Intraoperative Neuromonitoring in Thyroid Surgery: A Systematic Review

Abstract

This study aimed to assess the efficacy of intraoperative neurophysiologic monitoring (IONM) in preventing recurrent laryngeal nerve palsy (RLNP) during thyroid surgery. When IONM results in false positives, it seeks to evaluate contributing factors. A systematic review was conducted gauging the predictive power of neuromonitoring in determining RLN function intraoperatively, its reductions of temporary and permanent RLNP rates, and surgeons' response to the technology. MEDLINE, EMBASE, and PubMed were searched for RLN monitoring in thyroid surgery following a set of inclusion/exclusion criteria. Seventeen studies comparing thyroid surgery with and without IONM were reviewed, including 30,926 patients. Selected studies were pooled to gage the predictive power. Mean specificity of IONM in identifying functional nerves was 90.24 % among 7366 nerves at risk (NAR). However, mean positive predictive power (PPP) was low, and both specificity and PPP varied substantially when stratified by risk levels. Among the pooled studies focusing on IONM efficacy-there were 44,575 NAR, of which (57.98 %) were operated on with IONM and 18,732 (42.02 %) without (control). The rates of overall RLNP per NAR were 3.18 and 3.83 % for the IONM group and control, respectively. There is no statistically significant difference between IONM and control, a conclusion supported by qualitative analysis from many individual studies. IONM is not recommended as the standard of care for thyroidectomies. Low PPP of IONM and complications associated with IONM-assisted thyroidectomies may be attributed to either the absence of a standardized negative-signal cutoff value or injury from intubation.