Cerebellopontine Angle Masses ALI SAFAR - PGY4 November 09, 05 University of Ottawa ENT Dept Grand Rounds Introduction     10% of all intracranial tumors Fatal without treatment 78% are acoustic neuromas- mostly on vestibular branch Other CPA masses:       Meningiomas CN schwannomas Dermoid tumors Arachnoid cysts Lipomas, metastatic tumors Vascular tumors Anatomy   Potential space in the posterior fossa of the brain CPA boundries:       Anterior: posterior surface of temporal bone Posterior: anterior surface of the cerebellum Medial: lateral surface of brainstem Lateral: petrous bone Superior: inferior border of pons & cerebellar peduncle Inferior: cerebellar tonsil  Cranial nerves:     VII & VIII V IX, X, XI Important structures:    Flocculus Lateral aperture of 4th ventrical AICA Differential        Acoustic Neuroma 60 - 92% Meningioma Epidermoids Rare CPA lesions Petrous Apex masses Vascular malformations Intra-axial masses Acoustic Neuroma        Comprises 60-92% of CPA lesions Usually unilateral Arise from schwann cells, commonly within IAC Occur with equal frequency on the Superior & Inferior vestibular nerves Greatest density of S cells at scarpa ganglion Majority of cases (95%) are sporadic Rarely occur on the cochlear division of the th CN Acoustic Neuroma  Type NF:      Genetic defect on long arm of chromosome 22 Autosomal-dominant Bilateral or early in life Assoc with intracranial meningiomas & spinal cord tumors Tumors supressor gene is absent Pathology  Composed of Antoni A&B tissue  Antoni A – compact tissue with spindle cells in palisades (most common)  Antoni B – loose tissue with cyst formation Vertebrobasilar Dolichoectasia AICA loop Glomus Jugulare Petrous Apex       Cholesterol granulomas (most common) Epidermoid cyst Trigeminal schwannoma Carotid artery aneurysm Chondroma Chondrosarcoma Cholesterol Granulomas Intra-axial       Astrocytoma Ependymoma Medulloblastoma Hemangioma / Hemangioblastoma Choroid plexus papilloma Metastasis Treatment   Observation Surgery     Translabrynthine Retrosigmoid Middle Fossa Radiotherapy   Conventional radiation therapy Stereotactic radiosurgery Observation  Indications        Advanced age (over 65 or 75) Poor health Lack of symptoms Non-progression of symptoms Only hearing ear Isolated IAC tumors in the elderly Contraindications     Young patient Healthy patient Symptomatic progression Compression of brainstem structures Trans-labrynthine  Indications     Extension into CPA > 0.5 - 1cm Non-serviceable hearing Adequate contralateral hearing in large tumors Contraindications  Serviceable hearing Middle Fossa  Indications      Small tumor Intracanallicular tumor Moderate CPA involvement Adequate hearing (SRT50%) Contraindications    Large tumors Extensive CPA involvement ( > 0.5 – cm) Older patients ( > 60 yrs may have higher rate of bleeding or stroke) Retrosigmoid  Indications     Serviceable hearing Large tumors Compression of brainstem Contraindications   Functional hearing with extensive IAC involvement Intracanallicular tumors Stereotactic Radiosurgery  Indications       Small tumors Functional hearing Older patients (>75) Medically unstable patients Previous resection Contraindications    Tumors > cm Prior radiotherapy Tumor compressing brainstem Stereotactic Radiosurgery  Outcome    Local control (non-progression): 94% Hearing preservation: 47 – 77% Complications    Facial nerve injury: - 17% Trigeminal nereve injury: - 11% Hyrodcephalus: 3% ... X Schwanoma Vascular  Vertebrobasilar dolichoectasia    AICA loop      Enlongation and dilatation of the vertebrobasilar artery Symptomas - Facial spasm, trigeminal neuralgia May loop... Non-serviceable hearing Adequate contralateral hearing in large tumors Contraindications  Serviceable hearing Middle Fossa  Indications      Small tumor Intracanallicular tumor Moderate CPA involvement... Symptoms - vertigo Giant Aneurysms Hemangioma Paragangliomas (may extend to CPA)   Glomus Jugulare Glomus Tympanicum Vertebrobasilar Dolichoectasia AICA loop Glomus Jugulare Petrous Apex     