Intraoperative monitoring of auditory and brain-stem function.

Extensive clinical experience has demonstrated that intraoperative brain stem auditory evoked potentials (BAEPs) are a reliable method of monitoring auditory and brain stem function during posterior fossa surgery. An intraoperative BAEP change identifies possible neurophysiologic compromise and allows adjustment of the surgical approach in an attempt to avoid permanent neurologic injury. The use of BAEPs intraoperatively has been associated with a significant decline in postoperative auditory morbidity. Supplementation of this technique with direct eighth nerve recordings and/or upper extremity somatosensory evoked potentials offers further improvement in identifying possible surgical threat to auditory or brain stem function.