[Preservation of hearing and facial nerve function after Gamma knife therapy for acoustic neurinomas].

Thirty-five patients with acoustic neurinomas were treated by Gamma knife from Sept. 1995 to Oct. 1997. Neuroimaging studies performed in 21 patients with more than 12 months showed that tumor size decreased in 9(43%) cases, unchanged in 11(51%) cases, and increased in 1(15%) case. The tumor growth control and regression rates were 95% and 43%, respectively. Some hearing was preserved in four patients (36%) who had hearing prior to Gamma knife treatment. There was new transient facial weakness in five patients(23%), and there was new trigeminal neuropathy after treatment in one patient (4.8%). These findings indicate that Gamma knife therapy is a safe and effective management for acoustic neurinomas, especially in preventing facial function and hearing.