Thermal injury of the recurrent laryngeal nerve by THUNDERBEAT during thyroid surgery: findings from continuous intraoperative neuromonitoring in a porcine model.

BACKGROUND: Recurrent laryngeal nerve (RLN) palsy is the most common and serious complication of thyroid surgery. The use of energy-based devices (EBDs) has replaced hand-tying methods in many institutions. However, EBD use proximal to the RLN presents risks related to lateral thermal spread and associated nerve damage. THUNDERBEAT (TB) is one of the most widely used EBDs. This study aimed to test the safety of TB during thyroidectomy.

METHODS: Four piglets weighing 30-40 kg experienced thyroidectomy while continuous electrophysiologic monitoring (continuous intraoperative neuromonitoring) occurred, using an electromyography endotracheal tube and NIM 3.0 response system. TB was applied at various distances from the RLN, and we assessed the safety of the protocols.

RESULTS: Adverse electromyography events did not occur at distances >3 mm from the RLN. Amplitude decreased at 2 mm from the RLN after 8 s. However, immediate loss of signal occurred at 1 mm from the RLN, likely due to immediate shrinkage of surrounding tissue after TB application.

CONCLUSIONS: TB can be used safely at 3 mm from the RLN but must be used for <8 s at more proximal locations. This is the first report assessing the safety of TB, and findings indicate that TB should be used at least 1 mm from the RLN to avoid injury.