Incidence of vestibular schwannomas

Objective: To determine the incidence of vestibular schwannoma (VS) in Denmark in a period of 19 1/2 years. Study Design: Retrospective review of prospective registered data on all patients with VS operated on by the translabyrinthine, lateral suboccipital, or middle cranial fossa approach, as well as patients who were allocated to the "wait-and-scan" group. Methods: Charts were reviewed and tabulated for age, extrameatal tumor extension, and date of diagnosis. The available data were divided into three periods: June 1976 to June 1983, July 1983 to June 1990, and July 1990 to December 1995, Results: The number of newly diagnosed tumors in the first period was 278, corresponding to an incidence of 7.8 tumors/million population per year in the second period 337, corresponding to an incidence of 9.4 tumors/million population per year; and in the third period 355, corresponding to an incidence of 12.4 tumors/million population per year, A significant increase in incidence of the newly diagnosed intracanalicular tumors in the second and third periods was observed, Conclusion: The increase in incidence of VS can probably be explained by the awareness among otolaryngologists of the diagnosis of VS and better access to computed tomography and magnetic resonance imaging scans. The observed increase in the diagnosis of the small and intrameatal tumor creates a clinical dilemma, whether to operate on tumors in this early stage or to allocate patients to the wait-and-scan group. This problem will still be relevant in the upcoming years, since the incidence of intrameatal and small VS is expected to increase.