Visual identification and neuromonitoring vs. no sighting the external branch of the superior laryngeal nerve in thyroid surgery: a randomized clinical trial

To evaluate the incidence of external branch of the superior laryngeal nerve (EBSLN) injuries after thyroid surgical procedures with or without the functional and visual identification of the EBSLN before ligation at the superior thyroid pole. Patients with papillary thyroid carcinoma (PTC) enrolled from a single tertiary referral academic medical center were assigned to functional and visual identification of EBSLN group (study group) or no identification of EBSLN group (controlled group). The main outcome measures were the incidence of EBSLN injury detected by the intraoperative neuromonitoring and Voice Handicap Index-10 (VHI-10) and Impairment Index-5 (VII-5) valuation questionnaires. Postoperative complications were recorded. A total of 140 (50.4%) patients were enrolled in study group and 138 (49.6%) in controlled group. In the study group, 110 (39.3%) EBSLNs were direct visual recognized and 170 (60.7%) nerves were visually identified with the help of neuromonitoring. Three patients in the study group and two patients in the controlled group were diagnosed with vocal cord paralysis. Six (4.4%) patients in the identification group and 37 (27.2%) patients in the no identification group presented no response from the stimulation of sternothyroid–laryngeal triangle. The VII-5 scores of the study group were significantly higher than those of the controlled group at one and three months postoperatively (P = 0.024 and P = 0.034). With significant lower scores of VII-5 and VHI-10, functional and visual identification of EBSLN might be necessary during thyroid surgery to protect the structural integrity and motor activity of the nerve.