Abstract: ［Abstract］  Objective〖HTSS〗〓To explore the normality of the recurrent laryngeal nerve in the thyroid surgery to monitor the appropriate intensity of the stimulus and the latency, in order to evaluate the clinical value of intraoperative laryngeal protection and predict the degree of nerve injury.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓Prospective collection of clinical data from 35 patients who underwent thyroid surgery and the use of intraoperative nerve monitoring, with 45 lesions with risk of injury. According to the normalized neural monitoring process, the recurrent laryngeal nerve was directly stimulated with the current intensity of 0.1-3 mA, and the amplitude of the electromyographic signal was recorded. The optimal current intensity was measured at each stage of the intraoperative nerve monitoring. With 1 mA current to stimulate the recurrent laryngeal nerve into the throat, from the larynx 1 cm, 2 cm away from the larynx, record the corresponding latency, and to calculate the conduction velocity of recurrent laryngeal nerve.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓Stimulation current greater than or equal to 0.5 mA, the stimulation of the recurrent laryngeal nerve in the nerve monitor are displayed on the amplitude and the maximum amplitude, and these amplitudes are stabie. When the stimulus current is less than 0.5 mA, the amplitude is lowered to the point where it cannot be read out as the stimulus current decreases. With 1 mA current to stimulate the 42 recurrent laryngeal nerves into the throat, from the larynx 1 cm, 2 cm away from the throat, respectively, we get the latency t0, t1, t2. When the conduction distance is 1cm, the conduction time is(t1-t0),(t2-t1),(t2-t0) / 2 respectively. There was no significant difference in the conduction time and the conduction velocity between the three groups.
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓The optimal current stimulation intensity is 0.5 mA, also it is the threshold. We identified the latency of the recurrent laryngeal nerve, and calculated the conduction velocity of recurrent laryngeal nerve is 4 cm/ms. We can calculate the distance from the damage point to the effector according to the latency when the recurrent laryngeal nerve is damaged.

Key words: recurrent laryngeal nerve injuries, thyroidectomy, neural conduction