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.
acoustic-neuroma

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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