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

Abstract

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

Comparison of Monopolar and Bipolar Stimulator Probes for Intraoperative Nerve Mapping During Thyroidectomy: A Prospective Study

“…14 Increasing current to 2 or 3 mA may expedite displaced VN mapping in the carotid sheath and provide higher amplitudes. 18,21,22 The study lacks stimulation data regarding the EBSLN. Additionally, the right and left nerve data were pooled data of all patients and not compared in the same patient.…”

Assessment of the Safety of the New Hybrid Pencil Type Energy (NP) Device Used Close to the Recurrent Laryngeal Nerve in a Porcine Model: Comparison With a Conventional Electrosurgical Knife

“…On the other hand, Chavez et al 6 concluded that a harmonic scalpel did not cause any significant thermal damage to the RLN, even when it was activated close to the nerve (up to 1 mm) or when the nonactive blade was placed at the nerve. Furthermore, Lu et al 10 revealed that the application of a short-duration, high-current stimulating pulse to the VN or RLN during monitored thyroidectomy had no harmful effects. With the NP device, the incision distance was 20 mm, and the short incision time might prevent nerve damage.…”

“…Many studies have attempted to overcome these issues and have reported on resection around the RLN using energy devices. [6][7][8][9][10][11][12][13] Olympus Corporation (Tokyo, Japan) recently developed the new hybrid pencil type energy (NP) device. This device allows surgeons to perform coagulation, cutting, and dissection during surgery with both ultrasonically generated energy and electrically generated energy.…”

“…Many studies have attempted to overcome these issues and have reported on resection around the RLN using energy devices. 6-13…”

Training Courses in Laryngeal Nerve Monitoring in Thyroid and Parathyroid Surgery- The INMSG Consensus Statement

“…Currently, most training programs and research use mediumsized animals for experimental models, most typically canine (dog) models (56)(57)(58)(59) and porcine(swine/mini-pig) models (60)(61)(62)(63)(64)(65)(66)(67)(68)(69)(70)(71)(72)(73)(74)(75)(76)(77). Dog models of laryngeal function and the RLN are well-established and closely mimic the anatomy, size, and physiology in humans.…”