Utility of intraoperative neuromonitoring in detecting recurrent nerve's anatomical anomalies during thyroidectomy

Anatomical variations such as a non-recurrent laryngeal nerve (NRLN) are very rare (reported rates within 0.6-1% to the right side and only four cases to the left side) but they can lead to serious risk of nerve lesion during thyroidectomy. It is known that to prevent inferior laryngeal nerve lesions, it is mandatory to obtain a correct and wide exposure of the nerve during all kind of thyroid surgeries but in case of laryngeal nerve position anomalies, it is hard to achieve a safe nerve identification. Continuous intraoperative neuromonitoring (C-IONM) technology can detect the presence of NRLN. In this study we present seven cases of NRLN incidentally found during our last 10-year experience, in a total of 1074 procedures, including total thyroidectomy and lobectomy. Three out of seven cases were identified with the help of C-IONM. On the other hand, the other four cases of non-recurrent laryngeal nerve were identified during an extensive dissection of the thyroid lodge. We registered no nerve palsy in the group of patients who underwent surgery with the help of C-IONM, while we had two nerve palsies (out of four cases) in the group of patients without the help of C-IONM. In our experience we also registered a reduction of surgery time when we used the C-IONM. In our opinion C-IONM is a safe method to discover anatomical anomalies such as a non-recurrent laryngeal nerve and may help to reduce nerve palsy rate.