Impact of EMG Changes in Continuous Vagal Nerve Monitoring in High‐Risk Endocrine Neck Surgery

Abstract

BackgroundContinuous vagal intraoperative neuromonitoring (CIONM) of the recurrent laryngeal nerve (RLN) may reduce the risk of RLN lesions during high-risk endocrine neck surgery such as operation for large goiter potentially requiring transsternal surgery, advanced thyroid cancer, and recurrence.MethodsFifty-five consecutive patients (41 female, median age 61 years, 87 nerves at risk) underwent high-risk endocrine neck surgery. CIONM was performed using the commercially available NIM-Response 3.0 nerve monitoring system with automatic periodic stimulation (APS) and matching endotracheal tube electrodes (Medtronic Inc.). All CIONM events (decreased amplitude/increased latency) were recorded.ResultsAPS malfunction occurred on three sides (3 %). A total of 138 CIONM events were registered on 61 sides. Of 138, 47 (34 %) events were assessed as imminent (13 events) or potentially imminent (34 events) lesions, whereas 91 (66 %) were classified as artifacts. Loss of signal was observed in seven patients. Actions to restore the CIONM baseline were undertaken in 58/138 (42 %) events with a median 60 s required per action. Four RLN palsies (3 transient, 1 permanent) occurred: one in case of CIONM malfunction, two sudden without any significant previous CIONM event, and one without any CIONM event. The APS vagus electrode led to temporary damage to the vagus nerve in two patients.ConclusionsCIONM may prevent RLN palsies by timely recognition of imminent nerve lesions. In high-risk endocrine neck surgery, CIONM may, however, be limited in its utility by system malfunction, direct harm to the vagus nerve, and particularly, inability to indicate RLN lesions ahead in time.

Continuous intraoperative neural monitoring of the recurrent nerves in thyroid surgery: a quantum leap in technology

“…Beside two anecdotal reports of local and cardiac complications during CIONM in a very few patients (20,21), there are several clinical data showing no evidence of adversity related to the circular dissection of the a vagal nerve segment or related intrinsically to CIONM (11,15,17,19,(22)(23)(24)(25)(26)(27).…”

Vocal cord function during recurrent laryngeal nerve injury assessed by accelerometry and EMG

“…Both the concept of staged thyroidectomy, for example, in case of LOS on the first side not to continue with the other side in planned bilateral surgery, as well as the concept of C‐IONM by alerting the surgeon to impending nerve injury with the possibility to release intraoperative nerve stress, require reliable interpretation and accurate prediction of postoperative vocal cord function. Definitions of clinically important signal changes in C‐IONM vary in the literature . The INMSG defines an impending adverse EMG as an amplitude decrease above 50% from initial baseline combined with latency increase of ≥10% .…”

Analysis of neuromonitoring signal loss during retroauricular versus conventional thyroidectomy

“…The main reason for using intermittent instead of continuous IONM is because continuous IONM is currently not approved or covered by the national insurance. Increasing the sample size and application of continuous IONM would help to improve our study in the identification of surgical maneuvers associated with RLN injury …”