434 Chapter 13 3 Sacral chordoma ◆ Common locations of chordoma include sacrococcygeal region (50%), clivus, and C1–2. ◆ Accounts for 40% of all sacral tumors. ◆ The tumor is destructive, lytic, and is often associated with calcifi cation. ◆ Differential diagnosis includes chondrosarcoma. 4 Multiple myeloma ◆ The rate of sacral involvement by plasmacytoma or multiple myeloma is 2–4%. ◆ Solitary osseous plasmacytomas usually have longer survival periods follow- ing radiation therapy. 5 Others ◆ Giant cell tumor (most common benign sacral tumor) ◆ Osteomyelitis ◆ Neurofi broma ◆ Aneurysmal bone cyst Specifi c diseases/differentials Chiari malformations Features Chiari I malformations Chiari II malformations Major abnormalities Peg-like, pointed tonsils displaced into upper cervical canal, >5 mm below foramen magnum Cerebellar tonsils, vermis, fourth ventricle, and brainstem are herniated through the foramen magnum, and the egress fourth ventricle is obstructed • Chiari malformation is a disorder of primary neurulation, mostly neural tube closure defects and early CNS anomalies, typically occurring around 3–4 weeks’ gestation. • The spectrum of congenital anomalies labeled the Chiari malformations spans a wide range. Symptomatic patients with Chiari malformations are seen with ataxia, vertical nystagmus, headache, cranial nerve VI through XII abnormalities, and signs of syringomyelia. • The different features of Chiari I and II are discussed in the table below. Chiari III malformations are associated with herniation of posterior fossa contents into an occipital or high cervical encephalocele with other features of Chiari II malformations. Chiari IV malformations are very rare and are associated with severe hypoplastic cerebellum, small brainstem, and large posterior fossa CSF spaces. Neuroradiology 435 Features Chiari I malformations Chiari II malformations Associated anomalies Skull & dura Normal • Calvarial defects • Small posterior fossa • Fenestrated falx • Gaping foramen magnum Brain Normal • Inferiorly displaced vermis • Medullary kink • Beaked tectum • Interdigitated gyri • Cerebellum creeps around brainstem Ventricles • Mild to moderate hydrocephalus (20–25%) • Hydrocephalus (90%) • Elongated, tube-like fourth ventricle • Colpocephaly, scalloped, pointed walls of lateral ventricles Spinal cord • Syringomyelia (30–60%) • Myelomeningocele (nearly 100%) • Syringohydromyelia (50–90%) • Diastematomyelia • Segmentation anomalies Skeletal anomalies • Basilar invagination (25–50%) • Klippel-Feil syndrome (5–10%) • Atlanto-occipital assimilation None Failed back syndrome 1 Soft-tissue causes 1.1 Recurrent or residual disc herniation ■ No enhancement on early T1W images. 1.2 Epidural fi brosis (scarring) ■ Heterogeneous enhancement on early T1W images. 1.3 Postoperative complications ■ Infections • Failed back syndrome refers to failure to improve or recurrence of low back pain in patients following lumbar disc surgery. • The incidence of this syndrome varies between 5 and 40%. • The diagnosis of scar versus residual/recurrent disc is critically important as the treatment is different. Surgery is not indicated for scar, but could be indicated if the disc causes radiculopathy. • MRI with gadolinium enhancement is useful in this differentiation as diffuse enhancement occurs in the scar but not the disc. 436 Chapter 13 ■ Hemorrhage 1.4 Adhesive arachnoiditis ■ Thickened, irregular clumped nerve roots 2 Osseous causes (less common) ◆ Central canal stenosis ◆ Foramina stenosis ◆ Spondylolisthesis 3 Iatrogenic causes ◆ Direct nerve injury during surgery ◆ Surgery at wrong level Intracranial hemorrhage Hypertensive hemorrhage vs. amyloid angiopathy Neuroradiological features Hypertensive hemorrhage Hemorrhage from cerebral amyloid angiopathy Common Most common cause of intracranial hemorrhage (overall) Less common, but probably the most common cause of recurrent hemorrhage in the elderly (10%) Locations • 60%: basal ganglia (esp. putamen), thalamus • 10–15%: brainstem (esp. pons) • 5–10%: cerebellum • 10–50%: can be lobar • Usually lobar, involving frontal and parietal lobes • Rarely in the cerebellum, white matter, basal ganglia, or brainstem Mutiple locations Usually solitary Clasically multiple Pathogenesis Unclear May be related to Charcot- Bouchard aneurysms (confl icting evidence!) Amyloid depositions probably cause microaneurysms and fi brinoid degeneration. Loss of vessel elasticity due to amyloid deposits. • Hypertension is the presumed cause of nontraumatic intraparenchymal hemorrhage in 70–90% of cases. The location of hypertensive hemorrhage varies. • Cerebral amyloid angiopathy (CAA) results from deposition of amyloid in the media and adventitia of small and medium-sized vessels of the superfi cial layers of the cerebral cortex and leptomeninges, usually with sparing of the deep gray nuclei. • CAA increases with advancing age and may be the most common cause of recurrent intracranial hemorrhage in elderly normotensive patients. Neuroradiology 437 Neuroradiological features Hypertensive hemorrhage Hemorrhage from cerebral amyloid angiopathy Neuroimaging fi ndings Follow hemorrhagic evolution pattern, (see hemorrhagic evolution for details) Multiple areas of hemorrhages Gradient-echo imaging with emphasis on T2 effects are useful Associations • Coronary artery disease • Peripheral vascular disease • Alzheimer disease (30–40%) • Down syndrome • Dementia pugilistica • Leukoencephalopathy • Spongiform encephalopathy (Not associated with systemic amyloidosis) Non-neoplastic vs. neoplastic hemorrhage Neuroradiological features Neoplastic hemorrhage Non-neoplastic hemorrhage Edema Prominent Less prominent Multiple lesions Usually solitary, unless metastases Supportive of vascular malformation in appropriate clinical setting Hemosiderin rim Incomplete Usually complete Heterogeneity Heterogeneous and complex More homogeneous Hemorrhagic evolution Delayed Not delayed Contrast enhancement Enhancement in non- hemorrhagic areas Varies depending on the nature of the lesion Common intracranial tumors with hemorrhage • Distinguishing hemorrhagic intracranial neoplasms from non-neoplastic hematomas can be diffi cult, since there is considerable overlap between neuroimaging fi ndings. • The following are helpful differentiating features, although they should not be considered as pathognomonic for either etiology. • In some cases where there is radiographic and clinical uncertainty, biopsy of lesions or close follow-up neuroimaging may be required. • The etiology of tumor-induced hemorrhage is unclear. However, many factors appear to contribute, including presence of a high-grade tumor, histologic type, presence of neovascularization, rapid tumor growth with necrosis, plasminogen activators, and direct vascular invasion. 438 Chapter 13 1 Anaplastic astrocytoma and glioblastoma ◆ Common cause of unexplained intracranial hemorrhage in normotensive, non-demented elderly patients. 2 Pituitary adenoma ◆ The most common non-glial hemorrhagic primary intracranial tumor. ◆ Other non-glial tumors rarely bleed. 3 Metastatic tumors ◆ Hemorrhage occurs in up to 15% of brain metastases. ◆ Common tumors include renal cell carcinoma, choriocarcinoma, melanoma, brochogenic carcinoma, and thyroid carcinoma. ◆ Typical MR fi ndings of hemorrhage into metastatic foci are: ■ Marked heterogeneity ■ Blood degradation products of different ages ■ Fluid-fl uid levels ■ Located at gray-white interface 4 Oligodendroglioma ◆ The most common non-astrocytic gliomas associated with hemorrhage. 5 Primitive neuroectodermal tumors and teratomas ◆ More likely in young children. 6 Ependymoma ◆ Especially in the spinal cord, can cause repeated hemorrhages resulting in su- perfi cial siderosis. • The overall incidence is approximately 1 to 15%. Virtually any tumor in any location can bleed, although some tumors are more likely to bleed than others. • In general, the more malignant astrocytomas bleed, as do vascular tumors and necrotic tumors. Low-grade astrocytomas, mesenchymal cysts, and slowly growing tumors are less likely to bleed. • Primary CNS lymphomas in immunocompetent patients rarely have necrosis or hemorrhage, in contrast to primary CNS lymphomas in HIV- infected patients, which tend to bleed. • Unless the metastatic deposit is hemorrhagic, calcifi ed, hyperproteinaceous, or highly cellular (where it would be hyperdense on noncontrast CT), most metastases are low density on unenhanced CT imaging. • Hemorrhagic metastases are usually seen as areas of high signal intensity on T1W and T2W MRI with a relative absence of hemosiderin deposition. Neuroradiology 439 Hemorrhagic metastases to the brain 1 Breast and bronchogenic carcinoma: the most common tumors to cause hem- orrhagic metastases. 2 Mnemonic ‘MR CT’ ◆ M for melanoma ◆ R for renal cell carcinoma and retinoblastoma ◆ C for choriocarcinoma ◆ T for thyroid carcinoma (Ref: Modifi ed from Neuroradiology: The requisites.) Intracranial cysts 1 Congenital lesions 1.1 Arachnoid cyst ■ The most common congenital cystic abnormality in the brain. ■ It is a benign condition and rarely produces symptoms. ■ Thought to be due to accumulation of CSF between the layers of arach- noid membrane. ■ Common locations include the middle cranial fossa, parasellar cisterns, and the subarachnoid space over the convexities. ■ On MRI, the most common appearance is that of an extra-axial mass, which has a signal intensity identical to CSF on all pulse sequences. 1.2 Colloid cyst ■ It probably arises congenitally as a result of encystment of ependyma. ■ Usually located in the anterior portion of the third ventricle near the foramen of Monro. • Hemorrhagic metastases must be differentiated from occult cerebrovascular malformations or non-neoplastic hematomas. In hemorrhagic metastases, the edema, mass effect, and enhancement tend to be larger and more persistent than occult hemorrhagic lesions in malformations. • Intracranial cysts can be found incidentally or as space-occupying lesions producing focal defi cits, signs of increased intracranial pressure, or hydrocephalus. • The etiology varies, commonly being congenital, infection-related, or part of the tumors. 440 Chapter 13 ■ Positional headaches or hydrocephalus may be the presenting com- plaints in 30–40-year-old patients. ■ The lesion is usually hyperdense on CT imaging because of the high protein content. 1.3 Rathke cleft cyst ■ Rathke cleft cyst is an embryologic remnant of Rathke pouch, the endo- derm that ascends from the oral cavity to the sellar region to form the pituitary anterior lobe and pars intermedia. ■ The cyst is usually found incidentally showing high or low signal inten- sity on T1WI and high signal intensity on T2WI with hypodensity on CT and does not enhance with contrast. 2 Tumoral cyst 2.1 Pineal cyst ■ Pineal region tumors can have cystic components, especially germ cell tumors. 2.2 Dermoid and epidermoid cyst ■ Epidermoids have a single medium, but dermoids have multiple media, such as fat, cystic fl uid, and soft tissue. 2.3 Intratumoral cyst, e.g. in cystic astrocytoma. 3 Infections 3.1 Cysticercosis ■ Endemic in parts of Latin America, Mexico, Asia, and Africa. ■ The parasite is acquired by ingestion of insuffi ciently cooked pork, con- taining the encysted larvae. Infestation to the CNS produces seizures as the most common neurological manifestation. ■ Classically, the plain skull X-ray shows calcifi cation in the brain paren- chyma of 1–2 mm in diameter, representing the scolex, surrounded by a calcifi ed sphere. 3.2 Hydatid cyst, from Echinococcus infection. 4 Others 4.1 Cyst of the cavum septum pellucidum 4.2 Cava interpositum and vergae 5 Pseudocyst 5.1 Porencephaly ■ Porencephaly refers to an area of focal encephalomalacia that commu- nicates with the ventricular system, causing what appears to be a focal dilated ventricle. ■ The causes include trauma, infection, and perinatal ischemia. Neuroradiology 441 Lymphoma vs. toxoplasmosis in AIDS Features Lymphoma Toxoplasmosis Patient’s immune status Both immunodefi cient and immunocompetent Usually occurs in only immunodefi cient patients Multiple lesions 81% 61% Size of lesions 75% of lesions are 1–3 cm 52% of lesions are < 1 cm 36% of lesions are 1–3 cm Lesion locations Periventricular and deep gray matter lesions, subependymal and spread across the corpus callosum Often in deep gray matter. Less likely to be periventricular, subependymal or in corpus callosum Homogeneous CT enhancement Yes, in approximately 70% Yes, in approximately 70% Hyperdensity on non-enhanced CT 30% of lesions Unlikely unless hemorrhage present Hemorrhage Very rare May occur T2W MRI 50% isointense All hyperintense Ref: Modifi ed from Dinas T.S. Primary CNS lymphoma versus toxoplasmosis in AIDS. Radiology 1991; 179: 823–828. • The most common type of lymphoma to affect the brain is diffuse histiocytic lymphoma (primary cerebral lymphoma). It is mostly non- Hodgkin type. • The classic teaching used to be that lymphoma was one of the lesions that is typically hyperdense on noncontrast CT and enhances to moderate degree. Such generalizations are no longer valid, since AIDS-related lymphoma causes a variety of appearances. AIDS-related lymphoma tends to present with multiple, smaller lesions and shows marked (and ring) enhancement with gadolinium, compared to lymphoma in immunocompetent patients. • Primary lymphoma of the brain is usually supratentorial and located in deep gray nuclei or periventricular white matter. Coating of the ventricles and spread across the corpus callosum is suggestive of lymphoma. • Toxoplasmosis remains the important differential diagnosis, especially in AIDS patients with lesions in deep gray nuclei. When radiological differentiation is not possible, empirical treatment with pyrimethamine should be considered. Patients with toxoplasmosis usually respond rapidly to the treatment, while patients with lymphoma do not. 442 Chapter 13 Ring enhancing lesions 1 Infectious causes: usually suggest hematogenous spread. ◆ Pyogenic brain abscess. ◆ Toxoplasmosis, especially in HIV. ◆ Tuberculosis. ◆ Fungal infection. 2 Neoplastic: the rim is usually thick, irregular and nodular. ◆ Metastatic tumor (hematogenous metastases), more common than primary brain tumor. ◆ Primary brain tumor, e.g. glioblastoma, primary CNS lymphoma. 3 Infarction 4 Granulomatous process 5 Demyelination 6 Subacute hematoma (suggests 6 days to 6 weeks old) PS: in HIV patients, it is sometimes diffi cult to differentiate clinically and radio- logically between toxoplasmosis and primary CNS lymphoma. Helpful clues are a greater predilection for basal ganglia (subcortical gray matter) and more sur- rounding edema in toxoplasmosis and less so in lymphoma. Occasionally, empirical treatment with pyrimethamine is indicated in cases with unclear diagnosis. • When there is enhancement, it suggests that the process is subacute or chronic. Slowly progressive conditions should not enhance. • In addition, enhancement is at the rim because the central area generally lacks a good blood supply and is necrotic. The process is usually focal or multifocal and unlikely to be diffuse. 443 Chapter 14 Spinal Cord Disorders Signs and symptoms 443 Distinguishing spinal cord from peripheral nerve pathology 443 Differential diagnosis and symptoms by location in cord 444 Distinguishing lesions of the conus medullaris vs. cauda equina 448 Pain 448 Low back pain 448 Radiculopathy 450 Differentiating neurogenic from vascular claudication 451 Syndromes 451 Spinal cord syndromes 451 Acute paresis/plegia 453 Transverse myelitis 455 Chronic para- or quadriparesis 457 Spinal cord tumors (see Chapter 10: Neuro-oncology) Slowly progressive weakness 458 Anterior horn cell disease 458 Combined anterior horn cell and corticospinal tract disease 459 Spinal muscular atrophy 461 Signs and symptoms Distinguishing spinal cord from peripheral nerve pathology • Spinal cord pathology is suggested when there is a triad of symptoms: ◆ Sensory level (the hallmark of spinal cord disease) ◆ Distal, symmetric, spastic weakness ◆ Bowel and bladder dysfunction Neurological Differential Diagnosis: A Prioritized Approach Roongroj Bhidayasiri, Michael F. Waters, Christopher C. Giza, Copyright © 2005 Roongroj Bhidayasiri, Michael F. Waters and Christopher C. Giza [...]... Serological tests for neurosyphilis Other clinical tests Autonomic dysfunction: clinical tests Tensilon or edrophonium test Urodynamic findings on neurogenic bladder 487 488 4 89 490 490 491 492 493 493 493 494 495 496 497 497 498 499 500 501 501 502 503 503 505 506 506 506 507 EEG Normal or nonpathological EEG Electroencephalographic rhythms • • The rhythmic EEG activity is due to intrinsic membrane properties... 3 4 5 6 7 8 Fp1-C3 C3-O1 Fp2-C4 C4-O2 Fp1-T3 T3-O1 Fp2-T4 T4-O2 2 Interelectrode impedance should be less than 10,000 ohm but more than 100 ohm 3 Verify the integrity of the recording system 4 Interelectrode distances of at least 10 cm 5 A sensitivity of 2 μV/mm for at least 30 minutes of recording 6 Use of appropriate filtering settings 7 Use of monitoring techniques 8 No EEG activity 9 Performed by... and fibrillations This differential is distinct from that for ‘Combined anterior horn cell and corticospinal tract disease’ (see p 4 59) Spinal Cord Disorders 4 59 1 Infantile spinal muscular atrophy (~1:15,000) (Werdnig-Hoffman disease) ◆ (See p 461, Spinal muscular atrophy) 2 Juvenile spinal muscular atrophy (Kugelburg-Welander disease) ◆ (See p 461, Spinal muscular atrophy) 3 Adult-onset spinal muscular... prognosis Ability to Fasciculations sit Serum creatine kinase Inheritance Never + /- Normal AR + /- Normal AR > 4 years / no Usually ambulation Juvenile (KugelbergWelander) (type III) > 2 years Adulthood Always ++ Elevated AR Adult-onset (type IV) > 20 years 50 years + / slow progression Always ++ Elevated AR Neurological Differential Diagnosis: A Prioritized Approach Roongroj Bhidayasiri, Michael F Waters,... Progressive muscular atrophy (Aran-Duchenne syndrome) ◆ Predominance of lower motor neuron signs ◆ Asymmetric muscle atrophy and weakness ◆ Reflexes normal or slightly decreased Other conditions whose presentation may mimic ALS ◆ Important to consider because most are treatable (except Guamanian Parkinson-dementia-ALS complex) 7.1 Monoclonal gammopathy ALS-like syndrome: anti-MAG antibodies 7.2 Multifocal... Tuberculosis 3.4 Syphilis 3.5 Human T-cell lymphotropic virus type 1/2 (HTLV-1/2) 4 Metabolic/toxic 4.1 Vitamin B12 deficiency 4.2 Nitrous oxide inhalation-induced subacute combined degeneration 4.3 Post-radiation therapy myelopathy 4.4 Vitamin E deficiency 5 Hereditary and congenital conditions 5.1 Cerebral palsy: spastic diplegia, hemiplegia, or quadriplegia 5.2 Arnold-Chiari malformation with or without... (anti-parietal cell antibodies, reduced intrinsic factor), tropical sprue, gastric/ileal resection, jejunal diverticula, rarely due to inadequate dietary animal protein 4.2 Tabes dorsalis (syphilis) Other associated findings include lancinating lightning-like pains, lower extremity areflexia, Argyll-Robertson pupils, muscle wasting, optic atrophy, ataxia, sphincter dysfunction 4.3 N2O inhalation-associated... Adrenomyeloneuropathy: usually chronic/progressive 2 Other non-infectious inflammatory disorders 2.1 Post-infectious/post-vaccinal transverse myelitis 2.2 Primary angiitis of the central nervous system 2.3 Systemic lupus erythematosis 2.4 Paraneoplastic myelopathy Some myelopathies associated with breast, lung, lymphomas Others with anti-Hu antibody associated with dorsal root ganglia degeneration 2.5... Epileptiform activity Pathological spikes and sharp waves and clinical correlation 468 468 468 4 69 470 470 471 Periodic patterns on EEG Hypsarrthythmia Prognostic EEG patterns following a hypoxic insult 473 474 474 Evoked potentials Brainstem auditory-evoked potentials (BAEPs) Somatosensory-evoked potentials (SSEPs) Visual-evoked potentials (VEPs) Peripheral electrodiagnostics Normal electromyographic activity... 476 477 478 478 4 79 480 481 482 483 484 485 486 486 Diagnostic Tests 463 Intracranial hypotension CSF findings in meningoencephalitis and hemorrhage Cloudy CSF Elevated CSF glucose Low CSF glucose (hypoglycorrhachia) Elevated CSF protein Low CSF protein CSF eosinophilia Specialized CSF tests CSF oligoclonal bands Elevated CSF myelin basic protein CSF 1 4-3 -3 protein CSF angiotensin-converting enzyme . in AIDS. Radiology 199 1; 1 79: 823–828. • The most common type of lymphoma to affect the brain is diffuse histiocytic lymphoma (primary cerebral lymphoma). It is mostly non- Hodgkin type. • . lancinating lightning-like pains, low- er extremity arefl exia, Argyll-Robertson pupils, muscle wasting, optic atrophy, ataxia, sphincter dysfunction. 4.3 N 2 O inhalation-associated subacute. hemorrhage in normotensive, non-demented elderly patients. 2 Pituitary adenoma ◆ The most common non-glial hemorrhagic primary intracranial tumor. ◆ Other non-glial tumors rarely bleed. 3 Metastatic