Changes in clinical features of acoustic neuroma.

During a 14-year period from 1976 to 1989, the authors experienced 160 cases of acoustic neuroma (AN). The clinical features were investigated in 132 of these cases (excluding those cases of recurrence and neurofibromatosis 2). The cases were divided into three periods for study. There were no significant differences in the patients' age, sex, or affected side among the three periods. The number of intracanalicular tumors have increased in recent years. The proportion of medium-sized and large tumors, however, has not changed, comprising about 70% of the total number of cases. Tumors of 20 mm or smaller in diameter were found in 24% of the cases in the early period, but increased to 58% in the most recent period. There was no difference among the periods in the length of time elapsed from the onset of symptoms to the first examination. A higher proportion of cases were diagnosed in otolaryngology departments in the middle and most recent periods than in the early period. Fewer cases in the most recent period presented initially with disequilibrium or trigeminal nerve symptoms. This was believed to be due to the increase in early stage cases. Patients are increasingly presenting with early stage AN. We feel that in order to support this favorable tendency, more emphasis needs to be placed on early diagnosis.