Direct cochlear nerve monitoring: first report on a new atraumatic, self-retaining electrode

To assess the efficacy and safety of a new atraumatic, self-retaining cranial nerve electrode for direct cochlear nerve monitoring during cerebellopontine angle surgery.

Prospective clinical investigation.

The Skull Base Surgery Center at Kaiser Permanente, San Diego, a tertiary referral center for neurotologic and skull-base surgery within Southern California Permanente Medical Group.

Eighteen patients, with aidable preoperative hearing, underwent direct cochlear nerve monitoring with this new electrode during cerebellopontine angle surgery for a variety of diagnoses.

Intraoperative observations of cochlear nerve action potential amplitude and latency were recorded. Preoperative and 1-month postoperative audiograms were compared to assess the degree of hearing preservation. Postoperative facial nerve function was assessed using the House-Brackmann method.

Good auditory function was preserved in four of eight acoustic tumors, with poor hearing preserved in two additional patients. Good auditory function was preserved in the remaining ten patients. Cochlear nerve action potential amplitudes between 5 and 70 microV were recorded. Postoperative facial nerve function was House-Brackmann class I-II in all 18 patients.

The authors find this new electrode to be safe and effective for monitoring cochlear nerve function during cerebellopontine angle surgery.