Auditory monitoring during acoustic neuroma removal.

Preservation of hearing has become attainable for patients with small acoustic neuromas. Brain-stem auditory evoked response was monitored intraoperatively in 60 patients undergoing acoustic neuroma surgery via the posterior fossa approach. The overall rate of hearing preservation was 30% in the monitored group and 20% in 60 patients who were matched for tumor size and preoperative hearing level and underwent the same surgical procedure but without intraoperative brain-stem auditory evoked response monitoring. The rate of hearing preservation was correlated with tumor size: with tumors less than or equal to 1 cm, hearing was preserved in 82% of monitored and 36% of unmonitored patients; hearing was not preserved with tumors larger than 3 cm. Intraoperative brain-stem auditory evoked response monitoring appears to have improved the preservation of hearing during removal of small tumors.