Meta-analysis Of Intraoperative Neuromonitoring Of External Branch Of The Superior Laryngeal Nerve In Thyroidectomy

PurposeThe effectiveness of intraoperative neuromonitoring(IONM)of the external branch of the superior laryngeal nerve(EBSLN)in thyroidectomy lacks sufficient evidence-based medical evidence.In this study,we use the evidence-based method to explore the significance of IONM in the identification and protection of the EBSLN.MethodsA systematic literature search of randomized controlled trials(RCTs)and before-after studies was conducted in the PubMed,EMBASE,Cochrane Library,Web of Science,China Knowledge Network Database and Wanfang databases for studies published until March 1,2019.All data were analysed using Review Manager 5.3 software.Results1.A total of 15 studies including 2136 patients with 3403 EBSLNs at risk met the inclusion criteria.There are 14 English studies and 1 Chinese study including 7 before-after studies and 8 randomized controlled studies.2.A total of 12 studies assessed the identification rate of EBSLN with IONM versus without IONM in thyroid surgeries.The identification rate of EBSLN was significantly higher in thyroidectomy conducted with IONM than in that conducted without IONM(95.07%vs.67.97%,RR=1.76,95%CI=1.48-2.10,P<0.05).Significant heterogeneity was observed(I~2=98%).3.Five RCTs assessed the rate of overall EBSLN palsy.The overall EBSLN palsy rate was significantly lower in thyroidectomy conducted with IONM than in that conducted without IONM(1.35%vs.8.54%,RR=0.18,95%CI=0.08-0.41,p<0.0001).No significant heterogeneity was observed(I~2=0%).4.Three RCTs assessed rate of transient EBSLN palsy.IONM was significantlyassociated with a reduction in transient EBSLN palsy(1.11%vs.5.56%,RR=0.25,95%CI=0.08-0.79,p=0.02)without significant heterogeneity(I~2=0%).5.Three RCTs assessed rate of permanent EBSLN palsy.The rates of permanentEBSLN palsy with and without IONM did not differ significantly(0.37%vs.2.29%,RR=0.35,95%CI=0.07-1.70,p=0.19).No significant heterogeneity was found(I~2=0%).ConclusionIONM is associated with an increase in the identification rate of EBSLN and areduction in overall and transient EBSLN palsy in thyroid surgery.However,there was no significant difference in the rate of permanent EBSLN palsy compared to non-IONM surgery.