Intraoperative recurrent laryngeal nerve monitoring versus visualisation alone - A systematic review and meta-analysis of randomized controlled trials

Background: Intraoperative nerve monitoring (IONM) is perceived to reduce recurrent laryngeal nerve injury (RLNI) compared to RLN visualisation alone (VA). We performed a meta-analysis of randomized controlled trials (RCTs) to establish the value of using IONM instead of RLN VA for patients undergoing thymidectomy. Methods: A meta-analysis of RCTs was performed as per PRISMA guidelines. RLNI rates were expressed as dichotomous variables and pooled as odds ratios (OR) and associated 95% confidence intervals (CI) using the Mantel-Haenszel method. Results: Eight RCTs with 2521 patients with 4977 nerves at risk were included. Overall, 49.8% of RLNs underwent IONM (2480/4978) and 50.2% underwent VA (2497/4978). Overall RLNI rates were higher for VA (VA: 3.2% (80/2497) vs. IONM: 2.3% (58/2480), OR: 0.72, 95% CI: 0.51-1.02, P = 0.060, I-2 = 9%). Permanent RLNI rates were slightly higher for VA (VA: 0.6%, (12/2497) vs. IONM: 0.5%, (12/2480), OR: 0.76, 95% CI: 0.36-1.59, P = 0.470, I-2 = 0%). Conclusion: When compared to VA alone, using IONM failed to significantly reduce RLNI rates during thyroid surgery.