Concept
Vestibular schwannoma
Vestibular schwannomas are tumours of cranial nerve VIII and account for approx. 90% of cerebellopontine angle tumours. They are benign tumours arising de novo (except in neurofibromatosis type 2 where there is a genetic mutation) from Schwann cells of the nerve sheath. Suggestive features include unilateral sensorineural hearing loss, unilateral tinnitus, vertigo, absent corneal reflex, and facial palsy.
The gold standard investigation is MRI head; the size (diameter of the cerebellopontine angle portion) can then be measured to help guide management. 70% of vestibular schwannomas are stable whereas 20% increase in size (average 1-2mm per year but not predictable). The most appropriate management for tumours not already compressing the cerebellum or brainstem is to rescan in 6 months.
For large or fast-growing tumours, surgical intervention may be considered. Options include translabyrinthine, retrosigmoid and middle fossa approaches; various objective and subjective patient and surgeon factors are considered in deciding the type of surgical approach. In patients where surgery is not possible, stereotactic radiosurgery – a form of radiotherapy – may be considered, though the long-term side effects and complications are less known.
Correct Answer:
B
ASCENT 