Vagus Nerve Stimulation in the Carotid Triangle: An Effective Method for Monitoring the Recurrent Laryngeal Nerve in Thyroid and Parathyroid Surgery

Our objective is the description of the technique of vagus nerve stimulation in carotid triangle in order to monitor the recurrent laryngeal nerve (RLN) during thyroid and parathyroid surgery. We stimulated the vagus nerve in the carotid triangle during 150 thyroid or parathyroid surgeries using a monopolar electromyography electrode inserted under the mastoid process towards the jugular foramen as a cathode, and using another subdermal electrode in the mastoid as an anode. Another complementary method of vagus stimulation was achieved with a pair of subdermal electrodes, placing the cathode at the mandibular angle and the anode at the mastoid. In all patients, compound muscle action potential (CMAP) was recorded in the vocal cords with both stimulation techniques, allowing semi-continuous monitoring to be carried out. Intraoperative lesions were detected in 16 of the cases; 9 of them were transient with CMAP recovery achieved when modifying surgical maneuvers. Vagus nerve stimulation in the carotid triangle is a reliable technique for monitoring the RLN in thyroid surgery. Vagus nerve stimulation in the carotid triangle is effective and safe for RLN monitoring, and it is a clear alternative to direct continuous stimulation of the nerve that by contrast requires its dissection in the carotid sheath.