Intraoperative monitoring of the recurrent laryngeal nerve by vagal nerve stimulation in thyroid surgery

• Published in: European archives of oto-rhino-laryngology Vol. 274; no. 1; pp. 421 - 426
• Main Authors: Farizon, Brigitte, Gavid, Marie, Karkas, Alexandre, Dumollard, Jean-Marc, Peoc’h, Michel, Prades, Jean-Michel
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2017
• Subjects: Action Potentials - physiology; Adolescent; Adult; Aged; Aged, 80 and over; Female; Head and Neck; Head and Neck Surgery; Humans; Laryngeal Muscles - innervation; Laryngeal Muscles - physiology; Male; Medicine; Medicine & Public Health; Middle Aged; Monitoring, Intraoperative - methods; Neurosurgery; Otorhinolaryngology; Postoperative Complications; Prospective Studies; Recurrent Laryngeal Nerve; Recurrent Laryngeal Nerve Injuries - prevention & control; Sensitivity and Specificity; Thyroid Gland - surgery; Vagus Nerve Stimulation; Vocal Cord Paralysis - etiology; Young Adult; Thyroid gland; Intraoperative monitoring; Thyroarytenoid muscle; Vagal nerve; Recurrent laryngeal nerve
• ISSN: 0937-4477; 1434-4726
• DOI: 10.1007/s00405-016-4191-2

The aim of the present study was to evaluate the thyroarytenoid muscle response during bilateral thyroid surgery using vagal nerve stimulation. 195 patients (390 nerves at risk) underwent a total thyroidectomy. The recurrent laryngeal nerve’s function was checked by analyzing the amplitude and the latency of the thyroarytenoid muscle’s responses after a vagal nerve’s stimulation (0.5 and 1 mA) using the NIM3 Medtronic system. All patients were submitted to preoperative and postoperative laryngoscopy. 20 patients get no thyroarytenoid muscle response to the vagal nerve stimulation, and 14 postoperative recurrent laryngeal nerve palsies were confirmed (3.8 %). Two palsies were present after 6 months (0.51 %). All the patients with muscle’s response have normal mobility vocal fold. The test sensitivity was 100 % and the test specificity was 98 %. Physiologically, the mean latencies of the muscular potentials for the right RLN were, respectively, 3.89 and 3.83 ms ( p  > 0.05) for the stimulation at 0.5 and 1 mA. The mean latencies for the left RLN were, respectively, 6.25 and 6.22 ms for the stimulation at 0.5 and 1 mA ( p  > 0.05). The difference of the latencies between the right and the left nerve was 2.30 ms (1.75–3.25 ms) with a stimulation of 0.5 or 1 mA ( p  < 0.05). Thyroarytenoid muscle’s response via a vagal nerve stimulation showed a functional asymmetry of the laryngeal adduction with a faster right response. Surgically, this method can predict accurately an immediate postoperative vocal folds function in patients undergoing a bilateral thyroid surgery.