Abstract: Objective To verify the safety and feasibility of modified transcricothyroid electromyography for intraoperative nerve monitoring in total areolar endoscopic thyroid surgery.Methods 50 patients who were going to undergo total areola endoscopic thyroidectomy were recruited.At the same time of using the surface electrode of endotracheal intubation,a paired needle electrode was inserted between the cricothyroid muscle and thyroid cartilage under the guidance of the endoscopy.The standard four-step method(V1-R1-R2-V2) was used to locate,expose and evaluate the function of the recurrent laryngeal nerve during the operation,and the electronic fiber laryngoscope was used to evaluate the vocal cord movement before and after the operation. Results A total of 50 recurrent laryngeal nerves were monitored during the operation,and effective electromyography(EMG) signals were successfully recorded through cricothyroid needle electrode and endotracheal intubation surface electrode.The EMG signal amplitude of the cricothyroid needle electrode is larger than that of the endotracheal intubation surface electrode[V1/R1=(2 179.3±1 252.3/2 304.8±1 644.0)μV vs (937.2±612.8/1 088.9±613.5)μV].There was no loss of EMG signal during the operation,and there was no obvious change of EMG signal before and after tumor resection.The electronic fiber laryngoscope indicated normal vocal cord movement before and after the operation.Conclusion Improved transcricothyroid EMG signal recording method is safe and feasible for neuromonitoring in total areola endoscopic thyroidectomy.It has the advantages of convenient installation,strong EMG signal,no influence of tracheal intubation position and little influence on endoscopic operation.

Key words: endoscopic thyroidectomy via areola approach(ETA), intraoperative neuromonitoring, needle electrode, recurrent laryngeal nerve