Percutaneous continuous vagal stimulation provided superior neuromonitoring over the peroral electrode in transoral thyroidectomy

Continuous intraoperative neuromonitoring (C-IONM) has been developed and used in open thyroidectomy to perceive imminent recurrent laryngeal nerve (RLN) injury, but has scarcely been reported in transoral endoscopic thyroidectomy vestibular approach (TOETVA) due to technical difficulty. This study aims to report the percutaneous C-IONM technology in TOETVA and compare it with the conventional peroral method to confirm its feasibility, safety, and effectiveness. This prospective study included 102 consecutive patients who received TOETVA and standardized continuous vagal nerve (VN) stimulation via percutaneous insertion of commercially available handheld stimulation probe into the moderately dissected carotid space between carotid artery and internal jugular vein and fixed by an external fixator (PC group, n = 52 with 67 nerves at risk [NAR]) or conventional peroral DELTA electrode (DELTA group, n = 50 with 61 NAR). Demographic data, technical outcome variables, and electromyography (EMG) signals were collected and compared. C-IONM procedures were successfully set up in all PC group patients but failed in three DELTA group patients. Comparisons of technical characteristics show the PC group demonstrated a shorter electrode positioning time, fewer stimulator displacement events, and more stable EMG responses than the DELTA group. Four NARs (3 in PC, 1 in DELTA group) reported imminent recurrent laryngeal nerve (RLN) traction-related adverse events, all with intraoperative recovery after surgical technique modification, causing no postoperative vocal cord palsy. Severely weakened or loss of EMG signal occurred in 4 NARs (all in DELTA group), either due to stretch injury of VN (3 NAR) or traction injury of RLN (1 NAR), causing two postoperative VCP in 2 NARs. Percutaneous continuous vagal stimulation was superior to peroral vagal stimulation in a selected cohort of patients undergoing TOETVA to perceive the imminent injury of RLN to start immediate rescue.