium > 50% of volume of frontal sinus filled by osteoma Extends intraorbitally or intracranially CT evidence of significant enlargement Traditionally removed with open surgical procedures Endonasal endoscopic resection possible Small size Frontoethmoidal or orbitoethmoidal in location DIAGNOSTIC CHECKLIST Consider Other fibroosseous lesions if soft tissue density is major component of lesion Be sure to evaluate for affect of osteoma on adjacent structures Patency of sinus drainage pathways; mass effect on orbit, meninges, & brain Image Interpretation Pearls Dense, ossified sinus mass should be considered osteoma until proven otherwise If multiple craniofacial osteomas, consider possibility of Gardner syndrome SELECTED REFERENCES Erdogan N et al: A prospective study of paranasal sinus osteomas in 1,889 cases: Changing patterns of localization Laryngoscope Epub ahead of print, 2009 McHugh JB et al: Sino-orbital osteoma: a clinicopathologic study of 45 surgically treated cases with emphasis on tumors with osteoblastoma-like features Arch Pathol Lab Med 133(10):1587-93, 2009 Alexander AA et al: Paranasal sinus osteomas and Gardner's syndrome Ann Otol Rhinol Laryngol 116(9):658-62, 2007 Eller R et al: Common fibro-osseous lesions of the paranasal sinuses Otolaryngol Clin North Am 39(3):585-600, x, 2006 Earwaker J: Paranasal sinus osteomas: a review of 46 cases Skeletal Radiol 22(6):417-23, 1993 P.IV(1):73 Image Gallery 942 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows a very large, mixed density osteoma involving the right maxillary sinus, ethmoid sinuses, and nasal cavity There is thinning of the orbital floor The turbinates on the right are not visible (Right) Sagittal CT reconstruction shows a large, lobulated ivory osteoma involving the posterior aspect of the right maxillary sinus The mass extends superiorly into the posterior aspect of the orbit and caused proptosis in this patient (Left) Axial STIR MR demonstrates a large left ethmoid osteoma protruding into the left orbit and causing diplopia The hypointense signal in this lesion is typical for lesions that are densely calcified with low water content (Right) Axial T1WI C+ FS MR in the same patient shows lateral displacement of the left medial rectus muscle and optic nerve Patchy enhancement is seen in portions of the osteoma that are less ossified 943 Diagnostic Imaging Head and Neck (Left) Axial CT reconstruction shows the classic appearance of an “ivory” compact osteoma arising within the right frontal sinus This mass did not occlude the frontal recess, and there is no associated mucosal disease or mucocele formation (Right) Axial bone CT shows a dense osteoma of the left ethmoid labyrinth The lesion extends into the extraconal space of the left orbit and caused proptosis in this patient Sinonasal Ossifying Fibroma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Benign Tumors and Tumorlike Lesions > Sinonasal Ossifying Fibroma Sinonasal Ossifying Fibroma Michelle A Michel, MD Key Facts Terminology Benign fibro-osseous lesion composed of fibrous tissue & mature bone Imaging Imaging appearance depends on age (↑ ossified portions with age) Classic appearance: Thick bony peripheral rim surrounding fibrous center CT: Expansile mass with soft tissue density (fibrous) central area surrounded by ossified rim May be indistinguishable from fibrous dysplasia & osteoma MR: Intermediate to low T1 signal throughout tumor T2: Mixed low signal (ossified) & high signal (fibrous) areas Inhomogeneous enhancement of fibrous components Top Differential Diagnoses Sinonasal fibrous dysplasia Sinonasal osteoma Sinonasal osteosarcoma Pathology Thought to arise from mesenchyme of periodontal ligament Clinical Issues Generally asymptomatic & found incidentally 20-40 year olds most common M:F = 1:5 Benign, but locally aggressive May obstruct sinus drainage, cause cosmetic deformity & ocular dysfunction Complete surgical excision is treatment of choice 944 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows an ossifying fibroma of the ethmoid region with dense osseous material peripherally and a fibrous center The margins are well defined There is mass effect on the orbital contents (Right) Coronal bone CT demonstrates a very large, bilobed, ossifying fibroma with a large maxillary antral portion and smaller component extending into the buccal space Peripheral ossification of the maxillary component is noted (Left) Coronal bone CT shows a large OsFib of the orbital plate of the frontal bone This OsFib shows a mixed ossified and fibrous density It is expansile, and the patient presented with cosmetic deformity from forehead swelling and proptosis from orbital mass effect (Right) Axial NECT in the same patient shows that the dominant focus of ossification in this case is central with surrounding soft tissue density rather than the classic pattern with peripheral ossification P.IV(1):75 TERMINOLOGY Abbreviations Ossifying fibroma (OsFib) Synonyms Cemento-ossifying fibroma, psammomatoid ossifying fibroma, juvenile-aggressive ossifying fibroma Definitions Benign fibro-osseous lesion composed of encapsulated mixture of fibrous tissue & mature bone IMAGING General Features Best diagnostic clue 945 Diagnostic Imaging Head and Neck Well-demarcated, expansile mass with soft tissue density (fibrous) central area surrounded by ossified rim Location 10-20% of craniofacial OsFib arise from maxilla Most common craniofacial site is mandible (75%) Characteristically monostotic Size 0.5-10 cm Morphology Well circumscribed, expansile CT Findings NECT Well-circumscribed, expansile mass with mixed soft tissue & bone density Most often unilobular CECT Fibrous areas may show subtle to more avid enhancement Bone CT Imaging appearance depends on age of OsFib (↑ ossified portions with age) Classic appearance Thick bony peripheral rim surrounding low attenuation fibrous center Other appearance Scattered foci of soft tissue density among ossified areas Thin, “eggshell” appearance of peripheral bone CT appearance may be indistinguishable from fibrous dysplasia & osteoma May absorb maxillary tooth roots MR Findings T1WI Intermediate to low signal throughout tumor Fibrous areas intermediate signal (classically central) Ossified areas hypointense (classically peripheral) T2WI Mixed low & high signal areas Fibrous areas hyperintense (usually lesion center) Ossified areas hypointense (usually lesion periphery) Obstructed secretions behind lesion & associated mucocele are hyperintense Fluid-fluid levels in portions of these tumors have been reported T1WI C+ Inhomogeneous enhancement of fibrous portions of tumor matrix Enhancement of outer shell & septae may be seen Imaging Recommendations Best imaging tool Fibro-osseous lesions of craniofacial area best studied with bone algorithm CT Protocol advice Thin slice bone CT in axial plane with coronal ± sagittal reformatted images Enhanced T1 fat-saturated MR provides complete presurgical roadmap of surrounding soft tissues at risk DIFFERENTIAL DIAGNOSIS Sinonasal Fibrous Dysplasia Poorly defined expansion of maxillofacial bones Classic “ground-glass” appearance Mixed pattern of less active “ground-glass” and more active fibrous areas May be monostotic (70%) or polyostotic (30%) Encompasses rather than absorbs healthy tooth roots Sinonasal Osteoma Mass comprised of mostly solid lamellar bone Frontal sinus common location Sinonasal Osteosarcoma Destructive, aggressive lesion of craniofacial bones Tumor “new bone” in mass matrix “Sunburst” periosteal reaction 946 Diagnostic Imaging Head and Neck Most common in adolescent males or long-term complication of XRT Cementoblastoma Benign tumor of cementum in young males Dense mass associated with tooth root Not located in frontal, ethmoid, sphenoid sinuses PATHOLOGY General Features Etiology Thought to arise from mesenchyme of periodontal ligament (related to cementifying fibroma, cementoossifying fibroma) Presumed to originate from mesenchymal blast cells Closely related to fibrous dysplasia & ameloblastoma Densely cellular, well-defined fibrous tumor with ossification progressing from periphery toward center Early stage: Primarily fibrous Late stage: Fills in with mature bone Associated abnormalities Large lesions may result in cosmetic deformity, ocular dysfunction P.IV(1):76 May obstruct sinus drainage pathways and lead to mucocele formation Intracranial extension complicated by tension pneumocephalus has been reported Staging, Grading, & Classification Subtypes described Juvenile Active Aggressive Psammomatoid Gross Pathologic & Surgical Features Gritty, gray to white, hard lesion Microscopic Features Islands of osteoid rimmed by osteoblast-forming lamellar bone Central OsFib contains immature (woven) bone while periphery has more mature (lamellar) bone Fibrous stroma shows a parallel & whorl arrangement of collagen & fibroblasts May be densely cellular with hemorrhage, inflammation, & giant cells OsFib may be histologically indistinguishable from active form of fibrous dysplasia CLINICAL ISSUES Presentation Most common signs/symptoms Generally asymptomatic & found incidentally Other signs/symptoms Chronic sinusitis symptoms: Rhinorrhea, pain, cheek swelling, nasal obstruction Displaced teeth Exophthalmos, diplopia, visual acuity loss due to orbital mass effect Clinical profile 20-40-year-old female with mixed soft tissue-ossified sinus lesion incidentally detected on CT performed for other reasons Appearance mimics other fibro-osseous lesions & diagnosis not made of basis of imaging alone Based on combination of clinical, radiological, & pathological criteria Demographics Age 1st appears in young adult 20-40 year olds most common Wide age range reported Gender M:F = 1:5 Epidemiology 10-20% of craniofacial OsFib arise in maxilla < 0.5% risk of malignant degeneration 947 Diagnostic Imaging Head and Neck Natural History & Prognosis Slow growing but may be locally aggressive OsFib of paranasal sinuses are more aggressive than OsFib of mandible Juvenile variant (active ossifying fibroma) may have aggressive, locally destructive behavior Prognosis excellent after complete resection High rate of recurrence if incompletely resected Treatment Complete surgical excision is treatment of choice as permitted by OsFib location Lesions with benign behavior that not produce deformity may be treated with curettage and ostectomy Recurrence rates higher with this approach DIAGNOSTIC CHECKLIST Consider May not have classic appearance of bony rim with fibrous center Densities may be patchy & randomly distributed Image Interpretation Pearls MR appearance of OsFib highly variable, & lesion may appear more aggressive Careful correlation with CT important May be indistinguishable from fibrous dysplasia in imaging Refer to more generically as “fibro-osseous lesion” If polyostotic process, fibrous dysplasia more likely Reporting Tips Be sure to describe position in relation to sinus drainage pathways Be sure to describe mass effect upon adjacent structures, such as orbit, neural foramina, & intracranial cavity SELECTED REFERENCES Boudewyns AN et al: Sinonasal fibro-osseous hamartoma: case presentation and differential diagnosis with other fibro-osseous lesions involving the paranasal sinuses Eur Arch Otorhinolaryngol 263(3):276-81, 2006 Eller R et al: Common fibro-osseous lesions of the paranasal sinuses Otolaryngol Clin North Am 39(3):585-600, x, 2006 Mehta D et al: Paediatric fibro-osseous lesions of the nose and paranasal sinuses Int J Pediatr Otorhinolaryngol 70(2):193-9, 2006 Kendi AT et al: Sinonasal ossifying fibroma with fluid-fluid levels on MR images AJNR Am J Neuroradiol 24(8):163941, 2003 Alawi F: Benign fibro-osseous diseases of the maxillofacial bones A review and differential diagnosis Am J Clin Pathol 118 Suppl:S50-70, 2002 Khoury NJ et al: Juvenile ossifying fibroma: CT and MR findings Eur Radiol 12 Suppl 3:S109-13, 2002 Cavalcanti MG et al: Evaluation of an ossifying fibroma using three-dimensional computed tomography Dentomaxillofac Radiol 30(6):342-5, 2001 Engelbrecht V et al: CT and MRI of congenital sinonasal ossifying fibroma Neuroradiology 41(7):526-9, 1999 Thompson J et al: Nasopharyngeal nonossifying variant of ossifying fibromyxoid tumor: CT and MR findings AJNR Am J Neuroradiol 16(5):1132-4, 1995 10 Sterling KM et al: Ossifying fibroma of sphenoid bone with coexistent mucocele: CT and MRI J Comput Assist Tomogr 17(3):492-4, 1993 11 Han MH et al: Sinonasal psammomatoid ossifying fibromas: CT and MR manifestations AJNR Am J Neuroradiol 12(1):25-30, 1991 P.IV(1):77 Image Gallery 948 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows a large maxillary ossifying fibroma that nearly fills the entire right maxillary antrum The right nasal airway is obstructed , and there are postobstructive secretions in the right ethmoid sinuses (Right) Coronal bone CT shows an atypical appearance of an ossifying fibroma This frontal sinus lesion demonstrates diffuse, slightly heterogeneous ossification with little fibrous component This OsFib mimics the appearance of an osteoma (Left) Axial bone CT demonstrates an expansile, predominantly soft tissue density mass within the posterior ethmoid region A focus of peripheral ossification along the lateral margin suggests that this is a fibro-osseous lesion, in this case, an ossifying fibroma (Right) Axial T2WI MR in the same patient shows hypointense signal in the ossified portion of the lesion Note the hyperintense obstructed secretions in the sphenoid sinus posterior to the lesion 949 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR in the same patient shows signal intensity similar to that of muscle within the majority of the ossifying fibroma The margins are well defined Note the mass effect upon the right orbital contents causing diplopia in this patient (Right) Axial T1WI C+ MR in the same patient reveals heterogeneous enhancement throughout the lesion The fibrous portions of OsFib typically enhance, and there is little or no enhancement in the ossified portions Juvenile Angiofibroma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Benign Tumors and Tumorlike Lesions > Juvenile Angiofibroma Juvenile Angiofibroma Michelle A Michel, MD Key Facts Terminology Benign, vascular, nonencapsulated, locally invasive nasal cavity mass Imaging Location: Centered in posterior nasal cavity near SPF Extends into nasopharynx, pterygopalatine fossa (PPF), infratemporal fossa CT findings in JAF Mass shows diffuse, avid enhancement Posterior wall of maxillary sinus bowed anteriorly Bone remodeling ± destruction MR findings in JAF Signal voids represent flow in enlarged vessels Intense enhancement ± flow voids Angiography typically performed at time of preoperative embolization shows tumor blush IMAX branch of ECA most common feeding vessel Top Differential Diagnoses Hemangioma Rhabdomyosarcoma Antrochoanal polyp Esthesioneuroblastoma Clinical Issues Symptoms: Unilateral nasal obstruction (90%) & epistaxis (60%) Almost exclusively occurs in males Preferred treatment: Complete surgical resection RT may be used as adjuvant therapy after surgery or as primary treatment in some cases Diagnostic Checklist Consider other diagnoses in female patient Be sure to look for JAF extension into surrounding structures 950 Diagnostic Imaging Head and Neck (Left) Transverse oblique graphic illustrates the classic features and location of a JAF The site of origin is in the sphenopalatine foramen , and there is extension into the pterygopalatine fossa and nasal cavity The internal maxillary artery is the dominant feeding vessel of this vascular mass (Right) Axial T1WI C+ MR shows a large, infiltrating JAF within the nasal cavity , sphenoid sinus , and extending into the middle cranial fossa (Left) Axial T1WI MR demonstrates a smaller angiofibroma centered at the left nasal choana The mass is slightly hypointense compared to adjacent mucosa in the nasopharynx and nasal cavity (Right) Axial T1WI C+ MR in the same patient shows diffuse, slightly heterogeneous enhancement throughout the lesion The contrast helps to differentiate the mass from adjacent soft tissues In this case, no extension into the pterygopalatine fossa or masticator space was present P.IV(1):79 TERMINOLOGY Abbreviations Juvenile angiofibroma (JAF) Synonyms Juvenile nasopharyngeal angiofibroma (JNA); fibromatous or angiofibromatous hamartoma JAF of nasal cavity is more correct terminology JNA is commonly used term, but tumor begins in nose, not in nasopharynx Definitions Benign, vascular, nonencapsulated, locally invasive nasal cavity mass IMAGING General Features 951 Diagnostic Imaging Head and Neck Best diagnostic clue Intensely enhancing mass originating at sphenopalatine foramen (SPF) in adolescent male Location Centered in posterior wall of nasal cavity off midline, at margin of SPF Extends from posterior nasal cavity into nasal cavity, nasopharynx, & pterygopalatine fossa (PPF) Penetrates PPF early (90%) with involvement of upper medial pterygoid lamina Sphenoid sinus extension (60%) May extend into maxillary (43%) & ethmoid sinuses (35%), masticator space (infratemporal fossa), inferior orbital fissure 5-20% extend into middle cranial fossa via vidian canal or foramen rotundum Size Usually 2-6 cm but may become massive Morphology Lobular, usually well-circumscribed mass Large lesions have infiltrating margins Radiographic Findings Radiography Lateral facial plain film shows anterior displacement of posterior wall of maxillary antrum (“bow” sign) Associated with nasal cavity opacification ± nasal cavity/nasopharyngeal soft tissue mass CT Findings NECT Soft tissue mass originating near SPF with extension into adjacent nasopharynx & PPF ± opacified sphenoid sinus (obstructed secretions vs tumor infiltration) CECT Mass shows diffuse, avid enhancement Bone CT Bone remodeling ± destruction Posterior wall maxillary sinus bowed anteriorly Ipsilateral nasal cavity & PPF enlarged CTA Enlarged ipsilateral external carotid (ECA) & internal maxillary (IMAX) arteries MR Findings T1WI Heterogeneous, intermediate signal similar to other soft tissues Signal voids represent flow in enlarged vessels T2WI Heterogeneous, intermediate to high signal mass Punctate & serpentine flow voids may be seen within tumor T1WI C+ Intense enhancement ± flow voids T1WI C+ FS Coronal plane shows cavernous sinus, sphenoid sinus, or skull base extension MRA Enlarged ipsilateral external carotid (ECA) & internal maxillary (IMAX) arteries Vessels within mass may be too small to evaluate with MRA Angiographic Findings Conventional angiography typically performed at time of preoperative embolization Intense capillary tumor blush is fed by enlarged feeding vessels from ECA IMAX, ascending pharyngeal arteries from ECA are most common feeding vessels If skull base or cavernous sinus extension, internal carotid artery (ICA) supply is common Imaging Recommendations Best imaging tool Maxillofacial bone-only unenhanced CT in axial & coronal planes for evaluating bone remodeling vs destruction Gadolinium-enhanced MR optimal for mapping lesion extent and determining vascularity Catheter angiography of both ECA & ICA Often performed in conjunction with embolization therapy 952 Diagnostic Imaging Head and Neck Helps plan surgery & decreases intraoperative blood loss Protocol advice Maxillofacial MR with T1 C+ in axial & coronal planes with fat saturation Multiplanar imaging optimal for evaluating extension into sphenoid sinus, orbit, skull base CECT may be helpful for evaluating residual disease in postoperative period DIFFERENTIAL DIAGNOSIS Sinonasal Hemangioma Usually isolated to nasal cavity Flow voids unlikely No adolescent male predilection Rhabdomyosarcoma Homogeneous mass with bone destruction Not necessarily centered in posterolateral nasal cavity Does not usually penetrate sphenopalatine foramen into PPF P.IV(1):80 Esthesioneuroblastoma 1st incidence peaks in 2nd decade; F > M Presenting symptoms same as JAF Nasal cavity mass near cribriform plate Avidly enhancing Antrochoanal Polyp Maxillary antrum is opacified Lesion herniates into anterior nasal cavity, then nasopharynx; PPF not involved Peripheral enhancement only Encephalocele Nasoethmoidal type presents as intranasal mass Connection to intracranial cavity seen on imaging No enhancement Usually more anterior in position PATHOLOGY General Features Etiology Source of fibrovascular tissue of JAF is not known Best current hypothesis Primitive mesenchyme of sphenopalatine foramen is source of JAF Staging, Grading, & Classification Staging systems based upon tumor size (< or > cm), invasion to PPF anterior &/or posterior to pterygoid plates, and skull base & intracranial invasion Gross Pathologic & Surgical Features Reddish-purple, compressible, mucosa-covered nodular mass Cut surface has “spongy” appearance Microscopic Features Unencapsulated, highly vascular polypoid mass of vascular angiomatous tissue in fibrous stroma Myofibroblast is thought to be cell of origin Estrogen, testosterone, or progesterone receptors may be present CLINICAL ISSUES Presentation Most common signs/symptoms Unilateral nasal obstruction (90%) & epistaxis (60%) Other signs/symptoms Nasal voice, nasal discharge Anosmia Clinical profile Adolescent male with nasal obstruction & epistaxis Nasal endoscopy reveals vascular-appearing nasal cavity mass Biopsy in outpatient setting should be avoided due to risk of hemorrhage Demographics 953 Diagnostic Imaging Head and Neck Age 10-25 years reported age range Average age at onset = 15 years Gender Almost exclusively occurs in males If found in a female, genetic testing may reveal mosaicism Epidemiology 0.5% of all head & neck neoplasms 5-20% JAF extend to skull base and may have skull base erosion Natural History & Prognosis May rarely spontaneously regress Local recurrence rate with surgery: 6-24% Treatment Preferred treatment: Complete surgical resection using preoperative embolization to ↓ blood loss Multiple surgical approaches Open resection (midface degloving) vs endoscopic removal ± laser assistance Endoscopic resection associated with ↓ bleeding & shorter hospital stay Radiation therapy (RT) Adjuvant to surgery for unresectable intracranial disease & cavernous sinus involvement (78% control rates reported) RT alone for cure used in some institutions Used with caution in young patients due to potential to induce malignancies Hormonal therapy (estrogen) is controversial DIAGNOSTIC CHECKLIST Consider JAF in adolescent male patient with epistaxis & enhancing posterior nasal cavity mass Image Interpretation Pearls Be sure to look for JAF extension into surrounding structures SELECTED REFERENCES Bleier BS et al: Current management of juvenile nasopharyngeal angiofibroma: a tertiary center experience 19992007 Am J Rhinol Allergy 23(3):328-30, 2009 Carrillo JF et al: Juvenile nasopharyngeal angiofibroma: clinical factors associated with recurrence, and proposal of a staging system J Surg Oncol 98(2):75-80, 2008 Danesi G et al: Juvenile nasopharyngeal angiofibroma: evaluation and surgical management of advanced disease Otolaryngol Head Neck Surg 138(5):581-6, 2008 Kania RE et al: Early postoperative CT scanning for juvenile nasopharyngeal angiofibroma: detection of residual disease AJNR Am J Neuroradiol 26(1):82-8, 2005 Mann WJ et al: Juvenile angiofibromas: changing surgical concept over the last 20 years Laryngoscope 114(2):2913, 2004 Jones BV et al: Magnetic resonance imaging of the pediatric head and neck Top Magn Reson Imaging 10(6): 34861, 1999 Davis KR: Embolization of epistaxis and juvenile nasopharyngeal angiofibromas AJR Am J Roentgenol 148(1):20918, 1987 Lloyd GA et al: Juvenile angiofibroma: imaging by magnetic resonance, CT and conventional techniques Clin Otolaryngol Allied Sci 11(4):247-59, 1986 P.IV(1):81 Image Gallery 954 Diagnostic Imaging Head and Neck (Left) Sagittal oblique graphic shows the spread patterns of JAF The lesion originates at the sphenopalatine foramen and extends into the nasal cavity , nasopharynx , and infratemporal fossa (Right) Coronal CECT shows a large JAF extending into the nasopharynx , infratemporal fossa , and middle cranial fossa The sphenoid sinus is replaced by the tumor Avid enhancement is characteristic of this vascular lesion (Left) Axial T2WI MR in a young male patient shows a large, infiltrating JAF in the classic location The mass is centered at the sphenopalatine foramen and extends laterally into the masticator space and medially into the nasopharynx (Right) Axial T1WI C+ FS MR in the same patient shows avid enhancement throughout the lesion Several serpiginous signal voids are noted in the mass , consistent with enlarged feeding vessels as seen on this sequence 955 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR demonstrates a lobular, diffusely enhancing mass filling the right nasal cavity and protruding into the nasopharynx Flow voids are also seen in this JAF consistent with its vascular nature (Right) Lateral catheter angiography shows areas of dense tumor blush within a JAF prior to embolization This external carotid artery injection shows that the main arterial feeding vessel is the internal maxillary artery Sinonasal Inverted Papilloma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Benign Tumors and Tumorlike Lesions > Sinonasal Inverted Papilloma Sinonasal Inverted Papilloma Michelle A Michel, MD Key Facts Imaging Typical location: Along lateral nasal wall centered at middle meatus ± extension into antrum CT findings 40% show “entrapped bone” Focal hyperostosis of adjacent bone may indicate point of tumor attachment MR findings T2: Predominantly hyperintense to skeletal muscle T2 & T1 C+ FS MR: Curvilinear striations or “convoluted, cerebriform pattern” is distinctive If portion of tumor appears invasive or necrosis present → consider synchronous SCCa Multiplanar MR optimal for tumor mapping & differentiating tumor from obstructed secretions PET cannot be reliably used to distinguish benign IPap & SCCa Top Differential Diagnoses Solitary sinonasal (antrochoanal) polyp Sinonasal squamous cell carcinoma Sinonasal polyposis Pathology Hyperplastic squamous epithelium replaces seromucinous ducts & glands in stroma with endophytic growth pattern 10% either degenerate into or coexist with SCCa SCCa may be either synchronous (7%) or metachronous (4%) Clinical Issues Typically 40-70 years M > F = 4-5:1 Strong potential for local recurrence if incompletely resected 956 Diagnostic Imaging Head and Neck (Left) Coronal graphic of an inverted papilloma originating near the middle meatus and extending into the maxillary sinus Blocked secretions are noted in the ethmoid and maxillary sinuses (Right) Axial bone CT shows a mass in the nasal cavity along the lateral wall near the middle meatus The maxillary sinus is opacified, but it is difficult to differentiate obstructed secretions from papilloma on the CT MR in such a case would be helpful to delineate the margins of the mass (Left) Coronal T2WI FS MR shows characteristic features on an inverted papilloma that involves the right maxillary sinus and nasal cavity The lesion has a “convoluted, cerebriform” architecture Note the inferior displacement of the inferior turbinate (Right) Axial T1WI C+ FS MR shows classic features of an inverted papilloma The lesion is centered at the middle meatus with nasal cavity and antral components This lesion, like the one in the previous image, shows characteristic architecture P.IV(1):83 TERMINOLOGY Abbreviations Inverted papilloma (IPap) Synonyms Endophytic papilloma, Schneiderian papilloma, squamous cell papilloma, transitional cell papilloma, cylindrical epithelioma Definitions Benign epithelial tumor of nasal mucosa with histology showing epithelium proliferating into underlying stroma IMAGING General Features 957 Diagnostic Imaging Head and Neck Best diagnostic clue Mass along lateral nasal wall centered at middle meatus ± extension into antrum with local bone remodeling & obstructive sinus disease Location Most commonly originates along lateral nasal wall near middle meatus Spreads into adjacent sinuses Maxillary (69%), ethmoid (50-90%), sphenoid (10-20%), frontal (10-15%), orbit & CNS (≈ 30%) Uncommonly originates in maxillary antrum, sphenoid, frontal, or ethmoid sinuses Size Small IPap: < cm centered in middle meatal region of lateral wall of nose Large IPap: > cm mass that remodels nasal cavity, invades or obstructs ipsilateral sinuses Morphology Architecture described as “convoluted, cerebriform” pattern CT Findings NECT Soft tissue mass along lateral nasal wall at middle meatus ± extension into maxillary sinus 40% show “entrapped bone” 10% show “tumorous calcification” Focal hyperostosis of adjacent bone (plaque or cone-shaped) may indicate point of tumor attachment Unilateral obstruction yields ostiomeatal unit pattern of inflammatory sinus disease Frontal, anterior ethmoid, & maxillary sinuses opacified Small IPap may show no bone changes, making identification of tumor difficult Larger IPap shows bone remodeling & mass effect in middle meatal region If bony destruction present, consider synchronous SCCa CECT IPap enhances while obstructed sinus secretions not Variable enhancement pattern from diffuse to heterogeneous “Convoluted, cerebriform” appearance evident with contrast MR Findings T1WI Isointense to slightly hyperintense to soft tissue & muscle T2WI Heterogeneous, predominantly hyperintense to skeletal muscle Curvilinear striations or “convoluted, cerebriform pattern” is distinctive Areas of necrosis & postobstructive secretions are high signal on T2 T1WI C+ Enhancement may have “convoluted, cerebriform” appearance If portion of tumor appears invasive or necrosis present → consider synchronous SCCa Imaging Recommendations Best imaging tool Tumor usually 1st detected on sinus CT performed for evaluation of “sinusitis” symptoms When mass is found on CT, MR completed for preoperative tumor mapping Protocol advice Multiplanar MR optimal for tumor mapping & differentiating tumor from obstructed secretions T1 & T2-enhanced FS sequences best show internal architecture Nuclear Medicine Findings PET/CT High FDG uptake with SUV max > 3.0 typical in IPap with higher SUV in associated SCCa PET cannot be reliably used to distinguish benign IPap & SCCa DIFFERENTIAL DIAGNOSIS Sinonasal Solitary Polyps Antrochoanal polyp: Dumbbell-shaped lesion involving maxillary antrum & ipsilateral nasal cavity Peripheral, not central, enhancing lesion with mucous or fluid density (CT) or intensity (MR) Sinonasal SCCa Destroys rather than remodels bones in most cases Typically originates within maxillary antrum > nasal cavity Sinonasal Polyposis Polypoid lesions in nasal cavity & paranasal sinuses 958 Diagnostic Imaging Head and Neck Bone remodeling & sinus expansion Juvenile Angiofibroma Adolescent males with nose bleeds Mass centered on margin of sphenopalatine foramen in posterior nasal cavity Intense enhancement of this highly vascular mass is typical Esthesioneuroblastoma Typically centered in superior nasal cavity near cribriform plate Intense enhancement; more likely to invade orbit/anterior skull base P.IV(1):84 PATHOLOGY General Features Etiology Maturation of sinonasal mucosa into ciliated columnar epithelium & mucous glands gives rise to papillomas Neither etiology nor factors responsible for malignant transformation are fully elucidated Viral origin has been postulated (e.g., human papilloma virus) Epigenetic events contribute to underlying pathogenesis (promoter hypermethylation of CDKN2B gene) Outdoor & industrial occupations may be potential risk factors Does not result from allergy, noxious agents, or chronic infection Associated abnormalities 10% either degenerate into or coexist with SCCa SCCa may be either synchronous (7%) or metachronous (4%) Staging, Grading, & Classification Schneiderian papilloma types arise from nasal mucosa Inverted papilloma (47%) Fungiform papilloma (50%): Occurs on nasal septum in young males & is rarely imaged prior to surgical treatment Cylindric cell papilloma (3%) No widely accepted, clinically relevant staging system Gross Pathologic & Surgical Features Endoscopic or surgical observations Bulky, opaque, polypoid mucosal mass with red-gray color characteristic of lobulated tumor surface Microscopic Features Hyperplastic squamous epithelium replacing seromucinous ducts & glands in underlying stroma Endophytic growth pattern Surrounding nasal mucosa often shows squamous metaplasia CLINICAL ISSUES Presentation Most common signs/symptoms Similar to recurrent sinusitis with nasal obstruction & discharge Other signs/symptoms Epistaxis, anosmia, headache, pain Clinical profile Adult male patient with symptoms similar to chronic rhinosinusitis Demographics Age Typically 40-70 years Gender M > F = 4-5:1 Epidemiology 0.5-7% of all tumors of nasal cavity Involves at least paranasal sinus 82% of time Typically unifocal Multifocal in 4% of cases Bilateral up to 13% due to transseptal extension Natural History & Prognosis 959 Diagnostic Imaging Head and Neck Benign, but locally aggressive tumor Strong potential for local recurrence if incompletely resected When SCCa is associated, prognosis changes to survival rates associated with nasal SCCa Treatment Type of surgery depends on location and size of lesion as well as involvement of critical structures Surgical resection using variety of methods Endoscopic resection is effective for most smaller tumors Midfacial degloving & sublabial approaches for larger lesions Medial maxillectomy through lateral rhinotomy + wide enbloc excision in more extensive IPap DIAGNOSTIC CHECKLIST Consider T1 C+ FS MR used to search for “convoluted, cerebriform” appearance MR used to evaluate for extension beyond sinonasal cavities & differentiate tumor from secretions Image Interpretation Pearls Identify invasion of deeper areas (ethmoid sinuses, pterygopalatine fossa, orbit) at imaging as this may alter surgical approach Areas of necrosis or frank bony destruction should raise suspicion for coexistent SCCa Look for additional masses as 4% multifocal SELECTED REFERENCES Jeon TY et al: 18F-FDG PET/CT findings of sinonasal inverted papilloma with or without coexistent malignancy: comparison with MR imaging findings in eight patients Neuroradiology 51(4):265-71, 2009 Karkos PD et al: Computed tomography and/or magnetic resonance imaging for pre-operative planning for inverted nasal papilloma: review of evidence J Laryngol Otol 123(7):705-9, 2009 Sham CL et al: Treatment results of sinonasal inverted papilloma: an 18-year study Am J Rhinol Allergy 23(2):20311, 2009 Jeon TY et al: Sinonasal inverted papilloma: value of convoluted cerebriform pattern on MR imaging AJNR Am J Neuroradiol 29(8):1556-60, 2008 Lee DK et al: Focal hyperostosis on CT of sinonasal inverted papilloma as a predictor of tumor origin AJNR Am J Neuroradiol 28(4):618-21, 2007 Maroldi R et al: Magnetic resonance imaging findings of inverted papilloma: differential diagnosis with malignant sinonasal tumors Am J Rhinol 18(5):305-10, 2004 Ojiri H et al: Potentially distinctive features of sinonasal inverted papilloma on MR imaging AJR Am J Roentgenol 175(2):465-8, 2000 Dammann F et al: Inverted papilloma of the nasal cavity and the paranasal sinuses: using CT for primary diagnosis and follow-up AJR Am J Roentgenol 172(2):543-8, 1999 Yousem DM et al: Inverted papilloma: evaluation with MR imaging Radiology 185(2):501-5, 1992 P.IV(1):85 Image Gallery (Left) Axial NECT shows a slightly lobular soft tissue mass within the left nasal cavity 960 with extension into the left Diagnostic Imaging Head and Neck maxillary sinus The location is typical of a papilloma It is difficult to differentiate the mass from obstructed secretions on the CT (Right) Axial T2WI MR in the same patient shows that the mass occupies most of the maxillary antrum and is hypointense compared to secretions trapped anteromedially The nasal component of this papilloma is hyperintense (Left) Axial STIR MR shows the classic architecture of inverted papilloma The lesion shows a “convoluted, cerebriform” appearance Trapped secretions laterally are hyperintense compared to the mass The frontal sinus is an unusual location for this lesion (Right) Coronal T2WI FS MR in the same patient shows that the papilloma involves the ethmoid sinuses in addition to the frontal sinus Trapped secretions along the margin of frontal tumor component are proteinaceous with T1 shortening (Left) Axial T1WI C+ MR shows an unusual case of bilateral inverted papillomas due to transseptal extension involving the maxillary sinuses The larger lesion on the left nearly fills the nasal cavity Both lesions demonstrate the convoluted appearance typical of these lesions (Right) Axial STIR MR demonstrates a squamous carcinoma arising within an inverted papilloma The carcinoma has destroyed the anterior maxillary wall , and the papilloma extends into the left nasal cavity Sinonasal Hemangioma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Benign Tumors and Tumorlike Lesions > Sinonasal Hemangioma Sinonasal Hemangioma Michelle A Michel, MD Key Facts Terminology 961 Diagnostic Imaging Head and Neck Lobular capillary hemangioma (LCH) Previously called “pyogenic granuloma” Benign capillary proliferation with distinct lobular architecture Imaging Location: Nasal septum (55%), particularly anteriorly (17%) Other: Nasal vestibule (17%), inferior turbinate (13%) Typically ≤ 1.5 cm CT Central areas of lobular enhancement surrounded by iso- to hypodense “cap” of variable thickness May cause bone erosion or remodeling MR T2 hyperintense Intense enhancement Larger lesions may show flow voids Top Differential Diagnoses Juvenile angiofibroma Angiomatous polyp Hemangiopericytoma Pathology Predisposing factors include trauma & hormonal influences Clinical Issues Symptoms: Epistaxis & nasal obstruction Peak incidence in 5th decade with slight F > M Diagnostic Checklist Multiplanar MR for tumor mapping if lesion extends superiorly toward skull base (Left) Axial CECT demonstrates an avidly enhancing, well-circumscribed soft tissue mass in the posterior nasal cavity and protruding into the nasopharynx This lobular hemangioma arose from the inferior turbinate; the patient presented with nasal bleeding (Right) Coronal CECT in the same patient shows that the enhancement is somewhat heterogeneous with a few small nonenhancing foci No extension into the skull base or sphenoid sinus is appreciated in the coronal plane 962 Diagnostic Imaging Head and Neck (Left) Axial T2WI MR demonstrates a well-defined, ovoid soft tissue mass in the superior aspect of the left nasal cavity in an adult patient with intermittent epistaxis The lesion is homogeneously hyperintense on this sequence, consistent with a hemangioma No orbital invasion is appreciated (Right) Coronal T1WI C+ MR in the same patient shows diffuse, avid enhancement throughout the hemangioma This mass obstructed the left frontal recess; secretions fill the frontal sinus P.IV(1):87 TERMINOLOGY Abbreviations Lobular capillary hemangioma (LCH) Synonyms Most common synonym: Pyogenic granuloma Inadequate terminology as there is no clear microbiological evidence for infectious origin & granulation tissue is not present histologically Other archaic terms: Telangiectatic granuloma, granuloma pedunculatum, human botryomycosis Definitions Benign capillary proliferation with microscopically distinct lobular architecture affecting skin and mucous membranes of oral cavity & nasal region IMAGING General Features Best diagnostic clue Well-defined, enhancing nasal cavity mass arising from anterior septum or turbinates Location Nasal septum most common (55%), particularly anteriorly (17%) Size Typically ≤ 1.5 cm Morphology Well defined, lobulated CT Findings NECT Isointense to slightly hypodense lobular soft tissue density mass compared to muscle CECT Avidly enhancing Central areas of lobular enhancement surrounded by iso- to hypodense “cap” of variable thickness Bone CT May cause bone erosion or remodeling Displaces lateral nasal wall, septum, & turbinates MR Findings T1WI 963 Diagnostic Imaging Head and Neck Low to intermediate signal mass (compared to muscle) T2WI Most often hyperintense Larger lesions may show signal voids (flow voids) Angiographic Findings Lobular areas of capillary blush Imaging Recommendations Best imaging tool Multiplanar enhanced MR imaging If large, bone CT for bone changes DIFFERENTIAL DIAGNOSIS Juvenile Angiofibroma Occurs exclusively in males, usually adolescent Posteriorly nasal cavity near sphenopalatine foramen Angiomatous Polyp Rare nasal cavity lesion Minimally or nonenhancing Hemangiopericytoma More likely within sinus May contain bone or cartilage Sinonasal Melanoma Clinical: Middle-aged patient ↑ precontrast T1 signal, ↓ T2 signal PATHOLOGY General Features Etiology Unknown Predisposing factors include trauma (nose picking, nasal packing) & hormonal factors (pregnancy, oral contraceptives) Gross Pathologic & Surgical Features Solitary, red-to-purple hypervascularized nasal mass ± superficial ulceration Microscopic Features Lobular growth pattern of capillary proliferation CLINICAL ISSUES Presentation Most common signs/symptoms Epistaxis & nasal obstruction Demographics Age Peak incidence in 5th decade Gender Slight female predominance Natural History & Prognosis “Pregnancy tumor” may regress after parturition Treatment Local surgical excision Recurrences are rare after surgical excision DIAGNOSTIC CHECKLIST Consider Multiplanar MR for tumor mapping if lesion extends superiorly toward skull base SELECTED REFERENCES Benoit MM et al: Lobular capillary hemangioma of the nasal cavity in a five-year-old boy Otolaryngol Head Neck Surg 142(2):290-1, 2010 Puxeddu R et al: Lobular capillary hemangioma of the nasal cavity: A retrospective study on 40 patients Am J Rhinol 20(4):480-4, 2006 Dillon WP et al: Hemangioma of the nasal vault: MR and CT features Radiology 180(3):761-5, 1991 964 Diagnostic Imaging Head and Neck Sinonasal Nerve Sheath Tumor > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Benign Tumors and Tumorlike Lesions > Sinonasal Nerve Sheath Tumor Sinonasal Nerve Sheath Tumor Michelle A Michel, MD Key Facts Terminology Slow-growing, benign tumors arising from nerve sheath (schwannoma) or peripheral nerve tissue (neurofibroma) Imaging Well-defined, expansile soft tissue mass arising in nasoethmoid region with adjacent bone remodeling MR evaluates extent & differentiates from obstructed secretions CT shows benign pattern of bone remodeling to best advantage Top Differential Diagnoses Inverted papilloma Sinonasal benign mixed tumor (pleomorphic adenoma) Sinonasal mucocele Sinonasal solitary polyp Pathology Several PNST types Schwannoma Neurofibroma Soft tissue perineurioma Malignant PNST Clinical Issues Symptoms usually nonspecific and mimic inflammatory disease < 4% of head & neck schwannomas arise in sinonasal cavities Diagnostic Checklist Imaging role: Direct biopsy, accurately map extent of lesion, & look for orbital/intracranial extension Imaging features usually not specific enough to make histologic diagnosis (Left) Coronal bone CT demonstrates an expansile mass involving the right nasal cavity and ethmoid region Note the smooth remodeling of the bone surrounding the lesion suggestive of a benign mass This schwannoma could be confused with a mucocele on CT alone (Right) Axial T1WI MR shows a schwannoma in the right nasal cavity deviating the septum to the left Trapped secretions with high T1 signal are noted lateral to the mass in the maxillary sinus 965 Diagnostic Imaging Head and Neck (Left) Axial T2WI MR in a young male patient with facial swelling and nasal obstruction shows a well-defined, low signal mass centered in the left maxillary sinus with trapped secretions lateral to the lesion (Right) Coronal T1WI C+ FS MR in the same patient shows diffuse enhancement throughout this neurofibroma The MR easily distinguishes this solid tumor from a more common expansile lesion, the mucocele Sinonasal Benign Mixed Tumor > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Benign Tumors and Tumorlike Lesions > Sinonasal Benign Mixed Tumor Sinonasal Benign Mixed Tumor Michelle A Michel, MD Key Facts Terminology Synonym: Pleomorphic adenoma Benign, histologically heterogeneous tumor compromised of epithelial, myoepithelial, & stromal components Imaging Originates in nasal cavity (septum > lateral nasal) > paranasal sinuses CT findings Well-demarcated soft tissue mass in anterior nasal cavity often arising from septum Bone remodeled rather than destroyed MR findings Typically very high T2 signal Variable enhancement; heterogeneous in larger lesions Top Differential Diagnoses Sinonasal solitary polyp Sinonasal inverted papilloma Juvenile angiofibroma Sinonasal nerve sheath tumor Pathology Thought to arise from minor salivary rests Nasal septal BMT tends to be highly cellular with little stromal component (compared to salivary gland tumors) Clinical Issues Presentation Nasal obstruction ± epistaxis Most present at 30-60 years Slow growing with excellent prognosis 966 Diagnostic Imaging Head and Neck (Left) Axial NECT shows a well-defined soft tissue mass centered at the junction of the nasal vestibule and nasal cavity There is remodeling of the nasal process of the maxilla and no invasion of the nasolacrimal duct (Right) Coronal bone CT demonstrates a circumscribed benign mixed tumor in the right nasal cavity adjacent to the nasal septum There is lateral displacement and remodeling, but not destruction, of the lateral nasal wall , which is typical of a benign lesion (Left) Axial T2WI FS MR shows a large, well-defined, hyperintense benign mixed tumor obstructing the posterior nasal cavity and extending into the nasopharynx Obstructed secretions are noted in both maxillary sinuses (Right) Sagittal T1WI C+ FS MR in the same patient demonstrates homogeneous enhancement throughout the lesion Additional mucosal disease is seen in the ethmoid sinuses Enhancement patterns in benign mixed tumors are highly variable Malignant Tumors Sinonasal Squamous Cell Carcinoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Sinonasal Squamous Cell Carcinoma Sinonasal Squamous Cell Carcinoma Michelle A Michel, MD Key Facts Terminology Malignant epithelial tumor with squamous cell or epidermoid differentiation 967 Diagnostic Imaging Head and Neck Imaging Location: Maxillary antrum involved > 80% CT findings Soft tissue density mass with irregular margins Aggressive bone destruction MR findings ↓ T2 signal due to ↑ N:C ratio Enhances to lesser degree than other sinonasal malignancies Multiplanar enhanced MR optimal for tumor mapping, detection of PNTS & nodes Top Differential Diagnoses Sinonasal adenocarcinoma Sinonasal undifferentiated carcinoma (SNUC) Invasive fungal sinusitis Sinonasal non-Hodgkin lymphoma Wegener granulomatosis Pathology Risk factors: Inhaled wood dust, metallic particles, chemicals, HPV, inverted papilloma Clinical Issues Symptoms mimic chronic sinusitis & delay diagnosis Age at presentation: 50-70 years old M>F Most common malignancy of sinonasal area 15% maxillary sinus SCCa have malignant adenopathy Overall 5-year survival: 60% Combined surgery & XRT most common treatment (Left) Coronal graphic shows the typical features of an aggressive right maxillary SCCa with destruction of the maxillary sinus walls Extension into the orbit , maxillary alveolus , and buccal space is noted (Right) Axial CECT shows the typical location and appearance of an antral SCCa There is extension into the premaxillary soft tissues anteriorly and through the posterior maxillary wall into the infratemporal fossa 968 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR shows a large antral SCCa The signal of the mass is similar to other soft tissues There is extension anteriorly into the premaxillary soft tissues , medially into the nasal cavity , and posteriorly into the masticator space (Right) Coronal T2WI FS MR in the same patient demonstrates ethmoid sinus involvement and masticator space extension The low T2 signal of this mass is consistent with high cellularity and N:C ratio P.IV(1):91 TERMINOLOGY Abbreviations Squamous cell carcinoma (SCCa) Synonyms Epidermoid carcinoma, transitional carcinoma, nonkeratinizing carcinoma, respiratory mucosal carcinoma Definitions Malignant epithelial tumor growing from sinus surface epithelium into sinus lumen with squamous cell or epidermoid differentiation IMAGING General Features Best diagnostic clue Aggressive antral soft tissue mass with invasion & destruction of sinus walls Location 75% arise in sinuses; ≈ 30% arise primarily in nose Maxillary antrum (85%), ethmoid (10%), frontal/sphenoid (< 5%) Radiologist creates presurgical tumor map of spread Medial: Nasal cavity → ethmoid sinuses Anterior: Subcutaneous tissues of cheek Posterior: Retroantral fat pad, pterygopalatine fossa (PPF) & masticator space Lateral: Malar eminence & subcutaneous tissues Superior: Through orbital floor into orbit proper or via PPF → inferior orbital fissure → orbit Perineural tumor spread (PNTS): Inferior orbital nerve or PPF → V2 (foramen rotundum) → cavernous sinus Size Usually fills maxillary antrum Morphology Well defined to poorly defined with irregular, spiculated margins CT Findings CECT Solid, moderately enhancing mass with aggressive bone destruction Enhancement tends to be heterogeneous Nonenhancing areas may represent necrosis 969 Diagnostic Imaging Head and Neck Bone CT Bone destruction is characteristic Soft tissue density mass with irregular margins MR Findings T1WI Intermediate signal mass, similar to muscle signal Areas of intratumoral hemorrhage may show ↑ T1 signal T2WI Intermediate to high signal compared to musculature, but lower than other sinonasal malignancies ↓ T2 signal due to ↑ cellularity & ↑ nuclear:cytoplasmic ratio T2 differentiates high signal obstructed sinus secretions from tumor T1WI C+ Enhancement typically mild to moderate; diffuse, but heterogeneous Enhances to lesser degree than adenocarcinoma, esthesioneuroblastoma, melanoma Areas of necrosis not enhance T1 C+ fat-saturated images optimal for detecting PNTS Nuclear Medicine Findings PET Avid uptake of F18 FDG due to hypermetabolism If SCCa arose in inverted papilloma (IPap), both may show avid FDG uptake Imaging Recommendations Best imaging tool Most are initially diagnosed on routine NECT for evaluation of “sinusitis type” symptoms Multiplanar enhanced MR optimal for tumor mapping, detection of PNTS, & retropharyngeal nodes Protocol advice Pre-contrast T1 & post-contrast T1 MR with fat suppression from sellar floor to hyoid bone DIFFERENTIAL DIAGNOSIS Sinonasal Adenocarcinoma Imaging features can be similar to SCCa Predilection for ethmoid sinus Tends to enhance more than SCCa Sinonasal Undifferentiated Carcinoma (SNUC) Can be impossible to distinguish from SCCa Rapidly growing Invasive Fungal Sinusitis Immunocompromised patient Rapidly progressive destructive lesion ICA invasion and thrombosis may be associated Sinonasal Non-Hodgkin Lymphoma Midline nasal location is typical Tendency to cause nasal septum destruction May exactly mimic Wegener granulomatosis Wegener Granulomatosis Septal and nonseptal bone destruction in nose Chronic sinusitis associated Sinonasal disease associated with tracheobronchial and renal disease PATHOLOGY General Features Etiology Risk factors: Inhaled wood dust, metallic particles, & chemicals used in leather & textile industries; Thorotrast exposure Formaldehyde & asbestos exposure may ↑ risk Human papilloma virus, pre- or coexisting inverted papilloma ↑ risk No direct link to smoking P.IV(1):92 Staging, Grading, & Classification Maxillary sinus primary tumor (T) staging criteria T1: Maxillary antrum only; no bone destruction 970 Diagnostic Imaging Head and Neck T2: Bone invasion (hard palate, nasal wall); not involving posterior wall maxillary sinus or pterygoid plates T3: Invades bone of posterior wall ± subcutaneous tissues ± floor of medial orbital wall ± pterygoid fossa ± ethmoid sinuses T4a (resectable): Invades anterior orbit, skin, infratemporal fossa, pterygoid plates, cribriform plate, frontal or sphenoid sinuses, T4b (unresectable): Involves orbital apex, dura, brain, middle fossa, clivus, nasopharynx, cranial nerves (other than V2) Staging taken from AJCC staging tables (2010) Gross Pathologic & Surgical Features Friable, polypoid, papillary, or fungating soft tissue mass Tan to white or red to pink color Aggressive spread into adjacent structures Microscopic Features main subtypes: Keratinizing (80%) & nonkeratinizing (20%) Keratinizing: Papillary, exophytic, or inverted architectural patterns; surface & individual cell keratinization, dyskeratosis, poorly differentiated to well differentiated Nonkeratinizing: Papillary or exophytic growth pattern; interconnecting bands of neoplastic epithelium; hypercellular, pleomorphism, mitotic activity Papillary variant of SCCa uncommon CLINICAL ISSUES Presentation Most common signs/symptoms Symptoms mimic chronic sinusitis (antral lesions) & may delay diagnosis Nasal cavity primaries present earlier with nasal obstruction, bleeding Other signs/symptoms Larger maxillary tumors: Unilateral nasal obstruction, epistaxis, nasal discharge, & cheek numbness Tooth pain or loosening, proptosis & diplopia, trismus, facial asymmetry, nonhealing sore or ulcer Clinical profile Older male patient presenting with symptoms of sinusitis refractory to medical therapy Demographics Age 50-70 years old 95% > 40 years old Gender M>F Epidemiology 3% of H&N neoplasms Most common malignancy of sinonasal area SCCa accounts for 80% of malignant tumors of sinonasal area 15% of maxillary sinus SCCa have malignant adenopathy Retropharyngeal or level II jugular chain nodes 0.2% of patients with H&N SCCa elsewhere develop 2nd primary in sinonasal region ↑ incidence in those with history of radiation therapy to H&N ↑ incidence in immunosuppressed patients Natural History & Prognosis Overall 5-year survival: 60% Survival statistics heavily influenced by tumor stage T1 SCCa treated aggressively have 100% survival (rarely diagnosed at T1 primary stage) 5-year survival rates for T4a primary SCCa drop to 34% Better prognosis: Ethmoid sinus SCCa, low tumor stage, tumor HPV(+), treatment with both surgery & XRT & history of inverted papilloma Worse prognosis: Extension beyond sinus walls, regional nodal disease, PNTS, large primary size Relapse occurs at primary site > regional lymph nodes If tumor recurs, 90% < 1-year survival Treatment Combined treatment with surgery & XRT En bloc resection vs endoscopic resection depending on tumor size & structures involved XRT may be conventional, 3D conformal, or IMRT 971 Diagnostic Imaging Head and Neck Chemotherapy gaining popularity as genetics of SCCa better understood DIAGNOSTIC CHECKLIST Consider SCCa primary diagnosis in adult male with aggressive soft tissue mass in maxillary antrum Image Interpretation Pearls ↓ T2 signal & tendency to enhance less than other sinonasal malignancies Reporting Tips Be sure to evaluate for extension into orbit, masticator space, palate Check PPF & foramen rotundum for V2 PNTS SELECTED REFERENCES Jeon TY et al: 18F-FDG PET/CT findings of sinonasal inverted papilloma with or without coexistent malignancy: comparison with MR imaging findings in eight patients Neuroradiology 51(4):265-71, 2009 Lee CH et al: Survival rates of sinonasal squamous cell carcinoma with the new AJCC staging system Arch Otolaryngol Head Neck Surg 133(2):131-4, 2007 Raghavan P et al: Magnetic resonance imaging of sinonasal malignancies Top Magn Reson Imaging 18(4):259-67, 2007 Loevner LA et al: Imaging of neoplasms of the paranasal sinuses Magn Reson Imaging Clin N Am 10(3): 467-93, 2002 P.IV(1):93 Image Gallery (Left) Coronal CT reconstruction shows a large mass filling the left nasal cavity with erosion of ipsilateral turbinates This SCCa eroded the inferior nasal septum The margins of the mass are difficult to delineate on the CT (Right) Coronal STIR MR in the same patient better defines the tumor margins Obstructed secretions within the maxillary & ethmoid sinuses are hyperintense compared to the tumor The low T2 tumor signal may be related to its high N:C ratio 972 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR shows a SCCa of the nasal cavity with involvement of the nasal septum , lateral spread into the pterygopalatine fossa , and posterior extension into the nasopharynx toward the skull base (Right) Axial T2WI FS MR in the same patient defines the tumor margins compared to mucosal thickening in the maxillary antrum , prevertebral muscles , and suppressed clival marrow Mastoid mucosal thickening is present due to eustachian tube obstruction (Left) Axial T1WI MR shows a very large antral SCCa with extension into the nasal cavity , infratemporal fossa , and clivus The mass encases the left internal carotid artery , but the flow void is preserved (Right) Axial T1WI C+ FS MR in the same patient shows homogeneous enhancement throughout the mass with no definite areas of necrosis Note invasion of the clivus and diffuse infiltration of the muscles of mastication Esthesioneuroblastoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Esthesioneuroblastoma Esthesioneuroblastoma Michelle A Michel, MD Key Facts Terminology Synonym: Olfactory neuroblastoma Rare malignant neuroectodermal tumor that arises in superior nasal cavity from olfactory mucosa Imaging Enhanced MR with bone-only CT best maps ENB for en bloc craniofacial surgery Dumbbell-shaped mass with “waist” at level of cribriform plate 973 Diagnostic Imaging Head and Neck Bone CT: Bone remodeling mixed with bone destruction, especially of cribriform plate CECT/T1 C+ MR: Homogeneously enhancing mass Cysts at intracranial tumor-brain margin Top Differential Diagnoses Sinonasal squamous cell carcinoma Sinonasal adenocarcinoma Sinonasal non-Hodgkin lymphoma Sinonasal undifferentiated carcinoma Pathology No etiologic basis or risk factors elucidated Kadish staging system Good predictor of outcome Clinical Issues Adolescent or middle-aged patient with unilateral nasal obstruction & mild epistaxis Bimodal distribution in 2nd & 6th decades Combined surgical resection & radiotherapy is treatment of choice Excellent prognosis vs other sinonasal malignancies 5-year survival rates: 75-77% overall Recurrences in ˜ 30% Metastases in 10-30% of patients (Left) Coronal graphic shows the classic features of esthesioneuroblastoma (ENB) centered below the cribriform plate and extending into the anterior cranial fossa and right orbit Cyst formation is noted at the tumor-brain interface (Right) Coronal bone CT shows an ENB filling the upper nasal cavity and ethmoid sinuses The lesion extends through the anterior skull base The lamina papyracea on the right is thinned and laterally displaced 974 Diagnostic Imaging Head and Neck (Left) Axial STIR MR demonstrates a large, heterogeneous ENB centered in the midline below the skull base and occupying the nasal cavity and ethmoid sinuses The mass is predominantly hypointense in this case and causes hypertelorism (Right) Coronal T1WI C+ FS MR shows an avidly enhancing ENB with extension into anterior cranial fossa and both orbits Avid enhancement is characteristic of this highly vascular neoplasm Note the trapped maxillary secretions P.IV(1):95 TERMINOLOGY Abbreviations Esthesioneuroblastoma (ENB) Synonyms Olfactory neuroblastoma, pleomorphic olfactory neuroblastoma Definitions Rare malignant neuroectodermal tumor that arises in nasal cavity IMAGING General Features Best diagnostic clue Dumbbell-shaped mass with upper portion in anterior cranial fossa, lower portion in upper nasal cavity, & “waist” at level of cribriform plate Peripheral tumor cysts at intracranial tumor-brain margin is highly suggestive of diagnosis of ENB Location Superior nasal cavity at cribriform plate Smaller ENB: Unilateral nasal mass centered on superior nasal wall; local spread in nose & sinuses Large ENB: Tumor in anterior cranial fossa with parenchymal & dural infiltration, extension into orbits Size Range from < cm nodule to mass filling entire nasal cavity & lower anterior cranial fossa Morphology Polypoid mass when small; dumbbell-shaped when large CT Findings NECT Bone CT Bone remodeling causing enlargement of nasal cavity mixed with bone destruction, especially of cribriform plate area Speckled pattern of calcification within tumor matrix unusual CECT Homogeneously enhancing mass When large, may see nonenhancing areas of necrosis MR Findings 975 Diagnostic Imaging Head and Neck T1WI Hypointense to intermediate signal intensity mass compared to brain Areas of hemorrhage can be hyperintense T2WI Intermediate to hyperintense to brain Areas of cystic degeneration are hyperintense Obstructed secretions in adjacent sinuses are hyperintense Hemorrhagic foci are hypo- to hyperintense depending on age of blood Intracranial cysts at tumor-brain interface are hyperintense T1WI C+ Avid homogeneous tumor enhancement Enhancement heterogeneous in areas of necrosis Imaging Recommendations Best imaging tool Enhanced MR with bone-only CT best maps ENB for en bloc craniofacial surgery Protocol advice Bone-only CT shows precise extent of bone destruction & may alter extent of craniofacial resection T2 MR sequences best differentiate tumor from sinus secretions Multiplanar post-gadolinium fat-suppressed sequences for evaluation of tumor extension beyond sinonasal (SN) cavities DIFFERENTIAL DIAGNOSIS Sinonasal Squamous Cell Carcinoma More common in maxillary antrum than nasal cavity Does not enhance to same degree as ENB Sinonasal Adenocarcinoma Wood dust & occupational exposures are risk factors Predilection for ethmoid origin with nasal cavity involvement Enhances less avidly & more heterogeneously than ENB Anterior Skull Base Meningioma May cause hyperostosis in adjacent skull base Not associated with cyst formation at tumor-brain interface Non-Hodgkin Lymphoma Dense on NECT Does not enhance to same degree as ENB Rarely breaches skull base Sinonasal Melanoma Favors lower nasal cavity as site of origin (septum & turbinates) ↑ T1 & ↓ T2 signal classic Sinonasal Undifferentiated Carcinoma Difficult to distinguish from ENB on imaging Not confined to cribriform plate/superior nasal cavity Usually in older patients PATHOLOGY General Features Etiology No etiologic basis or risk factors elucidated Tumor of neural crest origin & begins in olfactory mucosa in superior nasal cavity at cribriform plate Associated abnormalities ENB patients occasionally present with paraneoplastic symptoms Cushing syndrome → adrenocorticotrophic hormone secretion Hyponatremia → antidiuretic hormone secretion Staging, Grading, & Classification Histologic grading: Hyams' system P.IV(1):96 Grades 1-4 based upon architectural pleomorphism, neurofibrillary matrix, rosette formation, mitoses, necrosis, presence of gland formation, & calcifications Staging criteria: Kadish classification (good predictor of outcome) 976 Diagnostic Imaging Head and Neck Stage A: Localized to nasal cavity Stage B: Localized to nasal cavity & sinuses Stage C: Extends beyond sinonasal cavities Gross Pathologic & Surgical Features Clinically appears as a firm, nonpulsatile mass covered by intact respiratory mucosa Tumor may bleed profusely on biopsy Broad-based, pedunculated, lobulated, mucosal-covered mass at cribriform plate; soft, glistening May show engorged, red appearance due to rich, vascular stroma Microscopic Features Submucosal lesion with prominent nested appearance Neurofibrillary intercellular matrix & rosette formations Mild nuclear pleomorphism with low mitotic activity most common Frequently contains areas of necrosis & calcification Electron microscopy Shows neurosecretory granules May help make correct diagnosis when light microscopy is inconclusive When only sheets of small round cells are identified, incorrect histopathologic diagnosis may occur SN undifferentiated carcinoma, NHL, melanoma, & rhabdomyosarcoma may be misdiagnosed in this ENB setting CLINICAL ISSUES Presentation Most common signs/symptoms Nasal obstruction & epistaxis Symptoms usually pre-date diagnosis by 6-12 months Other signs/symptoms Anosmia, rhinorrhea Hypertelorism, proptosis, diplopia, & epiphora Headache Cranial neuropathies suggest skull base/cavernous sinus involvement Clinical profile Adolescent or middle-aged patient with unilateral nasal obstruction & mild epistaxis Demographics Age Occurs predominantly in young adults Wide range: 3-88 years Bimodal distribution in 2nd & 6th decades Gender Slight male predominance Epidemiology 2-3% of all intranasal neoplasms Natural History & Prognosis 5-year survival rates: 75-77% overall Staging & tumor grade are significant prognostic indicators 5-year disease-free survival Kadish stage A: > 90% Kadish stage B: > 68% Kadish stage C: < 67% Negative prognostic indicators Female sex, age less than 20 or over 50 years at presentation Higher tumor grade Extensive intracranial spread Cervical or distant metastasis Recurrences in ˜ 30% & may occur up to 15 years after primary diagnosis Metastases in 10-30% of patients Lymphatic spread to cervical lymph nodes Hematogenous to parotid glands, skin, lung, bone, liver, & spinal cord Treatment Combined therapy using craniofacial resection & radiotherapy is treatment of choice Radiotherapy offers better local control since negative resection margins often difficult to achieve 977 Diagnostic Imaging Head and Neck Low-stage resectable tumors may be approached endoscopically in selected patients Chemotherapy reserved for larger, high-grade ENB & disseminated disease DIAGNOSTIC CHECKLIST Consider Using both preoperative CT & MR imaging Bone CT for detection of extent of bone destruction by ENB MR for precise mapping of tumor soft tissue extent Image Interpretation Pearls Dumbell-shaped mass with waist at cribriform plate + intracranial marginal cysts are characteristic of ENB SELECTED REFERENCES Faragalla H et al: Olfactory neuroblastoma: a review and update Adv Anat Pathol 16(5):322-31, 2009 Tseng J et al: Peripheral cysts: a distinguishing feature of esthesioneuroblastoma with intracranial extension Ear Nose Throat J 88(6):E14, 2009 Ward PD et al: Esthesioneuroblastoma: Results and Outcomes of a Single Institution's Experience Skull Base 19(2):133-40, 2009 Yu T et al: Esthesioneuroblastoma methods of intracranial extension: CT and MR imaging findings Neuroradiology 51(12):841-50, 2009 Nichols AC et al: Esthesioneuroblastoma: the massachusetts eye and ear infirmary and massachusetts general hospital experience with craniofacial resection, proton beam radiation, and chemotherapy Skull Base 18(5):327-37, 2008 Zollinger LV et al: Retropharyngeal lymph node metastasis from esthesioneuroblastoma: a review of the therapeutic and prognostic implications AJNR Am J Neuroradiol 29(8):1561-3, 2008 Schuster JJ et al: MR of esthesioneuroblastoma (olfactory neuroblastoma) and appearance after craniofacial resection AJNR Am J Neuroradiol 15(6): 1169-77, 1994 P.IV(1):97 Image Gallery (Left) Axial T2WI FS MR shows diffuse intermediate to low signal within an ENB centered in the left nasal cavity Extension into the left orbit is seen Trapped secretions are noted in the left sphenoid sinus (Right) Coronal T1 C+ MR shows intracranial extension of a left nasal cavity esthesioneuroblastoma The tumor avidly enhances and invades dura causing a “dural tail” Invasion of left frontal lobe and left orbit was present in this case 978 Diagnostic Imaging Head and Neck (Left) Coronal T2WI MR demonstrates a very large ENB with extension into both orbits and into the anterior cranial fossa Despite large intracranial component, only brain edema and not parenchymal invasion was seen in this case (Right) Axial T1WI C+ MR shows diffuse, homogeneous enhancement throughout an esthesioneuroblastoma centered in the right nasal cavity This ENB crossed the midline through the nasal septum (Left) Axial T1WI C+ FS MR in an elderly man shows the intracranial component of a large, avidly enhancing ENB Multiple cysts are noted at the tumor-brain interface, a characteristic feature of this tumor (Right) Axial bone CT shows a somewhat unusual calcified tumor matrix within a recurrent left-sided ENB Invasion of anterior nasal soft tissues is present Note air-filled cavity resulting from prior maxillectomy Sinonasal Adenocarcinoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Sinonasal Adenocarcinoma Sinonasal Adenocarcinoma Michelle A Michel, MD Key Facts Terminology Malignant neoplasm with glandular differentiation, or arising from surface epithelium or minor salivary rests Imaging Predilection for nasal cavity & ethmoid sinuses May reach large size due to delay in diagnosis 75% with involvement of > SN area at diagnosis CT 979 Diagnostic Imaging Head and Neck Well- to poorly defined soft tissue density mass Bone destruction > remodeling MR Typically intermediate to hyperintense T2 signal Diffuse, heterogeneous enhancement Top Differential Diagnoses Sinonasal squamous cell carcinoma Esthesioneuroblastoma Sinonasal undifferentiated carcinoma Sinonasal non-Hodgkin lymphoma Pathology Confusion remains regarding histologic classification of SN AdenoCa Wood dust exposure has strong link to intestinal subtype Accounts for 15% of all SN cancers Clinical Issues 6th decade most common M > F (≈ 3:1) Poor prognosis with higher grades, incomplete resection, & intracranial involvement Complete surgical excision for cure (Left) Axial CECT shows a large, heterogeneously enhancing adenocarcinoma filling the upper nasal cavity and ethmoid sinuses There is anterior extension into the soft tissues of the nasal dorsum and destruction of the lamina papyracea (Right) Sagittal T1WI MR shows a large adenocarcinoma filling the nasal cavity and extending into the nasopharynx No extension through the skull base is seen The lesion extends into the subcutaneous fat anteriorly 980 Diagnostic Imaging Head and Neck (Left) Axial T2WI MR demonstrates a large, heterogeneous adenocarcinoma of the ethmoid region filling the nasal cavity and causing significant mass effect upon both orbits Obstructed secretions are present in the sphenoid sinuses (Right) Axial T1WI C+ FS MR shows a left nasal cavity adenocarcinoma The mass enhances in an irregular fashion The left maxillary sinus is obstructed with peripheral (but no central) enhancement around the retained secretions P.IV(1):99 TERMINOLOGY Abbreviations Sinonasal adenocarcinoma (SN AdenoCa) Definitions Malignant neoplasm with glandular differentiation or arising from surface epithelium or minor salivary rests IMAGING General Features Best diagnostic clue Poorly defined, enhancing sinonasal mass with ethmoid sinus, nasal cavity, & skull base involvement Location Predilection for nasal cavity & ethmoid sinuses Size May reach large size due to delay in diagnosis CT Findings NECT Well- to poorly defined soft tissue density mass CECT Diffuse, often heterogeneous enhancement Bone CT Bone destruction > remodeling MR Findings T1WI Intermediate signal; ↑ signal in foci of hemorrhage T2WI Variable; typically intermediate to hyperintense T1WI C+ Diffuse, heterogeneous enhancement Imaging Recommendations Best imaging tool Multiplanar enhanced MR DIFFERENTIAL DIAGNOSIS Sinonasal Squamous Cell Carcinoma Usually in maxillary antrum; more ill defined Esthesioneuroblastoma 981 Diagnostic Imaging Head and Neck Adolescent or middle-aged Near cribriform plate; intense enhancement Sinonasal Undifferentiated Carcinoma (SNUC) Can look very similar to SN AdenoCa Aggressive with rapid growth Sinonasal Non-Hodgkin Lymphoma Predilection for nasal cavity Homogeneous, ↓ T2 signal PATHOLOGY General Features Etiology Wood dust exposure has strong link to intestinal-type AdenoCa Staging, Grading, & Classification Subtypes include Intestinal: Most frequent form colonic (40%) followed by solid (20%), papillary (18%), and mucinous and mixed type (together 22%) Nonintestinal subtypes (not related to wood dust exposure) Gross Pathologic & Surgical Features Tan-white-pink, flat, exophytic, or papillary; friable to firm lesion Microscopic Features Well differentiated Unencapsulated tumor, uniform glands with cystic spaces, no stroma Poorly differentiated Invasive tumor with solid growth pattern, pleomorphism, ↑ mitoses Colonic (intestinal) type: Invasive with various growth patterns (papillary-tubular, alveolar-mucoid, alveolargoblet/signet ring, & mixed) CLINICAL ISSUES Presentation Most common signs/symptoms Nasal stuffiness & obstruction Epistaxis Clinical profile Male in 6th decade with sinusitis-type symptoms Demographics Age 6th decade most common (mean age = 64 years) Gender M > F (≈ 3:1) Epidemiology 15% of all SN cancers Natural History & Prognosis Prognosis excellent for low-grade tumors, poor for high grade 5-year survival rates generally poor (≈ 50%) Treatment Complete surgical excision for cure Radiation therapy and chemotherapy used alone or in conjunction with surgery DIAGNOSTIC CHECKLIST Consider AdenoCa if history of occupational exposure & involvement of nasal cavity & ethmoid sinuses SELECTED REFERENCES Raghavan P et al: Magnetic resonance imaging of sinonasal malignancies Top Magn Reson Imaging 18(4):259-67, 2007 Orvidas LJ et al: Adenocarcinoma of the nose and paranasal sinuses: a retrospective study of diagnosis, histologic characteristics, and outcomes in 24 patients Head Neck 27(5):370-5, 2005 Sinonasal Melanoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Sinonasal Melanoma Sinonasal Melanoma 982 Diagnostic Imaging Head and Neck Michelle A Michel, MD Key Facts Terminology Neural crest cell malignancy arising from melanocytes in sinonasal mucosa Imaging Soft tissue mass in nasal cavity > paranasal sinuses with bone destruction ± remodeling Predilection for nasal septum, lateral nasal wall, & inferior turbinate MR (melanotic melanoma) ↑ T1 & ↓ T2 signal (due to melanin, free radicals, metal ions, & hemorrhage) Areas of hemorrhage may show “blooming” Avidly enhances due to vascularity (enhancement may be difficult to appreciate if ↑ pre-contrast T1 signal) Top Differential Diagnoses Squamous cell carcinoma Non-Hodgkin lymphoma Esthesioneuroblastoma Clinical Issues Adult with nasal stuffiness, epistaxis, & pigmented mass identified at nasal endoscopy 5th-8th decades most common M>F > 90% occurs in whites Poor prognosis with 6-17% chance of 5-year survival Mean survival ≈ 24 months Systemic metastatic disease typically precedes death Diagnostic Checklist Look for mass arising in lower nasal cavity with ↑ T1 and ↓ T2 signal (Left) Coronal graphic shows a darkly pigmented (highly melanotic) mass centered in the nasal cavity Invasion of the skull base , orbit , and lateral nasal wall is seen, but the septum is deviated rather than invaded Trapped secretions are noted in the left maxillary sinus (Right) Coronal bone CT in a patient with left nasal obstruction and epistaxis shows a mass in the left nasal cavity with erosion of the left middle turbinate and portions of the lateral nasal wall 983 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR demonstrates a mass in the left nasal cavity with maxillary sinus extension The lesion is heterogeneous with areas of T1 shortening and intermediate signal T1 shortening on unenhanced images may indicate the presence of melanin (Right) Axial T2WI FS MR shows a lobular melanoma within the left nasal cavity It is somewhat hypointense and is readily distinguishable from the hyperintense obstructed secretions in the maxillary sinus P.IV(1):101 TERMINOLOGY Abbreviations Sinonasal melanoma (SNM) Definitions Neural crest cell malignancy arising from melanocytes in sinonasal mucosa IMAGING General Features Best diagnostic clue ↑ T1 MR signal mass in nasal cavity Location Nasal cavity > sinuses Nasal septum, lateral wall, & inferior turbinate Size cm to large (filling nasal cavity or sinuses) CT Findings Bone CT Lobular soft tissue mass in nasal cavity Bone destruction ± remodeling MR Findings T1WI Melanotic melanoma: ↑ signal due to melanin, free radicals, metal ions, hemorrhage Amelanotic melanoma: Intermediate (soft tissue) signal T2WI Melanotic melanoma: ↓ signal Amelanotic melanoma: Variable signal T2* GRE Areas of hemorrhage may show “blooming” T1WI C+ Avidly enhancing Imaging Recommendations Best imaging tool Multiplanar MR imaging DIFFERENTIAL DIAGNOSIS 984 Diagnostic Imaging Head and Neck Sinonasal Squamous Cell Carcinoma Arises in antrum > nasal cavity Aggressive bone destruction; heterogeneous with variable enhancement Sinonasal Non-Hodgkin Lymphoma Nasal cavity mass with bone destruction ± remodeling Homogeneous; ↓ T2 signal; ↑ density on NECT Esthesioneuroblastoma Mass near cribriform plate with bone destruction Juvenile Angiofibroma Young male patient Posterior nasal cavity near sphenopalatine foramen PATHOLOGY General Features Etiology Arises from melanocytes of neural crest origin migrated to SN epithelium Gross Pathologic & Surgical Features Pink to dark colored, soft vascular nasal mass Microscopic Features Epithelioid, spindle, & mixed cell types Melanin heavily deposited, limited, or absent CLINICAL ISSUES Presentation Most common signs/symptoms Nasal obstruction, epistaxis Other signs/symptoms Pain, nasal deformity, hyposmia Demographics Age 5th-8th decades most common (range: 30-85 years) Gender M>F Epidemiology SNM < 1% of all melanomas & < 4% of all SN neoplasms > 90% occurs in whites Natural History & Prognosis Poor prognosis with 6-17% chance of 5-year survival Mean survival ≈ 24 months Eventual metastatic disease to lungs, lymph nodes, and brain typically precedes death Treatment Aggressive radical surgical excision with adjuvant radiotherapy DIAGNOSTIC CHECKLIST Consider Can appear similar to nasal polyp on CT if low melanin content Consider SNM if clinical history of nose bleeds and pigmented appearance on nasal endoscopy Image Interpretation Pearls Look for mass arising in lower nasal cavity with ↑ T1 and ↓ T2 signal SELECTED REFERENCES Dauer EH et al: Sinonasal melanoma: a clinicopathologic review of 61 cases Otolaryngol Head Neck Surg 138(3):347-52, 2008 Raghavan P et al: Magnetic resonance imaging of sinonasal malignancies Top Magn Reson Imaging 18(4):259-67, 2007 Kim SS et al: Malignant melanoma of the sinonasal cavity: explanation of magnetic resonance signal intensities with histopathologic characteristics Am J Otolaryngol 21(6):366-78, 2000 Yousem DM et al: Primary malignant melanoma of the sinonasal cavity: MR imaging evaluation Radiographics 16(5):1101-10, 1996 Sinonasal Non-Hodgkin Lymphoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Sinonasal Non-Hodgkin Lymphoma 985 Diagnostic Imaging Head and Neck Sinonasal Non-Hodgkin Lymphoma Michelle A Michel, MD Key Facts Terminology NHL-SN: Extranodal lymphoproliferative malignancy Imaging Appearance can mimic variety of neoplasms & aggressive inflammatory disorders Predilection for nasal cavity > sinuses CT: Homogeneous mass ± bone remodeling or destruction May be hyperdense due to high N:C ratio MR: ↓ T2 signal Variable homogeneous enhancement Imaging modality of choice: Multiplanar MR with post-contrast fat suppression Top Differential Diagnoses Sinonasal Wegener granulomatosis Sinonasal adenocarcinoma Esthesioneuroblastoma Sinonasal squamous cell carcinoma Pathology pathologic subgroups B-cell (Western) phenotype T-cell (Asian) phenotype NKTL (Asian): Subtype of T cell Clinical Issues Male patient in 6th decade with nonspecific symptoms of nasal obstruction & discharge Local radiotherapy (XRT) is primary treatment ± combination chemotherapy Diagnostic Checklist NHL could be included in DDx for almost any aggressive adult nasal soft tissue mass (Left) Axial CECT shows a large NHL centered in the nasal cavity with slightly heterogeneous enhancement There is gross destruction of the nasal septum Obstructed secretions are noted in both maxillary sinuses (Right) Axial STIR MR shows a large lymphoma involving the nasal cavity and ethmoid sinuses Hypointense long TR signal is characteristic of this tumor with high nuclear to cytoplasmic ratio Note the involvement of the right orbit with resulting proptosis 986 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows the classic location of sinonasal non-Hodgkin lymphoma The mass is centered around the nasal septum, and there is destruction of the septum as well as multiple ethmoid septations (Right) Axial T1WI C+ FS MR demonstrates a large lymphoma filling the left nasal cavity The septum is displaced but not eroded Homogeneous mild enhancement is present Trapped secretions are present in the left antrum P.IV(1):103 TERMINOLOGY Abbreviations Sinonasal non-Hodgkin lymphoma (NHL-SN) Diffuse large B-cell lymphoma (DLBCL) Natural killer/T-cell lymphoma (NKTL) Definitions NHL-SN: Extranodal lymphoproliferative malignancy most often of B-cell, T-cell, or NK/T-cell origin NKTL: Subtype of peripheral T-cell lymphoma NKTL previously called lethal midline granuloma, polymorphic reticulosis, angiocentric T-cell malignant lymphoma IMAGING General Features Best diagnostic clue Homogeneous soft tissue mass with predilection for nasal cavity ± bone destruction Very nonspecific imaging features NHL-SN can mimic variety of neoplasms & aggressive inflammatory disorders Location Nasal cavity > maxillary > ethmoid > frontal sinuses NKTL may have simultaneous involvement of nasopharynx & oropharynx in addition to sinonasal cavities Size Usually between 2-5 cm Morphology Variable: Diffusely infiltrative & ill-defined, nodular, or bulky mass CT Findings NECT Bulky, lobular soft tissue mass in nasal cavity ± sinuses May be hyperdense compared to soft tissue due to high nuclear-to-cytoplasmic (N:C) ratio NKTL: Infiltrative > polypoid soft tissue mass in nasal cavity ± ulceration/necrosis/bone destruction CECT Moderate homogeneous enhancement Bone CT Tends to remodel ± erode bone B-cell (Western) type: Soft tissue & osseous destruction 987 Diagnostic Imaging Head and Neck More likely to invade orbit T-cell (Asian) type: Nasal septal destruction & perforation more common MR Findings T1WI Intermediate, homogeneous signal similar to or slightly higher than muscle T2WI Low to intermediate homogeneous signal Due to highly cellular nature & ↑ N:C ratio T1WI C+ Variable, but diffuse & homogeneous enhancement Typically greater than muscle but less than mucosa Nonenhancing areas of necrosis more common in NKTL than in other NHL-SN Nuclear Medicine Findings PET May show moderate to avid uptake Can be falsely negative for malignancy Imaging Recommendations Best imaging tool Multiplanar, contrast-enhanced MR with post-contrast fat suppression MR better to delineate tumor margins & differentiate tumor from mucosal thickening & secretions Protocol advice Begin with thin section axial & coronal T1 & T2 sequences Follow with fat-suppressed T1 C+ MR in same planes through sinonasal area DIFFERENTIAL DIAGNOSIS Sinonasal Wegener Granulomatosis Can be indistinguishable from NHL-SN on imaging Favors nasal cavity (septum & turbinates) Requires laboratory/biopsy confirmation Sinonasal Adenocarcinoma More likely to originate in sinuses, particularly ethmoids May be related to occupational exposure Esthesioneuroblastoma Adolescent or middle-aged adult Superior nasal cavity near cribriform plate Typically higher T2 signal, more prominent enhancement Sinonasal Squamous Cell Carcinoma (SCCa) Most common in maxillary sinus More heterogeneous with frank bone destruction Sinonasal Melanoma Originates in nasal cavity ↑ T1 & ↓ T2 signal with avid enhancement Tendency for bony remodeling > destruction PATHOLOGY General Features Etiology Malignant lymphoproliferative disorder arising from variety of immune cell types subgroups B-cell (Western) phenotype: Most frequent type in paranasal sinuses; less aggressive T-cell (Asian) phenotype: More common in nasal cavity; more aggressive NKTL: Subtype of T-cell lymphoma; more common in nasal cavity; more aggressive Epstein-Barr virus (EBV) likely has a role in pathogenesis of NKTL P.IV(1):104 Associated abnormalities Lymph nodes infrequently involved Distant metastases seen in stage IV: Liver, spleen, brain, & bone marrow Staging, Grading, & Classification 988 Diagnostic Imaging Head and Neck Multiple staging systems: Ann Arbor staging system (IE to IVE), Murphy staging system Histologic classification: WHO system for lymphoid neoplasms (1999) Multiple additional classification systems: Rappaport, Luke-Collins, REAL (Revised European American Lymphoma) Large tumors & those with extranasal extension represent higher tumor stage Gross Pathologic & Surgical Features Polypoid, soft to rubbery mass with homogeneous pink-tan or bluish color Locally destructive & ulcerative Microscopic Features Monomorphous malignant cellular infiltrate of various types Various types are characterized immunophenotypically NKTL: Polymorphous cellular infiltrate of mononuclear cells growing in angiocentric, angiodestructive growth pattern Mucosal ulceration, pseudoepitheliomatous hyperplasia, & inflammatory infiltrate may be seen EBV(+) in nearly all cases CLINICAL ISSUES Presentation Most common signs/symptoms Nasal obstruction & discharge Symptoms mimic sinusitis, which leads to delay in diagnosis Bleeding more common in NKTL due to ulceration & necrosis Other signs/symptoms Unilateral facial swelling, otitis media, cervical adenopathy, headache NKTL: Septal cartilage destruction leads to “saddle-nose” deformity Clinical profile Male patient in 6th decade with nonspecific symptoms of nasal obstruction & discharge Demographics Age B-cell (Western) type: 6th decade T-cell (Asian) type: 7th decade Gender Western form: M = F Asian form: M > F Ethnicity B-cell type more common in United States & Europe Accounts for 55-85% of SN lymphomas in Western populations T-cell type more common in East Asia & Latin America NKTL type more common in Asians & South Americans Epidemiology < 1% of all H&N malignancies 0.2-2% of all lymphomas arise in SN cavities Malignant lymphoma is 2nd most common SN malignancy after SCCa < 50% of NHL occurs in H&N 60% of H&N NHL is extranodal (sinonasal, oral cavity, laryngopharynx, salivary glands) 44% of H&N extranodal lymphomas occur in sinonasal cavities Natural History & Prognosis B-cell type can have slow, indolent course if left untreated Prognosis generally good with > 50% 5-year survival Asian (T-cell) form has much worse prognosis; can be rapidly fatal NKTL: Worse prognosis than B-cell lymphoma, even though it usually manifests as local disease in nasal cavity 42% 5-year survival in stages I & II; 0% in stages III & IV Treatment Primary treatment: Local radiotherapy (XRT) Intermediate or more aggressive NHL-SN usually treated with combination chemotherapy or combination of radiation & chemotherapy NKTL: XRT for local disease; XRT & chemotherapy for multifocal or disseminated disease DIAGNOSTIC CHECKLIST Consider 989 Diagnostic Imaging Head and Neck Sinonasal NHL can be difficult to distinguish from other neoplasms, chronic sinusitis, & granulomatous disorders NHL could be included in DDx for almost any aggressive adult nasal soft tissue mass Differentiation from granulomatous disease requires biopsy & laboratory studies Image Interpretation Pearls Presence of enlarged cervical nodes & Waldeyer lymphatic mass may be clue to diagnosis Simultaneous involvement of nasopharynx & oropharynx in addition to sinonasal cavities is suggestive of NKTL, particularly in Asian patients SELECTED REFERENCES Kim J et al: Extranodal nasal-type NK/T-cell lymphoma: computed tomography findings of head and neck involvement Acta Radiol 51(2):164-9, 2010 Sands NB et al: Extranodal T-cell lymphoma of the sinonasal tract presenting as severe rhinitis: case series J Otolaryngol Head Neck Surg 37(4):528-33, 2008 Borges A et al: Midline destructive lesions of the sinonasal tract: simplified terminology based on histopathologic criteria AJNR Am J Neuroradiol 21(2):331-6, 2000 Harnsberger HR et al: Non-Hodgkin's lymphoma of the head and neck: CT evaluation of nodal and extranodal sites AJR Am J Roentgenol 149(4):785-91, 1987 P.IV(1):105 Image Gallery (Left) Axial CECT shows a homogeneous soft tissue mass filling the right nasal cavity This NHL did not destroy the nasal septum The lesion obstructs the right middle meatus, and trapped secretions are present in the right maxillary antrum (Right) Axial STIR MR shows the typical appearance of NHL on long TR images The highly cellular tumor is homogeneous and hypointense compared to the obstructed secretions in the adjacent maxillary sinuses 990 Diagnostic Imaging Head and Neck (Left) Axial CECT reveals a large, homogeneously enhancing NHL centered in the right nasal cavity and ethmoid sinuses The ethmoid septations are destroyed There is extension into the orbit & frontal sinus (Right) Coronal T1WI MR shows a large lymphoma filling the nasal cavity with destruction of the septum Trapped ethmoid secretions are hyperintense On this sequence, it is difficult to differentiate tumor vs trapped secretions in the maxillary sinuses (Left) Coronal T1WI C+ FS MR in the same patient shows diffuse enhancement throughout the lymphoma There is extension through the skull base into the anterior cranial fossa On this sequence, there is good differentiation of the tumor from trapped secretions in the maxillary sinuses (Right) Axial PET image performed at the time of diagnosis in the same patient shows diffuse, avid uptake of FDG in the lymphoma No other uptake was noted in the neck Sinonasal Undifferentiated Carcinoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Sinonasal Undifferentiated Carcinoma Sinonasal Undifferentiated Carcinoma Michelle A Michel, MD Key Facts Terminology Sinonasal undifferentiated carcinoma (SNUC) Rare, aggressive, sinonasal nonsquamous cell epithelial or nonepithelial malignant neoplasm of varying histogenesis Imaging 991 Diagnostic Imaging Head and Neck Aggressive sinonasal mass with bone destruction & rapid growth Large, typically > cm at presentation Origin most common in nasal cavity with extension into paranasal sinuses; ethmoid origin more common than maxillary Bone CT: Poorly defined, soft tissue SN mass with aggressive bone destruction MR: Isointense to muscle on T1 Low to intermediate T2 signal Heterogeneous enhancement with necrosis Top Differential Diagnoses Sinonasal squamous cell carcinoma Esthesioneuroblastoma Sinonasal non-Hodgkin lymphoma Sinonasal adenocarcinoma Clinical Issues Higher propensity for distant metastases to bone, brain & dura, liver, & cervical nodes than other sinonasal malignancies Diagnostic Checklist Imaging features are nonspecific Tumor growth rate & presence of nodes/distant metastases helpful for suggesting SNUC Consider extending coverage to evaluate for intracranial (particularly dural) & cervical nodal disease (Left) Axial NECT demonstrates a large mass in the left maxillary antrum with marked bone destruction and extension into the nasal cavity , masticator space , and soft tissues of the cheek Foci of air are seen within the necrotic portion of this rapidly growing lesion (Right) Coronal T1WI C+ FS MR in the same patient shows a thick, nodular enhancing rim at the periphery of the mass with central necrosis There is aggressive invasion of the orbit 992 Diagnostic Imaging Head and Neck (Left) Axial FLAIR MR demonstrates a large mass filling the right nasal cavity and extending into the right maxillary antrum There is extension into the retroantral fat Note the trapped secretions in the lateral aspect of the maxillary sinus (Right) Axial T1WI C+ MR in the same patient at the level of the nasopharynx shows a pathologic lateral retropharyngeal nodal metastasis from the patient's SNUC Sinonasal Adenoid Cystic Carcinoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Sinonasal Adenoid Cystic Carcinoma Sinonasal Adenoid Cystic Carcinoma Michelle A Michel, MD Key Facts Terminology Malignant salivary type of adenocarcinoma Imaging Location: Maxillary > nasal cavity Low grade: Solidly enhancing, well-defined soft tissue mass High grade: Poorly defined, heterogeneous + bone destruction ± perineural tumor spread (PNTS) Multiplanar, gadolinium-enhanced MR with fat suppression recommended Improves detection of PNTS Top Differential Diagnoses Sinonasal squamous cell carcinoma Sinonasal adenocarcinoma (intestinal-type) Esthesioneuroblastoma Sinonasal undifferentiated carcinoma Pathology Not associated with inhalation exposures histologic types Cribriform (52%); best survival Tubular (20%) Solid (29%); worst outcome; higher tendency for PNTS Most patients present with T4 disease (65%) Clinical Issues Sinonasal ACCa accounts for 10-25% of H&N ACCa Most common SN salivary tumor Symptoms mimic sinusitis Facial pain ± numbness (CNV2) → PNTS More common in Caucasians Overall 5-year survival: 50-86% Late recurrences not uncommon even > 15 years post initial therapy 993 Diagnostic Imaging Head and Neck (Left) Axial NECT shows a large, somewhat heterogeneous soft tissue mass centered in the sphenoid sinuses There is extension laterally into the right infratemporal fossa and posteriorly into the clivus Typical of sinonasal ACCa, this patient presented at an advanced T stage (Right) Axial T1WI C+ MR in the same patient demonstrates diffuse but heterogeneous enhancement throughout the mass There is extensive clival invasion The lesion extends into the nasal cavity (Left) Coronal bone CT shows opacification of the right maxillary sinus by a large, expansile ACCa The medial maxillary wall is eroded, and the mass extends into the nasal cavity Note leftward deviation of the nasal septum (Right) Axial T2WI MR in the same patient shows slightly heterogeneous, high signal throughout the mass Slight extension into the premaxillary soft tissues is noted The relatively well-defined appearance of the ACCa may suggest a lower grade histology Sinonasal Chondrosarcoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Sinonasal Chondrosarcoma Sinonasal Chondrosarcoma Michelle A Michel, MD Key Facts Imaging Arises from maxilla, nasal septum, & skull base Bone CT: Chondroid matrix calcification & narrow bony transition zone 50% with chondroid matrix MR: Increased (high) signal on long TR images & heterogeneous enhancement 994 Diagnostic Imaging Head and Neck Top Differential Diagnoses Sinonasal osteosarcoma Skull base meningioma Sinonasal ossifying fibroma Sinonasal fibrous dysplasia Esthesioneuroblastoma Pathology Malignant neoplasm arising from chondrocytes, embryonal rests, or mesenchymal cells May complicate Ollier & Maffucci syndromes Clinical Issues Presents in 5th-7th decades Duration from symptom onset to diagnosis: months to year Accounts for 0.1% of H&N cancers Surgical resection is primary treatment modality Difficult to achieve oncologic resection due to proximity of vital structures Late recurrences after long disease-free periods are reported; long-term follow-up advised Overall 5-year survival: 54-81% Diagnostic Checklist Arc-whorl or ring-like calcified matrix on CT in lesion with ↑ T2 MR signal may suggest diagnosis of chondrosarcoma (Left) Axial bone CT shows a bilobed chondrosarcoma centered around the nasal septum at the bone-cartilage junction Multiple chondroid calcifications are characteristics of this neoplasm The lateral nasal walls are remodeled in this case (Right) Axial STIR MR demonstrates a large chondrosarcoma involving the ethmoid sinuses bilaterally There is extension into the right orbit High signal on T2-weighted images is a common feature of this histology 995 Diagnostic Imaging Head and Neck (Left) Coronal CT reconstruction in the coronal plane shows a large, aggressive mass filling the ethmoid sinuses and nasal cavity with extension into the right orbit This chondrosarcoma has nonspecific features and lacks the classic chondroid matrix (Right) Axial T1WI C+ FS MR shows a chondrosarcoma of the left maxilla with involvement of the maxillary antrum The lesion enhances heterogeneously and extends into the premaxillary and retromaxillary fat pad soft tissues Sinonasal Osteosarcoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Nose and Sinus > Malignant Tumors > Sinonasal Osteosarcoma Sinonasal Osteosarcoma Michelle A Michel, MD Key Facts Terminology Rare malignant bone tumor arising from primitive bone-forming mesenchyma Imaging > 50% of craniofacial OSa arise in jaw Mandible > maxilla CT best for delineating osteoid matrix & cortical involvement Hyperdense mass with osteoid matrix & periosteal reaction MR optimal for evaluating extent within marrow & adjacent structures Top Differential Diagnoses Chondrosarcoma Ossifying fibroma Osteoma Fibrous dysplasia Metastasis Pathology Up to 25% are secondary malignancy in prior radiation field Increased incidence in hereditary retinoblastoma May arise in bone affected by Paget disease, fibrous dysplasia, multiple exostoses, enchondromatosis Clinical Issues Most present in 3rd-4th decades Older than classical OSa of long bones No strong gender predilection Craniofacial OSa accounts for 6-13% of all OSa Surgical resection is mainstay of treatment Neoadjuvant chemotherapy has significantly improved cure rates 996 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows an aggressive mass involving the maxilla with soft tissue filling the maxillary antrum and nasal cavity There is extension into the orbit and infratemporal fossa Note the “sunburst” periosteal reaction consistent with osteosarcoma (Right) Axial T1WI C+ FS MR shows an avidly enhancing left maxillary osteosarcoma filling the antrum and extending into the nasal cavity Central areas of low signal correlate with areas of ossification on CT (not shown) (Left) Axial T2WI FS MR demonstrates a large osteosarcoma centered around the lateral wall of the right maxillary sinus There is medial extension into the nasal cavity and lateral extension into the masticator space Linear hypointense radiating periosteal reaction is noted along the bone of origin (Right) Axial T1WI C+ FS MR in the same patient shows diffuse, avid enhancement throughout the soft tissue component of the mass The hypointense periosteal reaction is noted Section - Orbit Introduction and Overview Orbit Overview > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Introduction and Overview > Orbit Overview Orbit Overview H Christian Davidson, MD 997 Diagnostic Imaging Head and Neck Imaging Approach & Indications General Approach Imaging of the orbit encompasses two clinically distinct areas of ophthalmology The eye or globe The bony orbit, soft tissues, & periorbita Lesions in these two areas result in specific clinical profiles that affect different patient groups When a patient is referred for imaging, it is usually clear to the clinician whether the problem involves the eye proper versus some other structure of the orbit The term “orbital” refers to those bony structures and soft tissues that are extrinsic to the eye, as opposed to the term “ocular,” which refers to the globe itself Most imaging referrals come from oculoplastic surgeons, neuroophthalmologists, neurosurgeons, and otolaryngologists who need help characterizing orbital processes extrinsic to the globe However, in some instances imaging of the globe provides complementary information to the physical and ophthalmoscopic examination Ultrasound Ultrasound of the eye is a readily available complement to funduscopic examination and is traditionally performed in the ophthalmology clinic In addition to providing imaging of the globe, transocular ultrasound provides a limited, high-resolution assessment of other soft tissue orbital structures Because of the availability of ultrasound, many simple diagnoses can be made without the need of further imaging In this regard, imaging of the orbit is a function that is shared between the ophthalmologist and the neuroradiologist CT Because of its superior bony characterization, CT has advantages over MR for orbital lesions that arise from or directly affect the bones, such as epithelial inclusions, osteocartilaginous tumors with matrix, osteodystrophic processes, benign masses that cause bony scalloping, and aggressive malignancies that cause bony destruction The presence of calcification is a specific differentiating feature in some lesions, and therefore, CT can provide essential diagnostic information, even after an MR has be obtained Examples include retinoblastoma, perioptic meningioma, and end-stage ocular disease (phthisis bulbi) It is worth noting that orbital cavernous hemangioma, a common intraconal orbital mass in the adult, rarely shows phleboliths or calcification In many instances, CT can provide enough information to allow for a definitive diagnosis and guide therapy without the need for MR Examples include thyroid ophthalmopathy, clinically benign lacrimal mass, and orbital cavernous hemangioma When the diagnosis is clinically apparent, CT is often adequate to identify associated findings or complications that directly impact treatment decisions For example, in a patient with orbital cellulitis, enhanced CT can identify the presence of sinus disease &/or abscess, thus guiding surgical therapy In children, CT has the particular advantage of rapid acquisition that obviates the need for sedation However, the risk of radiation exposure is a mitigating factor that must also be considered MR For evaluating complex orbital disease, MR is the preferred modality Superior soft tissue differentiation and enhancement make MR ideal for characterizing the extent of complicated lesions, including extraocular tumors, vascular malformations, and complex inflammatory processes In particular, MR is the optimal modality for delineating the extent of malignant orbital disease Important features visible on MR include perineural tumor spread, optic nerve invasion, hematogenous or CSF disseminated metastases, and intracranial extension Although ultrasound is usually the first line for imaging the globe, MR can provide a more accurate visualization of retrobulbar extension of intraocular malignancy, including retinoblastoma, ocular melanoma, and ocular metastases Additionally, MR provides exquisite characterization of the globe itself, which is particularly useful in circumstances where funduscopic evaluation is obscured, such as swollen or injured eye, retinal detachment, large intraocular mass, vitreal hemorrhage, or opaque media from any cause Imaging Anatomy Bony Orbit Major portions of the bony orbital walls are contributed by the frontal bone superiorly, zygomatic bone laterally & inferiorly, maxillary bone inferiorly & medially, & ethmoid bone medially Smaller contributions medially include the lacrimal bone, nasal bone, & tiny portion of the palatine bone The sphenoid bone makes up a large portion of the orbit posteriorly and laterally, forming the complex foramina at the orbital apex Globe The aqueous-filled anterior segment includes anterior & posterior chambers, both anterior to the lens The vitreousfilled posterior segment occupies the bulk of the globe posteriorly There is limited visualization of other normal anatomical substructures on routine imaging Orbital Septum 998 Diagnostic Imaging Head and Neck Fascia arising from the orbital periosteum inserts onto the aponeurosis of the tarsal plates of the lids, providing a barrier between the anterior periorbita & the intraorbital contents Although the septum itself is often not discernible, its presence is readily evident when a disease process is contained on one side of the barrier Lacrimal Apparatus The lacrimal gland lies in a bony fossa at the anterior aspect of the superolateral orbit Lacrimal drainage is via canaliculi and sac at the inferomedial orbit, & from there through the nasolacrimal duct, which drains via the inferior meatus Extraocular Muscles (EOM) The four rectus muscles originate from the annulus of Zinn at the apex and insert on the corneoscleral surface The superior oblique has similar origin & insertion, but courses through the trochlea (“pulley”) at the superomedial orbital rim The inferior oblique has a short, more direct course originating from the anteroinferior orbital rim The levator palpebrae superioris originates at the annulus, coursing just above the superior rectus to insert at the upper eyelid P.IV(2):3 Optic Nerve-Sheath Complex Actually a central tract, the optic nerve (CN2) traverses the optic canal to insert at the optic nerve head The surrounding dural sheath is contiguous with the intracranial dura & the sclera A thin layer of CSF surrounding the nerve is typically visible on MR and is contiguous with CSF in the suprasellar cistern Peripheral Cranial Nerves CN3, CN4, & CN6 supply motor innervation to the EOMs and parasympathetics to the iris via CN3 These nerves are not reliably identifiable within the orbit However, knowledge of their course via the cavernous sinus and superior orbital fissure (SOF) allows localization of pathology that involves these nerves Two of the branches of CN5 course through the orbit V1 passes with other nerves in through the SOF, and V1 exits through the supraorbital foramen V2 passes through foramen rotundum and inferior orbital fissure (IOF) and exits through the infraorbital foramen Vascular Structures The ophthalmic artery enters the orbit within the optic nerve; it is frequently visible in the orbit as it exits the nerve near the apex The superior ophthalmic vein is found between the superior rectus muscle & the optic nerve Orbital Fat In addition to providing volume “filler” for the orbital cavity, orbital fat provides intrinsic imaging contrast, making other structures & disease processes more conspicuous Anatomy-based Imaging Issues In approaching orbital lesions, it is useful to localize the process to a subregion of the orbit & ascertain the relationship of the lesion to critical structures Globe: Is the lesion entirely intraocular or is there trans-scleral extension? Optic nerve: Does the lesion arise within the nerve proper or involve primarily the dural sheath? EOM: Is the lesion intraconal, extraconal, or does it arise from the muscles themselves? Is muscle involvement symmetric? Lacrimal gland: Is the lesion unilateral or is it bilateral, indicating a systemic process? Bone: Does the bone show benign scalloped remodeling or aggressive destruction? Focality: Is the lesion isolated or multiple? Does the lesion extend beyond the orbit? Imaging Protocols CT Routine imaging of the orbit with CT does not require special discussion, but one circumstance is worth noting: Intermittent proptosis due to orbital varix This dynamic lesion enlarges with increases in venous pressures & is best demonstrated with provocation After performing routine enhanced CT, the scan is repeated with the breath held in Valsalva maneuver, increasing venous pressures & enlarging the varix MR Routine imaging of the orbit with MR is usually adequate for the vast majority of ophthalmologic indications The protocol includes three sequences types: pre-contrast T1WI; T2WI with fat suppression, or STIR; and post-contrast T1WI with fat suppression Each of these is performed in axial & coronal planes at 3.0 mm slice thickness & 18 cm field of view Whole-brain imaging is added when indicated Pathologic Issues: Vascular Malformations Vascular malformations are congenital, nonneoplastic lesions in which classification reflects their histologic and hemodynamic features Lymphatic/venolymphatic malformation: Lesions may have no flow (type 1), venous flow (type 2), or may be mixed There may be a distensible component, resulting in varix Outdated terminology includes “lymphangioma” and “cystic hygroma.” 999 Diagnostic Imaging Head and Neck Venous malformation: Purely venous malformations occur elsewhere in the head and neck, but are relatively uncommon in the orbit unless part of a larger trans-spatial lesion The misnomer “hemangioma” should be avoided Orbital cavernous hemangioma (OCH): This common mass is actually a malformation that is unique to the orbit It is encapsulated, with low-flow arterial (type 3) hemodynamics, but also some venous features The term “OCH” is a misnomer, but is widely used Arteriovenous malformations (AVM): True orbital AVMs are rare lesions, with high-flow arterial (type 3) hemodynamics Selected References Rootman J Diseases of the Orbit: A Multidisciplinary Approach Philadelphia: Lippincott, 2003 Tables Differential Diagnosis: Orbit Congenital Lesions Coloboma Persistent hyperplastic primary vitreous Coats disease Orbital dermoid and epidermoid Orbital neurofibromatosis, type Vascular Lesions Orbital lymphatic malformation Orbital varix Infectious Lesions Benign Tumors Ocular toxocariasis Orbital infantile hemangioma Orbital subperiosteal abscess Optic pathway glioma Orbital cellulitis Inflammatory Lesions Orbital idiopathic pseudotumor Orbital sarcoidosis Thyroid ophthalmopathy Optic neuritis Orbital cavernous hemangioma Orbital infantile hemangioma * Optic nerve sheath meningioma Lacrimal gland benign mixed tumor Malignant Tumors Retinoblastoma Ocular melanoma Orbital lymphoproliferative lesions Lacrimal gland carcinoma Tumor-like Lesions Orbital Langerhans histiocytosis * Infantile hemangioma is classified as a benign neoplasm, but is also listed alongside the vascular malformations for comparison P.IV(2):4 Image Gallery 1000 Diagnostic Imaging Head and Neck (Top) Frontal graphic demonstrates the complex anatomy of the bony orbit The walls of the orbital cavity receive contributions from eight different bones of the skull The complex foramina and fissures at the apex are located primarily within the greater & lesser wings of the sphenoid bone and its junctions with adjacent bones (Bottom) Sagittal graphic demonstrates the anterior and posterior segments of the globe The aqueous anterior segment is comprised of the anterior chamber and very small posterior chamber The much larger posterior segment is filled by the vitreous chamber The layered tunicae of the retina, choroid, and sclera are demonstrated as well as the components of the optic nerve at its insertion Some of the extraocular muscles and and eyelid structures are also demonstrated P.IV(2):5 Image Gallery 1001 Diagnostic Imaging Head and Neck (Top) Coronal T1WI MR demonstrates the peripherally located extraocular muscles, the central optic nerve sheath complex, and the vascular structures of the orbit The intrinsic T1 signal of the orbital fat provides excellent contrast for visualizing the intraorbital contents (Bottom) Axial T2WI MR with fat suppression nearly eliminates signal from orbital fat, allowing for conspicuity of fluid signal structures A small amount of CSF surrounding the optic nerve is usually visible on T2WI The normal extraocular muscles show intermediate to low signal A small portion of the lacrimal gland is seen, but the majority of the gland is located further superiorly The anterior segment of the eye shows water signal, primarily representing the anterior chamber; the posterior chamber is not discernible on routine MR The posterior segment also shows water signal, comprised of the vitreous chamber Note that this patient has a prosthetic lens on the right Congenital Lesions Coloboma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Congenital Lesions > Coloboma 1002 Diagnostic Imaging Head and Neck Coloboma H Christian Davidson, MD Key Facts Terminology Coloboma = gap or defect of ocular tissue Types of posterior coloboma Optic disc coloboma (ODC) Choroidoretinal coloboma (CRC) Related but distinct anomalies Morning glory disc anomaly (MGDA) Peripapillary staphyloma (PPS) Imaging Focal defect at posterior pole of globe Outpouching contiguous with vitreous Retrobulbar colobomatous cyst often present Isodense on CT/isointense on MR relative to vitreous Top Differential Diagnoses Congenital microphthalmos Staphyloma Axial myopia Orbital neurofibromatosis type Congenital glaucoma Pathology Failure of embryonic fissure fusion Isolated, sporadic, and syndromic genetic etiologies Bilateral when syndromic Clinical Issues Decreased visual acuity; leukocoria Treatment to address refractive errors, strabismus, amblyopia, retinal detachment Diagnostic Checklist Look for syndromic and systemic associations MR of brain helpful if syndromic to look for intracranial abnormalities (Left) Axial graphic of classic optic disc coloboma shows a focal defect in the posterior globe at the site of the optic nerve head insertion (Right) Axial CECT demonstrates a dehiscence of the posterior globe through a broad defect centered on the upper margin of the optic disc Note that the vitreous appears contiguous to the retrobulbar outpouching, with similar density 1003 Diagnostic Imaging Head and Neck (Left) Axial T1WI of the orbit demonstrates a focal outpouching of the globe at the posterior pole The defect is located just above and medial to optic nerve head Note the adjacent course of the intraorbital optic nerve (Right) Axial T2WI in the same patient demonstrates a focal defect of the globe near the insertion of the optic nerve The signal within the outpouching is identical to that of the intraocular vitreous P.IV(2):7 TERMINOLOGY Abbreviations Optic disc coloboma (ODC) Choroidoretinal coloboma (CRC) Morning glory disc anomaly (MGDA) Peripapillary staphyloma (PPS) Definitions Coloboma = gap or defect of ocular tissue Types of posterior coloboma ODC: Excavation confined to optic disc CRC: Defect separate from or extends beyond disc Related anomalies MGDA: Defect with glial tissue & pigmented rim PPS: Congenital scleral defect at optic nerve head Other colobomatous lesions May involve any or all structures of embryonic cleft Iris, ciliary body, lens, or eyelid IMAGING General Features Best diagnostic clue Focal defect with outpouching at posterior pole of globe Vitreous contiguous with defect Location Posterior globe at optic nerve head insertion Size Usually small (few to several mm) MGDA & PPS larger than simple coloboma Morphology Crater-shaped excavation, contiguous with vitreous MGDA defect funnel-shaped with central glial tissue PPS defect encircles optic disc Laterality Unilateral when sporadic, bilateral when syndromic MGDA almost always unilateral, R > L 1004 Diagnostic Imaging Head and Neck PPS usually unilateral CT Findings NECT Fluid in defect ± retrobulbar cyst isodense to vitreous Subretinal hyperdensity if hemorrhage Bone CT Dystrophic Ca++ rare, seen at margins of longstanding defects MR Findings T1WI and T2WI Isointense to vitreous Complex signal if retinal detachment, including hemorrhagic or proteinaceous fluid (↑ T1 signal) Glial tuft of MGDA isointense to white matter Enhancement Sclera enhances; glial tuft in MGDA may enhance Otherwise no abnormal enhancement within defect Prenatal MR Bulging of posterior globe profile Single shot and balanced/true FISP techniques Ultrasonographic Findings Outpouching of posterior globe at optic nerve head Hypoechoic retrobulbar mass if cyst present Optical Coherence Tomography (OCT) Micrometer resolution images of retina Demonstrates detachment and pathology at margins Imaging Recommendations Best imaging tool MR or CT show globe and extraocular features, especially if defects prevent direct visualization CT provides reasonable depiction without sedation MR of brain helpful if syndromic to evaluate for intracranial abnormalities DIFFERENTIAL DIAGNOSIS Congenital Microphthalmos Congenital severe ocular derangement Deformed small globe with adjacent cyst Staphyloma Degenerative ectasia of globe Thinning of posterior sclera-uveal rim Enlarged globe, associated with myopia Axial Myopia Elongated anteroposterior dimension Orbital Neurofibromatosis Type Globe enlargement = “buphthalmos” Associated optic glioma, sphenoid wing dysplasia, plexiform neurofibroma Congenital Glaucoma Present a birth, usually bilateral Orbital Trauma Traumatic globe rupture results in globe deformity Associated intraocular hemorrhage PATHOLOGY General Features Etiology Embryological considerations Embryonic fissure extends along inferonasal aspect of optic cup and stalk Fissure fusion (5th-7th week) required for normal globe and nerve formation Coloboma (ODC/CRC) Failure of embryonic fissure fusion superiorly MGDA Faulty scleral closure (4th week) Mesoectodermal dysgenesis of optic nerve head PPS 1005 Diagnostic Imaging Head and Neck Incomplete differentiation of sclera Posterior neural crest cells Relationship of coloboma to MGDA & PPS uncertain Genetics Sporadic coloboma Noninherited Unilateral; especially isolated ODC Nonsyndromic coloboma P.IV(2):8 Typically autosomal dominant Identified with many specific mutations Syndromic coloboma Usually autosomal recessive Typically bilateral, especially CRC Associated with trisomies Dozens of syndromes (CHARGE, Aicardi, Papillorenal, COACH, Meckel, Warburg, Lenz) MGDA Typically sporadic; rare familial cases Unilateral, except when familial PPS Typically sporadic Unilateral, usually isolated anomaly Associated abnormalities Associated orbital findings Microphthalmia; optic tract & chiasm atrophy Retrobulbar colobomatous cyst Retinal detachment (25-40%) (ODC, MGDA) Congenital optic pit (ODC, MGDA) Cataract; hyaloid artery (ODC, MGDA) Iris coloboma (ODC) PHPV, aniridia (MGDA) Associated systemic abnormalities Renal, CNS, and many other systemic associations, particularly when bilateral Staging, Grading, & Classification Simple coloboma (normal globe and cornea) ˜ 15% Best prognosis Coloboma with microcornea (< 30 mm) ˜ 40% Better prognosis Coloboma with microcornea and microphthalmos ˜ 40% Worse prognosis Coloboma with microphthalmos and cyst ˜ 5% Worst prognosis Gross Pathologic & Surgical Features Coloboma (ODC/CRC) Funnel-shaped depression at fundus MGDA Tuft of whitish tissue overlying enlarged disc PPS Excavation that incorporates sunken optic disk Microscopic Features Coloboma (ODC/CRC) Invagination of gliotic retina into defect MGDA Central core of vascular connective and glial tissue PPS Large peripapillary defect, thinned sclera CLINICAL ISSUES 1006 Diagnostic Imaging Head and Neck Presentation Most common signs/symptoms Decreased visual acuity (VA) Other signs/symptoms Leukocoria Microphthalmia or anophthalmia in severe cases Associated syndromic features Clinical profile Vision depends on extent of optic disc involvement and retinal detachment Strabismus and nystagmus secondary to poor VA Reduced visual evoked potentials Funduscopic examination ODC Enlarged disc with excavation May resemble glaucomatous cupping CRC White with pigmented margins Extends inferiorly from or inferior to disc MGDA Enlarged, excavated disc; central core of tissue Central tuft of tissue with surrounding ring of pigment; resembles morning glory blossom PPS Central crater with recessed optic nerve Optic disc sunken, otherwise normal; atrophy of surrounding pigment epithelium Demographics Gender No gender predilection Except MGDA: M < F (1:2) Epidemiology Coloboma (nonsyndromic): 1:12,000 MGDA and PPS: Rare Natural History & Prognosis Visual acuity correlates with retinal status Detachment leads to precipitous vision loss Nerve atrophy and cataracts may lead to more insidious vision loss Treatment Address refractive errors, strabismus, amblyopia Retinal detachment management DIAGNOSTIC CHECKLIST Consider Coloboma is ophthalmoscopic diagnosis Imaging confirms ocular features and evaluates coexistent anomalies Image Interpretation Pearls Look for syndromic and systemic associations SELECTED REFERENCES Gopal L: A clinical and optical coherence tomography study of choroidal colobomas Curr Opin Ophthalmol 19(3):248-54, 2008 Righini A et al: Prenatal magnetic resonance imaging of optic nerve head coloboma Prenat Diagn 28(3):242-6, 2008 Altun E et al: Anterior coloboma with macrophthalmos and cyst: MR findings Clin Imaging 29(6):430-3, 2005 Vogt G et al: A population-based case-control study of isolated ocular coloboma Ophthalmic Epidemiol 12(3):1917, 2005 Chan RT et al: Morning Glory Syndrome Clin Exp Optometry 85(6):383-388, 2002 Hornby SJ et al: Regional variation in blindness in children due to microphthalmos, anophthalmos and coloboma Ophthalmic Epidemiol 7(2):127-38, 2000 P.IV(2):9 Image Gallery 1007 Diagnostic Imaging Head and Neck (Left) Axial T2WI FS MR shows a slightly small left globe with a broad posterior coloboma Two associated distinct colobomatous cysts are also present in the retrobulbar fat immediately posterior to the globe (Right) Axial T2WI FS MR in a patient with multiple congenital defects demonstrates a small colobomatous defect at the small posterior left globe An associated large retrobulbar cyst is also present (Left) Axial STIR MR in a patient with Aicardi syndrome demonstrates a moderate-sized left coloboma at the optic nerve insertion A large choroid plexus cyst is present , a common finding in patients with this X-linked syndrome (Right) Axial CECT in a patient with CHARGE syndrome shows a small defect at the posterior pole of the right eye with focal vitreal herniation The right eye is microphthalmic, with abnormal appearance of the lens 1008 Diagnostic Imaging Head and Neck (Left) Funduscopy shows large posterior coloboma centered at the optic nerve head , with marginal pigmentation suggesting chorioretinal involvement (Courtesy Moran Eye Center.) (Right) Funduscopy shows an enlarged funnel-shaped optic disc with central glial tissue as well as annular pigmentation , resulting in appearance that resembles a morning glory flower (Courtesy Moran Eye Center.) Persistent Hyperplastic Primary Vitreous > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Congenital Lesions > Persistent Hyperplastic Primary Vitreous Persistent Hyperplastic Primary Vitreous H Christian Davidson, MD Key Facts Terminology Congenital lesion due to incomplete regression of embryonic ocular blood supply Imaging “Martini glass” shape of enhancing soft tissue Triangular retrolental vascular tuft of tissue Central tissue stalk of hyaloid remnant Retinal detachment common Small globe, hyperdense vitreous Calcification rare Hyperintense blood with layering debris Top Differential Diagnoses Retinoblastoma Congenital cataract Coats disease Retinopathy of prematurity Pathology Normal fetal primary vitreous involutes by birth Failure of hyaloid regression causes remnant to persist in Cloquet canal Clinical Issues Leukocoria with poor vision and small eye Anterior type has better prognosis for vision Surgical options include lensectomy, vitrectomy Long-term management Amblyopia therapy and refractive correction Management of glaucoma and detachments Diagnostic Checklist Primary vitreous may be normally visible in premature infant PHPV is most common intraocular abnormality to be confused with retinoblastoma 1009 Diagnostic Imaging Head and Neck (Left) Sagittal graphic depicts persistent hyperplastic primary vitreous A triangular retrolental soft tissue mass is present , with stalk-like hyaloid remnant Note the large V-shaped retinal detachment (Right) Transverse ultrasound shows a linear echogenicity , extending posteriorly from the lens to the site of the optic nerve insertion, representing the fibrovascular remnant containing the hyaloid artery (Left) Axial T2WI FS MR shows the hyaloid remnant in the right eye extending from the lens to the posterior pole at the nerve insertion A hyperintense large retinal detachment is relatively inconspicuous compared to vitreous on T2WI (Right) Axial T1WI C+ FS MR shows the “martini glass” appearance of retrolental tuft of tissue with linear stalk extending to the optic nerve head A large hyperintense detachment is present , with associated hemorrhage and fluid level P.IV(2):11 TERMINOLOGY Abbreviations Persistent hyperplastic primary vitreous (PHPV) Definitions Congenital lesion due to incomplete regression of embryonic ocular blood supply IMAGING General Features Best diagnostic clue Retrolental soft tissue & stalk Hyperdense or hyperintense small globe Location 1010 Diagnostic Imaging Head and Neck Isolated posterior form (15-25%) Isolated anterior form (5-25%) Both anterior and posterior (50-80%) Unilateral > bilateral (3:1) Morphology “Martini glass” shape of enhancing soft tissue Triangular retrolental vascular tuft of tissue Central tissue stalk of hyaloid remnant Retinal detachment common Enhancement Retrolental tissue enhances, as does vitreous depending on degree of persistent vascularity CT Findings NECT Small globe, hyperdense vitreous Layering blood or debris may be present Calcification rare MR Findings Spin-echo MR Small globe, vitreous abnormally hyperintense on both T1WI and T2WI Hemorrhage and layering debris in vitreous Signal varies with age of blood Ultrasonographic Findings Lens displacement, hyperechoic retrolental stalk Imaging Recommendations Best imaging tool CT differentiates from retinoblastoma (Ca++) MR superior for differentiating noncalcified retinoblastoma from other causes of leukocoria Protocol advice Contrast enhancement is essential DIFFERENTIAL DIAGNOSIS Retinoblastoma Calcification differentiates from PHPV Congenital Cataract Malformed lens due to prenatal insult Coats Disease Exudative retinopathy with detachments Retinopathy of Prematurity Retrolental fibroplasia; small, dense globe PATHOLOGY General Features Etiology Primary vitreous = embryonic hyaloid vasculature of developing globe Normal fetal primary vitreous involutes by birth Failure of hyaloid regression causes remnant to persist in Cloquet canal Associated abnormalities PHPV usually isolated and unilateral Bilateral lesions associated with systemic or syndromic conditions including Norrie, Warburg Gross Pathologic & Surgical Features Retrolental tissue and thin stalk Slightly small globe; retinal detachment Microscopic Features Fibrovascular loose connective tissue Hyaloid artery remnant CLINICAL ISSUES Presentation Most common signs/symptoms Leukocoria with poor vision and small eye Other signs/symptoms Cataract, strabismus, nystagmus, uveitis 1011 Diagnostic Imaging Head and Neck Natural History & Prognosis Anterior: Best prognosis for vision Posterior: May have light/motion perception only Risk of secondary glaucoma Treatment Goals: Salvage vision, avoid glaucoma, pupil cosmesis Surgical options Anterior: Lensectomy, intraocular prosthetic lens Posterior: Vitrectomy, removal of hyaloid stalk Long-term management Amblyopia therapy and refractive correction Management of glaucoma and detachments DIAGNOSTIC CHECKLIST Consider Primary vitreous may be incompletely regressed and normally visible in premature infant Image Interpretation Pearls PHPV is most common intraocular abnormality to be confused with retinoblastoma SELECTED REFERENCES Cerón O et al: The vitreo-retinal manifestations of persistent hyperplasic primary vitreous (PHPV) and their management Int Ophthalmol Clin 48(2):53-62, 2008 Schulz E et al: Long-term visual function and relative amblyopia in posterior persistent hyperplastic primary vitreous (PHPV) Strabismus 14(2):121-5, 2006 Castillo M et al: Persistent hyperplastic primary vitreous involving the anterior eye AJNR Am J Neuroradiol 18(8):1526-8, 1997 Coats Disease > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Congenital Lesions > Coats Disease Coats Disease H Christian Davidson, MD Key Facts Terminology Retinal telangiectasias, exudative retinopathy Abnormal retinal capillary development leading to subretinal accumulation of exudate Imaging Subretinal exudate with retinal detachment Unilateral in 90%; bilateral when syndromic Affected eye slightly smaller than normal eye Typical V-shaped contour of retinal detachment CT Hyperdense exudate, calcification very uncommon MR Hyperintense proteinaceous, hemorrhagic exudate Nerve enhancement in advanced disease Ultrasound Linear detached retina and tiny cholesterol crystals Top Differential Diagnoses Retinoblastoma Persistent hyperplastic primary vitreous Retinopathy of prematurity Pathology Breakdown of blood-retinal endothelial barrier Cholesterol crystals and hemosiderin in exudate Clinical Issues Presents with leukocoria, vision loss Tortuous and dilated capillaries with tiny aneurysms Male predominance; onset within 1st decade Laser photocoagulation and cryotherapy Diagnostic Checklist Retinoblastoma is most important differential consideration 1012 Diagnostic Imaging Head and Neck (Left) Sagittal graphic depicts both dilatation and tiny aneurysms of retinal capillaries with associated large subretinal exudates and retinal detachments A subfoveal nodule is also demonstrated (Right) Axial NECT shows left globe posterior segment hyperdensity representing subretinal exudate composed of proteinaceous fluid and blood products The classic “V” shape of the detached retina is faintly visible (Left) Axial STIR MR demonstrates subretinal fluid that is less hyperintense than normal vitreous The detached retina shows a characteristic “V” shape extending from the optic nerve head (Right) Axial T1WI C+ FS MR shows large, mildly hyperintense subretinal exudates peripherally in the posterior segment of the left eye Rather than enhancement, the signal of the exudate is due to intrinsic T1 properties of the proteinaceous and cholesterol-laden fluid P.IV(2):13 TERMINOLOGY Synonyms Retinal telangiectasias Exudative retinitis, exudative retinopathy Definitions Abnormal retinal capillary development leading to subretinal accumulation of exudate IMAGING General Features Best diagnostic clue Subretinal exudate with retinal detachment Location 1013 Diagnostic Imaging Head and Neck Unilateral in 90%; bilateral when syndromic Size Affected eye slightly smaller than normal eye Morphology Typical V-shaped contour of retinal detachment Imaging Recommendations Protocol advice Correlate with CT to assess for calcification Always include contrast enhancement CT Findings NECT Hyperdense exudate, calcification very uncommon MR Findings T1WI Hyperintense proteinaceous, hemorrhagic exudate T2WI Hyperintense proteinaceous, hemorrhagic exudate T1WI C+ FS Nerve enhancement in advanced disease MRS Large peak at 1-1.6 ppm (lipids/proteolipids) Ultrasonographic Findings Grayscale ultrasound Linear detached retina and tiny cholesterol crystals DIFFERENTIAL DIAGNOSIS Retinoblastoma Calcification present in vast majority Persistent Hyperplastic Primary Vitreous Retrolental tissue and stalk in small eye Retinopathy of Prematurity Small globe, hyperdense, bilateral Ocular Toxocariasis Uveoscleral enhancement PATHOLOGY General Features Etiology Breakdown of blood-retinal endothelial barrier Cause unknown, possible genetic component Associated abnormalities Norrie disease X-linked recessive, mutation of NDP gene Bilateral, infantile onset, more severe Gross Pathologic & Surgical Features Retinal detachment with yellowish subretinal exudate May demonstrate fibrous nodule Microscopic Features Dilated capillaries, some vessel wall thickening Retinal gliosis and granulomatous reaction Cholesterol crystals and hemosiderin in exudate CLINICAL ISSUES Presentation Most common signs/symptoms Leukocoria, vision loss Other signs/symptoms Tortuous and dilated capillaries with tiny aneurysms on funduscopy Demographics Age Onset within 1st decade of life Uncommon variation presents in adults Gender 1014 Diagnostic Imaging Head and Neck Male predominance Natural History & Prognosis Vision spared in early stages Increasing exudate leads to retinal detachment Secondary glaucoma and blindness in late stages Adult variation shows limited involvement, slower progression, and tendency to hemorrhage Treatment Laser photocoagulation and cryotherapy Vitrectomy and retinal reattachment when advanced Bevacizumab (Avastin) to inhibit angiogenesis DIAGNOSTIC CHECKLIST Consider Retinoblastoma is most important differential consideration Image Interpretation Pearls Lack of calcification and enhancement distinguish Coats disease from retinoblastoma Smaller size of affected globe may help distinguish Coats disease from noncalcifying retinoblastoma SELECTED REFERENCES Dhoot DS et al: Optic nerve enhancement in Coats disease with secondary glaucoma J AAPOS 13(3):301-2, 2009 Adam RS et al: Observations on the management of Coats' disease: less is more Br J Ophthalmol 91(3):303-6, 2007 Galluzzi P et al: Coats disease: smaller volume of the affected globe Radiology 221(1):64-9, 2001 Coats G: Forms of retinal disease with massive exudation Royal London Ophthalmic Hospital Reports 17(3):440525, 1908 Orbital Dermoid and Epidermoid > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Congenital Lesions > Orbital Dermoid and Epidermoid Orbital Dermoid and Epidermoid H Christian Davidson, MD Key Facts Terminology Developmental orbital ectodermal inclusion cyst resulting in choristomatous mass lesion Dermoid: Includes dermal appendages Epidermoid: Dermal adnexa absent Imaging Cystic, well-demarcated, anterosuperior extraconal mass with lipid, fluid, or mixed contents May contain debris or fluid levels Adjacent to orbital periosteum, near suture lines Superolateral at frontozygomatic suture Osseous remodeling in majority of lesions Distinguishing features Dermoid: Typically but not exclusively contain fat; more heterogeneous Epidermoid: Density and intensity similar to fluid; more homogeneous Top Differential Diagnoses Dermolipoma Frontal or ethmoid sinus mucocele Lacrimal cyst Pathology Inclusion of trapped ectoderm at suture site Fibrous capsule lined by squamous epithelium Clinical Issues Firm, fixed, nontender mass at lateral eyebrow Slowly progressive; may rupture with inflammation Surgical resection is curative Diagnostic Checklist Features are distinctive, but deep or inflamed lesions may present diagnostic challenge Presence of fat is essentially pathognomonic 1015 Diagnostic Imaging Head and Neck (Left) Coronal graphic depicts a superotemporal dermoid cyst located adjacent to the frontozygomatic suture of the right orbit Notice resultant mass effect on the globe, with remodeling of the bony orbit (Right) Coronal CT demonstrates an ovoid, well-marginated cystic mass in the superotemporal quadrant of the right orbit Even on bone windows, the lipid density within the mass can be readily appreciated Smooth remodeling of the adjacent bony orbit is evident (Left) Axial T2WI MR shows a very large, lobulated mass centered at the deep superolateral aspect of the right orbit This epidermoid cyst shows fluid signal with some internal heterogeneity Marked thinning of the adjacent bony orbit and skull base is evident (Right) Axial T1WI C+ FS MR in the same patient shows low signal with mild irregularity in the epidermoid cyst , but no enhancement The lesion appears the same on pre-contrast T1WI (not shown), without evidence of lipid signal P.IV(2):15 TERMINOLOGY Synonyms Developmental orbital ectodermal inclusion cyst Dermoid = epidermal dermoid cyst Epidermoid = epidermal or epithelial cyst Definitions Cystic, choristomatous mass lesion of orbit resulting from congenital epithelial inclusion Choristoma = tumor composed of tissue that is histologically normal but located in abnormal site Dermoid lesions Epithelial elements plus dermal substructure, including dermal appendages 1016 Diagnostic Imaging Head and Neck Epidermoid lesions Epithelial elements without adnexal structures IMAGING General Features Best diagnostic clue Cystic, well-demarcated, anterosuperior extraconal mass with lipid, fluid, or mixed contents Location Adjacent to orbital periosteum, near suture lines Majority extraconal in superolateral aspect of anterior orbit, at frontozygomatic suture (65-75%) Size Typically < 1-2 cm in superficial lesions Larger in deep, complicated lesions Morphology Ovoid, well-demarcated cystic mass Most show thin definable wall (75%) No nodular soft tissue outside cyst (80%) Subtypes Superficial (simple, exophytic) Typically smaller, discrete, rounded Present in early childhood Deep (complicated, endophytic) More insidious, extensive bony changes If extend into temporal fossa → dumbbell shape Contents Internal fat or fluid features Lipid components evident in 40-50% of lesions May be mixed or contain debris Fluid-fluid levels in 5-10% of lesions Distinguishing features Dermoid: Typically but not exclusively contain fat; more heterogeneous Epidermoid: Density and intensity similar to fluid; more homogeneous Radiographic Findings Radiography Scalloped bony lucency with sclerotic margins CT Findings NECT Hypodense fat in about half Density -30 to -80 HU Calcification in 15% Fine or punctate, in cyst wall CECT Mild, thin rim enhancement Irregular margins and enhancement indicate rupture and inflammatory reaction Bone CT Osseous remodeling in majority of lesions (85%) Pressure excavation; smooth, scalloped margins Thinning of bone, may cause focal dehiscence Bony tunnel, cleft, or pit in up to 1/3, leading to dumbbell appearance Bony changes less common in superficial lesions MR Findings T1WI Strongly hyperintense (cf vitreous) if fatty contents Isointense or slightly hyperintense otherwise T2WI Isointense or mildly hypointense (cf vitreous) Heterogeneous debris DWI Epidermoid shows diffusion restriction T1WI C+ 1017 Diagnostic Imaging Head and Neck Thin rim enhancement More extensive inflammation if ruptured Fat-saturation techniques Dermoid shows suppression of lipid signal Ultrasonographic Findings Grayscale ultrasound Adequate for evaluation of simple superficial lesions without posterior extension High internal reflectivity, variable attenuation Debris may impair determination of cystic nature Imaging Recommendations Best imaging tool CT without contrast often adequate for diagnosis Protocol advice Pursue MR with contrast if features not characteristic, particularly with lesion growth DIFFERENTIAL DIAGNOSIS Orbital Dermolipoma Clinical: Soft solid lateral canthus mass Limited to anterior conjunctival location Imaging: Homogeneous episcleral fat No debris or fluid levels Frontal or Ethmoid Sinus Mucocele Clinical: Chronic obstructive sinusitis Polyposis and noninvasive fungal sinusitis Imaging: Expansile obstructed frontal sinus Thinning and remodeling of bone Lacrimal Cyst Clinical: Lacrimal swelling and inflammation Imaging: Fluid density and intensity within gland Orbital Cellulitis Clinical: May mimic ruptured dermoid Imaging: Preseptal or intraorbital infiltration Orbital Rhabdomyosarcoma Clinical: Enlarging orbital mass in child P.IV(2):16 Imaging: Focal or infiltrative orbital mass ± bone destruction PATHOLOGY General Features Etiology Congenital inclusion of dermal elements Sequestration of trapped surface ectoderm Typically at site of embryonic suture closure Acquired epidermoid may occur after remote surgery or trauma (implantation cyst) Gross Pathologic & Surgical Features Whitish or yellowish, well-delineated mass Tethered to orbital periosteum by fibrovascular tissue Oily or cheesy material that is tan, yellow, or white May contain blood or chronic blood products Microscopic Features Fibrous capsule lined by keratinizing stratified squamous epithelium Granulomatous reaction, particularly in deep, complicated lesions May show evidence of rupture, particularly dermoid Disruption of lining, acute or remote Inflammatory changes in 40% Dermoid Sebaceous glands and hair follicles, blood vessels, fat, and collagen Contains keratin, sebaceous secretions, lipid metabolites, and hair Sweat glands in minority (20%) Epidermoid 1018 Diagnostic Imaging Head and Neck No adnexal structures Filled with keratinaceous debris and cholesterol CLINICAL ISSUES Presentation Most common signs/symptoms Firm, rounded mass at lateral eyebrow Nontender, slowly progressive Other signs/symptoms Painless in 90%, but inflamed if ruptured Relatively fixed to underlying bone Clinical profile Childhood presentation More common than adult Subcutaneous nodule near orbital rim Smaller, little globe displacement Adult presentation More commonly arises deep to orbital rim Typically in superolateral extraconal orbit, near lacrimal gland Less easily palpated; larger, globe displacement Less well-defined borders, more likely to erode into adjacent structures May present with rupture (10-15%) Secondary to trauma or spontaneously Acute inflammation mimics cellulitis or inflammatory tumor Can result in entrapment, neuropathy Mass effect if very large Diplopia due to restricted movement Compromise of globe or optic nerve Demographics Age Usually presents in childhood and teenage years Simple, superficial lesions often present in infancy May present or grow at any age Occasionally will appear in adult and grow significantly over several months Gender Equal or slight male predominance Epidemiology Most common noninflammatory space-occupying lesion of orbit Half of childhood orbital lesions 90% of cystic orbital lesions 10% of head and neck dermoid and epidermoid cysts are periorbital Natural History & Prognosis Benign lesion, usually cosmetic considerations Very slow growth, usually dormant for years Present during childhood but small and dormant May become symptomatic during rapid growth phase in young adult Sudden growth or change following rupture Significant inflammation and increased size Treatment Surgical resection is curative Entire cyst must be removed to prevent recurrence Including growth center at periosteal interface Brow or eyelid crease incision most common Approach depends on location in orbit Lesions evident in early childhood should be removed to avoid traumatic rupture Steroids or nonsteroidal drugs to calm inflammation in ruptured lesions Asymptomatic small lesions may be observed Particularly small epidermoid, with less inflammatory response in event of rupture DIAGNOSTIC CHECKLIST Consider 1019 Diagnostic Imaging Head and Neck Features of typical lesions are distinctive, but deep or inflamed lesions may present diagnostic challenge Dermoid cyst is distinct from dermolipoma Image Interpretation Pearls Presence of fat is essentially pathognomonic Posterior extent of complex lesions may not be clinically apparent; therefore, imaging is warranted SELECTED REFERENCES Yen KG et al: Current trends in the surgical management of orbital dermoid cysts among pediatric ophthalmologists J Pediatr Ophthalmol Strabismus 43(6):337-40; quiz 363-4, 2006 Shields JA et al: Orbital cysts of childhood—classification, clinical features, and management Surv Ophthalmol 49(3):281-99, 2004 Chawda SJ et al: Computed tomography of orbital dermoids: a 20-year review Clin Radiol 54(12):821-5, 1999 P.IV(2):17 Image Gallery (Left) Axial NECT shows an ovoid mass in the temporal fossa adjacent to the lateral orbit This dermoid cyst shows fat density, with slightly more dense debris layering dependently Note the broad scalloped remodeling of the adjacent bone (Right) Axial MR images show another dermoid cyst located lateral to orbit in region of temporal fossa, shown on T1WI and T1WI C+ FS The lesion shows signal suppression with fat saturation, indicating lipid contents (Left) Axial NECT in an infant shows a congenital mass at the lateral orbital rim , demonstrating fluid density that is typical of an epidermoid cyst Note the smooth scalloping of the adjacent bony orbit (Right) Axial MR images in 1020 Diagnostic Imaging Head and Neck an adult show an example of a deep epidermoid cyst, demonstrated on T1WI and T2WI The lesion shows near fluid signal without indication of fatty contents The lateral orbital wall shows benign marked thinning (Left) Axial T1WI MR shows a dermoid in a rare intraconal location The mass is sharply demarcated, with mottled internal contents that are moderately hypointense The cyst wall is visible as a thin, distinct hyperintense rim (Right) Gross pathology of an orbital dermoid cyst shows a white-yellow mass with a relatively thick fibrous capsule During surgery, care was taken not to rupture the cyst, thus avoiding possible inflammatory complications (Courtesy Moran Eye Center.) Orbital Neurofibromatosis Type > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Congenital Lesions > Orbital Neurofibromatosis Type Orbital Neurofibromatosis Type H Christian Davidson, MD Key Facts Terminology Neurocutaneous disorder (inherited tumor syndrome) with distinct orbitocranial features Imaging Constellation of features is characteristic of orbital NF1 Plexiform neurofibroma (PNF) Optic nerve glioma (ONG) Sphenoid dysplasia (SD) Buphthalmos Optic nerve sheath ectasia Orbitofacial NF1 typically unilateral Top Differential Diagnoses Plexiform neurofibroma Rhabdomyosarcoma, infantile hemangioma, venolymphatic malformation, lymphoma Optic nerve glioma Glioma without NF1; nerve sheath meningioma Sphenoid dysplasia Congenital cephalocele, traumatic cephalocele Buphthalmos Congenital glaucoma; staphyloma Optic nerve sheath ectasia Normal variant; intracranial hypertension Pathology Autosomal dominant, 50% new mutations Clinical Issues Presenting features: Infiltrative periorbital masses, proptosis, & ptosis Diagnostic Checklist 1021 Diagnostic Imaging Head and Neck Orbital manifestations are progressive over time Rapid change worrisome for malignant degeneration of PNF (Left) Axial graphic depicts dysplasia of the greater sphenoid wing , with arachnoid cyst protruding through the bony defect Extensive plexiform neurofibromas are demonstrated as well buphthalmos An optic pathway glioma is depicted on the right (Right) Axial CECT shows a large defect in the left sphenoid bone , with middle fossa contents protruding into the orbit and causing marked proptosis Extensive orbitotemporal plexiform neurofibromas are evident (Left) Axial T2WI FS MR shows hyperintense multilobulated plexiform masses in the orbit , extending through an enlarged superior orbital fissure and dysplastic sphenoid wing into the cavernous sinus (Right) Axial T1WI C+ FS MR in the same patient shows patchy enhancement of the massive orbital and skull base neurofibromas The right globe is severely proptotic Extracranial plexiform tumors in the orbitotemporal regions are also evident P.IV(2):19 TERMINOLOGY Abbreviations Neurofibromatosis type (NF1), plexiform neurofibroma (PNF), optic nerve glioma (ONG), sphenoid dysplasia (SD) Synonyms von Recklinghausen disease Definitions 1022 Diagnostic Imaging Head and Neck Neurocutaneous disorder (inherited tumor syndrome) with distinct orbitofacial and cranial manifestations IMAGING General Features Best diagnostic clue Constellation of orbital & intracranial features is pathognomonic of NF1 Location Orbitofacial NF1 typically unilateral Morphology Plexiform neurofibroma (PNF) Serpentine, unencapsulated infiltrative masses May involve cranial nerves, intraorbital branches, muscles, optic nerve sheath, and sclera Associated enlargement of skull base foramina Optic nerve glioma (ONG) Tubular or lobular enlargement of optic nerve May involve any segment of nerve May extend posterior to chiasm and brainstem Sphenoid dysplasia (SD) Bony defects, decalcification, or remodeling of greater sphenoid wing & lateral orbital wall Enlargement of middle fossa with herniation of intracranial contents into orbit Associated middle fossa arachnoid cyst common Buphthalmos Increased axial and AP globe diameter Remodeling & enlargement of anterior orbital rim Thickening of uveal/scleral layer Optic nerve sheath ectasia Nontumorous enlargement of dural sheath Increased CSF surrounding optic nerve Radiographic Findings Radiography Defect of greater sphenoid wing Enlarged egg-shaped anterior orbital rim “Harlequin eye” appearance CT Findings NECT PNF Hypodense infiltrative soft tissue masses ONG or nerve sheath ectasia: Enlarged nerve/sheath contour SD: Bony defect with herniation of middle fossa into orbit; proptosis may be marked MR Findings T1WI PNF: Hypointense ill-defined soft tissue masses ONG: Isointense ON mass ± cystic hypointensity T2WI PNF: Hyperintense nodular masses with central low signal “target” sign ONG: Hyperintense fusiform optic nerve mass Buphthalmos: Enlarged globe, thickened sclera Nerve sheath ectasia: Increased perioptic fluid T1WI C+ PNF: Irregular infiltrative serpentine masses; variable enhancement, may be intense ONG: Variably enhancing optic nerve mass Ultrasonographic Findings PNF: Irregular, compressible, highly reflective ONG: Smooth nerve enlargement, minimally reflective Buphthalmos: Increased axial eye diameter Imaging Recommendations Best imaging tool MR ideal for assessment of orbital, extracranial, and intracranial lesions Protocol advice Dedicated brain and orbit examinations indicated for extensive abnormalities 1023 Diagnostic Imaging Head and Neck NECT without sedation in child offers structural evaluation and gross tumor assessment DIFFERENTIAL DIAGNOSIS DDx of Plexiform Neurofibroma Infantile hemangioma Venolymphatic malformation Rhabdomyosarcoma Lymphoma Langerhans cell histiocytosis DDx of Optic Nerve Glioma Optic pathway glioma (isolated) Optic nerve sheath meningioma DDx of Sphenoid Dysplasia Congenital sphenorbital cephalocele Post-traumatic sphenoid cephalocele DDx of Buphthalmos Congenital glaucoma Staphyloma DDx of Optic Nerve Sheath Ectasia Normal variant Idiopathic intracranial hypertension Optic nerve sheath meningioma PATHOLOGY General Features Etiology Disorder of histogenesis, classified as neurocutaneous inherited tumor syndrome Constellation of orbital NF1 findings is characteristic Genetics Autosomal dominant; variable expression P.IV(2):20 50% new mutations; gene locus = 17q11.2 Loss of NF1 tumor suppressor gene function Associated abnormalities CNS tumors typical signal foci on brain imaging Characteristic foci of ↑ T2 signal in basal ganglia (nonneoplastic) Diffuse soft tissue neurofibromas; skeletal deformities Staging, Grading, & Classification Diagnostic criteria for NF1 established by NIH consensus statement on neurofibromatosis Treatment-based classification of orbital disease Orbital soft tissue with seeing eye Soft tissue & bone involvement with seeing eye Soft tissue & bone involvement with blind malpositioned eye Gross Pathologic & Surgical Features Plexiform neurofibroma Worm-like infiltrating tortuous masses May involve eyelid, anterior periorbita, scalp, orbit, temporal fossa, and skull base Optic nerve glioma Diffuse nerve enlargement; tan-white tumor Cystic component with mucinous changes Sphenoid dysplasia Bony defect of posterior lateral orbit Middle cranial fossa expansion with arachnoid cyst Buphthalmos Associated with PNF in anterior orbit Microscopic Features Plexiform neurofibroma Myxoid endoneural accumulation early Schwann cell proliferation, collagen accumulation 1024 Diagnostic Imaging Head and Neck Optic nerve glioma Spindle-shaped astrocytes with hyperplasia of fibroblasts and meningothelial cells Sphenoid dysplasia Bone decalcification; premature suture closure CLINICAL ISSUES Presentation Most common signs/symptoms Infiltrative periorbital masses, proptosis, and ptosis Other signs/symptoms Plexiform neurofibroma Bulky soft tissue masses; “bag of worms” texture PNF anywhere is pathognomonic for NF1 Optic nerve glioma Visual deficit, often relatively mild Proptosis associated with poor vision Sphenoid dysplasia Pulsatile exophthalmos due to orbital encroachment by middle fossa contents Clinical profile Child with progressive proptosis, visual impairment, soft tissue masses, & cosmetic deformities Demographics Age Findings may not be evident at birth Cutaneous signs present at birth or 1st year Tumors begin to appear in childhood Gender No significant gender predilection Epidemiology NF1 is most common inherited tumor syndrome Prevalence 1:2,500-5,000 Orbital involvement in up to 1/3 of NF1 Natural History & Prognosis Orbital features of NF1 are progressive developmental lesions rather than simply congenital defects Progressive worsening of complications over time Glaucoma, optic nerve compromise, blindness Proptosis, corneal exposure Muscle impairment, amblyopia PNF may undergo sarcomatous degeneration to malignant peripheral nerve sheath tumor (2-16%) Decreased life expectancy Malignancy most common cause of death Treatment Plexiform neurofibroma Generally not surgically curable due to infiltrative nature Anterior orbit and eyelid procedures most common Debulking may be required for vision or cosmesis Radiation therapy not effective Optic nerve glioma Observation unless vision threatened Radiation therapy and surgery for bulky tumors Sphenoid dysplasia Transcranial reconstruction with bone grafts for severe posterior defects Management of resultant proptosis; may ultimately require enucleation Debulking of associated PNF DIAGNOSTIC CHECKLIST Consider Although NF1 is inherited disorder, orbital manifestations are progressive and develop over time Image Interpretation Pearls Rapid change in appearance of tumor worrisome for malignant degeneration SELECTED REFERENCES Erb MH et al: Orbitotemporal neurofibromatosis: classification and treatment Orbit 26(4):223-8, 2007 1025 Diagnostic Imaging Head and Neck Ferner RE: Neurofibromatosis and neurofibromatosis 2: a twenty first century perspective Lancet Neurol 6(4):340-51, 2007 Jacquemin C et al: Orbit deformities in craniofacial neurofibromatosis type AJNR Am J Neuroradiol 24(8):167882, 2003 Jacquemin C et al: Reassessment of sphenoid dysplasia associated with neurofibromatosis type AJNR Am J Neuroradiol 23(4):644-8, 2002 Lövblad KO et al: Dural ectasia of the optic nerve sheath in neurofibromatosis type 1: CT and MR features J Comput Assist Tomogr 18(5):728-30, 1994 P.IV(2):21 Image Gallery (Left) Axial CECT in a young girl shows mild sphenoid dysplasia with widening of the superior orbital fissure and a neurofibroma extending into the central skull base The left globe shows buphthalmos (Right) Axial T1WI C+ FS MR in the same patient decades later shows a massive sphenoid defect , demonstrating the progressive nature of this process There is herniation of a large associated arachnoid cyst into the orbit An ICA aneurysm is noted incidentally (Left) Anteroposterior radiograph in a child with NF1 and sphenoid wing dysplasia shows enlargement of the left orbital rim The normal contour of the greater wing of the sphenoid is distorted and displaced , as compared to the normal appearance on the right (Right) 3D CT surface rendering in a different patient shows an enlarged, egg-shaped contour of the right orbital rim A defect is evident in the sphenoid bone at the orbital apex in the region of the superior orbital fissure 1026 Diagnostic Imaging Head and Neck (Left) Axial T2WI MR in a patient with NF1 shows diffuse enlargement of the optic nerves bilaterally consistent with optic pathway gliomas The lesions extend posteriorly to involve the chiasm and optic tracts (Right) Axial T2WI FS MR in another patient with NF1 but no orbital masses shows ectasia of the optic dural sheaths, seen as increased CSF signal surrounding the intraorbital segments of the optic nerves bilaterally Vascular Lesions Orbital Lymphatic Malformation > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Vascular Lesions > Orbital Lymphatic Malformation Orbital Lymphatic Malformation H Christian Davidson, MD Key Facts Terminology Congenital vascular malformation with variable lymphatic & venous vascular elements Imaging Poorly marginated, lobulated, trans-spatial mass Cystic regions with fluid-fluid levels Mixed age hemorrhagic, lymphatic, and proteinaceous fluid contents Hypodense with denser foci of blood on CT Punctate calcification or phleboliths uncommon Variably hyperintense T1WI and T2WI MR Variable enhancement: Rim enhancement of cysts More diffuse & pronounced in venous components Hypoechoic (US) with heterogeneous internal echoes Best imaging tool: Enhanced, fat-suppressed MR Top Differential Diagnoses Orbital varix Orbital cavernous hemangioma Infantile hemangioma Pathology Congenital nonneoplastic vascular malformation Dilated dysplastic lymphatic ± venous channels Clinical Issues Mass effect with proptosis and restricted movement Presents in infants and young adults May rapidly ↑ in size due to acute hemorrhage Conservative therapy preferred due to surgical risk Surgical resection difficult, recurrence common Diagnostic Checklist 1027 Diagnostic Imaging Head and Neck Blood products & fluid-fluid levels highly suggestive (Left) Axial graphic depicts the typical features of orbital lymphatic malformation Notice the multilocular, transspatial nature of this lesion involving the extraconal, conal, and intraconal orbit Also note the fluid-fluid levels as a characteristic feature of this lesion (Right) Axial T2WI MR with fat suppression in a young child with proptosis shows a complex trans-spatial malformation Multicystic spaces are present, which contain blood products with fluid-fluid levels (Left) Axial CECT demonstrates an irregular intraconal mass with lobulated margins and heterogeneous enhancement , representing a mixed venolymphatic malformation (Right) Axial CECT reveals a cystic, well-defined, nonenhancing mass with imperceptible wall in the medial left orbit The mass has a simple, unilocular appearance without fluid levels but is trans-spatial with intraconal, extraconal, and preseptal components P.IV(2):23 TERMINOLOGY Abbreviations Lymphatic malformation (LM) Synonyms Venolymphatic malformation (VLM) when combined with venous component Old terms: Lymphangioma, cystic hygroma Definitions Congenital vascular malformation with variable lymphatic and venous vascular elements IMAGING General Features 1028 Diagnostic Imaging Head and Neck Best diagnostic clue Poorly marginated, lobulated, trans-spatial mass Cystic regions with fluid-fluid levels, blood products, & variable irregular enhancement Location Superficial: Often confined to conjunctiva Relatively common type of VLM Deep: Extending into orbit Extraconal > intraconal, but often in multiple contiguous spaces Size From few mm (superficial) to several cm (deep) Morphology Irregular margins, multilocular cysts with fluid levels Atypical primarily venous lesions with well-defined margins may mimic orbital cavernous hemangioma CT Findings NECT Irregular multicystic hypodense mass Areas of hemorrhage → mixed hyperdense blood products Punctate calcification or phleboliths uncommon CECT Cystic structures with variable wall enhancement More diffuse enhancement of venous components Bone CT Remodeling of bony orbit with large lesions MR Findings T1WI Lobulated, poorly circumscribed mass Fluid-fluid levels with variable signal resulting from hemorrhagic, lymphatic, or proteinaceous fluid in cystic spaces Different ages of blood products; subacute blood characteristically hyperintense T2WI FS Lobulated, very hyperintense fluid signal Fluid-fluid levels show signal corresponding to age of blood products No flow voids (unlike infantile hemangioma) T1WI C+ FS Variable enhancement, typically rim pattern at margins of cysts More pronounced irregular enhancement if prominent venous components present Nonenhancing thrombus may be visible with acute exacerbation Ultrasonographic Findings Grayscale ultrasound Heterogeneous internal echoes Hypoechoic blood and lymph-filled cystic spaces Echoic spikes at endothelial walls Imaging Recommendations Best imaging tool Dedicated enhanced orbital MR with fat suppression DIFFERENTIAL DIAGNOSIS Orbital Varix Clinical: Intermittent pain and proptosis Imaging: Similar to VLM, but dynamic expansion demonstrated with Valsalva Often considered part of VLM spectrum but with distensible venous component Orbital Cavernous Hemangioma Clinical: Common, painless, slowly growing adult orbital mass Imaging: Circumscribed ovoid intraconal mass with dynamic fill-in enhancement Encapsulated venous malformation Infantile Hemangioma Clinical: Highly vascular tumor of infancy; frequently regresses spontaneously Imaging: Poorly marginated, intensely enhancing orbitofacial mass with flow voids Plexiform Neurofibroma Clinical: Associated with neurofibromatosis type 1029 Diagnostic Imaging Head and Neck Imaging: Infiltrative, trans-spatial masses Associated with sphenoid and orbit dysplasia Rhabdomyosarcoma Clinical: Most common primary orbital malignancy in children Imaging: Infiltrative, destructive orbital mass Lymphoproliferative Lesions Clinical: Non-Hodgkin lymphoma, primary to orbit or with systemic disease MALT variety typical Imaging: Pliable mass, involving lacrimal gland, EOM, or diffusely in orbit Often bilateral Idiopathic Inflammatory Pseudotumor Clinical: Inflammatory changes with painful proptosis and ophthalmoplegia Imaging: Asymmetric mass-like inflammation of muscles, lacrimal gland, and other orbital structures PATHOLOGY General Features Etiology P.IV(2):24 Congenital nonneoplastic vascular malformation with low or no venous flow Arise from pluripotent venous anlage Lymphatic tissue not normally found in orbit Associated abnormalities VLM in other regions of head and neck Generalized lymphangiomatosis Noncontiguous intracranial vascular malformations Staging, Grading, & Classification General classification of orbital malformations Type 1: No flow (lymphatic malformation) Type 2: Venous flow (venolymphatic malformation) Nondistensible (minimal venous connections) Distensible (associated with orbital varix) Type 3: Arterial flow Low flow (orbital cavernous hemangioma) High flow (true arteriovenous malformation) Gross Pathologic & Surgical Features Thin-walled multilocular mass Cystic structures containing clear fluid or chocolate-colored blood products Poorly marginated with insinuation along tissue planes; difficult to dissect Microscopic Features Unencapsulated mass of irregularly shaped sinuses; infiltrates into adjacent stroma Dilated dysplastic venous ± lymphatic channels lined with flattened endothelial cells Interstitium of smooth muscle fibers and loose connective tissue Lymphoid follicles and lymphocyte infiltration Cystic spaces with lymphatic fluid or chronic blood products Positive lymphatic immunohistochemical markers confirms lymphatic origin CLINICAL ISSUES Presentation Most common signs/symptoms Progressive proptosis with sudden episodic worsening Other signs/symptoms Mass effect; compressive optic neuropathy Diplopia, restricted extraocular muscles, ptosis Periorbital ecchymosis associated with hemorrhage Clinical profile Lesions may rapidly ↑ in size due to acute hemorrhage Recurrent hemorrhages in 50% Associated with lesion recurrence after surgery Thrombosis may precipitate hemorrhage 1030 Diagnostic Imaging Head and Neck Related to stasis, congestion, and inflammation Lesions may intermittently ↑ and ↓ in size in conjunction with upper respiratory infection Related to presence of lymphatic tissue Demographics Age Younger patients: Infants to young adults 40% present by age 6; 60% present by age 16 Gender Slight female predominance Epidemiology Incidence 3:100,000 8% of all expanding orbital tumors 5% of childhood orbital tumors Natural History & Prognosis Progressive slow growth during childhood, through puberty and into early adulthood Infiltrating nature results in frequent recurrence Refractory visual problems & disfigurement common Poor visual acuity associated with multiple surgical resections Optic nerve compromise with recurrent large lesions Treatment Options, risks, complications Conservative therapy Observation preferred if vision is not threatened due to hazards of surgery Systemic steroids may decrease pain, swelling, and proptosis; especially in younger patients Image-guided sclerotherapy Percutaneous intralesional injection of ethanol or other sclerosing agent Surgery Difficult resection due to complex insinuation with normal orbital structures Recurrence after surgery common (˜ 50%) Multiple surgeries lead to visual impairment Acute mass effect due to hemorrhage may require emergent decompression Indications include optic nerve dysfunction, corneal compromise, & intractable amblyopia DIAGNOSTIC CHECKLIST Consider Deep circumscribed lesions in adults may mimic orbital cavernous hemangioma VLM and orbital varix are related lesions VLM is hemodynamically isolated Varix has systemic drainage, which accounts for pressure-dependent distensibility Image Interpretation Pearls Presence of blood products with fluid-fluid levels is highly suggestive of LM SELECTED REFERENCES Chadha V et al: Orbital venous-lymphatic malformation Eye (Lond) 23(12):2265-6, 2009 Mavrikakis I et al: The role of thrombosis as a mechanism of exacerbation in venous and combined venous lymphatic vascular malformations of the orbit Ophthalmology 116(6):1216-24, 2009 Poon CS et al: Orbital lesions: differentiating vascular and nonvascular etiologic factors AJR Am J Roentgenol 190(4):956-65, 2008 Smoker WR et al: Vascular lesions of the orbit: more than meets the eye Radiographics 28(1):185-204; quiz 325, 2008 Burrows PE et al: Percutaneous treatment of low flow vascular malformations J Vasc Interv Radiol 15(5):431-45, 2004 P.IV(2):25 Image Gallery 1031 Diagnostic Imaging Head and Neck (Left) Axial T2WI FS MR in an older child with acute worsening of longstanding right proptosis shows a large retrobulbar mass with characteristic fluid-fluid levels The differing heights of the levels are indicative of the multilocular nature of the lesion (Right) Axial T1WI C+ FS MR in the same patient again demonstrates the variable signal of contents manifest as fluid-fluid levels , indicating proteinaceous and hemorrhagic products (Left) Axial CECT in a patient with a small mixed venolymphatic malformation demonstrates a primarily nonenhancing hypointense intraconal mass , with a small amount of central venous enhancement (Right) Coronal T1WI C+ FS MR demonstrates a large complex mass in the left orbit, which mostly contains nonenhancing material with differing amounts in intrinsic T1 signal Enhancing structure medially represents small venous component 1032 Diagnostic Imaging Head and Neck (Left) Axial T2WI FS MR shows a massive, complex left orbital malformation with proptosis Striking signal variability with fluid-fluid levels represents sequelae of multiple bouts of hemorrhage Additional preseptal component is also evident (Right) Axial T1WI C+ FS MR shows a small, irregular, extraconal mass in the lateral right orbit with mixed hyperintense signal and heterogeneous enhancement Enhancing component is also seen extending into the adjacent temporal fossa Orbital Venous Varix > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Vascular Lesions > Orbital Venous Varix Orbital Venous Varix H Christian Davidson, MD Key Facts Terminology Low-flow venous malformation with systemic connection and dynamically distensible varix Imaging Imaging recommendations CT without & with provocation (Valsalva) MR if thrombosis or hemorrhage suspected Imaging findings Intensely enhancing, tubular or tortuous orbital mass May show phleboliths Complex signal, blood products, fluid levels on MR Distends dynamically with ↑ venous pressure May be undetectable unless elicited Hypoechoic; slow flow on Doppler US Top Differential Diagnoses Orbital venolymphatic malformation Orbital cavernous hemangioma Orbital infantile hemangioma Pathology Congenital distensible vascular malformation Dilated venous channels, fibrotic walls, phleboliths Clinical Issues Intermittent reversible proptosis Elicited by head position, Valsalva, or coughing Sudden worsening of symptoms suggests thrombosis or hemorrhage Treatment Observation if symptoms mild & stable Embolization or surgery for intractable pain or threatened vision 1033 Diagnostic Imaging Head and Neck (Left) Axial CECT in a patient complaining of intermittent right-sided proptosis shows no evidence of orbital mass The scan was obtained with the patient lying quietly on the scanner table (Right) Axial CECT in the same patient, holding breath in Valsalva maneuver, shows distention of a large extraconal varix posteriorly and laterally in the right orbit The right globe is slightly proptotic The patient reported replication of symptoms with Valsalva (Left) Transocular ultrasound in a patient with intermittent proptosis shows a small, slightly hypoechoic retrobulbar structure The scan was obtained with the patient resting quietly, with no complaint of orbital discomfort (Right) Transocular ultrasound in the same patient during Valsalva maneuver demonstrates striking dynamic enlargement of the retrobulbar varix The patient reported orbital discomfort and a sensation of fullness during the period of breath holding P.IV(2):27 TERMINOLOGY Synonyms Distensible orbital venous malformation Definitions Low-flow venous malformation with systemic venous connection and dynamically distensible varix IMAGING General Features Best diagnostic clue Intensely enhancing orbital mass that distends with increased venous pressure Location Usually retrobulbar & extraconal, often superolateral 1034 Diagnostic Imaging Head and Neck May occur anywhere in orbit Size Changes dynamically with venous pressure May be undetectable unless elicited Morphology Well-defined margins; often tubular or tortuous CT Findings NECT Well-defined, tubular or tortuous soft tissue density lesion in retrobulbar space CECT Intense enhancement; increases in size on Valsalva May be small or undetectable with quiet breathing Bone CT May contain phleboliths MR Findings T1WI Complex signal, blood products, fluid levels T2WI Complex signal, blood products, fluid levels T1WI C+ Intense enhancement Heterogeneous flow voids with faster or turbulent flow Ultrasonographic Findings Grayscale ultrasound Hypoechoic; slow flow on Doppler Angiographic Findings Filling of dilated structure on late venous phase Imaging Recommendations Best imaging tool Dynamic CECT MR preferred if thrombosis or hemorrhage suspected Protocol advice CECT without and with provocation maneuver Valsalva, jugular tourniquet, or hanging head Varix will distend when venous pressure raised US useful for bedside provocative challenge DIFFERENTIAL DIAGNOSIS Orbital Venolymphatic Malformation May present with sudden proptosis due to hemorrhage Irregular multiloculated spaces, blood-fluid levels, variable enhancement Orbital Cavernous Hemangioma Most common isolated orbital mass in adults Well-defined, intense “fill-in” enhancement over time Orbital Infantile Hemangioma Frequently regresses spontaneously Irregular, intense enhancement & flow voids PATHOLOGY General Features Etiology Congenital venous malformation with systemic venous connection Associated abnormalities May be part of venolymphatic malformation Gross Pathologic & Surgical Features Single or multiple dilated valveless vessels Acute hemorrhage or thrombosis may be present Microscopic Features Dilated venous channels with fibrotic walls ± phleboliths CLINICAL ISSUES Presentation 1035 Diagnostic Imaging Head and Neck Most common signs/symptoms Intermittent reversible proptosis Other signs/symptoms Variable pain and ophthalmoplegia Clinical profile Proptosis elicited by change in head position, Valsalva, or coughing Natural History & Prognosis Congenital lesion, typically nonprogressive Sudden worsening due to thrombosis or hemorrhage often prompts attention or intervention Treatment Observation if symptoms mild and stable DIAGNOSTIC CHECKLIST Image Interpretation Pearls Routine imaging may be negative unless provocative test performed (e.g., Valsalva) SELECTED REFERENCES Smoker WR et al: Vascular lesions of the orbit: more than meets the eye Radiographics 28(1):185-204, 2008 Menon SV et al: Thrombosed orbital varix — a correlation between imaging studies and histopathology Orbit 23(1):13-8, 2004 Orbital Cavernous Hemangioma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Vascular Lesions > Orbital Cavernous Hemangioma Orbital Cavernous Hemangioma Megan Mills, MD H Christian Davidson, MD Key Facts Terminology Vascular malformation of orbit characterized by endothelial-lined cavernous spaces Encapsulated morphology distinguishes OCH from vascular malformations elsewhere Distinct lesion from infantile (“capillary”) hemangioma, a neoplastic tumor of infancy Imaging Well-demarcated, ovoid, enhancing intraconal mass Most intraconal, usually lateral Round or ovoid, sharply marginated Pseudocapsule of compressed surrounding tissue CT usually diagnostic in appropriate clinical setting MR with contrast is characteristic Heterogeneous early patchy central enhancement Fills in homogeneously on delayed images Pathology Nonneoplastic; not a “true hemangioma” Fibrous pseudocapsule, distinct from surrounding compressed tissue Dilated vascular channels, larger than capillaries, filled with red blood cells Clinical Issues Slowly progressive painless proptosis Range = 10-60 years; mean = 40 years Female predominance More rapid growth during pregnancy Excellent prognosis; extremely low recurrence rate after surgery Diagnostic Checklist Most common adult orbital mass lesion Often discovered incidentally during brain MR 1036 Diagnostic Imaging Head and Neck (Left) Axial graphic through orbit shows ovoid, well-demarcated, intraconal cavernous hemangioma that displaces the optic nerve and adjacent lateral rectus muscle Note the lack of adjacent structure invasion (Right) Axial NECT shows a well-demarcated, ovoid, slightly hyperdense mass centered in the lateral aspect of the left orbit The lateral rectus muscle is seen draping around the lateral margin of this intraconal mass (Left) Axial T2WI MR reveals a sharply marginated, ovoid, hyperintense intraconal mass A thin rim of signal represents the pseudocapsule, accentuated by chemical shift artifact (Right) Axial dynamic T1WI C+ MR demonstrates progressive enhancement of a vascular mass in the medial left orbit Serial scans were obtained over the course of several minutes, from earliest (top left) to latest (bottom right) following contrast injection P.IV(2):29 TERMINOLOGY Abbreviations Orbital cavernous hemangioma (OCH) Synonyms Encapsulated vascular malformation Definitions Vascular malformation of orbit characterized by endothelial-lined cavernous spaces Encapsulated morphology distinguishes OCH from vascular malformations elsewhere Distinct lesion from infantile (“capillary”) hemangioma, which is neoplastic tumor of infancy IMAGING General Features Best diagnostic clue 1037 Diagnostic Imaging Head and Neck Well-demarcated, ovoid, enhancing intraconal mass Avid heterogeneous enhancement Initially patchy; fills in dynamically Location Most (> 80%) intraconal, usually lateral May occur anywhere in orbit Intramuscular or extraconal lesions also occur; interosseous variant is rare Size Ranging from few millimeters (incidental) to very large (with mass effect) Morphology Round or ovoid, sharply marginated Larger lesions may be lobulated or flattened against orbit wall causing triangular shape Pseudocapsule of compressed surrounding tissue CT Findings NECT Homogeneously isodense May be hyperdense due to microcalcifications Coarse punctate macroscopic calcifications or phleboliths are not typical Benign remodeling of bone in large lesions CECT Avid enhancement MR Findings T1WI Homogeneous and isointense to muscle Pseudocapsule may be visible as hypointense rim T2WI Hyperintense; internal septations may be visible, particularly in larger lesions Chemical shift artifact visible in frequency encoded direction T1WI C+ Pattern of enhancement changes dynamically Heterogeneous early patchy central enhancement Enhancement fills in homogeneously on delayed post-contrast images MRA Does not have high flow characteristics Not visible on routine MRA Ultrasonographic Findings Grayscale ultrasound Well-demarcated hyperechoic retrobulbar mass Highly reflective borders representing pseudocapsule Doppler Low flow arterial and venous channels Angiographic Findings Contrast puddles extending into late venous phase No distinct tumor blush Nuclear Medicine Findings SPECT shows delayed focal uptake on Tc-99m RBC scintigraphy Imaging Recommendations Best imaging tool Enhanced thin section dedicated orbital MR Specific MR features include patchy enhancement, septations, and pseudocapsule Protocol advice CT usually diagnostic in appropriate clinical setting MR appearance is characteristic Use fat-suppressed FSE or STIR for T2WI Use fat-suppressed T1WI post contrast Include dynamic enhanced scan to show characteristic enhancement pattern FSE T1 or spoiled gradient pulse sequence Serial images every 30 seconds for minutes DIFFERENTIAL DIAGNOSIS 1038 Diagnostic Imaging Head and Neck Orbital Lymphoproliferative Lesion Invasive mass that can involve any area of orbit Orbital Metastasis Muscles and globe more common Can involve any area of orbit Optic Nerve Sheath Meningioma Fusiform enhancing mass surrounding optic nerve Tram-track calcification is characteristic Optic Nerve Glioma Tubular mass indistinguishable from optic nerve Associated with NF1 Orbital Varix Uniformly enhancing vascular mass Distensible, enlarges with Valsalva maneuver Orbital Lymphatic Malformation Multilocular mass, trans-spatial, fluid characteristics Hemangiopericytoma Uncommon vascular neoplasm May have similar appearance to OCH Intense enhancement; margins less well defined Schwannoma Uncommon in orbit Ovoid to fusiform, homogeneously enhancing mass Neurofibroma Less well-defined mass; associated with NF1 P.IV(2):30 PATHOLOGY General Features Etiology Slowly growing vascular mass Cavernous malformation with dilated vascular spaces Nonneoplastic; not a “true hemangioma” Associated abnormalities Multiple lesions associated with systemic hemangiomatosis, e.g., blue rubber bleb nevus syndrome Staging, Grading, & Classification General classification of vascular malformations of orbit based on flow Type 1: No flow (e.g., lymphatic) Type 2: Venous flow (e.g., venolymphatic, varix) Type 3: Arterial low flow (e.g., OCH) Type 3: Arterial high flow (e.g., AV malformation) Note: OCH is classified as a type lesion with antegrade arterial low flow, but it shares some similarities with venous malformations found elsewhere in head and neck Gross Pathologic & Surgical Features Round, well-defined, reddish mass; vascular channels Fibrous pseudocapsule, distinct from surrounding compressed tissue Apical vascular tag frequently present Microscopic Features Dilated vascular channels, larger than capillaries, filled with red blood cells Thin-walled sinusoidal spaces lined with flattened endothelial cells, surrounded by few layers of smooth muscle, separated by scant fibrous connective stroma No evidence of cellular proliferation CLINICAL ISSUES Presentation Most common signs/symptoms Slowly progressive painless proptosis Clinical profile Diplopia, visual impairment, increased intraocular pressure with large lesions 1039 Diagnostic Imaging Head and Neck Funduscopic examination Choroidal striae, optic nerve elevation, and posterior indentation with large lesions Demographics Age Range = 10-60 years; mean = 40 years Gender Female predominance, reported as high as 7:3 Ethnicity No known predilection Epidemiology Most common isolated orbital mass in adults Natural History & Prognosis Slow, progressive enlargement over years theories why lesions grow Theory 1: Progressive incorporation of dilated spaces outside lesion capsule Theory 2: Capillary proliferation at margins of cavernous venous spaces More rapid growth during pregnancy Eventually compress orbital structures + remodel bone Excellent prognosis; very low recurrence rate Compare infantile hemangiomas, which spontaneously regress Treatment Surgical resection indicated for visual disturbance, cosmesis, or other significant mass effect Lateral orbitotomy is conventional surgical approach Transconjunctival techniques may be option More extensive surgery for apex lesions; higher complication rate Pseudocapsule promotes easy extraction Observation only for stable lesions, lesions without significant symptoms or poor surgical candidates DIAGNOSTIC CHECKLIST Consider Most common adult orbital mass lesion Often discovered incidentally during brain MR Hemangiopericytoma is rare but has similar imaging appearance Image Interpretation Pearls Patchy dynamic enhancement is feature reminiscent of cavernous hemangiomas seen elsewhere MR appearance showing septations on T2WI is more specific than CT in distinguishing from other orbital masses Reporting Tips Radiologist should be confident diagnosing this common benign adult lesion with characteristic appearance SELECTED REFERENCES Smoker WR et al: Vascular lesions of the orbit: more than meets the eye Radiographics 28(1):185-204; quiz 325, 2008 Warrier S et al: Orbital arteriovenous malformations Arch Ophthalmol 126(12):1669-75, 2008 Rootman J: Vascular malformations of the orbit: hemodynamic concepts Orbit 22(2):103-20, 2003 Chang EL et al: Bilateral multifocal hemangiomas of the orbit in the blue rubber bleb nevus syndrome Ophthalmology 109(3):537-41, 2002 Sayit E et al: The role of Tc-99m RBC scintigraphy in the differential diagnosis of orbital cavernous hemangioma Ann Nucl Med 15(2):149-51, 2001 Bilaniuk LT: Orbital vascular lesions Role of imaging Radiol Clin North Am 37(1):169-83, xi, 1999 Harris GJ: Orbital vascular malformations: a consensus statement on terminology and its clinical implications Orbital Society Am J Ophthalmol 127(4):453-5, 1999 Thorn-Kany M et al: Cavernous hemangiomas of the orbit: MR imaging J Neuroradiol 26(2):79-86, 1999 Mulliken JB et al: Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics Plast Reconstr Surg 69(3):412-22, 1982 P.IV(2):31 Image Gallery 1040 Diagnostic Imaging Head and Neck (Left) Axial CECT shows an ovoid, well-circumscribed, enhancing mass within the intraconal fat of the right orbit, abutting the optic nerve and lateral rectus muscle (Right) Axial T1WI C+ FS MR demonstrates avid enhancement of an intraconal mass The mass is relatively small, with little mass effect, and no aggressive features Such lesions are frequently asymptomatic or have gradual changes that are unnoticed by the patient (Left) Coronal CECT shows an intraconal mass with a patchy early enhancement pattern, highly suggestive of orbital cavernous hemangioma Although the lesion extends to the periphery of the orbit, its center is intraconal (Right) Coronal STIR MR shows a large intraconal cavernous hemangioma The mass shows high signal similar to the CSF that surrounds the displaced optic nerve 1041 Diagnostic Imaging Head and Neck (Left) Axial T2WI FS MR shows a large, hyperintense, slightly lobulated mass at the apex of the right orbit There is enlargement of the superior orbital fissure from this slowly growing mass (Right) Axial T1WI FS MR shows incomplete but intense enhancement of the large orbital cavernous hemangioma at the apex The nonenhancing portions would be expected to fill in on delayed images Infectious and Inflammatory Lesions Ocular Toxocariasis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Infectious and Inflammatory Lesions > Ocular Toxocariasis Ocular Toxocariasis H Christian Davidson, MD Key Facts Terminology Synonyms: Ocular larva migrans, sclerosing endophthalmitis Granulomatous lesion in eye due to immunoallergic reaction following Toxocara larval death Imaging US: Echogenic granuloma with folds extending from nodule CT: Enhancing, posterior nodular mass without calcification MR: Isointense or hypointense to vitreous on T2WI ± intravitreal membranes and retinal detachment Top Differential Diagnoses Retinoblastoma Coats disease Persistent hyperplastic primary vitreous Pathology Pathogen: Toxocara species of roundworm parasites Humans are paratenic (accidental) hosts Ingestion of eggs from ova-laden pet feces Immunoallergic reaction results in granuloma Clinical Issues Leukocoria & ↓ visual acuity in child/young adult Clinical forms Chronic endophthalmitis: Severe inflammation Posterior granuloma: Nodule, folds, and membranes Peripheral granuloma: Anterior nodule, retinal detachment Diagnostic Checklist May closely mimic retinoblastoma Lack of Ca++ on CT helps differentiate 1042 Diagnostic Imaging Head and Neck (Left) Sagittal graphic demonstrates a granulomatous reaction secondary to an expired Toxocara larva A retinal fold is present due to postinflammatory changes and traction, as well a small subretinal fluid collection (Right) Transocular ultrasound shows an echoic nodule at the posterior pole of the globe , corresponding to a Toxocara granuloma An intravitreal membrane is seen extending from the nodule (Courtesy R Harrie, MD.) (Left) Axial CECT shows a mildly enhancing nodule posteriorly in the right eye Adjacent chorioretinal thickening represents inflammatory changes, postinflammatory membranes, retinal folds, &/or subretinal fluid collection (Right) Axial T1WI C+ FS MR shows moderate enhancement of a retinal-based nodule at the posterior pole of the right globe , representing granulomatous reaction at the site of the expired nematode larva P.IV(2):33 TERMINOLOGY Synonyms Ocular larva migrans (OLM) Sclerosing endophthalmitis Definitions Granulomatous retinal nematode infection IMAGING General Features Best diagnostic clue Enhancing granulomatous nodule posteriorly in eye with inflammatory and postinflammatory changes Location Posterior pole of eye; almost always unilateral 1043 Diagnostic Imaging Head and Neck Morphology Retinal-based nodular mass CT Findings NECT Posterior nodular mass without calcification Vitreal hyperdensity due to retinal detachment MR Findings T2WI Isointense or hypointense to vitreous Higher T2 signal than retinoblastoma Intravitreal membranes and retinal detachments Variable signal subretinal fluid T1WI C+ Moderately enhancing retinal nodule Ultrasonographic Findings Grayscale ultrasound Echogenic nodular granuloma Vitreous membranes and retinal folds DIFFERENTIAL DIAGNOSIS Retinoblastoma Calcification present in vast majority More often bilateral Coats Disease More common in males Retinal detachments with large complex exudates Persistent Hyperplastic Primary Vitreous Retrolental tissue and stalk in small eye Retinopathy of Prematurity Small globe, hyperdense, bilateral Acute Endophthalmitis Uveoscleral enhancement PATHOLOGY Parasitology Toxocara species of roundworm parasites T canis (dog host) and T cati (cat host) Humans are paratenic (accidental) hosts Ingestion of eggs from ova-laden pet feces Larvae migrate from intestine to eye Laboratory Tests Serum ELISA for anti-Toxocara antibodies Low titers in ocular compared to visceral disease CLINICAL ISSUES Presentation Most common signs/symptoms Loss of visual acuity, leukocoria Other signs/symptoms Squinting, perceived light flashes Chorioretinitis, optic papillitis, endophthalmitis Demographics Age Mean age = years (may occur in young adults) Gender 60% male, 40% female Epidemiology 1-2% of childhood uveitis Seroprevalence for Toxocara varies 4-30% of children in developed countries 80-90% in endemic regions Majority of pets are infested (33-100%) Natural History & Prognosis Ocular disease months to years after initial infection 1044 Diagnostic Imaging Head and Neck Chronic endophthalmitis Severe granulomatous vitreoretinitis Leukocoria, strabismus, retinal detachment Posterior granuloma Posterior pole granulomatous nodule Retinal folds and vitreous membranes Peripheral granuloma Granuloma anterior to equator, often temporal Retinal folds with traction and detachment Treatment Pharmaceutical Antihelmintic (mebendazole, albendazole) Larval death leads to severe inflammation Corticosteroids Surgical Vitrectomy and subretinal surgery Photocoagulation DIAGNOSTIC CHECKLIST Image Interpretation Pearls May closely mimic retinoblastoma Lack of Ca++ on CT helps differentiate SELECTED REFERENCES Pivetti-Pezzi P: Ocular toxocariasis Int J Med Sci 6(3):129-30, 2009 Kadom N et al: Radiological reasoning: leukocoria in a child AJR Am J Roentgenol 191(3 Suppl):S40-4, 2008 Stewart JM et al: Prevalence, clinical features, and causes of vision loss among patients with ocular toxocariasis Retina 25(8):1005-13, 2005 Orbital Subperiosteal Abscess > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Infectious and Inflammatory Lesions > Orbital Subperiosteal Abscess Orbital Subperiosteal Abscess H Christian Davidson, MD Key Facts Terminology Pus accumulation between bony orbital wall and orbital periosteum (periorbita) Imaging Imaging recommendations Best imaging tool: CECT often adequate Serial CTs helpful for monitoring response MR for assessment of intracranial complications or negative CT with strong clinical suspicion Lentiform collection with rim enhancement along medial orbital wall Loculated fluid density/signal on CT/MR Ethmoid sinus opacification ± dehiscence of lamina papyracea Inflammation, infiltration, and enhancement of orbital fat and muscles Diffusion restriction of abscess contents on MR Top Differential Diagnoses Orbital cellulitis Idiopathic inflammatory pseudotumor Sinonasal mucocele Nasolacrimal duct mucocele Subperiosteal hematoma Clinical Issues Orbital edema and painful proptosis with fever Associated with sinusitis, especially ethmoid 20% of orbital complications of sinusitis IV antibiotics alone may be adequate in children Surgical drainage indicated in adults, when vision is threatened, or failed drug treatment Diagnostic Checklist Orbital disease may be 1st sign of sinusitis 1045 Diagnostic Imaging Head and Neck Risk of blindness; requires immediate attention (Left) Axial graphic depicts spread of infection from the left ethmoid sinuses through the lamina papyracea into the medial orbit Resultant subperiosteal abscess causes mass effect, displacing the adjacent muscle cone and putting the optic nerve at risk (Right) Axial CECT shows asymmetric opacification of the left ethmoid sinuses , with a large subperiosteal abscess extending into the medial extraconal orbit Displacement of the medial rectus is a typical finding (Left) Axial CECT shows a small right medial orbital subperiosteal abscess , with a broad base along the lamina papyracea adjacent to the diseased ipsilateral ethmoid sinus Intraorbital edema is evident, with mass effect and proptosis (Right) Axial T1WI C+ FS MR shows a large subperiosteal abscess extending through the lamina papyracea, with findings of acute sinusitis and right orbital cellulitis Posterior extension of the abscess implies higher risk of vision loss P.IV(2):35 TERMINOLOGY Abbreviations Orbital subperiosteal abscess (SPA) Definitions Pus accumulation between bony orbital wall and orbital periosteum (periorbita) IMAGING General Features Best diagnostic clue 1046 Diagnostic Imaging Head and Neck Lentiform, rim-enhancing collection along medial orbit with adjacent sinusitis (ethmoid) Location Medial extraconal orbit, along lamina papyracea Posterior extension with progression Superolateral location less common Size SPA may appear relatively small relative to degree of orbital edema and proptosis Morphology Flat or lenticular collection bowing laterally Muscle displacement, particularly medial rectus CT Findings NECT Confluent density in medial orbit Opacified ethmoid air cells Inflammatory stranding of orbital fat (“dirty fat”) Gas in collection suggests anaerobes CECT Rim-enhancing hypodense fluid collection Prominently enhancing paranasal sinus mucosa Displaced, enlarged, irregular medial rectus Bone CT Demineralization, dehiscence of lamina papyracea Infection can extend from ethmoid sinus to orbit without frank dehiscence MR Findings T1WI Hypointense fluid signal within SPA Infiltrative inflammatory changes in orbital fat T2WI FS Hyperintense fluid signal within SPA Hyperintense edema in adjacent fat Opacified ethmoid sinuses ↑ signal STIR Similar to T2, less prone to artifact DWI Diffusion restriction within SPA, due to viscosity and dense cellular material within pus Helpful when contrast cannot be given T1WI C+ Rim-enhancing fluid collection in medial orbit Prominently enhancing paranasal sinus mucosa Irregular enhancement of orbital fat Ultrasonographic Findings Grayscale ultrasound Fusiform collection between bone and highly reflective periosteum, adjacent to muscle Imaging Recommendations Best imaging tool CECT often adequate for diagnosis Retroorbital extension best evaluated by enhanced MR with fat suppression Protocol advice Serial CTs helpful for monitoring response Improvement in CT findings may lag behind clinical improvement Balance against risk of radiation dose MR advised for problem solving Evaluate for potential intracranial complications More sensitive than CT and should be pursued when strong clinical suspicion DIFFERENTIAL DIAGNOSIS Orbital Cellulitis Periorbital edema and erythema Infiltration and enhancement without discrete collection; may be preseptal or intraorbital Idiopathic Inflammatory Pseudotumor 1047 Diagnostic Imaging Head and Neck Orbital inflammation, uveitis, vision loss, without fever or leukocytosis Inflammatory changes involving muscles, lacrimal gland, globe, or orbital soft tissues Sinonasal Mucocele Chronic sinus obstruction Expanded sinus cavity with osseous remodeling Density of contents variable; ↑ if inspissated Nasolacrimal Duct Mucocele Nasolacrimal drainage imperforation or obstruction Cystic mass in enlarged lacrimal sac ± enlarged and opacified nasolacrimal duct Subperiosteal Hematoma Post-traumatic, postsurgical, or spontaneous Extraconal collection, hyperdense on NECT if acute Dermoid and Epidermoid Developmental epithelial inclusion Cystic mass in superior-lateral orbit near suture with osseous remodeling; may contain lipid Venolymphatic Malformation Congenital vascular malformation Poorly marginated multicystic mass, irregular enhancement, fluid-fluid levels with hemorrhage PATHOLOGY General Features Etiology Microbiology Children: Commonly single aerobes Adolescents: Mixed, mostly aerobes Adults: Mixed aerobes and anaerobes Mechanisms of spread Hematogenous transmission of bacteria through valveless orbital veins Direct extension through congenital or acquired dehiscence in lamina papyracea P.IV(2):36 Abscess formation Ethmoid sinusitis → orbital periostitis Relatively avascular subperiosteal space limits antibiotic penetration Pus rapidly accumulates in subperiosteal space → orbital phlegmon Associated abnormalities Underlying sinus disease Cystic fibrosis, ciliary dyskinesia Mechanical sinonasal obstruction Staging, Grading, & Classification Chandler grouping of sinus-related orbital disease (does not imply order of disease progression) I: Preseptal cellulitis II: Orbital cellulitis III: Subperiosteal abscess IV: Intraorbital abscess V: Cavernous sinus thrombosis Gross Pathologic & Surgical Features Pocket of yellow-green fluid in expanded space between bone and periosteum Microscopic Features Necrotic debris with inflammatory cell and microorganisms CLINICAL ISSUES Presentation Most common signs/symptoms Orbital edema and painful proptosis with fever Other signs/symptoms Eye swelling, erythema, gaze restriction Visual disturbance in 15-30% Optic neuritis due to intraconal extension May occur with minimal orbital signs 1048 Diagnostic Imaging Head and Neck Retinal ischemia from central artery occlusion Clinical profile Associated with sinusitis, especially ethmoid Preceded by upper respiratory infection in children Demographics Age Most common in children May be more severe in adults Epidemiology Orbital complications in 3% of sinusitis cases SPA represents 20% of orbital complications Natural History & Prognosis Rapidly progressive, potentially blinding disease Blindness if untreated in up to 10% IV antibiotics with drainage when indicated results in excellent prognosis in most cases Progression leads to intraorbital abscess Increased proptosis, increased pressure Worsening vision, ophthalmoplegia Other complications Superior ophthalmic vein thrombosis Cavernous sinus thrombosis; rare but devastating Intracranial extension Spread through diploic vessels Meningitis, empyema, cerebritis, brain abscess Treatment Children: IV antibiotics alone often adequate Adults: Surgical drainage generally indicated Medical therapy (IV antibiotics) Antibiotics without surgery appropriate in about 25% of patients Children under 10-15 years Absence of visual signs or surgical indications Phlegmon with small or no abscess Antibiotic regimen Broad polymicrobial coverage β-lactamase-resistant penicillin combinations, later generation cephalosporins, carbapenems Add anaerobe coverage when indicated Surgical indications Emergent (immediate drainage) Optic nerve or retinal compromise; intracranial involvement Urgent (antibiotics alone inadequate) Age over 10-15 years or immunocompromised Visual compromise or disproportionate pain Superior or inferior extension of abscess Frontal sinus origin Gas in collection (suggests anaerobic infection) Expectant (after failed medical therapy) Visual changes at any time Persistent fever after 36 hours Clinical deterioration after 48 hours No improvement after 72 hours Surgical options Endoscopic drainage Generally preferred for small medial SPA External drainage Larger abscesses; abscesses extending along roof or floor of orbit or originating from frontal sinus DIAGNOSTIC CHECKLIST Consider 1049 Diagnostic Imaging Head and Neck Orbital disease may be 1st sign of sinusitis Particularly in children Image Interpretation Pearls Presence of diffusion restriction on MR increases diagnostic confidence when contrast cannot be administered Reporting Tips Requires immediate attention (may cause blindness) SELECTED REFERENCES Sepahdari AR et al: MRI of orbital cellulitis and orbital abscess: the role of diffusion-weighted imaging AJR Am J Roentgenol 193(3):W244-50, 2009 McIntosh D et al: Failure of contrast enhanced computed tomography scans to identify an orbital abscess The benefit of magnetic resonance imaging J Laryngol Otol 122(6):639-40, 2008 Tanna N et al: Surgical treatment of subperiosteal orbital abscess Arch Otolaryngol Head Neck Surg 134(7):764-7, 2008 Rahbar R et al: Management of orbital subperiosteal abscess in children Arch Otolaryngol Head Neck Surg 127(3):281-6, 2001 P.IV(2):37 Image Gallery (Left) Clinical photograph in a young child with sinusitis and cystic fibrosis shows a swollen eyelid, but relatively minor periorbital edema, indicating postseptal disease The patient responded well to IV antibiotics without surgery (Right) Axial CECT in the same child shows opacification of the ethmoid sinuses , with dehiscence of the right lamina papyracea A small subperiosteal abscess is present , with displacement of the adjacent medial rectus 1050 Diagnostic Imaging Head and Neck (Left) Axial T2WI FS MR in a patient who failed antibiotic therapy for cellulitis shows marked intraorbital edema, with proptosis and tenting of the globe An abscess is present with subperiosteal extraconal and intraconal components (Right) Axial T1WI C+ FS MR in the same patient demonstrates the abscess as low intensity extraconal and intraconal pus with rim enhancement Ethmoid mucosal enhancement is evident This patient suffered total vision loss in the left eye (Left) Sagittal CT reconstruction in a patient with acute sinusitis shows a complex abscess in the superior extraconal orbit , containing fluid and gas Mass effect is evident on the globe and muscle cone The location of this abscess would preclude the use of endoscopic drainage (Right) Coronal T1WI C+ FS MR in a patient status post endoscopic sinus surgery shows phlegmonous enhancement in the medial right extraconal fat , with a small abscess pocket forming centrally Orbital Cellulitis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Infectious and Inflammatory Lesions > Orbital Cellulitis Orbital Cellulitis H Christian Davidson, MD Key Facts Terminology Preseptal cellulitis Infection limited to periorbital soft tissues Intraorbital (postseptal) cellulitis 1051 Diagnostic Imaging Head and Neck Infection posterior to orbital septum Imaging Periorbital or intraorbital soft tissue infiltration with mass effect and enhancement Enhanced CT adequate for uncomplicated cases CT and MR show infiltration of fat and diffuse heterogeneous enhancement Top Differential Diagnoses Orbital subperiosteal abscess Idiopathic orbital inflammatory disease Orbital sarcoidosis Orbital lymphoproliferative lesions Pathology Preseptal cellulitis Trauma, insect bites common Intraorbital cellulitis Sinusitis most common Fungal infections in immunocompromised hosts Clinical Issues Preseptal cellulitis Periorbital edema and erythema Responds well to antibiotics Intraorbital cellulitis Axial (forward) displacement of globe May progress to abscess if inadequately treated Loss of vision and movement are ominous signs Targeted antimicrobials with cultures Surgical drainage if abscess develops (Left) Axial CECT in an older patient with facial impetigo shows typical findings of preseptal cellulitis The preseptal soft tissues show edema and enhancement , with normal appearance of the intraorbital fat Note that the adjacent sinuses are clear (Right) Axial CT in a patient with aggressive preseptal cellulitis shows periorbital swelling and enhancement There is also postseptal infiltration of the intraconal fat The infection was polymicrobial with resistant organisms 1052 Diagnostic Imaging Head and Neck (Left) Coronal CECT in a patient who suffered a bee sting shows periorbital edema & enhancement There is also atypical intraorbital extension of cellulitis, seen as lateral extraconal infiltration as well as lateral rectus myositis with thickening (Right) Axial T1WI C+ FS MR in a diabetic patient with invasive fungal sinusitis shows orbital infection with both preseptal & intraorbital disease and proptosis Note the avascular, nonenhancing appearance of the ethmoid fungal sinusitis P.IV(2):39 TERMINOLOGY Synonyms Preseptal cellulitis Infection limited to periorbital soft tissues Intraorbital (postseptal) cellulitis Infection posterior to orbital septum Definitions Orbital septum Connective tissue plane that acts as diaphragm at anterior boundary of orbit Phlegmon Infectious infiltrate without discrete abscess IMAGING General Features Best diagnostic clue Periorbital or intraorbital soft tissue infiltration with mass effect and enhancement Location Preseptal: Anterior periorbital soft tissues Intraorbital: Extraconal ± intraconal Morphology Infiltrative and ill defined with mass effect Imaging Recommendations Best imaging tool CECT adequate for uncomplicated cases MR with contrast for difficult or aggressive cases Protocol advice Serial CT useful if treatment response indeterminate CT Findings CECT Infiltration of periorbital and intraorbital fat Diffuse heterogeneous enhancement MR Findings T1WI 1053 Diagnostic Imaging Head and Neck Hypointense infiltration of normal fat T2WI FS Heterogeneous hyperintensity T1WI C+ FS Diffuse heterogeneous enhancement DIFFERENTIAL DIAGNOSIS Orbital Subperiosteal Abscess Progressive phase of sinogenic orbital cellulitis Usually indicates surgical intervention Idiopathic Orbital Inflammatory Pseudotumor Subacute onset, absence of fever Mass-like features; multifocal involvement Orbital Sarcoidosis Systemic granulomatous disease Multifocal involvement, especially lacrimal Orbital Lymphoproliferative Lesions Ranges from benign hyperplasia to overt lymphoma Multifocal masses anywhere in orbit PATHOLOGY General Features Etiology Preseptal cellulitis Trauma most common cause Insect bites also common, particularly in children Intraorbital cellulitis Sinusitis most common cause May be secondary to foreign bodies Fungal infections in immunocompromised hosts Associated abnormalities Underlying sinus disease Sinonasal polyposis or obstructive lesion Immunocompromised hosts (diabetes, HIV) Orbit involvement in invasive fungal infection Microbiology Bacterial Preseptal: Staphylococcus, Streptococcus, and H influenzae Intraorbital: Polymicrobial including anaerobes Fungal Rhizopus, Mucor, and Aspergillus species CLINICAL ISSUES Presentation Most common signs/symptoms Preseptal cellulitis Periorbital edema and erythema Intraorbital cellulitis Axial (forward) displacement of globe Other signs/symptoms Fever, pain, chemosis, malaise Natural History & Prognosis Preseptal cellulitis Responds well to antibiotics Postseptal extension rare Intraorbital cellulitis May progress to abscess if inadequately treated Treatment Targeted antimicrobials with cultures Surgical drainage if abscess develops DIAGNOSTIC CHECKLIST Image Interpretation Pearls 1054 Diagnostic Imaging Head and Neck Orbital signs may be primary clinical manifestation of acute invasive fungal sinusitis SELECTED REFERENCES Kapur R et al: MR imaging of orbital inflammatory syndrome, orbital cellulitis, and orbital lymphoid lesions: the role of diffusion-weighted imaging AJNR Am J Neuroradiol 30(1):64-70, 2009 Ryan JT et al: Management of pediatric orbital cellulitis in patients with radiographic findings of subperiosteal abscess Otolaryngol Head Neck Surg 140(6):907-11, 2009 Vairaktaris E et al: Orbital cellulitis, orbital subperiosteal and intraorbital abscess: report of three cases and review of the literature J Craniomaxillofac Surg 37(3):132-6, 2009 Orbital Idiopathic Inflammatory Pseudotumor > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Infectious and Inflammatory Lesions > Orbital Idiopathic Inflammatory Pseudotumor Orbital Idiopathic Inflammatory Pseudotumor H Christian Davidson, MD Key Facts Terminology Nonspecific orbital inflammation, not due to any known etiology or systemic illness Imaging Best imaging tool: Contrast-enhanced MR with fat suppression Poorly marginated mass-like enhancing soft tissue involving any area of orbit Categorized by area(s) of involvement Myositic, lacrimal, anterior, diffuse, apical Moderate diffuse enlargement, irregularity, and enhancement of involved structures Isointense or slightly hyperintense on T2WI or STIR ↓ signal compared to many orbital lesions due to cellular infiltrate and fibrosis ↓ signal in chronic disease suggests sclerosing variant and portends worse prognosis Top Differential Diagnoses Lymphoproliferative lesions Thyroid ophthalmopathy Sarcoidosis Wegener granulomatosis Orbital cellulitis Pathology Polymorphous chronic inflammation & fibrosis Clinical Issues Symptoms: Pain & swelling, restricted eye motion, diplopia, proptosis, & impaired vision 3rd most common orbital disorder Steroid treatment effective in most patients Diagnostic Checklist Pseudotumor is diagnosis of exclusion! (Left) Axial graphic depicts multifocal orbital idiopathic inflammation, including involvement of the extraocular 1055 Diagnostic Imaging Head and Neck muscles , orbital fat , lacrimal gland , sclera , and optic sheath (Right) Coronal T1WI C+ FS MR demonstrates extensive orbital inflammation, with ill-defined enlargement and enhancement of the rectus muscles , extraconal infiltration extending to the lacrimal gland , and intraconal enhancement partially surrounding the optic nerve (Left) Coronal NECT in a middle-aged woman with left eye pain and diplopia shows enlargement and mild hypodensity of the left lateral rectus Isolated lateral rectus myositis is a typical manifestation of orbital pseudotumor, rare in thyroid orbitopathy (Right) Axial T1WI C+ FS MR in a patient with symptoms of uveitis shows orbital inflammatory changes of the anterior right orbit Marked right uveoscleral “shaggy” enhancement is evident , as well as illdefined enhancement of the retrobulbar fat P.IV(2):41 TERMINOLOGY Synonyms Orbital pseudotumor (or simply “pseudotumor”) Definitions Pseudotumor = nonspecific orbital inflammation Tolosa-Hunt Variant form extending into cavernous sinus Sclerosing orbital inflammatory pseudotumor Variant characterized by chronic progressive fibrosis IMAGING General Features Best diagnostic clue Poorly marginated, mass-like enhancing soft tissue involving any area of orbit Location Typically unilateral, bilateral in 25% of cases Categorized by area(s) of involvement Myositic (extraocular muscles [EOM]) Most common pattern Any muscle affected; superior complex and medial rectus most frequent Involves tendinous insertions, tubular configuration, shaggy margins Lacrimal (lacrimal gland) 2nd most common pattern Diffuse enlargement of gland in AP dimension Cannot differentiate from lymphoproliferative lesions or sarcoidosis by imaging alone Anterior (globe, retrobulbar orbit) 3rd most common pattern Uveal-scleral (episcleritis or sclerotenonitis): Thickened sclera with shaggy enhancement Variable involvement of retrobulbar fat and optic nerve 1056 Diagnostic Imaging Head and Neck Perineuritis (uncommon): Irregular nerve sheath thickening and enhancement; differentiate from optic neuritis Diffuse (multifocal intraconal ± extraconal) Overlaps with other patterns Frequently mass-like but tends not to distort globe or erode bone Apical (orbital apex, intracranial extension) Less common; involves orbital apex with posterior extension through fissures Disease variants Tolosa-Hunt: Extends through superior orbital fissure into cavernous sinus Sclerosing pseudotumor: More often bilateral, may extend into sinuses Morphology May be focally mass-like or diffuse Irregular margins, infiltrative features CT Findings NECT Lacrimal, EOM, or other orbital mass Focal or infiltrative; poorly circumscribed soft tissue CECT Moderate diffuse irregularity and enhancement of involved structures MR Findings T1WI Hypointense, particularly sclerosing disease T2WI FS Isointense or slightly hyperintense to muscle ↓ signal intensity compared to many orbital lesions due to cellular infiltrate and fibrosis Hypointense in chronic disease or sclerosing variant due to fibrosis ↓ signal in chronic disease portends worse treatment response STIR Similar to T2WI FS, less prone to artifact T1WI C+ Moderate to marked diffuse irregularity and enhancement of involved structures Tolosa-Hunt: Enhancement and fullness of anterior cavernous sinus and superior orbital fissure MRA Tolosa-Hunt: Associated with cavernous ICA narrowing that reverses with effective therapy Imaging Recommendations Best imaging tool Contrast-enhanced thin section MR with fat suppression DIFFERENTIAL DIAGNOSIS Lymphoproliferative Lesions Non-Hodgkin lymphoma, primary to orbit or with systemic disease; MALT variety typical Pliable mass, involving lacrimal gland, EOM, or diffusely in orbit; often bilateral Thyroid Ophthalmopathy Thyroid dysfunction clinically; less often painful Bilateral, characteristic pattern of EOM involvement; affects muscle bellies, spares tendons Sarcoidosis Orbital involvement in 20% of patients with systemic sarcoidosis Granulomatous enhancement of multiple orbital structures, particularly lacrimal gland Wegener Granulomatosis Necrotizing vasculitis of multiple organs Paranasal sinus and orbital involvement with bone destruction; commonly bilateral Orbital Cellulitis Secondary to adjacent sinusitis (ethmoid) or trauma Phlegmonous periorbital and intraconal infiltration; subperiosteal abscess Carotid-Cavernous Fistula Clinically presents with pulsatile exophthalmos, chemosis Enlarged arterialized venous structures (signal voids on MR); no discrete orbital mass P.IV(2):42 PATHOLOGY 1057 Diagnostic Imaging Head and Neck General Features Etiology Pathogenesis unknown; probably related to underlying immune-mediated processes Not due to infection, granulomatous disease, thyroid orbitopathy, lymphoproliferative disease, or other systemic illness Associated abnormalities Secondary angle-closure glaucoma Autoimmune disorders Gross Pathologic & Surgical Features Typically soft, compressible mass Occasionally hard, fibrotic; particularly chronic Microscopic Features Polymorphous infiltration of chronic inflammatory cells with variable fibrosis Proliferating fibroblastic connective tissue Capillary proliferation with perivasculitis Lipogranulomatous changes Histological variations Sclerosing: Disproportionate connective tissue and early fibrosis with sclerosis Granulomatous: Histiocytes, multinucleated giant cells, and granuloma formation Vasculitic: Small vessel inflammatory infiltrate Eosinophilic: Infiltration of eosinophilia without vasculitis; more common in children CLINICAL ISSUES Presentation Most common signs/symptoms Acute to subacute onset of orbital pain, inflammation, & edema Restricted eye motion, diplopia, & proptosis Other signs/symptoms Impaired vision (perineuritis) Clinical profile Myositic Diplopia; painful limitation of ocular movement Conjunctival injection at muscle insertions Lacrimal Enlarged, tender gland Proptosis and globe displacement More likely to have systemic disorder Anterior Proptosis, ptosis, lid swelling, injection Uveitis, sclerotenonitis, retinal detachments Decreased vision and limited movement Apical Milder signs of inflammation Decreased vision; optic neuropathy Tolosa-Hunt Painful ophthalmoplegia (CN III, IV, V, VI) Diagnosis Biopsy for confirmation indicated in patients unresponsive to or relapse after first-line therapy Demographics Age Any age may be affected; mean in 5th decade Gender Overall F = M; myositic form F > M (2:1) Epidemiology Most common painful orbital mass in adults 10% of all orbital masses 3rd most common orbital disorder After thyroid orbitopathy and lymphoproliferative lesions 5% of all orbital lesions Natural History & Prognosis 1058 Diagnostic Imaging Head and Neck Intermittent disease more likely in younger patients 5-10% resolve spontaneously Pattern of involvement affects prognosis Recurrence more likely with multifocal disease Poor visual outcome more likely in apical and diffuse disease Chronic sclerosing disease not as responsive, but therapy may slow progression Rarely severe cases progress to fixed, painless, sightless eye requiring exenteration Treatment Systemic steroids are first-line therapy 80-85% of patients respond Dramatic and rapid improvement typical Recurrence after initial response in 25-40% Second-line therapies for nonresponsive or refractory cases or when steroids contraindicated Low-dose radiotherapy Long-term control rates 50% or higher Cytotoxic chemotherapy Other immunosuppressive agents DIAGNOSTIC CHECKLIST Consider Pseudotumor is diagnosis of exclusion Atypical onset, poor response, or recurrence should prompt biopsy for confirmation Consider other systemic causes with bilateral, multifocal, lacrimal, or apical involvement Consider infectious cellulitis and carotid fistula in cases with acute onset Image Interpretation Pearls Isolated lateral rectus enlargement most likely orbital pseudotumor, essentially never thyroid orbitopathy SELECTED REFERENCES Mendenhall WM et al: Orbital pseudotumor Am J Clin Oncol 33(3):304-6, 2010 Schuknecht B et al: Tolosa-Hunt syndrome: MR imaging features in 15 patients with 20 episodes of painful ophthalmoplegia Eur J Radiol 69(3):445-53, 2009 Swamy BN et al: Idiopathic orbital inflammatory syndrome: clinical features and treatment outcomes Br J Ophthalmol 91(12):1667-70, 2007 Brannan PA et al: Sclerosing idiopathic orbital inflammation J Pediatr Ophthalmol Strabismus 43(3):183-4, 2006 Yuen SJ et al: Idiopathic orbital inflammation: distribution, clinical features, and treatment outcome Arch Ophthalmol 121(4):491-9, 2003 P.IV(2):43 Image Gallery (Left) Coronal T1WI C+ FS MR in a patient with a painful, fixed right eye shows extensive ill-defined orbital enhancement The extraocular muscles show enlarged, poorly defined contours , with infiltration surrounding the optic sheath (Right) Axial T2WI MR in the same patient shows ill-defined, hypointense infiltration of the right 1059 Diagnostic Imaging Head and Neck orbit The low T2 signal is indicative of chronic fibrosis due to sclerosing pseudotumor Note the presence of a fixed lateral gaze (Left) Coronal T1WI C+ FS MR in a patient with restricted gaze shows poorly enhancing infiltrative tissue involving the intraconal and extraconal left orbit and mild enlargement of the extraocular muscles Patient responded to multimodal drug therapy (Right) Coronal T1WI C+ FS MR in a patient with facial pain and ophthalmoplegia shows bulging and enhancement of the cavernous sinus Also note decreased caliber of cavernous carotid artery in this Tolosa-Hunt variant (Left) Axial T1WI C+ FS MR in an older woman with optic neuropathy shows an intraconal mass encasing the optic nerve sheath A presumptive diagnosis of meningioma was made based on initial clinical presentation (Right) Axial T1WI C+ FS MR in the same patient years later shows near complete spontaneous resolution of the intraconal mass, with some residual enhancement along the optic nerve sheath Subsequently, the patient showed intermittent signs of idiopathic orbital inflammation Orbital Sarcoidosis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Infectious and Inflammatory Lesions > Orbital Sarcoidosis Orbital Sarcoidosis H Christian Davidson, MD Key Facts Terminology Noncaseating granulomatous inflammation of orbit 1060 Diagnostic Imaging Head and Neck Imaging Best imaging tool: Enhanced, fat-suppressed MR Multiple sites of orbital involvement Diffuse lacrimal gland infiltration Optic nerve-sheath thickening, enhancement Asymmetric extraocular muscle infiltration Intraorbital enhancing soft tissue masses Eyelid and periorbital preseptal infiltration Uveitis, especially anterior, but also posterior Top Differential Diagnoses Isolated orbital sarcoid reaction Idiopathic orbital inflammatory disease Lymphoproliferative lesions Wegener granulomatosis Pathology Noncaseating granulomas are hallmark CSF and ↑ serum ACE levels support diagnosis Clinical Issues Associated with systemic sarcoidosis 20-25% of sarcoidosis have ophthalmic disease Isolated orbital disease = “sarcoid reaction” Sign/symptom profiles Eye pain, conjunctivitis, uveitis Palpable, enlarged lacrimal gland; dry eye Optic perineuritis, papillitis, vision loss Limited eye movement, diplopia Occurs at any age; 20-40 years most common Female predominance (2:1) Observation for mild disease Systemic steroids for progressive disease (Left) Axial CECT shows marked bilateral enlargement and enhancement of the lacrimal glands , with associated displacement of the globes Marked thickening of the preseptal periorbital soft tissues is also evident (Right) Axial T1 C+ FS MR shows unilateral right orbital sarcoidosis, with enlargement and enhancement of the lacrimal gland There is abnormal uveoscleral enhancement and nodularity , secondary to uveitis with retrobulbar inflammation 1061 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in a patient with sarcoidosis and acute vision loss shows abnormal enhancement along the left intraorbital optic nerve In addition, the right medial and lateral rectus muscles show increased size and enhancement (Right) Axial T1 C+ FS MR shows numerous ophthalmologic manifestations of sarcoidosis, with thickening and enhancement of the right optic nerve , medial rectus , and oculomotor nerve Suprasellar granulomatous mass is also present P.IV(2):45 TERMINOLOGY Definitions Noncaseating granulomatous inflammation of orbit IMAGING General Features Best diagnostic clue Orbital mass effect or enlargement involving any or multiple typical structure(s) Location Diffuse lacrimal gland infiltration Optic nerve-sheath thickening, enhancement Asymmetric extraocular muscle (EOM) infiltration Intraorbital enhancing soft tissue masses Eyelid and periorbital preseptal infiltration Uveitis; especially anterior, but also posterior CT Findings NECT Isodense enlarged orbital structures or masses CECT Diffuse enhancement of involved structures MR Findings T1WI Hypointense enlarged orbital structures or masses T2WI Variably hyperintense orbital structures or masses T1WI C+ Diffuse enlargement and homogeneously increased enhancement of lacrimal gland ± muscles Optic nerve ± sheath enhancement Enhancing intraorbital soft tissue masses Intracranial involvement with enhancement & nodularity Nuclear Medicine Findings Ga-67 scintigraphy Increased uptake; supportive but nonspecific 1062 Diagnostic Imaging Head and Neck Imaging Recommendations Best imaging tool Enhanced, fat-suppressed MR DIFFERENTIAL DIAGNOSIS Isolated Orbital Sarcoid Reaction No diagnosis of systemic sarcoidosis Considered a distinct entity from sarcoidosis & primarily involves lacrimal gland Idiopathic Orbital Inflammatory Disease Nonspecific inflammation, protean manifestations Lymphoproliferative Lesions Pliable, homogeneous orbital masses Wegener Granulomatosis Necrotizing vasculitis, sinonasal and orbital disease Thyroid Ophthalmopathy Predictable EOM enlargement pattern PATHOLOGY General Features Etiology Unknown Laboratory CSF and ↑ serum ACE levels support diagnosis Microscopic Features Noncaseating granulomas are hallmark Central multinucleated giant cells and surrounding rim of lymphocytes CLINICAL ISSUES Presentation Most common signs/symptoms Uveitis, lacrimal mass, and dacryoadenitis Swelling, ptosis, and globe displacement Other signs/symptoms Anterior uveitis: Eye pain, conjunctivitis Posterior uveitis: Vitreous and retinal changes Lacrimal gland: Palpable, enlarged gland; dry eye Optic nerve: Perineuritis, papillitis, vision loss EOM: Limited movement, diplopia Clinical profile Associated with systemic sarcoidosis Orbital disease common initial presentation 20-25% of have ophthalmic disease Isolated orbital disease = “sarcoid reaction” Demographics Age 20-40 years most common Gender Female predominance (2:1) Ethnicity Highest in African & northern European descent Epidemiology Prevalence ranges from 2-60 per 100,000 Natural History & Prognosis Stable or diminishing mild disease in 75% Progressive disease requiring treatment in 25% Treatment Observation for mild disease Systemic steroids for progressive disease Other immunosuppressants for recalcitrant disease DIAGNOSTIC CHECKLIST Image Interpretation Pearls Imaging appearance very similar to that of pseudotumor and lymphoma 1063 Diagnostic Imaging Head and Neck SELECTED REFERENCES Mavrikakis I et al: Diverse clinical presentations of orbital sarcoid Am J Ophthalmol 144(5):769-775, 2007 Prabhakaran VC et al: Orbital and adnexal sarcoidosis Arch Ophthalmol 125(12):1657-62, 2007 Simon EM et al: Systemic sarcoidosis with bilateral orbital involvement: MR findings AJNR Am J Neuroradiol 19(2):336-7, 1998 Thyroid Ophthalmopathy > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Infectious and Inflammatory Lesions > Thyroid Ophthalmopathy Thyroid Ophthalmopathy H Christian Davidson, MD Key Facts Terminology Synonyms: Graves ophthalmopathy; thyroid orbitopathy Autoimmune orbital inflammatory condition associated with thyroid dysfunction Imaging CT For uncomplicated disease & surgical planning Nonuniform, symmetric or asymmetric EOM involvement Enlargement of muscle bellies, sparing tendinous insertions “I'M SLO” mnemonic for sites of predilection Increased volume of orbital fat MR Assess disease activity ↑ T2WI MR signal acutely due to edema ↓ T2WI MR signal chronically due to fibrosis US: Effective for bedside diagnosis Top Differential Diagnoses Idiopathic orbital inflammatory pseudotumor Sarcoidosis Lymphoproliferative lesions Pathology Autoantibodies target thyrotropin receptors found in both thyroid gland and orbit Cellular infiltrate with hyaluron deposition acutely Fibrosis and muscle degeneration in chronic phase Clinical Issues Typical patient is middle-aged woman with periorbital edema, proptosis, & restricted gaze Corticosteroids first-line of therapy in acute disease Surgery for decompression in severe cases (Left) Coronal graphic shows bilateral symmetric enlargement of extraocular muscles Irregularity within the muscles represents accumulation of lymphocytes and mucopolysaccharide deposition (Right) Coronal NECT shows 1064 Diagnostic Imaging Head and Neck enlargement of the bilateral inferior, medial, & superior rectus muscles in a patient with thyroid ophthalmopathy Mucopolysaccharide deposition manifests as areas of low density within the muscles, particularly inferior recti (Left) Coronal STIR MR demonstrates bilateral diffuse enlargement of multiple rectus muscles Hyperintensity on STIR imaging correlates with acuity of disease, as well as potential responsiveness to glucocorticoid therapy (Right) Axial T1WI C+ FS MR in the same patient shows diffuse enlargement of essentially all of the rectus muscles, except the superior obliques Extraocular muscles affected by acute thyroid orbitopathy typically enhance less intensely than normal muscles P.IV(2):47 TERMINOLOGY Synonyms Graves ophthalmopathy, thyroid orbitopathy Definitions Autoimmune orbital inflammatory condition associated with thyroid dysfunction IMAGING General Features Best diagnostic clue Exophthalmos and bilateral extraocular muscle (EOM) enlargement Location Nonuniform, symmetric EOM involvement Bilateral in 90%; symmetrical in 70% Even if symptoms are unilateral I'M SLO mnemonic for sites of predilection Inferior ≥ medial ≥ superior > lateral ≥ oblique Superior recti frequent in some reports Isolated muscle involvement in 5% Size EOM enlargement varies with disease severity Normative EOM thickness (mm) at mid-belly based on CT data Inferior: 4.8, medial: 4.2, superior: 4.6, lateral: 3.3 Thickness > mm considered abnormal Morphology Enlargement of muscle bellies; typically spares tendons, but may be involved in acute phase CT Findings NECT Isodense enlargement of EOM Heterogeneous areas of internal lower density, indicating glycosaminoglycan deposition Exophthalmos Line drawn between lateral orbital rims demonstrates degree of exophthalmos Other features 1065 Diagnostic Imaging Head and Neck Increased orbital fat, especially in patients < 40 years Straightened (“stretched”) optic nerve Lacrimal gland enlargement CECT Superior ophthalmic vein enlargement MR Findings T1WI Isointense enlargement of EOM bellies Decreased optic nerve diameter posteriorly T2WI FS Increased EOM signal in acute disease Increased water due to edema and inflammation Decreased EOM signal in chronic disease Involutional changes with fibrosis STIR Similar to T2WI FS, less prone to artifact Signal intensity ratio correlates with clinical activity T1WI C+ Decreased EOM enhancement compared to normal Impaired microcirculation, decreased perfusion Secondary to intraorbital mass effect Ultrasonographic Findings Grayscale ultrasound Enlarged EOM bellies, spares tendons Internal reflectivity lower in acute disease Edema and inflammation Internal reflectivity higher in chronic disease End-stage changes and fibrosis Nuclear Medicine Findings DTPA and somatostatin analogues Retrobulbar uptake indicates active inflammation Increased lacrimal uptake Uptake decreases with immunosuppressive therapy Imaging Recommendations Best imaging tool CT to assess uncomplicated disease and plan surgical decompression MR to assess active disease in deciding therapy or, in atypical cases, to exclude other pathology US effective for bedside diagnosis Protocol advice Imaging not routinely necessary in patients with mild disease if diagnosis is established clinically Coronal and axial planes critical for assessing muscle size and relationship to orbital structures Volumetric analysis (EOM) Can be used to monitor treatment response 10-15% reduction suggests positive response CT with region growing algorithm most useful MR manual technique limited at orbital apex DIFFERENTIAL DIAGNOSIS Idiopathic Orbital Inflammatory Pseudotumor Inflammatory changes with painful proptosis and ophthalmoplegia Unilateral, often involving lateral rectus; may involve other orbital structures (especially lacrimal gland) Sarcoidosis 20% of patients with systemic sarcoid Granulomatous enhancement of multiple orbital and intracranial structures Lymphoproliferative Lesions Non-Hodgkin lymphoma, primary to orbit or with systemic disease; MALT variety typical Pliable, homogeneous mass may originate from or infiltrate EOM; may involve other orbital structures Metastasis History of known primary Breast and lung primary most common 1066 Diagnostic Imaging Head and Neck Melanoma & carcinoid high predilection for orbit and EOM Isolated or multiple masses within EOM, orbital fat, globe, or bony orbit Orbital Cellulitis Orbital edema, proptosis, fever Fat infiltration, subperiosteal abscess, rectus enlargement (myositis) Associated sinus infection (ethmoid) P.IV(2):48 PATHOLOGY General Features Etiology Autoimmune inflammation of EOM, periorbital fat, and connective tissues Autoantibodies target thyrotropin receptors found in both thyroid gland and orbit Orbital fibroblasts react to lymphocyte (T-cell) infiltration and cytokine-mediated inflammation Associated abnormalities Associated with other autoimmune diseases Increased incidence of myasthenia gravis Potential confounding cause of EOM dysfunction Staging, Grading, & Classification Functional classification (clinical severity and risk) Mild: Eyelid lag and retraction with proptosis in setting of active hyperthyroidism Moderate: Soft tissue inflammation, intermittent myopathy, stabilizes without major sequelae Severe: Rapid and fulminant, greater mass effect, severe sequelae including optic nerve compromise VISA scheme (focuses on key points) Vision: Specifically, optic neuropathy Inflammation: Indicated by pain and swelling Strabismus: Limitations in motility Appearance: Proptosis, lid function, and exposure Microscopic Features Mixed cellular infiltration with lymphocytes, plasma cells, macrophages, and eosinophils Glycosaminoglycan (hyaluron) deposition Enlargement of fibroblasts, increased collagen Fibrosis and muscle degeneration in chronic phase CLINICAL ISSUES Presentation Most common signs/symptoms Periorbital edema, proptosis, pain, restricted gaze Other signs/symptoms Eyelid retraction and eyelid lag on downgaze Dry eyes, chemosis, and corneal ulceration Diplopia, restricted EOM movement, strabismus Dysthyroid optic neuropathy in severe cases Vision loss due to optic nerve compression at orbital apex Clinical profile Orbitopathy common in systemic Graves disease 30-50% have clinically evident orbit symptoms 70-90% of Graves disease with orbital involvement if subclinical disease included 5% have severe orbital disease Associated with systemic thyroid disease 90% hyperthyroid; 10% hypothyroid or euthyroid Orbit symptoms precede systemic disease in 20%; coincident in 40%; afterwards in 40% Demographics Age Young and middle-aged adults (30-50 years) Orbitopathy more severe in older patients Graves disease uncommon in children Most likely cause of hyperthyroidism Gender 1067 Diagnostic Imaging Head and Neck F > > M (3-6x more common) More severe and later onset in men Epidemiology Incidence 1:2,000 (reports vary from 1:200 to 1:5,000) Most common cause of exophthalmos in adults Natural History & Prognosis Orbitopathy often self-limited, favorable outcome Within year of onset 60-70% show significant or some improvement 20-25% remain unchanged; 10-15% worsen Significant chronic disease in 10-15%; severe in 5% Treatment of systemic thyroid disease may worsen orbitopathy, particularly radioiodine treatment Smoking exacerbates orbital disease Treatment Supportive therapy for early and mild cases Corneal care; observation for vision impairment More aggressive therapy for patients with severe inflammation or optic nerve compromise Medical therapy Corticosteroids first-line therapy in acute disease Radiation therapy Rapid palliation with 60-70% response Surgical therapy Decompression for uncontrolled mass effect Chronic disease, failed medical therapy Decompression via ethmoidectomy, resection of lateral orbital walls/orbital floors Restoration of eyelid position and function Correction of strabismus DIAGNOSTIC CHECKLIST Consider Most common cause of exophthalmos in adult Typical patient is middle-aged woman Image Interpretation Pearls Fluid-sensitive MR sequence can help differentiate acute edema from late change fibrosis Acute phase more responsive to steroid therapy MR shows optic nerve compression better than CT Reporting Tips Consider other diagnoses if isolated to lateral rectus SELECTED REFERENCES Bahn RS: Graves' ophthalmopathy N Engl J Med 362(8):726-38, 2010 Bartalena L et al: Clinical practice Graves' ophthalmopathy N Engl J Med 360(10):994-1001, 2009 Kirsch E et al: Imaging in Graves' orbitopathy Orbit 28(4):219-25, 2009 Bijlsma WR et al: Radiologic measurement of extraocular muscle volumes in patients with Graves' orbitopathy: a review and guideline Orbit 25(2):83-91, 2006 Cakirer S et al: Evaluation of extraocular muscles in the edematous phase of Graves ophthalmopathy J Comput Assist Tomogr 28(1):80-6, 2004 P.IV(2):49 Image Gallery 1068 Diagnostic Imaging Head and Neck (Left) Axial CECT shows marked thickening of the medial rectus bellies , with relative sparing of the tendinous insertions The disconjugate orientation of the lenses is evidence of impaired muscle movement (Right) Axial NECT in a patient with clinical exophthalmos shows prominent intraorbital fat , with relatively little muscle thickening, especially on other slices The degree of proptosis is made evident by a line drawn between the lateral orbital rims (dotted line) (Left) Coronal NECT in a patient with advanced thyroid eye disease shows marked enlargement of the rectus muscle bellies , worse on the right This results in crowding at the orbital apex, with the potential for compression of the optic nerves (Right) Coronal NECT shows diffuse marked enlargement of rectus muscles In this patient, decompression of the medial and inferior orbital walls has been performed to decrease the degree of mass effect on the optic nerves 1069 Diagnostic Imaging Head and Neck (Left) Coronal STIR MR in a patient with acute hyperthyroidism shows asymmetric hyperintensity and enlargement of the inferior, medial, and lateral rectus muscles on the right and superior rectus on the left Hyperintense STIR signal in the setting of thyroid eye disease indicates more acute inflammation (Right) Anterior I-123 scan in the same patient shows diffuse, intense, homogeneous uptake of iodine in the thyroid gland The uptake was markedly elevated at 72%; normal is considered 5-30% Optic Neuritis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Infectious and Inflammatory Lesions > Optic Neuritis Optic Neuritis H Christian Davidson, MD Key Facts Imaging Focal or segmental T2 hyperintensity of optic nerve Central or diffuse nerve enhancement ± peripheral sheath enhancement Nerve normal in size or minimally enlarged Top Differential Diagnoses Ischemic optic neuropathy Infectious optic neuritis Idiopathic perineuritis (pseudotumor) Granulomatous optic neuropathy (sarcoid) Optic nerve sheath meningioma Optic nerve glioma Pathology Presumed autoimmune process triggered by infection, systemic disease, or other stressor Clinical Issues Symptoms: Acute loss of visual acuity, impaired color vision, & eye pain Distinct clinical profiles Acute optic neuritis (ON) Neuromyelitis optica (Devic syndrome) Acute demyelinating encephalomyelitis (ADEM) Pediatric ON Spontaneous recovery of vision is characteristic Corticosteroids accelerate acute recovery Early interferon therapy mitigates risk of MS Diagnostic Checklist Identification of demyelinating lesions in CNS is most important neuroimaging task in setting of ON High incidence of MS in patients with ON Findings on MR strongly predictive of MS 1070 Diagnostic Imaging Head and Neck Recommend brain & spinal cord imaging (Left) Axial T1WI C+ FS MR in an adult woman with left eye pain and decreased color vision shows intense segmental enhancement of the left intraorbital optic nerve A component of peripheral nerve sheath enhancement is seen extending posteriorly (Right) Axial FLAIR MR of the brain in the same patient shows multiple periatrial, capsular, and callosal white matter lesions CSF analysis yielded oligoclonal bands, and the patient was diagnosed with multiple sclerosis (Left) Coronal T1WI C+ FS MR in a young adult woman with right eye vision loss, pain, & afferent pupillary defect shows moderate enhancement of the intraorbital optic nerve There are no other inflammatory changes in the orbit (Right) Coronal STIR MR in the same patient shows increased signal in the right optic nerve Note that the hyperintense signal of the right nerve is similar to CSF in the optic nerve sheath, whereas the normal left nerve is distinct from the surrounding CSF P.IV(2):51 TERMINOLOGY Abbreviations Optic neuritis (ON) IMAGING General Features Best diagnostic clue Enhancement & mild enlargement of optic nerve Location Unilateral in 70% 1071 Diagnostic Imaging Head and Neck Segment(s) of nerve involvement Anterior intraorbital: 45% Mid intraorbital: 60% Intracanalicular: 35% Prechiasmatic & chiasm: 10% Size Optic nerve diffusely mildly enlarged CT Findings CECT Often normal, may show mild optic nerve enlargement or enhancement MR Findings T1WI Optic nerve diffusely & mildly enlarged T2WI Focal or segmental hyperintensity of optic nerve ± coexistent ↑ signal brain & spinal cord lesions STIR Hyperintensity of optic nerves similar to T2WI FLAIR ± coexistent ↑ signal white matter lesions in brain Presence is strong predictor for multiple sclerosis (MS) DWI Increased diffusivity in demyelinating plaques May temporarily show decreased diffusion acutely (uncommon) Decreased fractional anisotropy T1WI C+ Nerve enhancement centrally or diffusely > 90% Consistent with active demyelination Variant peripheral sheath enhancement pattern May simulate nerve sheath meningioma Less likely to be associated with MS Functional MR Reduced visual cortex activation Ultrasonographic Findings Grayscale ultrasound Mild enlargement of optic nerve Imaging Recommendations Best imaging tool Enhanced MR is imaging tool of choice Despite advantages of MR, optic nerves, brain, & spinal cord may appear normal in MS Protocol advice Thin section axial & coronal sequences Fat-suppressed T2 FSE or STIR & T1 C+ Include whole brain sagittal & axial FLAIR DIFFERENTIAL DIAGNOSIS Ischemic Optic Neuropathy Restricted diffusion on MR, otherwise often normal More likely in male, advanced age Visual acuity does not improve, unlike acute ON Infectious Optic Neuritis Nerve enlargement more pronounced May be indistinguishable from ON on imaging Idiopathic Perineuritis (Pseudotumor) Enlarged, enhancing optic nerve-sheath complex Inflammation may involve any orbital structure Painful proptosis; mobility restriction & diplopia Granulomatous Optic Neuropathy (Sarcoid) Enlarged, enhancing optic nerve similar to ON EOM & lacrimal gland involvement Intracranial disease with meningeal enhancement 1072 Diagnostic Imaging Head and Neck Optic Nerve Sheath Meningioma Thickened, enhancing optic nerve sheath “Tram-track” calcifications are diagnostic Progressive vision loss, lack of pain Optic Nerve Glioma Tubular enlarged, variably enhancing optic nerve NF1 often present but not majority Rare malignant optic glioma in adults Radiation-Induced Optic Neuropathy Bilateral optic nerve enhancement 1-3 years following radiation Pituitary, parasellar, & skull base tumors Toxic Optic Neuropathy Methanol, carbon monoxide, many pharmaceuticals PATHOLOGY General Features Etiology Presumed autoimmune process T cells & autoreactive antibodies cross blood brain barrier resulting in demyelinating inflammation Infection, systemic disease, or other stressor may be inciting event that triggers autoimmune response Genetics Several HLA alleles associated with ↑ risk of developing ON & MS Staging, Grading, & Classification Subtypes of optic neuritis Retrobulbar neuritis Papillitis Perineuritis Neuroretinitis McDonald criteria Based on clinical, imaging, & CSF findings Gross Pathologic & Surgical Features Nerve edema acutely, atrophy chronically P.IV(2):52 Microscopic Features Acute: Macrophages, lymphocytes, & plasma cells Myelin loss, axonal damage, cholesterol droplets Oligodendrocyte precursors & remyelination attempts suggest potential for intervention Chronic: Atrophy, gliosis, astrocytic scar Axonal loss, little remyelination, may cavitate CLINICAL ISSUES Presentation Most common signs/symptoms Acute loss of visual acuity & eye pain Other signs/symptoms Dyschromatopsia (impaired color vision) Vision worse in bright light Phosgenes (light flashes) Eye tenderness or pain with movement Uhthoff symptom: Exertion-induced vision loss Relative afferent pupillary defect Swollen optic disc (papillitis) in 33% Delayed visual evoked potential (VEP) latency Clinical profile Typical acute ON Most common in younger women 1073 Diagnostic Imaging Head and Neck High risk of developing clinical MS Neuromyelitis optica (NMO) = Devic syndrome Acute ON, typically bilateral, with myelitis ON more likely to relapse Seropositive autoantibody marker, NMO-IgG Antibody to aquaporin-4 water channels Acute demyelinating encephalomyelitis (ADEM) Clinically isolated syndrome without overt MS May involve optic nerves primarily or exclusively Pediatric ON Rare, ≤ 5% of cases More frequently bilateral (40-60%) Less likely to develop MS (15-35%) May follow viral illness or vaccination More frequently attributable to ADEM Demographics Age Presentation 15-50 years, average early 30s Gender M:F = 1:2 Males present slightly older Ethnicity Highest prevalence among those with white Northern European ancestry 8:1 ratio Northern Europeans to Africans & Asians Moderately high with Mediterranean ancestry Low with African or Asian ancestry Epidemiology Incidence: 4-6 per 100,000 in USA & Europe 50-60% of ON patients ultimately develop MS 75% of women, 35% of men MR findings highly correlated with subsequent MS 75% of patients with brain lesions 25% of patients with normal MR 70-90% of MS patients develop ON at some point 15-25% of MS patients initially present with ON Natural History & Prognosis Acute symptom onset over hours to days Spontaneous recovery of vision is characteristic Begins in weeks, continues for months to years 70% ≥ 20/25; 80% ≥ 20/30; 90% ≥ 20/40 ON frequently initial demyelinating event in MS Recurrent ON is common Overall 35%, more frequent in MS & NMO Recurs in same eye in 20-30% Vision outcome worse if eventually develop MS Abnormalities of contrast sensitivity are predictive of persistent visual deficits Treatment Corticosteroid treatment (IV with PO taper) Accelerates short-term recovery Does not alter long-term vision outcome Interferon β-1a (IM) Early treatment with initial event (including ON) Delays conversion to & decreases risk of development of clinically definite MS Optic Neuritis Treatment Trial National Eye Institute sponsored investigation DIAGNOSTIC CHECKLIST Consider Significant recovery of vision is typical Consider other diagnosis if vision remains poor 1074 Diagnostic Imaging Head and Neck Ischemic neuropathy more likely in older patients Image Interpretation Pearls Identification of demyelinating lesions in CNS is most important neuroimaging task in setting of ON High incidence of MS in patients with ON Findings on MR strongly predictive of MS Early immunotherapy decreases risk of MS Reporting Tips Recommend brain & spinal cord imaging SELECTED REFERENCES Swanton JK et al: Early MRI in optic neuritis: the risk for clinically definite multiple sclerosis Mult Scler 16(2):15665, 2010 Osborne BJ et al: Optic neuritis and risk of MS: differential diagnosis and management Cleve Clin J Med 76(3):18190, 2009 Swanton JK et al: Early MRI in optic neuritis: the risk for disability Neurology 72(6):542-50, 2009 Optic Neuritis Study Group: Multiple sclerosis risk after optic neuritis: final optic neuritis treatment trial follow-up Arch Neurol 65(6):727-32, 2008 Volpe NJ: The optic neuritis treatment trial: a definitive answer and profound impact with unexpected results Arch Ophthalmol 126(7):996-9, 2008 Wilejto M et al: The clinical features, MRI findings, and outcome of optic neuritis in children Neurology 67(2):25862, 2006 Wingerchuk DM et al: Revised diagnostic criteria for neuromyelitis optica Neurology 66(10):1485-9, 2006 Hickman SJ et al: Optic nerve diffusion measurement from diffusion-weighted imaging in optic neuritis AJNR Am J Neuroradiol 26(4):951-6, 2005 P.IV(2):53 Image Gallery (Left) Axial T1WI C+ FS MR in a patient with severe acute vision loss shows marked enhancement of the right optic nerve, involving the cisternal segment and extending from the optic canal to the chiasm (Right) Sagittal T2WI MR in the same patient also with acute myelopathy shows a long segment of cervical cord enlargement with T2 hyperintensity MR of the brain was normal, and CSF did not show oligoclonal b&s Serum antibody testing confirmed neuromyelitis optica (Devic syndrome) 1075 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in a young male with blurry vision and eye pain shows patchy enhancement and mild enlargement of the optic nerves , worse on the left CSF and clinical course were consistent with ADEM (Right) Axial diffusivity image (above) in a patient with optic neuritis shows increased mean diffusivity in the right optic nerve compared to the left Tractography (below) shows corresponding loss of fiber bundle distinction of the right compared to left optic nerves (Left) Axial T1WI C+ FS MR in a 7-year-old girl with acute vision loss following a viral illness shows bilateral irregular enhancement of the optic nerves , worse on the left CSF analysis was unremarkable, and the patient had an uneventful recovery (Right) Funduscopic image in a child with postviral optic neuritis shows typical appearance of papillitis The fundus returned to normal after corticosteroid therapy Tumor-like Lesions Orbital Langerhans Cell Histiocytosis > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Tumor-like Lesions > Orbital Langerhans Cell Histiocytosis Orbital Langerhans Cell Histiocytosis H Christian Davidson, MD Key Facts Terminology Spectrum of diseases characterized by proliferation of pathological Langerhans type histiocytes Eosinophilic granuloma: Unifocal-unisystem Bony lesions; older; milder, responsive disease 1076 Diagnostic Imaging Head and Neck Hand-Schüller-Christian: Multifocal-unisystem Bone, skin, viscera; younger; good prognosis Letterer-Siwe: Multifocal-multisystem Disseminated, fulminant; infants; poor prognosis Imaging CT often adequate in children Orbital disease usually unifocal May occur in conjunction with multifocal/multisystem disease Typical location: Anterolateral orbitofrontal skull & greater sphenoid wing “Punched out” or geographic lytic bone lesion Associated homogeneous soft tissue mass with diffuse heterogeneous enhancement Infratemporal and middle cranial fossa extension Top Differential Diagnoses Rhabdomyosarcoma Metastasis Leukemia Fibrous dysplasia Pathology Unknown etiology (reactive vs neoplastic) Birbeck granules on electron microscopy Clinical Issues Periorbital pain and swelling, proptosis Excellent prognosis for localized lesions High mortality with disseminated disease (Left) Axial CECT in a child with focal swelling over the left medial eye shows a homogeneously enhancing soft tissue mass that extends into the subcutaneous soft tissues and the medial extraconal orbit The imaging features on the soft tissue window CT are nonspecific (Right) Axial bone CT in the same patient shows a focal lytic lesion in the frontal bone overlying the superior orbital rim , with irregular geographic margins Note the absence of periosteal reaction or calcification 1077 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR in a child with multifocal bone disease shows a large isodense soft tissue mass centered in the lateral orbital wall and extending to the infratemporal fossa The mass displaces the lateral rectus muscle but remains extraconal in location (Right) Axial CECT in a young child with disseminated Langerhans cell histiocytosis shows bulky soft tissue masses involving the lateral orbits bilaterally , as well as the central skull base and temporal bone P.IV(2):55 TERMINOLOGY Abbreviations Langerhans cell histiocytosis (LCH) Synonyms Eosinophilic granuloma (EG): Unifocal-unisystem Hand-Schüller-Christian (HSC): Multifocal-unisystem Letterer-Siwe (LS): Multifocal-multisystem Histiocytosis X (outdated term) Definitions Spectrum of diseases characterized by proliferation of pathological Langerhans type histiocytes IMAGING General Features Best diagnostic clue Geographic, lytic lesion of skull/orbit with associated enhancing soft tissue mass Location Orbital disease usually unifocal May occur in conjunction with multifocal/multisystem disease Anterior or lateral orbitofrontal skull most common Lateral orbital wall and greater sphenoid wing also common, particularly multifocal disease Size Ranges from small discrete lesion to diffuse bony involvement Morphology Destructive bony changes with soft tissue mass CT Findings NECT Isodense, homogeneous soft tissue mass CECT Diffuse, moderate enhancement Bone CT Destructive osteolytic changes Classically “punched out” with beveled margins but may be irregular and geographic MR Findings T1WI 1078 Diagnostic Imaging Head and Neck Isointense to hypointense soft tissue mass T2WI Isointense to hyperintense soft tissue mass T1WI C+ FS Diffusely enhancing soft tissue mass Frequently mildly heterogeneous Intracranial extension with dural involvement Imaging Recommendations Best imaging tool CT adequate in young patients with typical presentation to avoid sedation MR to assess intracranial involvement DIFFERENTIAL DIAGNOSIS Rhabdomyosarcoma Aggressive, destructive primary orbital malignancy Metastasis Particularly neuroblastoma in young children Leukemia AML, CLL, or granulocytic sarcoma Fibrous Dysplasia Expansile, mixed lytic/sclerotic, “ground-glass” PATHOLOGY General Features Etiology Unknown etiology (reactive vs neoplastic) Staging, Grading, & Classification Unifocal-unisystem (EG) Bony lesions; older patient population Milder, responsive disease Multifocal-unisystem (HSC) Bone, skin, viscera; younger patient population Good prognosis Multifocal-multisystem (LS) Disseminated, fulminant; infants Poor prognosis Microscopic Features Characteristic Birbeck granules (electron microscopy) CLINICAL ISSUES Presentation Most common signs/symptoms Periorbital pain and swelling, proptosis Other signs/symptoms Systemic signs in disseminated disease Demographics Age EG: 5-20 years; HSC: 1-4 years; LS: < years Gender M:F = 2:1 Natural History & Prognosis Excellent prognosis for localized lesions High mortality with disseminated disease Treatment Local curettage and intralesional corticosteroid injection extremely effective in unifocal lesions DIAGNOSTIC CHECKLIST Reporting Tips Recommend skeletal radiographic survey &/or radionuclide bone scan to exclude multifocal disease SELECTED REFERENCES Lee Y et al: Orbital langerhans cell histiocytosis Int Ophthalmol Clin 49(1):123-31, 2009 Erly WK et al: Orbital histiocytosis X AJNR Am J Neuroradiol 16(6):1258-61, 1995 1079 Diagnostic Imaging Head and Neck Benign Tumors Orbital Infantile Hemangioma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Benign Tumors > Orbital Infantile Hemangioma Orbital Infantile Hemangioma Deborah R Shatzkes, MD Key Facts Terminology Synonyms: Orbital capillary hemangioma, infantile periocular hemangioma Definition: Benign vascular tumor of infancy Distinct lesion from vascular malformation Imaging Location: preseptal &/or postseptal orbit Exclusively retrobulbar in 10% CT findings Lobular, slightly hyperdense, homogeneous Intense enhancement MR findings T1 intermediate; prominent internal flow voids Moderate T2 hyperintensity (high cellularity) US: High vessel density, absent arteriovenous shunting, high peak arterial Doppler shift When superficial, US confirms clinical diagnosis MR best for mapping larger, deeper lesions Top Differential Diagnoses Rhabdomyosarcoma Metastatic neuroblastoma Orbital cellulitis Orbital Langerhans cell histiocytosis Orbital venous malformation Plexiform neurofibroma Orbital non-Hodgkin lymphoma Clinical Issues Distinguish from vascular malformations Present at birth; grow in monophasic fashion Diagnostic Checklist Remember differential diagnosis for rapidly growing mass in infant includes malignancy (Left) Clinical photograph shows a superficial vascular mass centered at the medial orbit and nose, with typical violaceous discoloration seen in infantile hemangioma (Right) Axial CT without contrast demonstrates the most common location for orbital infantile hemangioma, within the superior medial preseptal soft tissues There is no 1080 Diagnostic Imaging Head and Neck evidence of postseptal extension (Left) Axial enhanced T1WI depicts a well-delineated intensely enhancing infantile hemangioma with internal septations &/or flow voids in a typical periorbital location Once again, postseptal extension is absent (Right) Doppler ultrasound in the same patient shows striking internal flow, typical for phase I (proliferating) lesions P.IV(2):57 TERMINOLOGY Synonyms Orbital capillary hemangioma, infantile periocular hemangioma Definitions Benign vascular tumor of infancy Distinct lesion from vascular malformation IMAGING General Features Best diagnostic clue Lobular or infiltrative, hypervascular, intensely enhancing mass in infant Location May involve multiple contiguous areas Predilection for eyelids, supranasal periorbita Sites of orbital involvement Most commonly superficial superomedial extraconal location May extend postseptal, into superior orbital fissure or into intraconal space Exclusively retrobulbar in 10% Size Variable, small superficial lesions rarely imaged Morphology Ranges from lobular to infiltrative Infiltrative pattern typical in postseptal component CT Findings NECT Intermediate attenuation, relatively homogeneous Increasing fat content & septations with involution CECT Intense enhancement, usually homogeneous Decreases with involution Prominent vessels during proliferative phase MR Findings T1WI Slightly hyperintense to muscle Internal flow voids 1081 Diagnostic Imaging Head and Neck T2WI Moderate hyperintensity reflects high cellularity Flow voids frequently visible T1WI C+ Diffuse, intense enhancement Enhancement may appear heterogeneous, particularly in involuting phase MRA Generally not necessary for diagnosis but helpful in assessing associated arterial abnormalities in PHACES syndrome MPGR Intralesional high-flow vessels Ultrasonographic Findings Lobular soft tissue mass with high vessel density, high peak arterial Doppler shift, absent AV shunting Angiographic Findings Enlarged feeding branches from external carotid, ophthalmic arteries Dense parenchymal stain, no AV shunting Imaging Recommendations Best imaging tool When small and superficial, ultrasound may be sufficient to confirm clinical diagnosis MR best for mapping larger, deeper, and more complex lesions Protocol advice Enhanced MR in multiple planes with fat suppression best for tumor mapping DIFFERENTIAL DIAGNOSIS Rhabdomyosarcoma Rapidly progressive invasive orbital mass Bone destruction present when large Metastatic Neuroblastoma Rapidly progressive osseous metastatic mass Predilection for greater sphenoid wing Cellulitis, Orbit Inflammatory changes ± abscess formation Orbital Langerhans Cell Histiocytosis Well-defined, lytic bone lesion with enhancing soft tissue mass in children Orbital Venous Malformation Hypointense T1, hyperintense T2, diffuse contrast enhancement, ± phleboliths Plexiform Neurofibroma Infiltrative + sphenoid dysplasia + other stigmata of neurofibromatosis type Orbital Non-Hodgkin Lymphoma Multicompartmental infiltrating mass Orbital Leukemia Homogeneous masses that mold to or more orbital walls ± periosteal reaction, usually without frank bone destruction PATHOLOGY General Features Etiology Proliferation of vascular endothelium Grows by endothelial cellular hyperplasia Distinguish from vascular malformation: Localized defect of vascular morphogenesis with quiescent endothelium Genetics Most cases sporadic Some associated with pleiotropic genetic syndromes Small percent autosomal dominant Gene map locus 5q35.3, 5q31-q33 Associated abnormalities Large lesions may involve ectodermal structures of face, neck, and airway P.IV(2):58 1082 Diagnostic Imaging Head and Neck Parotid involvement common PHACES syndrome: Posterior fossa anomalies; hemangioma, arterial, cardiac, eye & sternal anomalies Staging, Grading, & Classification Classification by location Deep: Within deep tissues of lid and anterior orbit, or entirely retrobulbar Superficial: Confined to dermis Combined: Both dermal and deep components Gross Pathologic & Surgical Features Bluish hue of overlying skin May have external or internal carotid arterial supply Capable of profuse bleeding Microscopic Features Unencapsulated lobulated cellular neoplasm Thin-walled, capillary-sized vascular spaces in lobules with thin fibrous septae Venous malformation has larger vascular spaces Increased numbers of endothelial and mast cells during proliferative phase Decreased cellularity during involutional phase Immunohistochemical marker Glut-1 positive in all phases CLINICAL ISSUES Presentation Most common signs/symptoms Unilateral eyelid, brow, or nasal vascular lesion Ophthalmologic symptoms common: Amblyopia, astigmatism, proptosis, and decreased visual acuity Risk of amblyopia highest when diffuse, > cm in size, and associated with PHACES syndrome Clinical profile Rubbery, soft mass Bluish discoloration of skin or conjunctiva (80%) Blanche with pressure, unlike port-wine stain Enlarge with Valsalva or crying in 50% Occasional periorbital fat excess following involution Demographics Age Typically not present at birth; most appear within 1st few weeks Vascular malformations present at birth, deep lesions may not become apparent until later in life Gender Female predominance 2-3:1 Even higher F:M in genetic syndromes Epidemiology Affects about 1% of neonates Natural History & Prognosis distinct phases Proliferative phase: Appears a few weeks after birth and grows rapidly for 1st year or two Involuting phase: Regression over 3-5 years Involuted phase: Usually complete regression by late childhood Distinguish from vascular malformations: Present at birth & grow in monophasic fashion with age Variants: NICH (noninvoluting congenital hemangioma) and RICH (rapidly involuting congenital hemangioma) Present at or before birth, Glut-1 negative Treatment Expectant observation unless complications Indications for treatment Ophthalmologic: Visual disturbance, nerve compromise, proptosis Dermatologic: Ulceration, infection, cosmesis Corticosteroid treatment very effective Intralesional, systemic, or topical administration Intratumoral laser therapy in larger lesions Interferon, Vincristine, surgical resection or laser ablation for recalcitrant lesions 1083 Diagnostic Imaging Head and Neck Intravascular embolization contraindicated for intraorbital lesions DIAGNOSTIC CHECKLIST Consider Remember differential diagnosis for rapidly growing mass in infant includes malignancy Image Interpretation Pearls US can provide easy bedside evaluation In appropriate age group, cellular enhancing mass with prominent flow voids nearly diagnostic Reporting Tips Map lesion with particular reference to critical structures in orbit & intracranial compartment SELECTED REFERENCES Nguyen J et al: Pharmacologic therapy for periocular infantile hemangiomas: a review of the literature Semin Ophthalmol 24(3):178-84, 2009 Frank RC et al: Visual development in infants: visual complications of periocular haemangiomas J Plast Reconstr Aesthet Surg Epub ahead of print, 2008 Tronina SA et al: Combined surgical method of orbital and periorbital hemangioma treatment in infants Orbit 27(4):249-57, 2008 Chung EM et al: From the archives of the AFIP: Pediatric orbit tumors and tumorlike lesions: nonosseous lesions of the extraocular orbit Radiographics 27(6):1777-99, 2007 Judd CD et al: Intracranial infantile hemangiomas associated with PHACE syndrome AJNR Am J Neuroradiol 28(1):25-9, 2007 Levi M et al: Surgical treatment of capillary hemangiomas causing amblyopia J AAPOS 11(3):230-4, 2007 Kavanagh EC et al: Imaging of the natural history of an orbital capillary hemangioma Orbit 25(1):69-72, 2006 Neudorfer M et al: Intraorbital and periorbital tumors in children—value of ultrasound and color Doppler imaging in the differential diagnosis Am J Ophthalmol 137(6):1065-72, 2004 Castillo BV Jr et al: Pediatric tumors of the eye and orbit Pediatr Clin North Am 50(1):149-72, 2003 10 Mulliken JB et al: Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics Plast Reconstr Surg 69(3):412-22, 1982 P.IV(2):59 Image Gallery (Left) Axial T1WI MR in a large supraorbital infantile hemangioma reveals prominent internal flow voids and enlargement of the superior ophthalmic vein , which serves as the primary drainage pathway (Right) Axial T2WI MR of a large infantile hemangioma in a similar location demonstrates a small lobular retrobulbar component Careful inspection of the postseptal soft tissues is critical when reviewing imaging studies in periorbital hemangioma 1084 Diagnostic Imaging Head and Neck (Left) Preand postseptal components are present in this child with right orbital hemangioma demonstrating typical intense enhancement While some lesions are lobular and well demarcated, others show a more infiltrative pattern (Right) The medial rectus muscle is displaced medially by this hemangioma with postseptal component , confirming extraconal location Though the lesion appears “soft” and is deformed by the globe, subtle globe deviation and distortion are present (Left) Axial CECT demonstrates an intensely enhancing, lobular, primarily retrobulbar hemangioma The mass is multicompartmental, with intraconal and extraconal components, as well as a small superficial preseptal component laterally The globe is markedly proptotic (Right) Axial T2WI MR in a child with right orbitofacial hemangioma & PHACES syndrome shows right cerebellar hypoplasia and absence of the expected flow void for the right cavernous internal carotid artery Optic Pathway Glioma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Benign Tumors > Optic Pathway Glioma Optic Pathway Glioma Deborah R Shatzkes, MD Key Facts Terminology Optic pathway glioma (OPG) Primary neuroglial tumor of optic pathway broad subtypes 1085 Diagnostic Imaging Head and Neck Childhood syndromic (NF1), childhood sporadic, adult Imaging Fusiform optic nerve (ON) mass with variable posterior pathway involvement MR is preferred imaging modality Isointense to mildly hypointense on T1WI Variably hyperintense on T2WI Enhancement varies from minimal to intense Associated neuroimaging findings in NF1 ↑ T2 foci in brain, other CNS tumors, sphenoid dysplasia, buphthalmos Top Differential Diagnoses Optic neuritis Optic nerve sheath meningioma Idiopathic orbital inflammatory pseudotumor Sarcoidosis Pathology Childhood OPG: Low-grade glioma Adult OPG: Anaplastic astrocytoma or glioblastoma multiforme Clinical Issues Decreased vision, proptosis; often asymptomatic Childhood OPG: Onset 0.5-15 years 30-40% of patients with OPG have NF1 11-30% of patients with NF1 have OPG Natural history highly variable, but generally indolent in childhood OPG (Left) Axial graphic depicts a left optic pathway glioma extending along the length of the intraorbital nerve, through the enlarged optic canal, and into the prechiasmatic segment The fusiform pattern of enlargement is typical (Right) Axial T2WI FS MR shows fusiform enlargement and buckling of the left intraorbital optic nerve resulting in mild proptosis The tumor is hyperintense on T2WI, as is typical for optic pathway glioma Note normal CSF in the sheath posterior to the tumor 1086 Diagnostic Imaging Head and Neck (Left) Oblique sagittal T1WI C+ FS MR reveals globular enlargement and intense homogeneous enhancement of the intraorbital optic nerve extending posteriorly into the widened optic canal (Right) Axial T1WI C+ FS MR shows mild patchy enhancement and marked fusiform enlargement of the intraorbital , intracanalicular , and prechiasmatic segments of the right optic nerve Lesions in children with neurofibromatosis type may demonstrate only minimal contrast enhancement P.IV(2):61 TERMINOLOGY Abbreviations Optic pathway glioma (OPG) Synonyms Optic nerve glioma; anterior visual pathway glioma Definitions Primary neuroglial tumor of optic pathway broad subtypes Childhood benign tumors: Associated with neurofibromatosis type (NF1), syndromic 30-40% Childhood benign tumors: No NF1 association (sporadic) Adult tumors: Typically malignant IMAGING General Features Best diagnostic clue Fusiform optic nerve (ON) mass with variable posterior pathway involvement Location Childhood lesions with NF1 (syndromic) Anterior pathways, unilateral or bilateral Bilaterality highly associated with NF1 50% extend to chiasm, hypothalamus, and retrochiasmal optic pathways Optic radiation involvement is rare Childhood lesions without NF1 (sporadic) Affects chiasm and retrochiasmal segment predominantly Adult lesions Unilateral ON with posterior extension Size Syndromic (with NF1): 0.5-2 cm long Sporadic (without NF1): 1-8 cm long Adult lesions: Varies depending on posterior extent Morphology General Diffuse sausage-shaped or fusiform enlargement of nerve and chiasm 1087 Diagnostic Imaging Head and Neck Characteristic kinking or buckling of nerve Syndromic: Smooth, tubular, tortuous ON enlargement Sporadic: Smooth, nodular, with cystic components Adult: Diffuse ON enlargement, invasive features Associated neuroimaging findings if NF1 present: ↑ T2 foci in brain, other CNS tumors, sphenoid dysplasia, buphthalmos, plexiform neurofibromas CT Findings NECT Isodense fusiform nerve enlargement; focal hypodensity if cystic spaces Bone CT Ca++ rare (unlike optic nerve sheath meningioma) Enlargement of bony optic canal if intracranial extension MR Findings T1WI Isointense to mildly hypointense compared to brain Focal hypointensity if cystic spaces present T2WI Signal is variable, but moderate hyperintensity typical Peripheral hyperintensity due to perineural arachnoid gliomatosis (PAG) in NF1 Focally hyperintense cystic spaces of mucinous degeneration in sporadic cases DWI Elevated mean ADC values have been demonstrated T1WI C+ Enhancement varies from minimal to intense Syndromic: Often little enhancement Sporadic: Moderate to intense enhancement Adult: Moderate heterogeneous enhancement Dynamic contrast-enhanced (DCE) MR: Increased mean permeability values demonstrated in clinically aggressive tumors Imaging Recommendations Best imaging tool MR is preferred imaging modality Defines involvement of proximal optic pathways Allows assessment of related intracranial findings in patients with NF1 CT adequate for intraorbital assessment and may be performed without sedation DIFFERENTIAL DIAGNOSIS Optic Neuritis Acute onset pain and visual loss Enhancing ON with minimal nerve enlargement Optic Nerve Sheath Meningioma Slow onset proptosis and ↓ vision in adult Perineural mass, may be calcified Idiopathic Orbital Inflammatory Pseudotumor Painful proptosis, mass-like inflammation Can involve any structure in orbit Variable imaging appearance, including perineural enhancement Sarcoidosis Systemic illness, orbital inflammation Predilection for lacrimal gland ON, orbital, and intracranial enhancement PATHOLOGY General Features Genetics NF1 (if present): Autosomal dominant with variable penetrance and variable clinical expressivity Associated abnormalities Focal brain T2 hyperintensities in NF1 patients Seen in 80-90% of NF1 patients who have OPG Seen in 50-70% of all NF1 patients Other CNS tumors in NF1 patients (most commonly low-grade astrocytomas) 1088 Diagnostic Imaging Head and Neck Staging, Grading, & Classification Low-grade gliomas Vast majority of childhood lesions P.IV(2):62 60% WHO grade I pilocytic astrocytoma 40% WHO grade II fibrillary astrocytoma In NF1, tumor may represent perineural arachnoid gliomatosis (PAG) rather than true astrocytoma High-grade gliomas Most adult lesions, occasionally childhood lesions Anaplastic astrocytoma, glioblastoma multiforme Dodge classification defines locoregional extent of tumor Stage A: Limited to optic nerve Stage B: Involves chiasm ± optic nerve Stage C: Extends toward hypothalamus or posterior visual pathways Gross Pathologic & Surgical Features Diffuse ON enlargement; tan-white tumor Cystic component related to mucinous degeneration or infarction Microscopic Features Syndromic: Circumferential perineural infiltration with arachnoid gliomatosis Central nerve sparing (relatively preserved vision) Sporadic: Expansile intraneural infiltration CLINICAL ISSUES Presentation Most common signs/symptoms Decreased vision Other signs/symptoms Proptosis, optic atrophy Nystagmus Intracranial mass effect Clinical profile Childhood optic pathway glioma Syndromic: Frequently asymptomatic; lesions detected on routine imaging Sporadic: Larger, more aggressive Adult optic pathway glioma Aggressive course with rapid deterioration of vision Demographics Age Childhood: Onset 0.5-15 years (mean: years) Adult: Onset 20-80 years (mean: 50 years) Gender Slight female predominance in childhood OPG Epidemiology Childhood benign lesions 3% of orbital tumors; 5% of intracranial tumors 30-40% of patients with OPG have NF1 11-30% of patients with NF1 have OPG Adult malignant lesions: Very rare Natural History & Prognosis Natural history highly variable Ranges from spontaneous regression to progressive visual and neurologic impairment culminating in death Syndromic: Generally indolent course, progression typically stops by age 6, though can continue to age 12 Progression most frequent 1st years following diagnosis Spontaneous regression can occur Sporadic: Less indolent, more intervention required Shorter time to relapse Adult: Poor prognosis, rapidly fatal 1089 Diagnostic Imaging Head and Neck Specific location impacts prognosis Rate of complications and death Optic chiasm/retrochiasmal gliomas > optic nerve gliomas Treatment Childhood lesions with NF1 Biopsy generally not required; presumptive diagnosis Observation unless vision threatened Chemotherapy is first-line for tumor progression Radiation therapy (XRT) and surgery reserved for patients with bulky tumor or older children with progressive disease XRT complications: Secondary tumors, radiation necrosis, moyamoya disease, impaired growth, cognitive deficits Childhood lesions without NF1 Biopsy typically indicated Surgical debulking for large tumors when there is severe visual loss and proptosis Adjunctive radiation ± chemotherapy Adult OPG Multimodality therapy DIAGNOSTIC CHECKLIST Consider Clinical & imaging features vary with specific subtype: Syndromic, sporadic, adult Bilateral intraorbital lesions indicate syndromic disease (NF1) SELECTED REFERENCES Nicolin G et al: Natural history and outcome of optic pathway gliomas in children Pediatr Blood Cancer 53(7):12317, 2009 Wilhelm H: Primary optic nerve tumours Curr Opin Neurol 22(1):11-8, 2009 Jost SC et al: Diffusion-weighted and dynamic contrast-enhanced imaging as markers of clinical behavior in children with optic pathway glioma Pediatr Radiol 38(12):1293-9, 2008 Walrath JD et al: Magnetic resonance imaging evidence of optic nerve glioma progression into and beyond the optic chiasm Ophthal Plast Reconstr Surg 24(6):473-5, 2008 Binning MJ et al: Optic pathway gliomas: a review Neurosurg Focus 23(5):E2, 2007 Sener RN: Diffusion MRI in neurofibromatosis type 1: ADC evaluations of the optic pathways, and a comparison with normal individuals Comput Med Imaging Graph 26(2):59-64, 2002 Chateil JF et al: MRI and clinical differences between optic pathway tumours in children with and without neurofibromatosis Br J Radiol 74(877):24-31, 2001 Millar WS et al: MR of malignant optic glioma of adulthood AJNR Am J Neuroradiol 16(8):1673-6, 1995 P.IV(2):63 Image Gallery (Left) Axial T2WI MR shows the typical MR appearance of a large left optic pathway glioma, with globular enlargement 1090 Diagnostic Imaging Head and Neck and prominent T2 hyperintensity of the intraorbital optic nerve The optic sheath anterior to the tumor is markedly dilated (Right) Axial T2WI MR demonstrates enlargement and moderate T2 hyperintensity of the intraorbital segment of the right optic nerve A peripheral zone of higher signal intensity is compatible with associated arachnoid hyperplasia (Left) Axial T2WI MR shows an optic pathway glioma involving the intracranial prechiasmatic segment , chiasm , and left optic tract Optic pathway gliomas typically demonstrate higher T2 signal than this isointense lesion (Right) Coronal T1 C+ MR demonstrates vivid enhancement of the chiasm and bilateral proximal optic tracts in a patient with bilateral optic pathway gliomas The degree of contrast enhancement is extremely variable in optic pathway gliomas (Left) Axial T1WI C+ MR shows diffuse enlargement of the prechiasmatic and chiasmatic segments of the bilateral optic nerves , with only minimal patchy enhancement The presence of bilateral optic gliomas generally heralds the diagnosis of neurofibromatosis type (Right) Axial T2WI MR of the brain demonstrates a rounded, high signal lesion in the basal ganglia typical for neurofibromatosis type These lesions not demonstrate significant enhancement Optic Nerve Sheath Meningioma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Benign Tumors > Optic Nerve Sheath Meningioma Optic Nerve Sheath Meningioma Deborah R Shatzkes, MD Key Facts 1091 Diagnostic Imaging Head and Neck Terminology Optic nerve sheath meningioma (ONSM) Also known as perioptic meningioma Benign, slow-growing tumor of optic nerve sheath Distinct entity from intracranial (spheno-orbital) meningioma that extends through orbital apex Imaging Enhancing mass surrounding intraorbital optic nerve with Ca++ in 1/3 to 1/2 of cases “Tram-tracking” appearance: Tumor enhancement or Ca++ on either side of optic nerve Uniform, moderately intense enhancement Variably hyperintense to hypointense on T2WI Top Differential Diagnoses Optic nerve glioma Orbital pseudotumor Orbital sarcoidosis Metastasis Orbit lymphoproliferative lesions Pathology Benign tumor arising from arachnoid “cap” cells within optic nerve sheath May be associated with NF2 Clinical Issues Classic triad: Visual loss, optic atrophy, optociliary venous shunting Fractionated radiosurgery currently first-line therapy Diagnostic Checklist MR is preferred imaging modality for tumor assessment, but look for Ca++ on CT when diagnosis in doubt (Left) Axial graphic depicts a fusiform meningioma arising from the optic nerve sheath Characteristic “perioptic cyst” evident behind the globe represents trapped CSF within the nerve sheath (Right) Axial T1WI FS MR demonstrates globular configuration of avidly enhancing ONSM eccentrically surrounding the orbital segment of the right optic nerve As is common, the optic nerve immediately posterior to the globe is spared 1092 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR shows a more symmetric “en plaque” configuration to left ONSM Enhancing tumor outlining the nerve results in the “tram-track” appearance mimicking calcification described on CT (Right) Axial T1WI FS MR reveals pedunculated appearance to ONSM This small lesion resulted in late symptoms, as optic nerve compression is mild There is considerable variability in the imaging appearance of ONSM, though enhancement and sparing of the nerve are fairly consistent findings P.IV(2):65 TERMINOLOGY Abbreviations Optic nerve sheath meningioma (ONSM) Synonyms Perioptic meningioma Definitions Benign, slow-growing neoplasm of optic nerve (ON) dural sheath Distinct entity from intracranial (spheno-orbital) meningioma that extends through orbital apex 90% of meningiomas that involve orbit are secondary lesions rather than primary ONSM IMAGING General Features Best diagnostic clue Enhancing mass surrounding intraorbital optic nerve with Ca++ Location Intraconal or orbital apex mass that arises from optic nerve sheath complex Size Intraorbital ONSM relatively small at presentation because of early symptoms Spheno-orbital tumors have larger intracranial component Morphology Solid, well-defined enlargement of optic nerve complex Encases optic nerve in circumferential pattern, although may show eccentric or pedunculated growth pattern Tubular shape (65%) > pedunculated (25%) > fusiform (10%) Diffuse thickening more common than segmental En plaque variants may occur Radiographic Findings Radiography Optic canal enlargement or skull base hyperostosis may be evident in advanced tumors CT Findings NECT Linear or punctate Ca++ characteristic Present in 1/3 to 1/2 of cases Typically spares distal-most segment of optic nerve as it enters nerve head 1093 Diagnostic Imaging Head and Neck If no Ca++, tumor is isodense to other soft tissue CECT Uniform, moderately intense enhancement “Tram-track” appearance: Tumor enhancement or Ca++ on either side of optic nerve Although relatively specific, “tram-track” is not pathognomonic Pseudotumor, lymphoma, or sarcoid may show this feature MR Findings T1WI Isointense to other soft tissue on noncontrast images T2WI Variably hyperintense to hypointense on T2WI depending on degree of Ca++ “Perioptic cysts” are specific feature Defined as ↑ CSF within nerve sheath surrounding distal optic nerve between tumor and globe STIR Similar to T2, but lesions more conspicuous because of suppression of orbital fat signal T1WI C+ Uniform moderate to marked contrast enhancement Tumor best demonstrated with fat suppression Imaging Recommendations Best imaging tool Contrast-enhanced MR with fat suppression MR better than CT for characterizing tumor relative to adjacent orbital structures MR also better at defining extent of disease involving orbital apex, optic canal, and intracranial structures CT can provide diagnostic information in indeterminate cases by demonstrating Ca++ Protocol advice Post-contrast, fat-suppressed T1WI delineates tumor margins best Perioptic cysts best demonstrated on T2WI with fat saturation DIFFERENTIAL DIAGNOSIS Optic Nerve Glioma Neoplastic enlargement of optic nerve No “tram-track” enhancement, Ca++, or perioptic cysts Typically low-grade pediatric tumor (ONSM usually adult tumor) May be associated with neurofibromatosis type (NF1); ONSM with neurofibromatosis type (NF2) Optic Neuritis Enhancing, T2 hyperintense optic nerve with minimal nerve enlargement or sheath enhancement Often associated with multiple sclerosis Orbital Idiopathic Inflammatory Pseudotumor Ill-defined and usually not isolated to ON sheath Presents with painful exophthalmos Orbital Sarcoidosis When no systemic disease, can be indistinguishable from ONSM on enhanced CT and MR Predilection for lacrimal glands Metastasis Breast and lung most common primaries Often involve choroid & extraocular muscles Orbit Lymphoproliferative Lesions Usually not isolated to nerve sheath Typically well-defined, pliable mass ↓ T2 signal due to high cellularity P.IV(2):66 PATHOLOGY General Features Etiology Benign tumor arising from arachnoid “cap” cells within optic nerve sheath Genetics NF2 is present in 4-12% of patients overall 1094 Diagnostic Imaging Head and Neck 28% of juveniles diagnosed with ONSM are concomitantly diagnosed with NF2 Associated abnormalities Patients with NF2 show characteristic findings, such as bilateral vestibular schwannoma Staging, Grading, & Classification Same WHO classification as for intracranial meningiomas Gross Pathologic & Surgical Features Sharply circumscribed, unencapsulated Circumferential to optic nerve Tightly adherent to perineural pial microvascular structures Rarely invades optic nerve Microscopic Features Histologic features similar to intracranial meningiomas Meningothelial subtype most common in orbit Transitional (54%) and meningotheliomatous (38%) subtypes most common in children Positive for progesterone receptors in 40-80%, more so in women CLINICAL ISSUES Presentation Most common signs/symptoms Slow, painless, progressive unilateral vision loss and proptosis Central vision is preserved until late in disease Other signs/symptoms Diplopia, transient visual obscuration, headache Funduscopic examination Optic disc pallor & swelling typical Optociliary venous shunting in association with optic disc changes is very suggestive of ONSM Clinical profile Classic triad: Visual loss, optic atrophy, optociliary venous shunting Demographics Age Typically presents in 4th & 5th decades, but broad age range ONSM in juvenile patients has distinct natural history Average age at presentation: 10 years More likely associated with NF2 Gender Approximately 2:1 to 4:1 female predominance In children, slightly more common in males Epidemiology Approximately 5% of primary orbital tumors Approximately 2% of meningiomas Radiation exposure, hereditary predisposition, and hormonal influence are cited risk factors Natural History & Prognosis Progressive but slow vision loss is expected in most untreated patients More aggressive behavior in juvenile patients Relative increased size, growth, recurrence rates, and incidence of malignant degeneration Postoperative visual impairment inevitable because tumor is tightly adherent to pia and shares blood supply Treatment Fractionated stereotactic radiotherapy currently considered first-line therapy for patients with preservable vision but progressive impairment Observation with regular visual testing and MR surveillance recommended if vision is good and stable Surgical excision indicated for tumor control if intracranial extension or if vision preservation impossible Generally poor results with optic canal or optic nerve sheath decompression DIAGNOSTIC CHECKLIST Consider Optic nerve glioma is major differential consideration in young patients If imaging appearance is characteristic, radiation therapy without biopsy may provide best chance of vision preservation Image Interpretation Pearls MR is preferred imaging modality for tumor assessment CT shows Ca++ when diagnosis in doubt 1095 Diagnostic Imaging Head and Neck SELECTED REFERENCES Milker-Zabel S et al: Fractionated stereotactic radiation therapy in the management of primary optic nerve sheath meningiomas J Neurooncol 94(3):419-24, 2009 Wilhelm H: Primary optic nerve tumours Curr Opin Neurol 22(1):11-8, 2009 Harold Lee HB et al: Primary optic nerve sheath meningioma in children Surv Ophthalmol 53(6):543-58, 2008 Eddleman CS et al: Optic nerve sheath meningioma: current diagnosis and treatment Neurosurg Focus 23(5):E4, 2007 Miller NR: New concepts in the diagnosis and management of optic nerve sheath meningioma J Neuroophthalmol 26(3):200-8, 2006 Jackson A et al: Intracanalicular optic nerve meningioma: a serious diagnostic pitfall AJNR Am J Neuroradiol 24(6):1167-70, 2003 Andrews DW et al: Fractionated stereotactic radiotherapy for the treatment of optic nerve sheath meningiomas: preliminary observations of 33 optic nerves in 30 patients with historical comparison to observation with or without prior surgery Neurosurgery 51(4):890-902; discussion 903-4, 2002 Lindblom B et al: Perioptic cyst distal to optic nerve meningioma: MR demonstration AJNR Am J Neuroradiol 13(6):1622-4, 1992 P.IV(2):67 Image Gallery (Left) Axial NECT shows the typical “tram-track” calcifications of optic nerve sheath meningioma without obvious soft tissue mass Occasionally, post-traumatic or idiopathic optic nerve sheath calcification can mimic this appearance (Right) Axial T1WI C+ FS MR in the same patient shows typical encasement of the optic nerve by enhancing tumor , the MR equivalent of the “tram-track” sign The presence of enhancing tumor rules out traumatic or idiopathic etiologies 1096 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR demonstrates tumor surrounding the intraorbital and intracanalicular segments of the right optic nerve Note the presence of a dural “tail” along the sphenoid lesser wing (Right) Coronal T1WI C+ FS MR in the same patient confirms enhancement in the right optic canal medial to the anterior clinoid process , as well as diffusely overlying the sphenoid lesser wing As the bulk of the tumor is intraorbital, ONSM is favored over spheno-orbital lesion (Left) Axial T2WI FS MR reveals a globular meningioma involving the intraorbital segment of the right optic nerve Note T2 signal similar to brain parenchyma Though signal is variable, ONSMs, like intracranial lesions, are often relatively hypointense on T2WI (Right) Coronal T2WI FS MR demonstrates the optic nerve to be mildly eccentric within the right ONSM , with the bulk of tumor located medially and superiorly The tumor in this case is hyperintense relative to brain Lacrimal Gland Benign Mixed Tumor > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Benign Tumors > Lacrimal Gland Benign Mixed Tumor Lacrimal Gland Benign Mixed Tumor Deborah R Shatzkes, MD Key Facts Terminology Benign mixed tumor (BMT) of lacrimal gland a.k.a pleomorphic adenoma Benign epithelial neoplasm of lacrimal gland Imaging 1097 Diagnostic Imaging Head and Neck Unilateral circumscribed lacrimal fossa mass with scalloped bony remodeling Anterior superotemporal extraconal orbit Majority originate in orbital lobe of lacrimal gland CT: Mild heterogeneity; occasional punctate calcifications MR: Increased conspicuity of cystic elements Moderate to marked enhancement on CECT and T1 MR Top Differential Diagnoses Lacrimal gland lymphoproliferative lesion Lacrimal gland carcinoma Orbital dermoid/epidermoid Orbital idiopathic inflammatory pseudotumor Lacrimal cyst Clinical Issues Most common benign lacrimal tumor Adenoid cystic carcinoma 2x as common Cumulative low risk of malignant transformation 5% at 10 years; 10% at 20 years; 20% at 30 years Occurs in 2nd to 5th decades (younger age than malignant neoplasms) Presents with slowly progressive painless proptosis Complete surgical excision is curative If capsular disruption, need long-term follow-up Diagnostic Checklist Scalloped bony remodeling on CT is characteristic (Left) Axial CECT demonstrates a slightly heterogeneous, well-circumscribed, enhancing superolateral orbital mass Small internal cysts are a common finding Note opposite normal lacrimal gland (Right) Axial NECT shows a well-defined lobular mass of the left lacrimal gland with internal calcifications identified posteriorly Over 50% of lacrimal gland tumors are benign mixed tumors 1098 Diagnostic Imaging Head and Neck (Left) Coronal NECT reveals a lobular mass in the superior temporal aspect of the left orbit associated with scalloped remodeling of the lacrimal fossa Note typical inferomedial displacement of the globe associated with tumors of the lacrimal region (Right) Axial T1WI C+ FS MR demonstrates uniform, moderately intense enhancement of a small lacrimal fossa BMT This was an incidental finding on a study performed for headache; note an incidental 3rd ventricular cystic lesion P.IV(2):69 TERMINOLOGY Abbreviations Benign mixed tumor (BMT) of lacrimal gland Synonyms Pleomorphic adenoma of lacrimal gland Definitions Benign epithelial neoplasm of lacrimal gland IMAGING General Features Best diagnostic clue Unilateral lacrimal mass with scalloped bony remodeling of lacrimal fossa Location Anterior superotemporal extraconal orbit Majority originate in orbital lobe of gland Morphology Solid, round or oval, circumscribed CT Findings CECT Moderate to marked enhancement Small cystic elements common Bone CT Soft tissue mass with scalloping/remodeling of lacrimal fossa Occasional punctate calcification (33%) MR Findings T1WI Hypointense to isointense; mild heterogeneity T2WI Isointense to hyperintense Increased conspicuity of cystic elements T1WI C+ Moderate to marked enhancement Imaging Recommendations 1099 Diagnostic Imaging Head and Neck Best imaging tool Enhanced MR to confirm circumscribed nature Coronal bone CT to assess bony remodeling DIFFERENTIAL DIAGNOSIS Orbital Lymphoproliferative Lesions Homogeneous enlargement of gland; molds to shape of globe ↑ density on NECT; ↓ T2 MR signal; homogeneous enhancement Lacrimal Gland Carcinoma Lacrimal mass with ill-defined margins and invasion of adjacent bone/soft tissue Imaging features can be nonspecific Orbital Dermoid and Epidermoid Well-circumscribed extraconal mass near frontozygomatic suture DWI high signal if epidermoid; presence of fat = dermoid; scalloping of adjacent bone Orbital Idiopathic Inflammatory Pseudotumor Palpably enlarged, tender gland Diffuse anterior-posterior enlargement of gland with stranding of fat at margins Lacrimal Cyst Well-defined, fluid density/signal lesion within gland parenchyma Dacryoadenitis Tender, enlarged gland often with overlying cellulitis Infiltration and stranding in surrounding fat PATHOLOGY Staging, Grading, & Classification Follows WHO classification for salivary neoplasms Microscopic Features “Pleomorphic” refers to diverse epithelial and myoepithelial components CLINICAL ISSUES Presentation Most common signs/symptoms Slowly progressive painless proptosis Inferomedial globe displacement Demographics Age 2nd to 5th decades Generally younger age than malignant neoplasms Epidemiology 2% of all orbital neoplasms Most common benign epithelial lacrimal tumor Adenoid cystic carcinoma most common malignant tumor & occurs 2x as frequently Natural History & Prognosis Cumulative low risk of malignant transformation 5% at 10 years; 10% at 20 years; 20% at 30 years Treatment Complete surgical excision is curative Lateral orbitotomy for wide exposure Intact removal without rupture or incision Capsular disruption requires long-term follow-up DIAGNOSTIC CHECKLIST Image Interpretation Pearls Scalloped bony remodeling on CT is characteristic SELECTED REFERENCES Rootman J et al: Changes in the 7th edition of the AJCC TNM classification and recommendations for pathologic analysis of lacrimal gland tumors Arch Pathol Lab Med 133(8):1268-71, 2009 Weis E et al: Epithelial lacrimal gland tumors: pathologic classification and current understanding Arch Ophthalmol 127(8):1016-28, 2009 Currie ZI et al: Long-term risk of recurrence after intact excision of pleomorphic adenomas of the lacrimal gland Arch Ophthalmol 125(12):1643-6, 2007 1100 Diagnostic Imaging Head and Neck Malignant Tumors Retinoblastoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Malignant Tumors > Retinoblastoma Retinoblastoma Deborah R Shatzkes, MD Key Facts Terminology Retinoblastoma (RB) Malignant primary retinal neoplasm Trilateral/quadrilateral RB: Bilateral ocular RB plus pineal ± suprasellar tumors Imaging Unilateral in 60%, bilateral in 40% Trilateral or quadrilateral disease rare Extraocular extension in < 10% Indicates poor prognosis CT: Calcification in > 90% MR: Assess extent of intraocular tumor & presence of optic nerve, orbital or intracranial involvement T1: Mild hyperintensity T2: Moderate to marked hypointensity Moderate to marked heterogeneous enhancement Top Differential Diagnoses Persistent hyperplastic primary vitreous Coats disease Retinopathy of prematurity Orbital toxocariasis Pathology Primitive neuroectodermal tumor (PNET) Inherited (germline): Multilateral > unilateral Clinical Issues Most common intraocular tumor of childhood Leukocoria in 50-60% 90-95% diagnosed by age years Diagnostic Checklist Calcified intraocular mass in child is RB until proven otherwise (Left) Axial graphic depicts retinoblastoma with lobulated tumor extending through the limiting membrane into the vitreous Punctate calcifications are characteristic (Right) Axial CECT demonstrates a lobular endophytic retinoblastoma containing small calcifications and filling much of the vitreous compartment A calcified ocular mass in a child represents retinoblastoma until proven otherwise 1101 Diagnostic Imaging Head and Neck (Left) CECT shows an enhancing soft tissue mass within the posterolateral right globe, without extension beyond the sclera Note the focal calcific density within the tumor; calcification may be absent in early lesions (Right) A similar lesion is evident on this T2WI FS MR at the margin of the left optic disc Virtually all RBs demonstrate hypointensity relative to vitreous on T2WI; the lenticular shape is typical for early lesions P.IV(2):71 TERMINOLOGY Abbreviations Retinoblastoma (RB) Definitions Malignant primary retinal neoplasm Trilateral RB: Bilateral ocular tumors plus midline intracranial neuroblastic tumor, typically pineal Quadrilateral (tetralateral) RB: Bilateral disease plus pineal and suprasellar tumors IMAGING General Features Best diagnostic clue Intraocular calcified mass in child Location Diagnosis typically with ophthalmoscopy and ultrasound MR for tumor mapping and prognostication Unilateral in 60%, bilateral in 40% Trilateral or quadrilateral disease rare Extraocular extension in < 10% Spreads along scleral vessels into orbit and along optic nerve to subarachnoid space Predicators for metastatic disease: Involvement of optic nerve, choroid, anterior chamber or orbit Anterior chamber enhancement reflects neoangiogenesis and is associated with more aggressive tumor behavior Role of MR imaging Exclude pseudoneoplastic lesions Assess intraocular (choroid, sclera, prelaminar optic nerve), extraocular (postlaminar optic nerve, orbital) and intracranial (pineal, parasellar, metastatic) involvement Size Decreased ocular size in RB Growth patterns Endophytic form (45%) Inward protrusion into vitreous Associated with vitreous seeding Exophytic form (45%) Outward growth into subretinal space, typically with hemispherical configuration Associated retinal detachment & subretinal exudate 1102 Diagnostic Imaging Head and Neck Mixed endophytic and exophytic (10%) CT Findings NECT Punctate or finely speckled calcification (> 90-95%) CECT Moderate to marked heterogeneous enhancement MR Findings T1WI Variable, mildly hyperintense (vs vitreous) T2WI Moderate to markedly hypointense (vs vitreous) Helps distinguish from other congential lesions (PHPV, Coats) that are hyperintense Best for identifying subretinal fluid ± vitreous hemorrhage T1WI C+ Moderate to marked heterogeneous enhancement Best to assess extent of intraocular disease & presence of optic nerve or extraocular invasion Choroidal invasion: Localized thickening and heterogeneous contrast enhancement near tumor Scleral invasion: Interruption in thin hypointense zone surrounding enhancing choroid Optic nerve invasion: Thickening of optic disc (prelaminar), enhancement of nerve (postlaminar) MR shown to have low sensitivity & specificity in assessing optic nerve invasion Ultrasonographic Findings A-scan: Highly reflective spikes at calcifications B-scan: Echodense, irregular mass with focal shadows Imaging Recommendations Best imaging tool Enhanced MR with fat-saturated T1- and T2-weighted imaging best for tumor mapping Calcification on CT relatively specific Protocol advice Include whole brain to assess for trilateral disease DIFFERENTIAL DIAGNOSIS Persistent Hyperplastic Primary Vitreous Small globe, hyperdense; no Ca++ Hyperintense on T2WI; retrolental tissue stalk Coats Disease Normal size globe, hyperdense; no Ca++ Hyperintense on T1WI and T2WI Retinopathy of Prematurity Retrolental fibroplasia; associated with excess oxygen and premature retinal vessels Small globe, hyperdense, bilateral; Ca++ if advanced Toxocariasis, Orbit Uveoscleral enhancement; no Ca++ acutely Other Causes of Leukocoria Retinal detachment Subretinal hemorrhage, retinal folds Choroidal osteoma Choroidal hemangioma (hamartoma) Retinal dysplasia PATHOLOGY General Features Etiology Primitive neuroectodermal tumor (PNET) Sporadic (nongermline): 60% of RB Majority (85%) of unilateral disease Inherited (germline): 40% of RB Essentially all bilateral and multilateral disease Minority (15%) of unilateral disease Autosomal dominant with 90% penetrance Positive family history in 5-10% New germline mutations in 30-35% 1103 Diagnostic Imaging Head and Neck P.IV(2):72 Genetics RB1 gene: Chromosome 13, q14 band Somatic mosaicism in 10-20% of RB patients Associated abnormalities Risk of 2nd malignancy ↑ in germline disease Sarcoma, melanoma, CNS tumors, epithelial tumors (lung, bladder, breast) 20-30% in nonirradiated patients 50-60% in irradiated patients Occur within 30 years, average 10-13 years 13q deletion syndrome: RB plus multiple organ system anomalies Staging, Grading, & Classification Reese-Ellsworth classification Groups 1-5 Based on size, location, and multifocality More useful in radiation therapy management International (Murphree) classification of retinoblastoma (ICRB); newer Groups A through E Based on size, retinal location, subretinal or vitreous seeding, and several specific prognostic features More useful in chemotherapy management Gross Pathologic & Surgical Features Yellowish-white irregular pedunculated retinal mass Microscopic Features Small round cells, scant cytoplasm, and large nuclei Flexner-Wintersteiner rosettes and fleurettes CLINICAL ISSUES Presentation Most common signs/symptoms Leukocoria (50-60%) Other signs/symptoms Severe vision loss Strabismus common with macular involvement or retinal detachment Proptosis if significant orbital disease Rubeosis iridis (redness of iris secondary to neovascularization) correlates with anterior chamber enhancement on MR Inflammatory signs in 10% Demographics Age RB is congenital but usually not apparent at birth Average age at diagnosis: 18 months Unilateral: 24 months, bilateral: 13 months Earlier with family history and routine screening 90-95% diagnosed by age years Epidemiology Most common intraocular tumor of childhood Incidence of 1:17,000 live births Has increased in past 60 years 3% of cancers in children under 15 1% of cancer deaths; 5% of childhood blindness Natural History & Prognosis Poor prognosis for extraocular disease < 10% 5-year disease-free survival Degree of nerve involvement correlates with survival Superficial or no invasion: 90% Invasion to lamina cribrosa (prelaminar): 70% Invasion beyond lamina cribrosa (postlaminar): 60% Involvement at surgical margin: 20% 1104 Diagnostic Imaging Head and Neck Poor prognosis for trilateral disease or CSF spread < 24 month survival Treatment > 95% of children with RB in USA are cured with modern techniques Challenge is maintaining eye & vision Based on tumor volume and localization, intraocular tumor extension, and extraocular stage of disease Enucleation Advanced disease with no chance of preserving useful vision External beam radiation therapy (EBRT) Indicated for bulky tumors with seeding Unfavorable complications, e.g., arrested bone growth and radiation-induced tumors Chemotherapy (“chemoreduction”) Currently favored first-line therapy for lower grade intraocular tumors Limits need for external radiation and enucleation Combine with other local modalities to achieve cure Plaque radiotherapy Locally directed, I-125 or other isotope Selected solitary or small tumors Cryotherapy Primary local treatment of small anterior tumors Photocoagulation Primary local treatment of small posterior tumors DIAGNOSTIC CHECKLIST Consider Assess for intraocular and extraocular spread, including optic nerve Check for intracranial trilateral or quadrilateral disease in pineal and suprasellar regions Image Interpretation Pearls Calcified intraocular mass in child is RB until proven otherwise SELECTED REFERENCES de Graaf P et al: Contrast-Enhancement of the Anterior Eye Segment in Patients with Retinoblastoma: Correlation between Clinical, MR Imaging, and Histopathologic Findings AJNR Am J Neuroradiol Epub ahead of print, 2009 Mallipatna AC et al: Management and outcome of unilateral retinoblastoma J AAPOS 13(6):546-50, 2009 Wilson MW et al: Lack of correlation between the histologic and magnetic resonance imaging results of optic nerve involvement in eyes primarily enucleated for retinoblastoma Ophthalmology 116(8):1558-63, 2009 de Graaf P et al: Eye size in retinoblastoma: MR imaging measurements in normal and affected eyes Radiology 244(1):273-80, 2007 Shields CL et al: The International Classification of Retinoblastoma predicts chemoreduction success Ophthalmology 113(12):2276-80, 2006 de Graaf P et al: Retinoblastoma: MR imaging parameters in detection of tumor extent Radiology 235(1):197-207, 2005 P.IV(2):73 Image Gallery 1105 Diagnostic Imaging Head and Neck (Left) Enhanced T1WI MR shows bulky enhancing intraocular masses compatible with bilateral retinoblastomas Note prominent enhancement of each iris ; anterior segment enhancement is associated with more aggressive tumor behavior (Right) Axial T2WI FS MR reveals lobular, hypointense mass filling much of the vitreous compartment of the left globe Note posterior fluid level indicating associated vitreous hemorrhage (Left) Axial T1WI C+ MR shows moderately enhancing retinoblastoma, associated with prominent anterior segment enhancement Note intact thin lines of enhancing choroid and hypointense sclera indicating absence of invasion of these structures (Right) Axial T1WI C+ FS MR demonstrates RB virtually filling the right globe There is subtle thickening and enhancement of the right optic nerve , indicating post laminar invasion 1106 Diagnostic Imaging Head and Neck (Left) On T1WI C+ FS MR, interruption of linear hypodensity with focal contour abnormality indicates scleral invasion of RB on the right The postlaminar optic nerve demonstrates asymmetric enlargement and enhancement on the left (Right) In this patient with pathologically proven trilateral retinoblastoma, only ocular lesion is identified on this fat-sat enhanced T1WI There is a bulky enhancing suprasellar and parasellar mass, with extension along dural reflections Ocular Melanoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Malignant Tumors > Ocular Melanoma Ocular Melanoma Deborah R Shatzkes, MD Key Facts Terminology Synonyms: Uveal melanoma, choroidal melanoma, ocular adnexal melanoma Malignancy arising from melanocytes within choroid Imaging US primary imaging modality for evaluation of intraocular disease Enhanced MR of with fat suppression to assess extraocular disease Location: Choroid > ciliary > iris Dome- or mushroom-shaped with broad choroidal base Often with associated retinal detachment CT Solid soft tissue density mass with moderate enhancement MR Mildly to strongly T1 hyperintense to vitreous Strongly T2 hypointense Moderate, diffuse tumor enhancement Top Differential Diagnoses Choroidal metastasis Choroidal hemangioma Retinal detachment Choroidal osteoma Clinical Issues Most common primary intraocular tumor in adults Globe sparing treatment options for small/medium tumors Prognosis worsens with extraocular invasion, extension through Bruch membrane, and ↑ size Death from systemic metastases; liver most common 1107 Diagnostic Imaging Head and Neck (Left) Axial CECT demonstrates a bilobed left choroidal lesion , homogeneously hyperdense on this enhanced study Distinction between tumor and retinal detachment is difficult (Right) Sagittal T1WI MR without contrast demonstrates a small mass along the posterior choroid that is moderately hyperintense relative to vitreous Melanoma is classically known for causing shortening of T1 and T2 relaxation times, resulting in a lesion that is hyperintense (bright) on T1 and hypointense (dark) on T2 (Left) Axial T1WI MR reveals a tumor along the nasal choroidal surface of the right globe , which is only mildly hyperintense relative to vitreous Ocular melanomas distant from the macula may be quite large before significant visual defects are apparent (Right) Axial T1WI C+ MR in the same patient shows intense enhancement of this domeshaped ocular mass Lenticular-shaped mild hyperintensity lateral to the enhancing lesion is compatible with associated retinal detachment P.IV(2):75 TERMINOLOGY Synonyms Uveal melanoma, ocular adnexal melanoma, choroidal melanoma Definitions Primary malignancy of uveal tract IMAGING General Features Best diagnostic clue Enhancing intraocular mass with ↑ T1WI MR signal in adult Location 1108 Diagnostic Imaging Head and Neck Temporal hemisphere posterior to equator most common site of origin Posterior uvea Choroidal lesions (85%) Posterior segment peripheral mass Trans-scleral/optic nerve extension when advanced Ciliary body (10%): Behind posterior chamber Anterior uvea Iris lesions (5%): Within anterior chamber Size Criteria for therapeutic decisions Small: 5-16 mm diameter, < mm depth Medium: 5-16 mm diameter, 3-10 mm depth Large: > 16 mm diameter, > 10 mm depth Morphology Dome- or mound-shaped, broad choroidal base “Mushroom” shape implies penetration through Bruch membrane (separates choroid from retina) Diffuse, laterally spreading form in 5% Typically solid Cavitary variant appears cystic CT Findings NECT Solid soft tissue density mass Calcification rare; may occur after therapy CECT Diffuse moderate enhancement MR Findings T1WI Mildly to strongly hyperintense compared to vitreous Signal increases with ↑ melanotic pigmentation Retinal detachments with subretinal fluid: Variably hyperintense, due to blood products or protein T2WI Strongly hypointense compared to vitreous Subretinal fluid: Isointense to hypointense, depending on nature of exudate T1WI C+ Moderate, diffuse tumor enhancement No enhancement of retinal detachment or subretinal fluid Ultrasonographic Findings A-scan Low to medium internal reflectivity Spike at tumor surface; vascular oscillations B-scan Domed, lobulated, or mushroom-shaped mass Choroidal excavation/scleral bowing indicate invasion Nuclear Medicine Findings PET/CT Limited utility at primary site, sensitive for detection of metastases Higher tumor SUV correlated with chromosome loss and larger tumor size (poor prognostic signs) I-123-IMP SPECT May be helpful in diagnosis of atypical or indeterminate lesions Imaging Recommendations Best imaging tool Ultrasound for intraocular tumor evaluation Enhanced MR of orbits with fat suppression to assess extraocular disease DIFFERENTIAL DIAGNOSIS Choroidal Metastasis Breast and lung primaries most common Located on temporal side of macula Choroidal Hemangioma (Hamartoma) 1109 Diagnostic Imaging Head and Neck Benign vascular lesion Circumscribed form in adults ± retinal detachment Diffuse form in infants associated with Sturge-Weber > T2 signal and enhancement than melanoma Retinal Detachment Serous, exudative, or hemorrhagic Myriad etiologies, including trauma, inflammation, underlying tumor, or systemic disease Does not enhance, but may obscure underlying mass Choroidal Osteoma Tendency to occur in young adult females Often asymptomatic, found incidentally Curvilinear, plaque-like Ca++ lesion along posterior globe Idiopathic Inflammatory Pseudotumor May affect any orbital structure Globe/scleral involvement → endophthalmitis Painful, inflammatory presentation Retinoblastoma Most common intraocular tumor in children Rarely occurs in adults Calcification in 95% PATHOLOGY General Features Etiology Primary malignancy arising from melanocytes within choroid Genetics Several mutations and familial melanoma syndromes have been identified P.IV(2):76 Associated abnormalities Ocular melanocytosis, dysplastic nevus syndrome, xeroderma pigmentosum Risk factors Most arise within preexisting melanocytic nevi Sun exposure, light-colored irides increase risk Staging, Grading, & Classification Modified Callender classification Spindle cell nevus: Premalignant Spindle cell melanoma: A and B cell types Fascicular: Palisaded B cells (spindle subtype) Necrotic: Significant necrosis prior to treatment Mixed: Spindle and epithelioid cells Epithelioid: Predominantly epithelioid cells Gross Pathologic & Surgical Features Range from heavily pigmented to amelanotic Discoloration and atrophy of overlying retina Microscopic Features cell types used for classification Spindle A: Elongated nuclei, few mitoses Spindle B: Plump nuclei, more prominent nucleoli Epithelioid: Ovoid nuclei, anaplastic, poor prognosis CLINICAL ISSUES Presentation Most common signs/symptoms Painless vision disturbance Frequent coexisting retinal detachment Other signs/symptoms Blurred vision, scotoma, field loss, floaters Pain rare (due to ciliary nerve involvement) Clinical profile 1110 Diagnostic Imaging Head and Neck Frequently asymptomatic Often discovered on routine eye exam Presentation more advanced when located farther from fovea and nerve head Ophthalmoscopy Dome-shaped mass of variable pigmentation Orange discoloration of overlying retina; exudative detachment may obscure mass Demographics Age Peak incidence: 6th decade Iris melanoma presents slightly younger Ethnicity Northern European descent highest risk Hispanic, Asian uncommon African descent rare Epidemiology Most common primary intraocular tumor in adults Incidence 6-8 per 1,000,000 5% of all melanomas Natural History & Prognosis Appears to be systemic disease at presentation with treatment of primary disease curative in some patients Death from systemic metastases (liver most common) 5-/10-year cumulative metastasis rates 25/34%, respectively No effective treatment for metastatic disease Worse prognosis Large size, anterior location, extension through Bruch membrane, trans-scleral/nerve invasion Optic nerve invasion most common in juxtapapillary or diffuse tumors Amelanotic, epithelioid pattern, highly mitotic Treatment Protocols largely driven by results of Collaborative Ocular Melanoma Study (COMS) Group Multicenter NIH/National Eye Institute trial Observation Suitable for indeterminate stable small nevi Sequential ultrasound to document stability Transpupillary thermotherapy Option for small tumors; preserves vision Tumor heating by infrared radiation Surgical block excision (sclerouvectomy) Option for small tumors < 1/3 of globe circumference Preserves some vision Plaque brachytherapy Common option for medium-sized tumors Isotope plaque (I-125) sutured over tumor site External beam irradiation Alternative for medium-sized tumors Charged particles (protons, helium ions) Gamma knife radiosurgery Surgical enucleation Standard for large tumors, treatment failures Radical exenteration for widespread tumor DIAGNOSTIC CHECKLIST Consider Most common ocular tumor in adults Ultrasonography remains most frequently utilized diagnostic modality for intraocular disease MR more accurate than US for extraocular spread Image Interpretation Pearls Enhancement reliably distinguishes tumor from associated retinal detachment on MR SELECTED REFERENCES McCannel TA et al: Association of positive dual-modality positron emission tomography/computed tomography imaging of primary choroidal melanoma with chromosome loss and tumor size Retina 30(1):146-51, 2010 1111 Diagnostic Imaging Head and Neck Collaborative Ocular Melanoma Study Group: The COMS randomized trial of iodine 125 brachytherapy for choroidal melanoma: V Twelve-year mortality rates and prognostic factors: COMS report No 28 Arch Ophthalmol 124(12):1684-93, 2006 Lemke AJ et al: Uveal melanoma: correlation of histopathologic and radiologic findings by using thin-section MR imaging with a surface coil Radiology 210(3):775-83, 1999 Mafee MF: Uveal melanoma, choroidal hemangioma, and simulating lesions Role of MR imaging Radiol Clin North Am 36(6):1083-99, 1998 P.IV(2):77 Image Gallery (Left) Axial T1WI MR obtained with a regional orbit coil demonstrates a well-defined hyperintense mass within the posterior nasal quadrant of the right globe The mushroom-shaped configuration with waist-like narrowing at the tumor base indicates that invasion of Bruch membrane is likely (Right) Micropathology at low power shows a mushroom-shaped melanoma penetrating through Bruch membrane Bulky extraocular tumor is seen extending posteriorly through the optic nerve head (Left) Axial T2WI MR shows the typical appearance of intraocular melanoma with the tumor appearing markedly hypointense relative to vitreous This small choroidal tumor remains confined to the globe (Right) Axial CECT shows an enhancing tumor within the posterior aspect of the left globe with an unusually large extraocular (retrobulbar) component resulting in proptosis The very large size of this melanoma and the presence of extraocular extension are both poor prognostic factors 1112 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR shows thickening of the posterior choroid of the left globe with extraocular tumor extending through the supraorbital fissure into the cavernous sinus This is a variant case, both because of the large volume of extraocular disease, and its highly infiltrative appearance (Right) Axial T2WI MR in the same patient demonstrates characteristic low T2 signal in both intraocular and extraocular components in the lesion, supporting the diagnosis of ocular melanoma Orbital Lymphoproliferative Lesions > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Malignant Tumors > Orbital Lymphoproliferative Lesions Orbital Lymphoproliferative Lesions Deborah R Shatzkes, MD Key Facts Terminology Spectrum from benign to malignant Lymphoid hyperplasia: 10-40% Lymphoma (NHL): 60-90% Low-grade primary small B-cell lymphoma most common (especially MALT) Imaging Solid, pliable tumor occurring anywhere in orbit Prefers anterior compartment Molds to and encases orbital structures CT: Isodense to slightly hyperdense Diffuse, homogeneous enhancement MR: Isointense to muscle on T1WI MR Mildly hyperintense to muscle on T2WI MR, reflecting high cellularity Infiltrative appearance & bone destruction associated with unfavorable histology Top Differential Diagnoses Lacrimal gland benign mixed tumor Idiopathic orbital inflammatory pseudotumor Sarcoidosis Thyroid ophthalmopathy Orbital cellulitis Orbital metastasis Pathology Reactive (polyclonal) or malignant (monoclonal) lymphocytic proliferation Clinical Issues Insidious anterior orbital mass Indolent course for low-grade and low-stage tumors Major long-term risk is development of systemic lymphoma (33-50%) 1113 Diagnostic Imaging Head and Neck (Left) Axial CECT demonstrates a lobular retrobulbar mass conforming to the shape (“molding”) of the posterior aspect of the right globe Only minimal flattening of the scleral margin is present This MALT lymphoma has homogeneous density characteristics (Right) Axial CECT shows focal fusiform enlargement of the right lateral rectus muscle in a patient who presented with insidious onset of painless right proptosis Biopsy of a facial lymph node revealed NHL (Left) Axial CECT reveals preseptal orbital soft tissue thickening (orbital septum and conjunctiva) in this case of isolated anterior compartment NHL LPLO most commonly involves preseptal soft tissues (Right) Axial T1WI C+ FS MR reveals a diffusely infiltrating lesion that involves the extraconal , conal, intraconal , and preseptal regions of the right orbit Virtually every portion of the orbit may be involved in LPLO This appearance mimics cellulitis or pseudotumor P.IV(2):79 TERMINOLOGY Abbreviations Lymphoproliferative lesions of orbit (LPLO) Synonyms Ocular adnexal lymphoma (OAL) Orbital lymphoproliferative tumors (OLT) Definitions LPLO spectrum from benign to malignant Lymphoid hyperplasia: 10-40% Reactive hyperplasia; benign, polyclonal 1114 Diagnostic Imaging Head and Neck Atypical hyperplasia; indeterminate Non-Hodgkin lymphoma (NHL): 60-90% Low-grade primary small B-cell lymphoma most common (especially mucosa-associated lymphoid tissue [MALT]) Diffuse large B-cell lymphoma, usually systemic Other: Burkitt, T-cell, mantle cell lymphoma IMAGING General Features Best diagnostic clue Solid, pliable, homogeneously enhancing orbital tumor that molds to & encases orbital structures Location Can occur anywhere in orbit; predilection for anterior extraconal space & lacrimal gland Anterior extraconal orbit: Often centered in superotemporal quadrant Predilection for lacrimal gland & may be only site of involvement Conjunctival disease frequent; isolated (20%) May present with primary extraocular muscle involvement, simulating thyroid orbitopathy Diffuse infiltrative form may occur with intraconal, muscular, or perineural involvement Rarely multifocal within orbit (< 5%) Bilateral in 25%, usually higher grade lesions Morphology Discrete, lobulated margins with molding to adjacent structures in lower grade lesions May have infiltrative or inflammatory appearance CT Findings NECT Isodense to slightly hyperdense Due to highly cellular nature & ↑ N:C ratio CECT Moderate diffuse, homogeneous enhancement Bone CT Bone destruction indicates aggressive histology Molding associated with more indolent disease MR Findings T1WI Mildly hyperintense to muscle; homogeneous T2WI Only mildly hyperintense to muscle Reflects high cellularity T1WI C+ Moderate to marked homogeneous enhancement Nuclear Medicine Findings PET/CT Limited value in assessing orbital disease due to high activity in extraocular muscles and typical small volume of disease Useful in screening for systemic lymphoma Imaging Recommendations Best imaging tool MR is modality of choice for evaluating location and extent of disease CECT adequate in many situations Often 1st study done for orbital symptoms Protocol advice Axial and coronal MR: T1, T2, and post contrast with fat suppression essential DIFFERENTIAL DIAGNOSIS Idiopathic Orbital Inflammatory Pseudotumor Presentation typically more acute & painful Similar wide range of imaging appearances Orbital Sarcoidosis Painless masses anywhere in orbit Predilection for lacrimal glands; may be bilateral Thyroid Ophthalmopathy 1115 Diagnostic Imaging Head and Neck Painless, often bilateral symmetric proptosis Extraocular muscle enlargement Lacrimal Gland Benign Mixed Tumor Unilateral painless lacrimal mass ↑ T2 MR signal Orbital Sjögren Syndrome Lacrimal involvement with keratoconjunctivitis sicca Look for bilateral parotid enlargement, cysts, Ca+ Orbital Cellulitis Presents with pain, erythema Discrete orbital masses are less common Look for sinus source of infection Orbital Metastasis Can occur anywhere in orbit Breast & lung carcinoma are common primaries PATHOLOGY General Features Etiology Reactive or malignant lymphocytic proliferation Chlamydia psittaci infection has been linked with some low-grade ocular lymphomas Genetics Hyperplasia: Polyclonal Lymphoma: Monoclonal Associated abnormalities Systemic conditions Collagen vascular disease Sjögren disease Hematologic malignancy Immunocompromised status P.IV(2):80 AIDS Transplant patients Staging, Grading, & Classification WHO classification of lymphoid neoplasms B cell Most common orbital type MALT (mucosa-associated lymphoid tissue), a.k.a extranodal marginal zone lymphoma (EMZL), is common subtype T-cell & T/NK-cell Hodgkin lymphoma Staging of lymphomas (Ann Arbor system) I: Single node region or extralymphatic site (E) II: nodal regions or single extralymphatic site with regional nodes (E) III: Lymph node regions both sides of diaphragm, with extralymphatic (E) or spleen (S) involvement IV: Disseminated extralymphatic sites ± nodes Subclassification A/B: Without (A) or with (B) systemic symptoms (weight loss, fever, night sweats) Most MALT NHL stage IE-A or IIE-A at presentation Microscopic Features Common feature of all LPLO subtypes: Cellular lymphocytic infiltration Hyperplasia: Polymorphous infiltrate of lymphocytes, follicle formation, endothelial proliferation Small B-cell lymphoma: Small round lymphocytes, vaguely nodular, plasma cells MALT has characteristic marginal zone cells Large B-cell lymphoma: Diffuse sheets of large malignant lymphocytes CLINICAL ISSUES Presentation Most common signs/symptoms Insidious anterior orbital/eyelid swelling Fleshy mass visible if conjunctiva involved 1116 Diagnostic Imaging Head and Neck Proptosis, diplopia Globe displacement (nonaxial, inferior) in 50% Other signs/symptoms Fever, night sweats, weight loss Clinical profile basic clinical syndromes Indolent painless orbital mass (most common) Fulminant orbital mass (immunocompromised) Regional bony mass (secondary orbit extension) Neuro-ophthalmic (CNS disease) Demographics Age Elderly (> 60 years) Epidemiology 5-10% of orbital masses Constitutes 1-2% of NHL, 8% of extranodal lymphoma Orbit involvement develops in 5% of systemic NHL Systemic lymphoma (SL) in up to 50% at presentation Natural History & Prognosis Indolent course for primary low-grade and low-stage (IE-A) tumors Major long-term risk is development of SL (33-50%) Systemic relapse typically begins in abdominal, pelvic, or neck lymph nodes Histology influences risk of SL Small B cell (atypical hyperplasia, MALT, etc.): 25-50% All others (large B cell, mantle cell, T cell, etc.): 50-75% Orbital site influences risk of SL Eyelid: 67% Orbit: 35% Conjunctiva: 20% Increased risk of SL in bilateral disease Very good prognosis for MALT lesions following radiotherapy Survival: year = 90-100%, 10 year = 70-90% Local control approaches 100% Indolent course even after relapse Treatment Lymphoid hyperplasia Responsive to steroids Cytotoxic agents, monoclonal antibodies (rituximab) or low-dose radiation for widespread or recalcitrant lesions Low-grade small B-cell lymphoma (esp MALT) Excellent response to radiation therapy alone Complications (cataracts, dry eye) increase > 30 Gy High-grade diffuse B-cell lymphoma Systemic chemotherapy or immunotherapy Local radiation treatment may be beneficial in selected cases DIAGNOSTIC CHECKLIST Consider Whole body staging and surveillance are indicated because of risk of development of systemic lymphoma Tumor location has significant impact on eventual risk of systemic lymphoma Image Interpretation Pearls Broad range of imaging manifestations Carefully examine anterior compartment structures, including orbital septum, conjunctiva, and lids Consider LPLO in differential for any orbital mass SELECTED REFERENCES Cohen VM: Treatment options for ocular adnexal lymphoma (OAL) Clin Ophthalmol 3:689-92, 2009 Demirci H et al: Orbital lymphoproliferative tumors: analysis of clinical features and systemic involvement in 160 cases Ophthalmology 115(9):1626-31, 1631, 2008 Gayed I et al: Value of positron emission tomography in staging ocular adnexal lymphomas and evaluating their response to therapy Ophthalmic Surg Lasers Imaging 38(4):319-25, 2007 1117 Diagnostic Imaging Head and Neck Sullivan TJ et al: Imaging features of ocular adnexal lymphoproliferative disease Eye (Lond) 20(10):1189-95, 2006 Akansel G et al: MRI patterns in orbital malignant lymphoma and atypical lymphocytic infiltrates Eur J Radiol 53(2):175-81, 2005 Weber AL et al: Lymphoproliferative disease of the orbit Neuroimaging Clin N Am 6(1):93-111, 1996 P.IV(2):81 Image Gallery (Left) Coronal T1WI MR shows an infiltrating mass in the medial anterior extraconal orbit that “points” into the nasolacrimal duct Biopsy revealed follicular lymphoma, a less favorable histology than the more common MALT lymphoma (Right) Coronal T2WI FS MR in the same patient demonstrates typical intermediate T2 signal , reflecting the highly cellular nature of these lymphoproliferative neoplasms (Left) Coronal CECT reveals a highly infiltrative LPLO in the inferior aspect of the left orbit, with extension into the inferior orbital fissure This typically homogeneous lesion has markedly ill-defined margins (Right) Sagittal CECT in the same patient demonstrates further infiltrative extension of the posterior orbital lesion through the inferior orbital fissure and into the pterygopalatine fossa Ill-defined lesions often demonstrate more aggressive histology 1118 Diagnostic Imaging Head and Neck (Left) Axial CECT reveals severe left proptosis with tenting of the optic disc This mantle cell lymphoma, demonstrating typical homogeneous density on CECT, has destroyed much of the left ethmoid complex (Right) Coronal T1WI C+ FS MR shows bilateral lobular homogeneously enhancing lacrimal masses This is a common presentation for LPLO The differential for this appearance includes sarcoidosis, Sjögren syndrome, and Wegener granulomatosis Lacrimal Gland Carcinoma > Table of Contents > Part IV - Sinonasal Cavities and Orbit > Section - Orbit > Malignant Tumors > Lacrimal Gland Carcinoma Lacrimal Gland Carcinoma Deborah R Shatzkes, MD Key Facts Terminology Malignant epithelial neoplasm of lacrimal gland Subtypes: Adenoid cystic carcinoma (ACCa), adenocarcinoma, squamous cell carcinoma, carcinoma ex pleomorphic adenoma Imaging Irregular or lobular lacrimal gland mass Bone destruction (70%) best indicator of malignant nature CT: Isodense with moderate enhancement Bone algorithm CT to delineate bone erosion MR: T1 isointense with moderate to prominent T2 hyperintensity and enhancement Post-gad fat-suppressed images best for tumor mapping & identifying perineural spread Top Differential Diagnoses Benign mixed tumor Lymphoproliferative lesion Dacryoadenitis Idiopathic inflammatory pseudotumor Sarcoidosis Sjögren syndrome Wegener granulomatosis Pathology Parallels that of salivary gland neoplasms Divided into low and high grade based on WHO classification of salivary tumors Clinical Issues ˜ 2% of orbital neoplasms ACCa most common malignant lacrimal tumor Must assess for perineural spread 1119 Diagnostic Imaging Head and Neck (Left) Coronal graphic depicts an infiltrating mass of the right lacrimal gland The superolateral bony orbit is invaded by this lacrimal gland carcinoma, and the globe is displaced inferomedially (Right) Coronal T2WI FS MR shows a markedly hyperintense, somewhat heterogeneous mass with lobulated, circumscribed borders centered in the right lacrimal fossa In the absence of bone destruction, this adenoid cystic carcinoma cannot be distinguished from a benign lacrimal tumor (Left) Coronal T1WI C+ FS MR reveals an irregular mass in the superolateral right orbit with bone destruction and extension into both the anterior cranial and temporalis fossae Biopsy showed carcinoma ex pleomorphic adenoma (Right) Axial NECT shows extensive local infiltration of an adenocarcinoma that invades the preseptal tissues , as well as conal and intraconal retrobulbar spaces The mass is closely apposed to the globe with scleral irregularity suspicious for invasion P.IV(2):83 TERMINOLOGY Synonyms Subtypes include adenoid cystic carcinoma (ACCa), adenocarcinoma, squamous cell carcinoma, acinic cell carcinoma, carcinoma ex pleomorphic adenoma Definitions Malignant epithelial neoplasm of lacrimal gland IMAGING General Features Best diagnostic clue Irregular lacrimal fossa mass with bone erosion 1120 Diagnostic Imaging Head and Neck Location Superior temporal quadrant of orbit Contiguous or perineural spread to surrounding structures and skull base CT Findings NECT Lobular or infiltrative isodense mass CECT Moderate to intense enhancement Bone CT Bone destruction in 70% Best indicator of malignant nature Distinguish from bone remodeling as seen in lesions such as benign mixed tumor MR Findings T1WI Isointense to mildly hypointense to muscle T2WI Moderate to prominent hyperintensity T1WI C+ Moderate to intense enhancement Imaging Recommendations Best imaging tool Enhanced MR with fat suppression best for mapping tumor extent & perineural spread Protocol advice Bone algorithm CT to identify osseous erosion DIFFERENTIAL DIAGNOSIS Lacrimal Benign Mixed Tumor Slow-growing mass Scalloped, bone remodeling Orbital Lymphoproliferative Lesion Typically show lower T2 signal intensity Dacryoadenitis Acute to subacute onset of painful swelling Orbital Idiopathic Inflammatory Pseudotumor Steroid-responsive, noninfectious inflammation Painful & may be bilateral Orbital Sarcoidosis Granulomatous process ± concurrent sinusitis Orbital Sjögren Syndrome Autoimmune sialadenitis Orbital Wegener Granulomatosis Granulomatous vasculitis with aggressive sinusitis PATHOLOGY Staging, Grading, & Classification AJCC 7th edition incorporated major changes in lacrimal staging Parallels that of salivary gland neoplasms Divided into low and high grade based on WHO classification of salivary tumors Low-grade tumors include carcinoma ex pleomorphic adenoma and acinic cell carcinoma High-grade tumors include ACCa, squamous cell carcinoma, and adenocarcinoma CLINICAL ISSUES Presentation Most common signs/symptoms Inferomedial globe displacement (75%) Other signs/symptoms Diplopia Pain → bone/perineural involvement Sensory loss in distribution of lacrimal nerve Demographics Epidemiology Rare: 2% of orbital neoplasms Epithelial neoplasms = 4% of lacrimal gland lesions ACCa most common lacrimal malignancy (50%) 1121 Diagnostic Imaging Head and Neck Natural History & Prognosis Low grade: Good prognosis following local resection High grade: High incidence of local and distant recurrences, particularly in ACCa Disease-free survival rate 50% at 10 years for ACCa Treatment Primarily surgical, ranging from local resection to exenteration ± bone removal Adjuvant radiation therapy for high-grade lesions DIAGNOSTIC CHECKLIST Image Interpretation Pearls Perineural spread is important feature of ACCa, the most common lacrimal carcinoma SELECTED REFERENCES Vaidhyanath R et al: Lacrimal fossa lesions: pictorial review of CT and MRI features Orbit 27(6):410-8, 2008 Jung WS et al: The radiological spectrum of orbital pathologies that involve the lacrimal gland and the lacrimal fossa Korean J Radiol 8(4):336-42, 2007 Part V - Skull Base Section - Skull Base Lesions Introduction and Overview Skull Base Overview > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Introduction and Overview > Skull Base Overview Skull Base Overview H Christian Davidson, MD Imaging Approaches and Indications CT is the primary imaging tool for evaluating the bony details of the skull base (SB) Multislice CT scanners allow thin slices (≤ mm) and provide excellent multiplanar reformatted images These function as the mainstay for evaluating bony changes associated with SB diseases as well as providing evidence for calcific or bony matrices of these lesions MR is an essential partner to bone CT in evaluating SB lesions as it provides the best understanding of lesion soft tissue extent T1 pre-contrast images show lesion margins against the contrast of skull base marrow fat T1 also reveals high signal subacute blood & intralesion high-velocity flow voids to best advantage Enhanced, fat-saturated T1 sequences define enhancement characteristics of the lesion in question GRE may show blooming if hemorrhage or venous sinus thrombosis is present DWI hyperintensity in a focal SB lesion suggests the diagnosis of epidermoid MRA & MRV are important sequences to acquire if internal carotid & vertebral artery or venous sinus involvement is suspected Imaging Anatomy The SB is made up of bones: The paired frontal and temporal bones and the unpaired ethmoid, sphenoid, and occipital bones Two major surfaces of the SB can be described: The endocranial surface, which faces the brain, cisterns, cranial nerves (CN), & intracranial vessels, and the exocranial surface, which faces the extracranial H&N The exocranial surface anteriorly interfaces with the sinus, nose, and orbits, centrally with the masticator (MS), parotid (PS), parapharyngeal, and anterior pharyngeal mucosal spaces (PMS), and posteriorly with the carotid (CS), retropharyngeal (RPS), perivertebral (PVS), & posterior PMS The endocranial surface can be further divided into regions: The anterior, central, & posterior SB The anterior SB (ASB) is the floor of the anterior cranial fossa It is comprised of the orbital plate of the frontal bone, ethmoid bone cribriform plate & ethmoid sinus roof, & the planum sphenoidale & lesser wing (LWS) of the sphenoid bone Important ASB foramina include the foramen cecum (FC) & the cribriform plate foramina The central SB (CSB) is the floor of the middle cranial fossa It is made up of the basisphenoid, greater wing of the sphenoid bone (GWS), & the temporal bone (T-bone) anterior to the petrous ridge Bony landmarks of the CSB include the sella turcica, tuberculum sellae, & the posterior clinoid process Important CSB foramina & fissures are the optic canal, superior orbital fissure (SOF), inferior orbital fissure (IOF), foramen rotundum, foramen ovale, foramen spinosum, vidian canal, carotid canal, & foramen lacerum The posterior SB (PSB) is the bony bowl that makes up the floor of the posterior cranial fossa The PSB is made up of the posterior wall of the T-bone & the occipital bone The occipital bone has parts: The basilar part (lower clivus/basiocciput), the condylar part lateral to the foramen magnum, including the occipital condyles, & the squamous part (large bony plate posterosuperior to foramen magnum) Important PSB foramina & 1122 Diagnostic Imaging Head and Neck fissures include the internal auditory canal (IAC), jugular foramen, hypoglossal canal, stylomastoid foramen, & foramen magnum Skull Base Foramina/Fissures & Contents Anterior skull base Foramen cecum: Midline, anterior to crista galli Embryologic remnant of anterior neuropore, which normally involutes in early childhood Cribriform plate foramina: Roof of nasal cavity Transmits afferent fibers from nasal mucosa to the olfactory bulbs of CN1 Central skull base Optic canal: Medial LWS Transmits CN2 to globe, dura, arachnoid & pia, CSF, ophthalmic artery SOF: Between LWS & GWS Transmits CN3, CN4, CN6, CNV1, & superior ophthalmic vein IOF: Cleft between maxilla body & GWS Transmits inferior orbital artery, vein, & nerve Foramen rotundum: Conduit to pterygopalatine fossa (PPF) within sphenoid bone superolateral to vidian canal Transmits CNV2 to PPF, artery of foramen rotundum, emissary veins from cavernous sinus to pterygoid plexus Foramen ovale: Within GWS Conduit to masticator space Transmits CNV3 into masticator space, lesser petrosal nerve, & accessory meningeal branch of internal maxillary artery Foramen spinosum: Within GWS posterolateral to foramen ovale Transmits middle meningeal artery & vein and recurrent branch of CNV3 Vidian canal: Inferolateral to foramen rotundum within GWS Connects foramen lacerum to PPF Transmits vidian nerve & artery Carotid canal: In T-bone & GWS Transmits petrous (C2) & lacerum (C3) segments of internal carotid artery (ICA) and sympathetic plexus Foramen lacerum: Pseudoforamen; cartilaginous floor of lacerum ICA segment Posterior skull base IAC: In posterior wall of T-bone Opening called porus acusticus Transmits CN7, CN8, & labyrinthine artery Jugular foramen (JF): Cleft between temporal & occipital bones with parts (pars nervosa & vascularis) Pars nervosa transmits CN9 into CS, Jacobsen nerve, inferior petrosal vein Pars vascularis transmits CN10, CN11, Arnold nerve, posterior meningeal artery, jugular bulb Hypoglossal canal: Found with condylar occipital bone inferomedial to JF Transmits CN12 into CS Stylomastoid foramen: Exocranial surface of T-bone between medial mastoid tip & styloid process Transmits CN7 into parotid space Foramen magnum: Occipital bone inferior ring Transmits medulla oblongata, vertebral arteries, & CN11 (ascending spinal component) Embryology ASB embryology is key to understanding disease in this area (anterior neuropore anomaly, cephalocele, nasal glioma) The prenasal space is a transient prenatal region separating nasal bones & cartilaginous nasal capsule The anterior neuropore extends from intracranial space to P.V(1):3 prenasal space & briefly contacts skin at the bridge of the nose but involutes prior to birth The prenasal space reduces to a small canal anterior to the crista galli called the foramen cecum The newborn FC diameter is ˜ mm The FC should be completely ossified by years of age As the ASB originates largely from cartilaginous precursors, the process of ossification can be confusing on imaging The ASB ossifies from posterior to anterior and lateral to medial At birth the ASB is composed of cartilage, which progressively ossifies Ossification of the crista galli and cribriform plate begins at months and is nearly complete by 24 months The crista galli contains fat at about 12 months (don't call it a dermoid!) The area of the FC ossifies last, reaching its adult configuration by years (don't overcall an anterior neuropore anomaly!) The CSB forms from ˜ 24 ossifications centers Major centers include the presphenoid (planum sphenoidale), postsphenoid (basisphenoid containing sella, dorsum, sphenoid sinus), alisphenoid (GWS), and orbitosphenoid (LWS) The sphenooccipital synchondrosis lies between the basisphenoid & basiocciput It is the site of most postnatal SB growth and one of the last sutures to fuse (completed by age 20 years) Persistence of the craniopharyngeal canal (remnant of Rathke pouch) may occur between the presphenoid & basisphenoid Persistence of the median basal canal may be seen between the basioccipital ossification centers Approaches to Skull Base Imaging Issues Creating skull base lesion DDx can be difficult because some lesions can occur anywhere along the SB Understanding the DDx list of the lesions that can occur anywhere in the SB is essential Adding this group to a site-specific DDx can yield a near complete set of possible lesions to be considered ASB, CSB, PSB DDx lists can be constructed The CSB can 1123 Diagnostic Imaging Head and Neck be further refined into shorter site-specific DDx lists for the sella, clivus, petrooccipital fissure, and Meckel cave The PSB has one important site-specific DDx for the jugular foramen Knowledgeable reports about SB lesions require the radiologist to understand the interface relationships between the SB & the extracranial H&N The ASB sits atop the frontal & ethmoid sinuses, orbit, & nose Many of the ASB lesions originate in these structures The CSB resides superior to the MS, PS, & PMSs Nasopharyngeal carcinoma directly accesses the intracranial compartment via the foramen lacerum (perivascular spread) MS & PS space malignancies may reach the intracranial compartment via perineural spread along CNV3 & CN7, respectively The PSB directly interacts with the CS, RPS, & PVSs When JF lesions exit the skull base inferiorly, they plunge directly into the nasopharyngeal CS Without a clear understanding of perineural tumor (PNT) SB spread, the radiologist may not identify this key imaging finding PNT from PS malignancy enters the stylomastoid foramen & climbs the CN7 mastoid segment MS malignancy CNV3 PNT traverses the foramen ovale on its way to Meckel cave Cheek skin, palate, sinus, or orbit carcinoma can access CNV2 via the infraorbital nerve or PPF, following CNV2 through the foramen rotundum into the middle cranial fossa PPF malignancy may also show PNT spread via the vidian nerve to the foramen lacerum PNT also connects between CN5 & CN7 along the greater superficial petrosal nerve on the superior ridge of the petrous T-bone Selected References Borges A: Skull base tumours part I: imaging technique, anatomy and anterior skull base tumours Eur J Radiol 66(3):338-47, 2008 Borges A: Skull base tumours Part II Central skull base tumours and intrinsic tumours of the bony skull base Eur J Radiol 66(3):348-62, 2008 Tables Skull Base Differential Diagnosis: Tumors & Tumor-Like Lesions by Site Skull Base, Anterior, Central, or Posterior Meningioma Giant cell tumor Hemangiopericytoma Metastases Multiple myeloma Plasmacytoma Osteosarcoma Rhabdomyosarcoma, parameningeal Langerhans cell histiocytosis Tumor-like lesions Fibrous dysplasia Paget disease Idiopathic inflammatory pseudotumor Anterior Skull Base Mucocele, SN Osteoma, SN Esthesioneuroblastoma, N Squamous cell carcinoma, SN Non-Hodgkin lymphoma, SN or O SN = sinonasal; N = nasal; O = orbit P.V(1):4 Image Gallery 1124 Melanoma, N Lacrimal gland carcinoma, O Central Skull Base Sella: Pituitary macroadenoma Clivus: Chordoma, ecchordosis physaliphora Petrooccipital fissure: Chondrosarcoma Meckel cave: Trigeminal schwannoma T-bone: Tumor Endolymphatic sac tumor T-bone: Tumor-like lesions Acquired cholesteatoma Congenital cholesteatoma Cholesterol granuloma Posterior Skull Base Clivus (occipital bone): Chordoma Jugular foramen Glomus jugulare paraganglioma Jugular foramen schwannoma Jugular foramen meningioma Hypoglossal canal: Hypoglossal schwannoma Diagnostic Imaging Head and Neck (Top) Schematic graphic of skull base shows many ossification centers Between ossification centers of presphenoid is cartilaginous gap called olivary eminence, which is obliterated shortly after birth In the midline, note the craniopharyngeal canal, sphenooccipital synchondrosis, and the median basal canal The sphenooccipital synchondrosis fuses over the first 15 years of life while the craniopharyngeal and median basal canals are rarely persistent into childhood When persistent, these two canals can rarely be the source of meningitis (Bottom) Graphic of skull base viewed from below shows the relationship of spaces of the suprahyoid neck to the skull base Four spaces have key interactions with skull base: Masticator, parotid, carotid, and pharyngeal mucosal spaces Parotid space (green) malignancy can follow CN7 into stylomastoid foramen Masticator space (purple) receives CNV3 while CN9-12 enter the carotid space (red) The pharyngeal mucosal space abuts the foramen lacerum, which is covered by fibrocartilage in life P.V(1):5 Image Gallery 1125 Diagnostic Imaging Head and Neck (Top) Graphic of anterior skull base seen from above shows olfactory bulb of CN1 lying on cribriform plate Neural structures have been removed on right, allowing visualization of numerous perforations in the cribriform plate, through which afferent fibers from olfactory mucosa pass to form the olfactory bulb The posterior margin of the anterior skull base is formed by the lesser wing of sphenoid & planum sphenoidale Note the foramen cecum, a small pit anterior to the crista galli, bounded anteriorly by frontal bone, posteriorly by ethmoid bone If the anterior neuropore persists, an enlarged foramen cecum, bifid crista galli, and epidermoid along the neuropore tract are possible (Bottom) Sagittal graphic of anterior skull base during development shows ossification of chondrocranium proceeding from posterior to anterior The prenasal space is now encased in bone & has become the foramen cecum A normal stalk of dura extends through foramen cecum to skin (anterior neuropore) P.V(1):6 Image Gallery 1126 Diagnostic Imaging Head and Neck (Top) Graphic of central skull base from above shows important nerves on left and the numerous fissures & foramina on the right The greater wing of the sphenoid bone forms anterior wall of middle cranial fossa The posterior limit of central skull base is dorsum sella medially & petrous ridge laterally (Bottom) Coronal graphic shows the important anatomy of the central skull base/sphenoid bone The cavernous portions of the internal carotid arteries lie lateral & posterior to the sinuses At the orbital apex, the optic nerve can be seen traversing the optic canal Multiple cranial nerves pass through the superior orbital fissure into the orbit, including CNs 3, 4, & as well as the ophthalmic division on CN5 The maxillary division of CN5 in foramen rotundum & the vidian nerve are positioned lateral & inferior to the sinus, respectively P.V(1):7 Image Gallery 1127 Diagnostic Imaging Head and Neck (Top) Graphic shows the posterior skull base as seen from above The neural structures are shown on the left while the bony landmarks are seen on the right The anterior boundary of posterior skull base is clivus medially and petrous ridge laterally The major foramina are the foramen magnum, porus acusticus, jugular foramen, and hypoglossal canal Notice that the jugular foramen connects anteriorly with the petrooccipital fissure (Bottom) Graphic of the posterior skull base shows the major dural venous sinuses and jugular foramen from above The midbrain and pons as well as the left half of the tentorium cerebelli have been removed Notice the transverse sinus is in the wall of the occipital bone while the sigmoid sinus is in the medial wall of the temporal bone The two portions of the jugular foramen are also visible The anterior pars nervosa receives the glossopharyngeal nerve (CN9), while the pars vascularis has the vagus (CN10) & accessory (CN11) nerves passing through it Clivus Ecchordosis Physaliphora > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Clivus > Ecchordosis Physaliphora 1128 Diagnostic Imaging Head and Neck Ecchordosis Physaliphora C Douglas Phillips, MD, FACR Key Facts Terminology Benign nodule of tissue in prepontine cistern dorsal to clivus considered to be ectopic notochordal remnant Imaging CT: Prepontine intradural mass connected by osseous stalk or pedicle to clivus May have associated well-marginated scalloped lesion of clivus with sclerotic margins MR: Provides best depiction of lesion, stalk, and intradural component Uniformly T2 hyperintense Clival component hypointense compared to normal marrow Restricted diffusion often noted Lack of enhancement differentiates from chordoma Top Differential Diagnoses Chordoma Skull base metastasis Dermoid or epidermoid Arachnoid cyst Pathology Few clear cells (“physaliphorous cells”) surrounded by chondromyxoid stroma Clinical Issues Asymptomatic & usually found incidentally on head MR Found in 2% of autopsies & 1.6% of MR studies Indolent lesion, which does not appear to grow Typically not managed surgically unless significant brainstem compression or symptoms are present (Left) Sagittal T1WI MR in an asymptomatic patient shows a hypointense mass in the prepontine cistern The lesion deforms the ventral surface of pons This case of EP is slightly higher in signal than CSF on this sequence, similar to the appearance of an epidermoid (Right) Axial T1WI C+ MR in the same patient demonstrates no enhancement of the lesion in prepontine cistern Mild ventral deformity of pons is evident The lesion is slightly hyperintense to CSF 1129 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows well-marginated lytic lesion of the clivus with sclerotic borders This lesion extended to the carotid canal although carotid artery was normal No intradural component is appreciated on this CT (Right) Axial T2WI MR in the same patient shows hyperintense T2 signal with internal septations and demonstrates slight extension into the prepontine cistern adjacent to basilar artery A normal internal carotid artery flow void is evident P.V(1):9 TERMINOLOGY Abbreviations Ecchordosis physaliphora (EP) Definitions Small gelatinous nodule of tissue considered to be ectopic notochordal remnant IMAGING General Features Best diagnostic clue Well-defined lesion of clivus with prepontine intradural mass connected by stalk or pedicle to clival lesion Location Prepontine cistern along dorsal midline clivus; occasionally paramedian Morphology Well defined, lobular ± stalk Imaging Recommendations Best imaging tool MR provides best depiction of lesion, stalk, and intradural component Protocol advice Sagittal (T1 & T2) images best for identifying osseous stalk attaching lesion to clivus CT Findings NECT CT may not identify intradural component (similar density to CSF) CECT No appreciable enhancement Bone CT Variable osseous stalk or pedicle connecting basisphenoid portion of clivus to intradural component Well-marginated scalloped clival component with sclerotic margins MR Findings T1WI Intradural component may be nearly isointense to CSF Intraclival component (if present) hypointense compared to normal clivus marrow T2WI Uniformly hyperintense in most cases 1130 Diagnostic Imaging Head and Neck DWI Restricted diffusion often noted T1WI C+ No enhancement noted (differentiates from chordoma) DIFFERENTIAL DIAGNOSIS Clivus Chordoma Malignant clival mass that typically remains extradural Always enhances; destroys bone Aggressive & symptomatic Skull Base Metastasis Multiple lesions, enhancement more common Intradural component less likely Dermoid and Epidermoid Rarely located in clivus but may closely resemble imaging characteristics No osseous stalk or intradural component More common in CPA cistern Arachnoid Cyst Rarely retroclival in location Follows CSF density/signal exactly PATHOLOGY General Features Etiology Benign congenital malformation arising from ectopic notochordal tissue Gross Pathologic & Surgical Features Small, somewhat cystic or gelatinous mass, which is intradural and attached to clivus by stalk Microscopic Features Few clear cells (“physaliphorous cells”) surrounded by chondromyxoid stroma CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic lesion often found incidentally on head MR Other signs/symptoms Rare brainstem compressive symptoms, pontine hemorrhage, CSF fistulae with rhinorrhea Demographics Epidemiology Found in 2% of autopsies & 1.6% of MR studies Natural History & Prognosis Indolent lesion, which does not appear to grow Treatment Typically not managed surgically unless significant brainstem compression or symptoms are present DIAGNOSTIC CHECKLIST Image Interpretation Pearls Identification of stalk arising from clivus with intradural extension of lesion into prepontine cistern is characteristic SELECTED REFERENCES Srinivasan A et al: Case 133: Ecchordosis physaliphora Radiology 247(2):585-8, 2008 Mehnert F et al: Retroclival ecchordosis physaliphora: MR imaging and review of the literature AJNR Am J Neuroradiol 25(10):1851-5, 2004 Invasive Pituitary Macroadenoma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Clivus > Invasive Pituitary Macroadenoma Invasive Pituitary Macroadenoma C Douglas Phillips, MD, FACR Key Facts Terminology Invasive, benign pituitary adenoma with inferior extension into skull base Imaging Multiplanar gadolinium-enhanced MR is imaging modality of choice Central skull base mass contiguous with soft tissue in sella Sella expanded or inferior cortex is destroyed 1131 Diagnostic Imaging Head and Neck Variable enhancement (moderate to intense) Dural “tail” may mimic meningioma Look for extension into cavernous sinus Top Differential Diagnoses Clival chordoma Skull base meningioma Skull base metastasis Petrooccipital chondrosarcoma Skull base plasmacytoma Clinical Issues Mean age at presentation ≈ 40 years If hormone secreting, symptoms depend on which hormone secreted 25% visual field defect or other cranial nerve palsy Treatment: Multimodality therapy required for best outcome Surgery often indicated for decompression of optic apparatus Resection often incomplete & leads to recurrences ↑ morbidity due to proximity to vital structures Diagnostic Checklist Look at sagittal images for normal pituitary gland & if absent, invasive adenoma should be at top of DDx (Left) Sagittal T1WI MR shows an invasive pituitary adenoma extending inferiorly into the clivus and replacing normal clival fat The mass also invades the sphenoid sinus and posterior nasal cavity The normal pituitary gland is not visualized (Right) Coronal T1WI C+ FS MR shows an adenoma with invasion of the right cavernous sinus with encasement of the carotid artery Residual normal enhancing pituitary gland is seen superior to the invasive adenoma 1132 Diagnostic Imaging Head and Neck (Left) Coronal bone CT through the central skull base shows expansion of the sella with erosion of its floor and lateral margins by an invasive macroadenoma (Right) Axial bone CT of a large invasive pituitary adenoma shows irregular permeation of central skull base The medial aspects of both petrous ICA canals are eroded , and the mass extends to the basiocciput with cortical thinning of the inferior clivus The mass also extends inferiorly and anteriorly into left nasal cavity P.V(1):11 TERMINOLOGY Definitions Invasive benign pituitary macroadenoma with inferior extension into skull base IMAGING General Features Best diagnostic clue Mass invading central skull base contiguous with soft tissue mass in sella Size Generally > cm CT Findings NECT Ill-defined soft tissue mass centered in sella with invasion of surrounding bone & soft tissue Hemorrhage in 10%; calcification in 2% MR Findings T1WI Sellar & infrasellar mass typically isointense to gray matter T2WI Variable signal on long TR images T1WI C+ Intense, heterogeneous enhancement Dural “tail” may be seen & mimic meningioma May extend into cavernous sinus Imaging Recommendations Best imaging tool Multiplanar gadolinium-enhanced MR DIFFERENTIAL DIAGNOSIS Clival Chordoma Midline clival mass ↑ T2 signal characteristic Skull Base Meningioma Centered along lateral margin of cavernous sinus or tentorium Avidly enhancing ± dural “tail,” tumoral Ca+ Skull Base Metastasis 1133 Diagnostic Imaging Head and Neck Destructive mass that can be anywhere in skull base Knowledge of primary tumor essential (breast & lung most common) Chondrosarcoma (Petrooccipital Fissure) Centered along lateral margin of clivus in petrooccipital fissure Chondroid calcifications (50%) Skull Base Plasmacytoma T2 signal is low to intermediate > 50% have concurrent multiple myeloma PATHOLOGY General Features Etiology Hypothesis for pituitary tumor formation Hypophysiotrophic hormone excess, suppressive hormone insufficiency, or growth factor excess → hyperplasia Hyperplasia predisposes to genetic instability → cell transformation → adenoma formation Staging, Grading, & Classification Radioanatomical classification of adenomas Stage I: Microadenoma < cm without sellar expansion Stage II: Macroadenoma ≥ cm & may extend above sella Stage III: Macroadenoma with enlargement & invasion of floor or suprasellar extension Stage IV: Destruction of sella Histologic criteria Microscopic Features Monotonous sheets of uniform cells CLINICAL ISSUES Presentation Most common signs/symptoms Pituitary hormonal abnormality (symptoms depend on which hormone secreted) Other signs/symptoms 25% visual field defect or other cranial nerve palsy Demographics Age Mean age at presentation ≈ 40 years Epidemiology Pituitary adenoma: 15% of intracranial tumors Invasive adenomas account for 35% of all pituitary neoplasms Natural History & Prognosis Adenomas typically slow growing More than 1/3 behave in more aggressive manner with high recurrence rate Treatment Multimodality therapy and long-term follow-up required for best outcome Surgical resection is treatment of choice if possible Surgery often followed by radiation ± chemotherapy DIAGNOSTIC CHECKLIST Image Interpretation Pearls Look at sagittal images for normal pituitary gland; if absent, invasive adenoma should be at top of DDx SELECTED REFERENCES Hornyak M et al: Multimodality treatment for invasive pituitary adenomas Postgrad Med 121(2):168-76, 2009 Nakasu Y et al: Tentorial enhancement on MR images is a sign of cavernous sinus involvement in patients with sellar tumors AJNR Am J Neuroradiol 22(8):1528-33, 2001 Chordoma Key Facts Terminology Rare, locally aggressive tumor of clivus arising from cranial end of primitive notochord remnant Imaging Location: Clivus; spheno-occipital synchondrosis Can occur anywhere along primitive notochord CT findings 1134 Diagnostic Imaging Head and Neck Midline, expansile, multilobulated well-circumscribed mass Lytic bone destruction with intratumoral Ca++ Variable enhancement MR findings T1: Intermediate to low signal ≈ brain T2: Classically ↑ ↑ signal T1WI C+: Moderate to marked enhancement Top Differential Diagnoses Invasive pituitary macroadenoma Skull base chondrosarcoma Skull base plasmacytoma Skull base metastasis Skull base meningioma Clinical Issues 35% of all chordomas arise in skull base Commonly symptoms: Headache & diplopia (CN 6) Most common age = 30-50 years M:F = 2:1 Treatment Surgical resection (conventional surgery vs endonasal transclival resection) Proton beam RT: Post-op & unresectable tumors (Left) Sagittal graphic shows an expansile, destructive mass originating from clivus, “thumbing” pons & elevating the pituitary gland Note bone fragments floating in chordoma (Right) Sagittal T1 MR correlative image shows near complete involvement of the clivus with expansile low signal tumor and the classic “thumb” of chordoma focally compressing the pons Note multiple foci of high signal consistent with intratumoral hemorrhage, calcification, or mucinous material 1135 Diagnostic Imaging Head and Neck (Left) Sagittal T1WI C+ MR shows classic expansile clival chordoma Note the normal pituitary gland ruling out an aggressive pituitary lesion Although chordomas classically significantly enhance on MR, mild enhancement can also be seen (Right) Axial T1WI C+ MR in the same patient shows extension into the left cavernous sinus encasing the ICA Angiographic balloon occlusion testing of the left ICA may be warranted should surgery be considered in this patient P.V(1):13 TERMINOLOGY Abbreviations Clival chordoma (CCh) Synonyms Basicranial chordoma Definitions Rare, locally aggressive tumor of clivus arising from cranial end of primitive notochord remnant IMAGING General Features Best diagnostic clue Destructive, expansile, midline clival mass with ↑ T2 signal Location Can occur anywhere along primitive notochord Clivus near spheno-occipital synchondrosis Commonly found in midline from sella to coccyx Other rare locations in head & neck Sellar region, sphenoid sinus, nasopharynx, maxilla, & paranasal sinuses Size Usually 2-5 cm at presentation Morphology Expansile, multilobulated, well-circumscribed mass Expanding tumor invades or displaces local structures Cavernous sinuses & sella superiorly Jugular foramen & petrous apex laterally Basilar artery & brainstem posteriorly Basisphenoid, sphenoid, & posterior ethmoid sinuses anteriorly Nasopharynx anteroinferiorly Jugular foramen & foramen magnum posteroinferiorly CT Findings NECT Centrally located, well-circumscribed, expansile soft tissue mass Hyperdense relative to adjacent neural axis CECT 1136 Diagnostic Imaging Head and Neck Variable enhancement May contain low-attenuation areas representing myxoid/gelatinous material Bone CT Mass causes lytic bone destruction Intratumoral Ca++ = sequestra from destroyed bone > dystrophic Ca++ MR Findings T1WI Intermediate to low signal compared to brain ↓ tumor signal easily distinguished from adjacent fatty marrow Small foci ↑ signal - hemorrhage or mucoid material Tumor “thumb” indents anterior pons on sagittal images T2WI Classically ↑ T2 signal Secondary to high fluid content Foci of ↓ signal from calcification, hemorrhage, & mucoid ↓ signal septations can separate ↑ signal lobules T2* GRE Foci of hemorrhage ↓ signal T1WI C+ Moderate to marked enhancement “Honeycomb” enhancement pattern secondary to intratumoral areas of low signal intensity Subtle or no enhancement reflects necrosis ± ↑ volume mucinous material MRA Vessel encasement/displacement frequent Arterial narrowing rare; therefore, MRA less useful than MR Angiographic Findings Avascular mass Propensity to displace & encase internal carotid arteries and vertebrobasilar system Angiography better evaluates degree of luminal narrowing Balloon test occlusion evaluates risk of neurologic impairment with vessel sacrifice Imaging Recommendations Best imaging tool MR without and with contrast Protocol advice Focused enhanced MR of skull base Thin section axial & coronal CT of skull base (or axial only with coronal ± sagittal reformations) DIFFERENTIAL DIAGNOSIS Invasive Pituitary Macroadenoma Originates in sella & involves pituitary gland Extends into sphenoid sinus, not prepontine cistern Skull Base Chondrosarcoma Arises off midline at petro-occipital fissure Similar T1 & T2 characteristics to CCh Chondroid calcifications more common Skull Bases Plasmacytoma Can be midline destructive mass of clivus T2 signal usually intermediate to low Skull Base Metastasis Destructive lesion; extraosseous component < CCh Known primary neoplasm Skull Base Meningioma Sclerosis/hyperostosis of adjacent bone Homogeneous enhancement with “dural tails” Commonly causes narrowing of encased vessels PATHOLOGY General Features Etiology Arises from remnants of primitive notochord Genetics 1137 Diagnostic Imaging Head and Neck Familial chordoma rarely reported P.V(1):14 Staging, Grading, & Classification histopathologic subtypes Typical (classic) chordoma & chondroid chordoma Gross Pathologic & Surgical Features Gross appearance: Multilobulated, gelatinous, gray mass Microscopic Features Classic chordoma: Cords of physaliphorous cells with areas of necrosis, hemorrhage, & entrapped bone Physaliphorous cells confirms diagnosis Large cell containing mucin & glycogen vacuoles with “bubbly” appearance to cytoplasm Chondroid chordoma: Stroma resembles hyaline cartilage with neoplastic cells in lacunae Term “chondroid” in chondroid chordoma is misnomer; refers to histologic mimic Lesion does not contain true cartilage or cells of cartilage origin Classic & chondroid chordomas immunopositive for epithelial markers (cytokeratin & epithelial membrane antigen Compared to chondrosarcoma, which is negative for those markers CLINICAL ISSUES Presentation Most common signs/symptoms Headaches & diplopia (CN 6) Other signs/symptoms Ophthalmoplegia results from tumor proximity to cranial nerves Cranial nerves 3, 4, & in cavernous sinus CN6 in Dorello canal Visual loss (optic nerve, chiasm, optic tracts involved) Facial pain (CN V2) Lateral growth can injure CN7 or in CPA-IAC Large chordoma may reach jugular foramen inferolaterally affecting CN9-12 Headache likely related to stretching of dura Clinical profile Adult with gradual onset of ophthalmoplegia & headache Demographics Age 30-50 years old Can occur at any age Gender M:F = 2:1 Ethnicity Caucasians > African-Americans Epidemiology 35% of all chordomas arise in skull base 50% are sacrococcygeal 15% arise from vertebral body Natural History & Prognosis Begins as expansile destructive bone lesion Infiltrates/transgresses dura, encases CN & vessels, & compresses brain/brainstem Rarely begin intradural/intracranial Better prognosis if young age presentation Chondroid chordoma has better prognosis than classic chordoma Poorer 5-year survival than chondrosarcoma Poorer prognosis in women, necrotic tumors by imaging & volume > 70 mL Local recurrence is common despite combined therapy Rarely tumor recurrence along surgical pathway Distant metastasis rare: Lymph nodes, bone, lung, liver Distant metastases more common in recurrent CCh “Drop” metastasis with subarachnoid seeding rare 1138 Diagnostic Imaging Head and Neck Treatment Surgical resection (conventional surgery vs endonasal transclival resection) Complete excision difficult due to close proximity of critical structures Significant occipital condyle extension may require surgical fusion & instrumentation Proton beam RT: Post-op & unresectable tumors DIAGNOSTIC CHECKLIST Consider Destructive midline mass originating from clivus hyperintense on T2 is most common presentation Image Interpretation Pearls T1WI C+ MR best demonstrates tumor characteristics & extent Bone CT can better characterize bony destruction Look for encasement of ICA & vertebrobasilar system Reporting Tips Comment on involvement of adjacent vital structures SELECTED REFERENCES Fraser JF et al: Endoscopic endonasal transclival resection of chordomas: operative technique, clinical outcome, and review of the literature J Neurosurg 112(5):1061-9, 2010 Ares C et al: Effectiveness and safety of spot scanning proton radiation therapy for chordomas and chondrosarcomas of the skull base: first long-term report Int J Radiat Oncol Biol Phys 75(4):1111-8, 2009 Stippler M et al: Endoscopic endonasal approach for clival chordomas Neurosurgery 64(2):268-77; discussion 2778, 2009 Takahashi S et al: Skull base chordomas: efficacy of surgery followed by carbon ion radiotherapy Acta Neurochir (Wien) 151(7):759-69, 2009 Nguyen QN et al: Emerging role of proton beam radiation therapy for chordoma and chondrosarcoma of the skull base Curr Oncol Rep 10(4):338-43, 2008 Yoneoka Y et al: Cranial base chordoma—long term outcome and review of the literature Acta Neurochir (Wien) 150(8):773-8; discussion 778, 2008 Almefty K et al: Chordoma and chondrosarcoma: similar, but quite different, skull base tumors Cancer 110(11):2457-67, 2007 Géhanne C et al: Skull base chordoma: CT and MRI features JBR-BTR 88(6):325-7, 2005 Erdem E et al: Comprehensive review of intracranial chordoma Radiographics 23(4):995-1009, 2003 P.V(1):15 Image Gallery (Left) Axial graphic illustrates a large clival chordoma pushing posteriorly to indent the low pons & basilar artery Basi-sphenoid invasion is also seen lifting pituitary gland in the sella (Right) Axial NECT demonstrates a typical midline clival chordoma with irregular posterior intratumoral calcifications These may represent associated matrix calcifications &/or bone fragments This tumor compresses the pons posteriorly 1139 Diagnostic Imaging Head and Neck (Left) Axial T2WI MR in the same patient shows the mass displaying characteristic marked, diffuse hyperintensity with an internal matrix Notice right posterolateral displacement of the basilar artery and compression of the pons without parenchymal edema from this slow-growing tumor (Right) Coronal T1WI MR in the same patient shows focal areas of T1 shortening within the mass consistent with calcification, hemorrhage, &/or mucoid degeneration (Left) Sagittal T1WI MR demonstrates a chordoma involving the lower portion/basiocciput of the clivus This expansile tumor shows significant inferior extension (Right) Axial T2WI MR in the same patient shows extensive T2 hyperintense clival tumor involving the occipital bone The marked hyperintense T2 signal on this sequence is a classic feature of chordoma Surgical excision in such a case would also require stabilization of the craniocervical junction Sphenoid Bone Persistent Craniopharyngeal Canal > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Sphenoid Bone > Persistent Craniopharyngeal Canal Persistent Craniopharyngeal Canal C Douglas Phillips, MD, FACR Key Facts Terminology Persistent craniopharyngeal canal (PCPC) 1140 Diagnostic Imaging Head and Neck Synonyms: Transsphenoidal canal, craniopharyngeal duct, hypophyseal canal, basipharyngeal canal, persistent hypophyseal canal Developmental anomaly with persistent tract from nasopharynx to pituitary fossa Thought to be persistence of Rathke duct Imaging Skull base bone CT Midline, well-marginated tract from sella to roof of nasopharynx Anterior to sphenooccipital synchondrosis Typically < 1.5 mm in diameter Multiplanar MR Smoothly marginated cylindrical “canal” extending from sella to nasopharynx Variable signal intensity in canal itself Coronal sections demonstrate adenohypophysis sitting on superior aspect of craniopharyngeal canal like “ball on a tee” MR best to evaluate pituitary and suprasellar structures for associated abnormality Top Differential Diagnoses Skull base cephalocele Sphenobasilar synchondrosis Persistent medial basal canal Clinical Issues Typically incidental finding Seen in 0.42% of population Usually obliterated by 12th week of gestation “Leave alone” lesion when isolated finding (Left) Sagittal T1WI C+ MR demonstrates persistent craniopharyngeal canal projecting inferiorly from sellar floor to bony roof of nasopharynx Sphenooccipital synchondrosis is posterior to craniopharyngeal canal (Right) Coronal T1WI C+ MR demonstrates pituitary gland superior to a persistent craniopharyngeal canal like a “ball on a tee.” The inferior aspect of the canal is noted in bony roof of nasopharynx deep to adenoidal soft tissues 1141 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a young child shows well-defined sclerotic ovoid “lesion” in the sphenoid bone , consistent with the midsegment of a persistent craniopharyngeal canal This smooth canal was incomplete, terminating above the nasopharynx (Right) Axial T1WI C+ MR demonstrates persistent craniopharyngeal canal as midline round defect in the sphenoid bone This fat-containing canal is hyperintense on T1 MR and has hypointense rim of sclerosis P.V(1):17 TERMINOLOGY Abbreviations Persistent craniopharyngeal canal (PCPC) Synonyms Transsphenoidal canal, craniopharyngeal duct, hypophyseal canal, basipharyngeal canal, persistent hypophyseal canal Definitions Developmental anomaly with persistent tract from nasopharyngeal roof to pituitary fossa Most believe it to be persistence of Rathke duct Alternative hypothesis: Persistent vascular channel unrelated to Rathke duct IMAGING General Features Best diagnostic clue Midline well-marginated cylindrical to ovoid tract from sella to nasopharyngeal roof Location Extends between superior surface of nasopharynx to floor of sella turcica in oblique fashion Terminates in nasopharynx near junction of vomer & sphenoid rostrum Lies anatomically between presphenoid and basisphenoid Anterior to sphenooccipital synchondrosis Size Typically < 1.5 mm in diameter When larger, evaluate carefully for associated pituitary abnormality Morphology Tubular canal May be incomplete, ending blindly without communication with sella Imaging Recommendations Best imaging tool High-resolution skull base CT Multiplanar MR best to exclude pituitary abnormality or cephalocele Protocol advice Sagittal and coronal CT reconstructions demonstrate connections to sella & nasopharynx CT Findings Bone CT Smoothly marginated cylindrical-to-ovoid midline bony “canal” extending from sella to nasopharynx 1142 Diagnostic Imaging Head and Neck Oblique orientation to nasopharynx May rarely contain air if communication with pharyngeal lumen exists MR Findings Smoothly marginated tubular “canal” in sphenoid Variable signal intensity in canal itself Central tissue may demonstrate some mild enhancement on post-contrast T1W images Coronal sections reveal adenohypophysis sitting on superior aspect of craniopharyngeal canal like “ball on a tee” Careful to evaluate pituitary and suprasellar structures for associated abnormality DIFFERENTIAL DIAGNOSIS Skull Base Cephalocele Nasopharyngeal or basioccipital nasopharyngeal cephalocele types in similar location Contain variable meningeal-lined CSF/brain parenchyma Sphenooccipital Synchondrosis Linear cleft between basisphenoid & basiocciput Conspicuity decreases from childhood to adulthood Persistent Medial Basal Canal (Basilaris Medianus) Developmental variant of lower midline clivus Posteroinferior to sphenooccipital synchondrosis PATHOLOGY General Features Associated abnormalities Association of other abnormalities may lead to increased size of craniopharyngeal canal Pituitary abnormalities, cephaloceles, midline craniofacial anomalies Cysts within PCPC CLINICAL ISSUES Presentation Most common signs/symptoms Typically incidental finding Demographics Epidemiology Seen in 0.42% of population Natural History & Prognosis Usually obliterated by 12th week of gestation Rarely reported to cause upper airway obstruction during infancy, CSF leak, meningitis, sinusitis, hydrocephalus Treatment “Leave alone” lesion when isolated finding DIAGNOSTIC CHECKLIST Image Interpretation Pearls Evaluate hypothalamic-pituitary axis for associated abnormality SELECTED REFERENCES Pinilla-Arias D et al: Recurrent meningitis and persistence of craniopharyngeal canal: case report Neurocirugia (Astur) 20(1):50-3, 2009 Ekinci G et al: Transsphenoidal (large craniopharyngeal) canal associated with a normally functioning pituitary gland and nasopharyngeal extension, hyperprolactinemia, and hypothalamic hamartoma AJR Am J Roentgenol 180(1):76-7, 2003 Sphenoid Benign Fatty Lesion > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Sphenoid Bone > Sphenoid Benign Fatty Lesion Sphenoid Benign Fatty Lesion C Douglas Phillips, MD, FACR Key Facts Terminology Synonym: Arrested pneumatization of sphenoid Definition: Well-corticated, fat-containing lesion of sphenoid bone Occurs in regions where primary or accessory pneumatization known to occur Usually adjacent to posterior sinus wall Imaging Bone CT findings Thin section axial images best for depicting uniform cortical bone rim 1143 Diagnostic Imaging Head and Neck Well-defined, low-attenuation (fat density) lesion with sclerotic rim May have occasional curvilinear calcification or soft tissue density MR Can help delineate smaller lesions Central ↑ T1, variable T2, & ↓ T1 signal post fat suppression Hypointense rim Minimal if any enhancement Top Differential Diagnoses Fibrous dysplasia Hemangioma Chordoma Ossifying fibroma Clinical Issues Common incidental finding on CT or MR depicting skull base “Leave me alone” lesion Diagnostic Checklist Identification of internal fat & sclerotic margin is essentially pathognomonic (Left) Axial bone CT shows characteristic features of an incidentally discovered fatty lesion of the sphenoid The lesion bulges into left sphenoid sinus and has well-defined sclerotic margins and predominantly low density (fat) centrally Note normal trabeculae traverse lesion (Right) Sagittal T1WI MR in the same patient demonstrates T1 shortening within the lesion previously shown on CT The lesion followed fat signal intensity on this and all other sequences (Left) Axial bone CT demonstrates another typical benign fatty lesion of the sphenoid 1144 with well-defined margins Diagnostic Imaging Head and Neck and a low-density central component, confirmed on MR to represent fat (Right) Axial T2WI MR in the same patient confirms predominantly hyperintense (paralleling fat) signal with a lobulated contour to the lesion There is no significant distortion of skull base foramina or normal structures, such as petrous segments of internal carotid arteries Central Skull Base Trigeminal Schwannoma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Sphenoid Bone > Central Skull Base Trigeminal Schwannoma Central Skull Base Trigeminal Schwannoma Deborah R Shatzkes, MD Key Facts Terminology Synonyms: Giant TS, “dumbbell” TS Imaging Tubular mass along course of trigeminal nerve Can involve preganglionic (cisternal) segment, Meckel cave, CNV1, CNV2, CNV3 May extend extracranially via CNV exit foramina Size: Small to giant Morphology: “Dumbbell” shape secondary to constriction at porus trigeminus or skull base foramen CT: Soft tissue mass with smooth bony erosion of central skull base, ± foraminal widening MR: T1 iso- to hypointense, T2 hyperintense, variable enhancement Cyst formation is common Top Differential Diagnoses Meningioma CNV3 perineural tumor CNV2 perineural tumor Non-Hodgkin lymphoma Pathology Benign nerve sheath tumor 2nd most common intracranial schwannoma next to vestibular schwannoma May occur in setting of neurofibromatosis Diagnostic Checklist Dumbbell-shaped or tubular mass along course of trigeminal nerve is characteristic Enhanced MR best to identify intracranial and extracranial extent of lesion (Left) Axial T1WI MR shows a well-demarcated dumbbell-shaped mass in the superior left cerebellopontine angle cistern extending anteriorly into Meckel cave An extraaxial location is indicated by widening of the cistern and displacement of the brainstem (Right) Axial T1WI C+ MR reveals a dumbbell-shaped giant TS with a waist formed at the level of the porus trigeminus Extensive cystic components are present Note the normal left Meckel cave containing CSF signal 1145 Diagnostic Imaging Head and Neck (Left) Coronal T2WI FS MR demonstrates a well-demarcated hyperintense giant TS encasing, but not significantly compressing the left internal carotid artery In this location, a waist is formed as the mass extends through the enlarged foramen ovale (Right) Sagittal T1WI C+ MR reveals a “dumbbell” TS affecting the preganglionic and Meckel cave segments of the trigeminal nerve Notice the intramural cyst in the preganglionic segment , common in schwannomas Occipital Bone Hypoglossal Nerve Schwannoma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Occipital Bone > Hypoglossal Nerve Schwannoma Hypoglossal Nerve Schwannoma C Douglas Phillips, MD, FACR Key Facts Terminology Benign tumor of differentiated Schwann cells surrounding CN12 Imaging Multiplanar contrast-enhanced MR with bone CT for delineation of bone margins CT findings Sharply marginated fusiform mass with enlarged HC Coronal plane: Remodeling of undersurface of jugular tubercle Tongue muscle fatty atrophy with fatty replacement MR: Homogeneous, enhancing mass following course of CN12 Cephalad growth toward preolivary sulcus Caudal growth into nasopharyngeal carotid space Top Differential Diagnoses Asymmetric HC venous drainage Skull base metastasis Persistent hypoglossal artery Jugular foramen meningioma Glomus jugulare paraganglioma Pathology Smooth, encapsulated mass arising eccentrically from CN12 Multiple schwannomas are associated with NF2 Clinical Issues Hypoglossal neuropathy results in unilateral tongue denervation Larger lesions may produce multiple lower cranial neuropathies Surgical removal in single operation is curative 1146 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a sharply marginated, enlarged left hypoglossal canal The cortical margins are well maintained Note normal right hypoglossal canal (Right) Axial T1 C+ MR in the same patient reveals a heterogeneously enhancing schwannoma with multiple, large intramural cysts in its intracranial component The portion of the schwannoma in the hypoglossal canal shows more solid enhancement The adjacent medulla & cerebellar hemisphere are compressed (Left) Coronal bone CT shows a markedly expanded hypoglossal canal on the right eroding undersurface of “eagle's beak.” Contrast this with the normal left hypoglossal canal and jugular tubercle (Right) Coronal T1WI C+ FS MR in the same patient reveals heterogeneous enhancement of the schwannoma with marked scalloping of adjacent occipital bone & obliteration of normal “eagle's beak” as seen on CT The normal hypoglossal canal & jugular tubercle are identified on left P.V(1):21 TERMINOLOGY Abbreviations Hypoglossal nerve schwannoma (HNS), hypoglossal canal (HC) Definitions Benign tumor of differentiated Schwann cells surrounding CN12 IMAGING General Features Best diagnostic clue Fusiform, well-defined soft tissue mass along expected course of CN12 1147 Diagnostic Imaging Head and Neck Location May occur anywhere along course of CN12 Size Usually large Due to slow growth & location Morphology Fusiform; may attain dumbbell shape CT Findings NECT Sharply marginated soft tissue density mass along course of CN12 Fatty attenuation in ipsilateral hemitongue secondary to denervation atrophy CECT Uniformly enhancing ± intramural cysts Bone CT Smooth, sharply marginated, scalloped enlargement of HC Coronal plane: Enlargement, remodeling of undersurface & neck of jugular tubercle (below “eagle's beak”) MR Findings T1WI Typically isointense to gray matter Associated denervation may cause ipsilateral tongue muscle atrophy & fatty replacement with ↑ signal T2WI Typically ↑ signal Large HNS may have ↑ T2 signal intramural cysts T1WI C+ Uniform enhancement Imaging Recommendations Best imaging tool Enhanced multiplanar MR with bone CT providing complementary information with bony remodeling of HC DIFFERENTIAL DIAGNOSIS Asymmetric HC Venous Drainage (Pseudolesion) Nonenlarged HC with normal cortical margins Linear transcanalicular venous enhancement surrounding normal nerve Skull Base Metastasis Bony margins of HC are lytic or permeative Enhancing, invasive mass Persistent Hypoglossal Artery MR + MRA: Flow void passes through enlarged hypoglossal canal to basilar artery Jugular Foramen Meningioma Dural-based mass with enhancing dural “tail”; secondarily involves HC Permeative-sclerotic bony changes or hyperostosis Glomus Jugulare Paraganglioma Permeative-destructive bone margins of jugular foramen High-velocity flow voids are characteristic on MR PATHOLOGY Gross Pathologic & Surgical Features Smooth, tan, ovoid, encapsulated, & lobulated mass Arises eccentrically from CN12 nerve sheath CLINICAL ISSUES Presentation Most common signs/symptoms Hypoglossal neuropathy results in unilateral tongue denervation Tongue deviates toward side of lesion on protrusion Demographics Epidemiology Nonvestibular schwannoma incidence: CN5 > > > 10 > > 11 > 12 > > > Natural History & Prognosis Slowly growing, benign tumor 1148 Diagnostic Imaging Head and Neck Treatment Surgical removal of tumor in single operation is optimal DIAGNOSTIC CHECKLIST Consider HNS if well-defined fusiform mass identified along expected course of CN12 Reporting Tips Be sure to follow entire craniocaudal extent of lesion SELECTED REFERENCES Edizer DT et al: Hypoglossal schwannoma presenting only with headache J Craniofac Surg 21(1):261-2, 2010 Rachinger J et al: Dumbbell-shaped hypoglossal schwannoma A case report Magn Reson Imaging 21(2):155-8, 2003 Sarma S et al: Nonvestibular schwannomas of the brain: a 7-year experience Neurosurgery 50(3):437-48; discussion 438-9, 2002 Ogawa T et al: A multifocal neurinoma of the hypoglossal nerve with motor paralysis confirmed by electromyography Int J Oral Maxillofac Surg 30(2):176-8, 2001 Jugular Foramen Jugular Bulb Pseudolesion > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Jugular Foramen > Jugular Bulb Pseudolesion Jugular Bulb Pseudolesion Karen L Salzman, MD Key Facts Terminology Asymmetric, large jugular bulb (JB) flow phenomenon simulates neoplasm or thrombosis on MR sequences Imaging Best diagnostic clue: Complex MR signal in JB with normal jugular foramen cortex & jugular spine Complex MR signal does not persist on all MR sequences Normal bony margins of JB on T-bone CT Top Differential Diagnoses High jugular bulb Jugular bulb diverticulum Dehiscent jugular bulb Sigmoid sinus-jugular bulb thrombosis Jugular foramen schwannoma Clinical Issues Found incidentally on brain MR during work-up for unrelated symptoms Surgical exploration must be avoided by radiologist making correct diagnosis Diagnostic Checklist JB pseudolesion is most common JB “lesion” Once abnormality is seen in JF on MR, 1st question to ask is, “Am I looking at JB pseudolesion?” Do not mistake JB pseudolesion for schwannoma or venous sinus thrombosis If JB pseudolesion is observed while patient is in imaging center, add MRV to protocol to clarify Use bone CT to evaluate bony margins of JF if MR diagnosis uncertain 1149 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR shows heterogeneous enhancement of the left jugular foramen , concerning for thrombosis Other MR sequences confirmed this as a jugular bulb pseudolesion Right mastoid surgical changes are present (Right) Axial T1WI MR shows heterogeneous signal intensity within the left jugular foramen , concerning for pathology Other MR sequences proved this to be a jugular bulb pseudolesion These pseudolesions are most commonly related to an asymmetric, large jugular bulb (Left) Axial T2WI MR shows a hyperintense right jugular foramen “lesion” , concerning for a jugular foramen schwannoma in this elderly patient with new onset right-sided numbness (Right) Axial T1WI C+ FS MR in the same patient shows normal enhancement of a mildly prominent right jugular bulb The enhancement is similar to the enhancement of the normal sigmoid sinuses Other sequences including an MRA/MRV confirmed this as a jugular bulb pseudolesion P.V(1):23 TERMINOLOGY Synonyms Jugular bulb pseudomass, “leave-me-alone” lesion of jugular foramen Definitions Asymmetric, large jugular bulb (JB) flow phenomenon simulates neoplasm or thrombosis on MR sequences IMAGING General Features Best diagnostic clue Complex MR signal intensity in JB with normal jugular foramen (JF) cortex & jugular spine Location 1150 Diagnostic Imaging Head and Neck Jugular foramen bulb Prominent JB more commonly right-sided Size Typical jugular bulb measures 1.0-1.5 cm Morphology Rounded area of heterogeneous signal intensity centered on JF CT Findings CECT Normal enhancing sigmoid sinus (SS) & JB No filling defect to suggest thrombosis Bone CT Asymmetric JB, with intact cortical margins & jugular spine CTV: Asymmetric JB shows same enhancement as internal jugular vein (IJV) & SS MR Findings T1WI Variable signal; may have soft tissue intensity or heterogeneous signal T2WI Heterogeneous signal intensity Usually conspicuous when iso- to hyperintense FLAIR Heterogeneous signal intensity, often hyperintense T2* GRE No significant “blooming” T1WI C+ Avid enhancement of JB Identical enhancement to adjacent IJV & SS MRV JB shows asymmetric enlargement without evidence of thrombosis Phase contrast MRV: Shows normal flow in JB & SS Normal JB shows decrease in dynamic curve at ˜ 30 sec following contrast administration Angiographic Findings Catheter venography: Normal, asymmetrically large SS & JB fill with contrast Jugular bulb often “high-riding” DIFFERENTIAL DIAGNOSIS High Jugular Bulb Most cephalad portion of JB extends superior to floor of IAC ± basal turn of cochlea Bone CT: JB cortical margins intact; no middle ear extension Jugular Bulb Diverticulum Focal polypoid mass extending from cephalad JB into middle ear Smooth bone margins, intact sigmoid plate Dehiscent Jugular Bulb Usually present with vascular “mass” behind intact tympanic membrane Sigmoid plate dehiscence on CT Sigmoid Sinus-Jugular Bulb Thrombosis NECT: Hyperdense SS/JB, normal bony margins CECT/CTA/CTV: Look for intraluminal thrombus Vasa vasorum of vein wall may enhance as thin white rim (empty delta sign) MRV: Filling defect or lack of flow Glomus Jugulare Paraganglioma Permeative bony changes along JF T1WI MR: JF mass with high-velocity flow voids Vector of spread: Superolateral from JB to middle ear Jugular Foramen Schwannoma Smoothly scalloped, enlarged JF T1WI C+ MR: Dumbbell-shaped enhancing mass in JF Vector of spread: Superomedial along CN9-11 Jugular Foramen Meningioma Permeative-sclerotic or hyperostotic bony change around JF T1WI C+ MR: Enhancing dural “tails” along margins 1151 Diagnostic Imaging Head and Neck Vector of spread: Centrifugal along dural surfaces PATHOLOGY General Features Etiology Normal developmental variant CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic Found incidentally on brain MR during work-up for unrelated symptoms Demographics Epidemiology Most common “lesion” of JF found on MR imaging SELECTED REFERENCES Fayad JN et al: Jugular foramen tumors: clinical characteristics and treatment outcomes Otol Neurotol 31(2):299305, 2010 Palacios E et al: Jugular bulb appearing as a mass Ear Nose Throat J 78(8):536, 1999 High Jugular Bulb > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Jugular Foramen > High Jugular Bulb High Jugular Bulb Karen L Salzman, MD Key Facts Terminology High jugular bulb (JB): Superior aspect of JB extends above floor of IAC with no middle ear connection If dehiscence into middle ear present, use “dehiscent JB” not “high JB” to describe Imaging Most cephalad portion of JB extends superior to floor of IAC ± at level of basal turn of cochlea Jugular foramen cortical margins intact Axial: JB at level of IAC or cochlea Cor: JB medial ± inferior to semicircular canals T1WI C+: High JB enhances same as jugular vein MRV: Same signal as surrounding venous structures High JB occurs most commonly on right Best imaging tool: T-bone CT Top Differential Diagnoses Jugular bulb pseudolesion Jugular bulb diverticulum Dehiscent jugular bulb Glomus jugulare paraganglioma Jugular foramen schwannoma Jugular foramen meningioma Pathology High JB is more commonly seen with poorly aerated mastoid air cells Clinical Issues High JB is typically incidental May ↑ risk of inadvertently entering JB during mastoidectomy Otoscopic exam: Normal Conservative management most common treatment 1152 Diagnostic Imaging Head and Neck (Left) Axial T-bone CT of the left ear shows a high jugular bulb present at the level of the internal auditory canal The high jugular bulb abuts the bony vestibular aqueduct on its posterior margin (Right) Coronal T-bone CT in the same patient shows the high jugular bulb as a cephalad extension of the jugular foramen A high jugular bulb occurs most commonly on the right side This congenital lesion can be associated with jugular bulb dehiscence or a jugular bulb diverticulum (Left) Axial T-bone CT of the right ear shows a high jugular bulb at the level of the cochlea These congenital lesions are typically incidental, but may be associated with pulsatile tinnitus (Right) Coronal T1WI C+ FS MR shows a high jugular bulb connected inferiorly to a large internal jugular vein The top of the high jugular bulb reaches the level of the floor of the internal auditory canal On axial images, this may mimic an inner ear lesion if the connection to the jugular vein is not appreciated P.V(1):25 TERMINOLOGY Abbreviations High jugular bulb (JB) Synonyms High-riding jugular bulb Definitions Superior aspect of JB extends above floor of IAC with no connection to middle ear If dehiscent JB into middle ear, use “dehiscent JB” not “high JB” to describe IMAGING General Features Best diagnostic clue 1153 Diagnostic Imaging Head and Neck Bone CT: Most cephalad portion of JB extends superior to floor of IAC ± at level of basal turn of cochlea Location When JB reaches or exceeds floor of IAC Occurs most commonly on right Size Variable, JB typically 1.0-1.5 cm Morphology Superior extension of JB with smooth bony margins Imaging Recommendations Best imaging tool: T-bone CT CT Findings NECT Axial: JB at level of IAC, often at cochlea basal turn Cor: JB medial ± inferior to semicircular canals Bone CT: Jugular foramen (JF) cortical margins intact, including sigmoid plate MR Findings T1WI: May be heterogeneous T2WI: Most commonly hypointense (invisible), may be heterogeneous T1WI C+: High JB enhances same as internal jugular vein (IJV) Coronal: Extends to level of IAC MRV: Same signal as surrounding venous structures DIFFERENTIAL DIAGNOSIS Jugular Bulb Pseudolesion MR shows asymmetric large JB with mass-like signal Usually found incidentally in skull base work-up Bone CT: Intact jugular spine & JB cortical margins Jugular Bulb Diverticulum Bone CT: Focal projection extending off JB margin superiorly into deep temporal bone just behind IAC T1 C+ MR: Enhancing middle ear mass connects to enhancing JB Dehiscent Jugular Bulb Vascular retrotympanic mass Protruding mass extends into posteroinferior middle ear cavity Bone CT: Sigmoid plate shows focal dehiscence T1 C+ MR: Enhancing mass connects to enhancing JB Glomus Jugulare Paraganglioma Enhancing mass in jugular foramen (JF) Bone CT: Permeative destructive JF bony changes T1 C- MR: High-velocity flow voids (“pepper”) Jugular Foramen Schwannoma Dumbbell-shaped mass along cranial nerves 9-11 Bone CT: Smoothly scalloped, enlarged JF T1 C+ MR: Fusiform enhancing JF mass Jugular Foramen Meningioma Mass in JF spreading centrifugally along dural planes Bone CT: Permeative-sclerotic or hyperostotic margins T1 C+ MR: Avidly enhancing mass with dural “tails” PATHOLOGY General Features Etiology Congenital abnormality, benign vascular variant High JB is more commonly seen with poorly aerated mastoid & perilymphatic structures CLINICAL ISSUES Presentation Most common signs/symptoms Most commonly an incidental finding Rarely reported to be associated with pulsatile tinnitus; causality uncertain Demographics Age: May be discovered at any age Gender: Slight female predominance 1154 Diagnostic Imaging Head and Neck Epidemiology: 5% of temporal bone specimens JB diverticulum present in 35% of cases with high JB Treatment Conservative management DIAGNOSTIC CHECKLIST Consider High JB is typically incidental ↑ risk of entering JB during mastoidectomy Image Interpretation Pearls MR: Complex or increased signal of high JB does not persist on all MR sequences SELECTED REFERENCES Friedmann DR et al: Clinical spectrum of patients with erosion of the inner ear by jugular bulb abnormalities Laryngoscope 120(2):365-72, 2010 Vachata P et al: An anatomical and radiological study of the high jugular bulb on high-resolution CT scans and alcohol-fixed skulls of adults J Clin Neurosci 17(4):473-8, 2010 Muluk NB: The SF-36 Health Survey in tinnitus patients with a high jugular bulb J Otolaryngol Head Neck Surg 38(2):166-71, 2009 Dehiscent Jugular Bulb > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Jugular Foramen > Dehiscent Jugular Bulb Dehiscent Jugular Bulb Deborah R Shatzkes, MD Key Facts Terminology DJB: Normal venous variant with superior & lateral extension of jugular bulb (JB) into middle ear (ME) cavity through dehiscent sigmoid (jugular) plate Imaging Soft tissue mass in ME contiguous with JB through dehiscent sigmoid plate Lateral outpouching from JB well seen on coronal bone CT Enhances to same degree as adjacent venous structures on C+ CT and MR CTA or MRA may be performed in equivocal cases Top Differential Diagnoses Asymmetrically large jugular bulb High-riding jugular bulb Jugular bulb diverticulum Glomus jugulare paraganglioma Glomus tympanicum paraganglioma Jugular foramen schwannoma Jugular foramen meningioma Clinical Issues DJB has been reported as linked to many symptoms, though causality is disputed Pulsatile tinnitus, hearing loss, Ménière disease Otoscopy: Vascular blue “mass” behind intact tympanic membrane may prompt imaging Important to warn surgeons of presence of DJB when surgery is contemplated for other indications Diagnostic Checklist DJB in differential diagnosis list of any vascular retrotympanic mass Coronal temporal bone CT will show direct continuity of middle ear mass with JB 1155 Diagnostic Imaging Head and Neck (Left) Axial graphic depicts a dehiscent jugular bulb projecting superolaterally into the middle ear through the dehiscent sigmoid plate Typically, a vascular “mass” is identified behind the intact tympanic membrane (Right) Axial T1WI C+ MR shows enhancement of the prominent jugular bulb contiguous with the dehiscent component in the middle ear Enhancement is identical to the sigmoid sinuses (Left) Axial bone CT demonstrates the jugular bulb and the soft tissue density mass within the inferior right middle ear cavity contiguous through the widely dehiscent jugular plate (Right) Coronal bone CT shows a laterally lobulated extension of the dehiscent jugular bulb into the right middle ear DJB is the most common vascular variant of the temporal bone and is more frequent on the right P.V(1):27 TERMINOLOGY Abbreviations Dehiscent jugular bulb (DJB) Definitions Normal venous variant with superior & lateral extension of JB into middle ear (ME) through dehiscent sigmoid (jugular) plate IMAGING CT Findings CECT Protruding mass enhances to same degree as JB Bone CT 1156 Diagnostic Imaging Head and Neck Soft tissue mass in posteroinferior ME Sigmoid plate is dehiscent CTA Enhancement pattern mirrors sigmoid sinus & internal jugular (IJ) vein MR Findings T1WI May have heterogeneous intensity or flow void T2WI May have heterogeneous intensity or flow void T1WI C+ Avidly enhancing ME mass connects to avidly enhancing JB MRV Coronal images show lateral lobulation best DIFFERENTIAL DIAGNOSIS Jugular Foramen Asymmetry Common normal variant, right more common Bone CT: Intact JB cortical margins High Jugular Bulb Defined by most cephalad portion extending superior to floor of IAC ± at level of basal turn of cochlea JB cortical margins intact, including sigmoid plate Jugular Bulb Diverticulum Focal polypoid mass extending from cephalad JB Sigmoid plate is intact Glomus Jugulare Paraganglioma Bone CT: Permeative-destructive bony changes along JB superolateral margins Unenhanced T1 MR: Jugular foramen (JF) mass with high-velocity flow voids (“pepper”) Glomus Tympanicum Paraganglioma Bone CT: Focal mass on cochlear promontory with ME floor intact Jugular Foramen Schwannoma Bone CT: Smoothly scalloped, enlarged JF T1 C+ MR: Dumbbell-shaped enhancing JF mass Jugular Foramen Meningioma CT: Permeative-sclerotic or hyperostotic bony changes T1 C+ MR: May show dural “tails” T2 MR: Intermediate signal intensity, similar to cortex PATHOLOGY General Features Etiology Congenital lesion Associated abnormalities Most often associated with high-riding JB CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic incidental finding Other signs/symptoms DJB has been reported as linked to many symptoms, though causality disputed Pulsatile tinnitus, hearing loss, Ménière disease Otoscopy: Vascular mass behind intact TM, prompting imaging Demographics Epidemiology Most common vascular variant of petrous bone More common on right side Dural venous sinuses and jugular vein are larger on right in 75% of individuals Natural History & Prognosis Renders JB vulnerable to trauma Important to warn surgeons of presence of DJB when surgery is contemplated for other indications DIAGNOSTIC CHECKLIST Consider 1157 Diagnostic Imaging Head and Neck DJB in differential diagnosis list of any vascular retrotympanic mass Image Interpretation Pearls Coronal TB CT will show direct continuity of middle ear mass with jugular bulb Smooth bony margins exclude more aggressive processes, such as tumor or infection SELECTED REFERENCES Ball M et al: Beware the silent presentation of a high and dehiscent jugular bulb in the external ear canal J Laryngol Otol 124(7):790-2, 2010 El-Begermy MA et al: A novel surgical technique for management of tinnitus due to high dehiscent jugular bulb Otolaryngol Head Neck Surg 142(4):576-81, 2010 Huang BR et al: Dehiscent high jugular bulb: a pitfall in middle ear surgery Otol Neurotol 27(7):923-7, 2006 Hourani R et al: Dehiscence of the jugular bulb and vestibular aqueduct: findings on 200 consecutive temporal bone computed tomography scans J Comput Assist Tomogr 29(5):657-62, 2005 Weissman JL et al: Imaging of tinnitus: a review Radiology 216(2):342-9, 2000 Caldemeyer KS et al: The jugular foramen: a review of anatomy, masses, and imaging characteristics Radiographics 17(5):1123-39, 1997 Jugular Bulb Diverticulum > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Jugular Foramen > Jugular Bulb Diverticulum Jugular Bulb Diverticulum Karen L Salzman, MD Key Facts Terminology Congenital vascular anomaly of jugular bulb (JB), with focal finger-like projection extending from JB into surrounding skull base Imaging T-bone CT: Focal projection extending off JB margin superiorly into deep T-bone just behind IAC Other directions of extension: Lateral, medial, anterior, or posterior Imaging protocol: Start with thin section T-bone CT If concern lingers, MR with contrast & MRV Top Differential Diagnoses Jugular bulb pseudolesion High jugular bulb Dehiscent jugular bulb Glomus jugulare paraganglioma Jugular foramen schwannoma or meningioma Pathology JBD thought to represent expansion of high JB into surrounding bone but hindered by dense otic capsule Clinical Issues Asymptomatic, incidental finding commonly Many symptoms have been linked to JBD JBD present in 35% of cases with high-riding JB Diagnostic Checklist Jugular bulb diverticulum in differential of medial temporal bone mass with smooth margins on CT Turbulent flow makes JB & JBD difficult to evaluate by MR Look for smooth bony remodeling on bone CT & continuity with jugular bulb 1158 Diagnostic Imaging Head and Neck (Left) Coronal graphic depicts a jugular bulb diverticulum as a finger-like superior projection off the jugular bulb into the petrous temporal bone without extension into the middle ear (Right) Coronal left ear T-bone CT shows a jugular bulb diverticulum as a thumb-like projection arising from the superior jugular bulb margin Continuity with the normal jugular bulb and smooth bony margins help confirm the diagnosis This jugular bulb lesion is more common on the left side Patients are most commonly asymptomatic (Left) Axial left T-bone CT shows a jugular bulb diverticulum projecting cephalad from the jugular bulb into the medial temporal bone These diverticula are typically located posterior to the internal auditory canal and have smooth bony margins (Right) Axial MRV source image shows a medially projecting jugular bulb diverticulum This polypoid extension from the jugular bulb has similar enhancement characteristics as the jugular bulb and jugular vein A JB diverticulum may be discovered at any age P.V(1):29 TERMINOLOGY Abbreviations Jugular bulb diverticulum (JBD) Synonyms Jugular diverticulum, petrous jugular malposition Definitions JBD: Congenital vascular anomaly of jugular bulb (JB), with focal finger-like projection extending from JB into surrounding skull base IMAGING 1159 Diagnostic Imaging Head and Neck General Features Best diagnostic clue T-bone CT: Focal polypoid projection extending off JB margin superiorly into deep temporal bone just behind IAC Location JBD most commonly extends superiorly Other directions of extension Lateral, medial, anterior, or posterior Lateral extension is often through dehiscent sigmoid plate = dehiscent jugular bulb JB itself may be high or less commonly in normal position Size Typical jugular bulb measures 1.0-1.5 cm Diverticulum smaller than JB, typically < cm in diameter & length Morphology Lobulated outpouching arising from JB May be finger-like or broad-based CT Findings Bone CT: JBD is well-corticated smooth polypoid extension off JB margin Axial: Most commonly seen behind IAC Coronal: Finger-like projection off top of JB CECT: Uniform enhancement of JB & JBD CTA: Contiguous with JB, similar enhancement MR Findings T1WI: Heterogeneous signal intensity T2WI: Low signal from high-velocity flow (invisible) Turbulent flow, heterogeneous high intensity (uncommon) T1WI C+: Avid enhancement, similar to JB & IJV May mimic IAC or intralabyrinthine schwannoma MRV: Finger-like projection off JB Imaging Recommendations Protocol advice: Start with thin section T-bone CT If concern lingers, MR with contrast & MRV DIFFERENTIAL DIAGNOSIS Jugular Bulb Pseudolesion MR shows asymmetric large JB with mass-like signal Usually found incidentally in skull base work-up Bone CT: Intact jugular spine & JB cortical margins High Jugular Bulb Defined by most as cephalad portion of JB extending superior to floor of IAC ± at level of basal turn of cochlea CT: Jugular foramen (JF) cortical margins intact, including sigmoid plate MR: Complex or increased signal does not persist on all MR sequences Dehiscent Jugular Bulb Vascular retrotympanic mass Protruding mass extends into posteroinferior middle ear cavity CT: Sigmoid plate shows focal dehiscence T1 C+ MR: Avidly enhancing middle ear mass connects to avidly enhancing JB Glomus Jugulare Paraganglioma Enhancing mass in jugular foramen CT: Permeative destructive JF margin bony changes T1 C- MR: High-velocity flow voids (“pepper”) Jugular Foramen Schwannoma Dumbbell-shaped mass along cranial nerve 9-11 CT: Smoothly scalloped bony margins of enlarged JF T1 C+ MR: Fusiform enhancing mass in JF PATHOLOGY General Features Etiology JBD may be secondary to hemodynamic factors JBD more commonly seen with high-riding JB 1160 Diagnostic Imaging Head and Neck Thought to represent expansion of high JB into surrounding bone, hindered by dense otic capsule CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic, incidental finding Many symptoms have been linked to JBD, based on direction of diverticulum extension: Sensorineural hearing loss, tinnitus, vertigo Symptoms reported have tenuous link to JBD Demographics Epidemiology Present in 8% of T-bone specimen studies More common on left side Treatment Caveat: Include in radiology report to warn surgeon if ear surgery planned SELECTED REFERENCES Friedmann DR et al: Clinical spectrum of patients with erosion of the inner ear by jugular bulb abnormalities Laryngoscope 120(2):365-72, 2010 Bilgen C et al: Jugular bulb diverticula: clinical and radiologic aspects Otolaryngol Head Neck Surg 128(3):382-6, 2003 Glomus Jugulare Paraganglioma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Jugular Foramen > Glomus Jugulare Paraganglioma Glomus Jugulare Paraganglioma Karen L Salzman, MD H Ric Harnsberger, MD Key Facts Terminology GJP: Benign tumor arising from neural crest progenitor crest cells (glomus bodies) located in & around jugular foramen (JF) Imaging Bone CT: Permeative-destructive bone changes along JF margins Jugular spine erosion is common MR: Lesions > cm demonstrate characteristic “salt & pepper” appearance CTA/angiography: Main arterial supply is from ascending pharyngeal artery Paraganglia rests occur in distinct bodies around JF: Jugular bulb, tympanic branch of CN9 (Jacobsen nerve), & auricular branch of CN10 (Arnold nerve) Vector of spread: Superolateral through floor of middle ear is typical Top Differential Diagnoses Jugular foramen schwannoma Jugular foramen meningioma Jugular foramen metastasis Jugular foramen pseudolesion Dehiscent jugular bulb Clinical Issues Presentation: Objective pulsatile tinnitus Otoscopic exam: Vascular retrotympanic mass Other symptoms: 9-11 ± 12 cranial neuropathy; or cranial neuropathy less often GJP & carotid body paraganglioma account for 80% of head & neck paragangliomas Treatment: Surgical resection ± radiation Radiosurgery may be used as primary therapy 1161 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows a glomus jugulare paraganglioma centered in the jugular foramen with superolateral extension into the middle ear The main arterial supply for this vascular tumor is the ascending pharyngeal artery (Right) Coronal T-bone CT of the right ear shows the classic permeative destructive margins of a glomus jugular paraganglioma Note the typical vector of spread superolateral from the jugular foramen to the middle ear The middle ear component is seen as a vascular retrotympanic mass at otoscopy (Left) Axial T1WI MR shows a large mass arising from the jugular foramen with multiple areas of “salt & pepper.” The “salt” represents blood products or slow flow, while the “pepper” represents high-velocity arterial branch flow voids that help differentiate this tumor from other lesions in this location (Right) Axial T1WI C+ FS MR in the same patient shows the classic intense enhancement of this large vascular tumor There is intracranial extension in this patient with mass effect upon the adjacent medulla P.V(1):31 TERMINOLOGY Abbreviations Glomus jugulare paraganglioma (GJP), jugular foramen (JF) Synonyms Glomus jugulotympanicum paraganglioma, jugular foramen paraganglioma, chemodectoma Definitions Benign tumor arising from neural crest progenitor cells (glomus bodies) located in & around jugular foramen (JF) IMAGING General Features Best diagnostic clue 1162 Diagnostic Imaging Head and Neck Mass in JF with “permeative-destructive” change of adjacent bone on CT Multiple black dots (“pepper”) in tumor mass indicating high-velocity flow voids from feeding arterial branches on MR Location Paraganglia rests occur in distinct bodies around jugular foramen Jugular bulb (JB), tympanic branch of CN9 (Jacobsen nerve), & auricular branch of CN10 (Arnold nerve) Vector of spread: Superolateral through floor of middle ear (most common) Size Large at presentation 2-6 cm range most commonly Morphology Poorly marginated JF tumor with adjacent bone invasion CT Findings NECT Poorly defined soft tissue mass centered over JF CECT Diffuse, intense enhancement Bone CT Permeative-destructive bone changes along superolateral margin of JF mark extent of tumor Jugular spine erosion is common Vertical segment of petrous ICA posterior wall often dehiscent Mastoid segment of facial nerve may be engulfed Mimics malignancy MR Findings T1WI Lesions > cm demonstrate characteristic “salt & pepper” appearance “Salt” refers to hyperintense foci within tumor related to hemorrhage or slow flow Hyperintense foci relatively rare MR finding “Pepper” refers to numerous hypointense foci within tumor representing high-velocity arterial flow voids Hypointense foci common MR finding T2WI Mixed hyperintense mass with hypointense foci (“pepper”) T1WI C+ Intense enhancement is characteristic Delineates tumor extent in skull base & middle ear Tumor may extend intraluminal within internal jugular vein or sigmoid sinus Coronal: May show tongue of tumor curving up from JF, through middle ear floor, terminating on cochlear promontory MRV Delineates sigmoid sinus status Angiographic Findings Hypervascular mass with enlarged feeding arteries, rapid, intense tumor blush & early draining veins Main arterial supply is from ascending pharyngeal artery that supplies inferomedial territory Caroticotympanic branches of ICA & meningeal branches of vertebral artery may contribute Anterior tympanic artery from ECA supplies anterior compartment Stylomastoid artery from ECA supplies posterolateral compartment Nuclear Medicine Findings PET Paragangliomas show avid 18F FDG uptake Useful in detecting metastasis or response to therapy Imaging Recommendations Best imaging tool Combination of bone CT and enhanced MR Bone CT, MR, & angiography all done before surgery Bone CT delineates areas of bone destruction & dehiscence; shows bony landmarks less well seen on MR MR reveals exact soft tissue extent of tumor Angiography provides vascular road map for surgeon 1163 Diagnostic Imaging Head and Neck Embolization used for preoperative hemostasis DIFFERENTIAL DIAGNOSIS Jugular Foramen Schwannoma Bone CT: Smooth remodeling, enlargement of JF T1 C+ MR: Fusiform enhancing mass ± cysts Angio: Absence of tumor blush or enlarged feeding arteries on angiography; “puddling” on venous phase Vector of spread: Superomedial along CN9-11 course Jugular Foramen Meningioma Bone CT: Permeative-sclerotic bony JF margins T1 C+ MR: Enhancing mass with dural “tails” Angio: Prolonged but mild tumor blush Vector of spread: Centrifugal spread along dural surfaces Jugular Foramen Metastasis Bone CT: Destructive bone changes on JF margins T1 C+ MR: Heterogeneously enhancing invasive mass Vector of spread: Irregular centrifugal spread pattern Jugular Foramen Pseudolesion Asymmetric JF MR signal mimics schwannoma or other lesion P.V(1):32 Bone CT: JF bony margins intact MR: Conspicuous JB signal does not persist in all MR sequences Dehiscent Jugular Bulb Bone CT: Sigmoid plate is focally dehiscent Coronal CT or MR: Superolateral extension of jugular bulb into middle ear PATHOLOGY General Features Etiology Benign tumor arising from paraganglia in & around jugular foramen Paraganglia (glomus bodies): Chemoreceptors that respond to changes in blood oxygen, carbon dioxide levels Genetics Familial prevalence 8% for all paragangliomas Only gene that is passed on paternally will manifest in familial form Associated abnormalities Increased risk of thyroid malignancy Increased risk of paragangliomas in MEN 1, NF1, multiple myocutaneous neuromas Staging, Grading, & Classification Glasscock-Jackson Classification of Glomus Jugulare: Correlates tumor extent with surgical approach I: Small tumor involving JB, middle ear, mastoid II: Tumor extends under IAC; may have intracranial extension III: Extends into petrous apex (PA); may have intracranial extension IV: Extends beyond PA, into clivus or infratemporal fossa; ± intracranial extension Fisch Classification: Anatomic classification A: Tumor limited to middle ear B: Limited to tympanomastoid area, no infralabyrinthine involvement C: Invades infralabyrinthine compartment & PA C1: Limited involvement of vertical carotid canal C2: Invades vertical carotid canal C3: Invades horizontal carotid canal D1: Intracranial extension < cm D2: Intracranial extension > cm Gross Pathologic & Surgical Features Lobulated, solid mass with fibrous pseudocapsule Cut surface shows multiple enlarged feeding arteries Microscopic Features Biphasic cell pattern composed of chief cells & sustentacular cells surrounded by fibromuscular stroma Chief cells arranged in characteristic compact cell nests or balls of cells (zellballen) 1164 Diagnostic Imaging Head and Neck Electromicroscopy: Shows neurosecretory granules CLINICAL ISSUES Presentation Most common signs/symptoms Objective pulsatile tinnitus Otoscopic exam: Vascular retrotympanic mass Other symptoms: 9-11 ± 12 cranial neuropathy; or cranial neuropathy less often Otologic symptoms predominate initially with cranial nerve palsies occurring late Clinical profile 50-year-old woman with progressive pulsatile tinnitus & vascular retrotympanic mass Demographics Age 40-60 years Gender M:F = 1:4 Epidemiology GJP & carotid body paraganglioma account for 80% of head & neck paragangliomas GJP is most common JF tumor GJP is 2nd most common temporal bone tumor (glomus tympanicum paraganglioma is 1st) Multicentric 5-10% in sporadic GJPs Multicentric 25-50% in familial GJPs Natural History & Prognosis Slow-growing tumor can be watched in older patients 60% have postoperative cranial neuropathy Aggressive behavior is seen in 2-13% of cases Mortality rates are estimated at 15% Treatment Surgery: Infratemporal fossa approach (Fisch type A) Larger lesions may require surgery & radiation Radiation therapy or radiosurgery may be used as primary therapy DIAGNOSTIC CHECKLIST Consider Look for multicentric lesions when evaluating GJP Both GJP & JF metastases will have permeative bone destruction Vascular schwannoma may mimic GJP on MR Image Interpretation Pearls Use bone CT to distinguish paraganglioma from meningioma & schwannoma GJP diagnosed when mass shows following MR: JF mass with prominent flow voids (“pepper”) Vector of spread: Superolateral → JF into middle ear Bone CT: Permeative-destructive bone invasion SELECTED REFERENCES Chen PG et al: Treatment of glomus jugulare tumors with gamma knife radiosurgery Laryngoscope Epub ahead of print, 2010 Fayad JN et al: Jugular foramen tumors: clinical characteristics and treatment outcomes Otol Neurotol 31(2):299305, 2010 Navarro Martín A et al: Successful treatment of glomus jugulare tumours with gamma knife radiosurgery: clinical and physical aspects of management and review of the literature Clin Transl Oncol 12(1):55-62, 2010 Kemeny AA: Contemporary management of jugular paragangliomas (glomus tumours): microsurgery and radiosurgery Acta Neurochir (Wien) 151(5):419-21, 2009 P.V(1):33 Image Gallery 1165 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows a large glomus jugulare paraganglioma arising from the jugular foramen engulfing the jugular vein and CN9-12 and infiltrating the adjacent skull base (Right) Coronal T1WI MR shows a large glomus jugulare paraganglioma involving the skull base with extension to the external auditory canal Note the multiple high-velocity flow voids , characteristic of paraganglioma A glomus jugulare paraganglioma is the 2nd most common tumor of the temporal bone (Left) Axial T-bone CT of the right ear shows a large mass centered in the jugular foramen with the typical permeative destructive margins of a glomus jugulare paraganglioma (Right) T1WI C+ FS MR in the same patient shows marked enhancement of the glomus jugulare paraganglioma Note fluid in the adjacent mastoid air cells related to obstruction of the eustachian tube CT and MR are complementary in evaluation of jugular foramen lesions 1166 Diagnostic Imaging Head and Neck (Left) Coronal T-bone CT of the right ear shows permeative destructive margins of a small glomus jugulare paraganglioma The tumor has the typical vector of spread superolateral from the jugular foramen Note an intact jugular tubercle in this case, a rare finding (Right) Anteroposterior selective ascending pharyngeal artery angiogram reveals extensive filling of a glomus jugulare paraganglioma Note the early draining vein related to arteriovenous shunting Jugular Foramen Schwannoma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Jugular Foramen > Jugular Foramen Schwannoma Jugular Foramen Schwannoma Karen L Salzman, MD H Ric Harnsberger, MD Key Facts Terminology Benign tumor of differentiated Schwann cells wrapping around cranial nerves (CN) 9, 10, or 11 within jugular foramen (JF) Imaging Bone CT: Sharply marginated, enlarged JF T1WI C+ MR Tubular or dumbbell-shaped, uniformly enhancing No flow voids (“pepper”) (vs paraganglioma) Nonenhancing cystic areas in large lesions Superomedial vector of tumor growth Follows craniocaudal course of CNs 9-11 Grows cephalad from JF through basal cistern toward retro-olivary sulcus of lateral medulla Grows inferiorly from JF into nasopharyngeal carotid space MRV: Dural sinus compressed, not occluded Top Differential Diagnoses Jugular foramen pseudolesion Glomus jugulare paraganglioma Jugular foramen meningioma Skull base metastasis Clinical Issues Mean age: 45 years old Sensorineural hearing loss in 90% at presentation May present clinically like vestibular schwannoma 2nd most common JF tumor Glossopharyngeal nerve most common nerve of origin Complete surgical removal of tumor in single procedure is goal 1167 Diagnostic Imaging Head and Neck May be complicated by lower cranial neuropathy Radiosurgery as primary or adjuvant therapy (Left) Coronal graphic depicts a classic jugular foramen schwannoma as a fusiform mass arising on one of the cranial nerves (9-11) within the jugular foramen Note the vector of spread is superomedial The jugular foramen is enlarged with an intact cortex (Right) Coronal bone CT shows a sharply marginated, enlarged jugular foramen with amputation of the lateral jugular tubercle The smooth enlargement with sclerotic margins is characteristic of jugular foramen schwannoma (Left) Coronal T1WI C+ MR shows an enhancing JF schwannoma with a fusiform shape, projecting superomedially from the JF toward the brainstem Inferiorly, the schwannoma extends into the nasopharyngeal carotid space (Right) Axial T2WI MR shows heterogeneous hyperintense signal within the inferior portion of a jugular foramen schwannoma due to intramural cysts The internal carotid artery flow void is seen along the anterior margin of the tumor Note the absence of flow voids P.V(1):35 TERMINOLOGY Abbreviations Jugular foramen schwannoma (JFS) Synonyms Neuroma, neurilemoma, neurinoma Definitions Benign tumor of differentiated Schwann cells wrapping around cranial nerves (CN) 9, 10, or 11 within JF 1168 Diagnostic Imaging Head and Neck IMAGING General Features Best diagnostic clue Sharply marginated enlarged JF on bone CT Fusiform, enhancing mass enlarging JF on T1WI C+ MR Location Jugular foramen Vector of tumor growth Follows general craniocaudal course of CNs 9-11 Grows cephalad from JF through basal cistern toward retro-olivary sulcus of lateral medulla Grows inferiorly from JF into nasopharyngeal carotid space Size Often large at presentation (> cm) Morphology Fusiform or “dumbbell” mass Waist is within JF CT Findings NECT Well-defined soft tissue mass isodense to brain, occasionally hypodense CECT Dense contrast enhancement is typical Larger JFS often show nonenhancing intramural cysts Bone CT Smooth JF enlargement with thin, sclerotic margins Coronal plane may show amputation of lateral jugular tubercle (“bird's beak”) Multilobular intraosseous extension into adjacent skull base may be marked MR Findings T1WI Tubular or dumbbell-shaped JF mass Typically isointense to brain Internal carotid artery characteristically displaced over anteromedial margin of JFS in nasopharyngeal carotid space No flow voids (“pepper”) even when large T2WI High signal relative to white matter ↑ signal cystic areas can be seen in large JFS 25% of JFS show intramural cysts T1WI C+ Uniformly enhancing JF mass Nonenhancing intramural cystic components in larger tumors When small, may be difficult to differentiate enhancing normal jugular bulb (JB) from small JFS Tissue-intensity mass seen better on unenhanced T1 & T2WI MRV Dural sinuses usually compressed, not occluded Occlusion can be evaluated with phase contrast MRV employing low VENC (velocity encoding setting) Angiographic Findings Tumor is moderately vascular Feeding vessels are tortuous but not enlarged Scattered contrast “puddles” are characteristic in venous phase Arteriovenous shunting or vascular encasement not present Imaging Recommendations Best imaging tool Enhanced brain/skull base MR best delineates internal architecture & soft tissue extent of JFS Bone CT is best for assessing JF cortex for typical smooth, sclerotic margins DIFFERENTIAL DIAGNOSIS Jugular Foramen Pseudolesion Venous flow phenomenon mimics schwannoma or other lesion 1169 Diagnostic Imaging Head and Neck Asymmetric large JB with complex MR signal Asymmetric large JF with normal margins on CT T1 C+ MR: Slow flow in JF enhances MRV: Normal dural sinuses & jugular bulb Glomus Jugulare Paraganglioma Permeative-destructive JF bone margins on bone CT High-velocity flow voids (“pepper”) on unenhanced MR sequences Rapid tumor blush with early draining veins on angiography Growth vector: Superolateral from JF into middle ear Jugular Foramen Meningioma Permeative-sclerotic bone margins of JF on CT Intermediate to low signal on T2WI Dural-based mass with enhancing dural “tails” Prolonged blush into capillary phase on angiography Growth vector: Centrifugally along dural surfaces Skull Base Metastasis Bony margins of JF are destructive on CT Heterogeneously enhancing, invasive JF mass Growth vector: All directions from JF PATHOLOGY General Features Etiology Arises from differentiated neoplastic Schwann cells wrapping around CNs 9, 10, or 11 Genetics P.V(1):36 90% are solitary and sporadic 4% arise in setting of NF2 < 5% associated with schwannomatosis Associated abnormalities Multiple schwannomas are associated with NF2 or schwannomatosis Staging, Grading, & Classification Kaye & Pellet Surgical Classification (from surgical & radiologic findings) Type A: Extends to cerebellopontine angle (CPA) Type B: Within jugular foramen Type C: Nasopharyngeal carotid space &/or jugular foramen Type D: Intracranial and extracranial (cisternal & carotid space) Gross Pathologic & Surgical Features Smooth, lobulated mass arising from nerve sheath Arises eccentrically from nerve sheath Tan, round/ovoid, encapsulated mass Microscopic Features Differentiated neoplastic Schwann cells Spindle cells with elongated nuclei Areas of compact, elongated cells = Antoni A Areas of less cellular loosely arranged tumor, ± clusters of lipid-laden cells = Antoni B Immunochemistry: Strong, diffuse immunostaining for S100 protein = neural crest marker antigen present in supporting cells of nervous system No necrosis but may have intratumoral cysts ± hemorrhage CLINICAL ISSUES Presentation Most common signs/symptoms Sensorineural hearing loss (SNHL) in 90% at presentation May present clinically like vestibular schwannoma Other signs/symptoms CNs 9-11 neuropathy occurs late in disease progression Hoarseness, aspiration (recurrent laryngeal nerve, branch of CN10) Dizziness may be related to cerebellar compression 1170 Diagnostic Imaging Head and Neck Pulsatile tinnitus may be related to dural sinus thrombosis and dAVF Hemifacial spasm Clinical profile Middle-aged (˜ 45 years old) individual with unilateral SNHL Demographics Age Mean age: 45 years old Gender No gender predilection Epidemiology Schwannomas represent 8% of intracranial tumors 85-90% of CPA tumors are schwannoma 2nd most common JF tumor Glomus jugulare paraganglioma > > schwannoma > meningioma Nonvestibular schwannoma incidence: CN5 > > CN9 > CN10 > CN7 > CN11 > CN12 > CN3 > CN4 > CN6 Glossopharyngeal nerve most common nerve of origin of JFS Natural History & Prognosis Benign, slow-growing tumor Advanced disease or treatment may result in late CN7-12 neuropathy Treatment Complete surgical removal of tumor in single procedure is goal Surgical approach dictated by presence or absence of cisternal or nasopharyngeal carotid space extension Surgical cure may be complicated by lower cranial neuropathy, often CN9 & 10 Stereotactic radiosurgery is being used more frequently as primary or adjuvant therapy DIAGNOSTIC CHECKLIST Consider JFS most likely when smooth, scalloped margins seen around JF soft tissue mass on CT Image Interpretation Pearls Lack of flow voids help differentiate JFS from more common glomus jugulare paraganglioma Reporting Tips Be sure to describe extension below skull base into carotid space! SELECTED REFERENCES Fayad JN et al: Jugular foramen tumors: clinical characteristics and treatment outcomes Otol Neurotol 31(2):299305, 2010 Safavi-Abbasi S et al: Nonvestibular schwannomas: an evaluation of functional outcome after radiosurgical and microsurgical management Acta Neurochir (Wien) 152(1):35-46, 2010 Chibbaro S et al: Dumbbell-shaped jugular foramen schwannomas: surgical management, outcome and complications on a series of 16 patients Neurosurg Rev 32(2):151-9; discussion 159, 2009 Fukuda M et al: Long-term outcomes after surgical treatment of jugular foramen schwannoma Skull Base 19(6):401-8, 2009 Nishioka K et al: Stereotactic radiotherapy for intracranial nonacoustic schwannomas including facial nerve schwannoma Int J Radiat Oncol Biol Phys 75(5):1415-9, 2009 Hamm KD et al: Stereotactic radiotherapy for the treatment of nonacoustic schwannomas Neurosurgery 62(5 Suppl):A29-36; discussion A36, 2008 Song MH et al: Jugular foramen schwannoma: analysis on its origin and location Otol Neurotol 29(3):387-91, 2008 Wilson MA et al: Jugular foramen schwannomas: diagnosis, management, and outcomes Laryngoscope 115(8):1486-92, 2005 Eldevik OP et al: Imaging findings in schwannomas of the jugular foramen AJNR Am J Neuroradiol 21(6):1139-44, 2000 10 Caldemeyer KS et al: The jugular foramen: a review of anatomy, masses, and imaging characteristics Radiographics 17(5):1123-39, 1997 P.V(1):37 Image Gallery 1171 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR shows a small left jugular foramen schwannoma Note the typical lack of high-velocity flow voids, which helps differentiate this lesion from the more common glomus jugulare paraganglioma (Right) Axial T1WI C+ FS MR in the same patient shows diffuse enhancement , a typical pattern for schwannoma When lesions are large, intramural cystic, nonenhancing components may be present Small lesions may be difficult to differentiate from jugular bulb asymmetry (Left) Axial bone CT shows the classic smooth enlargement of the jugular foramen with thin sclerotic margins in this patient with a jugular foramen schwannoma These bone changes can help differentiate this lesion from other common lesions of the jugular foramen, including glomus jugulare paraganglioma and meningioma (Right) Axial T2WI MR shows a hyperintense left skull base mass centered within the jugular foramen, consistent with a schwannoma Note the typical absence of flow voids 1172 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR shows a fusiform, homogeneously enhancing right jugular foramen schwannoma with extension into adjacent cistern Most of these patients have associated sensorineural hearing loss (Right) Coronal T1WI C+ FS MR shows a heterogeneously enhancing lobulated mass arising from jugular foramen Note typical superomedial vector of spread toward brainstem Large tumors like this may have nonenhancing components related to intramural cysts Jugular Foramen Meningioma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Jugular Foramen > Jugular Foramen Meningioma Jugular Foramen Meningioma Karen L Salzman, MD H Ric Harnsberger, MD Key Facts Terminology Benign neoplasm arising from arachnoid cap cells found along cranial nerves within jugular foramen Imaging Bone CT: Permeative-sclerotic JF margins T1WI C+ MR: Enhancing JF mass spreading along dural surfaces Enhancing dural “tails” may be seen No high-velocity flow voids Centrifugal vector of spread: Extends in all directions from JF along dural surfaces & through surrounding bones May protrude into basal cisterns or nasopharyngeal carotid space Top Differential Diagnoses Glomus jugulare paraganglioma Jugular foramen schwannoma Jugular foramen metastasis Jugular foramen pseudolesion Dehiscent jugular bulb Pathology Proliferation of arachnoid meningothelial cap cells along CNs 9-11 in JF Clinical Issues Risk factors Prior nasopharynx, skull base, or brain radiation; NF2; female sex hormones Meningioma is 3rd most common JF mass Paraganglioma > > schwannoma > meningioma Treatment: Complete surgical removal is goal Surgical cure often results in multiple lower cranial neuropathies Radiotherapy for elderly patients, poor surgical risk or subtotal resection 1173 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows a large jugular foramen meningioma invading the middle ear , skull base marrow , and internal auditory canal Note the cranial nerves of the jugular foramen (CN 9-11) are engulfed (Right) Coronal bone CT shows the characteristic permeative sclerotic changes along the jugular foramen margins of this jugular foramen meningioma This meningioma extends into the middle ear and may present clinically as a vascular retrotympanic mass on otoscopy (Left) Axial T1WI C+ FS MR shows a jugular foramen meningioma with en plaque morphology and dural “tails” Note the lack of flow voids and the jugular foramen involvement with extensive adjacent skull base infiltration (Right) Coronal T1WI C+ FS MR shows a large jugular foramen meningioma with a significant cerebellopontine angle component Jugular foramen meningiomas have a centrifugal vector of spread and often extend along dural surfaces and through the surrounding bones P.V(1):39 TERMINOLOGY Definitions Benign neoplasm arising from arachnoid cap cells found along cranial nerves within jugular foramen (JF) IMAGING General Features Best diagnostic clue Permeative-sclerotic involvement of bone around JF on CT Enhancing JF mass spreading centrifugally along dural surfaces on enhanced MR Location 1174 Diagnostic Imaging Head and Neck Centered within JF Vector of spread: Centrifugal pattern (“away from center”) Extends in all directions from JF along dural surfaces & through surrounding bones Dural-based spread into basal cistern most common May protrude into nasopharyngeal carotid space below Morphology Poorly circumscribed mass CT Findings NECT Hyperdense jugular foramen mass Bone CT Permeative-sclerotic JF margins MR Findings T1WI Hypo- to isointense JF mass compared to brain parenchyma No high-velocity flow voids T2WI Relative T2 hypointensity suggests dense histology T1WI C+ Dense, uniform contrast enhancement Enhancing dural “tails” may be visible along adjacent dural surfaces of basal cisterns MRV May occlude dural sinuses & jugular bulb Patency of adjacent dural sinuses should be documented prior to surgery Angiographic Findings Supply primarily from dural branches of external carotid artery & vertebral artery Angiography provides vascular road map for surgeon Evaluates collateral arterial & venous circulation Embolization used for preoperative hemostasis DIFFERENTIAL DIAGNOSIS Glomus Jugulare Paraganglioma Permeative-destructive JF bony margins on CT High-velocity flow voids (“pepper”) characteristic on MR Jugular Foramen Schwannoma Smooth enlargement of JF on CT Tubular JF mass on MR ± intramural cysts when large Jugular Foramen Metastasis Destructive bone margins of JF on CT Heterogeneously enhancing invasive JF mass on MR Jugular Foramen Pseudolesion Asymmetric JF MR signal suggests lesion JF bony margins intact on CT Complex JF signal does not persist on all MR sequences Dehiscent Jugular Bulb Superolateral extension of jugular bulb into middle ear Sigmoid plate focally dehiscent on CT PATHOLOGY General Features Etiology Meningioma arises from proliferation of arachnoidal cap cells of meninges May follow CNs 9-11 into JF Genetics Sporadic: Isolated defect on chromosome 22 Inherited: Associated with NF2 & systemic chromosome 22 abnormality Staging, Grading, & Classification Typical meningioma (90%): WHO grade I Atypical meningioma (7%): WHO grade II Anaplastic meningioma (3%): WHO grade III CLINICAL ISSUES 1175 Diagnostic Imaging Head and Neck Presentation Most common signs/symptoms CNs 9-11 neuropathy Demographics Age Typically 40-60 year old Gender F > M → 2:1 DIAGNOSTIC CHECKLIST Image Interpretation Pearls Large JF meningioma may mimic glomus jugulare paraganglioma SELECTED REFERENCES Toyama C et al: Primary jugular foramen meningioma Otol Neurotol 29(3):417-8, 2008 Hamilton BE et al: Imaging and clinical characteristics of temporal bone meningioma AJNR Am J Neuroradiol 27(10):2204-9, 2006 Dural Sinuses Dural Sinus & Aberrant Arachnoid Granulations > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Dural Sinuses > Dural Sinus & Aberrant Arachnoid Granulations Dural Sinus & Aberrant Arachnoid Granulations H Ric Harnsberger, MD Key Facts Terminology Arachnoid granulation (AG) Defined as enlarged arachnoid villi projecting into major dural venous sinus lumen Aberrant arachnoid granulation (AbAG) Defined as AG that penetrates dura but fails to reach venous sinus, typically in sphenoid bone Imaging Intrasinus AG: Well-circumscribed, discrete, filling defect in venous sinus ± inner calvarial table erosion CECT: Nonenhancing; density like CSF MR: T1/T2 intensity follows CSF; FLAIR often hyperintense AbAG: Multiple focal outpouches in sphenoid bone, often greater wing Bone CT: Multiple smooth pits in sphenoid bone MR: T1 and T2 intensity follows CSF 5-15 mm range in size Top Differential Diagnoses Dural sinus hypoplasia-aplasia Transverse-sigmoid sinus pseudolesion Dural sinus thrombosis, skull base Dural AV fistula, skull base Clinical Issues Intrasinus AG: Asymptomatic with rare exception If pressure gradient across giant AG of venous sinus, venous hypertension with headache possible Aberrant AG: Mostly asymptomatic If CSF pulsations enlarge AbAG in sphenoid sinus wall, CSF leak ± meningitis possible If significant cephalocele occurs, seizure possible 1176 Diagnostic Imaging Head and Neck (Left) Graphic shows a giant arachnoid granulation (AG) projecting from subarachnoid space into transverse sinus CSF core extends into the AG and is separated by arachnoid cap cells from the venous sinus endothelium Giant AGs often contain prominent venous channels and septations (Right) Axial CECT shows a giant arachnoid granulation cluster at the transverse-sigmoid venous sinus junction The 1st imaging interpretation of this finding mistakenly suggested venous sinus thrombosis (Left) Axial T1WI MR in the same patient reveals the multiple giant arachnoid granulations as low signal within the transverse and proximal sigmoid sinuses The medial low signal line is the dura (Right) Axial T2WI FS MR in the same patient demonstrates the lesion to be high signal similar to cerebrospinal fluid in the cerebellopontine angle cistern The low signal line on the deep surface of arachnoid granulations is the dura P.V(1):41 TERMINOLOGY Abbreviations Arachnoid granulation (AG) Aberrant arachnoid granulation (AbAG) Synonyms Pacchionian depressions, granulations, or bodies When large → giant arachnoid granulation When in sphenoid bone → AbAG Definitions AG: Enlarged arachnoid villi projecting into major dural venous sinus lumen AbAG: AG that penetrated dura but fails to reach venous sinus, typically in sphenoid bone 1177 Diagnostic Imaging Head and Neck Also referred to as arachnoid pits IMAGING General Features Best diagnostic clue Intrasinus AG: Discrete filling defect in venous sinus ± inner calvarial table erosion CECT: Nonenhancing; similar density to CSF MR: T1/T2 intensity follows CSF; often hyperintense on FLAIR AbAG: Multiple focal outpouches in sphenoid bone, often greater wing Bone CT: Multiple smooth pits in sphenoid bone MR: T1 and T2 intensity follows CSF Location Most common location: Transverse sinus Other locations: Sigmoid, sagittal, straight sinus AbAG location: Sphenoid bone, often greater wing, or lateral sinus wall Size 5-15 mm size range If > 15 mm, called “giant AG” Morphology Single or multiple ovoid lesions Focal osseous pits in inner table of calvarium CT Findings NECT Intrasinus AG isodense with CSF CSF pulsations may result in erosion or scalloping of inner table AbAG: Focal osseous erosions in sphenoid bone If large, may appear multilocular; mimic cystic bone lesion CECT Nonenhancing, ovoid focal filling defect within venous sinus Isodense to CSF AbAG: CSF density with subtle rim (dural) enhancement CT venogram Focal filling defect within venous sinus MR Findings T1WI Venous sinus defect isointense to CSF T2WI Hyperintense (like CSF) Surrounded by normal flow void of major venous sinus AbAG: High signal outpouching into sphenoid bone If large, may see arachnoid pouch bulging into sphenoid sinus lumen Arachnoid strands seen as low signal lines within pouch Larger lesions may have CSF leak into sphenoid sinus Larger lesions may have cephalocele associated T1WI C+ Intrasinus AG: Ovoid without enhancement surrounded by enhancing blood in dural sinus Veins, septae may enhance AbAG: Nonenhancing foci in sphenoid bone MRV Intrasinus AG Source images show focal signal loss in location of AG MRV reformation shows focal defect in affected sinus Imaging Recommendations Best imaging tool Intrasinus AG: Enhanced MR with MRV AbAG: Bone CT of skull base Enhanced MR focused to sphenoid bone area DIFFERENTIAL DIAGNOSIS Dural Sinus Hypoplasia-Aplasia Congenital hypoplastic-aplastic transverse sinus 1178 Diagnostic Imaging Head and Neck “High-splitting” tentorium Transverse-Sigmoid Sinus Pseudolesion Asymmetric complex flow phenomenon in sinus mimics lesions Not present on all sequences; MRV sorts out Dural Sinus Thrombosis, Skull Base Long-segment region of ↓ venous sinus flow NECT: Hyperdense CECT: Nonenhancing clot in venous sinus lumen MR: Hyperintense on T1 or lack of flow void on T2 Dural AV Fistula, Skull Base MR: Recanalized, irregular transverse-sigmoid sinuses Angio: Enlarged, feeding external carotid artery branches PATHOLOGY General Features Etiology Intrasinus AG: Normal variant enlarged arachnoid villi Arachnoid villi responsible for CSF resorption Aberrant AG: AG that penetrates dura but fails to reach venous sinus in sphenoid bone CSF pulsations suspected in enlarging AbAG causing arachnoid pouch bulging into bone With enlargement of arachnoid pouch, rupture results in CSF leak into sphenoid sinus P.V(1):42 Cephalocele may be accompanied by larger AbAG Gross Pathologic & Surgical Features AG: Smooth arachnoid granulation projecting into venous sinus or subarachnoid space Aberrant AG: Osteodural defects in lateral sphenoid sinus wall or greater wing of sphenoid Microscopic Features Enlarged arachnoid villi Central core of loose, peripheral zone of dense connective tissue Projects through dura of venous sinus wall CLINICAL ISSUES Presentation Most common signs/symptoms Intrasinus AG: Asymptomatic with rare exception If pressure gradient across giant AG of venous sinus, venous hypertension with headache is possible Aberrant AG: Mostly asymptomatic If CSF pulsations enlarge AbAG in sphenoid sinus wall, CSF leak ± meningitis possible If significant cephalocele occurs, seizure possible Other signs/symptoms Benign intracranial hypertension in obese middle-aged females with empty sella and spontaneous CSF rhinorrhea have been linked to aberrant AG expression Demographics Age ↑ in frequency with ↑ age; ≥ 40 years Epidemiology Intrasinus AG: 25% CECT or T2WI MR Aberrant AG: Rare; incidence unknown (< 1%) Natural History & Prognosis Intrasinus AG: Remains asymptomatic Aberrant AG: May remain small or enlarge from CSF pulsations to create CSF leak or cephalocele Treatment Intrasinus AG: No treatment required Aberrant AG: No treatment needed unless enlarged from CSF pulsation or CSF leak Can follow large, asymptomatic AbAG If CSF leak present into sphenoid sinus, surgical dural repair necessary DIAGNOSTIC CHECKLIST Consider If intrasinus giant AG with history of headache, consider angiogram to look for intrasinus pressure gradient 1179 Diagnostic Imaging Head and Neck If aberrant AG presents in lateral wall sphenoid bone, look for fluid in sphenoid sinus as evidence for CSF leak Also use MR to evaluate for possible associated cephalocele Image Interpretation Pearls Intrasinus AG Confirm AG remains CSF density (as seen with CECT or CT angiogram) and intensity (as seen with T1 and T2 MR sequences) Make sure proximal and distal venous sinus is normal from imaging perspective Aberrant AG in lateral sphenoid sinus wall If large or multiple, look for evidence of CSF leak (fluid or fluid level in sphenoid sinus) SELECTED REFERENCES Kiroglu Y et al: Giant arachnoid granulation in a patient with benign intracranial hypertension Eur Radiol 18(10):2329-32, 2008 La Fata V et al: CSF leaks: correlation of high-resolution CT and multiplanar reformations with intraoperative endoscopic findings AJNR Am J Neuroradiol 29(3):536-41, 2008 Lloyd KM et al: Imaging of skull base cerebrospinal fluid leaks in adults Radiology 248(3):725-36, 2008 Schuknecht B et al: Nontraumatic skull base defects with spontaneous CSF rhinorrhea and arachnoid herniation: imaging findings and correlation with endoscopic sinus surgery in 27 patients AJNR Am J Neuroradiol 29(3):542-9, 2008 Haroun AA et al: Arachnoid granulations in the cerebral dural sinuses as demonstrated by contrast-enhanced 3D magnetic resonance venography Surg Radiol Anat 29(4):323-8, 2007 Amlashi SF et al: Intracranial hypertension and giant arachnoid granulations J Neurol Neurosurg Psychiatry 75(1):172, 2004 Liang L et al: Normal structures in the intracranial dural sinuses: delineation with 3D contrast-enhanced magnetization prepared rapid acquisition gradient-echo imaging sequence AJNR Am J Neuroradiol 23(10):1739-46, 2002 Gacek RR et al: Adult spontaneous cerebrospinal fluid otorrhea: diagnosis and management Am J Otol 20(6):770-6, 1999 Casey SO et al: Prevalence of arachnoid granulations as detected with CT venography of the dural sinuses AJNR Am J Neuroradiol 18(5):993-4, 1997 10 Leach JL et al: Normal appearance of arachnoid granulations on contrast-enhanced CT and MR of the brain: differentiation from dural sinus disease AJNR Am J Neuroradiol 17(8):1523-32, 1996 11 Roche J et al: Arachnoid granulations in the transverse and sigmoid sinuses: CT, MR, and MR angiographic appearance of a normal anatomic variation AJNR Am J Neuroradiol 17(4):677-83, 1996 P.V(1):43 Image Gallery (Left) Lateral internal carotid artery angiogram clearly depicts multiple giant arachnoid granulations in the transverse and proximal sigmoid venous sinuses No intrasinus pressure gradient was present across the lesion (Right) Axial bone CT through the mid sphenoid sinus shows multiple ovoid bony defects in the greater wing of sphenoid bone representing aberrant arachnoid granulations (arachnoid pits) These arachnoid granulations may enlarge 1180 Diagnostic Imaging Head and Neck from CSF pulsations (Left) Axial bone CT reveals a multilocular lesion in the left greater wing of the sphenoid and basisphenoid The most likely etiology of this lesion is CSF pulsations enlarging aberrant arachnoid granulations (Right) Coronal CT cisternography in the same patient reveals contrast leaking from the subarachnoid space into the giant aberrant arachnoid granulations (Left) Axial T2WI MR in the same patient demonstrates CSF signal within the greater wing of the sphenoid bone and basi-sphenoid Arachnoid outpouching with arachnoid stranding can be seen within the giant aberrant arachnoid granulations (Right) Coronal T1WI C+ MR in the same patient shows fluid within the expanded pterygoid wing of sphenoid This represents CSF within an arachnoid pouch filling giant aberrant arachnoid granulations Skull Base Dural Sinus Thrombosis > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Dural Sinuses > Skull Base Dural Sinus Thrombosis Skull Base Dural Sinus Thrombosis C Douglas Phillips, MD, FACR Key Facts Terminology Abbreviation: Dural sinus thrombosis (DST) Imaging MR with MRV best single imaging exam for DST CT findings 1181 Diagnostic Imaging Head and Neck ↑ density thrombus in affected dural sinus Conforms to shape of sinus; fusiform enlargement acutely CECT → enhancing dura surrounding less dense thrombus MR findings ↓ signal (“blooming”) on T2* sequences in thrombus ↑ DWI in parenchymal venous infarction in temporal/occipital lobes or cerebellum Parenchymal hemorrhage more common than arterial infarct Top Differential Diagnoses Arachnoid granulation Physiologic sinus flow asymmetry Dural sinus hypoplasia-aplasia Subdural hematoma Pathology Wide variety of causes (> 100 identified) Otomastoiditis most common Pregnancy & oral contraceptives Trauma (temporal bone fracture) Metabolic (dehydration, thyrotoxicosis, cirrhosis) Clinical Issues Headache most common symptom: 70-90% Young female most common (autoimmune, oral contraceptives) ≤ 50% of DSTs progress to venous infarction (Left) Axial CECT shows sinus thrombosis secondary to oral contraceptive use A tubular filling defect represents thrombus in the right transverse sinus with enhancement of the anterior dura of the sinus The torcular enhances normally (Right) Sagittal T1WI MR demonstrates heterogeneous signal representing acute & subacute blood products within transverse sinus clot extending into the sigmoid sinus No evidence of temporal lobe infarction is seen 1182 Diagnostic Imaging Head and Neck (Left) Axial T2WI MR shows heterogeneous but largely high signal representing thrombus in the right transverse and sigmoid sinuses No abnormal signal is identified in the right cerebellar hemisphere that would suggest venous infarction (Right) Axial MRV in the same patient confirms the absence of flow-related signal in the thrombosed portions of the right transverse and sigmoid sinuses and confirms the patency of other dural sinuses and contralateral transverse and sigmoid sinuses P.V(1):45 TERMINOLOGY Abbreviations Dural sinus thrombosis (DST) Synonyms Cerebral venous sinus thrombosis, sinovenous thrombosis Definitions In situ thrombosis of posterior fossa dural venous sinus due to variety of causes IMAGING General Features Best diagnostic clue Increased density (CT) or abnormal signal intensity (MR) in affected dural sinus of posterior fossa Location Thrombophlebitis most commonly starts at transverse-sigmoid confluence DST may involve ≥ of following posterior fossa sinuses Torcular herophili Transverse sinus (TS) ± vein of Labbé Sigmoid sinus (SS) Jugular bulb Size In acute thrombosis, affected sinus may be enlarged Caveat: Transverse sinus size typically varies from side-to-side in an individual Morphology Conforms to shape of dural sinus affected Fusiform enlargement of venous structure acutely Important for distinguishing DST from arachnoid granulation (focal filling defect) CT Findings NECT ↑ density thrombus in affected dural sinus Dense triangle of thrombus, “delta” sign, if sinus seen in cross section Phrase used mainly to describe sagittal sinus thrombosis Sagittal CT reconstruction of TS or coronal reconstruction of SS could show “delta” sign Parenchymal venous infarction may be associated (≈ 1/3 of cases) Parenchymal hypodensity (edema ± infarction) 1183 Diagnostic Imaging Head and Neck Temporal or occipital lobe location with TS thrombosis Cerebellar hemisphere location with distal TS & sigmoid sinus (SS) thrombosis Cortical/subcortical hemorrhages (may be petechial) CECT “Reverse” or “empty delta” sign, enhancing dural leaves surrounding less dense thrombus (25% of cases) Filling defect in TS ± SS; may extend into jugular bulb or vein CECT alone unreliable for diagnosis of DST High-density clot may appear like patent enhancing sinus CTV 10-15 second delay beyond CTA image acquisition allowing venous timing for “CT venogram” Filling defect in dural venous sinus with surrounding dural enhancement MR Findings T1WI Acute DST: Absent flow void with isointense clot (similar to gray matter) Subacute DST: Hyperintense clot (methemoglobin) Chronic DST: Isointense clot T2WI Acute DST: Hypointense clot (deoxyhemoglobin) Subacute DST: Hyperintense clot Chronic DST: Hyperintense clot Additional findings if parenchymal infarction present Gyral swelling, sulcal effacement in temporal lobe Hyperintense if venous infarction is acute T2* GRE Profound hypointense signal or “blooming” on T2* sequences with acute or subacute thrombosis May be difficult to discern against bone, air (in adjacent temporal bone) Parenchymal hemorrhage in venous infarct ↓ signal in acute stage DWI Acute and subacute clot may demonstrate restricted diffusion Acute parenchymal venous infarct shows restricted diffusion Parenchymal DWI abnormalities are more likely reversible compared to arterial ischemic insults T1WI C+ Filling defect may nearly completely fill dural sinuses Peripheral enhancement may be reactive dura or residual flow around clot Chronic DST may enhance intensely and should be correlated with MRV findings Irregular enhancing venous channels may be seen with incomplete recanalization Enhancement within recanalized clot may mimic normal sinus enhancement Associated parenchymal venous infarction may show patchy enhancement MRV Lack of flow-related signal in TS-SS, ± jugular bulb Angiographic Findings Late venous phase images critical Complete lack of flow in affected dural sinuses Central filling defect with surrounding contrast Imaging Recommendations Best imaging tool MR with MRV best single imaging exam for DST Almost all MR sequences show signal abnormality in dural sinuses Complications (venous infarct, hemorrhage) easily identified Susceptibility weighted imaging (SWI) may prove to be useful technique Protocol advice P.V(1):46 Coronal & sagittal CTV reconstructions ± MRV sequences very helpful for TS & SS thrombosis evaluation Contrast-enhanced MRV decreases “false-positive DST” in small but patent dural sinus Use MRV with multiple encoding gradients to distinguish physiological flow asymmetry from thrombus DIFFERENTIAL DIAGNOSIS Arachnoid Granulation 1184 Diagnostic Imaging Head and Neck Focal ovoid filling defect extending into TS-SS CSF density (CT) & intensity (MR) Physiologic Sinus Flow Asymmetry Slow or asymmetric flow creates MR variable signal Normal Dural Sinus Flowing blood in normal, asymmetric dural sinus Slightly more dense than brain on NECT Not as dense as thrombus Dural Sinus Hypoplasia-Aplasia 33% of normal individuals with hypoplastic unilateral TS Congenitally small TS may show no flow or enhancement on MRV Sagittal T1 shows no TS structure along posterior tentorium No signal abnormality of small sinus on T2, FLAIR, or GRE Subdural Hematoma Subdural blood adjacent to TS-SS mimics clot within dural sinus “False reverse (empty) delta” sign PATHOLOGY General Features Etiology Most common cause: Otomastoiditis ± subdural empyema → dural sinus thrombophlebitis Wide variety of causes (> 100 identified) Pregnancy, oral contraceptives Trauma (temporal, occipital bone fracture adjacent to sinus); variable rate of DST depending on sinus involved Metabolic (dehydration, thyrotoxicosis, cirrhosis) Hematologic (coagulopathy) Associated abnormalities DST with arterial infarctions in patients with Behỗet disease CLINICAL ISSUES Presentation Most common signs/symptoms Headache (70-90%) May be confused clinically with idiopathic intracranial hypertension (pseudotumor cerebri) No diagnosis of pseudotumor cerebri should be made without venous evaluation Other signs/symptoms Nausea, vomiting, & papilledema Neurologic deficits & seizures Clinical profile Young woman with sudden onset unrelenting headache & ear infection or history of oral contraceptive use Demographics Age May be seen at any age Young female most common (autoimmune, oral contraceptives) Gender F>M Epidemiology 1% of acute stokes arise from DST Natural History & Prognosis ≤ 50% of DSTs progress to venous infarction Extension to straight sinus or vein of Labbé dramatically increases complication risk Temporal lobe infarction ± parenchymal hemorrhage Treatment Anticoagulation (heparin) is mainstay of therapy Endovascular thrombolysis may be utilized for subacute or chronic thrombosis or if lack of improvement with anticoagulation Treat inciting cause of thrombosis Antibiotics & mastoidectomy for acute otomastoiditis with thrombophlebitis, for example DIAGNOSTIC CHECKLIST 1185 Diagnostic Imaging Head and Neck Image Interpretation Pearls Use contralateral cortical veins, dural sinuses, or arterial structures for density comparison on NECT CECT may be misleading, may mask clot Reporting Tips Identify cause of DST if possible Identify which veins secondarily involved Identify complications SELECTED REFERENCES Leach JL et al: Partially recanalized chronic dural sinus thrombosis: findings on MR imaging, time-of-flight MR venography, and contrast-enhanced MR venography AJNR Am J Neuroradiol 28(4):782-9, 2007 Leach JL et al: Imaging of cerebral venous thrombosis: current techniques, spectrum of findings, and diagnostic pitfalls Radiographics 26 Suppl 1:S19-41; discussion S42-3, 2006 Rodallec MH et al: Cerebral venous thrombosis and multidetector CT angiography: tips and tricks Radiographics 26 Suppl 1:S5-18; discussion S42-3, 2006 Provenzale JM et al: Dural sinus thrombosis: findings on CT and MR imaging and diagnostic pitfalls AJR Am J Roentgenol 170(3):777-83, 1998 P.V(1):47 Image Gallery (Left) Axial NECT demonstrates high-attenuation thrombus in the left transverse sinus In a case like this, differentiation from subdural hematoma may be difficult MR imaging or CECT could be helpful for making that distinction (Right) Coronal MRV source image shows high signal from normal blood flow in the right sigmoid sinus Absence of flow-related signal in the contralateral sinus has resulted from dural sinus thrombosis 1186 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a patient with acute coalescent otomastoiditis complicated by dural sinus thrombosis shows thinning of the sigmoid plate and a small focus of air in the location of the sigmoid sinus (Right) Postcontrast head CT in the same patient depicts only peripheral enhancement of the dura around the sigmoid sinus The clot located within the sinus in this case is hypodense compared to the contrast Intracranial air is again noted adjacent to the thrombus (Left) Axial T2WI MR in the same patient shows inflammatory material in the mastoid and middle ear , as well as heterogeneous high signal in the sigmoid sinus A pertinent negative observation is the normal appearance of the temporal lobe and cerebellum (Right) Anteroposterior MRV (maximum intensity projection image) in the same patient demonstrates abrupt occlusion of the transverse sinus and lack of flow-related signal in the sigmoid sinus and jugular bulb/vein Cavernous Sinus Thrombosis > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Dural Sinuses > Cavernous Sinus Thrombosis Cavernous Sinus Thrombosis Laurie A Loevner, MD Key Facts Terminology Cavernous sinus thrombosis/thrombophlebitis (CST) CST = blood clot in CS Imaging Relevant anatomy CSs = trabeculated venous cavities 1187 Diagnostic Imaging Head and Neck Receive blood from multiple valveless veins Blood flows in any direction (depending on pressure gradient) CT findings often subtle or negative in CST Look for Enlarged CS with convex margins Filling defects in CS Enlarged superior ophthalmic vein ± clot, proptosis Enlarged extraocular muscles Top Differential Diagnoses Cavernous sinus neoplasm Meningioma, lymphoma, metastasis Cavernous carotid aneurysm, fistula Infection/inflammation Tolosa/Hunt, sarcoid, Wegener Pathology Often complication of sinusitis/midface infection S aureus most common pathogen Clinical Issues Headache most common early symptom Orbital pain, ophthalmoplegia, visual loss Diagnostic Checklist Clinical setting + high index of suspicion Negative CT → MR/MRV or CTA (Left) Axial T1WI MR shows enlargement of the right cavernous sinus with material isointense to gray matter There is mild narrowing of the cavernous internal carotid artery The patient presented with sphenoethmoidal sinusitis, headache, right 6th nerve palsy, and mild right proptosis (Right) Axial T2WI MR shows mild enlargement and a convex margin of the right cavernous sinus with heterogeneous, hyperintense tissue 1188 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ MR shows bilateral cavernous sinus thrombosis complicating acute pansinusitis There are filling defects within the cavernous sinuses consistent with clot There is prominent enhancement of the lateral dural margins of the CSs and bilateral proptosis due to venous congestion (Right) Axial DWI MR shows hyperintense clot in the bilateral cavernous sinuses P.V(1):49 TERMINOLOGY Abbreviations Cavernous sinus thrombosis/thrombophlebitis (CST) Definitions CST = blood clot in cavernous sinus (CS) IMAGING General Features Best diagnostic clue Appropriate clinical setting + high index of suspicion Location Relevant anatomy CSs = trabeculated venous cavities (not single pool of blood) Multiple venous interconnections Receive blood from multiple valveless veins Facial veins (via superior ophthalmic vein [SOV], inferior ophthalmic vein [IOV]) Sphenoid, deep middle cerebral veins CSs drain into inferior petrosal sinuses → IJVs Also superior petrosal sinuses → sigmoid sinuses Blood flows in any direction (depending on pressure gradient) Imaging Recommendations Best imaging tool CTA; MR ± contrast 1-3 mm sections through orbits, CSs CT Findings NECT Findings often subtle or negative CECT Filling defects in involved CS CS margins convex, not flat/concave Orbits: SOVs ↑ ± clot Proptosis, enlarged extraocular muscles CTA/CTV Filling defects in or both CSs MR Findings 1189 Diagnostic Imaging Head and Neck T1WI Convex, enlarged CS isointense to gray matter T2WI Heterogeneous high signal intensity in CS DWI May see hyperintense clot in CS T1WI C+ Variable; classic = filling defects in CS DIFFERENTIAL DIAGNOSIS Cavernous Sinus Neoplasm Meningioma, schwannoma Metastasis, lymphoma, invasive carcinomas Cavernous Carotid Aneurysm, Fistula “Flow voids” Infection/Inflammation Tolosa-Hunt, sarcoid, Wegener PATHOLOGY General Features Etiology Complication of sinusitis or infection Usually in midface (furuncle), orbits, or tonsils S aureus most common pathogen ± bacteremia Miscellaneous causes: Trauma Otomastoiditis, odontogenic infection Underlying malignancy CLINICAL ISSUES Presentation Most common signs/symptoms Headache most common early symptom Often localized to regions innervated by V1 and V2 Orbital pain, periorbital edema, chemosis Ptosis, ophthalmoplegia, visual loss Other signs/symptoms Hypoesthesia or hyperesthesia in V1 and V2 dermatomes Decreased pupillary responses Signs/sx in contralateral eye diagnostic of CST Meningeal signs Systemic signs indicative of sepsis are late findings Demographics Epidemiology S aureus ˜ 70% of infections S pneumoniae, gram-rods, anaerobes Fungi (Aspergillus, Rhizopus) rare Natural History & Prognosis Without therapy, signs appear in contralateral eye in 24-48 hours Spread via communicating veins to contralateral CS Can be fatal (death from sepsis or CNS involvement) Incidence/fatality significantly ↓ with early antibiotics Complete recovery infrequent Permanent visual impairment (15%) Cranial nerve deficits (50%) Treatment Intravenous antibiotics Supportive care, hydration, steroids DIAGNOSTIC CHECKLIST Image Interpretation Pearls Maintain high clinical suspicion Negative CT → MR/MRV or CTA SELECTED REFERENCES 1190 Diagnostic Imaging Head and Neck Agayev A et al: Images in clinical medicine Cavernous sinus thrombosis N Engl J Med 359(21):2266, 2008 Dural AV Fistula > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Dural Sinuses > Dural AV Fistula Dural AV Fistula C Douglas Phillips, MD, FACR Key Facts Terminology Dural arteriovenous fistula (dAVF) Acquired direct shunt between a dural artery and a dural venous sinus or cortical vein Imaging Best imaging modality: Digital subtraction angiography (DSA) Most common site → transverse sinus (TS) CECT findings in dAVF Tortuous, enhancing arterial feeders with enlarged dural sinus ± flow-related aneurysms MR findings in dAVF Localized or generalized venous dilatation Enlarged cortical draining veins → aggressive dAVF Focal hyperintensity in adjacent brain (venous perfusion abnormalities) Top Differential Diagnoses Hypoplastic transverse-sigmoid sinus (TS-SS) Jugular bulb pseudolesion Dural sinus thrombosis Pial arteriovenous malformation Clinical Issues Account for 35% of infratentorial vascular malformations TS-SS dAVF presents with pulsatile tinnitus Usually present in middle-aged, older patients Prognosis depends on location, venous drainage pattern Diagnostic Checklist If patient has objective pulsatile tinnitus and no other vascular lesion on cross-sectional imaging, angiography necessary to completely exclude dAVF (Left) Lateral graphic depicts a short segment of thrombosed transverse sinus with a dural arteriovenous fistula (dAVF) consisting of multiple dural vessels in the wall of the thrombosed segment Multiple dural & transosseous feeders arise from ECA & ICA (Right) Axial MRA demonstrates extensive prominent vascularity in the right skull base from a dAVF Source images from MRA should be carefully reviewed for correlation with MIP images The dural sinuses remain patent in this case 1191 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows multiple serpiginous canals that represent dAVF transosseous collaterals connecting the occipital artery to the recanalized transverse and sigmoid dural sinuses (Right) Lateral ECA arteriogram in the same patient reveals an enlarged occipital artery and meningeal arteries supplying a network of transosseous collaterals The sigmoid sinus is recanalized distal to the occluded segment P.V(1):51 TERMINOLOGY Abbreviations Dural arteriovenous fistula (dAVF) Synonyms Dural arteriovenous (AV) shunt, dural fistula Definitions Abnormal acquired direct shunt between a dural artery and a dural venous sinus or cortical vein Heterogeneous group of lesions with common angioarchitecture (AV shunts within dura) IMAGING General Features Best diagnostic clue Network of tiny (crack-like) vessels in wall of thrombosed dural venous sinus Location Skull base dural venous sinuses Most common site → transverse sinus (TS) 2nd most common → cavernous sinus (CS) Size Variable size, but actual shunt nidus usually < cm CT Findings NECT Usually normal in cases presenting without hemorrhage Subarachnoid, subdural, or parenchymal hemorrhage may be seen in cases presenting acutely with hemorrhage Parenchymal hemorrhage not in typical location for hypertensive bleed CECT If small, CECT normal Larger dAVFs show tortuous enhancing dural feeders with enlarged dural sinus ± flow-related aneurysms Dilated vessels in proximity to parenchymal hemorrhage (if present) Enlarged, tortuous cortical draining veins with aggressive dAVF Bone CT Transosseous collateral channels may be seen in area of occipitomastoid suture MR Findings T1WI May be normal 1192 Diagnostic Imaging Head and Neck Isointense thrombosed dural sinus ± “flow voids” T2WI Isointense thrombosed sinus ± “flow voids” Localized or generalized venous dilatation Focal hyperintensity in adjacent brain = retrograde leptomeningeal venous drainage, venous perfusion abnormalities T2* GRE Usually normal in uncomplicated dAVF May show parenchymal hemorrhage in dAVF with cortical venous drainage Thrombosed dural sinus will bloom DWI Normal unless venous infarct or ischemia present T1WI C+ Chronically thrombosed sinus enhances intensely Rare: Diffuse dural enhancement MRA Time-resolved contrast-enhanced MRA useful for depiction of angioarchitecture & dynamics TOF MRA positive in larger dAVF MRV Occluded involved sinus, collateral flow 3D phase contrast MRA with low-velocity encoding can identify fistula, feeding arteries, flow reversal in draining veins Angiographic Findings Conventional Most common site = wall of TS or SS (35-40%) Multiple arterial feeders are typical with dural/transosseous branches from ECA most commonly followed by ICA & vertebral artery (VA) tentorial/dural branches Arterial inflow into parallel venous channel (“recipient pouch”) common; may allow embolization with preservation of sinus Involved dural sinus often thrombosed Flow reversal in dural sinus/cortical veins correlates with ↑ symptoms, hemorrhage risk Tortuous engorged pial veins (“pseudophlebitic pattern”) with venous congestion/hypertension (clinically aggressive) High flow may result in high-flow vasculopathy with progressive stenoses, outlet occlusion, bizarre vascular appearance Imaging Recommendations Best imaging tool Digital subtraction angiography (DSA) with superselective catheterization of involved dural supply DIFFERENTIAL DIAGNOSIS Dural Sinus Hypoplasia-Aplasia Congenitally small transverse sinus (TS)-sigmoid sinus (SS) may have low flow on MRV, no enhancement on T1 C+ MR Sagittal T1WI shows no or very small sinus in normal anatomic location No signal abnormalities on T2, FLAIR, or GRE Sigmoid Sinus-Jugular Bulb Pseudolesion Slow or asymmetric flow creates variable signal on MR sequences Use MRV to clarify Thrombosed Dural Sinus Collateral/congested venous drainage can mimic dAVF Can be spontaneous, traumatic, infectious (thrombophlebitis) Pial Arteriovenous Malformation Congenital lesion with intraaxial nidus Pial arterial supply with possible parasitization of dural supply P.V(1):52 PATHOLOGY General Features Etiology 1193 Diagnostic Imaging Head and Neck Adult dAVFs are usually acquired, not congenital May be “idiopathic” Can occur in response to trauma, craniotomy, venous occlusion, or venous hypertension Associated abnormalities Cortical drainage may lead to edema, encephalopathy, hemorrhage Staging, Grading, & Classification Cognard classification of intracranial dAVFs correlates venous drainage pattern with clinical course Type I: Located in sinus wall, normal antegrade venous drainage, benign clinical course Type IIA: Located in main dural sinus, reflux into sinus but not cortical veins Type IIB: Reflux (retrograde drainage) into cortical veins, 10-20% hemorrhage rate Type III: Direct cortical drainage, no venous ectasia, 40% hemorrhage Type IV: Direct cortical drainage, venous ectasia, 65% hemorrhage Type V: Spinal perimedullary venous drainage, progressive myelopathy CLINICAL ISSUES Presentation Most common signs/symptoms major modes of presentation Due to hemorrhage (parenchymal, subarachnoid, or subdural) Hemorrhagic complications present acutely in stroke-like manner Due to venous hypertension/congestion (pulsatile tinnitus, dementia, seizures, encephalopathy) Nonhemorrhagic neurological presentations typically have subacute, slowly progressive onset Symptoms vary with site, type of shunt TS-SS → pulsatile tinnitus Cavernous sinus → pulsatile exophthalmos, chemosis, retroorbital pain Brainstem dAVF → quadriparesis, lower CN palsies Clinical profile Middle-aged patient with pulse-synchronous tinnitus Demographics Age Adult dAVFs usually present in middle-aged or older patients Epidemiology Rare, acquired lesions Account for 6% of supratentorial & 35% of infratentorial vascular malformations Account for 10-15% of all cerebrovascular malformations with AV shunting Natural History & Prognosis Prognosis, clinical course depends on location, venous drainage pattern 98% of dAVFs without retrograde venous drainage have benign course dAVFs draining into major dural sinus usually follow benign clinical course dAVFs with retrograde venous drainage (into arterialized leptomeningeal veins or cortical leptomeningeal veins) have aggressive clinical course Overall risk of hemorrhage from dAVF = 2% per year (depends on location & hemodynamics) Spontaneous closure rare Acute deterioration has been reported after lumbar puncture Treatment Observation Treatment options if hemorrhage risk exists Endovascular → embolization with particulates, liquid agents, coils Surgical resection → skeletonization of involved sinus Stereotaxic radiosurgery Recurrences occur despite definitive treatment, so long-term follow-up is required DIAGNOSTIC CHECKLIST Consider Dural AVFs are rare but treatable, so consider in patient with hemorrhage in atypical location for hypertensive bleed and no other cause If patient has objective pulsatile tinnitus & no other vascular lesion on cross-sectional imaging, DSA necessary to completely exclude dAVF Image Interpretation Pearls Single pedicle or small dAVF may not be seen even with focused MR with MRA 1194 Diagnostic Imaging Head and Neck Venous collateral flow in dural sinus thrombosis can become very prominent & mimic dAVF Reporting Tips Evaluate both internal, external carotid and vertebral arteries when performing angiography in patient with spontaneous intracranial hemorrhage Identification of associated venous varix is important as this finding signals ↑ risk of hemorrhage SELECTED REFERENCES Morales H et al: Documented development of a dural arteriovenous fistula in an infant subsequent to sinus thrombosis: case report and review of the literature Neuroradiology 52(3):225-9, 2010 Noguchi K et al: Intracranial dural arteriovenous fistulas: evaluation with combined 3D time-of-flight MR angiography and MR digital subtraction angiography AJR Am J Roentgenol 182(1):183-90, 2004 Burrows PE et al: Venous variations of the brain and cranial vault Neuroimaging Clin N Am 13(1):13-26, 2003 Kai Y et al: Pre- and post-treatment MR imaging and single photon emission CT in patients with dural arteriovenous fistulas and retrograde leptomeningeal venous drainage AJNR Am J Neuroradiol 24(4):619-25, 2003 P.V(1):53 Image Gallery (Left) Axial MRA MIP (maximum intensity projection) image reveals irregular flow-related enhancement in a partially recanalized transverse sinus with compact transosseous dAVF arterial supply (Right) Axial MRA source image in the same patient demonstrates numerous transosseous collateral vessels as linear areas of flow-related signal in the temporal bone Note the enlarged distal occipital artery and partially recanalized transverse sinus (Left) Anteroposterior MRV reveals that the left transverse & sigmoid sinus are smaller than the right with distal transverse sinus occlusion The distal transverse sinus-proximal sigmoid sinus is the most common site for dAVFs 1195 Diagnostic Imaging Head and Neck of posterior skull base (Right) Composite MR image shows atypical dAVF with innumerable small flow voids in the thrombosed segment of the transverse-sigmoid sinus junction MRA may show flow-related enhancement of vessels, but angiography is often necessary to confirm (Left) Axial MRA source image shows no evidence for vascularity within a large temporal lobe hemorrhage A high index of suspicion for a potential dAVF led to an arteriographic study (Right) Lateral angiography in the same patient shows an enlarged meningohypophyseal trunk and multiple transosseous perforating feeders from occipital artery draining into a short patent segment of the transverse sinus with distal occlusion of the sinus Diffuse or Multifocal Skull Base Disease Skull Base Cephalocele > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Cephalocele Skull Base Cephalocele Bernadette L Koch, MD Key Facts Terminology Basal cephalocele = congenital extracranial herniation of meninges, CSF, ± brain tissue through mesodermal defect in sphenoid, ethmoid, or basiocciput Imaging Nasopharyngeal Transethmoid: Defect in cribriform plate Sphenoethmoid: Bony defect junction of cribriform plate and planum sphenoidale Sphenonasopharyngeal = trans-sphenoid: Defect in body of sphenoid bone; most common Basioccipital-nasopharyngeal (trans-basioccipital): Bony defect parallel & inferior to sphenooccipital synchondrosis (area of median basal canal) Sphenoorbital Sphenomaxillary Best imaging tool MR best identifies meninges, CSF, brain, pituitary, and optic nerves/chiasm position Bone CT defines osseous defects prior to surgery Top Differential Diagnoses Nasal glioma Nasal dermal sinus Nasolacrimal duct mucocele Teratoma Clinical Issues Most common signs/symptoms May be clinically occult 1196 Diagnostic Imaging Head and Neck Hypertelorism, nasal mass, nasal stuffiness, endocrine dysfunction Recurrent meningitis (Left) Sagittal T1WI MR in a 3-day-old boy with a nasal mass shows CSF signal intensity trans-sphenoidal meningocele protruding into the nasopharynx via a skull base defect in the floor of the sella Notice posterior pituitary hyperintensity in the dorsal aspect of the sella (Right) Sagittal T1WI MR in the same child at months of age demonstrates increase in size of the cephalocele , a defect anterior to the sphenooccipital synchondrosis , and associated callosal agenesis (Left) Coronal T2WI MR in an 18-month-old boy reveals a large meningocele extending into the nasopharynx through a large osseous defect in the sphenoid (Right) Sagittal T1WI MR shows a trans-sphenoidal cephalocele in the location of the craniopharyngeal canal, anterior to the sphenooccipital synchondrosis The adenohypophysis is compressed in the dorsal aspect of the cephalocele , and neurohypophysis is likely along the posterior superior border P.V(1):55 TERMINOLOGY Synonyms Basal cephaloceles “Occult” cephaloceles Definitions Basal cephalocele = congenital extracranial herniation of meninges, CSF ± brain tissue through mesodermal defect in sphenoid, ethmoid, or basiocciput 1197 Diagnostic Imaging Head and Neck Nasopharyngeal Transethmoid Sphenoethmoid Sphenonasopharyngeal = trans-sphenoid (large craniopharyngeal canal) Basioccipital-nasopharyngeal (trans-basioccipital) Sphenoorbital Sphenomaxillary IMAGING General Features Best diagnostic clue Midline inferior herniation of CSF ± brain or pituitary gland into nasopharynx through defect in skull base Location Nasopharyngeal Transethmoid: Bone defect in cribriform plate Sphenoethmoid: Bony defect at junction of cribriform plate & planum sphenoidale Sphenonasopharyngeal = trans-sphenoid = craniopharyngeal canal Bony defect in body of sphenoid bone Basioccipital-nasopharyngeal (trans-basioccipital) Bony defect parallel and 1-1.5 cm inferior to sphenooccipital synchondrosis In area of persistent median basal canal May simulate patent sphenooccipital synchondrosis Communicates with prepontine cistern Sphenoorbital Posterior orbital cephaloceles communicate with middle cranial fossa through optic foramen, superior orbital fissure, or orbital wall defect Sphenomaxillary Extend through superior orbital fissure into posterior orbit ± extension through inferior orbital fissure and pterygopalatine fossa Size Variable Morphology Well circumscribed, round or ovoid Imaging Recommendations Best imaging tool MR best identifies meninges, CSF, brain, pituitary, and optic nerves/chiasm position Bone CT complimentary to define osseous defects prior to surgery Protocol advice Thin (3 mm) multiplanar T1 & T2 MR CT Findings NECT Variable attenuation mass protruding into nasopharynx Most commonly CSF attenuation Bone CT Depicts osseous defect in skull base MR Findings Mass with variable signal intensity protruding into nasopharynx or oropharynx Depends on amount of CSF, meninges, and brain tissue present Pituitary gland variable location within cephalocele Frequently lines posterior wall of cephalocele No abnormal enhancement Presence of enhancement may suggest infection/inflammation DIFFERENTIAL DIAGNOSIS Nasal Glioma Well-defined soft tissue mass No intracranial extension Nasal Dermal Sinus ± fluid-filled cyst anywhere from tip of nose to foramen cecum ± bifid crista galli Nasolacrimal Duct Mucocele 1198 Diagnostic Imaging Head and Neck Round intranasal cyst with enlarged nasolacrimal canal & cystic enlargement of lacrimal sac Unilateral or bilateral Teratoma Oropharyngeal location Mixed cystic/solid mass with soft tissue, fat, & calcium PATHOLOGY General Features Etiology Majority congenital, rarely post-traumatic Osseous defect secondary to faulty separation of neurectoderm from surface ectoderm during neural tube formation Prevents mesodermal tissue, which should form bone, from interposing between germ layers Genetics Sporadic No well-defined genetic link Associated abnormalities Callosal dysgenesis Eye abnormalities: Optic pits or posterior coloboma Midline facial clefts: Lip, nose, palate Rare reports ICA dysgenesis Epignathus teratoma Hypothalamic hamartoma Staging, Grading, & Classification Cephaloceles classified by contents of sac Meningoceles contain leptomeninges and CSF P.V(1):56 Meningoencephaloceles contain leptomeninges, CSF, & brain Atretic cephaloceles formes fruste of cephaloceles, i.e., small, noncystic, flat nodules in scalp Parietal are near vertex, occipital are cephalic to external occipital protuberance Glioceles contain glial-lined cyst and CSF Cephaloceles classified by site of osseous defect Calvarium Occipitocervical, occipital, parietal, lateral, interfrontal, temporal Skull base Frontoethmoidal = sincipital Nasofrontal, nasoethmoidal and nasoorbital Basal cephaloceles Nasopharyngeal: Transethmoid, sphenoethmoid, sphenonasopharyngeal (transsphenoid or craniopharyngeal canal), basioccipital-nasopharyngeal (transbasioccipital) Sphenoorbital Sphenomaxillary Gross Pathologic & Surgical Features Well-defined, meningeal-lined mass containing CSF ± brain tissue Microscopic Features Meningoceles: Leptomeninges & CSF Meningoencephaloceles: Leptomeninges, CSF, & brain Atretic cephaloceles: Dura, fibrous tissue, & degenerated brain tissue Glioceles: Glial-lined cyst containing CSF CLINICAL ISSUES Presentation Most common signs/symptoms May be clinically occult Hypertelorism Nasal mass & nasal stuffiness 1199 Diagnostic Imaging Head and Neck Endocrine dysfunction Other signs/symptoms Recurrent meningitis Highest incidence in patients with basioccipital-nasopharyngeal cephalocele Developmental delay primarily related to associated malformations Demographics Age Congenital lesion May be recognized on prenatal US/MR or present after birth Natural History & Prognosis Present at birth May not be diagnosed at birth due to occult location May increase in size rapidly if CSF-filled Prognosis depends in part on associated abnormalities Treatment Combined surgical procedure may involve neurosurgery, otolaryngology, &/or plastic surgery Recent success with endoscopic repair DIAGNOSTIC CHECKLIST Consider Look for cephalocele in patients with recurrent meningitis history High-resolution sagittal & coronal T1 & T2 images for optimal evaluation of contents of mass and contiguity with intracranial space Bone CT defines osseous defect prior to surgical repair Reporting Tips Identify lesion contents and osseous defect prior to surgical repair Recognize associated intracranial and craniofacial abnormalities SELECTED REFERENCES Borges A: Imaging of the central skull base Neuroimaging Clin N Am 19(4):669-96, 2009 Castelnuovo P et al: Endoscopic endonasal management of encephaloceles in children: an eight-year experience Int J Pediatr Otorhinolaryngol 73(8):1132-6, 2009 Lesavoy MA et al: Nasopharyngeal encephalocele: report of transcranial and transpalatal repair with a 25-year follow-up J Craniofac Surg 20(6):2251-6, 2009 Lee TJ et al: Endoscopic treatment of traumatic basal encephaloceles: a report of cases J Neurosurg 108(4):72935, 2008 Schuknecht B et al: Nontraumatic skull base defects with spontaneous CSF rhinorrhea and arachnoid herniation: imaging findings and correlation with endoscopic sinus surgery in 27 patients AJNR Am J Neuroradiol 29(3):542-9, 2008 Gupta DK et al: Transethmoidal transpharyngeal nasal encephalocele: Neuroimaging Pediatr Neurosurg 42(5):3357, 2006 Kizilkilic O et al: Hypothalamic hamartoma associated with a craniopharyngeal canal AJNR Am J Neuroradiol 26(1):65-7, 2005 Woodworth BA et al: Evolutions in the management of congenital intranasal skull base defects Arch Otolaryngol Head Neck Surg 130(11):1283-8, 2004 Ekinci G et al: Transsphenoidal (large craniopharyngeal) canal associated with a normally functioning pituitary gland and nasopharyngeal extension, hyperprolactinemia, and hypothalamic hamartoma AJR Am J Roentgenol 180(1):76-7, 2003 10 Castillo M et al: Imaging of orofacial clefting disorders Neuroimaging Clin N Am 10(1):253-69, x, 2000 11 Blustajn J et al: Dysgenesis of the internal carotid artery associated with transsphenoidal encephalocele: a neural crest syndrome? AJNR Am J Neuroradiol 20(6):1154-7, 1999 12 Daniilidis J et al: Intrasphenoidal encephalocele and spontaneous CSF rhinorrhoea Rhinology 37(4):186-9, 1999 13 Hughes ML et al: Persistent hypophyseal (craniopharyngeal) canal Br J Radiol 72(854):204-6, 1999 14 Madeline LA et al: Postnatal development of the central skull base: normal variants Radiology 196(3):757-63, 1995 15 Koch BL et al: Congenital malformations causing skull base changes Neuroimaging Clin N Am 4(3):479-98, 1994 16 Naidich TP et al: Cephaloceles and related malformations AJNR Am J Neuroradiol 13(2):655-90, 1992 17 Nager GT: Cephaloceles Laryngoscope 97(1):77-84, 1987 P.V(1):57 1200 Diagnostic Imaging Head and Neck Image Gallery (Left) Sagittal T1WI MR in an 18-month-old boy shows a large trans-sphenoidal cephalocele occluding the nasopharynx, anterior to the sphenooccipital synchondrosis The pituitary gland is not identifiable; the corpus callosum is dysplastic There is associated Chiari configuration of the cerebellar tonsil (Right) Sagittal T2WI MR in the same child shows similar findings of skull base cephalocele , corpus callosum dysgenesis , and lowlying cerebellar tonsil (Left) Coronal CECT in a day old with a nasal mass shows a trans-sphenoidal cephalocele extending into the nasopharynx via a large skull base defect On this image, the contents of the cephalocele appear to be predominantly CSF MR is better for determining the nature of the contents (Right) Axial CECT in the same child shows hypertelorism secondary to the cephalocele extending through the skull base defect and a well-defined optic nerve coloboma 1201 Diagnostic Imaging Head and Neck (Left) Coronal NECT defines a defect in the roof of the partially opacified right sphenoid sinus in a teenager In this case, the skull defect was related to previous head trauma, and the patient had a post-traumatic CSF leak (Right) Sagittal T1WI MR in the same patient better defines the nature of the cephalocele herniating through a skull base defect into the sphenoid sinus It contains posterior inferior frontal lobe tissue and a large amount of CSF Skull Base CSF Leak > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base CSF Leak Skull Base CSF Leak Patricia A Hudgins, MD Key Facts Imaging Best clue: Anterior or central SB defect on bone CT with positive β2-transferrin test on nasal secretions Anterior skull base bone CT findings Bone defect in cribriform plate, lateral lamella of middle turbinate or ethmoid roof Other evidence for fracture, functional endoscopic sinus surgery (FESS), congenital cephalocele Central skull base bone CT findings Bone defect in sella floor (transnasal pituitary surgery, craniopharyngeal canal persistence), lateral wall sphenoid (arachnoid granulation) Top Differential Diagnoses Vasomotor rhinitis Skull base defect without CSF leak Pathology Congenital CSF leak Cribriform plate defect, congenital cephalocele, persistent craniopharyngeal canal Acquired leak: From arachnoid granulation (pit, osteodural defect) or “spontaneous” Lateral roof of sphenoid sinus Post-traumatic leak: Can occur with any sinonasal fx Roof or lateral wall of sphenoid sinus, or cribriform plate/ethmoid roof Postoperative defect: Can occur after any sinonasal or anterior or central SB surgery Clinical Issues Rhinorrhea with Valsalva or head down maneuvers β2-transferrin is single best test to confirm fluid from nose is CSF Persistent CSF leaks endoscopically repaired 1202 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows large bony defect in left ethmoid roof, lateral to insertion of middle turbinate Because there is complete opacification of the ethmoid cells, an MR was performed that showed meningoencephalocele (Right) Coronal bone CT after intrathecal contrast placement shows accumulation of CSF in left sphenoid chamber, bone defect , and contrast extending through defect CT-cisternography is rarely necessary when high-resolution bone CT & MR are performed 1st for CSF leak (Left) Coronal T2WI MR reveals lateral wing of sphenoid sinus filled with CSF Note the osseous defect in roof of lateral sphenoid roof , and brain herniating through defect This woman had a “spontaneous” CSF leak Many such leaks are caused by large arachnoid granulations (Right) Coronal T1WI C+ MR in the same patient shows peripheral enhancement on the margin of the sphenoid meningoencephalocele Note diffuse thin dural enhancement , including at the defect site, secondary to leak P.V(1):59 IMAGING General Features Best diagnostic clue Anterior or central skull base (SB) defect on bone CT, ± fluid level or opacified sinus with positive β2transferrin test on nasal secretions Location Anterior SB: Cribriform plate, lateral lamella, ethmoid roof (fovea ethmoidalis) Central SB: Sella floor, lateral sphenoid sinus wall in pneumatized inferolateral recess Imaging Recommendations Best imaging tool 1203 Diagnostic Imaging Head and Neck Bone CT with multiplanar reformations Large defects easily visualized on multiplanar CT obviating need for CT-cisternography Small, < mm defects difficult to see, especially if present in bone that is normally thin May require CT-cisternography MR used if cephalocele suspected CT-cisternogram indicated if > potential site of leak or CSF leak with no site seen on bone CT Positive study much more likely if patient leaking day of study Be sure to CT scan prone after cisternogram portion to best see contrast column extending from subarachnoid space into sinus cavity CT Findings Bone CT Anterior skull base Bone defect in cribriform plate, lateral lamella of middle turbinate or ethmoid roof Other evidence for fracture, functional endoscopic sinus surgery (FESS), congenital cephalocele Central skull base Bone defect in sella floor (transnasal pituitary surgery, craniopharyngeal canal persistence), lateral wall sphenoid (arachnoid granulation) MR Findings T2WI Osseous defect, fluid in sinus cavity “Traction” encephalomalacia at leak site, especially if cephalocele present T1WI C+ Dural enhancement at defect site common Does not always mean infection DIFFERENTIAL DIAGNOSIS Vasomotor Rhinitis Rhinorrhea from sinuses with negative β2-transferrin Skull Base Defect Without CSF Leak Not all bony defects leak PATHOLOGY General Features Etiology Congenital CSF leak: Cribriform plate defect, congenital cephalocele, persistent craniopharyngeal canal Acquired leak: Large arachnoid granulation (pit, osteodural defect) or “spontaneous” leak Most common at lateral roof of sphenoid sinus just lateral to foramen rotundum Post-traumatic leak: Can occur with any fracture (fx) of sinus or nose wall Most commonly seen at roof or lateral wall of sphenoid sinus, or cribriform plate/ethmoid roof Postoperative defect: Can occur after any sinonasal or anterior or central SB surgery Following FESS at cribriform plate, lateral lamella or ethmoid roof Following trans-sphenoidal hypophysectomy in sella floor Associated abnormalities Cephalocele can be associated with herniation of meninges or brain through osseous defect CLINICAL ISSUES Presentation Most common signs/symptoms Rhinorrhea, especially with Valsalva or head down maneuvers β2-transferrin single best test to confirm fluid from nose is CSF Demographics Age Spontaneous leaks most common in middle-aged, obese women Natural History & Prognosis Post-traumatic CSF leaks: Usually resolve spontaneously due to scarring at SB defect “Spontaneous” CSF leak: Usually secondary to idiopathic intracranial hypertension with arachnoid granulation enlargement Leak may recur unless intracranial pressure ↓ with shunt Treatment Persistent CSF leaks endoscopically repaired Fascia-bone graft placed on intracranial side of defect DIAGNOSTIC CHECKLIST 1204 Diagnostic Imaging Head and Neck Consider If risk factors for CSF leak are known, any sinus chamber opacification should be assessed on coronal images for SB defect Image Interpretation Pearls If β2-transferrin of nasal fluid is positive, carefully assess skull base on bone CT (indicates leak) SELECTED REFERENCES Lloyd KM et al: Imaging of skull base cerebrospinal fluid leaks in adults Radiology 248(3):725-36, 2008 Skull Base Fibrous Dysplasia > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Fibrous Dysplasia Skull Base Fibrous Dysplasia C Douglas Phillips, MD, FACR Key Facts Terminology Fibrous dysplasia (FD) Congenital disorder with defect in osteoblastic differentiation & maturation, resulting in progressive replacement of normal cancellous bone by mixture of fibrous tissue & immature woven bone Imaging May affect calvarium, skull base, & facial bones Density (CT) & signal (MR) appearance highly variable CT findings Expansile lesion centered in medullary space with variable attenuation Sclerotic FD: “Ground-glass” density Pagetoid FD: Mixed lucent & sclerotic areas Cystic FD: Centrally lucent with thin sclerotic borders MR findings Low signal in ossified ± fibrous portions of lesion Variable enhancement depending on lesion pattern Top Differential Diagnoses Paget disease Ossifying fibroma Meningioma Skull base metastasis Pathology Contains fibrous tissue with interspersed trabeculae of immature woven bone that resemble “Chinese letters” Clinical Issues presentations: Monostotic, polyostotic, & McCune-Albright syndrome (Left) Lateral radiograph in a patient with McCune-Albright syndrome shows diffuse fibrous dysplasia involvement of the skull base Note the “ground-glass” expansion of the facial and sphenoid bones (Right) Coronal bone CT demonstrates expansion of the facial bones and sphenoid with a monotonous “ground-glass” appearance Note the 1205 Diagnostic Imaging Head and Neck normal cortical and medullary appearance of pterygoid processes images confirmed polyostotic disease and uninvolved segments of mandible Other (Left) Axial bone CT shows fibrous dysplasia involving the temporal bone with a smooth, expanded appearance of the bone The petrous temporal bone is extensively involved with sparing of the inner ear structures The more posterior-lateral component shows the classic ground-glass density (Right) Axial T1WI C+ FS MR in the same patient demonstrates enhancement of entire extent of the involved petrous bone In this case, the enhancement is diffuse and homogeneous P.V(1):61 TERMINOLOGY Abbreviations Fibrous dysplasia (FD) Synonyms Craniofacial fibrous dysplasia (CFD), osteitis fibrosa, osteodystrophy fibrosa McCune-Albright syndrome Jaffe-Lichtenstein dysplasia Definitions Congenital disorder with defect in osteoblastic differentiation & maturation, resulting in progressive replacement of normal cancellous bone by mixture of fibrous tissue & immature woven bone IMAGING General Features Best diagnostic clue “Ground-glass” matrix in expansile bone lesion on bone CT Location Affects any bone including skull, skull base, & facial bones Often > bone involved Size Polyostotic lesions may be massive Morphology Expanded bone Radiographic Findings Radiography Expanded thickened bone with “ground-glass” density May be accompanied by areas of sclerosis or lucency CT Findings NECT Appearance varies with relative content of fibrous vs osseous tissue Expansile lesion with abrupt transition zone between lesion & normal bone typical CECT Enhancement often difficult to appreciate except in areas of lucent bone 1206 Diagnostic Imaging Head and Neck Bone CT Bone CT shows expansile lesion centered in medullary space with variable attenuation Pagetoid (mixed) pattern (50%): Mixed radiopacity & radiolucency Sclerotic FD (25%): “Ground-glass” density Cystic FD (25%): Centrally lucent lesions with thinned but sclerotic borders MR Findings T1WI Expansile mass with ↓ signal in ossified ± fibrous portions of lesion T2WI Low signal in ossified ± fibrous portions of lesion In active phase, heterogeneous signal pattern often present T1WI C+ Variable enhancement depending on lesion pattern None, rim, or diffuse Impressive enhancement may also be seen in fibrous areas MRA Vascular narrowing or displacement where affected bone encroaches on arterial vascular canals/foramina MRV Vascular narrowing or displacement where affected bone encroaches on venous vascular canals/foramina Nuclear Medicine Findings Bone scan Nonspecific; sensitive to extent of skeletal lesions in polyostotic FD Increased radionuclide accumulation, perfusion & delayed bone phase PET Accumulation of [11C]methyl-L-methionine on PET Can be variably hot on FDG PET Imaging Recommendations Best imaging tool Bone CT best for most cases Protocol advice T1 C+ FS MR in complicated cases (cranial neuropathy, suspected malignant transformation) DIFFERENTIAL DIAGNOSIS Paget Disease Typically presents in elderly Involves T-bone & calvarium more frequently than craniofacial area “Cotton-wool” CT appearance Ossifying Fibroma May mimic cystic form of FD Thick, bony rim & lower density center Tends to appear more mass-like & localized than FD Meningioma Intraosseous meningioma may mimic FD En plaque soft tissue mass may be evident on enhanced MR Skull Base Metastasis Mixed sclerotic-destructive may mimic FD Prostate & breast carcinoma most common primary tumors to metastasize to skull base Chondrosarcoma Centered on petro-occipital fissure Arc or ring-like matrix calcifications on bone CT Hyperintense on T2WI MR Giant Cell Tumor May mimic sclerotic FD Hypointense on T2 MR due to hemosiderin deposition More intense enhancement on MR than FD P.V(1):62 1207 Diagnostic Imaging Head and Neck PATHOLOGY General Features Etiology Benign tumor-like lesion of bone with local arrest of normal structural/architectural development Genetics Sporadic mutation of GNAS1 gene All cells descended from mutated cell line can manifest features of monostotic or polyostotic FD Associated abnormalities Aneurysmal bone cysts Multiple endocrine disorders may be seen with severe polyostotic form Staging, Grading, & Classification Monostotic vs polyostotic Specific lesion type relates to disease activity Pagetoid Sclerotic Cystic Gross Pathologic & Surgical Features Tan-yellow to white mass Rubbery to gritty consistency depending on fibrous vs osseous content Microscopic Features Fibrous tissue with interspersed trabeculae of immature woven bone that resemble “Chinese letters” Fibrous stroma is myxofibrous tissue of mixed vascularity CLINICAL ISSUES Presentation Most common signs/symptoms Symptoms depend on lesion location Temporal bone: Conductive hearing loss; EAC stenosis; CN7 weakness Orbital: Proptosis, optic neuropathy 2° to optic nerve compression Sinonasal: Ostial obstruction → mucocele formation Other signs/symptoms Pain, focal swelling, tenderness Leontiasis ossea (lion facies) with extensive facial bone involvement Alters facial & calvarial contours Obstructs sinuses Complex cranial neuropathy possible from foraminal encroachment Clinical profile presentations: Monostotic, polyostotic, & McCune-Albright syndrome Monostotic FD (70%) Single osseous site affected Older children & young adults (75% present before age 30) Skull base & face involved in 25%; maxilla (especially zygomatic process) & mandible (molar area) > > frontal bone > ethmoid & sphenoid bones > T-bone May be asymptomatic, incidental finding Polyostotic FD (25%) Involves ≥ separate osseous sites Skull base & face involved in 50% Younger patients (mean age at diagnosis years) 2/3 have symptoms, including craniofacial asymmetry, by age 10 McCune-Albright syndrome (MAS) (3-5%) Polyostotic FD (usually unilateral) Associated with endocrine dysfunction (precocious puberty) & cutaneous hyperpigmentation (café au lait spots) Appears earlier & affects more bones more severely Demographics Age Most < 30 years Gender M:F = 1:2 MAS usually female 1208 Diagnostic Imaging Head and Neck Epidemiology One of most common fibroosseous lesions Monostotic FD 6x more common than polyostotic FD Polyostotic form more likely to have calvarial involvement Natural History & Prognosis Monostotic craniofacial FD has excellent prognosis Often ceases to progress after puberty Polyostotic FD rarely life threatening but has poor prognosis May progress beyond 3rd decade Malignant (sarcomatous) transformation of FD is rare (< 0.5% of cases) Osteosarcoma most common Treatment Aggressive surgical management typically not recommended Radiation therapy generally avoided (may cause malignant transformation) Bisphosphonate therapy may ameliorate course (↓ pain & fractures) DIAGNOSTIC CHECKLIST Image Interpretation Pearls Classic appearance → “ground-glass” on bone CT; ↓ signal on T2WI MR SELECTED REFERENCES Wei YT et al: Fibrous dysplasia of skull J Craniofac Surg 21(2):538-42, 2010 Lisle DA et al: Imaging of craniofacial fibrous dysplasia J Med Imaging Radiat Oncol 52(4):325-32, 2008 Adada B et al: Fibrous dysplasia of the clivus Neurosurgery 52(2):318-22; discussion 323, 2003 Chong VF et al: Fibrous dysplasia involving the base of the skull AJR Am J Roentgenol 178(3):717-20, 2002 Jee WH et al: Fibrous dysplasia: MR imaging characteristics with radiopathologic correlation AJR Am J Roentgenol 167(6):1523-7, 1996 P.V(1):63 Image Gallery (Left) Axial bone CT in a patient with polyostotic FD shows mixed lucent and sclerotic pattern of bone involvement Note the abrupt transition of imaging appearance at a suture , characteristic of FD (Right) Coronal bone CT in the same patient shows expanded mixed density within the temporal bone Involvement of sphenoid bone is also noted with expansion into basisphenoid A predominantly cystic (fibrous) focus of FD involvement is seen in the mandibular body 1209 Diagnostic Imaging Head and Neck (Left) Axial bone CT demonstrates mixed sclerotic and lucent fibrous dysplasia affecting the sphenoid bone and maxilla Note the narrowing of the left pterygomaxillary fissure A cortical defect along the maxilla represents previous biopsy (Right) Coronal bone CT shows extensive FD involvement of the sphenoid and pterygoid processes Narrowing of the left vidian canal and displacement and minimal narrowing of left foramen rotundum are noted (Left) Axial bone CT shows bony expansion and sclerosis and “ground-glass” density in the left greater sphenoid wing Note the abrupt change to normal-appearing bone at the left sphenotemporal suture , typical of fibrous dysplasia (Right) Axial T2WI FS MR in the same patient shows predominantly hypointense signal in the affected bone MR signal characteristics and enhancement can be highly variable on MR imaging depending on the amount of fibrous vs sclerotic tissue Skull Base Paget Disease > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Paget Disease Skull Base Paget Disease C Douglas Phillips, MD, FACR Key Facts Terminology Primary metabolic bony disease of unknown etiology Imaging CT findings Bone CT is most demonstrative of mixed sclerosis and lysis 1210 Diagnostic Imaging Head and Neck Well-defined lytic regions with expansion of bone in early phase disease “Cotton wool” appearance in later lytic-sclerotic phase MR findings T1WI: Hypointense signal due to fibrovascular replacement of marrow space Heterogeneous enhancement due to hypervascular nature of new bone Top Differential Diagnoses Fibrous dysplasia Skull base metastasis Osteopetrosis Osteogenesis imperfecta Pathology 15-20% of patients have 1st-degree relative with disease Mutations have been identified in familial & some sporadic cases Clinical Issues Common presentation: Expansile, lytic & sclerotic bony disease of axial skeleton and skull in elderly male patient Hearing loss if temporal bone involvement Malignant transformation in < 1% of cases (Left) Axial bone CT of the skull base shows Paget disease with diffuse expansion and hyperdensity of skull base and a “fluffy” appearance of the abnormally thickened bone The process also involves the temporal bones and otic capsules (Right) Axial bone CT in the same patient demonstrates the extensive nature of the disease with diffuse irregular calvarial cortical thickening , patchy osteolysis , and islands of sclerotic bone representing “cotton wool” lesions (Left) Axial bone CT demonstrates diffuse skull base sclerosis with mild bony expansion, irregular cortical thickening 1211 Diagnostic Imaging Head and Neck , and poor corticomedullary differentiation There is demineralization of the otic capsules bilaterally Temporal bone involvement in such a case may cause the patient to suffer hearing loss (Right) Axial T1WI C+ MR in the same patient demonstrates avid enhancement of the petrous apex , which is mildly expanded and results in stenosis of the internal auditory canal P.V(1):65 TERMINOLOGY Abbreviations Paget disease (PD) Synonyms Osteitis deformans Definitions Primary metabolic bony disease of unknown etiology caused by waves of osteoclastic and osteoblastic activity IMAGING General Features Best diagnostic clue Mixed expansile, lytic & sclerotic bony disease of axial skeleton and skull in elderly male patient Imaging Recommendations Best imaging tool Bone CT is most demonstrative of mixed sclerosis & lysis CT Findings Bone CT Characteristic stages of bone remodeling with progression from bony lysis to sclerosis Well-defined lytic regions with expansion of bone in early phase of disease “Cotton wool” appearance in later lytic-sclerotic phase MR Findings T1WI Hypointense signal due to fibrovascular replacement of fat in marrow space Patchy ↑ signal possible with hemorrhage, slow flow in vascular channels T2WI Heterogeneous, occasional hyperintense signal T1WI C+ Heterogeneous enhancement due to hypervascular nature of new bone DIFFERENTIAL DIAGNOSIS Fibrous Dysplasia Classic “ground-glass” appearance and expansion in segments of diseased bone Can have more focal areas of soft tissue & sclerosis and mimic Paget disease Skull Base Metastasis Investigate for history of known malignancy Typically less diffuse & lesions more well defined Osteopetrosis Uniform bony sclerosis, diffuse involvement Spiculated periosteal reaction Osteogenesis Imperfecta Age of onset usually much younger PATHOLOGY General Features Etiology Cause is unknown, but strong genetic influence Genetics 15-20% of patients have 1st-degree relative with disease Mutations in sequestosome 1/p62 gene has been identified in familial Paget cases and in some sporadic cases Staging, Grading, & Classification 1st stage of disease is lysis Progresses to mixed lytic & sclerotic disease Final stage of disease is dense sclerosis Microscopic Features 1212 Diagnostic Imaging Head and Neck Histologic “mosaic” bone pattern in final stage of disease CLINICAL ISSUES Presentation Most common signs/symptoms May be incidental finding “Pagetic bone pain” is uncommon (constant, boring character) May present with hearing loss if temporal bone involvement Conductive hearing loss may result from involvement of ossicles Sensorineural hearing loss may result from bony compression of CN VIII or cochlear involvement Other signs/symptoms Wide range of other presentations, including Skull deformity & fractures Cranial neuropathies Demographics Age Typically disease of elderly Uncommon under age of 55 Gender More common in males → 1.8:1 Natural History & Prognosis Generally benign course Malignant transformation to osteosarcoma in < 1% of cases Treatment Multiple bisphosphonate agents have been proven effective SELECTED REFERENCES Merchant A et al: Somatic mutations in SQSTM1 detected in affected tissues from patients with sporadic Paget's disease of bone J Bone Miner Res 24(3):484-94, 2009 Hullar TE et al: Paget's disease and fibrous dysplasia Otolaryngol Clin North Am 36(4):707-32, 2003 Smith SE et al: From the archives of the AFIP Radiologic spectrum of Paget disease of bone and its complications with pathologic correlation Radiographics 22(5):1191-216, 2002 Skull Base Langerhans Cell Histiocytosis > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Langerhans Cell Histiocytosis Skull Base Langerhans Cell Histiocytosis C Douglas Phillips, MD, FACR Key Facts Terminology Proliferation of Langerhans type histiocytes forming granulomas with bone ± soft tissue involvement Imaging CT findings Geographic, lytic lesion of skull base/temporal bone Associated with enhancing soft tissue mass MR findings Heterogeneous, strongly enhancing soft tissue mass ± intracranial/dural extension Top Differential Diagnoses Acute coalescent otomastoiditis Acquired cholesteatoma Rhabdomyosarcoma Pathology Poorly understood disease of histiocytic proliferation and infiltration 70% have involvement of head and neck Clinical Issues Typical presentation: Young male with otalgia, otorrhea, & postauricular mass Usually presents in 1st decade M:F = 2:1 Otologic symptoms may be only initial sign of disease More common among Caucasians 90% cure rate for unifocal disease of temporal bone 1213 Diagnostic Imaging Head and Neck Usually responds well to medical management ± RT Surgical curettage or mastoidectomy for localized mastoid-middle ear disease (Left) Coronal bone CT demonstrates a destructive Langerhans cell histiocytosis (LCH) lesion centered in the basisphenoid and extending into the left orbital apex through the medial orbital wall A large area of bone dehiscence involves the planum sphenoidale (Right) Coronal T1WI C+ MR in the same patient shows involvement of the left orbit near apex , right orbital apex , and anterior cranial fossa Dural involvement is also noted with abnormal dural enhancement at the tumor margins (Left) Sagittal T1WI C+ MR shows a large, heterogeneously enhancing, central skull base LCH lesion extending into the sella Note intracranial extension into anterior fossa through planum sphenoidale and involvement of the infundibulum (Right) Axial T1WI C+ FS MR in the same patient depicts extensive involvement of basisphenoid and ethmoid sinuses, as well as the superior nasal cavity The mass invades the left and right orbital apices P.V(1):67 TERMINOLOGY Abbreviations Langerhans cell histiocytosis (LCH) Synonyms Eosinophilic granuloma, histiocytosis X, Hand-Schüller-Christian syndrome, Letterer-Siwe disease Definitions Proliferation of Langerhans type histiocytes forming granulomas with bone ± soft tissue involvement IMAGING General Features 1214 Diagnostic Imaging Head and Neck Best diagnostic clue Well-marginated, geographic, lytic lesion of skull base/temporal bone associated with enhancing soft tissue mass Location Mastoid portion of temporal bone common Petrous apex less common Skull lesions (frontal & parietal bones) more common than skull base Mandible, maxilla, & vertebral body lesions also may occur May be multiple lesions in severe cases Size Varies from small “punched out” lesion to total diffuse bony involvement May involve entire skull base Morphology Destructive, marginated lesion most often Radiographic Findings Radiography Lytic bone lesion with “punched-out” borders “Button sequestrum” occasionally noted in skull lesions CT Findings NECT Destructive soft tissue mass involving mastoid May be bilateral CECT Variably enhancing soft tissue mass in mastoid May involve contiguous dura Bone CT Bony lesions of variable appearance, typically lytic Most have sharply defined “punched out” appearance Geographic bone destruction in mastoid temporal bone Ossicular & otic capsule destruction Lytic lesions with beveled margins, with or without sclerosis (common appearance in skull) May have more diffuse bone destructive change MR Findings T1WI Iso- to hypointense mass of bone ± adjacent soft tissue mass ↑ signal in proliferative LCH lesions due to lipid-laden macrophages T2WI Hyper- to isointense mass T2 may rarely demonstrate blood products in soft tissue mass T1WI C+ Heterogeneous, strongly enhancing soft tissue mass May show defined or infiltrative borders Intracranial extension (dural involvement) best seen post contrast Imaging Recommendations Best imaging tool Bone CT delineates geographic pattern of temporal bone/skull base involvement Gadolinium-enhanced MR best for depicting soft tissue extent & intracranial involvement CECT or MR help differentiate inflammatory mastoid lesions from LCH Protocol advice Post-gadolinium MR with fat suppression DIFFERENTIAL DIAGNOSIS Acute Coalescent Otomastoiditis Acutely ill patient; responsive to antibiotics Trabecular loss, cortical dehiscence usually less extensive than in LCH No soft tissue component unless abscess present Congenital Cholesteatoma White retrotympanic mass on otoscopy Does not enhance Acquired Cholesteatoma 1215 Diagnostic Imaging Head and Neck Tympanic membrane perforation with white mass on otoscopy Bone destruction involves scutum & ossicles; usually less extensive than LCH Does not enhance Rhabdomyosarcoma Aggressive unilateral soft tissue mass with bone destruction May have ipsilateral cervical nodal disease Biopsy may be required to differentiate from LCH Fibrous Dysplasia Lytic phase lesions may mimic LCH Typically causes bone expansion & areas of “ground-glass” attenuation PATHOLOGY General Features Etiology Poorly understood disease of histiocytic proliferation and infiltration Cause uncertain (inflammatory vs neoplastic) Best hypothesis is reactive immunostimulation Stimulus source is unknown Causes osteoclastic activating factor release & eosinophilic infiltration in monoclonal Langerhans cells P.V(1):68 ↑ risk of LCH: Family history of thyroid disease, underimmunization, penicillin use, solvent exposure Genetics Monoclonality of pathologic Langerhans cell Familial cases documented t(7;12) translocation, involvement in TEL gene on chromosome 12 Associated abnormalities Hypothalamic-pituitary disease most common with classic finding of diabetes insipidus Infratentorial abnormalities common, involving dentate nuclei, cerebellar white matter, and pons Staging, Grading, & Classification Formerly classified into of overlapping forms Unifocal LCH (eosinophilic granuloma) Mildest form of LCH Age of onset: Children, 5-20 years old Unifocal osseous lesions of long bones, skull, skull base, & temporal bone Prognosis: Excellent Hand-Schüller-Christian disease Age of onset: Children, 1-4 years old Multifocal bone, skin, viscera, and brain involvement Good prognosis Letterer-Siwe disease Most severe form of LCH Age of onset: 0-2 years old Acute, fulminant, disseminated multiorgan disease including liver, spleen, lymphatic, lung, & bone Prognosis poor with high mortality rate Now classified according to risk factors Young age, multifocal involvement, multiorgan dysfunction, relapse Gross Pathologic & Surgical Features Bone biopsy may be required to confirm diagnosis Yellow, gray, or brown tumor mass Microscopic Features Langerhans cell is histiocyte-like cell with folded nucleus EM shows Birbeck granules, an elongated tennis racket-shaped cytoplasmic inclusion Langerhans cell is diffusely immunoreactive with S100 protein & CD1a CLINICAL ISSUES Presentation Most common signs/symptoms 1216 Diagnostic Imaging Head and Neck Otologic symptoms may be only initial sign of disease Initial presentation with otologic symptoms in 25% Conductive hearing loss & otorrhea Other signs/symptoms Otalgia, vertigo Otitis externa/media Postauricular swelling Clinical profile Male child or adolescent with otalgia, otorrhea, & postauricular mass Demographics Age Usually presents in 1st decade Inverse relationship between age of presentation & severity of disease Age range varies with LCH subtype Unifocal LCH (eosinophilic granuloma): 5-20 years Hand-Schüller-Christian disease: 1-4 years Letterer-Siwe disease: < years Gender M:F = 2:1 Ethnicity More common among Caucasians Epidemiology Rare (0.2-2 cases per 100,00 children) 70% have involvement of head & neck Bilateral disease in 30% of cases Bone lesions most common manifestation of disease (80-95% of children with LCH) Natural History & Prognosis 90% cure rate for unifocal disease of temporal bone Soft tissue component resolves initially, then reossification of lytic bone lesion Local recurrence may occur Treatment Usually responds well to medical management ± RT Low-dose radiotherapy for larger, destructive lesions Surgical curettage or mastoidectomy for localized mastoid-middle ear disease Systemic disease treated with chemotherapy in combination with radiation therapy DIAGNOSTIC CHECKLIST Consider Consider LCH when destructive temporal bone lesion does not respond to antibiotics and tympanostomy tubes Reporting Tips Differentiation of LCH lesion from rhabdomyosarcoma essential SELECTED REFERENCES Chung EM et al: From the archives of the AFIP Pediatric orbit tumors and tumorlike lesions: osseous lesions of the orbit Radiographics 28(4):1193-214, 2008 Prosch H et al: Long-term MR imaging course of neurodegenerative Langerhans cell histiocytosis AJNR Am J Neuroradiol 28(6):1022-8, 2007 Krishna H et al: Solitary Langerhans-cell histiocytosis of the clivus and sphenoid sinus with parasellar and petrous extensions: case report and a review of literature Surg Neurol 62(5):447-54, 2004 Prayer D et al: MR imaging presentation of intracranial disease associated with Langerhans cell histiocytosis AJNR Am J Neuroradiol 25(5):880-91, 2004 Cochrane LA et al: Langerhans' cell histiocytosis in the paediatric population: presentation and treatment of head and neck manifestations J Otolaryngol 32(1):33-7, 2003 P.V(1):69 Image Gallery 1217 Diagnostic Imaging Head and Neck (Left) Axial CECT shows a destructive LCH lesion centered in the basisphenoid that invades posterior left and right orbital apices with extensive bone erosion of medial orbital walls This lesion enhances relatively homogeneously (Right) Axial CECT demonstrates a very large LCH mass of the central and lateral skull base with relatively homogeneous enhancement This mass causes extensive destruction of the right temporal bone, sphenoid wings, orbits, and base of skull (Left) Axial bone CT shows a destructive LCH mass of the left middle ear and mastoid with scalloping of the bone in the mastoid cavity and areas of dehiscence of the lateral mastoid cortex (Right) Axial T1WI C+ MR of bilateral temporal bone skull base LCH reveals relatively homogeneous enhancement of soft tissue within the temporal bones of this young child The large mass on the left extends into the soft tissues The right LCH lesion is confined to the temporal bone 1218 Diagnostic Imaging Head and Neck (Left) Coronal T1WI C+ MR demonstrates bilateral temporal bone LCH On the left, irregular LCH lesion involves dura , while on the right, it extends to dural surface In the right neck, there is an associated cervical adenopathy (Right) Axial bone CT demonstrates a case of LCH involving the petrous apex The mass is characterized by welldefined margins on CT and extends anteriorly to involve the posterior wall of the horizontal petrous carotid canal Skull Base Osteopetrosis > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Osteopetrosis Skull Base Osteopetrosis H Ric Harnsberger, MD Key Facts Terminology Rare heritable metabolic bone disease with defective bone remodeling resulting in overproduction of immature bone Autosomal recessive osteopetrosis (AROP): Childhood (malignant) form; severe osteopetrosis Autosomal dominant osteopetrosis (ADOP): Adult (benign) form; less severe osteopetrosis Imaging AROP: CT findings seen in infancy Diffuse increase in overall bone density T-bone: IAC & ICA canal stenoses, middle ear encroachment Skull base: Foraminal & dural sinus stenoses ADOP, type 2: Adult CT findings Dense sclerosis of skull base & spine; spares calvarium Generalized ↑ density of entire skull base “Endobones” (unresorbed primary ossification centers) Sclerotic otic capsule beyond normal bony labyrinth margins IAC short & trumpet-shaped Enlarged subarcuate fossa possible Top Differential Diagnoses Skull base Paget disease Skull base fibrous dysplasia Pathology Hereditary disorder: CLCN7 gene mutation Clinical Issues AROP is apparent in infancy ADOP manifests later in life 1219 Diagnostic Imaging Head and Neck (Left) Lateral radiograph shows diffuse thickening of calvarium , cranial base , and the temporal bone , characteristic of the more severe form of osteopetrosis (autosomal recessive) (Right) Axial skull base bone CT shows diffuse sclerosis of entire cranial base There is narrowing of both middle ears Note also compromise of each internal auditory canal This child has autosomal recessive osteopetrosis (Left) Axial bone CT through the skull base in a young adult with type autosomal dominant osteopetrosis shows bilateral dense sclerosis of temporal bone with thickening of the calvarium without increased density Notice the “endobone” appearance of both malar eminences from unresorbed primary ossification centers (Right) Axial bone CT of the left temporal bone in the same patient reveals encroachment upon the internal auditory canal by osteopetrosis of inner ear bone P.V(1):71 TERMINOLOGY Synonyms Marble bone disease, Albers-Schönberg disease Definitions Rare heritable metabolic bone disease with defective bone remodeling resulting in overproduction of immature bone Autosomal recessive osteopetrosis (AROP): Childhood (malignant) form; severe osteopetrosis Autosomal dominant osteopetrosis (ADOP): Adult (benign) form; less severe osteopetrosis IMAGING General Features 1220 Diagnostic Imaging Head and Neck Best diagnostic clue Dense, sclerotic bones (“chalk bones”) Location T-bone, calvarium, & skull base Radiographic Findings Radiography Dense bone is easily appreciated in AROP CT Findings NECT AROP: Calcifications within basal ganglia, thalami, dentate nuclei, & white matter From renal tubular acidosis secondary to associated carbonic anhydrase II deficiency Bone CT AROP: CT findings seen in infancy Diffuse increase in overall bone density T-bone: IAC & ICA canal stenoses, middle ear encroachment Skull base: Foraminal & dural sinus stenoses ADOP: Adult CT findings Type 1: Dense sclerosis of calvarium & spine T-bone & skull base spared Type 2: Dense sclerosis of skull base & spine; spares calvarium Generalized ↑ density of entire skull base “Endobones” (unresorbed primary ossification centers) Sclerotic otic capsule beyond normal bony labyrinth margins IAC short & trumpet-shaped Enlarged subarcuate fossa possible MR Findings T1WI AROP: Thickening of calvarium, skull base, & T-bone T2* GRE ADOP type 2: Blooming of Ca++ Basal ganglia, thalami, dentate nuclei, & white matter T1WI C+ AROP: C+ in suprahyoid neck = extramedullary hematopoiesis MRA: Petrous ICA stenosis (AROP) MRV: Dural venous sinus stenosis (AROP) DIFFERENTIAL DIAGNOSIS Skull Base Paget Disease Clinical: Elderly patients Usually seen as diffuse, “cotton-wool” appearance Demineralized otic capsule correlates with SNHL Skull Base Fibrous Dysplasia Clinical: < 30 years old Relative sparing of otic capsule Lytic, sclerotic, or mixed Increased bone volume is characteristic PATHOLOGY General Features Etiology Hereditary disorder: CLCN7 gene mutation Genetics Autosomal recessive or dominant Overproduction of immature bone Osteoclast function is defective Microscopic Features Persistent primary bony spongiosa CLINICAL ISSUES Presentation Most common signs/symptoms AROP 1221 Diagnostic Imaging Head and Neck Cranial neuropathies, poor bone growth, petrous ICA & dural venous sinus stenoses Marrow replaced: Anemia & neutropenia Extramedullary hematopoiesis possible Fragile bones: Fractures with minor trauma ADOP May be asymptomatic Conductive hearing loss more common than SNHL Demographics Age AROP is apparent in infancy ADOP manifests later in life Epidemiology Rare otodystrophy Natural History & Prognosis Children with AROP rarely survive childhood Progressive bilateral hearing loss in ADOP type SELECTED REFERENCES Turgut M et al: Autosomal recessive osteopetrosis as an unusual cause of hydrocephalus, extensive calcification of tentorium cerebelli, and calvarial hyperostosis J Neurosurg Pediatr 5(4):419-21, 2010 Fotiadou A et al: Type II autosomal dominant osteopetrosis: radiological features in two families containing five members with asymptomatic and uncomplicated disease Skeletal Radiol 38(10):1015-21, 2009 Curé JK et al: Cranial MR imaging of osteopetrosis AJNR Am J Neuroradiol 21(6):1110-5, 2000 Skull Base Idiopathic Inflammatory Pseudotumor > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Idiopathic Inflammatory Pseudotumor Skull Base Idiopathic Inflammatory Pseudotumor H Ric Harnsberger, MD Key Facts Terminology Nonspecific, nonneoplastic benign inflammatory process without identifiable local or systemic causes characterized by polymorphous lymphoid infiltrate with varying degrees of fibrosis Imaging Intraorbital, cavernous sinus, meningeal, skull base, or nasopharyngeal enhancing infiltrating lesion T2: Iso- to hypointense infiltrating mass ↑ ↑ fibrosis, ↑ ↑ hypointensity T1WI C+ MR: Diffusely C+ infiltrating mass with multiple appearances Extends from orbit through superior orbital fissure to cavernous sinus, local meninges, Meckel cave Extends through inferior orbital fissure to pterygopalatine fossa and nose Involves deep spaces of nasopharynx MRA: When involves cavernous sinus, internal carotid artery narrowing often present Top Differential Diagnoses Meningitis Neurosarcoid En plaque meningioma Metastases, skull and meningeal Meningeal non-Hodgkin lymphoma (NHL) Nasopharyngeal carcinoma Clinical Issues Painful proptosis ± headaches ± cranial neuropathies Extracranial soft tissues: Focal or diffuse mass Diagnosis of exclusion; must be biopsied Treatment: High-dose systemic steroids 1222 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR through the orbits shows enhancing, infiltrating lesion in orbital apex and lateral rectus, cavernous sinus and Meckel cave The initial impression of adenoid cystic carcinoma gave way to biopsyproven idiopathic inflammatory disease with both intraorbital and intracranial components (Right) Axial T1WI C+ FS MR in the same patient shows the lesion invading inferiorly through the inferior orbital fissure into the pterygopalatine fossa and nose (Left) Axial T1WI C+ FS MR demonstrates an enlarged, enhancing left cavernous sinus with subtle narrowing of the intracavernous internal carotid artery (Right) Axial T2WI MR in the same patient reveals that the cavernous sinus lesion is strikingly low signal Biopsy revealed an idiopathic inflammatory pseudotumor No significant intraorbital disease was present Imaging mimics a meningioma in this patient with cranial neuropathy P.V(1):73 TERMINOLOGY Abbreviations Idiopathic inflammatory pseudotumor (IIP) Synonyms Idiopathic inflammatory disease, Tolosa-Hunt syndrome, hypertrophic cranial pachymeningitis, plasma cell granuloma Definitions Nonspecific, nonneoplastic benign inflammatory process without identifiable local or systemic causes characterized by polymorphous lymphoid infiltrate with varying degrees of fibrosis IMAGING General Features 1223 Diagnostic Imaging Head and Neck Best diagnostic clue Intraorbital, cavernous sinus, meningeal, skull base, or nasopharyngeal enhancing infiltrating lesion Location Intracranial involvement Meningeal surfaces Cavernous sinus, Meckel cave area Falx and tentorium are less often involved Skull base and extracranial involvement Central and anterior skull base Pterygopalatine fossa and nose Deep spaces of nasopharynx Size May extensively involve meningeal surfaces and adjacent skull base Focal meningeal thickening may range in thickness from few millimeters to > cm Skull base and extracranial soft tissue masses may be large (many centimeters) Morphology Skull base and nasopharyngeal soft tissue infiltrating lesions mimic malignancy Infiltrating mass along meningeal surfaces CT Findings CECT Enhancing, soft tissue mass Bone CT Associated bone erosion unusual CTA If cavernous ICA involved, often narrowed MR Findings T1WI Lesion isointense to gray matter T2WI Iso- to hypointense infiltrating mass ↑ ↑ fibrosis, ↑ ↑ hypointensity FLAIR No adjacent brain edema T1WI C+ Diffusely enhancing infiltrating mass with multiple appearances Extends from orbit through superior orbital fissure to cavernous sinus, local meninges, Meckel cave Extends through inferior orbital fissure to pterygopalatine fossa May affect posterior nose Involves deep spaces of nasopharynx Underlying bone is rarely invaded Fat-saturated T1 C+ best sequence MRA When involving cavernous sinus, internal carotid artery narrowing often present Imaging Recommendations Best imaging tool MR imaging intracranial & extracranial extensions Protocol advice Begin with MR, including full brain FLAIR and enhanced T1WI C+ with fat saturation Bone CT may help differentiate this lesion from en plaque meningioma DIFFERENTIAL DIAGNOSIS Neurosarcoid Systemic manifestations abound Increased erythrocyte sedimentation rate (ESR) and serum angiotensin converting enzyme (ACE) Skull and Meningeal Metastases Nodular meningeal carcinomatosis less common than diffuse Cranial neuropathy occurs early CSF cellular analysis usually provides diagnosis, but meningeal biopsy may be necessary En Plaque Meningioma 1224 Diagnostic Imaging Head and Neck Enhancing meningeal mass + dural “tails” Permeative-sclerotic invasive bone changes typical May exactly mimic intracranial IIP Meningeal Non-Hodgkin Lymphoma (NHL) Usually more diffuse, multifocal with underlying bone involvement “Great pretender” (can mimic many intracranial diseases) Nasopharyngeal Carcinoma Arises in nasopharyngeal mucosal space Invades cephalad into skull base, sinuses Meningitis TB, fungal, or other infectious agent causes focal meningeal thickening CSF analysis may not make diagnosis Meningeal biopsy may be necessary PATHOLOGY General Features Etiology Benign inflammatory process of unknown origin Hypothesis 1: Immune-autoimmune pathophysiology Hypothesis 2: Low-grade fibrosarcoma with inflammatory (lymphomatous) cells Other pathologic features P.V(1):74 IIP is “quasi-neoplastic” lesion; most commonly affects lung and orbit Has been reported to occur in nearly every site in human body Can involve meninges, cavernous sinus, skull base, extracranial soft tissues Spectrum of idiopathic inflammatory lesions Gross Pathologic & Surgical Features Surgical impression depends on histopathologic composition Soft, compressible mass: Intracranial pseudotumor Hard, fibrotic mass: Hypertrophic cranial pachymeningitis Microscopic Features Histologic hallmarks Mixed inflammatory infiltrate of lymphocytes (T and B cells) and plasma cells Varying degrees of fibrosis present Terminology depends on mix during histopathologic evaluation IIP-pseudotumor Inflammatory meningeal mass with balanced mixture of lymphocytes, plasma cells, and fibrous tissue Plasma cell granuloma Inflammatory meningeal mass with predominance of plasma cells Hypertrophic cranial pachymeningitis Inflammatory meningeal mass with predominance of dense fibrous tissue CLINICAL ISSUES Presentation Most common signs/symptoms Orbital lesion: Painful proptosis Intracranial lesion only: Chronic headaches Cavernous sinus: Cranial neuropathy (CN3, 4, 5, 6) Extracranial soft tissues: Focal or diffuse mass Clinical profile Adult presenting with painful proptosis, headaches, and cranial nerve palsies Demographics Age Intracranial IIP: Adults (40-65 years of age) Epidemiology Extraorbital IIP: Intracranial or extracranial Most commonly associated with orbital IIP Can be seen without orbital IIP 1225 Diagnostic Imaging Head and Neck Natural History & Prognosis Intracranial and extracranial IIP May respond to steroid therapy When extensive intra- & extracranial involvement present, may be resistant to all therapies Such intractable disease may cause severe disability or death Orbital lesions Treatment successes (65%) Treatment failures (35%) Treatment Options, risks, complications Diagnosis of exclusion Intra- or extracranial disease must be biopsied Biopsy excludes infectious and neoplastic (NHL) causes of focal meningeal thickening High-dose systemic steroids with slow taper is principal treatment option Steroid-resistant cases ± cases with extensive skull base involvement Radiotherapy ± chemotherapy Surgical resection as possible DIAGNOSTIC CHECKLIST Consider IIP is diagnosis of exclusion! 1st exclude infection and malignancy with biopsy Realize that intracranial IIP, plasma cell granuloma, and hypertrophic cranial pachymeningitis are all part of same disease spectrum Image Interpretation Pearls If mass in orbit with proximal meningeal, cavernous sinus lesion, consider IIP IIP orbit alone > > orbit and intracranial > > orbit intracranial and extracranial Reporting Tips If orbital lesion suggests IIP, report any associated intracranial or extracranial soft tissue lesions SELECTED REFERENCES Strasnick B et al: Inflammatory pseudotumor of the temporal bone: a case series Skull Base 18(1):49-52, 2008 Agir H et al: W(h)ither orbital pseudotumor? J Craniofac Surg 18(5):1148-53, 2007 Mangiardi JR et al: Extraorbital skull base idiopathic pseudotumor Laryngoscope 117(4):589-94, 2007 Lee DK et al: Inflammatory pseudotumor involving the skull base: response to steroid and radiation therapy Otolaryngol Head Neck Surg 135(1):144-8, 2006 Lee EJ et al: MR imaging of orbital inflammatory pseudotumors with extraorbital extension Korean J Radiol 6(2):82-8, 2005 Narla LD et al: Inflammatory pseudotumor Radiographics 23(3):719-29, 2003 Yuen SJ et al: Idiopathic orbital inflammation: distribution, clinical features, and treatment outcome Arch Ophthalmol 121(4):491-9, 2003 Dehner LP: The enigmatic inflammatory pseudotumours: the current state of our understanding, or misunderstanding J Pathol 192(3):277-9, 2000 Tekkök IH et al: Intracranial plasma cell granuloma Brain Tumor Pathol 17(3):97-103, 2000 10 Bencherif B et al: Intracranial extension of an idiopathic orbital inflammatory pseudotumor AJNR Am J Neuroradiol 14(1):181-4, 1993 11 Clifton AG et al: Intracranial extension of orbital pseudotumour Clin Radiol 45(1):23-6, 1992 P.V(1):75 Image Gallery 1226 Diagnostic Imaging Head and Neck (Left) In this patient with painful proptosis, an axial T1WI C+ FS MR shows an intraorbital lateral rectus & intraconal lesion Note the pseudotumor progresses through the superior orbital fissure to the anterior cavernous sinus (Right) Coronal T1WI C+ FS MR in the same patient shows the intracranial extension of the lesion into the left cavernous sinus Orbital pseudotumor extending into the cavernous sinus is the most common form of intracranial extension (Left) Axial T1WI C+ FS MR shows extensive orbital apex , ethmoid sinus , and foramen rotundum infiltrating enhancing idiopathic inflammatory pseudotumor (Right) On a more inferior slice in the same patient, the axial T1WI C+ FS MR reveals bilateral pterygopalatine fossa involvement with continuous transnasal pseudotumor Both inferior orbital fissures are also affected Imaging often mimics a neoplasm A biopsy is necessary for diagnosis 1227 Diagnostic Imaging Head and Neck (Left) Axial T2WI FS MR in the same patient shows an infiltrating pseudotumor in the orbital apex and ethmoid sinus Obstructed sinuses are easily differentiated from the pseudotumor Isointensity of the pseudotumor results from greater cellular content in this lesion compared to fibrosis content (Right) Axial T2WI FS MR in the same patient shows extensive pseudotumorous involvement of the pterygopalatine fossae and posterior nose Skull Base Giant Cell Tumor > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Giant Cell Tumor Skull Base Giant Cell Tumor Deborah R Shatzkes, MD Key Facts Terminology Giant cell tumor (GCT) Benign intraosseous neoplasm arising from multinucleated giant cells Imaging CT: Expansile intraosseous soft tissue mass with thinned surrounding cortical shell MR: Hypointense rim & prominent internal enhancement Sphenoid bone > temporal bone > > frontal bone Top Differential Diagnoses Aneurysmal bone cyst (ABC) Chordoma Chondrosarcoma Fibrous dysplasia Plasmacytoma Pathology Hemorrhage/hemosiderin deposition common Overlap with other giant cell containing tumors, such as giant cell lesion, ABC, brown tumor, PVNS Clinical Issues Rare lesion: 2% of all GCT arise in skull base Peak incidence: 3rd-4th decade Metastases in 2% of cases Recurrence rate 40-60% after resection Diagnostic Checklist If in patient < 30 years of age, consider fibrous dysplasia If lesion centered in sella & normal pituitary not seen, consider invasive adenoma If patient has known malignancy, consider metastasis 1228 Diagnostic Imaging Head and Neck (Left) Coronal bone CT reveals a lytic, expansile lesion of the left greater sphenoid wing with eggshell calcification along its superior margin This giant cell tumor secondarily involved the left sphenoid sinus and the region of the left temporomandibular joint (Right) Coronal T2WI FS MR in the same patient reveals central hyperintensity with a rim of prominent hypointensity Inferior extension of the mass into the left masticator space is evident (Left) Axial NECT shows an expansile GCT of the central skull base extending anteriorly into the posterior nasoethmoidal region The contents of the lesion are heterogeneous with a small internal calcification MR confirmed that the lesion was centered in the sphenoid bone (Right) Coronal T1 C+ FS MR demonstrates a GCT in its least common skull base location, the frontal bone There is intracranial and extracranial extension, including involvement of the superior orbit P.V(1):77 TERMINOLOGY Abbreviations Giant cell tumor (GCT) Synonyms Osteoclastoma Definitions Benign intraosseous neoplasm arising from multinucleated giant cells IMAGING General Features Best diagnostic clue 1229 Diagnostic Imaging Head and Neck CT: Expansile intraosseous soft tissue mass with thin surrounding cortical shell MR: Hypointense rim with prominent internal enhancement Location Sphenoid bone > temporal bone > > frontal bone Size Variable, usually > centimeters CT Findings NECT Mildly hyperdense soft tissue mass CECT Marked enhancement Bone CT Overlying cortical shell may be focally dehiscent Occasional scant matrix calcification MR Findings T1WI Mixed iso- to hyperintense to gray matter Hypointense rim common T2WI Mixed iso- to hyperintense to gray matter Occasionally diffusely hypointense (due to hemosiderin, calcification) Markedly hypointense rim T1WI C+ Marked enhancement DIFFERENTIAL DIAGNOSIS Aneurysmal Bone Cyst “Soap bubble” appearance with blood-fluid levels May arise secondarily from GCT Chordoma Destructive midline clival mass with bone fragments Chondrosarcoma Eccentric erosive mass, chondroid calcifications Fibrous Dysplasia Diffuse ground-glass density, hypointense on T2WI < 30 years old, rarely progressive Plasmacytoma Homogeneous soft tissue mass Solitary or seen in association with multiple myeloma PATHOLOGY General Features Etiology Unknown Can arise secondarily in pagetoid bone Microscopic Features Multinucleated osteoclastic giant cells, often with hemorrhage/hemosiderin Light microscopic findings very similar to other lesions with giant cells Patient demographics, lesion location, and radiographic features often necessary to arrive at specific diagnosis Giant cell lesion (formerly known as giant cell reparative granuloma) Brown tumor Aneurysmal bone cyst and PVNS CLINICAL ISSUES Presentation Most common signs/symptoms Headache & local pain Cranial nerve palsies Other signs/symptoms Sphenoid GCT: Diplopia, ophthalmoplegia Temporal bone (TB) GCT: Otalgia, hearing loss, facial palsy, TMJ dysfunction 1230 Diagnostic Imaging Head and Neck Demographics Age Peak incidence: 3rd-4th decade Gender Female predominance Epidemiology Only 2% of all GCT in skull base Natural History & Prognosis Rare sarcomatous transformation Usually seen only after radiation therapy Metastases in 2% of cases Treatment Preoperative embolization Surgical resection/curettage Reported recurrence rate after resection: 40-60% Radiation therapy for inoperable lesions SELECTED REFERENCES Pelaz AC et al: Giant cell tumor of the greater wing of the sphenoid: an unusual presentation J Craniofac Surg 19(3):822-6, 2008 Kashiwagi N et al: MRI and CT findings of the giant cell tumors of the skull; five cases and a review of the literature Eur J Radiol 58(3):435-43, 2006 Wang Y et al: Giant cell tumor at the lateral skull base Am J Otolaryngol 27(1):64-7, 2006 Ito H et al: Secondary aneurysmal bone cyst derived from a giant-cell tumour of the skull base Neuroradiology 45(9):616-7, 2003 Lee JA et al: Giant cell tumor of the skull Radiographics 18(5):1295-302, 1998 Skull Base Meningioma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Meningioma Skull Base Meningioma Deborah R Shatzkes, MD Key Facts Terminology Benign extraaxial neoplasm arising from arachnoid cap cells Imaging Anterior skull base: Olfactory groove, tuberculum sella, & sphenoid wing Central skull base: Petroclival & pericavernous Posterior skull base: Lower clival & foramen magnum Morphology: Sessile (en plaque)/lentiform > globose/spherical CT findings Hyperdense, homogeneously enhancing mass 25% intramural calcification Hyperostosis > permeative sclerotic MR findings Isointense to gray matter with prominent enhancement Enhancing reactive dural “tail” in 60% CSF-vascular cleft between tumor & parenchyma Top Differential Diagnoses Skull base schwannoma Giant pituitary macroadenoma Chordoma Skull base/dural metastasis Sarcoidosis Clinical Issues 2nd most common primary intracranial tumor Middle-aged to elderly patients M:F = 1:3 Diagnostic Checklist Assess involvement of critical skull base structures: Optic canal, vessels, cavernous sinus, Meckel cave 1231 Diagnostic Imaging Head and Neck (Left) Coronal T1WI C+ MR demonstrates a peripherally enhancing mass based along the floor of the anterior fossa While the central low signal is atypical (reflecting heavy calcification), the presence of hyperostosis and upward “blistering” of the planum sphenoidale is highly characteristic of meningioma (Right) Axial bone CT in the same patient shows the calcified meningioma along the planum sphenoidale, with accompanying pneumatosis dilatans of the adjacent sphenoid sinus (Left) Sagittal T1WI C+ FS MR shows a large, avidly enhancing anterior cranial fossa meningioma buckling the medial frontal lobe There is inferior extension through the cribriform plate into the olfactory recess of the nasal cavity (Right) Axial FLAIR MR in the same patient demonstrates signal intensity similar to gray matter, with only mild heterogeneity There is extensive peritumoral edema , a finding that increases surgical morbidity and likelihood of recurrence P.V(1):79 TERMINOLOGY Definitions Benign extraaxial neoplasm arising from arachnoid cap cells IMAGING General Features Best diagnostic clue Avidly enhancing, extraaxial dural-based mass with enhancing “tails” Location Anterior skull base (40% of intracranial meningiomas) 50% in olfactory groove and tuberculum sella 1232 Diagnostic Imaging Head and Neck 15% of olfactory groove meningiomas grow into sinonasal cavity Tuberculum sella meningiomas may grow into or both optic canals 50% in sphenoid wing Clinoidal (medial sphenoid wing) Spheno-orbital (lateral sphenoid wing); most frequently symptomatic Central skull base Petroclival (upper clivus, cavernous sinus, tentorium, and petrous apex) Posterior skull base Lower clival, foramen magnum Foramen magnum lesions may be posterior, anterior, or lateral Additional skull base locations: CPA/IAC, temporal bone, jugular foramen Morphology Sessile/lentiform > globose/spherical Occasional en plaque configuration Carpet-like tumor overlying hyperostotic bone Common in spheno-orbital lesions (lateral sphenoid wing) CT Findings NECT 75% hyperdense compared to brain parenchyma 25% intramural calcification May occasionally be entirely calcified CECT 90% show strong, uniform enhancement Bone CT Hyperostotic > permeative sclerotic adjacent bone changes Hyperostotic bone may or may not be invaded Upward “blistering” may be seen along planum sphenoidale Pneumosinus dilatans of adjacent sphenoid sinus may occur MR Findings T1WI Hypo- to isointense to gray matter May be low or absent signal in heavily calcified areas Rare ↑ signal in foci of hemorrhage T2WI Hypo- to isointense to gray matter 25% atypical appearance with ↑ signal in necrosis, cysts CSF-vascular cleft at periphery of large lesions Thin space between tumor and brain containing fluid and vessels Peritumoral brain edema correlates with pial blood supply Increased incidence surgical morbidity and early recurrence T2* GRE If significantly calcified, may “bloom” T1WI C+ Prominent enhancement in 95% Enhancing dural “tail” in 60% Meningioma within cavernous sinus typically enhances to lesser degree than uninvolved sinus Angiographic Findings Dural vessels supply center, pial vessels supply periphery “Sunburst” or “spoke-wheel” pattern of enlarged dural feeders common Prolonged vascular “stain” into venous phase Imaging Recommendations Best imaging tool Enhanced, fat-suppressed MR generally best for precise tumor mapping DIFFERENTIAL DIAGNOSIS Trigeminal Schwannoma Parasellar mass, often with cystic components May extend through trigeminal exit foramina or prepontine cistern Giant Pituitary Macroadenoma Large, invasive mass with skull base invasion 1233 Diagnostic Imaging Head and Neck No identifiable normal pituitary tissue Clival Chordoma Midline destructive mass High T2 signal; heterogeneous enhancement Chondrosarcoma Eccentric mass with chondroid matrix ↑ T2 signal Skull Base Metastasis Variable appearance depending on histology of primary and whether mets are to skull base marrow or dura Multiple dural-based enhancing masses Plasmacytoma Lytic destructive mass of clivus May be solitary or multiple in setting of multiple myeloma Neurosarcoid Multifocal, dural-based enhancing foci Look for infundibular stalk enhancement & enlargement Rosai-Dorfman Disease Rare histiocytic disease P.V(1):80 May demonstrate multiple dural-based, T2 hypointense masses PATHOLOGY General Features Etiology Most are sporadic Multiple inherited schwannomas, meningiomas, & ependymomas (“MISME”) in NF2 Increased incidence following radiotherapy More commonly over convexities than skull base Develop 20-35 years following radiation Genetics Mutations in NF2 gene on chromosome 22 are detected in approximatively in 60% of sporadic meningiomas Staging, Grading, & Classification WHO classification (2000) Grade I: Benign (90%), e.g., meningothelial Grade II: Atypical (7%), e.g., clear cell Grade III: Anaplastic/malignant (2%), e.g., rhabdoid Grade II and III meningiomas are less common at skull base than along convexities Poor correlation between histologic grade and imaging features Gross Pathologic & Surgical Features “Semilunar” or “en plaque” > round or globose Sharply circumscribed Adjacent dural thickening (“tail”) Not specific for meningioma; may accompany any dural-based process Usually reactive, not neoplastic Microscopic Features Arise from meningothelial (arachnoid “cap”) cells Relatively uniform cells with tendency to encircle one another forming whorls Psammoma bodies (laminated calcific concretions) Highly vascularized CLINICAL ISSUES Presentation Most common signs/symptoms May be incidental finding 33% of incidental intracranial neoplasms Symptoms often nonspecific Headache Dizziness 1234 Diagnostic Imaging Head and Neck Syncope Other signs/symptoms Anterior skull base: Anosmia, visual loss, proptosis Central skull base: Ophthalmoplegia Posterior skull base: Myelopathy, lower cranial neuropathy Demographics Age Middle-aged to elderly patients Peak age = 60 years Gender M:F = 1:3 Epidemiology 2nd most common primary intracranial tumor Most common extraaxial tumor 15-25% of primary intracranial tumors 10% multiple (NF2; multiple meningiomatosis) Natural History & Prognosis Indolent course is typical More aggressive course in WHO grade II/III lesions Those with peritumoral brain edema have higher surgical complication & recurrence rates Treatment Surgery most likely to achieve cure, but often requires complex combined approach with significant morbidity risk Preoperative angiography/embolization may be employed to reduce intraoperative blood loss Simpson grading system used to estimate completeness of resection Grade I (complete removal including dura and underlying bone) → grade IV (subtotal resection) Prognosis for cure more dependent on tumor location than grade Radiotherapy/radiosurgery may be used primarily or adjunctive when resection is incomplete DIAGNOSTIC CHECKLIST Consider Solitary, enhancing, dural-based extraaxial mass = meningioma, particularly in adult patient without known malignancy Reporting Tips Assess caliber of internal carotid, basilar, or vertebral arteries if surrounded by tumor Meningioma often narrows ICA Other parasellar lesions, such as schwannoma, macroadenoma, and lymphoma, typically will not Assess for Meckel cave or optic canal involvement Always search for 2nd meningioma Multiple meningiomas in 10% of sporadic cases Report brain edema, as it increases rate of surgical morbidity and recurrence SELECTED REFERENCES Hsu CC et al: Do aggressive imaging features correlate with advanced histopathological grade in meningiomas? J Clin Neurosci 17(5):584-7, 2010 Mirone G et al: En plaque sphenoid wing meningiomas: recurrence factors and surgical strategy in a series of 71 patients Neurosurgery 65(6 Suppl):100-8; discussion 108-9, 2009 Razek AA et al: Imaging lesions of the cavernous sinus AJNR Am J Neuroradiol 2009 Mar;30(3):444-52 Epub 2008 Dec 18 Review Erratum in: AJNR Am J Neuroradiol 30(7):E115, 2009 Guermazi A et al: The dural tail sign—beyond meningioma Clin Radiol 60(2):171-88, 2005 Buetow MP et al: Typical, atypical, and misleading features in meningioma Radiographics 11(6):1087-106, 1991 P.V(1):81 Image Gallery 1235 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in a patient with left proptosis reveals an en plaque meningioma of the left sphenoid wing characterized by striking hyperostosis and only thin intraorbital and intracranial rinds of enhancing tumor (Right) Axial T1WI C+ FS MR demonstrates a meningioma of the central skull base encasing and narrowing the right internal carotid artery The tumor extends through the porus trigeminus into the prepontine cistern A dural “tail” is present medially (Left) Axial T2WI MR in the same patient demonstrates a central skull base meningioma that is approximately isointense to gray matter with a CSF-vascular cleft between the tumor and the displaced temporal lobe The small posterior fossa component is associated with deformity of the pons (Right) Sagittal T1WI MR shows a globose configuration to this clival meningioma The CSF/vascular cleft between the lesion and the brainstem confirms its extraaxial location 1236 Diagnostic Imaging Head and Neck (Left) Sagittal T1WI C+ MR shows a globose mass at the anterior foramen magnum buckling the medulla posteriorly The broad base along the dura favors meningioma over other foramen magnum lesions, such as schwannoma (Right) Axial T1WI C+ MR shows an anterior foramen magnum meningioma lying medial to the left vertebral artery Given the plethora of critical vascular and neural structures at the skull base, resection of even small lesions may be difficult Skull Base Plasmacytoma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Plasmacytoma Skull Base Plasmacytoma Phillip R Chapman, MD Key Facts Terminology Abbreviations: Solitary bone plasmacytoma (SBP), extramedullary plasmacytoma (EMP), multiple myeloma (MM) Definition: Isolated intramedullary or extramedullary neoplasm of plasma cells in absence of clinical or radiographic findings of MM Imaging CT findings SBP: Solitary intraosseous, lytic mass with nonsclerotic margins EMP: Sinonasal mass with secondary osseous invasion of skull base MR findings More sensitive for marrow space involvement and excluding additional small/early lesions Top Differential Diagnoses Multiple myeloma Skull base metastasis Invasive pituitary macroadenoma Chordoma Pathology Monoclonal proliferation of immunoglobulin-secreting plasma cells Clinical Issues Symptoms: Local pain, headache, cranial nerve deficits M > F in 5th-9th decade SBP has higher rate of conversion to MM than EMP If skull base plasmacytoma diagnosed, complete clinical and radiologic work-up for MM required 1237 Diagnostic Imaging Head and Neck (Left) Sagittal T1WI MR in a 61-year-old man demonstrates a large solitary mass expanding the clivus, obliterating the sphenoid sinus and extending into the posterior nasal cavity and nasopharynx The plasmacytoma is slightly hyperintense to brain parenchyma (Right) Sagittal T1WI C+ MR in the same patient shows heterogeneous enhancement of the lesion without necrosis Dural thickening is noted posteriorly as epidural extension begins to compress the medulla (Left) Coronal bone CT in a 45-year-old woman with sinus pain demonstrates an expansile mass centered in the left sphenoid bone The mass expands medially into the sphenoid sinus and erodes medial floor of the middle cranial fossa The margins of the tumor are relatively sharp, and in some areas there is preservation of thin eggshell margin of cortical bone (Right) Coronal T1WI C+ MR in the same patient demonstrates homogeneous enhancement of the skull base plasmacytoma P.V(1):83 TERMINOLOGY Abbreviations Solitary bone plasmacytoma (SBP) Extramedullary plasmacytoma (EMP) Multiple myeloma (MM) Definitions Solitary bone plasmacytoma Monoclonal plasma cell neoplasm of bone marrow seen in absence of MM Extramedullary plasmacytoma Solitary extraosseous plasma cell proliferation in absence of MM 1238 Diagnostic Imaging Head and Neck Malignant plasmacytoma Focal intramedullary or extramedullary tumor in context of MM Once diagnosis of MM is established, most no longer use term “plasmacytoma” IMAGING General Features Best diagnostic clue CT shows solitary intraosseous mass causing lytic destruction of skull base Location SBP: Epicenter is marrow space of sphenoid, temporal bone (petrous), or occipital bones Soft tissue mass may be isolated to bone Can have significant extraosseous soft tissue component EMP: Involves skull base secondarily when lesion originates in sinonasal cavities, orbit, or nasopharynx Sinonasal region is most common site of origin Predominantly extraosseous with secondary skull base invasion EMPs that occur in nasopharynx or sphenoid sinus can invade clivus and be indistinguishable from SBPs Calvarial marrow space Dura (rare) Leptomeningeal (rare) Size Variable, often large at presentation Morphology Intraosseous mass with biconvex expansion of involved bone, with or without extraosseous mass Radiographic Findings Radiography SBP: Lucent osseous lesion with nonsclerotic margins EMP: Nonspecific sinus opacification with expansion, bony erosion CT Findings NECT Hyperdense (relative to muscle or brain) soft tissue attenuation CECT Mild-moderate homogeneous enhancement Epidural space involvement common Bone CT Lytic lesion with scalloped, nonsclerotic margins No tumoral calcification, but peripherally displaced osseous fragments may be seen MR Findings T1WI Homogeneous, iso- to hypointense to gray matter (GM) T2WI Homogeneous, isointense to GM most often STIR Homogeneous, iso- or hyperintense to GM FLAIR Homogeneous, iso- or hyperintense to GM T1WI C+ Moderate, homogeneous enhancement Angiographic Findings Hypervascular mass supplied by external carotid artery branches Nuclear Medicine Findings Bone scan No uptake on Tc-99m pertechnetate bone scan (“cold lesion”) Variable uptake on gallium scintigraphy PET/CT Moderate to marked FDG uptake Imaging Recommendations Best imaging tool Bone CT best defines bone margins and cortical involvement MR best defines marrow extent & soft tissue extent of lesion 1239 Diagnostic Imaging Head and Neck Protocol advice Multiplanar MR imaging with axial & coronal T1 & T1 C+ fat-saturation sequences through lesion Follow with bone CT without contrast to assess bony margins & extent of bone destruction Whole body work-up necessary to confirm isolated nature of solitary plasmacytoma & exclude MM DIFFERENTIAL DIAGNOSIS Multiple Myeloma Multiple lesions Diffuse lucent lesions on radiographs & CT MR shows diffusely abnormal bone marrow Skull Base Metastasis Known primary tumor Multiple lesions common Invasive Pituitary Macroadenoma Expansile mass of clivus indistinguishable from pituitary gland Predominant growth vector of macroadenoma is inferior into clivus and sphenoid sinus Superior margin of pituitary gland and suprasellar cistern may appear normal Chordoma Midline clivus location P.V(1):84 May contain calcifications or ossific fragments on CT Typically hyperintense on T2WI MR Non-Hodgkin Lymphoma Soft tissue mass with bony destruction of skull base Secondary invasion of skull base from nasal cavity site of origin Skull Base Meningioma Primary osseous site of origin or secondary skull base invasion (more common) Permeative, sclerotic intraosseous mass on CT Avid enhancement on CT & MR PATHOLOGY General Features SBP: Monoclonal proliferation of immunoglobulin-secreting plasma cells Considered benign in absence of MM criteria and no conversion to MM in year period Staging, Grading, & Classification types Plasmacytic plasmacytomas Plasmablastic plasmacytomas Gross Pathologic & Surgical Features Bony defects filled with soft, red tumor of gelatinous consistency Microscopic Features Plasma cells in reticular stroma Plasmacytic plasmacytomas Mature plasma cells with eccentric round nuclei, condensed clumped chromatin, basophilic cytoplasm, prominent pale Golgi zone Plasmablastic plasmacytomas Plasma cells with large vesicular nuclei, prominent nucleoli, amphophilic to basophilic cytoplasm, small often indistinct Golgi zone CLINICAL ISSUES Presentation Most common signs/symptoms Highly dependent on lesion location Local pain & headache Various cranial neuropathies Demographics Age Most present in 5th to 9th decade Gender M>F 1240 Diagnostic Imaging Head and Neck EMP: Occurs predominately in males Ethnicity More common in African-American patients Epidemiology Solitary bone plasmacytomas (all locations) represent only 3% of plasma cell neoplasms EMP: 80% of primary EMPs occur in head & neck Natural History & Prognosis SBP: Progression to MM common with skull base lesions, often within year of initial presentation Higher rates of progression to MM associated with Tumoral proliferative activity Plasmablastic histology Intraosseous skull base location EMP: Conversion to MM is significantly less compared with SBP Treatment Surgical resection Skull base resection highly morbid with cranial nerve dysfunction common post-op Radiation therapy Plasmablastic variety may require higher radiation doses Follow-up critical to monitor for evolution of multiple myeloma DIAGNOSTIC CHECKLIST Consider When plasmacytoma diagnosed, patient needs complete work-up for MM If no MM is present, then lesion considered benign plasmacytoma Routine follow-up is then employed to watch for possible emergence of MM Image Interpretation Pearls SBP: CT shows solitary intraosseous, osteolytic soft tissue mass with nonsclerotic margins Use enhanced MR with fat suppression to exclude additional lesions in commonly overlooked regions Mandibular condyle, greater wing of sphenoid, occipital condyle, calvarium, upper cervical spine Reporting Tips Include broad differential for solitary, expansile clival lesion Recommend whole body work-up, including skeletal survey, MR, or PET/CT to exclude additional lesions SELECTED REFERENCES Bret P et al: [Solitary plasmacytoma of the sphenoid A case report] Neurochirurgie 48(5):431-5, 2002 Schwartz TH et al: Association between intracranial plasmacytoma and multiple myeloma: clinicopathological outcome study Neurosurgery 49(5):1039-44; discussion 1044-5, 2001 Vijaya-Sekaran S et al: Solitary plasmacytoma of the skull base presenting with unilateral sensorineural hearing loss J Laryngol Otol 113(2):164-6, 1999 Okamoto K et al: Solitary plasmacytomas of the occipital bone: a report of two cases Eur Radiol 7(4):503-6, 1997 Provenzale JM et al: Craniocerebral plasmacytoma: MR features AJNR Am J Neuroradiol 18(2):389-92, 1997 Mantyla R et al: Intracranial plasmacytoma: a case report Neuroradiology 38(7):646-9, 1996 Bindal AK et al: Management of intracranial plasmacytoma J Neurosurg 83(2):218-21, 1995 Toland J et al: Plasmacytoma of the skull base Clin Radiol 22(1):93-6, 1971 P.V(1):85 Image Gallery 1241 Diagnostic Imaging Head and Neck (Left) Sagittal T1WI MR in an 82-year-old man with headache and abnormal sinus CT reveals a solitary infiltrating plasmacytoma of the basisphenoid bulging anteriorly into the sphenoid sinus The lesion is distinct from the inferior margin of the pituitary gland (Right) Axial T2WI MR in the same patient shows the mass is slightly hyperintense and extends into the sphenoid sinus and laterally into the left cavernous sinus, encasing the left internal carotid artery (Left) Axial T1WI C+ FS MR in the same patient shows solid homogeneous enhancement without necrosis or flow voids Notice the anterior margin of the mass is easily distinguished from the enhancing mucosa of the sphenoid sinus (Right) Coronal T1WI C+ FS MR (delayed) in the same patient shows progressive contrast enhancement of the plasmacytoma , making it difficult to separate the mass from enhancing pituitary tissue This plasmacytoma mimics an invasive macroadenoma 1242 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a 72-year-old man with headaches, diplopia, and MM reveals a “solitary” lytic mass of the right petrous apex This plasmacytoma invades the cochlea and internal auditory canal (Right) Axial T1WI C+ FS MR in the same patient shows moderate enhancement of this malignant plasmacytoma of the petrous apex There is encasement of petrous internal carotid artery and erosion into the inner ear and IAC posteriorly Skull Base Multiple Myeloma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Multiple Myeloma Skull Base Multiple Myeloma Phillip R Chapman, MD Key Facts Terminology Malignant monoclonal plasma cell proliferation Imaging CT shows osteolytic lesion(s) in 90% of patients Lesions of skull base with additional lytic foci of calvaria and facial bones MR is most sensitive for evaluation of marrow involvement & assessing soft tissue characteristics Homogeneous, isointense to gray matter on T1 & T2WI with moderate, homogeneous enhancement Skeletal survey still most widely used approach for staging and surveillance Top Differential Diagnoses Skull base metastases Plasmacytoma Non-Hodgkin lymphoma Clinical Issues Most patients > 40 years (average = 62 years) 70% men Patients have localized pain and cranial neuropathy depending on lesion location Systemic symptoms related to anemia, renal failure, hypercalcemia Diagnostic Checklist Key to imaging diagnosis is demonstrating multiple osseous lesions Use T1 MR C+ FS images to evaluate commonly overlooked regions of skull base & face Petrous apex, mandibular condyle, occipital condyle, greater wing of sphenoid Whole body imaging is recommended to evaluate for extracranial disease 1243 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a 62-year-old man with multiple myeloma and month history of a right facial nerve palsy demonstrates a large lytic lesion within the posterior skull base An additional lesion is appreciated in the left pterygoid process (Right) Axial T1WI C+ FS MR in the same patient shows homogeneously enhancing osseous and extraosseous mass destroying the mastoid segment of the right temporal bone and obliterating the stylomastoid foramen (Left) Axial T1WI MR in a 72-year-old man shows a large infiltrating homogeneous mass expanding the basisphenoid, replacing normal fat in the clivus and obliterating the sphenoid sinus Tumor extends bilaterally into the cavernous sinuses and partially encases the internal carotid arteries (Right) Coronal T1WI C+ FS MR in the same patient shows the dominant mass in the clivus with additional smaller myelomatous lesions in the calvaria and right infratemporal fossa P.V(1):87 TERMINOLOGY Abbreviations Multiple myeloma (MM) Synonyms Malignant plasmacytoma, diffuse myelomatosis Definitions Malignant monoclonal plasma cell neoplasm IMAGING Imaging Recommendations 1244 Diagnostic Imaging Head and Neck Best imaging tool CT optimally shows lytic nature of lesions in bony skull base MR best for evaluating soft tissue characteristics & marrow infiltration Protocol advice Multiplanar T1 sequences with contrast-enhanced T1 images with fat suppression for direct comparison Best for evaluating marrow space abnormalities Radiographic Findings Classic “punched out” lytic lesions of calvaria CT Findings Bone CT Multiple intraosseous lytic lesions with nonsclerotic margins MR Findings T1WI Homogeneous, isointense to gray matter (GM) T2WI Homogeneous, typically isointense to GM STIR Homogeneous, iso- or hyperintense to GM T1WI C+ FS Moderate, homogeneous enhancement Less often heterogeneous enhancement Nuclear Medicine Findings Bone scan No uptake on Tc-99m pertechnetate bone scan (“cold lesion”) DIFFERENTIAL DIAGNOSIS Skull Base Metastases Often late stage with known primary extracranial neoplasm (lung, breast, colon) Skull Base Plasmacytoma Isolated plasma cell proliferation in absence of MM Non-Hodgkin Lymphoma Lymphoproliferative neoplasm with extranodal, extralymphatic invasion of skull base Invasive Pituitary Macroadenoma Macroadenoma with dominant growth pattern inferiorly into clivus and sphenoid sinus PATHOLOGY Staging, Grading, & Classification Salmon and Durie PLUS staging of MM Gross Pathologic & Surgical Features Brownish, gelatinous tumor with associated trabecular bone loss Microscopic Features Uniform plasma cell infiltrate with eccentric nuclei and basophilic cytoplasm CLINICAL ISSUES Presentation Most common signs/symptoms Pain at site of lesion Site-dependent cranial neuropathy Diplopia, compressive optic neuropathy Demographics Age Majority > 40 years (average = 62) Gender M > F (70% vs 30%) Epidemiology Associated with exposure to radiation & agricultural agents Treatment Oral regimen of melphalan and prednisone has been mainstay of therapy Newer treatments include thalidomide, bortezomid, lenalidomide Autologous stem cell transplantation prolongs survival DIAGNOSTIC CHECKLIST Image Interpretation Pearls 1245 Diagnostic Imaging Head and Neck Use T1 MR C+ FS images to evaluate commonly overlooked regions of skull base & face Petrous apex, mandibular condyle, occipital condyle, greater wing of sphenoid Reporting Tips Can be difficult to differentiate MM from extensive metastatic disease If skull base & calvarial lesions identified, whole body imaging recommended to evaluate for additional lesions SELECTED REFERENCES Delorme S et al: Imaging in multiple myeloma Eur J Radiol 70(3):401-8, 2009 Lütje S et al: Role of radiography, MRI and FDG-PET/CT in diagnosing, staging and therapeutical evaluation of patients with multiple myeloma Ann Hematol 88(12):1161-8, 2009 Shortt CP et al: Whole-Body MRI versus PET in assessment of multiple myeloma disease activity AJR Am J Roentgenol 192(4):980-6, 2009 Baur-Melnyk A et al: Role of MRI for the diagnosis and prognosis of multiple myeloma Eur J Radiol 55(1):56-63, 2005 Skull Base Metastasis > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Metastasis Skull Base Metastasis Phillip R Chapman, MD Key Facts Terminology Metastatic disease affecting osseous skull base ± adjacent intracranial structures (dura, leptomeninges, & cranial nerves) Imaging Best clue: Enhancing skull base (osseous or extraosseous) mass in patient with known extracranial primary neoplasm Enhanced T1 MR is best overall modality Osseous metastasis: Enhancing marrow space mass ± extraosseous extension Dural metastasis: Enhancing, infiltrating dural-based lesion Leptomeningeal disease: Nodular pial enhancement most conspicuous in basilar cisterns and along cranial nerves CT: Patterns of bone involvement are variable Lytic with irregular margins Sclerotic Permeative or mixed permeative-sclerotic Top Differential Diagnoses Multiple myeloma Non-Hodgkin lymphoma Skull base meningioma Chordoma Chondrosarcoma Pathology Source of mets: Breast cancer (40%) > lung cancer (14%) > prostate cancer (12%) Diagnostic Checklist Consider metastatic disease if skull base lesion seen in patient with known malignancy who develops craniofacial pain or cranial neuropathy 1246 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a lung cancer patient with new left facial pain and dizziness shows a lytic lesion of the left sphenoid body Note erosion of the anterior vidian canal and cortical irregularity of the margins of pterygopalatine fossa (Right) Axial T1WI C+ FS MR in the same patient reveals an enhancing mass of the sphenoid wing with dural invasion Close inspection shows leptomeningeal tumor in right internal auditory canal and tiny pontine brain metastasis (Left) Coronal T1WI C+ MR in a 60 year old with breast cancer and right facial palsy shows a smooth enhancing dural metastasis along the squamous temporal bone and petrous ridge Tumor extends to the geniculate ganglion Note extracranial tumor lateral to the involved squamous temporal bone (Right) Axial T1WI C+ MR in the same patient shows thick dural tumor infiltrating the petrous ridge with perineural extension to CN7 geniculate ganglion to the fundus of the IAC P.V(1):89 TERMINOLOGY Definitions Metastatic disease affecting osseous skull base ± adjacent intracranial structures including dura, leptomeninges, & cranial nerves IMAGING General Features Best diagnostic clue Enhancing osseous or extraosseous mass of skull base in patient with known extracranial primary malignancy Location 1247 Diagnostic Imaging Head and Neck Can occur anywhere in skull base ± calvaria Size Variable Often large dominant symptomatic lesion with subsequent detection of additional lesions Small “strategically located” lesions can cause profound symptoms Morphology Pattern of disease highly variable dependent on anatomic site Imaging Recommendations Best imaging tool Enhanced MR is best for evaluating skull base lesions within bone & delineating invasion into adjacent soft tissues Protocol advice Axial and coronal T1WI without fat saturation to identify marrow lesions T1WI C+ FS in identical axial & coronal planes to demonstrate osseous and extraosseous tumor CT Findings CECT Skull base & calvarial metastases: Enhancing mass infiltrating bone marrow Bone CT Patterns of bone involvement are highly variable Lytic with irregular margins Permeative destructive Sclerotic MR Findings T1WI Hypointense lesion in marrow replaces normal ↑ signal fat T2WI Hyperintense marrow space lesion T1WI C+ FS Enhancing marrow space mass ± extraosseous extension Nuclear Medicine Findings PET/CT Combination of lytic-destructive lesions on CT with moderate-to-marked FDG uptake DIFFERENTIAL DIAGNOSIS Multiple Myeloma Plasma cell neoplasm Multiple enhancing lytic lesions of skull base & calvarium Non-Hodgkin Lymphoma Lymphoproliferative neoplasm Can have multifocal extranodal & extralymphatic lesions of skull base and dura Skull Base Meningioma Primary dural-based enhancing neoplasm(s) with secondary sclerosis or invasion of skull base May be multiple & mimic metastatic disease Idiopathic Inflammatory Pseudotumor Enhancing, nonneoplastic fibroinflammatory process of orbital apex, cavernous sinus, or skull base Solitary Central Skull Base Mass Chordoma Chondrosarcoma Invasive pituitary macroadenoma PATHOLOGY General Features Etiology Common primary malignancies Breast cancer (40%) Lung cancer (14%) Prostate cancer (12%) CLINICAL ISSUES Presentation Most common signs/symptoms Craniofacial pain & progressive unilateral cranial neuropathy 1248 Diagnostic Imaging Head and Neck Demographics Epidemiology Skull base metastasis from extracranial primaries occurs in 4% of cancer patients Treatment Radiation therapy is mainstay of treatment DIAGNOSTIC CHECKLIST Image Interpretation Pearls Remember to evaluate subarachnoid space, dura, and osseous structures of skull base in metastatic work-up SELECTED REFERENCES Nayak L et al: Intracranial dural metastases Cancer 115(9):1947-53, 2009 Maroldi R et al: Metastatic disease of the brain: extra-axial metastases (skull, dura, leptomeningeal) and tumour spread Eur Radiol 15(3):617-26, 2005 Skull Base Chondrosarcoma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Chondrosarcoma Skull Base Chondrosarcoma Rebecca Cornelius, MD Key Facts Terminology Skull base chondrosarcoma (CSa-SB): Chondroid malignancy of skull base Imaging Typical location off-midline, centered on petro-occipital fissure (POF) CT Characteristic chondroid tumor matrix calcification in 50% Arc or ring-like calcifications Sharp, narrow, nonsclerotic transition zone to adjacent normal bone MR High T2 signal with scattered hypointense foci (calcifications) Heterogeneously enhancing Whorls of enhancing lines within tumor matrix often seen Top Differential Diagnoses Chordoma Meningioma Skull base metastasis Plasmacytoma Petrous apex cholesteatoma Clinical Issues Typically middle-aged patient with insidious onset of headache & cranial nerve palsies (CN6) Diagnostic Checklist Is lesion off-midline (CSa) or in midline (chordoma)? Do calcifications represent arc-whorl intralesional calcifications (CSa) or fragmented destroyed bone (chordoma)? 1249 Diagnostic Imaging Head and Neck (Left) Axial graphic depicts the classic location of a chondrosarcoma of the skull base centered in the left petrooccipital fissure Note the normal right petro-occipital fissure Chondroid calcifications, depicted in yellow, are present within the lesion (Right) Axial T2WI MR shows the typical location and signal of a skull base chondrosarcoma The mass is centered off-midline at the left petro-occipital fissure and is hyperintense on this long TR sequence (Left) Axial T1WI C+ MR shows mottled enhancement within a chondrosarcoma centered at the left petro-occipital fissure Calcified matrix is seen as a focal low signal intensity area within the otherwise enhancing tumor The left internal carotid artery is patent (Right) Axial bone CT demonstrates typical chondroid calcification in a left petro-occipital fissure chondrosarcoma In this case, no significant destruction of the adjacent petrous apex is appreciated P.V(1):91 TERMINOLOGY Abbreviations Chondrosarcoma-skull base (CSa-SB) Definitions CSa-SB: Chondroid malignancy of skull base IMAGING General Features Best diagnostic clue Chondroid matrix in tumor centered on petro-occipital fissure (POF) Location 1250 Diagnostic Imaging Head and Neck Petro-occipital fissure (2/3) Anterior basisphenoid (1/3) Usually solitary but may be multiple Size Variable, usually > cm Morphology Well-circumscribed, lobulated margins CT Findings NECT Soft tissue component is relatively dense CECT Variable, heterogeneous enhancement Bone CT Characteristic chondroid calcification in tumor matrix 50% have matrix calcification Arc or ring-like calcifications Sharp, narrow, nonsclerotic transition zone to adjacent normal bone > 50% have associated bone destruction MR Findings T1WI Low to intermediate signal intensity relative to gray matter ↓ signal foci within tumor may suggest underlying coarse matrix mineralization or fibrocartilaginous elements T2WI High signal Hypointense foci (calcifications) less conspicuous than on CT PD/intermediate High signal T1WI C+ Heterogeneous enhancement Whorls of enhancing lines within tumor matrix often seen Angiographic Findings Avascular or hypovascular mass Internal carotid artery displacement ± encasement Imaging Recommendations Best imaging tool Multiplanar, gadolinium enhanced MR of skull base Protocol advice Axial & coronal skull base bone CT for evaluation of chondroid matrix & pattern of bone destruction Enhanced MR images with fat suppression to best define tumor margins Magnetic resonance angiography (MRA) & magnetic resonance venography (MRV) helpful to assess vascular involvement preoperatively Preoperative angiography with test occlusion if vessel sacrifice necessary DIFFERENTIAL DIAGNOSIS Chordoma Destructive clival lesion; bone fragments within matrix Midline > lateral location Low T1 & high T2 MR signal; enhancing mass Chondroid chordomas more aggressive & worse prognosis Meningioma Calcification in meningioma can mimic chondroid matrix Hyperostosis possible; not typically destructive Low to intermediate T2 MR signal; enhancing with dural “tails” Skull Base Metastasis Bone CT: Destructive mass that can be anywhere in skull base MR: Often multiple enhancing, invasive lesions Known primary tumor Plasmacytoma Usually more midline, within clivus 1251 Diagnostic Imaging Head and Neck T2 signal is low to intermediate Over 50% have concurrent multiple myeloma Petrous Apex Cholesteatoma Expansile, smooth petrous apex lesion Low T1, high T2 MR lesion without enhancement Chondromyxoid Fibroma Rare, expansile, noninfiltrating skull base mass Areas of ground-glass density may be seen Appearance may overlap with CSa-SB Nasopharyngeal Carcinoma Main mass is in nasopharyngeal mucosal space Skull base invasion may occur in clivus or petro-occipital fissure PATHOLOGY General Features Etiology Arises from remnants of embryonal cartilage, endochondral bone, or from primitive mesenchymal cells in meninges May arise from metaplasia of meningeal fibroblasts Genetics May complicate Ollier disease & Maffucci syndromes P.V(1):92 Staging, Grading, & Classification Classification Conventional CSa: Hyaline (7%), myxoid (30%), or mixed (63%) Clear cell Mesenchymal Dedifferentiated Grading from low grade to high grade Based on degree of cellularity, pleomorphism, mitoses, & multinucleated cells Gross Pathologic & Surgical Features Smooth, lobulated mass “welling up” from petro-occipital fissure Cut surface shows a gray-white, glistening parenchyma Microscopic Features Hypercellular tumor composed of chondrocytes with hyperchromatic, pleomorphic nuclei & prominent nucleoli Binucleate or multinucleate cells are rule Hyaline matrix may calcify in “ringlets” Intercellular matrix is solid in hyaline type compared to mucinous/gelatinous matrix in myxoid or mixed types Histology may overlap with or be confused with that of chordoma Histology particularly confusing in chondroid chordoma, myxoid chondrosarcoma Differentiation facilitated by immunohistochemical staining CLINICAL ISSUES Presentation Most common signs/symptoms Abducens (CN6) palsy Headache Mean duration of symptoms at diagnosis = 27 months Other signs/symptoms Other cranial nerve palsies (CNs 3, 5, 7, 8) Clinical profile Middle-aged patient with insidious onset of headaches & cranial nerve palsies Demographics Age Range: 10-80 years old Mean: 40 years old Epidemiology 6% of all skull base tumors 1252 Diagnostic Imaging Head and Neck 75% of all cranial CSa occur in skull base Natural History & Prognosis Prognosis depends on extent at diagnosis, histologic grade, & completeness of surgical resection Disease-specific 10-year survival rates of 99% recently reported Most central skull base chondrosarcomas are well- to moderately differentiated High-grade CSa metastasizes to bones & lung more frequently Conventional CSa: Indolent growth pattern Most are slow growing, locally invasive, but rarely metastasize Mesenchymal & dedifferentiated forms: Aggressive behavior; poor prognosis Treatment Aggressive resection associated with significant morbidity and low likelihood of complete resection Basal subfrontal approach used for tumor that invades clivus & extends anteriorly into sphenoid & ethmoid sinuses Subtemporal & preauricular infratemporal approach used when CSa extends laterally beyond petrous internal carotid artery Combined radical resection & postoperative, high-dose, fractionated precision conformal radiation therapy most often utilized Charged particle RT (protons or carbon ions) alone or combined with subtotal resection DIAGNOSTIC CHECKLIST Consider Is lesion in off-midline (CSa) vs midline (chordoma)? Do calcifications represent arc-whorl intralesional calcifications (CSa) or fragmented destroyed bone (chordoma)? Does patient have known primary neoplasm (metastasis), myeloma (plasmacytoma), or nasopharyngeal mass (nasopharyngeal carcinoma)? Image Interpretation Pearls Classic appearance: Heterogeneously enhancing tumor located at petro-occipital fissure with hyperintense signal on T2 MR CT shows chondroid mineralization & bone destruction When no tumor matrix found, difficult to tell from CSa plasmacytoma, focal metastasis, or chondromyxoid fibroma SELECTED REFERENCES Amichetti M et al: A systematic review of proton therapy in the treatment of chondrosarcoma of the skull base Neurosurg Rev 33(2):155-65, 2010 Ares C et al: Effectiveness and safety of spot scanning proton radiation therapy for chordomas and chondrosarcomas of the skull base: first long-term report Int J Radiat Oncol Biol Phys 75(4):1111-8, 2009 Gallia GL et al: Skull base chondrosarcoma presenting with hemorrhage Can J Neurol Sci 36(6):774-5, 2009 Hong P et al: Chondrosarcoma of the head and neck: report of 11 cases and literature review J Otolaryngol Head Neck Surg 38(2):279-85, 2009 Samii A et al: Surgical treatment of skull base chondrosarcomas Neurosurg Rev 32(1):67-75; discussion 75, 2009 Abdelmalek M et al: Recurrent chondrosarcoma of the right skull base in a patient with Maffucci syndrome Am J Clin Dermatol 9(1):61-5, 2008 Cho YH et al: Chordomas and chondrosarcomas of the skull base: comparative analysis of clinical results in 30 patients Neurosurg Rev 31(1):35-43; discussion 43, 2008 Gelderblom H et al: The clinical approach towards chondrosarcoma Oncologist 2008 Mar;13(3):320-9 Review Erratum in: Oncologist 13(5):618, 2008 P.V(1):93 Image Gallery 1253 Diagnostic Imaging Head and Neck (Left) Axial bone CT demonstrates a large skull base chondrosarcoma with exuberant calcified chondroid matrix This large lesion shows typical CT features, including location at the POF and chondroid matrix (Right) Axial bone CT in the same patient shows rounded and arc-like calcified foci in the center of the large chondrosarcoma Up to 50% of cases of chondrosarcomas demonstrate matrix calcification Note slight narrowing of the left vidian canal (Left) Axial T2WI MR shows a typical case of petro-occipital fissure skull base chondrosarcoma The mass is centered off-midline and is diffusely hyperintense on this T2 sequence Inferiorly the high signal tumor involves the lateral clivus (Right) Axial T2WI MR in the same patient cephalad to the previous image shows that the mass involves the right petrous apex and extends into the right cerebellopontine angle cistern (CPA) The petrous carotid artery is displaced anteriorly 1254 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in the same patient demonstrates that the chondrosarcoma enhances avidly Again note the petrous apex and CPA cistern involvement Most skull base chondrosarcomas emanate from the petrooccipital fissure However, when they become large it may be hard to see the point of origin (Right) Coronal T1WI C+ FS MR in the same patient delineates tumor invasion into the jugular foramen and occipital condyle Note the normal left occipital condyle Skull Base Osteosarcoma > Table of Contents > Part V - Skull Base > Section - Skull Base Lesions > Diffuse or Multifocal Skull Base Disease > Skull Base Osteosarcoma Skull Base Osteosarcoma Rebecca Cornelius, MD Key Facts Terminology Neoplasm composed of malignant cells producing osteoid matrix, or immature bone Imaging Very rare in skull base → clivus, parasellar, sphenoid wing, & anterior skull base CT findings Often destructive & expansile May be lytic or blastic May show tumor bone formation & periosteal reaction MR findings Heterogeneous low to intermediate T1 signal Intermediate to high T2 signal; bone components ↓ T2WI signal Marrow/soft tissue enhancement Top Differential Diagnoses Skull base metastasis Chordoma Meningioma Plasmacytoma Pathology May occur secondary to prior irradiation Associated with Paget disease, fibrous dysplasia, giant cell tumor, Ollier disease, chronic osteomyelitis Clinical Issues Nonspecific symptoms: Swelling, pain Present in 3rd-4th decade; M = F Difficult to completely resect due to proximity to critical structures within skull base Relatively resistant to XRT 1255 Diagnostic Imaging Head and Neck (Left) Sagittal T1WI MR demonstrates an expansile, intermediate signal clival osteosarcoma Normal pituitary parenchyma is seen at the superior aspect of the mass This finding helps to exclude invasive pituitary adenoma from the differential diagnosis (Right) Sagittal T1WI C+ MR in the same patient shows heterogeneous enhancement throughout the mass Note extension into the sphenoid sinus Nonenhancing foci with hypointense signal may represent areas of osteoid (Left) Axial T2WI MR in the same patient shows heterogeneous, intermediate signal with areas of higher signal , which may be due to focal necrosis Curvilinear lower signal area may represent an area of internal calcification (Right) Axial bone CT in the same patient shows that this osteosarcoma is predominantly lytic There is some expansion of the clivus with a large area of bone destruction posteriorly This lesion does not show osteoid matrix P.V(1):95 TERMINOLOGY Abbreviations Osteosarcoma of skull base (OSa-SB) Definitions Neoplasm composed of malignant spindle cells producing osteoid or immature bone IMAGING General Features Best diagnostic clue Aggressive, ill-defined mass arising from bone with soft tissue & osteoid matrix Location Clivus, sphenoid-sella, greater sphenoid wing, anterior skull base 1256 Diagnostic Imaging Head and Neck Very rare in skull base More common in mandible and maxilla Size 3-6 cm Imaging Recommendations Best imaging tool Multiplanar contrast-enhanced MR best for mapping lesion margins, evaluating invasion of adjacent soft tissues & marrow Bone CT shows internal osteoid matrix & periosteal reaction to better advantage CT Findings Bone CT May be lytic or blastic Bone of origin may show expansion ± destruction May show tumor bone formation or malignant periosteal reaction MR Findings T1WI Heterogeneous, low to intermediate signal T2WI Heterogeneous intermediate to high T2 signal with densely ossified components showing ↓ signal Telangiectatic type may show fluid-fluid levels T1WI C+ FS Marrow/soft tissue components show enhancement DIFFERENTIAL DIAGNOSIS Skull Base Metastasis Patient has known primary neoplasm Lesions often multiple Lytic, poorly defined, non-bone-forming Chordoma Midline clival mass Hyperintense on T2WI MR Meningioma Typically dural based with secondary osseous involvement May cause sclerosis (hyperostosis) of adjacent skull base Plasmacytoma Solitary or multiple if in setting of multiple myeloma Homogeneous, lytic, & well defined PATHOLOGY General Features Etiology Primary etiology unknown May occur secondary to prior irradiation Genetics Mutations of RB1 and p53 tumor suppressor genes appear to play a role in development of some osteosarcomas, especially high-grade tumors Associated abnormalities May be associated with Paget disease, fibrous dysplasia, giant cell tumor, solitary or multiple osteochondroma, enchondroma, Ollier disease Staging, Grading, & Classification Classification based upon histology: Osteoblastic, chondroblastic, fibroblastic, telangiectatic, & juxtacortical types Grading (low, intermediate, high) based on degree of cellular atypia and recognizable histologic architecture Microscopic Features Osteoid production by atypical neoplastic osteoblasts CLINICAL ISSUES Presentation Most common signs/symptoms Swelling, mass, & pain Other signs/symptoms Cranial nerve deficits Demographics 1257 Diagnostic Imaging Head and Neck Age 3rd-4th decade Gender M=F Epidemiology Most common primary bone malignancy overall but only 6-10% in head & neck Natural History & Prognosis Poor overall survival Treatment Complete surgical excision; chemotherapy increases 5-year survival if complete resection not possible Surgery associated with high morbidity due to critical skull base anatomy SELECTED REFERENCES Chennupati SK et al: Osteosarcoma of the skull base: case report and review of literature Int J Pediatr Otorhinolaryngol 72(1):115-9, 2008 Smith RB et al: National Cancer Data Base report on osteosarcoma of the head and neck Cancer 98(8):1670-80, 2003 Section - Skull Base and Facial Trauma Introduction and Overview Skull Base and Facial Trauma Overview > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Introduction and Overview > Skull Base and Facial Trauma Overview Skull Base and Facial Trauma Overview Michelle A Michel, MD Summary Thoughts: Skull Base & Facial Trauma Fractures (fxs) of the skull base require considerable force and are often associated with other craniofacial injuries Blunt trauma is responsible for over 90% of skull base and facial fxs & are frequently related to vehicular accidents Injuries may range from a solitary linear fracture to complex injuries involving the craniofacial skeleton In these cases, associated intracranial injuries, such as cerebral contusion, intra-/extraaxial hemorrhage, dural tears, & vascular injuries are common It is important to understand the normal anatomy of the facial skeleton & skull base as covered elsewhere in this book The objective of imaging is these trauma patients is to depict the location & extent of fxs and to recognize associated injuries to vital structures Accurate imaging interpretation also aids in surgical planning and in prevention of complications Imaging Approaches & Indications High-resolution bone algorithm CT is the modality of choice for imaging skull base & facial trauma Thin slice (0.6-1 mm) axial images extend from the skull vertex through the facial bones with coronal reformatted images generated from the axial data set Sagittal reformatted images are helpful for assessing injuries to the anterior & central skull base, particularly in patients with CSF leak 3D-reformatted images of facial fxs are beneficial for surgical planning as they provide a more anatomic representation of fracture malalignment prior to reconstruction In patients with CSF leak or recurrent meningitis, most defects in the anterior & central skull base are demonstrated with high-resolution bone CT If a defect is not identified on bone CT or there are multiple fxs and it is unclear which is the source of the leak, CT cisternography may better delineate the leak site Arterial vascular injuries may be seen with central skull base fxs that traverse the carotid canals CTA can be performed in these patients to assess for dissection, traumatic pseudoaneurysm, or presence of carotid-cavernous fistula (CCF) Fxs of the petrous temporal bones and posterior fossa may extend into major venous sinuses, resulting in posterior fossa epidural hematoma or post-traumatic venous thrombosis CTV or MRV may be obtained in such cases Conventional angiography is typically not necessary but used for treating vascular complications Cerebral injuries are often seen in high-impact trauma Although MR is not performed initially, it is more sensitive for assessing the degree of parenchymal injury Approaches to Imaging Issues in Skull Base & Facial Trauma Skull Base Trauma Anterior skull base (ASB) ASB (frontobasal) trauma is frequently associated with injury to the sinonasal cavities and orbits The majority of these patients have facial injuries, including fxs of the forehead, orbital roofs, & cribriform plates (CP) Imaging analysis should address the following questions: Do fracture lines involve the CP or traverse the anterior or posterior walls of the frontal sinuses? 1258 Diagnostic Imaging Head and Neck Do fxs involve the orbital apex or optic canals? Central skull base (CSB) CSB (lateral basal) trauma may involve the sphenoid sinus walls, cavernous sinuses, & clivus and may present with carotid vascular injury or CNs 3, 4, 6, or CNV1-3 deficits Imaging analysis should address the following questions: Are the walls of the sphenoid sinuses, carotid canals, & clivus intact? Do the cavernous sinuses appear symmetric? Temporal bone Petrous temporal fxs typically have a longitudinal or transverse trajectory The longitudinal type is more common, traverses the mastoid & middle ear cavities, terminates in the squamous portion, and may result in ossicular chain disruption Transverse fxs often extend into the occipital bone after traversing the inner ear Imaging analysis should address the following questions: Is the main fracture line parallel (longitudinal) or perpendicular (transverse) to the petrous ridge? Is the ossicular chain intact? Does the fx traverse the inner ear or CN7 canal? Does the fx traverse the tegmen? Posterior skull base (PSB) Fxs of the occipital bones may be isolated or associated with transverse petrous ridge fxs The fracture may extend into a dural venous sinus, jugular foramen (CN9-11), or CN12 canal Craniocervical junction injuries should also be suspected in these patients Imaging analysis should address the following questions: Does the fracture extend into the transverse sinus, sigmoid sinus, or jugular foramen? Does the fx involve internal auditory canal? Is the hypoglossal canal involved? Facial Trauma Orbital trauma Orbital fxs are classified as: 1) Those involving the orbital walls, frequently the inferior orbital rim, and 2) the orbital “blowout” fracture Blowout fxs may involve the orbital floor or medial orbital wall, but the inferior orbital rim remains intact Imaging analysis should address the following questions: Is there entrapment of the inferior ± medial rectus muscles & fat? How large & displaced are the fx fragments? Is the fracture isolated or are other orbital or facial fxs present (ZMC, NOE, Le Fort)? Trans-facial fracture (Le Fort) There are types of Le Fort fxs, and a consistent feature of all types is the presence of bilateral pterygoid plate fxs Le Fort I is a horizontal fracture through the maxilla involving the piriform aperture Le Fort II is a pyramidal fracture involving the nasofrontal junction, infraorbital rims, medial orbital walls & orbital floors, & zygomaticomaxillary suture lines Le Fort III (craniofacial separation) consists of fxs at the nasofrontal junction extending laterally through the lateral orbital walls & zygomatic arches Le Fort fxs are rarely “pure” & are often seen in combination with other fxs Imaging analysis should address the following questions: Which Le Fort types are involved? Are the fxs the same on each side of the face? Are other facial fx patterns present (ZMC, NOE)? P.V(2):3 Zygomaticomaxillary complex fracture (ZMC) The prominent position of the zygomatic arch makes it susceptible to trauma This fracture type was formerly referred to as the “tripod” fracture, however that is a misnomer as the zygoma has involved articulations, and distinct fxs are evident Imaging analysis should address the following questions: How displaced & comminuted is the ZMC fracture? What is the extent of involvement of the orbital floor, orbital apex, & lamina papyracea? How is the lateral orbital wall displaced? Complex midfacial fracture (CMF) The CMF or “facial smash injury” consists of multiple facial fxs that cannot be classified as one of the named patterns (Le Fort, ZMC, NOE) Imaging analysis should address the following questions: Where are the fxs concentrated and are there associated injuries to the orbit or skull base? Naso-orbital-ethmoid fracture (NOE) High-force trauma to the nasal bones is transmitted to the ethmoid sinuses & orbits in NOE fractures The medial canthal tendon (MCT) may be disrupted in these cases & fxs may extend into the lacrimal apparatus Imaging analysis should address the following questions: Is the bone fragment to which the MCT attaches displaced or comminuted? Is the nasal bridge displaced posteriorly into the ethmoids or superiorly into the anterior fossa? Are there injuries to the CP, frontal recess, or globes? 1259 Diagnostic Imaging Head and Neck Mandible fracture Mandible fxs may occur within the row of teeth (parasymphysis, body, or angle) or posterior to the teeth (ascending ramus, subcondylar region, condyle, or coronoid process) The mandible is essentially a “ring or bone” and multiple fxs are common, often bilaterally Fracture fragment displacement is affected by muscular attachments to the bone Imaging analysis should address the following questions: Where are the fxs located & what is the degree & direction of displacement? Is the inferior alveolar foramen or canal involved? Are the condyles subluxed or dislocated? Clinical Implications Understanding the mechanisms and complications of injury is essential for managing skull base trauma The objective of treatment in patients with facial trauma is to stabilize and restore facial anatomy and to provide skeletal support for the function of mastication Treatment is also directed toward relief of early and prevention of late complications Clinical signs of ASB injury include epistaxis, proptosis, chemosis, rhinorrhea, anosmia, & visual deficits In addition to CSF leak, patients with fxs of the posterior frontal sinus wall or cribriform plate are at risk for subsequent meningitis Fxs at the orbital apex & optic canal may cause visual deficits Signs of temporal bone trauma may include postauricular hematoma (Battle sign), hemotympanum, otorrhea, conductive or sensorineural hearing loss, vertigo, or facial weakness Clinical signs of PSB trauma include symptoms of mass effect from epidural hematoma related to dural sinus trauma or lower cranial never deficits In patients with midfacial trauma, injuries to the palate, maxilla, & mandible should be assessed at imaging, as lack of appropriate repair can result in malocclusion Depending on the degree, orbital floor involvement in patients with ZMC fracture will likely require surgical reduction Orbital wall fxs will be treated if there is entrapment of the extraocular muscles, impingement upon the orbital apex or middle cranial fossa, or to prevent globe malposition that is resulting in diplopia or enophthalmos Traumatic telecanthus & damage to the lacrimal drainage pathway are complications of NOE fxs that require surgical intervention Selected References Fraioli RE et al: Facial fractures: beyond Le Fort Otolaryngol Clin North Am 41(1):51-76, vi, 2008 Samii M et al: Skull base trauma: diagnosis and management Neurol Res 24(2):147-56, 2002 Tables Temporal Bone, Skull Base & Facial Trauma Complications Fracture Locations/Type Potential Complications Skull Base Trauma Anterior skull base Posterior wall frontal sinus contaminated fx; cribriform plate fx: CSF leak/cephalocele, CN1 injury; orbital apex or optic canal fx: CN2 injury Central skull base ICA injury: Thrombosis, dissection, pseudoaneurysm, CCF; sphenoid sinus superior wall fx: CSF leak/cephalocele if dural tear CNs at risk: CN3, 4, 6, CNV1-3 Posterior skull base Transvenous sinus fx: Venous sinus thrombosis, epidural hematoma; CNs at risk: CN7-8 (IAC area); CN9-11 (jugular foramen); CN12 (hypoglossal canal) Temporal bone Tegmen mastoideum/tympani fx: CSF leak/cephalocele if dural tear; CNs at risk: CN7 (facial n canal fx), CN8 (transcochlear fx) Orbital Trauma Medial blowout Medial rectus entrapment; diplopia, enophthalmos Inferior blowout Inferior rectus entrapment; infraorbital nerve injury, diplopia, enophthalmos Foreign body Globe rupture; CN2 laceration/transaction; infection Facial Trauma Trans-facial (Le Fort I-III), Traumatic telecanthus, nasolacrimal apparatus injury, epiphora, ZMC, complex midfacial, inferior orbital nerve injury (CNV2), malocclusion, mucocele NOE fxs Mandibular fracture Trismus, inferior alveolar nerve injury, teeth loss P.V(2):4 1260 Diagnostic Imaging Head and Neck Image Gallery (Top) Graphic of endocranial view of the skull base shows multiple fractures with expected complications An ASB fracture crosses the cribriform plate and extends into the optic canal A fracture through the right middle fossa extends through the petrous apex involving the petrous carotid canal An oblique clival fracture extends into the hypoglossal canal A posterior fossa occipital fracture damages the transverse sinus and causes an extraaxial hemorrhage (Bottom) Coronal graphic illustrates a medial and an inferior blowout fracture on the left The medial blowout fracture displaces the lamina papyracea medially into the ethmoid sinus An inferior blowout fracture of the floor of the orbit (maxillary sinus roof) with infraorbital nerve injury is depicted Herniation of the inferior rectus muscle and orbital fat into the maxillary sinus may occur with variably sized floor fractures A blow to the anterior orbit/globe, such as from a baseball, may cause either both or one of these fractures P.V(2):5 1261 Diagnostic Imaging Head and Neck (Top) Frontal graphic demonstrates fractures of the midface and mandible A zygomaticomaxillary complex fracture is shown on the right with involvement of the lateral orbital wall, zygomatic arch, and maxillary walls Trauma to the nasal bridge results in a naso-orbital-ethmoid complex fracture with traumatic telecanthus with the tendon attached to a dominant fracture fragment A fracture of the mandibular body on the right involves the inferior alveolar foramen with inferior alveolar nerve injury (Bottom) Coronal graphic shows lines defining the types of Le Fort fxs Le Fort I (green) involves the nasal aperture and essentially separates the maxilla & palate from the remaining midface Le Fort II (red) traverses the inferior orbital rim and is also known as the “pyramidal fracture” due to its configuration The Le Fort III (black), or craniofacial separation, extends through the zygomatic arches A common feature of all Le Fort fracture types is involvement of the pterygoid plates (not shown) 1262 Diagnostic Imaging Head and Neck Introduction and Overview Temporal Bone Trauma > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Skull Base > Temporal Bone Trauma Temporal Bone Trauma Deborah R Shatzkes, MD Troy Hutchins, MD Key Facts Terminology Temporal bone (T-bone) fracture Imaging Bone algorithm MDCT with coronal reconstructions, CTA/MRA for suspected vascular injury Dedicated brain imaging critical to evaluate for intracranial injuries, present in up to 85% Longitudinal fractures: Vertical plane parallels long axis of petrous ridge (PR) External auditory canal (EAC), middle ear (ME)/ossicular involvement common; otic capsule (OC) involvement rare Transverse fractures: Perpendicular to PR long axis OC involvement, facial nerve (CN7) injury very common; EAC/ME involvement rare Oblique fractures: Mixed features, typically horizontal and parallel to PR long axis OC violating vs OC sparing classification better predicts complications, such as SNHL, CN7 injury, and CSF leak Ossicular injuries: Dislocations > > fractures, incus most commonly involved CN7 injuries: Most commonly at geniculate, often resolve spontaneously All varieties: Assess for tegmen fracture (CSF leak), carotid canal injury, extension to central skull base Top Differential Diagnoses Pseudofractures: Sutures, fissures, canaliculi, aqueducts Diagnostic Checklist Always assess most clinically relevant structures: CN7 canal, otic capsule, tegmen, carotid canal, ossicles Do not misdiagnose a pseudofracture! (Left) Axial bone CT demonstrates linear lucency through anterior wall of EAC representing the normal tympanosquamous fissure ; this was initially misdiagnosed as a fracture A true fracture line extends through the anterior aspect of the glenoid fossa (Right) Coronal bone CT reveals pneumolabyrinth Linear lucency through the otic capsule was initially diagnosed as a fracture but represents the normal singular canal Comparison with the contralateral temporal bone will help exclude pseudofractures 1263 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a longitudinal otic-capsule-sparing fracture extending to the tegmen tympani ; the patient is thus at risk for CSF leak There is widening of the incudomalleolar joint , the most common form of ossicular disruption (Right) Axial bone CT reveals a transverse OC-violating fracture extending through the labyrinthine CN7 canal and the vestibule This medial subtype of transverse fractures often results in complete and permanent sensorineural hearing loss and facial palsy P.V(2):7 TERMINOLOGY Synonyms Temporal bone (T-bone) fracture Definitions Traumatic injury of temporal bone, ossicles IMAGING General Features Best diagnostic clue Bone CT shows fracture line Secondary signs include hemotympanum, pneumolabyrinth, intracranial or extracranial air/hemorrhage near mastoid Unexplained parapharyngeal space air should prompt search for mastoid fracture Morphology Longitudinal fracture: Vertical plane parallels long axis of petrous ridge (PR), run with (not across) petrotympanic fissure Transverse fracture: Perpendicular to PR long axis; from foramen magnum or jugular foramen to middle fossa Oblique fracture: Mixed features, typically horizontal and parallel to PR long axis, crosses petrotympanic fissure Newer classification: Otic capsule (OC) violating vs OC sparing, more clinically relevant OC-violating fractures: Increased incidence of sensorineural hearing loss (SNHL), CN7 injury, & CSF leak 5-20% of fractures violate otic capsule CT Findings Bone CT Longitudinal fractures Often involve temporal squamosa, external auditory canal (EAC), tympanic membrane (TM), middle ear (ME); usually spare otic capsule Hemotympanum & ossicular disruption common CN7 canal involvement most often occurs at geniculate or tympanic segments CN7 injury less common than with transverse fractures Transverse fractures Medial subtype: Posterior petrous surface through IAC to geniculate CN7 canal 1264 Diagnostic Imaging Head and Neck Lateral subtype: Posterior petrous surface through OC Pneumolabyrinth common Frequent CN7 injury, often at geniculate or IAC EAC, TM, ME involved less commonly than in longitudinal fractures Oblique fractures Involve EAC, ME, usually spare otic capsule Ossicular injuries Dislocations > > fractures Incus most commonly fractured ossicle Incudostapedial > incudomalleolar > complete incus dislocation Stapediovestibular disruption: Increasingly diagnosed with high-resolution MDCT Malleus dislocation rare (supported by malleal ligaments, TM attachments) Perilymph fistula (PLF): Oval or round window rupture with communication between middle ear & membranous labyrinth Subtle findings include pneumolabyrinth and fluid at oval/round windows All fracture types: Assess for tegmen fractures, carotid canal injuries, propagation to central skull base, intracranial injury CTA Consider CTA if fracture extends to carotid canal Carotid canal fracture only moderately associated with ICA injury Risk similar to other findings not typically associated with ICA injury (e.g., subdural hematoma) Consider CTV if fracture extends to dural venous sinus or jugular bulb Both carotid and dural venous sinus injuries are rare MR Findings T1WI Hemotympanum, hemolabyrinth (low signal acutely, high signal subacutely) ICA injury: Dissection (“fried egg” sign) or occlusion (loss of ICA flow void) T2WI ME & mastoid debris appears hyperintense Look for hypointense line of intact dura over tegmen on coronal images if CSF leak suspected Loss of expected high signal in labyrinth may indicate hemolabyrinth or pneumolabyrinth T1WI C+ Most valuable for suspected subacute intracranial complications (meningitis, abscess) CN7, membranous labyrinth may enhance when involved by fracture MRA Internal carotid artery occlusion or dissection, carotid cavernous fistula MRV Sigmoid sinus or jugular vein thrombosis Imaging Recommendations Best imaging tool Temporal bone CT Protocol advice Bone algorithm MDCT with reconstructed coronal images 3D CT reconstructions helpful for clarifying fracture orientation, ossicular alignment Routine brain CT or MR for intracranial complications Consider CTA/MRA if involves carotid canal, CTV/MRV if involves dural sinus or jugular foramen DIFFERENTIAL DIAGNOSIS Pseudofractures Sclerotic, well-corticated margins, typically bilaterally symmetric P.V(2):8 Sutures/fissures External: Temporoparietal, petrooccipital, sphenopetrosal (angular), occipitomastoid Internal: Petrotympanic, petrosquamosal, tympanosquamous, tympanomastoid Canaliculi Mastoid, inferior tympanic, subarcuate (petromastoid canal), singular canaliculi Aqueducts 1265 Diagnostic Imaging Head and Neck Cochlear, vestibular aqueducts Incus Interposition Procedure Surgical remodeling/realignment of incus to bridge deficient ossicular chain, correct CHL Mimics chronic incus dislocation PATHOLOGY General Features Etiology T-bone fracture requires application of great force, typically high velocity impact MVA most common etiology Longitudinal fractures secondary to lateral impact Transverse fractures secondary to occipital or frontal impact CLINICAL ISSUES Presentation Most common signs/symptoms Physical findings: Periauricular swelling and ecchymosis (Battle sign), EAC hemorrhage, hemotympanum Conductive hearing loss: Initially may reflect hemotympanum ± tympanic membrane injury If persistent, must evaluate for ossicular injury SNHL: Injury to OC, IAC, brainstem, or PLF If fracture absent, may reflect labyrinthine concussion Intralabyrinthine hemorrhage may ultimately lead to labyrinthitis ossificans Facial nerve dysfunction: CN7 injuries represent spectrum from stretching/crushing/compression to complete transection Delayed paresis often reflects reversible injury; typically managed conservatively Immediate, complete paralysis: Poor prognosis for recovery; may be managed surgically CSF leak: Most resolve spontaneously within days Surgery for persistent leak 10% or less develop meningitis Vertigo: Common after even minor head trauma When severe/persistent, may reflect brain stem injury, labyrinthine concussion, benign paroxysmal positional vertigo, Ménière syndrome (endolymphatic hydrops), PLF Perilymphatic fistula: Symptoms often vague and include dizziness, vertigo, imbalance, fluctuating SNHL Early detection facilitates surgical repair, hearing preservation Chronic presentations Acquired cephalocele Acquired cholesteatoma Squamous invasion of fracture site EAC stenosis Other signs/symptoms Intracranial pathology on CT in up to 85% Extracerebral (epidural, subdural, subarachnoid) or intracerebral (contusion, diffuse axonal injury) CN6 injury Trismus if glenoid fossa is involved Demographics Age All ages CN7 paralysis less common in pediatric T-bone fractures Gender M>F Epidemiology Most common fractures of skull base 20% patients with skull fracture have T-bone fractures Incidence is increasing, likely reflecting increasing traffic and population Natural History & Prognosis Primarily related to intracranial complications Treatment Management of severe head injury is priority Anticoagulation ± endovascular therapy for carotid injury Antibiotics if CSF leak is demonstrated 1266 Diagnostic Imaging Head and Neck Management of CN7 injuries remains controversial; most advocate observation ± steroids for paresis Surgical decompression or CN7 repair may be performed in patients with immediate paralysis DIAGNOSTIC CHECKLIST Consider Systematically assess most clinically relevant structures: CN7 canal, otic capsule, tegmen, carotid canal, ossicles Do not forget to evaluate intracranial contents! Image Interpretation Pearls Check contralateral side to exclude pseudofracture Reporting Tips Classify fractures with regard to both anatomic (longitudinal/transverse/oblique) and otic capsule violating/sparing criteria SELECTED REFERENCES Nash JJ et al: Management and outcomes of facial paralysis from intratemporal blunt trauma: a systematic review Laryngoscope 120(7):1397-404, 2010 Johnson F et al: Temporal bone fracture: evaluation and management in the modern era Otolaryngol Clin North Am 41(3):597-618, x, 2008 Little SC et al: Radiographic classification of temporal bone fractures: clinical predictability using a new system Arch Otolaryngol Head Neck Surg 132(12):1300-4, 2006 Rafferty MA et al: A comparison of temporal bone fracture classification systems Clin Otolaryngol 31(4):287-91, 2006 P.V(2):9 Image Gallery (Left) Axial bone CT shows an unusual longitudinal OC-violating fracture with medial subluxation of the malleus head The fracture extends to the oval window with pneumolabyrinth ; these findings may indicate the presence of perilymph fistula There is medial extension to the IAC (Right) Axial bone CT reveals a chronic fracture with medial extension to the fundus of the IAC The CN7 canal is involved in the mid-tympanic segment , and the incudomalleolar joint is grossly widened 1267 Diagnostic Imaging Head and Neck (Left) Axial bone CT demonstrates a transverse fracture that extends to the jugular bulb and round window niche Stapediovestibular joint disruption is suggested by the alignment of the anterior stapedial crus with the posterior margin of the oval window (Right) Coronal bone CT shows a lucency at the junction of the long and lenticular processes of the incus Persistent CHL should prompt a careful search for ossicular injury; this subtle fracture was confirmed at surgery (Left) Coronal bone CT demonstrates a large traumatic defect of the tegmen tympani with herniation of soft tissue into the epitympanum, representing a small acquired cephalocele The most common complication of a tegmen fracture is transient CSF otorrhea (Right) Axial bone CT shows a chronic fracture line extending through the otic capsule to the basal turn of the cochlea , where abnormal high density indicates the presence of labyrinthitis ossificans Skull Base Trauma > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Skull Base > Skull Base Trauma Skull Base Trauma Kristine M Mosier, DMD, PhD Key Facts Terminology Traumatic injury of bony anterior, middle, or posterior cranial fossa Imaging Noncorticated, noninterdigitating lucency + pneumocephalus or intraorbital emphysema Location 1268 Diagnostic Imaging Head and Neck Anterior fossa: Frontal bone-sinus, cribriform plate Middle fossa: Greater sphenoid wing, sphenoid sinus, clivus Posterior fossa: Petrous temporal bone, occiput Protocol advice Bone CT: Skull + facial bones + cervical spine NECT: Brain + neck soft tissues CTA or MRA: Suspected neurovascular injury MR brain: Suspected cerebral injury Top Differential Diagnoses “Pseudofractures” Sutures and fissures Canals and foramina Emissary veins and venous sinuses Pathology Associated abnormalities Intracranial contusion, hematoma Pneumocephalus Neurovascular injury CSF fistula/leak Cranial nerve deficits Clinical Issues Results from high-velocity impact: MVA, gunshot/missile Management triaged according to degree/severity of intracranial injury (Left) Axial bone CT shows a type I/II frontobasal fracture with a fracture line extending through the superomedial orbit just lateral to the frontal sinus There is significant associated pneumocephalus (Right) Axial bone CT in the same patient shows an additional fracture through the posterior wall of the right frontal sinus This fracture, in addition to other small fractures in the cribriform plate (not shown), accounts for the source of pneumocephalus 1269 Diagnostic Imaging Head and Neck (Left) Coronal bone CT shows a type III frontobasal fracture with a large fracture extending through the left frontal bone to the NOE complex The fracture traverses the left frontal sinus and terminates in the region of the left lacrimal sac (Right) Axial bone CT in the same patient shows additional MCF fractures through the left GWS and the lateral wall of the right sphenoid sinus Fractures of the MCF often involve vascular canals or neural foramina P.V(2):11 TERMINOLOGY Definitions Traumatic injury of anterior, middle, or posterior skull base IMAGING General Features Best diagnostic clue Noncorticated, noninterdigitating lucency in skull base bone ± pneumocephalus or intraorbital emphysema Location Anterior cranial fossa (ACF): Frontobasal Frontal bone, ethmoid bone, & anterior sphenoid bone Includes frontal sinus, medial 1/3 superior orbital rim, nasoethmoid, cribriform plate, and planum sphenoidale Middle cranial fossa (MCF): Greater wing of sphenoid bone (GWS), sphenoid sinus, clivus Includes cavernous sinus, horizontal and vertical petrous carotid canals Posterior cranial fossa (PCF): Petrous temporal bone & occiput See: Temporal bone trauma Size Fractures involving cribriform plate, fovea ethmoidalis, carotid canal may be subtle Morphology Linear Longitudinal, transverse, or oblique May be vertical or horizontal Frontobasal longitudinal fractures run parallel to cribriform plate Frontobasal transverse or oblique fractures usually type II or III MCF fractures typically transverse or oblique Comminuted Often associated skull or midface fractures Usually type II or III frontobasal Imaging Recommendations Best imaging tool Thin slice axial bone CT with multiplanar reconstruction Protocol advice 1270 Diagnostic Imaging Head and Neck Bone CT: Head + facial bones Multidetector CT (MDCT) higher accuracy for detection of fracture Thin section axial acquisition with mm coronal and sagittal reformats 3D volumetric reconstruction for assessment of deformity, fracture orientation, & reconstruction planning NECT: Head + facial bones Assess associated intracranial injury Assess soft tissue injury of orbit, face, upper neck CTA or MRA: Suspected carotid/vertebral dissection, thromboembolism, carotid-cavernous fistula (CCF) Fracture involves carotid canal or extends through clivus Enlarged superior ophthalmic vein, significant air in cavernous sinus MR brain: Suspected cerebral parenchymal injury CT Findings NECT Associated intracranial injury Epidural, subdural hematoma, parenchymal contusion, subarachnoid blood, infarct Associated intraorbital soft tissue injury Globe rupture or “tenting”; intraocular hemorrhage Lens dislocation Retrobulbar or subperiosteal hematoma Paranasal sinus hemorrhage or hematoma Bone CT Noncorticated, noninterdigitating lucency May have associated diastasis of sutures Comminution of bone typically mild to moderate Displacement of bone fragments Highly comminuted cribriform or ethmoid fractures usually associated with complex facial fractures Associated pneumocephalus, intraorbital emphysema Air-fluid levels in frontal, ethmoid, sphenoid sinuses CTA Arterial occlusion/dissection Vessel wall irregularity, luminal narrowing, pseudoaneurysm Lack of contrast opacification Segmental high-grade tapered narrowing/“string” sign → dissection 16 slice MDCT: 92% negative predictive value for carotid/vertebral occlusion, dissection Carotid-cavernous fistula Focal bulging, asymmetric distension of involved cavernous sinus Enlargement of ipsilateral superior ophthalmic vein Fistula tract between cavernous carotid and cavernous sinus MR Findings T1/T2/FLAIR/DWI: Hemorrhage, infarction, shear injury Loss of flow void in ICA/vertebral or “fried egg”/“crescent” sign → occlusion or dissection MRA: Carotid/vertebral occlusion or dissection, CCF DIFFERENTIAL DIAGNOSIS Pseudofractures of Skull Base Sutures and fissures Sphenofrontal suture and metopic suture Sphenooccipital synchrondoses Petrooccipital fissure Sphenopetrosal synchondrosis and sphenosquamosal suture Tympanosquamous suture and petrotympanic fissure Occipitomastoid suture Canals and foramina Anterior, posterior ethmoidal artery canal P.V(2):12 Supraorbital artery foramen 1271 Diagnostic Imaging Head and Neck Vidian canal Neurovascular channels from foramen rotundum and ovale Inferior and lateral rotundal canals Accessory meningeal artery canal and foramen of Vesalius Emissary veins and venous sinuses Mastoid, occipital, petrosquamosal, posterior condylar Superior petrosal sinus PATHOLOGY General Features Etiology Frontobasal: Results from frontal bone impact Predominately secondary to motor vehicle accident (MVA) Lower velocity frontal bone → type I Higher velocity lateral or inferior frontal bone/glabella, supraorbital, zygoma → type II/III MCF: High-velocity impact to lateral frontal bone, zygoma, temporal or parietal bone Associated abnormalities Intracranial contusion, hematoma Pneumocephalus CSF fistula/leak ↑ probability with type II or III frontobasal fractures Carotid or vertebrobasilar dissection, thromboembolism Fracture involving sphenoid sinus or carotid canal → ↑ probability of neurovascular injury Dural AV fistula CCF: ↑ incidence of CCF with sphenoid, carotid canal fracture Cranial nerve deficits Frontobasal: CN1, less commonly CN3, 4, MCF: CN 3-6 Horner syndrome Staging, Grading, & Classification Frontobasal fractures Type I Isolated linear fracture Occurs in frontal bones or sinus, medial 1/3 supraorbital rim, naso-orbital ethmoid (NOE), cribriform plate, or planum sphenoidale May extend through pituitary fossa and separate ACF and MCF from PCF Type II Vertical linear fracture involving skull vault (frontal bone) + base Involves lateral 2/3 of supraorbital rim, squamous temporal bone + orbital roof, lateral wall, or apex Type III Combined fracture Involves comminution of frontal and lateral skull vault + orbital roof MCF: No specific classification CLINICAL ISSUES Presentation Most common signs/symptoms Frontal or temporal scalp laceration, hematoma Periorbital hematoma (“raccoon eyes”) Proptosis, other orbital injuries Altered mental status, loss of consciousness, & neurological deficit Other signs/symptoms Nausea, vomiting, seizure, drowsiness Demographics Age All ages Less common in pediatric populations Gender M>F Epidemiology 1272 Diagnostic Imaging Head and Neck High-velocity impact predominately MVA, gunshot/missile Lower velocity blunt trauma more often following falls, assault/nonaccidental trauma Natural History & Prognosis Type II and III frontobasal Higher risk for intracranial injuries Higher risk for CSF leak MCF fractures Higher risk for intracranial injuries Higher risk for neurovascular injuries Higher risk for cranial nerve deficits Treatment Management triaged according to degree/severity of intracranial injury Endovascular treatment for neurovascular injury Antibiotic coverage for meningitis/CSF leak Management of orbital injuries CSF leak repair SELECTED REFERENCES Maillard AA et al: Trauma to the intracranial internal carotid artery J Trauma 68(3):545-7, 2010 Ringl H et al: The skull unfolded: a cranial CT visualization algorithm for fast and easy detection of skull fractures Radiology 255(2):553-62, 2010 Manson PN et al: Frontobasal fractures: anatomical classification and clinical significance Plast Reconstr Surg 124(6):2096-106, 2009 Mithani SK et al: Predictable patterns of intracranial and cervical spine injury in craniomaxillofacial trauma: analysis of 4786 patients Plast Reconstr Surg 123(4):1293-301, 2009 Feiz-Erfan I et al: Incidence and pattern of direct blunt neurovascular injury associated with trauma to the skull base J Neurosurg 107(2):364-9, 2007 Madhusudan G et al: Nomenclature of frontobasal trauma: a new clinicoradiographic classification Plast Reconstr Surg 117(7):2382-8, 2006 P.V(2):13 Image Gallery (Left) Axial NECT shows displaced fracture through posterior rim of right lesser wing of sphenoid bone with orbital emphysema & a subperiosteal hematoma Note that slight rotation of the sphenoid wing fracture fragment impinges on the superior orbital fissure (Right) Sagittal bone CT in a patient following an MVA shows multiple comminuted sphenoid and clival fractures The posterior clivus is intact , reducing the probability of vertebral artery injury 1273 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a comminuted fracture through the lateral wall of the right sphenoid sinus and carotid canal Note the “double wall” in the carotid canal Additional small fractures are seen in the right squamous temporal bone , and there are air-fluid levels in the maxillary sinuses (Right) Sagittal CTA in the same patient shows a pseudoaneurysm in the cavernous (C4) segment of the internal carotid artery adjacent to the sphenoid fracture fragments (Left) Axial bone CT in a patient following high-speed MVA shows multiple temporal, petrous temporal bone and sphenoid fractures Both carotid canals are fractured , increasing the probability of carotid injury (Right) Axial CTA from the same patient shows a traumatic carotid-cavernous fistula (CCF) in the left cavernous carotid The superior ophthalmic vein was also enlarged (not shown) The CCF was confirmed on digital subtraction angiography Introduction and Overview Orbital Foreign Body > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Facial Bones > Orbital Foreign Body Orbital Foreign Body Michelle A Michel, MD Key Facts Terminology Foreign body (FB) Imaging 1274 Diagnostic Imaging Head and Neck CT demonstrates most FB and is safe in evaluation for metallic FB If initial CT negative, consider MR if possibility of wooden FB Presence of metallic FB is contraindication to MR! CT findings Bright streaks may be seen from metallic beam-hardening artifact Wood FB appears as air density with geographic margin Density of glass subtypes is variable MR findings Inflammatory response around organic FB shows ↑ T2 signal & enhancement Top Differential Diagnoses Surgically implanted device Drusen Phthisis bulbi Arcus senilis Trochlear apparatus calcification Pathology Most FB occur after high-velocity injury Clinical Issues Organic FB more likely to incite cellulitis & abscess Decisions regarding surgical removal depend on type & location of FB Diagnostic Checklist Look for fractures, optic nerve, or globe injury in path of introduced object (Left) Axial NECT in a patient who sustained a shotgun injury to the face shows shrapnel in the sclera posteriorly The globe was ruptured and there is intraocular hemorrhage Additional FB artifact is noted on the left (Right) Axial bone CT in a patient who had been using a nail gun demonstrates a foreign body (nail) within the extraconal fat of the right orbit Fortunately the patient's globe was not ruptured in this case 1275 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a piece of a broken pencil within the right orbit The center dense core represents the pencil “lead” and the outer casing of wood is low density (Right) Axial T1WI C+ FS MR shows a retained orbital foreign body, which was unrecognized at the time of original injury, and presented with a foreign body granuloma The granuloma shows increased T1 signal and is medial to the optic nerve Determined to be organic plant material from hiking injury years prior P.V(2):15 TERMINOLOGY Abbreviations Foreign body (FB) Definitions Metallic or nonmetallic foreign material introduced into orbit via trauma IMAGING General Features Size Larger FB easier to detect CT detects > 90% glass FB ≥ 1.5 mm in size; < 50% ≤ 0.5 mm Imaging Recommendations Best imaging tool CT demonstrates most FB and is safe in presence of metallic FB If initial CT negative, consider MR if possibility of wooden FB CT Findings NECT Bright streaks may be seen from metallic beam-hardening artifact Wood FB appears as air density with geographic margin Dry wood (-656 HU); fresh wood (-24 HU) Wood FB more easily detected if associated with metallic paint or granuloma Density of glass subtypes is variable High-density glass (green beer bottle) easiest to detect MR Findings STIR Inflammatory response around organic FB shows ↑ signal T1WI C+ FS Enhancement of inflammatory tissue around organic FB DIFFERENTIAL DIAGNOSIS Orbital Surgical Device Scleral band, ocular prosthesis or screws, plates, & mesh Drusen Calcifications at optic disc Phthisis Bulbi 1276 Diagnostic Imaging Head and Neck Destroyed calcified globe Arcus Senilis Calcification at margin of cornea Cholesterol deposits or hyalinosis of corneal stroma Trochlear Apparatus Calcification Curvilinear Ca++ in superior nasal quadrant of orbit associated with superior oblique muscle PATHOLOGY General Features Etiology Most FB occur after high-velocity injury (gunshot or industrial accident) Associated abnormalities Orbital fractures & globe injury anticipated in path of introduced object Staging, Grading, & Classification Metallic, inorganic (steel, lead, iron, etc.) Nonmetallic, inorganic (glass, plastic, fiberglass, concrete) Nonmetallic, organic (wood, sandpaper, etc.) CLINICAL ISSUES Presentation Most common signs/symptoms Sharp, stabbing pain at time of injury Pain on eye movement ↓ visual acuity Demographics Age Most patients young (< 30 years) Epidemiology Penetrating injury is component of 50% of trauma to eye Intraocular FB present in 18-41% of open globe injuries Natural History & Prognosis Organic FB (wood) more likely to incite cellulitis & abscess compared to metallic FB Treatment Inorganic FB (especially metal) may be treated conservatively due to morbidity associated with attempted removal Decision regarding surgical removal depends on type & location of FB DIAGNOSTIC CHECKLIST Image Interpretation Pearls CT is sensitive for FB detection and should be performed first Presence of metallic FB within orbit is contraindication to MR! Reporting Tips Be sure to assess for globe rupture & optic nerve injury! SELECTED REFERENCES Kubal WS: Imaging of orbital trauma Radiographics 28(6):1729-39, 2008 Saeed A et al: Plain X-ray and computed tomography of the orbit in cases and suspected cases of intraocular foreign body Eye (Lond) 22(11):1373-7, 2008 Adesanya OO et al: Intraorbital wooden foreign body (IOFB): mimicking air on CT Emerg Radiol 14(1):45-9, 2007 Orbital Blowout Fracture > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Facial Bones > Orbital Blowout Fracture Orbital Blowout Fracture Deborah R Shatzkes, MD Key Facts Terminology Traumatic deformity of orbital floor or medial wall resulting from impact of blunt object larger than orbital aperture Imaging High-resolution axial bone CT with coronal & sagittal reconstructions is modality of choice broad categories of blowout fractures Open door: Large, displaced, frequently comminuted 1277 Diagnostic Imaging Head and Neck Trapdoor: Linear, hinged, minimally displaced Associated findings Herniation of orbital contents through bony defect Involvement of infraorbital canal Orbital soft tissue injury May occur in combination with other facial fractures (nasal, transfacial, ZMC) Top Differential Diagnoses Dehiscent lamina papyracea Orbital decompression surgery Naso-orbital-ethmoidal fracture Clinical Issues Most common symptoms Diplopia: Typically related to entrapment Enophthalmos: Due to prolapse of orbital contents into sinuses Hypesthesia of cheek and upper gum: Due to infraorbital nerve injury Diagnostic Checklist Entrapment is clinical, not radiographic, diagnosis Note abnormal position & morphology of EOMs In children, minimally displaced but highly symptomatic trapdoor fractures are common (Left) Coronal bone CT demonstrates a mildly depressed left orbital floor OBF just medial to the infraorbital canal The inferior rectus muscle is grossly normal in position and configuration (Right) Coronal NECT reveals a chronic right orbital floor OBF with herniation of a small volume of fat and a portion of the inferior rectus muscle through the fracture defect The muscle also demonstrates an abnormal vertical orientation 1278 Diagnostic Imaging Head and Neck (Left) Coronal bone CT reveals a comminuted OBF that involves both the medial wall and floor of the right orbit The right medial rectus muscle is in normal position, though in close proximity to a fracture fragment The optic nerve is outlined by emphysema (Right) Axial NECT shows a small right medial orbital OBF The irregular contour, heterogeneous internal density, dislocated lens , and periocular hematoma are all indicative of globe rupture P.V(2):17 TERMINOLOGY Abbreviations Orbital blowout fracture (OBF) Definitions Orbital floor or medial wall fracture resulting from impact of blunt object of diameter greater than orbital aperture Pure: Without orbital rim fracture Impure: With orbital rim fracture IMAGING General Features Best diagnostic clue Deformity of orbital floor/medial wall with or without herniation of orbital contents through bony defect Location Floor fractures: Middle 1/3, near infraorbital canal Conflicting data exist regarding relative frequency of floor vs medial wall fractures Morphology Open-door: Large, displaced, frequently comminuted Trapdoor: Linear, hinged, minimally displaced High frequency of extraocular muscle (EOM) entrapment despite scant external signs of trauma May be difficult to diagnose radiographically because of minimal displacement Most pediatric blowout fractures are trapdoor type CT Findings Bone CT Simple or comminuted fracture of orbital floor/medial wall, with or without Herniation of orbital contents (fat, EOMs) Fracture through infraorbital canal Injury to orbital soft tissues (globe rupture, retrobulbar hematoma) Significant orbital emphysema more common in medial wall fractures May occur in combination with other facial fractures, e.g., nasal, transfacial (LeFort), zygomaticomaxillary complex (ZMC) Imaging Recommendations Best imaging tool Thin slice bone algorithm MDCT in axial plane with coronal, sagittal reconstructions Protocol advice Include soft tissue algorithm reconstructions to evaluate orbital contents DIFFERENTIAL DIAGNOSIS Dehiscent Lamina Papyracea Medial wall deformity may reflect congenital dehiscence &/or is associated with ethmoid hypoplasia Orbital Decompression Surgery Resection of medial orbital wall performed for thyroid orbitopathy Naso-Orbital-Ethmoidal Fracture Fractures also involve nasal bridge with nasal depression and traumatic telecanthus Zygomaticomaxillary Complex Fracture Fractures also seen in zygomatic arch, lateral orbital wall, maxillary sinus walls CLINICAL ISSUES Presentation Most common signs/symptoms Diplopia Typically secondary to EOM ± fat entrapment May occur without entrapment, secondary to edema/hemorrhage Enophthalmos 1279 Diagnostic Imaging Head and Neck Secondary to prolapse of orbital contents into maxillary (or ethmoid) sinus Hypoglobus (downward eye displacement) may occur, as well Hypesthesia of cheek and upper gum Secondary to fracture through infraorbital canal Other signs/symptoms Visual loss Secondary to globe/optic nerve injury Oculocardiac reflex Natural History & Prognosis Small uncomplicated fractures: No treatment Urgent surgery recommended for nonresolving oculocardiac reflex, “white-eyed” OBF with severe gaze restriction, early enophthalmos Timing otherwise controversial Most advocate surgery within weeks for diplopia, herniation of orbital contents on CT, or large orbital floor fractures (> 50% of floor area) that may result in delayed enophthalmos Treatment Orbital floor reconstruction typically performed with alloplast (titanium mesh, porous polyethylene) DIAGNOSTIC CHECKLIST Consider In children, minimally displaced but highly symptomatic trapdoor fractures are common Image Interpretation Pearls Entrapment is clinical, not radiographic, diagnosis Reporting Tips Assess position, orientation and configuration of EOMs, as functional entrapment can occur without significant displacement SELECTED REFERENCES Gosau M et al: Retrospective analysis of orbital floor fractures-complications, outcome, and review of literature Clin Oral Investig Epub ahead of print, 2010 Yano H et al: A consecutive case review of orbital blowout fractures and recommendations for comprehensive management Plast Reconstr Surg 124(2):602-11, 2009 Trans-facial Fracture (Le Fort) > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Facial Bones > Trans-facial Fracture (Le Fort) Trans-facial Fracture (Le Fort) Kristine M Mosier, DMD, PhD Key Facts Terminology Fractures disrupting pterygomaxillary junction, pterygoid processes/plates, & disjoining portions of face (maxilla) from skull LF type I: Guerin fracture; “floating palate” LF type II: Pyramidal fracture, separates midface from skull LF type III: Craniofacial disassociation Imaging Best diagnostic clue: Pterygoid process & pterygoid plate fxs in patient with clinically mobile facial skeleton Best imaging tool: Thin section (≤ mm) bone CT 3D reconstructions greatly facilitate fx analysis & assist in surgical planning Le Fort I: Pterygomaxillary disjunction + fx of inferior medial and lateral maxillary buttress Le Fort II: Pterygomaxillary disjunction + superior medial maxillary buttress + inferior lateral maxillary buttress Le Fort III: Pterygomaxillary disjunction + zygomatic arch + superior lateral & medial maxillary buttress Top Differential Diagnoses Zygomaticomaxillary complex fracture Naso-orbital-ethmoidal fracture Complex facial fracture Pterygoid plate avulsion Pathology Blunt facial trauma, fracturing along lines of weakness in facial skeleton Most cases due to motor vehicle accidents, assaults, or falls 1280 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows lines defining the types of Le Fort fractures Le Fort I (green) involves the nasal aperture, Le Fort II (red) traverses the inferior orbital rim, and Le Fort III (black) extends through the zygomatic arches (Right) Lateral 3D CT reformation shows a horizontal Le Fort I fx separating the maxillary alveolus from the midface Note the involvement of the nasal aperture , but intact inferior orbital rim and zygomatic arch (Left) Lateral 3D CT reformation shows a Le Fort II fx with a fracture through the nasofrontal junction and extending obliquely through the inferior orbital rim There is also an associated Le Fort I fx and a fracture through the subcondylar region of the mandible (Right) Lateral 3D CT reformation of a right Le Fort III fx shows frontonasal diastasis , medial and lateral orbital wall fxs, & pterygoid plate fxs with sparing of inferior orbital rim P.V(2):19 TERMINOLOGY Abbreviations Le Fort (LF) fracture (fx) Definitions Fractures disrupting pterygomaxillary junction, fracturing pterygoid processes/plates, & disjoining portions of face (maxilla) from skull IMAGING General Features Best diagnostic clue Pterygoid process & pterygoid plate fractures in patients with clinically mobile facial skeleton 1281 Diagnostic Imaging Head and Neck Imaging Recommendations Best imaging tool Thin section bone CT Protocol advice Noncontrast axial helical CT (slice thickness ≤ mm) with bone algorithm, coronal, and 3D reconstructions CT Findings Bone CT Le Fort I: Pterygomaxillary disjunction + fracture of inferior medial & lateral maxillary buttress Fx involving pyriform rim + medial & lateral walls maxillary sinus/alveolus + pterygoid plates + nasal septum Le Fort II: Pterygomaxillary disjunction + superior medial maxillary buttress + inferior lateral maxillary buttress Fx of superior medial maxillary buttress = frontomaxillary suture/nasofrontal junction & inferior orbital rim Fx of inferior lateral maxillary buttress = zygomaticomaxillary suture Le Fort III: Pterygomaxillary disjunction + zygomatic arch + superior lateral & medial maxillary buttress Fx of upper transverse maxillary buttress = zygomatic arch Fx of zygomaticofrontal, zygomaticosphenoid sutures, orbital floor, nasofrontal junction DIFFERENTIAL DIAGNOSIS Zygomaticomaxillary Complex Fracture (ZMC) Associated with blow to malar eminence Spares pterygoid process/plates Involves zygomaticofrontal, zygomaticomaxillary, zygomaticosphenoid, & zygomaticotemporal sutures Naso-Orbital-Ethmoidal Fracture (NOE) Associated with focal blow over nasal bridge Spare pterygoid processes/plates Depression of nasal pyramid ± telecanthus due to displacement of medial canthal ligament Complex Facial Fracture Highly comminuted midface fx In “pure form” spares pterygoid processes/plates but frequently coexists with LF fxs Pterygoid Plate Avulsion Associated with violent trauma to mandible Lateral pterygoid plate typically involved, pterygoid process usually spared PATHOLOGY General Features Etiology Most cases due to trauma from motor vehicle accidents, assaults, or falls CLINICAL ISSUES Presentation Most common signs/symptoms “Mobile face” (maxillary alveolus & hard palate, midface, or entire face) Midface depression (retrusion), also called “dish face” deformity Demographics Epidemiology Le Fort and maxillary fractures account for approximately 25.5% of facial fractures Le Fort II fracture is most common type Le Fort III fx least common type (in isolated form) Natural History & Prognosis Long-term complications may include Facial deformity, breathing difficulty, & masticatory problems/malocclusion Telecanthus, visual loss, diplopia, & epiphora Treatment Surgical reduction & fixation of facial fractures starts with frontal bar (thickened frontal bone above frontonasal sutures & superior orbital rims) Other facial bones are “suspended” from frontal bar by open reduction/internal fixation with titanium plates & screws, fixing fxs in top-to-bottom fashion DIAGNOSTIC CHECKLIST Consider 1282 Diagnostic Imaging Head and Neck Le Fort fracture in setting of high-impact injury to face with pterygoid process/plate fractures SELECTED REFERENCES Hopper RA et al: Diagnosis of midface fractures with CT: what the surgeon needs to know Radiographics 26(3):783-93, 2006 Rhea JT et al: How to simplify the CT diagnosis of Le Fort fractures AJR Am J Roentgenol 184(5):1700-5, 2005 Linnau KF et al: Imaging of high-energy midfacial trauma: what the surgeon needs to know Eur J Radiol 48(1):1732, 2003 P.V(2):20 Image Gallery (Left) Oblique 3D CT reformation shows a right Le Fort I fracture mobilizing the right hemimaxilla, which is rotated inferiorly In addition, there are multiple nasal bone fxs and comminuted left maxillary fxs (Right) Sagittal CT reconstruction shows the utility of sagittal reformats for demonstrating the maxillary disjunction of a Le Fort I with fx extending from the lateral aspect of the nasal aperture through the pterygoid plate (Left) Anteroposterior 3D CT reformation shows a left Le Fort II fx extending from the nasal bones through the ethmoid complex and antero-inferiorly to the orbital rim Note the associated bilateral Le Fort I fxs and bone plates from an old zygomaticomaxillary fx (Right) Lateral 3D CT reformation shows a Le Fort II fx involving the nasal bones , inferior orbital rim , and pterygoid plates There is an associated Le Fort I fx Rotation of the zygoma displaces the TMJ 1283 Diagnostic Imaging Head and Neck (Left) Oblique 3D CT reformation of an impure right Le Fort III fx shows the craniofacial disjunction as a depressed nasal fx , zygoma fxs , and depressed zygomatic arch fx Note the accompanying comminuted orbital and maxillary smash fxs (Right) Axial bone CT of a right Le Fort III shows bilateral nasal bone fractures and a right zygomatic arch fracture A combination of a nasoethmoid and zygoma fractures should prompt search for a Le Fort III P.V(2):21 (Left) Sagittal bone CT of combined Le Fort I and II fxs demonstrates the nasofrontal junction fracture of the Le Fort II pattern and the medial maxillary buttress fracture of the Le Fort I (Right) Coronal bone CT shows fractures involving the inferomedial orbital walls extending from the nasofrontal junction There are fxs through the upper transverse maxillary buttress (orbital rim and floors) and inferior medial and lateral maxillary buttresses Le Fort I and II 1284 Diagnostic Imaging Head and Neck (Left) Coronal bone CT illustrates the transverse and vertical buttresses There are fractures through the inferior medial (lower transverse) maxillary buttress as a component of the Le Fort I pattern Note that the vertical medial maxillary buttress is preserved (Right) Coronal bone CT shows fractures through the right lower transverse medial and lateral maxillary buttresses in the Le Fort I pattern The upper transverse and vertical buttresses are intact (Left) Coronal bone CT demonstrates fracture through the nasofrontal junction common to Le Fort II and III patterns This fracture site is at the confluence of the vertical (medial maxillary) & transverse (upper transverse maxillary) buttresses, forming the anterior point of midfacial or craniofacial disjunction (Right) Coronal bone CT shows fracture of the upper transverse buttresses and zygomaticofrontal suture in the Le Fort II and III pattern Note the right Le Fort I fracture Zygomaticomaxillary Complex Fracture > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Facial Bones > Zygomaticomaxillary Complex Fracture Zygomaticomaxillary Complex Fracture Michelle A Michel, MD Key Facts Terminology Fracture complex with fracture lines involving zygomatic arch, lateral orbital wall, anterior & lateral walls of maxillary sinus, & orbital floor Although called “trimalar” or “tripod fracture,” “ZMC fracture” terminology most accurate as this fracture involves orbital floor 1285 Diagnostic Imaging Head and Neck Imaging Fracture lines surround malar eminence Modality of choice: Thin slice axial bone algorithm CT Can be reformatted in coronal plane 3D reformatted images very helpful for demonstrating degree of fracture displacement & angulation for surgical planning Top Differential Diagnoses Complex midfacial fracture Transfacial (LeFort) fractures Zygomatic arch fracture Pathology Most commonly occurs after direct blow to cheek (malar eminence) Classification systems not often used to plan treatment since advent of miniplates & microplates Clinical Issues Teenage to young adult males most commonly affected Signs & symptoms Loss of cheek projection with increased facial width Impaired sensation or anesthesia of cheek/upper lip Excellent prognosis for restored cosmesis after surgical fixation (Left) Axial bone CT shows the typical fracture patterns of a zygomaticomaxillary complex (ZMC) fracture There is a comminuted fracture of the left zygomatic arch and a fracture of the lateral maxillary sinus wall that is buckled The anterior wall fracture is not seen on this image (Right) Axial bone CT through the orbits in the same patient shows a displaced lateral orbital wall fracture The bone fragment protrudes into the extraconal fat near the lateral rectus muscle 1286 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a right ZMC fracture There is premaxillary soft tissue swelling Fractures of the anterior and lateral right maxillary sinus walls are noted, in addition to a right zygomatic arch fracture (Right) 3D reformation demonstrates the classic features of a ZMC fracture Fractures involve the walls of the left maxillary sinus , the left zygomatic arch , and the lateral orbital wall This patient also sustained trauma to the nasal dorsum P.V(2):23 TERMINOLOGY Abbreviations Zygomaticomaxillary complex (ZMC) fracture Synonyms Trimalar fracture; tripod fracture; displaced ZMC fracture = “quadripod” or “quadramalar” fracture ZMC fracture terminology more accurate as this fracture involves orbital floor Definitions Fracture complex with fracture lines involving zygomatic arch, lateral orbital wall, anterior & lateral walls of maxillary sinus, & orbital floor IMAGING General Features Best diagnostic clue Fracture complex with fracture lines involving zygomatic arch, lateral orbital wall, anterior & lateral walls of maxillary sinus, & orbital floor Location Fracture lines surround malar eminence CT Findings Bone CT Lucent fracture line locations Along lateral orbital wall (zygomaticofrontal & zygomaticosphenoid sutures) From inferior orbital fissure to orbital floor (near infraorbital canal) Down anterior maxilla (near zygomaticomaxillary suture) Up posterior maxillary wall to inferior orbital fissure Also fracture through zygomatic arch Imaging Recommendations Best imaging tool Thin slice (0.6-1.0 mm) axial bone algorithm CT DIFFERENTIAL DIAGNOSIS Complex Midfacial Fracture Multiple markedly comminuted fractures not fitting into a classification Bilateral Transfacial (Le Fort) Fractures All Le Fort types involve pterygoid processes 1287 Diagnostic Imaging Head and Neck LeFort III is only type involving zygomatic arch Zygomatic Arch Fracture Isolated zygomatic arch fracture(s) without maxillary wall or lateral orbital wall involvement Decreased projection of lateral cheek (malar eminence) Inferior Orbital (Blowout) Fracture Fractures involve orbital floor ± inferior orbital rim Sparing of zygomatic arch, lateral orbital wall, maxillary sinus walls PATHOLOGY General Features Etiology Most commonly occurs after direct blow to cheek (malar eminence) during assault Paired zygomas each have attachments to cranium & to maxilla creating large portions of orbital floors & lateral orbital walls These complexes are referred to as “ZMCs” Staging, Grading, & Classification Classification systems not often used to plan treatment with use of miniplates & microplates of more complete classification systems based upon type, frequency, & post-reduction stability of malar fractures CLINICAL ISSUES Presentation Most common signs/symptoms Loss of cheek projection with increased facial width Impaired sensation or anesthesia of cheek/upper lip Infraorbital nerve injury in orbital floor (> 90% of cases) Demographics Age Teenage to young adults most common Gender More common in males Epidemiology Zygomatic fractures are 2nd most common facial fractures after nasal bone trauma Natural History & Prognosis Excellent prognosis for restored cosmesis after surgical fixation Surgical results depend somewhat upon degree of comminution, fracture displacement, & angulation Treatment Surgical exposure indicated if angulated or severely comminuted Surgery goals Correct 3-dimensional position of malar prominence Restore orbital volume by correcting alignment of zygoma & sphenoid SELECTED REFERENCES Fraioli RE et al: Facial fractures: beyond Le Fort Otolaryngol Clin North Am 41(1):51-76, vi, 2008 Hopper RA et al: Diagnosis of midface fractures with CT: what the surgeon needs to know Radiographics 26(3):783-93, 2006 Linnau KF et al: Imaging of high-energy midfacial trauma: what the surgeon needs to know Eur J Radiol 48(1):1732, 2003 Complex Facial Fracture > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Facial Bones > Complex Facial Fracture Complex Facial Fracture Michelle A Michel, MD Key Facts Terminology Synonyms: Facial “smash” injury, panfacial fracture No widely accepted definition Severely comminuted fractures involving multiple facial bones Does not follow pattern described for traditional transfacial (Le Fort) fracture Imaging Thin section axial bone CT with multiplanar reconstruction is modality of choice 1288 Diagnostic Imaging Head and Neck 3D CT reformatted images improve appreciation of disrupted facial architecture for surgical planning Fractures may involve frontal, nasoethmoid, midfacial, or craniofacial regions May also involve mandible CTA may be necessary to exclude carotid artery injury MR helpful for assessing associated intracranial & orbital injuries Top Differential Diagnoses Transfacial (Le Fort) fracture Zygomaticomaxillary complex fracture Naso-orbital-ethmoidal fracture Pathology High association with intracranial injuries Clinical Issues Soft tissue injuries & loss of bone structure may lead to malocclusion, “dish” face deformity, & enophthalmos Treatment often delayed because of other life-threatening injuries Reconstruction often performed in multiple stages (Left) Lateral CT scout image in a patient status post high-force blunt facial trauma demonstrates flattening of facial projection involving the nasal dorsum and midface (“dish” face) (Right) Axial bone CT demonstrates significant injuries to the facial soft tissues and underlying facial skeleton Lacerations with soft tissue emphysema are noted Severely comminuted fractures involve the maxillae , orbital walls , and nasal septum The entire face is depressed (Left) Coronal bone CT demonstrates extensive fractures of the midface involving the medial orbital walls , orbital floors , right maxillary alveolus , and left lateral maxillary sinus The fractures not conform to a described fracture pattern (Right) Anteroposterior 3D reformation in a patient after reconstruction of a panfacial injury shows 1289 Diagnostic Imaging Head and Neck numerous malleable screw plates bridging fractures and mesh along the left orbital floor Naso-orbital-ethmoidal Fracture > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Facial Bones > Naso-orbitalethmoidal Fracture Naso-orbital-ethmoidal Fracture Michelle A Michel, MD Key Facts Terminology Central upper midface fracture complex involving confluence of medial & upper maxillary buttresses & their posterior extensions Disruption of medial canthal regions, ethmoids, & medial orbital walls Imaging Bone CT: Nasal bone fx in combination with fxs of medial orbital wall & frontal process of maxilla Top Differential Diagnoses Complex midfacial fracture Nasal bone fracture Medial orbital blowout fracture Pathology Force transmitted through nasal bones & involves ethmoid sinuses & medial orbits May involve frontal recess resulting in impaired frontal sinus drainage May involve cribriform plate → CSF leak, meningoencephalocele, intracranial infection Manson classification Type I: Medial canthal insertion on large fracture fragment Type II: Canthal tendon attached to small bone fragment Type III: Complete avulsion of medial canthal tendon Clinical Issues Symptoms & signs Loss of nasal projection in profile Increased distance between inner corners of eyes (telecanthus) NOE fxs can be one of most difficult facial fracture patterns to accurately repair (Left) Axial bone CT shows markedly comminuted fractures involving the NOE complex Multiple small fracture fragments are noted in the medial canthal regions and there is a degree of telecanthus Soft tissue swelling, emphysema, and a lateral orbital fracture are noted (Right) Axial bone CT in the same patient inferior to the previous image shows that the fractures involve both nasolacrimal ducts In such a patient, epiphora would be an expected complication of the injury 1290 Diagnostic Imaging Head and Neck (Left) Coronal CT reconstruction shows severely comminuted fractures of the NOE region with involvement of the frontal sinus walls Fracture fragments are displaced into the extraconal spaces superiorly , increasing the likelihood of ocular injury (Right) Axial bone CT in the same patient shows dominant medial orbital fracture fragments to which the medial canthal tendons are attached This NOE fx would be a type I according to the Manson classification with the best postsurgical prognosis Mandible Fracture > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Facial Bones > Mandible Fracture Mandible Fracture Michelle A Michel, MD Key Facts Imaging Mandible simulates bony “ring”: breaks common (50%) Parasymphysial fx often associated with contralateral angle/body or subcondylar fx Bilateral subcondylar fractures after direct impact to symphysis CT has largely replaced plain film evaluation of facial trauma Thin slice axial bone algorithm CT with coronal & 3D reformat Bone CT appearance Lucent, noncorticated lines with variable diastasis, angulation, & comminution Fx tends to follow long axis of teeth In condylar neck fracture, condylar head pulled medially by lateral pterygoid muscle “Empty TMJ” sign when TMJ dislocated Top Differential Diagnoses “Pseudofractures” Nutrient canal Inferior alveolar nerve canal Mental foramen Pathology Causes of mandibular fracture Motor vehicle accidents: 40% Assault: 40% Fall: 10% Sports-related injury: 5% 15% have ≥ other facial bone fx Clinical Issues 2nd most commonly fractured facial bone Goals of treatment are restoration of normal occlusion & complete bony union 1291 Diagnostic Imaging Head and Neck (Left) Sagittal graphic shows complex mandibular ramus fracture obliquely crossing posterior margin of mandible Inferior alveolar nerve may be injured in such a fracture resulting in numb chin (Right) Axial bone CT shows displaced mandibular fractures of the right angle and left parasymphysis Two fractures are commonly seen as the mandible is essentially a somewhat fixed “ring” of bone Extensive lacerations were responsible for the associated soft tissue emphysema (Left) Coronal bone CT demonstrates bilateral mandibular condyle fractures with more displacement of fracture fragments on the right than the left Trauma to the right TMJ was significant, and air is noted in the joint (Right) 3D reformation shows an obliquely oriented fracture through the coronoid process of the mandible on the right The ramus, angle, body, and symphysis are intact 3D reformatted images are often helpful for surgical planning of facial fractures P.V(2):27 TERMINOLOGY Abbreviations Fracture (fx) of mandible Definitions Traumatic break in mandibular cortex IMAGING General Features Best diagnostic clue Focal noncorticated lucency in mandibular cortex 1292 Diagnostic Imaging Head and Neck Location Mandible simulates bony ring breaks in “ring” common (50%) & bilateral fx result Parasymphysial fx on side often associated with contralateral angle/body or subcondylar fx Bilateral subcondylar fractures after direct impact to symphysis Alternatively unilateral mandibular fx may occur with contralateral temporomandibular joint (TMJ) dislocation Morphology Linear or branching CT Findings Bone CT Lucent, noncorticated fx lines with variable diastasis, angulation, & comminution Fx lines tend to follow long axis of teeth In condylar neck fracture, condylar head pulled medially by lateral pterygoid muscle “Empty TMJ” sign may be seen on axial CT images when TMJ dislocated MR Findings T1WI ↓ marrow signal intensity from edema May see discrete, well-defined hypointense fracture line Hypointense joint effusion if TMJ affected Hyperintense blood products may also be seen T2WI ↑ marrow signal due to edema Surrounding edema on MR may be more extensive than fracture length Hypointense fracture line Surrounding ↑ signal soft tissue edema Imaging Recommendations Best imaging tool Thin slice axial bone algorithm CT through mandible & TMJs DIFFERENTIAL DIAGNOSIS Nutrient Canal Pseudofracture caused by radiolucent channels extending through osseous structures Commonly mistaken for fracture lines Inferior Alveolar Nerve Canal Usually located inferior & medial within mandible Corticated, exits at mental foramen Mental Foramen Small opening at anterolateral mandible, where mental nerve and vessels emerge Located between & cm from midline mandible; may be duplicated Mandibular Lingula Tongue-shaped bony projection extending from medial mandible to cover mandibular foramen Usually symmetric and triangular in shape PATHOLOGY General Features Etiology Fx causes Motor vehicle accidents: 40% Assault: 40% Fall: 10% Sports-related injury: 5% Associated abnormalities 15% of cases with mandibular fx have ≥ other facial bone fx CLINICAL ISSUES Presentation Most common signs/symptoms Jaw pain Abnormal mobility on palpation Demographics 1293 Diagnostic Imaging Head and Neck Epidemiology Mandible is 2nd most commonly fractured facial bone Account for ≈ 25% of facial fx Mandibular fracture frequencies Condylar process: 30% Angle: 25% Body: 25% Symphyseal/parasymphysial: 15% Ramus: 3% Coronoid process: 2% Treatment Goals of treatment are restoration of normal occlusion & complete bony union DIAGNOSTIC CHECKLIST Consider Mandible is considered “ring of bone” → look for 2nd fx, TMJ dislocation (empty TMJ socket) or facial fx! SELECTED REFERENCES Ellis E 3rd et al: Fractures of the mandible: a technical perspective Plast Reconstr Surg 120(7 Suppl 2):76S-89S, 2007 Schuknecht B et al: Radiologic assessment of maxillofacial, mandibular, and skull base trauma Eur Radiol 15(3):560-8, 2005 TMJ Meniscal Dislocation > Table of Contents > Part V - Skull Base > Section - Skull Base and Facial Trauma > Facial Bones > TMJ Meniscal Dislocation TMJ Meniscal Dislocation Kristine M Mosier, DMD, PhD Key Facts Terminology Internal derangement (ID) of TMJ Abnormal positional and functional relationship between articular disc and articulating surfaces Imaging Best imaging tool: Oblique corrected sagittal PD or T1WI and T2WI MR Articular disc most commonly positioned anterior to mandibular condyle Normal or dysmorphic disc morphology Top Differential Diagnoses Rheumatoid arthritis Synovial chondromatosis Calcium pyrophosphate deposition disease Pigmented villonodular synovitis Clinical Issues Very prevalent: 20-30% of population Majority asymptomatic ID seen in > 80% of symptomatic TMJ patients Symptoms: Trismus, preauricular pain, limited range of motion Most prevalent 20-40 years Symptomatic joints: F:M = 4:1 More common in males if 2° to trauma Treatment Conservative: Bite splint Surgical: Arthrocentesis & discectomy Diagnostic Checklist Report anterior disc displacement ± reduction Report associated effusion or synovitis 1294 Diagnostic Imaging Head and Neck (Left) Sagittal T1WI MR shows the articular disc anteriorly displaced with the posterior band anterior to the condyle, thinned intermediate zone , and dysmorphic anterior band Note the thinning of cortex and flattening of the articular surface of the condyle (Right) Sagittal T1WI MR on opening in the same patient shows the condyle translating to the articular eminence and recapture of the articular disc This case shows anterior disc displacement with reduction (Left) Sagittal T1WI MR shows a dysmorphic articular disc completely dislocated anteriorly with respect to the mandibular condyle Note the flattening and beaking of the anterior aspect of the mandibular condyle (Right) Sagittal T1WI MR on opening in the same patient also shows translation of the mandibular condyle to the articular eminence but with the disc remaining anterior to the condyle This case shows anterior disc displacement without reduction P.V(2):29 TERMINOLOGY Synonyms Internal derangement (ID) of TMJ Definitions Abnormal positional & functional relationship between articular disc & articulating surfaces IMAGING General Features Best diagnostic clue Articular disc positioned anterior to mandibular condyle Location 1295 Diagnostic Imaging Head and Neck Usually intracapsular Unilateral or bilateral Morphology Normal disc shape or dysmorphic Imaging Recommendations Best imaging tool Thin section oblique corrected sagittal & coronal MR in closed and open mouth positions Protocol advice MR sequences should include sagittal PDWI or T1WI + T2WI Cine images provide more accurate functional information MR Findings T1WI Displacement may be anterior, medial, lateral, or combination Posterior band of articular disc anterior to “12 o'clock” position relative to mandibular condyle Anterior displacement = angle > 10° between posterior band and vertical orientation of condyle Posterior disc displacement is rare T2WI May have superior or inferior joint space effusion with ↑ signal ↑ signal if associated marrow edema T1WI C+ Disc nonenhancing Associated acute synovitis will enhance DIFFERENTIAL DIAGNOSIS Rheumatoid Arthritis Proliferating, inflamed synovial tissue (“pannus”) Enhancing, enlarged synovium Moderate to significant osteoarthritis often present also Synovial Chondromatosis Chondrometaplasia of synovial membrane Cartilaginous nodules detach from synovium and calcify These are known as loose bodies Calcium Pyrophosphate Dihydrate Deposition Disease Metabolic disease associated with chondrocalcinosis Uncommon in TMJ Calcified, enhancing intracapsular mass Pigmented Villonodular Synovitis Rare in TMJ Tumefactive proliferation of synovium Locally aggressive Synovial Cyst Rare in TMJ Cyst arising from synovium PATHOLOGY General Features Etiology Multifactorial; arises from dysfunctional remodeling ↓ adaptive capacity of articular surface ± functional overloading Ligamentous laxity May occur secondary to trauma (condylar fracture/dislocation) Gross Pathologic & Surgical Features Hyperemic, deformed articular disc Microscopic Features Connective tissue hyalinization, hyperplasia, and vascular reaction CLINICAL ISSUES Presentation Most common signs/symptoms Majority asymptomatic Trismus Preauricular pain 1296 Diagnostic Imaging Head and Neck Other signs/symptoms Limited range of motion on opening “Clicking” or locking Demographics Age Adults: Most prevalent from 20-40 years Gender Symptomatic: F:M = 4:1 More common in males if 2° to trauma Epidemiology 20-30% of population ID seen in > 80% of symptomatic TMJ patients SELECTED REFERENCES Wang EY et al: Dynamic sagittal half-Fourier acquired single-shot turbo spin-echo MR imaging of the temporomandibular joint: initial experience and comparison with sagittal oblique proton-attenuation images AJNR Am J Neuroradiol 28(6):1126-32, 2007 Rao VM et al: MR imaging of the temporomandibular joint Neuroimaging Clin N Am 14(4):761-75, 2004 Part VI - Temporal Bone and CPA-IAC Section - Introduction and Overview Temporal Bone Overview > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Introduction and Overview > Temporal Bone Overview Temporal Bone Overview Karen L Salzman, MD H Ric Harnsberger, MD Summary Thoughts: Temporal Bone The temporal bone (T-bone) is one of the most complex and intriguing areas of the head & neck Understanding normal anatomy is key to correct T-bone image interpretation Incorporating the otologic findings of a middle ear mass also helps the radiologist to arrive at a correct preoperative diagnosis If the clinical question is conductive hearing loss, an abnormality on the CT is almost always present & should be extensively searched for, especially in children Cholesteatoma is a very common clinical concern in most ENT practices The following questions should be addressed in a patient with a cholesteatoma: 1) Is the tegmen tympani intact?, 2) Is there potential for fistula into the membranous labyrinth?, 3) Is the facial nerve canal adjacent to or eroded by the cholesteatoma?, 4) Is there tissue in the sinus tympani?, and 5) What is the relationship of the mass to the ossicles? Imaging Techniques & Indications CT is the primary imaging tool for evaluating the fine bony detail of the T-bone Current multislice CT scanners allow thin slices (≤ mm) and provide excellent multiplanar reformatted images, which have become the mainstay for diagnosis of T-bone disease Current protocols include direct axial and coronal views as well as a vestibular oblique view (Poschl plane) and a cochlear oblique view (Stenver plane) A window width of 4000 is ideal CT is the imaging study of choice when the clinical question is conductive hearing loss (CHL), external auditory canal atresia, or possible cholesteatoma MR is helpful for evaluation of inner ear pathology, particularly sensorineural hearing loss (SNHL) in an adult The gold standard for imaging patients with SNHL is enhanced thin section (≤ mm) axial & coronal images through the T-bone with fat-saturated, post-contrast images Pre-contrast T1-weighted images are helpful to evaluate for T1-hyperintense lesions, such as hemorrhage or lipoma; the addition of this modality helps prevent the misdiagnosis of these lesions as vestibular schwannoma High-resolution T2 MR images serve as an excellent screening examination for patients with SNHL These thin section (≤ mm) MR sequences (CISS, FIESTA, etc.) in the axial & coronal plane can help identify patients with mass lesions of the internal auditory canal (IAC), particularly a vestibular schwannoma Sagittal oblique planes are excellent for evaluation of a child with SNHL to easily identify the four nerves within the IAC When the clinical question is SNHL, inner ear malformation, petrous apex lesion, or possible IAC or cerebellopontine angle (CPA) lesion, MR is the imaging study of choice Embryology 1297 Diagnostic Imaging Head and Neck The otocyst buds from the neuroectoderm, migrates to the location of the inner ear, and becomes the membranous labyrinth The external auditory canal (EAC) forms from the 1st branchial groove or cleft The middle ear (tympanic) cavity forms from the 1st branchial (pharyngeal) pouch The tympanic membrane (TM) forms where the EAC (1st branchial cleft) and middle ear (1st branchial pouch) meet The middle ear cavity & the eustachian tube form from the same 1st branchial pouch The middle ear cavity envelops the ossicles The ossicles form from the 1st & 2nd brachial arches, separately from the inner ear The endolymphatic system forms from the otocyst The perilymphatic space and the otic capsule forms from surrounding mesenchyme In EAC atresia, the inner ear is spared since it forms from migration of the otocyst, which is independent from the 1st & 2nd branchial groove-pouch-arch interaction Therefore, inner ear anomalies in most cases form without EAC or middle ear anomalies Consider the following imaging questions when evaluating a patient with EAC atresia: 1) Is the EAC plug bony or membranous?, 2) How small is the middle ear cavity?, 3) What is the status of the ossicles?, 4) Is the facial nerve in the normal position?, 5) What is the status of the oval & round windows? 6) Is there a congenital cholesteatoma?, and 7) What is the appearance of the inner ear structures? Imaging Anatomy The T-bone is located in the middle cranial fossa posterolateral floor Its boundaries include the sphenoid bone anteriorly, the occipital bone posteriorly & medially, and the parietal bone superiorly and laterally There are five bony parts of the adult T-bone: Squamous, mastoid, petrous, tympanic, and styloid portions The squamous portion forms the lateral wall of the middle cranial fossa The mastoid portion represents the postnatal development of the posteroinferior mastoid The petrous portion of the T-bone contains the middle & inner ear, IAC, & petrous apex The tympanic segment is a U-shaped bone that forms most of the bony external ear The styloid portion forms the styloid process after birth The petrous portion of the T-bone includes two important structures anteriorly The tegmen tympani (Latin for “roof of the cavity”) serves as the roof of the tympanic cavity The arcuate eminence is the bony prominence over the superior semicircular canal and an important surgical landmark along the middle cranial fossa floor There are five major anatomic components of the T-bone: External auditory canal (EAC), middle ear-mastoid (ME-M), inner ear, petrous apex, and facial nerve These anatomic components help define the various differential diagnosis lists of the temporal bone The EAC is made up of tympanic bone medially and fibrocartilage laterally The medial border of the EAC is formed by the tympanic membrane (TM), which attaches to the scutum superiorly and the tympanic annulus inferiorly The nodal drainage of the EAC and the adjacent scalp is to parotid lymph nodes The middle ear includes the epitympanum, mesotympanum, & hypotympanum The epitympanum (attic) is defined superiorly by the tegmen tympani, which forms the roof The inferior margin is defined by a line between the scutum and the tympanic segment of the facial nerve The tegmen tympani is the thin bony roof between the epitympanum & the middle cranial fossa dura Prussak space represents the lateral epitympanic recess and is a classic location for acquired (pars flaccida) cholesteatoma The malleus head & body and the short process of the incus are present within the epitympanum P.VI(1):3 The mesotympanum is the middle ear area between the epitympanum above and the hypotympanum below It is defined superiorly by a line between the scutum and the tympanic segment of facial nerve and inferiorly by a line between the tympanic annulus and the base of the cochlear promontory The remainder of the ossicles (manubrium of the malleus, long process of the incus and the stapes) are located in the mesotympanum The two muscles of the middle ear, tensor tympani and stapedius muscle, are also in the mesotympanum and function to dampen sound The posterior wall of the mesotympanum has three important structures: Facial nerve recess, pyramidal eminence, and the sinus tympani The facial nerve recess contains the mastoid facial nerve and may be dehiscent or have a bony covering The pyramidal eminence contains the belly and tendon of the stapedius muscle The sinus tympani is a clinical blind spot during a standard mastoid surgical approach to the T-bone where cholesteatomas may hide The medial wall contains the lateral semicircular canal, the tympanic segment of the facial nerve, and the oval and round windows The hypotympanum is a shallow trough on the floor of the middle ear cavity The mastoid sinus contains three important anatomic structures The mastoid antrum (Latin for “cave”) is the large, central mastoid air cell The aditus ad antrum (Latin for “entrance to the cave”) connects the epitympanum of the middle ear to the mastoid antrum Körner septum is part of the petrosquamosal suture running posterolaterally through the mastoid air cells This septum functions as an important surgical landmark within the mastoid air cells and also serves as a barrier to the extension of infections from the lateral mastoid air cells to the medial mastoid air cells The mastoid T-bone develops after birth As the mastoid eminence protects the facial nerve, this nerve is relatively unprotected until the eminence is formed This is why the facial nerve is vulnerable to birth trauma 1298 Diagnostic Imaging Head and Neck The inner ear contains the membranous labyrinth, which is housed within the bony labyrinth (otic capsule) The membranous labyrinth is the fluid spaces within the bony labyrinth including the fluid & soft tissues within the vestibule, semicircular canals & cochlea, as well as the endolymphatic duct and sac, and cochlear duct The vestibule is the largest part of the membranous labyrinth, consisting of the utricle and saccule The utricle is the more cephalad portion and the saccule the caudal portion of the vestibule The vestibule is separated laterally from the middle ear by the oval window niche The semicircular canals project off the superior, posterior, and lateral aspects of the vestibule The lateral (or horizontal) semicircular canal is at risk for fistula formation from an epitympanic cholesteatoma as it projects into the epitympanum The endolymphatic duct and sac contain endolymph while the cochlear duct contains perilymph The bony labyrinth (otic capsule) forms the cochlea, vestibule, semicircular canals, and vestibular and cochlear aqueducts The cochlea has approximately two and one-half turns The entire cochlea encircles a central bony axis, the modiolus The modiolus houses the spiral ganglion, the cell bodies of the cochlear nerve The three spiral chambers of the cochlea are the scala tympani (posterior chamber), scala vestibuli (anterior chamber), & the scala media (contains organ of Corti = hearing apparatus) The semicircular canals (SCC) project off the superior, lateral, & posterior aspects of the vestibule The superior SCC projects cephalad The bony ridge over the superior SCC in the roof of the petrous pyramid is called the arcuate eminence, an important surgical landmark The lateral (or horizontal) SCC projects into the middle ear The tympanic segment of the facial nerve is on the undersurface of the lateral SCC The posterior SCC projects posteriorly along the petrous ridge The crus communis is the common origin of all three SCCs The petrous apex is anteromedial to the inner ear and lateral to the petro-occipital fissure It is normally pneumatized in approximately 33% of people The abducens nerve (CN6) passes on the medial surface of the petrous apex and through Dorello canal The trigeminal nerve (CN5) passes through the porus trigeminus into Meckel cave on the cephalad-medial surface of the petrous apex In petrous apicitis, these two nerves are commonly affected The petrous internal carotid artery (ICA) includes the vertical & horizontal segments within the petrous temporal bone The vertical segment rises to the genu beneath the cochlea The horizontal segment projects anteromedially to turn cephalad as the cavernous segment The intratemporal facial nerve (CN7) is composed of the IAC, labyrinthine, tympanic, and mastoid segments The IAC segment is located anterosuperiorly within the IAC The labyrinthine segment extends from the IAC fundus to the geniculate ganglion The geniculate ganglion is also known as the anterior genu, and the greater superficial petrosal nerve originates here The tympanic segment leaves the geniculate ganglion and passes under the lateral SCC The posterior genu is the portion where the tympanic segment bends inferiorly to become the mastoid segment The mastoid segment leaves the posterior genu to pass inferiorly to the stylomastoid foramen It first gives off the motor nerve to the stapedius muscle, then the chorda tympani nerve The facial nerve then exits the skull base through the stylomastoid foramen The motor root of CN7 innervates the muscles of facial expression, stapedius, platysma, and the posterior belly of the digastric muscles The sensory-parasympathetic root (nervus intermedius) contains special sensory visceral afferent fibers that convey taste to the anterior 2/3 of the tongue, and the parasympathetic portion provides general visceral efferent secretomotor fibers to lacrimal, submandibular, and sublingual glands CN7 has four major functions that may be used to help localize a lesion along its course Lacrimation is via the greater superficial petrosal nerve The stapedius nerve provides the stapedius reflex, which creates sound dampening Taste to the anterior 2/3 of the tongue is via the chorda tympani nerve to the lingual nerve to the oral tongue The motor branches provides muscles of facial expression The two muscles of the temporal bone, the tensor tympani and stapedius muscles, function to dampen sound When dysfunctional, the patient presents with hyperacusis The tensor tympani is innervated by a branch of the trigeminal nerve (CNV3) It is located in the anteromedial wall of the mesotympanum The tensor tympani muscle tendon goes through cochleariform process and turns laterally to attach on the manubrium P.VI(1):4 of the malleus The stapedius muscle is innervated by the CN7 The stapedius muscle belly is located in the pyramidal eminence The stapedius tendon attaches on the head of the stapes There are three ossicles of the middle ear: Malleus, incus, and stapes The malleus is the most anterior ossicle and is composed of the umbo, manubrium, and head The incus is located posteriorly and is composed of the short process, body, long process, and lenticular process The stapes is located medially and is composed of the hub, crura, and footplate Approaches to Imaging Issues of the Temporal Bone When faced with a T-bone study, use a systematic approach through the five major functional components (EAC, MEM, inner ear, petrous apex, and facial nerve) Be sure to evaluate and report on the location of the ICA, status of the ossicles, location of the CN7 and integrity of the facial nerve canal, presence of the oval window, and integrity of the fissula ante fenestram (anterior margin of the oval window) If a lesion of the temporal bone is found, its location as well as clinical findings help refine the differential diagnosis list 1299 Diagnostic Imaging Head and Neck CHL is caused by a disruption of the conductive chain, which may be due to diseases of the EAC, TM, ossicles, or oval window Typical lesions to consider in a patient with CHL include acquired cholesteatoma, chronic otitis media, EAC atresia, fenestral otosclerosis, and cholesterol granuloma Less common etiologies include oval window atresia, congenital cholesteatoma, ossicular fixation, and medial canal fibrosis SNHL involves lesions of the cochlea, modiolus, or cochlear nerve These lesions may be present in the temporal bone, internal auditory canal, cerebellopontine angle, or brainstem The most common lesion to present with unilateral SNHL is vestibular schwannoma (˜ 90% of lesions) Other much less common etiologies include meningioma, otosclerosis, facial nerve schwannoma, hemangioma, metastases, and labyrinthitis Whenever the T-bone is imaged, the entire facial nerve canal should be visualized and inspected If a lesion of the CN7 is found, it should be precisely localized to one of the CN7 segments: Cisternal segment (brainstem to porus acusticus), IAC (canalicular) segment, labyrinthine segment, tympanic segment, mastoid segment, or parotid segment Some lesions of the temporal bone may result in facial nerve paralysis, including Bell palsy, temporal bone fractures, cholesteatoma, schwannoma, hemangioma, glomus jugulare paraganglioma, meningioma, metastases, middle ear rhabdomyosarcoma, and Langerhans histiocytosis Clinical Implications When a middle ear lesion is present, correlation with otoscopic findings provides critical clues to precise preoperative diagnosis If a ruptured TM is present, a cholesteatoma may be seen through the defect Most retrotympanic lesions have a distinctive hue and location When the ENT surgeon sees a white middle ear lesion behind an intact TM, diagnoses to consider include an congenital cholesteatoma or schwannoma If there is a red hue, the list includes a paraganglioma or aberrant ICA If there is a blue hue, cholesterol granuloma, chronic otitis media with hemorrhage, or a dehiscent jugular bulb should be considered Peripheral facial nerve paralysis is defined as a unilateral facial nerve injury with involvement of the entire face, including the forehead This type of CN7 injury includes loss of the four facial nerve functions: lacrimation (parasympathetic), stapedius reflex (sound dampening), taste to the anterior 2/3 of the tongue, & facial expression Injury to CN7 at any point as it winds through the T-bone results in peripheral facial nerve paralysis P.VI(1):5 Tables Differential Diagnosis: Location External auditory canal EAC atresia Cholesteatoma Squamous cell carcinoma Exostoses (surfer's ear) Osteoma Medial canal fibrosis Keratosis obturans Necrotizing otitis externa Middle ear-mastoid Acquired cholesteatoma Congenital cholesteatoma Cholesterol granuloma Chronic otitis media ± tympanosclerosis Dehiscent jugular bulb Aberrant internal carotid artery Glomus tympanicum paraganglioma Glomus jugulare paraganglioma Meningioma Rhabdomyosarcoma Adenoma Inner ear Superior semicircular canal dehiscence Labyrinthitis & labyrinthine ossificans Large endolymphatic sac anomaly Fenestral & cochlear otosclerosis Intralabyrinthine schwannoma Endolymphatic sac tumor Intralabyrinthine hemorrhage Labyrinthine dysplasias Petrous apex Trapped fluid Cholesterol granuloma Congenital cholesteatoma Cephalocele Apical petrositis Mucocele Intratemporal facial nerve Herpetic facial neuritis (Bell palsy) Facial nerve hemangioma Facial nerve schwannoma Perineural parotid malignancy Image Gallery 1300 Diagnostic Imaging Head and Neck (Top) Coronal magnified graphic of middle ear The middle ear is divided into pieces: Epitympanum, mesotympanum, & hypotympanum The epitympanum is defined as the middle ear cavity above a line drawn from the tip of the scutum to the tympanic segment of CN7 The epitympanic roof is called the tegmen tympani The mesotympanum extends from this line inferiorly to a line connecting the tympanic annulus to the base of the cochlear promontory (Bottom) Sagittal graphic shows the petrous internal carotid artery The cervical ICA enters the carotid canal of skull base to become the vertical petrous ICA (C2 subsegment ICA) It then turns anteromedially to become the horizontal petrous ICA (C2 subsegment ICA) The segment of the intracranial ICA just above the foramen lacerum is called the lacerum segment (C3 ICA segment) Note the inferior tympanic artery rises through the inferior tympanic canaliculus, & middle meningeal artery arises off the internal maxillary artery passing through foramen spinosum P.VI(1):6 1301 Diagnostic Imaging Head and Neck (Top) Axial graphic shows the facial nerve from the brainstem nuclei to the posterior genu in the temporal bone The motor nucleus sends out fibers, which encircle the CN6 nucleus before reaching the root exit zone at the pontomedullary junction Superior salivatory nucleus sends parasympathetic secretomotor fibers to the lacrimal, submandibular, and sublingual glands The solitary tract nucleus receives anterior 2/3 tongue taste information via the chorda tympani nerve to the lingual nerve to the oral tongue (Bottom) Sagittal graphic depicts CN7 within the temporal bone Motor fibers pass through the T-bone, giving off the stapedius nerve to the stapedius muscle, then exit via stylomastoid foramen to the extracranial CN7 (entirely motor) Parasympathetic fibers from the superior salivatory nucleus reach lacrimal gland via greater superficial petrosal nerve and submandibular-sublingual glands via chorda tympanic nerve Anterior 2/3 of tongue taste fibers come via chorda tympani nerve P.VI(1):7 1302 Diagnostic Imaging Head and Neck (Left) Axial T-bone CT through the epitympanum shows the malleus head anterior to the incus short process Prussak space is the lateral epitympanic recess and is a typical location for acquired cholesteatoma Tympanic segment CN7 is well seen (Right) Axial T-bone CT through the mesotympanum shows the posterior wall sinus tympani and pyramidal eminence , which contains the stapedius muscle & mastoid CN7 The most anterior ossicle is the malleus The posterior ossicle is the incus (Left) Axial T-bone CT through the low mesotympanum shows the normal manubrium of malleus and the incudostapedial articulation Basal turn of the cochlea ends at the round window (Right) Coronal T-bone CT through the posterior mastoid region shows the mastoid segment of CN7 , which then exits at the stylomastoid foramen The mastoid tip helps protect this portion of CN7 The jugular foramen and the hypoglossal canal are separated by the jugular tubercle 1303 Diagnostic Imaging Head and Neck (Left) Coronal T-bone CT through semicircular canals demonstrates the long process & the lenticular process of the incus Notice absence of bone evident in the normal oval window niche (Right) Coronal T-bone CT through the anterior middle ear shows the malleus , labyrinthine , & tympanic facial nerve segments Notice the horizontal petrous ICA below the cochlea Section - External Auditory Canal Congenital Lesions Congenital External Ear Dysplasia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - External Auditory Canal > Congenital Lesions > Congenital External Ear Dysplasia Congenital External Ear Dysplasia H Ric Harnsberger, MD Key Facts Terminology CEED: Partial or complete atresia of EAC with associated auricle (external ear) deformity Imaging CT findings depend on severity of CEED dysplasia Auricle & EAC in CEED Mild CEED: Stenotic EAC Severe CEED: No EAC development Mild CEED middle ear findings Thickened, calcified tympanic membrane; middle ear small Moderate CEED middle ear findings Small middle ear cavity Fusion & rotation of malleus & incus Oval window atresia (35%) Mastoid CN7 more anterolateral than normal Severe CEED middle ear findings No aerated middle ear cavity No ossicles seen Bizarre facial nerve canal locations possible Top Differential Diagnoses Acquired EAC stenosis (surfer's ear) EAC osteoma EAC cholesteatoma Tympanosclerosis Clinical Issues 1304 Diagnostic Imaging Head and Neck Conductive hearing loss = most common symptom Severity of microtia ˜ severity of CEED EAC is stenotic or absent Diagnostic Checklist EAC atresia = clinical diagnosis CT provides preoperative roadmap (Left) Coronal graphic of the right ear shows deformed auricle with absent external auditory canal Ossicular fusion mass and rotation with oval window atresia are also present (Right) Coronal bone CT in this congenital external ear dysplasia patient shows the ossicular fusion mass ankylosed to the lateral wall of the middle ear cavity Oval window atresia is present, diagnosed by observing the narrowed oval window niche and thin bone covering the oval window itself (Left) Clinical photograph reveals small, severely malformed auricle with no identifiable external auditory canal Severe microtia will be reflected in severe EAC and middle ear dysplasia on temporal bone CT (Right) Axial bone CT in a patient with severe microtia reveals a normal-appearing inner ear with a very small middle ear cavity and no ossicles The absence of ossicles combined with near absence of the middle ear cavity makes surgical correction extremely difficult P.VI(2):3 TERMINOLOGY Abbreviations Congenital external ear dysplasia (CEED) Synonyms 1305 Diagnostic Imaging Head and Neck External auditory canal atresia Congenital aural atresia or dysplasia Definitions CEED: Variable severity dysplasia of external ear (auricle & EAC) and middle ear Microtia: Small, malformed auricle IMAGING General Features Best diagnostic clue Small or absent EAC associated with microtia Location EAC-middle ear Morphology Dysplastic auricle (microtia) Mildest form CEED has narrowed EAC More severe CEED has no identifiable EAC Hypoplastic middle ear cavity Dysmorphic ossicles, especially malleus & incus CT Findings Bone CT CT findings depend on severity of CEED dysplasia Auricle & EAC in CEED Small, dysmorphic auricle (microtia) Mild CEED: Stenotic EAC Severe CEED: No EAC development Membranous ± bony “atresia plate” No cartilaginous or bony EAC found Middle ear in CEED Mild CEED Thickened, calcified tympanic membrane Slightly small middle ear cavity All ossicles seen with variable fusion to each other & lateral wall middle ear Fusion of malleolar-incudal articulation Mastoid segment CN7 near normal in location Moderate CEED Small middle ear cavity Fusion & rotation of malleus & incus Oval window atresia (35%) Round window atresia (5%) Mastoid CN7 more anterolateral than normal Congenital cholesteatoma associated (2%) Severe CEED No aerated middle ear cavity No ossicles seen Bizarre facial nerve canal locations possible Facial nerve canal findings Aberrant course of tympanic & mastoid portions of facial nerve common Tympanic segment may be dehiscent, overlying oval or round windows Mastoid segment usually anterolaterally displaced May exit skull base into glenoid fossa, or lateral to styloid process Inner ear findings Inner ear & IAC (10%) MR Findings Usually unnecessary Of use only if large congenital cholesteatoma Imaging Recommendations Best imaging tool High-resolution axial & coronal CT best Protocol advice 0.6 mm axials CT with coronal reformations 1306 Diagnostic Imaging Head and Neck Longitudinal oblique reformation: CN7 canal view DIFFERENTIAL DIAGNOSIS Acquired EAC Stenosis (Surfer's Ear) Bilateral acquired lesions Exostosis of EAC, often presenting with history of cold water swimming or other local EAC trauma Auricle normal EAC Osteoma Unilateral, acquired lesion Benign bony growth obliterating EAC EAC Cholesteatoma Unilateral with normal auricle Soft tissue mass protrudes into EAC Underlying bony EAC scalloping May have bone fragments in soft tissue mass Tympanosclerosis EAC normal in size Inflammatory calcifications of tympanic membrane, ossicles, middle ear-mastoid inflammatory tissues Chronic otomastoiditis present PATHOLOGY General Features Etiology Factors causing arrest of EAC-middle ear development unknown Epithelial cells of 1st branchial groove fail to split & canalize, resulting in EAC-middle ear dysplasia Genetics 14% have positive prior family history Infrequently linked to chromosome 18 mutations May be associated with inherited syndromes Crouzon, Goldenhar, or Pierre Robin syndromes Associated abnormalities Inner ear anomaly occurs < 10% Inner ear forms earlier from otocyst Isolated or part of cranial-facial syndrome Embryology-anatomy in CEED 1st & 2nd branchial arches & 1st pharyngeal pouch develop at same time during embryogenesis Associated middle ear anomalies are commonly seen with auricular dysplasia & EAC atresia Branchial groove & 1st pharyngeal pouch give rise to EAC Initially, solid core of epithelial cells In 3rd trimester, cell core canalizes into EAC P.VI(2):4 Failure of canalization leads to EAC stenosis or atresia 1st branchial arch forms malleus head, incus body & short process, & tensor tympani tendon 2nd branchial arch forms manubrium of malleus, long process of incus, stapes (except footplate), & stapedial muscle and tendon Ossicular fusion mass very common in CEED Oval window atresia may be associated with CEED Inner ear forms earlier than EAC Anomalies of labyrinth unusual in CEED Staging, Grading, & Classification Jahrsdoerfer scale and surgical outcomes Score of ≥ points predicts adequate surgical success Scoring system; best possible score = 10 points Stapes present: Oval window open: Middle ear space present: Facial nerve course identified: Malleus-incus complex present: Incus-stapes connection present: 1307 Diagnostic Imaging Head and Neck Mastoid pneumatization present: Round window present: External ear present: Recommendations Operate on unilateral CEED score ≥ Operate on bilateral CEED score ≥ 5-6 Gross Pathologic & Surgical Features Auricle is malformed; may be abnormally positioned Stenosis or absence of EAC Atresia plate membranous or bony Microscopic Features Congenital cholesteatoma may be associated (≤ 2%) CLINICAL ISSUES Presentation Most common signs/symptoms Conductive hearing loss = most common symptom Physical exam Dysplastic auricle Severity of microtia ˜ severity of EAC-middle ear dysplasia EAC is stenotic or absent Demographics Age Present at birth Gender Occurs more commonly in males Epidemiology in 10,000-20,000 live births Unilateral:bilateral cases 4:1 Nonsyndromal EAC atresia usually unilateral Bilateral CEED common when syndromal Natural History & Prognosis Status at birth remains unchanged through life, unless there is associated middle ear cholesteatoma In unilateral atresia, other ear has normal hearing Bilateral atresia: Bilateral conductive hearing loss After surgery, hearing is adequate but not normal Auricle reconstruction may require 4-5 staged surgeries Treatment Unilateral atresia not treated if other ear is normal Cosmetic reconstruction of auricle dysplasia usually occurs in adolescence Course of CN7, status of oval window & inner ear should be established by CT prior to surgery Bilateral atresia is treated at 5-6 years of age, when head has reached 90% of adult size Reconstruction of auricle precedes surgical treatment of middle ear & ossicular deformities Surgical reconstruction ear with mildest EAC atresia Both auricles are repaired for cosmetic reasons Normal morphology & location of stapes important for surgical reconstruction of ossicular function DIAGNOSTIC CHECKLIST Consider EAC atresia = clinical diagnosis CT provides preoperative roadmap CT scoring systems suggest when to operate Severity of auricular dysplasia parallels degree of deformity of middle ear & ossicles Reporting Tips Preoperative CT checklist used for surgical planning Atresia plate: Bony vs membranous; note thickness Report size of middle ear cavity as normal or small Status of ossicular chain: Note presence, morphology, & ankylosis to wall Assess malleoincudal & incudostapedial joints Oval window present? Stapes? If no stapes, ossicular reconstruction difficult 1308 Diagnostic Imaging Head and Neck Trace course of facial nerve, as aberrant nerve may be at risk during surgery Survey for presence of associated cholesteatoma SELECTED REFERENCES El-Begermy MA et al: Congenital auditory meatal atresia: a numerical review Eur Arch Otorhinolaryngol 266(4):501-6, 2009 Kösling S et al: Congenital malformations of the external and middle ear Eur J Radiol 69(2):269-79, 2009 Shonka DC Jr et al: The Jahrsdoerfer grading scale in surgery to repair congenital aural atresia Arch Otolaryngol Head Neck Surg 134(8):873-7, 2008 Yu Z et al: Facial nerve course in congenital aural atresia— identified by preoperative CT scanning and surgical findings Acta Otolaryngol 128(12):1375-80, 2008 Chang SO et al: Long term results of postoperative canal stenosis in congenital aural atresia surgery Acta Otolaryngol Suppl (558):15-21, 2007 Yamane H et al: Disregard of cholesteatoma in congenital aural stenosis Acta Otolaryngol 127(2):221-4, 2007 Klingebiel R et al: Multislice computed tomographic imaging in temporal bone dysplasia Otol Neurotol 23(5):71522, 2002 Calzolari F et al: Clinical and radiological evaluation in children with microtia Br J Audiol 33(5):303-12, 1999 Selesnick S et al: Surgical treatment of acquired external auditory canal atresia Am J Otol 19(2):123-30, 1998 10 Mayer TE et al: High-resolution CT of the temporal bone in dysplasia of the auricle and external auditory canal AJNR Am J Neuroradiol 18(1):53-65, 1997 P.VI(2):5 Image Gallery (Left) Coronal bone CT in a patient with congenital external ear dysplasia through the pyramidal eminence demonstrates the mastoid segment of the facial nerve canal at the same level as the sinus tympani This is anterior to its normal location (Right) Coronal bone CT in a patient with bilateral EAC dysplasia shows the left narrowed EAC canal has channels, aerated , and with a membranous plug Such a “duplicated EAC” is a rare variant seen in EAC atresia 1309 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a patient with severe congenital external ear dysplasia reveals an ectopic tympanic segment of the facial nerve canal arching lateral to the opacified middle ear cavity (Right) Coronal bone CT in the same patient shows complete absence of the EAC associated with bilobed middle ear cavity partially aerated inferiorly with the ossicular fusion mass in the superolateral cavity (Left) Coronal bone CT in a patient with mild microtia reveals the mildest form of CEED as a narrowed EAC , calcified thickened tympanic membrane , and an ossicular mass fused to the upper TM (Right) Axial bone CT in a 2-year-old patient with microtia and absent external auditory canal shows an expansile lesion in the lateral temporal bone At surgery this was found to be an associated congenital cholesteatoma Cholesteatoma is associated in 2% of this patient group Infectious and Inflammatory Lesions Necrotizing External Otitis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - External Auditory Canal > Infectious and Inflammatory Lesions > Necrotizing External Otitis Necrotizing External Otitis H Ric Harnsberger, MD Key Facts Terminology Necrotizing external otitis (NEO) NEO: Severe invasive infection of external auditory canal (EAC), adjacent soft tissues, and skull base 1310 Diagnostic Imaging Head and Neck Imaging Swollen EAC soft tissues with bony erosion (bone CT) & adjacent cellulitis or abscess T2 MR findings T2 diffuse trans-spatial high signal suggests cellulitis T2 focal high signal areas suggest abscess Tissues of EAC & auricle diffusely enhance T1WI C+ MR findings Phlegmon: Heterogeneously enhancing tissue Abscesses: Rim-enhancing fluid collections Nuclear medicine findings Bone and gallium scans often done together If both positive with gallium scan showing larger activity area, high correlation with NEO Top Differential Diagnoses EAC squamous cell carcinoma EAC cholesteatoma Postinflammatory medial canal fibrosis Pathology Diabetic vasculopathy & immune dysfunction Pseudomonas aeruginosa: 98% NEO infections Clinical Issues Severe otalgia and otorrhea Treatment Glucose control, granulation debridement Topical and systemic antibiotic therapy Surgical drainage of any abscess (Left) Axial bone CT shows EAC opacification with focal anterior wall and floor of middle ear erosion in this diabetic patient with painful otorrhea and early necrotizing external otitis (Right) Coronal bone CT in the same patient demonstrates anterior EAC wall bony destruction accompanied by complete opacification of the external auditory canal The middle ear is also opacified In this case, the pseudomonas infection involved both the EAC and the middle ear cavity 1311 Diagnostic Imaging Head and Neck (Left) Axial bone CT reveals EAC opacification associated with multiple areas of erosive bony change The mandibular condyle is also eroded , indicating that the infection has spread to involve the TMJ (Right) Axial T2WI FS MR in the same patient shows abnormal high signal in the masticator , parapharyngeal , & prevertebral spaces secondary to spread of the EAC infection into the subjacent spaces of the suprahyoid neck Sigmoid sinus high signal is from thrombosis P.VI(2):7 TERMINOLOGY Abbreviations Necrotizing external otitis (NEO) Synonyms Malignant external otitis, malignant otitis externa Definitions NEO: Severe invasive infection of external auditory canal (EAC), adjacent soft tissues, and skull base IMAGING General Features Best diagnostic clue Swollen EAC soft tissues with bony erosion & adjacent cellulitis or abscess CT Findings Bone CT Early: Thickened mucosa of EAC & auricle Late: Bony EAC erosive change (especially floor) MR Findings T1WI Muscle signal in EAC & adjacent soft tissues Replacement of normal fatty marrow signal in infected T-bone & skull base T2WI Diffuse trans-spatial high signal suggests cellulitis Focal high signal areas suggest abscess T1WI C+ FS Tissues of EAC & auricle diffusely enhance Heterogeneous enhancement with cellulitis-phlegmon in adjacent soft tissues Abscesses present as rim-enhancing fluid collections Nuclear Medicine Findings General comments Less commonly used compared to a decade ago Less commonly used than CT & MR Bone and gallium scans often done together If both are positive with gallium scan showing larger area of activity, high correlation with NEO diagnosis Imaging Recommendations 1312 Diagnostic Imaging Head and Neck Best imaging tool Bone CT may identify subtle cortical erosions signaling early osteomyelitis MR more sensitive for intracranial complications, bone marrow edema, extent of extracranial soft tissue involvement Follow-up treatment Bone changes persist on CT for up to a year Nuclear medicine studies: Gallium scan correlates most specifically with treatment response Resolution of soft tissue & marrow changes on MR may be better marker of treatment response DIFFERENTIAL DIAGNOSIS EAC Squamous Cell Carcinoma Known auricle SCCa CT-MR: Imaging mimics NEO EAC Cholesteatoma Submucosal EAC mass CT: Unilateral EAC mass with bony erosion (intramural bony “flakes” in 50%) Postinflammatory Medial Canal Fibrosis CT: Fibrous crescent in medial EAC No underlying bony erosion PATHOLOGY General Features Etiology Diabetic vasculopathy & immune dysfunction Pseudomonas aeruginosa: 98% of NEO infections CLINICAL ISSUES Presentation Most common signs/symptoms Severe otalgia and otorrhea Other signs/symptoms CN5-7, CN9-12 cranial neuropathies WBC normal or mildly ↑, ESR invariably ↑ Demographics Age Middle-aged or elderly (> 60 years) Immunocompromised patients (e.g., HIV): Younger, nondiabetic Epidemiology 95% of adults with NEO have diabetes Natural History & Prognosis Begins as soft tissue EAC infection Progresses into surrounding osseous & soft tissue structures May progress to frank skull base osteomyelitis May progress to deep spatial abscess 20% recurrence rate Treatment Glucose control, aggressive granulation debridement Topical and systemic antibiotic therapy Surgical drainage of any deep facial abscess DIAGNOSTIC CHECKLIST Consider EAC SCCa can mimic NEO on imaging Auricle SCCa clinically obvious Image Interpretation Pearls Early cortical erosions best seen with bone CT SELECTED REFERENCES Mani N et al: Cranial nerve involvement in malignant external otitis: implications for clinical outcome Laryngoscope 117(5):907-10, 2007 Grandis JR et al: Necrotizing (malignant) external otitis: prospective comparison of CT and MR imaging in diagnosis and follow-up Radiology 196(2):499-504, 1995 1313 Diagnostic Imaging Head and Neck Keratosis Obturans > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - External Auditory Canal > Infectious and Inflammatory Lesions > Keratosis Obturans Keratosis Obturans H Ric Harnsberger, MD Key Facts Terminology Keratosis obturans (KO) defined as Abnormal accumulation & obstruction of bony EAC from desquamated keratin without erosive bony changes Imaging Temporal bone CT findings Benign-appearing luminal soft tissue lesion partially or completely filling EAC May diffusely enlarge EAC No bony erosive change (cf EAC cholesteatoma) Bilateral (50%) Middle ear spared unless KO neglected Top Differential Diagnoses Benign EAC debris EAC cholesteatoma Necrotizing external otitis EAC squamous cell carcinoma Clinical Issues Clinical presentation Acute severe otalgia Conductive hearing loss (CHL) KO treatment Excision of keratin plug Removal of re-accumulated debris often required Diagnostic Checklist “KO” & “EAC cholesteatoma” terms often confused KO: EAC luminal lesion without bony erosions EAC cholesteatoma: Submucosal lesion with EAC erosions ± bony flecks (50%) Both lesions consist of exfoliated keratin (Left) Axial bone CT in this patient with otoscopic evidence of EAC obstruction shows a soft tissue “plug” in the EAC extending laterally from the tympanic membrane Note absence of underlying bony changes (Right) Axial bone CT in a patient with conductive hearing loss demonstrates a benign-appearing soft tissue lesion in the left EAC extending from the tympanic membrane to the lateral bony EAC margin The middle ear and underlying EAC bone are not involved 1314 Diagnostic Imaging Head and Neck (Left) Axial bone CT of the left ear shows EAC filled with soft tissue This bland-appearing lesion extends from the tympanic membrane laterally into the cartilaginous EAC (Right) Coronal bone CT in the same patient reveals benign-appearing soft tissue within the EAC extending from the tympanic membrane laterally into the cartilaginous EAC There is slight flaring of the lateral bony EAC, but no other bony change is apparent P.VI(2):9 TERMINOLOGY Abbreviations External auditory canal (EAC) keratosis obturans (KO) Synonyms Laminated epithelial plug Definitions KO: Abnormal accumulation & obstruction of bony EAC from desquamated keratin without erosive bony changes IMAGING General Features Best diagnostic clue KO appears as homogeneous soft tissue filling EAC Mild EAC enlargement common Focal bony erosion not present Morphology Soft tissue conforms to EAC CT Findings Bone CT Benign-appearing soft tissue filling EAC May diffusely enlarge EAC No bony erosive change (cf EAC cholesteatoma) Bilateral (50%) Middle ear spared unless KO neglected MR Findings T1WI Homogeneous low-intermediate signal soft tissue filling EAC T2WI Isointense or low signal intensity T1WI C+ May rim enhance Imaging Recommendations Best imaging tool T-bone CT DIFFERENTIAL DIAGNOSIS Benign EAC Debris 1315 Diagnostic Imaging Head and Neck CT: Partially filled EAC; no bony erosion EAC Cholesteatoma CT: Unilateral EAC soft tissue with bony erosion Bony intramural flakes (50%) Necrotizing External Otitis CT: EAC swelling ± bone erosion ± abscess EAC Squamous Cell Carcinoma CT: Irregular mass ± bony erosion PATHOLOGY General Features Etiology common theories Abnormal epithelial migration with keratinaceous debris build-up Sympathetic reflex stimulation of ceruminous glands in EAC causes hyperemia & epidermal plugging Chronic radiation dermatitis can also produce radiation keratosis Associated abnormalities Chronic sinusitis & bronchiectasis Gross Pathologic & Surgical Features Marked inflammation in subepithelial tissue Benign keratin plug filling bony EAC without focal bony erosion Microscopic Features Desquamated keratin tissue Keratin tightly organized in lamellar pattern in KO EAC cholesteatoma shows random keratin organization pattern CLINICAL ISSUES Presentation Most common signs/symptoms Acute severe otalgia Conductive hearing loss Demographics Age Younger patients (< 40 years old) Epidemiology Rare EAC lesion Treatment Excision of keratin plug Direct treatment of granulations when present Excision, cauterization, topical steroids Removal of re-accumulated debris often required DIAGNOSTIC CHECKLIST Image Interpretation Pearls “KO” & “EAC cholesteatoma” terms often confused KO: EAC luminal lesion without bony erosions EAC cholesteatoma: Submucosal lesion with EAC erosions ± bony flecks (50%) Both lesions consist of exfoliated keratin SELECTED REFERENCES Saunders NC et al: Complications of keratosis obturans J Laryngol Otol 120(9):740-4, 2006 Loock J: Keratosis obturans and external ear cholesteatoma Clin Otolaryngol 30(2):213; author reply 213-4, 2005 Kuczkowski J et al: Immunohistochemical and histopathological features of keratosis obturans and cholesteatoma of the external auditory canal Atypical keratosis obturans J Laryngol Otol 118(3):249-50; author reply 250-1, 2004 Shire JR et al: Cholesteatoma of the external auditory canal and keratosis obturans Am J Otol 7(5):361-4, 1986 Medial Canal Fibrosis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - External Auditory Canal > Infectious and Inflammatory Lesions > Medial Canal Fibrosis Medial Canal Fibrosis H Ric Harnsberger, MD Key Facts 1316 Diagnostic Imaging Head and Neck Terminology Medial canal fibrosis (MCF) Discrete clinicopathological disease characterized by formation of fibrous tissue in medial aspect of bony EAC Imaging Early stage MCF Thickened TM with edematous, mildly thickened medial EAC mucosa Late stage MCF Thick tissue “crescent” overlying lateral TM surface TM cannot be resolved as separate from MCF fibrous mass No underlying bony changes present Top Differential Diagnoses Benign EAC debris EAC cholesteatoma EAC exostoses EAC squamous cell carcinoma Necrotizing external otitis EAC keratosis obturans Pathology MCF is final common pathophysiologic pathway for multiple mechanisms of injury to EAC Chronic otitis externa: Most common etiology Secondary to surgical procedure or trauma Suppurative otitis media Radiotherapy to EAC Clinical Issues 50-year-old woman with bilateral otorrhea, conductive hearing loss, and history of chronic otitis Surgical intervention alone corrects conductive hearing loss; topical steroids (Left) Coronal graphic of the right ear shows medial canal fibrosis as a thick fibrous crescent overlying the tympanic membrane, filling medial external auditory canal Inflammatory changes of medial EAC walls also depicted (Right) Coronal T-bone CT reveals a band of soft tissue filling the medial EAC and abutting the tympanic membrane The middle ear is unaffected by medial canal fibrosis The inferior insertion of the tympanic membrane is marked by the tympanic annulus 1317 Diagnostic Imaging Head and Neck (Left) Axial bone CT of the left ear demonstrates the characteristic appearance of mature medial canal fibrosis as a crescentic area of soft tissue thickening on the outer surface of the tympanic membrane extending laterally into the external auditory canal (Right) Coronal bone CT in the same patient reveals the fibrous rind on the outer surface of the tympanic membrane Notice that the middle ear is spared, as is typical for medial canal fibrosis P.VI(2):11 TERMINOLOGY Abbreviations Medial canal fibrosis (MCF) Synonyms Idiopathic inflammatory medial meatal fibrotizing otitis (IMFO) Postinflammatory MCF, acquired MCF, acquired atresia, chronic stenosing external otitis Definitions Discrete clinicopathological disease characterized by formation of fibrous tissue in medial aspect of bony external auditory canal (EAC) IMAGING General Features Best diagnostic clue Fibrous crescent overlying lateral surface of tympanic membrane (TM) Location Medial EAC, adjacent to TM ˜ 50% bilateral Size Variable May have mild thickening of TM with edematous EAC walls early More advanced cases show near complete opacification of EAC Morphology Homogeneous soft tissue conforming to medial EAC CT Findings CECT May see slight enhancement of edematous EAC thickened walls Bone CT Unilateral or bilateral medial EAC fibrous plug Early stage MCF Thickened TM with edematous, mildly thickened medial EAC mucosa Late stage MCF Looks like thick “crescent” of tissue overlying lateral surface of TM TM cannot be resolved as separate from MCF fibrous mass No underlying bony changes present Middle ear-mastoid uninvolved 1318 Diagnostic Imaging Head and Neck MR Findings T1WI Homogeneous low signal soft tissue in medial EAC T2WI Intermediate to low signal soft tissue in medial EAC More fibrous tissue present, the lower the signal T1WI C+ Enhancement of inflamed/edematous EAC thickened walls and TM common Imaging Recommendations Best imaging tool Temporal bone CT Protocol advice T-bone thin section (1 mm or less) nonenhanced, bone algorithm CT Acquire in axial plane; construct coronal plane Be sure to include entire EAC in magnified images DIFFERENTIAL DIAGNOSIS Benign EAC Debris Clinical: Usually obvious on otoscopic exam T-bone CT: Luminal soft tissue in EAC without osseous erosion Air often present in clefts and interstices of EAC debris EAC Cholesteatoma Clinical: Otorrhea and EAC mass in older patient population T-bone CT: Unilateral EAC soft tissue with underlying bony destruction Bony “flakes” seen within mass in 50% of cases EAC Exostoses Clinical: Younger patients with repetitive exposure to cold water (surfer's ear) T-bone CT: Bilateral osseous encroachment of EAC canal Diffuse broad-based overgrowth of osseous EAC with normal mucosal surfaces Usually begins at medial osseous EAC EAC Squamous Cell Carcinoma Clinical: Ulcerating lesion affects external ear Spreads to involve EAC mucosal surfaces CT: Irregular, ill-defined mass with underlying aggressive bony erosion Can mimic EAC cholesteatoma Necrotizing External Otitis Clinical: Elderly diabetics with pseudomonas aeruginosa EAC infection T-bone CT: EAC mucosal swelling ± underlying bone erosion ± deep space abscess (extension of disease inferiorly) Diagnosis confirmed with biopsy and culture EAC Keratosis Obturans Clinical: Younger patients with sinusitis and bronchiectasis T-bone CT: Bilateral keratin plugs filling EAC Mild diffuse EAC enlargement seen without focal bony erosions Spares middle ear cavity PATHOLOGY General Features Etiology Chronic inflammation of medial EAC heals via granulation tissue formation Granulation tissue slowly matures into mature fibrous plug MCF is final common pathophysiologic pathway for multiple mechanisms of injury to EAC Chronic otitis externa Most common underlying etiology Secondary to surgical procedure or trauma P.VI(2):12 Suppurative otitis media Radiotherapy to EAC Autoimmune mechanism suspected Staging, Grading, & Classification 1319 Diagnostic Imaging Head and Neck Early (wet) stage Chronic otitis media with otorrhea and conductive hearing loss Late (dry) stage (mature MCF) Medial EAC fibrous plug with conductive hearing loss Gross Pathologic & Surgical Features Inflamed, edematous margins to fibrous plug covering tympanic membrane Microscopic Features Early stage Granulation tissue May demonstrate lymphocyte infiltration Late stage Layered fibrous connective tissue May demonstrate focal areas of calcification CLINICAL ISSUES Presentation Most common signs/symptoms Conductive hearing loss Typically 20-40 decibel Other signs/symptoms Chronic otitis externa Chronic dermatitis (eczema or psoriasis) Tinnitus Otorrhea Early stage Chronic otitis media with otorrhea and conductive hearing loss (CHL) (wet) Late stage Mature fibrous plug present with CHL (dry) Clinical profile 50-year-old woman with bilateral otorrhea, conductive hearing loss, and history of chronic otitis Demographics Age Mean age: 50 years old Range: 5-80 years old Usually rare in pediatric population Gender M:F = 1:2 Epidemiology Rare lesion Natural History & Prognosis Surgical complication Recurrence of EAC stenosis (< 5%) Re-stenosis may occur years after treatment Treatment Surgical intervention alone corrects conductive hearing loss Early phase Topical steroids Late phase Surgical intervention required to correct CHL Excision of all fibrous tissue and involved skin Wide canaloplasty Meatoplasty followed by reconstruction by split skin graft Squamous epithelium may be needed to repopulate EAC and lateral TM Skin grafts may be needed from posterior pinna DIAGNOSTIC CHECKLIST Consider Differentiate MCF from keratosis obturans and EAC cholesteatoma Medial canal fibrosis: Look for medial EAC tissue plug with no EAC bone changes Keratosis obturans: Look for complete opacification and subtle EAC bony widening 1320 Diagnostic Imaging Head and Neck EAC cholesteatoma: Look for focal EAC soft tissue mass with underlying bony erosion ± intramural bone flecks Image Interpretation Pearls Crescentic soft tissue plug against tympanic membrane highly suggestive of MCF No role for MR imaging in MCF diagnosis or imaging evaluation Long-term follow-up is recommended to evaluate risk of recurrence SELECTED REFERENCES Hopsu E et al: Idiopathic inflammatory medial meatal fibrotizing otitis presenting in children Otol Neurotol 29(3):350-2, 2008 Eshraghi AA et al: Partial medial canal fibrosis Ear Nose Throat J 85(2):75, 2006 Ulubil SA et al: Complete medial canal fibrosis Ear Nose Throat J 85(1):10, 2006 Lin VY et al: Medial canal fibrosis: surgical technique, results, and a proposed grading system Otol Neurotol 26(5):825-9, 2005 Luong A et al: Acquired external auditory canal stenosis: assessment and management Curr Opin Otolaryngol Head Neck Surg 13(5):273-6, 2005 Hopsu E et al: Idiopathic inflammatory medial meatal fibrotizing otitis Arch Otolaryngol Head Neck Surg 128(11):1313-6, 2002 Lavy J et al: Chronic stenosing external otitis/postinflammatory acquired atresia: a review Clin Otolaryngol 25(6):435-9, 2000 el-Sayed Y: Acquired medial canal fibrosis J Laryngol Otol 112(2):145-9, 1998 Slattery WH 3rd et al: Postinflammatory medial canal fibrosis Am J Otol 18(3):294-7, 1997 10 Birman CS et al: Medial canal stenosis—chronic stenosing external otitis Am J Otol 17(1):2-6, 1996 11 Gorenflo M et al: Morphometric techniques in the evaluation of pulmonary vascular changes due to congenital heart disease Pathol Res Pract 192(2):107-16, 1996 12 Magliulo G et al: Medial meatal fibrosis: current approach J Laryngol Otol 110(5):417-20, 1996 13 Katzke D et al: Postinflammatory medial meatal fibrosis A neglected entity? Arch Otolaryngol 108(12):779-80, 1982 P.VI(2):13 Image Gallery (Left) Axial bone CT of the right ear shows the early findings of medial canal fibrosis as thin crescentic tympanic membrane (TM) thickening Clinical diagnosis at this stage is necessary as CT will not differentiate this appearance from other causes of TM thickening (Right) Coronal bone CT in the same patient reveals the upper tympanic membrane is thicker than the lower portion As the lesion progresses, the fibrous crescent will affect the whole lateral TM surface 1321 Diagnostic Imaging Head and Neck (Left) Coronal bone CT in this patient with a more aggressive case of medial canal fibrosis reveals a sliver of air remaining as the EAC lumen The fibrous plug has nearly obliterated the EAC (Right) Coronal T1 C+ MR in this patient with early phase medial canal fibrosis demonstrates enhancing fibrous tissue within the medial right external auditory canal As expected, the middle ear is spared (Left) Axial bone CT of the right ear reveals a thick tympanic membrane with foci of calcification Calcification has been reported in path specimens of MCF Whether this is a part of the lesion or an associated locus of tympanosclerosis cannot be determined (Right) Axial T1WI C+ FS MR in the same patient shows that the medial canal fibrosis is enhancing with the area of calcification seen as a low signal foci EAC Cholesteatoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - External Auditory Canal > Infectious and Inflammatory Lesions > EAC Cholesteatoma EAC Cholesteatoma H Ric Harnsberger, MD Key Facts Terminology External auditory canal cholesteatoma (EACC) EACC: EAC erosive lesion composed of exfoliated keratin within stratified squamous epithelium Imaging Unilateral scalloping soft tissue bony EAC mass Bone fragments within soft tissue mass (50%) May extend locally into subjacent bony structures 1322 Diagnostic Imaging Head and Neck Tympanic membrane intact; middle ear spared Top Differential Diagnoses Medial canal fibrosis of EAC Necrotizing external otitis Squamous cell carcinoma of EAC Keratosis obturans of EAC Pathology Spontaneous: Abnormal migration of EAC ectoderm Secondary: Postoperative or post-traumatic Congenital: Ectodermal rest within EAC wall (rare) May be associated with congenital external ear dysplasia Clinical Issues Primary symptoms: Otorrhea & otalgia Older population, 40-75 years old Natural history: Relentless increase in size & erosion of EAC bony wall Surgical excision for larger lesions with bony invasion Diagnostic Checklist Focal, unilateral EAC mass + EAC bony scalloping ± bony flecks = EACC (Left) Coronal graphic shows an EAC cholesteatoma as an erosive-scalloping submucosal mass in the inferior bony external auditory canal Note bone erosion with bony flecks within cholesteatoma matrix (Right) Coronal bone CT reveals an EAC cholesteatoma as a soft tissue mass along the inferior bony canal with underlying osseous erosion with bony flecks within the cholesteatoma matrix (Left) This elderly woman presented with otorrhea, otalgia, & heaped up submucosal lesion in EAC area Axial bone CT 1323 Diagnostic Imaging Head and Neck shows an erosive lesion of the bony EAC affecting the anterior, posterior, and inferior walls Note multifocal bony flecks within the soft tissue component of the lesion (Right) Coronal bone CT in the same patient reveals an EAC cholesteatoma with bony flecks and underlying bone erosions Note air foci within the lesion P.VI(2):15 TERMINOLOGY Abbreviations External auditory canal cholesteatoma (EACC) Synonyms Acquired atresia of EAC Definitions EAC erosive lesion composed of exfoliated keratin within stratified squamous epithelium IMAGING General Features Best diagnostic clue Erosive EAC soft tissue mass ± internal bony flecks Size mm to cm CT Findings Bone CT Unilateral scalloping soft tissue bony EAC mass Bone fragments within soft tissue mass (50%) May extend locally into subjacent bony structures Tympanic membrane intact; middle ear spared MR Findings T1WI Soft tissue intensity mass in EAC T2WI Intermediate signal; compared to ↑ signal of inflammatory tissues T1WI C+ Low intensity, rim-enhancing EAC mass Imaging Recommendations Best imaging tool Axial & coronal bone CT of temporal bone DIFFERENTIAL DIAGNOSIS Medial Canal Fibrosis of EAC CT: Obstructive fibrous tissue within medial EAC Bilateral; no bony erosion present Necrotizing External Otitis Elderly diabetic patients with pseudomonas Infectious process of EAC CT: Unilateral inflammatory soft tissue changes Bony osteomyelitis changes Squamous Cell Carcinoma (SCCa) of EAC Elderly patients with known external ear skin SCCa CT: Unilateral invasive soft tissue mass Keratosis Obturans of EAC Younger patients with sinusitis & bronchiectasis CT: Bilateral keratin plugs filling EAC No focal EAC bony changes PATHOLOGY General Features Etiology Spontaneous: Abnormal migration of EAC ectoderm Secondary: Postoperative or post-traumatic Congenital: Ectodermal rest within EAC wall (rare) May be associated with congenital external ear dysplasia Staging, Grading, & Classification 1324 Diagnostic Imaging Head and Neck Staging criteria (histopathology + clinical stage) Stage I: Superficial; hyperplasia of canal epithelium Stage II: Periosteitis; localized to ear pocket Stage III: Extension into bony canal Stage IV: Extension into adjacent bony structures Gross Pathologic & Surgical Features Different type of cholesteatoma; not “pearly white” Waxy material discolored by inflammatory change Intramural bony fragments possible Microscopic Features Similar to epidermoid inclusion cyst Stratified squamous epithelium with progressive exfoliation of keratinous material Contents may be rich in cholesterol crystals CLINICAL ISSUES Presentation Most common signs/symptoms Otorrhea & otalgia Other signs/symptoms Conductive hearing loss Demographics Age Older population, 40-75 years old Natural History & Prognosis Relentless increase in size & erosion of EAC bony wall Recurrences more common with increasing lesion size & invasion of surrounding osseous structures Treatment Most controlled with periodic office debridement Surgical excision for larger lesions with bony invasion DIAGNOSTIC CHECKLIST Consider EAC cholesteatoma unilateral lesion Medial canal fibrosis & keratosis obturans bilateral Image Interpretation Pearls Focal, unilateral EAC mass + EAC bony scalloping ± bony flecks = EACC SELECTED REFERENCES Magliulo G: Acquired atresia of the external auditory canal: recurrence and long-term results Ann Otol Rhinol Laryngol 118(5):345-9, 2009 Dubach P et al: External auditory canal cholesteatoma: reassessment of and amendments to its categorization, pathogenesis, and treatment in 34 patients Otol Neurotol 29(7):941-8, 2008 Heilbrun ME et al: External auditory canal cholesteatoma: clinical and imaging spectrum AJNR Am J Neuroradiol 24(4):751-6, 2003 Benign and Malignant Tumors EAC Osteoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - External Auditory Canal > Benign and Malignant Tumors > EAC Osteoma EAC Osteoma H Ric Harnsberger, MD Key Facts Terminology Rare, benign, focal, pedunculated, bony overgrowth of osseous EAC with normal overlying soft tissues Imaging Most common site: Bony cartilaginous junction EAC Bone CT: Benign-appearing, focal, pedunculated, bony overgrowth of osseous EAC Wax, squamous debris, or secondary cholesteatoma possible with large, lateral lesions Top Differential Diagnoses EAC exostoses (surfer's ear) EAC cholesteatoma 1325 Diagnostic Imaging Head and Neck Medial canal fibrosis Necrotizing external otitis Benign EAC debris Pathology Irregularly oriented lamellated bone with surrounding discrete, fibrovascular channels Osteoma found in other T-bone sites Ossicles, mastoid, internal auditory canal Clinical Issues Asymptomatic, usually incidental finding Permanent cure with adequate surgical excision Diagnostic Checklist Differentiate from EAC exostoses EAC osteoma: Narrow-based, single lesion, lateral EAC, unilateral EAC exostosis: Broad-based, circumferential, multilobular, medial EAC, bilateral (Left) Patient presents with hard submucosal mass in mid-external auditory canal Axial bone CT shows an osteoma pedunculating from the anterolateral aspect of the bony EAC (Right) Coronal bone CT in the same patient shows the osteoma almost completely plugging the external auditory canal lumen There is still sufficient room for wax and squamous debris to exit the medial EAC (Left) Clinical examination shows complete occlusion of the external auditory canal Axial bone CT demonstrates a pedunculated osteoma arising from the anterior wall of the bony EAC Notice the secondary cholesteatoma within the medial EAC (Right) Coronal bone CT in the same patient reveals the osteoma plugging the EAC The secondary cholesteatoma is visible medial to the osteoma Notice the subtle scalloping of the bony wall of the EAC inferiorly 1326 Diagnostic Imaging Head and Neck P.VI(2):17 TERMINOLOGY Abbreviations External auditory canal (EAC) osteoma Definitions Rare, benign, focal, pedunculated, bony overgrowth of osseous EAC with normal overlying soft tissues IMAGING General Features Best diagnostic clue Unilateral, solitary, pedunculated, bony overgrowth of EAC without aggressive features Location Unilateral EAC, single lesion typical Most common site: Bony cartilaginous junction EAC Size Variable, usually small (< cm) Morphology Variable, usually oval CT Findings Bone CT Benign-appearing, focal, pedunculated, bony overgrowth of osseous EAC Wax, squamous debris, or secondary cholesteatoma possible with large, lateral lesions Imaging Recommendations Best imaging tool Axial & coronal T-bone CT DIFFERENTIAL DIAGNOSIS EAC Exostoses (Surfer's Ear) Most common solid tumor of EAC Broad-based, benign-appearing, bilateral bony overgrowths of EAC Circumferential, multilobular EAC Cholesteatoma Unilateral EAC destructive mass Intramural bony “flakes” (50%) Medial Canal Fibrosis Fibrous mass in medial EAC without bony erosion Follows otitis externa or surgical procedure Necrotizing External Otitis Severe EAC infectious process Granulation tissue with possible bony erosion at inferior bony-cartilaginous junction Benign EAC Debris Soft tissue density in EAC without bony changes PATHOLOGY General Features Etiology Likely spontaneous bony growth Reaction to repeated external insult? Associated abnormalities Osteomas associated with EAC cholesteatoma Possible association of osteomas with prior EAC surgical procedures Osteoma found in other T-bone sites Ossicles, mastoid, internal auditory canal Embryology-anatomy May be attached to tympanosquamous or tympanomastoid suture line Gross Pathologic & Surgical Features Osteoma connected to underlying EAC bone Microscopic Features Pathologically similar to exostoses Irregularly oriented lamellated bone with surrounding discrete, fibrovascular channels 1327 Diagnostic Imaging Head and Neck CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic, usually incidental finding Other signs/symptoms If large, conductive hearing loss Demographics Age Broad age range Epidemiology Unilateral & solitary EAC osteoma is less common than exostoses 20% prevalence in surfers (possible early exostoses) Natural History & Prognosis Permanent cure with adequate surgical excision Possible surgical complications EAC stenosis Temporomandibular joint prolapse Treatment Medical therapy is adequate without surgical excision for symptomatic lesions Surgical removal may be performed through EAC under local anesthesia DIAGNOSTIC CHECKLIST Image Interpretation Pearls Differentiate from EAC exostoses EAC osteoma: Narrow-based, single lesion, lateral EAC, unilateral EAC exostosis: Broad-based, circumferential, multilobular, medial EAC, bilateral SELECTED REFERENCES Viswanatha B: Extracanalicular osteoma of the temporal bone Ear Nose Throat J 87(7):381-3, 2008 Yuen HW et al: External auditory canal osteoma Otol Neurotol 29(6):875-6, 2008 Ramirez-Camacho R et al: Fibro-osseous lesions of the external auditory canal Laryngoscope 109(3):488-91, 1999 Orita Y et al: Osteoma with cholesteatoma in the external auditory canal Int J Pediatr Otorhinolaryngol 43(3):28993, 1998 EAC Exostoses > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - External Auditory Canal > Benign and Malignant Tumors > EAC Exostoses EAC Exostoses H Ric Harnsberger, MD Key Facts Terminology Definition: Benign overgrowth of bony EAC in response to chronic cold water exposure Imaging Temporal bone CT Broad-based or more focal circumferential bony overgrowth of osseous EAC Bilateral; variable EAC stenosis results Top Differential Diagnoses EAC osteoma EAC cholesteatoma EAC medial canal fibrosis Necrotizing external otitis Clinical Issues Conductive hearing loss (CHL) Other signs/symptoms Otitis externa, tinnitus, otalgia Patient profile 20-50 year olds Male predominance 70% prevalence in surfers Treatment issues 1328 Diagnostic Imaging Head and Neck Often require no treatment May require surgical excision Diagnostic Checklist Image interpretation pearls Most common differential diagnosis: EAC osteoma EAC osteoma: Unilateral, lateral bony EAC focal osseous protuberance EAC exostoses: Bilateral mid-bony EAC circumferential, multilobular narrowing (Left) Coronal graphic shows benign-appearing bony overgrowth of the right EAC in a case of EAC exostoses Insert shows otoscopic view of circumferential submucosal EAC narrowing (Right) Coronal bone CT of right temporal bone shows severe EAC stenosis secondary to circumferential exostoses that developed bilaterally as a result of chronic cold water exposure from surfing (Left) Axial bone CT reveals bilateral external auditory canal exostoses with moderate EAC luminal stenosis (Courtesy C Schatz, MD.) (Right) Coronal temporal bone CT in the same patient shows external auditory canal exostoses with moderate EAC luminal stenosis The bilaterality (not shown) and circumferential bony involvement differentiate this lesion from unilateral, focal EAC osteoma P.VI(2):19 TERMINOLOGY Synonyms Surfer's ear; cold water ear Definitions Benign overgrowth of bony EAC in response to chronic cold water exposure 1329 Diagnostic Imaging Head and Neck IMAGING General Features Best diagnostic clue Benign, overgrowth of osseous EAC with normal overlying soft tissues Location Bony EAC; bilateral Usually located medial to EAC isthmus EAC osteoma usually located lateral to isthmus Size Variable, narrowing of EAC Morphology Broad-based or focal; circumferential CT Findings CECT Normal soft tissues overlying stenotic EAC Bone CT Broad-based or more focal circumferential bony overgrowth of osseous EAC Bilateral; variable EAC stenosis results Imaging Recommendations Best imaging tool Temporal bone CT MR of no help with this diagnosis DIFFERENTIAL DIAGNOSIS EAC Osteoma Unilateral focal, pedunculated, bony overgrowth EAC Cholesteatoma Unilateral, bone flakes (50%) Underlying bony scalloping EAC Medial Canal Fibrosis Inflammatory fibrous EAC plug Necrotizing External Otitis EAC infection in immunocompromised patient PATHOLOGY General Features Etiology Bony EAC “reaction” to cold water exposure Gross Pathologic & Surgical Features Benign, bony overgrowth of osseous EAC Microscopic Features Pathologically similar to osteoma Parallel, concentric layers of subperiosteal bone CLINICAL ISSUES Presentation Most common signs/symptoms Conductive hearing loss (CHL) Other signs/symptoms Otitis externa, tinnitus, otalgia Although bilateral, 80% present with unilateral symptoms Clinical profile CHL in adult male with history of prolonged cold water exposure (swimmers, surfers, divers) Demographics Age 20-50 year olds Gender Male predominance Ethnicity Lesion not found in African-Americans Epidemiology 70% prevalence in surfers 1330 Diagnostic Imaging Head and Neck Natural History & Prognosis Complete occlusion of EAC is rare Normal hearing & normal epithelial migration patterns seen postoperatively 5% surgical complication rate Canal stenosis, TMJ prolapse, sensorineural loss, & persistent tympanic membrane (TM) perforation Treatment Often requires no treatment May require surgical excision Complications of superior EAC drilling TM perforation Temporomandibular joint dehiscence Drilling excision along posterior, inferior, & anterior walls performed with less risk of complications Allows preservation of canal skin, leading to permanent cure DIAGNOSTIC CHECKLIST Image Interpretation Pearls Biggest differential diagnosis: EAC osteoma Osteoma: Unilateral, focal osseous protuberance Exostoses: Bilateral circumferential, multilobular bony EAC narrowing SELECTED REFERENCES Sheard PW et al: Prevalence and severity of external auditory exostoses in breath-hold divers J Laryngol Otol 122(11):1162-7, 2008 Hetzler DG: Osteotome technique for removal of symptomatic ear canal exostoses Laryngoscope 117(1 Pt Suppl 113):1-14, 2007 Kutz JW Jr et al: Exostosis of the external auditory canal Ear Nose Throat J 85(3):142, 2006 Vasama JP: Surgery for external auditory canal exostoses: a report of 182 operations ORL J Otorhinolaryngol Relat Spec 65(4):189-92, 2003 Smelt GJ: Exostoses of the internal auditory canal J Laryngol Otol 98(4):347-50, 1984 EAC Skin SCCa > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - External Auditory Canal > Benign and Malignant Tumors > EAC Skin SCCa EAC Skin SCCa Hilda E Stambuk, MD Key Facts Imaging Best diagnostic clue: EAC mass with aggressive underlying bony changes T-bone CT: Best predicts tumor osseous invasion Larger lesions: Use T-bone CT & enhanced MR Top Differential Diagnoses Benign EAC debris EAC cholesteatoma Necrotizing external otitis Pathology Auricle skin SCCa spreads into EAC ↑ incidence in patients with otological diseases SCCa is most common malignancy of EAC Clinical Issues Ulcerating auricle-EAC skin lesion EAC SCCa 1st destroys osseous EAC Next invades surrounding anatomic landscape Any nodal disease should be considered advanced disease (stage IV) Treatment alternatives T1-T2 tumors: Treated with surgery or radiation therapy T3-T4 tumors: Treated with surgery and radiation ± chemotherapy With localized tumors, en bloc resection often curative Best outcomes with combined surgery & postoperative radiation therapy Diagnostic Checklist Secondary EAC involvement from regional primary skin SCCa is much more common than primary EAC squamous cell carcinoma 1331 Diagnostic Imaging Head and Neck (Left) Axial right ear T-bone CT reveals EAC SCCa invading inferiorly from EAC, causing osseous invasion of the anterolateral mastoid and posterior wall of the condylar fossa (Right) Axial T1WI C+ MR at the level of the external auditory canal shows invasive, enhancing EAC squamous cell carcinoma posterior and lateral to right condylar head (Left) Axial CT of temporal bone reveals a SCCa of the right EAC with prominent soft tissue mass in and inferior to the right EAC Osseous invasion through the posterior wall of the right TMJ condylar fossa and inferior mastoid process is present (Right) Axial T1WI C+ FS MR shows advanced EAC SCCa with gross transdural extension into the left middle cranial fossa and perineural spread along the left 7th cranial nerve labyrinthine segment and geniculate ganglion P.VI(2):21 TERMINOLOGY Definitions External ear SCCa involving EAC IMAGING General Features Best diagnostic clue EAC mass ± aggressive underlying bony changes Relevant anatomy EAC, auricle, & adjacent scalp nodal drainage To pre- & postauricular & parotid nodes 1332 Diagnostic Imaging Head and Neck CT Findings CECT Heterogeneously enhancing EAC lesion Periauricular, parotid malignant nodes possible Bone CT Early: EAC soft tissue mass; no bony destruction EAC cartilage invasion may be difficult to diagnose Late: Underlying bony destructive changes SCCa tends to spread to auricle & EAC Involvement of middle ear structures is rare MR Findings T1WI C+ Homogeneous or heterogeneous enhancement Rare if advanced disease spreads to middle ear CN7 perineural spread in advanced disease Middle cranial fossa invasion Nuclear Medicine Findings PET FDG-PET useful for detecting residual or recurrent disease post treatment DIFFERENTIAL DIAGNOSIS Benign EAC Debris CT: Soft tissue debris in EAC without bony erosion EAC Cholesteatoma May exactly mimic EAC SCCa CT: Often see bony “flakes” in mass Necrotizing External Otitis Older diabetic patients; secondary to pseudomonas CT: Granulation tissue with possible bony erosion at inferior bony-cartilaginous junction PATHOLOGY Staging, Grading, & Classification T1: Tumor limited to EAC without bony erosion or soft tissue involvement T2: Tumor with limited EAC osseous erosion or soft tissue involvement T3: Tumor eroding osseous EAC with limited soft tissue/middle ear/mastoid involvement T4: Tumor eroding deeper inner ear structures/TMJ/extensive soft tissue extension, or CN7 paresis Gross Pathologic & Surgical Features Presents as ill-defined, ulcerative ± indurated lesion Microscopic Features SCCa is defined as having predominantly squamous differentiation Intracellular bridges or keratinization (± keratin pearls) present EAC SCCa pathologically similar to pseudoepitheliomatous hyperplasia CLINICAL ISSUES Presentation Most common signs/symptoms Ulcerating auricle-EAC skin lesion Presentation may mimic otitis externa or EAC cholesteatoma Other signs/symptoms Otorrhea, otalgia, & conductive hearing loss Demographics Age Median age: 65 years old Epidemiology Malignant tumors of EAC are relatively rare SCCa > > basal cell ca > > adenoid cystic ca Natural History & Prognosis EAC SCCa destroys osseous EAC, then invades surrounding anatomic landscape Treatment Surgery nearly always performed With localized tumors, en bloc resection often curative T1-T2 tumors: Surgery or radiation therapy 1333 Diagnostic Imaging Head and Neck T3-T4 tumors: Surgery and radiation ± chemotherapy Best results: Combined surgery-postoperative radiation DIAGNOSTIC CHECKLIST Consider Secondary EAC involvement from adjacent primary skin SCCa much more common than primary EAC SCCa Radiologically interrogate surrounding structures for possible involvement Parotid gland (direct invasion or nodes) Temporomandibular joint Image Interpretation Pearls Look for osseous destructive changes! Bony invasion predicts treatment outcome SELECTED REFERENCES Cristalli G et al: Treatment and outcome of advanced external auditory canal and middle ear squamous cell carcinoma J Craniofac Surg 20(3):816-21, 2009 Gidley PW: Managing malignancies of the external auditory canal Expert Rev Anticancer Ther 9(9):1277-82, 2009 Prabhu R et al: Squamous cell carcinoma of the external auditory canal: long-term clinical outcomes using surgery and external-beam radiotherapy Am J Clin Oncol 32(4):401-4, 2009 Pulec JL et al: Squamous cell carcinoma of the external auditory canal Ear Nose Throat J 83(1):9, 2004 Section - Middle Ear-Mastoid Congenital Lesions Congenital Middle Ear Cholesteatoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Congenital Lesions > Congenital Middle Ear Cholesteatoma Congenital Middle Ear Cholesteatoma H Ric Harnsberger, MD Key Facts Terminology Congenital middle ear cholesteatoma (CMEC) Definition: Cholesteatoma in middle ear behind intact TM in patient with no history of surgery, otitis media, or otorrhea Imaging Temporal bone CT findings Small: Well-circumscribed soft tissue ME mass medial to ossicles Large: Erodes ossicles, middle ear wall, lateral semicircular canal, or tegmen tympani Long process of incus & stapes superstructure most commonly destroyed ossicles If aditus ad antrum occluded, mastoid air cells opacify with retained secretions Mastoid pneumatization usually normal MR findings T1WI C+: Peripherally enhancing ME mass DWI: Larger lesions visible as high signal mass Top Differential Diagnoses Pars flaccida-acquired cholesteatoma Pars tensa-acquired cholesteatoma Glomus tympanicum paraganglioma Facial nerve schwannoma of tympanic segment Middle ear cholesterol granuloma Clinical Issues Incidental avascular ME mass behind intact TM Unilateral conductive hearing loss (30%) Complete surgical extirpation = treatment of choice Diagnostic Checklist Younger patient + CT lesion medial to ossicles + normal mastoid pneumatization = CMEC 1334 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows congenital middle ear cholesteatoma Notice the lesion surrounds and is medial to the ossicles The tympanic membrane is intact (Right) Coronal T-bone CT of the right ear demonstrates a large congenital cholesteatoma filling the middle ear cavity with subtle long process of incus and stapes hub erosion and deossification The tympanic membrane bulges laterally but is intact by otoscopic examination (Left) Axial bone CT of the right ear reveals a medial epitympanic congenital cholesteatoma eroding the medial head of the malleus and short process of the incus Aditus ad antrum block causes mastoid effusion (Right) Coronal bone CT in the same patient shows CMEC eroding long process of incus and filling the oval window niche The tympanic segment of CN7 canal enlargement is secondary to cholesteatoma focal invasion P.VI(3):3 TERMINOLOGY Abbreviations Congenital middle ear cholesteatoma (CMEC) Synonyms Primary cholesteatoma, epidermoid Definitions Cholesteatoma in middle ear behind intact TM in patient with no history of surgery, otitis media, or otorrhea IMAGING General Features Best diagnostic clue T-bone CT shows smooth, well-circumscribed middle ear mass ± ossicular erosions 1335 Diagnostic Imaging Head and Neck Location Multiple middle ear (ME) locations Anterosuperior quadrant of tympanic cavity near eustachian tube Posterior epitympanum at tympanic isthmi (area between middle ear cavity & attic) Epitympanum medial to ossicles Size Usually small because identified on otoscopic exam Entire ME cavity not involved at presentation Morphology Lobular, discrete ME mass CT Findings Bone CT T-bone CT appearance depends on size of lesion Small: Detected early, appears as well-circumscribed soft tissue ME mass Large: Larger CMEC may erode ossicles, middle ear wall, lateral semicircular canal, or tegmen tympani Long process of incus & stapes superstructure most commonly destroyed ossicles Bone erosion less common than in acquired cholesteatoma Labyrinthine extension may occur but only late in disease process If aditus ad antrum occluded, mastoid air cells opacify with retained secretions Associated inflammatory changes infrequent Mastoid pneumatization usually normal Common ME locations Anterosuperior quadrant middle ear, adjacent to eustachian tube & anterior tympanic ring Inferior but adjacent to tensor tympani muscle Peristapedial region Posterior epitympanum, at tympanic isthmi MR Findings T1WI Iso- to hypointense ME mass T2WI Intermediate intensity ME mass With larger lesions, aditus ad antrum obstruction seen as high signal retained secretions in mastoid DWI Larger lesions visible as high signal mass T1WI C+ Peripherally enhancing ME mass CMEC is nonenhancing material with subtle rim enhancement If lesion is longstanding, associated scar may be seen as thickened area of enhancement adjacent to CMEC Imaging Recommendations Best imaging tool T-bone CT = exam of choice T1WI C+ MR is complementary exam in certain circumstances Recommended if recurrent or large CMEC Recommended if diagnosis uncertain with glomus tympanicum or facial nerve schwannoma possible considerations Glomus tumor & CN7 schwannoma enhance Protocol advice If large cholesteatoma, DWI sequence diagnostic DIFFERENTIAL DIAGNOSIS Pars Flaccida-Acquired Cholesteatoma Otoscopy shows pars flaccida TM perforation CT findings Scutum erosion with lesion in lateral epitympanum Ossicular chain & lateral semicircular canal erosion Chronic inflammatory changes present Mastoid underpneumatized Pars Tensa-Acquired Cholesteatoma Otoscopy shows pars tensa TM perforation 1336 Diagnostic Imaging Head and Neck CT findings Lesion enlarges medial to ossicles Ossicular erosion common Glomus Tympanicum Paraganglioma Otoscopy shows pulsatile, vascular mass behind TM Unusual in pediatric or adolescent patient CT findings Sessile mass on cochlear promontory No bony erosions present MR findings Focal enhancing mass on T1WI C+ MR Facial Nerve Schwannoma of Tympanic Segment Otoscopy shows avascular mass behind intact TM Appearance can closely mimic congenital cholesteatoma CT findings Tubular mass emanating from tympanic CN7 canal Enlarged bony facial nerve canal Enlarged geniculate fossa MR findings Tubular enhancing mass on T1WI C+ MR Extends from geniculate ganglion along tympanic segment of facial nerve Middle Ear Cholesterol Granuloma Otoscopy reveals blue TM History of prior surgery or recurrent ME infection CT findings Middle ear mass with ossicular erosion common P.VI(3):4 MR findings T1 nonenhanced MR shows high signal in ME PATHOLOGY General Features Etiology principal theories Congenital ectodermal rest in middle ear cavity left behind at time of closure of neural tube (3rd-5th week of fetal life) Lack of regression of “epidermoid formation” Epidermoid formation: Point of epithelial transformation between tympanic cavity & eustachian tube When does not regress, becomes mass-like middle ear accumulation of stratified epithelial squamous cells Anterosuperior CMEC results Neither theory is unifying Associated abnormalities EAC atresia can present with associated congenital cholesteatoma In EAC or middle ear Rarely associated with 1st branchial cleft remnant Other locations of congenital cholesteatoma in temporal bone Petrous apex, mastoid, external auditory canal, facial nerve canal Staging, Grading, & Classification CMEC staging system (after Potsic, 2002) Stage 1: Single quadrant; no ossicular involvement or mastoid extension Stage 2: Multiple quadrant; no ossicular involvement or mastoid extension Stage 3: Ossicular involvement; no mastoid involvement Stage 4: Mastoid extension Gross Pathologic & Surgical Features Circumscribed, pearly-white mass with capsular sheen Microscopic Features 1337 Diagnostic Imaging Head and Neck Identical to epidermoid inclusion cyst Stratified squamous epithelium, with progressive exfoliation of keratinous material Contents rich in cholesterol crystals CLINICAL ISSUES Presentation Most common signs/symptoms Incidental avascular ME mass behind intact TM Other signs/symptoms Unilateral conductive hearing loss (30%) Large CMEC can obstruct eustachian tube with resultant ME-mastoid effusion & infection Demographics Age Average age of presentation or detection Anterior or anterosuperior: years Posterosuperior & mesotympanum: 12 years Attic & mastoid antrum involvement: 20 years Gender M:F = 3:1 Epidemiology Accounts for 5% of all temporal bone cholesteatomas Natural History & Prognosis Smaller, anterior lesions have better outcome with complete surgical resection Smaller lesions may be encapsulated or cystic & easily removed If untreated, keratin debris accumulates over time, with resultant larger lesion Enlarging, cyst-like lesion may rupture, extending throughout ME If eustachian tube obstructed, otomastoiditis occurs Larger lesions with infection may be difficult to differentiate from acquired cholesteatoma Large lesions or posterior epitympanic cholesteatoma have recurrence rates as high as 20% Treatment Complete surgical extirpation = treatment of choice Tympanoplasty for small, well-encapsulated CMEC Tympanoplasty with canal wall up mastoidectomy for large CMEC Tympanoplasty with canal wall down mastoidectomy for very large CMEC Ossicle chain reconstruction often necessary DIAGNOSTIC CHECKLIST Consider CMEC when avascular mass seen behind intact TM CMEC when no history of repeat ME infections CMEC when ME is opacified with wall erosion in congenital external ear dysplasia Image Interpretation Pearls Younger patient + CT lesion medial to ossicles + normal mastoid pneumatization = CMEC SELECTED REFERENCES Park KH et al: Congenital middle ear cholesteatoma in children; retrospective review of 35 cases J Korean Med Sci 24(1):126-31, 2009 De Foer B et al: The value of single-shot turbo spin-echo diffusion-weighted MR imaging in the detection of middle ear cholesteatoma Neuroradiology 49(10):841-8, 2007 Lazard DS et al: Congenital cholesteatoma: risk factors for residual disease and retraction pockets—a report on 117 cases Laryngoscope 117(4):634-7, 2007 Kojima H et al: Congenital cholesteatoma clinical features and surgical results Am J Otolaryngol 27(5):299-305, 2006 Darrouzet V et al: Congenital middle ear cholesteatomas in children: our experience in 34 cases Otolaryngol Head Neck Surg 126(1):34-40, 2002 Nelson M et al: Congenital cholesteatoma: classification, management, and outcome Arch Otolaryngol Head Neck Surg 128(7):810-4, 2002 Potsic WP et al: A staging system for congenital cholesteatoma Arch Otolaryngol Head Neck Surg 128(9):1009-12, 2002 Potsic WP et al: Congenital cholesteatoma: 20 years' experience at The Children's Hospital of Philadelphia Otolaryngol Head Neck Surg 126(4):409-14, 2002 P.VI(3):5 1338 Diagnostic Imaging Head and Neck Image Gallery (Left) Axial bone CT of the right ear in a patient with recurrent otomastoiditis and conductive hearing loss reveals a soft tissue mass in the medial epitympanum eroding the medial surface of the head of the malleus & short process of incus The anterior tympanic CN7 canal is also dehiscent (Right) Coronal bone CT in the same patient shows erosion of medial malleus head and lateral margin of anterior tympanic segment of CN7 canal by this medial epitympanic CMEC (Left) Axial bone CT of the left ear reveals a CMEC in the anterior epitympanic recess scalloping adjacent middle ear wall and bowing the epitympanic cog posteriorly The malleus head abuts the posterior margin of the CMEC (Right) Axial T1WI C+ MR in the same patient reveals the typical rim enhancement along the margins of this anterior epitympanic CMEC The central nonenhancing component is the CMEC Notice the more medial cochlear signal 1339 Diagnostic Imaging Head and Neck (Left) Axial left ear bone CT in this 32-year-old patient demonstrates a posterior epitympanum-aditus ad antrum CMEC that has eroded the short process of the incus The exact extent of the lesion is difficult to assess on the CT image (Right) Axial T1WI C+ fat-saturated MR in the same patient shows the CMEC extending into the mastoid antrum with the retained mastoid fluid enhancing Posterior epitympanic CMEC often present remain asymptomatic and present in older patients Congenital Mastoid Cholesteatoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Congenital Lesions > Congenital Mastoid Cholesteatoma Congenital Mastoid Cholesteatoma H Ric Harnsberger, MD Key Facts Terminology Congenital cholesteatoma in mastoid secondary to epithelial rest Imaging Bone CT findings Expansile soft tissue mass Smooth erosion of mastoid bone MR findings T1 low, T2 high T1WI C+ nonenhancing DWI high signal Mastoid locations Anywhere in mastoid area Medial mastoid ± IAC ± petrous apex Occipito-mastoid suture Top Differential Diagnoses Large pars flaccida acquired cholesteatoma Mastoid cholesterol granuloma T-bone fibrous dysplasia T-bone Langerhans histiocytosis Pathology Stratified squamous epithelium with progressive exfoliation of keratinous material Clinical Issues Presentations Incidental head MR finding Headache Older patient group compared to other locations; 20-40 years Treatment Surgical removal treatment of choice 1340 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a multilobular congenital cholesteatoma involving the lateral clivus and the medial mastoid The expansile bony margins are suggestive of this diagnosis (Right) Axial T2WI MR reveals a giant temporal bone congenital mastoid cholesteatoma as a high signal sharply marginated mass (Left) Axial T1WI C+ MR in the same patient as the previous images shows both the lateral clival and mastoid components of a large temporal bone congenital cholesteatoma As in this case, nonenhancement would be expected (Right) Axial DWI MR in the same patient as the previous images shows high signal in the location of the giant temporal bone congenital cholesteatoma Restricted diffusion within the lesion is highly suggestive of the diagnosis of cholesteatoma Congenital Ossicular Fixation > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Congenital Lesions > Congenital Ossicular Fixation Congenital Ossicular Fixation H Ric Harnsberger, MD Key Facts Terminology Congenital ankylosis where rigid bar connects ossicle (usually malleus) to wall of middle ear Imaging Malleus > incus > stapes Bone CT findings High-density linear focus connecting ossicle to middle ear wall 1341 Diagnostic Imaging Head and Neck Ossicles otherwise normal in configuration Top Differential Diagnoses Tympanosclerosis involving ossicles Congenital external ear dysplasia Calcified stabilizing ligaments Ossicular fixation, post-traumatic Ossicular prosthesis Clinical Issues Congenital middle ear deafness Fixation restricts normal ossicular motion, causing conductive hearing loss Diagnostic Checklist Once ossicle fixation is identified, differentiate congenital & acquired causes Congenital ossicular fixation: Ossicle configuration normal; mastoid normally developed Congenital external ear dysplasia: Ossicles are fused; malleus annealed to lateral wall epitympanum; EAC abnormal Acquired fixation from tympanosclerosis: Calcified middle ear ligament or tendons; bony plaque connect middle ear wall to ossicle (Left) Axial bone CT shows bony bar between malleus head and lateral epitympanic wall Notice that there is no evidence of prior infection or trauma The mastoid air cells are normally developed, and no inflammatory debris is present (Right) Coronal bone CT in the same patient shows a bony bar between malleus head and lateral epitympanic wall The external auditory canal is normal (not shown), and there is no evidence of previous infection (Left) Axial bone CT in this patient with conductive hearing loss reveals bony ankylosis of the lateral margin of the short process of incus to lateral epitympanic wall (Right) Coronal bone CT in the same patient demonstrates the 1342 Diagnostic Imaging Head and Neck bony attachment of short process of incus and absence of inflammatory changes to lateral epitympanic wall Notice the normal external auditory canal Oval Window Atresia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Congenital Lesions > Oval Window Atresia Oval Window Atresia H Ric Harnsberger, MD Key Facts Terminology Absent cleavage plane (OW = stapes footplate + annular ligament) between lateral semicircular canal above & cochlear promontory below associated with anomalous stapes & malpositioned CN7 Imaging T-bone CT findings Normal OW replaced by ossific web Inferomedially positioned tympanic segment CN7 May completely overlie expected location of OW Critical surgical importance Best imaging tool: Multiplanar high-resolution temporal bone CT OW niche best seen in coronal plane Stapes crura best seen in axial plane Top Differential Diagnoses Tympanosclerosis Fenestral otosclerosis Congenital external ear dysplasia Pathology Best hypothesis: Primitive stapes fails to fuse with primitive vestibule during 7th week of gestation Clinical Issues Presentation Profound conductive hearing deficit in child Lack of history of otomastoiditis; normal EAC Treatment: Vestibulotomy with stapes prosthesis or total ossicular replacement prosthesis (TORP) CN7 ectopia into OW niche is relative surgical contraindication (Left) Coronal graphic illustrates features of oval window atresia, including dysplasia of stapes crura and footplate and tympanic segment of facial nerve abnormal location (Right) Coronal bone CT through the IAC demonstrates that the oval window is absent with bone density in its expected location The tympanic segment of the facial nerve is not in its expected location inferior to the horizontal SCC but instead overlies the atretic window The stapes is not seen 1343 Diagnostic Imaging Head and Neck (Left) Axial bone CT in this adolescent patient with conductive hearing loss shows deformed ossicles with angulation of the incus and anterior malleolar ligament calcification The oval window is bone covered with the tympanic segment of CN7 traversing its margin (Right) Coronal bone CT in the same patient reveals the bony plate within the oval window Notice the tympanic segment is present along the inferior margin of the oval window niche P.VI(3):9 TERMINOLOGY Abbreviations Oval window atresia (OWA) Synonyms Congenital absence of oval window (OW) Definitions Absent cleavage plane (OW = stapes footplate + annular ligament) between lateral semicircular canal above & cochlear promontory below associated with anomalous stapes & malpositioned CN7 IMAGING General Features Best diagnostic clue OW covered by thin bony plate on coronal bone CT CT Findings Bone CT Normal OW replaced by ossific web Malformed stapes superstructure (absence of normal paired crura) & distal incus Inferomedially positioned tympanic segment CN7 May completely overlie expected location of OW Critical surgical importance OW drill-out may be contraindicated if present Common associated finding (> 60%) Normal external auditory canal (EAC) Imaging Recommendations Best imaging tool Multiplanar high-resolution temporal bone CT OW niche best seen in coronal plane Stapes crura best seen in axial plane Protocol advice Thin section (< mm) axial & coronal T-bone CT Addition reformations for oval window, CN7, & stapes visualization Transverse & longitudinal obliques Custom oblique views as needed DIFFERENTIAL DIAGNOSIS 1344 Diagnostic Imaging Head and Neck Tympanosclerosis Clinical: Chronic otomastoiditis Imaging: Stapes may be thickened, including footplate Ossific deposits on ossicle surface may be seen Middle ear debris/sclerotic mastoid = chronic otomastoiditis Stapes & facial nerve are normal Fenestral Otosclerosis Clinical: Rare in childhood Imaging: Lucent lesions anterior to OW Obliterative variety (< 10%) results in similar appearance to OWA, but stapes & facial nerve are intrinsically normal Congenital External Ear Dysplasia Clinical: Microtia, EAC dysplasia Imaging: Variable EAC narrowing or absence Ossicle fusion, rotation; CN7 anomalous course OWA may be associated PATHOLOGY General Features Etiology Best hypothesis: Primitive stapes fails to fuse with primitive vestibule during 7th week of gestation If stapes forms but annular ligament does not, congenital stapes fixation results (instead of OWA) Caution: This may result in congenital conductive hearing loss in absence of imaging findings! Gross Pathologic & Surgical Features Tympanic segment of CN7 abnormal in most cases Inferomedially positioned Abnormal incus lenticular process associated Expected since distal incus & stapes superstructure are both formed from 2nd branchial arch CLINICAL ISSUES Presentation Most common signs/symptoms Profound conductive hearing deficit in child Lack of history of otomastoiditis; normal EAC Demographics Age Usually discovered in children Gender M>F Epidemiology OWA bilateral in ˜ 40% Natural History & Prognosis Surgery less successful than prosthetic stapedectomy for otosclerosis Treatment Vestibulotomy with stapes prosthesis or total ossicular replacement prosthesis (TORP) CN7 ectopia into OW niche is relative surgical contraindication DIAGNOSTIC CHECKLIST Consider Carefully inspect OW in children with congenital conductive deficit Image Interpretation Pearls Thickened bone over OW + inferomedially displaced tympanic CN7 = OWA SELECTED REFERENCES de Alarcon A et al: Congenital absence of the oval window: diagnosis, surgery, and audiometric outcomes Otol Neurotol 29(1):23-8, 2008 Booth TN et al: Imaging and clinical evaluation of isolated atresia of the oval window AJNR Am J Neuroradiol 21(1):171-4, 2000 Zeifer B et al: Congenital absence of the oval window: radiologic diagnosis and associated anomalies AJNR Am J Neuroradiol 21(2):322-7, 2000 1345 Diagnostic Imaging Head and Neck Lateralized Internal Carotid Artery > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Congenital Lesions > Lateralized Internal Carotid Artery Lateralized Internal Carotid Artery Christine M Glastonbury, MBBS Key Facts Terminology Lateralized internal carotid artery (Lat-ICA) Rare temporal bone vascular anomaly Unusual intratemporal course of ICA mimics aberrant ICA Imaging CTA best shows ICA entering anterior mesotympanum lateral to normal position ICA appears to be within anterior middle ear cavity Often has dehiscent lateral ICA wall also Coronal bone CT reveals nonenlarged inferior tympanic canaliculus On MIP projection CTA/MRA vessel contour mimics aberrant ICA Source images best for clarifying exact anomalous course of ICA through temporal bone Top Differential Diagnoses Aberrant ICA Glomus tympanicum paraganglioma Glomus jugulare paraganglioma ICA aneurysm of petrous apex Pathology Developmental anomaly Not associated with persistent stapedial artery Clinical Issues Often asymptomatic; incidental on CT or otoscopy Patient may present with pulsatile tinnitus Important finding to avoid inadvertent surgical injury Diagnostic Checklist Differentiate from aberrant ICA (Left) Axial CTA through level of left external auditory canal demonstrates lateral and posterior location of left ICA , which appears to course through middle ear cavity and is suspicious for aberrant ICA (Right) Coronal bone CT in the same patient reveals incursion of left internal carotid artery to hypotympanum and mesotympanum of anterior aspect of middle ear cavity, below cochlea and extending more lateral to cochlea than is normally found Bony lateral ICA wall is present 1346 Diagnostic Imaging Head and Neck (Left) Axial CTA at level of right external auditory canal shows enhancing right ICA in anterior aspect of middle ear There is marked thinning or dehiscence of overlying bone, so that the artery looks like enhancing nodule in mesotympanum (Right) MRA maximal intensity projection shows asymmetry of contour of internal carotid arteries with posterior genu (where ascending carotid turns to become petrous portion) on right side appearing more posterior & slightly lateral than on left P.VI(3):11 TERMINOLOGY Abbreviations Lateralized internal carotid artery (Lat-ICA) Definitions Anomalous intratemporal course of ICA Enters anterior mesotympanum Often has dehiscent lateral ICA bony wall IMAGING General Features Best diagnostic clue Temporal bone CT/CTA shows lateral course of ICA in mesotympanum Location ICA lies in anteromedial aspect of middle ear cavity as turns medially to petrous segment CT Findings Bone CT Bone CT shows protrusion of ICA into anterior aspect of middle ear Dehiscence usually near basal turn of cochlea Coronal T-bone CT shows laterally displaced ICA at level of cochlear promontory CTA Intermediate window/level setting shows course & contour of Lat-ICA projecting into middle ear Bone window shows lateral wall dehiscence MR Findings MRA On MIP projections, mimics aberrant ICA Source images show lateral position of genu of vertical & horizontal portions of petrous ICA Basilar projection reveals bulbous, posterolaterally placed petrous ICA Routine MR sequences Lat-ICA may be “invisible” because of low signal mastoid air and bone Imaging Recommendations Best imaging tool Temporal bone CT/CTA best show course and distinguish from aberrant ICA MRA source images key for clarification of anomalous course Protocol advice 1347 Diagnostic Imaging Head and Neck CTA most readily confirms diagnosis Carefully evaluate coronal and axial planes DIFFERENTIAL DIAGNOSIS Aberrant ICA ICA enters hypotympanum through enlarged inferior tympanic canaliculus Aberrant ICA then courses through middle ear across cochlear promontory Glomus Tympanicum Paraganglioma Focal mass on cochlear promontory No tubular shape; normal ICA on MRA/CTA Glomus Jugulare Paraganglioma Mass arising in jugular foramen & projecting superolaterally into middle ear Permeative-destructive bony changes on CT ICA Aneurysm of Petrous Apex Focal or fusiform expansion of petrous ICA canal MRA & CTA show focal vascular mass PATHOLOGY General Features Etiology Developmental variation No etiology known Associated abnormalities Lat-ICA appears to be isolated finding Not associated with persistent stapedial artery CLINICAL ISSUES Presentation Most common signs/symptoms Often asymptomatic; incidental finding on CT or otoscopy Patient may present for imaging with objective or subjective pulsatile tinnitus Demographics Epidemiology Rare temporal bone vascular lesion Natural History & Prognosis No long-term sequelae reported Treatment None; probably incidental developmental anomaly Important radiologic observation Inadvertent surgical vascular injury can result in significant neurologic deficits DIAGNOSTIC CHECKLIST Consider Must differentiate from aberrant ICA Lat-ICA does not enter middle ear through enlarged inferior tympanic canaliculus ICA does not course across cochlear promontory Important normal vascular variant to recognize & report to avoid surgical injury to ICA Image Interpretation Pearls Always check course of ICA on T-bone CT or CTA Always check integrity of lateral wall of temporal ICA SELECTED REFERENCES Pak MW et al: Lateralized carotid artery: an unusual cause of pulsatile tinnitus Ear Nose Throat J 80(3):148-9, 2001 Saada AA et al: Imaging quiz case Ectopic internal carotid artery (ICA) within the petrous temporal bone Arch Otolaryngol Head Neck Surg 122(7):792, 794, 1996 Sinnreich AI et al: Arterial malformations of the middle ear Otolaryngol Head Neck Surg 92(2):194-206, 1984 Aberrant Internal Carotid Artery > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Congenital Lesions > Aberrant Internal Carotid Artery Aberrant Internal Carotid Artery H Ric Harnsberger, MD Key Facts Terminology 1348 Diagnostic Imaging Head and Neck AbICA: Congenital vascular anomaly resulting from failure of formation of extracranial ICA with arterial collateral pathway Imaging Appearance of AbICA on thin section (< mm) temporal bone CT is diagnostic AbICA appears as tubular lesion crossing middle ear posterior to anterior Enlarged inferior tympanic canaliculus important observation Caveat: Do not mistake AbICA for glomus tympanicum paraganglioma! Top Differential Diagnoses Vascular middle ear lesion Glomus tympanicum paraganglioma Dehiscent jugular bulb Lateralized internal carotid artery Pathology Best explanation: “Alternative blood flow” theory Persistence of pharyngeal artery system means C1 portion of ICA absent Mature arterial collateral system compensates for absent C1 and vertical petrous ICA segments Ascending pharyngeal artery → inferior tympanic artery → caroticotympanic artery → posterolateral aspect of horizontal petrous ICA 30% of AbICA have persistent stapedial artery Clinical Issues Discovered at time of routine physical exam, during middle ear surgery, or as incidental imaging finding Associated symptoms: Pulsatile tinnitus and conductive hearing loss (Left) Axial graphic of the left temporal bone illustrates a classic AbICA rising along the posterior cochlear promontory and crossing along the medial middle ear wall to rejoin the horizontal petrous ICA At the point of reconnection, stenosis is often present (Right) Axial CTA image through the middle ear shows the looping aberrant internal carotid on the low cochlear promontory Note the caliber change as the AbICA rejoins the normal horizontal segment of the ICA 1349 Diagnostic Imaging Head and Neck (Left) Lateral graphic of adult suprahyoid and petrous ICA reveals the inferior tympanic artery branching off the ascending pharyngeal artery and passing into the T-bone to anastomose with the very small caroticotympanic artery on the cochlear promontory (Right) Lateral graphic depicts failure of the cervical ICA to develop (dotted lines) with the ascending pharyngeal , inferior tympanic , and caroticotympanic arteries, providing an alternative collateral arterial channel (AbICA) P.VI(3):13 TERMINOLOGY Abbreviations Aberrant internal carotid artery (AbICA) Synonyms Lateral internal carotid artery (ICA) Aberrant carotid artery Definitions Congenital vascular anomaly resulting from failure of formation of extracranial ICA with arterial collateral pathway IMAGING General Features Best diagnostic clue Tubular structure running horizontally through middle ear cavity from posterior to anterior Location Enters posterior middle ear through enlarged inferior tympanic canaliculus Posterior and lateral to expected site of petrous carotid canal Courses anteriorly across cochlear promontory to join horizontal petrous ICA through dehiscent carotid plate Size Smaller than horizontal petrous ICA Morphology Tubular morphology is key observation CT Findings CECT Enhancement equivalent to other arteries Caution: Glomus tympanicum paraganglioma also enhances Use morphology to differentiate tubular AbICA from ovoid paraganglioma Bone CT Appearance of AbICA on thin section (< mm) temporal bone CT is diagnostic Axial bone CT AbICA appears as tubular lesion crossing middle ear posterior to anterior Enlarged inferior tympanic canaliculus is important observation Anteromedial to stylomastoid foramen and mastoid segment of facial nerve 1350 Diagnostic Imaging Head and Neck Smaller AbICA often stenotic at point of reconnection with horizontal petrous ICA Carotid foramen and vertical segment of petrous ICA are absent Coronal bone CT AbICA appears as round, soft tissue lesion on cochlear promontory Single slice looks disturbingly like glomus tympanicum paraganglioma Caveat: Do not mistake AbICA for glomus tympanicum paraganglioma! Tubular nature of AbICA is key observation Inferior tympanic canaliculus is vertical tube posterolateral to normal location of vertical segment of petrous ICA Rises at coronal level of round window niche If persistent stapedial artery associated Absent foramen spinosum Enlarged anterior tympanic segment of CN7 canal CTA Diagnostic for AbICA Usually not necessary as CT alone is diagnostic MR Findings Conventional MR does not reliably identify AbICA Low signal of bone is difficult to distinguish from low signal of arterial flow void MRA source and reformatted images show aberrant nature of vessel AbICA enters skull base posterior and lateral, compared to normal contralateral side Frontal reformat: Petrous segment of ICA extends laterally instead of medially In left ear, AbICA looks like “7” In right ear, AbICA looks like “reverse 7” Angiographic Findings Frontal view: Petrous segment of ICA extends laterally instead of medially Lateral view: Absent extracranial course of suprabifurcation ICA (C1 segment) Smaller caliber vessels rises from bifurcation posteriorly, looping back to horizontal segment of petrous ICA Stenosis may be present at site of reconnection between AbICA and horizontal petrous ICA Conventional angiography no longer necessary to confirm imaging diagnosis CTA or MRA sufficient if uncertainty arises from bone CT images Imaging Recommendations Best imaging tool T-bone CT: Tubular morphology and posterolateral position diagnostic Contrast CT not necessary Protocol advice Bone CT: < mm axial and coronal images if possible If MR is used, MRA is critical component DIFFERENTIAL DIAGNOSIS Glomus Tympanicum Paraganglioma Otoscopy: Rose-colored, pulsatile, retrotympanic mass Bone CT: Focal ovoid mass on cochlear promontory MR: T1WI C+ enhancing mass Lateralized Internal Carotid Artery Otoscopy: Vague, vascular hue deep behind tympanic membrane Bone CT: Dehiscent lateral wall of petrous ICA genu Aneurysm, Petrous Internal Carotid Artery Otoscopy: Negative unless large Bone CT: Focal, smooth, petrous ICA canal expansion P.VI(3):14 ICA has normal course but focal ovoid, expansile section MR: MRA is diagnostic of nonthrombosed aneurysm Dehiscent Jugular Bulb Otoscopy: Gray-blue retrotympanic mass in posteroinferior quadrant Bone CT: Focal absence of sigmoid plate “Bud” from superolateral jugular bulb enters middle ear as “mass” 1351 Diagnostic Imaging Head and Neck Cholesterol Granuloma, Middle Ear Otoscopy: Blue-black retrotympanic mass Bone CT: Appears identical to acquired cholesteatoma MR: High signal on T1 without contrast suggests diagnosis PATHOLOGY General Features Etiology Etiology of AbICA is controversial Best explanation: “Alternative blood flow” theory Persistence of pharyngeal artery system means C1 portion of ICA is absent Mature arterial collateral system compensates for absent C1 and vertical petrous ICA segments Ascending pharyngeal artery → inferior tympanic artery → caroticotympanic artery → posterolateral aspect of horizontal petrous ICA Results of absent extracranial ICA C1 segment Ascending pharyngeal, inferior tympanic, and caroticotympanic arteries enlarge Inferior tympanic canaliculus enlarges to accommodate enlarged inferior tympanic artery Bony margin of posterolateral horizontal petrous ICA canal is penetrated at site of caroticotympanic artery origin Associated abnormalities 30% of AbICA have persistent stapedial artery Enlarged anterior tympanic segment of CN7 canal Absent ipsilateral foramen spinosum Gross Pathologic & Surgical Features Pulsatile aberrant artery is found in middle ear cavity Microscopic Features Histologically normal artery CLINICAL ISSUES Presentation Most common signs/symptoms Most commonly asymptomatic Discovered at time of routine physical exam, during middle ear surgery, or as incidental imaging finding Associated symptoms Pulsatile tinnitus (PT) (pulse-synchronous sound) May be subjective (only patient hears) or objective (patient and MD hear) Objective PT: When stenosis present at junction of AbICA and normal horizontal petrous ICA Subjective PT: Pulsatile sound may transmit directly through cochlear promontory to basal turn of cochlea Conductive hearing loss Otoscopy: Retrotympanic pink-red mass Inferior aspect of tympanic membrane May mimic paraganglioma Demographics Age Average at presentation: 38 years Gender M < F in single study (N = 16) Epidemiology Very rare disorder Natural History & Prognosis No long-term sequelae reported with AbICA Poor prognosis results only if misdiagnosis → biopsy Pseudoaneurysm may require endovascular repair If tinnitus is loud, AbICA can be debilitating Treatment No treatment is best treatment Greatest risk is misdiagnosis leading to biopsy DIAGNOSTIC CHECKLIST 1352 Diagnostic Imaging Head and Neck Image Interpretation Pearls Radiologist must remain firm on imaging diagnosis despite clinical impression of paraganglioma Biopsy or attempted resection of misdiagnosed AbICA can be disastrous Hemorrhage, stroke, or death may result from vessel injury Reporting Tips Report diagnosis; offer no differential diagnosis Equivocal report such as “cannot exclude paraganglioma” may lead to surgical intervention SELECTED REFERENCES Sauvaget E et al: Aberrant internal carotid artery in the temporal bone: imaging findings and management Arch Otolaryngol Head Neck Surg 132(1):86-91, 2006 Windfuhr JP: Aberrant internal carotid artery in the middle ear Ann Otol Rhinol Laryngol Suppl 192:1-16, 2004 Kojima H et al: Aberrant carotid artery in the middle ear: multislice CT imaging aids in diagnosis Am J Otolaryngol 24(2): 92-6, 2003 Roll JD et al: Bilateral aberrant internal carotid arteries with bilateral persistent stapedial arteries and bilateral duplicated internal carotid arteries AJNR Am J Neuroradiol 24(4):762-5, 2003 Jain R et al: Management of aberrant internal carotid artery injury: a real emergency Otolaryngol Head Neck Surg 127(5): 470-3, 2002 Davis WL et al: MR angiography of an aberrant internal carotid artery AJNR Am J Neuroradiol 12(6):1225, 1991 Lo WW et al: Aberrant carotid artery: radiologic diagnosis with emphasis on high-resolution computed tomography Radiographics 5(6):985-93, 1985 P.VI(3):15 Image Gallery (Left) Axial bone CT of the left ear shows a larger caliber AbICA entering the posteromedial middle ear cavity , looping anteriorly across the low cochlear promontory to reconnect to the horizontal petrous ICA CN7 mastoid segment is posterolateral to AbICA (Right) Axial bone CT reveals a smaller caliber AbICA entering the middle ear cavity through enlarged inferior tympanic canaliculus , coursing across middle ear on cochlear promontory, and reentering the horizontal petrous ICA 1353 Diagnostic Imaging Head and Neck (Left) Coronal bone CT of the left ear shows the posterior aspect of an AbICA with its enlarged inferior tympanic canaliculus and looping course up onto the cochlear promontory The tubular configuration of the vessel should prevent misdiagnosis (Right) Coronal left T-bone CT at the level of the oval window shows the AbICA as a “mass” located on the cochlear promontory resembling a glomus tympanicum paraganglioma Accidental biopsy of AbICA may have devastating consequences! (Left) Sagittal oblique MRA reveals an AbICA with significant stenosis at the junction where the AbICA rejoins the horizontal petrous ICA Notice the characteristic “7” shape to this left AbICA (Right) Lateral internal carotid angiography of an AbICA reveals that the normal extracranial ICA is replaced by an enlarged collateral circuit including the ascending pharyngeal , inferior tympanic , and caroticotympanic arteries Note the caliber change from AbICA to horizontal petrous ICA Persistent Stapedial Artery > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Congenital Lesions > Persistent Stapedial Artery Persistent Stapedial Artery H Ric Harnsberger, MD Key Facts Terminology PSA definition: Rare congenital vascular anomaly in which embryological stapedial artery persists Imaging Temporal bone CT findings Enlargement of anterior tympanic segment of facial nerve canal 1354 Diagnostic Imaging Head and Neck Absent foramen spinosum Top Differential Diagnoses Facial nerve hemangioma Facial nerve schwannoma Perineural parotid malignancy in CN7 canal Bell palsy (herpetic facial neuritis) Pathology Embryology-anatomy Primitive 2nd aortic arch gives rise to hyoid artery Hyoid artery gives rise to stapedial artery Stapedial artery divides into dorsal (middle meningeal artery) & ventral divisions (to maxilla & mandible) PSA courses from infracochlear ICA through stapedial obturator foramen PSA enlarges tympanic CN7 canal on its way to middle cranial fossa PSA becomes middle meningeal artery Clinical Issues Asymptomatic on T-bone CT or during surgery No treatment is best treatment Diagnostic Checklist If AbICA discovered, look for associated PSA Large anterior tympanic CN7 + absent foramen spinosum = persistent stapedial artery (Left) Lateral graphic shows persistent stapedial artery (PSA) arising from vertical segment of petrous internal carotid artery , passing through stapes and traveling along tympanic segment of facial nerve to become middle meningeal artery (Right) Lateral graphic shows PSA arising from aberrant internal carotid artery , passing through stapes, to follow anterior tympanic facial nerve segment Intracranially the PSA becomes middle meningeal artery 1355 Diagnostic Imaging Head and Neck (Left) Axial right ear bone CT reveals an enlarged anterior tympanic segment of the intratemporal facial nerve (Right) Coronal bone CT of the right ear in the same patient demonstrates the persistent stapedial artery rising from its take-off origin from the genu of the petrous internal carotid artery , ascending on the cochlear promontory , passing through the crura of the stapes on its way to join the mid-tympanic segment of the facial nerve canal (Courtesy K Funk, MD.) P.VI(3):17 TERMINOLOGY Abbreviations Persistent stapedial artery (PSA) Definitions Rare congenital vascular anomaly in which embryological stapedial artery persists IMAGING General Features Best diagnostic clue Enlargement of anterior tympanic segment CN7 canal + absent foramen spinosum Location PSA passes through stapes footplate Size Doubles size of anterior CN7 tympanic segment CT Findings Bone CT Absent ipsilateral foramen spinosum Enlargement of anterior tympanic segment of CN7 canal Separate parallel canal possible Curvilinear structure crossing medial wall of middle ear cavity over cochlear promontory Small canaliculus leaving carotid canal PSA seen with or without aberrant internal carotid artery (AbICA) CTA Shows absence of normal middle meningeal artery PSA arising from genu of vertical & horizontal petrous ICA Imaging Recommendations Best imaging tool Axial & coronal temporal bone CT DIFFERENTIAL DIAGNOSIS Facial Nerve Hemangioma Bone CT: Intratumoral ossification (50%) T1 C+ MR: Enhancing mass in geniculate fossa Facial Nerve Schwannoma Bone CT: Tubular or focal enlargement of CN7 canal 1356 Diagnostic Imaging Head and Neck T1 C+ MR: Mass enhancing in CN7 canal Perineural Parotid Malignancy, Mastoid CN7 Bone CT: Enlarged mastoid segment of CN7 canal T1 C+ MR: Enhancing tumor coming up from parotid Bell Palsy (Herpetic Facial Neuritis) Bone CT: Normal T1 C+ MR: Entire intratemporal CN7 enhances PATHOLOGY General Features Etiology Stapedial artery fails to involute in 3rd fetal month Associated abnormalities Aberrant internal carotid artery Trisomy 13, 15, & 21 Paget disease, otosclerosis, anencephaly, neurofibromatosis Embryology-anatomy Primitive 2nd aortic arch gives rise to hyoid artery Hyoid artery gives rise to stapedial artery Stapedial artery divides into dorsal (middle meningeal artery) & ventral components (to maxilla & mandible) PSA courses from infracochlear ICA through stapedial obturator foramen PSA enlarges tympanic CN7 canal on its way to middle cranial fossa PSA becomes middle meningeal artery Gross Pathologic & Surgical Features Otoendoscopy shows PSA passing through stapes CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic on T-bone CT or during surgery Rarely presents with tinnitus ± pulsatile retrotympanic red mass Demographics Age Congenital, may be discovered at any age Epidemiology Very rare lesion Natural History & Prognosis Excellent; just needs to be left alone Treatment No treatment is best treatment If presumed cause of pulsatile tinnitus, surgical ligation or endovascular occlusion may be considered Only in severe, intractable pulsatile tinnitus PSA surgical implications Can complicate stapedectomy or cholesteatoma resection May prevent cochlear implantation DIAGNOSTIC CHECKLIST Consider If AbICA discovered, look for associated PSA Image Interpretation Pearls Large anterior tympanic CN7 + absent foramen spinosum = PSA SELECTED REFERENCES Saini J et al: Aberrant petrous internal carotid artery with cochlear anomaly-an unusual association Surg Radiol Anat 30(5):453-7, 2008 Koesling S et al: Vascular anomalies, sutures and small canals of the temporal bone on axial CT Eur J Radiol 54(3):335-43, 2005 Yilmaz T et al: Persistent stapedial artery: MR angiographic and CT findings AJNR Am J Neuroradiol 24(6):1133-5, 2003 1357 Diagnostic Imaging Head and Neck Infectious and Inflammatory Lesions Acute Otomastoiditis with Abscess > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Infectious and Inflammatory Lesions > Acute Otomastoiditis with Abscess Acute Otomastoiditis with Abscess H Ric Harnsberger, MD Key Facts Terminology Acute coalescent otomastoiditis (ACOM) ACOM definition: Acute middle ear-mastoid infection with progressive resorption & demineralization due to intramastoid empyema Imaging Bone CT findings: Mastoid cortex ± trabecula erosions (confluent mastoiditis) CECT or enhanced MR findings Subperiosteal abscess: Periauricular fluid collection Bezold abscess: Walled-off pus in & around sternocleidomastoid muscles Middle cranial fossa abscess (epidural or temporal lobe abscess) Posterior fossa abscess (epidural or cerebellar abscess) Top Differential Diagnoses Acquired cholesteatoma Apical petrositis Temporal bone Langerhans histiocytosis Temporal bone rhabdomyosarcoma Pathology Common pathophysiology Granulation tissue or cholesteatoma block aditus ad antrum & prevent mastoid air cell drainage Less common pathophysiology Mastoid cortex remains intact with septic thrombophlebitis of emissary veins seeding periosteum Clinical Issues Young child with day to week history otalgia, post-auricular swelling, fever, & otorrhea (Left) Axial CECT in a patient with post-auricular tender mass with headache and fever reveals post-auricular abscess , confluent mastoiditis , and nonthrombosed transverse sinus (Right) Axial bone CT in the same patient demonstrates the loss of mastoid trabecula along with a dehiscent sigmoid plate diagnostic of confluent mastoiditis A subtle gap in the lateral mastoid cortex indicates the site where the mastoid pus communicates with the post-auricular abscess 1358 Diagnostic Imaging Head and Neck (Left) Axial CECT in a child with ear pain and decreased consciousness shows an epidural abscess adjacent to the mastoid air cells in the posterior fossa (Right) Axial bone CT in the same patient reveals complete opacification of the middle ear and mastoid Note intact medial bony wall of the mastoid and absence of confluent mastoiditis Emissary veins may provide a route of spread from acute otomastoiditis to the intracranial compartment Epidural abscess found at surgery P.VI(3):19 TERMINOLOGY Abbreviations Acute coalescent otomastoiditis (ACOM) Acute otomastoiditis (AOM) Synonyms Coalescent otomastoiditis with abscess Definitions AOM: Active infection in middle ear-mastoid without destruction of mastoid septations or cortex ACOM: Acute middle ear-mastoid infection with progressive resorption & demineralization due to intramastoid empyema ACOM + abscess: Coalescent mastoiditis with resultant intracranial or extracranial abscess IMAGING General Features Best diagnostic clue Rim-enhancing fluid collection adjacent to eroded mastoid cortex + mastoid air cell opacification Location Abscess location depends on direction of mastoid cortical dehiscence Lateral mastoid wall Post-auricular (cortical bone thin here) abscess Pre- or periauricular abscess Inferior mastoid wall Mastoid tip → Bezold abscess Other remaining inferior mastoid cortical dehiscence → trans-spatial abscess Tegmen mastoideum → temporal lobe abscess Medial mastoid wall → epidural abscess, posterior fossa Size Variable; usually presents with > cm fluid pocket Morphology Crescentic, lentiform, or spherical CT Findings CECT Subperiosteal abscess: Periauricular fluid collection Thick, enhancing lateral wall represents inflamed periosteum 1359 Diagnostic Imaging Head and Neck Bezold abscess: Walled-off pus in & around sternocleidomastoid muscles Middle cranial fossa abscess (epidural or temporal lobe abscess) Epidural or intratemporal lobe rim-enhancing fluid Posterior fossa abscess (epidural or cerebellar abscess) Epidural or intracerebellar rim-enhancing fluid Bone CT Middle ear-mastoid opacification Variable trabecular & cortical erosions (CT sign of confluent disease) Subtle to gross focus of dehiscent cortex just deep to area of abscess Lateral mastoid cortex → subperiosteal abscess Mastoid tip cortex → Bezold abscess Tegmen mastoideum cortex → epidural or temporal lobe abscess Medial mastoid cortex → epidural or cerebellar abscess CTV May show dural sinus thrombosis MR Findings T2WI High signal fills middle ear-mastoid High signal fluid in epidural or parenchymal abscess DWI Restricted diffusion in abscess T1WI C+ Variably enhancement of middle ear-mastoid Rim-enhancing pus in subperiosteal, epidural, or parenchymal brain abscess MRV May show dural sinus thrombosis (DST) Imaging Recommendations Best imaging tool Temporal bone CT defines bony changes (confluence, cortical dehiscence) CECT will define most infectious complications Enhanced temporal bone MR more sensitive for intracranial complications (DST, meningitis, subdural empyema, abscess) Protocol advice Keep section thickness small (≤ mm) for enhanced MR DIFFERENTIAL DIAGNOSIS Acquired Cholesteatoma Clinical: Retraction or rupture of tympanic membrane; may be superinfected Imaging: CT shows erosive mass with poor enhancement When associated with ACOM, may also cause extracranial or intracranial abscess Apical Petrositis Clinical: CN6 palsy, retroauricular pain, AOM Imaging: CT shows coalescent changes in petrous apex T1WI C+ MR shows enhancing meninges & focal walled-off fluid in petrous apex Usually no associated intracranial abscess Temporal Bone Langerhans Histiocytosis Clinical: Child with draining ear & periauricular mass Imaging: Extensive, often bilateral, mastoid destruction with enhancing soft tissue Temporal Bone Rhabdomyosarcoma Clinical: Neurologic deficits common, including CN7 palsy Imaging: CT shows extensive bone destruction; intracranial extension T1WI C+ MR shows enhancing soft tissue mass emanating from middle ear P.VI(3):20 PATHOLOGY General Features Etiology Inflammation, granulation tissue, or cholesteatoma block aditus ad antrum & prevent mastoid air cell drainage 1360 Diagnostic Imaging Head and Neck Local hyperemia-acidosis creates enzymatic resorption of trabeculae (confluent mastoiditis) Cortical subtle or gross dehiscence conveys infection into adjacent tissues Less common pathophysiology: Mastoid cortex remains intact with septic thrombophlebitis of emissary veins seeding periosteum Macewen triangle Surgical access point to mastoid antrum at posterosuperior EAC Weakest bone-loose periosteum allow breakout of infection in post-auricular location Gross Pathologic & Surgical Features Pus in mastoid, adjacent abscess cavity Granulation tissue or cholesteatoma occasionally identified in middle ear-mastoid More common in subacute-chronic disease Requires more extensive surgery Microscopic Features Polymicrobial aerobes & anaerobes Streptococcus species common CLINICAL ISSUES Presentation Most common signs/symptoms Otalgia (ear pain) Other signs/symptoms Fever Otorrhea (ear drainage) Post-auricular pain & swelling Lateralized auricle (ear pushed outward by abscess) Conductive > sensorineural hearing loss ↑ WBC, ↑ ESR Clinical profile Young child with day to week history otalgia, post-auricular swelling, fever, & otorrhea 35-70% of patients already received antibiotics for AOM Post-auricular edema (Griesinger sign) common in uncomplicated acute mastoiditis (85%) Enhancing fluid collection needed to confirm subperiosteal abscess Demographics Age Infants & young children If complication of acquired cholesteatoma, often older age group affected Epidemiology 46% of children have > episodes AOM by age 0.24% of patients with AOM develop ACOM Socio-economic Lower income, malnourished children have ↑ risk of abscess after AOM Natural History & Prognosis Isolated extracranial subperiosteal abscess Excellent prognosis with prompt therapy Worse if prior incomplete antibiotic therapy, virulent organism, or immunocompromised host Intracranial abscess (temporal lobe most common) Worse prognosis If concomitant complications, even worse prognosis Venous sinus thrombosis Epidural abscess or subdural empyema Treatment Intravenous antibiotics ± tympanocentesis with myringotomy tube placement Surgical treatment Incision & drainage (I & D) of extracranial subperiosteal abscess with cortical mastoidectomy Surgical therapy must be performed with hearing preservation in mind Radical mastoidectomy if cholesteatoma present DIAGNOSTIC CHECKLIST Consider Seek other complications of ACOM Temporal bone findings (T1 C+ MR) 1361 Diagnostic Imaging Head and Neck Facial nerve paralysis shows as enhancing CN7 Labyrinthitis shows as enhancement within membranous labyrinth Apical petrositis (enhancing apical air cells on MR) Intracranial findings (T1 C+ MR) Epidural or brain abscess Subdural empyema, meningitis ± DST Image Interpretation Pearls ACOM usually manifests after AOM resolves SELECTED REFERENCES Zevallos JP et al: Advanced pediatric mastoiditis with and without intracranial complications Laryngoscope 119(8):1610-5, 2009 Park H et al: Surgical management of acute mastoiditis with epidural abscess Acta Otolaryngol 126(7):782-4, 2006 Taylor MF et al: Indications for mastoidectomy in acute mastoiditis in children Ann Otol Rhinol Laryngol 113(1):6972, 2004 Migirov L: Computed tomographic versus surgical findings in complicated acute otomastoiditis Ann Otol Rhinol Laryngol 112(8):675-7, 2003 Vazquez E et al: Imaging of complications of acute mastoiditis in children Radiographics 23(2):359-72, 2003 Tarantino V et al: Acute mastoiditis: a 10 year retrospective study Int J Pediatr Otorhinolaryngol 66(2):143-8, 2002 Antonelli PJ et al: Computed tomography and the diagnosis of coalescent mastoiditis Otolaryngol Head Neck Surg 120(3):350-4, 1999 Spiegel JH et al: Contemporary presentation and management of a spectrum of mastoid abscesses Laryngoscope 108(6):822-8, 1998 Mafee MF et al: Acute otomastoiditis and its complications: role of CT Radiology 155(2):391-7, 1985 P.VI(3):21 Image Gallery (Left) Coronal T1 enhanced fat-saturated MR reveals mastoid enhancement with a large periauricular abscess Lateral mastoid is focally dehiscent with proximal meninges thick and enhancing Subjacent skull base enhances , indicating extensive associated osteomyelitis (Right) Axial DWI in the same patient reveals restricted diffusion within the extensive periauricular abscess (Courtesy N Fischbein, MD.) 1362 Diagnostic Imaging Head and Neck (Left) Axial T1 enhanced MR in an adult with decreased consciousness and fever demonstrates a bilobed, ring enhancing temporal lobe abscess , along with meningeal enhancement secondary to meningitis (Right) Coronal T1 enhanced MR in the same patient reveals acute otomastoiditis with a confluent area of suppuration A direct connection between the mastoid abscess and the temporal lobe abscess is seen with associated meningitis (Left) Axial bone CT in a child with mastoid tenderness, fever, and a posterior neck mass shows right mastoid trabecular breakdown , indicating acute confluent otomastoiditis Note also the focal lateral mastoid cortex dehiscence (Right) Axial CECT in the same patient shows a large trans-spatial abscess posteroinferior to the mastoid tip resulting from spreading infection from acute confluent otomastoiditis The rent in the lateral mastoid cortex provided an escape route for the pus Coalescent Otomastoiditis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Infectious and Inflammatory Lesions > Coalescent Otomastoiditis Coalescent Otomastoiditis H Ric Harnsberger, MD Key Facts Terminology Acute infection of middle ear-mastoid air cells with progressive resorption & demineralization of mastoid septae ± mastoid cortex Due to edema-local acidosis with development of intramastoid empyema Imaging 1363 Diagnostic Imaging Head and Neck CT findings Opacification of middle ear & mastoid air cells Focal destruction of mastoid septations ± cortex MR findings Diffuse C+ of inflammatory debris Focal nonenhancing pus pockets Top Differential Diagnoses Acute uncomplicated otomastoiditis Chronic otitis media T-bone Langerhans cell histiocytosis T-bone rhabdomyosarcoma Pathology Prolonged infection creates hyperemia, venous stasis, & ↑ osteoclastic activity Suppuration under pressure causes local acidosis, decalcification, ischemia, & osteoclastic activity Clinical Issues Symptoms & signs Otalgia & spiking fevers Treatment Acute otitis media: Antibiotics with no imaging required Acute confluent otomastoiditis: Prolonged IV antibiotics; mastoidectomy often required (Left) Axial right ear bone CT in a patient with otalgia and fever reveals a large area of coalescent mastoid air cells Associated medial mastoid cortex dehiscence puts patient at risk for epidural abscess or sigmoid sinus thrombosis (Right) Axial right ear bone CT shows middle ear and mastoid air cell opacification Anterolaterally there is a focal area of coalescence associated with lateral and medial cortical dehiscence Either pre-auricular or epidural abscess may result 1364 Diagnostic Imaging Head and Neck (Left) Coronal bone CT of posterior mastoid reveals diffuse mastoid air cell opacification from otomastoiditis An early area of confluence is visible associated with medial mastoid wall cortical dehiscence (Right) Axial T1WI C+ MR in the same patient shows heterogeneous enhancement of the middle ear & mastoid Focal area of mastoid trabecular dehiscence on CT is seen as low signal pus Cortical dehiscence is present medially Enhancing meninges indicates associated meningitis P.VI(3):23 TERMINOLOGY Abbreviations Acute coalescent otomastoiditis (ACOM) Acute otomastoiditis or acute otitis media (AOM) Synonyms Erosive otomastoiditis, coalescent otomastoiditis Definitions Acute infection of middle ear-mastoid air cells with progressive resorption & demineralization of mastoid septae ± mastoid cortex Due to edema-local acidosis with development of intramastoid empyema IMAGING General Features Best diagnostic clue Erosion of mastoid septations is most specific CT finding distinguishing coalescent from noncoalescent AOM Location Middle ear, mastoid, petrous apex CT Findings CECT Enhancement of inflammatory debris within middle ear & mastoid Bone CT Opacification of middle ear & mastoid air cells Focal destruction of mastoid septations ± cortex MR Findings T1WI Isointense debris within middle ear-mastoid (MEM) T2WI Hyperintense debris within MEM Trabecular loss & cortical dehiscence T1WI C+ Diffuse C+ of inflammatory debris within MEM Focal nonenhancing pus pockets Imaging Recommendations 1365 Diagnostic Imaging Head and Neck Best imaging tool T-bone CT makes this diagnosis Comparison to opposite side is crucial Enhanced MR for regional complications Always include MRA and MRV DIFFERENTIAL DIAGNOSIS Acute Uncomplicated Otomastoiditis Clinical: Painful inflamed ear CT: Opacified middle ear & mastoid only Chronic Otitis Media Clinical: Longstanding, recurrent infections CT: Partial opacification middle ear-mastoid Mastoid trabecula intact T-Bone Langerhans Cell Histiocytosis CT: Significant bone destruction usually present T1WI C+ MR: Enhancing mass + bone destruction T-Bone Rhabdomyosarcoma CT: Bone destruction usually present T1WI C+ MR: Enhancing mass + bone destruction PATHOLOGY General Features Etiology Prolonged infection creates hyperemia, venous stasis, & ↑ osteoclastic activity Suppuration under pressure causes local acidosis, decalcification, ischemia, & osteoclastic activity Gross Pathologic & Surgical Features Soft osteomyelitic bone with pus-filling confluent mastoid air cells CLINICAL ISSUES Presentation Most common signs/symptoms Otalgia & spiking fevers Demographics Age Most aggressive cases in children Epidemiology Rare complication of AOM Natural History & Prognosis With failure to control AOM with antibiotics, infection invades bone (ACOM) Treatment Acute otitis media Treated with antibiotics with no imaging required Myringotomy when severe Acute confluent otomastoiditis Mastoidectomy needed more often DIAGNOSTIC CHECKLIST Consider ACOM difficult to distinguish clinically or by imaging from rhabdomyosarcoma or Langerhans cell histiocytosis Usually these cause more destruction & have more associated mass than with ACOM Image Interpretation Pearls Carefully examine mastoid septations on CT & compare to opposite side Beware of overcalling otomastoiditis with asymmetric mastoid air cell size as ACOM SELECTED REFERENCES Zanetti D et al: Indications for surgery in acute mastoiditis and their complications in children Int J Pediatr Otorhinolaryngol 70(7):1175-82, 2006 Migirov L: Computed tomographic versus surgical findings in complicated acute otomastoiditis Ann Otol Rhinol Laryngol 112(8):675-7, 2003 Vazquez E et al: Imaging of complications of acute mastoiditis in children Radiographics 23(2):359-72, 2003 1366 Diagnostic Imaging Head and Neck Chronic Otomastoiditis with Ossicular Erosions > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Infectious and Inflammatory Lesions > Chronic Otomastoiditis with Ossicular Erosions Chronic Otomastoiditis with Ossicular Erosions H Ric Harnsberger, MD Key Facts Terminology Erosive changes involving ossicles in absence of cholesteatoma in patient with history of COM Imaging Axial bone CT Absence of part of posterior line of normal “2 parallel lines” Incudostapedial joint (ISJ) may be replaced by fibrous tissue ISJ appears widened on axial CT Erosion of cone (incus body/short process) also occurs Coronal bone CT Long process of incus most commonly absent Vertical segment of “right angle” missing Tympanic membrane retraction often present Top Differential Diagnoses Mild congenital external ear dysplasia Acquired cholesteatoma + ossicular erosion Congenital middle ear cholesteatoma + ossicle erosion Postoperative ossicular loss Post-traumatic ossicular dislocation Clinical Issues Clinical presentation Post-inflammatory conductive hearing loss Usually long history of chronic otitis media Primary treatment: Surgical Exploratory tympanotomy with ossicular reconstruction (Left) Coronal graphic of left ear shows postinflammatory ossicular erosion of incus long process and stapes hub Note the changes of tympanosclerosis of tympanic membrane and remaining ossicles (Right) Coronal bone CT reveals retraction of a thickened tympanic membrane with demineralization of long process of incus Stranding soft tissue in the middle ear is associated inflammatory debris 1367 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a normal right short process of the incus and head of malleus Notice the wellpneumatized mastoid (Right) Axial bone CT of the left ear in the same patient with a history of chronic otitis media demonstrates deossification of the left short process of the incus The head of the malleus is normal in density and size The mastoid is underpneumatized from otomastoiditis during mastoid formation P.VI(3):25 TERMINOLOGY Abbreviations Chronic otomastoiditis (COM) Synonyms Noncholesteatomatous ossicular erosion; post-inflammatory ossicular erosion Definitions Erosive changes involving ossicles in absence of cholesteatoma in patient with history of COM IMAGING CT Findings Bone CT Anatomy of ossicular chain necessary to make imaging diagnosis Axial CT/epitympanum: “Ice cream cone” (anterior “ice cream” = malleus head; posterior “cone” = incus body/short process) Axial CT/mesotympanum: “2 parallel lines” (anterior line = tensor tympani tendon leading to malleus neck; posterior line = incus lenticular process, incudostapedial joint, & stapes head) Coronal CT through long process incus: Ossicular “right angle” (vertically oriented incus long process; horizontally oriented incus lenticular process) Axial bone CT images Absence of part of posterior line of normal “2 parallel lines” Incudostapedial joint (ISJ) may be replaced by fibrous tissue ISJ appears widened on axial CT Erosion of “cone” (incus body/short process) also occurs Coronal bone CT images Long process of incus most commonly absent Vertical segment of “right angle” missing Tympanic membrane retraction often present Mastoid underpneumatization common Imaging Recommendations Best imaging tool Axial & coronal T-bone CT DIFFERENTIAL DIAGNOSIS Mild Congenital External Ear Dysplasia Pediatric hearing loss; microtia CT: Rotation ± fusion of ossicles 1368 Diagnostic Imaging Head and Neck Acquired Cholesteatoma + Ossicular Erosion CT: Nondependent soft tissue mass is associated Perforated or retracted tympanic membrane Congenital Middle Ear Cholesteatoma + Ossicle Erosion CT: Soft tissue usually medial to ossicles Focal ossicular erosion associated Postoperative Ossicular Loss Evidence for mastoidectomy CT: Stapedectomy for otosclerosis most commonly Post-Traumatic Ossicular Dislocation Fractured, dislocated ossicle may appear absent PATHOLOGY General Features Etiology COM initiates ossicular loss Initial phase: Periostitis & osteitis Subsequent osteoclasia & decalcification creates bone loss Incus is most vulnerable portion of ossicular chain due to tenuous blood supply CLINICAL ISSUES Presentation Most common signs/symptoms Postinflammatory conductive hearing loss Usually long history of chronic otitis media Demographics Epidemiology Very common clinical & CT entity Natural History & Prognosis Surgical repair results variable Relates to severity of ossicular loss & associated tympanic membrane status Treatment Exploratory tympanotomy with ossicular reconstruction as needed DIAGNOSTIC CHECKLIST Consider In patients with conductive hearing loss Look for ossicle loss with COM Then consider other diagnoses Fenestral otosclerosis Congenital ossicular deformity in mild EAC dysplasia Image Interpretation Pearls Absence of segment of ossicular chain Common CT finding; usually overlooked SELECTED REFERENCES Pandey AK et al: Is there a role for virtual otoscopy in the preoperative assessment of the ossicular chain in chronic suppurative otitis media? Comparison of HRCT and virtual otoscopy with surgical findings Eur Radiol 19(6):1408-16, 2009 Carrillo RJ et al: Probabilities of ossicular discontinuity in chronic suppurative otitis media using pure-tone audiometry Otol Neurotol 28(8):1034-7, 2007 Jeng FC et al: Relationship of preoperative findings and ossicular discontinuity in chronic otitis media Otol Neurotol 24(1):29-32, 2003 Lemmerling MM et al: Normal and opacified middle ears: CT appearance of the stapes and incudostapedial joint Radiology 203(1):251-6, 1997 Chronic Otomastoiditis with Tympanosclerosis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Infectious and Inflammatory Lesions > Chronic Otomastoiditis with Tympanosclerosis Chronic Otomastoiditis with Tympanosclerosis H Ric Harnsberger, MD Key Facts Terminology 1369 Diagnostic Imaging Head and Neck Definition: Calcific, bony, or fibrous middle ear foci secondary to suppurative COM Imaging Bone CT: Common locations of tympanosclerotic calcification Tympanic membrane Ossicle surface Stapes footplate Muscle tendons Ossicle ligaments Focal tympanosclerotic ossifications May be seen anywhere in middle ear-mastoid Chronic otomastoiditis findings associated Top Differential Diagnoses Chronic otitis media COM with ossicular erosions COM with ossicular fixation Fenestral otosclerosis Ossicular prosthesis Pathology Etiology: Healing response to repeated inflammatory events in middle ear-mastoid “True” tympanosclerosis Diffuse hyalinization & deposition of calcium & phosphate crystals New bone formation (osteoneogenesis) Clinical Issues Treatment options Atticotomy with mobilization of ossicles Insertion of prosthesis or homograft device (Left) Coronal graphic shows severe tympanosclerosis in setting of chronic otomastoiditis Postinflammatory calcification can be seen in tympanic membrane , ossicles , and ossicle ligament (Right) Coronal bone CT reveals the ossicles as a “fuzzy ball” This appearance is due to tympanosclerotic calcific foci deposited on the surface of the middle ear ossicles 1370 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a focal area of ossific tympanosclerosis just medial to the ossicles in the medial wall of the epitympanum Also note the malleus-incus articulation is fused , and the mastoid contains an antral cavity only (Right) Coronal bone CT reveals thickening of the tympanic membrane with a linear focus of calcification along its surface Tympanosclerotic calcifications can affect ligaments, tendons, ossicles, or the tympanic membrane as in this case P.VI(3):27 TERMINOLOGY Abbreviations Chronic otomastoiditis (COM) with tympanosclerosis Synonyms COM with focal calcification or ossification Postinflammatory ossicular fixation Definitions Calcific, bony, or fibrous middle ear foci secondary to suppurative COM IMAGING CT Findings Bone CT Common locations of tympanosclerotic Ca++ Tympanic membrane Ossicle surface Stapes footplate Crura and footplate thickened Referred to as “peri-stapedial tent” Muscle tendons Stapedius & tensor tympani muscles Ossicle ligaments Mastoid air cells Focal tympanosclerotic ossifications Heaped up new bone (osteoneogenesis) May occur anywhere in middle ear-mastoid (ME-M) Chronic otomastoiditis findings Heterogeneous soft tissue (inflammatory tissue) ME-M Underpneumatized mastoid DIFFERENTIAL DIAGNOSIS Chronic Otitis Media Clinical: Conductive hearing loss (CHL) variable; COM history CT: Patchy, nondestructive middle ear debris Debris not calcific or ossific COM with Ossicular Erosions 1371 Diagnostic Imaging Head and Neck Clinical: COM + CHL CT: Inflammatory debris, ossicle loss COM with Ossicular Fixation Clinical: COM + CHL CT: Focal ossicle ankylosis May have component of tympanosclerosis Fenestral Otosclerosis Clinical: No history of COM (well-pneumatized mastoid) CT: Lucency in fissula ante fenestram Associated with cochlear otosclerosis PATHOLOGY General Features Etiology Healing response to repeated inflammatory events “True” calcific tympanosclerosis Diffuse hyalinization & deposition of calcium & phosphate crystals Ossific tympanosclerosis New bone formation (osteoneogenesis) Associated abnormalities Formed by fused collagenous fibers Fibers hardened by deposition of calcium & phosphate crystals Staging, Grading, & Classification types of postinflammatory ossicular fixation Fibrous tissue fixation No calcification May occur anywhere in ME-M “True” calcific tympanosclerosis Multiple small calcifications Ossific tympanosclerosis New bone formation (osteoneogenesis) Microscopic Features Calcification of previously hyalinized mucoperiosteum Onion skin-like lamellar arrangement CLINICAL ISSUES Presentation Most common signs/symptoms Severe CHL + COM history Other signs/symptoms Otoscopy: Thick, opaque TM Demographics Age Average age at diagnosis = 35 years Epidemiology 10% suppurative COM patients develop tympanosclerosis Treatment Atticotomy with mobilization of ossicles Insertion of prosthesis or homograft device DIAGNOSTIC CHECKLIST Consider Fenestral otosclerosis 1st in CHL patient without COM SELECTED REFERENCES Celik H et al: Analysis of long-term hearing after tympanosclerosis with total/partial stapedectomy and prosthesis used Acta Otolaryngol 128(12):1308-13, 2008 Karlidağ T et al: Comparison of free radicals and antioxidant enzymes in chronic otitis media with and without tympanosclerosis Laryngoscope 114(1):85-9, 2004 Palacios E et al: Tympanosclerosis Ear Nose Throat J 79(1):17, 2000 Lemmerling MM et al: Normal and opacified middle ears: CT appearance of the stapes and incudostapedial joint Radiology 203(1):251-6, 1997 1372 Diagnostic Imaging Head and Neck Swartz JD et al: Postinflammatory ossicular fixation: CT analysis with surgical correlation Radiology 154(3):697-700, 1985 Pars Flaccida Cholesteatoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Infectious and Inflammatory Lesions > Pars Flaccida Cholesteatoma Pars Flaccida Cholesteatoma Yolanda Y.P Lee, MBChB, FRCR H Ric Harnsberger, MD Key Facts Terminology Pars flaccida cholesteatoma (PFC) “Attic” or “Prussak space” cholesteatoma Imaging T-bone CT: Smaller PFC Soft tissue mass in Prussak space with scutum & ossicle erosions T-bone CT: Larger PFC Lateral semicircular canal dehiscence Tegmen tympani ± mastoideum dehiscence Facial nerve canal erosion Sinus tympani extension (associated with high postoperative recurrence rate) Top Differential Diagnoses Acquired pars tensa cholesteatoma Congenital middle ear cholesteatoma Middle ear cholesterol granuloma Glomus tympanicum paraganglioma Pathology Beginning at pars flaccida of tympanic membrane (TM) in small posterosuperior portion of TM Retraction pocket theory and basal hyperplasia theories relate best with PFC Microscopically consists of exfoliated keratin within stratified squamous epithelium Clinical Issues Most common type of cholesteatoma (80% of all acquired cholesteatomas) Patient with chronic ME inflammatory disease & conductive hearing loss & TM abnormality TM retraction: PFC not visible; CT must make diagnosis based on ossicle or bone loss TM perforation: PFC visible; diagnosis known (Left) Coronal graphic shows small cholesteatoma originating at pars flaccida portion of the tympanic membrane with filling of Prussak space Slight erosion with medial displacement of head of malleus is present (Right) Coronal bone CT reveals a small pars flaccida cholesteatoma filling the Prussak space with blunting of the scutum The head of malleus is mildly eroded and medially displaced 1373 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows a large pars flaccida cholesteatoma Complications include erosion of ossicles, dehiscence of lateral semicircular canal , & scalloping of tegmen tympani (Right) Coronal bone CT shows a large pars flaccida cholesteatoma as a soft tissue mass within the right middle ear and mastoid cavity There is fistulation with the lateral semicircular canal Cholesteatoma is also visible protruding through the TM perforation into the external auditory canal P.VI(3):29 TERMINOLOGY Abbreviations Pars flaccida cholesteatoma (PFC) Synonyms “Attic” or “Prussak space” cholesteatoma Primary acquired cholesteatoma Definitions Focal accumulation of exfoliated keratin within stratified squamous epithelium, begins in Prussak space IMAGING General Features Best diagnostic clue Soft tissue mass starts in Prussak space with scutum, ossicle, or lateral epitympanum wall erosion Location From Prussak space, spreads to posterior epitympanum, posterior mesotympanum, & less commonly anterior epitympanum Size From millimeters (early) to centimeters (late) Neglected PFC could fill entire middle ear (ME) cavity & beyond Morphology Well-circumscribed ME mass Soft tissue density Large lesions often associated with scar & effusion; may be less well defined CT Findings CECT No enhancement of cholesteatoma Surrounding granulation tissue may enhance Bone CT Small PFC Soft tissue mass starts in Prussak space Prussak space = lateral epitympanic recess Ossicular chain erosion in 70% Long process of incus erosion more common than incus body & malleus head erosion Ossicles medially displaced 1374 Diagnostic Imaging Head and Neck Scutum erosion common Caveat: Small cholesteatoma without bone erosion can be nonspecific on bone CT Large PFC Local extension Superior extension into Prussak space & remaining epitympanum Posterolateral through aditus ad antrum into mastoid antrum Expansion and scalloping of ME & mastoid cavity Important potential bone erosions/complications Lateral semicircular canal/labyrinthine fistula Tegmentum tympani & mastoideum/intracranial extension ± infection CN7 canal, tympanic segment/CN7 injury Focal erosions around oval or round window MR Findings T1WI Hypointense middle ear mass T2WI Homogeneously hyperintense ME mass DWI Larger PFC seen as hyperintense (restricted diffusion) T1WI C+ Nonenhancing except for peripheral rim of granulation tissue If tegmen tympani erosion present, dural enhancement at bony defect Imaging Recommendations Best imaging tool Temporal bone CT, without contrast = test of choice Coronal CTs best show Prussak space mass, attic, and scutum Temporal bone MR adjunctive when PFC large & complicated T1 C+ shows nonenhancing cholesteatoma vs enhancing inflammatory tissues Extratemporal infection (abscess, empyema) easily diagnosed DWI high signal confirms PFC present Protocol advice Single-shot (SS) turbo spin-echo (TSE) DWI more sensitive than echo-planar (EPI) DWI Reportedly detects lesion as small as mm DIFFERENTIAL DIAGNOSIS Acquired Pars Tensa Cholesteatoma Otoscopy: TM rupture or retraction in posterosuperior pars tensa area Less common than pars flaccida type Bone CT: Sinus tympani & facial recess involvement are classic Ossicles pushed laterally Middle Ear Congenital Cholesteatoma Otoscopy: Tan-white mass behind intact TM Bone CT: Nondependent ME mass Medial to ossicles ± ossicle erosions Middle Ear Cholesterol Granuloma Otoscopy: Retrotympanic “blue” mass Bone CT: Ossicular & bony erosions may be similar to cholesteatoma MR: Hyperintense on T1 Glomus Tympanicum Paraganglioma Otoscopy: Retrotympanic red, pulsatile mass Bone CT: Focal mass on cochlear promontory; ME floor intact MR: T1 C+ shows avidly enhancing tumor PATHOLOGY General Features Etiology Beginning at pars flaccida (PF) portion of tympanic membrane (TM) P.VI(3):30 PF = small posterosuperior portion of TM 1375 Diagnostic Imaging Head and Neck Various theories on pathogenesis Retraction pocket theory (RPT) & basal hyperplasia theories (BHT) relate best with PFC RPT: Eustachian tube dysfunction → negative ME pressure → PF retraction pocket → accumulation of keratin debris → superinfection + inflammation BHT: Inflammation & epidermal hyperplasia breaks basement membrane → subepithelial invasion + keratinocytic proliferation Squamous epithelium + keratin accumulation forms cholesteatoma Gross Pathologic & Surgical Features “Pearly tumor,” composed of soft, waxy, white-gray or pale yellow material Chronic inflammatory change always present Erosion of ossicles, scutum, and upper part of bony tympanic annulus visible in most cases Microscopic Features Stratified squamous epithelium with anucleated (dead) keratin squames Content high in cholesterol crystals Layer of granulation tissue always present when in contact with bone Seems to be cause of bone erosion CLINICAL ISSUES Presentation Most common signs/symptoms Foul-smelling aural discharge Conductive hearing loss (CHL) Chronic ME inflammatory disease & TM retraction or perforation Other signs/symptoms Noise- or pressure-induced vertigo if lateral semicircular canal dehisced Otologic examination TM retraction pocket or perforation at pars flaccida If TM perforation: PFC visible If TM retracted: PFC often not visible Demographics Age May occur in children or adults Unusual in children < years of age Cholesteatoma in children more aggressive Extensive disease & recurrence common Epidemiology Most common middle ear-mastoid lesion Most common type of cholesteatoma (80% of all acquired cholesteatomas) Natural History & Prognosis Progressive ↑ in size of cholesteatoma Increasing destruction of surrounding structures, including ossicular chain, lateral semicircular canal, tegmen tympani CN7 involvement, venous sinus thrombosis, & intracranial extension are late complications Small cholesteatoma: Excellent for total eradication with normal long-term hearing Large cholesteatoma: Residual conductive hearing loss is possible Recurrence rate is 5-10% Treatment Early treatment of retraction pocket with tympanostomy tube may prevent cholesteatoma formation Surgery includes mastoidectomy & formation of common cavity between mastoid antrum & EAC TM & ossicle reconstruction necessary Treatment aimed at clearing cholesteatoma & infection, preventing further damage Hearing improvement is secondary goal DIAGNOSTIC CHECKLIST Consider clinical presentations for imaging possible cholesteatoma Patient has visible cholesteatoma Referring clinician wants to know extent & complications Patient has visible TM retraction pocket + CHL Referring clinician wants to know if cholesteatoma present Caveat: If ME soft tissue seen without bone or ossicle erosion, not suggest cholesteatoma! 1376 Diagnostic Imaging Head and Neck Image Interpretation Pearls When ME & mastoid completely opacified with no ossicular erosion, most likely ME effusion, not cholesteatoma Reporting Tips Sinus tympani extension associated with high postoperative recurrence rate Lateral semicircular canal fistula & CN7 canal dehiscence warrant cautious operation SELECTED REFERENCES Jeunen G et al: The value of magnetic resonance imaging in the diagnosis of residual or recurrent acquired cholesteatoma after canal wall-up tympanoplasty Otol Neurotol 29(1):16-8, 2008 Persaud R et al: Evidence-based review of aetiopathogenic theories of congenital and acquired cholesteatoma J Laryngol Otol 121(11):1013-9, 2007 De Foer B et al: Single-shot, turbo spin-echo, diffusion-weighted imaging versus spin-echo-planar, diffusionweighted imaging in the detection of acquired middle ear cholesteatoma AJNR Am J Neuroradiol 27(7):1480-2, 2006 Vercruysse JP et al: The value of diffusion-weighted MR imaging in the diagnosis of primary acquired and residual cholesteatoma: a surgical verified study of 100 patients Eur Radiol 16(7):1461-7, 2006 Watts S et al: A systematic approach to interpretation of computed tomography scans prior to surgery of middle ear cholesteatoma J Laryngol Otol 114(4):248-53, 2000 Iino Y et al: Risk factors for recurrent and residual cholesteatoma in children determined by second stage operation Int J Pediatr Otorhinolaryngol 46(1-2):57-65, 1998 Vartiainen E et al: Long-term results of surgical treatment in different cholesteatoma types Am J Otol 14(5):50711, 1993 P.VI(3):31 Image Gallery (Left) Axial bone CT reveals a large cholesteatoma in the middle ear cavity with scalloping of the walls There is erosion of the anterior portion of the lateral semicircular canal with fistulation (Right) Coronal bone CT of the same patient shows that the tegmen tympani is thinned and that the lateral semicircular canal is dehiscent Saucerization of the bony tympanic CN7 canal and blunting of the scutum are also present 1377 Diagnostic Imaging Head and Neck (Left) Axial bone CT demonstrates soft tissue mass filling the tympanic cavity The soft tissue extends to the sinus tympani , which is an important checkpoint as it is a surgical blind spot and often a site of recurrence The long process of incus is eroded (not shown) (Right) Coronal bone CT in the same patient shows epitympanic cholesteatoma with scutum blunting Malleus is medially displaced and partially eroded Lesion abuts but does not erode into anterior tympanic CN7 (Left) Coronal T1 C+ MR reveals a large acquired cholesteatoma expanding the mastoid cavity The lesion breached tegmen mastoideum with extension to the middle cranial fossa Note enhancement of adjacent dura indicative of inflammatory change, confirming the intracranial extension (Right) Axial DWI MR in a patient many years after surgical removal of large cholesteatoma shows recurrent disease as high signal from restricted diffusion in the inferior mastoid Pars Tensa Cholesteatoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Infectious and Inflammatory Lesions > Pars Tensa Cholesteatoma Pars Tensa Cholesteatoma Yolanda Y.P Lee, MBChB, FRCR H Ric Harnsberger, MD Key Facts Terminology Pars tensa cholesteatoma (PTC) Synonym: Secondary acquired cholesteatoma 1378 Diagnostic Imaging Head and Neck Focal accumulation of exfoliated keratin within stratified squamous epithelium at site of perforation or retraction pocket at pars tensa TM Imaging Bone CT findings Erosive mass in posterior mesotympanum Medial to ossicles May involve sinus tympani, facial recess, aditus ad antrum ± mastoid Ossicular erosion common, along medial incus long process, stapes superstructure, & manubrium of malleus Axial & coronal T-bone CT are studies of choice MR adjunctive; answers issues raised by bone CT Top Differential Diagnoses Middle ear congenital cholesteatoma Pars flaccida acquired cholesteatoma Middle ear cholesterol granuloma Glomus tympanicum paraganglioma Pathology Most believe related to TM perforation at pars tensa Migrated/implanted epithelium through TM perforation → nidus of stratified squamous epithelium with keratin squames in ME → cholesteatoma Clinical Issues 10-20% of all middle ear cholesteatomas Significantly less common than pars flaccida cholesteatoma (Left) Coronal graphic of pars tensa cholesteatoma (PTC) shows the cholesteatoma extending laterally through an inferior TM rupture The middle ear PTC erodes ossicles , invades & flattens tympanic CN7 canal , and is primarily medial to the ossicles (Right) Coronal bone CT at the level of the cochlea demonstrates a pars tensa tympanic membrane perforation The most anterior aspect of the PTC is seen above and below the perforation in the middle ear cavity 1379 Diagnostic Imaging Head and Neck (Left) Axial bone CT in the same patient reveals the PTC eroding the short process of the incus and extending through the aditus ad antrum into the mastoid antrum (Right) Axial bone CT at the level of the oval window reveals erosion of the incus and hub of the stapes with invasion of the facial nerve recess and sinus tympani Sinus tympani involvement must be reported, as this area is blind to the surgeon and recurrence may occur if unnoticed P.VI(3):33 TERMINOLOGY Abbreviations Pars tensa cholesteatoma (PTC) Synonyms “Sinus” cholesteatoma, due to involvement of sinus tympani Secondary acquired cholesteatoma Definitions Focal accumulation of exfoliated keratin within stratified squamous epithelium at site of perforation or retraction pocket at pars tensa portion of tympanic membrane (TM) “Tense” lower 2/3 of TM IMAGING General Features Best diagnostic clue Erosive mass in posterior mesotympanum involving sinus tympani, facial nerve recess, aditus ad antrum ± mastoid Location Posterior mesotympanum Spread posteromedially In part medial to ossicles Size From several millimeters to 2-3 cm Large PTC fills middle ear cavity Morphology Lobular, well-circumscribed, soft tissue density mass Nonenhancing, with ossicular or bone erosion Bone erosion has multiple causes Inflammatory enzymatic dissolution of bone Pressure-induced bone resorption from expanding PTC CT Findings CECT Nonenhancing soft tissue mass Bone CT Small PTC 1380 Diagnostic Imaging Head and Neck Soft tissue mass begins at posterior mesotympanum Most commonly begins at sinus tympani & facial nerve recess Mass projects medial to ossicular chain Subtle lateral displacement of ossicles Early ossicular erosion from medial aspect Large PTC Fills middle ear cavity Invades mastoid through widened aditus ad antrum Ossicular erosion common Along medial incus long process, stapes superstructure, & manubrium of malleus Posterior tegmen tympani & anterior tegmen mastoideum dehiscence may occur MR Findings T1WI Hypointense middle ear mass T2WI PTC usually high signal Trapped secretions of mastoid higher signal than PTC DWI Hyperintense, restricted diffusion as in other types of cholesteatoma or epidermoid T1WI C+ PTC itself does not enhance Granulation tissue & other scar may enhance If tegmen erosion present, dural enhancement at bony defect Shows intracranial complications Imaging Recommendations Best imaging tool Axial & coronal T-bone CT is study of choice T1 C+ MR to answer specific issues raised by bone CT Temporal lobe extension, subperiosteal or intracranial abscess, meningitis, labyrinthitis, lateral sinus thrombosis Enhancement of labyrinth suggests labyrinthitis DIFFERENTIAL DIAGNOSIS Middle Ear Congenital Cholesteatoma Otoscopy: White mass behind intact TM in children Bone CT: Often located posteriorly like pars tensa cholesteatoma Pars Flaccida Acquired Cholesteatoma Otoscopy: Pars flaccida perforation or retraction pocket Bone CT: Prussak space mass with erosion of scutum, lateral body of incus, and head of malleus; ossicles pushed medially Middle Ear Cholesterol Granuloma Otoscopy: Blue mass behind intact TM Bone CT: Ossicular & bony erosions may mimic cholesteatoma T1 MR: Hyperintense mass Glomus Tympanicum Paraganglioma Otoscopy: Cherry red pulsatile mass behind intact TM Bone CT: Mass on cochlear promontory without ossicular erosion T1 C+ MR: Intense enhancement of mass PATHOLOGY General Features Etiology Migration theory: TM perforation → migration of TM epidermis to middle ear Implantation theory: Implantation of TM epidermis behind healed TM perforation, temporal bone fracture, or ME surgical site Migrated/implanted stratified squamous epithelium with keratin squames is nidus of cholesteatoma Gross Pathologic & Surgical Features “Pearly tumor” seen at surgery Well-circumscribed, soft, waxy, white material P.VI(3):34 1381 Diagnostic Imaging Head and Neck Microscopic Features Stratified squamous epithelium with anucleated keratin squames Same histology as epidermoid and any cholesteatoma elsewhere in body CLINICAL ISSUES Presentation Most common signs/symptoms Can be asymptomatic History of chronic otitis media ± TM perforation Progressive unilateral conductive hearing loss Foul-smelling otorrhea due to infection Other signs/symptoms Noise- or pressure-induced vertigo if labyrinthine fistula present Most common at basal turn of cochlear Facial nerve paresis or palsy Due to pressure effect (slow onset), infection (acute onset), CN7 canal erosion Otalgia, headache If infected ± intracranial complication Otologic examination Retraction pocket, perforation, or visible cholesteatoma at pars tensa Edema, granulation tissue, aural polyp representing chronic inflammation Sensorineural hearing loss suspicious for complication with labyrinthine fistula Demographics Age Occurs in children & adults Gender M=F Ethnicity Rare lesion in Eskimo, American Indian, & Australian children, despite middle ear infections Epidemiology 10-20% of all middle ear cholesteatomas Significantly less common than pars flaccida cholesteatoma Natural History & Prognosis Progressive enlargement with growing symptom complex due to local extension Small lesion Excellent for total eradication & normal hearing Large lesion Residual conductive hearing loss common Postoperative recurrence rate ˜ 10% Treatment Surgical removal of cholesteatoma requires mastoidectomy Formation of common cavity between mastoid antrum & external auditory canal Canal-wall-up surgery: Posterior wall EAC not removed Canal-wall-down surgery: Posterior wall EAC removed TM & ossicular reconstruction required for hearing restoration if ossicular chain involved DIAGNOSTIC CHECKLIST Consider PTC if CT shows middle ear mass is centered posteriorly, extends medial to ossicles, & displaces ossicles laterally If bone CT shows medial ossicle erosion, consider PTC Image Interpretation Pearls Axial and coronal CT show location and local extension best MR differentiates PTC from effusion, granulation, cholesterol granuloma, and glomus tympanicum Enhanced T1 MR shows intracranial complication or labyrinthitis if suspected Reporting Tips Sinus tympani involvement is often site of recurrence Presence of labyrinthine fistula, degree of posterior canal wall erosion, and mastoid aeration/sclerosis affects choice of operation Facial nerve canal erosion and tegmen dehiscence important for preoperative planning 1382 Diagnostic Imaging Head and Neck Intracranial complication requires urgent attention SELECTED REFERENCES Vercruysse JP et al: Magnetic resonance imaging of cholesteatoma: an update B-ENT 5(4):233-40, 2009 Jeunen G et al: The value of magnetic resonance imaging in the diagnosis of residual or recurrent acquired cholesteatoma after canal wall-up tympanoplasty Otol Neurotol 29(1):16-8, 2008 De Foer B et al: The value of single-shot turbo spin-echo diffusion-weighted MR imaging in the detection of middle ear cholesteatoma Neuroradiology 49(10):841-8, 2007 Vercruysse JP et al: The value of diffusion-weighted MR imaging in the diagnosis of primary acquired and residual cholesteatoma: a surgical verified study of 100 patients Eur Radiol 16(7):1461-7, 2006 Aikele P et al: Diffusion-weighted MR imaging of cholesteatoma in pediatric and adult patients who have undergone middle ear surgery AJR Am J Roentgenol 181(1):261-5, 2003 Gocmen H et al: Surgical treatment of cholesteatoma in children Int J Pediatr Otorhinolaryngol 67(8):867-72, 2003 Minor LB: Labyrinthine fistulae: pathobiology and management Curr Opin Otolaryngol Head Neck Surg 11(5):3406, 2003 Williams MT et al: Detection of postoperative residual cholesteatoma with delayed contrast-enhanced MR imaging: initial findings Eur Radiol 13(1):169-74, 2003 Yates PD et al: CT scanning of middle ear cholesteatoma: what does the surgeon want to know? Br J Radiol 75(898):847-52, 2002 10 Sade J: Surgical planning of the treatment of cholesteatoma and postoperative follow-up Ann Otol Rhinol Laryngol 109(4):372-6, 2000 11 Watts S et al: A systematic approach to interpretation of computed tomography scans prior to surgery of middle ear cholesteatoma J Laryngol Otol 114(4):248-53, 2000 12 Vartiainen E et al: Long-term results of surgical treatment in different cholesteatoma types Am J Otol 14(5):50711, 1993 P.VI(3):35 Image Gallery (Left) Axial temporal bone CT reveals a smaller middle ear PTC, medial to ossicles , eroding the short process of the incus and filling the sinus tympani (Right) Coronal temporal bone CT in the same patient shows a pars tensa cholesteatoma surrounding the ossicles emanating from a tympanic membrane perforation The scutum remains intact and the bulk of the lesion is medial to the ossicles , both features supporting diagnosis of PTC 1383 Diagnostic Imaging Head and Neck (Left) Axial bone CT through the low mesotympanum shows thickening of the lower tympanic membrane with expansile bony changes in anterior mesotympanum Note underpneumatized mastoid secondary to chronic otomastoiditis (Right) Axial bone CT in the same patient reveals low mesotympanum opacification with bony eustachian tube expansile remodeling along with subtle focal erosion of lateral petrous ICA wall PTC began in anteroinferior TM & extended into eustachian tube (Left) Axial temporal bone CT shows a small PTC in the anteroinferior tympanic membrane in this patient with history of remote tympanostomy tube placement and current pars tensa perforation Tympanostomy tubes are usually placed through the par tensa portion of the tympanic membrane (Right) Coronal bone CT in the same patient shows the small infratympanic membrane pars tensa cholesteatoma just above the tympanic annulus Mural Cholesteatoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Infectious and Inflammatory Lesions > Mural Cholesteatoma Mural Cholesteatoma Yolanda Y.P Lee, MBChB, FRCR H Ric Harnsberger, MD Key Facts Terminology Synonyms: Automastoidectomy; “shell” or “rind” cholesteatoma Rare variant of acquired cholesteatoma 1384 Diagnostic Imaging Head and Neck Definition: Residual cholesteatoma rind left behind after acquired middle ear-mastoid cholesteatoma extrudes central matrix through dehiscent EAC bony wall Imaging Temporal bone CT findings “Mastoidectomy cavity” with residual soft tissue rind along cavity wall without history of mastoidectomy Large lesion can fistulize any area of inner ear Focal dehiscence of posterior or superior EAC wall Top Differential Diagnoses Coalescent mastoiditis Mastoidectomy Pathology Rind of tissue found along wall of cavity Only “lining” of cholesteatoma seen by pathologist Microscopic features: Aggressive keratinizing stratified squamous epithelium Clinical Issues Long history of chronic otitis media without mastoidectomy May report material “falling out of ear” Older patient with chronically draining ear Diagnostic Checklist CT findings suggest mastoidectomy but none has occurred: “Automastoidectomy” Check for ossicle destruction, inner ear or CN7 canal dehiscence, EAC wall erosion (Left) Coronal graphic shows a large cholesteatoma beginning at a pars flaccida perforation The lesion has eroded the middle ear walls, ossicles, mastoid cavity, and the EAC bony walls (Right) Coronal graphic reveals the large cholesteatoma in the previous drawing has evacuated its central material through the EAC dehiscence into the external ear canal A mural cholesteatoma is left behind as a cholesteatoma rind along the walls of the middle ear and mastoid 1385 Diagnostic Imaging Head and Neck (Left) Coronal T-bone CT demonstrates a partially extruded mural cholesteatoma in an enlarged mastoid cavity with a broad EAC posterosuperior wall dehiscence (Right) Coronal T-bone CT shows a thin-walled mural cholesteatoma in a hollowed out mastoid cavity Lateral semicircular canal dehiscence is present The thickness of the mural cholesteatoma rind is dependent on the amount of the lesion that has been extruded P.VI(3):37 TERMINOLOGY Synonyms Automastoidectomy; “shell” or “rind” cholesteatoma Definitions Residual cholesteatoma rind left behind after acquired middle ear-mastoid cholesteatoma extrudes central matrix through dehiscent EAC bony wall IMAGING General Features Best diagnostic clue “Mastoidectomy” cavity with residual soft tissue along cavity wall without history of mastoidectomy Location Middle ear & mastoid Size Cholesteatoma rind of variable thickness CT Findings Bone CT “Hollowed out” middle ear-mastoid with residual cholesteatoma rind seen along walls of cavity Variably sized mastoid cavity Common cavity connects middle ear & antrum Ossicles usually destroyed Scutum severely truncated Labyrinthine fistula often present Lateral semicircular canal most common Large lesion can fistulize any area of inner ear MR Findings T1WI Mastoid cavity appears identical to surgical defect May be complicated by cephalocele T1WI C+ Peripheral enhancement along margin of cavity if granulation tissue present Imaging Recommendations Best imaging tool Temporal bone CT study of choice Protocol advice 1386 Diagnostic Imaging Head and Neck T-bone CT in axial & coronal planes T1 C+ MR reserved for complicated cases DIFFERENTIAL DIAGNOSIS Coalescent Mastoiditis Middle ear cavity not enlarged Mastoid air cells become confluent in setting of acute otitis media Middle ear & mastoid completely opacified Mastoidectomy Posterolateral wall of mastoid absent Surgical history is known PATHOLOGY General Features Etiology Acquired cholesteatoma begins in middle ear Enlargement of cholesteatoma fills entire middle ear cavity ± mastoid antrum Pressure built up with further cholesteatoma growth relieved by expulsion of content through EAC dehiscence or TM perforation Cholesteatoma matrix extrudes through perforated TM or directly into EAC Outer shell/erosive membrane persists after drainage Continued cavity growth from enzymatic activity Gross Pathologic & Surgical Features Cholesteatoma rind found along wall of cavity Microscopic Features Only “lining” of cholesteatoma viewable Aggressive keratinizing stratified squamous epithelium CLINICAL ISSUES Presentation Most common signs/symptoms Long history of chronic otitis media No history of mastoidectomy May report material “falling out of ear” Otologic exam May be seen as tympanic membrane perforation or draining sinus through EAC wall Demographics Age Usually in older patient Epidemiology Mural cholesteatoma = rare variant form of acquired cholesteatoma Pars flaccida > > pars tensa > > mural acquired cholesteatoma Natural History & Prognosis Restoration of hearing difficult because of complete ossicle destruction & bone erosion Treatment Surgery depends on lesion size and extent Excision of tissue lining cavity imperative Ossicular reconstruction DIAGNOSTIC CHECKLIST Consider Imaging findings suggest mastoidectomy has occurred No history of mastoidectomy; hence term “automastoidectomy” Image Interpretation Pearls EAC dehiscence along with hollowed out mastoid + mastoid rind = mural cholesteatoma SELECTED REFERENCES Miranda JA et al: Automastoidectomy Braz J Otorhinolaryngol 72(3):429, 2006 Aberg B et al: Clinical characteristics of cholesteatoma Am J Otolaryngol 12(5):254-8, 1991 Nardis PF et al: Unusual cholesteatoma shell: CT findings J Comput Assist Tomogr 12(6):1084-5, 1988 Middle Ear Cholesterol Granuloma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Infectious and Inflammatory Lesions > Middle Ear Cholesterol Granuloma 1387 Diagnostic Imaging Head and Neck Middle Ear Cholesterol Granuloma H Ric Harnsberger, MD Key Facts Terminology Recurrent hemorrhage into ME cavity causes inflammatory mass of granulation tissue Imaging Bone CT: Smoothly expansile mass of middle ear ± mastoid cells MR: High T1 & T2 signal in middle ear Top Differential Diagnoses Dehiscent jugular bulb Aberrant internal carotid artery Chronic otitis media + hemorrhage Pars flaccida acquired cholesteatoma Paraganglioma Glomus tympanicum paraganglioma Glomus jugulare paraganglioma Encephalocele of middle ear Traumatic hemotympanum Clinical Issues Otoscopy: Nonpulsating bluish discoloration of tympanic membrane = “blue eardrum” Symptoms arise years after initial episodes of otitis media Recurrence rates for CG-ME much lower than for CG-PA Most CG-ME grow over decades Initial surgery: Resection of wall & contents Intractable disease: Mastoidectomy + ventilation tube Diagnostic Checklist “Blue tympanic membrane” + expansile changes (on bone CT) + high T1 (on MR) = cholesterol granuloma of middle ear (Left) Coronal graphic depicts a large middle ear cholesterol granuloma The entire middle ear is filled with dark brown (“chocolate”) fluid with the ossicles no longer present Otoscopy reveals a “blue-black eardrum.” (Right) Coronal T1WI MR demonstrates a retrotympanic high signal cholesterol granuloma that causes the tympanic membrane to bulge into the external auditory canal Notice the signal of the cochlea medially The cholesterol granuloma fills the entire middle ear cavity 1388 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR in a patient with a blue-black retrotympanic lesion shows high signal cholesterol granuloma filling the middle ear and mastoid antrum Note the low signal head of malleus and short process of incus visible within the lesion (Right) Axial T2WI fat-saturated MR in the same patient reveals hyperintense cholesterol granuloma in the epitympanum & mastoid antrum Early phase disease preserves the ossicles & shows no evidence of bony scalloping P.VI(3):39 TERMINOLOGY Abbreviations Cholesterol granuloma (CG) Synonyms Cholesterol cyst, chocolate cyst, blue-dome cyst Definitions Recurrent hemorrhage into middle ear (ME) cavity causes inflammatory mass of granulation tissue IMAGING General Features Best diagnostic clue Bone CT: Smoothly expansile mass of middle ear ± mastoid cells MR: High T1 & T2 signal in middle ear Location CG most commonly arises in middle ear Also occurs in petrous apex (PA) & orbit Size Depends on chronicity; millimeters to centimeters Morphology Expansile nature critical to diagnosis, distinguishes CG from hemorrhagic otitis media without granulation tissue CT Findings CECT May be useful to distinguish small CG from glomus tympanicum paraganglioma, which enhances briskly Bone CT Early CG-ME bone CT findings Small middle ear mass No ossicular loss or bone remodeling Difficult to make specific diagnosis Late CG-ME bone CT findings Opacified middle ear & mastoid Expansile bony changes with scalloping of surrounding bone Ossicular displacement ± destruction MR Findings 1389 Diagnostic Imaging Head and Neck T1WI ↑ signal from paramagnetic effect of methemoglobin T2WI Central ↑ signal from granulation tissue Peripheral ↓ signal from hemosiderin deposition STIR Follows T2 signal T1WI C+ Inherent high T1 signal confused with enhancement Compare to unenhanced T1WI MRA May be useful to distinguish CG from vascular anomalies (e.g., aberrant internal carotid artery) CT preferred to eliminate vascular lesions Imaging Recommendations Best imaging tool Temporal bone CT initially MR used in larger lesions DIFFERENTIAL DIAGNOSIS Dehiscent Jugular Bulb Otoscopy: Blue-black mass in middle ear Bone CT: Absence of thin bone between jugular bulb & hypotympanum Diverticulum of jugular vein extends into ME Thin section CT needed for diagnosis Both axial & coronal planes useful Aberrant Internal Carotid Artery (ICA) Otoscopy: Red, pulsatile mass in middle ear Bone CT: Tubular mass crosses ME cavity to rejoin horizontal petrous ICA Large inferior tympanic canaliculus Enlarged collateral vessel traverses ME when ICA fails to develop Chronic Otitis Media + Hemorrhage Otoscopy: Inflammatory tissue & blood in middle ear ± ruptured tympanic membrane Bone CT: Inflammatory tissue & blood fill middle ear without expansile bony changes MR: Variable T1 & T2 signal Pars Flaccida Acquired Cholesteatoma Otoscopy: Tympanic membrane retraction-rupture ± visible cholesteatoma Bone CT: Erosive ME-mastoid mass with ossicle loss MR: Low T1 & high T2; rim enhances on T1 C+ Like CG-ME, associated with recurrent prior infections ± effusions Microscopic: Cholesteatoma lined by squamous epithelium CG-ME lined with fibrous connective tissue Paraganglioma Otoscopy: Red mass in middle ear Bone CT Glomus tympanicum paraganglioma On cochlear promontory Glomus jugulare paraganglioma Permeative bone changes, jugular foramen to ME Encephalocele of Middle Ear Surgical view: Can mimic CG-ME strongly Bone CT: Dehiscent tegmen tympani with brain herniation into ME or mastoid cavity MR: Coronal T2 may define contents Usually post-traumatic or postsurgical Traumatic Hemotympanum Otoscopy: Blood in ME from recent trauma Bone CT: Associated T-bone fractures MR: High T1 methemoglobin does not expand ME No obstruction as with CG-ME PATHOLOGY General Features 1390 Diagnostic Imaging Head and Neck Etiology Etiology still not definite P.VI(3):40 Obstruction-vacuum hypothesis Chronic otitis media, cholesteatoma, or previous surgery obstructs air cells of ME ± mastoid air cells Resorption of gas in obstructed air cells creates relative vacuum Decrease in pressure → mucosal engorgement → blood vessel rupture Anaerobic red blood cell degradation to cholesterol crystals incites multinucleated foreign giant cell response → inflammation with small vessel proliferation → vessel rupture Granulation tissue forms from repeated hemorrhage, expanding ME ± mastoid Exposed marrow hypothesis In young adulthood, enlarging mucosa creates bony defects into hematopoietic marrow of Tbone Recurrent microhemorrhage → accumulation of red cell degradation products Anaerobic red blood cell degradation to cholesterol crystals incites multinucleated foreign giant cell response Obstruction secondary to inflammation, rather than obstruction as primary cause Associated abnormalities Recurrent otitis media or effusion Cholesteatoma Benign granulation tissue Differences between CG-ME & CG-PA CG-ME presents with conductive hearing loss; CG-PA presents with facial pain-headache CG-ME has no cranial neuropathies; CG-PA associated with neuropathies of CN5-7 CG-ME has recurrent infections history; CG-PA has no infection history CG-ME has bone erosion late; large CG-PA may have extensive bone erosion CG-ME occurs in poorly pneumatized T-bone (result of prior infections); CG-PA occurs in highly pneumatized T-bone Gross Pathologic & Surgical Features Cystic mass with fibrous capsule, filled with brownish liquid containing old blood & cholesterol crystals Fluid described as “crankcase oil” or “chocolate cyst” Microscopic Features Lined by fibrous connective tissue Red blood cells Multinucleated giant cells surrounding cholesterol crystals embedded in connective tissue Hemosiderin-laden macrophages, chronic inflammatory cells, & blood vessels CLINICAL ISSUES Presentation Most common signs/symptoms Slowly progressive conductive hearing loss Other signs/symptoms Pulsatile tinnitus “Pressure on the ear” Otoscopy: Nonpulsating bluish discoloration of tympanic membrane = “blue eardrum” Clinical profile Younger to middle-aged patient with “blue eardrum” & conductive hearing loss Easily confused clinically with vascular malformation or vascular tumor Recurrent ME infection history helpful for diagnosis Demographics Age Broad age range beginning in 2nd decade Epidemiology CG-ME much more common than CG-PA Natural History & Prognosis Great variability in growth rate of CG-ME Depends on frequency & severity of microhemorrhages within lesion 1391 Diagnostic Imaging Head and Neck Clinical prognostic indicator Protruding TM: Poorer treatment outcome Retracted TM: Better treatment outcome Treatment Initial surgery: Resection of wall & contents Intractable disease: Mastoidectomy + ventilation tube DIAGNOSTIC CHECKLIST Consider “Blue TM” + expansile changes (CT) + high T1 (MR) = cholesterol granuloma of middle ear Image Interpretation Pearls Do not mistake high T1 signal for enhancement Compare with unenhanced T1 Reporting Tips Note if extension into eustachian tube or mastoid Comment on ossicle status SELECTED REFERENCES Matsuda Y et al: Analysis of surgical treatment for middle-ear cholesterol granuloma J Laryngol Otol Suppl (31):906, 2009 Martin TP et al: A large and uncharacteristically aggressive cholesterol granuloma of the middle ear J Laryngol Otol 119(12):1001-3, 2005 Murugasu E et al: Invasive middle ear cholesterol granuloma involving the basal turn of the cochlea with profound sensorineural hearing loss Otol Neurotol 25(3):231-5, 2004 Jackler RK et al: A new theory to explain the genesis of petrous apex cholesterol granuloma Otol Neurotol 24(1):96-106; discussion 106, 2003 Maeta M et al: Surgical intervention in middle-ear cholesterol granuloma J Laryngol Otol 117(5):344-8, 2003 Friedmann I et al: The ultrastructure of cholesterol granuloma of the middle ear: an electron microscope study The Journal of Laryngology and Otology, 1979; Vol 93, pp 433-442 J Laryngol Otol 116(11):877-81, 2002 Campos A et al: Cholesterol granuloma of the middle ear: report of cases Acta Otorhinolaryngol Belg 50(2):1259, 1996 Martin N et al: Cholesterol granulomas of the middle ear cavities: MR imaging Radiology 172(2):521-5, 1989 P.VI(3):41 Image Gallery (Left) Axial bone CT shows a soft tissue mass in the epitympanum , widened aditus ad antrum and mastoid antrum There is no way to tell this is a cholesterol granuloma on CT (Right) Axial T1WI MR in the same patient reveals the high signal cholesterol granuloma in the middle ear and mastoid antrum The high signal of this lesion along with the enlarged aditus ad antrum on CT is highly suggestive of the diagnosis of cholesterol granuloma 1392 Diagnostic Imaging Head and Neck (Left) Axial bone CT reveals a postoperative temporal bone with soft tissue in the mastoid bowl & middle ear as well as in the posterior mastoid air cells The nature of the soft tissue cannot be determined on CT images (Right) Axial T1 nonenhanced MR in the same patient shows a bilobed high signal cholesterol granuloma filling the mastoid bowl and the posterior mastoid air cells (Left) Axial bone CT in the inferior aspect of the left temporal bone reveals an expansile focus just lateral to the jugular foramen Notice the dehiscent lateral margin of the jugular foramen (Right) Axial T1WI MR in the same patient shows that the expansile lesion just lateral to the jugular foramen is high signal without contrast Surgical exploration revealed a “chocolate cyst” of cholesterol granuloma Benign and Malignant Tumors Glomus Tympanicum Paraganglioma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Benign and Malignant Tumors > Glomus Tympanicum Paraganglioma Glomus Tympanicum Paraganglioma Megan Mills, MD H Ric Harnsberger, MD Key Facts Terminology Abbreviation: Glomus tympanicum paraganglioma (GTP) Benign tumor arising from glomus bodies situated on cochlear promontory 1393 Diagnostic Imaging Head and Neck Imaging Best imaging study: Bone-only CT without contrast CT: Mass with flat base on cochlear promontory MR: Enhancing mass with flat base on cochlear promontory Floor of middle ear cavity is intact (if dehiscent, glomus jugulare) Top Differential Diagnoses Glomus jugulare paraganglioma Aberrant internal carotid artery Dehiscent jugular bulb Congenital cholesteatoma, middle ear Facial nerve schwannoma, tympanic segment Pathology Arise from glomus (Latin for “a ball”) bodies (paraganglia) found along inferior tympanic nerve (Jacobson nerve) on cochlear promontory Clinical Issues GTP is most common tumor of middle ear Clinical profile: 50-year-old woman with vascular retrotympanic mass & pulsatile tinnitus Treatment: Surgical resection, approach depends extent of GTP GTP may be clinically indistinguishable from glomus jugulare paraganglioma or AbICA Imaging differentiates GTP from glomus jugulare, AbICA and dehiscent jugular bulb (Left) Coronal graphic shows a vascular glomus tympanicum paraganglioma pedunculating off cochlear promontory into inferior middle ear cavity The bony floor of middle ear cavity is intact Otoscopy reveals this tumor as a reddish, pulsatile mass behind the lower tympanic membrane (Right) Coronal T1WI C+ FS MR demonstrates a larger glomus tympanicum paraganglioma filling the middle ear cavity The floor is present , separating the tumor from the jugular bulb below 1394 Diagnostic Imaging Head and Neck (Left) Axial graphic shows glomus bodies along course of inferior tympanic nerve (branch of Jacobsen nerve ) on the cochlear promontory Glomus tympanicum tumors arise from this normal cellular collection Also note the cochlea (Right) An axial T-bone CT reveals an ovoid glomus tumor on the low cochlear promontory abutting the manubrium of the malleus The patient's history of conductive hearing loss is secondary to the fixation of the inferior malleus-tympanic membrane by the tumor P.VI(3):43 TERMINOLOGY Abbreviations Glomus tympanicum paraganglioma (GTP) Synonyms Glomus tympanicum; chemodectoma Definitions Benign tumor arising from glomus bodies situated on cochlear promontory IMAGING General Features Best diagnostic clue CT: Mass with flat base on cochlear promontory MR: Enhancing mass with flat base on cochlear promontory Location Primary location: Cochlear promontory Variant locations Anterior to promontory, beneath cochleariform process Inferior to promontory, in recess beneath basal turn of cochlea Size Millimeters to cm May be so small that unfocused imaging causes radiologist to miss lesion altogether Morphology Round mass with flat base most common Larger lesions resemble “New Jersey” on coronal image when they fill middle ear cavity CT Findings CECT Difficult to identify enhancing mass in middle ear when GTP small Bone CT Focal mass with flat base on cochlear promontory is characteristic Small GTP May be subtle soft tissue bump on cochlear promontory Projects off cochlear promontory into lower mesotympanum May reach as far lateral as lower tympanic membrane (TM) Large GTP 1395 Diagnostic Imaging Head and Neck Fills middle ear cavity, creating attic block resulting in fluid collection in mastoid Tumor margins may not be discernible on CT Floor of middle ear cavity is intact (if dehiscent or permeative, glomus jugulare) Larger lesions may show “aggressive” bone changes with erosion of medial wall of middle ear cavity ± ossicles Rare involvement of air cells along inferior cochlear promontory may be mistaken for invasion MR Findings T1WI Tissue intensity mass on cochlear promontory GTP too small to see high velocity flow voids inmass T2WI GTP lower signal compared to obstructed fluids T1WI C+ Focal enhancing mass on cochlear promontory With larger obstructing GTP, contrast helps differentiate tumor from obstructed secretions Utilized to determine tumor involvement of hypotympanum Angiographic Findings GTP arterial supply Ascending pharyngeal artery & its inferior tympanic branch, via inferior tympanic canaliculus Imaging Recommendations Best imaging tool Bone CT: Bone-only CT without contrast best if GTP suspected clinically MR: Used if glomus jugulare suspected from bone CT findings Small GTP may be missed if slice thickness > mm May be used to confirm GTP hypotympanic involvement Angiography: Unnecessary if GTP diagnosis clearly established by CT Protocol advice Keep enhanced MR slice thickness ≤4 mm DIFFERENTIAL DIAGNOSIS Glomus Jugulare Paraganglioma Imaging: CT shows permeative change in bony floor of middle ear Clinical: Red-pink mass behind TM Otoscopic exam identical to GTP Aberrant Internal Carotid Artery (AbICA) Imaging: Tubular mass crosses middle ear cavity to rejoin horizontal petrous ICA Large inferior tympanic canaliculus Clinical: Red-pink mass behind TM ± pulsatile tinnitus Dehiscent Jugular Bulb Imaging: CT shows dehiscent sigmoid plate Venous protrusion into middle ear cavity from superolateral jugular bulb Clinical: Asymptomatic; blue mass behind posteroinferior TM Middle Ear Congenital Cholesteatoma Imaging: T1 C+ MR shows no enhancement Clinical: “White” mass behind intact TM Facial Nerve Schwannoma, Tympanic Segment Imaging: Pedunculated mass off tympanic CN7 Clinical: Tan-white mass behind superior TM PATHOLOGY General Features Etiology P.VI(3):44 Arise from glomus (Latin for “a ball”) bodies (paraganglia) found along inferior tympanic nerve (Jacobson nerve) on cochlear promontory Chemoreceptor cells derived from primitive neural crest Nonchromaffin (nonsecretory) in this location Genetics Inactivating mutation of succinate dehydrogenase gene of 11q23 gene may predispose to GTP formation 1396 Diagnostic Imaging Head and Neck Named by location Glomus tympanicum paraganglioma: Middle ear Glomus jugulare: Jugular foramen → middle ear Glomus vagale: Nodose ganglion of nasopharyngeal carotid space Carotid body paraganglioma: In notch of carotid bifurcation Staging, Grading, & Classification Glasscock-Jackson classification of GTP Type I: Small mass limited to cochlear promontory Type II: Tumor completely filling middle ear space Type III: Tumor filling middle ear & extending into mastoid air cells Type IV: Tumor filling middle ear, extending into mastoid or through tympanic membrane to fill external auditory canal May extend anterior to carotid artery Gross Pathologic & Surgical Features Glistening, red, polypoid mass on cochlear promontory Fibrous pseudocapsule Microscopic Features All paragangliomas have same histopathology Chief cells arranged in characteristic compact cell nests or “balls” of cells, referred to as “zellballen” Immunohistochemistry: Chief cells show a diffuse reaction to chromogranin Electron microscopy: Shows neurosecretory granules CLINICAL ISSUES Presentation Most common signs/symptoms Vascular, pulsatile retrotympanic mass If small: Anteroinferior quadrant of TM Pneumatic otoscopy will cause blanching of mass known as “Brown's sign” Other signs/symptoms Pulsatile tinnitus (90%), conductive hearing loss (50%), facial nerve paralysis (5%) Clinical profile 50-year-old woman with vascular retrotympanic mass & pulsatile tinnitus Demographics Age 66% are between 40-60 years of age at diagnosis Gender M:F = 1:3 Epidemiology GTP is most common tumor of middle ear GTP rarely associated with multicentric paragangliomas Natural History & Prognosis Slow-growing, noninvasive tumor Average time from onset of symptoms to surgical treatment is years Complete resection yields permanent surgical cure Treatment Smaller GTP lesions Removed via tympanostomy through external auditory canal Larger GTP lesions Often require mastoidectomy Preoperative selective embolization not necessary Stereotactic radiosurgery used when conventional surgical resection is contraindicated or incomplete DIAGNOSTIC CHECKLIST Consider Be careful with initial diagnosis GTP may be clinically indistinguishable from glomus jugulare paraganglioma or AbICA If GTP diagnosed when glomus jugulare present, incomplete surgery will result If GTP diagnosed when AbICA present, biopsy could be fatal Preoperative imaging must differentiate these diagnoses Image Interpretation Pearls Ask referring clinician color & location of retrotympanic mass 1397 Diagnostic Imaging Head and Neck Red anteroinferior mass: GTP Blue posteroinferior mass: Dehiscent jugular bulb Red mass crossing behind inferior TM: AbICA White mass: Congenital cholesteatoma (inferior) or facial nerve schwannoma (superior) SELECTED REFERENCES Alaani A et al: The crucial role of imaging in determining the approach to glomus tympanicum tumours Eur Arch Otorhinolaryngol 266(6):827-31, 2009 Hirunpat S et al: Nasopharyngeal extension of glomus tympanicum: an unusual clinical and imaging manifestation AJNR Am J Neuroradiol 27(9):1820-2, 2006 Braun S et al: Active succinate dehydrogenase (SDH) and lack of SDHD mutations in sporadic paragangliomas Anticancer Res 25(4):2809-14, 2005 van den Berg R: Imaging and management of head and neck paragangliomas Eur Radiol 15(7):1310-8, 2005 Noujaim SE et al: Paraganglioma of the temporal bone: role of magnetic resonance imaging versus computed tomography Top Magn Reson Imaging 11(2):108-22, 2000 Weissman JL et al: Beyond the promontory: the multifocal origin of glomus tympanicum tumors AJNR Am J Neuroradiol 19(1):119-22, 1998 Alshaikhly A et al: Glomus tympanicum chemodectoma: unusual radiological findings J Laryngol Otol 108(7):607-9, 1994 O'Leary MJ et al: Glomus tympanicum tumors: a clinical perspective Laryngoscope 101(10):1038-43, 1991 Larson TC et al: Glomus tympanicum chemodectomas: Radiographic and clinical characteristics Radiology 163(3):801-6, 1987 P.VI(3):45 Image Gallery (Left) An axial left ear temporal bone CT shows a multilobular soft tissue mass on the low cochlear promontory , consistent with a diagnosis of glomus tympanicum paraganglioma (Right) CT shows this large glomus tympanicum paraganglioma in the middle ear cavity The lesion bulges the tympanic membrane laterally around the umbo of the manubrium Note extension into proximal bony eustachian tube Opacification of mastoid air cells secondary to aditus block 1398 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ fat-saturated MR of the right temporal bone shows an enhancing GTP filling the middle ear Note the dark ossicles within the tumor The aditus ad antrum is blocked, causing fluid to back up in the mastoid air cells (Right) Axial T2WI MR reveals the glomus tumor as intermediate signal intensity lesion in the middle ear compared to the very high signal obstructed mastoid secretions Notice the posterior margin of the mass obstructs the aditus ad antrum (Left) Coronal bone CT shows a small GTP located on the low cochlear promontory just cephalad and medial to the tympanic annulus On a single coronal image, the GTP looks remarkably like an aberrant internal carotid artery (Right) Coronal T1WI C+ FS MR in the same patient reveals the GTP as a subtle foci of enhance inferolateral to the cochlea It would be easy for a radiologist to overlook such a small GTP without a directing clinical history Temporal Bone Meningioma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Benign and Malignant Tumors > Temporal Bone Meningioma Temporal Bone Meningioma Yolanda Y.P Lee, MBChB, FRCR H Ric Harnsberger, MD Key Facts Terminology Synonym: Intratympanic meningioma Definition: Meningiomas involving middle ear (ME) or inner ear (IE) of T-bone Imaging 1399 Diagnostic Imaging Head and Neck Morphology: Dural-based globular or en plaque mass Extends into T-bone via tegmen tympani, IAC, or jugular foramen Bone CT findings Permeative-sclerotic or hyperostotic changes May underestimate extent of tumor MR findings Avidly enhancing mass involving T-bone If dural “tail” present, helps make diagnosis principal sites of origin + specific vector of spread Tegment tympani meningioma → inferiorly → ME Jugular foramen meningioma → centrifugal → ME if superolateral spread present IAC meningioma → inner ear T-bone focused MR with T1 C+ fat-saturated MR shows tumor extent best Clinical Issues Hearing loss Conductive: Tegmen tympani meningioma Mixed: Jugular foramen meningioma Sensorineural: IAC meningioma Otoscope: Vascular retrotympanic mass Treatment: Surgical removal Diagnostic Checklist Identify site of origin, vector of spread, and extent Dural tails (MR) ± permeative sclerotic bone change (CT) may allow specific diagnosis (Left) Coronal graphic of tegmen tympani meningioma reveals en plaque dural origins of the tumor with spread through the thickened tegmen into the upper middle ear The ossicles have been engulfed by the tumor Dural “tails” are visible along the tumor margins (Right) Coronal T1WI C+ MR shows an enhancing en plaque meningioma with dural “tails” in middle cranial fossa floor Transosseous tegmen tumor is visible Downward extension into the ME engulfs the ossicles 1400 Diagnostic Imaging Head and Neck (Left) Coronal graphic of a jugular foramen meningioma depicts the centrifugal spread pattern reaching the IAC , middle ear , and basal cistern When jugular foramen meningioma reaches the middle ear, it mimics glomus jugulare paraganglioma (Right) T1WI C+ fat-saturated MR reveals an extensive jugular foramen meningioma that spreads to the IAC , middle ear , & basal cistern Centrifugal spread pattern, dural-based morphology, & absence of flow voids suggest meningioma diagnosis P.VI(3):47 TERMINOLOGY Synonyms Temporal bone meningioma, intratympanic meningioma Definitions Meningiomas involving temporal bone May extend to middle ear (ME) or inner ear (IE) IMAGING General Features Best diagnostic clue Well-defined, avidly enhancing mass with involvement of T-bone Best seen on T1 C+ MR Dural “tails” highly suggestive of diagnosis Bone CT shows permeative-sclerotic bone change Location From principal sites of origin Tegmen tympani Jugular foramen Internal auditory canal Size ME & IE component small (< 15 mm) Involvement of T-bone & beyond can be large Morphology Dural component appears globular or en plaque ME-mastoid components usually small, lobular, soft tissue mass Transosseous/intraosseous component can be lobular or irregular Vector of spread characteristics from each site Tegmen tympani meningioma spreads inferiorly into middle ear Jugular foramen meningioma spreads centrifugally along dural surfaces in all directions Enters ME via superolaterally route Mimics glomus jugulare paraganglioma when ME involvement occurs IAC meningioma spread from CPA → IAC → intra-labyrinthine structures laterally CT Findings CECT 1401 Diagnostic Imaging Head and Neck 90% of these lesions show strong, uniform enhancement Bone CT General bone change findings When transosseous: Permeative-sclerotic appearance When adjacent to bone surface: Sclerotic or hyperostotic Tegmen tympani meningioma Bone of tegmen thickens, reacts to transosseous meningioma Ossicles encased as spreads into middle ear cavity Ossicular erosion subtle if present Jugular foramen meningoma Surrounding bone shows permeative-sclerotic change Bone changes may underestimate or overestimate tumor extent Intratumoral calcification common MR Findings T1WI Isointense to brain gray matter T2WI Isointense or slightly higher signal than gray matter If calcifications present, scattered low intensity foci T1WI C+ 90% of temporal bone meningiomas strongly enhance Dural component & ME/IE component enhance more strongly than intra-/transosseous component If dural “tail” present, may allow precise diagnosis Tegmen tympani meningioma En plaque dural lesion enhances avidly Middle ear-mastoid component also enhances Jugular foramen meningioma Enhancing mass fills jugular foramen Enhancing lesion extends in all directions through bone & along dural surfaces If extends to ME superolaterally, closely mimics glomus jugulare paraganglioma T1 pre-contrast images show no flow voids IAC meningioma Enhancement of vestibulocochlear (VC) apparatus ± IAC ± CPA meningioma When small can closely mimic vestibular schwannoma Intense, uniform enhancement of VC or dural “tail” distinguishes from schwannoma Angiographic Findings Vascular tumor with immediate tumor blush Prolonged vascular “stain” into venous phase “Sunburst” pattern of enlarged dural feeders may occur with large tumors Middle ear component may be obscured by subtraction artifact Imaging Recommendations Best imaging tool Combined focused imaging of temporal bone with bone CT and MR T-bone CT Gives precise information about status of ossicles, CN7 In larger lesions, pattern of bone change distinguishes meningioma from other diagnoses CT may underestimate tumor extent Thin section focused MR with T1 C+ fat saturated Best to show tumor extent within bone, dura, & ME-IE Protocol advice Bone CT: < mm axial unenhanced sections with multiplanar reformations MR: ≤ mm T2 & T1 fat-saturated C+ axial & coronal sequences DIFFERENTIAL DIAGNOSIS Glomus Jugulare Paraganglioma Clinical: Red-vascular retrotympanic mass T-bone CT: Permeative-destructive bone erosion along superolateral margin of jugular bulb P.VI(3):48 1402 Diagnostic Imaging Head and Neck T1 unenhanced MR: Jugular foramen mass with flow voids (“pepper”) extends into middle ear Glomus Tympanicum Paraganglioma Clinical: Red-vascular retrotympanic mass T-bone CT: Globular mass on cochlear promontory Bony floor of middle ear cavity intact T1 C+ MR: Enhancing mass on cochlear promontory Dehiscent Jugular Bulb Clinical: Blue-vascular posteroinferior retrotympanic mass T-bone CT: Dehisced bony plate between jugular bulb & ME Aberrant Internal Carotid Artery Clinical: Red-vascular retrotympanic mass crosses cochlear promontory T-bone CT: Tubular mass crosses middle ear cavity to rejoin horizontal petrous ICA Enlarged inferior tympanic canaliculus MRA: Asymmetric aberrant vessel Middle Ear Cholesterol Granuloma Clinical: Blue-black retrotympanic mass T-bone CT: Middle ear opacified ± ossicle destruction T1 unenhanced MR: High signal from methemoglobin PATHOLOGY General Features Etiology Arise from arachnoid “cap” cells Embryonic migration anomaly Genetics Long arm deletions of chromosome 22 common NF2 gene inactivated in 60% of sporadic cases Gross Pathologic & Surgical Features Sharply circumscribed, unencapsulated Adjacent dural thickening (collar or “tail”) is usually reactive, not neoplastic Globular (most common) or en plaque types Microscopic Features Wide range of histology with little bearing on outcome Meningothelial, fibrous, transitional, psammomatous, angiomatous, miscellaneous other (microcystic, chordoid, clear cell, secretory) Nests & whorls of “meningiomatous cells” Psammoma bodies: Calcifications Immunohistochemistry: Positive EMA; variable S100 CLINICAL ISSUES Presentation Most common signs/symptoms Hearing loss Conductive: Tegmen tympani meningioma Mixed: Jugular foramen meningioma Sensorineural: IAC meningioma Facial neuropathy uncommon Otoscopic examination: Vascular retrotympanic mass ME component may represent “tip of iceberg” for larger intracranial component Other signs/symptoms Symptoms from larger intracranial component Skull base: Complex cranial neuropathy may involve 5, 7, & Jugular foramen: 9-12 cranial neuropathy possible Clinical profile Middle-aged woman with conductive hearing loss Demographics Age Average age at presentation = 45 years Gender 1403 Diagnostic Imaging Head and Neck M:F = 1:3 Epidemiology 7% of intracranial meningiomas originate from anterior or posterior surface of petrous bone Natural History & Prognosis Slow-growing benign tumor Relatively high recurrence rate, due to difficulty of complete excision Prognosis relates to surgical outcome & complications Hearing usually preserved at preoperative level Facial nerve function good to acceptable Chance of cranial nerve function restoration is low Risk of new lower cranial nerve injury Treatment Complete surgical excision Aggressive surgery advocated because bone invasion hard to see at surgery DIAGNOSTIC CHECKLIST Image Interpretation Pearls Identify site of origin (tegmen, jugular foramen, or IAC) Use imaging findings to make meningioma diagnosis Morphology: Dural-based globular or en plaque mass Bone CT: Permeative-sclerotic, sclerotic, or hyperostotic change MR: Enhancing tumor with “tails” Use combination of CT & MR findings to define full tumor extent SELECTED REFERENCES Hamilton BE et al: Imaging and clinical characteristics of temporal bone meningioma AJNR Am J Neuroradiol 27(10):2204-9, 2006 Gilbert ME et al: Meningioma of the jugular foramen: glomus jugulare mimic and surgical challenge Laryngoscope 114(1):25-32, 2004 Laudadio P et al: Meningioma of the internal auditory canal Acta Otolaryngol 124(10):1231-4, 2004 Thompson LD et al: Primary ear and temporal bone meningiomas: a clinicopathologic study of 36 cases with a review of the literature Mod Pathol 16(3):236-45, 2003 Schick B et al: Magnetic resonance imaging in patients with sudden hearing loss, tinnitus and vertigo Otol Neurotol 22(6):808-12, 2001 Prayson RA: Middle ear meningiomas Ann Diagn Pathol 4(3):149-53, 2000 P.VI(3):49 Image Gallery (Left) Coronal T-bone CT shows thickened, sclerotic tegmen tympani with preserved trabeculation Soft tissue tumor filling the middle ear extends through the tegmen The ossicles are encased but not eroded by this meningioma involving the middle ear (Right) Axial T1WI C+ MR in the same patient reveals the enhancing tegmen meningioma in the floor of the middle cranial fossa Note tumor in aditus ad antrum and permeating the 1404 Diagnostic Imaging Head and Neck thickened bone anterolaterally (Left) Axial bone CT in a patient with an extensive CPA-IAC meningioma (not seen) shows middle ear and sphenoid sinus opacification Note the relative absence of bone changes that would suggest IAC and inner ear involvement (Right) Axial T1WI C+ MR in the same patient reveals the large CPA and IAC meningioma extending into the middle ear to engulf the ossicles Enhanced MR is far better at determining true meningioma extent than bone CT (Left) Axial T-bone CT shows a rare inner ear meningioma with both lucent and sclerotic components The lesion involves the area of the vestibule and basal turn of the cochlea (Courtesy R Wallace, MD.) (Right) Axial T1WI C+ MR in the same patient demonstrates enhancement of the radiolucent areas on CT and relative lack of enhancement in the radiodense areas Middle Ear Schwannoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Benign and Malignant Tumors > Middle Ear Schwannoma Middle Ear Schwannoma Richard H Wiggins, III, MD Key Facts Terminology Primary schwannoma: Tumor primary to middle ear (ME) cavity Tympanic segment CN7 > > Jacobson nerve (CN9 branch), chorda tympani nerve (CN7 branch) Secondary schwannoma: Arises outside middle ear 1405 Diagnostic Imaging Head and Neck Jugular foramen schwannoma involves ME Translabyrinthine CN8 schwannoma Primary inner ear schwannoma → middle ear Imaging Bone CT findings CN7 schwannoma: Well-marginated mass emanating from CN7 canal Translabyrinthine or inner ear schwannoma with ME protrusion: Labyrinth erosions with mass protruding into ME via round or oval window ME schwannoma (from chorda tympani or Jacobson nerve): Focal mass filling ME without involving CN7 canal MR enhanced T1 findings Facial nerve schwannoma: Enhancing lesion contiguous with tympanic or mastoid CN7 Translabyrinthine or inner ear schwannoma: Contiguous with IAC or inner ear spaces ME schwannoma: Mass primary to ME cavity Intramural cysts may be visible Top Differential Diagnoses Congenital middle ear cholesteatoma Glomus tympanicum paraganglioma Middle ear adenoma Clinical Issues Presentation: Conductive hearing loss Otoscopy: Fleshy-white mass behind intact TM (Left) Axial T-bone CT of the left ear reveals the middle ear component of the schwannoma pushing the ossicles laterally The mastoid air cells are opacified as a result of the aditus ad antrum block created by the schwannoma (Right) Axial T1WI C+ MR shows a transotic schwannoma extending from the cerebellopontine angle , through the inner ear , and into the middle ear cavity Original clinical diagnosis in this case was congenital cholesteatoma of the middle ear 1406 Diagnostic Imaging Head and Neck (Left) Axial bone CT reveals a facial nerve schwannoma enlarging the geniculate fossa and tympanic segment of the facial nerve canal The lesion pedunculates into the middle ear cavity, pushing the ossicles posterolaterally (Right) Axial T1WI C+ fat-saturated MR in the same patient shows the enhancing schwannoma in the geniculate ganglion with extension along the tympanic segment into the middle ear IAC fundal tumor is also seen Note the small intramural cyst P.VI(3):51 TERMINOLOGY Synonyms Jacobson nerve schwannoma, chorda tympani schwannoma, pedunculated facial nerve schwannoma Definitions Primary schwannoma: Tumor primary to middle ear (ME) cavity Tympanic segment CN7 > > Jacobson nerve (CN9 branch), chorda tympani nerve (CN7 branch) Secondary schwannoma: Arises outside middle ear Large 9-11 jugular foramen schwannoma eroding into middle ear Translabyrinthine CN8 schwannoma CPA-IAC → inner ear → middle ear Primary inner ear schwannoma → middle ear IMAGING General Features Best diagnostic clue T1 C+ MR shows enhancing mass in middle ear Size Variable, usually < 15 mm Morphology Well-marginated, lobular mass CT Findings CECT Lesion enhances with contrast Bone CT Facial nerve schwannoma Well-marginated mass emanating from CN7 canal Tympanic or mastoid segments Translabyrinthine or inner ear schwannoma with middle ear protrusion Labyrinth erosions with mass protruding into middle ear via round or oval window Middle ear schwannoma (from chorda tympani or Jacobson nerve) Well-marginated mass filling middle ear without involving CN7 canal Bony remodeling when large MR Findings T1WI C+ 1407 Diagnostic Imaging Head and Neck Lobulated, enhancing lesion (differentiates from cholesteatoma) Facial nerve schwannoma: Contiguous with tympanic or mastoid CN7 Translabyrinthine or inner ear schwannoma: Contiguous with IAC or inner ear spaces Middle ear schwannoma: Mass primary to middle ear cavity Intramural cysts may be visible Imaging Recommendations Best imaging tool T1 C+ MR thin sections through temporal bone Protocol advice Thin section T1 C+ MR with diffusion differentiates schwannoma from cholesteatoma Thin section bone CT in axial & coronal planes DIFFERENTIAL DIAGNOSIS Congenital Middle Ear Cholesteatoma Otoscopy: Tan-white mass behind intact TM Child or young adult with conductive hearing loss Bone CT: Lobulated mass, medial to ossicles MR: Nonenhancing middle ear mass DWI: High signal from restricted diffusion Glomus Tympanicum Paraganglioma Otoscopy: Pink-red pulsatile mass behind intact TM Adult patient population Bone CT: Cochlear promontory mass; ME floor intact MR: Enhancing mass Middle Ear Adenoma Rare middle ear tumor Otoscopy: Tan mass behind intact TM Bone CT: Remodeling or invasive-appearing ME mass MR: Enhancing middle ear mass Pars Flaccida Acquired Cholesteatoma Otoscopy: Ruptured TM with visible cholesteatoma Bone CT: Scutum, ossicles eroded ± tegmen tympani & lateral semicircular canal MR: Nonenhancing mass; DWI high signal PATHOLOGY General Features Etiology Neuroectodermal origin Slow-growing, encapsulated, benign lesion CLINICAL ISSUES Presentation Most common signs/symptoms Conductive hearing loss Otoscopy: Fleshy-white mass behind intact TM Treatment Surgical removal DIAGNOSTIC CHECKLIST Consider If middle ear schwannoma diagnosis considered Is tumor from facial nerve canal? Pedunculated facial nerve schwannoma Is tumor primary to middle ear cavity? ME schwannoma ME adenoma ME congenital cholesteatoma Glomus tympanicum paraganglioma SELECTED REFERENCES Huoh KC et al: Chorda Tympani Neuroma Otol Neurotol Epub ahead of print, 2010 Kim CW et al: Primary middle ear schwannoma Am J Otolaryngol 28(5):342-6, 2007 1408 Diagnostic Imaging Head and Neck Middle Ear Adenoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Benign and Malignant Tumors > Middle Ear Adenoma Middle Ear Adenoma Richard H Wiggins, III, MD Key Facts Terminology Middle ear adenoma (MEA) Very rare, benign, glandular tumor Imaging Soft tissue mass + well-pneumatized mastoid (no chronic otitis media findings) Temporal bone CT findings ME mass behind intact TM Indistinguishable on bone CT from glomus tympanicum & pedunculated ME schwannoma Well-pneumatized mastoid (no history of chronic otitis media) May show areas of local bone invasion MR findings If large adenoma present, T1 C+ MR may be helpful in defining lesion extent MEA enhances like glomus tympanicum & pedunculated CN7 schwannoma Enhancement excludes middle ear congenital cholesteatoma Top Differential Diagnoses Glomus tympanicum paraganglioma Pedunculated facial nerve schwannoma Middle ear congenital cholesteatoma Clinical Issues Otoscopy: Tan-pink soft tissue mass behind intact TM Symptoms: Tinnitus, conductive hearing loss Fullness in the ear Mean age at presentation = 45 years Complete surgical excision is treatment of choice ˜ 20% recurrence rate (Left) Axial bone CT through the middle ear shows a soft tissue mass filling the middle ear with polypoid extension into the external auditory canal Mastoid opacification is present due to obstruction at the aditus ad antrum (not shown) (Right) Coronal bone CT in same patient reveals a mass filling the middle ear and extending into the EAC There are permeative changes seen in the middle ear walls but not to the EAC Pathology showed the lesion to be middle ear adenoma 1409 Diagnostic Imaging Head and Neck (Left) Axial bone CT through the low mesotympanum reveals a noninvasive middle ear adenoma extending into the entrance to bony eustachian tube Post-mastoidectomy changes are present (Right) Axial T1 C+ MR in same patient shows a well-circumscribed enhancing lesion within the middle ear cavity The lesion enhancement makes middle ear adenoma a possible diagnosis Without otoscopy, one must also consider glomus tympanicum paraganglioma and middle ear schwannoma P.VI(3):53 TERMINOLOGY Abbreviations Middle ear adenoma (MEA) Synonyms Adenomatous tumor of middle ear, aldosteronoma Definitions Very rare, benign, glandular tumor IMAGING General Features Best diagnostic clue Soft tissue mass + well-pneumatized mastoid (no chronic otitis media findings) Location Middle ear cavity proper (mesotympanum) Size Early symptoms → small (< 10 mm) at diagnosis Morphology Often irregularly marginated CT Findings CECT Will enhance but difficult to see Bone CT Mass within middle ear (ME) behind intact TM Indistinguishable on bone CT from glomus tympanicum & pedunculated ME schwannoma May show areas of local bone invasion MR Findings T1WI Low to intermediate signal lesion T1WI C+ Enhancing soft tissue mass in ME Imaging Recommendations Best imaging tool Temporal bone CT Protocol advice 1410 Diagnostic Imaging Head and Neck Axial & coronal bone CT images without contrast If large adenoma present, T1 C+ MR may be helpful in defining lesion extent Nuclear Medicine Findings Octreotide scan Avid uptake similar to other neuroendocrine tumors DIFFERENTIAL DIAGNOSIS Glomus Tympanicum Paraganglioma Otoscopy: Pulsatile, red retrotympanic mass No history of chronic otitis media CT: Noninvasive cochlear promontory mass Middle ear floor intact MR: T1 C+ MR shows enhancing mass Pedunculated Facial Nerve Schwannoma Otoscopy: Avascular mass mimics congenital cholesteatoma T1 C+ MR: Enhancing mass connected to CN7 Middle Ear Congenital Cholesteatoma Clinical: Child; no history of chronic otitis media CT: When large, typically erosive MR: T1 C+ MR shows no enhancement PATHOLOGY General Features Etiology Benign, indolent epithelial tumors of ME that rarely invade bone MEA arises from modified respiratory mucosa Gross Pathologic & Surgical Features Pink, yellow, gray, or reddish-brown firm, shimmering, soft tissue mass Usually poorly vascularized CLINICAL ISSUES Presentation Most common signs/symptoms Otoscopy: Tan-pink soft tissue mass behind intact TM Conductive hearing loss Other signs/symptoms Ear fullness Tinnitus Demographics Age Mean age at presentation = 45 years Epidemiology MEA is very rare middle ear tumor Natural History & Prognosis Slow-growing benign tumor If aggressive type, facial nerve injury possible Recurrence of tumor common problem May progress to become malignant adenocarcinomas Treatment Complete surgical excision is treatment of choice DIAGNOSTIC CHECKLIST Consider If T1 C+ MR shows enhancing middle ear mass, consider MEA, glomus tympanicum paraganglioma, & pedunculated facial nerve schwannoma Image Interpretation Pearls Clinical otoscopic examination & imaging findings are both nonspecific Reporting Tips Describe extension outside of middle ear Follow-up is required: 20% recurrence rate SELECTED REFERENCES Zan E et al: Middle ear adenoma: a challenging diagnosis AJNR Am J Neuroradiol 30(8):1602-3, 2009 1411 Diagnostic Imaging Head and Neck Temporal Bone Rhabdomyosarcoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Benign and Malignant Tumors > Temporal Bone Rhabdomyosarcoma Temporal Bone Rhabdomyosarcoma Hilda E Stambuk, MD Key Facts Terminology Definition: Rare, aggressive, destructive temporal bone lesion generally arising in middle ear, skeletal muscle, or pluripotential mesenchymal tissue in pediatric population Imaging CT findings Middle ear-mastoid destructive mass Lytic, destructive bone & ossicle changes MR findings T1 C+: Enhances homogeneously T2: Intermediate to high signal tumor Coronal images best for intracranial extension through tegmen, mastoid roof ± skull base foramina Both CT & MR recommended to stage skull base destruction & intracranial extension Standard work-up Bilateral bone marrow biopsy, CSF analysis Chest CT/CXR & PET/CT Top Differential Diagnoses Acquired pars flaccida cholesteatoma Acquired pars tensa cholesteatoma Middle ear cholesterol granuloma T-bone Langerhans cell histiocytosis Acute otomastoiditis with coalescence Clinical Issues Most common soft tissue sarcoma in children 50% of rhabdo in children occurs in H&N 7% of H&N rhabdo occur in T-bone Orbit > nasopharynx/masticator space & associated spaces > sinonasal > T-bone Child under years with chronic otitis media Plus otorrhea, ear pain, EAC polyp (Left) Axial T-bone CT of right ear shows complete middle ear-mastoid opacification Note subtle lytic change in the mastoid air cells and medial cortex , indicating an aggressive process In the absence of infectious symptoms, rhabdomyosarcoma should be considered (Right) Axial T1WI C+ FS MR in the same patient reveals diffusely enhancing tumor of middle ear , aditus , & mastoid antrum Otomastoiditis with middle ear effusion or cholesteatoma would not enhance 1412 Diagnostic Imaging Head and Neck (Left) Axial T2WI fat-saturated MR demonstrates middle ear rhabdomyosarcoma obstructing aditus ad antrum Although tumor is hyperintense, it is slightly lower in signal than obstructed secretions in mastoid air cells (Right) Axial left ear bone CT reveals a destructive middle ear-mastoid rhabdomyosarcoma excavating the anterolateral mastoid air cells and destroying the lateral cortex This lesion would be be clinically palpable P.VI(3):55 TERMINOLOGY Abbreviations Middle ear (ME) rhabdomyosarcoma (rhabdo) Synonyms “Parameningeal type” rhabdomyosarcoma Definitions Rare pediatric aggressive, destructive temporal bone lesion generally arising in middle ear Skeletal muscle or pluripotential mesenchymal tissue origin IMAGING General Features Best diagnostic clue T-bone CT: Destructive middle ear-mastoid mass T1 fat-saturation C+ MR: Irregular, invasive, enhancing middle ear-mastoid mass in child Location Middle ear ± mastoid soft tissue mass Possible areas of extension Lateral extension commonly into external auditory canal (EAC) with aural polyp Medial extension into internal auditory canal (IAC) via CN7 canal Cephalad into middle cranial fossa via mastoid or tympanic tegmen Posterior into posterior cranial fossa: Direct extension or perineural spread (CN7 canal → IAC → posterior fossa) Inferior via carotid canal or jugular foramen into nasopharyngeal carotid space Size Depends on tumor location: Most > cm Morphology Poorly defined, locally destructive mass CT Findings CECT Mass homogeneously enhances Nodal metastases rare at presentation unless intracranial or extracranial extension present 30% incidence of nodal metastases in non-T-bone rhabdo head and neck primary sites Bone CT Middle ear-mastoid destructive mass Often with associated EAC extension 1413 Diagnostic Imaging Head and Neck Skull base & cranial nerve foraminal involvement common MR Findings T1WI Iso- to hypointense mass T2WI Hyper- to isointense, usually homogeneous unless necrotic or hemorrhagic Obstructed mastoid secretions higher signal T1WI C+ Tumor enhances homogeneously Coronal images best for detecting intracranial extension through tegmen, mastoid roof ± skull base foramina Focal thickened enhancing dura suggests dural involvement Nuclear Medicine Findings Bone scan Middle ear & adjacent skull base have increased uptake PET Cost effective for initial staging of locally advanced tumors Useful for post-treatment surveillance Imaging Recommendations Best imaging tool Both CT & MR recommended to stage skull base destruction, middle ear disease, & intracranial extension Coronal T1 FS C+ to identify intracranial & extracranial extension Protocol advice Complex skull base mass, with potential for intracranial extension, distant metastases, & cervical adenopathy requires careful multimodality work-up Thin section temporal bone CT in axial plane, with coronal & sagittal reformations Multiplanar MR pre- & post-contrast Cervical adenopathy can be staged with either CECT, MR, or PET Standard rhabdomyosarcoma work-up Bilateral bone marrow biopsy CSF analysis Chest CT/x-ray PET/CT is replacing bone scan DIFFERENTIAL DIAGNOSIS Acquired Pars Flaccida Cholesteatoma Clinical: Pars flaccida tympanic membrane (TM) perforation or retraction ± visible cholesteatoma Bone CT: Scutum & ossicle erosion; soft tissue in Prussak space Unless large, less extensive bone changes than rhabdo Acquired Pars Tensa Cholesteatoma Clinical: Pars tensa TM perforation with visible cholesteatoma Bone CT: Soft tissue medial to ossicles with erosions Middle Ear Cholesterol Granuloma Clinical: Retrotympanic “vascular” blue hue Past history of multiple prior ear infections Imaging: MR shows high T1& high T2 signal mass in middle ear ± mastoid T-Bone Langerhans Cell Histiocytosis Clinical: Pediatric patient with postauricular swelling Usually no cranial nerve palsy Bone CT: Unilateral or bilateral destructive mastoid-centered mass Often bilateral or other associated osseous lesions May strongly mimic T-bone rhabdo Biopsy needed to make final diagnosis Acute Otomastoiditis with Coalescence Clinical: Fever, mastoid tenderness in child P.VI(3):56 Bone CT: Opacified middle ear-mastoid Mastoid trabecular breakdown mimics tumor 1414 Diagnostic Imaging Head and Neck Clinical setting key differentiator PATHOLOGY General Features Etiology Malignant tumor of skeletal muscle vs pluripotential mesenchymal cells Genetics Most cases sporadic Deletion from 11p15 is characteristic for embryonal subtype Increased incidence in children with p53 tumor suppressor gene mutation Staging, Grading, & Classification T-bone rhabdo considered “parameningeal” No single standard staging system as very rare tumor International Rhabdomyosarcoma Study Group grading system used clinically Group I: Complete resection of localized disease Group II: Completely resected regional disease or microscopic residual Group III: Gross residual disease Group IV: Distant metastases; worst prognosis Gross Pathologic & Surgical Features Smooth, lobulated necrotic or hemorrhagic tumor Microscopic Features histologic subtypes: Pleomorphic, alveolar, botryoid, & embryonal Embryonal rhabdo: Most common subtype in head & neck Anaplastic, small, round, & spindle-shaped cells with hyperchromic nuclei & granular acidophilic cytoplasm Immunohistochemistry positive for desmin, vimentin, antibodies to muscle specific actin, antimyogenin, & MYOD1 In all subtypes, rhabdomyoblasts (cell of origin) are present CLINICAL ISSUES Presentation Most common signs/symptoms Mimics chronic otitis media with chronic otorrhea (sometimes bloody) & ear pain Other signs/symptoms Aural (external auditory canal) polyp CN7 palsy Other signs/symptoms Hearing loss, cervical lymph nodes Clinical profile Child under years with chronic otitis media, otorrhea, & ear pain, EAC polyp unresponsive to medical management Demographics Age Bimodal; occurring in children (2-5 years) and late teens (15-19 years) Rarely can occur in adults Epidemiology Rhabdomyosarcoma is most common soft tissue sarcoma in children 50% of rhabdo in children occurs in H&N 7% of H&N rhabdos occur in T-bone Head & neck sites of origin Orbit > nasopharynx/masticator & associated spaces > sinonasal > T-bone Natural History & Prognosis Delay to diagnosis common Child initially treated for acute or chronic otitis media Botryoid type: Most favorable subtype Alveolar type: Most unfavorable subtype Distant metastases lungs > > bone, liver, brain T-bone rhabdo parameningeal type with high probability of meningeal extension at time of diagnosis Extremely poor prognosis if intracranial spread & distant metastases Treatment T-bone tumors rarely resectable 1415 Diagnostic Imaging Head and Neck Role of surgery limited to biopsy Combined multidrug chemotherapy & adjuvant radiation DIAGNOSTIC CHECKLIST Consider Clinical: Consider T-bone rhabdo if aural polyp or CN7 palsy found in child with “chronic otitis” Imaging: Consider T-bone rhabdo if unilateral destructive T-bone mass in child Langerhans cell histiocytosis of T-bone can exactly mimic T-bone rhabdo Image Interpretation Pearls Both CT & MR important for staging primary site, local disease, & nodal ± distant metastases Coronal plane needed to assess integrity of skull base & detect intracranial extension MR is preferred modality PET/CT: Distant metastases and surveillance scanning Replacing bone scan in rhabdo work-up Reporting Tips Describe location and extent of osseous destruction Note intra- and extracranial extension Note perivascular & perineural spread SELECTED REFERENCES Sbeity S et al: Temporal bone rhabdomyosarcoma in children Int J Pediatr Otorhinolaryngol 71(5):807-14, 2007 Reid SR et al: Temporal bone rhabdomyosarcoma presenting as acute peripheral facial nerve paralysis Pediatr Emerg Care 22(10):743-5, 2006 Lehman DA et al: Radiology forum: quiz case Diagnosis: rhabdomyosarcoma with perineural intracranial invasion Arch Otolaryngol Head Neck Surg 127(3):331-2, 2001 Wiatrak BJ et al: Rhabdomyosarcoma of the ear and temporal bone Laryngoscope 99(11):1188-92, 1989 P.VI(3):57 Image Gallery (Left) Small lytic lesion in right petrous apex represents early rhabdomyosarcoma in year old complaining of right ear pain This lesion can be easily disregarded as trapped fluid but likely would have appeared more extensive on MR (Right) Axial CECT in the same patient again demonstrates the right petrous apex lesion Notice the subtle soft tissue in the anteromedial petrous apex-Meckel cave area Neither finding was worrisome enough on this image to be described as possible tumor 1416 Diagnostic Imaging Head and Neck (Left) Axial bone CT months later in same patient with new impairment of right eye movement shows an obvious expansile, destructive petrous apex lesion The medial bony otic capsule is eroded Note that the middle ear & mastoid air cells are spared from involvement (Right) Axial T2 fat-saturated MR shows classic homogeneous T2 hyperintensity associated with rhabdomyosarcoma of the T-bone petrous apex Note cavernous sinus invasion with cavernous ICA partially engulfed by tumor (Left) Axial enhanced T1 MR of the same patient reveals the homogeneously enhancing petrous apex rhabdomyosarcoma The cavernous sinus invasion is visible The cavernous ICA is partially engulfed and anteriorly displaced (Right) Coronal T1WI C+ FS MR in a patient with facial neuropathy shows an invasive mass involving the deep parotid space , middle ear , and tegmen-dura This rhabdomyosarcoma was primarily extracranial but invaded temporal bone secondarily Miscellaneous Temporal Bone Cephalocele > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Miscellaneous > Temporal Bone Cephalocele Temporal Bone Cephalocele Yolanda Y.P Lee, MBChB, FRCR H Ric Harnsberger, MD Key Facts Terminology 1417 Diagnostic Imaging Head and Neck Synonyms: Temporal lobe meningocele, encephalocele, or meningo-encephalocele; defined by content T-bone cephalocele: Protrusion of cranial contents into middle ear (ME) or mastoid through dehiscence of tegmen Imaging CT: Tegmen tympani (ME roof) or mastoideum (mastoid roof) dehiscence Tegmen defect does not necessarily result in cephalocele MR: Temporal lobe ± dura & CSF herniation into ME cavity or mastoid Top Differential Diagnoses Large cholesteatoma with tegmen dehiscence Middle ear cholesterol granuloma T-bone arachnoid granulation Pathology T-bone cephalocele has multiple etiologies Chronic otitis media ± cholesteatoma: After operation more frequent than before operation Iatrogenic: Post-mastoidectomy Spontaneous/congenital/idiopathic Post-traumatic: Usually after severe T-bone trauma Natural history: Delayed presentation of cephalocele develops over time with CSF pulsation, variation of intracranial pressure, & low-grade inflammation Clinical Issues 85% conductive or mixed hearing loss Surgical treatment: Immediate closure of defect is key Threat of meningitis catalyzes this action (Left) Coronal CT in a patient with history of severe temporal bone trauma and conductive hearing loss reveals complete absence of the tegmen tympani with cephalocele surrounding the head of the malleus (Right) Coronal T1WI C+ FS MR in a patient with “fluid” behind an intact tympanic membrane shows a spontaneous tegmen tympani area cephalocele Enhancing tissue in the middle ear and dural enhancement is seen At surgery, CSF leak accompanied the cephalocele 1418 Diagnostic Imaging Head and Neck (Left) Coronal bone CT in a patient with CSF leak following mastoidectomy demonstrates a broad tegmen dehiscence accompanied by opacification of the epitympanum and lateral mastoid air cells below the area of dehiscence Possibility of cephalocele was raised by this coronal CT appearance (Right) Coronal T1 MR in the same patient reveals a hammock-like encephalocele of the temporal lobe through tegmen rent High signal surgical fat packing is visible below the encephalocele P.VI(3):59 TERMINOLOGY Synonyms Temporal lobe meningocele, encephalocele, or meningo-encephalocele; defined by content Definitions Protrusion of cranial contents into middle ear (ME) or mastoid through dehiscence of tegmen IMAGING General Features Best diagnostic clue CT: Tegmen tympani (ME roof) or mastoideum (mastoid roof) dehiscence MR: CSF ± dura ± temporal lobe into ME cavity or mastoid Location Tegmen mastoideum > tegmen tympani Morphology “Hourglass” or “hammock” shapes possible Imaging Recommendations Best imaging tool T-bone CT used initially to define bony dehiscence Focused coronal T2 MR best for cephalocele contents T1 C+ MR shows intracranial complication Both CT & MR coronal views are key CT Findings Bone CT Focal bone defect in tegmen tympani or mastoideum Other associated findings possible Mastoidectomy or other surgical findings Acute or chronic complex fractures If sporadic, superior semicircular canal dehiscence may also be present Opacified ME-mastoid air cells if CSF leak MR Findings T2WI Small defects usually associated with dural defect → cephalocele Large defects may contain meningoencephalocele Dura may be thin, or dural rent may be present 1419 Diagnostic Imaging Head and Neck If associated dural leak, high signal CSF in middle ear-mastoid T1WI C+ Possible rim enhancement (similar to intracranial hypotension) DIFFERENTIAL DIAGNOSIS Large Cholesteatoma with Tegmen Dehiscence Imaging: Nondependent soft tissue mass with ossicular erosion (CT) Restricted diffusion on DWI if large on MR Middle Ear Cholesterol Granuloma Imaging: High T1 & T2 MR signal characteristic T-Bone Arachnoid Granulation Imaging: Focal cortical defect on CT Enhances on T1 C+ MR PATHOLOGY General Features Etiology Chronic otitis media ± cholesteatoma Most common direct or indirect cause Iatrogenic 50% associated with cholesteatoma After canal wall down > canal wall up mastoidectomy Spontaneous/congenital/idiopathic Very rare condition affecting in 5-10,000 10-20% in skull base (T-bone/sphenoid bone) Post-traumatic: Usually after severe T-bone trauma Associated abnormalities Morbid obesity Superior semicircular canal dehiscence Gross Pathologic & Surgical Features Herniated brain usually nonfunctional Microscopic Features Normal or necrotic CNS contents CLINICAL ISSUES Presentation Most common signs/symptoms 85% conductive or mixed hearing loss Due to underlying disease, CSF effusion, or mass effect from herniated brain Complicated cephalocele: CSF otorrhea, meningitis, brain or epidural abscess, epilepsy Other signs/symptoms Pulsatile tinnitus, facial nerve palsy, trigeminal neuralgia, headache Otoscope: Pulsatile ME mass Demographics Age Usually presents > 50 years Chronic otitis media related or iatrogenic group may present earlier Natural History & Prognosis Tegmen defect does not always result in cephalocele Delayed presentation of cephalocele develops over time with CSF pulsation, variation of intracranial pressure, & low-grade inflammation Treatment Immediate closure of defect is mandatory due to risk of life-threatening meningitis SELECTED REFERENCES Sanna M et al: Management of meningoencephalic herniation of the temporal bone: Personal experience and literature review Laryngoscope 2009 Aug;119(8):1579-85 Review Erratum in: Laryngoscope 120(1):217, 2010 Ossicular Prosthesis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Middle Ear-Mastoid > Miscellaneous > Ossicular Prosthesis Ossicular Prosthesis Yolanda Y.P Lee, MBChB, FRCR 1420 Diagnostic Imaging Head and Neck H Ric Harnsberger, MD Key Facts Terminology Ossicular replacement prosthesis (ORP) Ossiculoplasty: Surgical reconstruction of malfunctioned ossicular chain to improve or to maintain residual conductive hearing function Common ORP types Stapes prosthesis Incus interposition graft Partial ossicular replacement prosthesis (PORP) Total ossicular replacement prosthesis (TORP) Imaging T-bone CT = best imaging tool All or part of ossicular chain, replaced by tissue graft (autograft or homograft) or allograft May over- or underestimate (< mm) size of metallic ORP due to metallic artifacts May underestimate fluoroplastic portion of ORP if surrounded by soft tissue Allow some leeway when commenting on medial-lateral position of ORP Prosthesis malfunction CT findings Displacement, dislocation, protrusion, extrusion Abnormal soft tissue embedded ORP Recurrent/progressive primary disease (cholesteatoma, otosclerosis, tympanosclerosis) Prosthetic MR safety Many modern ORP are tested safe or conditional at 1.5T or 3T; check product-specific guideline Top Differential Diagnoses Chronic otitis media with tympanosclerosis Post-traumatic incus dislocation Foreign body in middle ear Semi-implantable direct drive hearing device (Left) Coronal graphic shows a titanium PORP connecting the tympanic membrane (TM) to capitulum of stapes A cartilage graft is often placed between TM & head of prosthesis to reduce incidence of implant extrusion Prostheses connecting any part of ossicular chain to capitulum are called PORP (Right) Coronal graphic shows a TORP connecting the TM to the oval window A piston-based TORP is used with stapedectomy Intervening cartilage cap is between TM & prosthesis head 1421 Diagnostic Imaging Head and Neck (Left) Coronal graphic shows a type of stapes piston prosthesis The incus end hooks to incus long process The piston base connects to oval window via stapedotomy (Right) Coronal graphic reveals an example of incus interposition graft where the incus is sculpted & rotated to connect handle of malleus to capitulum of stapes A groove is created in the remaining long process of incus to anchor it to the manubrium A hole is drilled at incus body to accommodate the stapes capitulum P.VI(3):61 TERMINOLOGY Synonyms Ossicular replacement prosthesis (ORP) Definitions Ossiculoplasty: Surgical reconstruction of malfunctioned part of ossicular chain to improve or to maintain conductive hearing function Materials: Allograft > autograft > > homograft Allograft: Synthetic ossicular replacements Autograft: Patient's own ossicle used Homograft: Radiated, frozen human ossicles Homograft use ↓ ↓ in 1990s over concern of risk for disease transmission (e.g., AIDS) Common ORP Types Stapes prosthesis Incus interposition graft Partial ossicular replacement prosthesis (PORP) Total ossicular replacement prosthesis (TORP) IMAGING General Features Best diagnostic clue All or part of ossicular chain (OC) replaced by tissue graft (autograft or homograft) or allograft Auto- or homograft: Ossicular bone density Allograft: Metallic, soft tissue density, or combination Prosthetic malfunction suggested by displacement, presence of abnormal soft tissue ± recurrence of conductive hearing loss (CHL) Findings of underlying disease (e.g., otosclerosis), their complications (e.g., middle ear [ME] erosion in cholesteatoma) or related surgery (mastoidectomy) may be seen Location Mesotympanum (middle ear cavity proper) Radiographic Findings Radiography Only metallic devices can be appreciated Insufficient for diagnosis CT Findings 1422 Diagnostic Imaging Head and Neck Bone CT Stapes prosthesis Most commonly seen in otosclerosis setting Stapes allograft connects long process of incus to stapes footplate of oval window (OW) “Missing” all or part of stapes superstructure OW interaction usually through hole in stapes footplate (stapedotomy) OW insertion need not be central to function normally Allograft materials variably visible Metallic (titanium, stainless steel, platinum), soft tissue density (fluoroplastic), or combination main types: Wire loop, stapes piston > > bucket handle or homemade “Anatomical” parts designated incus end (hook/clip/bucket handle), shaft and base (wire loop/piston) Incus interposition graft Most commonly seen in chronic otitis media (COM) Incus rotated & resculpted to connect malleus with stapes capitulum Normal incus is “missing” Typically patient's own incus body (autograft) Malleus head, cortical bone, or cartilage graft may be used if incus not available Looks like “dislocated” incus if history of surgery is not known! TORP or PORP More commonly seen in advanced COM or cholesteatoma TORP: Replace entire OC, connect TM to OW “Anatomically” TORP head on TM, shaft and base on OW Shaft is straight from TM to OW PORP: Replace part of OC to articulate with stapes superstructure Straight if connects TM to capitulum Short & angled if incudostapedial joint only replaced Materials: Metallic (titanium), bone density (ceramic), plastic, or combination Wide variety of designs available Specific name depends on manufacturer TM looks thickened due to use of cartilage cap Prosthetic malfunction on bone CT General CT findings Dislocation/subluxation: Most commonly occurs in early postoperative period (< weeks) Before fibrosis secures ORP Lateralization: Prosthesis drifts away, widened gap with OW Protrusion: Prosthesis protrudes into vestibule (vertigo) Abnormal soft tissue visible on scan Embedded ORP: Represents granulation, fibrosis, or recurrent cholesteatoma At oval window: Granulation-fibrosis; soft tissue develops 4-6 week after surgery (excessive stapedectomy) Ankylosis with ME wall Higher risk if ossicle touches ME wall & with Gelfoam (used with TORP) Recurrent/progressive COM, cholesteatoma, otosclerosis Surgical complication: Rare, occur early Pneumolabyrinth or unexplained fluid in ME may suggest perilymph fistula ME wall thickening & soft tissue may suggest postoperative otitis media Specific stapes prosthesis malfunction findings Necrosis of long process of incus: Related to manipulation & crimping Malleoincudal joint subluxation: Abnormal torque from too long/malpositioned prosthesis Specific incus interposition malfunction findings Incus necrosis or recurrent cholesteatoma Specific TORP/PORP malfunction findings P.VI(3):62 Extrusion of prosthesis through TM Incidence reduced with interposing cartilage cap between TM & ORP head 1423 Diagnostic Imaging Head and Neck Imaging Recommendations Best imaging tool Temporal bone CT axial & coronal ˜ 0.6 mm slices best for evaluating ossicle status & protheses complications Ossicle relationships best seen on coronal CT TORP & PORP MR safety Many modern prostheses are tested safe or conditional at 1.5T or 3T Be sure to check specific product against known MR safety DIFFERENTIAL DIAGNOSIS COM with Tympanosclerosis If history of ossicular surgery unknown, misdiagnosis possible Must know normal prosthesis appearances Post-Traumatic Incus Dislocation Temporal bone trauma history key May appear identical to incus interposition graft Incus may be found anywhere in middle ear or EAC Middle Ear Foreign Body Clinical history is crucial Semi-Implantable Direct Drive Hearing Device Designed for moderate to severe sensorineural hearing loss, with intact ME ossicles May soon be used for CHL Implantable components consist of floating mass transducer anchored to incus Receiver in retroauricular subcutaneous layer (called vibrating ossicular prosthesis or VORP) Connecting wire visible PATHOLOGY General Features Etiology Need for ossicular chain surgery driven by multiple clinical scenarios COM & cholesteatoma account for 80% of ossicular injury Fenestral otosclerosis Tympanosclerosis Trauma Congenital or idiopathic ossicle fusion Gross Pathologic & Surgical Features Incus erosion = most commonly encountered defect Incudostapedial joint erosion > absent incus > absent incus & stapes superstructure Stapes foot plate fixation due to otosclerosis, tympanosclerosis, or congenital stapes fixation Malleal-incudal fixation may be congenital or due to tympanosclerosis CLINICAL ISSUES Presentation Most common signs/symptoms Conductive hearing loss Other signs/symptoms Postoperative symptoms suggesting prosthesis malfunction Recurrent conductive hearing loss or vertigo weeks to months after surgery Demographics Age All ages Natural History & Prognosis Early postoperative malfunction relates to surgical error or graft subluxation/dislocation Delayed prosthetic malfunction from mechanical failure, scarring, or recurrent/progressive disease Treatment Treat recurrent otitis media ± cholesteatoma first Prosthesis malfunction requires replacement DIAGNOSTIC CHECKLIST Consider Consider prosthesis subluxation if history of recurrent CHL or vertigo Image Interpretation Pearls Must have clinical & surgical history (including type of prosthesis used) 1424 Diagnostic Imaging Head and Neck Must have knowledge of the following prior to evaluation Normal ossicular anatomy Normal prosthesis appearance Detailed surgical history SELECTED REFERENCES Zeitler DM et al: Are postoperative hearing results better with titanium ossicular reconstruction prostheses? Laryngoscope 120(1):2-3, 2010 Streitberger C et al: Vibrant Soundbridge for hearing restoration after chronic ear surgery Rev Laryngol Otol Rhinol (Bord) 130(2):83-8, 2009 Burmeister HP et al: Three-dimensional imaging of active and passive middle ear prostheses using multislice computed tomography J Comput Assist Tomogr 32(2):304-12, 2008 Fritsch MH et al: Phylogeny of the stapes prosthesis Otol Neurotol 29(3):407-15, 2008 Rangheard AS et al: Postoperative complications in otospongiosis: usefulness of MR imaging AJNR Am J Neuroradiol 22(6):1171-8, 2001 Pickuth D et al: Vertigo after stapes surgery: the role of high resolution CT Br J Radiol 73(873):1021-3, 2000 Stone JA et al: CT evaluation of prosthetic ossicular reconstruction procedures: what the otologist needs to know Radiographics 20(3):593-605, 2000 Hirsch BE et al: Imaging of ossicular prostheses Otolaryngol Head Neck Surg 111(4):494-6, 1994 P.VI(3):63 Image Gallery (Left) Axial bone CT in a patient with post stapes implant vertigo and conductive hearing loss shows a stapes prosthesis protruding into the vestibule through oval window Notice the fenestral otosclerosis plaque in the fissula ante fenestram along the anterior margin of the oval window (Right) Coronal bone CT in the same patient shows that the head of stapes prosthesis articulates with long process of incus The oval window attachment is out of plane 1425 Diagnostic Imaging Head and Neck (Left) Axial bone CT demonstrates incus interposition graft The incus is rotated to connect the manubrium of the malleus with capitulum of the stapes A hole has been drilled in the incus body to receive capitulum (Right) Coronal bone CT shows a metallic PORP The head , shaft, and base project straight across to the stapes capitulum Focal soft tissue thickening at TM represents the cartilage cap commonly used with PROP & TROP to reduce risk of extrusion (Left) Coronal bone CT shows a metallic PROP A soft tissue nodule with erosion of inferior tympanic annulus represents recurrent cholesteatoma Evidence of mastoidectomy is related to previous congenital cholesteatoma excision (Right) Coronal bone CT in a patient with recurrent conductive hearing loss reveals a TORP connecting TM to oval window Notice the shaft has a beaded tip that is lateralized away from the oval window membrane Section - Inner Ear Pseudolesions Subarcuate Canaliculus > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Pseudolesions > Subarcuate Canaliculus Subarcuate Canaliculus H Ric Harnsberger, MD 1426 Diagnostic Imaging Head and Neck Key Facts Terminology Definition: Normal temporal bone osseous canal that passes through arch of superior semicircular canal conveying subarcuate artery to otic capsule Imaging Osseous canal passing through superior semicircular canal Infant: Tubular + CSF in subarachnoid space Adult: Linear with sclerotic margins on CT; unseen on MR Top Differential Diagnoses Large vestibular aqueduct (IP-II) Prominent cochlear aqueduct Temporal bone fracture involving inner ear Pathology Maximum size of subarcuate canaliculus at 21 weeks embryo development Then ↓ in size to form subarcuate fossa & canaliculus Contains subarcuate artery & vein SAC before years of age Dural-lined subarachnoid space connected to CPA cistern SAC after years of age Involutes with disappearance of dura, subarachnoid space, and CSF Diagnostic Checklist SAC may be mistaken for pathology In infant: Inner ear anomaly In adult: T-bone fracture SAC = potential route of spread of infection (Left) Axial bone CT in a month old shows a prominent subarcuate canaliculus extending from the medial petrous ridge , beneath the superior semicircular canal , to the medial mastoid antrum wall Note the thin bony wall at its medial margin (Right) Axial T2 MR in the same infant shows the conspicuous high signal subarcuate canaliculus Early in life (< years of age) this developing structure is a dural-lined subarachnoid space filled with high signal CSF that may be confused with pathology 1427 Diagnostic Imaging Head and Neck (Left) Axial temporal bone CT of an adult right ear shows a normal, linear, arching subarcuate canaliculus passing from medial petrous ridge under the superior semicircular canal to the lateral wall of the mastoid antrum (Right) Coronal right ear temporal bone CT in the same adult reveals a normal curvilinear subarcuate canaliculus passing from the subarcuate fossa of the medial petrous ridge beneath the superior semicircular canal to the medial wall of the mastoid antrum P.VI(4):3 TERMINOLOGY Abbreviations Subarcuate canaliculus (SAC) Synonyms Petromastoid canal, subarcuate channel or tract, subarcuate artery canal Definitions SAC: Normal temporal bone osseous canal that passes through arch of superior semicircular canal conveying subarcuate artery to otic capsule IMAGING General Features Best diagnostic clue Osseous canal passing through superior semicircular canal (SSC) Infant: Tubular + CSF in subarachnoid space Adult: Linear with sclerotic margins on CT CT Findings Bone CT Infant under years of age SAC passes under SSC Measures 2-3x cross-sectional SSC dimension Child > years of age Adult: SAC seen as “dark line” passing under SSC Measures ≤ cross-sectional SSC dimension MR Findings T2WI Infant under years of age CSF intensity passage from subarcuate fossa medially to lateral wall of mastoid antrum Passes under SCC Child > years of age SAC not visible Imaging Recommendations Best imaging tool T-bone CT without contrast best shows SAC DIFFERENTIAL DIAGNOSIS 1428 Diagnostic Imaging Head and Neck Large Vestibular Aqueduct (IP-II) CT: Large bony vestibular aqueduct posterior to IAC Connects to crus communis MR: Large endolymphatic sac Prominent Cochlear Aqueduct May be mistaken for fracture or SAC CT: Parallel & inferior to IAC Temporal Bone Fracture Clinical history of significant head trauma CT: Lacks sclerotic margins of subarcuate canaliculus PATHOLOGY General Features Embryology-anatomy 21st week of embryonal development, maximum size of subarcuate sinus Then ↓ in size to form subarcuate fossa & canaliculus Contains subarcuate artery & vein SAC before years of age is dural-lined subarachnoid space connected to CPA cistern After years of age involutes with disappearance of dura, subarachnoid space, and CSF Adult subarcuate canaliculus Mean length of SAC = 10.5 mm Approximately 50% of canals have width between 0.5-1.0 mm Other 50% > mm (rarely ≥ mm) Subarcuate artery Subarcuate artery arises from labyrinthine artery medial to IAC Labyrinthine artery arises from basilar artery or anterior inferior cerebellar artery (AICA) Subarcuate artery may arise directly from AICA Enters subarcuate fossa to travel in SAC Supplies otic capsule, semicircular canals, & posterior wall vestibule Distal branches anastomose with branches from superficial petrosal artery, stylomastoid, posterior meningeal & occipital arteries CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic normal variant Clinical profile Conspicuous structure in infant Incidentally noted during work-up for other clinical findings Natural History & Prognosis Normal anatomic variant Treatment None needed; normal anatomic structure DIAGNOSTIC CHECKLIST Consider SAC may be mistaken for pathology In infant: Inner ear anomaly In adult: T-bone fracture SAC = potential route of spread of infection SELECTED REFERENCES Migirov L et al: Radiology of the petromastoid canal Otol Neurotol 27(3):410-3, 2006 Krombach GA et al: The petromastoid canal on computed tomography Eur Radiol 12(11):2770-5, 2002 Tekdemir I et al: The subarcuate canaliculus and its artery— a radioanatomical study Ann Anat 181(2):207-11, 1999 Hilding DA: Petrous apex and subarcuate fossa maturation Laryngoscope 97(10):1129-35, 1987 Wilbrand H et al: The subarcuate fossa and channel A radioanatomic investigation Acta Radiol Diagn (Stockh) 27(6):637-44, 1986 Mazzoni A: The subarcuate artery in man Laryngoscope 80(1):69-79, 1970 Cochlear Cleft > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Pseudolesions > Cochlear Cleft 1429 Diagnostic Imaging Head and Neck Cochlear Cleft Caroline D Robson, MBChB Key Facts Terminology Synonyms for cochlear cleft Localized pericochlear hypoattenuating foci Cochlear capsule space Developmental curvilinear lucency attributed to nonosseous otic capsule space adjacent to cochlea in children Imaging Bone CT (< mm thick images) Bilateral > unilateral C-shaped, thin, sharply defined lucency in otic capsule Adjacent to middle & apical > basal cochlear turns Adjacent lateral > medial aspect of cochlea May extend to apical turn on axial images Anterior to oval window Does not extend to oval window Parallel to cochlea on coronal images Lucency curved in shape of cochlear promontory Top Differential Diagnoses Fenestral otosclerosis Cochlear otosclerosis T-bone osteogenesis imperfecta Postirradiated T-bone Clinical Issues Incidental finding Becomes less conspicuous & disappears with age Medial lucency disappears 1st Age vs incidence of CC < years: Present in ˜ 60% 4-7 years: Present in ˜ 45% 7-10 years: Present in ˜ 25% 10-19 years: Present in ˜ 20% (Left) Normal temporal bone CT in an 8-week-old baby girl with sensorineural hearing loss demonstrates a benign developmental cochlear cleft There is bilateral, faint, but sharply defined curvilinear lucency within the otic capsule bone, parallel to the cochlear turns The lucency is more pronounced laterally than medially (Right) Right ear coronal CT in the same patient reveals the curvilinear lucency within the otic capsule bone just deep to the cochlear promontory 1430 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a 3-year-old boy with sensorineural hearing loss and a normal CT exam shows an evolving cochlear cleft At this stage, a linear lucency is seen medial & lateral to the middle and apical turns of the cochlea (Right) Coronal CT reconstruction in the same patient shows a faint cochlear cleft lucent line lateral to the cochlea deep to the cochlear promontory surface P.VI(4):5 TERMINOLOGY Abbreviations Cochlear cleft (CC) Synonyms Localized pericochlear hypoattenuating foci Cochlear capsule space Definitions Developmental curvilinear lucency attributed to nonosseous otic capsule space adjacent to cochlea in children IMAGING General Features Best diagnostic clue Sharply defined, thin, curvilinear lucency on bone CT Location Adjacent to cochlear middle & apical turns CT Findings Bone CT Bilateral > unilateral C-shaped, thin, sharply defined lucency in otic capsule Adjacent to middle & apical > basal cochlear turns Adjacent lateral > medial aspect of cochlea May extend to apical turn on axial images Anterior to oval window Does not extend to oval window Parallel to cochlea on coronal images Follows shape of cochlear promontory Imaging Recommendations Best imaging tool Bone CT Protocol advice < mm images DIFFERENTIAL DIAGNOSIS Fenestral Otosclerosis Rare in children Conductive hearing loss 1431 Diagnostic Imaging Head and Neck CT: Focal hypodensity begins at fissula ante fenestram May spread to involve round window margin, cochlear otic capsule Cochlear Otosclerosis Rare in children Mixed hearing loss CT: Linear hypodensity within otic capsule T-Bone Osteogenesis Imperfecta Generalized hypodensity, multiple skeletal fractures CT: Lucency of otic capsule bone Cannot be differentiated from cochlear otosclerosis Postirradiated T-Bone Radiation history; uncommon complication CT: Heterogeneous lucency otic capsule bone PATHOLOGY Staging, Grading, & Classification Cochlear cleft scoring 0: Cleft not present 1: No definite cleft 2: Small cleft 3: Moderate cleft 4: Large cleft Gross Pathologic & Surgical Features possible explanations Space in interface between inner endosteal & outer periosteal layers of otic capsule Middle layer of otic capsule bone (endochondral + intrachondral bone) partly cartilaginous near term Rapidly ossifies leaving small marrow spaces Related to fissula ante fenestram Fissula ante fenestram is fibrocartilaginous cleft anterior to oval window Histologically aberrant bulky cartilage can form in proximity CC occurs in of last areas of otic capsule to fully ossify Variation vs delay in capsule ossification CLINICAL ISSUES Presentation Most common signs/symptoms Incidental finding Demographics Age < years: Present in ˜ 60% 4-7 years: Present in ˜ 45% 7-10 years: Present in ˜ 25% 10-19 years: Present in ˜ 20% Natural History & Prognosis Becomes less conspicuous & usually disappears by 10 years of age Medial lucency disappears 1st Treatment None; developmental variant DIAGNOSTIC CHECKLIST Image Interpretation Pearls Sharply defined lucency around cochlea in infant/young child Often bilateral Reporting Tips Do not mistake for otosclerosis! SELECTED REFERENCES Chadwell JB et al: The cochlear cleft AJNR Am J Neuroradiol 25(1):21-4, 2004 Pekkola J et al: Localized pericochlear hypoattenuating foci at temporal-bone thin-section CT in pediatric patients: nonpathologic differential diagnostic entity? Radiology 230(1):88-92, 2004 1432 Diagnostic Imaging Head and Neck Congenital Lesions Labyrinthine Aplasia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Labyrinthine Aplasia Labyrinthine Aplasia Caroline D Robson, MBChB Key Facts Terminology Definition: Complete labyrinthine aplasia (CLA) Old synonym: Michel anomaly Imaging Bilateral or unilateral anomaly Temporal bone CT findings Otic capsule bone: Aplasia/hypoplasia Petrous apex: Hypoplasia Cochlear promontory: Absent/flattened Absent cochlea, vestibule, semicircular canals & vestibular aqueduct Internal auditory canal (IAC): Aplasia/hypoplasia Tegmen tympani: Normal, low, or defective Ossicles: Normal or malformed stapes Facial nerve canal: Aberrant course Carotid canal: Normal or absent MR: Absent vestibular & cochlear nerves Top Differential Diagnoses Cochlear aplasia Common cavity Labyrinthine ossification, obliterative type Pathology Genetic mutation, thalidomide exposure or unknown etiology Arrested otic placode development < 3rd week gestation Clinical Issues Congenital SNHL, extremely rare Diagnostic Checklist Often asymmetric: Contralateral common cavity, inner ear hypoplasia or cochlear IP-I anomaly (Left) Axial graphic depicts labyrinthine aplasia Note the complete absence of all inner ear structures with the exception of small IAC with only CN7 Lateral wall of inner ear (promontory) is flattened (Right) Axial bone CT in a 21-year-old woman with SNHL shows severe hypoplasia of otic capsule bone with air cells in expected location of the promontory Inner ear structures are absent CN7 canal is present with a broadened anterior genu The left petrous apex is hypoplastic 1433 Diagnostic Imaging Head and Neck (Left) Axial bone CT in the same patient at a more cephalad level shows hypoplastic otic capsule bone The anterior genu and proximal tympanic segment of the anomalous CN7 canal are visible (Right) Coronal bone CT in the same patient reveals complete absence of inner ear structures and severe hypoplasia of the otic capsule bone & petrous apex Notice that despite all the inner aplasia, the middle ear and ossicles appear normal P.VI(4):7 TERMINOLOGY Synonyms Complete labyrinthine aplasia (CLA) Old synonym: Michel anomaly Definitions Absent cochlea, vestibule & semicircular canals (SCC) IMAGING General Features Best diagnostic clue Complete absence of inner ear structures Absence/hypoplasia otic capsule bone Morphology Labyrinth fails to develop Aplasia/hypoplasia otic capsule bone CT Findings Bone CT Bilateral or unilateral anomaly Otic capsule bone: Aplasia/hypoplasia Petrous apex: Hypoplasia Cochlear promontory: Absent/flattened Absent cochlea, vestibule, SCC, vestibular aqueduct Internal auditory canal (IAC): Aplasia/hypoplasia Middle ear & mastoid: Normal or hypoplastic Tegmen tympani: Normal, low, or defective (suggesting encephalocele) Ossicles: Normal or malformed stapes Facial nerve canal: Aberrant course Jugular bulb/vein: Normal, dehiscent or stenotic + large emissary veins Carotid canal: Normal or absent Clivus: Normal or narrowed Cervical spine: Normal or + anomalies MR Findings T2WI Absent membranous labyrinth Absent vestibular & cochlear nerves 1434 Diagnostic Imaging Head and Neck Large cerebellopontine angle cistern/arachnoid cyst Pontine anomaly Imaging Recommendations Best imaging tool Bone CT MR brain & temporal bones DIFFERENTIAL DIAGNOSIS Cochlear Aplasia Late 3rd week arrest: Absent cochlea, dysmorphic vestibule & SCC Common Cavity 4th week arrest: Ovoid globular sac represents cochlea + vestibule Labyrinthine Ossificans Post-meningitic inner ear ossification, promontory well formed PATHOLOGY General Features Etiology Genetic mutation, thalidomide exposure or unknown etiology Genetics FGF3 mutations: LAMM (labyrinthine aplasia, microtia, microdontia) HOXA1 mutations: Bosley-Salih-Alorainy syndrome (BSAS) & Athabascan brainstem dysgenesis (ABDS) Associated abnormalities BSAS & ABDS: Congenital heart disease, horizontal gaze palsy, absent internal carotid arteries Embryology Arrest of otic placode development before 3rd gestational week Gross Pathologic & Surgical Features Failure of bony & membranous labyrinth formation Microscopic Features Inner ear structures not present CLINICAL ISSUES Presentation Most common signs/symptoms Congenital sensorineural hearing loss (SNHL) Demographics Epidemiology Extremely rare, < 1% inner ear malformations Treatment Unilateral CLA: Assess contralateral side for implantation if bilateral SNHL Bilateral CLA: Brainstem implantation DIAGNOSTIC CHECKLIST Consider CLA if otic capsule bone absent/hypoplastic & absent cochlea, vestibule & SCC Image Interpretation Pearls Often asymmetric: Contralateral common cavity, inner ear hypoplasia or cochlear IP-I anomaly Reporting Tips Variable “pathognomonic” flattening of cochlear promontory: Subtle to marked Evaluate tegmen tympani integrity on coronal reformats SELECTED REFERENCES Ozgen B et al: Complete labyrinthine aplasia: clinical and radiologic findings with review of the literature AJNR Am J Neuroradiol 30(4):774-80, 2009 Bosley TM et al: The clinical spectrum of homozygous HOXA1 mutations Am J Med Genet A 146A(10):1235-40, 2008 Tekin M et al: Homozygous mutations in fibroblast growth factor are associated with a new form of syndromic deafness characterized by inner ear agenesis, microtia, and microdontia Am J Hum Genet 80(2):338-44, 2007 Common Cavity Malformation > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Common Cavity Malformation Common Cavity Malformation Caroline D Robson, MBChB 1435 Diagnostic Imaging Head and Neck Key Facts Terminology Common cavity is cystic space representing undifferentiated cochlea & vestibule Imaging Cochlea, vestibule, & horizontal SCC: Common cavity, variable size Posterior & superior SCC: Absent, normal, or malformed IAC: Variable size, anomalous course, deficient fundus CN8: Small or absent components Facial nerve canal: Anomalous course Vestibular aqueduct: Not dilated, may be absent Ossicles: Normal or anomalous stapes & stenotic oval window Top Differential Diagnoses Cochlear aplasia Cystic cochleovestibular anomaly (CCVA) Pathology Unknown or genetic mutation HOXA1 mutations: Bosley-Salih-Alorainy syndrome (BSAS) Clinical Issues Congenital sensorineural hearing loss Rare: < 1% of all congenital inner ear malformations Bilateral profound SNHL: Successful cochlear implantation reported in common cavity anomaly Diagnostic Checklist Common cavity if cochlea, vestibule, & horizontal SCC form single cavity without differentiation (Left) Axial graphic shows features of common cavity malformation Note cochlea & vestibule are melded into one common cyst Semicircular canals are not distinct from cystic vestibular component (Right) Axial bone CT in a 6month-old boy with unilateral sensorineural hearing loss reveals a common cavity anomaly of the inner ear with a cystic structure representing the rudimentary cochlea bud, vestibule, and horizontal semicircular canal A dilated posterior semicircular canal is seen 1436 Diagnostic Imaging Head and Neck (Left) Axial 3D FIESTA image in an 18-month-old child with bilateral congenital sensorineural hearing loss demonstrates a common cavity anomaly with a cystic structure representing the vestibule, rudimentary cochlear bud, and horizontal semicircular canal There is a small posterior semicircular canal (Right) Oblique 2D FIESTA MR image in the same patient shows a small internal auditory meatus containing only a single posteriorly located vestibular nerve P.VI(4):9 TERMINOLOGY Definitions Common cavity is cystic space representing undifferentiated cochlea & vestibule IMAGING General Features Best diagnostic clue Featureless common cavity represents rudimentary cochlea, vestibule, & semicircular canals (SCC) Location Inner ear membranous labyrinth Size Common cavity: Small or large cystic structure Morphology Ovoid cyst CT Findings Bone CT Unilateral or bilateral & often asymmetric Cochlea, vestibule, & horizontal SCC: Common cavity, variable size Posterior and superior SCC: Absent, normal, or malformed IAC Variable size, often small Defective fundus Course may be anomalous Facial nerve canal: Anomalous labyrinthine segment & anterior genu Middle ear space & ossicles: Normal or anomalous stapes & stenotic oval window Vestibular aqueduct: Not dilated, may be absent MR Findings T2WI High signal intensity fluid within common cavity Posterior & superior SCC: Absent, normal, or malformed IAC: Small or absent CN8 components Imaging Recommendations Best imaging tool T-bone CT or MR 1437 Diagnostic Imaging Head and Neck Protocol advice T2 oblique sagittal MR through IAC used to assess presence of cochlear nerve DIFFERENTIAL DIAGNOSIS Cochlear Aplasia Imaging: Absent cochlea, normal or malformed vestibule Embryogenesis: Developmental arrest late 3rd gestational week Cystic Cochleovestibular Anomaly Imaging: Cochlea & vestibule are normal or enlarged & cystic without internal architecture Embryogenesis: 5th gestational week developmental arrest Labyrinthine Aplasia Variant sometimes has tiny otocyst PATHOLOGY General Features Etiology Unknown or genetic mutation Genetics HOXA1 mutations: Bosley-Salih-Alorainy syndrome (BSAS) Embryology Arrest of development at 4th gestational week, after differentiation of otic placode into otocyst Microscopic Features May be some differentiation of organ of Corti, but neural populations absent or low CLINICAL ISSUES Presentation Most common signs/symptoms Congenital sensorineural hearing loss Demographics Epidemiology Rare: < 1% of all congenital inner ear malformations Treatment Bilateral profound SNHL: Successful cochlear implantation reported in common cavity anomaly DIAGNOSTIC CHECKLIST Consider Common cavity if cochlea & vestibule form single cavity without differentiation Image Interpretation Pearls Oblique sagittal T2 MR images through IAC necessary to determine presence of cochlear nerve Reporting Tips Can be difficult to distinguish from cochlear aplasia + globular vestibule & horizontal SCC Consider cystic cochleovestibular anomaly if greater differentiation into separate but featureless cochlea & vestibule SELECTED REFERENCES Giesemann AM et al: From labyrinthine aplasia to otocyst deformity Neuroradiology 52(2):147-54, 2010 Bosley TM et al: The clinical spectrum of homozygous HOXA1 mutations Am J Med Genet A 146A(10):1235-40, 2008 Sennaroglu L et al: Surgical results of cochlear implantation in malformed cochlea Otol Neurotol 27(5):615-23, 2006 Sennaroglu L et al: A new classification for cochleovestibular malformations Laryngoscope 112(12):2230-41, 2002 Jackler RK et al: Congenital malformations of the inner ear: a classification based on embryogenesis Laryngoscope 97(3 Pt Suppl 40):2-14, 1987 Cystic Cochleovestibular Malformation (IP-I) > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Cystic Cochleovestibular Malformation (IP-I) Cystic Cochleovestibular Malformation (IP-I) Caroline D Robson, MBChB Key Facts Terminology Cochlear incomplete partition type I + dilated vestibule and horizontal semicircular canal (SCC) Imaging Cochlea: Absent internal septation & modiolus (IP-I) 1438 Diagnostic Imaging Head and Neck Vestibule & SCC: Dilated vestibule & horizontal SCC form single cavity, wide communication with cochlea CN7 canal: Normal or mildly obtuse anterior genu angle; normal or dehiscent tympanic segment Internal auditory canal (IAC): Small or dilated, defective fundus CN8: Nerves hypoplastic or absent Vestibular aqueduct: Usually normal Oval window: Normal or stenotic + stapedial anomaly Top Differential Diagnoses Cochlear aplasia: Absent cochlea; vestibule & SCC normal, dilated, or hypoplastic Common cavity: Cystic cochlea & vestibule form ovoid or rounded common cavity Clinical Issues Congenital SNHL Isolated symptom or + syndromic features (cardiac, spine anomalies, etc.) CCVM accounts for < 2% of all congenital labyrinthine lesions Diagnostic Checklist CCVM: “Figure 8” cochlea & vestibule lacking internal architecture IP-I spectrum: CCVM = least differentiated manifestation; IP-I + normal vestibule = mildest manifestation (Left) Axial graphic depicts “figure 8” morphology of featureless cochlea & vestibule Cochlear interscalar septum and modiolus are absent CN8 components are hypoplastic IAC is narrow & shortened CN7 labyrinthine segment has lost its anteriorly curving shape and appears straightened as it ends at the geniculate ganglion (Right) Axial bone CT in a 6-month-old girl with unilateral SNHL and multiple congenital anomalies shows the typical “figure 8” morphology of CCVM (Left) CT in an 18-month-old boy with congenital SNHL and CCVM shows a cochlea that lacks internal architecture also termed IP-I malformation The vestibule and horizontal semicircular canal (SCC) form a single globular cavity 1439 , Diagnostic Imaging Head and Neck The middle ear space and mastoid air cells are opacified This patient had a contralateral common cavity anomaly (Right) Coronal bone CT in the same patient demonstrates the globular vestibule and horizontal SCC P.VI(4):11 TERMINOLOGY Synonyms Cystic cochleovestibular anomaly (CCVM) Cochlear incomplete partition type I (IP-I) Definitions Arrest of inner ear development: Cochlea lacks interscalar septum & modiolus (IP-I) + dilated vestibule & horizontal semicircular canal (SCC) IMAGING General Features Best diagnostic clue Cystic, featureless cochlea + dilated vestibule & horizontal SCC Location Membranous labyrinth Size Usually enlarged cochlea, vestibule & horizontal SCC Morphology Cochlea & vestibule: “Figure 8” contour, no internal features CT Findings Bone CT Unilateral or bilateral, often asymmetric Cochlea: Absent internal septation, absent modiolus (IP-I), variable size Vestibule: Dilated, enlarged communication with cochlea SCC: Dilated horizontal SCC forms common cavity with vestibule, anterior limb superior SCC ± dilated Internal auditory canal (IAC): Small or dilated, defective fundus CN7 canal: Normal or mildly obtuse anterior genu angle; normal or dehiscent tympanic segment Vestibular aqueduct: Usually normal Oval window: Normal or stenotic + stapedial anomaly MR Findings T2WI Cochlea + vestibule: “Figure 8” contour Cochlea: Lacks internal septation & modiolus Vestibule & horizontal SCC: Dilated CN8: Nerves hypoplastic or absent Imaging Recommendations Best imaging tool MR to identify CN8 components Protocol advice 3D T2 (FIESTA, SPACE): Axial & oblique sagittal DIFFERENTIAL DIAGNOSIS Cochlear Aplasia Absent cochlea; vestibule & SCC normal, dilated, or hypoplastic Common Cavity Cystic cochlea & vestibule form undifferentiated or minimally differentiated common cavity PATHOLOGY General Features Etiology Currently unknown Embryology Arrest of otic placode development ˜ 5th gestational week Gross Pathologic & Surgical Features Cochlea & vestibule lack internal architecture Microscopic Features Cochleovestibular nerves deficient Cochlea lacks interscalar septum & modiolus 1440 Diagnostic Imaging Head and Neck CLINICAL ISSUES Presentation Most common signs/symptoms Congenital SNHL Isolated or + syndromic features (cardiac, spine anomalies, etc.) Demographics Epidemiology Rare inner ear anomaly CCVM accounts for < 2% of all congenital labyrinthine anomalies Treatment If contralateral ear is normal, no treatment indicated Cochlear implantation Some success reported if cochlear nerve present Risks in CCVM: CSF leak (deficient IAC fundus), CN7 damage (dehiscent) DIAGNOSTIC CHECKLIST Consider CCVM for “Figure 8” cochlea & vestibule lacking internal architecture Image Interpretation Pearls MR to detect hypoplasia/aplasia CN8 components Reporting Tips IP-I spectrum: CCVM = least differentiated manifestation; IP-I + normal vestibule = mildest manifestation SELECTED REFERENCES Sennaroglu L et al: Surgical results of cochlear implantation in malformed cochlea Otol Neurotol 27(5):615-23, 2006 Sennaroglu L et al: Unpartitioned versus incompletely partitioned cochleae: radiologic differentiation Otol Neurotol 25(4):520-9; discussion 529, 2004 Sennaroglu L et al: A new classification for cochleovestibular malformations Laryngoscope 112(12):2230-41, 2002 Cochlear Incomplete Partition Type I (IP-I) > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Cochlear Incomplete Partition Type I (IP-I) Cochlear Incomplete Partition Type I (IP-I) Caroline D Robson, MBChB Key Facts Terminology Spectrum of anomalies from mild (cochlea lacks internal structure) to severe (cystic cochleovestibular malformation = CCVM) Cochlear incomplete partition type I (IP-I): Milder form of IP-I confined to cochlea CCVM: Least differentiated manifestation of IP-I involving cochlea, vestibule, & SCC Imaging IP-I has absent interscalar septum & modiolus Spectrum of IP-I severity Amorphous sac, wide communication between cochlea & vestibule; figure morphology (CCVM) Some external structure, dilated vestibule, & horizontal SCC (most common) External indentations suggesting cochlear turns, ± normal vestibule (rare) Cochlear nerve canal (CNC) & IAC: Normal, wide (most common) or narrow, absent macula cribrosa Cochlear nerve: Usually hypoplastic or absent Vestibule & horizontal SCC: Usually dilated Vestibular aqueduct: Normal Top Differential Diagnoses Cochlear hypoplasia: Small cochlea, < turns Large vestibular aqueduct (IP-II) Defective septation between middle & apical cochlear turns, normal basal turn Large vestibular aqueduct/endolymphatic sac Common cavity malformation Single cystic structure = cochlea + vestibule Clinical Issues When profound bilateral SNHL: Cochlear implantation variably successful Risk of CSF gusher 1441 Diagnostic Imaging Head and Neck (Left) 9-month-old girl with right SNHL shows complete absence of the cochlear modiolus and interscalar septum The anomaly affects the entire cochlea In this relatively mild and uncommon manifestation of IP-I, there is some external “shape” to the cochlea (Right) Axial T2WI MR shows same patient at 19 months of age Cochlear modiolus and interscalar septum are absent The vestibule and semicircular canals are partially seen and are normal The endolymphatic sac is not enlarged (Left) Axial bone CT in a 4-year-old boy with right SNHL shows dilatation of the vestibule and horizontal semicircular canal The vestibular aqueduct is not enlarged The internal auditory meatus is widened (Right) Axial bone CT in same patient shows cochlea appears cystic and lacks internal structure Note wide communication between the cochlea and vestibule This is the more common form of IP-I, with a cystic cochlea and dilatation of the vestibule and horizontal SCC, also referred to as CCVA P.VI(4):13 TERMINOLOGY Abbreviations Cochlear incomplete partition type I (IP-I) Synonyms Cystic cochleovestibular malformation (CCVM) Definitions Incomplete cochlear partition type I: Absent internal structure of entire cochlea Cochlear IP-I: Milder form of IP-I confined to cochlea CCVM: Least differentiated manifestation of IP-I involving cochlea, vestibule, & semicircular canals IMAGING 1442 Diagnostic Imaging Head and Neck General Features Best diagnostic clue Cochlea lacks interscalar septum between basal, middle, & apical turns Absent modiolus Size Normal-sized or large cochlea Morphology Variable morphology, unilateral or bilateral Most differentiated IP-I Visible external cochlear turns lacking internal interscalar septum & modiolus Normal vestibule & semicircular canals Least differentiated IP-I Cystic featureless cochlea with cystic vestibular malformation “Figure 8” morphology CT Findings Bone CT Cochlea appearance Malformation affects entire cochlea Absent interscalar septum Absent modiolus Variable external contour Amorphous sac or external indentations suggesting cochlear turns Cochlear nerve canal & IAC Normal, wide or narrow, absent macula cribrosa Vestibule & horizontal Semicircular canal Grossly dilated or normal Vestibular aqueduct: Rarely enlarged Middle ear & ossicles Normal or oval window stenosis/atresia + abnormal stapes MR Findings 3D CISS, FIESTA, or equivalent Cochlea: Lacks internal structure Vestibule & horizontal semicircular canal: Usually dilated Cochlear nerve: Usually hypoplastic or aplastic Imaging Recommendations Best imaging tool MR: To evaluate presence & size of cochlear nerve DIFFERENTIAL DIAGNOSIS Large Vestibular Aqueduct (IP-II) Normal basal turn, defective septation affects cochlear middle & apical turns Modiolar deficiency often associated Large bony vestibular aqueduct Cochlear Hypoplasia Small cochlea with < turns CHARGE Syndrome Stenotic/atretic cochlear nerve canal Variable cochlear anomaly Small vestibule & small/absent semicircular canals Common Cavity Malformation Single cystic structure represents undifferentiated cochlea + vestibule CLINICAL ISSUES Presentation Most common signs/symptoms Sensorineural hearing loss Natural History & Prognosis Congenital sensorineural hearing loss Absent macula cribrosa & modiolus Risk of meningitis & post meningitic labyrinthitis ossificans Treatment 1443 Diagnostic Imaging Head and Neck Profound bilateral sensorineural hearing loss: Cochlear implantation with variable success Risk of CSF gusher SELECTED REFERENCES Chadha NK et al: Bilateral cochlear implantation in children with anomalous cochleovestibular anatomy Arch Otolaryngol Head Neck Surg 135(9):903-9, 2009 Sennaroglu L et al: Surgical results of cochlear implantation in malformed cochlea Otol Neurotol 27(5):615-23, 2006 Sennaroglu L et al: Unpartitioned versus incompletely partitioned cochleae: radiologic differentiation Otol Neurotol 25(4):520-9; discussion 529, 2004 Sennaroglu L et al: A new classification for cochleovestibular malformations Laryngoscope 112(12):2230-41, 2002 Large Vestibular Aqueduct (IP-II) > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Large Vestibular Aqueduct (IP-II) Large Vestibular Aqueduct (IP-II) Caroline D Robson, MBChB Key Facts Terminology Large vestibular aqueduct (LVA) houses enlarged endolymphatic sac & duct IP-II: Incomplete partition between middle & apical cochlear turns typically seen with LVA IP-II + LVA: Mondini anomaly (historic terminology) Imaging CT: LVA: ≥ mm at midpoint &/or ≥ mm at operculum perpendicular to VA long axis MR: Enlarged endolymphatic sac & duct Cochlea: Abnormal in ˜ 75% LVA cases Absent septation between middle & apical turns Deficient modiolus, asymmetric scalar chambers Vestibule: Normal or mildly dilated Top Differential Diagnoses Cystic cochleovestibular malformation (IP-I) Cochlear hypoplasia CHARGE syndrome Branchiootorenal syndrome Pathology SLC26A4 mutations Autosomal recessive, ˜ 5-10% cases prelingual HL Syndromic deafness: Pendred syndrome Nonsyndromic deafness: DFNB4 ˜ 2/3 LVA patients have SLC26A4 mutations Clinical Issues Most common abnormality in pediatric SNHL Bilateral anomaly (90%) Congenital cause of acquired SNHL or MHL Progressive/fluctuating SNHL Avoid contact sports & head trauma Cochlear implantation for profound bilateral SNHL 1444 Diagnostic Imaging Head and Neck (Left) Axial graphic of left inner ear shows the large endolymphatic sac epidural & intraosseous components The cochlea is malformed, with absent septation between the middle and apical turns, which appear bulbous (Right) Axial T-bone CT in a 15-year-old boy with SNHL reveals a large vestibular aqueduct The interscalar septum is present between the apical and middle cochlear turns, but the modiolus is narrow and the scalar chambers are asymmetric (posterior > anterior) (Left) Axial T-bone CT in a 17-year-old girl with Pendred syndrome demonstrates a large vestibular aqueduct and absent septation between the middle and apical cochlear turns with absence of the modiolus This is typical of incomplete partition type II which result in a “baseball cap” appearance of the cochlea (Right) Axial bone CT in a 3year-old girl with SNHL and LVA shows a typical IP-II cochlear anomaly with a plump cochlear middle turn, absent modiolus, and no apical septation P.VI(4):15 TERMINOLOGY Abbreviations Large vestibular aqueduct (LVA) Synonyms Large endolymphatic sac anomaly (LESA): T2 MR term Enlarged vestibular aqueduct (EVA): T-bone CT term IP-II + LVA (current terminology): Incomplete cochlear partition type II + large vestibular aqueduct Mondini anomaly (historic terminology): IP-II + LVA Definitions 1445 Diagnostic Imaging Head and Neck LVA: Enlarged bony vestibular aqueduct houses large endolymphatic sac & duct associated with variable cochlear malformation IP-II: Incomplete partition (deficient interscalar septum) between middle & apical cochlear turns, usually seen with LVA IMAGING General Features Best diagnostic clue T-bone CT: Large vestibular aqueduct (VA) + IP-II T2 MR: Large endolymphatic sac + IP-II Location Petrous bone; bilateral Size Axial T-bone CT: VA ≥ mm at midpoint ± ≥ mm at operculum perpendicular to long axis of VA Axial T2 MR: Visible endolymphatic sac in fovea is abnormal Morphology Axial bone CT: V-shaped, enlarged bony VA Axial T2 MR: Large endolymphatic sac along posterior wall of petrous bone CT Findings Bone CT LVA: May scallop posterior margin of petrous bone Cochlea Abnormal on CT in ˜ 75% of LVA cases Basal turn: Normal Cochlear middle & apical turns Interscalar septum between middle & apical turns: Normal or deficient (IP-II) Plump/bulbous middle & apical turns if deficient septation Asymmetric scalar chambers (anterior < posterior) Modiolus: Deficient, absent, or normal Vestibule: Normal or mildly dilated Middle ear space & ossicles: Normal MR Findings T1WI Low to intermediate signal endolymphatic sac visible along posterior wall of petrous bone 3D FIESTA or CISS (or equivalent) Endolymphatic sac & duct: Enlarged, variable signal; hypointensity attributed to hyperviscous protein Cochlea MR findings Middle & apical turns: Normal or deficient septation with plump apical & middle turns (IP-II) Asymmetric scalar chambers: Anterior < posterior Anterior chamber = scala vestibuli Posterior chamber = scala tympani Modiolus: Deficient (typical), absent, or normal Imaging Recommendations Best imaging tool High-resolution thin section MR or T-bone CT Protocol advice CT: Thin section axial T-bone (< mm), reformatted coronals, reformatted 45% oblique (Pöschl view) MR: 3D FIESTA or CISS or equivalent (0.8-1 mm slice thickness) DIFFERENTIAL DIAGNOSIS Cystic Cochleovestibular Malformation (IP-I) Cystic cochlea without internal structure & cystic vestibule Cochlear Hypoplasia Small cochlea, < turns CHARGE Syndrome Funnel-shaped VA, small vestibule, & small/absent semicircular canals Cochlear nerve canal stenosis/atresia & thickened modiolus; occasional cochlear hypoplasia Branchiootorenal Syndrome Funnel-shaped VA, cochlear hypoplasia variant with small offset middle & apical turns High Jugular Bulb Communicates with jugular foramen not vestibule 1446 Diagnostic Imaging Head and Neck Normal variation of jugular foramen anatomy PATHOLOGY General Features Etiology Genetic ± environmental factors produce hearing loss LVA + large endolymphatic sac occur during embryogenesis ± hydrops membranous labyrinth Proposed mechanisms for sensorineural hearing loss (SNHL) or mixed hearing loss (MHL) Cochlea is “fragile” & susceptible to injury from mild trauma as result of microscopic infrastructural deficiencies Protein-rich, hyperosmolar endolymph refluxes into cochlea causing hair cell damage Increased CNS pressure damages cochlear hair cells Cochlear malformation per se may contribute to SNHL in some cases Conductive component of MHL due to inner ear mechanisms Genetics SLC26A4 mutations (PDS gene, chromosome 7) ˜ 2/3 LVA patients have SLC26A4 mutations P.VI(4):16 Encodes Pendrin protein Anion transporter (chloride & iodide) Expressed in thyroid, kidney, inner ear Role in endolymph homeostasis & resorption Defects cause neuroepithelial damage & inner ear malformation Autosomal recessive inheritance SLC26A4 mutations account for ˜ 5-10% cases prelingual hearing loss Syndromic deafness: Pendred syndrome (SNHL + thyroid organification defect ± goiter) ˜ 10% hereditary deafness Nonsyndromic deafness: DFNB4 (isolated familial SNHL) ˜ 4% nonsyndromic deafness 2nd most common cause nonsyndromic deafness after GJB2 mutation FOXI1 mutations (less common): SLC26A4 transcriptional activator gene Associated abnormalities Pendred syndrome: Goiter (2nd decade) Distal renal tubular acidosis (rare) Defect in urinary acidification + various degrees of metabolic acidosis Anatomic comments Endolymphatic sac has epidural portion (larger part) & intraosseous portion Endolymphatic duct is short connection between crus communis & intraosseous sac Normal endolymphatic sac & duct barely visible on 3D FIESTA/CISS MR Gross Pathologic & Surgical Features Enlarged VA houses large ELS found in dural sleeve in fovea in posterior wall of T-bone CLINICAL ISSUES Presentation Most common signs/symptoms SNHL (or MHL) Bilateral severe or profound Fluctuating or progressive course SNHL precipitated by minor head trauma Other signs/symptoms Tinnitus, vertigo, dizziness Pendred syndrome: Hypothyroidism ˜ 50%, ± goiter in adolescence Demographics Age Prelingual or early postlingual SNHL (or MHL) Congenital cause of acquired SNHL Epidemiology LVA: Most common CT/MR abnormality in pediatric SNHL Bilateral anomaly (90%) 1447 Diagnostic Imaging Head and Neck Natural History & Prognosis If bilateral, inevitably leads to profound SNHL SNHL (or mixed HL) Hearing loss may not be present until early adult life Fluctuating or progressive course ± linear relationship observed between VA width and progressive SNHL Prognosis best for unilateral HL or late onset HL Treatment Avoid contact sports & head trauma Profound bilateral SNHL: Cochlear implantation No increase in cochlear implant complications DIAGNOSTIC CHECKLIST Consider Known SLC26A4 mutation/Pendred syndrome: Look for EVA/LESA EVA/LESA: Recommend SLC26A4 testing, US thyroid, thyroid function tests, ± perchlorate discharge test Obtain MR if borderline VA measurements on CT: Visible endolymphatic sac = enlarged Image Interpretation Pearls LVA diagnosis: Look for associated cochlear anomaly Reporting Tips Reformatted coronal CT or short axis oblique (Pöschl) view differentiates LVA from high-riding jugular bulb SELECTED REFERENCES Boston M et al: The large vestibular aqueduct: a new definition based on audiologic and computed tomography correlation Otolaryngol Head Neck Surg 136(6):972-7, 2007 Fitoz S et al: SLC26A4 mutations are associated with a specific inner ear malformation Int J Pediatr Otorhinolaryngol 71(3):479-86, 2007 Vijayasekaran S et al: When is the vestibular aqueduct enlarged? A statistical analysis of the normative distribution of vestibular aqueduct size AJNR Am J Neuroradiol 28(6):1133-8, 2007 Albert S et al: SLC26A4 gene is frequently involved in nonsyndromic hearing impairment with enlarged vestibular aqueduct in Caucasian populations Eur J Hum Genet 14(6):773-9, 2006 Berrettini S et al: Distal renal tubular acidosis associated with isolated large vestibular aqueduct and sensorineural hearing loss Ann Otol Rhinol Laryngol 111(5 Pt 1):385-91, 2002 Miyamoto RT et al: Cochlear implantation with large vestibular aqueduct syndrome Laryngoscope 112(7 Pt 1):1178-82, 2002 Sennaroglu L et al: A new classification for cochleovestibular malformations Laryngoscope 112(12):2230-41, 2002 Davidson HC et al: MR evaluation of vestibulocochlear anomalies associated with large endolymphatic duct and sac AJNR Am J Neuroradiol 20(8):1435-41, 1999 Naganawa S et al: MR imaging of the cochlear modiolus: area measurement in healthy subjects and in patients with a large endolymphatic duct and sac Radiology 213(3):819-23, 1999 10 Phelps PD et al: Radiological malformations of the ear in Pendred syndrome Clin Radiol 53(4):268-73, 1998 11 Tong KA et al: Large vestibular aqueduct syndrome: a genetic disease? AJR Am J Roentgenol 168(4):1097-101, 1997 12 Harnsberger HR et al: Advanced techniques in magnetic resonance imaging in the evaluation of the large endolymphatic duct and sac syndrome Laryngoscope 105(10):1037-42, 1995 P.VI(4):17 Image Gallery 1448 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a 4-year-old boy with SNHL shows a structure that could represent a large vestibular aqueduct or a high-riding jugular bulb More cephalad images (not shown) demonstrated connection to the vestibule (Right) Coronal CT reconstruction in the same patient demonstrates the LVA medial to the posterior seimicircular canal Note the superolateral location of the LVA with respect to the inferomedial jugular bulb (Left) Conventional axial T2WI MR (same patient) shows the hyperintense large endolymphatic sac that should not be confused with an arachnoid cyst, epidermoid, or venous structure The hypointense dura is located between the endolymphatic sac & the cerebellopontine angle cistern (Right) Axial T-bone CT in 17-year-old girl with Pendred syndrome reveals the entirety of the left LVA extending from the crus communis of the vestibule to the posterior aspect of the petrous bone 1449 Diagnostic Imaging Head and Neck (Left) Axial 3D FIESTA MR in a 6-year-old girl with progressive SNHL reveals a large endolymphatic sac (ES) containing variable signal intensity, adjacent to the sigmoid sinus (Right) Axial 3D FIESTA MR in a 2-year-old girl with SNHL shows a large ES lateral to the hypointense dura There is absent septation between the middle and apical cochlear turns and modiolar deficiency The hypointense line in the center of each cochlear turn is the normal osseous spiral lamina X-Linked Stapes Gusher (DFNX2) > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > X-Linked Stapes Gusher (DFNX2) X-Linked Stapes Gusher (DFNX2) Caroline D Robson, MBChB Key Facts Terminology X-linked mixed hearing loss Conductive hearing loss (CHL) with stapes fixation CHL with perilymphatic gusher Profound SNHL ± CHL + unique inner ear anomaly Imaging Cochlea: Absent interscalar septum & modiolus → “corkscrew” appearance IAC: Bulbous dilatation lateral aspect + deficient lamina cribrosa CN7 canal: Widened labyrinthine & proximal tympanic segments Top Differential Diagnoses Cochlear incomplete partition type I (IP-I) Large vestibular aqueduct + cochlear incomplete partition type II (IP-II) Pathology X-linked recessive: Males affected, female carriers Molecular cause: POU3F4 gene mutation Absent lamina cribrosa → communication between CSF in subarachnoid space & perilymph in cochlea → perilymphatic hydrops Clinical Issues Bilateral profound SNHL (may be progressive) ± CHL secondary to stapes fixation CHL may be masked by severe SNHL Surgical perilymphatic fistula + perilymph/CSF gusher (e.g., during stapedectomy or cochleostomy) Most common cause of X-linked hearing loss Diagnostic Checklist Essential imaging feature: Bulbous lateral end IAC + deficient lamina cribrosa + cochlear IP-III anomaly (“corkscrew” cochlea) 1450 Diagnostic Imaging Head and Neck (Left) Axial graphic of X-linked stapes gusher reveals the “corkscrew” cochlea with no modiolus The internal auditory canal (IAC) is foreshortened & widened The labyrinthine CN7 segment is enlarged (Right) Axial bone CT in boy with hearing loss shows the cochlea has no internal structure The lateral half of the IAC & cochlear nerve canal appear widened with absence of the modiolus There is post-meningitis ossification of the horizontal semicircular canal Proximal tympanic CN7 canal segment is widened (Left) Coronal bone CT in the same patient demonstrates the bulbous lateral aspect of the internal auditory canal The appearance of the cochlea and IAC is characteristic of DFNX2 (Right) Axial bone CT in the same patient demonstrates the same characteristic “corkscrew” cochlear appearance Post-meningitis ossification of the horizontal semicircular canal can again be seen The absent modiolus & lamina cribrosa permits communication between the subarachnoid & perilymphatic spaces P.VI(4):19 TERMINOLOGY Abbreviations Deafness X-linked type (DFNX2) X-linked mixed hearing loss (XLMHL) Synonyms Deafness type (DFN3) Conductive hearing loss (CHL) with stapes fixation CHL with perilymphatic gusher Nance deafness Cochlear incomplete partition type III (IP-III) 1451 Diagnostic Imaging Head and Neck Definitions Profound sensorineural hearing loss ± CHL + unique inner ear anomaly IMAGING General Features Best diagnostic clue Absent cochlear partition & modiolus → “corkscrew” appearance + bulbous lateral aspect IAC CT Findings Bone CT Cochlea: Absent interscalar septum & modiolus → “corkscrew” appearance Cochlear nerve canal: Widened IAC: Bulbous dilatation laterally, deficient lamina cribrosa Vestibule & semicircular canals: Normal or slightly dilated Facial nerve canal: Wide labyrinthine & proximal tympanic segments Oval window-stapes: Usually normal May be small with stapes footplate thickening Some pedigrees have normal imaging MR Findings T2WI Cochlea: Absent interscalar septum & modiolus IAC: Bulbous dilatation laterally CN8: Normal branches DIFFERENTIAL DIAGNOSIS Cochlear Incomplete Partition Type I (IP-I) Absent internal cochlear structure without corkscrew morphology Large Vestibular Aqueduct (IP-II) LVA ± absent apical septation & deficient modiolus PATHOLOGY General Features Genetics Inheritance: X-linked recessive Chromosomal locus: Xq21; POU3F4 gene mutation Mutation affects ability of POU3F4 protein to bind DNA, abolishes transcriptional activity Gross Pathologic & Surgical Features Absent lamina cribrosa → communication between subarachnoid space & cochlear perilymphatic space → perilymphatic hydrops Stapes fixation → perilymphatic/CSF gusher on attempted stapedectomy CLINICAL ISSUES Presentation Most common signs/symptoms Affected males Bilateral profound SNHL (may be progressive) ± CHL from stapes fixation CHL may be masked by severe SNHL Impaired vestibular function Surgical perilymphatic fistula + perilymph/CSF gusher at attempted stapedectomy/cochleostomy Female carriers Normal (most) or mild/delayed onset hearing loss Normal imaging ± bulbous IACs Other signs/symptoms Risk of meningitis & labyrinthitis ossificans Demographics Gender Female carriers, affected males Epidemiology Most common cause of X-linked hearing loss Treatment Profound SNHL: Cochlear implantation with risk of CSF gusher & meningitis DIAGNOSTIC CHECKLIST 1452 Diagnostic Imaging Head and Neck Image Interpretation Pearls Key features: Bulbous lateral end IAC + deficient lamina cribrosa + cochlear IP-III anomaly Risk of perilymphatic gusher at stapedectomy/cochleostomy SELECTED REFERENCES Lee HK et al: Clinical and molecular characterizations of novel POU3F4 mutations reveal that DFN3 is due to null function of POU3F4 protein Physiol Genomics 39(3):195-201, 2009 Sennaroglu L: Cochlear implantation in inner ear malformations - a review article Cochlear Implants Int Epub ahead of print, 2009 Incesulu A et al: Cochlear implantation in cases with incomplete partition type III (X-linked anomaly) Eur Arch Otorhinolaryngol 2008 Nov;265(11):1425-30 Epub 2008 Feb 28 Erratum in: Eur Arch Otorhinolaryngol 265(11):1439, 2008 de Kok YJ et al: Association between X-linked mixed deafness and mutations in the POU domain gene POU3F4 Science 267(5198):685-8, 1995 Phelps PD et al: X-linked deafness, stapes gushers and a distinctive defect of the inner ear Neuroradiology 33(4):326-30, 1991 Nance WE et al: X-linked mixed deafness with congenital fixation of the stapedial footplate and perilymphatic gusher Birth Defects Orig Artic Ser 07(4):64-9, 1971 Cochlear Aplasia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Cochlear Aplasia Cochlear Aplasia Caroline D Robson, MBChB Key Facts Terminology Definition: Cochlea absence + vestibule, semicircular canals, & IAC present in some form Imaging Cochlea: Absent bilaterally or unilaterally Cochlear nerve canal & cochlear nerve: Absent Cochlear promontory: Hypoplastic, flattened Vestibule & SCC: Often malformed, globular, & dilated or hypoplastic Vestibular aqueduct: Normal Facial nerve canal: Anomalous, obtuse angle anterior genu IAC: Hypoplastic Middle ear: Normal size Ossicles: Normal or malformed stapes Oval window: Normal or stenotic/atretic Top Differential Diagnoses Labyrinthine aplasia Common cavity deformity Cystic cochleovestibular anomaly Labyrinthine ossificans Pathology Absent cochlea, remainder of inner ear usually abnormal Clinical Issues Extremely rare, congenital SNHL, usually bilateral Diagnostic Checklist Cochlear aplasia if no cochlea is seen on CT or T2 MR, but rest of membranous labyrinth present Distinguish from obliterative cochlear ossification 1453 Diagnostic Imaging Head and Neck (Left) Axial graphic depicts findings of cochlear aplasia, including small IAC with absence of cochlear nerve, absent cochlea , vestibular and semicircular canal dysplasia, and flattening of CN7 labyrinthine segment (Right) Axial T2 SPACE image in 4-month-old girl with congenital SNHL reveals absence of cochlea There is globular vestibulehorizontal semicircular canal anomaly The short, narrow internal auditory meatus contains vestibular and facial nerves No cochlear nerve was seen (Left) Axial bone CT in the same patient demonstrates absence of the cochlea and mild flattening of the cochlear promontory (Right) Axial bone CT in the same patient shows a globular, malformed vestibule-horizontal semicircular canal A shortened, narrowed IAC is seen An obtuse anterior genu of the facial nerve canal is partially visualized with an anomalous course of the facial nerve canal P.VI(4):21 TERMINOLOGY Synonyms Absent cochlea Definitions Cochlear absence + vestibule, semicircular canals (SCC), & internal auditory canal (IAC) present in some form IMAGING General Features Best diagnostic clue Absent cochlea, usually dysmorphic vestibule & SCC Location Anterior membranous labyrinth 1454 Diagnostic Imaging Head and Neck CT Findings Bone CT Cochlea: Absent, bilaterally or unilaterally Cochlear nerve canal: Absent Cochlear promontory: Hypoplastic, flattened Vestibule & SCC: Often malformed, globular, & dilated or hypoplastic Vestibular aqueduct: Normal Facial nerve canal: Anomalous, obtuse angle anterior genu IAC: Hypoplastic Middle ear: Normal size Ossicles: Normal or malformed stapes Oval window: Normal or stenotic/atretic MR Findings T2WI Cochlea & cochlear nerve: Absent Vestibule & SCC: Variable abnormality Imaging Recommendations Best imaging tool Temporal bone CT or MR DIFFERENTIAL DIAGNOSIS Labyrinthine Aplasia Cochlea, vestibule, & semicircular canals absent Embryogenesis: Developmental arrest, 3rd gestational week Common Cavity Deformity Dilated cochlea & vestibule form common cavity Embryogenesis: Developmental arrest in 4th week Cystic Cochleovestibular Anomaly Cochlea & vestibule are cystic with no internal architecture Embryogenesis: Developmental arrest, 5th week Labyrinthine Ossificans Clinical presentation: Acquired SNHL, usually following meningitis Densely ossified membranous labyrinth, normal promontory PATHOLOGY General Features Etiology Unknown Associated abnormalities Vestibule & SSCs may be dilated Embryology Arrest of otic placode development at late 3rd gestational week Gross Pathologic & Surgical Features Absent cochlea, remainder of inner ear usually present but abnormal CLINICAL ISSUES Presentation Most common signs/symptoms Congenital SNHL, usually bilateral Demographics Age Congenital, present at birth Epidemiology Extremely rare inner ear anomaly < 1% of all inner ear congenital lesions Treatment Bilateral SNHL + bilateral cochlear aplasia: Brainstem implantation Cochlear implant contraindicated when cochlea absent Remember, there is no “central connection” = cochlear nerve in cochlear aplasia DIAGNOSTIC CHECKLIST Consider Cochlear aplasia diagnosed if no cochlea is seen on CT or T2 MR, but rest of membranous labyrinth present 1455 Diagnostic Imaging Head and Neck Important to distinguish cochlear aplasia from obliterative cochlear ossification SELECTED REFERENCES Sannaroglu L et al: Preliminary results of auditory brainstem implantation in prelingually deaf children with inner ear malformations including severe stenosis of the cochlear aperture and aplasia of the cochlear nerve Otol Neurotol 30(6):708-15, 2009 Sennaroglu L et al: A new classification for cochleovestibular malformations Laryngoscope 112(12):2230-41, 2002 Jackler RK et al: Congenital malformations of the inner ear: a classification based on embryogenesis Laryngoscope 97(3 Pt Suppl 40):2-14, 1987 Cochlear Hypoplasia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Cochlear Hypoplasia Cochlear Hypoplasia Caroline D Robson, MBChB Key Facts Terminology Small, underdeveloped cochlea, ≤ turns Imaging Cochlea (variable severity) Primitive single turn or bud-like Small, cystic, no modiolus or interscalar septa (ISS) Small, + internal architecture, short modiolus Cochlear nerve canal: Absent, narrow, normal, wide Cochlear nerve: Often absent or hypoplastic Facial nerve canal: Aberrant course ± dehiscence IAC: Normal or narrow/anomalous Vestibule: Normal, dilated, or hypoplastic SCCs: Normal, dilated, hypoplastic, or absent Vestibular aqueduct: Normal or large Top Differential Diagnoses Cochlear incomplete partition (IP-I) Cochlea normal-large size; absent interscalar septa & modiolus Large vestibular aqueduct (IP-II) LVA, deficient interscala septa between apical & middle turns Branchiootorenal syndrome (BOR) Hypoplastic offset middle & apical turns CHARGE syndrome Small/absent SCC Clinical Issues Congenital SNHL Diagnostic Checklist Consider CHARGE syndrome: Cochlear hypoplasia, cochlear nerve canal stenosis, small vestibule, & small/aplastic SCC Consider branchio-oto-renal syndrome: Tapered basal turn, hypoplastic, offset middle & apical turns 1456 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a 2.5-year-old boy with bilateral profound congenital SNHL shows a small bud-like structure, consistent with cochlear hypoplasia , that is isolated from the internal auditory meatus (IAC) The round window is absent (Right) Coronal CT reconstruction in the same patient shows the small bud-like hypoplastic cochlea with no internal architecture (Left) Axial bone CT in a 10-month-old girl with bilateral profound SNHL shows < 1.5 cochlear turns with a small half turn above the basal turn that lacks internal structure The internal auditory meatus is absent with only a small anomalous canal for CN7 (not shown) (Right) Axial bone CT in the same patient shows a relatively normal-appearing basal turn of the left cochlea P.VI(4):23 TERMINOLOGY Definitions Cochlear underdevelopment: Small cochlea with ≤ turns IMAGING General Features Best diagnostic clue Small cochlea, ≤ turns Cochlea often lacks internal septation Location Cochlea Size Small 1457 Diagnostic Imaging Head and Neck CT Findings Bone CT Cochlear appearance Spectrum of severity, sometimes asymmetric Small cochlea, < turns Internal cochlear structure present or absent Primitive single turn or bud-like Small, cystic, no modiolus or interscalar septa Small, internal architecture present, short modiolus Round window: Absent or present Cochlear nerve canal: Absent, narrow, or wide Internal auditory meatus: Normal or narrow/anomalous Vestibule: Normal, dilated, or hypoplastic Semicircular canals: Normal, dilated, hypoplastic, or absent Vestibular aqueduct: Normal or enlarged Facial nerve canal: Aberrant course ± dehiscence Middle ear space & contents: Usually normal MR Findings Cochlea: Small, < turns, internal structure present or absent Cochlear nerve: Often absent or hypoplastic Imaging Recommendations Best imaging tool This section (≤ mm) bone CT with multiplanar reformations High-resolution, thin section (≤ mm) MR Protocol advice MR 3D TRUEFISP or FIESTA for CN8 components DIFFERENTIAL DIAGNOSIS Cochlear Incomplete Partition (IP-I) Cochlea normal to large in size Interscalar septum absent Modiolus absent Large Vestibular Aqueduct (IP-II) Normal-sized cochlea Deficient septation between apical & middle turns Enlarged bony vestibular aqueduct (CT) Enlarged endolymphatic sac & duct (MR) Branchiootorenal Syndrome (BOR) Tapered cochlear basal turn Hypoplastic, offset of middle & apical cochlear turns CHARGE Syndrome Hypoplastic (e.g., single turn) or normal-sized cochlea Stenotic cochlear nerve canal Small vestibule Small or absent semicircular canals (SCC) PATHOLOGY General Features Etiology Unknown etiology & syndromic forms Gross Pathologic & Surgical Features Small cochlea Cochlea ranges from bud to < turns Cochlear interscalar septa absent or present CLINICAL ISSUES Presentation Most common signs/symptoms Congenital sensorineural hearing loss Other signs/symptoms Varies depending on underlying etiology Treatment 1458 Diagnostic Imaging Head and Neck Bilateral sensorineural hearing loss + mild cochlear hypoplasia: Cochlear implant if cochlear nerve present High-resolution MR used in oblique sagittal plane to evaluate internal auditory canal for presence of cochlear nerve DIAGNOSTIC CHECKLIST Consider Cochlear hypoplasia if small cochlea with < turns Image Interpretation Pearls Consider CHARGE: Cochlear nerve canal stenosis, small vestibule, & semicircular canal hypoplasia/aplasia Consider BOR: Tapered basal turn cochlea Hypoplastic, offset middle & apical turns SELECTED REFERENCES Teissier N et al: Computed Tomography measurements of the normal and the pathologic cochlea in children Pediatr Radiol 40(3):275-83, 2010 Sennaroglu L: Cochlear implantation in inner ear malformations - a review article Cochlear Implants Int Epub ahead of print, 2009 Cochlear Nerve & Cochlear Nerve Canal AplasiaHypoplasia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Caroline D Robson, MBChB Key Facts Terminology Stenosis or atresia of cochlear nerve canal (CNC) Cochlear nerve deficiency (CND): Cochlear nerve hypoplasia/aplasia Imaging CNC extends from fundus of IAC to modiolus Diameter measured at narrowest point CNC stenosis: < 1.7 mm Cochlea (spectrum of findings) Normal Normal modiolus + mildly stenotic CNC Thickened modiolus + stenotic/atretic CNC Cochlear anomaly (e.g., atresia, hypoplasia, etc.) + stenotic/atretic CNC Internal auditory canal: Normal, small, or absent CND: CN smaller than normal CN7 (hypoplasia) or absent (aplasia) Top Differential Diagnoses CHARGE syndrome Cochlear aplasia or hypoplasia Pathology Unclear whether CN fails to form or forms initially then degenerates Clinical Issues Presents with congenital SNHL 73% incidence CN aplasia in pediatric unilateral “neural” SNHL Diagnostic Checklist Most cases of CND have normal cochlea ± modiolar thickening ± CNC stenosis Assess cochlear nerves on axial & oblique sagittal 3D T2-weighted/CISS/FIESTA MR sequences 1459 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a 3-year-old boy with left SNHL shows stenosis of the left CNC , which has a width of approximately 1.3 mm The cochlea and IAC appear normal (Right) Axial bone CT shows a 3-month-old boy who failed the newborn hearing screen test Subsequent auditory brain stem response revealed profound right SNHL There is absence of the CNC and marked thickening of the modiolus The right IAC is only partially seen on this image and appeared mildly narrowed (Left) 3D CISS sequence in a 4-month-old boy with severe neural right SNHL shows a normal left cochlear nerve and normal inferior vestibular nerves The right cochlear nerve is not seen, and the right modiolus is mildly thickened There is stenosis of the right CNC with a width of 1.5 mm (Right) Sagittal oblique 3D CISS image in the same patient shows severe hypoplasia of the cochlear nerve , which is far smaller than the facial nerve The vestibular nerves appear normal P.VI(4):25 TERMINOLOGY Abbreviations Cochlear nerve canal (CNC) stenosis-atresia Cochlear nerve (CN) deficiency (CND) Synonyms Cochlear aperture stenosis-atresia Definitions CNC hypoplasia-aplasia: Narrowing or absence of cochlear nerve canal CND: Hypoplasia or absence (aplasia) of CN 1460 Diagnostic Imaging Head and Neck IMAGING General Features Best diagnostic clue CND: CN smaller than normal CN7 (hypoplasia) or absent (aplasia) on MR CNC width: Narrowest diameter between IAC fundus & modiolus on axial images CNC stenosis = CNC width < 1.5 mm; 1.6 mm ≈ borderline stenosis Thickened modiolus Location CNC extends from fundus of IAC to modiolus CN division of CN8 is anteroinferior in IAC Imaging Recommendations Best imaging tool 3D axial & sagittal oblique T2-weighted MR Protocol advice Axial & sagittal oblique 3D FIESTA/CISS or analogous sequence CT Findings Bone CT Cochlear nerve canal Normal: In some cases of CND on MR Stenosis: Severity varies Atresia: Complete absence of CNC Cochlea Normal turns & normal modiolus ≈ normal or mildly stenotic CNC Normal turns & thickened modiolus ≈ moderate to severe stenosis CNC Abnormal cochlea ≈ stenotic/atretic CNC (less common) (e.g., cochlear hypoplasia) Vestibule & SCC: Normal (most); rarely abnormal (e.g., syndromic etiology) Internal auditory canal (IAC): Normal or small CN7 canal: Normal (most) or anomalous (rare) MR Findings Cochlear nerve: Hypoplasia or aplasia CNC normal: Occasional CND CNC borderline stenotic: CN normal or CND CNC stenotic < 1.5 mm ± thickened modiolus: CND CNC stenosis + IAC narrowing: CND difficult to see on MR because of ↓ CSF around CN8 & Vestibular nerves (VN) Normal IAC: VN usually normal Narrow IAC: VN normal or deficient Cochlea, vestibule, & SCC malformation is uncommon DIFFERENTIAL DIAGNOSIS CHARGE Syndrome CNC stenosis/atresia, CN8 deficiency, hypoplastic vestibule, absent/hypoplastic SCC Cochlear Aplasia Cochlea absent Cochlear Hypoplasia Small cochlea, < turns CLINICAL ISSUES Presentation Most common signs/symptoms Congenital SNHL Bilateral or unilateral (most) SNHL usually static “Neural” type SNHL typical of isolated CND 73% incidence CN aplasia in pediatric unilateral neural SNHL Treatment Cochlear implantation contraindicated if CN absent Brainstem implantation may provide benefit DIAGNOSTIC CHECKLIST Consider CND: Commonest finding in pediatric “neural” SNHL For unilateral auditory neuropathy with normal CNs, evaluate for tumor or brainstem malformation or injury 1461 Diagnostic Imaging Head and Neck Image Interpretation Pearls Most cases of CN deficiency have normal cochlea & CNC stenosis ± modiolar thickening Reporting Tips Neural SNHL: Assess cochlear nerves on MR SELECTED REFERENCES Miyasaka M et al: CT and MR imaging for pediatric cochlear implantation: emphasis on the relationship between the cochlear nerve canal and the cochlear nerve Pediatr Radiol Epub ahead of print, 2010 Laury AM et al: Etiology of unilateral neural hearing loss in children Int J Pediatr Otorhinolaryngol 73(3):417-27, 2009 Sennaroglu L et al: Preliminary results of auditory brainstem implantation in prelingually deaf children with inner ear malformations including severe stenosis of the cochlear aperture and aplasia of the cochlear nerve Otol Neurotol 30(6):708-15, 2009 Adunka OF et al: Value of computed tomography in the evaluation of children with cochlear nerve deficiency Otol Neurotol 28(5):597-604, 2007 Ito K et al: Isolated cochlear nerve hypoplasia with various internal auditory meatus deformities in children Ann Otol Rhinol Laryngol 116(7):520-4, 2007 Glastonbury CM et al: Imaging findings of cochlear nerve deficiency AJNR Am J Neuroradiol 23(4):635-43, 2002 Globular Vestibule-Semicircular Canal > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Globular Vestibule-Semicircular Canal Globular Vestibule-Semicircular Canal Caroline D Robson, MBChB Key Facts Terminology Dilatation of semicircular canal (SCC) & globular, enlarged vestibule Small or absent bone island between vestibule & affected SCC Imaging Most frequently seen SCC & vestibular anomaly Usually affects lateral SCC (LSCC): Last to develop Isolated finding or + other ear anomalies SCC: Widened lumen of limb or entire SCC; small or absent bone island Vestibule: Normal or large Cochlea: Normal or malformed Top Differential Diagnoses Large vestibular aqueduct (IP-II) Mild cochlear dysplasia Cochlear incomplete partition type I (IP-I) Absent cochlear septation, ± dilated vestibule & LSCC Apert syndrome Syndromic craniosynostosis + widened sagittal suture, polysyndactyly, globular vestibule/LSCC Clinical Issues Mild form may be asymptomatic Vestibular symptoms: Normal or imbalance, vertigo Caloric testing: Absent or decreased caloric responses Hearing: Normal, sensorineural, or conductive hearing loss (ossicular or inner ear origin) Diagnostic Checklist LSCC + external & middle ear malformation Syndromic or chromosomal/genetic anomaly Craniofacial anomaly (most) Toxic exposure 1462 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a 9-month-old boy with oculoauriculovertebral spectrum shows the LSCC is dilated with a small bone island between the LSCC and the globular vestibule Note the malformed ossicles apposed to the lateral wall of the attic (Right) Axial bone CT in a child with severe sensorineural hearing loss reveals dilatation of the posterior SCC and vestibule The vestibular aqueduct is large The cochlear modiolus and apical septation are deficient (IP-II) (Left) Axial bone CT in a 10-month-old girl with profound sensorineural hearing loss demonstrates a large, globular LSCC that communicates with a dilated vestibule , forming a single cavity (Right) Coronal CT reconstruction in the same patient reveals the massively dilated lateral SCC Oval window atresia was also noted on a more anterior image (not shown) Semicircular Canal Hypoplasia-Aplasia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > Semicircular Canal Hypoplasia-Aplasia Semicircular Canal Hypoplasia-Aplasia Caroline D Robson, MBChB Key Facts Terminology Hypoplasia/aplasia of or multiple semicircular canals (SCC) ± hypoplastic vestibule Imaging Hypoplastic vestibule + hypoplasia/aplasia of all SCC in CHARGE syndrome Oval window stenosis/atresia, anomalous CN7 Cochlea: Thickened modiolus, stenosis/atresia CN7 canal, deficient cochlear septation (IP-I) 1463 Diagnostic Imaging Head and Neck Vestibular aqueduct: Dilated, funnel-shaped Hypoplasia single SCC + normal vestibule Posterior SCC (PSCC) + normal cochlea: Waardenburg (WS) & Alagille syndromes PSCC + abnormal cochlea: Branchiootorenal (BOR) syndrome: Hypoplastic middle & apical cochlear turns Horizontal SCC: Oval window stenosis/atresia & anomalous ± dehiscent tympanic segment CN7 Top Differential Diagnoses Down syndrome: Small HSCC bone island ± horizontal SCC fused with dysplastic vestibule ± cochlear nerve canal stenosis, IAC stenosis, LVA Labyrinthine ossificans: Prior meningitis or surgery Diagnostic Checklist CHARGE if hypoplasia vestibule + SCC Axial & coronal T-bone to assess oval window & CN7 tympanic segment Consider BOR for hypoplastic, offset middle & apical turns cochlea; look for PSCC anomaly Consider Waardenburg & Alagille syndromes for isolated PSCC anomaly (rare) (Left) Axial graphic depicts severe, syndromic type of semicircular canal anomaly with complete absence of all semicircular canals, cochlear malformation, and dysmorphic small vestibule (Right) Axial bone CT in a 12-monthold boy with profound sensorineural hearing loss shows complete absence of the horizontal SCC at the level of the vestibule A normal posterior SCC is seen The IAC is narrow (Left) Coronal bone CT in the same patient reveals the facial nerve canal , absence of the horizontal SCC, and a normal superior SCC There is mild stenosis of the oval window (Right) Axial T2WI MR in a 1-day-old baby girl with Waardenburg syndrome shows a rudimentary posterior SCC bud along the posterior aspect of the vestibule A normal horizontal SCC is seen 1464 Diagnostic Imaging Head and Neck CHARGE Syndrome > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Congenital Lesions > CHARGE Syndrome CHARGE Syndrome Caroline D Robson, MBChB Key Facts Terminology CHARGE Coloboma Heart anomaly Atresia choanae Retardation: Mental & somatic development Genital hypoplasia Ear abnormalities Major signs: Coloboma, choanal atresia, semicircular canal (SCC) hypoplasia/aplasia, cranial nerve (CN) involvement Minor signs: Hindbrain, external/middle ear, cardiac/esophageal malformations, hypothalamo-hypophyseal dysfunction, mental retardation Imaging Choanal atresia, coloboma (variable) Hypoplastic vestibule & hypoplastic/absent SCC Thickened modiolus, stenotic/absent cochlear nerve canal, absent cochlear septation (IP-1) Stenotic/atretic oval window & overlying anomalous tympanic segment of CN7 Large emissary veins, hypoplasia basiocciput, basilar invagination, & spinal anomalies Hypoplastic pons, cerebellar malformation CN hypoplasia/aplasia (mainly CN 1, 7, & 8) Top Differential Diagnoses Kallmann syndrome: Allelic, less severe VACTERL Branchiootorenal syndrome Pathology CHD7 mutation 60%; SEMA3E mutation Highly predictive of CHARGE: Anomalies pinna, agenesis/hypoplasia SCC, arhinencephaly (Left) Axial FSE T2-weighted fetal MR at 32 weeks gestation shows bilateral choanal atresia with linear hypointensity extending from the thickened vomer to the lateral nasal walls, outlined by amniotic fluid A single cochlear turn is seen bilaterally , and the cochleae appeared isolated from the IACs (Right) Axial bone CT in the same infant at days of age shows lateral nasal wall medial deviation and a thickened vomer , with bilateral bony and membranous choanal atresia 1465 Diagnostic Imaging Head and Neck (Left) Axial FSE T2-weighted MR in the same baby boy age days reveals right microphthalmia and bilateral colobomas A CHD7 mutation was found, confirming CHARGE syndrome (Right) Axial bone CT in the same child confirms incomplete cochlear partitioning (IP-I) , hypoplastic vestibules , and absent semicircular canals The ossicles are dysmorphic, and the left malleus is fused to the attic It is unusual to see the ocular, ear, & nasal findings of CHARGE all in the same patient P.VI(4):29 TERMINOLOGY Synonyms CHARGE association, Hall-Hittner syndrome Definitions CHARGE acronym Coloboma Heart anomaly Atresia choanae Retardation: Mental & somatic development Genital hypoplasia Ear abnormalities IMAGING General Features Best diagnostic clue Inner ear: Hypoplastic vestibule & hypoplastic/absent semicircular canals (SCC) CT Findings Bone CT Nose: Choanal atresia Eyes: Coloboma Face & oral cavity: Cleft lip/palate Temporal bones Hypoplastic vestibule Hypoplastic/absent SCC Thickened modiolus & stenotic/absent cochlear nerve canal (typical) Absent cochlear septation/single plump cochlear turn (incomplete partition type I variant) Bulbous vestibular aqueduct (variable) Stenotic/atretic oval window Anomalous, hypoplastic, dehiscent CN7 canal Dysmorphic, fused ossicles Skull base & spine Jugular foraminal stenosis & large emissary veins Hypoplasia basiocciput & spinal anomalies MR Findings 1466 Diagnostic Imaging Head and Neck Hypoplastic pons (common), cerebellar malformation Hypoplasia/aplasia cranial nerves: Primarily CN1, CN7, & CN8 Hypoplasia basiocciput, basilar invagination, & spinal anomalies Imaging Recommendations Best imaging tool CT: Temporal bones, face, nose, clivus, & spine MR: Brain, clivus, eyes, cranial nerves, & spine Protocol advice Axial bone CT & coronal reformats MR: Brain, spine, & CISS/FIESTA cranial nerves DIFFERENTIAL DIAGNOSIS Kallmann Syndrome Allelic, less severe VACTERL Vertebral/vascular, Anal/auricular, Cardiac, Tracheoesophageal fistula, Esophageal atresia, Renal/radial/rib, Limb anomalies Lacks ear anomalies PATHOLOGY General Features Genetics Gene map locus 8q12.1, 7q21.11 CHD7 mutation 60%; SEMA3E mutation Staging, Grading, & Classification Major signs: Coloboma, choanal atresia, SCC hypoplasia/aplasia, cranial nerve involvement Minor signs: Hindbrain, external/middle ear, cardiac & esophageal anomalies, hypothalamo-hypophyseal dysfunction, & mental retardation Gross Pathologic & Surgical Features Highly predictive of CHARGE External ear anomalies Agenesis/hypoplasia SCC Arhinencephaly CLINICAL ISSUES Presentation Most common signs/symptoms Airway obstruction, feeding difficulty, GE reflux Facial dysmorphism, cleft lip/palate Low set, cup-shaped ears, deafness Cardiac symptoms (e.g., tetralogy of Fallot) Growth retardation Genital hypoplasia (central hypogonadism) Coloboma, microphthalmia Anosmia Developmental delay/autism Demographics Epidemiology Birth incidence: in 12,000 Phenotypic variability DIAGNOSTIC CHECKLIST Consider Characteristic “CHARGE” inner ear anomaly Consider alternative diagnosis for bilateral choanal atresia & normal inner ears Image Interpretation Pearls MR for absent cranial nerves, abnormal pons & clivus Reporting Tips MR: Include cranial nerve assessment SELECTED REFERENCES Fujita K et al: Abnormal basiocciput development in CHARGE syndrome AJNR Am J Neuroradiol 30(3):629-34, 2009 Morimoto AK et al: Absent semicircular canals in CHARGE syndrome: radiologic spectrum of findings AJNR Am J Neuroradiol 27(8):1663-71, 2006 1467 Diagnostic Imaging Head and Neck Verloes A: Updated diagnostic criteria for CHARGE syndrome: a proposal Am J Med Genet A 133A(3):306-8, 2005 P.VI(4):30 Image Gallery (Left) Axial bone CT in a 1-year-old boy with CHARGE syndrome shows a prominent modiolus , cochlear nerve canal stenosis , small vestibule , absent SCCs, abnormal course of vestibular aqueduct , and opacified middle ear cavity and mastoid air cells (Right) Axial bone CT in a 13-month-old boy with a CHD7 mutation shows a thick modiolus , small vestibule , absent SCCs, narrow malleoincudal joint , middle ear and mastoid air cell opacification, and a large emissary vein (Left) Axial bone CT in a 16-month-old boy with CHARGE syndrome and a CHD7 mutation shows a single amorphous, unsegmented cochlear turn The incus and stapes form a single solid bar that is inferiorly angulated (Right) Axial bone CT in the same patient demonstrates the cephalad aspect of the cochlea , essentially isolated from the IAC The vestibule is hypoplastic , and the SCCs are absent The middle ear cavity and mastoid air cells are opacified 1468 Diagnostic Imaging Head and Neck (Left) Coronal bone CT in a 1.5-year-old boy with a CHD7 mutation shows the tympanic segment of CN7 overlying oval window atresia, hypoplastic vestibule , and absent SCCs (Right) Coronal bone CT in a 7-year-old girl with CHARGE shows cervical spine anomaly , petrous angulation, hypoplastic vestibule, and absent SCCs The facial nerve canal is dehiscent and overlies the atretic oval window The ossicles contact the facial nerve A large emissary vein indents the tegmen tympani P.VI(4):31 (Left) Reformatted sagittal CT in a 7-month-old boy with CHARGE shows deformity and sclerosis of the basiocciput (Right) Sagittal T2-weighted MR in a 4-day-old boy with a CHD7 mutation shows convexity of the planum sphenoidale , inferior placement of the sella , and a hypoplastic basiocciput There is mild inferior vermian hypoplasia with a prominent 4th ventricle, and the pons appears shortened 1469 Diagnostic Imaging Head and Neck (Left) Sagittal T1-weighted MR in a 16-month-old boy with a CHD7 mutation demonstrates a partially empty sella and the infundibulum is not seen Note the severe hypoplasia of the basiocciput and basilar invagination The pons is hypoplastic (Right) Coronal T2 STIR in the 4-day-old boy with a CHD7 mutation reveals absence of the right olfactory bulb Note the prominent left olfactory bulb (Left) Axial 3D FIESTA MR image in a 16-month-old patient with CHARGE syndrome shows the right CN7 and CN8 The left CN7 and CN8 are absent The pons is hypoplastic and rotated , and the 4th ventricle is asymmetric (Right) Axial 3D FIESTA MR more cephalad in the same patient shows the right CN6 The left CN6 is absent Infectious and Inflammatory Lesions Labyrinthitis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Infectious and Inflammatory Lesions > Labyrinthitis Labyrinthitis Troy Hutchins, MD Key Facts Terminology Subacute inflammatory or infectious disease of fluid-filled spaces of inner ear (IE) Imaging No imaging necessary if classic presentation (unilateral sudden onset SNHL) MR findings 1470 , Diagnostic Imaging Head and Neck T1 C+: Faint to moderate C+ within IE fluid T2: Normal high fluid signal preserved T1: Normal to mildly increased signal; if hemorrhage, ↑ IE signal T-bone CT findings Normal in acute/subacute labyrinthitis Labyrinthine ossificans possible if suppurative labyrinthitis Top Differential Diagnoses Labyrinthine ossificans Intralabyrinthine schwannoma Intralabyrinthine hemorrhage Pathology Labyrinthitis classification Viral labyrinthitis: Unilateral Bacterial labyrinthitis: Meningogenic (bilateral) > > tympanogenic (unilateral) Post-traumatic/postsurgical: Unilateral Autoimmune: Related to systemic disease (bilateral) Clinical Issues Viral: Sudden onset unilateral sensorineural hearing loss (SNHL) ± vertigo & tinnitus Bacterial: Child with bacterial meningitis → bilateral, progressive SNHL Labyrinthitis ossificans possible (Left) Axial T-bone T1WI C+ MR demonstrates pathologic enhancement of the cochlea and vestibule , compatible with labyrinthitis Linear enhancement within the internal auditory canal represents an associated facial neuritis (Right) Axial T-bone T2WI MR in the same patient reveals normal fluid signal within the cochlea and vestibule , typical of subacute labyrinthitis Intralabyrinthine schwannomas also enhance but show loss of normal inner ear T2 fluid signal 1471 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ MR of left T-bone shows labyrinthitis with enhancement confined to the cochlea Labyrinthitis can be focal, as in this case, or diffuse (Right) Axial T1WI C+ MR of left T-bone reveals enhancement of the cochlea & internal auditory canal in a patient with bacterial otomastoiditis presenting with otalgia, CN7 palsy, and hearing loss Tympanic CN7 is also thickened & enhancing in this example of meningogenic labyrinthitis (Courtesy C Schatz, MD.) P.VI(4):33 TERMINOLOGY Synonyms Subacute labyrinthitis Definitions Subacute inflammatory or infectious disease of fluid-filled spaces of inner ear (IE) IMAGING General Features Best diagnostic clue T1 C+ MR shows faint to moderate enhancement within normally fluid-filled spaces of IE CT Findings Bone CT None in acute & subacute phase of labyrinthitis If suppurative labyrinthitis → labyrinthine ossificans (LO) MR Findings T1WI Signal often normal In severe, diffuse membranous labyrinthitis, may show subtle ↑ in signal If intralabyrinthine hemorrhage present, ↑ IE signal T2WI High signal IE fluid (appears normal) T1WI C+ Focal or diffuse faint to moderate enhancement within normally fluid-filled spaces of cochlea, vestibule, & semicircular canals Imaging Recommendations Best imaging tool If classic clinical presentation, no imaging necessary Atypical presentation: Thin section T1 C-, T1 C+, & T2 MR are key sequences DIFFERENTIAL DIAGNOSIS Labyrinthine Ossificans Bone CT: Ossification of membranous labyrinth T1 C+ MR: Early phase, IE enhancement Intralabyrinthine Schwannoma T1 C+ MR: Enhancement more intense and localized than labyrinthitis 1472 Diagnostic Imaging Head and Neck T2 MR: Focal decreased signal in region of enhancement Intralabyrinthine Hemorrhage Underlying coagulopathy or trauma history T1 MR: Hyperintense pre-contrast T1 signal PATHOLOGY General Features Etiology Serous or suppurative labyrinthitis possible Etiology of inner ear enhancement on MR Labyrinthine vasculature breakdown with subsequent neovascularization of intralabyrinthine membranes Begins in subacute phase, persists for months Microscopic Features Suppurative labyrinthitis → labyrinthine ossificans Early chronic findings: Fibrous stage shows fibroblast proliferation Late chronic findings: Ossific stage shows LO CLINICAL ISSUES Presentation Most common signs/symptoms Sudden onset sensorineural hearing loss (SNHL) Vertigo & tinnitus Labyrinthitis classification Viral labyrinthitis Sudden unilateral SNHL Often after upper respiratory illness Not imaged if classic presentation May be 2° to mumps/measles (“hematogenic”) Bacterial labyrinthitis Often progresses to permanent SNHL Meningogenic: Bilateral; secondary to meningitis Primary cause of acquired childhood deafness Spreads through IAC or cochlear aqueduct Tympanogenic: Unilateral, from acute bacterial otomastoiditis Direct spread through round or oval window Post-traumatic/postsurgical: Unilateral Hemorrhage likely incites enhancement Healing → granulation tissue ± LO Autoimmune: Very rare, related to systemic disease (e.g., Wegener, Cogan) Demographics Age Any age may be affected Epidemiology Viral > > bacterial labyrinthitis Natural History & Prognosis Hearing loss recovery common in viral labyrinthitis Persistent SNHL common in bacterial labyrinthitis Treatment Viral etiology: Steroids, vestibular suppressants, & vestibular exercises Bacterial: Topical & IV antibiotics Surgical intervention when severe SELECTED REFERENCES Wippold FJ 2nd et al: Vertigo and hearing loss AJNR Am J Neuroradiol 30(8):1623-5, 2009 Hegarty JL et al: The value of enhanced magnetic resonance imaging in the evaluation of endocochlear disease Laryngoscope 112(1):8-17, 2002 Palacios E et al: Hemorrhagic labyrinthitis Ear Nose Throat J 79(2):80, 2000 Seltzer S et al: Contrast enhancement of the labyrinth on MR scans in patients with sudden hearing loss and vertigo: evidence of labyrinthine disease AJNR Am J Neuroradiol 12(1):13-6, 1991 1473 Diagnostic Imaging Head and Neck Otosyphilis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Infectious and Inflammatory Lesions > Otosyphilis Otosyphilis Troy Hutchins, MD Key Facts Terminology Sexually transmitted inner ear disease caused by bacterium spirochete Treponema pallidum Imaging Bone CT: “Moth-eaten” permeative demineralization of T-bone (syphilitic osteitis) Inner ear, middle ear-mastoid, ossicles T1 C+ MR: Enhancement of CN7 & CN8 in internal auditory canal ± membranous labyrinth (syphilitic labyrinthitismeningitis) Top Differential Diagnoses Cochlear otosclerosis T-bone osteogenesis imperfecta T-bone Paget disease T-bone fibrous dysplasia Postirradiated T-bone Pathology Sexually transmitted spirochete Treponema pallidum Osteitis: Inflammatory resorptive osteitis Labyrinthitis: Obliterative endarteritis Clinical Issues Diagnosis made when otologic symptoms are present with positive serology Hearing loss (80%) & vertigo: Often acute & fluctuating Simulates Ménière disease Diagnostic Checklist Consider: If HIV patient with hearing loss and permeative inner demineralization, testing for positive syphilis serology completed before diagnosing otosyphilis (Left) Axial T-bone CT shows typical findings of advanced middle and inner otosyphilis There are extensive “motheaten” permeative bony changes of the inner ear , middle ear-mastoid , and ossicles (Courtesy M Sandlin, MD.) (Right) Coronal T-bone CT in the same patient demonstrates permeative demineralization of the otic capsule with otosclerosis-like plaque on cochlear promontory These findings are secondary to inflammatory resorptive osteitis 1474 Diagnostic Imaging Head and Neck (Left) Axial T-bone CT shows similar but less severe changes of otosyphilis of the inner ear bones and ossicles , with remainder of the middle ear osseous structures and mastoid CT findings of the radiated temporal bone may mimic this appearance (Courtesy M Sandlin, MD.) (Right) Coronal T1 C+ MR reveals pathologic leptomeningeal enhancement in the internal auditory canals and membranous labyrinth This is the labyrinthitis-meningitis form of otosyphilis P.VI(4):35 TERMINOLOGY Synonyms Luetic labyrinthitis, osteitis, & meningitis Definitions Sexually transmitted inner ear disease caused by bacterium spirochete Treponema pallidum IMAGING General Features Best diagnostic clue T-bone “moth-eaten” permeative demineralization Location Otic capsule, IAC & CPA meninges CT Findings CECT If contrast needed, MR with contrast instead Bone CT Osteitis: “Moth-eaten” permeative bone change Inner ear, middle ear-mastoid, ossicles Labyrinthitis: Not seen on T-bone CT MR Findings T1WI Osteitis: Patchy areas of intermediate signal T2WI Osteitis: If severe, patchy high signal in otic capsule Labyrinthitis: ↑ signal of inner ear fluid possible IAC meningeal infection: Thickened CN7-8 T1WI C+ Osteitis: Patchy enhancing foci in otic capsule Labyrinthitis: Enhancement of fluid-filled spaces of inner ear IAC meningitis: Enhancement of leptomeninges within IAC, including CN7 & CN8 Imaging Recommendations Best imaging tool Osteitis: Axial & coronal T-bone CT Labyrinthitis & IAC meningitis: T1 C+ MR 1475 Diagnostic Imaging Head and Neck DIFFERENTIAL DIAGNOSIS Cochlear Otosclerosis Clinical: Mixed hearing loss Imaging: Patchy radiolucent foci throughout otic capsule T-Bone Osteogenesis Imperfecta Clinical: Children with brittle bones & blue sclera Imaging: Exact cochlear otosclerosis mimic except usually more severe T-Bone Paget Disease Clinical: Affects elderly Imaging: Otic capsule demineralization is diffuse, involves entire skull base T-Bone Fibrous Dysplasia Clinical: Under 30 year old patient group Imaging: Ground-glass expansile bone Postirradiated T-Bone Clinical: Post T-bone irradiation Imaging: Also “moth-eaten” otic capsule PATHOLOGY General Features Etiology Sexually transmitted spirochete Treponema pallidum Gross Pathologic & Surgical Features Endolymphatic duct rarely obstructed by gumma Microscopic Features Osteitis: Inflammatory resorptive osteitis Labyrinthitis: Obliterative endarteritis CLINICAL ISSUES Presentation Most common signs/symptoms Hearing loss (80%) & vertigo: Often acute & fluctuating Simulates Ménière disease Facial palsy; meningeal signs Clinical profile Diagnosis made when otologic symptoms are present with positive serology Otosyphilis is late manifestation Demographics Age Older patients Gender M>F Ethnicity African-Americans > Caucasians Epidemiology Incidence began to ↑ in 1980s due to AIDS Natural History & Prognosis 25% hearing loss improves after therapy 70% tinnitus & vertigo improves after therapy Best response when symptoms are fluctuating, hearing loss is < years duration, & patient is < 60 years old Treatment Antibiotics & corticosteroids DIAGNOSTIC CHECKLIST Consider If HIV patient with permeative inner demineralization, test for syphilis serology SELECTED REFERENCES Mishra S et al: Otosyphilis in HIV-coinfected individuals: a case series from Toronto, Canada AIDS Patient Care STDS 22(3):213-9, 2008 Yimtae K et al: Otosyphilis: a review of 85 cases Otolaryngol Head Neck Surg 136(1):67-71, 2007 1476 Diagnostic Imaging Head and Neck Labyrinthine Ossificans > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Infectious and Inflammatory Lesions > Labyrinthine Ossificans Labyrinthine Ossificans Troy Hutchins, MD Key Facts Terminology Membranous labyrinth ossification as healing response to infectious, inflammatory, traumatic, or surgical insult to inner ear Imaging T-bone CT: High-density bone deposition within membranous labyrinth T2 MR: Low intensity foci within high signal fluid of inner ear Top Differential Diagnoses Labyrinthine aplasia Cochlear aplasia Intravestibular lipoma Cochlear otosclerosis Labyrinthine schwannoma Pathology Fibrous stage: Fibroblast proliferation Ossific stage: Osteoblasts forming abnormal bony trabeculae within membranous labyrinthine spaces Clinical Issues Most common: Bilateral SNHL in child 2-18 months after acute meningitis episode Less common: Unilateral SNHL with previous surgery, trauma, mastoid/middle ear infection Diagnostic Checklist In pre-cochlear implant evaluation of T-bone in children, look for LO & inner ear congenital anomalies Radiologist should describe LO as “cochlear” or “noncochlear” (Left) Axial left T-bone CT shows severe ossification of the cochlea and lateral semicircular canal with mild ossification of the vestibule , typical findings of labyrinthine ossificans (LO) (Right) Axial T2WI MR in the same patient demonstrates low signal bone replacing the lateral semicircular canal with abnormally decreased signal in the cochlea and vestibule , characteristic MR findings of LO 1477 Diagnostic Imaging Head and Neck (Left) Axial left T-bone CT in a patient with moderate labyrinthine ossificans reveals hazy ossification of the cochlea , lateral semicircular canal , and vestibule (Right) Axial T2WI MR of the same patient shows characteristic decreased signal in the cochlea, lateral semicircular canal, and vestibule The cochlear nerve is atrophic and small, a common associated finding P.VI(4):37 TERMINOLOGY Abbreviations Labyrinthine ossificans (LO) Synonyms Labyrinthine ossification, ossifying labyrinthitis, chronic labyrinthitis Definitions Membranous labyrinth ossification as healing response to infectious, inflammatory, traumatic, or surgical insult to inner ear IMAGING General Features Best diagnostic clue T-bone CT: High-density bone deposition within membranous labyrinth T2 MR: Low intensity foci within high signal fluid of inner ear Location Membranous labyrinth fluid spaces Cochlear LO: Fluid spaces of cochlea itself affected Noncochlear: Fluid spaces of semicircular canals (SCCs) or vestibule affected Morphology Focal ossific plaques or diffuse ossification of membranous labyrinth CT Findings CECT No role in making LO diagnosis Bone CT Mild LO: Fibroosseous changes seen as hazy increase in density within fluid spaces of membranous labyrinth & prominent modiolus Moderate LO: Focal areas of bony encroachment on fluid spaces of membranous labyrinth May be cochlear, noncochlear, or both Severe LO: Membranous labyrinth completely obliterated by bone, replacing fluid spaces MR Findings T2WI Mild LO: Intermediate & low signal fibroosseous material partially replaces high signal fluid spaces of membranous labyrinth Associated with apparent “enlargement” of modiolus 1478 Diagnostic Imaging Head and Neck Moderate LO: Focal areas of low signal bone encroaching on high signal fluid spaces of membranous labyrinth May be cochlear, noncochlear, or both Severe LO: High signal membranous labyrinth absent, completely replaced by low signal bone Cochlear nerve often severely atrophied T1WI C+ Membranous labyrinthitis secondary to infection is usual precursor to LO In this pre-LO phase, membranous labyrinth enhances, signifying active labyrinthitis Enhancement may be holo-labyrinthine or segmental Enhancement may persist in ossifying stage of LO T2 MR used to differentiate enhancing labyrinthitis from intralabyrinthine schwannoma Labyrinthitis has high intralabyrinthine signal; intralabyrinthine schwannoma replaces high signal fluid in membranous labyrinth Imaging Recommendations Best imaging tool mm thick axial & coronal T-bone CT easiest imaging tool to diagnose LO High-resolution T2 MR imaging makes diagnosis Careful inspection for absent inner ear fluid spaces T2 MR imaging can show fibrous obliteration of membranous labyrinth whereas CT cannot T1 C+ MR very useful in showing enhancing inner ear in pre-LO phase with labyrinthitis DIFFERENTIAL DIAGNOSIS Labyrinthine or Cochlear Aplasia Clinical: Sensorineural hearing loss (SNHL) present from birth Imaging: Flattening of cochlear promontory Labyrinthine aplasia: Absent cochlea, vestibule, semicircular canals Cochlear aplasia: Absent cochlea Intravestibular Lipoma Clinical: Mild, high frequency SNHL often present Imaging: T1 MR high signal foci in vestibule CPA-IAC lipoma may be associated Cochlear Otosclerosis Clinical: Disease of young adults Imaging: CT radiolucent foci in bony labyrinth Does not encroach on membranous labyrinth, even in healing phase Labyrinthine Schwannoma Clinical: Protracted history of slowly progressive unilateral SNHL Imaging: T1 C+ MR shows focal intralabyrinthine enhancement T2 MR shows tissue intensity material within portion of membranous labyrinth PATHOLOGY General Features Etiology Suppurative membranous labyrinthitis → cascading inflammatory response in membranous labyrinth Begins with fibrosis, progresses to ossification (as early as months) LO 2° to suppurative labyrinthitis from multiple sources Meningogenic LO: 2° to meningitis; bilateral Tympanogenic LO: 2° to middle ear infection; unilateral Hematogenic LO: 2° to blood-borne infection such as measles or mumps (rare); bilateral LO may also arise after severe trauma or temporal bone surgery P.VI(4):38 Labyrinthitis progresses to labyrinthine ossificans when suppurative LO seen on T-bone CT as early as months after episode of meningitis Gross Pathologic & Surgical Features Bivalving inner ear of patient with LO shows new bone formation in membranous labyrinth At surgery for cochlear implantation, bony obstruction to implant entry through round window niche is observed Microscopic Features Fibrous stage: Fibroblast proliferation Ossific stage: Osteoblasts form abnormal bony trabeculae within membranous labyrinthine spaces 1479 Diagnostic Imaging Head and Neck Scala tympani in basal turn most frequent area of ossification in all causes of LO Meningitis → suppurative labyrinthitis associated with greatest amount of ossification CLINICAL ISSUES Presentation Most common signs/symptoms Bilateral SNHL Other signs/symptoms Severe vertigo infrequent but devastating Vertigo may be serious enough to require labyrinthectomy Clinical profile Bilateral SNHL in child 2-18 months after acute meningitis episode Other possible patient histories Suppurative middle ear infection (tympanogenic LO) Severe bout of mumps, measles, or other viral illness (hematogenic LO) Profound head & skull base trauma (post-traumatic LO) Previous temporal bone operation (postsurgical LO) Demographics Age Pediatric malady Epidemiology Meningogenic labyrinthitis is most common cause of acquired childhood deafness Most commonly from Streptococcus pneumoniae or Hemophilus influenzae 6-30% have some degree of hearing loss following meningitis Natural History & Prognosis Gradual deterioration of hearing following ear infection (unilateral) or meningitis, blood-borne infection, head trauma, or T-bone surgery (bilateral) Prognosis for SNHL is defined by response to cochlear implantation High-resolution axial T2WI MR shows high negative predictive value in predicting intraoperative cochlear obstruction Treatment Cochlear implantation used for SNHL correction, if cochlear nerve still present Bilateral cochlear LO is serious detriment to cochlear implantation Presurgical identification of cochlear LO is key! Allows planning for “drill-out” of obstructed cochlea & modifications of implant device “Drill-out,” newer cochlear implant devices available for obstructed cochlea Scala vestibuli insertion an alternative Labyrinthectomy used in cases of intractable vertigo DIAGNOSTIC CHECKLIST Consider In pre-cochlear implant evaluation of T-bone in children, look for LO & inner ear congenital anomalies Both these diagnoses will often force surgical plan to be individualized LO may contraindicate or complicate cochlear implantation Image Interpretation Pearls Radiologist should describe LO as “cochlear” or “noncochlear” Only describing LO of inner ear does not help cochlear implant surgeon decide what can be done Cochlear LO makes implant problematic Be specific about what noncochlear portions of membranous labyrinth are involved SELECTED REFERENCES Isaacson B et al: Labyrinthitis ossificans: how accurate is MRI in predicting cochlear obstruction? Otolaryngol Head Neck Surg 140(5):692-6, 2009 Ozgen B et al: Complete labyrinthine aplasia: clinical and radiologic findings with review of the literature AJNR Am J Neuroradiol 30(4):774-80, 2009 Berrettini S et al: Scala vestibuli cochlear implantation in patients with partially ossified cochleas J Laryngol Otol 116(11):946-50, 2002 Glastonbury CM et al: Imaging findings of cochlear nerve deficiency AJNR Am J Neuroradiol 23(4):635-43, 2002 Thomas J et al: Evaluation of cochlear implantation in post-meningitic adults J Laryngol Otol Suppl 24:27-33, 1999 Muren C et al: Postmeningitic labyrinthine ossification primarily affecting the semicircular canals Eur Radiol 7(2):208-13, 1997 1480 Diagnostic Imaging Head and Neck Johnson MH et al: CT of postmeningitic deafness: observations and predictive value of cochlear implants in children AJNR 16(1):103-9, 1995 Silberman B et al: Role of modern imaging technology in the implementation of pediatric cochlear implants Ann Otol Rhinol Laryngol 104(1):42-6, 1995 deSouza C et al: Pathology of labyrinthine ossification J Laryngol Otol 105(8):621-4, 1991 10 Novak MA et al: Labyrinthine ossification after meningitis: its implications for cochlear implantation Otolaryngol Head Neck Surg 103(3):351-6, 1990 11 Steenerson RL et al: Scala vestibuli cochlear implantation for labyrinthine ossification Am J Otol 11(5):360-3, 1990 12 Harnsberger HR et al: Cochlear implant candidates: assessment with CT and MR imaging Radiology 164(1):53-7, 1987 13 Swartz JD et al: Labyrinthine ossification: etiologies and CT findings Radiology 157(2):395-8, 1985 P.VI(4):39 Image Gallery (Left) Axial right T-bone CT demonstrates complete ossification of the lateral semicircular canal , near complete ossification of the vestibule , and mixed ossification of the cochlea (Right) Axial T2WI MR of the same patient reveals low signal in regions of ossification with small focus of residual vestibular fluid Patient had similar left ear findings and a history of SNHL following childhood meningitis These are typical findings of labyrinthine ossificans post meningitis (Left) Axial left T-bone CT shows ossific plaque in the vestibule from LO with osseous thickening of the modiolus This “large modiolus” is due to fibroosseous changes sometimes seen in less severe LO of the cochlea (Right) Axial T2WI MR at same level again shows a “large modiolus” from fibroosseous LO, with vestibular ossific plaque of 1481 Diagnostic Imaging Head and Neck LO , and near complete loss of signal (obliterative LO) in the lateral semicircular canal (Left) Axial right T-bone CT in a patient with previous mastoidectomy and right SNHL shows severe osseous thickening of the cochlear modiolus representing postoperative labyrinthine ossificans (Right) Sagittal T2WI MR through the IAC in a patient with ipsilateral severe cochlear labyrinthine ossificans shows severe atrophy of the cochlear nerve compared with the normal facial nerve and vestibular nerves , a common associated finding in severe LO Otosclerosis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Infectious and Inflammatory Lesions > Otosclerosis Otosclerosis Troy Hutchins, MD Key Facts Terminology Synonym: Otospongiosis Types: Fenestral otosclerosis (FOto), cochlear otosclerosis (COto) Pathologic appearance of lytic spongy bone foci in bony labyrinth of unknown cause Starts perifenestral (FOto), progresses to surround cochlea (FOto + COto) Fissula ante fenestram: Cleft of fibrocartilaginous tissue between inner & middle ears just anterior to oval window Imaging Best diagnostic clue: T-bone CT shows lytic (otospongiotic) foci involving bony labyrinth FOto: Starts at anterior margin oval window (fissula ante fenestram) COto: Affects pericochlear bony labyrinth Top Differential Diagnoses Chronic otitis media with tympanosclerosis T-bone Paget disease T-bone fibrous dysplasia T-bone osteoradionecrosis T-bone osteogenesis imperfecta Pathology Enchondral layer of bony labyrinth displays spongy, vascular, decalcified, irregular bone formation Clinical Issues Bilateral progressive conductive (FOto) or mixed (FOto + COto) hearing loss in young adult Diagnostic Checklist Typical otospongiotic plaques of “otosclerosis” are lytic and affect bony labyrinth 1482 Diagnostic Imaging Head and Neck (Left) Coronal graphic illustrates findings of fenestral otosclerosis, with a “donut” otospongiotic plaque surrounding the stapes footplate in the oval window The crisp margins of the oval window are obscured by plaque (Right) Coronal right T-bone CT shows a lytic focus anterior to the oval window , the typical appearance and location of an otospongiotic plaque of fenestral otosclerosis (Left) Axial graphic demonstrates classic example of cochlear otosclerosis Note otospongiotic plaques in halo around cochlea , with concurrent fenestral otosclerosis (Right) Axial left T-bone CT shows cochlear otosclerosis as osteolytic foci surrounding the cochlea Concurrent fenestral otosclerosis is noted as bony lucency along cochlear promontory extending from fissula ante fenestram P.VI(4):41 TERMINOLOGY Abbreviations Fenestral otosclerosis (FOto) Cochlear otosclerosis (COto) Synonyms Otospongiosis, fenestral otospongiosis, cochlear otospongiosis Definitions Pathologic appearance of lytic spongy bone foci in bony labyrinth of unknown cause Starts perifenestral (FOto), progresses to surround cochlea (FOto + COto) Fissula ante fenestram: Cleft of fibrocartilaginous tissue between inner & middle ears just anterior to oval window Also called “cochlear cleft” IMAGING 1483 Diagnostic Imaging Head and Neck General Features Best diagnostic clue T-bone CT: Lytic (otospongiotic) foci involving bony labyrinth Location FOto: Starts at anterior margin of oval window (fissula ante fenestram) May involve any bony area along medial wall of middle ear COto: Affects pericochlear bony labyrinth May involve any portion of bony labyrinth Size Millimeter punctate or linear foci; may become confluent Morphology FOto: Ovoid plaques most common COto: Ovoid to linear (confluent foci) CT Findings CECT No role for CECT in diagnosis of otosclerosis Bone CT Early T-bone CT findings Begins as radiolucent focus at oval window anterior margin (FOto) Spreads to involve all margins of oval & round windows May spread to inner ear otic capsule (COto) “Double ring” sign or “halo” of radiolucency surrounds cochlea in severe COto Progressive disease may involve any portion of bony labyrinth, including internal auditory canal lateral walls Late, chronic (healing phase) T-bone CT findings FOto: “Heaped up” new bone along oval & round window margins Healed plaque may occlude oval ± round window COto: Mixed radiolucent-radiodense foci present in bony labyrinth MR Findings T2WI Thin section high-resolution T2 may not visualize otosclerosis, even when extensive Large plaques may show subtle increased signal T1WI C+ Enhancing punctate foci in medial wall of middle ear (FOto) ± pericochlear bony labyrinth (COto) Most obvious when FOto & COto combined Enhancing lesions may be seen anywhere in bony labyrinth in severe cases Imaging Recommendations Best imaging tool Temporal bone CT Protocol advice T1 C+ MR shows enhancing foci in active phase of otosclerosis High-resolution T2 MR may miss otosclerosis DIFFERENTIAL DIAGNOSIS Chronic Otitis Media with Tympanosclerosis Clinical: Obvious chronic middle ear-mastoid inflammatory disease Imaging: Post-inflammatory new bone deposition is not limited to oval & round windows as with most FOto Seen in tympanic membrane (TM), middle ear, ossicles, and mastoids New bone deposition is irregular, not smooth in oval window area T-Bone Paget Disease Clinical: Bone disease of old age (> 50 years) Imaging: Diffuse skull base involvement is rule Diffuse involvement of bony labyrinth, not confined to lateral wall Usually seen as diffuse temporal bone “cotton-wool” appearance T-Bone Fibrous Dysplasia Clinical: Bone disease of young (< 30 years) Imaging: Involves all parts of temporal bone Relative sparing of inner ear is rule Usually sclerotic, ground-glass in appearance T-Bone Osteoradionecrosis 1484 Diagnostic Imaging Head and Neck Clinical: History of skull base or nasopharyngeal radiation therapy Imaging: CT shows diffuse, permeative lucencies of otic capsule T-Bone Osteogenesis Imperfecta Clinical: Blue sclera; patients with mild form develop deafness by age 40 years Imaging: Looks like severe COto with more generalized demineralization of bony labyrinth PATHOLOGY General Features Etiology Otosclerosis etiology unknown Genetics Sporadic or autosomal dominant gene transmission Bony otic capsule development: layers P.VI(4):42 Thin inner endosteal layer Middle layer of combined endochondral & intrachondral bone (otosclerosis occurs here) Outer periosteal layer Normal otosclerosis progression Begins at fissula ante fenestram (FOto) Disease spreads from fissula ante fenestram posteriorly along oval window margins to round window Continued active disease spreads to otic capsule (both FOto & COto present) Active FOto fixes stapes footplate in oval window niche This “donut” FOto ankyloses stapes footplate Pathophysiology of conductive hearing loss COto leads to sensorineural hearing loss Best hypothesis: Spiral ligament becomes compromised Secondary hypothesis: Toxic proteases affect cochlear nerve cells Staging, Grading, & Classification Symons/Fanning CT grading system of otosclerosis (2005) has high intra- and interobserver agreement Grade 1: Solely fenestral Grade 2: Patchy localized cochlear disease (± fenestral involvement) To basal cochlear turn (grade 2A) To middle/apical turns (grade 2B) Grade 3: Diffuse confluent cochlear involvement (± fenestral involvement) Gross Pathologic & Surgical Features Otoscopic vascular hue behind tympanic membrane = Schwartze sign Represents active otosclerotic areas along margins of oval & round windows or just beneath cochlear promontory Bony ankylosis of stapes footplate is reflected as stapes immobilization when pulled on by surgeon Microscopic Features Enchondral layer of bony labyrinth displays spongy, vascular, decalcified, irregular bone formation pathologic phases of otosclerosis Acute phase: Deposition of islets of osteoid tissue Subacute phase: Spongiotic remodeling with osteoclasts causing focal bone resorption Chronic-sclerotic phase: Osteoblasts create new bone with irregular features resembling mosaic “Otospongiosis” better describes active disease process Chronic, healing phase appears truly sclerotic May be histologically indistinguishable from Paget disease CLINICAL ISSUES Presentation Most common signs/symptoms Bilateral progressive conductive (FOto) or mixed (FOto + COto) hearing loss Other signs/symptoms Tinnitus (ringing in ears) Otoscopy: Vascular hue behind tympanic membrane = Schwartze sign Clinical profile Young adult presents with unexplained bilateral progressive conductive (FOto) or mixed (FOto + COto) hearing loss 1485 Diagnostic Imaging Head and Neck Demographics Age Appears in 2nd to 3rd decades of life Gender M:F = 1:2 Epidemiology Occurs in 1% of population Most common type of otosclerosis is FOto alone (85%); COto found in 15% In adult patients with conductive hearing loss, FOto responsible in ˜ 90% Natural History & Prognosis FOto: Conductive hearing loss is progressive COto: Untreated will gradually worsen to profound hearing loss Treatment FOto: Stapedectomy with stapes prosthesis Results negatively impacted by concurrent COto If round window is obliterated, stapedectomy will fail Cochlear implantation Used when severe FOto & COto present bilaterally resulting in profound mixed hearing loss If round window obliteration present bilaterally, cochlear implantation may be more challenging Fluoride treatment if COto present Early treatment can arrest progression DIAGNOSTIC CHECKLIST Consider Always check oval window anterior margin for FOto in CT evaluation of conductive hearing loss Common “blind spot”; CT findings can be subtle If COto present, FOto also is present so look for it! Multidetector CT sometimes shows normal fissula ante fenestram on pediatric T-bone exams as focal radiolucency Image Interpretation Pearls Typical otospongiotic plaques of “otosclerosis” are lytic and affect bony labyrinth If bony encroachment is on membranous labyrinth, diagnosis is labyrinthine ossificans, not COto SELECTED REFERENCES Lee TC et al: CT grading of otosclerosis AJNR Am J Neuroradiol 30(7):1435-9, 2009 Marshall AH et al: Cochlear implantation in cochlear otosclerosis Laryngoscope 115(10):1728-33, 2005 Chadwell JB et al: The cochlear cleft AJNR Am J Neuroradiol 25(1):21-4, 2004 Pekkola J et al: Localized pericochlear hypoattenuating foci at temporal-bone thin-section CT in pediatric patients: nonpathologic differential diagnostic entity? Radiology 230(1):88-92, 2004 P.VI(4):43 Image Gallery 1486 Diagnostic Imaging Head and Neck (Left) Magnified axial right T-bone CT in a young adult with progressive conductive hearing loss demonstrates typical otospongiotic plaque of fenestral otosclerosis anterior to the oval window in the expected location of the fissula ante fenestram (Right) Coronal right T-bone in a patient with mixed hearing loss shows “halo” of radiolucency surrounding the cochlea representing cochlear otosclerosis Also note the associated fenestral otosclerosis (Left) Axial right T-bone CT reveals “heaped up” mixed sclerotic and lucent plaque anterior to the oval window and involving the fissula ante fenestram This represents a healing (sclerotic portion) but active (lucent portion) plaque of fenestral otosclerosis (Right) Coronal right T-bone CT in the same patient again shows mixed sclerotic and lucent plaque This appearance with sclerotic healing portion is less common than the pure lytic lesion typically seen in fenestral otosclerosis (Left) Axial left T-bone CT shows typical lytic plaques of combined fenestral and cochlear otosclerosis The patient has undergone stapedectomy with insertion of a stapes prosthesis Note the metallic density stapes prosthesis (Right) Axial T1WI C+ FS MR in the same patient reveals enhancement anterior to the oval window (fissula ante fenestram) and surrounding the cochlea representing active fenestral and cochlear otosclerosis, respectively Benign and Malignant Tumors Intralabyrinthine Schwannoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Benign and Malignant Tumors > Intralabyrinthine Schwannoma Intralabyrinthine Schwannoma Karen L Salzman, MD Key Facts 1487 Diagnostic Imaging Head and Neck Terminology Benign tumor arising from Schwann cells within structures of membranous labyrinth Imaging T1 C+ MR: Focal enhancing mass in membranous labyrinth High-resolution T2 MR: “Filling defect” within hyperintense perilymph Focal intralabyrinthine mass named by location Intracochlear: Schwannoma within cochlea Intravestibular: Within vestibule of inner ear Vestibulocochlear: Involves both vestibule & cochlea Transmodiolar: Crosses modiolus from cochlea to fundus of IAC Transmacular: Crosses from vestibule into fundus of IAC Transotic: Involves inner ear from fundus of IAC to middle ear Use focused T1 C+ or high-resolution T2 imaging of CPA-IAC to make diagnosis of ILS Top Differential Diagnoses Labyrinthitis Labyrinthine ossificans Intralabyrinthine hemorrhage Facial nerve schwannoma with inner ear dehiscence Clinical Issues Tumor location-specific symptoms When in vestibule: Tinnitus, episodic vertigo with nausea & vomiting, mixed hearing loss When in cochlea: Slowly progressive SNHL Treatment: Conservative management vs surgical resection (Left) Axial T2WI MR shows a classic example of an intralabyrinthine schwannoma This is a vestibulocochlear type as it involves both the vestibule and cochlea Notice the tumor is soft tissue intensity, replacing the normal perilymphatic tissue of the membranous labyrinth (Right) Axial T1WI C+ MR shows an intracochlear schwannoma as focal enhancement of the cochlea It is important to review pre-contrast T1 & T2WI to exclude intralabyrinthine hemorrhage & labyrinthitis, which may mimic this tumor 1488 Diagnostic Imaging Head and Neck (Left) Coronal T2WI MR shows a soft tissue filling defect in the left vestibule, replacing the normal high intensity perilymphatic fluid This intravestibular type of intralabyrinthine schwannoma often presents with vertigo or tinnitus (Right) Axial T1WI C+ MR in the same patient shows intense enhancement of this intravestibular schwannoma When these tumors are small, they may be treated conservatively unless the patient has intractable vertigo or the tumor shows signs of interval growth P.VI(4):45 TERMINOLOGY Abbreviations Intralabyrinthine schwannoma (ILS) Synonyms Inner ear schwannoma Definitions ILS: Benign tumor arising from Schwann cells within structures of membranous labyrinth Includes schwannomas of cochlea, vestibule, or both, as well as tumors of inner ear extending to IAC or middle ear IMAGING General Features Best diagnostic clue T1 C+ MR: Focal enhancing mass in membranous labyrinth High-resolution T2 MR: “Filling defect” within hyperintense perilymph Location Focal intralabyrinthine mass named by location Intracochlear: Schwannoma within cochlea Intravestibular: Schwannoma within vestibule of inner ear Vestibulocochlear: Schwannoma involves both vestibule & cochlea Transmodiolar: Schwannoma crosses modiolus from cochlea to fundus of IAC Transmacular: Schwannoma crosses from vestibule into fundus of IAC Transotic: Schwannoma crosses entire inner ear from fundus of IAC to middle ear Size Usually remains in millimeter range within membranous labyrinth Larger lesions extend extralabyrinthine Morphology Early, small lesions are ovoid to round Older, larger lesions take on shape of portion of membranous labyrinth affected CT Findings NECT Typically normal, ILS not seen CECT ILS not visible on CECT even if thin sections are obtained 1489 Diagnostic Imaging Head and Neck Bone CT Normal, unless mass projects into middle ear through round window niche In very large lesions (transmodiolar, transmacular, transotic), bone erosion may be visible Bone CT usually not helpful in making this diagnosis MR Findings T1WI Soft tissue intensity material in inner ear May be mildly hyperintense to fluid of labyrinth Not seen unless larger lesion is present & thinner sections are obtained T2WI Focal low signal mass within high signal fluids of membranous labyrinth T1WI C+ Homogeneous enhancement of ILS ILS may project multiple directions from inner ear Through round window into middle ear Along vestibular nerve branches into fundus of IAC = transmacular ILS Through modiolus & cochlear nerve canal into IAC = transmodiolar ILS Imaging Recommendations Use focused T1 C+ or high-resolution T2 imaging of CPA-IAC to make diagnosis of ILS Careful examination of all “rule out acoustic” MR scans for presence of intralabyrinthine mass is critical Observe precise location of tumor Consider if it involves vestibule, cochlea, or both Consider if it projects into middle ear or IAC fundus All patients undergoing surgery for Ménière disease should undergo preoperative focused MR imaging to exclude ILS DIFFERENTIAL DIAGNOSIS Labyrinthitis Clinical: Acute onset sensorineural hearing loss (SNHL) ± vertigo & facial neuropathy High-resolution T2 MR: No tissue intensity mass seen within high signal inner ear fluid T1 C+ MR: Enhancement of most or all of membranous labyrinth Labyrinthine Ossificans Clinical: History of previous meningitis or suppurative middle ear-mastoiditis High-resolution T2 MR: Focal low signal areas within high signal inner ear fluid; when fibroosseous, may mimic ILS T1 C+ MR: Minimal or no inner ear enhancement Bone CT: Encroachment on fluid of membranous labyrinth by bone Intralabyrinthine Hemorrhage Clinical: Unilateral sudden onset SNHL T1 MR: High signal fluid within membranous labyrinth Facial Nerve Schwannoma with Dehiscence into Inner Ear Clinical: SNHL with associated facial neuropathy T1 C+ MR: Enhancing tubular mass follows course of intratemporal facial nerve canal Involvement of inner ear is secondary finding Bone CT: Smooth enlargement of intratemporal facial nerve canal PATHOLOGY General Features Etiology Tumor arises from Schwann cells wrapping distal vestibular or cochlear nerve axons within membranous labyrinth P.VI(4):46 Secondary endolymphatic hydrops explains Ménière symptoms Same pathology as other schwannomas in human body Gross Pathologic & Surgical Features Tan-gray, encapsulated mass found within labyrinth Microscopic Features Differentiated neoplastic Schwann cells Antoni A: Areas of compact, elongated cells Antoni B: Less densely cellular areas with tumor loosely arranged, ± clusters of lipid-laden cells 1490 Diagnostic Imaging Head and Neck Strong, diffuse expression of S100 protein CLINICAL ISSUES Presentation Most common signs/symptoms Unilateral sensorineural hearing loss Tumor location-specific symptoms When in vestibule: Tinnitus, episodic vertigo with nausea & vomiting, mixed hearing loss (tumor impedes stapes footplate, creating element of conductive hearing loss) When in cochlea: Slowly progressive SNHL Clinical profile Unilateral SNHL that develops over decades Demographics Age Adults over 40 years of age Gender No gender predilection Epidemiology Rare lesion Perhaps 100x less common than CPA-IAC vestibular schwannoma Natural History & Prognosis Very slow-growing, benign tumor of membranous labyrinth History of progressive hearing loss may date back 20 years Often grows to fill inner ear, then stops growing Total deafness in ear will result eventually if left alone Deafness certain if tumor removed Treatment Conservative management Watchful waiting Applied when symptoms are minor (serviceable hearing maintained) & tumor is confined to inner ear Surgical removal Translabyrinthine surgery removes tumor in vestibule Transotic surgery completed for tumors involving cochlea or middle ear Completed if symptoms are disabling Usually when there is intractable vertigo If transmodiolar or transmacular extension is significant, middle cranial fossa approach may be used DIAGNOSTIC CHECKLIST Consider ILS may be missed diagnosis by excellent radiologists because they are not aware of its existence ILS now being diagnosed more often with high-resolution T2 imaging (CISS, FIESTA, 3D-TSE) Increased diagnosis in part secondary to ↑ awareness of this lesion Some ILS not enhance robustly but can be seen on high-resolution T2 MR Image Interpretation Pearls When visually interrogating MR images to “rule out acoustic schwannoma,” remember to carefully evaluate inner ear fluid spaces for ILS Unless radiologists specifically look at inner ear for focal lesions, ILS will be missed Once ILS is suspected, use high-resolution T2 MR to differentiate ILS from labyrinthitis ILS will appear as tissue intensity lesion within high signal inner ear fluid Labyrinthitis will show no such focal mass within high signal inner ear fluid SELECTED REFERENCES Iseri M et al: Hearing loss owing to intralabyrinthine schwannoma responsive to intratympanic steroid treatment J Otolaryngol Head Neck Surg 38(3):E95-7, 2009 Jia H et al: Intralabyrinthine schwannomas: symptoms and managements Auris Nasus Larynx 35(1):131-6, 2008 Nishimura T et al: Progressive hearing loss in intracochlear schwannoma Eur Arch Otorhinolaryngol 265(4):489-92, 2008 Tieleman A et al: Imaging of intralabyrinthine schwannomas: a retrospective study of 52 cases with emphasis on lesion growth AJNR Am J Neuroradiol 29(5):898-905, 2008 Di Lella F et al: Management of intralabyrinthine schwannomas Auris Nasus Larynx 34(4):459-63, 2007 Hamed A et al: Intralabyrinthine schwannoma Otol Neurotol 26(5):1085-6, 2005 1491 Diagnostic Imaging Head and Neck Kennedy RJ et al: Intralabyrinthine schwannomas: diagnosis, management, and a new classification system Otol Neurotol 25(2):160-7, 2004 Falcioni M et al: Inner ear extension of vestibular schwannomas Laryngoscope 113(9):1605-8, 2003 Jackson LE et al: Intralabyrinthine schwannoma: subtle differentiating symptomatology Otolaryngol Head Neck Surg 129(4):439-40, 2003 10 Neff BA et al: Intralabyrinthine schwannomas Otol Neurotol 24(2):299-307, 2003 11 Fitzgerald DC et al: Intralabyrinthine schwannomas Am J Otol 20(3):381-5, 1999 12 Green JD Jr et al: Diagnosis and management of intralabyrinthine schwannomas Laryngoscope 109(10):1626-31, 1999 13 Zbar RI et al: Invisible culprit: intralabyrinthine schwannomas that not appear on enhanced magnetic resonance imaging Ann Otol Rhinol Laryngol 106(9):739-42, 1997 14 Mafee MF: MR imaging of intralabyrinthine schwannoma, labyrinthitis, and other labyrinthine pathology Otolaryngol Clin North Am 28(3):407-30, 1995 P.VI(4):47 Image Gallery (Left) Axial T1WI MR shows slightly hyperintense signal within the vestibule and cochlea of this patient with a vestibulocochlear schwannoma (Right) Axial T2WI MR shows soft tissue intensity material replacing the normal fluid signal of the vestibule and cochlea in this patient with a vestibulocochlear type of intralabyrinthine schwannoma These tumors are being recognized more frequently with the use of high-resolution T2 MR and increased awareness of the lesion (Left) Axial T2WI MR shows a transmacular type of intralabyrinthine schwannoma as soft tissue intensity material 1492 Diagnostic Imaging Head and Neck filling the vestibule and coursing along the vestibular nerve branches into the distal fundus of the IAC (Right) Axial T1WI C+ MR in the same patient shows enhancement of both the intravestibular and distal intracanalicular portion of this transmacular schwannoma The slight difference in enhancement characteristics is related to volume averaging (Left) Axial T1WI C+ MR shows enhancement of the distal IAC fundus and cochlea in this transmodiolar type of intralabyrinthine schwannoma This tumor grew from the cochlea through the modiolus and cochlear nerve canal to reach the IAC fundus (Right) Axial T1WI C+ FS MR shows the very rare transotic type of intralabyrinthine schwannoma Note the enhancing tumor extends from the CPA through the IAC and also involves the inner ear and middle ear Endolymphatic Sac Tumor > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Benign and Malignant Tumors > Endolymphatic Sac Tumor Endolymphatic Sac Tumor Hilda E Stambuk, MD Key Facts Terminology Endolymphatic sac (ELS) tumor (ELST) Papillary cystadenomatous tumor of ELS Imaging CT findings Permeative destructive retrolabyrinthine mass Central spiculated tumor Ca++ (100%) Thin calcified rim along posterior margin of small tumor MR findings T1 hyperintense foci in 80% Inhomogeneous T2 signal Heterogeneous enhancement Angiographic findings Tumors < cm supplied by ECA branches Tumors > cm also recruit ICA branches Top Differential Diagnoses Petrous apex cholesterol granuloma Glomus jugulare paraganglioma Jugular foramen schwannoma Jugular foramen meningioma Pathology Sporadic occurrence > VHL associated ELST 15% VHL patients develop ELST → 30% bilateral von Hippel-Lindau disease 1493 Diagnostic Imaging Head and Neck Cerebellar & spinal cord hemangioblastoma, renal cell carcinoma, pheochromocytoma Kidney & pancreas cysts Clinical Issues Sensorineural hearing loss = most common symptom Treatment: Complete surgical resection If sporadic ELST, check patient & family for VHL (Left) Axial graphic of T-bone illustrates typical appearance of ELST Important features include its vascular nature, its tendency to fistulize inner ear , & bone fragments within tumor matrix Note the classic retrolabyrinthine location between the IAC and sigmoid sinus (Right) Axial bone CT shows imaging features of ELST, including 1) tumor centered in posterior T-bone in area of fovea of the endolymphatic sac, 2) spiculated tumor matrix Ca++ , and 3) permeative bone changes (Left) Axial T1WI MR shows an expansile lobular mass centered in the left T-bone with areas of ↑ T1 signal, which are common in ELST and are typically peripheral in location (Right) Axial T1WI C+ FS MR in the same patient reveals the typical intense, heterogeneous contrast enhancement expected in ELST This tumor has also grown into the left IAC , middle ear , & mastoid Note diffuse abnormal signal in left globe indicating retinal angioma with detachment seen in VHL disease P.VI(4):49 TERMINOLOGY Abbreviations Endolymphatic sac (ELS) tumor (ELST) Synonyms 1494 Diagnostic Imaging Head and Neck Adenomatous tumor of ELS, Heffner tumor Definitions Papillary cystadenomatous tumor of ELS IMAGING General Features Best diagnostic clue Bone CT: Central intratumoral bone spicules & posterior rim Ca++ MR: High signal foci on unenhanced T1 Location Retrolabyrinthine location Size Smaller now that von Hippel-Lindau disease (VHL) screening in progress CT Findings Bone CT Permeative destructive retrolabyrinthine mass Central spiculated tumor Ca++ (100%) Thin calcified rim, posterior margin small tumor MR Findings T1WI Hyperintense foci in 80% Secondary to hemorrhage, slow flow, protein content, cholesterol cleft Tumors > cm may have flow voids T1WI C+ Heterogeneous enhancement Angiographic Findings Tumors < cm supplied by ECA branches Tumors > cm also recruit ICA branches DIFFERENTIAL DIAGNOSIS Petrous Apex Cholesterol Granuloma Imaging findings Bone CT: Smooth expansile margins MR: Entire lesion has ↑ signal on T1 & T2 Glomus Jugulare Paraganglioma Imaging findings Bone CT: Permeative-destructive bone invasion without spicules MR: ↑ T1 foci rare; T2 flow voids very common Jugular Foramen Schwannoma Imaging findings Bone CT: Smooth enlargement of jugular foramen T1 C+ MR: Uniform enhancement; intramural cysts Jugular Foramen Meningioma Imaging findings Bone CT: Scalloped margins ± hyperostosis ± permeative sclerotic bones MR: T1 C+ homogeneous enhancement; dural tail; T2 uniform ↓ signal PATHOLOGY General Features Genetics Sporadic > VHL ELST VHL tumor suppressor gene mutated in both Associated abnormalities 15% VHL patients develop ELST 30% of these have bilateral ELST Staging, Grading, & Classification Grade I: Confined to T-bone, middle ear, ± EAC Grade II: Posterior cranial fossa extension Grade III: Posterior & middle fossa extension Grade IV: Clival ± sphenoid wing extension CLINICAL ISSUES Presentation 1495 Diagnostic Imaging Head and Neck Most common signs/symptoms Sensorineural hearing loss ELST may not be visible on imaging for years Other signs/symptoms Tinnitus, vertigo (confused with Ménière) Facial nerve palsy Demographics Age Sporadic 50 years; VHL 30 years old Natural History & Prognosis Prognosis excellent with complete surgical resection VHL ELST found earlier (annual MR screening) Late recurrence possible (slow growth rate of tumor) Long-term imaging follow-up recommended Treatment Complete surgical resection Retrolabyrinthine approach for small tumor preserves hearing Preoperative embolization for larger lesions Radiation therapy for unresectable lesion or nonsurgical candidate If sporadic ELST, check patient & family for VHL DIAGNOSTIC CHECKLIST Consider VHL is diagnosis if bilateral ELST Image Interpretation Pearls Posterior wall T-bone tumor with ↑ T1 foci = ELST SELECTED REFERENCES Lalwani AK: Endolymphatic sac tumors in von Hippel-Lindau disease Arch Otolaryngol Head Neck Surg 133(9):857, 2007 Patel NP et al: The radiologic diagnosis of endolymphatic sac tumors Laryngoscope 116(1):40-6, 2006 Miscellaneous Intralabyrinthine Hemorrhage > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Miscellaneous > Intralabyrinthine Hemorrhage Intralabyrinthine Hemorrhage Troy Hutchins, MD Key Facts Terminology Blood within normally fluid-filled spaces of labyrinth Imaging T1 MR: High signal within normally fluid-filled space of labyrinth T2 MR: High signal looks normal T1 C+: High signal, not to be confused with enhancement T1 FS: High IE signal remains on fat-saturated images Not if intralabyrinthine lipoma present Top Differential Diagnoses Labyrinthitis Vestibular schwannoma Intralabyrinthine schwannoma Congenital intralabyrinthine lipoma Pathology Shortened T1 relaxation time caused by intra-/extracellular methemoglobin Clinical Issues Presentation: Acute onset unilateral SNHL History: Anticoagulant therapy, sickle cell disease, or trauma Prognosis: Variable return of hearing Treatment: Aimed at underlying condition Diagnostic Checklist 1496 Diagnostic Imaging Head and Neck Always perform unenhanced T1 MR & evaluate for evidence of intralabyrinthine high signal Differentiate from intralabyrinthine lipoma with fat-saturated images (Left) Axial T1WI MR without contrast shows the classic findings of intralabyrinthine hemorrhage, with hyperintense blood (methemoglobin) within the membranous labyrinth of the cochlea , vestibule , and semicircular canals (Right) Axial T2WI MR in the same patient reveals preservation of high fluid signal within the inner ear , differentiating this case of ILH from the rare hemorrhagic intralabyrinthine schwannoma, which would have low T2 signal (Left) Axial T1WI MR without contrast at the level of the IACs shows hyperintense signal in the left inner ear membranous labyrinth , representing intralabyrinthine hemorrhage Compare to normal fluid signal on the right (Right) Coronal T1WI FS MR in the same patient demonstrates that the high signal in the left inner ear is not fat, as it persists despite fat saturation sequence Findings exclude the possibility of intralabyrinthine lipoma and confirm the diagnosis of ILH P.VI(4):51 TERMINOLOGY Abbreviations Intralabyrinthine hemorrhage (ILH) Synonyms Inner ear (IE) hemorrhage, membranous labyrinthine hemorrhage, perilymphatic labyrinthine hemorrhage Definitions Blood within normally fluid-filled spaces of labyrinth IMAGING 1497 Diagnostic Imaging Head and Neck General Features Best diagnostic clue Bright signal on T1 nonenhanced MR of IE Inner ear fluid normally isointense with CSF Highly proteinaceous inner ear contents may have identical appearance Location Membranous labyrinth of inner ear Size May be diffuse or segmental within inner ear spaces Morphology Conforms to inner ear shape MR Findings T1WI High signal within normally fluid-filled space of labyrinth on nonenhanced T1 Inner ear normally low signal (fluid intensity) T2WI High signal looks normal Inner ear hemorrhage not visible on thin section high-resolution T2 imaging T1WI C+ High signal already present If pre-contrast imaging not done, may be mistaken for inner ear enhancement Imaging Recommendations Protocol advice Include at least nonenhanced T1 sequence in all inner ear protocols DIFFERENTIAL DIAGNOSIS Labyrinthitis T1 C+ MR high signal (enhancement) Focal or diffuse, usually faint Unenhanced T1 usually normal Vestibular Schwannoma Intralabyrinthine ↑ on unenhanced T1 MR from high protein content Often postoperative finding Intralabyrinthine Schwannoma T1 C+ MR ↑ signal (focal intense enhancement) Congenital Intralabyrinthine Lipoma Unenhanced T1 ↑ signal may appear identical T1 fat saturated: Lesion no longer seen (saturates) PATHOLOGY General Features Etiology Intralabyrinthine hemorrhage inciting events Trauma Anticoagulant therapy Hematologic lesions: Leukemia, sickle cell anemia, & other hyperviscosity syndromes Neoplasm Shortened T1 relaxation time caused by intra-/extracellular methemoglobin CLINICAL ISSUES Presentation Most common signs/symptoms Acute onset unilateral SNHL Sudden hearing loss: Hearing loss that has evolved over hours to days At least 30 decibel ↓ in threshold in contiguous test frequencies over 24-72 hour period Other signs/symptoms Vertigo, tinnitus Clinical profile Patient with history of anticoagulant therapy, sickle cell disease, or trauma Demographics Age Possible at any age 1498 Diagnostic Imaging Head and Neck Ethnicity Spontaneous ILH more common in African-Americans due to increased incidence in sickle cell disease Natural History & Prognosis Prognosis same as for underlying condition Return of hearing is variable Treatment None unless underlying condition exists Treat underlying condition DIAGNOSTIC CHECKLIST Consider Intravestibular lipoma also has increased unenhanced T1 signal Will lose its signal (saturate) on fat-saturated images Image Interpretation Pearls Always perform unenhanced T1 & evaluate for evidence of intralabyrinthine high signal SELECTED REFERENCES Rosado WM Jr et al: Sudden onset of sensorineural hearing loss secondary to intralabyrinthine hemorrhage: MRI findings Ear Nose Throat J 87(3):130-1, 2008 Shinohara S et al: Clinical features of sudden hearing loss associated with a high signal in the labyrinth on unenhanced T1-weighted magnetic resonance imaging Eur Arch Otorhinolaryngol 257(9):480-4, 2000 Semicircular Canal Dehiscence > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Miscellaneous > Semicircular Canal Dehiscence Semicircular Canal Dehiscence Troy Hutchins, MD Key Facts Terminology Defined as extreme thinning or absence of bony roof over superior or posterior semicircular canal Imaging Coronal T-bone CT: ≥ mm dehiscence of roof of superior semicircular canal Thinning of tegmen tympani may be associated Transverse oblique T-bone CT reformats In-plane view of SSCC dehiscent roof Axial T-bone CT Provides in-plane view of dehiscence of superficial bony wall of PSCC Pathology Unknown; most likely a developmental anomaly Results in “unphysiological motion” of endolymph in affected semicircular canal Best hypothesis for clinical findings Bony opening overlying semicircular canal creates “3rd mobile window” into inner ear 3rd window allows canal to respond to sound & pressure changes in membranous labyrinth Clinical Issues Sound ± pressure-induced vestibular symptoms ± eye movements Tullio phenomenon Vertigo ± nystagmus related to sound Treatable form of vestibular disturbance Diagnostic Checklist Vestibular symptoms + positive bone CT = semicircular canal dehiscence syndrome Since usually unilateral, use opposite semicircular canal bony cover as baseline normal to compare with suspicious side 1499 Diagnostic Imaging Head and Neck (Left) Coronal graphic illustrates the principal findings of superior semicircular canal dehiscence, absence of bone overlying the superior semicircular canal and associated thinning of tegmen tympani (Right) Coronal T-bone CT shows no bone covering the roof of the superior semicircular canal representing superior semicircular canal dehiscence Note thinning of the tegmen tympani , a common associated finding on temporal bone CT (Left) Coronal T2WI MR reveals absence of cortical bone covering the superior semicircular canal , diagnostic of superior semicircular canal dehiscence (Right) T-bone CT transverse oblique reformation clearly demonstrates an inplane view of the superior semicircular canal, showing the entire extent of superior semicircular canal dehiscence in a single image P.VI(4):53 TERMINOLOGY Abbreviations Semicircular canal dehiscence (SCCD) Definitions Extreme thinning or absence of bony roof over superior or posterior semicircular canal IMAGING General Features Best diagnostic clue T-bone CT shows dehiscence of bone covering superior (SSCC) or posterior (PSCC) semicircular canal Location May be bilateral Size 1500 Diagnostic Imaging Head and Neck 2-4 mm dehiscent segment CT Findings Bone CT Coronal T-bone CT ≥ mm dehiscence of roof of SSCC Extreme thinning of tegmen tympani may be associated Transverse oblique (Poschl) T-bone CT reformats Ideal for in-plane view of SSCC dehiscent roof Axial T-bone CT ≥ mm dehiscence of superficial bony wall of PSCC MR Findings T2WI Thin section high-resolution T2 MR Coronal: Absence of arcuate eminence bone covering SSCC Axial: Best shows segmental absence of superficial wall of PSCC T1WI C+ Look for acoustic schwannoma as alternative explanation for vertigo Imaging Recommendations Axial & coronal T-bone CT best test Nonenhanced, bone algorithm, high-resolution (1 mm) CT Oblique reconstructions in plane of SSCC or PSCC shows scope of dehiscence DIFFERENTIAL DIAGNOSIS Normal Thinning of SSCC or PSCC Wall Asymptomatic thinning bony cover of SSCC or PSCC occurs Usually seen on only coronal or axial CT image PATHOLOGY General Features Etiology Unknown; most likely a developmental anomaly Head injury or change in intracranial pressure (barotrauma) may fracture thin bone or destabilize dura over preexistent dehiscence Best hypothesis for clinical findings Bony opening overlying semicircular canal creates “3rd mobile window” into inner ear allowing canal to respond to sound & pressure changes in membranous labyrinth Motion at oval window (from loud noises) or ↑ intracranial pressure may then cause bowing of thin cover over SSC or PSC Results in “unphysiological motion” of endolymph in affected SCC Similar clinical findings described with cholesteatomas eroding horizontal SCC Gross Pathologic & Surgical Features Surgical view shows absent bony cover SSCC or PSCC CLINICAL ISSUES Presentation Most common signs/symptoms Sound ± pressure-induced vestibular symptoms ± eye movements Other symptoms & signs Chronic disequilibrium may be debilitating Oscillopsia (oscillating vision) Tullio phenomenon: Vertigo ± nystagmus related to sound Demographics Age Mean: 50 years, range: 20-70 years Epidemiology ˜ 2% of population have thinning or dehiscence of bone over SSCC on autopsy; 50% bilateral SSCC dehiscence > > PSCC dehiscence Natural History & Prognosis Slowly progressive symptoms Treatment Treatable form of vestibular disturbance Earplugs & avoiding provoking stimuli 1501 Diagnostic Imaging Head and Neck Surgical resurfacing of affected SCC beneficial DIAGNOSTIC CHECKLIST Consider Vestibular symptoms + positive CT = SCCD syndrome Image Interpretation Pearls Since usually unilateral, use opposite SCC as baseline normal to compare with suspicious side SELECTED REFERENCES Krombach GA et al: Semicircular canal dehiscence: comparison of T2-weighted turbo spin-echo MRI and CT Neuroradiology 46(4):326-31, 2004 Mong A et al: Sound- and pressure-induced vertigo associated with dehiscence of the roof of the superior semicircular canal AJNR Am J Neuroradiol 20(10):1973-5, 1999 Cochlear Implants > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Inner Ear > Miscellaneous > Cochlear Implants Cochlear Implants Troy Hutchins, MD Key Facts Terminology Cochlear implant (CI) Multi-component electronic device that provides auditory information by directly stimulating auditory fibers in cochlea Imaging Postoperative CI evaluation: T-bone CT Stimulation wire tip should be in basal turn or 2nd turn of cochlea No wire in cochlea (“empty cochlea”) signifies malpositioning Wire fracture or kinking may be demonstrated in malfunctioning CI Clinical Issues Torque experienced by CI in 1.5T MR is sufficient to cause implant movement CI patients should not undergo 1.5T MR Diagnostic Checklist Key absolute contraindications to CI placement Cochlear or labyrinthine aplasia Absent cochlear nerve Key relative contraindications to CI placement Labyrinthine ossificans Dysplastic cochlea (common cavity, cystic cochleovestibular anomaly) Large endolymphatic sac anomaly Key findings that may complicate surgery Hypoplastic mastoid process Aberrant facial nerve Otosclerosis Otomastoiditis Dehiscent jugular bulb Aberrant internal carotid artery Persistent stapedial artery 1502 Diagnostic Imaging Head and Neck (Left) Axial right T-bone CT shows normal appearance and location of cochlear implant The wire enters the round window and traverses the basal turn of the cochlea to reach the cochlear 2nd turn (Right) Coronal T-bone CT in the same patient demonstrates normal positioning of the cochlear implant wire in the basal turn of the cochlea (Left) Modified Stenver view of left temporal bone shows the normal configuration of the distal cochlear implant wire spiraling within the cochlea The receiver and magnet are seen in profile (Right) Coronal left T-bone CT shows normally positioned cochlear implant wire in the basal turn of the cochlea P.VI(4):55 TERMINOLOGY Abbreviations Cochlear implant (CI) Synonyms Cochlear electrode Definitions CI: Multi-component electronic device that provides auditory information by directly stimulating auditory fibers in cochlea Microphone External component that resides behind ear Receives sound from environment Transforms sound to electrical impulse Transmits impulse to speech processor 1503 Diagnostic Imaging Head and Neck Speech processor External component that may be attached to microphone or worn separately in clothing Custom programmed computer that emphasizes speech over other sounds Digitally encodes sounds from frequency range of human speech Encoding strategy depends on manufacturer Transmitter External component that resides behind ear, atop subcutaneous receiver Transcutaneously sends magnetic impulses from speech processor to receiver Held in place by magnet in subcutaneous receiver Receiver Thin, subcutaneous component that resides behind ear Surgically implanted Converts magnetic impulses from transmitter to electrical signal for stimulator wire Stimulator Wire placed inside cochlea directly stimulates spiral ganglion cells and cochlear axons Stimulator wire enters cochlea via round window Array of electrodes along wire appear as tiny bumps radiographically IMAGING General Features Best diagnostic clue Thin metallic wire (stimulator) with tiny beads (electrodes) extending into cochlea Stimulator wire is connected to subcutaneous receiver behind ear Location Stimulator wire should be in basal turn of cochlea, sometimes into 2nd turn Enters cochlea via round window Size Sub-millimeter thickness Morphology Curvilinear with small beads on intracochlear stimulator wire Radiographic Findings Modified Stenver view of T-bone shows CI best Head rotated 45° from direct AP, away from implanted ear Slight head flexion CT Findings Bone CT Pre-implant evaluation: Absolute & relative contraindications to implantation Key preoperative absolute contraindication: Cochlear aplasia alone or in labyrinthine aplasia Key preoperative relative contraindications: Labyrinthitis ossificans, other inner ear dysplasias Pre-implant CT: Findings that may complicate surgery Hypoplastic mastoid process Aberrant facial nerve course Otomastoiditis Fenestral ± cochlear otosclerosis Persistent stapedial artery Dehiscent jugular bulb Aberrant internal carotid artery Enlarged endolymphatic sac & duct Postoperative search for complications Key post-op complication: Misplaced wire (not in cochlea) Wire penetrates only part way into cochlea Broken wire Wire penetration out of inner ear MR Findings T2WI MR must include high-resolution fluid sequence Preoperative setting: Look for absolute & relative contraindications Key preoperative contraindication on MR: Absence of cochlear nerve Absence of fluid in cochlea (e.g., labyrinthitis ossificans) Ipsilateral brainstem infarct 1504 Diagnostic Imaging Head and Neck Superficial siderosis Postoperative setting: Traditional CI are not considered safe for 1.5T MR Magnetic torque may dislodge CI Embedded magnet causes marked field distortion Imaging Recommendations Preoperative high-resolution T-bone CT and high-resolution T2 MR are complimentary Preoperative evaluation Temporal bone CT Adequately evaluates round window patency Identifies bony phase of labyrinthitis ossificans in cochlea Shows inner anomalies & anatomic variants Temporal bone MR Identifies both fibrous & ossific obstructions within cochlea Can see absent or hypoplastic cochlear nerve Postoperative evaluation Modified Stenver view of temporal bone shows CI misplacement High-resolution T-bone CT now superior tool P.VI(4):56 DIFFERENTIAL DIAGNOSIS Major Lesions to Identify in Preoperative CI Candidate Absolute contraindication diagnoses Cochlear nerve & cochlear nerve canal aplasia-hypoplasia Atretic cochlea Labyrinthine aplasia Cochlear aplasia Relative contraindication diagnoses Dysplastic cochlea Common cavity malformation Cystic cochleovestibular malformation (IP-I) Large vestibular aqueduct (IP-II) Labyrinthine ossificans Cochlear Nerve & Cochlear Nerve Canal Aplasia-Hypoplasia Imaging: Absent cochlear nerve with small IAC (congenital type) Embryogenesis: Cochlear nerve fails to form Labyrinthine Aplasia Imaging: No cochlea or vestibule present Embryogenesis: Developmental arrest, 3rd gestational week Cochlear Aplasia Imaging: No cochlea present Embryogenesis: Developmental arrest, late 3rd gestational week Common Cavity Malformation Imaging: Coalesced cystic cochlea & vestibule form common cavity Embryogenesis: Developmental arrest in 4th gestational week Cystic Cochleovestibular Malformation (IP-I) Imaging: Cochlea & vestibule cystic with no internal architecture Embryogenesis: Developmental arrest, 5th gestational week Large Vestibular Aqueduct (IP-II) Imaging: Large endolymphatic duct & sac with mild cochlear dysplasia Embryogenesis: Developmental arrest in 7th week PATHOLOGY General Features Etiology Primary causes of hearing loss = congenital, infection Gross Pathologic & Surgical Features Placement of CI requires partial mastoidectomy Microscopic Features Beaded appearance of stimulator wire represents individual stimulating electrodes 1505 Diagnostic Imaging Head and Neck CLINICAL ISSUES Presentation Most common signs/symptoms Severe to profound bilateral sensorineural hearing loss (SNHL) Clinical profile CI candidates must be > years old with bilateral severe SNHL Must also show no benefit from conventional hearing aids Demographics Age Candidates must be > years old Epidemiology Estimated 17% (36,000,000) Americans report some degree of hearing loss in 2010 Natural History & Prognosis Postlingually deafened patients (those who have already learned to speak, usually > years old) have best CI outcome Postoperative complications (5%) Transient CN7 paresis, imbalance, perilymph fistula, hardware failure, & skin flap problems 90% of CI patients report basic sentence understanding after months Torque experienced by CI in 1.5T MR is sufficient to cause implant movement; traditional CI patients should not undergo 1.5T MR MR-compatible CI are now available External components should be removed in all cases Treatment CI is effective rehabilitation method for profoundly hearing-impaired patients who not benefit from hearing aids CI users should return to clinic at least once a year for speech processor adjustments Postoperative results depend on number of intracochlear electrodes Alternative hearing augmentation options Hearing aid Ossicular prosthesis Auditory brainstem implant DIAGNOSTIC CHECKLIST Consider Are there any contraindications to CI placement? Are there any findings that might complicate surgery? Which side would be easier for surgeon? Post-op patients: Is CI in appropriate location (basal turn of cochlea)? SELECTED REFERENCES Verbist BM et al: Multisection CT as a valuable tool in the postoperative assessment of cochlear implant patients AJNR Am J Neuroradiol 26(2):424-9, 2005 Witte RJ et al: Pediatric and adult cochlear implantation Radiographics 23(5):1185-200, 2003 P.VI(4):57 Image Gallery 1506 Diagnostic Imaging Head and Neck (Left) Axial left T-bone CT demonstrates a normal cochlear implant (CI) The wire enters the round window on its way to the basal turn of the cochlea , extending well into the cochlear 2nd turn There is no evidence of wire kinking or breaking (Right) Coronal T-bone CT of the same patient reveals CI wire appropriately positioned within the cochlea The normal beaded appearance from electrodes on the distal CI wire is well appreciated on this image (Left) Axial left T-bone CT of a malpositioned cochlear implant shows abnormal kinking of the CI wire at the round window niche Note severe obliterative labyrinthine ossificans with bone replacing the basal turn of the cochlea , likely responsible for difficulty placing CI in this case (Right) Axial bone CT of the same ear at a more inferior level shows the tip of CI wire in an abnormal extracochlear position embedded within the carotid canal posterolateral margin 1507 Diagnostic Imaging Head and Neck (Left) Axial left T-bone CT reveals portions of the cochlear implant wire passing through mastoidectomy cavity with no wire seen in the round window niche or cochlea This “empty cochlea” signifies abnormal extracochlear location of cochlear implant wire (Right) Axial T-bone CT in the same patient demonstrates cochlear implant wire traversing the middle ear with tip malpositioned in the bony eustachian tube “Empty cochlea” is again partially visualized Section - Petrous Apex Pseudolesions Petrous Apex Asymmetric Marrow > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Petrous Apex > Pseudolesions > Petrous Apex Asymmetric Marrow Petrous Apex Asymmetric Marrow H Ric Hamsberger, MD Key Facts Terminology Synonym:Petrous apex pseudolesion PA-AM: Asymmetric aeration of PA with nonpneumatized marrow space in opposite PA simulating mass lesion Imaging Bone CT findings Normal PA marrow space Normal air cells visible in contralateral PA No expansile changes present MR findings Nonpneumatized PA hyperintense T1 normal fatty marrow Mimics cholesterol granuloma Top Differential Diagnoses Petrous apex cholesterol granuloma Petrous apex trapped fluid Petrous apex congenital cholesteatoma Apical petrositis Pathology Congenital normal variant in PA pneumatization-marrow space spectrum Embryology-anatomy 33% have pneumatized petrous apices 5% are asymmetrically pneumatized Clinical Issues Asymptomatic by definition 1508 Diagnostic Imaging Head and Neck Patient undergoing brain MR for unrelated symptoms Incidental MR finding Requires no treatment or follow-up (Left) Axial T1WI MR demonstrates an irregularly shaped high signal collection in the left petrous apex The right petrous apex is low signal due to the presence of air cells (Right) Axial bone CT in the same patient reveals only minimal petrous apex pneumatization The remainder of the petrous apex is marrow space There is no evidence for any expansile changes in this area (Left) Axial T1WI MR shows a conspicuous bright “lesion” in the left petrous apex suspicious for “cholesterol granuloma.” A bone CT was ordered to further define the nature of this finding (Right) Axial bone CT in the same patient demonstrates asymmetric marrow in the left petrous apex Notice the opposite petrous apex is pneumatized Asymmetric fatty marrow spaces may appear quite conspicuous on T1WI MR P.VI(5):3 TERMINOLOGY Abbreviations Petrous apex asymmetric marrow (PA-AM) Synonyms Petrous apex pseudolesion Definitions PA-AM: Asymmetric aeration of PA with nonpneumatized marrow space in opposite PA simulating mass lesion IMAGING General Features 1509 Diagnostic Imaging Head and Neck Best diagnostic clue Asymmetric aerated PA across from opposite normal PA bone marrow in absence of expansile changes CT Findings CECT No abnormal enhancement present Bone CT Normal PA marrow space juxtaposed with contralateral normal PA air cells No expansile changes present MR Findings T1WI Nonpneumatized PA hyperintense T1 normal fatty marrow Mimics cholesterol granuloma If red marrow, may be of intermediate signal T2WI When fatty, PA-AM will follow subcutaneous fat with ↓ signal T1WI C+ Fat-saturated sequences confirm diagnoses of normal PA-AM Imaging Recommendations Best imaging tool Most commonly incidental finding on brain MR T-bone CT used to confirm marrow in PA Ensures no worrisome changes to trabeculae, lack of expansile or erosive bone changes Protocol advice “Lesion” is 1st suspected on brain MR exam without fat saturation DIFFERENTIAL DIAGNOSIS Petrous Apex Cholesterol Granuloma Bone CT: Smooth, expansile mass MR: High signal on T1 & T2 Petrous Apex Trapped Fluid Bone CT: Nonexpansile, opacified PA air cells MR: Low T1, high T2 signal in most cases Petrous Apex Congenital Cholesteatoma Bone CT: Smooth, expansile lesion MR: Low T1, high T2 signal DWI high signal Apical Petrositis Bone CT: Destruction of PA trabecula & cortex MR: Thick enhancing walls with focal fluid; dural enhancement Petrous Apex Mucocele Bone CT: Smooth, expansile lesion MR: Low T1, high T2 signal; DWI low signal PATHOLOGY General Features Etiology Congenital normal variant in PA pneumatization-marrow space spectrum Embryology-anatomy 33% have pneumatized petrous apices 5% are asymmetrically pneumatized PA pneumatization amount correlates with amount of mastoid aeration CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic by definition Clinical profile Patient undergoing brain MR for unrelated symptoms Incidental MR finding PA-AM described as “suspicious for cholesterol granuloma” in radiology report Patient is referred for surgical assessment T-bone CT reveals normal PA air cells visible across from opposite normal PA bone marrow 1510 Diagnostic Imaging Head and Neck Natural History & Prognosis PA-AM remains unchanged over time Multiple possible morbidities from treatment of this “leave me alone” lesion of PA Treatment Requires no treatment or follow-up DIAGNOSTIC CHECKLIST Consider PA-AM is common incidental finding on brain MR May be misdiagnosed as PA cholesterol granuloma or high T1 signal trapped PA fluid One of the “leave me alone” lesions of PA Trapped PA fluid also “leave me alone” lesion Misdiagnosis creates clinical confusion and potential for unnecessary treatment SELECTED REFERENCES Connor SE et al: Imaging of the petrous apex: a pictorial review Br J Radiol 81(965):427-35, 2008 Leonetti JP et al: Incidental petrous apex findings on magnetic resonance imaging Ear Nose Throat J 80(4):200-2, 205-6, 2001 Moore KR et al: ‘Leave me alone’ lesions of the petrous apex AJNR Am J Neuroradiol 19(4):733-8, 1998 Petrous Apex Cephalocele > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Petrous Apex > Pseudolesions > Petrous Apex Cephalocele Petrous Apex Cephalocele H Ric Hamsberger, MD Key Facts Terminology Synonyms: Petrous apex (PA) arachnoid cyst, apical meningocele Definition: Congenital or acquired herniation of posterolateral wall of Meckel cave (MC) into PA Imaging Bone CT findings Unilateral or bilateral expansile PA lesions Enlarges porus trigeminus PA notch MR findings CSF intensity ovoid PA lesion on all sequences Directly communicates with MC Appears to “spill out” of patulous MC Top Differential Diagnoses Petrous apex cholesterol granuloma Petrous apex congenital cholesteatoma Petrous apex mucocele Clinical Issues Common presentation: Incidental asymptomatic MR brain finding Rare presentation: Symptomatic lesion (CSF otorrhea, trigeminal neuralgia, meningitis) Rare symptoms occur when lesion breaks into temporal bone air cells No treatment in > 95% of cases Surgical treatment if lesion communicates with PA air cells Diagnostic Checklist PAC = “leave me alone” lesion of PA PAC requires no further work-up or surgical intervention in > 95% cases 1511 Diagnostic Imaging Head and Neck (Left) Axial graphic illustrates the herniation of a cephalocele from Meckel cave into the petrous apex A portion of the trigeminal ganglion is depicted protruding into the cephalocele (Right) Axial T2WI MR shows a cephalocele protruding into the left petrous apex just anteromedial to the internal auditory canal Notice the connection of the lesion to Meckel cave (Left) Axial bone CT demonstrates right and left petrous apex ovoid, scalloping lesions projecting into the petrous apex air cells from the posterolateral Meckel cave area Bilateral petrous apex cephaloceles were suspected, and MR was ordered for confirmation (Right) Axial enhanced T1WI MR in the same patient reveals bilateral, left larger than right , fluid intensity PA cephaloceles that arise from the inferior aspect of Meckel cave P.VI(5):5 TERMINOLOGY Abbreviations Petrous apex cephalocele (PAC) Synonyms Petrous apex arachnoid cyst, apical meningocele Definitions Congenital or acquired herniation of posterolateral wall of Meckel cave (MC) into PA IMAGING General Features Best diagnostic clue CSF density/intensity lesion of PA that directly communicates with MC 1512 Diagnostic Imaging Head and Neck Appears to “spill out” of patulous MC Location Anteromedial PA directly adjacent to MC CT Findings Bone CT Unilateral or bilateral smooth expansile PA lesion(s) Enlarged PA porus trigeminus notch CT cisternography Contrast fills MC & PAC When CSF otorrhea present, may define PAC connection to PA air cells MR Findings T1WI Low T1 signal, isointense to CSF T2WI High T2 signal, isointense to CSF Coronal best shows connection to MC FLAIR Fluid in PAC attenuates with CSF T1WI C+ No enhancement vs mild rim enhancement If gasserian ganglion within cephalocele, will appear as “enhancing component” within ovoid nonenhancing lesion Periganglion venous plexus enhances Imaging Recommendations Best imaging tool Focused multiplanar T2 MR makes diagnosis T-bone CT confirms impression CT cisternography if CSF otorrhea present DIFFERENTIAL DIAGNOSIS Petrous Apex Cholesterol Granuloma CT: Expansile PA lesion MR: T1 & T2 signal high Does not suppress on FLAIR Petrous Apex Congenital Cholesteatoma CT: Smooth, expansile PA mass MR: T1 low, T2 high signal; DWI restricts Petrous Apex Mucocele CT: Smooth, expansile PA lesion MR: T1 low, T2 high signal; DWI negative PATHOLOGY General Features Etiology Congenital hypothesis Developmental anomaly results in deficient dural & osseous covering of PA Defect allows MC “herniation” into PA Acquired hypothesis Chronic CSF pulsations against thin anterior wall of pneumatized PA results in dehiscence Arachnoid granulation adjacent to anterior PA may accelerate dehiscence Eventual prolapse of meninges into PA defect Microscopic Features or all meningeal layers may be present CLINICAL ISSUES Presentation Most common signs/symptoms Incidental asymptomatic MR brain finding Rarely complicated by CSF otorrhea, trigeminal neuralgia, meningitis Occur when lesion breaks into T-bone air cells Clinical profile Common: Incidental MR finding in patient imaged for nonspecific brain indication 1513 Diagnostic Imaging Head and Neck Rare: Pneumococcal meningitis, CSF otorrhea, trigeminal neuralgia Demographics Epidemiology Uncommon incidental lesion on brain MR Treatment No treatment in most cases Surgical treatment if air cell communication exists Recurrent meningitis, CSF leak require surgery Middle cranial fossa extradural approach Repair dural defect; obliterate PA defect DIAGNOSTIC CHECKLIST Consider PAC = “leave me alone” lesion of PA PAC requires no further work-up or surgical intervention in > 95% cases SELECTED REFERENCES Stark TA et al: Dilation of the subarachnoid spaces surrounding the cranial nerves with petrous apex cephaloceles in Usher syndrome AJNR Am J Neuroradiol 30(2):434-6, 2009 Alorainy IA: Petrous apex cephalocele and empty sella: is there any relation? Eur J Radiol 62(3):378-84, 2007 Moore KR et al: Petrous apex cephaloceles AJNR Am J Neuroradiol 22(10):1867-71, 2001 Congenital Lesions Congenital Petrous Apex Cholesteatoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Petrous Apex > Congenital Lesions > Congenital Petrous Apex Cholesteatoma Congenital Petrous Apex Cholesteatoma H Ric Hamsberger, MD Key Facts Terminology PA-Chol: Petrous apex focus of cholesteatoma due to epithelial rest of embryonal origin Imaging May simultaneously involve adjacent areas Horizontal petrous ICA canal Inner ear structures (otic capsule) Internal auditory canal Meckel cave Medial mastoid air cells Facial nerve canal (labyrinthine & anterior tympanic segments) Bone CT: Expansile mass with smooth-lobular bone remodeling Shows smooth, expansile, lobulated lesion of PA MR: Expansile PA lesion low T1, high T2 signal but without enhancement Restricted diffusion (high signal on DWI) is characteristic Top Differential Diagnoses Petrous apex trapped fluid Apical petrositis Petrous apex cholesterol granuloma Petrous apex mucocele Petrous ICA aneurysm Pathology Aberrant PA epithelial rest of exfoliated keratin within stratified squamous epithelium Growth from progressive desquamation of epithelium Clinical Issues 30- to 40-year-old adult with unilateral sensorineural hearing loss 1514 Diagnostic Imaging Head and Neck (Left) Axial graphic depicts typical PA congenital cholesteatoma Notice the benign expansile nature of PA bone as it responds to growing cholesteatoma The horizontal petrous ICA posterior wall is thinned by cholesteatoma growth (Right) Axial T1WI C+ MR reveals a large PA cholesteatoma with minimal rim enhancement The lesion is impinging on the internal auditory canal and sphenoid sinus (Left) Axial bone CT in the right ear show an expansile, smoothly marginated cholesteatoma remodeling the PA and eroding the bony labyrinth around the cochlea The cholesteatoma can also be seen emerging from the round window niche (Right) Axial T2 MR in the same patient shows the hyperintense congenital cholesteatoma eroding the PA and the bone of the cochlea PA congenital cholesteatoma often involve more than just the PA In this case the inner ear is affected P.VI(5):7 TERMINOLOGY Abbreviations Petrous apex cholesteatoma (PA-Chol) Synonyms Congenital cholesteatoma, epidermoid cyst of petrous apex Definitions PA-Chol: Petrous apex focus of cholesteatoma due to epithelial rest of embryonal origin IMAGING General Features Best diagnostic clue Bone CT: Expansile mass with smooth-lobular bone remodeling 1515 Diagnostic Imaging Head and Neck MR: Expansile PA lesion with low T1, high T2 signal but without enhancement Location Petrous apex May involve more than petrous apex Medial inner ear & IAC Medial mastoid Size May become very large before discovered 2-10 centimeters in maximum diameter Morphology Ovoid to round; lobulated When involves medial inner ear & mastoid with PA, may have dumbbell morphology CT Findings CECT PA-Chol will not enhance Bone CT Shows smooth, expansile, lobulated lesion of PA May simultaneously involve adjacent areas Horizontal petrous ICA canal Inner ear structures (otic capsule) Internal auditory canal Meckel cave Medial mastoid air cells Facial nerve canal (labyrinthine & anterior tympanic segments) MR Findings T1WI Low T1 signal May be homogeneous or heterogeneous T2WI High T2 signal FLAIR Does not attenuate on FLAIR Partial attenuation (mixed intermediate-low signal) may be seen DWI Restricted diffusion (high signal on DWI) is characteristic Same as congenital cholesteatoma in CPA (epidermoid cyst) T1WI C+ Will not enhance Mild rim enhancement common MRA Large lesions may cause mass effect on horizontal petrous internal carotid artery MRV Large lesions may compress sigmoid sinus ± jugular foramen Angiographic Findings Avascular petrous apex mass lesion Imaging Recommendations Best imaging tool Temporal bone CT is best initial exam No contrast necessary MR in axial & coronal planes used to confirm diagnosis & obtain soft tissue roadmap for surgery Especially useful in large lesions T1 C+ MR confirms lack of enhancement Use DWI sequence to confirm diagnosis DIFFERENTIAL DIAGNOSIS Petrous Apex Trapped Fluid Clinical: Asymptomatic incidental finding on T2 MR Bone CT: Nonexpansile, opacified PA air cells MR: Low or intermediate T1 + high T2 signal in most cases Can be high signal on T1 1516 Diagnostic Imaging Head and Neck Apical Petrositis Clinical: Septic patient unless already partially treated with antibiotics Bone CT: Destructive PA lesion with trabecular & cortical loss MR: Thick enhancing walls with focal fluid Dural thickening & enhancement Petrous Apex Cholesterol Granuloma Clinical: Previous history of chronic otomastoiditis common Bone CT: Smooth, lobular expansile mass MR: High signal on T1 & T2 Petrous Apex Mucocele Bone CT: Smooth, expansile lesion MR: Low T1, high T2 signal May exactly mimic cholesteatoma of PA Except no diffusion restriction seen on DWI MR sequence Petrous ICA Aneurysm Clinical: Skull base trauma history may be present Bone CT: Fusiform or focal expansion centered in horizontal petrous ICA canal MR: Complex signal ovoid to fusiform mass inseparable from horizontal petrous ICA PATHOLOGY General Features Etiology P.VI(5):8 Aberrant epithelial rest in petrous apex of exfoliated keratin within stratified squamous epithelium Growth from progressive desquamation of epithelium PA cholesteatoma congenital, primary to PA or along labyrinthine segment of CN7 PA cholesteatoma may be part of large, multilobular lesion involving inner ear, IAC, medial mastoid Embryology-anatomy Rests of epithelial tissue can occur in multiple locations in & around temporal bone Middle ear > CPA > mastoid > petrous apex > facial nerve canal Gross Pathologic & Surgical Features Pearly white tissue within eggshell bone Microscopic Features Sheets of stratified, keratinizing, squamous epithelium No evidence of abnormal mitosis present Granulation tissue and fibrosis often surround them Rich in cholesterol crystals CLINICAL ISSUES Presentation Most common signs/symptoms Sensorineural hearing loss Other signs/symptoms Peripheral facial nerve paralysis Abducens nerve paralysis Headache Clinical profile 30- to 40-year-old adult with unilateral sensorineural hearing loss Demographics Age 20-50 years old Epidemiology Very rare PA lesion (< 1% of PA lesions) Trapped fluid > > apical petrositis, cholesterol granuloma, metastases > PA congenital cholesteatoma Natural History & Prognosis Very slow-growing lesion Complete surgical removal arrests symptom progression 1517 Diagnostic Imaging Head and Neck Treatment Surgical approaches Removal via transpetrous approach Middle fossa approach also used DIAGNOSTIC CHECKLIST Consider Once discovery of petrous apex expansile lesion occurs, sort into benign expansile and invasive expansile groups Invasive expansile PA group includes apical petrositis, metastases & plasmacytoma, Langerhans cell histiocytosis Benign expansile PA group includes cholesteatoma, cholesterol granuloma, mucocele, petrous ICA aneurysm, PA cephalocele Image Interpretation Pearls Sorting through radiologic characteristics of bone CT based benign expansile PA group with MR key Congenital cholesteatoma of petrous apex T1 low, T2 high T1 C+ MR shows no enhancement FLAIR shows partial or absent attenuation DWI shows restricted diffusion Cholesterol granuloma of petrous apex T1 high, T2 high Mucocele of petrous apex T1 low, T2 high DWI shows no restricted diffusion Petrous ICA aneurysm MR sequences show complex signal mass centered on horizontal petrous ICA Complex signal due to various ages of blood in luminal clot & turbulent flow PA cephalocele Look for connection to patulous Meckel cave Reporting Tips Be precise about surrounding structure involvement Horizontal petrous ICA, facial nerve canal require specific comment Inner ear erosion present or absent? Jugular foramen & sigmoid sinus involvement? SELECTED REFERENCES Connor SE et al: Imaging of the petrous apex: a pictorial review Br J Radiol 81(965):427-35, 2008 Kojima H et al: Congenital cholesteatoma clinical features and surgical results Am J Otolaryngol 27(5):299-305, 2006 Mattox DE: Endoscopy-assisted surgery of the petrous apex Otolaryngol Head Neck Surg 130(2):229-41, 2004 Profant M et al: Petrous apex cholesteatoma Acta Otolaryngol 120(2):164-7, 2000 Chang P et al: Imaging destructive lesions of the petrous apex Laryngoscope 108(4 Pt 1):599-604, 1998 Kikuchi S et al: Congenital cholesteatoma of the petrous pyramid ORL J Otorhinolaryngol Relat Spec 55(4):236-9, 1993 Mafee MF: MRI and CT in the evaluation of acquired and congenital cholesteatomas of the temporal bone J Otolaryngol 22(4):239-48, 1993 Atlas MD et al: Petrous apex cholesteatoma: diagnostic and treatment dilemmas Laryngoscope 102(12 Pt 1):13638, 1992 Jackler RK et al: Radiographic differential diagnosis of petrous apex lesions Am J Otol 13(6):561-74, 1992 10 Ishii K et al: Middle ear cholesteatoma extending into the petrous apex: evaluation by CT and MR imaging AJNR Am J Neuroradiol 12(4):719-24, 1991 11 Rosenberg RA et al: Cholesteatoma vs cholesterol granuloma of the petrous apex Otolaryngol Head Neck Surg 94(3):322-7, 1986 12 Horn KL et al: Congenital cholesteatoma of the petrous pyramid Arch Otolaryngol 111(9):621-2, 1985 13 Latack JT et al: Epidermoidomas of the cerebellopontine angle and temporal bone: CT and MR aspects Radiology 157(2):361-6, 1985 P.VI(5):9 Image Gallery 1518 Diagnostic Imaging Head and Neck (Left) Giant petrous apex-medial temporal bone congenital cholesteatoma is seen on bone CT Note the PA , medial wall temporal bone , and nasopharyngeal components (Right) Axial T2-CISS MR in the same patient demonstrates the intermediate-high signal large congenital cholesteatoma involving the PA , medial inner ear and mastoid The horizontal petrous ICA is bowed anteriorly by the lesion (Left) Axial enhanced T1WI MR in the same patient reveals the expected nonenhancing cholesteatoma in the PA medial inner ear , and medial mastoid Minimal rim enhancement is a common finding in congenital cholesteatoma (Right) Axial DWI MR in the same patient reveals the diagnostic restricted diffusion in the PA , medial inner ear , and medial mastoid Air-bone-soft tissue interfaces in the temporal bone degrade DWI images to the point that only large cholesteatoma can be seen 1519 , , Diagnostic Imaging Head and Neck (Left) Axial bone CT in a patient with facial nerve paresis shows an expansile lesion of the geniculate fossa and labyrinthine segment of the CN7 canal The congenital cholesteatoma remodels bone into the area of the medial petrous apex (Right) Axial T2WI MR in the same patient reveals the congenital cholesteatoma to be high signal in the geniculate fossa and labyrinthine CN7 canal The PA & superior semicircular canal are eroded by the lesion Infectious and Inflammatory Lesions Petrous Apex Trapped Fluid > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Petrous Apex > Infectious and Inflammatory Lesions > Petrous Apex Trapped Fluid Petrous Apex Trapped Fluid H Ric Hamsberger, MD Key Facts Terminology Definition: Sterile residual fluid collection in PA air cells left behind after remote otomastoiditis Imaging Variable T1, high T2 signal “lesion” of PA on MR with bone CT showing opacified PA air cells without trabecular loss & without expansion Temporal bone CT findings Opacified PA air cells; middle ear-mastoid clear No expansile component to lesion No PA cortical or trabecular erosions MR findings T1 intermediate to high signal most common High T2 signal in normal-appearing PA Top Differential Diagnoses PA cholesterol granuloma PA congenital cholesteatoma Apical petrositis Pathology Pathophysiology Remote otomastoiditis involves PA air cells Sterile PA air cell fluid persists after treatment Clinical Issues Principal presenting symptom: None! Patient is undergoing brain MR for unrelated symptoms Incidental MR finding of PA lesion described as “suspicious for cholesterol granuloma or apical petrositis” in radiology report Patient is referred for clinical assessment & possible surgical assessment 1520 Diagnostic Imaging Head and Neck Bone CT shows typical trapped fluid finding Treatment: None! (Left) Axial graphic of the left temporal bone demonstrates fluid-filled petrous apex air cells Notice that trapped fluid in the petrous apex has no associated expansion or trabecular breakdown (Right) Axial bone CT demonstrates a classic example of petrous apex trapped fluid as a group of nonexpansile opacified petrous apex air cells with preservation of the trabecula and cortical margins (Left) Axial T2WI MR shows a conspicuous area of high signal in the left petrous apex on brain MR performed for loss of consciousness The radiologist queried the diagnosis of cholesterol granuloma in the radiologic report and suggested temporal bone CT for further evaluation (Right) Axial bone CT in the same patient shows opacified air cells in the left PA without evidence for expansion or trabecular loss The diagnosis of trapped fluid was made with no follow-up recommended P.VI(5):11 TERMINOLOGY Abbreviations Trapped fluid, petrous apex (TF-PA) Synonyms Petrous apex effusion Definitions TF-PA: Sterile residual fluid collection in PA air cells left behind after remote otomastoiditis IMAGING General Features 1521 Diagnostic Imaging Head and Neck Best diagnostic clue Variable T1, high T2 signal “lesion” of PA on MR with bone CT showing opacified PA air cells without trabecular loss & without expansion CT Findings CECT No enhancement of PA or adjacent meninges Bone CT Unilateral opacification of PA air cells No PA cortical or trabecular erosions No expansile component to lesion Sclerotic air cell margins from remote inflammation (˜ 50%) Absence of middle ear-mastoid inflammation MR Findings T1WI Variable PA air cell signal (protein content of fluid) Intermediate to high signal most common Heterogeneous T1 signal possible Protein content of adjacent air cells varies T2WI High T2 signal normal-appearing PA T1WI C+ No enhancement of PA or adjacent meninges Imaging Recommendations Best imaging tool Bone CT after TF-PA is discovered on brain MR Protocol advice year follow-up bone CT in TF-PA with high T1 MR signal Done to exclude rare possibility of transformation into cholesterol granuloma Documentation of TF-PA transforming into cholesterol granuloma has not occurred DIFFERENTIAL DIAGNOSIS PA Cholesterol Granuloma Bone CT: Expansile lesion of PA air cells Loss of PA bony trabeculae High T1 and high T2 MR signal PA Congenital Cholesteatoma Bone CT: Smooth, expansile lesion of PA air cells MR: T1 C+ shows low signal lesion with rim enhancement No meningeal enhancement present Apical Petrositis Bone CT: Trabecular and cortical erosion MR: Low T1 signal, high T2 signal T1 C+ shows thickened, enhancing meninges with spread to adjacent structures Clinical setting of otomastoiditis or post-mastoidectomy PATHOLOGY General Features Etiology Remote otomastoiditis involves PA air cells Sterile PA air cell fluid persists after treatment Embryology-anatomy PA pneumatization required for TF-PA to occur 33% of people have pneumatized petrous apices Microscopic Features Clear to xanthochromic fluid discovered at surgery CLINICAL ISSUES Presentation Most common signs/symptoms Principal presenting symptom: None! Demographics Epidemiology 1522 Diagnostic Imaging Head and Neck Residual fluid in PA air cells is present in ˜ 1% of all head MR TF-PA is most common lesion found in PA TF-PA: Cholesterol granuloma of PA ratio is ˜ 500:1 Natural History & Prognosis TF-PA remains unchanged throughout patient's life Theoretical possibility that one of rare high T1 signal lesions will transform into cholesterol granuloma Treatment No therapy or follow-up is warranted for classic TF-PA DIAGNOSTIC CHECKLIST Image Interpretation Pearls Nonexpansile & nondestructive PA lesion on bone CT with uniform intermediate to high T1 & high T2 signal on MR requires no further work-up SELECTED REFERENCES Lemmerling MM et al: Imaging of inflammatory and infectious diseases in the temporal bone Neuroimaging Clin N Am 19(3):321-37, 2009 Arriaga MA: Petrous apex effusion: a clinical disorder Laryngoscope 116(8):1349-56, 2006 Leonetti JP et al: Incidental petrous apex findings on magnetic resonance imaging Ear Nose Throat J 80(4):200-2, 205-6, 2001 Palacios E et al: ‘Don't touch me’ lesions of the petrous apex Ear Nose Throat J 80(3):140, 2001 Moore KR et al: ‘Leave me alone’ lesions of the petrous apex AJNR Am J Neuroradiol 19(4):733-8, 1998 Arriaga MA et al: Differential diagnosis of primary petrous apex lesions Am J Otol 12(6):470-4, 1991 Petrous Apex Mucocele > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Petrous Apex > Infectious and Inflammatory Lesions > Petrous Apex Mucocele Petrous Apex Mucocele H Ric Hamsberger, MD Key Facts Terminology Mucus-containing, expanded petrous apex (PA) air cells(s) lined by secretory epithelium resulting from chronic ostial obstruction Imaging CT: Fluid-filled, expanded PA air cell(s) MR: Nonenhancing, T1 low, T2 high signal; DWI with no restricted diffusion Top Differential Diagnoses Petrous apex cholesterol granuloma Petrous apex trapped fluid Petrous apex congenital cholesteatoma T-bone ICA aneurysm Pathology Results from obstruction to PA air cell drainage Obstruction from middle ear-mastoid infection, trauma, previous surgery Secretion of mucus into obstructed air cells Air cell expansion from pressure remodeling of wall Clinical Issues Treatment issues Controversial 1st follow to see if change occurs Surgical obliteration if enlarges Diagnostic Checklist When bone CT shows expansile PA lesion If T1 signal is high, consider cholesterol granuloma If DWI shows restricted diffusion, consider congenital cholesteatoma If T1 is low, T2 is high, & DWI shows no restricted diffusion, consider mucocele 1523 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows an expansile right petrous apex lesion with loss of the normal air cell trabeculations The differential diagnosis of this lesion is congenital cholesteatoma, cholesterol granuloma, and mucocele (Right) Axial T1WI in the same patient reveals the lesion is just slightly higher signal than CSF The low signal of the internal auditory canal is seen just posterolateral to the lesion This T1 signal excludes cholesterol granuloma from the differential diagnosis (Left) Axial T2WI MR in the same patient demonstrates the PA lesion to be uniformly hyperintense DWI showed no restricted diffusion An expansile PA lesion with low T1, high T2 and no restricted diffusion is highly suggestive of the diagnosis of mucocele (Right) Axial T2WI MR shows an expansile, high signal lesion in the left petrous apex T1 signal was low (not a cholesterol granuloma) and there was no restricted diffusion (not a congenital cholesteatoma) on DWI MR images (not shown) P.VI(5):13 TERMINOLOGY Definitions Mucus-containing, expanded petrous apex (PA) air cells(s) lined by secretory epithelium resulting from chronic ostial obstruction From Latin “muco” = mucous + Greek “kele” = tumor or “mucous tumor” IMAGING General Features Best diagnostic clue CT: Fluid-filled, expanded PA air cell(s) MR: T1 low, T2 high signal, DWI no restricted diffusion, nonenhancing 1524 Diagnostic Imaging Head and Neck Imaging Recommendations Best imaging tool Temporal bone CT Enhanced MR if atypical CT features MR will differentiate PA mucocele from cholesterol granuloma & congenital cholesteatoma CT Findings Bone CT Expanded, opacified PA air cell(s) PA cell walls are remodeled May be thinned, focally absent, or normal thickness MR Findings T1WI Usually low signal Variable with ↑ signal with ↑ protein T2WI Usually high signal If inspissated mucus exists, ↓ signal area DWI No high signal restricted diffusion T1WI C+ FS Minimal to no rim enhancement DIFFERENTIAL DIAGNOSIS Petrous Apex Cholesterol Granuloma Bone CT: Expansile PA air cells MR: T1 high, T2 high signal Petrous Apex Trapped Fluid Bone CT: Nonexpansile air cells trabeculated MR: T1 variable, T2 high signal Petrous Apex Congenital Cholesteatoma Bone CT: Expansile PA air cells MR: T1 low, T2 high signal: DWI restricted T-Bone ICA Aneurysm Bone CT: Expansile area of petrous ICA canal MR: Complex signal from clot, calcium, flow PATHOLOGY General Features Etiology Results from obstruction to PA air cell drainage Obstruction from middle ear-mastoid infection, trauma, previous surgery Secretion of mucus into obstructed air cells PA air cell expansion from pressure remodeling of wall Microscopic Features Flattened, pseudostratified, ciliated columnar epithelium = mucus-secreting respiratory epithelium Reactive bone formation or bone remodeling of air cell wall may be present CLINICAL ISSUES Presentation Most common signs/symptoms Headache Incidental finding on CT or MR Demographics Age Most common in adults Epidemiology Extremely rare lesion Natural History & Prognosis Gradual enlargement over time Treatment Controversial 1st follow to see if change occurs 1525 Diagnostic Imaging Head and Neck Surgical obliteration if enlarges DIAGNOSTIC CHECKLIST Consider When bone CT shows expansile PA lesion If T1 signal is high, consider cholesterol granuloma If DWI shows restricted diffusion, consider congenital cholesteatoma If T1 is low, T2 is high, DWI shows no restricted diffusion, consider mucocele SELECTED REFERENCES Le BT et al: Petrous apex mucocele Otol Neurotol 29(1):102-3, 2008 Muckle RP et al: Petrous apex lesions Am J Otol 19(2):219-25, 1998 Memis A et al: Petrous apex mucocele: high resolution CT Neuroradiology 36(8):632-3, 1994 Larson TL et al: Primary mucocele of the petrous apex: MR appearance AJNR Am J Neuroradiol 13(1):203-4, 1992 Petrous Apex Cholesterol Granuloma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Petrous Apex > Infectious and Inflammatory Lesions > Petrous Apex Cholesterol Granuloma Petrous Apex Cholesterol Granuloma H Ric Hamsberger, MD Key Facts Terminology PA-CG: Expansile PA lesion resulting from foreign body giant cell reaction to deposition of cholesterol crystals in apical air cells, with fibrosis & vascular proliferation Imaging Temporal bone CT findings Sharply marginated, expansile PA lesion Trabecular breakdown with cortical thinning of PA expected Larger lesions will have areas of focal bony wall dehiscence Temporal bone MR findings High T1 internal signal High T2 internal signal Peripheral low signal hemosiderin ring (T2) Top Differential Diagnoses Petrous apex asymmetric marrow Petrous apex trapped fluid Petrous apex congenital cholesteatoma Petrous apex ICA aneurysm Petrous apex mucocele Apical petrositis Pathology Obstruction-vacuum pathogenesis (classic hypothesis) Exposed bone marrow pathogenesis (recent alternative hypothesis) Pneumatized PA air cells required Clinical Issues May be incidental, asymptomatic lesion Most common symptoms: SNHL, tinnitus 1526 Diagnostic Imaging Head and Neck (Left) Axial graphic shows a cholesterol granuloma of the petrous apex The lesion is expansile with air cell trabecular loss and “eggshell” medial cortex The lesion compresses the IAC and thins the posterior wall of the horizontal petrous ICA (Right) Axial bone CT reveals an expansile cholesterol granuloma in the left petrous apex with marginal bone dehiscence present Right PA is well pneumatized PA-CG most commonly occurs in a pneumatized petrous apex (Left) Axial T1WI unenhanced MR in the same patient shows characteristic high signal of PA cholesterol granuloma If no fat saturation is applied to the enhanced sequences through this lesion, it will appear to enhance when in fact it does not (Right) Axial T2WI MR in the same patient demonstrates the lesion has inhomogeneous high signal Cholesterol granuloma contains “old blood.” T1 signal is therefore high (methemoglobin) & T2 signal inhomogeneous (methemoglobin & hemosiderin) P.VI(5):15 TERMINOLOGY Abbreviations Petrous apex cholesterol granuloma (PA-CG) Synonyms Cholesterol cyst, “chocolate” cyst Definitions PA-CG: Expansile PA lesion resulting from foreign body giant cell reaction to deposition of cholesterol crystals in apical air cells, with fibrosis & vascular proliferation IMAGING General Features 1527 Diagnostic Imaging Head and Neck Best diagnostic clue High T1 & T2 signal in expansile PA mass Location Petrous apex air cells When large, extends into surrounding structures Size Ranges from small lesions confined to PA to large lobulated masses Morphology Smooth, sharply marginated, lobulated when large CT Findings Bone CT Sharply marginated, expansile PA lesion Trabecular breakdown with cortical thinning of PA expected Larger lesions will have areas of focal bony wall dehiscence When large, erodes regionally Anteriorly to involve horizontal petrous ICA canal Medially into clivus, sphenoid sinus Lateral to inner & middle ear, facial nerve canal Posterior to IAC & CPA MR Findings T1WI High T1 internal signal Secondary to presence of hemorrhage, blood break-down products, & cholesterol crystals Primary reason most likely presence of paramagnetic intracellular methemoglobin T2WI High internal T2 signal Peripheral low signal hemosiderin ring FLAIR High T2 signal does not attenuate (remains high) T1WI C+ No internal enhancement If no T1 pre-contrast imaging, may be mistaken for “enhancing” lesion MRA Useful in surgical planning, assess for involvement of petrous ICA Beware: Lesions with high T1 signal will appear bright on time of flight MRA; mimics aneurysm Imaging Recommendations Best imaging tool Combination bone CT & MR T-bone CT evaluates bony erosion & invasion of contiguous structures MR characteristic high T1 signal confirms diagnosis Protocol advice MR imaging suggestions Remember to include pre-contrast T1 sequences Contrast is not helpful in delineating diagnosis of PA-CG MRA to evaluate for involvement of petrous ICA in large lesions Postoperative imaging for recurrence MR more sensitive than CT for evaluation of recurrence ↑ T1 signal in postoperative PA = recurrence Beware surgical fat packing DIFFERENTIAL DIAGNOSIS Petrous Apex Asymmetric Marrow CT: Nonexpansile fat density T1 MR: High signal; T2 MR: Intermediate to high signal Suppresses on fat-saturated MR Petrous Apex Trapped Fluid CT: Opacified air cells; nonexpansile; cortex & trabeculae intact T1 MR: Low to high signal; T2 MR: High signal T1 C+ MR: No contrast enhancement of lesion or meninges Petrous Apex Congenital Cholesteatoma 1528 Diagnostic Imaging Head and Neck CT: Smooth, expansile margins T1 MR: Low to intermediate signal; T2 MR: Intermediate to high signal DWI: Restricted diffusion (high signal) Petrous Apex ICA Aneurysm CT: Smooth expansion of petrous ICA canal MR: Heterogeneous T1 & T2 with internal flow void T1 C+ MR: Heterogeneous internal enhancement Petrous Apex Mucocele CT: Single, expansile air cell area in PA MR: Low T1, high T2, nonrestricted DWI Apical Petrositis CT: Permeative, destructive changes of cortex & trabeculae T1 MR: Low signal; T2 MR: High signal T1 C+ MR: Thick, enhancing rim; meninges thick & enhancing PATHOLOGY General Features Etiology Obstruction-vacuum pathogenesis (classic hypothesis) Otitis media creates mucosal obstruction of PA air cells causing development of vacuum Vacuum phenomena leads to rupture of blood vessels & hemorrhage in PA air cells P.VI(5):16 Anaerobic degradation of red blood cells forms cholesterol crystals, which incite foreign body giant cell infiltration Granulation tissue forms secondary to repeated hemorrhage, leading to expansile PA lesion Exposed bone marrow pathogenesis (recent alternative hypothesis) Begins with mucosal penetration into PA in young adulthood Marrow exposed, which leads to sustained/repeated microhemorrhage Embryology-anatomy Pneumatized PA air cells required PA pneumatization occurs normally in 33% of people Gross Pathologic & Surgical Features Cystic mass without epithelial lining Fibrous capsule filled with brownish liquid containing old blood & cholesterol crystals = “chocolate cyst” Fluid described as “crankcase oil” Microscopic Features RBC in various stages of degradation Multinucleated giant cells surrounding cholesterol crystals embedded in fibrous connective tissue Hemosiderin-laden macrophages Chronic inflammatory cells & blood vessels CLINICAL ISSUES Presentation Most common signs/symptoms May be incidental, asymptomatic lesion When IAC involved: Sensorineural hearing loss (SNHL), dizziness, tinnitus Other signs/symptoms Headache, facial pain (dural stretching) Abducens nerve palsy possible if projects anteromedially Clinical profile Otoscopy normal unless middle ear (ME) involved Blue-black retrotympanic mass if in ME Audiometric exam: SNHL or mixed pattern Demographics Age Young to middle-aged adults Epidemiology Most common surgical lesion in PA ME-CG > > PA-CG 1529 Diagnostic Imaging Head and Neck Natural History & Prognosis Growth rate highly variable Depends on frequency & severity of microhemorrhages Most take decades to grow Symptoms show up years after initial bout of chronic otitis media If adequately drained, excellent prognosis Treatment Asymptomatic patients can be safely followed with imaging Traditional surgical treatment Drainage & stent placement to re-establish PA aeration via transtemporal approach Reported recurrence rate as high as 60% Extended middle cranial fossa approach with extradural removal of PA-CG & obliteration of its cavity Significant decrease in recurrence rates Selective trans-sphenoidal endoscopic drainage DIAGNOSTIC CHECKLIST Consider Consider PA-CG in any expansile PA lesion with high T1 & T2 signal CT, MR, & MRA in preoperative planning, particularly in large lesions MR best for evaluating postoperative recurrence Image Interpretation Pearls Characteristic appearance of expansile high T1 & T2 lesion differentiates from other PA lesions CT most useful to evaluate bony destruction & involvement of adjacent otic capsule & carotid canal Make sure to evaluate for internal flow to avoid misdiagnosing petrous ICA aneurysm Reporting Tips Specifically comment on integrity of adjacent critical structures Facial nerve canal Petrous ICA canal Internal auditory canal Inner ear otic capsule SELECTED REFERENCES Sanna M et al: Otoneurological management of petrous apex cholesterol granuloma Am J Otolaryngol 30(6):40714, 2009 Connor SE et al: Imaging of the petrous apex: a pictorial review Br J Radiol 81(965):427-35, 2008 Oyama K et al: Petrous apex cholesterol granuloma treated via the endoscopic transsphenoidal approach Acta Neurochir (Wien) 149(3):299-302; discussion 302, 2007 Jackler RK et al: A new theory to explain the genesis of petrous apex cholesterol granuloma Otol Neurotol 24(1): 96-106; discussion 106, 2003 Brackmann DE et al: Surgical management of petrous apex cholesterol granulomas Otol Neurotol 23(4): 529-33, 2002 Chaljub G et al: Magnetic resonance imaging of petrous tip lesions Am J Otolaryngol 20(5):304-13, 1999 Palacios E et al: Petrous apex lesions: cholesterol granuloma Ear Nose Throat J 78(4): 234, 1999 Chang P et al: Imaging destructive lesions of the petrous apex Laryngoscope 108(4 Pt 1): 599-604, 1998 Morrison GA et al: Cholesterol cyst and cholesterol granuloma of the petrous bone J Laryngol Otol 106(5): 465-7, 1992 10 Clifton AG et al: Cholesterol granuloma of the petrous apex Br J Radiol 63(753): 724-6, 1990 11 Greenberg JJ et al: Cholesterol granuloma of the petrous apex: MR and CT evaluation AJNR Am J Neuroradiol 9(6):1205-14, 1988 12 Griffin C et al: MR and CT correlation of cholesterol cysts of the petrous bone AJNR Am J Neuroradiol 8(5): 825-9, 1987 13 Lo WW et al: Cholesterol granuloma of the petrous apex: CT diagnosis Radiology 153(3):705-11, 1984 P.VI(5):17 Image Gallery 1530 Diagnostic Imaging Head and Neck (Left) Large petrous apex cholesterol granuloma is seen on bone CT as an expansile mass with fully dehiscent anterolateral margin The lesion has broken into the IAC and is eroding the otic capsule The cavernous ICA is displaced anteriorly (Right) A more inferior axial bone CT in the same patient again shows the PA-CG compressing the bony eustachian tube Fluid in the mastoid is secondary to eustachian tube obstruction (Left) Axial T1WI MR in the same patient reveals the expansile, high signal petrous apex cholesterol granuloma The mastoid fluid is intermediate signal, most likely due to higher protein in the fluid (Right) Axial T2WI MR in the same patient shows a high signal expansile PA mass A few low signal foci are seen within the mass secondary to hemosiderin deposits In the classic cholesterol granuloma both T1 and T2 are high signal Obstructed fluid in the mastoid is also high signal 1531 Diagnostic Imaging Head and Neck (Left) Axial bone CT reveals an expansile cholesterol granuloma in the petrous apex that thins the posterior margin of the horizontal petrous ICA Note the 2nd opacified but nonexpanded air cell posterolateral to the expansile cell (Right) Axial T1WI MR in the same patient shows a high signal cholesterol granuloma focus & a 2nd high signal area posterolaterally Additional smaller foci are present laterally If left untreated, this lesion would continue to grow Apical Petrositis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Petrous Apex > Infectious and Inflammatory Lesions > Apical Petrositis Apical Petrositis H Ric Hamsberger, MD Key Facts Terminology Definition: Extension of middle ear-mastoid (ME-M) infection into pneumatized petrous apex (PA) with resulting suppurative apical petrositis Imaging Bone CT: Trabecular breakdown ± cortical erosions in opacified PA air cells Enhanced T1 findings Rim-enhancing fluid-filled petrous apex Adjacent meningeal thickening Enhanced T1 findings: Advanced disease Thickened, C+ Meckel cave, & cavernous sinus Skull base osteomyelitis (enhancing clival marrow) Enhancing cranial nerves (especially CN5, CN6) Petrous ± cavernous ICA spasm Epidural or brain abscess Top Differential Diagnoses PA trapped fluid PA metastasis PA cholesterol granuloma PA congenital cholesteatoma Petrooccipital fissure chondrosarcoma Pathology Pathophysiology: Suppurative ME-M infection spreads via air cells or venous channels to PA Clinical Issues Complete clinical syndrome = Gradenigo syndrome Acute otomastoiditis, deep facial pain (CN5), & lateral rectus palsy (CN6) Treatment: Antibiotics alone usually sufficient If severe symptoms at presentation, surgical intervention with mastoidectomy 1532 Diagnostic Imaging Head and Neck (Left) Axial graphic of the left petrous apex shows “confluent apical petrositis” with petrous apex abscess formation Pus surrounds the 6th cranial nerve & associated inflammation thickens adjacent meninges (Right) Axial bone CT in a child with full-blown Gradenigo syndrome (retro-orbital pain, lateral rectus palsy, & otorrhea) reveals infection of left PA cortical bone with infection crossing the petrooccipital fissure to involve the bone of the lateral clivus (Left) Axial T1WI C+ FS MR in the same patient shows infection of the PA with adjacent involvement of the clivus , dura , & IAC Note the spasm of cavernous ICA secondary to adjacent infectious process (Right) Axial T1WI C+ MR in a patient with subtle apical petrositis reveals intense enhancement of the petrous apex air cells with subtle adjacent dural enhancement in the posterior fossa and middle cranial fossa Bone CT showed no loss of PA trabeculae P.VI(5):19 TERMINOLOGY Synonyms Confluent apical petrositis, petrous apicitis Definitions Extension of middle ear-mastoid (ME-M) infection into pneumatized petrous apex (PA) with resulting suppurative apical petrositis IMAGING General Features Best diagnostic clue Bone CT: Trabecular breakdown ± cortical erosions in opacified PA air cells 1533 Diagnostic Imaging Head and Neck Location Both mastoid & petrous air cells usually simultaneously involved Early disease confined to petrous apex Advanced disease spreads to meninges, skull base, Meckel cave, & cavernous sinus Morphology Irregular phlegmon confined to PA until cortical breakthrough & meningeal involvement occurs CT Findings CECT Peripherally enhancing fluid (pus) in petrous apex Thickened & enhancing meninges Advanced disease Epidural abscess Cavernous sinus phlegmon ± thrombosis Bone CT Affected PA is pneumatized Opacification of PA air cells Middle ear-mastoid opacification usually associated Destructive changes of PA = coalescent apical petrositis PA trabeculae lysis Focal cortical destruction in PA Fistulization of bony labyrinth in advanced disease MR Findings T1WI Asymmetric low to intermediate signal in PA T2WI High signal within air cells of petro-mastoid complex High signal focus in PA where focal abscess may occur Advanced disease Cavernous or sigmoid sinus thrombosis Epidural or brain abscess T1WI C+ Rim-enhancing fluid-filled petrous apex Avidly enhancing adjacent meningeal thickening Advanced disease Skull base osteomyelitis: Enhancing marrow in clivus Thickened, enhancing Meckel cave & cavernous sinus Enhancing cranial nerves (especially CN5, CN6) Petrous ± cavernous ICA spasm Epidural or brain abscess MRA Severe lesions can involve adjacent skull base arteries Internal carotid arteritis Petrous carotid pseudoaneurysm rare MRV Advanced disease may cause dural venous sinus thrombophlebitis Cavernous, petrosal, or sigmoid sinus, jugular bulb-vein thrombosis possible Nuclear Medicine Findings Bone scan Asymmetric uptake in PA on Tc bone scan or gallium scan PET/CT Avid uptake possible; not mistake for tumor Imaging Recommendations Best imaging tool Initial diagnosis best made with thin-section T-bone CT Axial & coronal T1 C+ MR with fat saturation, including PA, skull base, & cavernous sinus important in evaluating intracranial complications DIFFERENTIAL DIAGNOSIS PA Trapped Fluid Clinical: Usually asymptomatic incidental brain MR finding 1534 Diagnostic Imaging Head and Neck CT: PA air cell trabeculae maintained; nonexpansile MR: Usually intermediate T1 MR signal T1 signal may be high High T2 signal; no meningeal enhancement PA Metastasis Clinical: Lacks acute infectious symptoms Systemic malignancy known CT: Permeative-destructive mass of PA MR: Infiltrative inhomogeneous enhancing PA mass PA Cholesterol Granuloma CT: Trabecular breakdown & cortical expansion in PA MR: T1 & T2 signal high T2 low signal hemosiderin rim possible PA Congenital Cholesteatoma CT: Smooth, expansile PA mass MR: Low T1 MR signal; no meningeal enhancement DWI high signal (restricted diffusion) Petrooccipital Fissure Chondrosarcoma Clinical: Lacks acute infectious symptoms CT: Destructive mass of petrooccipital fissure + Ca++ (50%) MR: Infiltrative inhomogeneous enhancing petrooccipital fissure mass P.VI(5):20 PATHOLOGY General Features Etiology Acute or chronic suppurative ME-M infection spreads via air cells or venous channels to PA Infection of PA air cells causes coalescence with breakdown of trabeculae ± cortical loss Thrombophlebitis or direct extension to adjacent structures, including meninges, Meckel cave, & cavernous sinus Embryology-anatomy Pneumatized PA present ≈ 33% PA pneumatization required for apical petrositis to occur in most cases In rare nonpneumatized PA, spread via fascial planes, vascular channels, or directly through osteomyelitic bone Gross Pathologic & Surgical Features Soft osteomyelitic bone with pockets of purulent material within confluent PA air cells Air cell tracks from mastoid to PA filled with pus and granulation tissue Phlegmon thickens & inflames adjacent meninges Microscopic Features Offending organism often not cultured secondary to preoperative broad spectrum antibiotics Flora of acute infection similar to otomastoiditis: S pneumoniae, H influenzae Chronic apical petrositis associated with chronic suppurative otomastoiditis: P aeruginosa, Proteus CLINICAL ISSUES Presentation Most common signs/symptoms Otorrhea associated with deep facial, ear, or retro-orbital pain Other signs/symptoms Symptoms variable; may be subtle, appearing gradually or acutely Acute onset of deep facial pain & otorrhea following acute otomastoiditis Insidious onset of cranial neuropathy (especially CN5) & otorrhea with chronic suppurative ear Other cranial neuropathies (CN6, 7, & 8) Fever, hearing loss, & diplopia Clinical profile Complete clinical syndrome = Gradenigo syndrome Classic clinical triad associated with apical petrositis Rare presentation Acute otomastoiditis, deep facial pain (CN5), & lateral rectus palsy (CN6) 1535 Diagnostic Imaging Head and Neck Demographics Age Child or adolescent with acute otomastoiditis Adult with chronic suppurative ear or following mastoidectomy Epidemiology Rare in post-antibiotic era Natural History & Prognosis Progresses to obtundation & death if untreated (common in pre-antibiotic era) Prognosis excellent given adequate surgical drainage & aggressive antibiotics Treatment Antibiotics alone usually sufficient Used when severe symptoms not yet present If severe symptoms at presentation, surgical intervention with mastoidectomy Surgery follows air cell tracks to PA Multiple surgical options have been described Simple vs radical mastoidectomy & middle cranial fossa approach DIAGNOSTIC CHECKLIST Consider Consider initial imaging with a thin-section nonenhanced T-bone CT MR with multiplanar, fat-saturated, enhanced images are most effective way to evaluate for intracranial complications Image Interpretation Pearls T-bone CT to evaluate for subtle trabecular ± cortical erosion & involvement of middle and inner ear To differentiate from other PA lesions, look for peripheral PA/meningeal enhancement & correlate with clinical history Evaluate vascular structures adjacent to PA for involvement: ICA, dural venous sinuses, cavernous sinus SELECTED REFERENCES Connor SE et al: Imaging of the petrous apex: a pictorial review Br J Radiol 81(965):427-35, 2008 Fournier HD et al: Surgical anatomy of the petrous apex and petroclival region Adv Tech Stand Neurosurg 32:91146, 2007 Lee YH et al: CT, MRI and gallium SPECT in the diagnosis and treatment of petrous apicitis presenting as multiple cranial neuropathies Br J Radiol 78(934):948-51, 2005 Park SN et al: Cavernous sinus thrombophlebitis secondary to petrous apicitis: a case report Otolaryngol Head Neck Surg 128(2): 284-6, 2003 Price T et al: Abducens nerve palsy as the sole presenting symptom of petrous apicitis J Laryngol Otol 116(9): 7269, 2002 Dave AV et al: Clinical and magnetic resonance imaging features of Gradenigo syndrome Am J Ophthalmol 124(4): 568-70, 1997 Murakami T et al: Gradenigo's syndrome: CT and MRI findings Pediatr Radiol 26(9): 684-5, 1996 Hardjasudarma M et al: Magnetic resonance imaging features of Gradenigo's syndrome Am J Otolaryngol 16(4): 247-50, 1995 Frates MC et al: Petrous apicitis: evaluation by bone SPECT and magnetic resonance imaging Clin Nucl Med 15(5): 293-4, 1990 10 Contrucci RB et al: Petrous apicitis Ear Nose Throat J 64(9): 427-31, 1985 11 Allam AF et al: Pathology of petrositis Laryngoscope 78(11):1813-32, 1968 P.VI(5):21 Image Gallery 1536 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in a patient with severe headache associated with suppurative otomastoiditis shows rim-enhancing pus in confluent PA air cells The horizontal petrous ICA has thick enhancing phlegmon along its margins (Right) Coronal MRA in the same patient reveals a long segment of horizontal-cavernous internal carotid artery narrowing secondary to carotid canal phlegmon associated with the confluent apical petrositis and suppurative otomastoiditis (Left) Axial bone CT in a patient with “trapped fluid” in PA on head MR shows opacification of PA air cells with no trabecular loss The imaging diagnosis was uncomplicated “trapped fluid.” (Right) Axial bone CT in the same patient, now with new severe headache years after initial diagnosis of “trapped fluid,” shows loss of PA trabeculae and cortical thickening The presumptive imaging diagnosis of superinfection of “trapped fluid” was made & symptoms responded to antibiotics 1537 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ MR in a child presenting with headache and fever demonstrates rim-enhancing pus in the right petrous apex and area of the porus acusticus Focal enhancement in the right internal auditory canal indicates the infection has caused focal meningitis (Right) Axial DWI MR in the same patient at the level of the lateral ventricles shows restricted diffusion caused by frontoparietal empyema Spread of bacteria from the IAC over the cerebral hemisphere has occurred Vascular Lesions Petrous Apex ICA Aneurysm > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Petrous Apex > Vascular Lesions > Petrous Apex ICA Aneurysm Petrous Apex ICA Aneurysm H Ric Hamsberger, MD Key Facts Terminology Rare congenital or acquired aneurysm of petrous ICA Imaging Complex expansile mass of petrous ICA canal with internal flow on CTA, MRA, or angio Size: Variable; 1-5 cm Shape: Focal ovoid to fusiform Bone CT findings Focal ovoid or fusiform enlargement of petrous ICA canal Curvilinear calcifications in aneurysm wall CTA: Aneurysmal dilation of petrous ICA is diagnostic MR findings T1: Complex signal mass High signal: Intraluminal clot, slow flow Low signal: Wall calcification, high flow Top Differential Diagnoses Petrous apex cholesterol granuloma Aberrant internal carotid artery Dehiscent jugular bulb Pathology Congenital aneurysm (true aneurysm) Forms at congenital weakness at origin of obliterated embryologic vessel (caroticotympanic) Acquired aneurysm (false or pseudoaneurysm) Post-traumatic, postinfectious, post-radiation Clinical Issues Sensorineural hearing loss, Horner syndrome, pulsatile tinnitus, stroke Gradual enlargement; progressive risk of rupture 1538 Diagnostic Imaging Head and Neck Endovascular therapy: Obliteration or stent placement (Left) Axial graphic through the left temporal bone shows a focal aneurysmal dilation of horizontal petrous internal carotid artery Note the proximity to the trigeminal nerve and the abducens nerve to the petrous ICA aneurysm (Right) Axial bone CT in a patient presenting with recurrent transient ischemic attacks shows an expansile ovoid lesion in the left petrous apex Note the anterior wall dehiscence where the aneurysm connects to the horizontal petrous ICA (Left) Axial T2WI MR in the same patient demonstrates a complex signal ovoid mass in the PA Without CTA or MRA, it might be possible to mistake this petrous ICA aneurysm for a cholesterol granuloma (Right) Oblique left internal carotid artery angiogram in the same patient reveals the PA aneurysm projecting off the under surface of the horizontal petrous internal carotid artery P.VI(5):23 TERMINOLOGY Definitions Rare congenital or acquired aneurysm of petrous ICA IMAGING General Features Best diagnostic clue Complex expansile mass of petrous ICA canal with internal flow on CTA, MRA, or angio Location Horizontal petrous ICA most common location Size 1539 Diagnostic Imaging Head and Neck Variable: 1-5 cm CT Findings Bone CT Focal ovoid or fusiform enlargement of petrous ICA canal Curvilinear calcifications in aneurysm wall May appear destructive Extensive bone loss/remodeling possible When breaks into petrous apex (PA) air cells, loses ovoid shape CTA Aneurysmal dilation of petrous ICA is diagnostic MR Findings T1WI Complex signal mass High signal: Intraluminal clot, slow flow Low signal: Wall calcification, high flow T2WI Complex signal mass with peripheral hemosiderin Internal flow voids produce swirl pattern T1WI C+ Diffusely enhancing complex mass within PA MRA Enlarged, irregular area along petrous ICA Often smaller than actual aneurysm since only lumen with flowing blood is seen Angiographic Findings Petrous ICA aneurysm lumen visible May underestimate aneurysm size Imaging Recommendations Best imaging tool CTA is best exam Diagnostic of aneurysm with precise localization along petrous ICA Bone CT from CTA show skull base anatomy Angiography for treatment not diagnosis DIFFERENTIAL DIAGNOSIS Petrous Apex Cholesterol Granuloma Bone CT: Expansile PA mass MR: ↑ T1 & T2 signal in PA Aberrant Internal Carotid Artery Bone CT: Tubular mass crosses middle ear cavity to rejoin horizontal petrous ICA CTA or MRA: Artery enters middle ear posterolateral to normal entry point Dehiscent Jugular Bulb Bone CT: Focal absence of sigmoid plate connects jugular bulb to middle ear “mass” CTA or MRV: Coronal reprojection shows “bud” off superolateral jugular bulb PATHOLOGY General Features Etiology Congenital aneurysm (true aneurysm) Forms at congenital weakness at origin of obliterated embryologic vessel (caroticotympanic) Acquired aneurysm (false or pseudoaneurysm) Post-traumatic, postinfectious, post-radiation Rarely atherosclerotic in this location Associated abnormalities Congenital aneurysm associated with multiple additional intracranial aneurysms CLINICAL ISSUES Presentation Most common signs/symptoms Sensorineural hearing loss Other signs/symptoms Horner syndrome Pulsatile tinnitus 1540 Diagnostic Imaging Head and Neck Transient ischemic attacks; stroke Demographics Age Congenital aneurysm: Childhood or adolescence Acquired pseudoaneurysm: Any age Epidemiology Very rare lesion: Errors in diagnosis common Natural History & Prognosis Gradual enlargement; progressive risk of rupture Treatment Endovascular therapy Allows for pretreatment ICA occlusion trial Balloon trapping or aneurysmal obliteration with ICA preservation Endovascular stent placement across aneurysm viable option Surgical therapy no longer preferred 1st approach When necessary includes ICA sacrifice with or without ECA-ICA bypass SELECTED REFERENCES Malikov S et al: Open surgical reconstruction of the internal carotid artery aneurysm at the base of the skull J Vasc Surg 51(2):323-9, 2010 Liu JK et al: Aneurysms of the petrous internal carotid artery: anatomy, origins, and treatment Neurosurg Focus 17(5):E13, 2004 Halbach VV et al: Aneurysms of the petrous portion of the internal carotid artery: results of treatment with endovascular or surgical occlusion AJNR Am J Neuroradiol 11(2):253-7, 1990 Section - Intratemporal Facial Nerve Pseudolesions Intratemporal Facial Nerve Enhancement > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Intratemporal Facial Nerve > Pseudolesions > Intratemporal Facial Nerve Enhancement Intratemporal Facial Nerve Enhancement H Ric Hamsberger, MD Key Facts Terminology Definition: Normal enhancement on T1 C+ MR along course of intratemporal facial nerve (CN7) without abnormal bony changes Imaging T1 C+ MR enhancement along CN7 Geniculate ganglion, tympanic, & mastoid segments Bone CT shows normal CN7 canal Top Differential Diagnoses Bell palsy Perineural parotid tumor of intratemporal CN7 Facial nerve schwannoma within T-bone Pathology Lush circumneural arteriovenous plexus surrounds CN7 within temporal bone Labyrinthine segment is least well vascularized Clinical Issues Clinical presentation: Asymptomatic by definition Treatment: None; not mistake for Bell palsy Bone CT used when asymmetric enhancement is marked to rule out underlying bony changes Diagnostic Checklist Enhancement along cisternal, labyrinthine segment or extracranial mastoid FN segments is not normal Higher field strength (3T) makes normal CN7 enhancement more conspicuous Normal CN7 enhancement will not change over time If fundal vestibular schwannoma present, labyrinthine segment of CN7 may enhance normally Arteriovenous plexus congestion likely cause 1541 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR through the internal auditory canals reveals normal geniculate ganglion and anterior tympanic segment CN7 enhancement on the left On the right, the normal anterior tympanic segment enhancement is visible (Right) Axial T1WI C+ FS MR in a patient with right vestibular schwannoma demonstrates increased enhancement of the labyrinthine CN7, geniculate ganglion , and anterior tympanic segment CN7 (Left) Coronal T1WI C+ FS MR at the level of the vestibules reveals normal enhancement of the mid-tympanic segment of the facial nerves (Right) Coronal T1WI C+ FS MR in the same patient shows the normal geniculate ganglion enhancement just superior to the cochleas Note that the tensor tympani muscles both also enhance With 3T imaging, more normal enhancement of structures within the temporal bone is seen P.VI(6):3 TERMINOLOGY Definitions Normal enhancement on T1 C+ MR along course of intratemporal facial nerve (CN7) without abnormal bony changes IMAGING General Features Best diagnostic clue T1 C+ MR enhancement along CN7 geniculate ganglion, tympanic, & mastoid segments without bony CN7 canal changes Location Geniculate ganglion, tympanic, & mastoid segments CT Findings 1542 Diagnostic Imaging Head and Neck Bone CT Normal bony intratemporal CN7 canal MR Findings T1WI Normal CN7 will produce increased signal on T1 C-compared to surrounding osseous structures T1WI C+ Normal enhancement along portions of CN7 Mastoid > geniculate ganglion > tympanic segments Imaging Recommendations Best imaging tool Normal enhancement seen best on mm axial & coronal T1 C+ MR of T-bone CT used if continued doubt about CN7 normalcy DIFFERENTIAL DIAGNOSIS Bell Palsy Clinical: Acute onset unilateral peripheral CN7 paralysis T1 C+ MR: Intense enhancement of intratemporal CN7 “Tuft” of IAC fundal enhancement highly suggestive Bone CT: CN7 bony canal normal Perineural Parotid Tumor of Intratemporal CN7 Clinical: Parotid mass + facial nerve paralysis T1 C+ MR: Focal enhancement spreading from invasive parotid mass into mastoid CN7 segment CT: Enlarged bony mastoid segment of CN7 canal Fat in stylomastoid foramen replaced by tissue Facial Nerve Schwannoma Within T-Bone Clinical: Hearing loss ± peripheral CN7 paresis late Most frequently found in geniculate fossa T1 C+ MR: Focal enhancing mass along CN7 course Bone CT: Enlargement of intratemporal CN7 canal PATHOLOGY General Features Embryology/anatomy CN7 plexus has components Anterior: From anterior tympanic branch of internal maxillary artery or middle meningeal artery Middle: Tympanic plexus on medial wall of mesotympanum supplied from ascending pharyngeal artery Posterior: From stylomastoid artery (from occipital artery) Lush circumneural arteriovenous plexus surrounds CN7 within temporal bone Labyrinthine segment is least well vascularized Microscopic Features Dense CN7 circumneural arteriovenous plexus predominantly located in geniculate ganglion, tympanic, & mastoid segments ± proximal greater superficial petrosal nerve CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic by definition Clinical profile CN7 normal enhancement seen incidentally during T1 C+ MR imaging work-up for unrelated clinical findings Demographics Epidemiology Majority of patients have enhancement along ≥ segment of intratemporal CN7 Enhancement seen along CN7 segments Natural History & Prognosis Normal FN enhancement will not change over time Treatment None; not mistake for Bell palsy Bone CT used when asymmetric CN7 enhancement is marked to rule out underlying bony changes DIAGNOSTIC CHECKLIST Consider 1543 Diagnostic Imaging Head and Neck Enhancement along cisternal, labyrinthine segment or extracranial mastoid FN segments is not normal Higher field strength (3T) makes normal enhancement more conspicuous If fundal vestibular schwannoma present, labyrinthine segment of CN7 may enhance normally Arteriovenous plexus congestion likely cause SELECTED REFERENCES Hong HS et al: Enhancement pattern of the normal facial nerve at 3.0 T temporal MRI Br J Radiol 83(986):118-21, 2010 Tabuchi T et al: Vascular permeability to fluorescent substance in human cranial nerves Ann Otol Rhinol Laryngol 111(8):736-7, 2002 Gebarski SS et al: Enhancement along the normal facial nerve in the facial canal: MR imaging and anatomic correlation Radiology 183(2):391-4, 1992 Middle Ear Prolapsing Facial Nerve > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Intratemporal Facial Nerve > Pseudolesions > Middle Ear Prolapsing Facial Nerve Middle Ear Prolapsing Facial Nerve H Ric Hamsberger, MD Key Facts Terminology Definition: Mid-tympanic facial nerve (CN7) segment protrudes through bony dehiscence CN7 dehiscence refers only to segmental absence of bony covering of CN7 Prolapsing CN7: CN7 protrudes through dehiscence in tympanic CN7 canal Imaging Incidental finding on temporal bone CT Tubular soft tissue extends from mid-tympanic CN7 into oval window niche Coronal bone CT Soft tissue “mass” in oval widow niche Along undersurface of lateral semicircular canal Contiguous with mid-tympanic segment of CN7 Axial bone CT Hammock-like CN7 spanning middle ear cavity under lateral semicircular canal Top Differential Diagnoses Intratemporal facial nerve schwannoma Oval window atresia Congenital cholesteatoma in facial nerve canal Persistent stapedial artery Clinical Issues Presentation: Asymptomatic most commonly Rarely conductive hearing loss from impingement on stapes Diagnostic Checklist Caveat: Prolapsed CN7 in peril during stapedectomy Report and call this finding to ear surgeon 1544 Diagnostic Imaging Head and Neck (Left) Coronal left ear temporal bone CT shows the normal tympanic segment of facial nerve in cross section along undersurface of lateral semicircular canal Note subtle bone covering and relationship to the oval window niche (Right) Coronal left ear temporal bone CT reveals focal “mass” projecting from mid-tympanic facial nerve Lesion is prolapsed facial nerve, not a facial nerve schwannoma Facial nerve prolapse can create significant surgical difficulties during stapedectomy (Left) Axial bone CT in the same patient demonstrates the hammock-like protruding tympanic segment of CN7 strung across middle ear cavity Notice CN7 touches the crura of the stapes, explaining the conductive hearing loss presentation (Right) Coronal left ear temporal bone CT shows a round soft tissue “mass” projecting off the mid-tympanic segment of CN7 Enhanced MR can differentiate protrusion of CN7 (no enhancement) vs facial nerve schwannoma (enhancement) P.VI(6):5 TERMINOLOGY Definitions Mid-tympanic facial nerve (CN7) segment protrudes through bony dehiscence CN7 dehiscence refers only to segmental absence of bony covering of CN7 Prolapsing CN7: CN7 protrudes through dehiscence IMAGING General Features Best diagnostic clue Tubular soft tissue extends from mid-tympanic CN7 into oval window niche (CT) 1545 Diagnostic Imaging Head and Neck Location Under surface lateral semicircular canal (LSC) → oval window niche Size Variable; may be subtle or appear mass-like (2-3 mm) within oval window niche Morphology Smooth, tubular appearance CT Findings Bone CT Coronal: Soft tissue “mass” in oval widow niche Along undersurface of LSC Contiguous with mid-tympanic segment of CN7 Axial: Hammock-like CN7 spanning middle ear cavity under LSC MR Findings T1 C+ is normal excluding facial nerve schwannoma Imaging Recommendations Best imaging tool Axial & coronal thin section temporal bone CT Best seen on coronal at level of oval window Protocol advice When protruding CN7 mass-like, use contrast-enhanced MR to exclude CN7 schwannoma Facial nerve schwannoma enhances DIFFERENTIAL DIAGNOSIS Intratemporal Facial Nerve Schwannoma Clinical: Hearing loss > > facial nerve palsy CT: Tubular enlargement of CN7 canal Geniculate fossa > tympanic > mastoid segments MR: Enhancing tubular mass enlarges CN7 canal Oval Window Atresia Clinical: Conductive hearing loss With or without EAC atresia CT: Facial nerve tympanic segment “ectopic” CN7 tympanic segment most common in oval window niche Congenital Cholesteatoma in Facial Nerve Canal Rare congenital cholesteatoma type CT: Enlargement of CN7 bony canal Most commonly geniculate ganglion area Persistent Stapedial Artery Asymptomatic vascular variant CT: Absent foramen spinosum Tubular lesion on cochlear promontory Large anterior tympanic segment CN7 PATHOLOGY General Features Etiology Congenital/developmental Can be acquired from cholesteatoma CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic most commonly Rarely conductive hearing loss: Impingement on stapes Clinical profile Incidental finding on temporal bone CT Critical to communicate its presence to surgeon prior to middle ear exploration Easy to injure facial nerve during stapedectomy if CN7 prolapse is present! Demographics Age All ages; congenital lesion Epidemiology 1546 Diagnostic Imaging Head and Neck Simple dehiscence without protrusion occurs ˜ 50% Prolapsing facial nerve is rare (˜ 1%) Natural History & Prognosis Excellent if left alone Treatment Careful avoidance at time of middle ear surgery DIAGNOSTIC CHECKLIST Image Interpretation Pearls Prolapse often associated with absence of notch defect along undersurface of LSC If notch is seen, consider alternative explanation Reporting Tips Caveat: Prolapsed CN7 in peril during stapedectomy Report and call this finding to ear surgeon SELECTED REFERENCES Ozbek C et al: Incidence of fallopian canal dehiscence at surgery for chronic otitis media Eur Arch Otorhinolaryngol 266(3):357-62, 2009 Di Martino E et al: Fallopian canal dehiscences: a survey of clinical and anatomical findings Eur Arch Otorhinolaryngol 262(2):120-6, 2005 Daniels RL et al: The other ear: findings and results in 1,800 bilateral stapedectomies Otol Neurotol 22(5):603-7, 2001 Swartz JD: The facial nerve canal: CT analysis of the protruding tympanic segment Radiology 153(2):443-7, 1984 Infectious and Inflammatory Lesions Bell Palsy > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Intratemporal Facial Nerve > Infectious and Inflammatory Lesions > Bell Palsy Bell Palsy H Ric Hamsberger, MD Key Facts Terminology Bell palsy (BP): Herpetic peripheral facial nerve paralysis secondary to herpes simplex virus Imaging T1WI C+ fat-saturated MR: Fundal “tuft” and labyrinthine segment CN7 intense asymmetric enhancement Entire intratemporal CN7 may enhance Imaging note: Classic rapid onset BP requires no imaging in initial stages If atypical Bell palsy, search with imaging for underlying lesion Top Differential Diagnoses Normal enhancement of intratemporal CN7 Facial nerve schwannoma Facial nerve hemangioma Perineural tumor from parotid Pathology Etiology-pathogenesis (current hypothesis) Latent herpes simplex infection of geniculate ganglion with reactivation and spread of inflammatory process along proximal and distal intratemporal facial nerve fibers Clinical Issues Classic clinical presentation Acute onset peripheral CN7 paralysis (36 hr onset) Medical therapy Tapering course of prednisone; begin within days of symptoms for best result Surgical therapy Profound denervation (> 95%) treated with facial nerve decompression from IAC fundus to stylomastoid foramen 1547 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR shows classic findings of Bell palsy with the fundal “tuft” sign , labyrinthine , and tympanic facial nerve segment enhancement (Right) Axial T1WI C+ FS MR in the same patient again shows the IAC fundal “tuft” sign and tympanic segment of the facial nerve enhancement Remember that only the geniculate ganglion area of the facial nerve may normally enhance (Left) Axial T1WI C+ FS MR in the same patient through the stylomastoid foramen demonstrates an enhancing, slightly enlarged facial nerve Swelling of the facial nerve is possible outside the bony facial nerve canal within the temporal bone (Right) Coronal T1WI C+ FS MR in the same patient reveals avid enhancement in the mastoid , stylomastoid , and extracranial facial nerve in this patient with typical Bell palsy P.VI(6):7 TERMINOLOGY Abbreviations Bell palsy (BP) Synonyms Herpetic facial paralysis Definitions BP (original definition): Idiopathic acute onset lower motor neuron facial paralysis BP (modern definition): Herpetic facial paralysis secondary to herpes simplex virus IMAGING General Features Best diagnostic clue Fundal “tuft” and labyrinthine segment CN7 intense asymmetric enhancement on T1WI C+ MR 1548 Diagnostic Imaging Head and Neck Location Fundal and labyrinthine segment CN7 most commonly affected May involve entire intratemporal CN7 Intraparotid segment less commonly affected Size CN7 swells within facial nerve canal CT Findings CECT No role for C+ CT in BP Bone CT Normal facial nerve canal If enlargement present, not Bell palsy MR Findings T1WI Intratemporal CN7 may be more conspicuous T2WI Brain normal; no high signal lesions High-resolution T2WI may show distal IAC CN7 enlargement T1WI C+ Uniform, contiguous CN7 enhancement CN7: Normal in size within bony canal CN7: Conspicuous high signal appears slightly enlarged Enhancement pattern is linear, not nodular Enhancement is usually present from distal IAC through labyrinthine segment, geniculate ganglion, and anterior tympanic segment Tuft of enhancement in IAC fundus (premeatal segment) along with C+ of labyrinthine segment of CN7 are distinctive MR findings Mastoid CN7 enhances less frequently Enhancement of intraparotid CN7 infrequent Holotympanic CN7 enhancement may be seen Imaging Recommendations Best imaging tool Thin section fat-saturated T1WI C+ MR focused to IAC and temporal bone T-bone CT: Only used if MR creates suspicion of enlarged CN7 canal Classic rapid onset BP requires no imaging in initial stages 90% CN7 recover spontaneously in < months If decompressive surgery is anticipated, MR imaging warranted to ensure that no other lesion is causing CN7 paralysis If atypical Bell palsy, search for underlying lesion Atypical Bell palsy Slowly progressive CN7 palsy Facial hyperfunction (spasm) preceding BP Recurrent CN7 palsies Unusual degrees of ear pain BP with any other associated cranial neuropathies Peripheral CN7 paralysis persisting or deepening > months DIFFERENTIAL DIAGNOSIS Normal Enhancement of Intratemporal CN7 Clinical: No facial nerve paralysis T1WI C+ MR: Mild, linear, discontinuous enhancement of anterior and posterior genus of intratemporal CN7 Premeatal and labyrinthine CN7 segments normal Facial Nerve Schwannoma Clinical: Hearing loss more common than CN7 palsy T1WI C+ MR: Well-circumscribed, tubular, C+ mass within enlarged CN7 canal most commonly centered on geniculate ganglion Facial Nerve Hemangioma Clinical: CN7 paralysis occurs when lesion is small Bone CT: May show intratumoral bone spicules T1WI C+ MR: Poorly circumscribed, enhancing mass commonly found in geniculate fossa 1549 Diagnostic Imaging Head and Neck Perineural Tumor from Parotid Clinical: Parotid malignancy usually palpable Imaging: Invasive parotid mass is present Tissue-filled stylomastoid foramen CN7 is enlarged from distal to proximal with mastoid air cell invasion associated PATHOLOGY General Features Etiology Etiology-pathogenesis (current hypothesis) Latent herpes simplex infection of geniculate ganglion with reactivation and spread of inflammatory process along proximal and distal CN7 fibers Pathophysiology: Formation of intraneural edema in neuronal sheaths caused by breakdown of blood-nerve barrier and by venous congestion in epineural and perineural venous plexus CN7 swelling within bony canal causes ischemia Intratemporal CN7 normal anatomy CN7 normal C+ at its anterior and posterior genus C+ from robust circumneutral arteriovenous plexus Radiologist must be familiar with normal CN7 T1WI C+ MR enhancement P.VI(6):8 Familiarity with normal patterns of intratemporal CN7 C+ allows radiologist to identify abnormal C+ seen with BP Gross Pathologic & Surgical Features CN7 edema peaks at weeks after symptom onset Microscopic Features Herpes simplex DNA recovered from CN7 CLINICAL ISSUES Presentation Most common signs/symptoms Acute onset peripheral CN7 paralysis (36 hour onset) Clinical profile Healthy adult with acute unilateral CN7 paralysis More common in diabetic patients Other signs/symptoms Viral prodrome often reported before BP onset 70%: Taste alterations days before CN7 paralysis 50%: Pain around ipsilateral ear (not severe) 20%: Numbness in ipsilateral face Demographics Age All ages affected; incidence peaks in 5th decade Epidemiology Herpetic facial paralysis is responsible for > 50% of peripheral CN7 paralysis cases Annual BP incidence: 15-30/100,000 persons Natural History & Prognosis > 90% of patients spontaneously recover all or part of CN7 function without therapy in 1st months Treatment Test for diabetes and Lyme disease Medical therapy Tapering course of prednisone; begin within days of symptoms for best result Acyclovir or valacyclovir (antivirals) out of favor Surgical therapy Profound denervation (> 95%) treated with CN7 decompression, fundus to stylomastoid foramen Decompression performed within weeks of onset of total paralysis for maximal effect Intensity, pattern ± location of enhancement seen on T1WI C+ MR not helpful in predicting outcome for individual patient DIAGNOSTIC CHECKLIST Consider 1550 Diagnostic Imaging Head and Neck MR imaging reserved for atypical Bell palsy Abnormal CN7 C+ may persist well beyond clinical improvement or full recovery Image Interpretation Pearls “Tuft” of IAC fundal C+ associated with labyrinthine segment CN7 C+ without associated focal lesion is highly suggestive of Bell palsy Reporting Tips Remember to comment on parotid as normal Also note absence of focal CN7 lesions SELECTED REFERENCES Song MH et al: Clinical significance of quantitative analysis of facial nerve enhancement on MRI in Bell's palsy Acta Otolaryngol 128(11):1259-65, 2008 Sullivan FM et al: Early treatment with prednisolone or acyclovir in Bell's palsy N Engl J Med 357(16):1598-607, 2007 Kress B et al: Bell palsy: quantitative analysis of MR imaging data as a method of predicting outcome Radiology 230(2):504-9, 2004 Suzuki F et al: Herpes virus reactivation and gadolinium-enhanced magnetic resonance imaging in patients with facial palsy Otol Neurotol 22(4):549-53, 2001 Roob G et al: Peripheral facial palsy: etiology, diagnosis and treatment Eur Neurol 41(1):3-9, 1999 Engstrom M et al: Serial gadolinium-enhanced magnetic resonance imaging and assessment of facial nerve function in Bell's palsy Otolaryngol Head Neck Surg 117(5):559-66, 1997 Saatỗi I et al: MRI of the facial nerve in idiopathic facial palsy Eur Radiol 6(5):631-6, 1996 Tien R et al: Contrast-enhanced MR imaging of the facial nerve in 11 patients with Bell's palsy AJNR Am J Neuroradiol 11(4):735-41, 1990 Tables Brackman Facial Nerve Grading System Grade Description of Facial Measurement** Function % Estimated Function % Paralysis I Normal 8/8 100 100 II Slight 7/8 76-99 80 III Moderate 5/8-6/8 51-75 60 IV Moderately severe 3/8-4/8 26-50 40 V Severe 1/8-2/8 1-25 20 VI Total 0/8 0 ** Facial nerve injury is measured by the superior movement of the mid-portion of the upper eyebrow and the lateral movement of the oral commissure For each 0.25 cm of upward motion for both eyebrow and oral commissure, a scale of is assigned up to cm The points are then added together A total of points can be obtained if both the eyebrow and the oral commissure both move cm Adapted from House JW et al: Facial nerve grading system Otolaryngol Head Neck Surg 93(2):146-7, 1985 P.VI(6):9 Image Gallery 1551 Diagnostic Imaging Head and Neck (Left) Coronal T1WI C+ FS MR in a patient with right Bell palsy shows asymmetric right mastoid CN7 avid enhancement compared to the minimal enhancement on the left (Right) Coronal T1WI C+ FS MR in the same patient shows similar enhancement of the right compared to the left geniculate ganglion This can be explained by the fact that the geniculate ganglion is the area of normal intratemporal facial nerve enhancement (Left) Axial T1WI MR in a patient with left Bell palsy reveals the left facial nerve in the stylomastoid foramen is larger than the right The injured left facial nerve swells when it is not confined by the intratemporal bony facial nerve canal (Right) Axial T1WI C+ FS MR in a patient with right-sided Bell palsy demonstrates typical findings of enhancing tympanic and labyrinthine segments of the facial nerve Notice the more subtle IAC fundus “tuft” sign 1552 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in a patient with profound, unremitting Bell palsy shows intense enhancement of the labyrinthine, geniculate ganglion, and anterior tympanic portions of the facial nerve The IAC “tuft” spreads along the IAC facial nerve as more subtle enhancement reaching the porus acusticus (Right) Axial thin section (1 mm) T2WI FS MR in the same patient reveals a swollen intracanalicular facial nerve through the internal auditory canal Benign and Malignant Tumors T-Bone Facial Nerve Venous Malformation (Hemangioma) > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Intratemporal Facial Nerve > Benign and Malignant Tumors > T-Bone Facial Nerve Venous Malformation (Hemangioma) T-Bone Facial Nerve Venous Malformation (Hemangioma) H Ric Harnsberger, MD Key Facts Terminology Facial nerve venous malformation (FNVM) Older terms: Facial nerve hemangioma/ossifying hemangioma Definition: Benign developmental lesion near intratemporal CN7 in geniculate fossa area Imaging “Honeycomb” high-density matrix lesion in geniculate fossa area (bone CT) Enhancing geniculate ganglion area lesion with irregular margins (T1 C+ MR) Top Differential Diagnoses Normal intratemporal facial nerve enhancement Intratemporal facial nerve schwannoma Bell palsy Perineural parotid malignancy on intratemporal CN7 Congenital cholesteatoma within intratemporal CN7 canal Pathology Immunohistochemical markers critical to correct VM diagnosis Endothelial lining of vascular channels stain negatively for hemangioma-associated markers (GLUT1 & LeY) Podoplanin staining utilizing D2-40 antibody negativity excludes lymphatic malformation Clinical Issues Intratemporal FNVM produces peripheral CN7 paralysis early in its natural history Caveat: May be described as “atypical Bell palsy!” Treatment: Surgery done as soon as possible Final CN7 function depends on duration of preoperative CN7 deficit 1553 Diagnostic Imaging Head and Neck (Left) Axial graphic illustrates a classic example of a medium-sized facial nerve venous malformation centered in the geniculate fossa of the T-bone Notice the “honeycomb” bone within the lesion matrix (Right) Axial enhanced T1 MR with fat saturation in a patient with a left “atypical Bell palsy” reveals a classic left geniculate fossa enhancing facial nerve venous malformation Punctate areas of high density on bone CT (not shown) confirmed this imaging impression (Left) Axial bone CT demonstrates the “honeycombing” appearance of FNVM centered in the geniculate fossa Note extension of the lesion along the proximal tympanic CN7 segment (Right) Axial T1WI C+ MR in the same patient shows a poorly marginated avidly enhancing lesion in the geniculate fossa Note extension along tympanic segment of CN7 and into the fundus of the internal auditory canal IAC extension occurred via the labyrinthine segment of CN7 (not shown) P.VI(6):11 TERMINOLOGY Abbreviations Facial nerve venous malformation (FNVM) Synonyms Facial nerve hemangioma/ossifying hemangioma Historic terms for FNVM Definitions FNVM: Benign developmental lesion near intratemporal facial nerve in geniculate fossa area IMAGING General Features 1554 Diagnostic Imaging Head and Neck Best diagnostic clue “Honeycomb” high-density matrix lesion in geniculate fossa area (bone CT) Enhancing geniculate ganglion area lesion with irregular margins (T1 C+ MR) Location Geniculate fossa area > > internal auditory canal Size Range: mm to cm Small at presentation, often < cm Morphology Irregular, invasive-appearing margins typical CT Findings Bone CT Poorly marginated lesion of geniculate fossa Larger lesions affect adjacent temporal bone Anteromedial to geniculate fossa Labyrinthine segment CN7 → internal auditory canal (IAC) “Dumbbell” lesion appearance Amorphous “honeycomb” bone changes are distinctive Seen in 100% of larger lesions Punctate high-density foci also possible MR Findings T1WI Mixed signal lesion with foci of low signal within lesion matrix (ossific matrix) T2WI High signal lesion with foci of low signal within lesion matrix FLAIR Lesion mixed intermediate & high signal T1WI C+ Avid lesion enhancement is rule Perineural spread from geniculate ganglion Posterolateral along tympanic segment CN7 Posteromedial along labyrinthine segment CN7 → internal auditory canal “Dumbbell” appearance possible Fundal IAC FNVM, exactly mimics vestibular schwannoma Ovoid, well-demarcated, enhancing IAC mass Low signal foci may distinguish from vestibular schwannoma Imaging Recommendations Best imaging tool Imaging indication CN7 (facial nerve paresis) or CN8 (hearing loss) dysfunction 1st exam: Thin section T1 C+ MR focused to CPA-IAC-inner ear If MR negative or shows equivocal small area of enhancement along intratemporal CN7, recommend Tbone CT Bone CT may show small FNVM in geniculate fossa Inspect intratemporal CN7 canal carefully for 1-2 mm FNVM DIFFERENTIAL DIAGNOSIS Normal Intratemporal Facial Nerve Enhancement Clinical: Asymptomatic Imaging: T1 C+ MR shows normal enhancement of geniculate ganglion, anterior tympanic CN7, or mastoid segment CN7 Comment: Sometimes mistaken for facial nerve pathology Intratemporal Facial Nerve Schwannoma Clinical: Hearing loss ± gradual onset of CN7 paralysis Imaging: T1 C+ MR reveals tubular enhancing mass, smoothly enlarging CN7 canal (bone CT) Comment: Most commonly centered in geniculate ganglion like FNVM Bell Palsy Clinical: Acute onset of peripheral CN7 paralysis Imaging: T1 C+ MR shows prominent enhancement of entire intratemporal CN7 Comment: No focal mass; bone CT normal Perineural Parotid Malignancy on Intratemporal CN7 1555 Diagnostic Imaging Head and Neck Clinical: Parotid malignancy in history, palpable or subclinical Imaging: T1 C+ MR shows invasive parotid mass Stylomastoid foramen is tissue filled CN7 enlarged & enhancing from distal to proximal CN7 may be involved to CPA-IAC Mastoid air cell invasion also possible Comment: Continuous linear nature different from focal FNVM Congenital Cholesteatoma Within Intratemporal CN7 Canal Clinical: Avascular mass behind intact tympanic membrane Imaging: T1 C+ MR shows nonenhancing middle ear mass tracking along CN7 canal Comment: Involvement of facial nerve canal rare with this lesion PATHOLOGY General Features Etiology P.VI(6):12 Benign congenital venous malformation arising out of sites of anastomoses between feeding arteries in temporal bone Staging, Grading, & Classification Classification for vascular lesions based on clinical, histopathological, & cytological features was introduced by Mulliken & Glowacki in 1982 Malformation term used for errors of vascular morphogenesis that develop in utero & persist postnatally Hemangioma term reserved for benign vascular tumors that arise by cellular hyperplasia Gross Pathologic & Surgical Features Richly vascular lesion without large feeding vessels Microscopic Features H&E: Nonencapsulated venous malformation composed of dilated vascular channels of varying sizes Widely ectatic vascular channels rimmed by thin smooth muscle coats without evident elastic laminae Flattened & mitotically quiescent endothelial cells Venous malformations = low-flow lesions Ossifying type: Lesion has spicules of lamellar bone When seen, called ossifying venous malformation Immunohistochemical markers critical to correct VM diagnosis Endothelial lining of vascular channels stain negatively for hemangioma-associated markers (GLUT1 & LeY antigen) Venous vs lymphatic malformation endothelial differentiation Podoplanin staining utilizing D2-40 antibody negative for endothelial cells confirms lack of lymphatic differentiation CLINICAL ISSUES Presentation Most common signs/symptoms Intratemporal FNVM produces peripheral CN7 paralysis early in its natural history Occurs early because of intimate relationship between CN7 & FNVM Onset of CN7 paralysis usually acute: May be slowly progressive or intermittent Caveat: May be described as “atypical Bell palsy!” IAC facial nerve venous malformation Sensorineural hearing loss may be more prominent symptom IAC lesion with CN7 symptoms, consider FNVM Other signs/symptoms Hemifacial spasm may progress to CN7 paralysis Demographics Age Wide range but usually adults Epidemiology Rare lesion 0.7% of all temporal bone lesions Slightly less common than CN7 schwannoma Natural History & Prognosis 1556 Diagnostic Imaging Head and Neck FNVM = slowly growing lesion Proportional growth is norm Disproportionate growth can occur secondary to infection, trauma, hormonal influences, or progressive hemodynamic forces Prognosis related to size at diagnosis, severity & duration of preoperative CN7 paralysis After surgery, full CN7 function rarely regained Treatment Surgery done as soon as possible Final facial nerve function depends on duration of preoperative CN7 deficit Surgical alternatives Middle cranial fossa (MCF) approach for lesions confined to geniculate fossa MCF-transmastoid approach for lesion of geniculate fossa & tympanic segment CN7 Small FNH are extraneural Resection with preservation of CN7 function = goal Even with small lesions, rarely achieved Larger FNH invade facial nerve Segmental facial nerve resection completed Followed by primary or cable graft repair of CN7 When necessary, yields poorer outcome DIAGNOSTIC CHECKLIST Consider FNVM presents with CN7 dysfunction when small Since early removal is best chance at CN7 preservation, radiologist must make diagnosis of subtle lesions! Caveat: Small FNVM may be subtle on T1 C+ MR Use CT liberally in negative or equivocal MR Image Interpretation Pearls Poorly circumscribed, C+ lesion in geniculate fossa in setting of CN7 paralysis most likely FNVM SELECTED REFERENCES Benoit MM et al: Facial nerve hemangiomas: vascular tumors or malformations? Otolaryngol Head Neck Surg 142(1):108-14, 2010 Greene AK et al: Intraosseous “hemangiomas” are malformations and not tumors Plast Reconstr Surg 119(6):194950; author reply 1950, 2007 Isaacson B et al: Hemangiomas of the geniculate ganglion Otol Neurotol 26(4):796-802, 2005 Piccirillo E et al: Management of temporal bone hemangiomas Ann Otol Rhinol Laryngol 113(6):431-7, 2004 Friedman O et al: Temporal bone hemangiomas involving the facial nerve Otol Neurotol 23(5):760-6, 2002 Salib RJ et al: The crucial role of imaging in detection of facial nerve haemangiomas J Laryngol Otol 115(6):510-3, 2001 Shelton C et al: Intratemporal facial nerve hemangiomas Otolaryngol Head Neck Surg 104(1):116-21, 1991 Curtin HD et al: “Ossifying” hemangiomas of the temporal bone: evaluation with CT Radiology 164(3):831-5, 1987 Mulliken JB et al: Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics Plast Reconstr Surg 69(3):412-22, 1982 P.VI(6):13 Image Gallery 1557 Diagnostic Imaging Head and Neck (Left) Axial bone CT in a patient with right facial nerve palsy shows a small FNVM in the geniculate fossa Notice the punctate ossific foci within the lesion This finding allows differentiation of FNVM from facial nerve schwannoma, which also occurs most frequently in the geniculate fossa (Right) Axial T1WI C+ MR with fat saturation in the same patient reveals FNVM enhancing in the geniculate ganglion The punctate ossific area is seen as an intralesional low signal focus (Left) Axial bone CT through the right temporal bone demonstrates a medium-sized FNVM in the geniculate fossa with extension along the anteromedial surface of the temporal bone The crescentic shape of this lesion arching around the cochlea medially on anterior temporal bone surface is typical of FNVM (Right) Axial T1WI C+ MR in the same patient shows diffuse FNVM enhancement in the geniculate fossa , arching around the cochlea along the anteromedial temporal bone surface 1558 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows a FNVM within the anteromedial temporal bone and in the bone surrounding the geniculate fossa Subtle foci of increased density are also seen in the IAC (Right) Axial T1WI C+ fat-saturated MR in the same patient shows the venous malformation enhancing in anteromedial temporal bone , around geniculate ganglion , and in IAC IAC lobe of FNVM occurs due to extension along the labyrinthine segment of CN7 (not shown) T-Bone Facial Nerve Schwannoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Intratemporal Facial Nerve > Benign and Malignant Tumors > T-Bone Facial Nerve Schwannoma T-Bone Facial Nerve Schwannoma H Ric Harnsberger, MD Key Facts Terminology FNS: Rare benign tumor of Schwann cells that invests intratemporal facial nerve (CN7) Imaging T-bone CT: Tubular mass spanning multiple intratemporal CN7 segments with smooth enlargement of bony CN7 canal > 90% FNS span ≥ intratemporal CN7 segments T1 C+ MR: Homogeneously enhancing tubular mass ± intramural cysts T-bone CT appearance dictated by specific location Geniculate fossa FNS: Ovoid smooth enlargement of geniculate fossa with projections into labyrinthine ± anterior tympanic segments of CN7 Tympanic segment FNS: Pedunculated FNS emanates from tympanic CN7 into middle ear Mastoid segment FNS: Either tubular with sharp margins or globular with irregular margins (breaks into mastoid air cells) GSPN schwannoma: Enlargement of GSPN canal; middle cranial fossa mass Top Differential Diagnoses Normal intratemporal facial nerve enhancement Bell palsy (herpetic facial paralysis) Intratemporal facial nerve venous malformation Intratemporal CN7 perineural malignancy Clinical Issues Symptoms: Hearing loss (70%), CN7 paresis (50%) Treatment options Conservative: Observation Surgical treatment: Complete removal is goal Radiotherapy: Early evidence suggests this may be viable treatment option 1559 Diagnostic Imaging Head and Neck (Left) Axial graphic shows a tubular facial nerve schwannoma involving the labyrinthine segment, geniculate ganglion , and anterior tympanic segment of the intratemporal facial nerve (Right) Axial bone CT in a patient with CN7 paresis shows tubular enlargement of the distal labyrinthine segment , geniculate fossa , & anterior tympanic segment of the CN7 canal Involvement of multiple segments of the facial nerve, as in this case, is highly suggestive of facial nerve schwannoma (Left) Coronal bone CT in the same patient reveals the facial nerve schwannoma involving the mid-tympanic segment of the facial nerve Notice the facial nerve bony canal “opens” into the middle ear mass (Right) Coronal bone CT in the same patient demonstrates that the facial nerve schwannoma also involves the mastoid CN7 , exiting the enlarged stylomastoid foramen inferiorly The tumor has broken into adjacent air cells on its lateral margin P.VI(6):15 TERMINOLOGY Abbreviations Facial nerve schwannoma (FNS) Synonyms Facial neuroma, facial neurilemmoma Definitions FNS: Rare benign tumor of Schwann cells that invests intratemporal facial nerve (CN7) IMAGING General Features Best diagnostic clue 1560 Diagnostic Imaging Head and Neck T-bone CT: Tubular mass spanning multiple intratemporal CN7 segments with smooth enlargement of bony CN7 canal T1 C+ MR: Homogeneously enhancing tubular mass ± intramural cysts Location Most common location: Geniculate ganglion > 90% FNS span ≥ intratemporal CN7 segments Size Often long (multiple centimeters) Cross-sectional measurement usually < cm Morphology Location dependent Geniculate fossa: Ovoid or triangular Greater superficial petrosal nerve (GSPN): Ovoid, projects into middle cranial fossa Tympanic CN7: Lobulates into middle ear Mastoid CN7: Irregular margin if breaks into surrounding air cells Tubular shape along multiple CN7 segments CT Findings CECT No role for CECT in this diagnosis Use enhanced MR instead Bone CT General T-bone CT appearances Tubular enlargement of CN7 canal Bony margins are smooth, “benign-appearing” T-bone CT appearance is dictated by specific location of FNS along CN7 Geniculate fossa FNS: Ovoid smooth enlargement of geniculate fossa Tumor projects into labyrinthine ± anterior tympanic segments of CN7 Tympanic segment FNS: Pedunculated FNS emanates from tympanic segment of CN7 into middle ear cavity Mastoid segment FNS: Either tubular with sharp margins or globular with irregular margins Shape depends on whether FNS breaks into surrounding mastoid air cells GSPN schwannoma: Enlargement of GSPN canal anteromedial to geniculate fossa MR Findings T1WI Intermediate to low signal lesion T2WI High signal lesion T1WI C+ Geniculate ganglion FNS: Ovoid, enhancing mass in enlarged geniculate fossa Tumor tails project into labyrinthine ± anterior tympanic segments of CN7 Tympanic segment FNS: Pedunculates into middle ear cavity Mastoid segment FNS Either tubular with sharp margins or globular with irregular margins Depends on whether it breaks into surrounding mastoid air cells GSPN schwannoma Diagnosed when enhancing mass is seen in location of GSPN Just anteromedial to geniculate fossa Middle cranial fossa enhancing mass with connection to geniculate fossa May be difficult to establish extraaxial nature of this schwannoma Imaging Recommendations Best imaging tool Patient presents with hearing loss ± CN7 paresis Start with thin section T1 C+ fat-saturated MR in axial & coronal plane through IAC & T-bone If intratemporal, tubular enhancing mass diagnosed on MR, T-bone CT helps delineate nature of lesion based on bone changes DIFFERENTIAL DIAGNOSIS Normal Intratemporal Facial Nerve Enhancement Clinical: Asymptomatic T-bone CT: Intratemporal CN7 canal normal 1561 Diagnostic Imaging Head and Neck T1 C+ MR: Geniculate ganglion, anterior tympanic ± mastoid segments normally enhance Labyrinthine CN7 does not normally enhance Bell Palsy (Herpetic Facial Paralysis) Clinical: Sudden onset of peripheral CN7 paralysis T-bone CT: Normal intratemporal CN7 canal T1 C+ MR: Intratemporal + IAC fundal CN7 C+ Intratemporal Facial Nerve Venous Malformation Clinical: Sudden unilateral peripheral CN7 paralysis T-bone CT: Intratumoral “honeycomb” or bone spicules T1 C+ MR: Poorly circumscribed, geniculate fossa enhancing mass Intratemporal CN7 Perineural Malignancy Clinical: Known or recurrent parotid malignancy T-bone CT: Mastoid CN7 canal enlarged T1 C+ MR: Infiltrating parotid mass is present PATHOLOGY General Features Etiology Slowly growing, benign tumor from Schwann cells investing intratemporal CN7 Genetics P.VI(6):16 If multiple schwannomas ± meningiomas, think NF2 Associated abnormalities NF2: Bilateral vestibular schwannomas; other schwannoma & meningioma possible Gross Pathologic & Surgical Features Tan, ovoid-tubular, encapsulated mass Arises from outer nerve sheath layer of CN7, expanding eccentrically away from nerve Microscopic Features Benign encapsulated tumor made up of bundles of spindle-shaped Schwann cells forming whorled pattern Cellular architecture consists of densely cellular (Antoni A) areas ± loose, myxomatous (Antoni B) areas May display intramural cystic change CLINICAL ISSUES Presentation Most common signs/symptoms Hearing loss present in ˜ 70% Facial nerve symptoms in ˜ 50% CN7 weakness or paralysis > involuntary facial movements Bell palsy-like CN7 paralysis rare Ear ± facial pain Other signs/symptoms CPA-IAC FNS: Sensorineural hearing loss, vertigo & tinnitus Larger tympanic & mastoid segments FNS Avascular retrotympanic mass Conductive hearing loss Demographics Age Mean age at presentation = 50 years Epidemiology FNS is rare tumor (< 1% of intrapetrous tumors) Within T-bone > > CPA-IAC > intraparotid Natural History & Prognosis Slow-growing benign tumor Eventually enlarges sufficiently to cause hearing loss & other cranial neuropathy Some tumors (< 10%) not grow or become symptomatic Treatment Conservative management If CN7 paralysis absent or mild when diagnosed, surgical cure can be worse than disease! 1562 Diagnostic Imaging Head and Neck Incomplete recovery of full CN7 function may occur despite surgical restoration of CN7 continuity Follow until CN7 paralysis develops Treatment used in elderly patients Surgical treatment Goal = complete FNS removal with preservation of hearing & CN7 function restoration Size-specific surgical techniques Large FNS: Remove tumor + CN7 cable graft Small FNS (< cm): CN7 transposition with primary anastomosis Location-specific surgery Labyrinthine or geniculate FNS: Middle cranial fossa & transmastoid approaches combined Tympanic-mastoid FNS: Transmastoid alone Radiotherapy Early evidence suggests stereotactic radiotherapy may be alternative to surgery Surgery then reserved for radiotherapy failures Large series needed to confirm this therapy option DIAGNOSTIC CHECKLIST Consider Older patients with FNS often followed, not operated Younger patients without CN7 paresis often followed Image Interpretation Pearls Intratemporal FNS: Segmental, tubular enlargement of CN7 canal Distinctive imaging findings depending on segment of CN7 involved CPA-IAC FNS: Exactly mimics vestibular schwannoma if no extension into labyrinthine segment CN7 occurs If present, labyrinthine segment “tail” makes imaging diagnosis Intraparotid FNS: Tubular mass in parotid coursing lateral to retromandibular vein If present, mastoid segment “tail” suggests diagnosis Differentiate from perineural parotid malignancy SELECTED REFERENCES Chao WC et al: Facial nerve schwannoma Otolaryngol Head Neck Surg 141(1):146-7, 2009 Madhok R et al: Gamma knife radiosurgery for facial schwannomas Neurosurgery 64(6):1102-5; discussion 1105, 2009 Nishioka K et al: Stereotactic radiotherapy for intracranial nonacoustic schwannomas including facial nerve schwannoma Int J Radiat Oncol Biol Phys 75(5):1415-9, 2009 Thompson AL et al: Magnetic resonance imaging of facial nerve schwannoma Laryngoscope 119(12):2428-36, 2009 McMonagle B et al: Facial schwannoma: results of a large case series and review J Laryngol Otol 122(11):1139-50, 2008 Lee JD et al: Management of facial nerve schwannoma in patients with favorable facial function Laryngoscope 117(6):1063-8, 2007 Wiggins RH 3rd et al: The many faces of facial nerve schwannoma AJNR Am J Neuroradiol 27(3):694-9, 2006 Kim CS et al: Management of intratemporal facial nerve schwannoma Otol Neurotol 24(2):312-6, 2003 Liu R et al: Facial nerve schwannoma: surgical excision versus conservative management Ann Otol Rhinol Laryngol 110(11):1025-9, 2001 10 Salzman KL et al: Dumbbell schwannomas of the internal auditory canal AJNR Am J Neuroradiol 22(7):1368-76, 2001 11 Zhang Q et al: Outgrowing schwannomas arising from tympanic segments of the facial nerve Am J Otolaryngol 17(5):311-5, 1996 12 Martin N et al: Facial nerve neuromas: MR imaging Report of four cases Neuroradiology 34(1):62-7, 1992 13 Inoue Y et al: Facial nerve neuromas: CT findings J Comput Assist Tomogr 11(6):942-7, 1987 P.VI(6):17 Image Gallery 1563 Diagnostic Imaging Head and Neck (Left) Axial bone CT reveals an enlarged geniculate fossa mass with the tumor extending along the anterior tympanic CN7 , displacing the ossicles laterally The otic capsule lateral surface is thinned by the FNS (Right) Axial T1WI C+ fat-saturated MR in the same patient shows the enhancing FNS centered in the geniculate ganglion The tumor extends along CN7 tympanic segment as well as into the IAC via the labyrinthine segment of CN7 Note medial intramural cyst (Left) Axial bone CT in a patient with an EAC polyp shows an irregular mass centered in the area of the mastoid segment of CN7 that appears contiguous (Right) Axial T1WI C+ FS MR in the same patient reveals the enhancing FNS in the CN7 mastoid segment , projecting through a bony dehiscence into the external auditory canal 1564 Diagnostic Imaging Head and Neck (Left) Coronal T1WI C+ FS MR in a patient with conductive hearing loss & facial twitching shows a multilobular enhancing FNS that has broken into mastoid air cells & projects inferiorly along the mastoid CN7 segment (Right) Axial T1 C+ MR shows an enhancing mass projecting into the medial middle cranial fossa from the greater superficial petrosal nerve FNS diagnosis is suggested if the projections along the tympanic CN7 & along the labyrinthine CN7 into the IAC are seen T-Bone Perineural Parotid Malignancy > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Intratemporal Facial Nerve > Benign and Malignant Tumors > T-Bone Perineural Parotid Malignancy T-Bone Perineural Parotid Malignancy Hilda E Stambuk, MD Key Facts Terminology Perineural tumor (PNT) on CN7 in T-bone: Form of local extension of malignant tumor along course of intratemporal CN7 Imaging Best clue: Poorly circumscribed, enhancing, tubular lesion extending from intraparotid tumor extending through SMF to involve at least mastoid CN7 segment CN7 PNT can extend proximally to CPA Contiguous spread or “skip lesions” along CN7 T-bone CT findings Mastoid CN7 canal may be slightly enlarged Adjacent air cell opacification MR findings Loss of SMF fat best seen on axial T1 MR Axial images best delineate tympanic, geniculate ganglion, & labyrinthine CN7 PNT Coronal and sagittal images through T-bone best show PNT extending through SMF into mastoid CN7 segment Top Differential Diagnoses Bell palsy T-bone CN7 venous malformation (hemangioma) T-bone CN7 schwannoma Transmodiolar cochlear nerve schwannoma Clinical Issues Asymptomatic (60%) Progressive peripheral facial nerve paresis or paralysis in adult Adenoid cystic carcinoma (ACCa) is most common parotid malignancy to show PNT along CN7 1565 Diagnostic Imaging Head and Neck (Left) Sagittal graphic depicts an intraparotid neoplasm spreading along CN7, through the stylomastoid foramen Note it travels superiorly on the mastoid segment of CN7 to posterior genu (Right) Coronal T1WI C+ MR shows parotid adenoid cystic carcinoma spreading along proximal extracranial CN7 through stylomastoid foramen , then up mastoid segment of CN7 (Left) Axial CECT shows infiltrating parotid adenoid cystic carcinoma with perineural spread along the auriculotemporal nerve Perineural spread along intraparotid CN7 is seen as round lesion just below stylomastoid foramen (Right) Axial CECT in the same patient demonstrates enlarged facial nerve from perineural tumor in the left stylomastoid foramen in this patient with primary parotid adenoid cystic carcinoma P.VI(6):19 TERMINOLOGY Abbreviations Perineural tumor (PNT) on intratemporal facial nerve (CN7) Synonyms Neurotropic spread on intratemporal facial nerve Definitions PNT on CN7 in T-bone: Form of local extension of malignant tumor along course of intratemporal CN7 IMAGING General Features Best diagnostic clue Poorly circumscribed, enhancing, invasive mass arising within parotid gland extending through stylomastoid foramen (SMF) to involve mastoid CN7 segment 1566 Diagnostic Imaging Head and Neck Location Malignant source of CN7 PNT most commonly arises in parotid PNT can extend as far along CN7 as root exit zone in cerebellopontine angle and nucleus in brainstem Contiguous spread or “skip lesions” along CN7 Size Cross-section size: Variable, must be larger than normal nerve Length: May be many centimeters in length Morphology Tubular enlargement of intratemporal CN7 most common CT Findings CECT Helpful in defining intraparotid malignancy Not helpful in defining intratemporal CN7 PNT unless CN7 very enlarged Bone CT Asymmetric widening of SMF & mastoid CN7 canal Adjacent mastoid air cells may show tumor invasion MR Findings T1WI Infiltrating parotid malignancy Loss of fat in “bell” of SMF Best seen on axial T1 MR images T2WI High-resolution thin section T2 images define IAC PNT if present Thickened CN7 in IAC fundus may connect to enlarged labyrinthine segment CN7 Involved intratemporal segment may show ↑ T2 signal T1WI C+ PNT may involve mastoid & tympanic segments of CN7, geniculate ganglion, & labyrinthine segment CN7 Enhancing, enlarged intratemporal CN7 is characteristic PNT may extend into IAC fundus as enhancing nodule Extracranial findings: Infiltrating parotid malignancy; tissue in stylomastoid foramen PNT along auriculotemporal nerve connects CN7 to CNV3 in masticator space Imaging Recommendations Best imaging tool Enhanced, multiplanar MR ± fat saturation Defines scope of intraparotid malignancy Best depicts intratemporal CN7 PNT Temporal bone CT best to evaluate osseous SMF & intratemporal CN7 canal Also helpful in evaluating subtle involvement of adjacent structures Adjacent middle ear & mastoid air cells Medial external auditory canal Protocol advice 3T magnet exaggerates artifact with fat-sat images and may render intratemporal CN7 uninterpretable DIFFERENTIAL DIAGNOSIS Bell Palsy Clinical: Abrupt onset peripheral FN paralysis (often overnight) Self-limiting process: Generally resolves in weeks Imaging: Entire intratemporal FN conspicuously enhances on T1 C+ MR T-Bone CN7 Venous Malformation (Hemangioma) Clinical: Facial nerve paralysis early in disease process Imaging: Infiltrating focal enhancing FN lesion in geniculate fossa on T1 C+ MR T-bone CT: 50% with “honeycomb bone” pattern T-Bone CN7 Schwannoma Clinical: Present most commonly with hearing loss, less commonly with FN paralysis Imaging: Tubular enhancing mass along course of intratemporal facial nerve on T1 C+ MR T-bone CT: Fusiform enlargement of intratemporal FN canal; most commonly at geniculate ganglion Transmodiolar Cochlear Nerve Schwannoma Clinical: Slowly progressive sensorineural hearing loss; FN paralysis not present Imaging: Dumbbell-shaped enhancing mass extending from cochlea through cochlear aperture into IAC fundus on T1 C+ MR 1567 Diagnostic Imaging Head and Neck PATHOLOGY General Features Etiology Any parotid malignancy may show PNT Neurotropic tumors Adenoid cystic carcinoma (ACCa) Squamous cell carcinoma (SCCa) Desmoplastic melanoma Associated abnormalities PNT can extend retrograde or antegrade PNT may be contiguous or show skip areas along CN7 P.VI(6):20 PNT on intratemporal CN7 can also occur from skin cancer (SCCa, melanoma) Direct extension along CN7 More commonly involves CN5, then spreads to CN7 along auriculotemporal nerve PNT can occur from direct invasion by 1° parotid malignancy (especially ACCa) Staging, Grading, & Classification Staging criteria: Salivary gland tumor with perineural tumor on facial nerve T4: Tumor invades CN7 Stage IV: T4, any nodes (N), any metastases (M) Gross Pathologic & Surgical Features PNT patterns with H&N cancers can occur early in disease process PNT allows spread over great distance without local invasion of adjacent structures or significant lymphadenopathy Microscopic Features Initially tumor grows along CN7 sheath; eventually invades nerve CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic (60%) Progressive peripheral CN7 paresis or paralysis Palpable parotid mass (not always) Other signs/symptoms Burning or stinging facial or ear pain Formication (sensation of ants crawling) Clinical profile Adult + parotid mass + ipsilateral CN7 paralysis Demographics Age 40-60 year olds Epidemiology ACCa is most common parotid malignancy to show PNT along CN7 SCCa is most common H&N malignancy showing PNT spread Others malignancy with PNT from parotid Primary or secondary (from skin) SCCa or melanoma Non-Hodgkin lymphoma Mucoepidermoid carcinoma Natural History & Prognosis Carcinomas with PNT usually have relentless progression CN7 invasion can lead to devastating physical deformity & dysfunction H&N neoplasms can exist within nerves for years without symptoms Especially true in low-grade ACCa Diagnosis is frequently delayed & outcome is poor once clinical manifestations arise 5-year overall survival: Poor Parotid ACCa is special case Recurrence & survival rates depend on specific tumor grade 65% overall 10-year survival rate 1568 Diagnostic Imaging Head and Neck Long-term (> 10 year) imaging follow-up is recommended given tendency of ACCa to recur late Treatment Treatment & prognosis altered by PNT Surgery combined with postoperative radiation therapy 1° radiation therapy with neutron or proton beams may be indicated for surgically unresectable tumors DIAGNOSTIC CHECKLIST Consider Imaging findings of PNT may be subtle Caveat: If radiologist does not think to search for PNT when suspected parotid malignancy is seen, diagnosis of PNT is usually missed Making observation of PNT on staging imaging critical to patient's chances of surgical cure Since PNT along CN7 is direct extension of tumor, must be resected at time of 1st surgery Image Interpretation Pearls If invasive parotid space lesion seen on imaging, radiologist must search for intratemporal PNT on CN7 If stylomastoid foramen fat invaded, dedicated T-bone CT & enhanced MR indicated to assess extent of PNT along CN7 Intratemporal CN7 must be abnormally enlarged & enhancing to recognize as PNT on imaging Remember that there may be radiologic “skip areas” along CN7 Visually interrogate entire CN7 into CPA cistern & brainstem SELECTED REFERENCES Gomez DR et al: Clinical and pathologic prognostic features in acinic cell carcinoma of the parotid gland Cancer 115(10):2128-37, 2009 Lee KJ et al: Determination of perineural invasion preoperatively on radiographic images Otolaryngol Head Neck Surg 139(2):275-80, 2008 Terhaard C et al: Facial nerve function in carcinoma of the parotid gland Eur J Cancer 2006 Nov;42(16):2744-50 Epub 2006 Sep Erratum in: Eur J Cancer 43(12):1883, 2007 Chang PC et al: Perineural spread of malignant melanoma of the head and neck: clinical and imaging features AJNR Am J Neuroradiol 25(1):5-11, 2004 Schmalfuss IM et al: Perineural tumor spread along the auriculotemporal nerve AJNR Am J Neuroradiol 23(2):30311, 2002 Fischbein NJ et al: MR imaging in two cases of subacute denervation change in the muscles of facial expression AJNR Am J Neuroradiol 22(5):880-4, 2001 Jungehuelsing M et al: Limitations of magnetic resonance imaging in the evaluation of perineural tumor spread causing facial nerve paralysis Arch Otolaryngol Head Neck Surg 126(4):506-10, 2000 Parker GD et al: Clinical-radiologic issues in perineural tumor spread of malignant diseases of the extracranial head and neck Radiographics 11(3):383-99, 1991 P.VI(6):21 Image Gallery (Left) Sagittal T1WI MR shows subtle diffuse enlargement and enhancement of the left intratemporal facial nerve 1569 Diagnostic Imaging Head and Neck from primary parotid acinic cell carcinoma noted adjacent to stylomastoid foramen (Right) Axial T1WI C+ MR in the same patient shows subtle asymmetric enlargement and enhancement of the mastoid segment of CN7 from left parotid acinic cell carcinoma (Left) Coronal T1WI C+ MR demonstrates primary parotid malignancy entering right stylomastoid foramen and extending along the mastoid segment of CN7 (Right) Coronal T1WI C+ MR in the same patient reveals a “skip lesion” of perineural tumor involving the right anterior tympanic and labyrinthine segments of CN7 The intervening tympanic segment (not shown) appeared normal, hence the term “skip lesion.” (Left) Coronal T1WI C+ MR shows a small primary parotid acinic cell carcinoma at the level of the stylomastoid foramen Notice the perineural tumor extending along the mastoid segment of CN7 to the posterior genu (Right) Coronal T1WI C+ MR in the same patient shows the perineural spread in the mid-tympanic CN7 and anterosuperior fundus of the internal auditory canal It is unusual for such a small parotid malignancy to have this amount of perineural tumor spread along CN7 Section - Temporal Bone, No Specific Anatomic Location T-Bone CSF Leak > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Temporal Bone, No Specific Anatomic Location > T-Bone CSF Leak T-Bone CSF Leak 1570 Diagnostic Imaging Head and Neck Patricia A Hudgins, MD Key Facts Terminology Cerebrospinal fluid (CSF) leak into ME cavity Leak of CSF either from congenital or acquired tegmen or IE defect Imaging Axial bone CT (≤ mm) + coronal reformats Coronal best shows with tegmen defect Bone CT findings Opacified ME-mastoid air cells Tegmen defect isolated or with cephalocele Possible associated findings: Fracture, previous surgery, arachnoid granulation, IE anomaly MR findings if suspect cephalocele T2 coronal: Meningocele (fluid-filled sac) or encephalocele (brain) Extends through tegmen defect into middle ear Imaging recommendations CT includes all paranasal sinuses & both T-bones CT-cisternogram usually not required if thin section CT with reformations performed Top Differential Diagnoses Rhinorrhea differential diagnosis Cribriform plate, ethmoid roof, sphenoid sinus walls intact on HRCT Otorrhea differential diagnosis Otitis media with TM perforation, otitis externa, external auditory canal (EAC) foreign body Clinical Issues Watery fluid leaking from nose or EAC Fluid positive for β2-transferrin = CSF protein Diagnostic Checklist Consider temporal bone as source of leak even if CSF dripping from nose (Left) Coronal bone CT of left ear in a patient with CSF leak shows tegmen tympani dehiscence & cephalocele projecting into middle ear behind the tympanic membrane High-resolution coronal T2 MR would determine type of cephalocele (Right) Coronal bone CT reveals comminuted post-traumatic tegmen fracture with bone fragments in epitympanum Some CSF leaks resolve spontaneously, but a defect this large will likely need surgery Only MR can characterize soft tissue/fluid filling middle ear 1571 Diagnostic Imaging Head and Neck (Left) Coronal bone CT in an 80 year old with spontaneous CSF leak shows areas of dehiscence on either side of arcuate eminence , lateral tegmen mastoideum dehiscence , & medial petrous apex roof dehiscence Underlying arachnoid granulations are most likely the cause (Right) Coronal T2WI FS MR in same patient reveals tegmen mastoideum dehiscence lateral to arcuate eminence is accompanied by an encephalocele involving a temporal lobe gyrus Note CSF high signal in mastoid air cells P.VI(7):3 TERMINOLOGY Synonyms CSF otorhinorrhea, fistula Definitions Leak of cerebrospinal fluid (CSF) either from congenital or acquired tegmen or inner ear (IE) defect Acquired tegmen tympani or mastoideum defect, resulting in leak of CSF into middle ear (ME) Congenital IE anomaly with incompetent oval window with CSF leak into ME cavity IMAGING General Features Best diagnostic clue Opacified ME cavity with bony defect in tegmen Location Tegmen tympani or mastoideum CT Findings Bone CT Opacified ME-mastoid from CSF Possible causal findings Previous T-bone surgery or fracture Arachnoid granulation (pit, osteodural defect) of tegmen or posterior wall Size of osseous defect in planes required for surgical repair Congenital IE dysplasia absent modiolus, incompetent oval window MR Findings T2WI Fluid-filled ME-mastoid complex with dehiscent tegmen ± cephalocele Meningocele (CSF) or encephalocele (brain) “Traction encephalomalacia” of adjacent brain from sag into bone defect common secondary finding T1WI C+ Thin dural enhancement at site of bone defect common even without infection/meningitis Enhancement of cephalocele lining also common but does not always imply infection Imaging Recommendations Best imaging tool High-resolution, noncontrast T-bone CT Protocol advice 1572 Diagnostic Imaging Head and Neck Axial MDCT (≤ mm); reformat coronals Include all paranasal sinuses & both T-bones as multiple defects occur, especially post trauma Heavily T2-weighted multiplanar sequences best show associated cephalocele Enhanced MR if cephalocele or meningitis suspected Rarely, CT or radionuclide cisternography if CT normal or multiple bone defects that could be source of leak DIFFERENTIAL DIAGNOSIS Rhinorrhea Vasomotor rhinitis, post-traumatic autonomic dysfunction may mimic CSF leak Cribriform plate, ethmoid roof, sphenoid sinus walls intact on bone CT Otorrhea Otitis media with TM perforation, otitis externa or external auditory canal foreign body may all mimic CSF leak PATHOLOGY General Features Etiology Traumatic: Most T-bone CSF leaks are traumatic (MVA, GSW) Postsurgical: Usually cholesteatoma resection with tegmen leak developing after surgery Other acquired: Arachnoid granulation of tegmen or posterior wall enlarges with ensuing CSF leak Congenital: IE dysplasia + incompetent oval window CLINICAL ISSUES Presentation Most common signs/symptoms Watery fluid leaking from nose or EAC Other signs/symptoms Laboratory tests for CSF: β2-transferrin = protein found in CSF, newer β trace protein test Reliable test; only few drops fluid needed Ascending meningitis less common now due to early recognition & imaging after trauma Demographics Epidemiology 2-9% of patients with head injury have CSF leak 30% of patients with skull base fracture Natural History & Prognosis Post-traumatic: Up to 85% resolve spontaneously within days; almost all within months Meningitis (up to 50% of persistent CSF fistulas) Treatment Bedrest, lumbar drain Middle fossa or mastoid approach for T-bone leaks DIAGNOSTIC CHECKLIST Consider T-bone as leak source even if CSF from nose ME CSF → eustachian tube → nasopharynx If β2-transferrin positive, find leak! Reporting Tips Size of bone defect and presence of cephalocele critical to report If patient infected from ascending meningitis check for empyema or abscess SELECTED REFERENCES Stenzel M et al: Cerebrospinal fluid leaks of temporal bone origin: etiology and management ORL J Otorhinolaryngol Relat Spec 67(1):51-5, 2005 T-Bone Arachnoid Granulations > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Temporal Bone, No Specific Anatomic Location > T-Bone Arachnoid Granulations T-Bone Arachnoid Granulations H Ric Harnsberger, MD Key Facts Terminology Temporal bone AG: Non-venous sinus-related (aberrant) pseudopodial pia-arachnoid projection into tegmen tympani or posterior wall of T-bone Imaging 1573 Diagnostic Imaging Head and Neck Bone CT findings Tubular to ovoid scalloped erosion in T-bone wall MR findings Nonenhancing low signal (T1 C+) High T2 signal lesion Location: Lateral 1/3 of posterior T-bone wall Between posterior semicircular canal & anterior margin of sigmoid sinus At axial level of crus communis Size variation of posterior wall AG Few millimeters to 2-3 centimeters (giant AG) Top Differential Diagnoses Endolymphatic sac tumor Large vestibular aqueduct (IP-II) Skull base dural AV fistula Pathology T-bone AG = form of aberrant AG Aberrant AG = AG that penetrates dura but fails to reach venous sinus CSF pulsations suspected to enlarge AG causing arachnoid pouch to bulge into T-bone Clinical Issues Incidental asymptomatic finding Rarely CSF leak associated ± meningitis Posterior wall AG prevalence ↑ with age On CT can see posterior wall AG in 2.5% patients (Left) Axial bone CT of the left ear in patient with right ear symptoms shows a medium-sized incidental arachnoid granulation in the medial mastoid wall projecting into the mastoid air cells Note proximity of sigmoid sinus and bony vestibular aqueduct (Right) Short axis oblique image of the left temporal bone reveals a small arachnoid granulation in the medial mastoid wall Note the lesion is on the cephalad margin of the sigmoid sinus 1574 Diagnostic Imaging Head and Neck (Left) Axial bone CT of the right T-bone in a patient with clinically obvious CSF leak demonstrates a giant AG eroding the medial mastoid wall The posterior semicircular canal appears to float in the AG The middle ear is full of fluid (CSF) (Right) T1WI C+ fat-saturated MR in the same patient reveals the giant archnoid granulation as a lobular fluid signal structure with subtle rim enhancement Middle ear fluid is low signal Note proximity of sigmoid sinus to the giant AG P.VI(7):5 TERMINOLOGY Abbreviations Arachnoid granulation (AG) Synonyms Aberrant AG, osteodural defects When large → giant AG Definitions AG: Non-venous sinus-related (aberrant) pseudopodial pia-arachnoid projection into tegmen tympani or posterior wall of T-bone IMAGING General Features Best diagnostic clue Bone CT: Tubular to ovoid scalloped lucency in T-bone wall MR: Nonenhancing low signal (T1 C+), high T2 signal lesion Location Tegmen tympani Lateral 1/3 of posterior T-bone wall Between posterior semicircular canal & anterior margin of sigmoid sinus At axial level of crus communis Size Tegmen tympani AG: Millimeters Posterior wall AG: Few millimeters to 2-3 centimeters (giant AG) CT Findings Bone CT Tegmen tympani AG Small size & variable ossification of tegmen makes difficult to see with CT Posterior wall AG Tubular or ovoid lucency in medial mastoid wall Mastoid cortex with focal erosion AG may project into medial mastoid air cells MR Findings T1WI C+ FS Lobular low (fluid) signal lesion of posterior mastoid wall 1575 Diagnostic Imaging Head and Neck No or subtle rim enhancement No nodular enhancement CISS or FIESTA High (fluid) signal lesion Imaging Recommendations Best imaging tool Bone CT best characterizes AG DIFFERENTIAL DIAGNOSIS Endolymphatic Sac Tumor Centered in fovea of endolymphatic sac, posterior wall T-bone Bone CT: Spiculated or coarse calcifications within tumor matrix Thin Ca++ along posterior margin MR: T1 high signal foci from trapped blood products Large Vestibular Aqueduct (IP-II) Bone CT: Enlarged bony vestibular aqueduct MR: Enlarged endolymphatic sac Dural AV Fistula, Skull Base Bone CT: Transosseous collaterals traverse posterior mastoid MR: Recanalized, irregular transverse-sigmoid sinus PATHOLOGY General Features Etiology Unknown why AG can occur without venous sinus communication May represent aborted attempt by AG to enter sigmoid sinus to resorb CSF T-bone AG = form of aberrant AG Defined as AG that penetrates dura but fails to reach venous sinus CSF pulsations suspected to enlarge AG causing arachnoid pouch to bulge into T-bone Rarely with arachnoid pouch enlargement, rupture results in CSF leak into mastoid T-bone Gross Pathologic & Surgical Features Osteodural defect with arachnoid pouch Microscopic Features Arachnoid villi with central core of loose connective tissue, peripheral zone of dense connective tissue CLINICAL ISSUES Presentation Most common signs/symptoms Incidental asymptomatic finding Other signs/symptoms Rarely CSF leak associated ± meningitis Demographics Epidemiology Tegmen tympani AG more common than posterior wall AG Posterior wall AG prevalence ↑ with age Can see posterior wall AG on CT in ˜ 2.5% patients Treatment None unless CSF leak CSF leak treatment Canal wall-up mastoidectomy with repair of dural defect with tissue graft SELECTED REFERENCES Lee MH et al: Prevalence and appearance of the posterior wall defects of the temporal bone caused by presumed arachnoid granulations and their clinical significance: CT findings AJNR Am J Neuroradiol 29(9):1704-7, 2008 VandeVyver V et al: Arachnoid granulations of the posterior temporal bone wall: imaging appearance and differential diagnosis AJNR Am J Neuroradiol 28(4):610-2, 2007 Gacek RR: Evaluation and management of temporal bone arachnoid granulations Arch Otolaryngol Head Neck Surg 118(3):327-32, 1992 T-Bone Fibrous Dysplasia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Temporal Bone, No Specific Anatomic Location > T-Bone Fibrous Dysplasia T-Bone Fibrous Dysplasia 1576 Diagnostic Imaging Head and Neck H Ric Harnsberger, MD Key Facts Terminology Congenital disorder with defect in osteoblastic differentiation & maturation, resulting in progressive replacement of normal cancellous bone by mixture of fibrous tissue & immature woven bone Imaging Bone CT shows expansile “ground-glass” bony matrix Expansile lesion centered in medullary space with variable attenuation Pagetoid (mixed) pattern (50%): Mixed radiopacity & radiolucency Sclerotic FD (25%): “Ground-glass” density Cystic FD (25%): Centrally lucent lesions with thinned but sclerotic borders T1 MR: Expansile lesion with ↓ signal T2 MR: ↓ signal in ossified ± fibrous areas T1 C+ FS MR: None, rim, or diffuse enhancement possible Top Differential Diagnoses T-bone Paget disease Skull base giant cell tumor T-bone meningioma T-bone metastasis Pathology Benign tumor-like lesion of bone with local arrest of normal structural/architectural development Clinical Issues Young affected (< 30 years old) Most spontaneously cease to grow by age 25 (Left) Axial bone CT reveals the common sclerotic variety of fibrous dysplasia involving the mastoid , inner ear and encroaching on the posterior middle ear FD expansion causes EAC stenosis Anterolaterally note previous biopsy site (Right) Coronal bone CT shows sclerotic FD that has expanded to occlude the EAC Clinically significant conductive hearing loss can be expected Otoscopy reveals finding similar to congenital EAC dysplasia 1577 , Diagnostic Imaging Head and Neck (Left) Axial bone CT reveals aggressive-appearing anterior left temporal bone foci of “cystic” fibrous dysplasia This lesion was initially biopsied in search of malignant tumor histopathology (Right) Axial bone CT shows polyostotic fibrous dysplasia affecting both temporal bones Multiple other foci are apparent, including the right occipital bone , clivus , sphenoid bone , and frontal bone P.VI(7):7 TERMINOLOGY Abbreviations Fibrous dysplasia (FD) Definitions Congenital disorder with defect in osteoblastic differentiation & maturation, resulting in progressive replacement of normal cancellous bone by mixture of fibrous tissue & immature woven bone IMAGING General Features Best diagnostic clue Bone CT shows expansile “ground-glass” bony matrix Location May affect any bone in body Size Localized or diffuse Lesions may reach many cm in size Morphology FD conforms to general shape of affected bone CT Findings Bone CT Expansile lesion centered in medullary space with variable attenuation Pagetoid (mixed) pattern (50%): Mixed radiopacity & radiolucency Sclerotic FD (25%): “Ground-glass” density Cystic FD (25%): Centrally lucent lesions with thinned but sclerotic borders MR Findings T1WI Expansile lesion with ↓ signal T2WI ↓ signal in ossified ± fibrous areas T1WI C+ None, rim, or diffuse enhancement possible Nuclear Medicine Findings Bone scan ↑ radionuclide accumulation on perfusion & delayed bone phase Nonspecific; sensitive to extent of skeletal lesions in polyostotic FD 1578 Diagnostic Imaging Head and Neck PET Can be variably hot on FDG PET Should not be mistaken for metastasis Imaging Recommendations Best imaging tool Bone CT best for most cases DIFFERENTIAL DIAGNOSIS T-Bone Paget Disease Presents in elderly “Cotton-wool” CT appearance Pagetoid ground-glass FD mimics Paget disease Involves T-bone & calvarium, not craniofacial area Skull Base Giant Cell Tumor May mimic sclerotic FD Hypointense on T2 MR (hemosiderin deposition) T-Bone Meningioma Intraosseous meningioma mimics FD En plaque soft tissue mass seen on MR T-Bone Metastasis Mixed sclerotic-destructive metastasis mimics FD Prostate & breast carcinoma most common PATHOLOGY General Features Etiology Benign tumor-like lesion of bone with local arrest of normal structural/architectural development Genetics Sporadic gene mutation of GNAS1 gene Microscopic Features FD lesion contains fibrous tissue with intramural bone trabeculae CLINICAL ISSUES Presentation Most common signs/symptoms Bulging of temporal area Stenosis of EAC with recurrent otitis Hearing loss: Conductive, sensorineural or mixed Demographics Age Active in young, typically quiescent after puberty Young affected (< 30 years old) Gender M:F = 1:3 Epidemiology Monostotic FD is 6x more common than polyostotic Natural History & Prognosis Monostotic craniofacial FD has excellent prognosis Most spontaneously cease to grow by age 25 Polyostotic FD rarely life threatening but has poorer prognosis Treatment Aggressive surgical management not recommended in most cases SELECTED REFERENCES Kim YH et al: Role of surgical management in temporal bone fibrous dysplasia Acta Otolaryngol 129(12):1374-9, 2009 Wang YC et al: Fibrous dysplasia of the temporal bone presenting as an external auditory canal mass Otolaryngol Head Neck Surg 141(5):655-6, 2009 Karino S et al: Fibrous dysplasia of the temporal bone: assessment by three-dimensional helical CT imaging Otolaryngol Head Neck Surg 133(4):643, 2005 Jee WH et al: Fibrous dysplasia: MR imaging characteristics with radiopathologic correlation AJR Am J Roentgenol 167(6):1523-7, 1996 1579 Diagnostic Imaging Head and Neck T-Bone Paget Disease > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Temporal Bone, No Specific Anatomic Location > T-Bone Paget Disease T-Bone Paget Disease H Ric Harnsberger, MD Key Facts Terminology Paget disease (PD) definition: Bone dysplasia characterized by excessive remodeling of bone, resulting from alternating waves of osteoclastic & osteoblastic activity Imaging Location of involvement of PD Calvarium > cranial base > temporal bone Bone CT Calvarium & cranial base: Diffuse thickening with mixed density bone T-bone: Sclerotic & erosive bone change affecting all areas, including otic capsule when advanced External auditory canal: Tortuosity & stenosis Middle ear: Middle ear cavity constriction; ossicles & ligaments with Pagetoid changes Inner ear/otic capsule: Otic capsule demineralization (peripheral to central) involves all layers Internal auditory canal: Enlarging bone narrows IAC and compresses CN7 & CN8 MR: Diminished T1 signal of enlarged bones Top Differential Diagnoses T-bone osteoradionecrosis T-bone fibrous dysplasia Otosclerosis Clinical Issues Progressive bilateral mixed hearing loss → deafness Conductive: Ossicles & ligaments affected Sensorineural: Otic capsule erosions; IAC compression > 40 years of age (Left) Axial right ear temporal bone CT shows Paget disease causing diffusely thickened bones of the clivus, petrous apex, and bones around the middle and inner ear Notice the thickened ligament connected to the malleus and the erosion of the otic capsule (Right) Coronal bone CT in the opposite ear in the same patient reveals diffuse bony enlargement of all bones of the skull base and temporal bone Erosive changes of the otic capsule and thickening of the ossicles are evident 1580 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows diffuse enlarged bones of the skull base with “cotton wool” appearance The petrous apices are enlarged but demineralized, which indicates earlier, more active disease is present The anteromedial otic capsules are eroded (Right) Axial bone CT of right ear in a patient with hearing loss shows malleal ligament ossification as well as subacute erosive phase of Paget disease affecting otic capsule Stapedectomy with stapes prosthesis had been performed P.VI(7):9 TERMINOLOGY Abbreviations Paget disease (PD) Synonyms Osteitis deformans Definitions Bone dysplasia characterized by excessive remodeling of bone, resulting from alternating waves of osteoclastic & osteoblastic activity IMAGING General Features Best diagnostic clue Bone CT Calvarium & cranial base: Diffuse thickening with mixed density bone T-bone: Sclerotic & erosive bone change affecting all areas Location Calvarium > cranial base > temporal bone Spine, pelvis, & long bones 1st affected CT Findings Bone CT External auditory canal (EAC) & middle ear EAC tortuosity & stenosis Middle ear cavity constriction Ossicles & ligaments with Pagetoid changes Inner ear/otic capsule Otic capsule demineralization (peripheral to central) involves all layers Periosteum → endochondral → endosteum Internal auditory canal (IAC) Enlarging bone narrows IAC Skull base & calvarium Diffuse inhomogeneous thickening of cranial base & calvarium MR Findings T1WI Diminished T1 signal 1581 Diagnostic Imaging Head and Neck Marrow replacement by fibrous tissue Heterogeneous patchy T1 hyperintense signal Areas of hemorrhage & slow flow in vascular channels T1WI C+ Heterogeneous enhancement within thickened calvarium, skull base ± T-bone possible Secondary to hypervascular nature Meningeal enhancement has also been reported May reflect ↑ metabolism & blood flow Imaging Recommendations Best imaging tool T-bone CT only study needed to make diagnosis DIFFERENTIAL DIAGNOSIS T-Bone Osteoradionecrosis CT: Unilateral demineralization similar to acute PD Not thickened or diffuse like PD T-Bone Fibrous Dysplasia CT: Increased bone volume Commonly involves facial bones Otosclerosis CT: Multifocal otic capsule demineralization Usually bilateral, symmetric Adjacent skull base & calvarium normal PATHOLOGY General Features Etiology Unknown; nuclear viral inclusions suggest viral etiology Progressive osteodystrophy with monostotic & polyostotic varieties Genetics Mostly sporadic 15% autosomal dominant inheritance pattern Defects in chromosome & 18q implicated Associated abnormalities Characteristic involvement of vertebrae, pelvis, & long bones In T-bone, marrow-containing structures are involved 1st Petrous apex undergoes initial changes Demineralization of otic capsule & encroachment upon middle ear structures occur late CLINICAL ISSUES Presentation Most common signs/symptoms Mixed hearing loss Other signs/symptoms Tinnitus (intraosseous arteriovenous shunts) Vertigo, hemifacial spasm, trigeminal neuralgia Laboratory abnormalities ↑ serum alkaline phosphatase ↑ urinary hydroxyproline Demographics Age > 40 years of age Gender M:F = 4:1 Natural History & Prognosis Disorder usually progressive despite therapy Progressive bilateral mixed hearing loss → deafness Treatment Calcitonin, diphosphonates, mithramycin SELECTED REFERENCES Bahmad F Jr et al: Paget disease of the temporal bone Otol Neurotol 28(8):1157-8, 2007 1582 Diagnostic Imaging Head and Neck Teufert KB et al: Paget disease and sensorineural hearing loss associated with spiral ligament degeneration Otol Neurotol 26(3):387-91; discussion 391, 2005 Tehranzadeh J et al: Computed tomography of Paget disease of the skull versus fibrous dysplasia Skeletal Radiol 27(12):664-72, 1998 T-Bone Langerhans Cell Histiocytosis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Temporal Bone, No Specific Anatomic Location > T-Bone Langerhans Cell Histiocytosis T-Bone Langerhans Cell Histiocytosis Richard H Wiggins, III, MD Key Facts Terminology Langerhans cell histiocytosis (LCH) Histiocytosis X, eosinophilic granuloma (EG), Hand-Schüller-Christian syndrome (HSCD), Letterer-Siwe disease (LSD) Disorder with proliferation of Langerhans type histiocytes, which form granulomas within T-bone & surrounding soft tissues Imaging Well-defined lytic lesions of T-bone with associated enhancing soft tissue masses Small “punched out” to diffuse bone involvement Mastoid portion > petrous apex Both contrast-enhanced CT and MR are often performed for complicated T-bone lesions Bone CT best for evaluation of osseous structures MR best for LCH soft tissue evaluation Pathology Poorly understood pathology with histiocyte proliferation and infiltration Old classification system: groups Eosinophilic granuloma (EG) Hand-Schüller-Christian disease (HSCD) Letterer-Siwe disease (LSD) New classification system based on risk factors Multifocal involvement, young age, multiorgan dysfunction, disease relapse Clinical Issues Otologic symptoms in 25% of T-bone LCH cases Conductive hearing loss ± otorrhea T-bone LCH presents in 1st decade of life Other symptoms: Otalgia, vertigo, otitis media ± externa, postauricular soft tissue swelling, CN7 palsy, sensorineural hearing loss, aural polyp (Left) Typical temporal bone CT of Langerhans cell histiocytosis shows opacification of the left mastoid air cells with osseous destruction of the mastoid septations This appearance is not specific for LCH (Right) Axial CECT through the right temporal bone shows a soft tissue destructive lesion with an aggressive appearance involving the external 1583 Diagnostic Imaging Head and Neck ear , middle ear , mastoid , and petrous apex , found to be Langerhans cell histiocytosis (Left) Axial T1WI C+ FS MR in a 2-year-old boy shows multifocal enhancing lesions in the pre- and postseptal right orbit , the right sphenoid wing , and bilateral temporal bones , typical of LCH (Right) Axial CECT demonstrates a variant adult case of multifocal Langerhans histiocytosis of the skull base, with an extensive mass characterized by relatively homogeneous enhancement and bone destruction involving the right temporal bone and skull base P.VI(7):11 TERMINOLOGY Abbreviations Langerhans cell histiocytosis (LCH) Synonyms Histiocytosis X, eosinophilic granuloma (EG), Hand-Schüller-Christian syndrome (HSCD), Letterer-Siwe disease (LSD) Definitions Proliferation of Langerhans type histiocytes form granulomas within T-bone ± surrounding soft tissues IMAGING General Features Best diagnostic clue Well-defined lytic bone lesion usually with enhancing soft tissue mass CT Findings Bone CT Variable lytic “punched out” lesions Usually geographic osseous destruction of mastoid portion of T-bone May involve petrous apex, otic capsule ± ossicles Usually beveled margins of lytic lesions More common in calvarium May also have sclerosis (more common appearance of skull base lesions) May have diffuse temporal bone osseous destruction MR Findings T1WI Marrow replacement process of T-bone Hypointense or isointense to muscle T-bone lesion ± soft tissue component ± ↑ T1 signal (lipid-laden macrophages) ± blood products within soft tissue mass T2WI Iso- to hyperintense soft tissue mass T1WI C+ FS Avid heterogeneous soft tissue enhancement Well-defined or poorly defined margins ± intracranial spread with dural enhancement 1584 Diagnostic Imaging Head and Neck Imaging Recommendations Best imaging tool Contrast-enhanced CT ± MR Bone CT best for evaluation of bone MR best for evaluation of soft tissue & intracranial spread DIFFERENTIAL DIAGNOSIS Coalescent Otomastoiditis Acute infection of middle ear and mastoid air cells Progressive resorption of mastoid osseous septae T-Bone Rhabdomyosarcoma Soft tissue sarcoma from primitive mesenchymal cells committed to skeletal muscle differentiation (rhabdomyoblasts) Invasive heterogeneous soft tissue mass in child with aggressive osseous destruction T-Bone Fibrous Dysplasia “Ground-glass” osseous expansion of T-bone or lytic expansile lesion PATHOLOGY General Features Etiology Poorly understood pathology with histiocyte proliferation and infiltration Neoplastic or inflammatory May be secondary to reactive immunostimulation Increased risk of LCH with family history of thyroid disease, solvent exposure, penicillin history, nonimmunization Associated abnormalities Hypothalamic-pituitary disease Infratentorial abnormalities common Microscopic Features Langerhans cell is histiocyte-like cell with folded nucleus Eosinophils, plasma cells common EM shows Birbeck granules, & elongated tennis-racket-shaped cytoplasmic inclusion CLINICAL ISSUES Presentation Most common signs/symptoms Conductive hearing loss ± otorrhea Other signs/symptoms Otalgia, vertigo, otitis media ± externa, postauricular soft tissue swelling, CN7 palsy, sensorineural hearing loss, aural polyp Demographics Age T-bone LCH presents in 1st decade of life Gender M:F = 2:1 Epidemiology 70% have involvement of head & neck Bilateral disease in 30% of cases Bone lesions most common manifestation of disease 80-95% of children with LCH Natural History & Prognosis 90% cure rate for unifocal disease of T-bone Multifocal & systemic LCH: Mortality up to 18% Treatment Depends on symptoms, locations & extent of disease SELECTED REFERENCES Roger G et al: Cholesteatoma secondary to temporal bone involvement by Langerhans cell histiocytosis: a complication amenable to curative surgery Otol Neurotol 30(2):190-3, 2009 Saliba I et al: Langerhans' cell histiocytosis of the temporal bone in children Int J Pediatr Otorhinolaryngol 72(6):775-86, 2008 1585 Diagnostic Imaging Head and Neck T-Bone Metastasis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Temporal Bone, No Specific Anatomic Location > T-Bone Metastasis T-Bone Metastasis Hilda E Stambuk, MD Key Facts Terminology Hematogenous spread from distant primary neoplasm Rarely leptomeningeal spread from IAC Imaging Petrous apex most common site Commonly have other bone metastases Bone CT findings Focal lytic or permeative, rarely blastic lesion Subtle appearance in pneumatized portions T-bone Enhances significantly in most cases CT differentiates benign lesions (fibrous dysplasia, osteoma) MR findings T1: Lesion hypointense to normal fatty marrow T1 fat-saturated C+: Delineates tumor vs normal fatty marrow Top Differential Diagnoses Confluent apical petrositis PA cholesterol granuloma T-bone Langerhans cell histiocytosis T-bone plasmacytoma Clinical Issues Often asymptomatic Hearing loss if any symptoms CN palsy (CN8 > CN7 > CN5 or CN6) Breast > lung > renal > prostate cancer origin Diagnostic Checklist Remember background PA asymmetric marrow common when reviewing area for metastases Isolated T-bone lesion less likely to be metastasis Look for dural, dural sinus, and brain invasion (Left) Expansile osseous breast metastasis involving the left petrous apex , lateral clivus, & horizontal segment of the left carotid canal This common location for T-bone metastasis puts CN5 and at risk for paralysis (Right) Osseous metastasis to the left T-bone mastoid segment, with cortical destruction of the inner cortex/sigmoid plate , puts the sigmoid sinus at risk for invasion/thrombosis Smaller metastases are easily missed secondary to aerated/varied appearance of the T-bone 1586 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR shows typical appearance of right petrous apex metastasis replacing normal fatty “white” marrow with expansion into right Meckel cave in a patient with new right facial numbness Note normal marrow signal in left petrous apex (Right) Normal CSF signal in right Meckel cave is replaced by dark signal metastatic tumor in left Meckel cave secondary to left petrous apex metastasis also involving the left cavernous sinus T2 easily confirms involvement of Meckel cave P.VI(7):13 TERMINOLOGY Definitions Hematogenous spread to temporal bone from distant primary neoplasm Rarely leptomeningeal spread from IAC IMAGING General Features Best diagnostic clue Bone CT shows focal destructive lesion of temporal bone (T-bone) Location Petrous apex (PA) most commonly Size Variable, 2-8 centimeters Morphology Infiltrating margins CT Findings CECT Enhances significantly in most cases Bone CT Lytic or permeative, rarely blastic lesion Commonly have other bone metastases T-bone cortex is destroyed Subtle appearance in pneumatized portions T-bone MR Findings T1WI Nonspecific, low-intermediate signal Lower signal metastasis easily distinguished from adjacent normal adult fatty marrow T2WI Nonspecific, may be hyperintense or hypointense Depends upon cellularity of primary lesion T1WI C+ Variable enhancement; may blend with normal fatty marrow Fat saturation to exclude normal fatty marrow ± reactive dural enhancement/transdural tumor extension 1587 Diagnostic Imaging Head and Neck Nuclear Medicine Findings Bone scan Abnormal nonspecific ↑ radiotracer Associated with other bony metastases PET Positive in T-bone, other bones, and primary Imaging Recommendations Best imaging tool Both CT & MR helpful CT differentiates benign lesions (fibrous dysplasia, osteoma) Protocol advice T1 MR: Lesion hypointense to normal fatty marrow Fat saturation: Delineates tumor vs normal fatty marrow DIFFERENTIAL DIAGNOSIS Confluent Apical Petrositis Clinical: Infectious symptoms Imaging: Destructive lesion of PA + meningeal thickening PA Cholesterol Granuloma Clinical: History of chronic otitis media Imaging: Expansile PA lesion; T1 high signal T-Bone Langerhans Cell Histiocytosis Clinical: Pediatric patient Imaging: Destructive mastoid/middle ear lesion > PA T-Bone Plasmacytoma Clinical: Often with multiple myeloma Imaging: Destructive PA lesion PATHOLOGY General Features Etiology Marrow-filled PA may predispose to metastases Must exclude direct extension from local primary (NP, parotid, maxillary sinus, external ear) CLINICAL ISSUES Presentation Most common signs/symptoms Asymptomatic Hearing loss most common symptom Other signs/symptoms CN palsy (CN8 > CN7 > CN5 or CN6) Demographics Age 51-60 years: Most common age of onset of primary cancers Epidemiology Breast > lung > renal > prostate Ca origin Natural History & Prognosis Poor, depends on primary tumor type Treatment Palliative, depends on primary tumor type DIAGNOSTIC CHECKLIST Image Interpretation Pearls Remember background PA asymmetric marrow common when reviewing area for metastases Isolated T-bone lesion less likely to be metastasis Reporting Tips Look for dural, dural sinus, and brain invasion SELECTED REFERENCES Gloria-Cruz TI et al: Metastases to temporal bones from primary nonsystemic malignant neoplasms Arch Otolaryngol Head Neck Surg 126(2):209-14, 2000 1588 Diagnostic Imaging Head and Neck T-Bone Osteoradionecrosis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - Temporal Bone, No Specific Anatomic Location > T-Bone Osteoradionecrosis T-Bone Osteoradionecrosis Hilda E Stambuk, MD Key Facts Terminology Radiation-induced injury to temporal bone Imaging Bone CT findings “Moth-eaten” destruction of temporal bone & adjacent skull base ± sequestrum T2 MR findings High signal mucosal injury of EAC, MEC, mastoid High signal of adjacent brain → radiation necrosis Complications: Meningitis, abscess, dural sinus thrombosis Top Differential Diagnoses Malignant external otitis Coalescent mastoiditis Aggressive cholesteatoma Paget disease Pathology Avascular bone necrosis from obliterative endarteritis Susceptible to infection, which accelerates ORN Clinical Issues Presentation: Otalgia, otorrhea, hearing loss after regional RT Occurs few months to many years post-RT (> 60 Gy) In setting of RT for nasopharynx or EAC carcinoma most commonly Treatment options Localized form (EAC): Conservative management Diffuse form: Aggressive surgical resection of all necrotic tissue Diagnostic Checklist CT for bone changes; MR for complications (Left) Axial bone CT reveals abnormal soft tissue filling the left external auditory canal (EAC) and mastoid air cells with obvious destruction of the posterior EAC wall , mastoid septations , and petrous apex Findings represent classic appearance of temporal bone osteoradionecrosis (Right) Axial bone CT shows radiation-induced necrosis of the bony EAC along with confluent destruction of mastoid air cells and residual “floating” bony sequestrum , all indicating severe osteoradionecrosis 1589 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows diffuse opacification of the middle ear & mastoid in association with permeativedestructive bony changes in this previously radiated patient Focal bone necrosis is seen in otic capsule & lateral mastoid cortex (Right) Axial T1 C+ fat-saturated MR in previously radiated patient reveals nonspecific enhancing soft tissue in the middle ear , mastoid , & petrous apex Although radiation changes can be diagnosed by MR, ORN of bone is a diagnosis made by T-bone CT P.VI(7):15 TERMINOLOGY Abbreviations Osteoradionecrosis (ORN) Synonyms Radiation osteitis, radiation necrosis, irradiation osteomyelitis, avascular bone necrosis Definitions Radiation-induced injury to temporal bone IMAGING General Features Best diagnostic clue Bone CT shows “moth-eaten” demineralization/destruction of temporal bone ± sequestrum CT Findings CECT Mucosal involvement may enhance Contrast not needed to make diagnosis Bone CT Diffuse mucosal thickening in external auditory canal (EAC), middle ear cavity (MEC), & mastoid Permeative bone destruction ± sequestrum MR Findings T2WI Nonspecific high signal in EAC, MEC & mastoid High signal adjacent brain, if present, signals cerebral radiation necrosis T1WI C+ Mucosal injury will enhance MRV Evaluate for venous sinus thrombosis in severe cases Imaging Recommendations Best imaging tool Temporal bone CT Protocol advice Thin section axial & coronal bone CT MR for complications Cerebral radiation injury 1590 Diagnostic Imaging Head and Neck Meningitis or abscess Dural sinus thrombosis DIFFERENTIAL DIAGNOSIS Necrotizing External Otitis Immunocompromised, often diabetic patient EAC soft tissue & bone infection Coalescent Mastoiditis Disruption of mastoid septae in acute/chronic otomastoiditis Aggressive Cholesteatoma Cholesteatoma seen at otoscopy; no radiation history CT: Otic capsule invasion late finding Paget Disease Bilateral sensorineural hearing loss Entire cranial base usually involved Otosyphilis History of syphilis; no radiation therapy Permeative T-bone changes in osteitis phase PATHOLOGY General Features Etiology Radiation dose > 60 Gy Avascular bone necrosis from obliterative endarteritis Susceptible to infection, which accelerates ORN T-bone at higher risk for ORN Poorly vascularized bone Thin protective overlying soft tissue Exposure to respiratory tract pathogens via eustachian tube Gross Pathologic & Surgical Features Localized (more common) = limited to EAC Diffuse: Involves mastoid & MEC, possibly skull base Dead bone & soft tissue fibrosis CLINICAL ISSUES Presentation Most common signs/symptoms Purulent, foul-smelling otorrhea Hearing loss Tympanic membrane perforation Intracranial complications Meningitis, abscess, sinus thrombosis, CSF leak Natural History & Prognosis Occurs few months to many years post radiation therapy (RT) More commonly in setting of nasopharynx or EAC cancer Rarely develops radiation-induced tumors in RT field Treatment Localized form (EAC only): Conservative management Local debridement of EAC Antibiotics; otic prep (may need systemic treatment) Diffuse form: Aggressive surgical resection Resect all necrotic tissue ± vascularized flap ± hyperbaric oxygen DIAGNOSTIC CHECKLIST Image Interpretation Pearls CT for bone changes; MR for soft tissue complications SELECTED REFERENCES Metselaar M et al: Osteoradionecrosis of tympanic bone: reconstruction of outer ear canal with pedicled skin flap, combined with hyperbaric oxygen therapy, in five patients J Laryngol Otol 123(10):1114-9, 2009 Xu YD et al: Surgical treatment of osteoradionecrosis of the temporal bone in patients with nasopharyngeal carcinoma J Laryngol Otol 122(11):1175-9, 2008 Meiteles L et al: Osteoradionecrosis of the temporal bone Ear Nose Throat J 77(1):56-7, 1998 1591 Diagnostic Imaging Head and Neck Section - CPA-IAC Introduction and Overview CPA-IAC Overview > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Introduction and Overview > CPAIAC Overview CPA-IAC Overview H Ric Harnsberger, MD Embryology The temporal bone forms as distinct embryological events: 1) The external and middle ear, 2) the inner ear, and 3) the internal auditory canal (IAC) The practical implications of these related but separate embryological events is that the IAC may be absent or present independent of inner, middle, or external ear development status The IAC develops in response to formation/migration of the facial and vestibulocochlear nerves through this area IAC size depends on the number of nerve bundles migrating The fewer the nerve branches, the smaller the IAC If the IAC is very small and only nerve is seen, it is usually the facial nerve Imaging Techniques & Indications The principal imaging indication requiring radiologists to examine the CPA-IAC is sensorineural hearing loss (SNHL) Three goals must be achieved when completing the MR study in SNHL: 1) Use contrast-enhanced T1 fat-saturated thin section sequences through the CPA-IAC to identify lesions in this location, 2) utilize high-resolution T2-weighted sequences to answer presurgical questions when a mass lesion is found, and 3) screen the brain for intraaxial causes, such as multiple sclerosis The gold standard for imaging patients with SNHL is enhanced thin section (≤ mm) axial and coronal fat-saturated MR through the CPA-IAC With these enhanced sequences it is highly unlikely that a lesion causing SNHL will be missed Don't forget to obtain an axial or coronal pre-contrast T1 sequence and use fat saturation when contrast is applied to avoid the rare but troublesome mistake of calling a CPA-IAC lipoma a vestibular schwannoma In the absence of fat saturation, the inherent high signal of lipoma will appear to “enhance,” leading to the misdiagnosis of “vestibular schwannoma.” High-resolution T2-weighted thin section (≤ mm) MR sequences (CISS, FIESTA, etc.) in the axial and coronal plane can be used as a screening exam without contrast to identify patients with mass lesions in the CPA-IAC area However, these sequences are currently more commonly used as supplements when vestibular schwannoma is found on the enhanced T1 sequences to answer specific surgically relevant questions These questions include size of fundal cap and nerve of origin when vestibular schwannoma is small Whenever MR is ordered for SNHL, remember to include whole brain FLAIR, GRE, and DWI sequences FLAIR will identify the rare multiple sclerosis patient presenting with SNHL as well other intraaxial causes GRE will demonstrate micro- or macrohemorrhage within a vestibular schwannoma and may help with aneurysm diagnosis when blooming of blood products or calcium in an aneurysm wall is seen When DWI shows restricted diffusion in a CPA mass, the diagnosis of epidermoid is easily made Imaging Anatomy of the Cochlea-IAC-CPA The cochlear nerve portion of the vestibulocochlear nerve (CN8) begins in the modiolus of the cochlea where the bipolar spiral ganglia are found Distally projecting axons reach the organ of Corti within the scala media Proximally projecting axons coalesce to form the cochlear nerve itself within the fundus of the IAC CN8 in the CPA and IAC cisterns is made up of vestibular (balance) and cochlear (hearing) components The cochlear nerve is located in the anterior-inferior quadrant of the IAC In the region of the porus acusticus, the cochlear nerve joins the superior and inferior vestibular nerve bundles to become the vestibulocochlear nerve in the CPA cistern The vestibulocochlear nerve crosses the CPA cistern as the posterior nerve bundle (CN7 is the anterior nerve bundle) to enter the brainstem at the junction of the medulla and pons The entering nerve fibers pierce the brainstem, bifurcate to form synapses with both the dorsal and ventral cochlear nuclei These nuclei are found on the lateral surface of the inferior cerebellar peduncle (restiform body) Their location can be accurately determined by looking at high-resolution T2 axial images and identifying the contour of the inferior cerebellar peduncle Remembering the normal orientation of nerves within the IAC cistern is assisted by the mnemonic “seven-up, coke down.” CN7 is found in the anterosuperior quadrant while the cochlear nerve is confined to the anteroinferior quadrant From there it is simple to remember that the superior vestibular nerve (SVN) is posterosuperior while the inferior vestibular nerve (IVN) is posteroinferior Other normal structures to be aware of in the IAC include the horizontal crest (crista falciformis) and the vertical crest (“Bill bar”) The horizontal crest is a medially projecting horizontal bony shelf in the IAC fundus that separates the CN7-SVN above from the cochlear nerve-IVN below The vertical crest is found between CN7 and the SVN along the 1592 Diagnostic Imaging Head and Neck superior fundal bony wall The horizontal crest is easily seen on both bone CT and high-resolution MR The vertical crest can be visualized on bone CT only Openings from the IAC fundus into the inner ear are numerous The largest is the anteroinferior cochlear nerve canal conveying the cochlear nerve from the modiolus to the IAC fundus Anterosuperiorly the meatal foramen opens into the labyrinthine segment of CN7 The macula cribrosa is the multiply perforated bone separating the vestibule of the inner ear from the IAC fundus Other non-neural normal anatomy of interest in the CPA cistern includes the anterior inferior cerebellar artery (AICA loop), flocculus, and choroid plexus AICA arises from the basilar artery, courses superolaterally into the CPA, and then into the IAC cistern Within the IAC, the AICA feeds the internal auditory artery of the cochlea AICA loop in the IAC or CPA cisterns may mimic a cranial nerve bundle on high-resolution T2WI MR AICA vascular territory includes the cochlea, flocculus of the cerebellum, and anterolateral pons in the area of cranial nerve nuclei for CN5, CN7, and CN8 The flocculus is a lobule of the cerebellum projecting into the posterolateral CPA cistern The 4th ventricle choroid plexus may normally pass through the foramen of Luschka in the CPA cistern Approaches to Imaging Issues of CPA-IAC Approach to Sensorineural Hearing Loss in an Adult Unilateral SNHL in an otherwise healthy adult is evaluated with enhanced thin section fat-saturated T1WI P.VI(8):3 MR of the CPA-IAC area with high-resolution T2WI sequences providing help in surgical planning if a lesion is identified Despite audiometric and brainstem-evoked response testing in the otolaryngology clinic, positive MR studies for lesions causing the SNHL are infrequent (< 5% even in highly screened patient groups) Vestibular schwannoma is by far the most common cause of unilateral SNHL (about 90% of lesions found with MR) It is important for the radiologist to become familiar with the wide range of appearances of vestibular schwannoma, including intramural cystic change, micro-and macroscopic hemorrhage, and associated arachnoid cyst Meningioma, epidermoid cyst, and CPA aneurysm are responsible for about 8% of lesions found in adult patients with SNHL A long list of rare lesions, including otosclerosis, facial nerve, labyrinthine and jugular foramen schwannoma, IAC hemangioma, CPA metastases, labyrinthitis, sarcoidosis, lipoma, and superficial siderosis make up less than 2% of lesions found by MR causing unilateral SNHL in an adult Approach to Sensorineural Hearing Loss in a Child When a child presents with unilateral or bilateral SNHL, the emphasis in the imaging workup veers away from the typical adult tumor causes Instead, congenital inner ear and CPA-IAC lesions are sought as the cause of the hearing loss Complications of suppurative labyrinthitis (labyrinthine ossificans) are also included in the differential diagnosis When the child's presentation is bilateral profound SNHL, the imaging is usually obtained as part of the workup for possible cochlear implantation High-resolution T2 MR imaging is obtained in the axial and oblique sagittal planes to look for inner ear anomalies and labyrinthine ossificans as well as the presence or absence of a cochlear nerve in the IAC If complex congenital inner ear disease is found, bone CT is often obtained to further define the inner ear fluid spaces and look for an absent cochlear nerve canal In reviewing the MR and CT in a child with sensorineural hearing loss it is important to accurately describe any inner ear congenital anomaly if present If there is a history of meningitis, labyrinthine ossificans may be present Look for bony encroachment on the fluid spaces of the inner ear In particular, make sure the basal turn of the cochlea is open since occlusion by bony plaque may thwart successful cochlear implantation Check the T2 oblique sagittal MR images for the presence of a normal cochlear nerve If absent, cochlear implantation results may suffer Finally, look carefully at the IAC and CPA for signs of epidermoid cyst (restricted diffusion on DWI), lipoma (high signal on T1 pre-contrast sequences) and neurofibromatosis type (bilateral CPA-IAC vestibular or facial schwannoma) Selected References Sheth S et al: Appearance of normal cranial nerves on steady-state free precession MR images Radiographics 29(4):1045-55, 2009 Trimble K et al: Computed tomography and/or magnetic resonance imaging before pediatric cochlear implantation? Developing an investigative strategy Otol Neurotol 28(3):317-24, 2007 Rabinov JD et al: Virtual cisternoscopy: 3D MRI models of the cerebellopontine angle for lesions related to the cranial nerves Skull Base 14(2):93-9; discussion 99, 2004 Daniels RL et al: Causes of unilateral sensorineural hearing loss screened by high-resolution fast spin echo magnetic resonance imaging: review of 1,070 consecutive cases Am J Otol 21(2):173-80, 2000 Schmalbrock P et al: Assessment of internal auditory canal tumors: a comparison of contrast-enhanced T1-weighted and steady-state T2-weighted gradient-echo MR imaging AJNR Am J Neuroradiol 20(7):1207-13, 1999 Held P et al: MRI of inner ear and facial nerve pathology using 3D MP-RAGE and 3D CISS sequences Br J Radiol 70(834):558-66, 1997 Tables CPA Mass Differential Diagnosis 1593 Diagnostic Imaging Head and Neck Pseudolesions Asymmetric cerebellar flocculus Asymmetric choroid plexus Marrow foci around IAC High jugular bulb Jugular bulb diverticulum Congenital Epidermoid cyst Arachnoid cyst Lipoma Neurofibromatosis type Infectious Meningitis Cysticercosis Inflammatory Sarcoidosis Idiopathic intracranial pseudotumor Vascular Aneurysm (vertebrobasilar, PICA, AICA) Arteriovenous malformation Benign tumor Vestibular schwannoma Meningioma Facial nerve schwannoma IAC hemangioma Choroid plexus papilloma Hemangioblastoma, cerebellum Malignant tumor Metastases, systemic or subarachnoid spread (“drop”) Melanotic schwannoma Brainstem glioma, pedunculated Ependymoma P.VI(8):4 Image Gallery 1594 Diagnostic Imaging Head and Neck (Top) The normal cochlear nerve is seen as a coalescence of proximal axons from the modiolar spiral ganglia These axons pass through the cochlear nerve canal into the IAC fundus Distally projecting axons from the spiral ganglia reach the organ of Corti in the cochlear scala media (Bottom) Axial graphic depicts the vestibulocochlear nerve (CN8) The cochlear component of CN8 begins in bipolar cells bodies within spiral ganglion in the modiolus Central fibers run in the cochlear nerve to the dorsal & ventral cochlear nuclei on lateral margin of the inferior cerebellar peduncle Inferior & superior vestibular nerves begin in cell bodies in vestibular ganglion, from there coursing centrally to vestibular nuclei P.VI(8):5 1595 Diagnostic Imaging Head and Neck (Left) Axial bone CT through the superior IAC reveals the labyrinthine segment of CN7 , the meatal foramen , the vertical crest , and the superior vestibular nerve connecting the IAC to the vestibule through the macula cribrosa (Right) Axial T2WI MR through the superior IAC shows the anterosuperior CN7 , the superior vestibular nerve , and the vestibulocochlear nerve (Left) Axial bone CT through the inferior IAC shows the cochlear nerve canal , inferior vestibular nerve leaving the fundus , and singular nerve canal containing the posterior branch of the inferior vestibular nerve (Right) Axial T2WI MR through the inferior IAC reveals cochlear nerve projecting into cochlear nerve canal Dorsal & ventral cochlear nuclei are not seen but known to reside in the lateral inferior cerebellar peduncle margin Note the inferior vestibular nerve 1596 Diagnostic Imaging Head and Neck (Left) Oblique sagittal graphic of the IAC shows all nerves Anterior superior is CN7 , anterior inferior is the cochlear nerve , posterior superior is the superior vestibular nerve , and posterior inferior is the inferior vestibular nerve (Right) Oblique sagittal T2WI MR shows the nerve bundles of the mid-IAC cistern CN7 is anterosuperior , cochlear nerve anteroinferior , while the superior and inferior vestibular nerves are posterosuperior and posteroinferior, respectively Congenital Lesions CPA Epidermoid Cyst > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Congenital Lesions > CPA Epidermoid Cyst CPA Epidermoid Cyst H Ric Harnsberger, MD Key Facts Terminology Congenital inclusion of ectodermal epithelial elements during neural tube closure Imaging CPA cisternal insinuating mass with high signal on DWI MR 90% intradural, 10% extradural Margins usually scalloped or irregular Cauliflower-like margins with “fronds” possible TI and T2: Isointense or slightly hyperintense to CSF FLAIR: Does not null (attenuate) DWI: Hyperintensity here makes diagnosis Top Differential Diagnoses Arachnoid cyst, CPA Neurocysticercosis, CPA Neurenteric cyst Cystic neoplasm, CPA Cystic vestibular schwannoma Cystic meningioma, CPA Infratentorial ependymoma Pilocytic astrocytoma Pathology Surgical appearance: Pearly white CPA cistern mass Cyst wall: Internal layer of stratified squamous epithelium covered by fibrous capsule Clinical Issues Principal presenting symptom: Dizziness Other symptoms depend on location, growth pattern Cranial nerve 5, 7, neuropathy possible 1597 Diagnostic Imaging Head and Neck Treatment: Complete surgical removal is goal If recurs, takes many years to grow DWI MR key to diagnosing recurrence (Left) Axial graphic shows a large CPA epidermoid cyst within a typical “bed of pearls” appearance Note that the 5th , 7th, and 8th cranial nerves are characteristically engulfed by this insinuating mass (Right) Axial CECT shows a large CPA epidermoid cyst Note that this low-density lesion appears to invade the left cerebellar hemisphere Minimal rim enhancement is visible along the posterior margin of the cyst (Left) Axial FLAIR MR of the same patient shows “incomplete” or partial nulling of the signal of this large epidermoid cyst Associated high signal along the deep margins of the lesion is most likely due to gliosis of the cerebellar hemisphere (Right) Axial DWI MR in the same patient reveals the expected high signal from epidermoid cyst diffusion restriction DWI sequence allows differentiation of this epidermoid cyst from arachnoid cyst P.VI(8):7 TERMINOLOGY Synonyms Epidermoid tumor, primary cholesteatoma, or epithelial inclusion cyst Definitions Congenital inclusion of ectodermal epithelial elements during neural tube closure IMAGING General Features Best diagnostic clue 1598 Diagnostic Imaging Head and Neck CPA cisternal insinuating mass with high signal on DWI MR Engulfs cranial nerves (7th and 8th), vessels Location 90% intradural, 10% extradural Posterior fossa location most common CPA ˜ 40%; 4th ventricle ˜ 20% Size Wide range: 2-8 cm diameter Morphology Insinuating mass in cisterns Margins usually scalloped or irregular Cauliflower-like margins with “fronds” possible When large, compresses or invades brainstem ± cerebellum CT Findings NECT Similar density to cerebral spinal fluid (CSF) Calcification in 20%, usually margins Pressure erosion of T-bone and skull base may occur Rare variant: “Dense epidermoid” 3% of intracranial epidermoids From protein, cyst debris saponification to calcium soaps or iron-containing pigment CECT No enhancement is rule Sometimes margin of cyst minimally enhances MR Findings T1WI Isointense or slightly hyperintense to CSF If hyperintense, term “dirty CSF” has been applied Rare variant: “White epidermoid” with high T1 compared to brain Secondary to high triglycerides and unsaturated fatty acids T2WI Isointense to hyperintense to CSF “White epidermoid”: Low T2 signal FLAIR Does not null (attenuate) Lack of any attenuation or “incomplete attenuation” on FLAIR suggests diagnosis DWI Hyperintensity on DWI makes diagnosis Secondary to high fractional anisotropy from diffusion along 2D geometric plane Due to microstructure of parallel-layered keratin filaments and flakes ADC = brain parenchyma High-signal foci on DWI in surgical bed indicates recurrence T1WI C+ No enhancement is rule Mild marginal C+ may occur (25%) MRA Vessels of CPA may be displaced or engulfed Artery wall dimension not affected MRS Resonances from lactate No NAA, choline, or lipid Imaging Recommendations Best imaging tool Brain MR with FLAIR, DWI, and T1WI C+ sequences Protocol advice FLAIR and DWI sequences make diagnosis If looking for recurrence, DWI best sequence DIFFERENTIAL DIAGNOSIS Arachnoid Cyst, CPA 1599 Diagnostic Imaging Head and Neck Displaces, does not engulf, adjacent structures Isointense to CSF on all standard MR sequences T2 higher signal possible; if no CSF pulsations Completely nulls on FLAIR (low signal) Hypointense on DWI Contains highly mobile CSF ADC = stationary water Cystic Neoplasm in CPA Cystic vestibular schwannoma Cystic meningioma, CPA Infratentorial ependymoma Pedunculates from 4th ventricle Pilocytic astrocytoma Pedunculate from cerebellum All show some areas of enhancement on T1WI C+ MR Neurocysticercosis, CPA Partially enhances Density/signal intensity does not precisely follow CSF Adjacent brain edema or gliosis common Neurenteric Cyst Most common prepontine cistern in location T1 high signal (might mimic “white epidermoid”) T2 signal often low PATHOLOGY General Features Etiology Congenital inclusion of ectodermal elements during neural tube closure 3rd to 5th week of embryogenesis CPA lesion derived from 1st branchial groove cells Gross Pathologic & Surgical Features Pearly white mass in CPA Surgeons refer to it as “the beautiful tumor” Lobulated, cauliflower-shaped surface features P.VI(8):8 Insinuating growth pattern in cisterns Engulfs cisternal vessels and nerves May become adherent Lesion filled with soft, waxy, creamy, or flaky material Microscopic Features Cyst wall: Internal layer of stratified squamous epithelium covered by fibrous capsule Cyst contents: Solid crystalline cholesterol, keratinaceous debris No dermal appendages (hair follicles, sebaceous glands, or fat) Grows in successive layers by desquamation of squamous epithelium from cyst wall Conversion to keratin/cholesterol crystals form concentric lamellae CLINICAL ISSUES Presentation Most common signs/symptoms Principal presenting symptom: Dizziness Other symptoms depend on location, growth pattern Sensorineural hearing loss Trigeminal neuralgia (tic douloureux) Facial neuralgia (hemifacial spasm) Headache Symptoms usually present for > years before diagnosis Clinical profile 40-year-old patient with minor symptoms and large lesion discovered in CPA on MR Demographics 1600 Diagnostic Imaging Head and Neck Age Although congenital, presents in adult life Broad presentation: 20-60 years Peak age = 40 years Epidemiology 3rd most common CPA mass 1% of all intracranial tumors Natural History & Prognosis Slow-growing congenital lesions that remain clinically silent for many years Smaller cisternal lesions are readily cured with surgery Larger lesions with upward supratentorial herniation are more difficult to completely remove Larger lesions have more significant surgical complications Treatment Complete surgical removal is goal If large, near-total removal prudent surgical choice Aggressive total removal may cause significant cranial neuropathy Used when capsule is adherent to brainstem and cranial nerves If recurs, takes many years to grow DWI MR key to diagnosing recurrence DIAGNOSTIC CHECKLIST Consider MR diagnosis based on Insinuating CPA lesion Low signal on T1, high on T2 (similar to, but not identical to CSF) No or partial nulling on FLAIR Hyperintense on DWI Image Interpretation Pearls Diffusion MR imaging sequence is key to correct diagnosis Reporting Tips Be sure to report prepontine or medial middle cranial fossa extension if present SELECTED REFERENCES Jolapara M et al: Diffusion tensor mode in imaging of intracranial epidermoid cysts: one step ahead of fractional anisotropy Neuroradiology 51(2):123-9, 2009 Schiefer TK et al: Epidermoids of the cerebellopontine angle: a 20-year experience Surg Neurol 70(6):584-90; discussion 590, 2008 Akhavan-Sigari R et al: Epidermoid cysts of the cerebellopontine angle with extension into the middle and anterior cranial fossae: surgical strategy and review of the literature Acta Neurochir (Wien) 149(4):429-32, 2007 Ben Hamouda M et al: Atypical CT and MRI aspects of an epidermoid cyst J Neuroradiol 34(2):129-32, 2007 Osborn AG et al: Intracranial cysts: radiologic-pathologic correlation and imaging approach Radiology 239(3):65064, 2006 Hakyemez B et al: Intracranial epidermoid cysts: diffusion-weighted, FLAIR and conventional MR findings Eur J Radiol 54(2):214-20, 2005 Dutt SN et al: Radiologic differentiation of intracranial epidermoids from arachnoid cysts Otol Neurotol 23(1):8492, 2002 Kobata H et al: Cerebellopontine angle epidermoids presenting with cranial nerve hyperactive dysfunction: pathogenesis and long-term surgical results in 30 patients Neurosurgery 50(2):276-85; discussion 285-6, 2002 Dechambre S et al: Diffusion-weighted MRI postoperative assessment of an epidermoid tumour in the cerebellopontine angle Neuroradiology 41(11):829-31, 1999 10 Timmer FA et al: Chemical analysis of an epidermoid cyst with unusual CT and MR characteristics AJNR Am J Neuroradiol 19(6):1111-2, 1998 11 Ikushima I et al: MR of epidermoids with a variety of pulse sequences AJNR Am J Neuroradiol 18(7):1359-63, 1997 12 Kallmes DF et al: Typical and atypical MR imaging features of intracranial epidermoid tumors AJR Am J Roentgenol 169(3):883-7, 1997 13 Tien RD et al: Variable bandwidth steady-state free-precession MR imaging: a technique for improving characterization of epidermoid tumor and arachnoid cyst AJR Am J Roentgenol 164(3):689-92, 1995 14 Tsuruda JS et al: Diffusion-weighted MR imaging of the brain: value of differentiating between extraaxial cysts and epidermoid tumors AJNR Am J Neuroradiol 11(5):925-31; discussion 932-4, 1990 P.VI(8):9 1601 Diagnostic Imaging Head and Neck Image Gallery (Left) Axial T1WI C+ MR demonstrates a large, insinuating, right CPA cistern epidermoid cyst Note the low signal with lack of enhancement of the lesion The cyst insinuates into the cerebellar hemisphere and foramen of Luschka (Right) Axial T2WI MR in the same patient reveals a large, insinuating epidermoid cyst with typical high T2 signal and invagination into the cerebellar hemisphere and foramen of Luschka (Left) Axial T2WI FS thin section high-resolution MR shows a right CPA epidermoid cyst Note the cauliflower-like surface architecture This lesion is compressing the brachium pontis and adjacent cerebellar hemisphere (Right) Axial T2WI MR shows slight widening of the left CPA cistern with minimal mass effect on the brachium pontis , but no definite lesion is visible In a patient with left sensorineural hearing loss, arachnoid cyst or epidermoid cyst should be considered 1602 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in the same patient again reveals a widened CPA cistern but no evidence of enhancing tumor Both FLAIR and DWI sequences are used at this point to differentiate an arachnoid cyst from epidermoid cyst (Right) Axial DWI MR in the same patient demonstrates the characteristic restricted diffusion of the epidermoid cyst in the left CPA cistern Without DWI information, the lesion could have been missed altogether CPA Arachnoid Cyst > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Congenital Lesions > CPA Arachnoid Cyst CPA Arachnoid Cyst H Ric Harnsberger, MD Key Facts Terminology Arachnoid cyst (AC): Developmental arachnoid duplication anomaly creating CSF-filled sac Imaging Sharply demarcated round/ovoid extraaxial cisternal cyst with imperceptible walls with CSF density (CT) or intensity (MR) AC signal parallels CSF on all MR sequences Complete fluid attenuation on FLAIR MR No diffusion restriction on DWI MR imaging Top Differential Diagnoses Epidermoid cyst, CPA-IAC Mega cisterna magna Cystic vestibular schwannoma Neurenteric cyst Cystic meningioma, CPA-IAC Cystic infratentorial ependymoma Cerebellar pilocytic astrocytoma Clinical Issues Small AC: Asymptomatic, incidental finding (MR) Large AC: Symptoms from direct compression ± ↑ intracranial pressure Most AC not enlarge over time Most cases require no treatment Surgical intervention is highly selective process Diagnostic Checklist Differentiate AC from epidermoid cyst AC: No restriction on DWI = best clue Reporting tip: Since AC is usually not treated surgically, avoid offering any differential diagnosis when imaging findings diagnose AC 1603 Diagnostic Imaging Head and Neck (Left) Axial graphic of an arachnoid cyst in the CPA shows a thin, translucent wall Notice the cyst bowing the 7th and 8th cranial nerves anteriorly and effacing the brainstem and cerebellum (Right) Axial T1WI MR reveals a large right CPA arachnoid cyst causing bowing of the facial and vestibulocochlear nerves anteriorly and flattening of the lateral margin of the pons and cerebellar hemisphere No restriction on DWI is characteristic of arachnoid cyst (Left) Coronal graphic of a CPA arachnoid cyst depicts a typical translucent cyst wall CN7 and CN8 are pushed by the cyst without being engulfed by it In epidermoid cyst, cranial nerves are usually engulfed (Right) Coronal T1WI MR demonstrates a small CSF intensity CPA arachnoid cyst with subtle mass effect on the adjacent brainstem Complete fluid attenuation on FLAIR MR helps differentiate this lesion from an epidermoid cyst, which is the primary imaging differential diagnosis P.VI(8):11 TERMINOLOGY Abbreviations Arachnoid cyst (AC) Synonyms Primary or congenital AC, subarachnoid cyst Definitions Developmental arachnoid duplication anomaly creating CSF-filled sac IMAGING General Features Best diagnostic clue 1604 Diagnostic Imaging Head and Neck Sharply demarcated round/ovoid extraaxial cisternal cyst with imperceptible walls with CSF density on CT or signal intensity on MR AC signal parallels CSF on all MR sequences Complete fluid attenuation on FLAIR MR No diffusion restriction on DWI MR imaging Location 10-20% of all AC occur in posterior fossa CPA = most common infratentorial site Spread patterns Most remain confined to CPA (60%) May spread dorsal to brainstem (25%) Rarely spreads into IAC Size Broad range: 1-8 cm May be very large but asymptomatic When large, will exert mass effect on adjacent brainstem and cerebellum Morphology Sharply demarcated with broad-arching margins Displaces, does not engulf, surrounding structures Pushes cisternal structures but does not insinuate Epidermoid cyst insinuates adjacent structures CT Findings NECT Density same as CSF Rare high density from hemorrhage or proteinaceous fluid CECT No enhancement of cavity or wall Bone CT Rarely causes pressure erosion of adjacent bone CT cisternography May show connection to subarachnoid space MR Findings T1WI Low signal lesion isointense to CSF T2WI High signal lesion isointense to CSF May have brighter signal than CSF Cyst fluid lacks CSF pulsations Well-circumscribed, pushing lesion compresses adjacent brainstem and cerebellum when large FLAIR Suppresses (nulls) completely DWI No restriction (low signal) T1WI C+ No enhancement seen Phase-contrast cine MR Flow quantification can sometimes distinguish AC from subarachnoid space May show connection between AC and cistern Ultrasonographic Findings Grayscale ultrasound Shows sonolucent AC in infants < year of age Imaging Recommendations Best imaging tool MR ± contrast Protocol advice Add FLAIR (suppresses) Add DWI (no restricted diffusion) DIFFERENTIAL DIAGNOSIS Mega Cisterna Magna 1605 Diagnostic Imaging Head and Neck Prominence of retrocerebellar CSF space Large mega cisterna magna can extend into the CPA Not associated with cerebellar abnormalities Cystic Vestibular Schwannoma Intramural or marginal cysts seen in larger lesions Foci of enhancing tumor always present on T1WI C+ MR Rarely larger lesions have associated AC Epidermoid Cyst, CPA-IAC Major lesion of differential concern in setting of AC FLAIR: Incomplete fluid attenuation DWI: Restriction (high signal) Morphology: Insinuates adjacent CSF spaces Cystic Meningioma, CPA-IAC Rare meningioma variant Dural “tails,” asymmetry to IAC still present with mixed enhancement on T1WI C+ MR Neurenteric Cyst Rare prepontine cistern near midline Often contains proteinaceous fluid (↑ on T1WI MR) Cystic Infratentorial Ependymoma Ependymoma pedunculates from 4th ventricle via foramen of Luschka 50% calcified Cystic and solid enhancing components Cerebellar Pilocytic Astrocytoma Cystic tumor in cerebellar hemisphere Enhancing mural nodule PATHOLOGY General Features Etiology Embryonic meninges fail to merge Remain separate as duplicated arachnoid Split arachnoid contains CSF types P.VI(8):12 Noncommunicating; most common type Communicating with subarachnoid space/cistern Genetics Usually sporadic; rarely familial Associated abnormalities Acoustic schwannoma has AC associated in 0.5% Gross Pathologic & Surgical Features Fluid-containing cyst with translucent membrane Displaces adjacent vessels or cranial nerves Microscopic Features Thin wall of flattened but normal arachnoid cells CLINICAL ISSUES Presentation Most common signs/symptoms Small AC: Asymptomatic, incidental finding (MR) Large AC: Symptoms from direct compression ± ↑ intracranial pressure Other signs/symptoms Defined by location and size Headache Dizziness, tinnitus ± sensorineural hearing loss Hemifacial spasm or trigeminal neuralgia Clinical profile Adult undergoing brain MR for unrelated symptoms Demographics 1606 Diagnostic Imaging Head and Neck Age May be initially seen at any age 75% of AC occur in children Gender M:F = 3-5:1 Epidemiology Accounts for 1% of intracranial masses Natural History & Prognosis Most AC not enlarge over time Infrequently enlarge via CSF pulsation through ball-valve opening into AC Hemorrhage with subsequent ↓ in size reported If surgery is limited to AC where symptoms are clearly related, prognosis is excellent Radical cyst removal may result in cranial neuropathy ± vascular compromise Treatment Most cases require no treatment Surgical intervention is highly selective process Reserved for cases where clear symptoms can be directly linked to AC anatomic location Endoscopic cyst decompression via fenestration Least invasive initial approach DIAGNOSTIC CHECKLIST Consider Differentiate AC from epidermoid cyst AC: No restriction on DWI = best clue Determine if symptoms match location of AC before considering surgical treatment Image Interpretation Pearls AC signal follows CSF on all MR sequences Remember T2 signal may be higher than CSF from lack of CSF pulsation DWI sequence shows AC as low signal FLAIR sequence shows AC as low signal No enhancement of AC, including wall, is expected If nodular C+, consider alternative diagnosis Reporting Tips Since AC is usually not treated surgically, avoid offering any differential diagnosis when imaging findings diagnose AC SELECTED REFERENCES Boutarbouch M et al: Management of intracranial arachnoid cysts: institutional experience with initial 32 cases and review of the literature Clin Neurol Neurosurg 110(1):1-7, 2008 Marin-Sanabria EA et al: Evaluation of the management of arachnoid cyst of the posterior fossa in pediatric population: experience over 27 years Childs Nerv Syst 23(5):535-42, 2007 Helland CA et al: A population-based study of intracranial arachnoid cysts: clinical and neuroimaging outcomes following surgical cyst decompression in children J Neurosurg 105(5 Suppl):385-90, 2006 Osborn AG et al: Intracranial cysts: radiologic-pathologic correlation and imaging approach Radiology 239(3):65064, 2006 Tang L et al: Diffusion-weighted imaging distinguishes recurrent epidermoid neoplasm from postoperative arachnoid cyst in the lumbosacral spine J Comput Assist Tomogr 30(3):507-9, 2006 Alaani A et al: Cerebellopontine angle arachnoid cysts in adult patients: what is the appropriate management? J Laryngol Otol 119(5):337-41, 2005 Eskandary H et al: Incidental findings in brain computed tomography scans of 3000 head trauma patients Surg Neurol 63(6):550-3; discussion 553, 2005 Yildiz H et al: evaluation of communication between intracranial arachnoid cysts and cisterns with phase-contrast cine MR imaging AJNR Am J Neuroradiol 26(1):145-51, 2005 Dutt SN et al: Radiologic differentiation of intracranial epidermoids from arachnoid cysts Otol Neurotol 23(1):8492, 2002 10 Ottaviani F et al: Arachnoid cyst of the cranial posterior fossa causing sensorineural hearing loss and tinnitus: a case report Eur Arch Otorhinolaryngol 259(6):306-8, 2002 11 Samii M et al: Arachnoid cysts of the posterior fossa Surg Neurol 51(4):376-82, 1999 12 Jallo GI et al: Arachnoid cysts of the cerebellopontine angle: diagnosis and surgery Neurosurgery 40(1):31-7; discussion 37-8, 1997 1607 Diagnostic Imaging Head and Neck 13 Higashi S et al: Hemifacial spasm associated with a cerebellopontine angle arachnoid cyst in a young adult Surg Neurol 37(4):289-92, 1992 P.VI(8):13 Image Gallery (Left) Axial T2WI MR shows a high signal large arachnoid cyst enlarging the left cerebellopontine angle cistern The facial and vestibulocochlear nerves are visible bowing over the anteromedial surface of the arachnoid cyst (Right) Axial FLAIR MR in the same patient shows the low signal arachnoid cyst and complete fluid attenuation FLAIR suppression is expected as the arachnoid cyst is essentially CSF collecting between arachnoid layers (Left) Axial T1WI C+ FS MR in the same patient demonstrates that the CPA arachnoid cyst does not enhance (Right) Axial DWI MR in the same patient shows the arachnoid cyst has no associated signal (no restricted diffusion) If this were an epidermoid cyst, high signal on DWI (restricted diffusion) would be present DWI is the best way to differentiate an arachnoid cyst from an epidermoid cyst 1608 Diagnostic Imaging Head and Neck (Left) Axial NECT through the upper CPA cistern shows a large low-density arachnoid cyst causing flattening of the lateral brachium pontis and cerebellar hemisphere (Right) Axial T2WI FS MR demonstrates an incidental hyperintense CPA arachnoid cyst found at the time of imaging for headache This lenticular-shaped lesion displaces the glossopharyngeal nerve (CN9) anteriorly These small lesions require no additional imaging or treatment CPA-IAC Congenital Lipoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Congenital Lesions > CPA-IAC Congenital Lipoma CPA-IAC Congenital Lipoma H Ric Harnsberger, MD Key Facts Terminology Lipoma, CPA-IAC: Nonneoplastic mass of adipose tissue in CPA-IAC area Imaging Focal benign-appearing CPA-IAC mass, which follows fat density (CT) and intensity (MR) Concurrent intravestibular deposit may be seen in association with CPA-IAC lipoma MR: Hyperintense CPA mass (parallels subcutaneous and marrow fat intensity) Becomes hypointense with fat saturation Caveat: Fat-saturation MR sequences avoid mistaking lipoma for “enhancing CPA mass” Top Differential Diagnoses Neurenteric cyst Ruptured dermoid cyst Hemorrhagic vestibular schwannoma Aneurysm, CPA-IAC Pathology Persistence, maldevelopment of meningeal precursor tissue (embryonic meninx primitiva) Clinical Issues Most common presentation: Adult presenting with unilateral sensorineural hearing loss CN8 compression: Tinnitus (40%), vertigo (45%) Compression of CN5 root entry zone: Trigeminal neuralgia (15%) Compression of CN7 root exit zone: Hemifacial spasm, facial nerve weakness (10%) May be found incidentally on brain CT or MR completed for unrelated reasons Treatment: No treatment is best treatment Discontinue steroid treatment if present 1609 Diagnostic Imaging Head and Neck (Left) Axial graphic demonstrates a CPA lipoma abutting the lateral pons Notice that the facial nerve, vestibulocochlear nerve, and AICA loop all pass through the lipoma on their way to the internal auditory canal (Right) Axial T1WI MR shows a right CPA lipoma projecting off the lateral pontine pial surface Note the 2nd smaller lipoma along the lateral margin of the internal auditory canal A portion of the AICA loop passes through the anterolateral lipoma (Left) Axial T1WI MR shows a hyperintense CPA lipoma abutting the lateral pons Note the 2nd focus of T1 hyperintensity representing a small intravestibular lipoma Other T1 hyperintense lesions include hemorrhagic or proteinaceous masses (Right) Axial T1WI C+ FS MR in the same patient shows that the lesions disappear Fatsaturation MR sequences are key to confirming the diagnosis of lipoma and to avoid mistaking a lipoma for an enhancing CPA mass P.VI(8):15 TERMINOLOGY Synonyms Hamartomatous lipoma, lipomatous hamartoma Definitions Lipoma, CPA-IAC: Nonneoplastic mass of adipose tissue in CPA-IAC area Congenital malformation; not true neoplasm IMAGING General Features Best diagnostic clue Focal benign-appearing CPA-IAC mass, which follows fat density (CT) and intensity (MR) 1610 Diagnostic Imaging Head and Neck Location 20% of intracranial lipoma is infratentorial Primary location = CPA cistern May be in IAC only Concurrent intravestibular deposit may be seen in association with CPA-IAC lipoma Size 1-5 cm in maximum diameter May be as small as a few millimeters Morphology Lobulated pial-based fatty mass May encase CN7, CN8, AICA loop Small lesions Linear along course of cranial nerves and in CPA Ovoid within CPA cistern Large lesions Broad-based hemispherical shape adherent to lateral margin of pons CT Findings NECT Low-density CPA-IAC mass Measure mass using HU if uncertain Hounsfield unit range: -50 to -100 HU Calcification rare in CPA-IAC lesions CECT Lesion does not enhance MR Findings T1WI Hyperintense CPA mass (parallels subcutaneous and marrow fat intensity) Inner ear (vestibule) noncontiguous 2nd fatty lesion may be present Becomes hypointense with fat saturation T2WI Intermediate “fat intensity” lesion Conspicuous chemical shift artifact (frequency-encoding direction) Signal parallels subcutaneous and marrow fat STIR Hypointense due to STIR inherent fat saturation FLAIR Hyperintense compared to cisternal CSF T1WI C+ Lesion already hyperintense on pre-contrast images Use fat-saturated T1WI C+ sequence Lesion “disappears” secondary to fat saturation aspect of this MR sequence No enhancement in region of lesion is present Imaging Recommendations Best imaging tool MR is 1st study ordered when symptoms suggest possibility of CPA-IAC mass CT can easily confirm diagnoses by measuring HU if some confusion on MR images persists Protocol advice When T1WI C+ MR focused to CPA area is anticipated, need at least pre-contrast T1 sequence Pre-contrast T1 sequence helps distinguish fatty and hemorrhagic lesions from enhancing lesions Fatty lesions include lipoma and dermoid Hemorrhagic lesions with methemoglobin high-signal include aneurysm and venous varix Once high signal is seen on pre-contrast T1 sequence, fat-saturated sequences distinguish fat from hemorrhage Caveat: Fat saturation MR sequences avoid mistaking lipoma for “enhancing CPA mass” DIFFERENTIAL DIAGNOSIS Hemorrhagic Vestibular Schwannoma Rare manifestation of common lesion Patchy intraparenchymal signal on pre-contrast T1WI MR 1611 Diagnostic Imaging Head and Neck Hyperintensities persist with fat-saturated sequences Aneurysm, CPA-IAC CPA aneurysms from PICA > VA > AICA Rarely enters IAC (AICA) Ovoid CPA mass with calcified rim (CT) and complex layered signal (MR) MR signal complex with high-signal areas from methemoglobin in aneurysm lumen or wall Neurenteric Cyst Most common in prepontine cistern Contains proteinaceous fluid (hyperintense on T1WI MR) Ruptured Dermoid Cyst Ectodermal inclusion cyst Original location usually midline Rupture spreads fat droplets into subarachnoid space Rupture may lead to chemical meningitis PATHOLOGY General Features Etiology Best current hypothesis for lesion formation Persistence, maldevelopment of meningeal precursor tissue (embryonic meninx primitiva) Normally develops into leptomeninges and cisterns Maldifferentiates into fat instead Hyperplasia of fat cells normally within pia Genetics No known defects in sporadic CPA lipoma P.VI(8):16 Epidermal nevus syndrome has CPA lipomas as part of complex congenital anomalies Associated abnormalities 2nd fatty lesion may occur in inner ear vestibule Gross Pathologic & Surgical Features Soft, yellowish mass attached to leptomeninges Sometimes adherent to lateral pons May incorporate CN7 and CN8 with dense adhesions AICA loop may also be engulfed Microscopic Features Highly vascularized adipose tissue Mature lipocytes; mitoses rare CLINICAL ISSUES Presentation Most common signs/symptoms Mild, unilateral sensorineural hearing loss (60%) Clinical profile Adult presenting with slowly progressive unilateral sensorineural hearing loss Other signs/symptoms May be found incidentally on brain CT or MR completed for unrelated reasons CN8 compression: Tinnitus (40%), vertigo (45%) Compression of CN5 root entry zone: Trigeminal neuralgia (15%) Compression of CN7 root exit zone: Hemifacial spasm, facial nerve weakness (10%) Demographics Age Range at presentation: 10-40 years Epidemiology Lipomas occur less frequently in CPA than epidermoid and arachnoid cysts Epidermoid cyst > arachnoid cyst > > lipoma CPA lipoma represents 10% of all intracranial lipomas Interhemispheric (45%), quadrigeminal/superior cerebellar (25%), suprasellar/interpeduncular (15%), sylvian cisterns (5%) Natural History & Prognosis 1612 Diagnostic Imaging Head and Neck Usually does not grow over time Stability confirmed with follow-up examinations Attempts at complete excision of CPA lipomas may result in injury to CN7 and CN8 May enlarge if patient taking high-dose steroids Compressive symptoms may result Treatment No treatment is best treatment Discontinue steroid treatment if present Surgical removal is no longer recommended Cure often worse than disease due to entwined CN7 and CN8 Historically, 70% of postoperative patients had new postoperative deficits Surgical intervention only if cranial nerve decompression needed DIAGNOSTIC CHECKLIST Consider When high-signal lesion is seen in CPA on T1WI unenhanced MR, explanations to consider Fatty lesion Lipoma most common (dermoid rare) Hemorrhagic lesion Aneurysm lumen clot or clotted venous varix (dural arteriovenous fistula) Rare hemorrhagic acoustic schwannoma Highly proteinaceous fluid Neurenteric cyst (usually in prepontine cistern) Image Interpretation Pearls Once high-signal lesion is seen in CPA on pre-contrast T1WI MR, use fat saturation sequences to confirm diagnosis Reporting Tips Report size and extent of lipoma Check vestibule of inner ear for 2nd lesion Remind referring MD that CN7, CN8, and AICA loop often pass through CPA-IAC lipoma SELECTED REFERENCES Barajas RF Jr et al: Microvascular decompression in hemifacial spasm resulting from a cerebellopontine angle lipoma: case report Neurosurgery 63(4):E815-6; discussion E816, 2008 Vernooij MW et al: Intravestibular lipoma: an important imaging diagnosis Arch Otolaryngol Head Neck Surg 134(11):1225-8, 2008 Canyigit M et al: Epidermal nevus syndrome with internal carotid artery occlusion and intracranial and orbital lipomas AJNR Am J Neuroradiol 27(7):1559-61, 2006 Sade B et al: Cerebellopontine angle lipoma presenting with hemifacial spasm: case report and review of the literature J Otolaryngol 34(4):270-3, 2005 Gaskin CM et al: Lipomas, lipoma variants, and well-differentiated liposarcomas (atypical lipomas): results of MRI evaluations of 126 consecutive fatty masses AJR Am J Roentgenol 182(3):733-9, 2004 Dahlen RT et al: CT and MR imaging characteristics of intravestibular lipoma AJNR Am J Neuroradiol 23(8):1413-7, 2002 Tankéré F et al: Cerebellopontine angle lipomas: report of four cases and review of the literature Neurosurgery 50(3):626-31; discussion 631-2, 2002 Bigelow DC et al: Lipomas of the internal auditory canal and cerebellopontine angle Laryngoscope 108(10):145969, 1998 Kato T et al: Trigeminal neuralgia caused by a cerebellopontine-angle lipoma: case report Surg Neurol 44(1):33-5, 1995 10 Truwit CL et al: Pathogenesis of intracranial lipoma: an MR study in 42 patients AJR Am J Roentgenol 155(4):85564; discussion 865, 1990 11 Dalley RW et al: Computed tomography of a cerebellopontine angle lipoma J Comput Assist Tomogr 10(4):704-6, 1986 P.VI(8):17 Image Gallery 1613 Diagnostic Imaging Head and Neck (Left) Axial CECT reveals a fat-density lesion in the fundus of the right internal auditory canal The bone shape in this area is bulbous in comparison to the opposite normal IAC suggesting a congenital origin of the lesion (Right) Axial T1WI MR in the same patient shows the expected hyperintense fundal intracanalicular congenital lipoma Lipoma of the CPA-IAC area may be found in the CPA, IAC, and rarely, in the inner ear vestibule (Left) Axial T2WI FS MR in the same patient shows that the lipoma in the IAC fundus has become hypointense (Right) Axial T2WI MR without fat saturation shows a right intermediate-signal internal auditory canal mass as well as a left-sided mass Initial suspicion based on T2 screening study was neurofibromatosis type However, because the patient was 35 years old, further imaging was performed 1614 Diagnostic Imaging Head and Neck (Left) Axial T1WI MR in the same patient shows that the right IAC lesion is hyperintense while the left lesion is intermediate brain intensity Right IAC lipoma was diagnosed with probable left acoustic schwannoma (Right) Axial T1WI C+ FS MR in the same patient confirmed a right IAC lipoma and left IAC vestibular schwannoma Fatsaturation sequence nulls fat signal so that lipoma is no longer visible while enhancing schwannoma is highly conspicuous IAC Venous Malformation > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Congenital Lesions > IAC Venous Malformation IAC Venous Malformation H Ric Harnsberger, MD Key Facts Terminology IAC-VM: Benign developmental lesion associated with CN7 in IAC; may extend to geniculate ganglion Imaging Temporal bone CT findings Stippled ossifications in lesion matrix Enhanced T1 MR findings Enhancing IAC mass (< 10 mm) in fundus Focal intralesional low signal foci possible If extends along labyrinthine CN7 to geniculate ganglion, creates “dumbbell” appearance Top Differential Diagnoses CPA-IAC meningioma Vestibular schwannoma CPA-IAC facial nerve schwannoma CPA-IAC metastases Pathology Etiology Benign congenital VM arising in close approximation to IAC CN7 “Malformation” term used for errors of vascular morphogenesis that develop in utero and persist postnatally Microscopic features Immunohistochemical markers critical to venous malformation diagnosis Endothelial lining of vascular channels stain negatively for hemangioma-associated markers (GLUT1 & LeY antigen) Diagnostic Checklist IAC enhancing mass + CN7 paralysis ± punctate ossifications = IAC-VM 1615 Diagnostic Imaging Head and Neck (Left) Axial bone CT shows typical CT stippled ossifications in matrix of internal auditory canal venous malformation (hemangioma) When found, ossifications help differentiate IAC venous malformation from IAC acoustic schwannoma (Right) Axial T1WI C+ MR in the same patient demonstrates an enhancing IAC venous malformation The low signal foci along the anterior margin of the lesion are secondary to intratumoral ossifications (Left) Axial T1WI C+ FS MR reveals an enhancing IAC venous malformation with an area of low signal along the lesion anterior margin secondary to intratumoral ossification (Right) Micropathology shows dilated vascular spaces with collagenous walls, lined by a single layer of endothelium The endothelial lining stains negative for GLUT1 and LeY antigens These antigens are considered hemangioma-associated markers P.VI(8):19 TERMINOLOGY Abbreviations Internal auditory canal venous malformation (IAC-VM) Synonyms Hemangioma, cavernous hemangioma, cavernous malformation Definitions IAC-VM: Benign developmental lesion associated with CN7 in IAC; may extend to geniculate ganglion IMAGING General Features Best diagnostic clue Stippled ossifications in lesion matrix Location 1616 Diagnostic Imaging Head and Neck IAC ± labyrinthine CN7 ± geniculate ganglion Size Small at presentation; < 10 mm Morphology Ovoid to fusiform; may have irregular margins CT Findings Bone CT Fundal IAC mass < 10 mm Stippled ossifications often present No hyperostosis of IAC bony walls IAC flaring when lesion is larger MR Findings T2WI IAC mass < 10 mm Intermediate signal with focal low signal foci T2* GRE Blooming of intralesional ossifications possible T1WI C+ FS Enhancing IAC mass (< 10 mm) in fundus Focal intralesional low signal foci possible Imaging Recommendations Best imaging tool High-resolution CISS or FIESTA MR Enhanced T1 fat saturated also Temporal bone CT to verify ossifications DIFFERENTIAL DIAGNOSIS CPA-IAC Meningioma Most important lesion to differentiate from IAC-VM because it too may have low signal foci Enhancing IAC lesion ± hyperostotic bony walls ± calcification Vestibular Schwannoma Enhancing IAC lesion without ossifications If larger, symmetric projection from porus acusticus to CPA cistern CPA-IAC Facial Nerve Schwannoma Enhancing CPA-IAC mass Facial nerve labyrinthine segment “tail” key CPA-IAC Metastases Pial type: Thickens CN7 & CN8 in IAC; enhances Dural type: Diffuse smooth or nodular thickening of IAC-CPA dura; enhances PATHOLOGY General Features Etiology Benign congenital VM arising in close approximation to IAC CN7 “Malformation” used for in utero errors of vascular morphogenesis that persist postnatally Microscopic Features H&E: Nonencapsulated venous malformation composed of dilated vascular channels of varying sizes Widely ectatic vascular channels rimmed by smooth muscle coats without elastic laminae Flattened & mitotically quiescent endothelial cells Intralesional ossification often seen Immunohistochemical markers critical to VM diagnosis Endothelial lining of vascular channels stain negatively for hemangioma-associated markers (GLUT1 & LeY antigen) CLINICAL ISSUES Presentation Most common signs/symptoms Hearing loss associated with CN7 paralysis Hearing loss may come on rapidly Demographics Epidemiology Rare (< 1%) of IAC masses 1617 Diagnostic Imaging Head and Neck Natural History & Prognosis Adult onset progressive hearing loss ± CN7 paralysis Treatment Nerve sparing surgical resection CN7 graph necessary rarely if CN7 invaded DIAGNOSTIC CHECKLIST Consider IAC enhancing mass + CN7 paralysis ± punctate ossifications = IAC-VM SELECTED REFERENCES Benoit MM et al: Facial nerve hemangiomas: vascular tumors or malformations? Otolaryngol Head Neck Surg 142(1):108-14, 2010 Greene AK et al: Intraosseous “hemangiomas” are malformations and not tumors Plast Reconstr Surg 119(6):194950; author reply 1950, 2007 Bernardeschi D et al: Vascular malformation (so-called hemangioma) of Scarpa's ganglion Acta Otolaryngol 124(9):1099-102, 2004 Omojola MF et al: CT and MRI features of cavernous haemangioma of internal auditory canal Br J Radiol 70(839):1184-7, 1997 Infectious and Inflammatory Lesions CPA-IAC Meningitis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Infectious and Inflammatory Lesions > CPA-IAC Meningitis CPA-IAC Meningitis H Ric Harnsberger, MD Key Facts Terminology Definition: Acute or chronic infectious infiltrate of pia, arachnoid, & CSF in vicinity of temporal bone-IAC-CPA Imaging CT shows underlying lesion causing meningitis ± CSF leak Congenital: IE lesions, patent subarcuate canaliculus, cephalocele Acquired: Tegmen or posterior wall arachnoid granulations Acquired: T-bone fractures of tegmen or IE Acquired: Confluent mastoiditis or apical petrositis MR may show meningitis: Meningeal exudate + brain surface C+ Thickened meninges: Local or diffuse Top Differential Diagnoses Meningeal metastases CPA-IAC sarcoidosis Increased FLAIR signal in CSF from acute stroke, subarachnoid hemorrhage, or artifact Pathology Meningitis focused along deep surfaces of T-bone or in floor of middle cranial fossa is secondary to T-bone disease until proven otherwise Complications Cerebritis, abscess, empyema, ventriculitis Cerebrovascular complications Venous sinus or arterial thrombosis Clinical Issues Meningitis = clinical/laboratory diagnosis Not imaging diagnosis 1618 Diagnostic Imaging Head and Neck (Left) Coronal T1WI C+ MR shows enhancing mastoid tissue along with meningeal enhancement (meningitis) in this patient with severe headache and recurrent otomastoiditis (Right) Axial bone CT through the left temporal bone in the same patient demonstrates an air-fluid level in mastoid with thinning of anterior epitympanic recess wall Notice the partial opacification of the mastoid air cells In this case, bacterial otomastoiditis spread locally to cause the meningitis (Left) Axial bone CT of the right temporal bone in this patient with CSF proven meningitis reveals an arachnoid granulation in the location of the subarcuate canaliculus CSF otorrhea was present (Right) Coronal T1 C+ fatsaturated MR in the same patient after antibiotic treatment shows the arachnoid granulation as a focal fluid collection just above the right internal auditory canal Notice the diffuse leptomeningeal enhancement sometimes seen in the setting of meningitis P.VI(8):21 TERMINOLOGY Synonyms Leptomeningitis, infectious meningitis Definitions Acute or chronic infectious infiltrate of pia, arachnoid, & CSF in vicinity of temporal bone-IAC-CPA IMAGING General Features Best diagnostic clue Positive CSF by lumbar puncture Location 1619 Diagnostic Imaging Head and Neck Pia-arachnoid of T-bone intracranial surfaces Morphology Smooth thickening of pia-arachnoid Imaging Recommendations Best imaging tool Enhanced brain MR with CPA-IAC focused imaging Protocol advice MR with FLAIR, DWI, T1WI C+ CISS or FIESTA sequence aimed at temporal bone May show predisposing arachnoid granulations or inner ear (IE) malformation CT Findings Bone CT Underlying lesion causing CSF leak & meningitis Congenital predisposing lesions Congenital IE lesions, patent subarcuate canaliculus, cephalocele Acquired predisposing lesions Tegmen tympani/mastoideum or posterior wall arachnoid granulations Temporal bone fractures of tegmen or IE Confluent otomastoiditis or apical petrositis MR Findings T2WI Meningitis: Hyperintense exudate lines CPA-IAC ± deep temporal bone meningeal surfaces T-bone: High signal in middle ear if CSF leak FLAIR Meningitis: Hyperintense signal in sulci & cisterns of posterior fossa, middle cranial fossa DWI Detects vascular complications, empyema, abscess T1WI C+ Meningitis: Meningeal exudate + brain surface C+ Thickened meninges: Local or diffuse T-bone: Focal meningeal thickening + enhancement within T-bone may localize primary infection site CISS or FIESTA Thin section GRE imaging may show predisposing arachnoid granulations, inner ear anomaly, cephalocele DIFFERENTIAL DIAGNOSIS Meningeal Metastases Primary tumor usually known (exception = NHL) CPA-IAC Sarcoidosis Leptomeningeal nodular or lacy enhancement T-bone is uninvolved Increased FLAIR Signal in CSF Nonspecific MR finding Artifact Acute stroke Subarachnoid hemorrhage PATHOLOGY General Features Etiology Meningitis focused along deep surfaces of T-bone or in floor of middle cranial fossa is secondary to Tbone disease until proven otherwise Gross Pathologic & Surgical Features Looks similar whatever infectious agent Cisterns, sulci filled with cloudy CSF, then purulent exudate Pia-arachnoid thickened Microscopic Features Meningeal exudate: White cells, fibrin, bacteria CLINICAL ISSUES Presentation Most common signs/symptoms 1620 Diagnostic Imaging Head and Neck Meningitis = clinical/laboratory diagnosis CSF leak into middle ear + meningitis Otalgia, ↓ hearing, bulging tympanic membrane with retrotympanic fluid Headache, fever, nuchal rigidity, ± ↓ mental status ± seizures (30%) Clinical profile CSF shows ↑ white blood cells ↑ CSF protein, ↓ glucose (infectious meningitis) Natural History & Prognosis Effective antimicrobial agents have ↓ but not eliminated morbidity & mortality (˜ 20%) Treatment Intravenous antibiotics Surgical treatment varies with cause Acute T-bone infections T-bone fractures with meningitis ± CSF leak Underlying lesions causing meningitis ± CSF leak (arachnoid granulations, congenital IE lesions, cephalocele) SELECTED REFERENCES Smirniotopoulos JG et al: Patterns of contrast enhancement in the brain and meninges Radiographics 27(2):52551, 2007 Brown NE et al: Diagnosis and management of spontaneous cerebrospinal fluid-middle ear effusion and otorrhea Laryngoscope 114(5):800-5, 2004 Migirov L: Computed tomographic versus surgical findings in complicated acute otomastoiditis Ann Otol Rhinol Laryngol 112(8):675-7, 2003 Ramsay Hunt Syndrome > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Infectious and Inflammatory Lesions > Ramsay Hunt Syndrome Ramsay Hunt Syndrome Anna Jackson H Ric Harnsberger, MD Key Facts Terminology RHS: Varicella zoster virus infection involving sensory fibers of CN7 & CN8 & portion of external ear supplied by auriculotemporal nerve Imaging Imaging diagnosis: Pathologic enhancement on T1 C + MR of CN7 ± CN8 in IAC fundus along with all or part of membranous labyrinth Enhanced MR findings by location External ear: Enhancing external ear vesicles & associated inflammation Intratemporal CN7: Entire intratemporal CN7 enhancement typical Membranous labyrinth: Fluid spaces of cochlea, vestibule, & semicircular canals may all be variably affected Internal auditory canal: Linear to fusiform enhancement in IAC fundus (CN7 & CN8) Brainstem: Facial nucleus in brainstem enhances infrequently in RHS Top Differential Diagnoses Bell palsy Meningitis Clinical Issues Symptoms: CN7 palsy & sensorineural hearing loss associated with external ear vesicular rash Fever, vertigo, nausea, & vomiting Deep, burning pain in ear Conservative management 1st Pharmacologic treatment as indicated Corticosteroids ± acyclovir (↓ pain; improves CN7 function) 1621 Diagnostic Imaging Head and Neck (Left) Clinical photograph of the external ear demonstrates hemorrhagic vesicular rash affecting the auricle and external auditory canal This often painful rash along with facial and vestibulocochlear neuropathy makes the clinical diagnosis of Ramsay Hunt syndrome (RHS) obvious (Right) Axial T1WI C+ FS MR in a patient with Ramsay Hunt syndrome shows smooth linear enhancement of CN7 in IAC fundus and CN7 canal Note subtle enhancement in the vestibule also (Left) Axial SPGR C+ reveals enhancement of the left IAC fundus as well as enhancement of the labyrinthine segment, geniculate ganglion, and anterior tympanic segment of CN7 In addition, the greater superficial petrosal nerve branch of CN7 enhances along anterior margin of the petrous apex (Right) Magnified axial T2WI FS MR in the same patient shows the thickened, inflamed CN7 & CN8 as brain intensity material in the fundus of the internal auditory canal P.VI(8):23 TERMINOLOGY Abbreviations Ramsay Hunt syndrome (RHS) Synonyms Herpes zoster oticus Definitions RHS: Varicella zoster virus infection involving sensory fibers of CN7 & CN8 & portion of external ear supplied by auriculotemporal nerve IMAGING General Features 1622 Diagnostic Imaging Head and Neck Best diagnostic clue Pathologic enhancement on T1 C+ MR of CN7 ± CN8 in IAC fundus along with all or part of membranous labyrinth Morphology Linear or fusiform IAC enhancement is rule MR Findings T2WI High-resolution (≤ mm) T2 Fundal 7th & 8th cranial nerves thickened When severe, may mimic fundal vestibular schwannoma FLAIR Parenchymal brain normal T1WI C+ External ear Enhancing external ear vesicles & associated inflammation Intratemporal facial nerve Entire intratemporal CN7 enhancement typical Labyrinthine segment CN7 & geniculate ganglion reliably enhance Membranous labyrinth Fluid spaces of cochlea, vestibule, & semicircular canals may all be variably affected Cochlear portion enhances most commonly Membranous labyrinth enhancement may not be present even when hearing loss & vertigo present Internal auditory canal Linear to fusiform enhancement in IAC fundus (CN7 & CN8) IAC enhancement not always present even with sensorineural hearing loss ± vertigo Brainstem Facial nucleus in brainstem enhances infrequently in RHS Imaging Recommendations Best imaging tool Whole brain MR with enhanced sequences focused on CPA-IAC & temporal bone Findings best seen on fat-saturated T1 C+ MR images Protocol advice If external ear vesicular rash is clinically apparent, no imaging is necessary to investigate associated CN7 & CN8 palsies DIFFERENTIAL DIAGNOSIS Bell Palsy Enhancement of CN7; not membranous labyrinth or CN8 Fundal CN7 enhancing “tuft” IAC enhancement usually less intense than RHS Meningitis Headache, stiff neck, fever Thickened, diffusely enhancing meninges CSF analysis may be revealing PATHOLOGY General Features Etiology Classic hypothesis: Virus remains dormant within geniculate ganglion with periodic reactivation Varicella zoster virus can be cultured from vesicles or from saliva CLINICAL ISSUES Presentation Most common signs/symptoms Facial palsy & sensorineural hearing loss associated with external ear vesicular rash Other signs/symptoms Fever, vertigo, nausea, & vomiting Deep, burning pain in ear Natural History & Prognosis Ear pain followed in ˜ days by erythematous vesicular rash of external ear Cranial neuropathies appear after onset of ear pain 1623 Diagnostic Imaging Head and Neck Appear before or after vesicular eruption When before, imaging may be done looking for etiology of 7th cranial nerve palsy Treatment Conservative management 1st Warm compresses & analgesics Cornea care for facial paralysis Pharmacologic treatment Corticosteroids ± acyclovir (↓ pain, improves CN7) DIAGNOSTIC CHECKLIST Consider MR imaging should only be done when clinical presentation is atypical SELECTED REFERENCES Antón E: Less common MRI findings in ramsay hunt syndrome type I Ear Nose Throat J 86(11):649; author reply 649-50, 2007 Sartoretti-Schefer S et al: Ramsay Hunt syndrome associated with brain stem enhancement AJNR Am J Neuroradiol 20(2):278-80, 1999 Jonsson L et al: Gd-DPTA enhanced MRI in Bell's palsy and herpes zoster oticus: an overview and implications for future studies Acta Otolaryngol 115(5):577-84, 1995 CPA-IAC Sarcoidosis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Infectious and Inflammatory Lesions > CPA-IAC Sarcoidosis CPA-IAC Sarcoidosis Anna Jackson H Ric Harnsberger, MD Key Facts Terminology Neurosarcoidosis: Systemic disorder with noncaseating granulomas of multiple organ systems Imaging MR findings Multifocal enhancing meningeal masses Dural (35%), leptomeningeal (35%) Other intracranial locations: Cranial nerves, pituitary gland, hypothalamus T2: Hypointense or hyperintense meningeal foci Hypointense: Fibrocollagenous/gliotic tissue Hyperintense: Inflammatory tissue T1 C+: En plaque, nodular or linear dural enhancing lesions Top Differential Diagnoses Meningitis Multiple meningiomas CPA-IAC metastases Idiopathic inflammatory pseudotumor Pathology Noncaseating granulomas are characteristic Clinical Issues Systemic sarcoidosis: Pulmonary symptoms CNS sarcoidosis symptoms Visual loss & diabetes insipidus Cranial neuropathy: CN2 > > CN5, CN3 > CN7 CPA-IAC: Unilateral SNHL ± facial neuropathy African-Americans affected more frequently Laboratory findings are confirmatory CSF: ↑ protein & leukocyte count; lymphocytosis ↑ CSF angiotensin converting enzyme (ACE) Treatment: Steroids ± immunomodulators 1624 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ MR shows multifocal enhancing meningeal nodules The lesion in the left CPA enters the internal auditory canal Inflammatory diseases (Wegener granulomatosis, intracranial pseudotumor, granulomatous infection) and diffuse meningeal malignancies (NHL, metastases) are part of the differential diagnosis (Right) Axial thin section T2WI MR in the same patient reveals multifocal hypointense meningeal nodules with IAC involvement on the left (Left) Axial T1WI C+ MR demonstrates an extensive, contiguous sarcoid meningeal lesion with a conspicuous CPA component mimicking en plaque meningioma The meninges that line the middle cranial fossa are diffusely affected (Right) Sagittal T1WI C+ FS MR demonstrates leptomeningeal (primarily pial) enhancing sarcoid nodules in the CPA , along brainstem surface , and in the hypothalamus Also notice the meningeal lesion along anterior surface of cervical spinal canal P.VI(8):25 TERMINOLOGY Definitions Systemic disorder with noncaseating granulomas of multiple organ systems IMAGING General Features Best diagnostic clue Multifocal enhancing meningeal masses Location Dural (35%), leptomeningeal (35%) Other intracranial locations 1625 Diagnostic Imaging Head and Neck Cranial nerves, pituitary gland, hypothalamus CT Findings CECT Focal enhancing meningeal masses MR Findings T2WI Hypointense or hyperintense meningeal foci FLAIR Hyperintense cerebellum ± brainstem areas Most commonly seen in leptomeningeal form T1WI C+ En plaque, nodular or linear dural enhancing lesions Leptomeningeal disease spreads via perivascular spaces into brain Cranial nerve enhancement Imaging Recommendations Best imaging tool MR with FLAIR & T1 C+ sequences Radiographic Findings Chest x-ray/chest CT Adenopathy & interstitial disease Nuclear Medicine Findings PET/CT May be useful in finding unsuspected multivisceral disease & assessing therapy response DIFFERENTIAL DIAGNOSIS Meningitis T1 C+ MR may mimic sarcoidosis (especially in fungal or TB meningitis) Multiple Meningiomas Multifocal enhancing dural masses Hyperostosis of underlying bone possible CPA-IAC Metastases Nodular meningeal metastases < diffuse When nodular, T1 C+ MR appearance similar to sarcoidosis Idiopathic Inflammatory Pseudotumor Usually unifocal enhancing meningeal mass Underlying bone may show erosions PATHOLOGY General Features Etiology Pathophysiology unknown General pathology issues Diagnosis often made after biopsy of skin lesions Neurosarcoidosis patterns of involvement Dural en plaque or nodular disease Leptomeningeal disease on surface of brain Cranial nerves: CN2 > CN5 & CN3 > CN7 Brain foci: Penetration of leptomeninges via perivascular spaces Microscopic Features Noncaseating granulomas are characteristic Langerhans giant cells mixed within epithelioid cells Inflammatory or fibrocollagenous/gliotic cells CLINICAL ISSUES Presentation Most common signs/symptoms Systemic sarcoidosis: Pulmonary symptoms CNS sarcoidosis: Visual loss & diabetes insipidus Cranial neuropathy: CN2 > > CN5, CN3 > CN7 CPA-IAC: Unilateral SNHL ± facial neuropathy Clinical profile Adult with visual loss, central diabetes insipidus, & unilateral SNHL 1626 Diagnostic Imaging Head and Neck Laboratory findings are confirmatory CSF: High protein & leukocyte count; lymphocytosis ↑ CSF angiotensin converting enzyme (ACE) Demographics Age 20-40 year olds Ethnicity African-Americans > > other ethnicities Epidemiology CNS sarcoid: 25% of systemic sarcoidosis patients Subclinical in most cases Natural History & Prognosis 2/3 have self-limited monophasic illness > 50% recover without significant morbidity Prognosis worse if brain ± spinal lesions present Treatment Prompt administration of steroids ± immunomodulators SELECTED REFERENCES Bolat S et al: Fluorodeoxyglucose positron emission tomography (FDG-PET) is useful in the diagnosis of neurosarcoidosis J Neurol Sci 287(1-2):257-9, 2009 Shah R et al: Correlation of MR imaging findings and clinical manifestations in neurosarcoidosis AJNR Am J Neuroradiol 30(5):953-61, 2009 Scott TF et al: Aggressive therapy for neurosarcoidosis: long-term follow-up of 48 treated patients Arch Neurol 64(5):691-6, 2007 Benign and Malignant Tumors Vestibular Schwannoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Benign and Malignant Tumors > Vestibular Schwannoma Vestibular Schwannoma H Ric Harnsberger, MD Key Facts Terminology VS: Benign tumor arising from Schwann cells that wrap vestibular branches of CN8 in CPA-IAC Imaging High-resolution T2 or CISS: “Filling defect” in ↑ signal CSF of CPA-IAC cistern Small VS: Ovoid filling defect in ↑ signal CSF Large VS: “Ice cream on cone” shape in CPA-IAC 0.5% associated arachnoid cyst FLAIR: ↑ cochlear signal from ↑ protein GRE/TSE: Microhemorrhage ↓ signal foci (common) Not seen in meningioma < 1%: Macroscopic intratumoral hemorrhage T1WI C+: Focal, enhancing mass of CPA-IAC cistern centered on porus acusticus 15% with intramural cysts (low signal foci) Top Differential Diagnoses Epidermoid cyst, CPA Aneurysm, CPA-IAC Meningioma, CPA-IAC Facial nerve schwannoma, CPA-IAC Metastases, CPA-IAC Pathology Benign tumor arising from vestibular portion of CN8 at glial-Schwann cell junction Clinical Issues Adults with unilateral sensorineural hearing loss Translabyrinthine resection if no hearing Middle cranial fossa approach for IAC VS Retrosigmoid approach when CPA or medial IAC component present 1627 Diagnostic Imaging Head and Neck Fractionated or stereotactic radiosurgery (Left) Axial graphic shows small intracanalicular vestibular schwannoma arising from the superior vestibular nerve Notice the cochlear nerve canal is uninvolved (Right) Axial T2WI MR reveals a small intracanalicular vestibular schwannoma visualized as a tissue intensity mass surrounded by high intensity cerebrospinal fluid The cochlear nerve canal is not involved, and an mm fundal cap is present (Left) Axial graphic of a large vestibular schwannoma reveals the typical “ice cream on cone” CPA-IAC morphology Mass effect on the middle cerebellar peduncle and cerebellar hemisphere is evident (Right) Axial T1WI C+ MR demonstrates a large CPA-IAC vestibular schwannoma compressing the middle cerebellar peduncle and cerebellar hemisphere Enhancement within the IAC and the large intramural cyst make the imaging diagnosis certain P.VI(8):27 TERMINOLOGY Abbreviations Vestibular schwannoma (VS) Synonyms Acoustic schwannoma, acoustic neuroma, acoustic tumor Uncommon names: Neurinoma, neurilemmoma Definitions Benign tumor arising from Schwann cells that wrap vestibular branches of CN8 in CPA-IAC IMAGING General Features Best diagnostic clue 1628 Diagnostic Imaging Head and Neck Avidly enhancing cylindrical (IAC) or “ice cream on cone” (CPA-IAC) mass Location Small lesions: Intracanalicular Large lesions: Intracanalicular with CPA cistern extension Size Small lesions: 2-10 mm Larger lesions: Up to cm in maximum diameter Morphology Small and intracanalicular VS: Ovoid mass Large VS: “Ice cream (CPA) on cone (IAC)” CT Findings CECT Well-delineated, enhancing mass of CPA-IAC cistern Calcification not present (compared to CPA meningioma) May flare IAC when large Smaller intracanalicular lesions (< mm) may be missed with CECT MR Findings T1WI Brain signal most common ↑ signal foci if rare hemorrhage present T2WI FS High-resolution T2 or CISS: “Filling defect” in ↑ signal CSF of CPA-IAC cistern Small lesion: Ovoid filling defect in ↑ signal CSF of IAC Large lesion: “Ice cream on cone” filling defect in CPA-IAC FLAIR ↑ cochlear signal from ↑ perilymph protein T2* GRE Microhemorrhage low-signal foci common Not seen in meningioma T1WI C+ FS Focal, enhancing mass of CPA-IAC cistern centered on porus acusticus 100% enhance strongly 15% with intramural cysts (low signal foci) Dural “tails” rare (compared to meningioma) Other MR findings < 1%: Macroscopic intratumoral hemorrhage 0.5% associated arachnoid cyst Imaging Recommendations Best imaging tool Gold standard is full brain FLAIR MR with axial and coronal T1WI C+ FS MR of CPA-IAC Protocol advice High-resolution T2 or CISS MR of CPA-IAC is only screening exam for VS Used for uncomplicated unilateral SNHL in adult DIFFERENTIAL DIAGNOSIS Meningioma, CPA-IAC Intracanalicular meningioma may mimic VS (rare) CECT: Calcified dural-based mass eccentric to porus acusticus T1WI C+ MR: Broad dural base with associated dural “tails” Epidermoid Cyst, CPA May mimic rare cystic VS Insinuating morphology T1WI C+ MR: Nonenhancing CPA mass DWI: Diffusion restriction (high signal) Arachnoid Cyst, CPA-IAC Well-marginated CPA lesion that does not enter IAC Follows CSF signal on all MR sequences DWI: No restricted diffusion Aneurysm, CPA-IAC Ovoid to fusiform complex signal mass in CPA 1629 Diagnostic Imaging Head and Neck Facial Nerve Schwannoma, CPA-IAC When confined to CPA-IAC, may exactly mimic VS Look for labyrinthine segment “tail” to differentiate Metastases, CPA-IAC May be bilateral meningeal involvement Beware of misdiagnosing as NF2 PATHOLOGY General Features Etiology Benign tumor arising from vestibular portion of CN8 at glial-Schwann cell junction Rare in cochlear portion CN8 Genetics Inactivating mutations of NF2 tumor suppressor gene in 60% of sporadic VS Loss of chromosome 22q also seen Multiple or bilateral schwannomas = NF2 Associated abnormalities Arachnoid cyst (0.5%) Staging, Grading, & Classification WHO grade I lesion Gross Pathologic & Surgical Features Tan, round-ovoid, encapsulated mass Arises eccentrically from CN8 at glial-Schwann cell junction P.VI(8):28 Glial-Schwann cell junction most commonly near porus acusticus Microscopic Features Differentiated neoplastic Schwann cells in collagenous matrix Areas of compact, elongated cells = Antoni A Most VS comprised mostly of Antoni A cells Areas less densely cellular with tumor loosely arranged, ± clusters of lipid-laden cells = Antoni B Strong, diffuse expression of S100 protein No necrosis; instead intramural cysts < 1% hemorrhagic CLINICAL ISSUES Presentation Most common signs/symptoms Adults with unilateral sensorineural hearing loss (SNHL) Clinical profile Slowly progressive SNHL Laboratory Brainstem electric response audiometry (BERA) most sensitive pre-imaging test for VS Screening MR could replace BERA Other symptoms Small VS: Tinnitus (ringing in ear); disequilibrium Large VS: Trigeminal ± facial neuropathy Demographics Age Adults (rare in children unless NF2) Peak age = 40-60 years Age range = 30-70 years Epidemiology Most common lesion in unilateral SNHL (> 90%) Most common CPA-IAC mass (85-90%) 2nd most common extraaxial neoplasm in adults Natural History & Prognosis 60% of VS are slow growing (< mm/year) 10% of VS grow rapidly (> mm/year) 60% of VS grow slowly; can be followed with imaging 1630 Diagnostic Imaging Head and Neck Used in > 60 year olds, poor health, small tumor size, patient preference Successful surgical removal of VS will not restore any hearing already lost Negative prognostic imaging findings for hearing preservation Size > cm VS involves IAC fundus ± cochlear aperture Treatment Translabyrinthine resection if no hearing preservation possible Middle cranial fossa approach for intracanalicular VS Especially lateral IAC location Retrosigmoid approach when CPA or medial IAC component present Fractionated or stereotactic radiosurgery Gamma knife: Low dose, sharply collimated, focused cobalt-60 treatment Used when medical contraindications to surgery and residual postoperative VS Now used more commonly as 1st treatment DIAGNOSTIC CHECKLIST Consider Consider using high-resolution T2 unenhanced axial and coronal MR as “screening” for VS Thin section, T1WI C+ axial and coronal MR is gold standard imaging approach Image Interpretation Pearls Unilateral well-circumscribed IAC or CPA-IAC mass should be considered VS until proven otherwise Always make sure there is no labyrinthine “tail” on all VS to avoid misdiagnosing facial nerve schwannoma Reporting Tips Comment on tumor size ± CPA involvement Does VS involve cochlear nerve canal or IAC fundus? How large in mm is “fundal cap”? Is hemorrhage, intramural cyst, or arachnoid cyst present within or associated with VS? When small, comment on nerve of origin as possible SELECTED REFERENCES Bakkouri WE et al: Conservative management of 386 cases of unilateral vestibular schwannoma: tumor growth and consequences for treatment J Neurosurg 110(4):662-9, 2009 Fukuoka S et al: Gamma knife radiosurgery for vestibular schwannomas Prog Neurol Surg 22:45-62, 2009 Bhadelia RA et al: Increased cochlear fluid-attenuated inversion recovery signal in patients with vestibular schwannoma AJNR Am J Neuroradiol 29(4):720-3, 2008 Ferri GG et al: Conservative management of vestibular schwannomas: an effective strategy Laryngoscope 118(6):951-7, 2008 Meijer OW et al: Tumor-volume changes after radiosurgery for vestibular schwannoma: implications for follow-up MR imaging protocol AJNR Am J Neuroradiol 29(5):906-10, 2008 Thamburaj K et al: Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma AJNR Am J Neuroradiol 29(3):552-7, 2008 Okamoto K et al: Focal T2 hyperintensity in the dorsal brain stem in patients with vestibular schwannoma AJNR Am J Neuroradiol 27(6):1307-11, 2006 Darrouzet V et al: Vestibular schwannoma surgery outcomes: our multidisciplinary experience in 400 cases over 17 years Laryngoscope 114(4):681-8, 2004 Dubrulle F et al: Cochlear fossa enhancement at MR evaluation of vestibular Schwannoma: correlation with success at hearing-preservation surgery Radiology 215(2):458-62, 2000 10 Nakamura H et al: Serial follow-up MR imaging after gamma knife radiosurgery for vestibular schwannoma AJNR Am J Neuroradiol 21(8):1540-6, 2000 11 Allen RW et al: Low-cost high-resolution fast spin-echo MR of acoustic schwannoma: an alternative to enhanced conventional spin-echo MR? AJNR Am J Neuroradiol 17(7):1205-10, 1996 P.VI(8):29 Image Gallery 1631 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in a patient with left sensorineural hearing loss shows a small enhancing vestibular schwannoma within the internal auditory canal with a mm fundal CSF cap lateral to the tumor (Right) Axial CISS MR in the same patient reveals a “filling defect” within the high-signal CSF in the IAC The vestibular schwannoma is easily diagnosed with CISS imaging The fundal CSF cap is more readily seen with T2 or CISS MR (Left) Coronal high-resolution thin section T2WI MR demonstrates a mm superior vestibular schwannoma The lesion is seen superior to the crista falciformis with the anterior inferior cerebellar artery loop visible in the lateral IAC (Right) Axial T1WI MR reveals the IAC and CPA components of a larger vestibular schwannoma Increased signal in the medial CPA portion of this tumor is due to methemoglobin from subacute intratumoral hemorrhage 1632 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ MR in the same patient shows an enhancing vestibular schwannoma with IAC and CPA components The medial CPA intramural cystic change is due to hemorrhage (Right) Axial T2* GRE MR in the same patient demonstrates intense “blooming” of low signal in the CPA component of the vestibular schwannoma This finding along with the high signal on the nonenhanced T1 image confirms intratumor hemorrhage CPA-IAC Meningioma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Benign and Malignant Tumors > CPA-IAC Meningioma CPA-IAC Meningioma H Ric Harnsberger, MD Key Facts Terminology Benign, unencapsulated neoplasm arising from meningothelial arachnoid cells of CPA-IAC dura Imaging 10% occur in posterior fossa When in CPA, asymmetric to IAC porus acusticus NECT: 25% calcified; types seen Homogeneous, sand-like (“psammomatous”) Focal sunburst, globular, or rim pattern Bone CT: Hyperostotic or permeative-sclerotic bone changes possible (en plaque type) T2WI MR: Pial blood vessels seen as surface flow voids between tumor and brain High signal crescent from CSF (“CSF cleft”) T1WI C+ MR: Enhancing dural-based mass with dural “tails” centered along posterior petrous wall Top Differential Diagnoses Sarcoidosis, CPA-IAC Epidermoid cyst, CPA-IAC Idiopathic inflammatory pseudotumor, skull base Vestibular schwannoma Intracranial trigeminal schwannoma Metastases, CPA-IAC Primary CNS lymphoma Clinical Issues Incidental brain MR finding < 10% symptomatic Usually not cause sensorineural hearing loss Treatment Surgical removal if medically safe Adjunctive radiation therapy with incomplete surgery 1633 Diagnostic Imaging Head and Neck (Left) Axial graphic at level of the IAC shows a large CPA meningioma causing mass effect on the brainstem and cerebellum Notice the broad dural base creating the shape of a mushroom head A dural “tail” is present in approximately 60% of cases and typically represents reactive rather than neoplastic change (Right) Gross pathologic section viewed from below shows a large CPA meningioma with a broad dural base compressing the cerebellum The specimen demonstrates a CSF-vascular cleft (Left) Axial T1WI C+ FS MR through the IAC shows a meningioma overlying the porus acusticus Note the dural “tail” extending along the temporal bone posterior wall A dot of enhancement in the IAC fundus suggests the low signal area in the IAC is nonenhancing meningioma (Right) Axial T2WI FS MR in the same patient reveals a highvelocity flow void representing a dural artery feeder penetrating the meningioma core Low signal in IAC is intracanalicular meningioma P.VI(8):31 TERMINOLOGY Synonyms Posterior fossa meningioma Definitions Benign, unencapsulated neoplasm arising from meningothelial arachnoid cells of CPA-IAC dura IMAGING General Features Best diagnostic clue CPA dural-based enhancing mass with dural “tails” 1634 Diagnostic Imaging Head and Neck Location 10% occur in posterior fossa When in CPA, asymmetric to IAC porus acusticus Size Broad range; usually 1-8 cm but may be larger Generally significantly larger than vestibular schwannoma at presentation Morphology distinct morphologies “Mushroom cap” (hemispherical) with broad base towards posterior petrous wall (75%) Plaque-like (en plaque), ± bone invasion with hyperostosis (20%) Ovoid mass mimics vestibular schwannoma (5%) Frequently (50%) herniates cephalad into medial middle cranial fossa CT Findings NECT 25% isodense, 75% hyperdense 25% calcified; types seen Homogeneous, sand-like (“psammomatous”) Focal sunburst, globular, or rim pattern CECT > 90% strong, uniform enhancement Bone CT Hyperostotic or permeative-sclerotic bone changes possible (en plaque type) IAC flaring is rare (cf vestibular schwannoma) MR Findings T1WI Isointense or minimally hyperintense to gray matter When tumor has calcifications or is highly fibrous, hypointense areas are visible T2WI Wide range of possible signals on T2 sequence Isointense or hypointense CPA mass (compared to gray matter) most likely meningioma Focal or diffuse parenchymal low signal seen if calcified or highly fibrous CSF-vascular cleft Pial blood vessels seen as surface flow voids between tumor and brain High-signal crescent from CSF Tumor arterial feeders seen as arborizing flow voids High signal in adjacent brainstem or cerebellum Represents peritumoral brain edema Correlates with pial blood supply Signals problems with safe removal T2* GRE Calcifications may “bloom” T1WI C+ Enhancing dural-based mass with dural “tails” centered along posterior petrous wall > 95% enhance strongly Heterogeneous enhancement when large Dural “tail” in ˜ 60% Represents reactive rather than neoplastic change in most cases When extending into IAC, may mimic IAC component of vestibular schwannoma En plaque: Sessile thickened enhancing dura MRS ↑ alanine at short TE Triplet-like spectral pattern at 1.3-1.5 ppm (overlapping of alanine, lactate) ↑ Glx alfa/glutationine Angiographic Findings Digital subtraction angiography Dural vessels supply tumor center, pial vessels supply tumor rim “Sunburst” pattern: Enlarged dural feeders Prolonged vascular “stain” into venous phase Imaging Recommendations 1635 Diagnostic Imaging Head and Neck Best imaging tool Enhanced MR focused to posterior fossa Bone CT if bone invasion suspected on MR Protocol advice Full brain T2 ± FLAIR shows brain edema best DIFFERENTIAL DIAGNOSIS Vestibular Schwannoma Intracanalicular 1st, then CPA extension Intracanalicular meningioma may mimic Epidermoid Cyst, CPA-IAC Near CSF signal insinuating mass on MR DWI high signal characteristic Metastases, CPA-IAC May be bilateral in CPA area Multifocal meningeal involvement Sarcoidosis, CPA-IAC Often multifocal, dural-based foci Look for infundibular stalk involvement Idiopathic Inflammatory Pseudotumor, Skull Base Diffuse or focal meningeal thickening CPA involvement is rare Intracranial Trigeminal Schwannoma Ovoid, C+ mass centered in Meckel cave Primary CNS Lymphoma Rare intracranial lymphoma Focal, enhancing meningeal lesion P.VI(8):32 PATHOLOGY General Features Etiology Arises from arachnoid (“cap”) meningothelial cells Genetics Long arm deletions of chromosome 22 are common NF2 gene inactivated in 90% of sporadic cases May have progesterone, prolactin receptors; may express growth hormone Associated abnormalities Meningioma + schwannoma = NF2 Multiple meningiomas: 10% of sporadic cases Staging, Grading, & Classification WHO grading classification (grades I-III) Meningioma (classic, benign) = 90% Atypical meningioma = 9% Anaplastic (malignant) meningioma = 1% Gross Pathologic & Surgical Features “Mushroom cap” (hemispherical) morphology most common (75%) En plaque morphology (20%) also seen in CPA Sharply circumscribed, unencapsulated Adjacent dural thickening (collar or “tail”) is usually reactive, not neoplastic Microscopic Features Subtypes (wide range of histology with little bearing on imaging appearance or clinical outcome) Meningothelial (lobules of meningothelial cells) Fibrous (parallel, interlacing fascicles of spindle-shaped cells) Transitional (mixed; “onion-bulb” whorls and lobules) Psammomatous (numerous small calcifications) Angiomatous (↑ vascular channels), not equated with obsolete term “angioblastic meningioma” Miscellaneous forms (microcystic, chordoid, clear cell, secretory, lymphoplasmocyte-rich, etc.) CLINICAL ISSUES 1636 Diagnostic Imaging Head and Neck Presentation Most common signs/symptoms Incidental brain MR finding < 10% symptomatic Clinical profile Adult undergoing brain MR for unrelated indication Demographics Age Middle-aged, elderly; peak = 60 years old If found in children, consider possibility of NF2 Gender M:F = 1:4 Epidemiology Accounts for ˜ 20% of primary intracranial tumors 1-1.5% prevalence at autopsy or imaging 10% multiple (NF2; multiple meningiomatosis) 2nd most common CPA-IAC mass Natural History & Prognosis Slow-growing tumor Compresses rather than invades structures Negative prognostic findings on MR Peritumoral edema in adjacent brainstem Significant subjacent bone invasion Treatment Surgical removal if medically safe Complete surgical removal possible in 95% when tumor does not invade skull base Radiation therapy Adjunctive therapy with incomplete surgery Primary therapy if extensive skull base invasion DIAGNOSTIC CHECKLIST Consider Meningioma when MR shows hemispherical, dural-based enhancing CPA mass with dural “tails” Meningioma when CPA mass is large but asymptomatic Image Interpretation Pearls Focal or diffuse hypointensity on T2 in CPA mass suggests meningioma Dural “tail” in IAC suggests meningioma Reporting Tips Report extent of meningioma, including intraosseous component Mention cranial nerves in area of involvement Note any brainstem or brain edema indicating pia-arachnoid involvement SELECTED REFERENCES Takanashi M et al: Gamma knife radiosurgery for skull-base meningiomas Prog Neurol Surg 22:96-111, 2009 Thamburaj K et al: Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma AJNR Am J Neuroradiol 29(3):552-7, 2008 Zeidman LA et al: Growth rate of non-operated meningiomas J Neurol 255(6):891-5, 2008 Nakamura M et al: Facial and cochlear nerve function after surgery of cerebellopontine angle meningiomas Neurosurgery 57(1):77-90; discussion 77-90, 2005 Roche PH et al: Cerebellopontine angle meningiomas J Neurosurg 103(5):935-7; author reply 937-8, 2005 Roser F et al: Meningiomas of the cerebellopontine angle with extension into the internal auditory canal J Neurosurg 102(1):17-23, 2005 Nakamura M et al: Meningiomas of the internal auditory canal Neurosurgery 55(1):119-27; discussion 127-8, 2004 Asaoka K et al: Intracanalicular meningioma mimicking vestibular schwannoma AJNR Am J Neuroradiol 23(9):14936, 2002 Roberti F et al: Posterior fossa meningiomas: surgical experience in 161 cases Surg Neurol 56(1):8-20; discussion 20-1, 2001 10 Ildan F et al: Correlation of the relationships of brain-tumor interfaces, magnetic resonance imaging, and angiographic findings to predict cleavage of meningiomas J Neurosurg 91(3):384-90, 1999 P.VI(8):33 1637 Diagnostic Imaging Head and Neck Image Gallery (Left) Axial T1WI C+ MR demonstrates a large CPA meningioma with an IAC component This degree and depth of IAC enhancement usually signifies tumor rather than dural reaction (Right) Axial T2WI MR in the same patient reveals high signal in the adjacent brachium pontis Pial invasion by the meningioma is likely This MR finding is predictive of increased risk of complications when surgical removal occurs (Left) Axial T1WI C+ MR shows an enhancing intracanalicular mass Dural “tails” along the posterior margin of the porus acusticus suggest but not definitively diagnose meningioma (Right) Axial T2WI MR in the same patient reveals the intracanalicular meningioma as low signal tissue filling the IAC Often IAC meningioma cannot be reliably distinguished from IAC vestibular schwannoma, the most common lesion in this location 1638 Diagnostic Imaging Head and Neck (Left) Axial T2WI MR shows a parenchymal signal intensity meningioma abutting the posterior wall of the temporal bone Note the underlying dark signal of bony hyperostosis Despite the tumor abutting CN7-8 along the posterior margin of the porus acusticus, the patient did not have hearing loss (Right) Coronal T1WI C+ MR shows a large enhancing meningoma centered in the CPA Note that the IAC , middle ear , and jugular foramen are filled with enhancing tumor CPA-IAC Facial Nerve Schwannoma > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Benign and Malignant Tumors > CPA-IAC Facial Nerve Schwannoma CPA-IAC Facial Nerve Schwannoma H Ric Harnsberger, MD Key Facts Terminology Facial nerve schwannoma (FNS) FNS: Rare benign tumor of Schwann cells that line CPA-IAC CN7 Imaging Temporal bone CT findings ↑ size of labyrinthine CN7 canal ± geniculate fossa MR findings T1 C+ MR: CPA-IAC-labyrinthine canal enhancing mass ± intramural cystic change Top Differential Diagnoses Bell palsy (herpetic facial paralysis) Vestibular schwannoma CPA-IAC meningioma Pathology Tumor of Schwann cells lining CN7 Neurofibromatosis type Bilateral CPA-IAC schwannomas May be vestibular or facial nerve origin Clinical Issues Presentation: Sensorineural hearing loss ≈ facial nerve paralysis Conservative management: Do nothing until CN7 paralysis present Surgical management: Used when CN7 paralysis + other symptoms evolving Stereotactic radiosurgery: Used for poor surgical candidates May become first line of therapy 1639 Diagnostic Imaging Head and Neck (Left) Axial graphic of a larger facial nerve schwannoma shows CPA (ice cream) & IAC (cone) components that mimic acoustic schwannoma The labyrinthine segment of facial nerve involvement makes the diagnosis (Right) Axial T1WI C+ fat-saturated MR in a patient with unilateral sensorineural hearing loss shows FNS with CPA & IAC components Note the labyrinthine segment facial nerve “tail” , which differentiates FNS from vestibular schwannoma (Left) Axial T1WI C+ MR in a patient with mild facial paresis reveals an enhancing FNS that involves the CPA , IAC , labyrinthine segment facial nerve , and geniculate ganglion Without the labyrinthine segment and geniculate ganglion involvement, FNS would look exactly like vestibular schwannoma (Right) Coronal T1WI C+ fatsaturated MR demonstrates an enhancing FNS in the CPA and IAC The enlarged enhancing geniculate fossa confirms the diagnosis of FNS P.VI(8):35 TERMINOLOGY Abbreviations Facial nerve schwannoma (FNS) Synonyms Facial neuroma, facial neurilemmoma Definitions FNS: Rare benign tumor of Schwann cells that surround facial nerve in CPA-IAC IMAGING General Features Best diagnostic clue 1640 Diagnostic Imaging Head and Neck CPA-IAC mass + “tail” in labyrinthine CN7 canal Location CPA-IAC & labyrinthine segment CN7 canal Morphology Large: CPA-IAC “ice cream on ice cream cone” with comma-shaped “tail” Small: IAC mass curves into labyrinthine “tail” CT Findings Bone CT ↑ size labyrinthine CN7 canal ± geniculate fossa MR Findings T1WI C+ CPA-IAC-labyrinthine canal enhancing mass ± intramural cystic change CISS or FIESTA FNS CPA-IAC = mass displacing high signal CSF Imaging Recommendations Best imaging tool CN7 or CN8 symptoms 1st studied with contrast-enhanced T1 MR Axial ≤ mm T1 C+ MR; axial & coronal of CPA-IAC Bone CT: Verify MR suspicion of ↑ size labyrinthine CN7 DIFFERENTIAL DIAGNOSIS Bell Palsy (Herpetic Facial Paralysis) T1 C+ MR: Prominent enhancement of intratemporal CN7 with IAC fundal “tuft” Vestibular Schwannoma T1 C+ MR: CPA-IAC enhancing mass without labyrinthine canal “tail” CPA-IAC Meningioma T1 C+ MR: Dural-based, eccentric CPA enhancing mass with dural “tail” projecting into IAC PATHOLOGY General Features Etiology Tumor of Schwann cells investing CN7 Genetics Multiple schwannomas = NF2 Associated abnormalities Neurofibromatosis type Bilateral acoustic schwannoma Other schwannoma, meningiomas also seen Gross Pathologic & Surgical Features Tan, ovoid-tubular, encapsulated mass From outer nerve sheath layer Microscopic Features Encapsulated; bundles of spindle-shaped Schwann cells forming whorled pattern Cellular architecture: Densely cellular (Antoni A) areas ± loose, myxomatous (Antoni B) areas CLINICAL ISSUES Presentation Most common signs/symptoms Sensorineural hearing loss ≈ facial nerve paralysis Other symptoms: Vertigo, hemifacial spasm Demographics Age Average age at presentation ≈ 50 years Epidemiology Rare tumor (T-bone > CPA-IAC > parotid) Natural History & Prognosis CN7 paralysis takes years to develop Surgical cure can be worse than disease Treatment Conservative: Do nothing until CN7 paralysis present Some not grow 1641 Diagnostic Imaging Head and Neck Some never become symptomatic Surgery when CN7 paralysis + other symptoms evolving Goal: Complete tumor removal + preservation of hearing & restoration of CN7 function Stereotactic radiosurgery Evolving alternative to surgical therapy DIAGNOSTIC CHECKLIST Consider Thin section imaging shows labyrinthine “tail” Image Interpretation Pearls FNS CPA-IAC exactly mimics acoustic schwannoma if no labyrinthine “tail” present SELECTED REFERENCES Madhok R et al: Gamma knife radiosurgery for facial schwannomas Neurosurgery 64(6):1102-5; discussion 1105, 2009 Thompson AL et al: Magnetic resonance imaging of facial nerve schwannoma Laryngoscope 119(12):2428-36, 2009 McMonagle B et al: Facial schwannoma: results of a large case series and review J Laryngol Otol 122(11):1139-50, 2008 Wiggins RH 3rd et al: The many faces of facial nerve schwannoma AJNR Am J Neuroradiol 27(3):694-9, 2006 Salzman KL et al: Dumbbell schwannomas of the internal auditory canal AJNR Am J Neuroradiol 22(7):1368-76, 2001 CPA-IAC Metastases > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Benign and Malignant Tumors > CPA-IAC Metastases CPA-IAC Metastases H Ric Harnsberger, MD Key Facts Terminology CPA-IAC metastases: Systemic or CNS neoplasia affecting area of CPA-IAC Imaging major sites: Leptomeningeal, dura, flocculus, and choroid plexus T1WI C+ MR Leptomeningeal metastases: Diffuse thickening and enhancement of cranial nerves in IAC Dural metastases: Thickened enhancing dura ± dural nodules Floccular metastases: Enhancing floccular mass Choroid plexus metastases: Enhancing nodular lesion along normal course of choroid plexus Focal brain enhancing metastases may be present FLAIR MR Parenchymal brain metastases usually high signal Top Differential Diagnoses Bilateral vestibular schwannoma (NF2) Sarcoidosis, CPA-IAC Meningitis, CPA-IAC Ramsay Hunt syndrome Clinical Issues Rapidly progressive unilateral or bilateral CN7 and CN8 palsies Patient with past history of treated malignancy Diagnostic Checklist If trying to diagnose bilateral “vestibular schwannoma” in adult as NF2, probably CPA metastases instead Rapidly progressive 7th cranial nerve palsy + CPA mass suggests metastatic focus Vestibular schwannoma rarely causes CN7 palsy 1642 Diagnostic Imaging Head and Neck (Left) Axial graphic depicts the major types of CPA-IAC area metastases Along the posterolateral margin of the IAC, thickened dural metastases are visible Within the IAC metastatic leptomeningeal (pia-arachnoid) involvement is present Choroid plexus and floccular metastases are also depicted (Right) Axial T1WI C+ MR shows bilateral leptomeningeal breast carcinoma metastases within the internal auditory canals The left-sided disease is more subtle than the right (Left) Axial T2WI MR demonstrates right IAC leptomeningeal metastatic foci as thickening of the branches of CN7 and CN8 within the internal auditory canal (Right) Axial T2WI MR reveals left IAC metastatic disease as subtle thickening of the branches of CN7 and CN8 within the internal auditory canal In an adult patient with suspected “bilateral vestibular schwannoma,” consider metastatic disease rather than NF2 P.VI(8):37 TERMINOLOGY Abbreviations Metastases (mets) Synonyms Leptomeningeal carcinomatosis, meningeal carcinomatosis, carcinomatous meningitis All of above terms are misnomers 1st: Neoplasms are not always carcinomas 2nd: Pachymeninges (dura) and leptomeninges (pia + arachnoid) are often both involved 3rd: Usually does not contain inflammatory component (-itis suffix makes no sense) Definitions 1643 Diagnostic Imaging Head and Neck CPA-IAC metastases: Systemic or CNS neoplasia affecting area of CPA-IAC IMAGING General Features Best diagnostic clue Multiple enhancing masses on T1WI C+ MR Location major sites: Leptomeningeal (pia-arachnoid), dura, flocculus, and choroid plexus Primary site locations Primary tumors: Breast, lung, and melanoma Meningeal lymphoproliferative malignancy Lymphoma and leukemia Primary CNS tumor seeds basal cisterns via CSF pathways: “Drop” metastases Size Often small (< cm) Metastases cause symptoms early Morphology Leptomeningeal: Thickened CN7 and CN8 in IAC Dura: Diffuse dural thickening (pachymeninges) Flocculus: Enlarged flocculus with associated brain edema Choroid plexus: Nodular thickening CT Findings CECT Unilateral or bilateral dural enhancement along CPA and IAC CT shows metastases only when larger ± multiple MR Findings T1WI Focal dural thickening isointense to gray matter T2WI High-resolution T2 MR Leptomeningeal metastases: CN7 and CN8 thickening Floccular metastases: ↑ signal edema associated FLAIR Larger CPA-IAC metastases may cause ↑ signal in adjacent brainstem ± cerebellum Floccular metastases seen as ↑ signal T1WI C+ Leptomeningeal metastases: Diffuse thickening and enhancement of cranial nerves in IAC Late findings shows plug of enhancing tissue in IAC Unilateral or bilateral Dural metastases: Thickened enhancing dura ± dural nodules Associated with other dural or skull lesions Floccular metastases: Enhancing floccular mass Choroid plexus metastases: Enhancing nodular lesion along normal course of choroid plexus Lateral recess 4th ventricle → foramen of Luschka → inferior CPA cistern Focal brain enhancing metastases may be present Imaging Recommendations Best imaging tool T1WI C+ MR of posterior fossa is best imaging tool and sequence Whole brain FLAIR and T1WI C+ for associated brain metastases Protocol advice Axial and coronal planes recommended DIFFERENTIAL DIAGNOSIS Bilateral Vestibular Schwannoma (NF2) Younger patients; no history of malignancy T1WI C+ MR shows bilateral CPA-IAC enhancing masses Mimics bilateral leptomeningeal metastases Other cranial nerve schwannoma possible Sarcoidosis, CPA-IAC ↑ erythrocyte sedimentation rate (ESR) and serum angiotensin converting enzyme (ACE) T1WI C+ MR may be identical to metastases when multifocal meningeal type 1644 Diagnostic Imaging Head and Neck May be bilateral CPA lesions mimicking NF2 or metastases May be single, en plaque focus mimicking meningioma Look for infundibular stalk involvement Meningitis, CPA-IAC Bacterial meningitis Fungal meningitis Tuberculous meningitis T1WI C+ MR may be identical to CPA-IAC metastases Clinical information and cerebrospinal fluid (CSF) evaluation are key Ramsay Hunt Syndrome External ear vesicular rash T1WI C+ MR shows enhancement in IAC and inner ear ± 7th cranial nerve Mimics unilateral leptomeningeal metastasis PATHOLOGY General Features Etiology Metastatic tumor involves leptomeningeal or dural surfaces of CPA-IAC Leptomeningeal metastases follow CN7 and CN8 into IAC P.VI(8):38 Metastatic tumor deposits in flocculus or choroid plexus Routes of spread Extracranial neoplasm spreads hematogenously to meninges CSF spread from intracranial or intraspinal neoplasm is less common Associated abnormalities Multiple other pial or dural metastatic foci Parenchymal brain metastases also possible Key anatomy: Meninges has discrete layers Dura (pachymeninges): Dense connective tissue attached to calvarium Pia: Clear membrane firmly attaches to surface of brain; extends deeply into sulci Arachnoid: Interposed between pia and dura Pia + arachnoid = leptomeninges Gross Pathologic & Surgical Features Diffuse, nodular ± discrete Microscopic Features Common tissue types found Solid tumors = breast, lung, and melanoma All involve both leptomeninges and pachymeninges Lymphoproliferative malignancy = lymphoma and leukemia Involve both leptomeninges and pachymeninges “Drop” metastases from CNS tumors Medulloblastoma, ependymoma, glioblastoma multiforme CLINICAL ISSUES Presentation Most common signs/symptoms Rapidly progressive unilateral or bilateral CN7 and CN8 palsies Other signs/symptoms Vertigo and polycranial neuropathy Clinical profile Patient with past history of treated malignancy Demographics Age Older adults Epidemiology Increasingly more common neurologic complication of systemic cancer Due to increase in survival rate of cancer patients Natural History & Prognosis Meningeal metastases usually late-stage finding 1645 Diagnostic Imaging Head and Neck Poor prognosis as patients have advanced, incurable disease by definition Treatment No curative treatments available Therapies aimed at preserving neurologic function and improving quality of life Treatments are same as for underlying neoplasm Radiotherapy ± chemotherapy depending on tissue type Surgery will rarely play role at this stage Solitary melanoma metastases may be exception If any question of diagnosis, excisional biopsy necessary DIAGNOSTIC CHECKLIST Consider If trying to diagnose bilateral “vestibular schwannoma” in adult as NF2, probably CPA metastases instead Rapidly progressive 7th cranial nerve palsy + CPA mass suggests metastatic focus Vestibular schwannoma rarely causes CN7 palsy Image Interpretation Pearls If suspect CPA-IAC metastasis from T1WI C+ MR appearance or history of known malignancy, make sure to review Extracranial and calvarial structures for other lesions to confirm diagnosis Look for involvement of other meningeal sites, such as parasellar, other basal meninges Parenchymal brain for abnormal FLAIR high signal ± enhancing lesions on T1WI C+ sequences SELECTED REFERENCES Warren FM et al: Imaging characteristics of metastatic lesions to the cerebellopontine angle Otol Neurotol 29(6):835-8, 2008 Siomin VE et al: Posterior fossa metastases: risk of leptomeningeal disease when treated with stereotactic radiosurgery compared to surgery J Neurooncol 67(1-2):115-21, 2004 Soyuer S et al: Intracranial meningeal hemangiopericytoma: the role of radiotherapy: report of 29 cases and review of the literature Cancer 100(7):1491-7, 2004 Kesari S et al: Leptomeningeal metastases Neurol Clin 21(1):25-66, 2003 Krainik A et al: MRI of unusual lesions in the internal auditory canal Neuroradiology 43(1):52-7, 2001 Schick B et al: Magnetic resonance imaging in patients with sudden hearing loss, tinnitus and vertigo Otol Neurotol 22(6):808-12, 2001 Whinney D et al: Primary malignant melanoma of the cerebellopontine angle Otol Neurotol 22(2):218-22, 2001 Shen TY et al: Meningeal carcinomatosis manifested as bilateral progressive sensorineural hearing loss Am J Otol 21(4):510-2, 2000 Lewanski CR et al: Bilateral cerebellopontine metastases in a patient with an unknown primary Clin Oncol (R Coll Radiol) 11(4):272-3, 1999 10 Swartz JD: Meningeal metastases Am J Otol 20(5):683-5, 1999 11 Kingdom TT et al: Isolated metastatic melanoma of the cerebellopontine angle: case report Neurosurgery 33(1):142-4, 1993 12 Mark AS et al: Sensorineural hearing loss: more than meets the eye? AJNR Am J Neuroradiol 14(1):37-45, 1993 P.VI(8):39 Image Gallery 1646 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ MR reveals dural lung carcinoma metastases in the CPA region The enhancing, thickened dura should be distinguished from the enhancement in the normal sigmoid sinus CSF examination was positive for malignant cells (Right) Axial T1WI C+ FS MR shows an enhancing metastasis in the right IAC with extension of enhancing tissue through the cochlear nerve canal, across the modiolus into the membranous labyrinth of the cochlea (Left) Coronal T1WI C+ MR depicts an enhancing breast carcinoma metastasis centered within the right flocculus Note the normal flocculus and cisternal choroid plexus (Right) Axial FLAIR MR in the same patient shows the mass to be slightly lower in signal than the adjacent gray matter Vasogenic edema within the brachium pontis and cerebellum is seen as high signal The left flocculus is normal 1647 Diagnostic Imaging Head and Neck (Left) Axial T1WI C+ FS MR in a patient with known metastatic rectal carcinoma shows an enhancing metastasis the choroid plexus projecting into the low CPA cistern through the foramen of Luschka The normal right choroid plexus is seen (Right) Axial T1WI C+ FS reveals bilateral CPA-IAC “drop” metastases from a supratentorial glioblastoma multiforme Bilateral IAC enhancing metastases are seen along with multiple leptomeningeal metastases on surface of the cerebellum Vascular Lesions Trigeminal Neuralgia > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Vascular Lesions > Trigeminal Neuralgia Trigeminal Neuralgia Deborah R Shatzkes, MD Key Facts Terminology Vascular loop compressing trigeminal nerve at its root entry zone (REZ) along lateral pontine surface Imaging High-resolution T2WI MR shows serpiginous asymmetric signal void (vessel) in CPA CN5 REZ Offending vessels: Superior cerebellar artery > PICA > vertebral artery Top Differential Diagnoses Aneurysm, CPA-IAC Arteriovenous malformation, CPA Venous angioma, posterior fossa Pathology CN5 REZ experiences “irritation” from vessel Clinical Issues Trigeminal neuralgia symptoms Lancinating pain following V2 ± V3 distributions May occur spontaneously or in response to tactile stimulation Treatment Begin with conservative drug therapy Gamma-knife therapy (70% success) Microvascular decompression as needed Diagnostic Checklist Look for multiple sclerosis and cisternal masses Follow CN5 distally into cavernous sinus and face Exclude perineural tumor, malignancies of face Next view high-resolution thin section T2WI MR images for offending vessel Negative MR does not preclude surgical therapy 1648 of Diagnostic Imaging Head and Neck (Left) Axial T2WI MR in this patient with right trigeminal neuralgia shows the low signal superior cerebellar artery impinging on the root entry zone of the preganglionic segment of the trigeminal nerve (Right) Coronal T1WI MR in the same patient reveals the superior cerebellar artery compressing and deforming the right proximal preganglionic segment of CN5 Notice the larger normal left preganglionic CN5 indicating that atrophy is a feature of the affected right side (Left) Axial T2WI FS MR in patient with right trigeminal neuralgia reveals a multiple sclerosis lesion involving the lateral pons at the root entry zone of the trigeminal nerve Rarely cisternal masses or MS may present with trigeminal neuralgia (Right) Axial T1WI C+ MR in a patient with right TN shows a development venous anomaly of cerebellum draining through lateral pons and root entry zone of CN5 Less than 5% of patients with TN have a venous explanation for their symptoms P.VI(8):41 TERMINOLOGY Abbreviations Trigeminal neuralgia (TN) Synonyms Tic douloureux, trigeminal nerve vascular loop syndrome, trigeminal nerve hyperactive dysfunction syndrome Definitions Vascular loop compressing trigeminal nerve at its root entry zone (REZ) along lateral pontine surface IMAGING General Features Best diagnostic clue 1649 Diagnostic Imaging Head and Neck High-resolution T2WI MR shows serpentine asymmetric signal void (vessel) in CPA CN5 REZ TN offending vessels: Superior cerebellar artery (SCA) > PICA > vertebral artery CT Findings NECT: Most commonly normal MR Findings T2WI High-resolution T2 shows vessel compressing REZ of CN5 ± nerve atrophy FLAIR: Brainstem and brain are normal Multiple sclerosis (MS) may present with TN MRA: Source images most helpful Imaging Recommendations Best imaging tool High-resolution T2 for imaging of vascular loop DIFFERENTIAL DIAGNOSIS Aneurysm, CPA-IAC PICA or vertebral artery aneurysm Oval complex signal mass Rarely causes TN Arteriovenous Malformation, CPA Much larger vessels (arteries and veins) with nidus Rare in posterior fossa Venous Angioma, Posterior Fossa Larger vessels (veins) CPA rare as venous drainage route Rarely causes venous compression-induced TN PATHOLOGY General Features Etiology CN5 REZ vascular compression → atrophy Atrophy secondary to structural abnormalities Axonal loss and demyelination Atrophy → abnormal contacts among nerve fibers Abnormal contacts cause paroxysmal pain of TN Gross Pathologic & Surgical Features Offending vessel compresses REZ CN5 Microscopic Features Myelin cover of proximal CN5 is breached CLINICAL ISSUES Presentation Most common signs/symptoms Lancinating pain following V2 ± V3 distributions Spontaneous or in response to tactile stimulation Demographics Age Older patients (usually > 65 years) Epidemiology 5:100,000 Natural History & Prognosis Prognosis 70% pain-free 10 years after surgery Treatment Begin with conservative drug therapy Gamma-knife therapy (70% success) Microvascular decompression as needed DIAGNOSTIC CHECKLIST Consider Many normal vessels in CPA cistern Image Interpretation Pearls Look for MS and cisternal masses 1650 Diagnostic Imaging Head and Neck Follow CN5 distally into cavernous sinus and face Exclude perineural tumor, malignancies of face Next view T2 images for offending vessel Negative MR does not preclude surgical therapy SELECTED REFERENCES Fariselli L et al: CyberKnife radiosurgery as a first treatment for idiopathic trigeminal neuralgia Neurosurgery 64(2 Suppl):A96-101, 2009 Satoh T et al: Severity analysis of neurovascular contact in patients with trigeminal neuralgia: assessment with the inner view of the 3D MR cisternogram and angiogram fusion imaging AJNR Am J Neuroradiol 30(3):603-7, 2009 Sindou M et al: Microvascular decompression for primary trigeminal neuralgia: long-term effectiveness and prognostic factors in a series of 362 consecutive patients with clear-cut neurovascular conflicts who underwent pure decompression J Neurosurg 107(6):1144-53, 2007 Erbay SH et al: Nerve atrophy in severe trigeminal neuralgia: noninvasive confirmation at MR imaging—initial experience Radiology 238(2):689-92, 2006 Majoie CB et al: Trigeminal neuropathy: evaluation with MR imaging Radiographics 15(4):795-811, 1995 Hemifacial Spasm > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Vascular Lesions > Hemifacial Spasm Hemifacial Spasm H Ric Harnsberger, MD Key Facts Terminology Vascular loop compressing facial nerve at its root exit zone within CPA cistern causing hemifacial spasm Imaging High-resolution T2WI MR shows serpentine asymmetric signal void (vessel) in medial CPA Offending vessels: AICA (50%), PICA (30%), VA (15%), vein (5%) Top Differential Diagnoses Aneurysm, CPA-IAC Arteriovenous malformation, CPA Venous angioma, posterior fossa Pathology CN7 bundle experiences “irritation” from vessel Multiple sclerosis has been reported to cause HFS Cisternal masses, such as epidermoid or meningioma, may cause HFS Clinical Issues HFS: Unilateral involuntary facial spasms Begins with orbicularis oculi spasms Tonic-clonic bursts become constant over time Diagnostic Checklist Positive MR findings present in ˜ 50% HFS patients Look for cisternal mass lesions, multiple sclerosis Follow CN7 distally into T-bone and parotid Exclude CN7 hemangioma, parotid malignancy Next determine if source images for MRA or high-resolution T2WI images identify offending vessel Negative MR does not preclude surgical therapy 1651 Diagnostic Imaging Head and Neck (Left) Axial MRA source image in a patient with right hemifacial spasm shows a tortuous right vertebral artery and associated PICA pushing on the root exit zone of the facial nerve The facial nerve is visible in the CPA cistern (Right) Axial CISS MR through the CPA cisterns in a patient with right hemifacial spasm demonstrates a PICA loop pushing the cisternal CN7 and CN8 posteriorly, causing them to drape over the posterior margin of the porus acusticus (Left) Axial CISS MR in a patient with left hemifacial spasm reveals the left vertebral artery looping into the CPA cistern where it impinges on the proximal facial nerve at the root exit zone (Right) Axial T2WI MR reveals a dolichoectatic vertebral artery impinging on the root exit zone of the facial nerve in the medial CPA cistern in this patient with hemifacial spasm Approximately 50% of patients with hemifacial spasm have positive MR findings, typically on thin section T2 or MRA sequences P.VI(8):43 TERMINOLOGY Abbreviations Hemifacial spasm (HFS) Synonyms Facial nerve vascular loop syndrome, facial nerve hyperactive dysfunction syndrome Definitions Vascular loop compressing facial nerve at its root exit zone within CPA cistern causing hemifacial spasm IMAGING General Features Best diagnostic clue 1652 Diagnostic Imaging Head and Neck High-resolution T2WI MR shows serpentine asymmetric signal void (vessel) in medial CPA Location Loop in medial CPA cistern at CN7 root exit zone HFS offending vessels: AICA (50%), PICA (30%), VA (15%), vein (5%) CT Findings NECT: Most commonly normal MR Findings T2WI High-resolution T2WI: Vessel best seen as low signal tube coursing through high signal CSF FLAIR Adjacent brain most commonly normal Multiple sclerosis may present with HFS MRA: Source images most helpful Imaging Recommendations Best imaging tool Thin section high-resolution T2WI MR of CPA allows best vascular loop visualization DIFFERENTIAL DIAGNOSIS Aneurysm, CPA-IAC PICA or vertebral artery aneurysm Oval complex signal mass Arteriovenous Malformation, CPA Larger vessels (arteries and veins) with nidus Rare in posterior fossa Venous Angioma, Posterior Fossa Larger vessels (veins) CPA rare as venous drainage route Rarely causes venous compression with HFS PATHOLOGY General Features Etiology CN7 bundle experiences “irritation” from vessel Brainstem nuclei secondarily affected Abnormal brainstem response (ABR) Gross Pathologic & Surgical Features Offending vessel compresses root exit zone of CN7 Microscopic Features Myelin cover on proximal CN7 breached CLINICAL ISSUES Presentation Most common signs/symptoms HFS: Unilateral involuntary facial spasms Begins with orbicularis oculi spasms Tonic-clonic bursts become constant over time Demographics Age Older patients (usually > 65 years) Epidemiology < 1:100,000 Natural History & Prognosis 90% symptom free for ≥ years after surgery Treatment Begin with conservative drug therapy Microvascular decompression as needed DIAGNOSTIC CHECKLIST Consider Positive MR findings present in ˜ 50% of HFS patients Image Interpretation Pearls Look for cisternal mass lesions, multiple sclerosis Follow CN7 distally into T-bone and parotid 1653 Diagnostic Imaging Head and Neck Exclude CN7 hemangioma, parotid malignancy Next determine if source images for MRA or high-resolution T2WI images identify offending vessel Negative MR does not preclude surgical therapy SELECTED REFERENCES Huh R et al: Microvascular decompression for hemifacial spasm: analyses of operative complications in 1582 consecutive patients Surg Neurol 69(2):153-7; discussion 157, 2008 Kakizawa Y et al: Anatomical study of the trigeminal and facial cranial nerves with the aid of 3.0-tesla magnetic resonance imaging J Neurosurg 108(3):483-90, 2008 Lee MS et al: Clinical usefulness of magnetic resonance cisternography in patients having hemifacial spasm Yonsei Med J 42(4):390-4, 2001 Yamakami I et al: Preoperative assessment of trigeminal neuralgia and hemifacial spasm using constructive interference in steady state-three-dimensional Fourier transformation magnetic resonance imaging Neurol Med Chir (Tokyo) 40(11):545-55; discussion 555-6, 2000 Mitsuoka H et al: Delineation of small nerves and blood vessels with three-dimensional fast spin-echo MR imaging: comparison of presurgical and surgical findings in patients with hemifacial spasm AJNR Am J Neuroradiol 19(10):1823-9, 1998 CPA-IAC Aneurysm > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Vascular Lesions > CPA-IAC Aneurysm CPA-IAC Aneurysm H Ric Harnsberger, MD Key Facts Terminology Focal ballooning or fusiform dilatation of posterior inferior cerebellar artery (PICA), vertebral artery (VA), or anterior inferior cerebellar artery (AICA) in CPA-IAC cistern Imaging CPA mass with calcified rim (CT) or layered complex signal in wall (MR) CECT of partially thrombosed aneurysm Complex mass with central or eccentric enhancing lumen, nonenhancing mural thrombus Often has calcified rim CTA: Shows neck & originating artery (PICA, VA, AICA) MR findings MR complex signal from Ca++, clot, flow T1: Subacute luminal clot is hyperintense secondary to methemoglobin T1 shortening T2: Signal varies from hypointense “flow void” to complex mixed signal appearance Angio: Visible lumen may be smaller than overall aneurysm if clot is present Angiogram may underestimate aneurysm size Top Differential Diagnoses Vertebrobasilar dolichoectasia Dural AV fistula + venous varix Arteriovenous malformation Clinical Issues Symptoms: Sensorineural hearing loss (70%) Headache from subarachnoid hemorrhage (50%) Hemifacial spasm or facial nerve palsy Treatment: Endovascular coiling vs surgical clipping 1654 Diagnostic Imaging Head and Neck (Left) Axial T1WI shows a tubular hyperintense mass extending laterally from the basilar artery into the CPA cistern The more medial portion of the mass shows complex signal from flow and subacute clot while the more lateral component is completely thrombosed and filled with high signal subacute clot (Right) Axial T2WI MR in the same patient reveals the patent PICA-AICA complex takeoff from the basilar artery with area of partial & complete thrombosis of the aneurysm (Left) Axial CTA image through the IAC demonstrates a focal area of enhancement on the posterior margin of the porus acusticus (Right) Anteroposterior left vertebral angiogram in the same patient demonstrates the anterior inferior cerebellar artery (AICA) aneurysm looping into the vicinity of the internal auditory canal AICA aneurysm in the CPA-IAC is the rarest of the aneurysms affecting the CPA-IAC area P.VI(8):45 TERMINOLOGY Definitions Focal ballooning or fusiform dilatation of posterior inferior cerebellar artery (PICA), vertebral artery (VA), or anterior inferior cerebellar artery (AICA) in CPA-IAC cistern IMAGING General Features Best diagnostic clue CPA mass with calcified rim (CT) or layered complex signal in wall (MR) Location CPA aneurysms from PICA > VA > AICA Size 1655 Diagnostic Imaging Head and Neck Millimeters to centimeters Morphology Round, ovoid, or fusiform shaped CT Findings CECT Patent aneurysm Well-delineated iso- to hyperdense extraaxial mass with strong, uniform enhancement Partially thrombosed aneurysm Complex mass with central or eccentric enhancing lumen, nonenhancing mural thrombus Often has calcified rim Completely thrombosed aneurysm No enhancing lumen CTA Shows neck & originating artery (PICA, VA, AICA) MR Findings T1WI Subacute luminal clot is hyperintense secondary to methemoglobin T1 shortening T2WI Phase artifact across from patent aneurysm common Signal varies from hypointense “flow void” to complex mixed signal appearance Varies with flow rate & age of luminal thrombus Complex signal from Ca++, clot, flow T2* GRE Calcified wall & luminal clot may “bloom” T1WI C+ Aneurysm lumen enhances if slow flow present MRA May delineate relationship with parent vessel Angiographic Findings Visible lumen may be smaller than overall aneurysm if clot is present Angiogram may underestimate aneurysm size Angiography delineates precise vascular relationships Imaging Recommendations Best imaging tool Once CT or MR suggests aneurysm, confirm with CTA or angiography DIFFERENTIAL DIAGNOSIS Vertebrobasilar Dolichoectasia MRA reprojections or source images show no aneurysm Dural AV Fistula + Venous Varix Angio delineates best MR venography may help delineate Arteriovenous Malformation Large feeding arteries + nidus PATHOLOGY General Features Etiology Inherited factors + hemodynamic-induced degenerative changes in vessel wall often combine to form aneurysm Gross Pathologic & Surgical Features Saccular: Berry-like outpouching of artery wall Fusiform: Enlarged, ectatic atherosclerotic artery Microscopic Features Lacks internal elastic lamina, smooth muscle layers CLINICAL ISSUES Presentation Most common signs/symptoms Unilateral sensorineural hearing loss (SNHL) (70%) Other signs/symptoms Headache from subarachnoid hemorrhage (50%) 1656 Diagnostic Imaging Head and Neck Hemifacial spasm or facial nerve palsy Demographics Age 40-60 years Epidemiology CPA aneurysms account for ≤ 1% CPA masses 10% of all intracranial aneurysms are vertebrobasilar Natural History & Prognosis Larger aneurysms rupture more frequently Left unclipped, aneurysm rupture “growing” possibility Treatment Endovascular coiling vs surgical clipping SELECTED REFERENCES Chihara Y et al: Fusiform aneurysm of the basilar artery presenting as a cerebellopontine angle mass Eur Arch Otorhinolaryngol 266(1):151-2, 2009 Sun Y et al: Ruptured intrameatal AICA aneurysms— a report of two cases and review of the literature Acta Neurochir (Wien) 151(11):1525-30, 2009 Bonneville F et al: Unusual lesions of the cerebellopontine angle: a segmental approach Radiographics 21(2):41938, 2001 Kinney WC et al: Rare lesions of the posterior fossa with initial retrocochlear auditory and vestibular complaints Am J Otol 18(3):373-80, 1997 CPA-IAC Superficial Siderosis > Table of Contents > Part VI - Temporal Bone and CPA-IAC > Section - CPA-IAC > Vascular Lesions > CPA-IAC Superficial Siderosis CPA-IAC Superficial Siderosis H Ric Harnsberger, MD Key Facts Terminology Superficial siderosis: Recurrent subarachnoid hemorrhage (SAH) causes hemosiderin deposition on surface of brain, brainstem, and cranial nerve leptomeninges Imaging Nonenhanced CT findings Slightly hyperdense rim over brain surface Brainstem high-density line most evident Caveat: Do not mistake high-density rim on brain surfaces as subarachnoid hemorrhage! MR findings In diffuse disease, ventricle surfaces, brain, brainstem, cerebellum, and cervical spine all have hypointense hemosiderin rim Contours of brain and cranial nerves outlined by hypointense rim on T2 or T2* GRE MR images CN8 appears darker and thicker than normal GRE: Most sensitive to hemosiderin deposition on CNS surfaces (“blooming” dark signal) Once diagnosis of SS is made, search for cause of recurrent SAH must commence Whole brain MR with contrast and MRA Total spine MR if brain negative for underlying lesion Pathology Repeated SAH deposits hemosiderin on meningeal lining of CNS Affects brain, brainstem, cerebellum, cranial nerves, and spinal cord Causes of recurrent SAH Traumatic nerve root avulsion Bleeding CNS neoplasm Vascular malformations and aneurysms Surgical sites (brain or spine) 1657 Diagnostic Imaging Head and Neck (Left) Axial graphic shows darker brown hemosiderin staining on all surfaces of the brain, meninges, and cranial nerves Notice that cranial nerves and in the cerebellopontine angle-internal auditory canal are particularly affected (Right) Axial T2WI MR reveals superficial siderosis in the posterior fossa Both vestibulocochlear nerves (CN8) are seen as very low signal lines in the cerebellopontine angle cisterns Also observe low signal along the surface of the cerebellar folia (Left) Axial NECT demonstrates findings of superficial siderosis as a high-density right vestibulocochlear nerve CT is often normal in patients with this disease as the fine siderosis coating on the cranial nerves, brain, and brainstem may not be dense enough to see (Right) Axial NECT in this patient with superficial siderosis shows linear high density along the surface of the midbrain This is not an artifact or subarachnoid hemorrhage but hemosiderin deposition on the surface of the midbrain P.VI(8):47 TERMINOLOGY Abbreviations Superficial siderosis (SS) Synonyms Siderosis, central nervous system siderosis Definitions Recurrent subarachnoid hemorrhage (SAH) causes hemosiderin deposition on surface of brain, brainstem, and cranial nerve (CN) leptomeninges IMAGING General Features 1658 Diagnostic Imaging Head and Neck Best diagnostic clue Contours of brain and cranial nerves outlined by hypointense rim on T2 or T2* GRE MR images Location Cerebral hemispheres, cerebellum, brainstem, cranial nerves, and spinal cord may all be affected Size Linear low signal along CNS surfaces varies in thickness but usually ≤ mm Morphology Curvilinear dark lines on CNS surfaces CT Findings NECT Cerebral and cerebellar atrophy Especially marked in posterior fossa Cerebellar sulci often disproportionately large CN8 may be hyperdense Slightly hyperdense rim over brain surface Brainstem changes most evident CT relatively insensitive to SS compared to MR Caveat: Do not mistake high-density rim on brain surfaces as subarachnoid hemorrhage! CECT No enhancement typical MR Findings T1WI Hyperintense signal may be seen on CNS surfaces T2WI High-resolution, thin section T2 MR of CPA-IAC CN8 appears hypointense, thicker than normal Adjacent cerebellar structures and brainstem show low signal surfaces Less easily seen than on T2* GRE images In diffuse disease, ventricle, brain, brainstem, cerebellum, and cervical spine surfaces all have hypointense hemosiderin rim Vermian and cerebellar atrophy most prominent FLAIR Dark border on local surface of brain, brainstem, cerebellum, and cranial nerves T2* GRE More sensitive to hemosiderin deposition on CNS surfaces than T2 sequence “Blooming” dark signal Makes SS appear more conspicuous, thicker T1WI C+ Surface of CNS does not enhance MR findings not correlate with severity of disease Imaging Recommendations Best imaging tool Brain MR with posterior fossa focus Once diagnosis of SS is made, search for cause of recurrent SAH must commence Whole brain MR with contrast and MRA Then total spine MR if brain negative for underlying lesion Protocol advice Brain MR Unenhanced MR with FLAIR initially If SS suspected, add T2* GRE sequences to confirm DIFFERENTIAL DIAGNOSIS “Bounce Point” Artifact Mismatch between repetition time (TR) and inversion time (TI) on inversion recovery T1 and FLAIR sequences Imaging clue: Not present on all sequences Brain Surface Vessels Normal or abnormal surface veins Linear, focal area of low signal on brain surface Neurocutaneous Melanosis Congenital syndrome 1659 Diagnostic Imaging Head and Neck Large or multiple congenital melanocytic nevi Benign or malignant pigment cell tumors of leptomeninges may be low signal on surface of brain T1 high signal diffusely in pia-arachnoid T2 low signal diffusely in pia-arachnoid Meningioangiomatosis Hamartomatous proliferation of meningeal cells via intraparenchymal blood vessels into cerebral cortex Leptomeninges are thick and infiltrated with fibrous tissue May be calcified PATHOLOGY General Features Etiology Repeated SAH deposits hemosiderin on meningeal lining of CNS Affects brain, brainstem, cerebellum, cranial nerves, and spinal cord Hemosiderin is cytotoxic to neurons “Free” iron with excess production of hydroxyl radicals is best current hypothesis explaining cytotoxicity CN8 is extensively lined with CNS myelin, which is supported by hemosiderin-sensitive microglia Increased exposure in CPA cistern Associated abnormalities Causes of recurrent SAH Traumatic nerve root avulsion Bleeding CNS neoplasm Arteriovenous or cavernous malformation Aneurysm P.VI(8):48 Intradural surgical sites (brain or spine) Hemosiderin staining of meninges Gross Pathologic & Surgical Features Dark brown discoloration of leptomeninges, ependyma, and subpial tissue Causes of recurrent SAH found in ˜ 70% Dural pathology (70%) Traumatic cervical nerve root avulsion CSF cavity lesion (surgical cavity) with “fragile” neovascularity most common Bleeding neoplasms (20%) Ependymoma, oligodendroglioma, astrocytoma, etc Vascular abnormalities (10%) Arteriovenous malformation (AVM) or aneurysm Multiple cavernous malformations near brain surface Microscopic Features Hemosiderin staining of meninges & subpial tissues to mm depth Thickened leptomeninges Cerebellar folia: Loss of Purkinje cells and Bergmann gliosis CLINICAL ISSUES Presentation Most common signs/symptoms Bilateral sensorineural hearing loss (SNHL) in 95% Clinical profile Past history of trauma or intradural surgery common Past history of SAH rare Classic presentation is adult patient with bilateral SNHL and ataxia Seen less commonly as late complication of treated childhood cerebellar tumor Laboratory CSF from lumbar puncture High protein (100%) Xanthochromic (75%) Other symptoms Ataxia (88%) 1660 Diagnostic Imaging Head and Neck Bilateral hemiparesis Hyperreflexia, bladder disturbance, anosmia, dementia, & headache Presymptomatic phase averages 15 years Demographics Age Broad range: 14-77 years Gender M:F = 3:1 Epidemiology Rare chronic progressive disorder 0.15% of patients undergoing MR Natural History & Prognosis Bilateral worsening SNHL and ataxia within 15 years of onset Deafness almost certain if unrecognized 25% bedridden in years after 1st symptom Result of cerebellar ataxia, myelopathic syndrome, or both Treatment Treat source of bleeding Surgically remove source of bleeding (surgical cavity, tumor) Endovascular therapy for AVM and aneurysm Cochlear implantation for SNHL DIAGNOSTIC CHECKLIST Consider Remember that SS is effect, not cause Look for source of recurrent SAH in spine or brain MR findings not correlate with severity of patient's symptoms MR diagnosis may be made in absence of symptoms Image Interpretation Pearls CNS surfaces including cranial nerves appear “outlined in black” on T2 MR Reporting Tips Describe individual findings of SS Describe any possible sites of chronic SAH If no site of SAH visible, recommend full spine MR in search of SAH site Treatment of SAH site may arrest progression of associated symptoms SELECTED REFERENCES Koeppen AH et al: The pathology of superficial siderosis of the central nervous system Acta Neuropathol 116(4):371-82, 2008 Kumar N: Superficial siderosis: associations and therapeutic implications Arch Neurol 64(4):491-6, 2007 Kumar N et al: Superficial siderosis Neurology 66(8):1144-52, 2006 Dhooge IJ et al: Cochlear implantation in a patient with superficial siderosis of the central nervous system Otol Neurotol 23(4):468-72, 2002 Hsu WC et al: Superficial siderosis of the CNS associated with multiple cavernous malformations AJNR Am J Neuroradiol 20(7):1245-8, 1999 Lemmerling M et al: Secondary superficial siderosis of the central nervous system in a patient presenting with sensorineural hearing loss Neuroradiology 40(5):312-4, 1998 Castelli ML et al: Superficial siderosis of the central nervous system: an underestimated cause of hearing loss J Laryngol Otol 111(1):60-2, 1997 Offenbacher H et al: Superficial siderosis of the central nervous system: MRI findings and clinical significance Neuroradiology 38 Suppl 1:S51-6, 1996 Bracchi M et al: Superficial siderosis of the CNS: MR diagnosis and clinical findings AJNR Am J Neuroradiol 14(1):227-36, 1993 P.VI(8):49 Image Gallery 1661 Diagnostic Imaging Head and Neck (Left) Months after the surgical removal of a frontal lobe melanoma metastasis in this patient, axial T2WI MR shows the surgical cavity and subtle low signal lining the sulci and sylvian fissures , secondary to superficial siderosis (Right) Axial T2* GRE MR in the same patient demonstrates much more obvious siderosis involving the sylvian fissures and sulci GRE T2* sequences cause hemosiderin deposits to “bloom,” increasing the conspicuity of this disease (Left) Axial T1WI C+ FS MR in the same patient reveals focal areas of enhancement in the surgical cavity These are granulation tissue foci along the margin of the surgical site that likely continue to chronically ooze blood, causing superficial siderosis (Right) Axial T2WI MR in a patient with cervical trauma shows interruption of hemosiderin hypointense rim due to the absence of spinal cord pia mater at the root avulsion site Note the pseudomeningocele (Courtesy N Kumar, MD.) 1662 Diagnostic Imaging Head and Neck (Left) Axial T2WI MR reveals the “popcorn ball” appearance of a classic Zabramski type cavernous malformation A complete hemosiderin rim surrounds the lesion as a hypointense line (Right) Coronal T2* GRE in the same patient demonstrates extensive superficial siderosis in the posterior fossa “Blooming” of the hemosiderin on the surfaces is seen as a hypointense outline The superior vermis as well as the cerebellar folia are involved 1663 Diagnostic Imaging Head and Neck Index A Aberrant arachnoid granulations See Dural sinus, and aberrant arachnoid granulations Aberrant internal carotid artery See Carotid artery, aberrant internal Abscess acute otomastoiditis with abscess, VI(3):18, VI(3):19, VI(3):20, VI(3):21, VI(3):22 differential diagnosis, VI(3):19 temporal bone rhabdomyosarcoma vs., VI(3):55, VI(3):56 1st branchial cleft cyst vs., III(1):25 2nd branchial cleft cyst vs., III(1):29 3rd branchial cleft cyst vs., III(1):33 cerebral, as complications of rhinosinusitis, IV(1):38 cervical thymic cyst vs., III(1):21 intranodal See Lymph nodes, suppurative lymphatic malformation vs., III(1):7 masticator space See Masticator space, abscess oral cavity See Oral cavity, abscess pediatric dermoid/epidermoid cyst vs., III(1):41 retropharyngeal space See Retropharyngeal space, abscess subperiosteal orbital, IV(2):34, IV(2):35, IV(2):36, IV(2):37 cellulitis vs., IV(2):39 differential diagnosis, IV(2):35 postseptal, IV(1):37, IV(1):38 supraglottitis with abscess, laryngocele vs., I(11):26 tonsillar/peritonsillar, I(3):12, I(3):13 differential diagnosis, I(3):13 palatine tonsil squamous cell carcinoma vs., II(2):11 post-transplantation lymphoproliferative disorder vs., I(13):15 tonsillar inflammation vs., I(3):11 Absent cochlea See Cochlear aplasia Accessory salivary tissue, submandibular space, I(14):10, I(14):11 Achalasia, esophagopharyngeal diverticulum vs., I(10):39 Achondroplasia, mucopolysaccharidosis vs., III(2):25 Acinic cell carcinoma See Lacrimal gland carcinoma Acoustic neurofibromatosis, bilateral See Neurofibromatosis type Acoustic neuroma See Vestibular schwannoma Acoustic schwannoma See Vestibular schwannoma Adamantoblastoma See Ameloblastoma Adenitis See Lymph nodes, suppurative Adenocarcinoma lacrimal gland See Lacrimal gland carcinoma sinonasal, IV(1):98, IV(1):99 adenoid cystic carcinoma vs., IV(1):107 differential diagnosis, IV(1):99 esthesioneuroblastoma vs., IV(1):95 non-Hodgkin lymphoma vs., IV(1):103 squamous cell carcinoma vs., IV(1):91 staging, grading, & classification, IV(1):99 undifferentiated carcinoma vs., IV(1):106 Adenoid cystic carcinoma lacrimal gland See Lacrimal gland carcinoma laryngeal subglottic laryngeal SCCa vs., II(2):41 supraglottic laryngeal SCCa vs., II(2):35 parotid space, I(5):32, I(5):33 differential diagnosis, I(5):33 parotid mucoepidermoid carcinoma vs., I(5):29 parotid space malignant mixed tumor vs., I(5):35 staging, grading, & classification, I(5):33 sinonasal, IV(1):107 Adenoidal benign lymphoid hyperplasia, nasopharyngeal carcinoma vs., II(2):3 Adenoidal inflammation, Tornwaldt cyst vs., I(3):7 Adenoma middle ear, VI(3):52, VI(3):53 differential diagnosis, VI(3):53 middle ear schwannoma vs., VI(3):51 parathyroid, I(10):16, I(10):17, I(10):18, I(10):19 differential diagnosis, I(10):17 parathyroid carcinoma vs., I(10):35 pediatric neurofibromatosis type associated with, III(2):4 thyroid adenoma vs., I(10):13 pleomorphic carcinoma ex pleomorphic adenoma See Parotid malignant mixed tumor lacrimal gland See Lacrimal gland benign mixed tumor; Lacrimal gland carcinoma palate See Palate benign mixed tumor parapharyngeal space See Parapharyngeal space, benign mixed tumor P.ii parotid space See Parotid benign mixed tumor 1664 submandibular See Submandibular gland, benign mixed tumor thyroid See Thyroid adenoma Adenomatous tumor of endolymphatic sac See Endolymphatic sac tumor Adenopathy due to Mycobacterium tuberculosis See Tuberculous lymph nodes reactive See Lymph nodes, reactive suppurative See Lymph nodes, suppurative Aggressive fibromatosis See Fibromatosis of head and neck AIDS nodal non-Hodgkin lymphoma associated with neck, I(12):29 submandibular space, I(14):43 parotid cysts related to See Lymphoepithelial lesions-HIV, benign Albers-Schönberg disease See Osteopetrosis, skull base Alcohol abuse See Tobacco and alcohol abuse Aldosteronoma See Adenoma, middle ear Allergic fungal sinusitis See Fungal sinusitis, allergic Allergies acute rhinosinusitis associated with, IV(1):29 chronic rhinosinusitis associated with, IV(1):34 sinonasal polyposis associated with, IV(1):50 Alveolar nerve canal, inferior, mandible fracture vs., V(2):27 Alveolar ridge squamous cell carcinoma, II(2):22, II(2):23 differential diagnosis, II(2):23 osteoradionecrosis of mandible-maxilla vs., I(15):41 staging, grading, & classification, II(2):23 Alveolar soft part sarcoma, tongue, squamous cell carcinoma vs., II(2):17 Ameloblastoma, I(15):30, I(15):31, I(15):32, I(15):33 basal cell nevus syndrome vs., III(2):9 clinical issues, I(15):32 CNV3 schwannoma of masticator space vs., I(4):19 dentigerous cyst vs., I(15):15 differential diagnosis, I(15):31, I(15):32 giant cell granuloma of mandiblemaxilla vs., I(15):29 imaging, I(15):31, I(15):33 keratocystic odontogenic tumor vs., I(15):35 pathology, I(15):32 unicystic, simple (traumatic) bone cyst vs., I(15):17 Anaplastic thyroid carcinoma See Thyroid carcinoma, anaplastic Diagnostic Imaging Head and Neck Aneurysm carotid artery petrous ICA, VI(5):22, VI(5):23 aberrant internal carotid artery vs., VI(3):13, VI(3):14 cholesterol granuloma vs., VI(5):15 congenital cholesteatoma vs., VI(5):7 differential diagnosis, VI(5):23 lateralized internal carotid artery vs., VI(3):11 CPA-IAC, VI(8):44, VI(8):45 congenital CPA-IAC lipoma vs., VI(8):15 differential diagnosis, VI(8):45 hemifacial spasm vs., VI(8):43 trigeminal neuralgia vs., VI(8):41 vestibular schwannoma vs., VI(8):27 pseudoaneurysm See Carotid artery, pseudoaneurysm, in neck Aneurysmal bone cyst giant cell granuloma of mandiblemaxilla vs., I(15):29 mandible-maxilla, ameloblastoma vs., I(15):32 simple bone cyst (traumatic) vs., I(15):17 skull base fibrous dysplasia associated with, V(1):62 skull base giant cell tumor vs., V(1):77 Angiofibroma, juvenile See Juvenile angiofibroma Angiofollicular lymphoid hyperplasia See Giant lymph node hyperplasia (Castleman) Angiolipoma, I(13):8 Angiomatous lymphoid hamartoma See Giant lymph node hyperplasia (Castleman) Angiomatous polyp, sinonasal hemangioma vs., IV(1):87 Aniridia, coloboma associated with, IV(2):8 Anterior visual pathway glioma See Optic pathway glioma Antrochoanal polyp, juvenile angiofibroma vs., IV(1):80 Apert syndrome, globular vestibulesemicircular canal vs., VI(4):26 Apical periodontitis nasopalatine duct cyst vs., I(15):19 periapical (radicular) cyst vs., I(15):13 Apical petrositis See Petrositis, apical Arachnoid cyst CPA, VI(8):10, VI(8):11, VI(8):12, VI(8):13 clinical issues, VI(8):12 differential diagnosis, VI(8):11 epidermoid cyst vs., VI(8):7 imaging, VI(8):11, VI(8):13 pathology, VI(8):11, VI(8):12 vestibular schwannoma vs., VI(8):27 petrous apex See Petrous apex, cephalocele skull base, ecchordosis physaliphora vs., V(1):9 Arachnoid granulations aberrant See Dural sinus, and aberrant arachnoid granulations temporal bone, VI(7):4, VI(7):5 cephalocele vs., VI(3):59 differential diagnosis, VI(7):5 P.iii Warthin tumor associated with, I(5):24 Automastoidectomy See Mural cholesteatoma Avascular bone necrosis See Osteoradionecrosis Arcus senilis, orbital foreign body vs., V(2):15 Arteriovenous malformation CPA, trigeminal neuralgia vs., VI(8):41 CPA-IAC aneurysm vs., VI(8):45 hemifacial spasm vs., VI(8):43 infantile hemangioma vs., III(1):48 venous malformation vs., III(1):12 Arthritis juvenile idiopathic, temporomandibular joint, I(15):20, I(15):21 rheumatoid See Rheumatoid arthritis Artifacts “bounce point,” CPA-IAC superficial siderosis vs., VI(8):47 MRA motion artifact, carotid artery fibromuscular dysplasia vs., I(6):15 Aryepiglottic fold squamous cell carcinoma See Laryngeal squamous cell carcinoma, supraglottic Asthma chronic rhinosinusitis associated with, IV(1):34 Kimura disease associated with, I(12):26 sinonasal polyposis associated with, IV(1):50 Astrocytoma cerebellar pilocytic, arachnoid cyst of CPA vs., VI(8):11 plexiform neurofibroma of head and neck associated with, I(13):13 Atherosclerosis, extracranial acute idiopathic carotidynia vs., I(6):17 carotid artery fibromuscular dysplasia vs., I(6):15 vertebral artery dissection in neck vs., I(8):15 “Attic” space cholesteatoma See Pars flaccida cholesteatoma Auditory canal See CPA-IAC; External auditory canal Autoimmune disorders histiocytic necrotizing lymphadenitis associated with, I(12):23 medial canal fibrosis associated with, VI(2):12 orbital idiopathic inflammatory pseudotumor associated with, IV(2):42 parotid non-Hodgkin lymphoma associated with, I(5):38 Parotid Sjögren syndrome associated with, I(5):12 sinus histiocytosis of head and neck associated with, I(13):31 thyroid ophthalmopathy associated with, IV(2):48 Basal cell nevus syndrome, III(2):8, III(2):9 Basal cephalocele See Skull base, cephalocele Basal medial canal, persistent, persistent craniopharyngeal canal vs., V(1):17 Base of tongue cyst See Vallecular cyst, congenital squamous cell carcinoma See Lingual tonsil squamous cell carcinoma Basicranial chordoma See Chordoma Basipharyngeal canal See Craniopharyngeal canal, persistent Bell palsy, VI(6):6, VI(6):7, VI(6):8, VI(6):9 Brackman facial nerve grading system, VI(6):8 clinical issues, VI(6):8 differential diagnosis, VI(6):7 facial nerve enhancement vs., VI(6):3 facial nerve schwannoma vs., VI(8):35 imaging, VI(6):7, VI(6):9 pathology, VI(6):7, VI(6):8 perineural parotid malignancy vs., VI(6):19 persistent stapedial artery vs., VI(3):17 Ramsay Hunt syndrome vs., VI(8):23 schwannoma vs., VI(6):15 venous malformation (hemangioma) vs., VI(6):11 Benign mixed tumor lacrimal gland See Lacrimal gland benign mixed tumor palate, I(14):34, I(14):35 differential diagnosis, I(14):35 hard palate SCCa vs., II(2):27 minor salivary gland malignancy vs., I(14):41 palatine tonsil, squamous cell carcinoma vs., II(2):11 parapharyngeal space, I(2):4, I(2):5 parotid See Parotid benign mixed tumor pharyngeal mucosa See Pharyngeal mucosal space, benign mixed tumor sinonasal, IV(1):89 differential diagnosis, IV(1):89 nerve sheath tumor vs., IV(1):88 Bisphosphonate osteonecrosis See Osteonecrosis, mandible-maxilla Blue-dome cyst See Cholesterol granuloma, middle ear Bone cyst aneurysmal See Aneurysmal bone cyst simple (traumatic), I(15):16, I(15):17 “Bounce point” artifact, CPA-IAC superficial siderosis vs., VI(8):47 1665 B Diagnostic Imaging Head and Neck Brachial plexus schwannoma, perivertebral space, I(8):16, I(8):17 chordoma in perivertebral space vs., I(8):19 differential diagnosis, I(8):17 Brain surface vessels, CPA-IAC superficial siderosis vs., VI(8):47 P.iv Branchial apparatus lesions differential diagnosis, III(1):3 overview, III(1):2, III(1):3 Branchial cleft anomaly 1st, infected, acute parotitis vs., I(5):7 2nd lymphatic malformation vs., III(1):7 non-tuberculous mycobacterium vs., I(12):16 ranula vs., I(14):21 suppurative lymph nodes vs., I(12):11 3rd, posterior cervical space schwannoma vs., I(9):5 4th cervical thymic cyst vs., III(1):21 prominent thoracic duct vs., I(13):5 Branchial cleft cyst 1st, III(1):24, III(1):25, III(1):26, III(1):27 benign lymphoepithelial lesions-HIV vs., I(5):15 clinical issues, III(1):26 differential diagnosis, III(1):25 imaging, III(1):25, III(1):27 pathology, III(1):26 2nd, III(1):28, III(1):29, III(1):30, III(1):31 3rd branchial cleft cyst vs., III(1):33 benign mixed tumor of parapharyngeal space vs., I(2):5 cervical thymic cyst vs., III(1):21 clinical issues, III(1):30 differential diagnosis, III(1):29 HPV-related oropharyngeal SCCa vs., II(2):15 imaging, III(1):29, III(1):31 laryngocele vs., I(11):25 lymphocele of neck vs., I(13):29 nodal SCCa vs., II(2):47 pathology, III(1):29, III(1):30 submandibular space nodal squamous cell carcinoma vs., I(14):45 3rd, III(1):32, III(1):33, III(1):34, III(1):35 4th branchial cleft cyst vs., III(1):37 clinical issues, III(1):34 differential diagnosis, III(1):33, III(1):34 imaging, III(1):33, III(1):35 pathology, III(1):34 4th, III(1):36, III(1):37, III(1):38, III(1):39 3rd branchial cleft cyst vs., III(1):33 clinical issues, III(1):38 differential diagnosis, III(1):37 imaging, III(1):37, III(1):39 pathology, III(1):37, III(1):38 pyriform sinus squamous cell carcinoma vs., II(2):29 Branchiootic syndrome branchiootorenal syndrome vs., III(2):15 Treacher Collins syndrome vs., III(2):19 Branchiootorenal syndrome, III(2):14, III(2):15, III(2):16, III(2):17 2nd branchial cleft cyst associated with, III(1):30 cochlear hypoplasia vs., VI(4):23 differential diagnosis, III(2):15 imaging, III(2):15, III(2):16, III(2):17 large vestibular aqueduct vs., VI(4):15 pathology, III(2):15 Bronchiectasis, keratosis obturans associated with, VI(2):9 Brown tumor of hyperparathyroidism, giant cell granuloma of mandiblemaxilla vs., I(15):29 Buccal mucosa squamous cell carcinoma, II(2):26 differential diagnosis, II(2):26 retromolar trigone SCCa vs., II(2):25 Buphthalmos orbital neurofibromatosis type vs., IV(2):19 pediatric neurofibromatosis type associated with, III(2):4 C Caffey disease, McCune-Albright syndrome vs., III(2):22 Calcific longus colli tendinitis, acute, I(8):8, I(8):9 Calcium pyrophosphate dihydrate deposition disease, temporomandibular joint, I(15):24 pigmented villonodular synovitis of TMJ vs., I(15):25 synovial chondromatosis of TMJ vs., I(15):27 Callosal dysgenesis, skull base cephalocele associated with, V(1):55 Capillary hemangioma See Hemangioma, infantile orbital See Hemangioma, infantile, orbital Capsulitis, temporomandibular joint, juvenile idiopathic arthritis vs., I(15):21 Cardiopulmonary anomalies, PHACES association associated with, III(2):12 Carotid artery aberrant internal, VI(3):12, VI(3):13, VI(3):14, VI(3):15 clinical issues, VI(3):14 differential diagnosis, VI(3):13, VI(3):14 glomus tympanicum paraganglioma vs., VI(3):43 imaging, VI(3):13, VI(3):15 lateralized internal carotid artery vs., VI(3):11 middle ear cholesterol granuloma vs., VI(3):39 pathology, VI(3):14 persistent stapedial artery associated with, VI(3):17 petrous ICA aneurysm vs., VI(5):23 1666 temporal bone meningioma vs., VI(3):47, VI(3):48 atheromatous plaque, carotid artery dissection vs., I(6):9 dissection, in neck, I(6):8, I(6):9, I(6):10, I(6):11 acute idiopathic carotidynia vs., I(6):17 clinical issues, I(6):10 differential diagnosis, I(6):9 fibromuscular dysplasia vs., I(6):15 P.v imaging, I(6):9, I(6):11 meningioma vs., I(6):41 pathology, I(6):10 pseudoaneurysm vs., I(6):13 skull base trauma associated with, V(2):12 staging, grading, & classification, I(6):10 tortuous carotid artery vs., I(6):7 ectatic carotid body paraganglioma vs., I(6):25 reactive adenopathy of retropharyngeal space vs., I(7):8 fenestration, carotid artery dissection vs., I(6):9 fibromuscular dysplasia, in neck, I(6):14, I(6):15 carotid artery dissection vs., I(6):9 differential diagnosis, I(6):15 lateralized internal, VI(3):10, VI(3):11 aberrant internal carotid artery vs., VI(3):13 differential diagnosis, VI(3):11 petrous ICA aneurysm, VI(5):22, VI(5):23 aberrant internal carotid artery vs., VI(3):13, VI(3):14 cholesterol granuloma vs., VI(5):15 congenital cholesteatoma vs., VI(5):7 differential diagnosis, VI(5):23 lateralized internal carotid artery vs., VI(3):11 pseudoaneurysm, in neck, I(6):12, I(6):13 carotid body paraganglioma vs., I(6):25 differential diagnosis, I(6):13 glomus vagale paraganglioma vs., I(6):29 meningioma vs., I(6):41 neurofibroma vs., I(6):38 schwannoma vs., I(6):33 tortuous carotid artery vs., I(6):7 traumatic, carotid artery dissection vs., I(6):9 temporal bone ICA aneurysm, petrous apex mucocele vs., VI(5):13 tortuous, in neck, I(6):6 carotid artery pseudoaneurysm vs., I(6):13 carotid body paraganglioma vs., I(6):25 differential diagnosis, I(6):7 Carotid body paraganglioma, I(6):24, I(6):25, I(6):26, I(6):27 clinical issues, I(6):26 Diagnostic Imaging Head and Neck differential diagnosis, I(6):25 giant lymph node hyperplasia vs., I(12):19 glomus vagale paraganglioma vs., I(6):29 imaging, I(6):25, I(6):27 meningioma vs., I(6):41 neurofibroma vs., I(6):38 pathology, I(6):26 schwannoma vs., I(6):33 staging, grading, & classification, I(6):26 sympathetic schwannoma vs., I(6):37 tortuous carotid artery vs., I(6):7 Carotid bulb ectasia, carotid artery pseudoaneurysm vs., I(6):13 Carotid space, I(6):2, I(6):3, I(6):4, I(6):5, I(6):6, I(6):7, I(6):8, I(6):9, I(6):10, I(6):11, I(6):12, I(6):13, I(6):14, I(6):15, I(6):16, I(6):17, I(6):18, I(6):19, I(6):20, I(6):21, I(6):22, I(6):23, I(6):24, I(6):25, I(6):26, I(6):27, I(6):28, I(6):29, I(6):30, I(6):31, I(6):32, I(6):33, I(6):34, I(6):35, I(6):36, I(6):37, I(6):38, I(6):39, I(6):40, I(6):41 See also Carotid artery carotid body paraganglioma See Carotid body paraganglioma carotidynia, acute idiopathic, I(6):16, I(6):17 clinical implications, I(6):3 differential diagnosis, I(6):3 images, I(6):4, I(6):5 imaging anatomy, I(6):2 approaches to imaging issues, I(6):2, I(6):3 techniques & indications, I(6):2 jugular vein thrombosis See Jugular vein thrombosis meningioma, I(6):40, I(6):41 carotid space schwannoma vs., I(6):33 differential diagnosis, I(6):41 glomus vagale paraganglioma vs., I(6):29 neurofibroma See Neurofibroma, carotid space overview, I(6):2, I(6):3, I(6):4, I(6):5 post-pharyngitis venous thrombosis (Lemierre), I(6):22, I(6):23 schwannoma See Schwannoma, carotid space sympathetic schwannoma, I(6):36, I(6):37 differential diagnosis, I(6):37 glomus vagale paraganglioma vs., I(6):33 staging, grading, & classification, I(6):37 Carotid transposition See Carotid artery, tortuous, in neck Carotid-cavernous fistula cavernous sinus thrombosis vs., V(1):49 orbital idiopathic inflammatory pseudotumor vs., IV(2):41 pterygoid venous plexus asymmetry vs., I(4):7 Carotidynia, acute idiopathic, I(6):16, I(6):17 differential diagnosis, I(6):17 staging, grading, & classification, I(6):17 Castleman disease See Giant lymph node hyperplasia (Castleman) Cat scratch disease histiocytic necrotizing lymphadenitis (Kikuchi) vs., I(12):23 non-tuberculous mycobacterium vs., I(12):16 tuberculous lymph nodes vs., I(12):15 Cataract, congenital coloboma associated with, IV(2):8 persistent hyperplastic primary vitreous vs., IV(2):11 Cavernous carotid fistula See Carotidcavernous fistula Cavernous hemangioma IAC (venous malformation ), VI(8):18, VI(8):19 orbital, IV(2):28, IV(2):29, IV(2):30, IV(2):31 clinical issues, IV(2):30 differential diagnosis, IV(2):29 hemangiopericytoma vs., I(13):11 imaging, IV(2):29, IV(2):31 lymphatic malformation vs., IV(2):23 pathology, IV(2):30 staging, grading, & classification, IV(2):30 venous varix vs., IV(2):27 P.vi Cavernous malformation See Venous malformation Cavernous sinus neoplasms, cavernous sinus thrombosis vs., V(1):49 Cavernous sinus thrombosis, V(1):48, V(1):49 as complication of rhinosinusitis, IV(1):38 differential diagnosis, V(1):49 Cellulitis, orbital, IV(2):38, IV(2):39 dermoid/epidermoid cyst vs., IV(2):15 differential diagnosis, IV(2):39 idiopathic inflammatory pseudotumor vs., IV(2):41 infantile hemangioma vs., IV(2):57 lymphoproliferative lesions vs., IV(2):79 subperiosteal abscess vs., IV(2):35 thyroid ophthalmopathy vs., IV(2):47 Cementoblastoma, ossifying fibroma vs., IV(1):75 Cemento-ossifying fibroma See Fibroma, ossifying, sinonasal Central nervous system lymphoma, CPA-IAC meningioma vs., VI(8):31 siderosis See Siderosis, superficial tumors, orbital neurofibromatosis type associated with, IV(2):20 Central neurofibromatosis See Neurofibromatosis type Cephalocele See also Encephalocele 1667 frontoethmoidal See Frontoethmoidal cephalocele petrous apex, VI(5):4, VI(5):5 skull base, V(1):54, V(1):55, V(1):56, V(1):57 clinical issues, V(1):56 differential diagnosis, V(1):55 imaging, V(1):55, V(1):57 pathology, V(1):55, V(1):56 persistent craniopharyngeal canal vs., V(1):17 staging, grading, & classification, V(1):55, V(1):56 temporal bone, VI(3):58, VI(3):59 Cerebellar pilocytic astrocytoma, arachnoid cyst of CPA vs., VI(8):11 Cerebellopontine angle-internal auditory canal See CPA-IAC Cerebral abscess, as complication of rhinosinusitis, IV(1):38 Cerebral heterotopia, nasal See Nasal glioma Cerebral venous sinus thrombosis See Dural sinus, thrombosis Cerebritis, as complication of rhinosinusitis, IV(1):38 Cerebrospinal fluid, increased FLAIR signal, CPA-IAC meningitis vs., VI(8):21 Cerebrospinal fluid leak skull base, V(1):58, V(1):59 differential diagnosis, V(1):59 skull base trauma associated with, V(2):12 temporal bone, VI(7):2, VI(7):3 Cervical esophageal carcinoma, I(10):36, I(10):37 differential diagnosis, I(10):37 post-cricoid region SCCa vs., II(2):32 posterior hypopharyngeal wall SCCa vs., II(2):33 Cervical esophageal diverticulum, lateral, I(10):41 Cervical space lateral esophageal diverticulum, I(10):41 neck abscess, jugular vein thrombosis vs., I(6):20 neuroblastoma, primary See Neuroblastoma, primary cervical posterior See Posterior cervical space sympathetic chain schwannoma See Schwannoma, sympathetic thymic cyst See Thymic cyst, cervical Cervical spine injuries, laryngeal trauma associated with, I(11):13 CHARGE syndrome choanal atresia associated with, IV(1):11 cochlear hypoplasia vs., VI(4):23 cochlear incomplete partition type vs., VI(4):13 cochlear nerve and cochlear nerve canal aplasia-hypoplasia vs., VI(4):25 inner ear, VI(4):28, VI(4):29, VI(4):30, VI(4):31 clinical issues, VI(4):29 Diagnostic Imaging Head and Neck differential diagnosis, VI(4):29 imaging, VI(4):29, VI(4):30, VI(4):31 pathology, VI(4):29 staging, grading, & classification, VI(4):29 large vestibular aqueduct vs., VI(4):15 solitary median maxillary central incisor related to, I(15):9 Chemodectoma See Carotid body paraganglioma; Glomus jugulare paraganglioma; Glomus tympanicum paraganglioma; Glomus vagale paraganglioma Cherubism, III(2):23 differential diagnosis, III(2):23 giant cell granuloma of mandiblemaxilla vs., I(15):29 McCune-Albright syndrome vs., III(2):22 Choanal atresia, IV(1):10, IV(1):11, IV(1):12, IV(1):13 clinical issues, IV(1):12 congenital nasal pyriform aperture stenosis vs., IV(1):27 differential diagnosis, IV(1):11 imaging, IV(1):11, IV(1):13 pathology, IV(1):11 solitary median maxillary central incisor vs., I(15):9 staging, grading, & classification, IV(1):11 Choanal stenosis, choanal atresia vs., IV(1):11 “Chocolate cyst.” See Cholesterol granuloma, middle ear; Cholesterol granuloma, petrous apex P.vii Cholesteatoma acquired acute otomastoiditis with abscess vs., VI(3):19 plus ossicle erosion, chronic otomastoiditis with ossicular erosions vs., VI(3):25 primary See Pars flaccida cholesteatoma secondary See Pars tensa cholesteatoma skull base Langerhans cell histiocytosis vs., V(1):67 aggressive, temporal bone osteoradionecrosis vs., VI(7):15 congenital See Cholesteatoma, congenital external auditory canal, VI(2):14, VI(2):15 congenital external ear dysplasia vs., VI(2):3 differential diagnosis, VI(2):15 exostoses vs., VI(2):19 keratosis obturans vs., VI(2):9 medial canal fibrosis vs., VI(2):11 necrotizing external otitis vs., VI(2):7 osteoma vs., VI(2):17 squamous cell carcinoma vs., VI(2):21 staging, grading, & classification, VI(2):15 large, with tegmen dehiscence, temporal bone cephalocele vs., VI(3):59 middle ear cholesterol granuloma associated with, VI(3):40 mural, VI(3):36, VI(3):37 pars flaccida See Pars flaccida cholesteatoma pars tensa See Pars tensa cholesteatoma “shell” or “rind.” See Mural cholesteatoma Cholesteatoma, congenital facial nerve canal middle ear prolapsing facial nerve vs., VI(6):5 venous malformation (hemangioma) vs., VI(6):11 mastoid, VI(3):6 middle ear, VI(3):2, VI(3):3, VI(3):4, VI(3):5 clinical issues, VI(3):4 differential diagnosis, VI(3):3, VI(3):4 glomus tympanicum paraganglioma vs., VI(3):43 imaging, VI(3):3, VI(3):5 middle ear adenoma vs., VI(3):53 middle ear schwannoma vs., VI(3):51 pars flaccida cholesteatoma vs., VI(3):29 pars tensa cholesteatoma vs., VI(3):33 plus ossicle erosion, chronic otomastoiditis with ossicular erosions vs., VI(3):25 staging, grading, & classification, VI(3):4 petrous apex, VI(5):6, VI(5):7, VI(5):8, VI(5):9 apical petrositis vs., VI(5):19 asymmetric marrow vs., VI(5):3 cephalocele vs., VI(5):5 cholesterol granuloma vs., VI(5):15 chondrosarcoma vs., V(1):91 clinical issues, VI(5):8 differential diagnosis, VI(5):7 imaging, VI(5):7, VI(5):9 mucocele vs., VI(5):13 pathology, VI(5):7, VI(5):8 trapped fluid vs., VI(5):11 skull base Langerhans cell histiocytosis vs., V(1):67 Cholesterol cyst See Cholesterol granuloma Cholesterol granuloma mastoid, congenital mastoid cholesteatoma vs., VI(3):6 middle ear, VI(3):38, VI(3):39, VI(3):40, VI(3):41 aberrant internal carotid artery vs., VI(3):14 clinical issues, VI(3):40 congenital middle ear cholesteatoma vs., VI(3):3, VI(3):4 differential diagnosis, VI(3):39 imaging, VI(3):39, VI(3):41 1668 pars flaccida cholesteatoma vs., VI(3):29 pars tensa cholesteatoma vs., VI(3):33 pathology, VI(3):39, VI(3):40 temporal bone cephalocele vs., VI(3):59 temporal bone meningioma vs., VI(3):47, VI(3):48 temporal bone rhabdomyosarcoma vs., VI(3):55 petrous apex, VI(5):14, VI(5):15, VI(5):16, VI(5):17 apical petrositis vs., VI(5):19 asymmetric marrow vs., VI(5):3 cephalocele vs., VI(5):5 clinical issues, VI(5):16 congenital cholesteatoma vs., VI(5):7 differential diagnosis, VI(5):15 endolymphatic sac tumor vs., VI(4):49 imaging, VI(5):15, VI(5):17 mucocele vs., VI(5):13 pathology, VI(5):15, VI(5):16 temporal bone metastasis vs., VI(7):13 trapped fluid vs., VI(5):11 petrous ICA aneurysm vs., VI(5):23 Chondroblastoma, CPDD of temporomandibular joint vs., I(15):24 Chondroma, laryngeal chondrosarcoma vs., I(11):19 Chondromatosis, synovial See Synovial chondromatosis of temporomandibular joint Chondrometaplasia, nodular, laryngeal chondrosarcoma vs., I(11):19 Chondromyxoid fibroma, skull base chondrosarcoma vs., V(1):91 Chondrosarcoma chordoma in perivertebral space vs., I(8):19 CPDD of temporomandibular joint vs., I(15):24 laryngeal, I(11):18, I(11):19, I(11):20, I(11):21 differential diagnosis, I(11):19 P.viii staging, grading, & classification, I(11):19, I(11):20 subglottic laryngeal SCCa vs., II(2):41 masticator space, I(4):24, I(4):25, I(4):26, I(4):27 CNV3 motor denervation vs., I(4):11 differential diagnosis, I(4):25 imaging, I(4):25, I(4):27 staging, grading, & classification, I(4):26 petrooccipital fissure apical petrositis vs., VI(5):19 invasive pituitary macroadenoma vs., V(1):11 pigmented villonodular synovitis of TMJ vs., I(15):25 sinonasal, IV(1):108 differential diagnosis, IV(1):108 osteosarcoma vs., IV(1):109 skull base, V(1):90, V(1):91, V(1):92, V(1):93 Diagnostic Imaging Head and Neck chordoma vs., V(1):13 clinical issues, V(1):92 differential diagnosis, V(1):91 fibrous dysplasia vs., V(1):61 imaging, V(1):91, V(1):93 meningioma vs., V(1):79 pathology, V(1):91, V(1):92 staging, grading, & classification, V(1):92 synovial chondromatosis of TMJ vs., I(15):27 Chordoma, V(1):12, V(1):13, V(1):14, V(1):15 chondrosarcoma vs., V(1):91 clinical issues, V(1):14 differential diagnosis, V(1):13 ecchordosis physaliphora vs., V(1):9 extraosseous, I(13):16, I(13):17 giant cell tumor vs., V(1):77 hemangiopericytoma vs., I(13):11 imaging, V(1):13, V(1):15 invasive pituitary macroadenoma vs., V(1):11 meningioma vs., V(1):79 osteosarcoma vs., V(1):95 pathology, V(1):13, V(1):14 perivertebral space, I(8):18, I(8):19 differential diagnosis, I(8):19 perivertebral space infection vs., I(8):12 vertebral body metastasis vs., I(8):21 plasmacytoma vs., V(1):83 sphenoid benign fatty lesion vs., V(1):18 staging, grading, & classification, V(1):14 Choroid hemangioma (hamartoma), ocular melanoma vs., IV(2):75 melanoma See Ocular melanoma metastasis, ocular melanoma vs., IV(2):75 osteoma, ocular melanoma vs., IV(2):75 Chromosome 13q deletion syndrome, retinoblastoma associated with, IV(2):72 Chromosome 22q11 deletion, hemifacial microsomia vs., III(2):18 Ciliary dyskinesia, orbital subperiosteal abscess associated with, IV(2):36 Clivus chordoma See Chordoma CNV2 perineural tumor, trigeminal schwannoma of central skull base vs., V(1):19 CNV3 malignant nerve sheath tumor, CNV3 schwannoma of masticator space vs., I(4):19 normal fat pad, perineural CNV3 tumor of masticator space vs., I(4):21 CNV3 motor denervation, masticator space, I(4):10, I(4):11, I(4):12, I(4):13 clinical issues, I(4):12 differential diagnosis, I(4):11 imaging, I(4):11, I(4):13 pathology, I(4):11, I(4):12 CNV3 neurofibroma, masticator space CNV3 schwannoma of masticator space vs., I(4):19 perineural CNV3 tumor of masticator space vs., I(4):21 CNV3 perineural tumor masticator space, I(4):20, I(4):21, I(4):22, I(4):23 benign masticator muscle hypertrophy vs., I(4):9 clinical issues, I(4):22 CNV3 motor denervation vs., I(4):11 CNV3 schwannoma of masticator space vs., I(4):19 differential diagnosis, I(4):21, I(4):22 imaging, I(4):21, I(4):23 pathology, I(4):22 sarcoma vs., I(4):29 pterygopalatine fossa, pterygoid venous plexus asymmetry vs., I(4):7 trigeminal schwannoma of central skull base vs., V(1):19 CNV3 schwannoma, masticator space, I(4):18, I(4):19 differential diagnosis, I(4):19 imaging, I(4):19 perineural CNV3 tumor of masticator space vs., I(4):21 Coalescent otomastoiditis See Otomastoiditis Coats disease, IV(2):12, IV(2):13 differential diagnosis, IV(2):13 ocular toxocariasis vs., IV(2):33 persistent hyperplastic primary vitreous vs., IV(2):11 retinoblastoma vs., IV(2):71 Cocaine necrosis, nasal See Nasal cocaine necrosis Cochlear aperture stenosis-atresia See Cochlear nerve and cochlear nerve canal aplasia-hypoplasia Cochlear aplasia, VI(4):20, VI(4):21 cochlear implantation considerations, VI(4):56 cochlear nerve and cochlear nerve canal aplasia-hypoplasia vs., VI(4):25 common cavity malformation vs., VI(4):9 cystic cochleovestibular anomaly vs., VI(4):11 differential diagnosis, VI(4):21 P.ix labyrinthine aplasia vs., VI(4):7 labyrinthine ossificans vs., VI(4):37 Cochlear aqueduct, prominent, subarcuate canaliculus vs., VI(4):3 Cochlear cleft, VI(4):4, VI(4):5 Cochlear hypoplasia, VI(4):22, VI(4):23 cochlear incomplete partition type vs., VI(4):13 cochlear nerve and cochlear nerve canal aplasia-hypoplasia vs., VI(4):25 differential diagnosis, VI(4):23 large vestibular aqueduct vs., VI(4):15 1669 Cochlear implants, VI(4):54, VI(4):55, VI(4):56, VI(4):57 differential diagnosis, VI(4):56 imaging, VI(4):55, VI(4):57 pathology, VI(4):56 Cochlear incomplete partition type I (IP-I), VI(4):12, VI(4):13 See also Cochleovestibular malformation (IP-I), cystic cochlear hypoplasia vs., VI(4):23 differential diagnosis, VI(4):13 globular vestibule-semicircular canal vs., VI(4):26 X-linked stapes gusher vs., VI(4):19 Cochlear incomplete partition type III (IP-III) See X-linked stapes gusher (DFNX2) Cochlear nerve and cochlear nerve canal aplasia-hypoplasia, VI(4):24, VI(4):25 cochlear implantation considerations, VI(4):56 differential diagnosis, VI(4):25 Cochlear otosclerosis cochlear cleft vs., VI(4):5 labyrinthine ossificans vs., VI(4):37 otosyphilis vs., VI(4):35 Cochleovestibular malformation (IP-I), cystic, VI(4):10, VI(4):11 See also Cochlear incomplete partition type I (IP-I) cochlear aplasia vs., VI(4):21 cochlear implantation considerations, VI(4):56 common cavity malformation vs., VI(4):9 differential diagnosis, VI(4):11 large vestibular aqueduct vs., VI(4):15 Cold water ear See External auditory canal, exostoses (surfer's ear) Collagen vascular disease, orbital lymphoproliferative lesions associated with, IV(2):79 Colloid cyst, thyroid See Thyroid cyst, colloid Coloboma clinical issues, IV(2):8 differential diagnosis, IV(2):7 imaging, IV(2):7, IV(2):9 pathology, IV(2):7, IV(2):8 staging, grading, & classification, IV(2):8 Colobomatous cyst, retrobulbar, coloboma associated with, IV(2):8 COM See Otitis media, chronic Common cavity cystic cochleovestibular anomaly vs., VI(4):11 labyrinthine aplasia vs., VI(4):7 Common cavity malformation, VI(4):8, VI(4):9 cochlear aplasia vs., VI(4):21 cochlear implantation considerations, VI(4):56 cochlear incomplete partition type vs., VI(4):13 Diagnostic Imaging Head and Neck Conductive hearing loss with perilymphatic gusher See X-linked stapes gusher (DFNX2) with stapes fixation See X-linked stapes gusher (DFNX2) Condylar hypoplasia, temporomandibular joint, juvenile idiopathic arthritis vs., I(15):21 Confluent apical petrositis See Petrositis, apical Congenital anomalies, III(1):2, III(1):3, III(1):4, III(1):5, III(1):6, III(1):7, III(1):8, III(1):9, III(1):10, III(1):11, III(1):12, III(1):13, III(1):14, III(1):15, III(1):16, III(1):17, III(1):18, III(1):19, III(1):20, III(1):21, III(1):22, III(1):23, III(1):24, III(1):25, III(1):26, III(1):27, III(1):28, III(1):29, III(1):30, III(1):31, III(1):32, III(1):33, III(1):34, III(1):35, III(1):36, III(1):37, III(1):38, III(1):39, III(1):40, III(1):41, III(1):42, III(1):43 See also Congenital anomalies, syndromic branchial cleft cyst See Branchial cleft cyst branchiootorenal syndrome See Branchiootorenal syndrome cervical thymic cyst See Thymic cyst, cervical choanal atresia associated with, IV(1):11 clinical implications, III(1):3 congenital nasal pyriform aperture stenosis associated with, IV(1):27 differential diagnosis, III(1):3 embryology, III(1):2, III(1):3 external ear dysplasia See External ear dysplasia, congenital frontoethmoidal cephalocele associated with, IV(1):24 images, III(1):4, III(1):5 imaging anatomy, III(1):3 techniques and indications, III(1):2 labyrinthine aplasia associated with, VI(4):7 lymphatic malformation See Lymphatic malformation nasal dermal sinus associated with, IV(1):20 nasal glioma associated with, IV(1):16 overview, III(1):2, III(1):3, III(1):4, III(1):5 persistent craniopharyngeal canal vs., V(1):17 solitary median maxillary central incisor related to, I(15):9 thyroglossal duct cyst See Thyroglossal duct cyst vallecular cyst, III(1):14, III(1):15 differential diagnosis, III(1):15 retention cyst of pharyngeal mucosal space vs., I(3):9 venous malformation See Venous malformation Congenital anomalies, syndromic, III(1):2, III(1):3, III(1):4, III(1):5, III(1):6, III(1):7, III(1):8, III(1):9, III(1):10, III(1):11, III(1):12, III(1):13, III(1):14, III(1):15, III(1):16, III(1):17, III(1):18, III(1):19, III(1):20, III(1):21, III(1):22, III(1):23, III(1):24, III(1):25 basal cell nevus syndrome, III(2):8, III(2):9 P.x cherubism, III(2):23 differential diagnosis, III(2):23 giant cell granuloma of mandiblemaxilla vs., I(15):29 McCune-Albright syndrome vs., III(2):22 hemifacial microsomia, III(2):18 McCune-Albright syndrome, III(2):22 cherubism vs., III(2):23 differential diagnosis, III(2):22 mucopolysaccharidosis, III(2):24, III(2):25 neurofibromatosis type See Neurofibromatosis type neurofibromatosis type See Neurofibromatosis type PHACES association See PHACES association Pierre Robin sequence, III(2):20, III(2):21 Treacher Collins syndrome, III(2):19 Pierre Robin sequence vs., III(2):21 Connective tissue diseases, Kimura disease associated with, I(12):26 Corda tympani schwannoma See Schwannoma, middle ear CPA-IAC, VI(8):2, VI(8):3, VI(8):4, VI(8):5, VI(8):6, VI(8):7, VI(8):8, VI(8):9, VI(8):10, VI(8):11, VI(8):12, VI(8):13, VI(8):14, VI(8):15, VI(8):16, VI(8):17, VI(8):18, VI(8):19, VI(8):20, VI(8):21, VI(8):22, VI(8):23, VI(8):24, VI(8):25, VI(8):26, VI(8):27, VI(8):28, VI(8):29, VI(8):30, VI(8):31, VI(8):32, VI(8):33, VI(8):34, VI(8):35, VI(8):36, VI(8):37, VI(8):38, VI(8):39, VI(8):40, VI(8):41, VI(8):42, VI(8):43, VI(8):44, VI(8):45, VI(8):46, VI(8):47, VI(8):48, VI(8):49 See also External auditory canal; Facial nerve, intratemporal; Inner ear; Middle ear-mastoid; Petrous apex; Temporal bone aneurysm, VI(8):44, VI(8):45 congenital CPA-IAC lipoma vs., VI(8):15 differential diagnosis, VI(8):45 hemifacial spasm vs., VI(8):43 trigeminal neuralgia vs., VI(8):41 vestibular schwannoma vs., VI(8):27 arachnoid cyst, VI(8):10, VI(8):11, VI(8):12, VI(8):13 differential diagnosis, VI(8):11 epidermoid cyst vs., VI(8):7 vestibular schwannoma vs., VI(8):27 congenital lipoma, VI(8):14, VI(8):15, VI(8):16, VI(8):17 1670 CPA cystic neoplasm, epidermoid cyst vs., VI(8):7 differential diagnosis of CPA mass, VI(8):3 embryology, VI(8):2 epidermoid cyst, VI(8):6, VI(8):7, VI(8):8, VI(8):9 arachnoid cyst vs., VI(8):11 differential diagnosis, VI(8):7 meningioma vs., VI(8):31 vestibular schwannoma vs., VI(8):27 hemifacial spasm, VI(8):42, VI(8):43 IAC venous malformation, VI(8):18, VI(8):19 images, VI(8):4, VI(8):5 imaging anatomy of the cochlea-IAC-CPA, VI(8):2 approaches to imaging issues, VI(8):2, VI(8):3 techniques and indications, VI(8):2 meningioma See Meningioma, CPAIAC meningitis, VI(8):20, VI(8):21 differential diagnosis, VI(8):21 metastases vs., VI(8):37 Ramsay Hunt syndrome vs., VI(8):23 sarcoidosis vs., VI(8):25 metastases, VI(8):36, VI(8):37, VI(8):38, VI(8):39 clinical issues, VI(8):38 differential diagnosis, VI(8):37 IAC venous malformation vs., VI(8):19 imaging, VI(8):37, VI(8):39 meningioma vs., VI(8):31 neurofibromatosis type vs., III(2):7 pathology, VI(8):37, VI(8):38 sarcoidosis vs., VI(8):25 vestibular schwannoma vs., VI(8):27 neurocysticercosis, epidermoid cyst vs., VI(8):7 overview, VI(8):2, VI(8):3, VI(8):4, VI(8):5 Ramsay Hunt syndrome, VI(8):22, VI(8):23 CPA-IAC metastases vs., VI(8):37 differential diagnosis, VI(8):23 sarcoidosis, VI(8):24, VI(8):25 differential diagnosis, VI(8):25 meningioma vs., VI(8):31 meningitis vs., VI(8):21 metastases vs., VI(8):37 neurofibromatosis type vs., III(2):7 superficial siderosis, VI(8):46, VI(8):47, VI(8):48, VI(8):49 trigeminal neuralgia, VI(8):40, VI(8):41 vestibular schwannoma See Vestibular schwannoma CPPD See Calcium pyrophosphate dihydrate deposition disease, temporomandibular joint Cranial nerve(s) 11 (accessory nerve), motor denervation, nodal neck dissection vs., II(3):3 Diagnostic Imaging Head and Neck CNV2 perineural tumor, trigeminal schwannoma of central skull base vs., V(1):19 CNV3 See CNV3 entries deficits, skull base trauma associated with, V(2):12 facial See Facial nerve, intratemporal; Facial nerve schwannoma hypoglossal motor denervation, I(14):8, I(14):9 schwannoma, V(1):20, V(1):21 optic nerve See Optic nerve entries trigeminal See Trigeminal entries Cranial pachymeningitis, hypertrophic See Pseudotumor, idiopathic inflammatory, skull base Craniofacial fibrous dysplasia See Fibrous dysplasia, skull base Craniopharyngeal canal, persistent, V(1):16, V(1):17 Cricoid region squamous cell carcinoma See Post-cricoid region squamous cell carcinoma Crista galli, fatty marrow in nasal dermal sinus vs., IV(1):19 pediatric dermoid/epidermoid cyst vs., III(1):42 Croup, I(11):8, I(11):9 differential diagnosis, I(11):9 epiglottitis in child vs., I(11):10 upper airway infantile hemangioma vs., I(11):17 P.xi Cushing syndrome, esthesioneuroblastoma associated with, IV(1):95 Cylindrical epithelioma See Papilloma, inverted Cylindroma See Parotid carcinoma, adenoid cystic Cystic cochleovestibular anomaly See Cochlear incomplete partition type I (IP-I); Cochleovestibular malformation (IP-I), cystic Cystic fibrosis acute rhinosinusitis associated with, IV(1):29 orbital subperiosteal abscess associated with, IV(2):36 sinonasal polyposis associated with, IV(1):50 Cystic hygroma See Lymphatic malformation D Dacryoadenits lacrimal gland benign mixed tumor vs., IV(2):69 lacrimal gland carcinoma vs., IV(2):83 Dacryocystocele, nasolacrimal duct mucocele vs., IV(1):9 Deafness type See X-linked stapes gusher (DFNX2) Dehiscent jugular bulb See Jugular bulb, dehiscent Delphian chain necrotic node, thyroglossal duct cyst vs., III(1):17 Denervation atrophy See CNV3 motor denervation, masticator space Dental disease/infection chronic rhinosinusitis associated with, IV(1):34 submandibular gland sialadenitis vs., I(14):27 Dentigerous cyst ameloblastoma associated with, I(15):32 ameloblastoma vs., I(15):31 basal cell nevus syndrome vs., III(2):9 differential diagnosis, I(15):15 keratocystic odontogenic tumor vs., I(15):35 minor salivary gland malignancy vs., I(14):41 nasopalatine duct cyst vs., I(15):19 periapical (radicular) cyst vs., I(15):13 Dercum disease, lipoma of head and neck associated with, I(13):7, I(13):8 Dermoid cyst lipoma of head and neck vs., I(13):7 nasal See Nasal dermal sinus ruptured, congenital CPA-IAC lipoma vs., VI(8):15 venous malformation vs., III(1):12 Dermoid/epidermoid cyst oral cavity, I(14):12, I(14):13, I(14):14, I(14):15 abscess vs., I(14):29 clinical issues, I(14):14 differential diagnosis, I(14):13 imaging, I(14):13, I(14):15 minor salivary gland malignancy vs., I(14):41 nasolabial cyst vs., I(15):11 pathology, I(14):13, I(14):14 ranula vs., I(14):21 staging, grading, & classification, I(14):14 thyroglossal duct cyst vs., III(1):17 orbital, IV(2):14, IV(2):15, IV(2):16, IV(2):17 clinical issues, IV(2):16 differential diagnosis, IV(2):15 frontoethmoidal cephalocele vs., IV(1):23 imaging, IV(2):15, IV(2):17 lacrimal gland benign mixed tumor vs., IV(2):69 nasal glioma vs., IV(1):15 nasolacrimal duct mucocele vs., IV(1):9 pathology, IV(2):16 subperiosteal abscess vs., IV(2):35 pediatric, III(1):40, III(1):41, III(1):42, III(1):43 clinical issues, III(1):42 differential diagnosis, III(1):41, III(1):42 imaging, III(1):41, III(1):43 pathology, III(1):42 1671 staging, grading, & classification, III(1):42 skull base, ecchordosis physaliphora vs., V(1):9 Dermolipoma, orbital, dermoid/epidermoid cyst vs., IV(2):15 Desmoid, extraabdominal See Fibromatosis of head and neck Developmental cyst, oral cavity See Dermoid/epidermoid cyst, oral cavity Differentiated thyroid carcinoma See Thyroid carcinoma, differentiated DiGeorge syndromes, solitary median maxillary central incisor related to, I(15):9 Distensible orbital venous malformation See Venous varix, orbital Diverticulum jugular bulb See Jugular bulb diverticulum lateral cervical esophageal, I(10):41 Zenker See Esophagopharyngeal diverticulum (Zenker) Diving ranula See Ranula Down syndrome (trisomy 21) mucopolysaccharidosis vs., III(2):25 semicircular canal hypoplasia-aplasia vs., VI(4):27 Drusen, orbital foreign body vs., V(2):15 Duane retraction, solitary median maxillary central incisor related to, I(15):9 Ductal cyst See Vallecular cyst, congenital Dural arteriovenous fistula, V(1):50, V(1):51, V(1):52, V(1):53 clinical issues, V(1):52 differential diagnosis, V(1):51 imaging, V(1):51, V(1):53 pathology, V(1):52 skull base, dural sinus and aberrant arachnoid granulations vs., V(1):41 skull base trauma associated with, V(2):12 staging, grading, & classification, V(1):52 temporal bone arachnoid granulations vs., VI(7):5 P.xii and venous varix, CPA-IAC aneurysm vs., VI(8):45 Dural sinus and aberrant arachnoid granulations, V(1):40, V(1):41, V(1):42, V(1):43 clinical issues, V(1):42 differential diagnosis, V(1):41 dural sinus thrombosis vs., V(1):46 imaging, V(1):41, V(1):43 pathology, V(1):41, V(1):42 flow asymmetry, physiologic, dural sinus thrombosis vs., V(1):46 hypoplasia-aplasia Diagnostic Imaging Head and Neck dural arteriovenous fistula vs., V(1):51 dural sinus and aberrant arachnoid granulations vs., V(1):41 dural sinus thrombosis vs., V(1):46 normal, dural sinus thrombosis vs., V(1):46 thrombosis, V(1):44, V(1):45, V(1):46, V(1):47 clinical issues, V(1):46 differential diagnosis, V(1):46 dural arteriovenous fistula vs., V(1):51 dural sinus and aberrant arachnoid granulations vs., V(1):41 imaging, V(1):45, V(1):46, V(1):47 pathology, V(1):46 Dysplastic nevus syndrome, ocular melanoma associated with, IV(2):76 E Ear See External auditory canal; Inner ear; Middle ear-mastoid Ecchordosis physaliphora, V(1):8, V(1):9 Ectodermal inclusion cyst See Dermoid/ectodermoid cyst, oral cavity; Dermoid/epidermoid cyst, orbital Edema See Retropharyngeal space, edema Ehlers-Danlos syndrome, carotid artery dissection in neck associated with, I(6):10 Encapsulated vascular malformation See Cavernous hemangioma, orbital Encephalocele See also Cephalocele juvenile angiofibroma vs., IV(1):80 middle ear, cholesterol granuloma vs., VI(3):39 temporal bone See Temporal bone, cephalocele Enchondroma, skull base osteosarcoma associated with, V(1):95 Endolymphatic sac anomaly, large See Vestibular aqueduct (IP-II), large Endolymphatic sac tumor, VI(4):48, VI(4):49 differential diagnosis, VI(4):49 glomus vagale paraganglioma associated with, VI(6):30 staging, grading, & classification, VI(4):49 temporal bone arachnoid granulations vs., VI(7):5 Endophthalmitis acute, ocular toxocariasis vs., IV(2):33 sclerosing See Toxocariasis, ocular Endophytic papilloma See Papilloma, inverted Enophthalmos, silent sinus syndrome associated with, IV(1):61 Eosinophilic granuloma See Langerhans cell histiocytosis Eosinophilic hyperplastic lymphogranuloma See Kimura disease Ependymoma cystic infratentorial, arachnoid cyst of CPA vs., VI(8):11 neurofibromatosis type associated with, III(2):7 Epidermoid carcinoma See Sinonasal squamous cell carcinoma Epidermoid cholesteatoma, primary See Cholesteatoma, congenital, middle ear Epidermoid cyst CPA-IAC, VI(8):6, VI(8):7, VI(8):8, VI(8):9 arachnoid cyst vs., VI(8):11 clinical issues, VI(8):8 differential diagnosis, VI(8):7 imaging, VI(8):7, VI(8):9 meningioma vs., VI(8):31 pathology, VI(8):7, VI(8):8 vestibular schwannoma vs., VI(8):27 oral cavity See Dermoid/epidermoid cyst, oral cavity orbital See Dermoid/epidermoid cyst, orbital petrous apex See Cholesteatoma, congenital, petrous apex sublingual space, sialocele vs., I(14):25 venous malformation vs., III(1):12 Epiglottic cyst See Vallecular cyst, congenital Epiglottic squamous cell carcinoma See Laryngeal squamous cell carcinoma, supraglottic Epiglottitis adult See Supraglottitis child, I(11):10 croup vs., I(11):9 supraglottitis vs., I(11):11 Epstein-Barr virus nasopharyngeal carcinoma associated with, II(2):3 nodal non-Hodgkin lymphoma of neck associated with, I(12):29 Warthin tumor associated with, I(5):24 Esophageal carcinoma, cervical, I(10):36, I(10):37 differential diagnosis, I(10):37 post-cricoid region SCCa vs., II(2):32 posterior hypopharyngeal wall SCCa vs., II(2):33 Esophageal diverticulum, lateral cervical, I(10):41 Esophageal injuries, laryngeal trauma associated with, I(11):13 Esophagopharyngeal diverticulum (Zenker), I(10):38, I(10):39 P.xiii differential diagnosis, I(10):39 lateral cervical esophageal diverticulum vs., I(10):41 staging, grading, & classification, I(10):39 Esthesioneuroblastoma, IV(1):94, IV(1):95, IV(1):96, IV(1):97 adenocarcinoma vs., IV(1):99 adenoid cystic carcinoma vs., IV(1):107 chondrosarcoma vs., IV(1):108 clinical issues, IV(1):96 1672 differential diagnosis, IV(1):95 imaging, IV(1):95, IV(1):97 inverted papilloma vs., IV(1):83 juvenile angiofibroma vs., IV(1):80 melanoma vs., IV(1):101 non-Hodgkin lymphoma vs., IV(1):103 pathology, IV(1):95, IV(1):96 solitary sinonasal polyp vs., IV(1):53 staging, grading, & classification, IV(1):95, IV(1):96 undifferentiated carcinoma vs., IV(1):106 Ethmoid sinus cephalocele See Frontoethmoidal cephalocele mucocele, orbital dermoid/epidermoid cyst vs., IV(2):15 Ewing sarcoma osteosarcoma of mandible-maxilla vs., I(15):39 perivertebral space infection vs., I(8):12 Exostoses, external auditory canal See External auditory canal, exostoses (surfer's ear) External auditory canal, VI(2):2, VI(2):3, VI(2):4, VI(2):5, VI(2):6, VI(2):7, VI(2):8, VI(2):9, VI(2):10, VI(2):11, VI(2):12, VI(2):13, VI(2):14, VI(2):15, VI(2):16, VI(2):17, VI(2):18, VI(2):19, VI(2):20, VI(2):21 acquired stenosis (surfer's ear), congenital external ear dysplasia vs., VI(2):3 atresia See External ear dysplasia, congenital benign debris keratosis obturans vs., VI(2):9 medial canal fibrosis vs., VI(2):11 osteoma vs., VI(2):17 squamous cell carcinoma vs., VI(2):21 cholesteatoma See Cholesteatoma, external auditory canal congenital external ear dysplasia See External ear dysplasia, congenital differential diagnosis, VI(1):4 exostoses (surfer's ear), VI(2):18, VI(2):19 differential diagnosis, VI(2):19 medial canal fibrosis vs., VI(2):11 osteoma vs., VI(2):17 keratosis obturans, VI(2):8, VI(2):9 cholesteatoma vs., VI(2):15 differential diagnosis, VI(2):9 medial canal fibrosis vs., VI(2):11 medial canal fibrosis, VI(2):10, VI(2):11, VI(2):12, VI(2):13 cholesteatoma vs., VI(2):15 clinical issues, VI(2):12 differential diagnosis, VI(2):11 exostoses vs., VI(2):19 imaging, VI(2):11, VI(2):13 osteoma vs., VI(2):17 pathology, VI(2):11, VI(2):12 postinflammatory, necrotizing external otitis vs., VI(2):7 Diagnostic Imaging Head and Neck staging, grading, & classification, VI(2):12 necrotizing external otitis, VI(2):6, VI(2):7 osteoma, VI(2):16, VI(2):17 congenital external ear dysplasia vs., VI(2):3 differential diagnosis, VI(2):17 exostoses vs., VI(2):19 squamous cell carcinoma See Squamous cell carcinoma, external auditory canal External ear dysplasia, congenital, VI(2):2, VI(2):3, VI(2):4, VI(2):5 branchiootorenal syndrome vs., III(2):15 clinical issues, VI(2):4 congenital ossicular fixation vs., VI(3):7 differential diagnosis, VI(2):3 EAC cholesteatoma associated with, VI(2):15 imaging, VI(2):3, VI(2):5 middle ear cholesteatoma associated with, VI(3):4 mild, chronic otomastoiditis with ossicular erosions vs., VI(3):25 oval window atresia vs., VI(3):9 pathology, VI(2):3, VI(2):4 staging, grading, & classification, VI(2):4 Treacher Collins syndrome vs., III(2):19 External otitis, necrotizing, VI(2):6, VI(2):7 cholesteatoma vs., VI(2):15 exostoses vs., VI(2):19 keratosis obturans vs., VI(2):9 medial canal fibrosis vs., VI(2):11 osteoma vs., VI(2):17 squamous cell carcinoma vs., VI(2):21 temporal bone osteoradionecrosis vs., VI(7):15 Extracranial atherosclerosis acute idiopathic carotidynia vs., I(6):17 carotid artery fibromuscular dysplasia vs., I(6):15 vertebral artery dissection in neck vs., I(8):15 Extraosseous chordoma, I(13):16, I(13):17 Eye abnormalities PHACES association associated with, III(2):12 skull base cephalocele associated with, V(1):55 F Facial fractures See Skull base and facial trauma Facial microsomia, bilateral branchiootorenal syndrome vs., III(2):15 Treacher Collins syndrome vs., III(2):19 Facial nerve, intratemporal, VI(6):2, VI(6):3, VI(6):4, VI(6):5, VI(6):6, VI(6):7, VI(6):8, VI(6):9, VI(6):10, VI(6):11, VI(6):12, VI(6):13, VI(6):14, VI(6):15, VI(6):16, VI(6):17, VI(6):18, VI(6):19, VI(6):20, VI(6):21 Bell palsy See Bell palsy differential diagnosis, VI(1):4 enhancement (normal), VI(6):2, VI(6):3 Bell palsy vs., VI(6):7 differential diagnosis, VI(6):3 P.xiv schwannoma vs., VI(6):15 venous malformation (hemangioma) vs., VI(6):11 imaging anatomy, VI(1):3 middle ear prolapsing, VI(6):4, VI(6):5 perineural parotid malignancy, VI(6):18, VI(6):19, VI(6):20, VI(6):21 Bell palsy vs., VI(6):7 clinical issues, VI(6):20 differential diagnosis, VI(6):19 enhancement vs., VI(6):3 imaging, VI(6):19, VI(6):21 pathology, VI(6):19, VI(6):20 schwannoma vs., VI(6):15 staging, grading, & classification, VI(6):20 venous malformation (hemangioma) vs., VI(6):11 schwannoma See Facial nerve schwannoma venous malformation (hemangioma), VI(6):10, VI(6):11, VI(6):12, VI(6):13 Bell palsy vs., VI(6):7 clinical issues, VI(6):12 differential diagnosis, VI(6):11 imaging, VI(6):11, VI(6):13 pathology, VI(6):11, VI(6):12 perineural parotid malignancy vs., VI(6):19 persistent stapedial artery vs., VI(3):17 schwannoma vs., VI(6):15 staging, grading, & classification, VI(6):12 Facial nerve schwannoma CPA-IAC, VI(8):34, VI(8):35 clinical issues, VI(8):35 differential diagnosis, VI(8):34, VI(8):35 IAC venous malformation vs., VI(8):19 imaging, VI(8):35 pathology, VI(8):35 pedunculated See Schwannoma, middle ear persistent stapedial artery vs., VI(3):17 vestibular schwannoma vs., VI(8):27 imaging, VI(3):51 intratemporal, VI(6):14, VI(6):15, VI(6):16, VI(6):17 Bell palsy vs., VI(6):7 clinical issues, VI(6):16 differential diagnosis, VI(6):15 imaging, VI(6):15, VI(6):17 middle ear prolapsing facial nerve vs., VI(6):5 pathology, VI(6):15, VI(6):16 1673 perineural parotid malignancy vs., VI(6):19 venous malformation (hemangioma) vs., VI(6):11 with dehiscence into inner ear, intralabyrinthine schwannoma vs., VI(4):45 within T-bone, facial nerve enhancement vs., VI(6):3 tympanic segment congenital middle ear cholesteatoma vs., VI(3):3 glomus tympanicum paraganglioma vs., VI(3):43 Facial neuroma See Facial nerve schwannoma; Schwannoma, parotid space Facial trauma See Skull base and facial trauma False vocal cords See Laryngeal squamous cell carcinoma, supraglottic Familial adenomatous polyposis, fibromatosis associated with, I(13):33 Familial aggressive fibromatosis, fibromatosis associated with, I(13):33 Fanconi anemia lingual tonsil squamous cell carcinoma associated with, II(2):7 palatine tonsil squamous cell carcinoma associated with, II(2):11 Fatty marrow in crista galli nasal dermal sinus vs., IV(1):19 pediatric dermoid/epidermoid cyst vs., III(1):42 Fatty nodal metaplasia, suppurative lymph nodes vs., I(12):11 Faucial tonsil squamous cell carcinoma See Palatine tonsil squamous cell carcinoma Fenestral otosclerosis See Otosclerosis, fenestral Fibrolipoma, I(13):8 Fibroma, chondromyxoid, skull base chondrosarcoma vs., V(1):91 Fibroma, ossifying mandible-maxilla ameloblastoma vs., I(15):32 giant cell granuloma of mandiblemaxilla vs., I(15):29 masticator space chondrosarcoma vs., I(4):25 sinonasal, IV(1):74, IV(1):75, IV(1):76, IV(1):77 chondrosarcoma vs., IV(1):108 clinical issues, IV(1):76 differential diagnosis, IV(1):75 fibrous dysplasia vs., IV(1):69 imaging, IV(1):75, IV(1):77 osteoma vs., IV(1):71 osteosarcoma vs., IV(1):109 pathology, IV(1):75, IV(1):76 staging, grading, & classification, IV(1):76 skull base fibrous dysplasia vs., V(1):61 sphenoid benign fatty lesion vs., V(1):18 Diagnostic Imaging Head and Neck Fibromatosis colli, III(1):44, III(1):45 Fibromatosis of head and neck, I(13):32, I(13):33, I(13):34, I(13):35 clinical issues, I(13):34 differential diagnosis, I(13):33 imaging, I(13):33, I(13):35 osteosarcoma of mandible-maxilla vs., I(15):39 pathology, I(13):33, I(13):34 staging, grading, & classification, I(13):34 synovial sarcoma vs., I(13):25 Fibromuscular dysplasia, in neck carotid artery, I(6):14, I(6):15 carotid artery dissection vs., I(6):9 P.xv differential diagnosis, I(6):15 carotid artery dissection associated with, I(6):10 vertebral artery dissection vs., I(8):15 Fibrosarcoma, soft tissue, fibromatosis vs., I(13):33 Fibrous dysplasia cherubism vs., III(2):23 Langerhans cell histiocytosis vs., IV(2):55 mandibular, masticator space chondrosarcoma vs., I(4):25 monostotic, McCune-Albright syndrome vs., III(2):22 polyostotic, McCune-Albright syndrome vs., III(2):22 sinonasal, IV(1):68, IV(1):69 chondrosarcoma vs., IV(1):108 differential diagnosis, IV(1):69 ossifying fibroma vs., IV(1):75 osteoma vs., IV(1):71 osteosarcoma vs., IV(1):109 skull base, V(1):60, V(1):61, V(1):62, V(1):63 clinical issues, V(1):62 differential diagnosis, V(1):61 imaging, V(1):61, V(1):63 Langerhans cell histiocytosis vs., V(1):67 osteopetrosis vs., V(1):71 osteosarcoma associated with, V(1):95 Paget disease vs., V(1):65 pathology, V(1):62 skull base giant cell tumor vs., V(1):77 staging, grading, & classification, V(1):62 sphenoid benign fatty lesion vs., V(1):18 temporal bone, VI(7):6, VI(7):7 congenital mastoid cholesteatoma vs., VI(3):6 differential diagnosis, VI(7):7 otosclerosis vs., VI(4):41 otosyphilis vs., VI(4):35 Paget disease vs., VI(7):9 temporal bone Langerhans cell histiocytosis vs., VI(7):11 Fibrous histiocytoma, malignant, malignant peripheral nerve sheath tumor vs., I(13):27 Floor of mouth sialocele See Sialocele squamous cell carcinoma, II(2):20, II(2):21 differential diagnosis, II(2):21 staging, grading, & classification, II(2):21 sublingual gland carcinoma vs., I(14):37 Follicular cyst See Dentigerous cyst Follicular lymphoreticuloma See Giant lymph node hyperplasia (Castleman) Foramen cecum nonossified nasal dermal sinus vs., IV(1):19 pediatric dermoid/epidermoid cyst vs., III(1):42 thyroglossal duct cyst benign mixed tumor of pharyngeal mucosal space vs., I(3):15 retention cyst of pharyngeal mucosal space vs., I(3):9 Foregut duplication cyst, nontuberculous mycobacterium vs., I(12):16 Foreign body middle ear, ossicular prosthesis vs., VI(3):62 nasal, choanal atresia vs., IV(1):11 orbit, V(2):14, V(2):15 trachea, croup vs., I(11):9 Frontoethmoid sinus mucocele, orbital dermoid/epidermoid cyst vs., IV(2):15 Frontoethmoidal cephalocele, IV(1):22, IV(1):23, IV(1):24, IV(1):25 clinical issues, IV(1):24 differential diagnosis, IV(1):23 imaging, IV(1):23, IV(1):25 nasal dermal sinus vs., IV(1):19 nasal glioma vs., IV(1):15 pathology, IV(1):23, IV(1):24 pediatric dermoid/epidermoid cyst vs., III(1):42 solitary sinonasal polyp vs., IV(1):53 staging, grading, & classification, IV(1):24 Fungal sinusitis See also Rhinosinusitis allergic, IV(1):40, IV(1):41 chronic rhinosinusitis vs., IV(1):33 differential diagnosis, IV(1):41 mycetoma vs., IV(1):43 sinonasal mucocele vs., IV(1):57 sinonasal polyposis vs., IV(1):49 chronic rhinosinusitis vs., IV(1):33 invasive, IV(1):44, IV(1):45, IV(1):46, IV(1):47 clinical issues, IV(1):46 differential diagnosis, IV(1):45 imaging, IV(1):45, IV(1):47 mycetoma vs., IV(1):43 nasal cocaine necrosis vs., IV(1):67 orbital cellulitis associated with, IV(2):39 pathology, IV(1):45, IV(1):46 1674 perineural tumor spread vs., II(2):43 post-transplantation lymphoproliferative disorder vs., I(13):15 squamous cell carcinoma vs., IV(1):91 staging, grading, & classification, IV(1):46 Wegener granulomatosis vs., IV(1):63 mycetoma, IV(1):42, IV(1):43 G GM1 Gangliosidosis, mucopolysaccharidosis vs., III(2):25 Gardner syndrome fibromatosis associated with, I(13):33 lipoma of head and neck associated with, I(13):8 masticator space sarcoma associated with, I(4):29 P.xvi sinonasal osteoma associated with, IV(1):71 Garré sclerosing osteomyelitis, McCune-Albright syndrome vs., III(2):22 Gastro-esophageal reflux, supraglottic laryngeal SCCa vs., II(2):35 Giant arachnoid granulation See Dural sinus, and aberrant arachnoid granulations Giant cell granuloma central, cherubism vs., III(2):23 mandible-maxilla, I(15):28, I(15):29 differential diagnosis, I(15):29 simple bone cyst (traumatic) vs., I(15):17 Giant cell tumor pigmented villonodular synovitis of TMJ vs., I(15):25 skull base, V(1):76, V(1):77 differential diagnosis, V(1):77 fibrous dysplasia vs., V(1):61 osteosarcoma associated with, V(1):95 temporal bone fibrous dysplasia vs., VI(7):6, VI(7):7 Giant lymph node hyperplasia (Castleman), I(12):18, I(12):19, I(12):20, I(12):21 clinical issues, I(12):20 differential diagnosis, I(12):19 hyaline vascular, I(12):20 imaging, I(12):19, I(12):21 pathology, I(12):19, I(12):20 plasma cell, I(12):20 staging, grading, & classification, I(12):19 Giant trigeminal schwannoma See Trigeminal schwannoma, skull base, central Gingival squamous cell carcinoma, alveolar ridge See Alveolar ridge squamous cell carcinoma Glaucoma congenital, coloboma vs., IV(2):6 Diagnostic Imaging Head and Neck secondary angle closure, orbital idiopathic inflammatory pseudotumor associated with, IV(2):42 Glial heterotopia, nasal See Nasal glioma Glioma nasal See Nasal glioma optic pathway See Optic pathway glioma Globular vestibule-semicircular canal, VI(4):26 Glomangiopericytoma See Hemangiopericytoma of head and neck Glomus caroticum See Carotid body paraganglioma Glomus jugulare paraganglioma, V(1):30, V(1):31, V(1):32, V(1):33 clinical issues, V(1):32 dehiscent jugular bulb vs., V(1):27 differential diagnosis, V(1):31, V(1):32 endolymphatic sac tumor vs., VI(4):49 glomus tympanicum paraganglioma vs., VI(3):43 high jugular bulb vs., V(1):25 hypoglossal nerve schwannoma vs., V(1):21 imaging, V(1):31, V(1):33 jugular bulb diverticulum vs., V(1):29 jugular bulb pseudolesion vs., V(1):23 jugular foramen meningioma vs., V(1):39 jugular foramen schwannoma vs., V(1):35 lateralized internal carotid artery vs., VI(3):11 middle ear cholesterol granuloma vs., VI(3):39 pathology, V(1):32 staging, grading, & classification, V(1):32 temporal bone meningioma vs., VI(3):47, VI(3):48 Glomus tympanicum paraganglioma, VI(3):42, VI(3):43, VI(3):44, VI(3):45 aberrant internal carotid artery vs., VI(3):13 clinical issues, VI(3):44 congenital middle ear cholesteatoma vs., VI(3):3 dehiscent jugular bulb vs., V(1):27 differential diagnosis, VI(3):43 imaging, VI(3):43, VI(3):45 lateralized internal carotid artery vs., VI(3):11 middle ear adenoma vs., VI(3):53 middle ear cholesterol granuloma vs., VI(3):39 middle ear schwannoma vs., VI(3):51 pars flaccida cholesteatoma vs., VI(3):29 pars tensa cholesteatoma vs., VI(3):33 pathology, VI(3):43, VI(3):44 staging, grading, & classification, VI(3):44 temporal bone meningioma vs., VI(3):47, VI(3):48 Glomus vagale paraganglioma, I(6):28, I(6):29, I(6):30, I(6):31 carotid artery dissection vs., I(6):9 carotid body paraganglioma vs., I(6):25 carotid meningioma vs., I(6):41 carotid neurofibroma vs., I(6):38 carotid schwannoma vs., I(6):33 clinical issues, I(6):30 differential diagnosis, I(6):29 imaging, I(6):29, I(6):31 pathology, I(6):30 staging, grading, & classification, I(6):30 sympathetic schwannoma vs., I(6):37 Glottic laryngeal squamous cell carcinoma, II(2):38, II(2):39 differential diagnosis, II(2):39 staging, grading, & classification, II(2):39 subglottic laryngeal SCCa vs., II(2):41 vocal cord paralysis vs., I(11):29 Goiter, multinodular, I(10):8, I(10):9, I(10):10, I(10):11 anaplastic thyroid carcinoma vs., I(10):29 chronic lymphocytic thyroiditis vs., I(10):7 clinical issues, I(10):10 differential diagnosis, I(10):9, I(10):10 differentiated thyroid carcinoma vs., I(10):21 imaging, I(10):9, I(10):11 medullary thyroid carcinoma vs., I(10):25 non-Hodgkin thyroid lymphoma vs., I(10):33 parathyroid adenoma vs., I(10):17 pathology, I(10):10 thyroid adenoma vs., I(10):13 Goldenhar syndrome See also Hemifacial microsomia P.xvii solitary median maxillary central incisor related to, I(15):9 Gorlin-Goltz syndrome See Basal cell nevus syndrome Granuloma, cholesterol See Cholesterol granuloma Graves ophthalmopathy See Thyroid ophthalmopathy H Hamartoma angiomatous lymphoid See Giant lymph node hyperplasia (Castleman) fibromatous or angiofibromatous See Juvenile angiofibroma lingual, congenital vallecular cyst vs., III(1):15 lymph node See Giant lymph node hyperplasia (Castleman) 1675 Hamartomatous lipoma See Lipoma, CPA-IAC, congenital Hand-Schüller-Christian disease See Langerhans cell histiocytosis Hard palate squamous cell carcinoma, II(2):27 differential diagnosis, II(2):27 palate benign mixed tumor vs., I(14):35 Hashimoto thyroiditis See Thyroiditis, chronic lymphocytic (Hashimoto) Hearing device, semi-implantable direct drive, ossicular prosthesis vs., VI(3):62 Hearing loss sensorineural, imaging approaches to imaging issues, VI(8):2, VI(8):3 techniques and indications, VI(8):2 X-linked stapes gusher (DFNX2), VI(4):18, VI(4):19 Heffner tumor See Endolymphatic sac tumor Hemangioblastoma, glomus vagale paraganglioma associated with, VI(6):30 Hemangioma cavernous See Cavernous hemangioma choroidal, ocular melanoma vs., IV(2):75 congenital (RICH/NICH), infantile hemangioma vs., III(1):47 cutaneous, upper airway infantile hemangioma associated with, I(11):17 facial nerve See Facial nerve, intratemporal, venous malformation (hemangioma) infantile, III(1):46, III(1):47, III(1):48, III(1):49 clinical issues, III(1):48 differential diagnosis, III(1):47, III(1):48 imaging, III(1):47, III(1):49 pathology, III(1):48 venous malformation vs., III(1):12 infantile, orbital, IV(2):56, IV(2):57, IV(2):58, IV(2):59 clinical issues, IV(2):58 differential diagnosis, IV(2):57 imaging, IV(2):57, IV(2):59 lymphatic malformation vs., IV(2):23 pathology, IV(2):57, IV(2):58 pediatric dermoid/epidermoid cyst vs., III(1):41 staging, grading, & classification, IV(2):58 venous varix vs., IV(2):27 infantile, upper airway, I(11):16, I(11):17 differential diagnosis, I(14):17 lingual thyroid vs., I(14):19 staging, grading, & classification, I(11):17 internal auditory canal (venous malformation), VI(8):18, VI(8):19 sinonasal, IV(1):86, IV(1):87 differential diagnosis, IV(1):87 juvenile angiofibroma vs., IV(1):79 Diagnostic Imaging Head and Neck sphenoid benign fatty lesion vs., V(1):18 subglottic infantile, acquired subglottictracheal stenosis vs., I(11):33 Hemangiomatosis, systemic, orbital cavernous hemangioma associated with, IV(2):30 Hemangiopericytoma of head and neck, I(13):10, I(13):11 differential diagnosis, I(13):11 malignant peripheral nerve sheath tumor vs., I(13):27 orbital cavernous hemangioma vs., IV(2):29 sinonasal hemangioma vs., IV(1):87 synovial sarcoma of head and neck vs., I(13):25 Hematologic malignancy, orbital lymphoproliferative lesions associated with, IV(2):79 Hematoma postoperative, lymphocele of neck vs., I(13):29 subperiosteal, orbital subperiosteal abscess vs., IV(2):35 Hemifacial microsomia, III(2):18 Hemifacial spasm, VI(8):42, VI(8):43 Hemorrhage, intralabyrinthine, VI(4):50, VI(4):51 differential diagnosis, VI(4):51 intralabyrinthine schwannoma vs., VI(4):45 labyrinthitis vs., VI(4):33 Hemotympanum, traumatic, middle ear cholesterol granuloma vs., VI(3):39 Herpes zoster oticus See Ramsay Hunt syndrome Herpetic facial neuritis See Bell palsy Hibernoma, I(13):8 High jugular bulb See Jugular bulb, high Histiocytic necrotizing lymphadenitis (Kikuchi) See Lymphadenitis, histiocytic necrotizing (Kikuchi) Histiocytosis X See Langerhans cell histiocytosis HIV See also Lymphoepithelial lesionsHIV, benign nodal Hodgkin lymphoma in neck associated with, I(12):33 Hodgkin lymphoma in neck, nodal, I(12):32, I(12):33, I(12):34, I(12):35 clinical issues, I(12):34 differential diagnosis, I(12):33 P.xviii imaging, I(12):33, I(12):35 metastatic neuroblastoma vs., III(1):55 nodal non-Hodgkin lymphoma in neck vs., I(12):29 primary cervical neuroblastoma vs., III(1):54 staging, grading, & classification, I(12):33, I(12):34 Holoprosencephaly, congenital nasal pyriform aperture stenosis associated with, IV(1):27 Horner syndrome post-ganglionic, I(6):3 skull base trauma associated with, V(2):12 Human papilloma virus (HPV) infection lingual tonsil squamous cell carcinoma associated with, II(2):7 palatine tonsil squamous cell carcinoma associated with, II(2):11 Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma, II(2):15 Hyaloid artery, coloboma associated with, IV(2):8 Hypoglossal artery, persistent, hypoglossal nerve schwannoma vs., V(1):21 Hypoglossal canal venous drainage, asymmetric, hypoglossal nerve schwannoma vs., V(1):21 Hypoglossal nerve motor denervation, I(14):8, I(14):9 schwannoma, V(1):20, V(1):21 Hyponatremia, esthesioneuroblastoma associated with, IV(1):95 Hypopharyngeal squamous cell carcinoma cervical esophageal carcinoma vs., I(10):37 post-cricoid region, II(2):32 posterior hypopharyngeal wall, II(2):33 differential diagnosis, II(2):33 post-cricoid region SCCa vs., II(2):32 posterior oropharyngeal wall SCCa vs., II(2):14 pyriform sinus, II(2):28, II(2):29, II(2):30, II(2):31 retropharyngeal space abscess vs., I(7):11 retropharyngeal space edema vs., I(7):15 Hypopharynx, I(11):2, I(11):3, I(11):4, I(11):5, I(11):6, I(11):7, I(11):8, I(11):9, I(11):10, I(11):11, I(11):12, I(11):13, I(11):14, I(11):15, I(11):16, I(11):17, I(11):18, I(11):19, I(11):20, I(11):21, I(11):22, I(11):23, I(11):24, I(11):25, I(11):26, I(11):27, I(11):28, I(11):29, I(11):30, I(11):31, I(11):32, I(11):33, I(11):34, I(11):35 See also Larynx; Trachea clinical issues, I(11):3 differential diagnosis, I(11):3 embryology, I(11):2 images, I(11):4, I(11):5, I(11):6, I(11):7 imaging anatomy, I(11):2, I(11):3 approaches to imaging issues, I(11):3 techniques and indications, I(11):2 lateral pouch, laryngocele vs., I(11):26 minor salivary gland malignancy, pyriform sinus squamous cell carcinoma vs., II(2):29 1676 overview, I(11):2, I(11):3, I(11):4, I(11):5, I(11):6, I(11):7 posterior diverticulum See Esophagopharyngeal diverticulum (Zenker) upper airway infantile hemangioma, I(11):16, I(11):17 differential diagnosis, I(14):17 lingual thyroid vs., I(14):19 staging, grading, & classification, I(11):17 Hypophyseal canal See Craniopharyngeal canal, persistent Hypothalmic-pituitary disease skull base Langerhans cell histiocytosis associated with, V(1):68 T-bone Langerhans cell histiocytosis associated with, VI(7):11 I Idiopathic inflammatory pseudotumor See Pseudotumor, idiopathic inflammatory Imploding antrum See Silent sinus syndrome Incisive canal cyst See Nasopalatine duct cyst Incisor, single central See Solitary median maxillary central incisor Incomplete cochlear partition type I See Cochlear incomplete partition type I (IP-I) Incomplete cochlear partition type II See Vestibular aqueduct (IP-II), large Incus dislocation, post-traumatic, ossicular prosthesis vs., VI(3):62 interposition graft, VI(3):61 interposition procedure, temporal bone trauma vs., V(2):8 Infantile fibromatosis See Fibromatosis of head and neck Infantile hemangioma See Hemangioma, infantile Infectious meningitis See Meningitis, CPA-IAC Inflammation, reactive adenopathy associated with, I(7):7 Inflammatory disease idiopathic, orbital sarcoidosis vs., IV(2):45 post-obstructive, solitary sinonasal polyp associated with, IV(1):54 Inflammatory idiopathic pseudotumor See Pseudotumor, idiopathic inflammatory Infrahyoid neck See Suprahyoid and infrahyoid neck Infratentorial abnormalities skull base Langerhans cell histiocytosis associated with, V(1):68 T-bone Langerhans cell histiocytosis associated with, VI(7):11 Inner ear, VI(4):2, VI(4):3, VI(4):4, VI(4):5, VI(4):6, VI(4):7, VI(4):8, VI(4):9, Diagnostic Imaging Head and Neck VI(4):10, VI(4):11, VI(4):12, VI(4):13, VI(4):14, VI(4):15, VI(4):16, VI(4):17, VI(4):18, VI(4):19, VI(4):20, VI(4):21, VI(4):22, VI(4):23, VI(4):24, VI(4):25, VI(4):26, VI(4):27, VI(4):28, VI(4):29, VI(4):30, VI(4):31, VI(4):32, VI(4):33, VI(4):34, VI(4):35, VI(4):36, VI(4):37, VI(4):38, VI(4):39, VI(4):40, VI(4):41, VI(4):42, VI(4):43, VI(4):44, VI(4):45, VI(4):46, VI(4):47, VI(4):48, VI(4):49, VI(4):50, VI(4):51, VI(4):52, VI(4):53, VI(4):54, VI(4):55, VI(4):56, VI(4):57 CHARGE syndrome, VI(4):28, VI(4):29, VI(4):30, VI(4):31 cochlear aplasia See Cochlear aplasia cochlear cleft, VI(4):4, VI(4):5 cochlear hypoplasia See Cochlear hypoplasia cochlear implants, VI(4):54, VI(4):55, VI(4):56, VI(4):57 cochlear incomplete partition type I (IPI), VI(4):12, VI(4):13 cochlear hypoplasia vs., VI(4):23 differential diagnosis, VI(4):13 P.xix globular vestibule-semicircular canal vs., VI(4):26 X-linked stapes gusher vs., VI(4):19 cochlear nerve and cochlear nerve canal aplasia-hypoplasia, VI(4):24, VI(4):25 cochlear implantation considerations, VI(4):56 differential diagnosis, VI(4):25 common cavity cystic cochleovestibular anomaly vs., VI(4):11 labyrinthine aplasia vs., VI(4):7 common cavity malformation, VI(4):8, VI(4):9 cochlear aplasia vs., VI(4):21 cochlear implantation considerations, VI(4):56 cochlear incomplete partition type vs., VI(4):13 cystic cochleovestibular malformation See Cochleovestibular malformation (IP-I), cystic differential diagnosis, VI(1):4 endolymphatic sac tumor, VI(4):48, VI(4):49 differential diagnosis, VI(4):49 glomus vagale paraganglioma associated with, VI(6):30 staging, grading, & classification, VI(4):49 temporal bone arachnoid granulations vs., VI(7):5 globular vestibule-semicircular canal, VI(4):26 imaging anatomy, VI(1):3 intralabyrinthine hemorrhage, VI(4):50, VI(4):51 differential diagnosis, VI(4):51 intralabyrinthine schwannoma vs., VI(4):45 labyrinthitis vs., VI(4):33 intralabyrinthine schwannoma See Intralabyrinthine schwannoma labyrinthine aplasia See Labyrinthine aplasia labyrinthine ossificans See Labyrinthine ossificans labyrinthitis, VI(4):32, VI(4):33 differential diagnosis, VI(4):33 intralabyrinthine hemorrhage vs., VI(4):51 intralabyrinthine schwannoma vs., VI(4):45 large vestibular aqueduct (IP-II) See Vestibular aqueduct (IP-II), large otosclerosis See Otosclerosis otosyphilis, VI(4):34, VI(4):35 differential diagnosis, VI(4):35 temporal bone osteoradionecrosis vs., VI(7):15 semicircular canal dehiscence, VI(4):52, VI(4):53 hypoplasia-aplasia, VI(4):27 normal thinning, SSC dehiscence vs., VI(4):53 superior, dehiscence, temporal bone cephalocele associated with, VI(3):59 subarcuate canaliculus, VI(4):2, VI(4):3 X-linked stapes gusher (DFNX2), VI(4):18, VI(4):19 Internal auditory canal See also CPAIAC venous malformation, VI(8):18, VI(8):19 Internal carotid artery See Carotid artery Internal maxillary arterial branches, prominent, pterygoid venous plexus asymmetry vs., I(4):7 Intracranial abnormalities frontoethmoidal cephalocele associated with, IV(1):24 lymphatic malformation associated with, III(1):8 venous malformation associated with, III(1):12 Intracranial trauma laryngeal trauma associated with, I(11):13 skull base trauma associated with, V(2):12 Intracranial vascular malformations, orbital lymphatic malformation associated with, IV(2):24 Intralabyrinthine hemorrhage, VI(4):50, VI(4):51 differential diagnosis, VI(4):51 intralabyrinthine schwannoma vs., VI(4):45 labyrinthitis vs., VI(4):33 Intralabyrinthine lipoma, congenital, intralabyrinthine hemorrhage vs., VI(4):51 1677 Intralabyrinthine schwannoma, VI(4):44, VI(4):45, VI(4):46, VI(4):47 clinical issues, VI(4):46 differential diagnosis, VI(4):45 imaging, VI(4):45, VI(4):47 intralabyrinthine hemorrhage vs., VI(4):51 labyrinthine ossificans vs., VI(4):37 labyrinthitis vs., VI(4):33 pathology, VI(4):45, VI(4):46 Intranodal abscess See Lymph nodes, suppurative Intraorbital (postseptal) cellulitis See Cellulitis, orbital Intratemporal facial nerve See Facial nerve, intratemporal Intratonsillar abscess See Tonsillar/peritonsillar abscess Intratympanic meningioma See Meningioma, temporal bone Intravestibular lipoma, labyrinthine ossificans vs., VI(4):37 Invasive fungal sinusitis See Fungal sinusitis Inverted papilloma See Papilloma, inverted Iris coloboma, coloboma associated with, IV(2):8 J Jacobson nerve schwannoma See Schwannoma, middle ear Jaffe-Campanacci syndrome, McCuneAlbright syndrome vs., III(2):22 Jaffe-Lichtenstein dysplasia See Fibrous dysplasia, skull base Jugular bulb, dehiscent, V(1):26, V(1):27 aberrant internal carotid artery vs., VI(3):14 P.xx differential diagnosis, V(1):27 glomus jugulare paraganglioma vs., V(1):32 glomus tympanicum paraganglioma vs., VI(3):43 high jugular bulb vs., V(1):25 jugular bulb diverticulum vs., V(1):29 jugular bulb pseudolesion vs., V(1):23 jugular foramen meningioma vs., V(1):39 middle ear cholesterol granuloma vs., VI(3):39 petrous ICA aneurysm vs., VI(5):23 temporal bone meningioma vs., VI(3):47, VI(3):48 Jugular bulb, high, V(1):24, V(1):25 dehiscent jugular bulb vs., V(1):27 differential diagnosis, V(1):25 jugular bulb diverticulum vs., V(1):29 jugular bulb pseudolesion vs., V(1):23 large vestibular aqueduct vs., VI(4):15 Diagnostic Imaging Head and Neck Jugular bulb diverticulum, V(1):28, V(1):29 dehiscent jugular bulb vs., V(1):27 differential diagnosis, V(1):29 high jugular bulb vs., V(1):25 Jugular bulb pseudolesion, V(1):22, V(1):23 differential diagnosis, V(1):22, V(1):23 high jugular bulb vs., V(1):25 jugular bulb diverticulum vs., V(1):29 Jugular bulb thrombosis-sigmoid sinus, jugular bulb pseudolesion vs., V(1):23 Jugular foramen asymmetry, dehiscent jugular bulb vs., V(1):27 meningioma See Jugular foramen meningioma metastases glomus jugulare paraganglioma vs., V(1):31 jugular foramen meningioma vs., V(1):39 paraganglioma See Glomus jugulare paraganglioma pseudolesion glomus jugulare paraganglioma vs., V(1):31, V(1):32 jugular foramen meningioma vs., V(1):39 jugular foramen schwannoma vs., V(1):35 schwannoma See Jugular foramen schwannoma Jugular foramen meningioma, V(1):38, V(1):39 dehiscent jugular bulb vs., V(1):27 differential diagnosis, V(1):39 endolymphatic sac tumor vs., VI(4):49 glomus jugulare paraganglioma vs., V(1):31 high jugular bulb vs., V(1):25 hypoglossal nerve schwannoma vs., V(1):21 jugular bulb pseudolesion vs., V(1):23 jugular foramen schwannoma vs., V(1):35 staging, grading, & classification, V(1):39 Jugular foramen schwannoma, V(1):34, V(1):35, V(1):36, V(1):37 clinical issues, V(1):36 dehiscent jugular bulb vs., V(1):27 differential diagnosis, V(1):35 endolymphatic sac tumor vs., VI(4):49 glomus jugulare paraganglioma vs., V(1):31 high jugular bulb vs., V(1):25 imaging, V(1):35, V(1):37 jugular bulb diverticulum vs., V(1):29 jugular bulb pseudolesion vs., V(1):23 jugular foramen meningioma vs., V(1):39 pathology, V(1):35, V(1):36 staging, grading, & classification, V(1):36 Jugular vein, internal, slow or turbulent flow (pseudothrombosis), jugular vein thrombosis vs., I(6):19 Jugular vein thrombosis, I(6):18, I(6):19, I(6):20, I(6):21 carotid space schwannoma vs., I(6):33 clinical issues, I(6):20 differential diagnosis, I(6):19, I(6):20 glomus vagale paraganglioma vs., I(6):29 imaging, I(6):19, I(6):21 pathology, I(6):20 post-pharyngitis venous thrombosis (Lemierre) vs., I(6):23 Jugulodigastric lymph node, carotid body paraganglioma vs., I(6):25 Juvenile angiofibroma, IV(1):78, IV(1):79, IV(1):80, IV(1):81 clinical issues, IV(1):80 differential diagnosis, IV(1):79, IV(1):80 imaging, IV(1):79, IV(1):81 inverted papilloma vs., IV(1):83 melanoma vs., IV(1):101 pathology, IV(1):80 sinonasal benign mixed tumor vs., IV(1):89 sinonasal hemangioma vs., IV(1):87 solitary sinonasal polyp vs., IV(1):53 staging, grading, & classification, IV(1):80 Juvenile idiopathic arthritis, temporomandibular joint, I(15):20, I(15):21 Juvenile-aggressive ossifying fibroma See Fibroma, ossifying, sinonasal K Kallmann syndrome, CHARGE syndrome of inner ear vs., VI(4):29 Keratocystic odontogenic tumor, I(15):34, I(15):35, I(15):36, I(15):37 ameloblastoma vs., I(15):31 basal cell nevus syndrome vs., III(2):9 clinical issues, I(15):35 CNV3 schwannoma of masticator space vs., I(4):19 dentigerous cyst vs., I(15):15 differential diagnosis, I(15):35 imaging, I(15):35, I(15):36, I(15):37 masticator space sarcoma vs., I(4):29 nasopalatine duct cyst vs., I(15):19 pathology, I(15):35 periapical (radicular) cyst vs., I(15):13 simple bone cyst (traumatic) vs., I(15):17 Keratosis obturans, external auditory canal, VI(2):8, VI(2):9 P.xxi cholesteatoma vs., VI(2):15 differential diagnosis, VI(2):9 medial canal fibrosis vs., VI(2):11 1678 Kidney disease, autosomal dominant, carotid artery dissection in neck associated with, I(6):10 Kikuchi-Fujimoto disease See Lymphadenitis, histiocytic necrotizing (Kikuchi) Killian polyp See Polyp, solitary sinonasal Kimura disease, I(12):24, I(12):25, I(12):26, I(12):27 clinical issues, I(12):26 differential diagnosis, I(12):25 imaging, I(12):25, I(12):27 pathology, I(12):25, I(12):26 sarcoidosis lymph nodes vs., I(12):17 Klestadt cyst See Nasolabial cyst L Labyrinthine aplasia, VI(4):6, VI(4):7 cochlear aplasia vs., VI(4):21 cochlear implantation considerations, VI(4):56 common cavity malformation vs., VI(4):9 differential diagnosis, VI(4):7 labyrinthine ossificans vs., VI(4):37 Labyrinthine ossificans, VI(4):36, VI(4):37, VI(4):38, VI(4):39 clinical issues, VI(4):38 cochlear aplasia vs., VI(4):21 differential diagnosis, VI(4):37 imaging, VI(4):37, VI(4):39 intralabyrinthine schwannoma vs., VI(4):45 labyrinthine aplasia vs., VI(4):7 labyrinthitis vs., VI(4):33 pathology, VI(4):37, VI(4):38 semicircular canal hypoplasia-aplasia vs., VI(4):27 Labyrinthine schwannoma See Intralabyrinthine schwannoma Labyrinthitis, VI(4):32, VI(4):33 chronic See Labyrinthine ossificans differential diagnosis, VI(4):33 intralabyrinthine hemorrhage vs., VI(4):51 intralabyrinthine schwannoma vs., VI(4):45 luetic See Otosyphilis Lacrimal cyst lacrimal gland benign mixed tumor vs., IV(2):69 orbital dermoid/epidermoid cyst vs., IV(2):15 Lacrimal gland benign mixed tumor, IV(2):68, IV(2):69 differential diagnosis, IV(2):69 lacrimal gland carcinoma vs., IV(2):83 orbital lymphoproliferative lesions vs., IV(2):79 staging, grading, & classification, IV(2):69 Lacrimal gland carcinoma, IV(2):82, IV(2):83 differential diagnosis, IV(2):83 Diagnostic Imaging Head and Neck lacrimal gland benign mixed tumor vs., IV(2):69 staging, grading, & classification, IV(2):83 Lamina papyracea, dehiscent, orbital blowout fracture vs., V(2):17 Langerhans cell histiocytosis metastatic neuroblastoma vs., III(1):55 orbital, IV(2):54, IV(2):55 differential diagnosis, IV(2):55 infantile hemangioma vs., IV(2):57 pediatric dermoid/epidermoid cyst vs., III(1):41 staging, grading, & classification, IV(2):55 osteosarcoma of mandible-maxilla vs., I(15):39 sinus histiocytosis vs., I(13):31 skull base, V(1):66, V(1):67, V(1):68, V(1):69 clinical issues, V(1):68 differential diagnosis, V(1):67 imaging, V(1):67, V(1):69 pathology, V(1):67, V(1):68 staging, grading, & classification, V(1):68 temporal bone, VI(7):10, VI(7):11 acute otomastoiditis with abscess vs., VI(3):19 coalescent otomastoiditis vs., VI(3):23 congenital mastoid cholesteatoma vs., VI(3):6 differential diagnosis, VI(7):11 T-bone metastasis vs., VI(7):13 temporal bone rhabdomyosarcoma vs., VI(3):55 Large vestibular aqueduct See Vestibular aqueduct (IP-II), large Larva migrans, ocular See Toxocariasis, ocular Laryngeal neoplasms adenoid cystic carcinoma subglottic laryngeal SCCa vs., II(2):41 supraglottic laryngeal SCCa vs., II(2):35 chondrosarcoma, I(11):18, I(11):19, I(11):20, I(11):21 clinical issues, I(11):20 differential diagnosis, I(11):19 imaging, I(11):19, I(11):21 staging, grading, & classification, I(11):19, I(11):20 subglottic laryngeal SCCa vs., II(2):41 squamous cell carcinoma See Laryngeal squamous cell carcinoma Laryngeal squamous cell carcinoma glottic, II(2):38, II(2):39 differential diagnosis, II(2):39 staging, grading, & classification, II(2):39 subglottic laryngeal SCCa vs., II(2):41 vocal cord paralysis vs., I(11):29 subglottic, II(2):40, II(2):41 differential diagnosis, II(2):41 staging, grading, & classification, II(2):41 supraglottic, II(2):34, II(2):35, II(2):36, II(2):37 clinical issues, II(2):37 differential diagnosis, II(2):35 imaging, II(2):35, II(2):37 pathology, II(2):36 staging, grading, & classification, II(2):36 supraglottitis vs., I(11):11 P.xxii transglottic, post-radiation larynx vs., I(11):23 Laryngeal trauma, I(11):12, I(11):13, I(11):14, I(11):15 caustic or thermal, supraglottitis vs., I(11):11 clinical issues, I(11):14 differential diagnosis, I(11):13 imaging, I(11):13, I(11):15 post-radiation larynx vs., I(11):23 staging, grading, & classification, I(11):13 subglottic laryngeal SCCa vs., II(2):41 supraglottitis vs., I(11):11 vocal cord paralysis vs., I(11):29 Laryngocele, I(11):24, I(11):25, I(11):26, I(11):27 clinical issues, I(11):26 differential diagnosis, I(11):25, I(11):26 external, 3rd branchial cleft cyst vs., III(1):34 imaging, I(11):25, I(11):27 internal, definition of, I(11):25 mixed definition of, I(11):25 thyroglossal duct cyst vs., III(1):17 pathology, I(11):26 secondary, definition of, I(11):25 supraglottic laryngeal SCCa vs., II(2):35 vocal cord paralysis vs., I(11):29 Laryngotracheal stenosis See Subglottic-tracheal stenosis Laryngotracheobronchitis, acute See Croup Larynx See also Hypopharynx; Trachea; Vocal cord paralysis clinical issues, I(11):3 differential diagnosis, I(11):3 embryology, I(11):2 epiglottitis adult See Supraglottitis child, I(11):10 croup vs., I(11):9 supraglottitis vs., I(11):11 images, I(11):4, I(11):5, I(11):6, I(11):7 imaging anatomy, I(11):2, I(11):3 approaches to imaging issues, I(11):3 techniques and indications, I(11):2 neoplasms See Laryngeal neoplasms nodular chondrometaplasia, laryngeal chondrosarcoma vs., I(11):19 overview, I(11):2, I(11):3, I(11):4, I(11):5, I(11):6, I(11):7 1679 post-radiation, I(11):22, I(11):23 differential diagnosis, I(11):23 laryngeal trauma vs., I(11):13 supraglottitis vs., I(11):11 rheumatoid subglottic laryngeal SCCa vs., II(2):41 supraglottic laryngeal SCCa vs., II(2):35 saccule definition of, I(11):25 laryngocele vs., I(11):25 sarcoidosis, supraglottic laryngeal SCCa vs., II(2):35 squamous cell carcinoma See Laryngeal squamous cell carcinoma supraglottitis, I(11):11 differential diagnosis, I(11):11 post-radiation larynx vs., I(11):23 pyriform sinus squamous cell carcinoma vs., II(2):29 with abscess, laryngocele vs., I(11):26 trauma See Laryngeal trauma upper airway infantile hemangioma, I(11):16, I(11):17 differential diagnosis, I(14):17 lingual thyroid vs., I(14):19 staging, grading, & classification, I(11):17 Lateral cervical esophageal diverticulum, I(10):41 Lateral internal carotid artery See Carotid artery, aberrant internal Lateralized internal carotid artery See Carotid artery, lateralized internal Le Fort (trans-facial) fracture See Trans-facial fracture (Le Fort) Left lymphatic duct See Thoracic duct, prominent, in neck Leptomeningitis See Meningitis, CPAIAC Letterer-Siwe disease See Langerhans cell histiocytosis Leukemia, orbital infantile hemangioma vs., IV(2):57 Langerhans cell histiocytosis vs., IV(2):55 Leukocoria, other causes, retinoblastoma vs., IV(2):71 Levator scapulae muscle hypertrophy, I(8):6, I(8):7 Li-Fraumeni syndrome, masticator space sarcoma associated with, I(4):29 Lingual hamartoma, congenital vallecular cyst vs., III(1):15 Lingual thyroid, I(14):18, I(14):19 congenital vallecular cyst vs., III(1):15 differential diagnosis, I(14):18, I(14):19 thyroglossal duct cyst vs., III(1):17 Lingual tonsil lymphoid hyperplasia, lingual tonsil SCC vs., II(2):7 neoplasms, lingual tonsil SCC vs., II(2):7 Lingual tonsil squamous cell carcinoma, II(2):6, II(2):7, II(2):8, II(2):9 clinical issues, II(2):9 differential diagnosis, II(2):7 Diagnostic Imaging Head and Neck hypoglossal nerve motor denervation vs., I(14):9 imaging, II(2):7, II(2):9 non-Hodgkin lymphoma vs., I(3):19 oral tongue SCCa vs., II(2):17 pathology, II(2):7, II(2):8 staging, grading, & classification, II(2):7, II(2):8 Lipoblastoma, I(13):8 Lipoma CPA-IAC, congenital, VI(8):14, VI(8):15, VI(8):16, VI(8):17 clinical issues, VI(8):16 P.xxiii differential diagnosis, VI(8):15 imaging, VI(8):15, VI(8):17 pathology, VI(8):15, VI(8):16 head and neck, I(13):6, I(13):7, I(13):8, I(13):9 clinical issues, I(13):8 differential diagnosis, I(13):7 imaging, I(13):7, I(13):9 pathology, I(13):7, I(13):8 infiltrating, I(13):8 intralabyrinthine, congenital, intralabyrinthine hemorrhage vs., VI(4):51 intravestibular, labyrinthine ossificans vs., VI(4):37 liposarcoma of head and neck vs., I(13):23 retropharyngeal space, RPS edema vs., I(7):15 spindle cell, I(13):8 Lipomatosis benign symmetric, lipoma of head and neck associated with, I(13):7 familial multiple, lipoma of head and neck associated with, I(13):7 Lipomatous hamartoma See Lipoma, CPA-IAC, congenital Liposarcoma of head and neck, I(13):22, I(13):23 differential diagnosis, I(13):23 lipoma vs., I(13):7 staging, grading, & classification, I(13):23 Loeffler syndrome, Kimura disease associated with, I(12):26 Longus colli tendinitis acute calcific, I(8):8, I(8):9 vertebral body metastasis vs., I(8):21 Luetic labyrinthitis, osteitis, and meningitis See Otosyphilis Lung metastases, post-pharyngitis venous thrombosis (Lemierre) vs., I(6):23 Lymph nodes, I(12):2, I(12):3, I(12):4, I(12):5, I(12):6, I(12):7, I(12):8, I(12):9, I(12):10, I(12):11, I(12):12, I(12):13, I(12):14, I(12):15, I(12):16, I(12):17, I(12):18, I(12):19, I(12):20, I(12):21, I(12):22, I(12):23, I(12):24, I(12):25, I(12):26, I(12):27, I(12):28, I(12):29, I(12):30, I(12):31, I(12):32, I(12):33, I(12):34, I(12):35, I(12):36, I(12):37, I(12):38, I(12):39 clinical implications, I(12):3 differential diagnosis, I(12):3 giant lymph node hyperplasia (Castleman) See Giant lymph node hyperplasia (Castleman) histiocytic necrotizing lymphadenitis (Kikuchi), I(12):22, I(12):23 differential diagnosis, I(12):23 sarcoidosis lymph nodes vs., I(12):17 Hodgkin lymphoma in neck, nodal See Hodgkin lymphoma in neck, nodal images, I(12):4, I(12):5 imaging anatomy, I(12):2 approaches to imaging issues, I(12):3 techniques and indications, I(12):2, I(12):3 jugulodigastric, carotid body paraganglioma vs., I(6):25 Kimura disease, I(12):24, I(12):25, I(12):26, I(12):27 differential diagnosis, I(12):25 sarcoidosis lymph nodes vs., I(12):17 metastatic See Metastases, nodal; Metastases, nodal, systemic nodal differentiated thyroid carcinoma See Thyroid carcinoma, differentiated, nodal nodal neck dissection, II(3):2, II(3):3 differential diagnosis, II(3):2, II(3):3 staging, grading, & classification, II(3):2, II(3):3 non-Hodgkin lymphoma See NonHodgkin lymphoma, nodal non-tuberculous mycobacterium, I(12):16 1st branchial cleft cyst vs., III(1):25 differential diagnosis, I(12):16 suppurative lymph nodes vs., I(12):11 tuberculous lymph nodes vs., I(12):15 overview, I(12):2, I(12):3, I(12):4, I(12):5 parotid, metastatic See Parotid metastatic disease, nodal reactive See Lymph nodes, reactive sarcoidosis See Sarcoidosis, lymph nodes suppurative See Lymph nodes, suppurative systemic nodal metastases See Metastases, nodal, systemic tuberculous See Tuberculous lymph nodes Lymph nodes, reactive, I(12):6, I(12):7, I(12):8, I(12):9 benign mixed tumor vs., I(14):33 clinical issues, I(12):8 differential diagnosis, I(12):7 giant lymph node hyperplasia vs., I(12):19 imaging, I(12):7, I(12):9 metastatic neuroblastoma vs., III(1):55 1680 nodal Hodgkin lymphoma in neck vs., I(12):33 nodal non-Hodgkin lymphoma in neck vs., I(12):29 nodal SCCa vs., II(2):47 parathyroid adenoma vs., I(10):17 pathology, I(12):7, I(12):8 post-transplantation lymphoproliferative disorder vs., I(13):15 primary cervical neuroblastoma vs., III(1):54 retropharyngeal space, I(7):6, I(7):7 differential diagnosis, I(7):7 nodal non-Hodgkin lymphoma vs., I(7):21 non-SCCA metastatic nodes vs., I(7):23 suppurative adenopathy vs., I(7):9 sarcoidosis lymph nodes vs., I(12):17 sinus histiocytosis vs., I(13):31 spinal accessory node non-Hodgkin lymphoma vs., I(9):11 posterior cervical space schwannoma vs., I(9):5 squamous cell carcinoma vs., I(9):9 submandibular gland carcinoma vs., I(14):39 submandibular space accessory salivary tissue vs., I(14):11 nodal non-Hodgkin lymphoma vs., I(14):43 systemic nodal metastases in neck vs., I(12):39 tonsillar/peritonsillar abscess associated with, I(3):13 P.xxiv Lymph nodes, suppurative, I(12):10, I(12):11, I(12):12, I(12):13 1st branchial cleft cyst vs., III(1):25 clinical issues, I(12):12 differential diagnosis, I(12):11 imaging, I(12):11 jugular vein thrombosis vs., I(6):20 lymphatic malformation vs., III(1):7 lymphocele of neck vs., I(13):29 nodal SCCa vs., II(2):47 non-tuberculous mycobacterium vs., I(12):16 pathology, I(12):11, I(12):12 ranula vs., I(14):21 retropharyngeal space differential diagnosis, I(7):9 nodal non-Hodgkin lymphoma vs., I(7):21 non-SCCA metastatic nodes vs., I(7):23 reactive adenopathy vs., I(7):7 RPS abscess vs., I(7):11 spinal accessory node non-Hodgkin lymphoma vs., I(9):11 posterior cervical space schwannoma vs., I(9):5 squamous cell carcinoma vs., I(9):9 submandibular space nodal squamous cell carcinoma vs., I(14):45 Diagnostic Imaging Head and Neck tuberculous lymph nodes vs., I(12):15 Lymphadenitis acute See Lymph nodes, suppurative histiocytic necrotizing (Kikuchi), I(12):22, I(12):23 differential diagnosis, I(12):23 sarcoidosis lymph nodes vs., I(12):17 tuberculous, reactive lymph nodes vs., I(12):7 Lymphadenopathy, 2nd branchial cleft cyst vs., III(1):29 Lymphangioma See Lymphatic malformation Lymphangiomatosis, orbital lymphatic malformation associated with, IV(2):24 Lymphatic duct, left See Thoracic duct, prominent, in neck Lymphatic malformation, III(1):6, III(1):7, III(1):8, III(1):9 1st branchial cleft cyst vs., III(1):25 3rd branchial cleft cyst vs., III(1):33 4th branchial cleft cyst vs., III(1):37 cervical thymic cyst vs., III(1):21 clinical issues, III(1):8 congenital vallecular cyst vs., III(1):15 differential diagnosis, III(1):3, III(1):7 imaging, III(1):7, III(1):9 lipoma of head and neck vs., I(13):7 lymphocele of neck vs., I(13):29 neurofibromatosis type vs., III(2):3 oral cavity, I(14):16, I(14):17 2nd branchial cleft cyst vs., III(1):29 differential diagnosis, I(14):17 hypoglossal nerve motor denervation vs., I(14):9 oral cavity dermoid and epidermoid vs., I(14):13 ranula vs., I(14):21 staging, grading, & classification, I(14):17 sublingual gland carcinoma vs., I(14):37 orbital, IV(2):22, IV(2):23, IV(2):24, IV(2):25 cavernous hemangioma vs., IV(2):29 clinical issues, IV(2):24 differential diagnosis, IV(2):23 imaging, IV(2):23, IV(2):25 pathology, IV(2):23, IV(2):24 pediatric dermoid/epidermoid cyst vs., III(1):41 staging, grading, & classification, IV(2):24 subperiosteal abscess vs., IV(2):35 venous varix vs., IV(2):27 pathology, III(1):8 pediatric dermoid/epidermoid cyst vs., III(1):41 plexiform neurofibroma vs., I(13):13 posterior cervical space schwannoma vs., I(9):5 staging, grading, & classification, III(1):8 sublingual space, sialocele vs., I(14):25 submandibular space, accessory salivary tissue vs., I(14):11 thyroglossal duct cyst vs., III(1):17 venous malformation vs., III(1):11 Lymphocele of neck, I(13):28, I(13):29 differential diagnosis, I(13):29 prominent thoracic duct vs., I(13):5 staging, grading, & classification, I(13):29 Lymphocytic thyroiditis See Thyroiditis, chronic lymphocytic (Hashimoto) Lymphoepithelial lesions-HIV, benign, I(5):14, I(5):15, I(5):16, I(5):17 1st branchial cleft cyst vs., III(1):25 acute parotitis vs., I(5):7 clinical issues, I(5):15 differential diagnosis, I(5):15 imaging, I(5):15, I(5):17 parotid nodal metastatic disease vs., I(5):41 parotid non-Hodgkin lymphoma vs., I(5):37 parotid Sjögren syndrome vs., I(5):11, I(5):12 pathology, I(5):15 Warthin tumor vs., I(5):23 Lymphoepithelioma See Nasopharyngeal carcinoma Lymphogranuloma, eosinophilic hyperplastic See Kimura disease Lymphoid hyperplasia adenoidal benign, nasopharyngeal carcinoma vs., II(2):3 lingual tonsil, lingual tonsil SCC vs., II(2):7 reactive See Lymph nodes, reactive tonsillar, palatine tonsil SCC vs., II(2):11 Lymphoma cavernous sinus, cavernous sinus thrombosis vs., V(1):49 central nervous system, CPA-IAC meningioma vs., VI(8):31 Hodgkin See Hodgkin lymphoma in neck, nodal P.xxv non-Hodgkin See Non-Hodgkin lymphoma perivertebral space infection vs., I(8):12 Lymphoproliferative disorder, posttransplantation, I(13):14, I(13):15 differential diagnosis, I(13):15 non-Hodgkin lymphoma of pharyngeal mucosal space associated with, I(3):19 staging, grading, & classification, I(13):15 Lymphoproliferative lesions, orbital, IV(2):78, IV(2):79, IV(2):80, IV(2):81 cavernous hemangioma vs., IV(2):29 cellulitis vs., IV(2):39 clinical issues, IV(2):80 differential diagnosis, IV(2):79 idiopathic inflammatory pseudotumor vs., IV(2):41 imaging, IV(2):79, IV(2):81 lacrimal gland benign mixed tumor vs., IV(2):69 lacrimal gland carcinoma vs., IV(2):83 lymphatic malformation vs., IV(2):23 1681 optic nerve sheath meningioma vs., IV(2):65 pathology, IV(2):79, IV(2):80 sarcoidosis vs., IV(2):45 staging, grading, & classification, IV(2):80 thyroid ophthalmopathy vs., IV(2):47 M Macroadenoma, pituitary See Pituitary macroadenoma, invasive Madelung disease, lipoma of head and neck associated with, I(13):7 Malignant external otitis See External otitis, necrotizing Malignant fibrous histiocytoma, malignant peripheral nerve sheath tumor vs., I(13):27 Malignant mixed tumor, parotid, I(5):34, I(5):35 Malignant peripheral nerve sheath tumor, I(13):26, I(13):27 brachial plexus schwannoma in perivertebral space vs., I(8):17 differential diagnosis, I(13):27 pathology, I(13):27, III(2):4 synovial sarcoma of head and neck vs., I(13):25 Mandible-maxilla, I(15):2, I(15):3, I(15):4, I(15):5, I(15):6, I(15):7, I(15):8, I(15):9, I(15):10, I(15):11, I(15):12, I(15):13, I(15):14, I(15):15, I(15):16, I(15):17, I(15):18, I(15):19, I(15):20, I(15):21, I(15):22, I(15):23, I(15):24, I(15):25, I(15):26, I(15):27, I(15):28, I(15):29, I(15):30, I(15):31, I(15):32, I(15):33, I(15):34, I(15):35, I(15):36, I(15):37, I(15):38, I(15):39, I(15):40, I(15):41, I(15):42, I(15):43 See also Temporomandibular joint bisphosphonate osteonecrosis, osteomyelitis vs., I(15):23 common lesions, I(15):3 dentigerous cyst See Dentigerous cyst fibrous dysplasia, masticator space chondrosarcoma vs., I(4):25 fractured mandible, V(2):3, V(2):26, V(2):27 giant cell granuloma, I(15):28, I(15):29 differential diagnosis, I(15):29 simple bone cyst (traumatic) vs., I(15):17 images, I(15):4, I(15):5, I(15):7 imaging anatomy, I(15):2, I(15):3 approaches to imaging issues, I(15):3 infiltrative neoplasm, osteomyelitis vs., I(15):23 mandibular lingula, mandible fracture vs., V(2):27 metastases alveolar ridge SCCa vs., II(2):23 masticator space chondrosarcoma vs., I(4):25 masticator space sarcoma vs., I(4):29 Diagnostic Imaging Head and Neck osteonecrosis vs., I(15):43 osteosarcoma vs., I(15):39 nasolabial cyst, I(15):10, I(15):11 nasopalatine duct cyst See Nasopalatine duct cyst ossifying fibroma ameloblastoma vs., I(15):32 giant cell granuloma of mandiblemaxilla vs., I(15):29 masticator space chondrosarcoma vs., I(4):25 osteomyelitis, I(15):22, I(15):23 alveolar ridge SCCa vs., II(2):23 differential diagnosis, I(15):23 masticator space sarcoma vs., I(4):29 osteoradionecrosis vs., I(15):41 osteosarcoma vs., I(15):39 osteonecrosis, I(15):42, I(15):43 alveolar ridge SCCa vs., II(2):23 differential diagnosis, I(15):43 osteomyelitis vs., I(15):23 osteoradionecrosis vs., I(15):41 osteoradionecrosis See Osteoradionecrosis, mandible-maxilla osteosarcoma, I(15):38, I(15):39 alveolar ridge SCCa vs., II(2):23 differential diagnosis, I(15):39 masticator space chondrosarcoma vs., I(4):25 overview, I(15):2, I(15):3, I(15):4, I(15):5, I(15):6, I(15):7 periapical (radicular) cyst See Periapical (radicular) cyst simple bone cyst (traumatic), I(15):16, I(15):17 solitary median maxillary central incisor, I(15):8, I(15):9 zygomaticomaxillary complex fracture See Zygomaticomaxillary complex fracture Mandibular nerve See CNV3 motor denervation, masticator space Marble bone disease See Osteopetrosis, skull base Marfan syndrome carotid artery dissection in neck associated with, I(6):10 keratocystic odontogenic tumor associated with, I(15):35 PHACES association vs., III(2):11 Masseteric hypertrophy, benign See Masticator space, benign muscle hypertrophy Masticator space, I(4):2, I(4):3, I(4):4, I(4):5, I(4):6, I(4):7, I(4):8, I(4):9, I(4):10, I(4):11, I(4):12, I(4):13, I(4):14, I(4):15, I(4):16, I(4):17, I(4):18, I(4):19, I(4):20, I(4):21, I(4):22, I(4):23, I(4):24, I(4):25, I(4):26, I(4):27, I(4):28, I(4):29, I(4):30, I(4):31 abscess, I(4):14, I(4):15, I(4):16, I(4):17 P.xxvi benign masticator muscle hypertrophy vs., I(4):9 clinical issues, I(4):16 CNV3 motor denervation vs., I(4):11 differential diagnosis, I(4):15, I(4):16 imaging, I(4):15, I(4):17 pathology, I(4):16 retromolar trigone SCCa vs., II(2):25 sarcoma vs., I(4):29 benign muscle hypertrophy, I(4):8, I(4):9 CNV3 motor denervation vs., I(4):11 differential diagnosis, I(4):8, I(4):9 masticator space abscess vs., I(4):15 cellulitis-phlegmon, masticator space abscess vs., I(4):15 chondrosarcoma, I(4):24, I(4):25, I(4):26, I(4):27 CNV3 motor denervation vs., I(4):11 differential diagnosis, I(4):25 staging, grading, & classification, I(4):26 clinical implications, I(4):3 CNV3 motor denervation, I(4):10, I(4):11, I(4):12, I(4):13 CNV3 perineural tumor See CNV3 perineural tumor CNV3 schwannoma, I(4):18, I(4):19 differential diagnosis, I(4):19 perineural CNV3 tumor of masticator space vs., I(4):21 differential diagnosis, I(4):3 images, I(4):4, I(4):5 imaging anatomy, I(4):2 approaches to imaging issues, I(4):2, I(4):3 techniques and indications, I(4):2 infection, chondrosarcoma vs., I(4):25 muscle atrophy, masticator space abscess vs., I(4):15 overview, I(4):2, I(4):3, I(4):4, I(4):5, I(4):6, I(4):7, I(4):8, I(4):9, I(4):10, I(4):11, I(4):12, I(4):13, I(4):14, I(4):15, I(4):16, I(4):17, I(4):18, I(4):19, I(4):20, I(4):21, I(4):22, I(4):23, I(4):24, I(4):25, I(4):26, I(4):27, I(4):28, I(4):29, I(4):30, I(4):31 pseudolesion, benign masticator muscle hypertrophy vs., I(4):9 pterygoid venous plexus asymmetry, I(4):6, I(4):7 benign mixed tumor of parapharyngeal space vs., I(2):5 differential diagnosis, I(4):7 perineural CNV3 tumor of masticator space vs., I(4):21 sarcoma, I(4):28, I(4):29, I(4):30, I(4):31 benign masticator muscle hypertrophy vs., I(4):9 differential diagnosis, I(4):29 masticator space abscess vs., I(4):15 staging, grading, & classification, I(4):29, I(4):30 squamous cell carcinoma benign masticator muscle hypertrophy vs., I(4):9 invasive, sarcoma vs., I(4):29 1682 venous malformation, sarcoma vs., I(4):29 Mastoid See also Middle ear-mastoid cholesterol granuloma, congenital mastoid cholesteatoma vs., VI(3):6 congenital cholesteatoma, VI(3):6 imaging anatomy, VI(1):3 Mastoidectomy, mural cholesteatoma vs., VI(3):37 Mastoiditis See Otomastoiditis Maxilla-mandible See Mandiblemaxilla Maxillary arterial branches, internal, prominent, pterygoid venous plexus asymmetry vs., I(4):7 Maxillary central incisor, solitary median, I(15):8, I(15):9 Maxillary sinus atelectasis with enophthalmos See Silent sinus syndrome hypoplasia, silent sinus syndrome vs., IV(1):61 Mazabraud syndrome, McCuneAlbright syndrome vs., III(2):22 McCune-Albright syndrome, III(2):22 See also Fibrous dysplasia, skull base cherubism vs., III(2):23 differential diagnosis, III(2):22 Medial canal fibrosis See External auditory canal, medial canal fibrosis Median palatal cyst, nasopalatine duct cyst vs., I(15):19 Medullary thyroid carcinoma See Thyroid carcinoma, medullary Medulloblastoma, basal cell nevus syndrome associated with, III(2):9 Mega cisterna magna, arachnoid cyst of CPA vs., VI(8):11 Melanoma ocular, IV(2):74, IV(2):75, IV(2):76, IV(2):77 differential diagnosis, IV(2):75 staging, grading, & classification, IV(2):76 sinonasal, IV(1):100, IV(1):101 differential diagnosis, IV(1):101 esthesioneuroblastoma vs., IV(1):95 hemangioma vs., IV(1):87 non-Hodgkin lymphoma vs., IV(1):103 Melanosis, neurocutaneous, CPA-IAC superficial siderosis vs., VI(8):47 Melnick-Fraser syndrome See Branchiootorenal syndrome MEN syndromes skull base fibrous dysplasia associated with, V(1):62 type 1, glomus jugulare paraganglioma associated with, V(1):32 type carotid body paraganglioma associated with, VI(6):26 medullary thyroid carcinoma associated with, I(10):25 Meningeal metastases CPA-IAC meningitis vs., VI(8):21 P.xxvii Diagnostic Imaging Head and Neck skull base idiopathic inflammatory pseudotumor vs., V(1):73 Meningeal non-Hodgkin lymphoma, skull base idiopathic inflammatory pseudotumor vs., V(1):73 Meningioangiomatosis, CPA-IAC superficial siderosis vs., VI(8):47 Meningioma carotid space, I(6):40, I(6):41 carotid space schwannoma vs., I(6):33 differential diagnosis, I(6):41 glomus vagale paraganglioma vs., I(6):29 cavernous sinus, cavernous sinus thrombosis vs., V(1):49 CPA-IAC, VI(8):30, VI(8):31, VI(8):32, VI(8):33 clinical issues, VI(8):32 cystic, arachnoid cyst of CPA vs., VI(8):11 differential diagnosis, VI(8):31 facial nerve schwannoma vs., VI(8):35 IAC venous malformation vs., VI(8):19 imaging, VI(8):31, VI(8):33 pathology, VI(8):32 staging, grading, & classification, VI(8):32 vestibular schwannoma vs., VI(8):27 en plaque, skull base idiopathic inflammatory pseudotumor vs., V(1):73 jugular foramen See Jugular foramen meningioma multiple, sarcoidosis vs., VI(8):25 neurofibromatosis type associated with, III(2):7 optic nerve sheath, IV(2):64, IV(2):65, IV(2):66, IV(2):67 differential diagnosis, IV(2):65 optic neuritis vs., IV(2):51 optic pathway glioma vs., IV(2):61 orbital cavernous hemangioma vs., IV(2):29 staging, grading, & classification, IV(2):66 skull base See Skull base meningioma temporal bone, VI(3):46, VI(3):47, VI(3):48, VI(3):49 clinical issues, VI(3):48 differential diagnosis, VI(3):47, VI(3):48 fibrous dysplasia vs., VI(7):6, VI(7):7 imaging, VI(3):47, VI(3):49 pathology, VI(3):48 Meningitis CPA-IAC, VI(8):20, VI(8):21 differential diagnosis, VI(8):21 metastases vs., VI(8):37 Ramsay Hunt syndrome vs., VI(8):23 sarcoidosis vs., VI(8):25 rhinosinusitis complications associated with, IV(1):38 skull base idiopathic inflammatory pseudotumor vs., V(1):73 Meningocele apical (petrous apex cephalocele), VI(5):4, VI(5):5 lateral, brachial plexus schwannoma in perivertebral space vs., I(8):17 temporal bone (temporal bone cephalocele), VI(3):58, VI(3):59 Mental foramen, mandible fracture vs., V(2):27 Mesiodens, solitary median maxillary central incisor vs., I(15):9 Metastases choroid, ocular melanoma vs., IV(2):75 CPA-IAC See CPA-IAC, metastases jugular foramen glomus jugulare paraganglioma vs., V(1):31 jugular foramen meningioma vs., V(1):39 lung, post-pharyngitis venous thrombosis (Lemierre) vs., I(6):23 mandible-maxilla alveolar ridge SCCa vs., II(2):23 masticator space chondrosarcoma vs., I(4):25 masticator space sarcoma vs., I(4):29 osteonecrosis vs., I(15):43 osteosarcoma vs., I(15):39 meningeal CPA-IAC meningitis vs., VI(8):21 skull base idiopathic inflammatory pseudotumor vs., V(1):73 neuroblastoma, III(1):55 differential diagnosis, III(1):55 orbital infantile hemangioma vs., IV(2):57 primary cervical neuroblastoma vs., III(1):54 nodal cystic, 2nd branchial cleft cyst vs., III(1):29 cystic-necrotic, 3rd branchial cleft cyst vs., III(1):33 retropharyngeal space, non-squamous cell carcinoma, I(7):22, I(7):23 differential diagnosis, I(7):23 reactive adenopathy vs., I(7):7 squamous cell carcinoma See Squamous cell carcinoma, nodal thyroid carcinoma See Thyroid carcinoma, differentiated, nodal nodal, systemic brachial plexus schwannoma in perivertebral space vs., I(8):17 fibromatosis colli vs., III(1):45 histiocytic necrotizing lymphadenitis (Kikuchi) vs., I(12):23 lymphocele of neck vs., I(13):29 neck, I(12):38, I(12):39 differential diagnosis, I(12):39 staging, grading, & classification, I(12):39 nodal differentiated thyroid carcinoma vs., I(12):37 nodal non-Hodgkin lymphoma in neck vs., I(12):29 nodal SCCa vs., II(2):47 1683 P.xxviii prominent thoracic duct vs., I(13):5 reactive lymph nodes vs., I(12):7 orbital cavernous hemangioma vs., IV(2):29 Langerhans cell histiocytosis vs., IV(2):55 lymphoproliferative lesions vs., IV(2):79 optic nerve sheath meningioma vs., IV(2):65 thyroid ophthalmopathy vs., IV(2):47 osseous, metastatic neuroblastoma vs., III(1):55 parotid See Parotid metastatic disease petrous apex, apical petrositis vs., VI(5):19 sinonasal osteosarcoma vs., IV(1):109 skull base See Skull base metastasis soft tissue, fibromatosis vs., I(13):33 synovial sarcoma of head and neck vs., I(13):25 temporal bone, VI(7):12, VI(7):13 differential diagnosis, VI(7):13 fibrous dysplasia vs., VI(7):6, VI(7):7 vertebral body, in perivertebral space, I(8):20, I(8):21, I(8):22, I(8):23 chordoma in perivertebral space vs., I(8):19 differential diagnosis, I(8):21 infection vs., I(8):12 staging, grading, & classification, I(8):22 Microphthalmus coloboma associated with, IV(2):8 congenital, coloboma vs., IV(2):6 Microsomia bilateral facial branchiootorenal syndrome vs., III(2):15 Treacher Collins syndrome vs., III(2):19 hemifacial, III(2):18 Middle ear-mastoid, VI(3):2, VI(3):3, VI(3):4, VI(3):5, VI(3):6, VI(3):7, VI(3):8, VI(3):9, VI(3):10, VI(3):11, VI(3):12, VI(3):13, VI(3):14, VI(3):15, VI(3):16, VI(3):17, VI(3):18, VI(3):19, VI(3):20, VI(3):21, VI(3):22, VI(3):23, VI(3):24, VI(3):25, VI(3):26, VI(3):27, VI(3):28, VI(3):29, VI(3):30, VI(3):31, VI(3):32, VI(3):33, VI(3):34, VI(3):35, VI(3):36, VI(3):37, VI(3):38, VI(3):39, VI(3):40, VI(3):41, VI(3):42, VI(3):43, VI(3):44, VI(3):45, VI(3):46, VI(3):47, VI(3):48, VI(3):49, VI(3):50, VI(3):51, VI(3):52, VI(3):53, VI(3):54, VI(3):55, VI(3):56, VI(3):57, VI(3):58, VI(3):59, VI(3):60, VI(3):61, VI(3):62, VI(3):63 adenoma, VI(3):52, VI(3):53 differential diagnosis, VI(3):53 middle ear schwannoma vs., VI(3):51 cholesterol granuloma See Cholesterol granuloma, middle ear congenital cholesteatoma See Cholesteatoma, congenital, middle ear differential diagnosis, VI(1):4 Diagnostic Imaging Head and Neck encephalocele, middle ear cholesterol granuloma vs., VI(3):39 foreign body, ossicular prosthesis vs., VI(3):62 glomus tympanicum paraganglioma See Glomus tympanicum paraganglioma imaging anatomy, VI(1):2, VI(1):3 internal carotid artery aberrant See Carotid artery, aberrant internal lateralized, VI(3):10, VI(3):11 aberrant internal carotid artery vs., VI(3):13 differential diagnosis, VI(3):11 ossicular fixation See Ossicular fixation ossicular prosthesis See Ossicular prosthesis otomastoiditis See Otomastoiditis oval window atresia, VI(3):8, VI(3):9 differential diagnosis, VI(3):9 middle ear prolapsing facial nerve vs., VI(6):5 pars flaccida cholesteatoma See Pars flaccida cholesteatoma pars tensa cholesteatoma See Pars tensa cholesteatoma persistent stapedial artery, VI(3):16, VI(3):17 aberrant internal carotid artery associated with, VI(3):14 differential diagnosis, VI(3):17 middle ear prolapsing facial nerve vs., VI(6):5 schwannoma, VI(3):50, VI(3):51 differential diagnosis, VI(3):51 middle ear adenoma vs., VI(3):53 temporal bone cephalocele, VI(3):58, VI(3):59 temporal bone meningioma, VI(3):46, VI(3):47, VI(3):48, VI(3):49 differential diagnosis, VI(3):47, VI(3):48 fibrous dysplasia vs., VI(7):6, VI(7):7 temporal bone rhabdomyosarcoma, VI(3):54, VI(3):55, VI(3):56, VI(3):57 acute otomastoiditis with abscess vs., VI(3):19 coalescent otomastoiditis vs., VI(3):23 differential diagnosis, VI(3):55, VI(3):56 staging, grading, & classification, VI(3):56 Midfacial fracture, complex naso-orbital-ethmoidal fracture vs., V(2):25 zygomaticomaxillary complex fracture vs., V(2):23 Midline facial clefts, skull base cephalocele associated with, V(1):55 Minor salivary gland malignancy buccal mucosa SCCa vs., II(2):26 hard palate SCCa vs., II(2):27 hypopharyngeal, pyriform sinus squamous cell carcinoma vs., II(2):29 lingual tonsil, lingual tonsil SCC vs., II(2):7 nasopharyngeal, nasopharyngeal carcinoma vs., II(2):3 oral cavity, I(14):40, I(14):41 differential diagnosis, I(14):41 staging, grading, & classification, I(14):41 palatal, palate benign mixed tumor vs., I(14):35 pharyngeal mucosal space, I(3):16, I(3):17 benign mixed tumor of pharyngeal mucosal space vs., I(3):15 differential diagnosis, I(3):17 Non-Hodgkin lymphoma vs., I(3):19 staging, grading, & classification, I(3):17 retromolar trigone SCCa vs., II(2):25 Monosuperoincisivodontic dwarfism See Solitary median maxillary central incisor Motor denervation CNV3, masticator space, I(4):10, I(4):11, I(4):12, I(4):13 cranial nerve 11 (accessory nerve), nodal neck dissection vs., II(3):3 hypoglossal nerve, I(14):8, I(14):9 MRA motion artifact, carotid artery fibromuscular dysplasia vs., I(6):15 P.xxix Mucocele laryngeal See Laryngocele nasolacrimal duct See Nasolacrimal duct mucocele petrous apex, VI(5):12, VI(5):13 asymmetric marrow vs., VI(5):3 cephalocele vs., VI(5):5 cholesterol granuloma vs., VI(5):15 congenital cholesteatoma vs., VI(5):7 differential diagnosis, VI(5):13 sinonasal, IV(1):56, IV(1):57, IV(1):58, IV(1):59 allergic fungal sinusitis vs., IV(1):41 clinical issues, IV(1):58 differential diagnosis, IV(1):57 imaging, IV(1):57, IV(1):59 mycetoma vs., IV(1):43 nerve sheath tumor vs., IV(1):88 orbital subperiosteal abscess vs., IV(2):35 pathology, IV(1):57, IV(1):58 staging, grading, & classification, IV(1):58 submandibular gland accessory salivary tissue vs., I(14):11 benign mixed tumor vs., I(14):33 ranula vs., I(14):21 submandibular gland carcinoma vs., I(14):39 Mucoepidermoid carcinoma, parotid space See Parotid carcinoma, mucoepidermoid Mucopolysaccharidosis, III(2):24, III(2):25 differential diagnosis, III(2):25 1684 staging, grading, & classification, III(2):25 Multinodular goiter See Goiter, multinodular Multiple endocrine syndromes See MEN syndromes Multiple myeloma, skull base, V(1):86, V(1):87 differential diagnosis, V(1):87 metastases vs., V(1):89 plasmacytoma vs., V(1):83 staging, grading, & classification, V(1):87 Multi-spatial lesions See Trans-spatial and multi-spatial lesions Mural cholesteatoma, VI(3):36, VI(3):37 Muscular torticollis, congenital See Fibromatosis colli Mycetoma, IV(1):42, IV(1):43 Mycobacterium lymph nodes, nontuberculous, I(12):16 1st branchial cleft cyst vs., III(1):25 differential diagnosis, I(12):16 metastatic neuroblastoma vs., III(1):55 suppurative lymph nodes vs., I(12):11 tuberculous lymph nodes vs., I(12):15 Myelomatosis, diffuse See Multiple myeloma, skull base Myocutaneous neuroma, glomus jugulare paraganglioma associated with, V(1):32 Myopia, axial, coloboma vs., IV(2):6 Myositis, related to neck infection, fibromatosis colli vs., III(1):45 Myxoma (myxofibroma), odontogenic, ameloblastoma vs., I(15):31, I(15):32 N Nager syndrome, Treacher Collins syndrome vs., III(2):19 Nance deafness See X-linked stapes gusher (DFNX2) Nasal bone fracture, naso-orbitalethmoidal fracture vs., V(2):25 Nasal cocaine necrosis, IV(1):66, IV(1):67 differential diagnosis, IV(1):67 staging, grading, & classification, IV(1):67 Wegener granulomatosis vs., IV(1):63 Nasal dermal sinus, IV(1):18, IV(1):19, IV(1):20, IV(1):21 clinical issues, IV(1):20 differential diagnosis, IV(1):19 frontoethmoidal cephalocele vs., IV(1):23 imaging, IV(1):19, IV(1):21 nasal glioma vs., IV(1):15 pathology, IV(1):19, IV(1):20 skull base cephalocele vs., V(1):55 Nasal foreign body, choanal atresia vs., IV(1):11 Nasal glioma, IV(1):14, IV(1):15, IV(1):16, IV(1):17 clinical issues, IV(1):16 Diagnostic Imaging Head and Neck differential diagnosis, IV(1):15 frontoethmoidal cephalocele vs., IV(1):23 imaging, IV(1):q5, IV(1):17 nasal dermal sinus vs., IV(1):19 pathology, IV(1):16 pediatric dermoid/epidermoid cyst vs., III(1):42 skull base cephalocele vs., V(1):55 solitary sinonasal polyp vs., IV(1):53 Nasal pyriform aperture stenosis, congenital, IV(1):26, IV(1):27 choanal atresia vs., IV(1):11 differential diagnosis, IV(1):27 solitary median maxillary central incisor vs., I(15):9 Nasal septal perforation, traumatic, nasal cocaine necrosis vs., IV(1):67 Nasolabial cyst, I(15):10, I(15):11 Nasolacrimal duct mucocele, IV(1):8, IV(1):9 choanal atresia vs., IV(1):11 congenital nasal pyriform aperture stenosis vs., IV(1):27 differential diagnosis, IV(1):8, IV(1):9 frontoethmoidal cephalocele vs., IV(1):23 nasolabial cyst vs., I(15):11 orbital subperiosteal abscess vs., IV(2):35 skull base cephalocele vs., V(1):55 Naso-orbital-ethmoidal fracture, V(2):25 complex facial fracture vs., V(2):24 differential diagnosis, V(2):25 P.xxx orbital blowout fracture vs., V(2):17 overview, V(2):3 trans-facial (Le Fort) fracture vs., V(2):19 Nasopalatine duct cyst, I(15):18, I(15):19 benign mixed tumor of pharyngeal mucosal space vs., I(3):15 differential diagnosis, I(15):19 minor salivary gland malignancy vs., I(14):41 nasolabial cyst vs., I(15):11 palate benign mixed tumor vs., I(14):35 Nasopharyngeal angiofibroma See Juvenile angiofibroma Nasopharyngeal bursa See Tornwaldt cyst Nasopharyngeal carcinoma, II(2):2, II(2):3, II(2):4, II(2):5 AJCC staging, II(1):4, II(2):4 clinical issues, II(2):4 differential diagnosis, II(2):3 extraosseous chordoma vs., I(13):17 imaging, II(2):3, II(2):5 Non-Hodgkin lymphoma vs., I(3):19 pathology, II(2):3, II(2):4 posterior oropharyngeal wall SCCa vs., II(2):14 skull base chondrosarcoma vs., V(1):91 skull base idiopathic inflammatory pseudotumor vs., V(1):73 staging, grading, & classification, II(2):4 Tornwaldt cyst vs., I(3):7 Neck cysts, congenital, lymphocele of neck vs., I(13):29 Necrobacillosis See Post-pharyngitis venous thrombosis (Lemierre) Necrotizing external otitis See External otitis, necrotizing Neo-osteogenesis, fibrous dysplasia vs., IV(1):69 Nerve sheath tumor, sinonasal, IV(1):88 differential diagnosis, IV(1):88 sinonasal benign mixed tumor vs., IV(1):89 Neurenteric cyst arachnoid cyst of CPA vs., VI(8):11 congenital CPA-IAC lipoma vs., VI(8):15 epidermoid cyst vs., VI(8):7 Neurilemmoma See Schwannoma Neurinoma See CNV3 schwannoma, masticator space Neuroblastoma metastatic, III(1):55 differential diagnosis, III(1):55 orbital infantile hemangioma vs., IV(2):57 primary cervical neuroblastoma vs., III(1):54 olfactory See Esthesioneuroblastoma primary cervical, III(1):54 differential diagnosis, III(1):54 fibromatosis colli vs., III(1):45 Neurocutaneous melanosis, CPA-IAC superficial siderosis vs., VI(8):47 Neurocysticercosis, CPA, epidermoid cyst vs., VI(8):7 Neurofibroma brachial plexus schwannoma in perivertebral space vs., I(8):17 carotid space, I(6):38, I(6):39 carotid body paraganglioma vs., I(6):25 carotid space schwannoma vs., I(6):33 differential diagnosis, I(6):39 glomus vagale paraganglioma vs., I(6):29 staging, grading, & classification, I(6):39 sympathetic schwannoma vs., I(6):37 cervical spine, plexiform neurofibroma of head and neck associated with, I(13):13 localized, III(2):4 lymphatic malformation vs., III(1):7 malignant peripheral nerve sheath tumor vs., I(13):27 orbital cavernous hemangioma vs., IV(2):29 perineural tumor spread vs., II(2):43 plexiform, I(13):12, I(13):13 differential diagnosis, I(13):13 infantile hemangioma vs., III(1):48 orbital infantile hemangioma vs., IV(2):57 1685 orbital lymphatic malformation vs., IV(2):23 orbital neurofibromatosis type vs., IV(2):19 pathology, I(13):13, III(2):4 staging, grading, & classification, I(13):13 primary cervical neuroblastoma vs., III(1):54 Neurofibromatosis type 1, III(2):2, III(2):3, III(2):4, III(2):5 clinical issues, III(2):4 differential diagnosis, III(2):3 imaging, III(2):3, III(2):5 orbital, IV(2):18, IV(2):19, IV(2):20, IV(2):21 clinical issues, IV(2):20 coloboma vs., IV(2):6 differential diagnosis, IV(2):19 imaging, IV(2):19, IV(2):21 pathology, IV(2):19, IV(2):20 staging, grading, & classification, IV(2):20 pathology, III(2):3, III(2):4 pediatric rhabdomyosarcoma associated with, III(1):52 plexiform neurofibroma associated with, I(13):13 staging, grading, & classification, III(2):4 Neurofibromatosis type 2, III(2):6, III(2):7 carotid space schwannoma associated with, I(6):34 CPA-IAC facial nerve schwannoma associated with, VI(8):35 differential diagnosis, III(2):7 jugular foramen schwannoma associated with, V(1):36 masticator space CNV3 schwannoma associated with, I(4):19 optic nerve sheath meningioma associated with, IV(2):66 posterior cervical space schwannoma associated with, I(9):6 P.xxxi sympathetic schwannoma associated with, I(6):37 Neurogenic tumor, parapharyngeal space, benign mixed tumor of parapharyngeal space vs., I(2):5 Neuroma See Schwannoma Neuropore anomaly, anterior See Nasal dermal sinus Neurosarcoid, skull base idiopathic inflammatory pseudotumor vs., V(1):73 meningioma vs., V(1):79 Nevoid basal cell syndrome See Basal cell nevus syndrome Nodal hyperplasia See Lymph nodes, reactive Nodal neck dissection, II(3):2, II(3):3 differential diagnosis, II(3):2, II(3):3 Diagnostic Imaging Head and Neck staging, grading, & classification, II(3):2, II(3):3 Nodal non-Hodgkin lymphoma in neck See Non-Hodgkin lymphoma, nodal, in neck Nonchromaffin paraganglioma See Carotid body paraganglioma; Glomus vagale paraganglioma Non-Hodgkin lymphoma extralymphatic, differential diagnosis, I(13):19 fibromatosis vs., I(13):33 head and neck, I(13):18, I(13):19, I(13):20, I(13):21 clinical issues, I(13):20 differential diagnosis, I(13):19 imaging, I(13):19, I(13):21 pathology, I(13):19, I(13):20 staging, grading, & classification, I(13):19, I(13):20 lingual tonsil lingual thyroid vs., I(14):19 lingual tonsil SCC vs., II(2):7 meningeal, skull base idiopathic inflammatory pseudotumor vs., V(1):73 metastatic neuroblastoma vs., III(1):55 nasopharyngeal, nasopharyngeal carcinoma vs., II(2):3 nodal differential diagnosis, I(13):19 HPV-related oropharyngeal SCCa vs., II(2):15 nodal SCCa vs., II(2):47 spinal accessory node SCCa vs., I(9):9 nodal, in neck, I(12):28, I(12):29, I(12):30, I(12):31 clinical issues, I(12):30 differential diagnosis, I(12):29 giant lymph node hyperplasia vs., I(12):19 histiocytic necrotizing lymphadenitis (Kikuchi) vs., I(12):23 imaging, I(12):29, I(12):31 Kimura disease vs., I(12):25 nodal differentiated thyroid carcinoma vs., I(12):37 nodal Hodgkin lymphoma in neck vs., I(12):33 reactive lymph nodes vs., I(12):7 sarcoidosis lymph nodes vs., I(12):17 staging, grading, & classification, I(12):29, I(12):30 systemic nodal metastases in neck vs., I(12):39 nodal, retropharyngeal space, I(7):20, I(7):21 differential diagnosis, I(7):21 staging, grading, & classification, I(7):21 nodal, submandibular space, I(14):42, I(14):43 differential diagnosis, I(14):43 nodal squamous cell carcinoma vs., I(14):45 non-nodal lymphatic, differential diagnosis, I(13):19 orbital infantile hemangioma vs., IV(2):57 parotid, I(5):36, I(5):37, I(5):38, I(5):39 benign lymphoepithelial lesions-HIV vs., I(5):15 benign mixed tumor of parotid space vs., I(5):19, I(5):20 clinical issues, I(5):38 differential diagnosis, I(5):37 forms of, I(5):37 imaging, I(5):37, I(5):39 parotid mucoepidermoid carcinoma vs., I(5):29 parotid nodal metastatic disease vs., I(5):41 parotid Sjögren syndrome vs., I(5):12 staging, grading, & classification, I(5):38 Warthin tumor vs., I(5):23 pharyngeal mucosal space, I(3):18, I(3):19, I(3):20, I(3):21 benign mixed tumor of pharyngeal mucosal space vs., I(3):15 differential diagnosis, I(3):19 extraosseous chordoma vs., I(13):17 imaging, I(3):19, I(3):21 minor salivary gland malignancy vs., I(3):17 staging, grading, & classification, I(3):20 tonsillar inflammation vs., I(3):11 primary cervical neuroblastoma vs., III(1):54 sinonasal, IV(1):102, IV(1):103, IV(1):104, IV(1):105 adenocarcinoma vs., IV(1):99 allergic fungal sinusitis vs., IV(1):41 clinical issues, IV(1):104 differential diagnosis, IV(1):103 esthesioneuroblastoma vs., IV(1):95 imaging, IV(1):103, IV(1):105 invasive fungal sinusitis vs., IV(1):45 melanoma vs., IV(1):101 nasal cocaine necrosis vs., IV(1):67 pathology, IV(1):103, IV(1):104 squamous cell carcinoma vs., IV(1):91 staging, grading, & classification, IV(1):104 undifferentiated carcinoma vs., IV(1):106 Wegener granulomatosis vs., IV(1):63 sinus histiocytosis vs., I(13):31 skull base metastasis vs., V(1):89 skull base multiple myeloma vs., V(1):87 spinal accessory node, I(9):10, I(9):11 P.xxxii differential diagnosis, I(9):11 posterior cervical space schwannoma vs., I(9):5 staging, grading, & classification, I(9):11 thyroid, I(10):32, I(10):33 anaplastic thyroid carcinoma vs., I(10):29 cervical esophageal carcinoma vs., I(10):37 1686 chronic lymphocytic thyroiditis vs., I(10):7 differential diagnosis, I(10):33 differentiated thyroid carcinoma vs., I(10):21 medullary thyroid carcinoma vs., I(10):25 multinodular goiter vs., I(10):10 staging, grading, & classification, I(10):33 trigeminal schwannoma of central skull base vs., V(1):19 Nonkeratizing carcinoma See Sinonasal squamous cell carcinoma Non-tuberculous mycobacterium nodes See Mycobacterium lymph nodes, non-tuberculous Noonan syndrome keratocystic odontogenic tumor associated with, I(15):35 pediatric rhabdomyosarcoma associated with, III(1):52 Norrie disease, Coats disease associated with, IV(2):13 Nose See Nasal entries; Sinonasal cavities Nutrient canal, mandible fracture vs., V(2):27 O Obesity, temporal bone cephalocele associated with, VI(3):59 “Occult” cephalocele See Skull base, cephalocele Ocular adnexal lymphoma See Lymphoproliferative lesions, orbital Ocular melanocytosis, ocular melanoma associated with, IV(2):76 Ocular melanoma, IV(2):74, IV(2):75, IV(2):76, IV(2):77 clinical issues, IV(2):76 differential diagnosis, IV(2):75 imaging, IV(2):75, IV(2):77 pathology, IV(2):75, IV(2):76 staging, grading, & classification, IV(2):76 Ocular toxocariasis, IV(2):32, IV(2):33 Coats disease vs., IV(2):13 differential diagnosis, IV(2):33 retinoblastoma vs., IV(2):71 Oculoauriculovertebral spectrum See Hemifacial microsomia Odontogenic keratocyst See Keratocystic odontogenic tumor Odontogenic myxoma (myxofibroma), ameloblastoma vs., I(15):31, I(15):32 Odontoma, masticator space chondrosarcoma vs., I(4):25 Olfactory neuroblastoma See Esthesioneuroblastoma Ollier disease, skull base osteosarcoma associated with, V(1):95 Ophthalmopathy, thyroid See Thyroid ophthalmopathy Diagnostic Imaging Head and Neck Optic nerve glioma See Optic pathway glioma Optic nerve sheath ectasia, orbital neurofibromatosis type vs., IV(2):19 Optic nerve sheath meningioma, IV(2):64, IV(2):65, IV(2):66, IV(2):67 clinical issues, IV(2):66 differential diagnosis, IV(2):65 imaging, IV(2):65, IV(2):67 optic neuritis vs., IV(2):51 optic pathway glioma vs., IV(2):61 orbital cavernous hemangioma vs., IV(2):29 pathology, IV(2):66 staging, grading, & classification, IV(2):66 Optic neuritis, IV(2):50, IV(2):51, IV(2):52, IV(2):53 clinical issues, IV(2):52 differential diagnosis, IV(2):51 imaging, IV(2):51, IV(2):53 infectious, IV(2):51 optic nerve sheath meningioma vs., IV(2):65 optic pathway glioma vs., IV(2):61 pathology, IV(2):51, IV(2):52 staging, grading, & classification, IV(2):51 Optic neuropathy granulomatous (sarcoid), optic neuritis vs., IV(2):51 ischemic, optic neuritis vs., IV(2):51 radiation-induced, optic neuritis vs., IV(2):51 toxic, optic neuritis vs., IV(2):51 Optic pathway glioma, IV(2):60, IV(2):61, IV(2):62, IV(2):63 clinical issues, IV(2):62 differential diagnosis, IV(2):61 imaging, IV(2):61, IV(2):63 optic nerve sheath meningioma vs., IV(2):65 optic neuritis vs., IV(2):51 orbital cavernous hemangioma vs., IV(2):29 orbital neurofibromatosis type vs., IV(2):19 pathology, IV(2):61, IV(2):62 plexiform neurofibroma of head and neck associated with, I(13):13 staging, grading, & classification, IV(2):61, IV(2):62 Optic pit, congenital, coloboma associated with, IV(2):8 Oral cavity, I(14):2, I(14):3, I(14):4, I(14):5, I(14):6, I(14):7, I(14):8, I(14):9, I(14):10, I(14):11, I(14):12, I(14):13, I(14):14, I(14):15, I(14):16, I(14):17, I(14):18, I(14):19, I(14):20, I(14):21, I(14):22, I(14):23, I(14):24, I(14):25, I(14):26, I(14):27, I(14):28, I(14):29, I(14):30, I(14):31, I(14):32, I(14):33, I(14):34, I(14):35, I(14):36, I(14):37, I(14):38, I(14):39, I(14):40, I(14):41, I(14):42, I(14):43, I(14):44, I(14):45 abscess, I(14):28, I(14):29, I(14):30, I(14):31 accessory salivary tissue vs., I(14):11 clinical issues, I(14):30 dermoid and epidermoid vs., I(14):13 differential diagnosis, I(14):29, I(14):30 imaging, I(14):29, I(14):31 lymphatic malformation vs., I(14):17 pathology, I(14):30 ranula vs., I(14):21 sialocele vs., I(14):25 P.xxxiii sublingual gland carcinoma vs., I(14):37 thyroglossal duct cyst vs., III(1):17 tongue SCCa vs., II(2):17 alveolar ridge squamous cell carcinoma, II(2):22, II(2):23 differential diagnosis, II(2):23 osteoradionecrosis of mandible-maxilla vs., I(15):41 staging, grading, & classification, II(2):23 buccal mucosa squamous cell carcinoma, II(2):26 differential diagnosis, II(2):26 retromolar trigone SCCa vs., II(2):25 dermoid and epidermoid See Dermoid/epidermoid cyst, oral cavity differential diagnosis, I(14):3 floor of mouth squamous cell carcinoma, II(2):20, II(2):21 differential diagnosis, II(2):21 staging, grading, & classification, II(2):21 sublingual gland carcinoma vs., I(14):37 hard palate squamous cell carcinoma, II(2):27 differential diagnosis, II(2):27 palate benign mixed tumor vs., I(14):35 HPV-related oropharyngeal squamous cell carcinoma, II(2):15 hypoglossal nerve motor denervation, I(14):8, I(14):9 images, I(14):4, I(14):5, I(14):6, I(14):7 imaging anatomy, I(14):2, I(14):3 approaches to imaging issues, I(14):3 techniques and indications, I(14):2 infection, buccal mucosa SCCa vs., II(2):26 lingual thyroid, I(14):18, I(14):19 congenital vallecular cyst vs., III(1):15 differential diagnosis, I(14):18, I(14):19 thyroglossal duct cyst vs., III(1):17 lingual tonsil squamous cell carcinoma See Lingual tonsil squamous cell carcinoma lymphatic malformation See Lymphatic malformation, oral cavity minor salivary gland malignancy, I(14):40, I(14):41 differential diagnosis, I(14):41 staging, grading, & classification, I(14):41 1687 overview, I(14):2, I(14):3, I(14):4, I(14):5, I(14):6, I(14):7 palate benign mixed tumor, I(14):34, I(14):35 differential diagnosis, I(14):35 hard palate SCCa vs., II(2):27 minor salivary gland malignancy vs., I(14):41 palatine tonsil squamous cell carcinoma See Palatine tonsil squamous cell carcinoma ranula See Ranula retromolar trigone squamous cell carcinoma, II(2):24, II(2):25 sialocele, I(14):24, I(14):25 differential diagnosis, I(14):25 ranula vs., I(14):21 submandibular duct, abscess vs., I(14):30 sublingual gland carcinoma, I(14):36, I(14):37 submandibular gland See Submandibular gland submandibular space See Submandibular space tongue See Tongue, oral Orbit, IV(2):2, IV(2):3, IV(2):4, IV(2):5, IV(2):6, IV(2):7, IV(2):8, IV(2):9, IV(2):10, IV(2):11, IV(2):12, IV(2):13, IV(2):14, IV(2):15, IV(2):16, IV(2):17, IV(2):18, IV(2):19, IV(2):20, IV(2):21, IV(2):22, IV(2):23, IV(2):24, IV(2):25, IV(2):26, IV(2):27, IV(2):28, IV(2):29, IV(2):30, IV(2):31, IV(2):32, IV(2):33, IV(2):34, IV(2):35, IV(2):36, IV(2):37, IV(2):38, IV(2):39, IV(2):40, IV(2):41, IV(2):42, IV(2):43, IV(2):44, IV(2):45, IV(2):46, IV(2):47, IV(2):48, IV(2):49, IV(2):50, IV(2):51, IV(2):52, IV(2):53, IV(2):54, IV(2):55, IV(2):56, IV(2):57, IV(2):58, IV(2):59, IV(2):60, IV(2):61, IV(2):62, IV(2):63, IV(2):64, IV(2):65, IV(2):66, IV(2):67, IV(2):68, IV(2):69, IV(2):70, IV(2):71, IV(2):72, IV(2):73, IV(2):74, IV(2):75, IV(2):76, IV(2):77, IV(2):78, IV(2):79, IV(2):80, IV(2):81, IV(2):82, IV(2):83 blowout fracture, V(2):16, V(2):17 differential diagnosis, V(2):17 inferior, zygomaticomaxillary complex fracture vs., V(2):23 medial, naso-orbital-ethmoidal fracture vs., V(2):25 cavernous hemangioma See Cavernous hemangioma, orbital cellulitis See Cellulitis, orbital Coats disease, IV(2):12, IV(2):13 differential diagnosis, IV(2):13 ocular toxocariasis vs., IV(2):33 persistent hyperplastic primary vitreous vs., IV(2):11 retinoblastoma vs., IV(2):71 coloboma, IV(2):6, IV(2):7, IV(2):8, IV(2):9 decompression surgery, blowout fracture vs., V(2):17 Diagnostic Imaging Head and Neck dermoid/epidermoid See Dermoid/epidermoid cyst, orbital differential diagnosis, IV(2):3 foreign body, V(2):14, V(2):15 differential diagnosis, V(2):15 staging, grading, & classification, V(2):15 idiopathic inflammatory pseudotumor See Pseudotumor, idiopathic inflammatory, orbital images, IV(2):4, IV(2):5 imaging anatomy, IV(2):2, IV(2):3 anatomy-based imaging issues, IV(2):3 approach and indications, IV(2):2 protocols, IV(2):3 infantile hemangioma See Hemangioma, infantile, orbital lacrimal gland benign mixed tumor, IV(2):68, IV(2):69 differential diagnosis, IV(2):69 lacrimal gland carcinoma vs., IV(2):83 orbital lymphoproliferative lesions vs., IV(2):79 staging, grading, & classification, IV(2):69 lacrimal gland carcinoma, IV(2):82, IV(2):83 differential diagnosis, IV(2):83 lacrimal gland benign mixed tumor vs., IV(2):69 staging, grading, & classification, IV(2):83 Langerhans cell histiocytosis, IV(2):54, IV(2):55 differential diagnosis, IV(2):55 infantile hemangioma vs., IV(2):57 pediatric dermoid/epidermoid cyst vs., III(1):41 P.xxxiv staging, grading, & classification, IV(2):55 leukemia infantile hemangioma vs., IV(2):57 Langerhans cell histiocytosis vs., IV(2):55 lymphatic malformation See Lymphatic malformation, orbital lymphoproliferative lesions See Lymphoproliferative lesions, orbital metastases cavernous hemangioma vs., IV(2):29 Langerhans cell histiocytosis vs., IV(2):55 lymphoproliferative lesions vs., IV(2):79 optic nerve sheath meningioma vs., IV(2):65 thyroid ophthalmopathy vs., IV(2):47 neurofibromatosis type 1, IV(2):18, IV(2):19, IV(2):20, IV(2):21 coloboma vs., IV(2):6 differential diagnosis, IV(2):19 staging, grading, & classification, IV(2):20 ocular melanoma, IV(2):74, IV(2):75, IV(2):76, IV(2):77 differential diagnosis, IV(2):75 staging, grading, & classification, IV(2):76 ocular toxocariasis, IV(2):32, IV(2):33 Coats disease vs., IV(2):13 differential diagnosis, IV(2):33 retinoblastoma vs., IV(2):71 optic neuritis See Optic neuritis optic pathway glioma See Optic pathway glioma overview, IV(2):2, IV(2):3, IV(2):4, IV(2):5 pathologic issues: vascular malformations, IV(2):3 persistent hyperplastic primary vitreous See Vitreous, persistent hyperplastic primary retinoblastoma See Retinoblastoma rhabdomyosarcoma dermoid/epidermoid cyst vs., IV(2):15 infantile hemangioma vs., IV(2):57 Langerhans cell histiocytosis vs., IV(2):55 lymphatic malformation vs., IV(2):23 pediatric dermoid/epidermoid cyst vs., III(1):41 sarcoidosis See Sarcoidosis, orbital Sjögren syndrome lacrimal gland carcinoma vs., IV(2):83 lymphoproliferative lesions associated with, IV(2):79 lymphoproliferative lesions vs., IV(2):79 subperiosteal abscess, IV(2):34, IV(2):35, IV(2):36, IV(2):37 cellulitis vs., IV(2):39 differential diagnosis, IV(2):35 imaging, IV(2):35, IV(2):37 staging, grading, & classification, IV(2):36 surgical device, foreign body vs., V(2):15 thyroid ophthalmopathy See Thyroid ophthalmopathy trauma coloboma vs., IV(2):6 overview, V(2):2 venous malformation infantile hemangioma vs., IV(2):57 pediatric dermoid/epidermoid cyst vs., III(1):42 venous varix, IV(2):26, IV(2):27 cavernous hemangioma vs., IV(2):29 differential diagnosis, IV(2):27 and dural AV fistula, CPA-IAC aneurysm vs., VI(8):45 lymphatic malformation vs., IV(2):23 Oropharyngeal carcinoma HPV-related, II(2):15 lingual tonsil See Lingual tonsil squamous cell carcinoma palatine tonsil See Palatine tonsil squamous cell carcinoma posterior oropharyngeal wall, II(2):14 1688 Ossicular dislocation, post-traumatic, chronic otomastoiditis with ossicular erosions vs., VI(3):25 Ossicular erosion in chronic otitis media, chronic otomastoiditis with tympanosclerosis vs., VI(3):27 otomastoiditis, chronic, with ossicular erosions, VI(3):24, VI(3):25 Ossicular fixation congenital, VI(3):7 in chronic otitis media, chronic otomastoiditis with tympanosclerosis vs., VI(3):27 postinflammatory See Otomastoiditis, chronic, with tympanosclerosis post-traumatic, congenital ossicular fixation vs., VI(3):7 Ossicular loss, postoperative, chronic otomastoiditis with ossicular erosions vs., VI(3):25 Ossicular prosthesis, VI(3):60, VI(3):61, VI(3):62, VI(3):63 clinical issues, VI(3):62 congenital ossicular fixation vs., VI(3):7 differential diagnosis, VI(3):62 imaging, VI(3):61, VI(3):62, VI(3):63 incus interposition graft, VI(3):61 partial ossicular replacement prosthesis (PORP), VI(3):61 pathology, VI(3):62 stapes prosthesis, VI(3):61 total ossicular replacement prosthesis (TORP), VI(3):61 Ossifying fibroma See Fibroma, ossifying Ossifying labyrinthitis See Labyrinthine ossificans Osteitis deformans See Paget disease, temporal bone Osteitis fibrosa See Fibrous dysplasia, skull base Osteoblastoma, sinonasal fibrous dysplasia vs., IV(1):69 Osteochondritis dissecans, synovial chondromatosis of TMJ vs., I(15):27 P.xxxv Osteochondroma skull base osteosarcoma associated with, V(1):95 synovial chondromatosis of TMJ vs., I(15):27 Osteoclastoma See Giant cell tumor, skull base Osteodystrophy fibrosa See Fibrous dysplasia, skull base Osteogenesis imperfecta carotid artery dissection in neck associated with, I(6):10 skull base Paget disease vs., V(1):65 temporal bone cochlear cleft vs., VI(4):5 otosclerosis vs., VI(4):41 otosyphilis vs., VI(4):35 Diagnostic Imaging Head and Neck Osteogenic sarcoma See Osteosarcoma Osteoma choroidal, ocular melanoma vs., IV(2):75 external auditory canal, VI(2):16, VI(2):17 congenital external ear dysplasia vs., VI(2):3 differential diagnosis, VI(2):17 exostoses vs., VI(2):19 sinonasal, IV(1):70, IV(1):71, IV(1):72, IV(1):73 clinical issues, IV(1):72 differential diagnosis, IV(1):71 fibrous dysplasia vs., IV(1):69 imaging, IV(1):71, IV(1):73 ossifying fibroma vs., IV(1):75 osteosarcoma vs., IV(1):109 staging, grading, & classification, IV(1):72 Osteomyelitis Garré sclerosing, McCune-Albright syndrome vs., III(2):22 mandible-maxilla, I(15):22, I(15):23 alveolar ridge SCCa vs., II(2):23 differential diagnosis, I(15):23 masticator space sarcoma vs., I(4):29 osteoradionecrosis vs., I(15):41 osteosarcoma vs., I(15):39 primary chronic, mandible-maxilla osteomyelitis vs., I(15):23 Osteonecrosis, mandible-maxilla, I(15):42, I(15):43 alveolar ridge SCCa vs., II(2):23 differential diagnosis, I(15):43 osteomyelitis vs., I(15):23 osteoradionecrosis vs., I(15):41 Osteopetrosis, skull base, V(1):70, V(1):71 differential diagnosis, V(1):71 Paget disease vs., V(1):65 Osteoradionecrosis mandible-maxilla, I(15):40, I(15):41 alveolar ridge SCCa vs., II(2):23 differential diagnosis, I(15):41 masticator space abscess vs., I(4):15 osteomyelitis vs., I(15):23 osteonecrosis vs., I(15):43 osteosarcoma of mandible-maxilla vs., I(15):39 temporal bone, VI(7):14, VI(7):15 differential diagnosis, VI(7):15 otosclerosis vs., VI(4):41 Paget disease vs., VI(7):9 Osteosarcoma mandible-maxilla, I(15):38, I(15):39 alveolar ridge SCCa vs., II(2):23 differential diagnosis, I(15):39 masticator space chondrosarcoma vs., I(4):25 sinonasal, IV(1):109 chondrosarcoma vs., IV(1):108 differential diagnosis, IV(1):109 fibrous dysplasia vs., IV(1):69 ossifying fibroma vs., IV(1):75 skull base, V(1):94, V(1):95 Otitis idiopathic inflammatory medial meatal fibrotizing See External auditory canal, medial canal fibrosis malignant external See External otitis, necrotizing Otitis media acute, coalescent otomastoiditis vs., VI(3):23 chronic chronic otomastoiditis with tympanosclerosis vs., VI(3):27 with focal calcification or ossification See Otomastoiditis, chronic, with tympanosclerosis with hemorrhage, middle ear cholesterol granuloma vs., VI(3):39 with tympanosclerosis ossicular prosthesis vs., VI(3):62 otosclerosis vs., VI(4):41 recurrent, middle ear cholesterol granuloma associated with, VI(3):40 Otofaciocervical syndrome, branchiootorenal syndrome vs., III(2):15 Otomastoiditis acute, uncomplicated, coalescent otomastoiditis vs., VI(3):23 acute coalescent, VI(3):22, VI(3):23 differential diagnosis, VI(3):23 mural cholesteatoma vs., VI(3):37 skull base Langerhans cell histiocytosis vs., V(1):67 temporal bone Langerhans cell histiocytosis vs., VI(7):11 temporal bone osteoradionecrosis vs., VI(7):15 acute coalescent, with abscess, VI(3):18, VI(3):19, VI(3):20, VI(3):21, VI(3):22 clinical issues, VI(3):20 differential diagnosis, VI(3):19 imaging, VI(3):19, VI(3):21 pathology, VI(3):20 temporal bone rhabdomyosarcoma vs., VI(3):55, VI(3):56 P.xxxvi chronic with ossicular erosions, VI(3):24, VI(3):25 with tympanosclerosis, VI(3):26, VI(3):27 Otorhinorrhea See Temporal bone, cerebrospinal fluid leak Otorrhea, temporal bone CSF leak vs., VI(7):3 Otosclerosis, VI(4):40, VI(4):41, VI(4):42, VI(4):43 clinical issues, VI(4):42 cochlear cochlear cleft vs., VI(4):5 labyrinthine ossificans vs., VI(4):37 otosyphilis vs., VI(4):35 1689 differential diagnosis, VI(4):41 fenestral chronic otomastoiditis with tympanosclerosis vs., VI(3):27 cochlear cleft vs., VI(4):5 oval window atresia vs., VI(3):9 imaging, VI(4):41, VI(4):43 pathology, VI(4):41, VI(4):42 staging, grading, & classification, VI(4):42 temporal bone Paget disease vs., VI(7):9 Otospongiosis See Otosclerosis Otosyphilis, VI(4):34, VI(4):35 differential diagnosis, VI(4):35 temporal bone osteoradionecrosis vs., VI(7):15 Oval window atresia, VI(3):8, VI(3):9 differential diagnosis, VI(3):9 middle ear prolapsing facial nerve vs., VI(6):5 P Pacchionian depressions, granulations, or bodies See Dural sinus, and aberrant arachnoid granulations Pachymeningitis, cranial hypertrophic See Pseudotumor, idiopathic inflammatory, skull base Paget disease skull base, V(1):64, V(1):65 differential diagnosis, V(1):65 fibrous dysplasia vs., V(1):61 osteopetrosis vs., V(1):71 osteosarcoma associated with, V(1):95 staging, grading, & classification, V(1):65 temporal bone, VI(7):8, VI(7):9 differential diagnosis, VI(7):9 fibrous dysplasia vs., VI(7):6, VI(7):7 osteoradionecrosis vs., VI(7):15 otosclerosis vs., VI(4):41 otosyphilis vs., VI(4):35 Palatal cyst, median, nasopalatine duct cyst vs., I(15):19 Palate benign mixed tumor, I(14):34, I(14):35 differential diagnosis, I(14):35 hard palate SCCa vs., II(2):27 minor salivary gland malignancy vs., I(14):41 Palatine tonsil benign mixed tumor, squamous cell carcinoma vs., II(2):11 non-Hodgkin lymphoma, squamous cell carcinoma vs., II(2):11 Palatine tonsil squamous cell carcinoma, II(2):10, II(2):11, II(2):12, II(2):13 clinical issues, II(2):12 differential diagnosis, II(2):11 imaging, II(2):11, II(2):13 lingual tonsil SCC vs., II(2):7 Non-Hodgkin lymphoma vs., I(3):19 pathology, II(2):11, II(2):12 Diagnostic Imaging Head and Neck staging, grading, & classification, II(2):12 tonsillar inflammation vs., I(3):11 tonsillar/peritonsillar abscess vs., I(3):13 Pancreatic tumors and cysts, glomus vagale paraganglioma associated with, VI(6):30 Papilloma, inverted, IV(1):82, IV(1):83, IV(1):84, IV(1):85 clinical issues, IV(1):84 differential diagnosis, IV(1):83 imaging, IV(1):83, IV(1):85 mycetoma vs., IV(1):43 nerve sheath tumor vs., IV(1):88 pathology, IV(1):84 sinonasal benign mixed tumor vs., IV(1):89 solitary sinonasal polyp vs., IV(1):53 staging, grading, & classification, IV(1):84 Paraganglioma carotid body See Carotid body paraganglioma glomus jugulare See Glomus jugulare paraganglioma glomus tympanicum See Glomus tympanicum paraganglioma glomus vagale See Glomus vagale paraganglioma multiple head and neck, glomus vagale paraganglioma associated with, VI(6):30 Paraganglioma syndromes, carotid body paraganglioma associated with, VI(6):26 Parapharyngeal space, I(2):2, I(2):3, I(2):4, I(2):5 benign mixed tumor, I(2):4, I(2):5 clinical implications, I(2):2 differential diagnosis, I(2):2 images, I(2):3 imaging anatomy, I(2):2 approaches to imaging issues, I(2):2 overview, I(2):2, I(2):3 Parathyroid adenoma, I(10):16, I(10):17, I(10):18, I(10):19 clinical issues, I(10):18 differential diagnosis, I(10):17 imaging, I(10):17, I(10):19 parathyroid carcinoma vs., I(10):35 pathology, I(10):18 pediatric neurofibromatosis type associated with, III(2):4 thyroid adenoma vs., I(10):13 P.xxxvii Parathyroid carcinoma, I(10):34, I(10):35 differential diagnosis, I(10):35 parathyroid adenoma vs., I(10):17 staging, grading, & classification, I(10):35 Parathyroid cyst esophagopharyngeal diverticulum vs., I(10):39 lateral cervical esophageal diverticulum vs., I(10):41 visceral space, parathyroid adenoma vs., I(10):17 Parotid benign mixed tumor, I(5):18, I(5):19, I(5):20, I(5):21 adenoid cystic carcinoma vs., I(5):33 clinical issues, I(5):20 deep lobe, pharyngeal benign mixed tumor vs., I(2):5 differential diagnosis, I(5):19, I(5):20 imaging, I(5):19, I(5):21 malignant mixed tumor vs., I(5):35 mucoepidermoid carcinoma vs., I(5):29 pathology, I(5):20 recurrent, parotid nodal metastatic disease vs., I(5):41 schwannoma vs., I(5):27 Warthin tumor vs., I(5):23 Parotid carcinoma adenoid cystic, I(5):32, I(5):33 differential diagnosis, I(5):33 malignant, Warthin tumor vs., I(5):23 parotid mucoepidermoid carcinoma vs., I(5):29 parotid space malignant mixed tumor vs., I(5):35 staging, grading, & classification, I(5):33 ductal, parotid mucoepidermoid carcinoma vs., I(5):29 mucoepidermoid, I(5):28, I(5):29, I(5):30, I(5):31 clinical issues, I(5):30 differential diagnosis, I(5):29 imaging, I(5):29, I(5):31 Kimura disease vs., I(12):25 malignant, Warthin tumor vs., I(5):23 parotid adenoid cystic carcinoma vs., I(5):33 parotid space malignant mixed tumor vs., I(5):35 schwannoma vs., I(5):27 staging, grading, & classification, I(5):30 primary, benign mixed tumor of parotid space vs., I(5):19, I(5):20 Parotid malignancy acute parotitis vs., I(5):7 perineural intratemporal facial nerve See Facial nerve, intratemporal, perineural parotid malignancy mastoid facial nerve, persistent stapedial artery vs., VI(3):17 Parotid malignant mixed tumor, I(5):34, I(5):35 Parotid metastatic disease benign lymphoepithelial lesions-HIV vs., I(5):15 nodal, I(5):40, I(5):41, I(5):42, I(5):43 benign mixed tumor of parotid space vs., I(5):19, I(5):20 clinical issues, I(5):42 differential diagnosis, I(5):41 imaging, I(5):41, I(5):43 1690 Kimura disease vs., I(12):25 parotid adenoid cystic carcinoma vs., I(5):33 parotid mucoepidermoid carcinoma vs., I(5):29 parotid non-Hodgkin lymphoma vs., I(5):37 pathology, I(5):41, I(5):42 Warthin tumor vs., I(5):23 parotid Sjögren syndrome vs., I(5):12 schwannoma vs., I(5):27 Parotid sarcoidosis acute parotitis vs., I(5):7 benign lymphoepithelial lesions-HIV vs., I(5):15 parotid Sjögren syndrome vs., I(5):12 Parotid Sjögren syndrome, I(5):10, I(5):11, I(5):12, I(5):13 1st branchial cleft cyst vs., III(1):25 acute parotitis vs., I(5):7 benign lymphoepithelial lesions-HIV vs., I(5):15 clinical issues, I(5):12 differential diagnosis, I(5):11, I(5):12 imaging, I(5):11, I(5):13 non-Hodgkin lymphoma associated with, I(5):38 parotid nodal metastatic disease vs., I(5):41 parotid non-Hodgkin lymphoma vs., I(5):37 staging, grading, & classification, I(5):12 Parotid space, I(5):2, I(5):3, I(5):4, I(5):5, I(5):6, I(5):7, I(5):8, I(5):9, I(5):10, I(5):11, I(5):12, I(5):13, I(5):14, I(5):15, I(5):16, I(5):17, I(5):18, I(5):19, I(5):20, I(5):21, I(5):22, I(5):23, I(5):24, I(5):25, I(5):26, I(5):27, I(5):28, I(5):29, I(5):30, I(5):31, I(5):32, I(5):33, I(5):34, I(5):35, I(5):36, I(5):37, I(5):38, I(5):39, I(5):40, I(5):41, I(5):42, I(5):43 acute parotitis, I(5):6, I(5):7, I(5):8, I(5):9 adenoid cystic carcinoma See Parotid carcinoma, adenoid cystic benign lymphoepithelial lesions-HIV See Lymphoepithelial lesions-HIV, benign carcinoma See Parotid carcinoma clinical implications, I(5):2, I(5):3 differential diagnosis, I(5):3 images, I(5):4, I(5):5 imaging anatomy, I(5):2 approaches to imaging issues, I(5):3 techniques, I(5):2 metastatic disease See Parotid metastatic disease mucoepidermoid carcinoma See Parotid carcinoma, mucoepidermoid non-Hodgkin lymphoma See NonHodgkin lymphoma, parotid overview, I(5):2, I(5):3, I(5):4, I(5):5 schwannoma, I(5):26, I(5):27 sialocele, 1st branchial cleft cyst vs., III(1):25 Diagnostic Imaging Head and Neck sialosis, acute parotitis vs., I(5):7 Sjögren syndrome See Parotid Sjögren syndrome P.xxxviii Warthin tumor See Warthin tumor, parotid space Parotitis acute, I(5):6, I(5):7, I(5):8, I(5):9 clinical issues, I(5):8 differential diagnosis, I(5):7 imaging, I(5):7, I(5):9 pathology, I(5):8 chronic infectious or obstructive, parotid Sjögren syndrome vs., I(5):11 Pars flaccida cholesteatoma, VI(3):28, VI(3):29, VI(3):30, VI(3):31 clinical issues, VI(3):30 congenital mastoid cholesteatoma vs., VI(3):6 congenital middle ear cholesteatoma vs., VI(3):3 differential diagnosis, VI(3):29 imaging, VI(3):29, VI(3):31 middle ear cholesterol granuloma vs., VI(3):39 middle ear schwannoma vs., VI(3):51 pars tensa cholesteatoma vs., VI(3):33 pathology, VI(3):29, VI(3):30 temporal bone rhabdomyosarcoma vs., VI(3):55 Pars tensa cholesteatoma, VI(3):32, VI(3):33, VI(3):34, VI(3):35 clinical issues, VI(3):34 congenital middle ear cholesteatoma vs., VI(3):3 differential diagnosis, VI(3):33 imaging, VI(3):33, VI(3):35 pars flaccida cholesteatoma vs., VI(3):29 pathology, VI(3):33, VI(3):34 temporal bone rhabdomyosarcoma vs., VI(3):55 Pediatric lesions congenital, III(1):2, III(1):3, III(1):4, III(1):5, III(1):6, III(1):7, III(1):8, III(1):9, III(1):10, III(1):11, III(1):12, III(1):13, III(1):14, III(1):15, III(1):16, III(1):17, III(1):18, III(1):19, III(1):20, III(1):21, III(1):22, III(1):23, III(1):24, III(1):25, III(1):26, III(1):27, III(1):28, III(1):29, III(1):30, III(1):31, III(1):32, III(1):33, III(1):34, III(1):35, III(1):36, III(1):37, III(1):38, III(1):39, III(1):40, III(1):41, III(1):42, III(1):43, III(1):44, III(1):45, III(1):46, III(1):47, III(1):48, III(1):49, III(1):50, III(1):51, III(1):52, III(1):53, III(1):54, III(1):55 congenital syndromic, III(2):2, III(2):3, III(2):4, III(2):5, III(2):6, III(2):7, III(2):8, III(2):9, III(2):10, III(2):11, III(2):12, III(2):13, III(2):14, III(2):15, III(2):16, III(2):17, III(2):18, III(2):19, III(2):20, III(2):21, III(2):22, III(2):23, III(2):24, III(2):25 fibromatosis colli, III(1):44, III(1):45 infantile hemangioma See Hemangioma, infantile metastatic neuroblastoma, III(1):55 differential diagnosis, III(1):55 orbital infantile hemangioma vs., IV(2):57 primary cervical neuroblastoma vs., III(1):54 primary cervical neuroblastoma, III(1):54 differential diagnosis, III(1):54 fibromatosis colli vs., III(1):45 rhabdomyosarcoma See Rhabdomyosarcoma, pediatric Pendred syndrome, large vestibular aqueduct associated with, VI(4):16 Periapical (radicular) cyst, I(15):12, I(15):13 ameloblastoma vs., I(15):31 basal cell nevus syndrome vs., III(2):9 dentigerous cyst vs., I(15):15 differential diagnosis, I(15):13 keratocystic odontogenic tumor vs., I(15):35 nasolabial cyst vs., I(15):11 simple bone cyst (traumatic) vs., I(15):17 Pericochlear hypoattenuating foci, localized See Cochlear cleft Perineural parotid malignancy intratemporal facial nerve See Facial nerve, intratemporal, perineural parotid malignancy mastoid facial nerve, persistent stapedial artery vs., VI(3):17 Perineural tumor CNV2, trigeminal schwannoma of central skull base vs., V(1):19 CNV3 See CNV3 perineural tumor, masticator space Perineural tumor spread, II(2):42, II(2):43, II(2):44, II(2):45 clinical issues, II(2):44 differential diagnosis, II(2):43 imaging, II(2):43, II(2):45 pathology, II(2):43, II(2):44 staging, grading, & classification, II(2):44 Periodontal cyst, lateral, periapical (radicular) cyst vs., I(15):13 Periodontitis, apical nasopalatine duct cyst vs., I(15):19 periapical (radicular) cyst vs., I(15):13 Perioptic meningioma See Optic nerve sheath meningioma Peripheral nerve sheath tumor, malignant, I(13):26, I(13):27 brachial plexus schwannoma in perivertebral space vs., I(8):17 differential diagnosis, I(13):27 pathology, I(13):27, III(2):4 synovial sarcoma of head and neck vs., I(13):25 Perivertebral space, I(8):2, I(8):3, I(8):4, I(8):5, I(8):6, I(8):7, I(8):8, I(8):9, I(8):10, 1691 I(8):11, I(8):12, I(8):13, I(8):14, I(8):15, I(8):16, I(8):17, I(8):18, I(8):19, I(8):20, I(8):21, I(8):22, I(8):23 brachial plexus schwannoma, I(8):16, I(8):17 chordoma in perivertebral space vs., I(8):19 differential diagnosis, I(8):17 chordoma, I(8):18, I(8):19 differential diagnosis, I(8):19 perivertebral space infection vs., I(8):12 vertebral body metastasis vs., I(8):21 clinical implications, I(8):3 differential diagnosis, I(8):3 images, I(8):4, I(8):5 imaging anatomy, I(8):2 approaches to imaging issues, I(8):2, I(8):3 techniques and indications, I(8):2 infection, I(8):10, I(8):11, I(8):12, I(8):13 acute calcific longus colli tendinitis vs., I(8):9 chordoma vs., I(8):19 clinical issues, I(8):12 differential diagnosis, I(8):11, I(8):12 imaging, I(8):11, I(8):13 pathology, I(8):12 vertebral body metastasis vs., I(8):21 levator scapulae muscle hypertrophy, I(8):6, I(8):7 longus colli tendinitis acute calcific, I(8):8, I(8):9 vertebral body metastasis vs., I(8):21 P.xxxix overview, I(8):2, I(8):3, I(8):4, I(8):5 vertebral artery dissection in neck, I(8):14, I(8):15 vertebral body metastasis See Vertebral body metastasis, perivertebral space Persistent basal medial canal, persistent craniopharyngeal canal vs., V(1):17 Persistent craniopharyngeal canal, V(1):16, V(1):17 Persistent hyperplastic primary vitreous See Vitreous, persistent hyperplastic primary Persistent hypoglossal artery, hypoglossal nerve schwannoma vs., V(1):21 Persistent stapedial artery, VI(3):16, VI(3):17 aberrant internal carotid artery associated with, VI(3):14 differential diagnosis, VI(3):17 middle ear prolapsing facial nerve vs., VI(6):5 Petromastoid canal See Subarcuate canaliculus Petrooccipital fissure chondrosarcoma apical petrositis vs., VI(5):19 Diagnostic Imaging Head and Neck invasive pituitary macroadenoma vs., V(1):11 Petrositis, apical, VI(5):18, VI(5):19, VI(5):20, VI(5):21 acute otomastoiditis with abscess vs., VI(3):19 asymmetric marrow vs., VI(5):3 cholesterol granuloma vs., VI(5):15 clinical issues, VI(5):20 confluent, temporal bone metastasis vs., VI(7):13 congenital cholesteatoma vs., VI(5):7 differential diagnosis, VI(5):19 imaging, VI(5):19, VI(5):21 pathology, VI(5):20 trapped fluid vs., VI(5):11 Petrous apex, VI(5):2, VI(5):3, VI(5):4, VI(5):5, VI(5):6, VI(5):7, VI(5):8, VI(5):9, VI(5):10, VI(5):11, VI(5):12, VI(5):13, VI(5):14, VI(5):15, VI(5):16, VI(5):17, VI(5):18, VI(5):19, VI(5):20, VI(5):21, VI(5):22, VI(5):23 apical petrositis See Petrositis, apical asymmetric marrow, VI(5):2, VI(5):3 cholesterol granuloma vs., VI(5):15 differential diagnosis, VI(5):3 cephalocele, VI(5):4, VI(5):5 cholesterol granuloma See Cholesterol granuloma, petrous apex congenital cholesteatoma See Cholesteatoma, congenital, petrous apex differential diagnosis, VI(1):4 imaging anatomy, VI(1):3 internal carotid artery aneurysm See Carotid artery, petrous ICA aneurysm metastasis, apical petrositis vs., VI(5):19 mucocele See Mucocele, petrous apex trapped fluid, VI(5):10, VI(5):11 apical petrositis vs., VI(5):19 asymmetric marrow vs., VI(5):3 cholesterol granuloma vs., VI(5):15 congenital cholesteatoma vs., VI(5):7 differential diagnosis, VI(5):11 mucocele vs., VI(5):13 Petrous jugular malposition See Jugular bulb diverticulum PHACES association, III(2):10, III(2):11, III(2):12, III(2):13 clinical issues, III(2):12 differential diagnosis, III(2):11 imaging, III(2):11, III(2):13 orbital infantile hemangioma associated with, IV(2):57 pathology, III(2):11, III(2):12 staging, grading, & classification, III(2):12 upper airway infantile hemangioma associated with, I(11):17 Pharyngeal bursa See Tornwaldt cyst Pharyngeal mucosal space, I(3):2, I(3):3, I(3):4, I(3):5, I(3):6, I(3):7, I(3):8, I(3):9, I(3):10, I(3):11, I(3):12, I(3):13, I(3):14, I(3):15, I(3):16, I(3):17, I(3):18, I(3):19, I(3):20, I(3):21 benign mixed tumor, I(3):14, I(3):15 differential diagnosis, I(3):15 minor salivary gland malignancy vs., I(3):17 Non-Hodgkin lymphoma vs., I(3):19 retention cyst of pharyngeal mucosal space vs., I(3):9 tonsillar/peritonsillar abscess vs., I(3):13 Tornwaldt cyst vs., I(3):7 clinical implications, I(3):3 differential diagnosis, I(3):3 images, I(3):4, I(3):5 imaging anatomy, I(3):2 approaches to imaging issues, I(3):2, I(3):3 techniques and indications, I(3):2 minor salivary gland malignancy, I(3):16, I(3):17 benign mixed tumor of pharyngeal mucosal space vs., I(3):15 differential diagnosis, I(3):17 Non-Hodgkin lymphoma vs., I(3):19 staging, grading, & classification, I(3):17 non-Hodgkin lymphoma See NonHodgkin lymphoma, pharyngeal mucosal space overview, I(3):2, I(3):3, I(3):4, I(3):5 retention cyst, I(3):8, I(3):9 benign mixed tumor of pharyngeal mucosal space vs., I(3):15 congenital vallecular cyst vs., III(1):15 differential diagnosis, I(3):9 tonsillar/peritonsillar abscess vs., I(3):13 Tornwaldt cyst vs., I(3):7 sarcoma, nasopharyngeal carcinoma vs., II(2):3 squamous cell carcinoma benign mixed tumor of pharyngeal mucosal space vs., I(3):15 minor salivary gland malignancy vs., I(3):17 tonsillar inflammation, I(3):10, I(3):11 differential diagnosis, I(3):11 post-transplantation lymphoproliferative disorder vs., I(13):15 tonsillar/peritonsillar abscess, I(3):12, I(3):13 differential diagnosis, I(3):13 palatine tonsil squamous cell carcinoma vs., II(2):11 post-transplantation lymphoproliferative disorder vs., I(13):15 P.xl tonsillar inflammation vs., I(3):11 Tornwaldt cyst, I(3):6, I(3):7 differential diagnosis, I(3):7 extraosseous chordoma vs., I(13):17 retention cyst of pharyngeal mucosal space vs., I(3):9 1692 Pharyngeal pouch See Esophagopharyngeal diverticulum (Zenker) Pharyngoesophageal diverticulum See Esophagopharyngeal diverticulum (Zenker) Pheochromocytoma adrenal, glomus vagale paraganglioma associated with, VI(6):30 pediatric neurofibromatosis type associated with, III(2):4 Pial arteriovenous malformation, dural arteriovenous fistula vs., V(1):51 Pierre Robin sequence, III(2):20, III(2):21 Pigmented villonodular synovitis, temporomandibular joint, I(15):25 Pituitary macroadenoma giant, skull base meningioma vs., V(1):79 invasive, V(1):10, V(1):11 chordoma vs., V(1):13 differential diagnosis, V(1):11 nasopharyngeal carcinoma vs., II(2):3 skull base multiple myeloma vs., V(1):87 skull base plasmacytoma vs., V(1):83 staging, grading, & classification, V(1):11 Plasma cell granuloma See Pseudotumor, idiopathic inflammatory, skull base Plasmacytoma skull base, V(1):82, V(1):83, V(1):84, V(1):85 chondrosarcoma vs., V(1):91 chordoma vs., V(1):13 clinical issues, V(1):84 differential diagnosis, V(1):83, V(1):84 imaging, V(1):83, V(1):85 invasive pituitary macroadenoma vs., V(1):11 malignant See Multiple myeloma, skull base meningioma vs., V(1):79 multiple myeloma vs., V(1):87 osteosarcoma vs., V(1):95 pathology, V(1):84 skull base giant cell tumor vs., V(1):77 staging, grading, & classification, V(1):84 temporal bone, metastasis vs., VI(7):13 Pleomorphic adenoma See Adenoma, pleomorphic Plexiform neurofibroma See Neurofibroma, plexiform Plummer-Vinson syndrome, cervical esophageal carcinoma associated with, I(10):37 Pneumocephalus, skull base trauma associated with, V(2):12 Polychondritis, relapsing laryngeal chondrosarcoma vs., I(11):19 laryngeal trauma vs., I(11):13 Polyp Diagnostic Imaging Head and Neck angiomatous, sinonasal hemangioma vs., IV(1):87 antrochoanal, juvenile angiofibroma vs., IV(1):80 Polyp, solitary sinonasal, IV(1):52, IV(1):53, IV(1):54, IV(1):55 benign mixed tumor vs., IV(1):89 clinical issues, IV(1):54 differential diagnosis, IV(1):53 imaging, IV(1):53, IV(1):55 inverted papilloma vs., IV(1):83 mucocele vs., IV(1):57 nasal glioma vs., IV(1):15 nerve sheath tumor vs., IV(1):88 pathology, IV(1):53, IV(1):54 polyposis vs., IV(1):49 Polyposis familial adenomatous, fibromatosis associated with, I(13):33 sinonasal, IV(1):48, IV(1):49, IV(1):50, IV(1):51 allergic fungal sinusitis vs., IV(1):41 chronic rhinosinusitis vs., IV(1):33 clinical issues, IV(1):50 differential diagnosis, IV(1):49 imaging, IV(1):49, IV(1):51 inverted papilloma vs., IV(1):83 orbital cellulitis associated with, IV(2):39 pathology, IV(1):49, IV(1):50 sinonasal mucocele vs., IV(1):57 Postanginal septicemia See Postpharyngitis venous thrombosis (Lemierre) Post-cricoid region squamous cell carcinoma, II(2):32 differential diagnosis, II(2):32 posterior hypopharyngeal wall SCCa vs., II(2):33 Posterior cervical space, I(9):2, I(9):3, I(9):4, I(9):5, I(9):6, I(9):7, I(9):8, I(9):9, I(9):10, I(9):11 clinical implications, I(9):2 differential diagnosis, I(9):2 images, I(9):3 imaging anatomy, I(9):2 approaches and indications, I(9):2 approaches to imaging issues, I(9):2 non-Hodgkin lymphoma in spinal accessory node, I(9):10, I(9):11 differential diagnosis, I(9):11 posterior cervical space schwannoma vs., I(9):5 staging, grading, & classification, I(9):11 overview, I(9):2, I(9):3 schwannoma, I(9):4, I(9):5, I(9):6, I(9):7 differential diagnosis, I(9):5 spinal accessory node non-Hodgkin lymphoma vs., I(9):11 spinal accessory node SCC vs., I(9):9 squamous cell carcinoma in spinal accessory node, I(9):8, I(9):9 P.xli Posterior fossa meningioma See Meningioma, CPAIAC venous angioma, hemifacial spasm vs., VI(8):43 trigeminal neuralgia vs., VI(8):41 Posterior hypopharyngeal wall squamous cell carcinoma, II(2):33 differential diagnosis, II(2):33 post-cricoid region SCCa vs., II(2):32 posterior oropharyngeal wall SCCa vs., II(2):14 Posterior oropharyngeal wall squamous cell carcinoma, II(2):14 Post-inflammatory cyst See Retention cyst, pharyngeal mucosal space Postoperative infection/abscess, reconstruction flaps in neck vs., II(3):5 Post-pharyngitis venous thrombosis (Lemierre), I(6):22, I(6):23 Post-transplantation lymphoproliferative disorder, I(13):14, I(13):15 differential diagnosis, I(13):15 non-Hodgkin lymphoma of pharyngeal mucosal space associated with, I(3):19 staging, grading, & classification, I(13):15 Preseptal cellulitis See Cellulitis, orbital Prevertebral longus colli tendinitis See Longus colli tendinitis, acute calcific Prominent thoracic duct, in neck, I(13):4, I(13):5 Prominent/asymmetric tonsillar tissue lingual thyroid vs., I(14):19 tonsillar inflammation vs., I(3):11 tonsillar/peritonsillar abscess vs., I(3):13 “Prussak” space cholesteatoma See Pars flaccida cholesteatoma Psammatoid ossifying fibroma See Fibroma, ossifying, sinonasal Pseudoaneurysm See Carotid artery, pseudoaneurysm, in neck Pseudofractures skull base trauma vs., V(2):11, V(2):12 temporal bone trauma vs., V(2):7, V(2):8 Pseudotumor, idiopathic inflammatory carotid See Carotidynia, acute idiopathic CPA-IAC sarcoidosis vs., VI(8):25 orbital, IV(2):40, IV(2):41, IV(2):42, IV(2):43 cellulitis vs., IV(2):39 clinical issues, IV(2):42 differential diagnosis, IV(2):41 imaging, IV(2):41, IV(2):43 lacrimal gland benign mixed tumor vs., IV(2):69 lacrimal gland carcinoma vs., IV(2):83 lymphatic malformation vs., IV(2):23 ocular melanoma vs., IV(2):75 optic nerve sheath meningioma vs., IV(2):65 1693 optic pathway glioma vs., IV(2):61 orbital lymphoproliferative lesions vs., IV(2):79 pathology, IV(2):42 pediatric dermoid/epidermoid cyst vs., III(1):42 subperiosteal abscess vs., IV(2):35 thyroid ophthalmopathy vs., IV(2):47 skull base, V(1):72, V(1):73, V(1):74, V(1):75 clinical issues, V(1):73, V(1):74 CPA-IAC meningioma vs., VI(8):31 differential diagnosis, V(1):73 imaging, V(1):73, V(1):75 metastasis vs., V(1):89 pathology, V(1):73, V(1):74 Pterygoid plate avulsion, trans-facial (Le Fort) fracture vs., V(2):19 Pterygoid venous plexus asymmetry, I(4):6, I(4):7 benign mixed tumor of parapharyngeal space vs., I(2):5 differential diagnosis, I(4):7 perineural CNV3 tumor of masticator space vs., I(4):21 Pyogenic granuloma See Hemangioma, sinonasal Pyolaryngocele, I(11):25 Pyriform aperture stenosis, congenital nasal, IV(1):26, IV(1):27 choanal atresia vs., IV(1):11 differential diagnosis, IV(1):27 solitary median maxillary central incisor vs., I(15):9 Pyriform sinus squamous cell carcinoma, II(2):28, II(2):29, II(2):30, II(2):31 clinical issues, II(2):30 differential diagnosis, II(2):29 imaging, II(2):29, II(2):31 pathology, II(2):29, II(2):30 staging, grading, & classification, II(2):29, II(2):30 R Radiation osteitis See Osteoradionecrosis Radiation therapy, squamous cell carcinoma of neck complications, II(3):7 expected changes, II(3):6 Radicular cyst See Periapical (radicular) cyst Ramsay Hunt syndrome, VI(8):22, VI(8):23 CPA-IAC metastases vs., VI(8):37 differential diagnosis, VI(8):23 Ranula, I(14):20, I(14):21, I(14):22, I(14):23 abscess vs., I(14):29, I(14):30 accessory salivary tissue vs., I(14):11 clinical issues, I(14):22 dermoid and epidermoid cyst vs., I(14):13 differential diagnosis, I(14):21 Diagnostic Imaging Head and Neck imaging, I(14):21, I(14):23 lymphatic malformation vs., I(14):17 pathology, I(14):21, I(14):22 pediatric dermoid/epidermoid cyst vs., III(1):41 P.xlii sialocele vs., I(14):25 staging, grading, & classification, I(14):22 sublingual gland carcinoma vs., I(14):37 Reactive adenopathy See Lymph nodes, reactive Reconstruction flaps in neck, II(3):4, II(3):5 Relapsing polychondritis laryngeal chondrosarcoma vs., I(11):19 laryngeal trauma vs., I(11):13 Renal anomalies, 2nd branchial cleft cyst associated with, III(1):30 Renal dysfunction, Kimura disease associated with, I(12):26 Renal tubular acidosis, distal, large vestibular aqueduct associated with, VI(4):16 Renal tumors and cysts, glomus vagale paraganglioma associated with, VI(6):30 Respiratory mucosal carcinoma See Sinonasal squamous cell carcinoma Retention cyst pharyngeal mucosal space, I(3):8, I(3):9 benign mixed tumor of pharyngeal mucosal space vs., I(3):15 congenital vallecular cyst vs., III(1):15 differential diagnosis, I(3):9 tonsillar/peritonsillar abscess vs., I(3):13 Tornwaldt cyst vs., I(3):7 sinonasal, sinonasal polyposis vs., IV(1):49 Retinal detachment coloboma associated with, IV(2):8 ocular melanoma vs., IV(2):75 Retinal telangiectasis See Coats disease Retinoblastoma, IV(2):70, IV(2):71, IV(2):72, IV(2):73 clinical issues, IV(2):72 Coats disease vs., IV(2):13 differential diagnosis, IV(2):71 imaging, IV(2):71, IV(2):73 masticator space sarcoma associated with, I(4):29 ocular melanoma vs., IV(2):75 ocular toxocariasis vs., IV(2):33 pathology, IV(2):71, IV(2):72 persistent hyperplastic primary vitreous vs., IV(2):11 staging, grading, & classification, IV(2):72 Retinopathy of prematurity Coats disease vs., IV(2):13 ocular toxocariasis vs., IV(2):33 persistent hyperplastic primary vitreous vs., IV(2):11 retinoblastoma vs., IV(2):71 Retinopathy/retinitis, exudative See Coats disease Retromolar trigone squamous cell carcinoma, II(2):24, II(2):25 differential diagnosis, II(2):25 staging, grading, & classification, II(2):25 Retropharyngeal carotid artery See Carotid artery, tortuous, in neck Retropharyngeal space, I(7):2, I(7):3, I(7):4, I(7):5, I(7):6, I(7):7, I(7):8, I(7):9, I(7):10, I(7):11, I(7):12, I(7):13, I(7):14, I(7):15, I(7):16, I(7):17, I(7):18, I(7):19, I(7):20, I(7):21, I(7):22, I(7):23 abscess, I(7):10, I(7):11, I(7):12, I(7):13 acute calcific longus colli tendinitis vs., I(8):9 clinical issues, I(7):12 differential diagnosis, I(7):11 edema vs., I(7):15 epiglottitis in child vs., I(11):10 imaging, I(7):11, I(7):13 pathology, I(7):11 perivertebral space infection vs., I(8):11, I(8):12 suppurative adenopathy of retropharyngeal space vs., I(7):9 tonsillar/peritonsillar abscess vs., I(3):13 clinical implications, I(7):3 differential diagnosis, I(7):3 edema, I(7):14, I(7):15, I(7):16, I(7):17 acute calcific longus colli tendinitis vs., I(8):9 clinical issues, I(7):16 differential diagnosis, I(7):15 imaging, I(7):15, I(7):17 pathology, I(7):15, I(7):16 RPS abscess vs., I(7):11 images, I(7):4, I(7):5 imaging anatomy, I(7):2 approaches and indications, I(7):2 approaches to imaging issues, I(7):2, I(7):3 lipoma, RPS edema vs., I(7):15 metastatic nodes, non-squamous cell carcinoma, I(7):22, I(7):23 differential diagnosis, I(7):23 reactive adenopathy vs., I(7):7 nodal non-Hodgkin lymphoma, I(7):20, I(7):21 differential diagnosis, I(7):21 staging, grading, & classification, I(7):21 nodal squamous cell carcinoma, I(7):18, I(7):19 differential diagnosis, I(7):19 nodal non-Hodgkin lymphoma vs., I(7):21 non-SCCA metastatic nodes vs., I(7):23 reactive adenopathy vs., I(7):7 suppurative adenopathy of retropharyngeal space vs., I(7):9 1694 sympathetic schwannoma vs., I(6):37 overview, I(7):2, I(7):3, I(7):4, I(7):5 prominent normal fat, RPS edema vs., I(7):15 reactive adenopathy, I(7):6, I(7):7 differential diagnosis, I(7):7 nodal non-Hodgkin lymphoma vs., I(7):21 non-SCCA metastatic nodes vs., I(7):23 suppurative adenopathy vs., I(7):9 schwannoma, suppurative adenopathy of retropharyngeal space vs., I(7):9 suppurative adenopathy, I(7):8, I(7):9 differential diagnosis, I(7):9 nodal non-Hodgkin lymphoma vs., I(7):21 non-SCCA metastatic nodes vs., I(7):23 reactive adenopathy vs., I(7):7 RPS abscess vs., I(7):11 P.xliii Rhabdomyosarcoma fibromatosis vs., I(13):33 juvenile angiofibroma vs., IV(1):79 orbital dermoid/epidermoid cyst vs., IV(2):15 infantile hemangioma vs., IV(2):57 Langerhans cell histiocytosis vs., IV(2):55 lymphatic malformation vs., IV(2):23 pediatric dermoid/epidermoid cyst vs., III(1):41 “parameningeal type.” See Rhabdomyosarcoma, temporal bone pediatric, III(1):50, III(1):51, III(1):52, III(1):53 clinical issues, III(1):52 differential diagnosis, III(1):51 fibromatosis colli vs., III(1):45 imaging, III(1):51, III(1):53 infantile hemangioma vs., III(1):48 metastatic neuroblastoma vs., III(1):55 neurofibromatosis type vs., III(2):3 orbital, pediatric dermoid/epidermoid cyst vs., III(1):41 pathology, III(1):51, III(1):52 staging, grading, & classification, III(1):52 skull base Langerhans cell histiocytosis vs., V(1):67 synovial sarcoma of head and neck vs., I(13):25 temporal bone, VI(3):54, VI(3):55, VI(3):56, VI(3):57 acute otomastoiditis with abscess vs., VI(3):19 clinical issues, VI(3):56 coalescent otomastoiditis vs., VI(3):23 differential diagnosis, VI(3):55, VI(3):56 imaging, VI(3):55, VI(3):57 pathology, VI(3):56 staging, grading, & classification, VI(3):56 Rheumatoid arthritis Diagnostic Imaging Head and Neck non-Hodgkin lymphoma associated with, I(5):38 temporomandibular joint dislocation vs., V(2):29 Rheumatoid larynx subglottic laryngeal SCCa vs., II(2):41 supraglottic laryngeal SCCa vs., II(2):35 Rhinitis, vasomotor, skull base CSF leak vs., V(1):59 Rhinorrhea, temporal bone CSF leak vs., VI(7):3 Rhinosinusitis acute, IV(1):28, IV(1):29, IV(1):30, IV(1):31 chronic rhinosinusitis vs., IV(1):33 clinical issues, IV(1):30 differential diagnosis, IV(1):29 imaging, IV(1):29, IV(1):31 pathology, IV(1):29, IV(1):30 staging, grading, & classification, IV(1):30 chronic, IV(1):32, IV(1):33, IV(1):34, IV(1):35 See also Fungal sinusitis, allergic clinical issues, IV(1):34 differential diagnosis, IV(1):33 imaging, IV(1):33, IV(1):35 keratosis obturans associated with, VI(2):9 mycetoma vs., IV(1):43 pathology, IV(1):33, IV(1):34 sinonasal polyposis associated with, IV(1):50 staging, grading, & classification, IV(1):34 Wegener granulomatosis vs., IV(1):63 complications, IV(1):36, IV(1):37, IV(1):38, IV(1):39 clinical issues, IV(1):38 differential diagnosis, IV(1):38 imaging, IV(1):37, IV(1):39 invasive fungal sinusitis vs., IV(1):45 pathology, IV(1):38 hypertrophic polypoid See Polyposis, sinonasal Rosai-Dorfman disease See Sinus histiocytosis (Rosai-Dorfman) S Saccular cyst See Laryngocele; Vallecular cyst, congenital Salivary gland malignancy See Minor salivary gland malignancy Salivary tissue, accessory, submandibular space, I(14):10, I(14):11 Sarcoid reaction, orbital, sarcoidosis vs., IV(2):45 Sarcoidosis cavernous sinus thrombosis vs., V(1):49 CPA-IAC, VI(8):24, VI(8):25 differential diagnosis, VI(8):25 meningioma vs., VI(8):31 meningitis vs., VI(8):21 metastases vs., VI(8):37 neurofibromatosis type vs., III(2):7 laryngeal, supraglottic laryngeal SCCa vs., II(2):35 lymph nodes, I(12):17 differential diagnosis, I(12):17 Kimura disease vs., I(12):25 nodal non-Hodgkin lymphoma in neck vs., I(12):29 reactive lymph nodes vs., I(12):7 systemic nodal metastases in neck vs., I(12):39 orbital, IV(2):44, IV(2):45 cellulitis vs., IV(2):39 differential diagnosis, IV(2):45 idiopathic inflammatory pseudotumor vs., IV(2):41 lacrimal gland carcinoma vs., IV(2):83 lymphoproliferative lesions vs., IV(2):79 optic nerve sheath meningioma vs., IV(2):65 optic pathway glioma vs., IV(2):61 thyroid ophthalmopathy vs., IV(2):47 parotid acute parotitis vs., I(5):7 P.xliv benign lymphoepithelial lesions-HIV vs., I(5):15 parotid Sjögren syndrome vs., I(5):12 perineural tumor spread vs., II(2):43 sinonasal chronic rhinosinusitis vs., IV(1):33 nasal cocaine necrosis vs., IV(1):67 sinonasal polyposis vs., IV(1):49 Wegener granulomatosis vs., IV(1):63 Sarcoma See also Osteosarcoma alveolar soft part, tongue, squamous cell carcinoma vs., II(2):17 Ewing osteosarcoma of mandible-maxilla vs., I(15):39 perivertebral space infection vs., I(8):12 laryngeal chondrosarcoma vs., I(11):19 liposarcoma of head and neck vs., I(13):23 masticator space, I(4):28, I(4):29, I(4):30, I(4):31 benign masticator muscle hypertrophy vs., I(4):9 clinical issues, I(4):30 differential diagnosis, I(4):29 imaging, I(4):29, I(4):31 masticator space abscess vs., I(4):15 pathology, I(4):29, I(4):30 staging, grading, & classification, I(4):29, I(4):30 pharyngeal mucosal space, nasopharyngeal carcinoma vs., II(2):3 plexiform neurofibroma vs., I(13):13 synovial, of head and neck, I(13):24, I(13):25 Schneiderian papilloma See Papilloma, inverted Schwannoma brachial plexus, in perivertebral space, I(8):16, I(8):17 1695 chordoma in perivertebral space vs., I(8):19 differential diagnosis, I(8):17 carotid space, I(6):32, I(6):33, I(6):34, I(6):35 2nd branchial cleft cyst vs., III(1):29 carotid artery dissection vs., I(6):9 carotid body paraganglioma vs., I(6):25 clinical issues, I(6):34 differential diagnosis, I(6):33 glomus vagale paraganglioma vs., I(6):29 imaging, I(6):33, I(6):35 meningioma vs., I(6):41 neurofibroma vs., I(6):38 pathology, I(6):33, I(6):34 sympathetic schwannoma vs., I(6):37 cavernous sinus, cavernous sinus thrombosis vs., V(1):49 CNV3, masticator space, I(4):18, I(4):19 differential diagnosis, I(4):19 imaging, I(4):19 perineural CNV3 tumor of masticator space vs., I(4):21 facial nerve See Facial nerve schwannoma intralabyrinthine, VI(4):44, VI(4):45, VI(4):46, VI(4):47 differential diagnosis, VI(4):45 intralabyrinthine hemorrhage vs., VI(4):51 labyrinthine ossificans vs., VI(4):37 labyrinthitis vs., VI(4):33 jugular foramen See Jugular foramen schwannoma malignant peripheral nerve sheath tumor vs., I(13):27 middle ear, VI(3):50, VI(3):51 differential diagnosis, VI(3):51 middle ear adenoma vs., VI(3):53 multiple, posterior cervical space schwannoma associated with, I(9):6 myocutaneous, glomus jugulare paraganglioma associated with, V(1):32 oral tongue, oral tongue SCCa vs., II(2):17 orbital cavernous hemangioma vs., IV(2):29 parotid space, I(5):26, I(5):27 differential diagnosis, I(5):27 staging, grading, & classification, I(5):27 perineural tumor spread vs., II(2):43 posterior cervical space, I(9):4, I(9):5, I(9):6, I(9):7 clinical issues, I(9):6 differential diagnosis, I(9):5 imaging, I(9):5, I(9):7 pathology, I(9):6 spinal accessory node non-Hodgkin lymphoma vs., I(9):11 spinal accessory node squamous cell carcinoma vs., I(9):9 retropharyngeal space, suppurative adenopathy of retropharyngeal space vs., I(7):9 sympathetic, I(6):36, I(6):37 Diagnostic Imaging Head and Neck differential diagnosis, I(6):37 glomus vagale paraganglioma vs., I(6):33 staging, grading, & classification, I(6):37 translabyrinthine or inner ear, imaging, VI(3):51 transmodiolar cochlear nerve, perineural parotid malignancy vs., VI(6):19 trigeminal intracranial, CPA-IAC meningioma vs., VI(8):31 skull base central, V(1):19 hemangiopericytoma vs., I(13):11 meningioma vs., V(1):79 vestibular See Vestibular schwannoma Schwannomatosis See Neurofibromatosis type Sclerosing endophthalmitis See Toxocariasis, ocular Sclerosing lymphocytic thyroiditis See Thyroiditis, chronic lymphocytic (Hashimoto) Scoliosis, plexiform neurofibroma of head and neck associated with, I(13):13 Semicircular canal dehiscence, VI(4):52, VI(4):53 hypoplasia-aplasia, VI(4):27 P.xlv normal thinning, SSC dehiscence vs., VI(4):53 superior, dehiscence, temporal bone cephalocele associated with, VI(3):59 Sensorineural hearing loss, imaging approaches to imaging issues, VI(8):2, VI(8):3 techniques and indications, VI(8):2 Septicemia, postanginal See Postpharyngitis venous thrombosis (Lemierre) Seroma, postoperative, lymphocele of neck vs., I(13):29 Sialadenitis acute See Parotitis, acute submandibular gland, I(14):26, I(14):27 benign mixed tumor vs., I(14):33 differential diagnosis, I(14):27 submandibular gland carcinoma vs., I(14):39 Sialocele oral cavity, I(14):24, I(14):25 differential diagnosis, I(14):25 ranula vs., I(14):21 parotid, 1st branchial cleft cyst vs., III(1):25 submandibular duct, abscess vs., I(14):30 Sialosis, acute parotitis vs., I(5):7 Sicca syndrome See Parotid Sjögren syndrome Siderosis, superficial, VI(8):46, VI(8):47, VI(8):48, VI(8):49 clinical issues, VI(8):48 differential diagnosis, VI(8):47 imaging, VI(8):47, VI(8):49 pathology, VI(8):47, VI(8):48 Sigmoid sinus-jugular bulb pseudolesion, dural arteriovenous fistula vs., V(1):51 thrombosis, jugular bulb pseudolesion vs., V(1):23 Sigmoid-transverse sinus pseudolesion, dural sinus and aberrant arachnoid granulations vs., V(1):41 Silent sinus syndrome, IV(1):60, IV(1):61 Simple bone cyst (traumatic), I(15):16, I(15):17 Simple ranula See Ranula Sincipital cephalocele See Frontoethmoidal cephalocele Single central incisor See Solitary median maxillary central incisor Sinonasal cavities, IV(1):2, IV(1):3, IV(1):4, IV(1):5, IV(1):6, IV(1):7, IV(1):8, IV(1):9, IV(1):10, IV(1):11, IV(1):12, IV(1):13, IV(1):14, IV(1):15, IV(1):16, IV(1):17, IV(1):18, IV(1):19, IV(1):20, IV(1):21, IV(1):22, IV(1):23, IV(1):24, IV(1):25, IV(1):26, IV(1):27, IV(1):28, IV(1):29, IV(1):30, IV(1):31, IV(1):32, IV(1):33, IV(1):34, IV(1):35, IV(1):36, IV(1):37, IV(1):38, IV(1):39, IV(1):40, IV(1):41, IV(1):42, IV(1):43, IV(1):44, IV(1):45, IV(1):46, IV(1):47, IV(1):48, IV(1):49, IV(1):50, IV(1):51, IV(1):52, IV(1):53, IV(1):54, IV(1):55, IV(1):56, IV(1):57, IV(1):58, IV(1):59, IV(1):60, IV(1):61, IV(1):62, IV(1):63, IV(1):64, IV(1):65, IV(1):66, IV(1):67, IV(1):68, IV(1):69, IV(1):70, IV(1):71, IV(1):72, IV(1):73, IV(1):74, IV(1):75, IV(1):76, IV(1):77, IV(1):78, IV(1):79, IV(1):80, IV(1):81, IV(1):82, IV(1):83, IV(1):84, IV(1):85, IV(1):86, IV(1):87, IV(1):88, IV(1):89, IV(1):90, IV(1):91, IV(1):92, IV(1):93, IV(1):94, IV(1):95, IV(1):96, IV(1):97, IV(1):98, IV(1):99, IV(1):100, IV(1):101, IV(1):102, IV(1):103, IV(1):104, IV(1):105, IV(1):106, IV(1):107, IV(1):108, IV(1):109 adenocarcinoma See Adenocarcinoma, sinonasal adenoid cystic carcinoma, IV(1):107 allergic fungal sinusitis See Fungal sinusitis, allergic benign mixed tumor, IV(1):89 differential diagnosis, IV(1):89 nerve sheath tumor vs., IV(1):88 choanal atresia, IV(1):10, IV(1):11, IV(1):12, IV(1):13 differential diagnosis, IV(1):11 solitary median maxillary central incisor vs., I(15):9 staging, grading, & classification, IV(1):11 chondrosarcoma, IV(1):108 differential diagnosis, IV(1):108 1696 osteosarcoma vs., IV(1):109 clinical implications, IV(1):3 congenital nasal pyriform aperture stenosis, IV(1):26, IV(1):27 choanal atresia vs., IV(1):11 differential diagnosis, IV(1):27 solitary median maxillary central incisor vs., I(15):9 differential diagnosis, IV(1):3 esthesioneuroblastoma See Esthesioneuroblastoma fibroma See Fibroma, ossifying, sinonasal fibrous dysplasia, IV(1):68, IV(1):69 chondrosarcoma vs., IV(1):108 differential diagnosis, IV(1):69 ossifying fibroma vs., IV(1):75 osteoma vs., IV(1):71 osteosarcoma vs., IV(1):109 frontoethmoidal cephalocele See Frontoethmoidal cephalocele fungal sinusitis See Fungal sinusitis hemangioma, IV(1):86, IV(1):87 differential diagnosis, IV(1):87 juvenile angiofibroma vs., IV(1):79 hemangiopericytoma See Hemangiopericytoma of head and neck images, IV(1):4, IV(1):5, IV(1):6, IV(1):7 imaging anatomy, IV(1):2 approaches and indications, IV(1):2 approaches to imaging issues, IV(1):3 protocols, IV(1):2 inverted papilloma See Papilloma, inverted juvenile angiofibroma See Juvenile angiofibroma melanoma, IV(1):100, IV(1):101 differential diagnosis, IV(1):101 esthesioneuroblastoma vs., IV(1):95 hemangioma vs., IV(1):87 non-Hodgkin lymphoma vs., IV(1):103 mucocele See Mucocele, sinonasal mycetoma, IV(1):42, IV(1):43 nasal cocaine necrosis, IV(1):66, IV(1):67 differential diagnosis, IV(1):67 staging, grading, & classification, IV(1):67 Wegener granulomatosis vs., IV(1):63 nasal dermal sinus, IV(1):18, IV(1):19, IV(1):20, IV(1):21 differential diagnosis, IV(1):19 frontoethmoidal cephalocele vs., IV(1):23 nasal glioma vs., IV(1):15 skull base cephalocele vs., V(1):55 nasal glioma See Nasal glioma nasolacrimal duct mucocele See Nasolacrimal duct mucocele P.xlvi nerve sheath tumor, IV(1):88 differential diagnosis, IV(1):88 Diagnostic Imaging Head and Neck sinonasal benign mixed tumor vs., IV(1):89 non-Hodgkin lymphoma See NonHodgkin lymphoma, sinonasal obstruction acute rhinosinusitis associated with, IV(1):29 orbital subperiosteal abscess associated with, IV(2):36 sinonasal mucocele associated with, IV(1):58 sinonasal osteoma associated with, IV(1):71 ossifying fibroma See Fibroma, ossifying, sinonasal osteoma, IV(1):70, IV(1):71, IV(1):72, IV(1):73 differential diagnosis, IV(1):71 fibrous dysplasia vs., IV(1):69 ossifying fibroma vs., IV(1):75 osteosarcoma vs., IV(1):109 staging, grading, & classification, IV(1):72 osteosarcoma, IV(1):109 chondrosarcoma vs., IV(1):108 differential diagnosis, IV(1):109 fibrous dysplasia vs., IV(1):69 ossifying fibroma vs., IV(1):75 overview, IV(1):2, IV(1):3, IV(1):4, IV(1):5, IV(1):6, IV(1):7 polyposis See Polyposis, sinonasal postobstructive secretions, acute rhinosinusitis vs., IV(1):29 post-traumatic blood level, acute rhinosinusitis vs., IV(1):29 post-traumatic or surgical change, silent sinus syndrome vs., IV(1):61 “pseudo” fluid level, acute rhinosinusitis vs., IV(1):29 retention cyst, sinonasal polyposis vs., IV(1):49 rhinosinusitis See Rhinosinusitis sarcoidosis chronic rhinosinusitis vs., IV(1):33 nasal cocaine necrosis vs., IV(1):67 sinonasal polyposis vs., IV(1):49 Wegener granulomatosis vs., IV(1):63 silent sinus syndrome, IV(1):60, IV(1):61 solitary polyp See Polyp, solitary sinonasal squamous cell carcinoma See Sinonasal squamous cell carcinoma tumor, slow-growing, sinonasal mucocele vs., IV(1):57 undifferentiated carcinoma, IV(1):106 adenocarcinoma vs., IV(1):99 adenoid cystic carcinoma vs., IV(1):107 differential diagnosis, IV(1):106 esthesioneuroblastoma vs., IV(1):95 squamous cell carcinoma vs., IV(1):91 Wegener granulomatosis See Wegener granulomatosis, sinonasal Sinonasal squamous cell carcinoma, IV(1):90, IV(1):91, IV(1):92, IV(1):93 adenocarcinoma vs., IV(1):99 adenoid cystic carcinoma vs., IV(1):107 clinical issues, IV(1):92 differential diagnosis, IV(1):91 esthesioneuroblastoma vs., IV(1):95 hard palate SCCa vs., II(2):27 imaging, IV(1):91, IV(1):93 invasive fungal sinusitis vs., IV(1):45 inverted papilloma associated with, IV(1):84 inverted papilloma vs., IV(1):83 melanoma vs., IV(1):101 non-Hodgkin lymphoma vs., IV(1):103 pathology, IV(1):91, IV(1):92 staging, grading, & classification, IV(1):92 undifferentiated carcinoma vs., IV(1):106 Sinovenous thrombosis See Dural sinus, thrombosis Sinus cholesteatoma See Pars tensa cholesteatoma Sinus histiocytosis (Rosai-Dorfman), I(13):30, I(13):31 differential diagnosis, I(13):31 skull base meningioma vs., V(1):79 Sinus infection, secondary, sinonasal Wegener granulomatosis associated with, IV(1):63 Sinus thrombosis, cavernous See Cavernous sinus thrombosis Sinusitis, fungal See Fungal sinusitis Sjögren syndrome non-Hodgkin lymphoma of pharyngeal mucosal space associated with, I(3):19 orbital lacrimal gland carcinoma vs., IV(2):83 lymphoproliferative lesions associated with, IV(2):79 lymphoproliferative lesions vs., IV(2):79 parotid See Parotid Sjögren syndrome submandibular gland sialadenitis associated with, I(14):27 Skull base, V(1):2, V(1):3, V(1):4, V(1):5, V(1):6, V(1):7, V(1):8, V(1):9, V(1):10, V(1):11, V(1):12, V(1):13, V(1):14, V(1):15, V(1):16, V(1):17, V(1):18, V(1):19, V(1):20, V(1):21, V(1):22, V(1):23, V(1):24, V(1):25, V(1):26, V(1):27, V(1):28, V(1):29, V(1):30, V(1):31, V(1):32, V(1):33, V(1):34, V(1):35, V(1):36, V(1):37, V(1):38, V(1):39, V(1):40, V(1):41, V(1):42, V(1):43, V(1):44, V(1):45, V(1):46, V(1):47, V(1):48, V(1):49, V(1):50, V(1):51, V(1):52, V(1):53, V(1):54, V(1):55, V(1):56, V(1):57, V(1):58, V(1):59, V(1):60, V(1):61, V(1):62, V(1):63, V(1):64, V(1):65, V(1):66, V(1):67, V(1):68, V(1):69, V(1):70, V(1):71, V(1):72, V(1):73, V(1):74, V(1):75, V(1):76, V(1):77, V(1):78, V(1):79, V(1):80, V(1):81, V(1):82, V(1):83, V(1):84, V(1):85, V(1):86, V(1):87, V(1):88, V(1):89, V(1):90, V(1):91, V(1):92, V(1):93, V(1):94, V(1):95 1697 See also Skull base and facial trauma cavernous sinus thrombosis, V(1):48, V(1):49 as complication of rhinosinusitis, IV(1):38 differential diagnosis, V(1):49 central solitary mass, metastasis vs., V(1):89 cephalocele, V(1):54, V(1):55, V(1):56, V(1):57 differential diagnosis, V(1):55 persistent craniopharyngeal canal vs., V(1):17 staging, grading, & classification, V(1):55, V(1):56 cerebrospinal fluid leak, V(1):58, V(1):59 differential diagnosis, V(1):59 skull base trauma associated with, V(2):12 chondrosarcoma See Chondrosarcoma, skull base chordoma See Chordoma defect, without CSF leak, CSF leak vs., V(1):59 dehiscent jugular bulb See Jugular bulb, dehiscent differential diagnosis, V(1):3 P.xlvii dural arteriovenous fistula See Dural arteriovenous fistula dural sinus and aberrant arachnoid granulations, V(1):40, V(1):41, V(1):42, V(1):43 differential diagnosis, V(1):41 dural sinus thrombosis vs., V(1):46 dural sinus hypoplasia-aplasia dural arteriovenous fistula vs., V(1):51 dural sinus and aberrant arachnoid granulations vs., V(1):41 dural sinus thrombosis vs., V(1):46 dural sinus thrombosis, V(1):44, V(1):45, V(1):46, V(1):47 differential diagnosis, V(1):46 dural arteriovenous fistula vs., V(1):51 dural sinus and aberrant arachnoid granulations vs., V(1):41 ecchordosis physaliphora, V(1):8, V(1):9 embryology, V(1):2, V(1):3 fibrous dysplasia See Fibrous dysplasia, skull base foramina/fissures and contents, V(1):2 giant cell tumor, V(1):76, V(1):77 differential diagnosis, V(1):77 fibrous dysplasia vs., V(1):61 temporal bone fibrous dysplasia vs., VI(7):6, VI(7):7 glomus jugulare paraganglioma See Glomus jugulare paraganglioma high jugular bulb See Jugular bulb, high hypoglossal nerve schwannoma, V(1):20, V(1):21 Diagnostic Imaging Head and Neck idiopathic inflammatory pseudotumor, V(1):72, V(1):73, V(1):74, V(1):75 CPA-IAC meningioma vs., VI(8):31 differential diagnosis, V(1):73 metastasis vs., V(1):89 images, V(1):4, V(1):5, V(1):6, V(1):7 imaging anatomy, V(1):2 approaches and indications, V(1):2 approaches to imaging issues, V(1):3 invasive pituitary macroadenoma See Pituitary macroadenoma, invasive jugular bulb diverticulum, V(1):28, V(1):29 dehiscent jugular bulb vs., V(1):27 differential diagnosis, V(1):29 high jugular bulb vs., V(1):25 jugular bulb pseudolesion, V(1):22, V(1):23 differential diagnosis, V(1):22, V(1):23 high jugular bulb vs., V(1):25 jugular bulb diverticulum vs., V(1):29 jugular foramen See Jugular foramen Langerhans cell histiocytosis, V(1):66, V(1):67, V(1):68, V(1):69 meningioma See Skull base meningioma metastasis See Skull base metastasis multiple myeloma, V(1):86, V(1):87 differential diagnosis, V(1):87 metastases vs., V(1):89 plasmacytoma vs., V(1):83 staging, grading, & classification, V(1):87 normal marrow around foramen ovale, perineural CNV3 tumor of masticator space vs., I(4):21, I(4):22 osteopetrosis, V(1):70, V(1):71 differential diagnosis, V(1):71 Paget disease vs., V(1):65 osteosarcoma, V(1):94, V(1):95 overview, V(1):2, V(1):3, V(1):4, V(1):5, V(1):6, V(1):7 Paget disease See Paget disease, skull base persistent craniopharyngeal canal, V(1):16, V(1):17 plasmacytoma See Plasmacytoma, skull base sphenoid benign fatty lesion, V(1):18 trigeminal schwannoma central skull base, V(1):19 hemangiopericytoma vs., I(13):11 meningioma vs., V(1):79 Skull base and facial trauma, V(2):2, V(2):3, V(2):4, V(2):5, V(2):6, V(2):7, V(2):8, V(2):9, V(2):10, V(2):11, V(2):12, V(2):13, V(2):14, V(2):15, V(2):16, V(2):17, V(2):18, V(2):19, V(2):20, V(2):21, V(2):22, V(2):23, V(2):24, V(2):25, V(2):26, V(2):27, V(2):28, V(2):29 clinical implications, V(2):3 complex facial fracture, V(2):24 differential diagnosis, V(2):24 trans-facial (Le Fort) fracture vs., V(2):19 complications, V(2):3 images, V(2):4, V(2):5 imaging approaches and indications, V(2):2 approaches to imaging issues, V(2):2, V(2):3 mandible fracture, V(2):26, V(2):27 midfacial fracture, complex naso-orbital-ethmoidal fracture vs., V(2):25 overview, V(2):3 zygomaticomaxillary complex fracture vs., V(2):23 naso-orbital-ethmoidal fracture, V(2):25 complex facial fracture vs., V(2):24 differential diagnosis, V(2):25 orbital blowout fracture vs., V(2):17 overview, V(2):3 trans-facial (Le Fort) fracture vs., V(2):19 orbital blowout fracture, V(2):16, V(2):17 differential diagnosis, V(2):17 inferior, zygomaticomaxillary complex fracture vs., V(2):23 medial, naso-orbital-ethmoidal fracture vs., V(2):25 orbital foreign body, V(2):14, V(2):15 overview, V(2):2, V(2):3, V(2):4, V(2):5 skull base trauma, V(2):10, V(2):11, V(2):12, V(2):13 clinical issues, V(2):12 differential diagnosis, V(2):11, V(2):12 imaging, V(2):11 pathology, V(2):12 staging, grading, & classification, V(2):12 temporal bone trauma, V(2):6, V(2):7, V(2):8, V(2):9 temporomandibular joint dislocation, V(2):28, V(2):29 trans-facial fracture (Le Fort), V(2):18, V(2):19, V(2):20, V(2):21 P.xlviii complex facial fracture vs., V(2):24 differential diagnosis, V(2):19 overview, V(2):2 zygomaticomaxillary complex fracture vs., V(2):23 zygomaticomaxillary complex fracture, V(2):22, V(2):23 complex facial fracture vs., V(2):24 differential diagnosis, V(2):23 orbital blowout fracture vs., V(2):17 overview, V(2):3 staging, grading, & classification, V(2):23 trans-facial (Le Fort) fracture vs., V(2):19 Skull base meningioma, V(1):78, V(1):79, V(1):80, V(1):81 1698 anterior, esthesioneuroblastoma vs., IV(1):95 chondrosarcoma vs., IV(1):108, V(1):91 chordoma vs., V(1):13 clinical issues, V(1):80 differential diagnosis, V(1):79 fibrous dysplasia vs., V(1):61 hemangiopericytoma vs., I(13):11 imaging, V(1):79, V(1):81 invasive pituitary macroadenoma vs., V(1):11 osteosarcoma vs., V(1):95 pathology, V(1):80 perineural CNV3 tumor of masticator space vs., I(4):21, I(4):22 perineural tumor spread vs., II(2):43 sinus histiocytosis vs., I(13):31 skull base metastasis vs., V(1):89 staging, grading, & classification, V(1):80 trigeminal schwannoma of central skull base vs., V(1):19 Skull base metastasis, V(1):88, V(1):89 chondrosarcoma vs., V(1):91 chordoma vs., V(1):13 differential diagnosis, V(1):89 ecchordosis physaliphora vs., V(1):9 fibrous dysplasia vs., V(1):61 hemangiopericytoma vs., I(13):11 hypoglossal nerve schwannoma vs., V(1):21 invasive pituitary macroadenoma vs., V(1):11 jugular foramen schwannoma vs., V(1):35 meningioma vs., V(1):79 multiple myeloma vs., V(1):87 osteosarcoma vs., V(1):95 Paget disease vs., V(1):65 plasmacytoma vs., V(1):83 skull base idiopathic inflammatory pseudotumor vs., V(1):73 SMMCI syndrome, congenital nasal pyriform aperture stenosis associated with, IV(1):27 Solitary bone cyst See Bone cyst, simple (traumatic) Solitary median maxillary central incisor, I(15):8, I(15):9 Solitary sinonasal polyp See Polyp, solitary sinonasal Spasm, hemifacial, VI(8):42, VI(8):43 Sphenoid benign fatty lesion, V(1):18 Sphenoid dysplasia, orbital neurofibromatosis type vs., IV(2):19 Sphenooccipital synchondrosis, craniopharyngeal canal vs., V(1):17 Spinal accessory node non-Hodgkin lymphoma, I(9):10, I(9):11 differential diagnosis, I(9):11 posterior cervical space schwannoma vs., I(9):5 staging, grading, & classification, I(9):11 reactive, posterior cervical space schwannoma vs., I(9):5 squamous cell carcinoma, I(9):8, I(9):9 Diagnostic Imaging Head and Neck differential diagnosis, I(9):9 nodal non-Hodgkin lymphoma vs., I(9):11 posterior cervical space schwannoma vs., I(9):5 suppurative non-Hodgkin lymphoma vs., I(9):11 posterior cervical space schwannoma vs., I(9):5 squamous cell carcinoma vs., I(9):9 Spondyloepiphyseal dysplasia, mucopolysaccharidosis vs., III(2):25 Squamous cell carcinoma AJCC grading all other sites, II(1):4 nasopharyngeal SCC, II(1):4, II(2):4 alveolar ridge, II(2):22, II(2):23 differential diagnosis, II(2):23 osteoradionecrosis of mandible-maxilla vs., I(15):41 staging, grading, & classification, II(2):23 buccal mucosa, II(2):26 differential diagnosis, II(2):26 retromolar trigone SCCa vs., II(2):25 cervical esophageal, I(10):36, I(10):37 differential diagnosis, I(10):37 post-cricoid region SCCa vs., II(2):32 posterior hypopharyngeal wall SCCa vs., II(2):33 clinical implications, II(1):4 external auditory canal, VI(2):20, VI(2):21 cholesteatoma vs., VI(2):15 differential diagnosis, VI(2):21 keratosis obturans vs., VI(2):9 medial canal fibrosis vs., VI(2):11 necrotizing external otitis vs., VI(2):7 staging, grading, & classification, VI(2):21 extranodal tumor, acute idiopathic carotidynia vs., I(6):17 floor of mouth, II(2):20, II(2):21 differential diagnosis, II(2):21 staging, grading, & classification, II(2):21 sublingual gland carcinoma vs., I(14):37 P.xlix glottic laryngeal, II(2):38, II(2):39 differential diagnosis, II(2):39 staging, grading, & classification, II(2):39 subglottic laryngeal SCCa vs., II(2):41 vocal cord paralysis vs., I(11):29 hard palate, II(2):27 differential diagnosis, II(2):27 palate benign mixed tumor vs., I(14):35 HPV-related oropharyngeal SCCa, II(2):15 hypopharyngeal See Hypopharyngeal squamous cell carcinoma images, II(1):5, II(1):6, II(1):7 imaging anatomy, II(1):2 approaches and indications, II(1):2 approaches to imaging issues, II(1):3 lingual tonsil See Lingual tonsil squamous cell carcinoma masticator space benign masticator muscle hypertrophy vs., I(4):9 invasive, sarcoma vs., I(4):29 nodal, II(2):46, II(2):47, II(2):48, II(2):49 clinical issues, II(2):48 differential diagnosis, II(2):47 imaging, II(2):47, II(2):49 jugular vein thrombosis vs., I(6):20 nodal differentiated thyroid carcinoma vs., I(12):37 nodal Hodgkin lymphoma in neck vs., I(12):33 oral cavity dermoid and epidermoid vs., I(14):13 pathology, II(2):47, II(2):48 prominent thoracic duct vs., I(13):5 reactive adenopathy of retropharyngeal space vs., I(7):7 reactive lymph nodes vs., I(12):7 retropharyngeal space See Retropharyngeal space, nodal squamous cell carcinoma spinal accessory node non-Hodgkin lymphoma vs., I(9):11 posterior cervical space schwannoma vs., I(9):5 staging, grading, & classification, II(2):48 submandibular gland sialadenitis vs., I(14):27 submandibular space, I(14):44, I(14):45 benign mixed tumor vs., I(14):33 differential diagnosis, I(14):45 nodal non-Hodgkin lymphoma vs., I(14):43 submandibular gland carcinoma vs., I(14):39 suppurative lymph nodes vs., I(12):11 systemic nodal metastases in neck vs., I(12):39 oral tongue, II(2):16, II(2):17, II(2):18, II(2):19 abscess vs., I(14):30 differential diagnosis, II(2):17 hypoglossal nerve motor denervation vs., I(14):9 staging, grading, & classification, II(2):17, II(2):18 overview, II(1):2, II(1):3, II(1):4, II(1):5, II(1):6, II(1):7 palatine tonsil See Palatine tonsil squamous cell carcinoma perineural tumor spread, II(2):42, II(2):43, II(2):44, II(2):45 differential diagnosis, II(2):43 staging, grading, & classification, II(2):44 pharyngeal mucosal space benign mixed tumor of pharyngeal mucosal space vs., I(3):15 1699 minor salivary gland malignancy vs., I(3):17 post-cricoid region, II(2):32 differential diagnosis, II(2):32 posterior hypopharyngeal wall SCCa vs., II(2):33 posterior oropharyngeal wall, II(2):14 post-treatment, II(3):2, II(3):3, II(3):4, II(3):5, II(3):6, II(3):7 complications of neck radiation therapy, II(3):7 expected changes of neck radiation therapy, II(3):6 nodal dissection in neck, II(3):2, II(3):3 reconstruction flaps in neck, II(3):4, II(3):5 pyriform sinus, II(2):28, II(2):29, II(2):30, II(2):31 differential diagnosis, II(2):29 staging, grading, & classification, II(2):29, II(2):30 recurrent imaging issues, II(1):3 in resection cavity, reconstruction flaps in neck vs., II(3):5 retromolar trigone, II(2):24, II(2):25 sinonasal See Sinonasal squamous cell carcinoma sites and subsites, II(1):4 spinal accessory node, I(9):8, I(9):9 differential diagnosis, I(9):9 nodal non-Hodgkin lymphoma vs., I(9):11 posterior cervical space schwannoma vs., I(9):5 staging, II(1):3 subglottic laryngeal, II(2):40, II(2):41 supraglottic laryngeal, II(2):34, II(2):35, II(2):36, II(2):37 differential diagnosis, II(2):35 staging, grading, & classification, II(2):36 supraglottitis vs., I(11):11 transglottic, post-radiation larynx vs., I(11):23 treatment, II(1):3 Squamous cell papilloma See Papilloma, inverted Stabilizing ligaments, calcified, congenital ossicular fixation vs., VI(3):7 Stapedial artery, persistent, VI(3):16, VI(3):17 aberrant internal carotid artery associated with, VI(3):14 P.l differential diagnosis, VI(3):17 middle ear prolapsing facial nerve vs., VI(6):5 Stapes prosthesis, VI(3):61 Staphyloma, coloboma vs., IV(2):6 Sternocleidomastoid tumor of infancy See Fibromatosis colli Stickler and related syndromes, Pierre Robin sequence vs., III(2):21 Diagnostic Imaging Head and Neck Sturge-Weber syndrome, PHACES association vs., III(2):11 Subacute labyrinthitis See Labyrinthitis Subarachnoid cyst, CPA See Arachnoid cyst, CPA Subarachnoid hemorrhage, recurrent, superficial siderosis associated with, VI(8):47 Subarcuate canaliculus, VI(4):2, VI(4):3 Subclavian artery aneurysm, posterior cervical space schwannoma vs., I(9):5 Subdural empyema, as complications of rhinosinusitis, IV(1):38 Subglottic infantile hemangioma, acquired subglottic-tracheal stenosis vs., I(11):33 Subglottic laryngeal squamous cell carcinoma, II(2):40, II(2):41 Subglottic-tracheal stenosis acquired, I(11):32, I(11):33, I(11):34, I(11):35 clinical issues, I(11):34 differential diagnosis, I(11):33 imaging, I(11):33, I(11):35 pathology, I(11):33, I(11):34 congenital acquired subglottic-tracheal stenosis vs., I(11):33 upper airway infantile hemangioma vs., I(11):17 iatrogenic, upper airway infantile hemangioma vs., I(11):17 Sublingual gland carcinoma, I(14):36, I(14):37 differential diagnosis, I(14):37 staging, grading, & classification, I(14):37 Sublingual space abscess See Oral cavity, abscess epidermoid, sialocele vs., I(14):25 sialocele See Sialocele Submandibular duct sialocele See Sialocele Submandibular gland benign mixed tumor, I(14):32, I(14):33 differential diagnosis, I(14):33 submandibular gland carcinoma vs., I(14):39 submandibular gland sialadenitis vs., I(14):27 carcinoma, I(14):38, I(14):39 benign mixed tumor vs., I(14):33 differential diagnosis, I(14):39 staging, grading, & classification, I(14):39 submandibular gland sialadenitis vs., I(14):27 mucocele accessory salivary tissue vs., I(14):11 benign mixed tumor vs., I(14):33 ranula vs., I(14):21 submandibular gland carcinoma vs., I(14):39 sialadenitis, I(14):26, I(14):27 benign mixed tumor vs., I(14):33 differential diagnosis, I(14):27 submandibular gland carcinoma vs., I(14):39 Submandibular space abscess See Oral cavity, abscess accessory salivary tissue, I(14):10, I(14):11 lymphatic malformation, accessory salivary tissue vs., I(14):11 nodal non-Hodgkin lymphoma, I(14):42, I(14):43 differential diagnosis, I(14):43 nodal squamous cell carcinoma vs., I(14):45 nodal squamous cell carcinoma, I(14):44, I(14):45 benign mixed tumor vs., I(14):33 differential diagnosis, I(14):45 nodal non-Hodgkin lymphoma vs., I(14):43 submandibular gland carcinoma vs., I(14):39 Submucosal cyst, laryngocele vs., I(11):26 Subperiosteal abscess orbit, IV(2):34, IV(2):35, IV(2):36, IV(2):37 cellulitis vs., IV(2):39 clinical issues, IV(2):36 differential diagnosis, IV(2):35 pathology, IV(2):35, IV(2):36 staging, grading, & classification, IV(2):36 postseptal, IV(1):37, IV(1):38 Subperiosteal hematoma, orbital subperiosteal abscess vs., IV(2):35 Superficial siderosis, VI(8):46, VI(8):47, VI(8):48, VI(8):49 Suppurative lymph nodes See Lymph nodes, suppurative Supraglottic laryngeal squamous cell carcinoma, II(2):34, II(2):35, II(2):36, II(2):37 differential diagnosis, II(2):35 staging, grading, & classification, II(2):36 supraglottitis vs., I(11):11 Supraglottitis, I(11):11 differential diagnosis, I(11):11 post-radiation larynx vs., I(11):23 pyriform sinus squamous cell carcinoma vs., II(2):29 with abscess, laryngocele vs., I(11):26 Suprahyoid and infrahyoid neck carotid space, I(6):2, I(6):3, I(6):4, I(6):5, I(6):6, I(6):7, I(6):8, I(6):9, I(6):10, I(6):11, I(6):12, I(6):13, I(6):14, I(6):15, I(6):16, I(6):17, I(6):18, I(6):19, I(6):20, I(6):21, I(6):22, I(6):23, I(6):24, I(6):25, I(6):26, I(6):27, I(6):28, I(6):29, I(6):30, I(6):31, I(6):32, I(6):33, I(6):34, I(6):35, I(6):36, I(6):37, I(6):38, I(6):39, I(6):40, I(6):41 hypopharynx, larynx, and trachea, I(11):2, I(11):3, I(11):4, I(11):5, I(11):6, I(11):7, I(11):8, I(11):9, I(11):10, 1700 I(11):11, I(11):12, I(11):13, I(11):14, I(11):15, I(11):16, I(11):17, I(11):18, I(11):19, I(11):20, I(11):21, I(11):22, I(11):23, I(11):24, I(11):25, I(11):26, I(11):27, I(11):28, I(11):29, I(11):30, I(11):31, I(11):32, I(11):33, I(11):34, I(11):35 images fascia and spaces of infrahyoid neck, I(1):6 infrahyoid space longitudinal spatial relationships, I(1):7 oropharyngeal space, I(1):5 parapharyngeal space, I(1):4 skull base and suraphyoid neck space interaction, I(1):7 suprahyoid neck spaces, I(1):4 imaging P.li anatomy, I(1):2, I(1):3 approaches and indications, I(1):2 imaging issues, I(1):3 lymph nodes, I(12):2, I(12):3, I(12):4, I(12):5, I(12):6, I(12):7, I(12):8, I(12):9, I(12):10, I(12):11, I(12):12, I(12):13, I(12):14, I(12):15, I(12):16, I(12):17, I(12):18, I(12):19, I(12):20, I(12):21, I(12):22, I(12):23, I(12):24, I(12):25, I(12):26, I(12):27, I(12):28, I(12):29, I(12):30, I(12):31, I(12):32, I(12):33, I(12):34, I(12):35, I(12):36, I(12):37, I(12):38, I(12):39 mandible-maxilla and temporomandibular joint, I(15):2, I(15):3, I(15):4, I(15):5, I(15):6, I(15):7, I(15):8, I(15):9, I(15):10, I(15):11, I(15):12, I(15):13, I(15):14, I(15):15, I(15):16, I(15):17, I(15):18, I(15):19, I(15):20, I(15):21, I(15):22, I(15):23, I(15):24, I(15):25, I(15):26, I(15):27, I(15):28, I(15):29, I(15):30, I(15):31, I(15):32, I(15):33, I(15):34, I(15):35, I(15):36, I(15):37, I(15):38, I(15):39, I(15):40, I(15):41, I(15):42, I(15):43 masticator space, I(4):2, I(4):3, I(4):4, I(4):5, I(4):6, I(4):7, I(4):8, I(4):9, I(4):10, I(4):11, I(4):12, I(4):13, I(4):14, I(4):15, I(4):16, I(4):17, I(4):18, I(4):19, I(4):20, I(4):21, I(4):22, I(4):23, I(4):24, I(4):25, I(4):26, I(4):27, I(4):28, I(4):29, I(4):30, I(4):31 oral cavity, I(14):2, I(14):3, I(14):4, I(14):5, I(14):6, I(14):7, I(14):8, I(14):9, I(14):10, I(14):11, I(14):12, I(14):13, I(14):14, I(14):15, I(14):16, I(14):17, I(14):18, I(14):19, I(14):20, I(14):21, I(14):22, I(14):23, I(14):24, I(14):25, I(14):26, I(14):27, I(14):28, I(14):29, I(14):30, I(14):31, I(14):32, I(14):33, I(14):34, I(14):35, I(14):36, I(14):37, I(14):38, I(14):39, I(14):40, I(14):41, I(14):42, I(14):43, I(14):44, I(14):45 overview, I(1):2, I(1):3, I(1):4, I(1):5, I(1):6, I(1):7 Diagnostic Imaging Head and Neck parapharyngeal space, I(2):2, I(2):3, I(2):4, I(2):5 parotid space, I(5):2, I(5):3, I(5):4, I(5):5, I(5):6, I(5):7, I(5):8, I(5):9, I(5):10, I(5):11, I(5):12, I(5):13, I(5):14, I(5):15, I(5):16, I(5):17, I(5):18, I(5):19, I(5):20, I(5):21, I(5):22, I(5):23, I(5):24, I(5):25, I(5):26, I(5):27, I(5):28, I(5):29, I(5):30, I(5):31, I(5):32, I(5):33, I(5):34, I(5):35, I(5):36, I(5):37, I(5):38, I(5):39, I(5):40, I(5):41, I(5):42, I(5):43 perivertebral space, I(8):2, I(8):3, I(8):4, I(8):5, I(8):6, I(8):7, I(8):8, I(8):9, I(8):10, I(8):11, I(8):12, I(8):13, I(8):14, I(8):15, I(8):16, I(8):17, I(8):18, I(8):19, I(8):20, I(8):21, I(8):22, I(8):23 pharyngeal mucosal space, I(3):2, I(3):3, I(3):4, I(3):5, I(3):6, I(3):7, I(3):8, I(3):9, I(3):10, I(3):11, I(3):12, I(3):13, I(3):14, I(3):15, I(3):16, I(3):17, I(3):18, I(3):19, I(3):20, I(3):21 posterior cervical space, I(9):2, I(9):3, I(9):4, I(9):5, I(9):6, I(9):7, I(9):8, I(9):9, I(9):10, I(9):11 retropharyngeal space See Retropharyngeal space trans-spatial and multi-spatial lesions, I(13):2, I(13):3, I(13):4, I(13):5, I(13):6, I(13):7, I(13):8, I(13):9, I(13):10, I(13):11, I(13):12, I(13):13, I(13):14, I(13):15, I(13):16, I(13):17, I(13):18, I(13):19, I(13):20, I(13):21, I(13):22, I(13):23, I(13):24, I(13):25, I(13):26, I(13):27, I(13):28, I(13):29, I(13):30, I(13):31, I(13):32, I(13):33, I(13):34, I(13):35 visceral space, I(10):1, I(10):2, I(10):3, I(10):4, I(10):5, I(10):6, I(10):7, I(10):8, I(10):9, I(10):10, I(10):11, I(10):12, I(10):13, I(10):14, I(10):15, I(10):16, I(10):17, I(10):18, I(10):19, I(10):20, I(10):21, I(10):22, I(10):23, I(10):24, I(10):25, I(10):26, I(10):27, I(10):28, I(10):29, I(10):30, I(10):31, I(10):32, I(10):33, I(10):34, I(10):35, I(10):36, I(10):37, I(10):38, I(10):39, I(10):40, I(10):41 Surfer's ear See External auditory canal, exostoses (surfer's ear) Sympathetic schwannoma, I(6):36, I(6):37 differential diagnosis, I(6):37 glomus vagale paraganglioma vs., I(6):33 staging, grading, & classification, I(6):37 Synchondrosis, sphenooccipital, persistent craniopharyngeal canal vs., V(1):17 Syndromic pediatric lesions See Congenital anomalies, syndromic Synovial chondromatosis of temporomandibular joint, I(15):26, I(15):27 calcium pyrophosphate dihydrate deposition disease vs., I(15):24 differential diagnosis, I(15):27 masticator space chondrosarcoma vs., I(4):25 pigmented villonodular synovitis vs., I(15):25 TMJ dislocation vs., V(2):29 Synovial sarcoma of head and neck, I(13):24, I(13):25 Synovitis, temporomandibular joint juvenile idiopathic arthritis vs., I(15):21 pigmented villonodular, I(15):25 Systemic lupus erythematosus, histiocytic necrotizing lymphadenitis associated with, I(12):23 T Temporal bone See also CPA-IAC; External auditory canal; Facial nerve, intratemporal; Inner ear; Middle earmastoid; Petrous apex arachnoid granulations, VI(7):4, VI(7):5 cephalocele vs., VI(3):59 differential diagnosis, VI(7):5 cephalocele, VI(3):58, VI(3):59 cerebrospinal fluid leak, VI(7):2, VI(7):3 differential diagnosis, VI(1):4 embryology, VI(1):2 fibrous dysplasia, VI(7):6, VI(7):7 congenital mastoid cholesteatoma vs., VI(3):6 differential diagnosis, VI(7):7 otosclerosis vs., VI(4):41 otosyphilis vs., VI(4):35 Paget disease vs., VI(7):9 temporal bone Langerhans cell histiocytosis vs., VI(7):11 fractures overview, V(2):2 subarcuate canaliculus vs., VI(4):3 images, VI(1):5, VI(1):6, VI(1):7 imaging anatomy, VI(1):2, VI(1):3, VI(1):4 approaches to imaging issues, VI(1):4 techniques and indications, VI(1):2 internal carotid artery aneurysm, petrous apex mucocele vs., VI(5):13 Langerhans cell histiocytosis, VI(7):10, VI(7):11 acute otomastoiditis with abscess vs., VI(3):19 coalescent otomastoiditis vs., VI(3):23 congenital mastoid cholesteatoma vs., VI(3):6 differential diagnosis, VI(7):11 T-bone metastasis vs., VI(7):13 temporal bone rhabdomyosarcoma vs., VI(3):55 meningioma, VI(3):46, VI(3):47, VI(3):48, VI(3):49 differential diagnosis, VI(3):47, VI(3):48 fibrous dysplasia vs., VI(7):6, VI(7):7 metastasis, VI(7):12, VI(7):13 differential diagnosis, VI(7):13 fibrous dysplasia vs., VI(7):6, VI(7):7 osteogenesis imperfecta cochlear cleft vs., VI(4):5 1701 otosclerosis vs., VI(4):41 otosyphilis vs., VI(4):35 osteoradionecrosis, VI(7):14, VI(7):15 differential diagnosis, VI(7):15 otosclerosis vs., VI(4):41 Paget disease vs., VI(7):9 overview, VI(1):2, VI(1):3, VI(1):4, VI(1):5, VI(1):6, VI(1):7 Paget disease, VI(7):8, VI(7):9 differential diagnosis, VI(7):9 fibrous dysplasia vs., VI(7):6, VI(7):7 osteoradionecrosis vs., VI(7):15 otosclerosis vs., VI(4):41 otosyphilis vs., VI(4):35 plasmacytoma, metastasis vs., VI(7):13 post-irradiated cochlear cleft vs., VI(4):5 otosyphilis vs., VI(4):35 rhabdomyosarcoma, VI(3):54, VI(3):55, VI(3):56, VI(3):57 acute otomastoiditis with abscess vs., VI(3):19 P.lii coalescent otomastoiditis vs., VI(3):23 differential diagnosis, VI(3):55, VI(3):56 staging, grading, & classification, VI(3):56 trauma, V(2):6, V(2):7, V(2):8, V(2):9 clinical issues, V(2):8 differential diagnosis, V(2):7, V(2):8 imaging, V(2):7 pathology, V(2):8 Temporomandibular joint See also Mandible-maxilla ameloblastoma See Ameloblastoma calcium pyrophosphate dihydrate deposition disease, I(15):24 pigmented villonodular synovitis vs., I(15):25 synovial chondromatosis vs., I(15):27 common lesions, I(15):3 condylar hypoplasia, juvenile idiopathic arthritis vs., I(15):21 degenerative disease juvenile idiopathic arthritis vs., I(15):21 masticator space abscess vs., I(4):16 dislocation, V(2):28, V(2):29 images, I(15):6, I(15):7 imaging anatomy, I(15):3 juvenile idiopathic arthritis, I(15):20, I(15):21 differential diagnosis, I(15):21 staging, grading, & classification, I(15):21 keratocystic odontogenic tumor See Keratocystic odontogenic tumor overview, I(15):2, I(15):3, I(15):4, I(15):5, I(15):6, I(15):7 pigmented villonodular synovitis, I(15):25 synovial chondromatosis, I(15):26, I(15):27 calcium pyrophosphate dihydrate deposition disease vs., I(15):24 Diagnostic Imaging Head and Neck differential diagnosis, I(15):27 masticator space chondrosarcoma vs., I(4):25 pigmented villonodular synovitis vs., I(15):25 TMJ dislocation vs., V(2):29 synovitis/capsulitis, juvenile idiopathic arthritis vs., I(15):21 Teratogenic embryopathy, hemifacial microsomia vs., III(2):18 Teratoma fibromatosis colli vs., III(1):45 lipoma of head and neck vs., I(13):7 liposarcoma of head and neck vs., I(13):23 lymphatic malformation vs., III(1):7 skull base cephalocele vs., V(1):55 Thoracic duct, prominent, in neck, I(13):4, I(13):5 Thrombosis cavernous sinus, V(1):48, V(1):49 as complication of rhinosinusitis, IV(1):38 differential diagnosis, V(1):49 dural sinus, V(1):44, V(1):45, V(1):46, V(1):47 differential diagnosis, V(1):46 dural arteriovenous fistula vs., V(1):51 dural sinus and aberrant arachnoid granulations vs., V(1):41 jugular bulb thrombosis-sigmoid sinus, jugular bulb pseudolesion vs., V(1):23 jugular vein, I(6):18, I(6):19, I(6):20, I(6):21 carotid space schwannoma vs., I(6):33 differential diagnosis, I(6):19, I(6):20 glomus vagale paraganglioma vs., I(6):29 post-pharyngitis venous thrombosis (Lemierre) vs., I(6):23 post-pharyngitis venous thrombosis (Lemierre), I(6):22, I(6):23 Thymic cyst, cervical, III(1):20, III(1):21, III(1):22, III(1):23 2nd branchial cleft cyst vs., III(1):29 3rd branchial cleft cyst vs., III(1):33 4th branchial cleft cyst vs., III(1):37 clinical issues, III(1):22 differential diagnosis, III(1):21 imaging, III(1):21, III(1):23 lymphatic malformation vs., III(1):7 non-tuberculous mycobacterium vs., I(12):16 pathology, III(1):21, III(1):22 Thymopharyngeal duct cyst See Thymic cyst, cervical Thyroglossal duct cyst, III(1):16, III(1):17, III(1):18, III(1):19 4th branchial cleft cyst vs., III(1):37 clinical issues, III(1):18 colloid cyst of thyroid vs., I(10):40 congenital vallecular cyst vs., III(1):15 dermoid and epidermoid vs., I(14):13 differential diagnosis, III(1):3, III(1):17 foramen cecum benign mixed tumor of pharyngeal mucosal space vs., I(3):15 retention cyst of pharyngeal mucosal space vs., I(3):9 imaging, III(1):17, III(1):19 infrahyoid, 3rd branchial cleft cyst vs., III(1):33 laryngocele vs., I(11):25 lingual thyroid associated with, I(14):19 lymphatic malformation vs., I(14):17, III(1):7 overview, III(1):2 pathology, III(1):17, III(1):18 pediatric dermoid/epidermoid cyst vs., III(1):41 Thyroid, lingual See Lingual thyroid Thyroid adenoma, I(10):12, I(10):13, I(10):14, I(10):15 anaplastic thyroid carcinoma vs., I(10):29 clinical issues, I(10):14 colloid cyst of thyroid vs., I(10):40 differential diagnosis, I(10):13 follicular, differentiated thyroid carcinoma vs., I(10):21 imaging, I(10):13, I(10):15 medullary thyroid carcinoma vs., I(10):25 multinodular goiter vs., I(10):9 P.liii parathyroid adenoma vs., I(10):17 parathyroid carcinoma vs., I(10):35 pathology, I(10):13, I(10):14 Thyroid anomalies, thyroglossal duct cyst associated with, III(1):17 Thyroid carcinoma anaplastic, I(10):28, I(10):29, I(10):30, I(10):31 cervical esophageal carcinoma vs., I(10):37 chronic lymphocytic thyroiditis vs., I(10):7 clinical issues, I(10):30 differential diagnosis, I(10):29 differentiated thyroid carcinoma vs., I(10):21 imaging, I(10):29, I(10):31 multinodular goiter vs., I(10):10 non-Hodgkin thyroid lymphoma vs., I(10):33 pathology, I(10):29, I(10):30 staging, grading, & classification, I(10):29, I(10):30 differentiated, I(10):20, I(10):21, I(10):22, I(10):23 anaplastic thyroid carcinoma vs., I(10):29 cervical esophageal carcinoma vs., I(10):37 clinical issues, I(10):22 colloid cyst of thyroid vs., I(10):40 differential diagnosis, I(10):21 giant lymph node hyperplasia vs., I(12):19 1702 imaging, I(10):21, I(10):23 medullary thyroid carcinoma vs., I(10):25 multinodular goiter vs., I(10):9 non-Hodgkin thyroid lymphoma vs., I(10):33 parathyroid carcinoma vs., I(10):35 pathology, I(10):21, I(10):22 staging, grading, & classification, I(10):21, I(10):22 thyroid adenoma vs., I(10):13 differentiated, nodal, I(12):36, I(12):37 differential diagnosis, I(12):37 esophagopharyngeal diverticulum vs., I(10):39 lateral cervical esophageal diverticulum vs., I(10):41 nodal Hodgkin lymphoma in neck vs., I(12):33 nodal squamous cell carcinoma vs., II(2):47 prominent thoracic duct vs., I(13):5 spinal accessory node non-Hodgkin lymphoma vs., I(9):11 spinal accessory node squamous cell carcinoma vs., I(9):9 staging, grading, & classification, I(12):37 medullary, I(10):24, I(10):25, I(10):26, I(10):27 anaplastic thyroid carcinoma vs., I(10):29 clinical issues, I(10):26 differential diagnosis, I(10):25 differentiated thyroid carcinoma vs., I(10):21 glomus vagale paraganglioma associated with, VI(6):30 imaging, I(10):25, I(10):27 pathology, I(10):25, I(10):26 staging, grading, & classification, I(10):26 undifferentiated See Thyroid carcinoma, anaplastic Thyroid cyst, colloid, I(10):40 4th branchial cleft cyst vs., III(1):37 cervical thymic cyst vs., III(1):21 differential diagnosis, I(10):40 differentiated thyroid carcinoma vs., I(10):21 multinodular goiter vs., I(10):9 thyroid adenoma vs., I(10):13 Thyroid cyst, simple, colloid cyst of thyroid vs., I(10):40 Thyroid lymphoma, non-Hodgkin, I(10):32, I(10):33 anaplastic thyroid carcinoma vs., I(10):29 cervical esophageal carcinoma vs., I(10):37 chronic lymphocytic thyroiditis vs., I(10):7 differential diagnosis, I(10):33 differentiated thyroid carcinoma vs., I(10):21 Diagnostic Imaging Head and Neck medullary thyroid carcinoma vs., I(10):25 multinodular goiter vs., I(10):10 staging, grading, & classification, I(10):33 Thyroid malignancy, increased risk associated with glomus jugulare paraganglioma, V(1):32 Thyroid neuroendocrine carcinoma See Thyroid carcinoma, medullary Thyroid ophthalmopathy, IV(2):46, IV(2):47, IV(2):48, IV(2):49 clinical issues, IV(2):48 differential diagnosis, IV(2):47 imaging, IV(2):47, IV(2):49 orbital idiopathic inflammatory pseudotumor vs., IV(2):41 orbital lymphoproliferative lesions vs., IV(2):79 orbital sarcoidosis vs., IV(2):45 pathology, IV(2):48 staging, grading, & classification, IV(2):48 Thyroiditis chronic lymphocytic (Hashimoto), I(10):6, I(10):7 differential diagnosis, I(10):7 non-Hodgkin lymphoma of pharyngeal mucosal space associated with, I(3):19 non-Hodgkin lymphoma of thyroid vs., I(10):33 invasive fibrous (Riedel), chronic lymphocytic thyroiditis vs., I(10):7 Tic douloureux See Trigeminal neuralgia Tobacco and alcohol abuse alveolar ridge SSCa associated with, II(2):23 floor of mouth SCCa associated with, II(2):21 glottic laryngeal SCCa associated with, II(2):39 lingual tonsil SCCa associated with, II(2):7 oral tongue SCCa associated with, II(2):17 palatine tonsil SCCa associated with, II(2):11 pyriform sinus SCCa associated with, II(2):23 subglottic laryngeal SCCa associated with, II(2):41 supraglottic laryngeal SCCa associated with, II(2):36 Tolosa-Hunt syndrome See also Pseudotumor, idiopathic inflammatory, skull base P.liv cavernous sinus thrombosis vs., V(1):49 Tongue, oral See also Lingual entries abscess See Oral cavity, abscess alveolar soft part sarcoma, squamous cell carcinoma vs., II(2):17 denervation See Hypoglossal nerve, motor denervation schwannoma, squamous cell carcinoma vs., II(2):17 squamous cell carcinoma, II(2):16, II(2):17, II(2):18, II(2):19 abscess vs., I(14):30 clinical issues, II(2):18 differential diagnosis, II(2):17 hypoglossal nerve motor denervation vs., I(14):9 imaging, II(2):17, II(2):19 pathology, II(2):17, II(2):18 staging, grading, & classification, II(2):17, II(2):18 venous malformation, squamous cell carcinoma vs., II(2):17 Tonsil, lingual See Lingual tonsil Tonsillar cyst See Retention cyst, pharyngeal mucosal space Tonsillar inflammation, I(3):10, I(3):11 differential diagnosis, I(3):11 post-transplantation lymphoproliferative disorder vs., I(13):15 Tonsillar lymphoid hyperplasia Non-Hodgkin lymphoma vs., I(3):19 palatine tonsil squamous cell carcinoma vs., II(2):11 Tonsillar/peritonsillar abscess, I(3):12, I(3):13 differential diagnosis, I(3):13 palatine tonsil squamous cell carcinoma vs., II(2):11 post-transplantation lymphoproliferative disorder vs., I(13):15 tonsillar inflammation vs., I(3):11 Tonsillar/peritonsillar cellulitis/phlegmon See Tonsillar inflammation Tonsillar tissue, prominent/asymmetric lingual thyroid vs., I(14):19 tonsillar inflammation vs., I(3):11 tonsillar/peritonsillar abscess vs., I(3):13 Tonsillitis/tonsillopharyngitis See Tonsillar inflammation Tooth anomalies, congenital nasal pyriform aperture stenosis associated with, IV(1):27 Tornwaldt cyst, I(3):6, I(3):7 differential diagnosis, I(3):7 extraosseous chordoma vs., I(13):17 retention cyst of pharyngeal mucosal space vs., I(3):9 Toxocariasis, ocular, IV(2):32, IV(2):33 Coats disease vs., IV(2):13 differential diagnosis, IV(2):33 retinoblastoma vs., IV(2):71 Trachea See also Hypopharynx; Larynx clinical issues, I(11):3 croup, I(11):8, I(11):9 differential diagnosis, I(11):9 epiglottitis in child vs., I(11):10 1703 upper airway infantile hemangioma vs., I(11):17 differential diagnosis, I(11):3 diverticulum, esophagopharyngeal diverticulum vs., I(10):39 embryology, I(11):2 foreign body, croup vs., I(11):9 images, I(11):4, I(11):5, I(11):6, I(11):7 imaging anatomy, I(11):2, I(11):3 approaches to imaging issues, I(11):3 techniques and indications, I(11):2 overview, I(11):2, I(11):3, I(11):4, I(11):5, I(11):6, I(11):7 stenosis See Subglottic-tracheal stenosis upper airway infantile hemangioma, I(11):16, I(11):17 Tracheitis, exudative croup vs., I(11):9 epiglottitis in child vs., I(11):10 upper airway infantile hemangioma vs., I(11):17 Tracheomalacia, upper airway infantile hemangioma vs., I(11):17 Tracheopathia osteochondroplastica, laryngeal chondrosarcoma vs., I(11):19 Trans-facial fracture (Le Fort), V(2):18, V(2):19, V(2):20, V(2):21 clinical issues, V(2):19 complex facial fracture vs., V(2):24 differential diagnosis, V(2):19 imaging, V(2):19, V(2):20, V(2):21 overview, V(2):2 zygomaticomaxillary complex fracture vs., V(2):23 Transitional carcinoma See Sinonasal squamous cell carcinoma Transitional cell papilloma See Papilloma, inverted Trans-spatial and multi-spatial lesions, I(13):2, I(13):3, I(13):4, I(13):5, I(13):6, I(13):7, I(13):8, I(13):9, I(13):10, I(13):11, I(13):12, I(13):13, I(13):14, I(13):15, I(13):16, I(13):17, I(13):18, I(13):19, I(13):20, I(13):21, I(13):22, I(13):23, I(13):24, I(13):25, I(13):26, I(13):27, I(13):28, I(13):29, I(13):30, I(13):31, I(13):32, I(13):33, I(13):34, I(13):35 approaches to imaging, I(13):2 extraosseous chordoma, I(13):16, I(13):17 fibromatosis of head and neck See Fibromatosis of head and neck hemangiopericytoma of head and neck See Hemangiopericytoma of head and neck images, I(13):2 lipoma of head and neck, I(13):6, I(13):7, I(13):8, I(13):9 liposarcoma of head and neck, I(13):22, I(13):23 lymphocele of neck, I(13):28, I(13):29 differential diagnosis, I(13):29 prominent thoracic duct vs., I(13):5 Diagnostic Imaging Head and Neck staging, grading, & classification, I(13):29 malignant peripheral nerve sheath tumor, I(13):26, I(13):27 brachial plexus schwannoma in perivertebral space vs., I(8):17 P.lv differential diagnosis, I(13):27 pathology, I(13):27, III(2):4 synovial sarcoma of head and neck vs., I(13):25 multi-spatial diseases, I(13):2 non-Hodgkin lymphoma of head and neck, I(13):18, I(13):19, I(13):20, I(13):21 overview, I(13):2, I(13):3 plexiform neurofibroma of head and neck See Neurofibroma, plexiform post-transplantation lymphoproliferative disorder, I(13):14, I(13):15 differential diagnosis, I(13):15 non-Hodgkin lymphoma of pharyngeal mucosal space associated with, I(3):19 staging, grading, & classification, I(13):15 prominent thoracic duct in neck, I(13):4, I(13):5 sinus histiocytosis (Rosai-Dorfman), I(13):30, I(13):31 differential diagnosis, I(13):31 skull base meningioma vs., V(1):79 synovial sarcoma of head and neck, I(13):24, I(13):25 trans-spatial diseases, I(13):2 Transsphenoidal craniopharyngeal canal See Craniopharyngeal canal, persistent Transverse-sigmoid sinus pseudolesion, dural sinus and aberrant arachnoid granulations vs., V(1):41 Trapped fluid See Petrous apex, trapped fluid Traumatic bone cyst See Bone cyst, simple (traumatic) Treacher Collins syndrome, III(2):19 differential diagnosis, III(2):19 Pierre Robin sequence vs., III(2):21 Trigeminal nerve, mandibular branch See CNV3 Trigeminal neuralgia, VI(8):40, VI(8):41 Trigeminal schwannoma intracranial, CPA-IAC meningioma vs., VI(8):31 skull base central, V(1):19 hemangiopericytoma vs., I(13):11 meningioma vs., V(1):79 Trochlear apparatus calcification, orbital foreign body vs., V(2):15 Tuberculosis, nodal, nodal differentiated thyroid carcinoma vs., I(12):37 Tuberculous lymph nodes, I(12):14, I(12):15 differential diagnosis, I(12):15 histiocytic necrotizing lymphadenitis (Kikuchi) vs., I(12):23 nodal non-Hodgkin lymphoma in neck vs., I(12):29 non-tuberculous mycobacterium vs., I(12):16 reactive lymph nodes vs., I(12):7 sinus histiocytosis vs., I(13):31 submandibular space nodal nonHodgkin lymphoma vs., I(14):43 suppurative lymph nodes vs., I(12):11 Tympanosclerosis congenital external ear dysplasia vs., VI(2):3 in chronic otomastoiditis, VI(3):26, VI(3):27 involving ossicles, congenital ossicular fixation vs., VI(3):7 oval window atresia vs., VI(3):9 U Upper airway infantile hemangioma, I(11):16, I(11):17 differential diagnosis, I(11):17 lingual thyroid vs., I(14):19 staging, grading, & classification, I(11):17 Uveal melanoma See Ocular melanoma V VACTERL syndrome CHARGE syndrome of inner ear vs., VI(4):29 solitary median maxillary central incisor related to, I(15):9 Vagal body tumor See Glomus vagale paraganglioma Vagal neuropathy, I(6):3 Vagale chemodectoma See Glomus vagale paraganglioma Vallecular cyst, congenital, III(1):14, III(1):15 differential diagnosis, III(1):15 laryngocele vs., I(11):25 retention cyst of pharyngeal mucosal space vs., I(3):9 Varix See Venous varix, orbital Vasa nervosa CNV3, perineural CNV3 tumor of masticator space vs., I(4):21, I(4):22 Vascular malformations See also Lymphatic malformation; Venous malformation differential diagnosis, III(1):3 encapsulated See Cavernous hemangioma, orbital intracranial, orbital lymphatic malformation associated with, IV(2):24 pathologic issues in orbit, IV(2):3 1704 Vascular rings and slings, acquired subglottic-tracheal stenosis vs., I(11):33 Vasculitis, miscellaneous acute idiopathic carotidynia vs., I(6):17 vertebral artery dissection in neck vs., I(8):15 Vasomotor rhinitis, skull base CSF leak vs., V(1):59 Velocardiofacial syndrome Pierre Robin sequence vs., III(2):21 solitary median maxillary central incisor related to, I(15):9 tortuous carotid artery associated with, I(6):7 Venolymphatic malformation See Lymphatic malformation Venous angioma, posterior fossa hemifacial spasm vs., VI(8):43 P.lvi trigeminal neuralgia vs., VI(8):41 Venous malformation, III(1):10, III(1):11, III(1):12, III(1):13 clinical issues, III(1):12 differential diagnosis, III(1):3, III(1):11, III(1):12 facial nerve See Facial nerve, intratemporal, venous malformation (hemangioma) imaging, III(1):11, III(1):13 infantile hemangioma vs., III(1):47 internal auditory canal, VI(8):18, VI(8):19 lingual thyroid vs., I(14):19 lymphatic malformation associated with, III(1):8 masticator space, sarcoma vs., I(4):29 neurofibromatosis type vs., III(2):3 oral cavity, hypoglossal nerve motor denervation vs., I(14):9 orbital infantile hemangioma vs., IV(2):57 pediatric dermoid/epidermoid cyst vs., III(1):42 pathology, III(1):12 plexiform neurofibroma vs., I(13):13 posterior oropharyngeal wall SCCa vs., II(2):14 tongue, squamous cell carcinoma vs., II(2):17 venous malformation associated with, III(1):12 Venous plexus asymmetry, pterygoid See Pterygoid venous plexus asymmetry Venous thrombosis, post-pharyngitis (Lemierre), I(6):22, I(6):23 Venous varix, orbital, IV(2):26, IV(2):27 cavernous hemangioma vs., IV(2):29 differential diagnosis, IV(2):27 and dural AV fistula, CPA-IAC aneurysm vs., VI(8):45 lymphatic malformation vs., IV(2):23 Diagnostic Imaging Head and Neck Venous vascular malformation, pterygoid venous plexus asymmetry vs., I(4):7 Ventricular appendix See Larynx, saccule Vertebral artery dissection in neck, I(8):14, I(8):15 Vertebral body metastasis, perivertebral space, I(8):20, I(8):21, I(8):22, I(8):23 chordoma in perivertebral space vs., I(8):19 clinical issues, I(8):22 differential diagnosis, I(8):21 imaging, I(8):21, I(8):23 infection vs., I(8):12 pathology, I(8):21, I(8):22 staging, grading, & classification, I(8):22 Vertebrobasilar artery dissection, skull base trauma associated with, V(2):12 Vertebrobasilar dolichoectasia, CPA-IAC aneurysm vs., VI(8):45 Vestibular aqueduct (IP-II), large, VI(4):14, VI(4):15, VI(4):16, VI(4):17 clinical issues, VI(4):16 cochlear hypoplasia vs., VI(4):23 cochlear implantation considerations, VI(4):56 cochlear incomplete partition type vs., VI(4):13 differential diagnosis, VI(4):15 globular vestibule-semicircular canal vs., VI(4):26 imaging, VI(4):15, VI(4):17 pathology, VI(4):15, VI(4):16 subarcuate canaliculus vs., VI(4):3 temporal bone arachnoid granulations vs., VI(7):5 X-linked stapes gusher vs., VI(4):19 Vestibular schwannoma, VI(8):26, VI(8):27, VI(8):28, VI(8):29 bilateral, CPA-IAC metastases vs., VI(8):37 clinical issues, VI(8):28 CPA arachnoid cyst associated with, VI(8):12 CPA-IAC meningioma vs., VI(8):31 cystic, arachnoid cyst of CPA vs., VI(8):11 differential diagnosis, VI(8):27 facial nerve schwannoma vs., VI(8):35 hemorrhagic, congenital CPA-IAC lipoma vs., VI(8):15 imaging, VI(8):27, VI(8):29 internal auditory canal venous malformation vs., VI(8):19 intralabyrinthine hemorrhage vs., VI(4):51 pathology, VI(8):27, VI(8):28 staging, grading, & classification, VI(8):27 Virchow node, I(12):3 Visceral space, I(10):1, I(10):2, I(10):3, I(10):4, I(10):5, I(10):6, I(10):7, I(10):8, I(10):9, I(10):10, I(10):11, I(10):12, I(10):13, I(10):14, I(10):15, I(10):16, I(10):17, I(10):18, I(10):19, I(10):20, I(10):21, I(10):22, I(10):23, I(10):24, I(10):25, I(10):26, I(10):27, I(10):28, I(10):29, I(10):30, I(10):31, I(10):32, I(10):33, I(10):34, I(10):35, I(10):36, I(10):37, I(10):38, I(10):39, I(10):40, I(10):41 anaplastic thyroid carcinoma See Thyroid carcinoma, anaplastic cervical esophageal carcinoma, I(10):36, I(10):37 differential diagnosis, I(10):37 post-cricoid region SCCa vs., II(2):32 posterior hypopharyngeal wall SCCa vs., II(2):33 chronic lymphocytic thyroiditis (Hashimoto), I(10):6, I(10):7 differential diagnosis, I(10):7 non-Hodgkin lymphoma of pharyngeal mucosal space associated with, I(3):19 non-Hodgkin thyroid lymphoma vs., I(10):33 clinical issues, I(10):3 colloid cyst of thyroid See Thyroid cyst, colloid differential diagnosis, I(10):3 differentiated thyroid carcinoma See Thyroid carcinoma, differentiated esophagopharyngeal diverticulum (Zenker), I(10):38, I(10):39 differential diagnosis, I(10):39 lateral cervical esophageal diverticulum vs., I(10):41 staging, grading, & classification, I(10):39 images, I(10):4, I(10):5 imaging anatomy, I(10):2 approaches to imaging issues, I(10):2, I(10):3 techniques and indications, I(10):2 lateral cervical esophageal diverticulum, I(10):41 medullary thyroid carcinoma See Thyroid carcinoma, medullary multinodular goiter See Goiter, multinodular non-Hodgkin lymphoma of thyroid See Thyroid lymphoma, non-Hodgkin overview, I(10):2, I(10):3, I(10):4, I(10):5 parathyroid adenoma differential diagnosis, I(10):17 parathyroid carcinoma vs., I(10):35 thyroid adenoma vs., I(10):13 parathyroid carcinoma, I(10):34, I(10):35 differential diagnosis, I(10):35 parathyroid adenoma vs., I(10):17 staging, grading, & classification, I(10):35 thyroid adenoma See Thyroid adenoma Vitreous, persistent hyperplastic primary, IV(2):10, IV(2):11 Coats disease vs., IV(2):13 1705 coloboma associated with, IV(2):8 differential diagnosis, IV(2):11 ocular toxocariasis vs., IV(2):33 retinoblastoma vs., IV(2):71 Vocal cord paralysis, I(11):28, I(11):29, I(11):30, I(11):31 clinical issues, I(11):30 differential diagnosis, I(11):29 imaging, I(11):29, I(11):31 laryngeal trauma vs., I(11):13 pathology, I(11):29, I(11):30 pyriform sinus squamous cell carcinoma vs., II(2):29 Vocal cords, false See Laryngeal squamous cell carcinoma, supraglottic von Hippel Lindau syndrome carotid body paraganglioma associated with, VI(6):26 endolymphatic sac tumor associated with, VI(4):49 von Recklinghausen disease See Neurofibromatosis type W Warthin tumor, parotid space, I(5):22, I(5):23, I(5):24, I(5):25 adenoid cystic carcinoma vs., I(5):33 benign lymphoepithelial lesions-HIV vs., I(5):15 benign mixed tumor of parotid space vs., I(5):19 clinical issues, I(5):24 differential diagnosis, I(5):23 imaging, I(5):23, I(5):25 malignant mixed tumor vs., I(5):35 mucoepidermoid carcinoma vs., I(5):29 non-Hodgkin lymphoma vs., I(5):37 parotid nodal metastatic disease vs., I(5):41 parotid Sjögren syndrome vs., I(5):12 pathology, I(5):24 schwannoma vs., I(5):27 Wegener granulomatosis cavernous sinus thrombosis vs., V(1):49 orbital idiopathic inflammatory pseudotumor vs., IV(2):41 lacrimal gland carcinoma vs., IV(2):83 sarcoidosis vs., IV(2):45 sinonasal, IV(1):62, IV(1):63, IV(1):64, IV(1):65 chronic rhinosinusitis vs., IV(1):33 clinical issues, IV(1):64 differential diagnosis, IV(1):63 imaging, IV(1):63, IV(1):65 invasive fungal sinusitis vs., IV(1):45 nasal cocaine necrosis vs., IV(1):67 non-Hodgkin lymphoma vs., IV(1):103 pathology, IV(1):63, IV(1):64 sinonasal polyposis vs., IV(1):49 squamous cell carcinoma vs., IV(1):91 Diagnostic Imaging Head and Neck X Z Xeroderma pigmentosa, ocular melanoma associated with, IV(2):76 X-linked stapes gusher (DFNX2), VI(4):18, VI(4):19 Zenker diverticulum See Esophagopharyngeal diverticulum (Zenker) Zygomatic arch fracture, zygomaticomaxillary complex fracture vs., V(2):23 Zygomaticomaxillary complex fracture, V(2):22, V(2):23 1706 complex facial fracture vs., V(2):24 differential diagnosis, V(2):23 orbital blowout fracture vs., V(2):17 overview, V(2):3 staging, grading, & classification, V(2):23 trans-facial (Le Fort) fracture vs., V(2):19 ... MR 30(1) :2- 16, 20 09 8 42 Diagnostic Imaging Head and Neck Raghavan P et al: Magnetic resonance imaging of sinonasal malignancies Top Magn Reson Imaging 18(4) :25 9-67, 20 07 Aygun N et al: Imaging. .. Otorhinolaryngol 62( 2):111 -22 , 20 02 Lowe LH et al: Midface anomalies in children Radiographics 20 (4):907 -22 ; quiz 1106-7, 11 12, 20 00 Castillo M: Congenital abnormalities of the nose: CT and MR findings... Otol 118( 12) :955- 62, 20 04 Rahbar R et al: The presentation and management of nasal dermoid: a 30-year experience Arch Otolaryngol Head Neck Surg 129 (4):464-71, 20 03 Bloom DC et al: Imaging and surgical

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