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