Hereditary bilateral acoustic neuroma (central neurofibromatosis).

Fifty-five members of a kindred have bilateral acoustic neuroma. The trait is autosomal dominant with high penetrance. Onset is about age 20; survival varies from two to 42 years. In screening members, vestibular abnormalities are most consistently observed, but complete audiometric studies and brain scan are important, because no single study is diagnostically sufficient in all cases. Peripheral signs suggesting neurofibromatosis are rare, but other CNS tumors, often asymptomatic, are common suggesting this trait may represent a "central" form of neurofibromatosis.