Noninvasive, tube-based, continuous vagal nerve monitoring using the laryngeal adductor reflex: Feasibility study of 134 nerves at risk.

Abstract

Continuous vagal intraoperative neuromonitoring (IONM) currently requires placement of a vagal nerve electrode. Herein, we present data from 100 patients (134 nerves-at-risk) monitored continuously during neck endocrine surgeries using a noninvasive, new methodology that solely utilizes endotracheal tube electrodes to simultaneously stimulate laryngeal mucosa and record a laryngeal adductor reflex continuous IONM (LAR-C-IONM) response. The laryngeal adductor reflex (LAR) was elicited by electrical laryngeal mucosal stimulation on the side contralateral to the operative field using endotracheal tube electrodes. All patients completed preoperative and postoperative laryngeal and voice examinations. One hundred patients (134 nerves-at-risk) were included. Significantly more nerves-at-risk with an LAR opening to closing amplitude decrement >60% or with absolute closing amplitude <100 μV had postoperative vocal fold paralysis (P < .001). The LAR-C-IONM was highly sensitive to recurrent laryngeal nerve (RLN) stretch or compression. The LAR-C-IONM is a promising new way to perform continuous vagal monitoring that requires no equipment other than an electromyography (EMG) endotracheal tube and is undergoing further, large-scale evaluation.