Intraoperative facial nerve monitoring in parotid gland surgery

Abstract

To re-evaluate the value and the methods of intraoperative facial nerve monitoring in parotid gland surgery. Sixty-five cases received intraoperative facial nerve monitoring in parotidectomy (test group) since 2000 - 2008. The facial nerve was identified through central trunk method (n = 18), branch method (n = 35) and mixed method (n = 12). Most patients accepted general anesthesia by incubation. The operating duration and minimum electronic stimulation threshold values of EMG in evoked facial muscle were recorded. Facial nerve was identified though branch method (n = 44) and no intraoperative facial nerve monitoring was performed in parotidectomy (control group). There were four cases (6.1%) of mild temporary paralysis and no permanent post-operative paralysis of facial nerve in the test group. The average operating duration was 1.8 hour. The minimum reactive electronic stimulation threshold of EMG in evoked facial muscle was 0.08 mA. The range of suitable electronic stimulation threshold of EMG was from 0.2 mA to 1.0 mA. While there were nine cases (20.5%) of mild temporary paralysis and two cases (4.5%) of permanent post-operative paralysis of facial nerve in the control group and the average operating duration was 3.0 hours. Intraoperative facial nerve monitoring (IFNM) in parotidectomy can assist a surgeon to confirm and identify the facial nerve and exercise precautions so as to shorten operating duration and prevent potential surgical complications.