Bilateral vestibular schwannomas: the challenge of neurofibromatosis type 2

Vestibular schwannomas are benign tumours that are said to originate predominantly from the superior vestibular nerve. Their incidence is estimated to be between 2-20 cases per million worldwide, comprising approximately 5-10% of intracranial tumours. They arise in the cerebellopontine angle accounting for approximately 90% of mass lesions in this location. This chapter discusses how to recognise and treat vestibular schwannomas. Vestibular schwannomas may be managed conservatively, surgically or with radiotherapy. Combined modality treatment has also been successfully reported, for example sub-total debulking followed by gamma knife therapy for large vestibular schwannomas. Tumours may be approached surgically via three approaches. The two most commonly used are retrosigmoid transmeatal and translabyrinthine, with the middle cranial fossa approach less prevalent. Treatment of these tumours will increasingly depend on less invasive modalities including focussed radiation techniques and molecular chemotherapeutics. Radiosurgery is significantly less effective in NF2 associated schwannomas and this represents a particular challenge in management. Clinical trials of bevacizumab (a VEGF inhibitor), and Lapatinib (a tyrosine kinase inhibitor) in NF2 are ongoing.