Randomized clinical trial of visualization versus neuromonitoring of recurrent laryngeal nerves during thyroidectomy

Background: The aim of this study was to test the hypothesis that identification of the recurrent laryngeal nerve (RLN) during thyroid surgery reduces injury, and that intraoperative nerve monitoring may be of additional benefit. Methods: One thousand consenting patients scheduled to have bilateral thyroid surgery were randomized to standard protection or additional nerve monitoring. The primary outcome measure was prevalence of RLN injury. Results: Of 1000 nerves at risk in each group, transient and permanent RLN injuries were found respectively in 38 and 12 nerves without RLN monitoring (P = 0.011) and 19 and eight nerves with RLN monitoring (P = 0.368). The prevalence of transient RLN paresis was lower in patients who had RLN monitoring by 2.9 per cent in high-risk patients (P = 0.011) and 0.9 per cent in low-risk patients (P = 0.249). The negative and positive predictive values of RLN monitoring in predicting postoperative vocal cord function were 98.9 and 37.8 per cent respectively. Conclusion: Nerve monitoring decreased the incidence of transient but not permanent RLN paresis compared with visualization alone, particularly in high-risk patients. Registration number: NCT00661024 (http://www.clinicaltrials.gov).