Electromyographic Facial Nerve Monitoring During Parotidectomy for Benign Lesions Does Not Improve the Outcome of Postoperative Facial Nerve Function: A Prospective Two-Center Trial

Objectives/Hypothesis: To analyze the benefit of electromyographic (EMG) neuromonitoring during primary surgery on benign parotid lesions for postoperative facial function compared to visual observation only. Study Design: Prospective controlled clinical two-center trial. Methods: Using an operation microscope, 100 parotidectomies in 96 patients were performed: 50 procedures with a continuous EMG monitoring plus visual facial observation (EMG group), and 50 procedures with only visual facial control (control group). The rate of postoperative facial weakness was detected. Patients with postoperative facial paralysis were followed up until total recovery or defective healing by repeated EMG examinations. Results: Seventy-nine superficial and 21 total parotidectomies were performed. Histological analysis found pleomorphic adenoma in 38 patients, cystadenolymphoma in 39, and chronic parotitis in 18. Immediate postoperative facial paralysis was evident in 41 patients. Six patients had permanent paralysis; in this group definitive defective healing was detected by EMG in five cases. EMG was not classifiable in one case. Intraoperative EMG monitoring had no significant effect on immediate postoperative or definitive facial outcome (P=.23 and P=.45, respectively). The duration of superficial, but not of a total parotidectomy, was diminished in the EMG group (P=.02 and P=.61, respectively). This result was independent of the specimen's histology. Conclusions: EMG monitoring in parotid surgery in addition to visual facial observation did not diminish either the incidence of postoperative facial paralysis or the final facial outcome. Nevertheless, the duration of surgery for superficial parotidectomy could be reduced by using EMG monitoring.