In acoustic neuroma cranial nerve to be involved earliest is:
Ans. A V Vth nerve is the earliest nerve to be involved" Acoustic neuroma/vestibular schwannoma. a. MC intracranial schwannoma b. Constitutes 80% of CP angle tumor c. MC arises from superior vestibular nerve Clinical Features a. Generally affects adult females in age group of 40-60 year b. a/w tumor suppressor gene NF-2 which encodes merlin protein c. Earliest symptom - cochleo-vestibular symptoms (deafness, tinnitus) . MC symptom progressive U /L SNHL. d. Marked difficulty in understanding speech out of propoion to the pure tone hearing loss characteristic of acoustic neuroma. e. Earliest CN to be involved 5th nerve f. Sensory fiber of VII nerve are affected earlier than motor. There is hypoesthesia of posterior meatal wall calledHitzelberger Sign a. IV, VI, IX, X, XI, XII CN can also be involved. Diagnosis: b. Retrocochlear hearing loss c. MRI with gadolinium enhancement d. CT scan detects tumors that project even 0.5 cm into post fossa e. Veebral angiography to differentiate it from other cerebello pontine tumor. f. Electric response audiometry: delay of > 0.2 sec in wave between 2 ears is significant. Treatment: a. Surgery TOC i. Middle cranial fossa approach - if tumour is small with hearing present ii. Suboccipital approach - large tumour with some hearing iii. Translabyrinthine approach -large tumour with no hearing. b. Radiosurgery < 2.5 cm c. Gamma knife surgery (form of stereo tactic radiotherapy) used in patient who refuse surgery or CI to surgery or with residual tumor. Flip
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