Incidence of Vestibular Schwannoma and Neurofibromatosis 2 in the North West of England over a 10-year Period: Higher Incidence Than Previously Thought

Objective: To determine the incidence of vestibular schwannoma (VS) in sporadic, neurofibromatosis type 2 (NF2) germ-line and mosaic form in a 10-year period.

Study Design: Review of all incident cases of VS presenting to the four main neurosurgical centers for a population of 4.1 million from 1990 to 1999 and cross-referencing with the regional cancer registry.

Setting: Population based.

Patients: All patients presenting with VS detected on magnetic resonance imaging scan.

Results: A total of 419 sporadic and 64 NF2-related VS were identified over the study period. This represented an incidence of 10.4 per million per year for sporadic VS and 11.8 per million per year including NF2-related tumors. The incidence rose to 14 per million per year in the latter 5 years. The NF2 patient diagnoses represent an estimated birth incidence of 1 in 25,000, and 7% of the patients with VS had NF2, which is higher than previous estimates.

Conclusions: The incidence of VS is rising almost certainly due to increasing diagnosis in the magnetic resonance imaging era. At current rates, 1 per 1,000 individuals will be diagnosed with VS in their lifetime. More VS than previously thought are due to NF2, which may be because of recognition of mosaic forms of the disease.