The Incidence of Acoustic Neuromas

To the Editor.—Medical literature describes the acoustic neuroma as the most common tumor of the posterior fossa, but its actual incidence or prevalence in the general population is not known. Autopsy studies have found vestibular nerve sheath tumors in 1%, or fewer, of cases.1,2One percent would extrapolate to over two million cases in the United States, a number far greater than seen clinically. In Denmark, Tos and Thomsen3reviewed all neurosurgically referred cases for the entire country (population, 5.1 million) and found an average of 39.7 patients yearly over a seven-year period, for an incidence of 0.78 per 100000 population. As no such data existed for the United States, we reviewed the cases referred to neurosurgery in our membership (population, 2 million) and found an average of 23 yearly over a three-year period, for an incidence of 1.15 per 100000 population. Virtually all acoustic neuromas that