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Acoustic neuroma - misnomer; neuroma = SOL of CNS; CN8 is PNS!
Vestibular schwannoma - misnomer → the tumor source usually from acoustic nerve (sup. or inf).
Acute vestibulitis → pts in bed;
Chronic vestibulitis → ⊖ vestibular Sx (compensated w/ time)
Clinic:
The 1st Sx - ↓ hearing due to acoustic nerve involvement.
The facial nerve compresses but doesn't cause weakness.
Facial weakness → only if damaged in Qx
The 2nd Sx is hemifacial hypoesthesia due to CN5 involvement → compression by the tumor.
slow-growing (average of 1 mm/yr), benign posterior fossa tumour
arises from vestibular component of CN VIII in internal auditory canal, expanding into bony canal and cerebello-pontine angle (CPA)
if bilateral, diagnostic of neurofibromatosis type II
epidemiology: all age groups affected, peaks at 4th-6th decades
Clinical features
compression of structures in CPA, often CN VIII (hearing loss 98%, tinnitus, dysequilibrium), followed by CN V and VII
ataxia and raised ICP are late features
Investigations
MRI /w gadolinium or T2 FIESTA sequence (>98% sensitive/specific), CT with contrast 2nd choice
audiogram, brainstem auditory evoked potentials, caloric tests
Treatment
conservative: serial imaging
radiation: stereotactic radiosurgery or fractionated radiotherapy
surgery if: lesion >3 cm, brainstem compression, edema, hydrocephalus
curable if complete resection (almost always possible)
operative complications: CN VII, VIII dysfunction (only significant disability if bilateral), CSF leak
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