Definition: Benign tumor arises from schwann cells of vestibular n. (vestibular schwannoma).
Incidence: 40-50 years age of presentation. 8% of brain tumors,80% of CPA.
Pathology:
Arise from glial neurilemmal junction at IAM (or CPA).
Grossly: slowly growing, encapsulated, smooth, and firm.
MP: Fasiculated type (Antoni A), Reticular (Antoni B).
Clinical picture of Acoustic Neuroma
A) Otological:
- Unilateral slowly progressive SNHL.
- Unilateral tinnitus.
- Vertigo is not marked as condition is slowly progressive, allows for central compensation.
B) Neurological:
- Lost corneal reflex.
C) Cerebellar
D) Terminal:
- Increased intra-cranial tension and death.
Investigations for diagnosis of Acoustic Neuroma
- PTA : reveals SNHL.
- Speech audiogram: poorer speech discrimination than PTA (retrocochlear lesion).
- ABR delay of wave V.
- CT with contrast.
- MRI with contrast: the best.
Differential diagnosis of Acoustic Neuroma
Other CPA lesions, e.g Meningioma, congenital cholesteatoma, arachnoid cyst, and pontine glioma.
Treatment of Acoustic Neuroma
- Surgery: approach depends on size and hearing.
- Small intracanalicular tumor with good hearing….middle cranial fossa.
- Large CPA tumors with good hearing……….retrosigmoid.
- Bad hearing ….translabrynthine.
- Gamma knife (stereotactic radio surgery).
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