Facial nerve dysfunction after superficial parotidectomy with or without continuous intraoperative electromyographic neuromonitoring: a prospective randomized pilot study

PurposeThere are no randomized trials comparing the incidence or severity of facial nerve dysfunction after superficial parotidectomy with or without continuous intraoperative electromyographic neuromonitoring. This pilot study aimed to assess the variability in outcomes to help determine the needs and possible ethical issues in a full-scale study.MethodsProspective randomized pilot study comparing the incidence and grade of facial nerve dysfunction among 106 patients subjected to superficial parotidectomy with or without continuous four channels electromyographic neuromonitoring (52 monitored patients and 54 controls).ResultsThe incidences of immediate (38.3% vs. 51.8%, p=0.1) and late facial dysfunction, up to 180days following surgery, (3.8% vs. 5.5%, p=0.4) were similar between monitored patients and controls. Immediate facial nerve dysfunction with a House-Brackmanngrade III was more frequent among the non-monitored patients (57.8% vs. 30%, p=0.2), and outcomes were significantly poorer in this group (mean sum score of 68.7 vs. 81.5, p=0.002), when assessed with the regional Sunnybrook scale. A full-scale prospective randomized study to detect a significant reduction in the incidence of immediate facial nerve dysfunction with the use of continuous intraoperative electromyographic neuromonitoring, with 80% power and a 5% significant level, would require 560 patients allocated to the monitored and control groups. Considering a mean rate of 30 patients/year/center, such a study would require the participation of five centers for 4years.ConclusionsIn the present pilot study, the incidences of immediate and late facial nerve dysfunction were similar between patients with benign parotid tumors subjected to superficial parotidectomy with or without continuous intraoperative electromyographic neuromonitoring. However, immediate facial dysfunction was more severe among the non-monitored patients.