Facial Nerve Monitoring during Parotidectomy: A Systematic Review and Meta‐analysis

Abstract

Objectives: Determine the effectiveness of intraoperative facial nerve monitoring (FNM) in preventing immediate and permanent postoperative facial nerve weakness in patients undergoing primary parotidectomy. Methods: Systematic review and meta-analysis. A comprehensive literature search was conducted using the PubMed-NCBI database from 1970 to 2014. Acceptable studies included controlled series that evaluated facial nerve function following primary parotidectomy with or without FNM (intraoperative nerve monitor vs. control). Primary and secondary endpoints were defined as immediate postoperative and permanent facial nerve weakness (≥2 House-Brackmann score), respectively. Results: A total of 1414 articles were reviewed, resulting in 8 articles that met inclusion criteria. In total, 626 patients were included in the final meta-analysis. The incidence of immediate postoperative weakness following parotidectomy was significantly lower in the FNM group compared with the unmonitored group (22.4% vs 35.0%, P = .001). The incidence of permanent weakness was also lower, but this difference was not statistically significant (4.2% vs 7.6%, P = .10). The number of monitored cases needed to prevent 1 incidence of immediate postoperative facial nerve weakness was 8 given an absolute risk reduction of 12.6%. This corresponded to a 49% decrease in the incidence of immediate facial nerve dysfunction (odds ratio, 0.51; 95% confidence interval, 0.34 to 0.76, P = .001). Conclusions: In primary cases of parotidectomy, intraoperative facial nerve monitoring decreases the risk of immediate postoperative facial nerve weakness, but does not appear to influence the final outcome of permanent facial nerve weakness.