Effectiveness of Intraoperative Neuromonitoring of External Branch of Superior Laryngeal Nerve in Thyroid Surgery

With increased interest in quality of life after thyroidectomy, preservation of proper vocal cord function and voice quality is an important issue in thyroid surgery. External branch of the superior laryngeal nerve (EBSLN) and recurrent laryngeal nerve (RLN) are crucial organs for innervation and integration of laryngeal muscular system. The EBSLN innervates the cricothyroid muscle (CTM), which is important in adjusting the tension and length of the vocal cords. Damage of the EBSLN leads to CTM dysfunction, resulting in difficulty with high pitch phonation and decreased pitch range and reduced voice projection, which are important for voice professionals. As the intraoperative neuromonitoring was utilized as an adjunctive and objective tool to confirm the nerve presence and integrity, application of the intraoperative neuromonitoring system to confirm EBSLN function pre- and post-dissection of the upper thyroid pole can be regarded as an effective method to preserve cricothyroid muscle function. However, it remains unclear whether there is any intraoperative neuromonitoring techniques-added value to the clinical outcome of thyroidectomy in terms of identification of EBSLN and preserved voice performance. Therefore, this study could provide strong evidence of the application of the intraoperative neuromonitoring during thyroid surgery to identify and preserve EBSLN function.