Experience with intraoperative neuromonitoring of the recurrent laryngeal nerve improves surgical skills and outcomes of non-monitored thyroidectomy

Purpose: Intraoperative neuromonitoring (IONM) can serve as a tool to increase skills in recurrent laryngeal nerve (RLN) identification and complete removal of thyroid tissue. The aim of this study was to validate this hypothesis.

Methods: This prospective study involved 632 patients (1161 RLNs at risk) who underwent thyroid surgery in 2011-2014. Although IONM was not used until 2012, this prospective study started on 1 January 2011. The three participating surgeons knew about the study before that date and that the rate of RLN identification would be carefully measured in total and near-total surgery. Solely, visual identification of the RLN was used throughout 2011. IONM was introduced as a training tool in 2012-2014 for the first 3 months of each year. In the remaining months, thyroid operations were performed without IONM. Outcomes of non-monitored thyroid operations were compared before (01-12/2011) vs. after (04-12/2012-2014) 3 months of exposure to IONM yearly (01-03/2012-2014). The rate of RLN identification was assessed in total and near-total thyroidectomies and in totally resected lobes in Dunhill's operation. The prevalence of RLN injury and the utilization of total thyroidectomy were evaluated.

Results: In 2011, the rate of successful RLN visual identification in total and near-total thyroidectomies and in totally resected lobes in Dunhill's operation was 45.71 %. After the introduction of IONM in 2012-2014, in the procedures performed without IONM, the rate was 86.66, 90.81, and 91.3 %. The prevalence of RLN injury in 2011 was 6.8 %, while in the years following the introduction of IONM, it was 3.61, 2.65, and 1.45 %. Utilization of total thyroidectomy increased from 47.9 % in 2011 to 100 % in 2014.

Conclusions: Experience with IONM led to an increase in RLN identification (p < 0.0001), a decrease of RLN injury (p < 0.05), and an increase in the safe utilization of total thyroidectomy (p < 0.0001) in non-monitored thyroid operations. IONM is a valuable tool for surgical training.