ABSTRACT
Objective:To investigate the efficacy of routine exposure versus neuromonitoring of the external branch of the superior laryngeal nerve (EBSLN) in thyroid cancer surgery. Methods:The clinical data of 500 patients who underwent open thyroid cancer surgery in the Department of Breast and Thyroid Surgery, People's Hospital of Quzhou from July 2017 to June 2020 were retrospectively analyzed. These patients were divided into a monitoring group ( n = 300) and an unmonitored group (control group) ( n = 200) according to whether neuromonitoring was performed during surgery. In the control group, the EBSLN was routinely exposed during the surgery for naked observation. In the monitoring group, the EBSLN was monitored. The Voice Handicap Index score, vocal cord function, and serum levels of parathyroid hormone and calcium ion were compared between the two groups before and after surgery. All patients were followed up for 1 year to observe injury to the EBSLN, parathyroid gland injury, and hypocalcemia. Results:In the monitoring group, operative time (112.32 ± 10.42) minutes, intraoperative blood loss (10.58 ± 5.04) mL, time to extubation (2.07 ± 0.54) days, postoperative drainage flow (10.55 ± 3.58) mL, and postoperative hospital stay (3.03 ± 1.03) days were significantly shorter and less compared with the control group ( t = 18.68, 15.09, 15.24, 32.98, 27.37, all P < 0.001). Compared with before surgery, normalized noise energy, amplitude perturbation, fundamental frequency perturbation, and fundamental frequency value in each group were significantly decreased after surgery, harmonic to noise ratio and the Voice Handicap Index were significantly increased after surgery. These indices were more obviously improved in the monitoring group compared with the control group ( t = 43.31, 27.10, 46.45, 37.11, 8.97, all P < 0.001). Compared with before surgery, serum levels of parathyroid hormone and calcium ion in each group were significantly decreased after surgery. After surgery, serum levels of parathyroid hormone and calcium ion in the control group were significantly lower than those in the monitoring group ( t = 41.14, 5.99, both P < 0.001). The incidence of complications in the monitoring group [4 cases of hypocalcemia (1.33%), 0 cases of parathyroid injury (0.00%), 8 cases of injury to the EBSLN] was significantly lower than that in the control group ( χ2 = 73.41, 74.17, 76.29, all P < 0.001). Conclusion:Neuromonitoring of the EBSLN during open thyroid cancer surgery can effectively improve patient voice and vocal cord function, reduce the rate of injury to the EBSLN, and has a clinical application value.