Efficacy of Intraoperative Facial Nerve Monitoring in Parotidectomy: A Systematic Review and Meta-Analysis

Introduction: Facial nerve dysfunction is a significant complication of parotidectomy, with intraoperative facial nerve monitoring (FNM) widely used to mitigate this risk. This systematic review and meta-analysis updates the 2015 review by Sood et al., incorporating recent data (1970–2025) to evaluate the efficacy of FNM in reducing immediate and permanent postoperative facial nerve weakness.

Methods: This systematic review and meta-analysis evaluated the impact of intraoperative facial nerve monitoring (FNM) on outcomes in primary parotidectomy for benign or malignant parotid gland diseases. Data from 1970–2025 were retrieved from PubMed, focusing on studies comparing surgeries with and without FNM and reporting facial nerve dysfunction (House-Brackmann grade ≥2). Eleven studies with 1101 patients (622 with FNM, 479 without) met inclusion criteria. Conducted in tertiary care centers, these studies analyzed demographics, disease severity, surgical approach, and FNM use. Primary and secondary endpoints were immediate and permanent facial nerve dysfunction. Study quality, bias, heterogeneity (I²), pooled odds ratios (ORs), and the number needed to monitor (NNM) quantified FNM’s benefit.

Results: The meta-analysis included 622 patients in the FNM group and 479 in the control group. FNM significantly reduced the risk of immediate facial nerve weakness (OR = 0.385, 95% CI = 0.293–0.505, p < 0.01, I² = 38%) and permanent weakness (OR = 0.316, 95% CI = 0.196–0.509, p < 0.01, I² = 0%).

Conclusions: This study confirms the efficacy of intraoperative FNM in reducing both immediate and permanent facial nerve dysfunction after primary parotidectomy. Unlike prior reviews focused on immediate outcomes, this analysis demonstrates protective effects for both short- and long-term facial nerve function, with minimal heterogeneity (I² = 38% for immediate, 0% for permanent weakness). These findings support FNM as a standard approach for optimizing surgical outcomes in parotidectomy.