Comparison of Recording Electrode Arrays in Endotracheal Thyroid Monitoring Tubes in a Porcine Model

Objectives: Alteration in positioning or head manipulation during thyroid surgery can lead to endotracheal tube movement and potentially a change in intraoperative neural monitoring readings. We sought to study the impact of positional changes on two different commercially available recording electrode arrays.

Materials: Eight pigs divided equally into two study groups based on recording electrode arrays were used: Neurosign Lantern Laryngeal Electrode (LLE) (Neurosign_Technomed, The Netherlands) and Medtronic NIM EMG [neural integrity monitor electromyogram] endotracheal tube (ETT) (Medtronic, Jacksonville, FL). Neck movement and reposition were performed for all pigs. Signal data, including amplitude and latency, were collected for vagus nerve, recurrent laryngeal nerve (RLN), and external branch of superior laryngeal nerve (EBSLN) before and after repositioning. The differences of amplitude and latency by pre- and post-repositioning were compared for all animals.

Results: Eight pigs were included in the current study. ETT group (Medtronic) had a significant decrease in amplitude of all tested nerves: for the vagus nerve on the left side by 36.30% (P = .021) and on the right by 49.29% (P = .024), for RLN on the left by 30.22% (P = .014) and on the right by 42.34% (P = .004), and for EBSLN on the left by 63.62% (P = .003) and on the right by 13.58% (P = .010). The amplitude changes in LLE group (Neurosign) repositioning were not statistically significant in all nerves.

Conclusion: Recording electrode array configuration can impact the stability of nerve monitoring signal during thyroid surgeries. Repositioning was associated with changes in nerve signal amplitude in ETT group (Medtronic), whereas LLE (Neurosign) did not show any significant differences. Human studies are warranted.

Level of evidence: NA Laryngoscope, 130:2499-2505, 2020.