Intra-operative monitoring in acoustic neuroma surgery.

Intra-operative neurophysiologic monitoring (IOM) is rapidly evolving as an important adjunct during acoustic neuroma surgery to reduce the incidence of neurologic deficits. Monitoring alerts the surgeon to ongoing changes in neural function. The benefit of facial nerve monitoring in reducing the incidence of facial palsy during acoustic tumor resection appears clear and is now recommended by the National Institutes of Health (Consensus Development Conference on Acoustic Neuroma, 1991). Auditory monitoring is not as effective as facial monitoring but hearing preservation can be enhanced particularly if used with facial monitoring because the latter alerts the surgeon to traumatic manipulations that may affect both facial and cochlear nerves. Monitoring is not a replacement for surgical experience. 'Poor monitoring is worse than no monitoring'.