The Impact of Intraoperative Facial Nerve Monitoring During Parotidectomy on Postoperative Facial Nerve Function: A Systematic Review and Meta‐Analysis

BACKGROUND: Facial nerve dysfunction (FND) remains a key complication of parotidectomy. Intraoperative facial nerve monitoring (IOFNM) aims to assist facial nerve identification and preservation; however, its effect on postoperative FND remains unclear. This systematic review and meta-analysis evaluated the effect of IOFNM on facial nerve outcomes post-parotidectomy. METHODS: PubMed, Embase, MEDLINE (Ovid) and CINAHL were searched from inception to August 22nd, 2025. Primary outcomes were immediate and permanent FND, assessed using the House-Brackmann grading system. Retrospective and prospective double-arm studies were included. Screening, data extraction and risk of bias assessment (ROBINS-I/RoB-2) were performed independently. Random-effects meta-analyses were conducted using restricted maximum likelihood. Certainty of evidence was assessed using GRADE. RESULTS: Twelve studies (n = 2401) met inclusion criteria. Meta-analysis of ten studies (n = 2042) demonstrated significantly lower odds of immediate FND with IOFNM (OR 0.48; 95% CI: 0.31-0.72). This reduction occurred in superficial (OR 0.51; 95% CI: 0.30-0.87), but not total parotidectomy (OR 0.93; 95% CI: 0.42-2.08). Analysis of six studies (n = 981) found no significant difference in permanent FND (OR 0.84; 95% CI: 0.44-1.60). Four studies (n = 1369) reported operative time, with a non-significant reduction using IOFNM (MD -8.82 min; 95% CI: -18.78 to +1.13). CONCLUSION: IOFNM is associated with lower odds of immediate postoperative FND, particularly in superficial parotidectomy, but its effect on permanent FND and total parotidectomy remains uncertain. IOFNM use should be tailored to surgical complexity and surgeon experience, with high-quality prospective studies needed to clarify its clinical utility.