The Value Of Intraoperative Neuromo-Nitoring On The Protection Of Recurrent Laryngeal Nerve Injury During ThyRoid Reoperation:A Meta-analysis

Objective: To evaluate the protective value of intraoperative nervemonitoring(IONM)for recurrent laryngeal nerve(RLN)injury in thyroid reoperations.Methods: A systematic literature search was conducted in the MEDLINE(PubMed),Cochrane Library,Embase and China Knowledge Network(CNKI),Wanfang database,VIP databases for studies published up to February 2019.The retrieved literatures were about the clinical comparative study of IONM and RLN visualization in protecting RLN during thyroid reoperations.All studies calculated the injury rate of RLN were on the basis of the nerves at risk(NAR).The search was followed the inclusion and exclusion criteria.Comparisons of temporary,permanent,overall RLN injury rate and operation time between IONM group and visualization group were described.Besides,we also analyzed the subgroup of the unilateral and bilateral RLN injury.All data were analyzed by RevMan 5.3 software.Publication bias and sensitivity analysis was assessed by Stata15.1 software.Results:1.A total of 11 literatures were included in this study.The total number of nerves at risk was 3741.Compared with RLN visualization group,the application of IONM in thyroid reoperations could significantly reduce the permanent injury rate of RLN(2.32% vs 2.70%,RR: 0.63,95% CI: 0.41-0.98,P = 0.04)and the overall injury rate(4.64% vs 8.80%,RR: 0.62,95% CI: 0.38-0.99,P = 0.04).2.Compared with RLN visualization group,the unilateral RLN injury was not decreased significantly in IONM group(4.03%vs4.87%,RR: 0.54,95% CI: 0.06-4.78,P = 0.58);Besides,the difference of the bilateral RLN injury was equivalent to an absolute risk reduction of 2.17‰(5.54 ‰vs7.71‰)between two groups,but there was no significant difference(RR:0.80,95%CI:0.20~3.14,P=0.74).3.There was no statistical difference in operation time between IONM group andRLN visualization group(MD:-2.51,95% CI:-8.44-3.43,P=0.41).4.According to all studies,sensitivity analysis was carried out by eliminating one by one.The results did not change significantly,indicating that the stability of the results was good.Begg rank correlation method was used to quantify funnel plots.No significant publication bias was found(P > 0.1).Conclusions: The application of IONM in thyroid reoperations has a protective value for RLN injury.Compared with the recurrent laryngeal nerve visualization,IONM can significantly reduce the permanent injury rate and overall injury rate of RLN,but it can not reduce the temporary injury rate of RLN and shorten the operation time.Further expansion of the sample size and an in-depth study of risk stratification is required.