Intraoperative facial nerve monitoring in parotidectomy: A systematic review of its predictive value.

ObjectiveThe purpose of this study was to investigate the relationship between intraoperative facial nerve monitoring parameters and postoperative facial nerve function during parotid surgeries.MethodsRegistered in PROSPERO, a comprehensive search was conducted in PubMed, Embase, Web of Science, and the Cochrane Library for literature published between 1990 and 2024. Studies reporting the relationship between intraoperative facial nerve monitoring parameters and facial nerve outcomes following parotidectomy were included. Owing to the limited number of studies and heterogeneity, the findings were summarized using a narrative synthesis.ResultsA total of 8 studies, involving 632 participants, were included, among whom 193 developed postoperative facial palsy. Five studies reported that a reduction in amplitude or an increase in threshold was associated with postoperative facial dysfunction.ConclusionCurrent evidence does not provide conclusive support for the predictive value of intraoperative facial nerve monitoring parameters in postoperative facial nerve function. However, given its established protective role and some reported findings (e.g. >50% amplitude drop associated with severe palsy), continued use of intraoperative facial nerve monitoring appears reasonable.