1. Acoustic neuroma
Chunfu Dai M.D & Ph.D

2. Background Originate from vestibular branch of aucoustic nerve
Histologic feature: schwanoma, neuroma, neurolemmoma
Predilection: 30-50y
Unilateral: majority
Bilateral: Type II acoustic neuroma

3. Pathology Predominate: internal auditory canal Extension to CPA
Compression on brainstem and brain hydrops
Anterior: trigeminal nerve,
Medial: abducent nerve
Inferior: IX, X, XI, XII

4. Clinical presentations
Hearing loss and tinnitus
Progressive HL 90%
SDS reduction
10% of patients complain of sudden HL.
Unbalance
Otalgia and compression due to depression of sensor fiber of facial nerve
Involvement of trigeminal nerve
Compression of cerebellum and brainstem: ataxia, nystagmus and intracranial hypo-pressure

5. Work-up Audiometry PTA: threshold elevated in high frequency
tone decay test: positive
Speech audiometry
Acoustic impedance
ABR: latency of wave V prolongs, or wave V disappears
Acoustic emission

6. Work-up Vestibular function: Neurologic exam Image study
CT shows enlargement of internal auditory canal
MRI

7. Managements Surgery Middle cranionectomy: useful hearing
Translabyrinectomy:
no useful hearing
Nice exposure of facial nerve

8. Managements Retro-sigmoid sinus approach: Inferior occipital approach:
Big tumor >3cm
Nice exposure tumor

9. Managements
No surgical intervention
-Knife
observation