Intraoperative electrophysiologic monitoring of cranial motor nerves in skull base surgery.

BACKGROUND

Intraoperative cranial nerve monitoring has been applied for the preservation of nerve function during skull base surgery. However, its usefulness is controversial because clinical results reported are limited.

METHODS

We evaluated the usefulness of intraoperative electrophysiologic monitoring of the third to seventh cranial motor nerves in 15 patients undergoing skull base surgery. Intracranial bipolar electrical stimulation of each nerve was performed, and compound muscle action potentials (CMAP) were recorded from the innervated muscles.

RESULTS

CMAPs were successfully recorded from 23 of the innervated muscles. The loss of the CMAP response during the manipulation of lesions or high stimulus intensity at the end of manipulation seem to be related to the postoperative deficits of nerve function.

CONCLUSIONS

The results suggest that intraoperative electrophysiologic monitoring of cranial motor nerves is useful for prediction of postoperative nerve function.