Background: During thyroid surgery, extreme caution must be taken not to harm the recurrent laryngeal nerve to avoid vocal cord palsy. A non-recurrent laryngeal nerve (NRLN) is a rare anatomical variation that is extremely vulnerable during thyroid surgery.
Methods: Description of two NRLN during thyroid surgery discovered early by using continuous intra-operative vagal nerve neuromonitoring and review of the literature.
Results: During thyroid surgery, we use continuous intra-operative vagal nerve neuromonitoring starting with checking vagal nerve signals. It is essential to start stimulation in the most proximal portion of the carotid sheath. An absent pre-dissection signal on the right vagal nerve with a positive signal on the left vagal nerve indicates a non-recurrent course of the right laryngeal nerve. Post-operatively computed tomography scan (CT-scan) was performed and showed an associated extra-anatomical course of the subclavian artery also known as an arteria lusoria.
Conclusion: The NRLN is an important surgical challenge because unilateral palsy can lead to permanent hoarseness. This anomaly emphasizes the importance of a thorough surgical dissection and the use of intra-operative vagal nerve neuromonitoring. Our method of continuous intra-operative vagal nerve monitoring makes it possible to predict a non-recurrent laryngeal nerve in an early stage during surgery.
Keywords: Non-recurrent laryngeal nerve; arteria lusoria; intraoperative vagal neuromonitoring; thyroid surgery; thyroidectomy.