Continuous intraoperative vagus nerve stimulation for identification of imminent recurrent laryngeal nerve injury

BACKGROUND: Conventional intraoperative nerve monitoring, predicated on intermittent stimulation, can predict recurrent laryngeal nerve (RLN) palsy only after the damage has been done. METHODS: Fifty-two patients (52 nerves at risk) who underwent continuous intraoperative nerve monitoring (CIONM) for thyroid surgery via vagus nerve stimulation had their electromyographic (EMG) tracings recorded and correlated with surgical maneuvers and postoperative RLN function. RESULTS: There was 1 imminent loss of signal (LOS) with intraoperative signal recovery and there were 4 losses of signal with corresponding unilateral transient RLN palsy. When EMG amplitude decreased >50% and EMG latency increased >10%, LOS and postoperative RLN palsy were noted in 4 of 8 patients (50%) who had multiple combined events. In 9 of 13 patients (70%) who developed adverse EMG changes, modification of the causative surgical maneuver resulted in recovery of those EMG changes and aversion of impending RLN palsy. CONCLUSION: CIONM reliably signaled impending nerve injury, enabling immediate corrective action.