Incidence of Acoustic Neuromas

Introduction In a previous study! we have analyzed the incidence of acoustic neuromas diagnosed in Denmark in the 7-year period from June 1976 to January 1983. All tumors operated in Denmark by translabyrinthine or suboccipital approach were analyzed as well as cases not operated. There were in total 178 cases corresponding to 39.7 neuromas per year. In a population of 5.1 million, the annual incidence was 7.8 patients per million inhabitants per year. During the last years we have had the impression that our translabyrinthine surgery has become easier with fewer giant tumors than in the first years. The change of severity must be caused by the earlier diagnosis of tumors. In order to evaluate whether the change and severity of the material is caused by increase of incidence due to better diagnosis of small tumors or decrease of number of giant tumors, exactly the same calculation as previously! has been employed for the following 7-year period from June 1983 to June 1990, covering the entire country. In highly selected temporal bone studies from various temporal bone collections acoustic neuromas were found between 1.7%2and 2.7%.3.5In other selected autopsy series the incidence of undiagnosed acoustic neuromas was 0.8%6 and 0.9%7 respectively. Several of these tumors were very small and originated from either ampulla, utriculus or cochlea. Except from the mentioned Danish study! there are no other studies on incidence of acoustic neuroma in a welldefined geographic area or a country.