Dynamics of loss and recovery of the nerve monitoring signal during thyroidectomy predict early postoperative vocal fold function

Abstract

These data, including the observation that global type 2 injuries may entail less severe nerve injury, require validation in independent series before being adopted more widely. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1144-E1151, 2016.

Future Directions of Neural Monitoring in Thyroid Surgery

“…Additionally, C-IONM provides comprehensive electromyography (EMG) documentation, detects imminent RLN failure, and reveals RLN stress mechanisms. Finally, C-IONM can reveal malposition of an EMG tube (7,8,12).…”

“…A major advantage of C-IONM is that, by alerting the surgeon to the potential for irreversible neural damage, it can reduce the risk of permanent RLN injury (7,8). For example, C-IONM can provide an early warning of impending neural injury by revealing adverse changes in EMG.…”

“…For example, C-IONM can provide an early warning of impending neural injury by revealing adverse changes in EMG. Nerve function can then be preserved by taking appropriate corrective action and by aborting maneuvers that can potentially cause adverse EMG changes and permanent vocal cord paralysis (VCP) (7,8). However, thyroid surgeons require effective methods for identifying important adverse events and for differentiating between true adverse events and artifacts (7,8,12).…”

“…Notably, mCEs and isolated amplitude or latency changes are not associated with VCP whereas sCEs denote electrophysiologic events that can be reversed by aborting the related surgical maneuver. However, both mCEs and sCEs can cause a loss of signal (LOS), which typically has much lower reversibility, and postoperative VCP (7,8). Thus, modification of a surgical maneuver associated with sCEs can prevent subsequent neural injury leading to postoperative VCP.…”

“…Currently, both intermittent IONM (I-IONM) (2,3) and continuous IONM (C-IONM) (7,8) are recognized as effective techniques for RLN management. Studies also show that IONM can facilitate functional preservation of the external branch of the superior laryngeal nerve (SLN) (6).…”