Systematic review with meta-analysis of intraoperative neuromonitoring during thyroid reoperation

Objective: Recurrent laryngeal nerve (RLN) injury is a serious complication during thyroid reoperation. Intraoperative neuromonitoring (IONM) is one of the means to reduce RLN paralysis. However, the role of IONM during thyroidectomy is still controversial. The aim of this study was to assess whether the IONM could reduce the incidence of RLN injury during thyroid reoperation. Methods: We performed a systematic review to identify studies in English language which were published between January 1, 2004, and March 25, 2023 from PubMed, EMBASE, and Cochrane Library, comparing the use of IONM and Visualization Alone (VA) during thyroid reoperation. The RLN injury rate was calculated in relation to the number of nerves at risk. All data were analyzed using Review Manger (version 5.3) software. The Cochran Q test (I2 2 test) was used to test for heterogeneity. Odds ratios were estimated by fixed effects model or random effects model, according to the heterogeneity level. Results: Eleven studies (3655 at-risk nerves) met criteria for inclusion. Data presented as odds ratio(OR) and their 95% confidence intervals(CI). Incidence of overall, temporary, and permanent RLN injury in IONM group were, respectively, 4.67%, 4.17%, and 2.39%, whereas for the VA group, they were 8.30%, 6.27%, and 2.88%. The summary OR of overall, temporary, and permanent RLN injury compared using IONM and VA were, respectively, 0.68 (95%CI 0.4-1.14, p=0.14), 0.82 (95%CI 0.39-1.72, p=0.60), and 0.62 (95%CI 0.4-0.96, p=0.03). Conclusions: The presented data showed benefits of reducing permanent RLN injury by using IONM, but without statistical significance for temporary RLN injury.