Vagus Nerve Injury during Continuous Intraoperative Neuromonitoring (cIONM) for Thyroid Surgery: Assessment of Severity

• Published in: IIUM Medical Journal Malaysia
• Main Author: Rohaizak M.; Nor Faezan A.R.; Suraya O.; Shahrunniza A.S.
• Format: Article
• Language: English
• Published: International Islamic University Malaysia 2021
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85111352533&doi=10.31436%2fimjm.v20i3.1614&partnerID=40&md5=36ff76c362a400af11af0b7b72dbdfad
• ISSN: 27352285
• DOI: 10.31436/imjm.v20i3.1614

INTRODUCTION: Vocal cord palsy is one of the major concerns in thyroid surgery especially among professional voice users. Continuous intraoperative neuromonitoring (cIONM) allows real-time nerve function during surgery that will reduce the risk of injury. The procedure involved is not without complication thus meticulous usage and strict adherence to standard operating procedure is of utmost importance. This study was aimed to investigate the potential morbidity of the procedure. MATERIALS AND METHODS: A prospective observational study was conducted on 20 patients who underwent routine thyroid surgery using cIONM. The procedure of cIONM adhered to the standard guidelines. Measurements of vagal stimulation were taken proximal (V3) and distal (V2) to the automatic periodic stimulation (APS) electrode to document any injury to the vagus nerve. Blood pressure and pulse rate were also documented throughout the surgery, in order to observe the physiological effect of the stimulation. The function of the vocal cord was assessed by pre and post-operative laryngoscopy. RESULTS: 18 patients with 29 nerves at risk were included as the vagal stimulation did not achieve the acceptable amplitude (500 mA) in two patients. There were drops of amplitude between V3 and V2 in 14 nerves at risks but there was no clinical evidence of palsy on laryngoscopy. There was also the fluctuation of mean arterial pressure and pulse rate but not significant enough to warrant intervention. CONCLUSION: The use of cIONM during thyroidectomy does exert a minimal effect on the vagus nerve. It is safe and able to help the surgeon identify and preserve the nerve function especially in difficult thyroidectomy. © 2021. All Rights Reserved.