Intraoperative Neuromonitoring of the External Branch of the Superior Laryngeal Nerve During Thyroid Surgery

Abstract

Thyroid gland surgeries are among the most common surgical interventions worldwide and are considered by many surgeons as a relatively easy and safe procedure. But the number of complications still remains significant with unacceptable and unpleasant consequences for the patients. Among them, the most significant are postoperative hypoparathyroidism and the injuries of the laryngeal nerves - the recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (EBSLN). Nowadays, the surgical anatomy of the recurrent laryngeal nerves and the surgical approach to them are described in detail in the medical literature and their damages are perhaps the most known and discussed complications. EBSLN injury leads to paralysis of the cricothyroid muscle (CTM) and often remains unseen due to a lack of clear laryngoscopic markers. The main postoperative symptoms are accompanied mostly by qualitative voice disturbances of the patients. A relatively new method for timely assessment of the risk of iatrogenic lesions of the laryngeal nerves in thyroid surgery is the intraoperative neuromonitoring (IONM). The method emerged as the gold standard of care for prevention of RLN, and lately its application on EBSLN is subject of detailed analysis. This creates a need to assess the method and develop a friendly practice system for its clinical application.