Outcome of Postoperative Facial Nerve Function Following Electromyographic Facial Nerve Monitoring During Parotidectomy for Benign Lesions: a Retrospective Study

Does use of Facial nerve monitors during parotidectomy decrease incidence of facial paralysis/paresis without use of facial paresis? This study was done to compare the incidence, grade and risk factors of facial palsy in patients undergoing parotidectomy for benign parotid lesions with and without use of facial nerve monitor. This is a retrospective study. Eighty parotid patients operated for benign parotid lesions from 2013 to 2020 were retrospectively analysed. Demography details, history of the patients, history of addictions, clinical examination findings, investigation findings like the biopsy report, FNAC report, imaging i.e., CT / MRI / USG, use of intraoperative facial nerve monitor, time taken to identify the facial nerve, postoperative facial nerve palsy, facial nerve stimulation test and recovery time were analysed. Fifty patients were operated without use of facial nerve monitor, and 30 patients were operated using facial nerve monitor. Postoperative facial nerve complications were seen in 28 out of 80 patients (35%). Postoperative facial nerve complications were observed in 5 out of 30 patients (20%) in whom facial nerve monitoring was used. Marginal mandibular nerve palsy was observed in 4 patients and 1 patient had weakness of both marginal mandibular and orbital branches. While in postoperative facial nerve complications were observed in 25 out of 50 patients (50%), marginal mandibular nerve palsy was observed in 15 patients (40%), grade 3 facial palsy was observed in 3 out of 50 patients (6%), and grade 4 facial palsy were observed in 2 out of 50 patients (4%). The use of intraoperative FNM significantly lowered the incidence of paralysis.