STEREOTAXIC RADIOSURGERY FOR ACOUSTIC NERVE TUMORS IN PATIENTS WITH USEFUL PREOPERATIVE HEARING - RESULTS AT 2-YEAR FOLLOW-UP EXAMINATION

Twenty patients with acoustic nerve tumors (mean diameter less than or equal to 30 mm) and useful preoperative hearing were examined 2 years after stereotactic radiosurgery to determine the effectiveness of the surgery in the control of tumor growth and the preservation of crania l nerve function. Results showed tumor volume stabilization (12 cases) or reduction (seven cases) was achieved in a total of 19 patients (95 %). Useful hearing (defined as Gardner and Robertson Class I or II) pr eservation was obtained in 100% of cases immediately postoperatively, 50% at 6 months, and 45% at both 1 and 2 years. Two years after stereo tactic radiosurgery, facial nerve function was preserved in 90% of pat ients and 75% continued to have normal trigeminal nerve function. All patients returned to and maintained their preoperative functional stat us within 3 to 5 days after radiosurgery. These findings indicate that stereotactic radiosurgery with multiple isocenters and narrow radiati on beams is a safe and effective management strategy for progressive a coustic nerve tumors. Auditory, facial, and trigeminal nerve function can be preserved in most patients. Prevention of further growth and pr eservation of cranial nerve function appear to be satisfactory goals i n the current management of patients with acoustic neuromas.