Acoustic Neuroma: definition, incidence, symptoms, investigations and treatment

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).