Is trans-thyroid cartilage monitoring as good as endotracheal tube monitoring during thyroidectomy?

Purpose: To evaluate whether trans-thyroid cartilage nerve monitoring for thyroid surgeries is as effective and safe as endotracheal tube monitoring.

Methods: Fifty-one thyroidectomies (38 hemithyroidectomies and 13 total thyroidectomies, analyzed as two separate hemi-thyroidectomies) were included. Patients undergoing surgery from 6/2020 to 8/2021 were monitored simultaneously with the NIM® Nerve Monitoring System TriVantage™ Electromyography (EMG) endotracheal tube and EMG trans-thyroid cartilage. Electrophysiological responses of 64 vagus and recurrent laryngeal nerves were obtained. Peri-operative evaluation and 12-month post-operative follow-up were conducted to examine nerve function. Wilcoxon signed-rank and Spearman coefficient tests were used to determine whether there were differences between the methods.

Results: The average initial amplitude measured with the trans-thyroid cartilage method was higher in the recurrent laryngeal and vagus nerves (p = 0.002, p = 0.003, respectively). The mean difference in EMG amplitude from start to end of surgery for 10 damaged nerves (7 temporary and 3 permanent) differed from intact nerves in both methods and nerves (p < 0.05 for all). Among intact recurrent laryngeal nerves, 20.4% had 20-80% decrease in amplitude in endotracheal tube electrodes and 16.7% in trans-thyroid cartilage electrodes (p = 0.92). All cases with stable EMG signals or with increased EMG amplitude (with both types of electrodes and with both nerves) had normal post-operative vocal function. No significant difference was found between the two methods when measuring the vagus and recurrent laryngeal nerves. No complications occurred when using trans-thyroid cartilage electrodes.

Conclusions: Trans-thyroid cartilage nerve monitoring for thyroid surgeries is as effective and safe as the current standard monitoring using an endotracheal tube. During thyroid surgery, patients are monitored to avoid damaging nerves near the vocal cords. This study compared monitoring through a throat tube with the easier method of monitoring outside of the throat to see if it is as effective and safe. No major difference was found between the two methods and there were no problems.