Safety of high-current stimulation for intermittent intraoperative neural monitoring in thyroid surgery: A porcine model

Objectives During monitored thyroidectomy, displacement of the recurrent laryngeal nerve (RLN) or vagus nerve (VN) in some complicated cases can increase the risk of injury. Although increasing the stimulus current can facilitate nerve mapping and localization, the safety of a high-current stimulus remains unknown. Therefore, this study evaluated the safety of a high-current stimulus in a porcine model. Methods Short-duration (1 minute), high-current (3, 5, 10, 15, 20, 25, and 30 mA at 4Hz) stimulus pulses were repeatedly applied to the RLN or VN in six anesthetized piglets. The safety of the high-current stimulus pulses was assessed in terms of hemodynamic stability during VN stimulation and in terms of nerve function integrity after VN and RLN stimulation. Results During VN stimulation with a high-current stimulus pulse, sinus rhythms in all six piglets showed stable heart rates, and mean arterial pressure was unaffected. High-current stimulation of the VN and the RLN did not affect electromyography amplitude or latency. Conclusion This porcine study showed that applying a short-duration, high-current stimulus pulse to the VN or RLN during monitored thyroidectomy has no harmful effects. In clinical practice, a short duration of high-current stimulus can be applied to facilitate neural mapping, especially in patients with disoriented nerve positions. Level of evidence NA. Laryngoscope, 128:2206-2212, 2018.