Use of antidromic recording to monitor facial nerve function intraoperatively

This report describes a technique for monitoring facial nerve activity intraoperatively utilizing antidromic nerve stimulation and sequential averaging of the evoked responses. Compound facial nerve action potentials are obtained reliably even in the presence of paralyzing doses of muscle relaxants, which render the conventional methods useless. The electrophysiological setup is straightforward, and we utilize the same sequential averaging equipment with which we monitor cortical evoked responses intraoperatively. This technique facilitates identification of the facial nerve in large cerebellopontine angle tumors with minimal mechanical trauma. Recordings from eight clinical cases are presented to illustrate the reliability and reproducibility of this technique.