Epidemiology

Vestibular schwannomas are usually slow-growing tumours, with approximately one half of small tumours not demonstrating growth on repeat imaging in the first 3-5 years of active surveillance.[8][9][10]​​​​​​ They are the third most common intracranial benign tumour in adults and represent over 80% of all cerebellopontine angle tumours.[11][12]​

Approximately 95% of vestibular schwannomas develop sporadically and present as solitary tumours. Less commonly, people may develop bilateral vestibular schwannomas - with or without other associated cranial, spinal, or peripheral tumours - an autosomal dominant condition known as neurofibromatosis-related schwannomatosis (previously known as neurofibromatosis 2).[13][14]​​​​​​ Even less commonly, unilateral vestibular schwannoma, combined with other cranial, spinal, or peripheral schwannomas, may be associated with schwannomatosis.[15]​ The annual incidence varies significantly across the literature, typically between 1 and 4 cases per 100,000 people per year, with a similar distribution between sexes.[16][17]​​​​​ One systematic review found that the lifetime prevalence of developing sporadic vestibular schwannoma probably exceeds 1 per 500 persons.[18]​ Increased numbers of smaller tumours are detected owing to the widespread adoption of screening among people with asymmetrical hearing loss and the rising availability of magnetic resonance imaging. As a result, today, patients are commonly diagnosed with smaller tumours, less severe hearing loss, and at older ages than ever before.[19][20]​​​

There are slight variations in how different races and ethnicities are affected by vestibular schwannoma. A US-based analysis of a national population-based tumour registry found that the median annual incidence of disease was lowest among black (0.43 per 100,000 persons) and Hispanic (0.45 per 100,000 persons) populations and highest among white (1.61 per 100,000 persons) populations (P <0.001). In addition, compared with white populations, black, Hispanic, and Asian populations are more likely to present with larger tumours.[21]​ Differences in incidence may be because of genetic and environmental factors but are most likely to be because of different diagnostic practices and access to screening magnetic resonance imaging across groups.[13]

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