Electrode Configuration Impacts Stability of Nerve Monitoring Signal During Thyroid Surgery

by Linda Kossoff •

What is the impact of positioning or head manipulation during thyroid surgery on two different commercially available recording electrode arrays?

Bottom line: Recording electrode array configuration can impact the stability of the nerve monitoring signal during thyroid surgeries.

BACKGROUND: Vocal cord palsy following thyroid surgery is commonly caused by failure to safely visually identify or preserve the recurrent laryngeal nerve (RLN). Intraoperative neural monitoring (IONM) devices help surgeons localize the RLN and estimate the functional potentials of the nerve through electric stimulation; however, there is little uniformity in the nerve monitoring protocol.

STUDY DESIGN: Prospective cohort study (animal research).

SETTING: Department of Surgery, Tulane University School of Medicine, New Orleans, La.

SYNOPSIS: Using a prospective porcine model, researchers sought to evaluate the electrically evoked electromyogram (EMG) recorded from the vocalis muscles via two different types of endotracheal surface electrodes during thyroidectomy. Eight pigs were divided into two study groups, with four intubated using the Medtronic neural integrity monitor EMG endotracheal tube (ETT) and four intubated by the Neurosign Lantern Laryngeal Electrode (LLE). In both groups, intubation was performed using video laryngoscopy to ensure proper placement. The IONM system was also used to confirm proper EMG recording with neural stimulation. One operating surgeon conducted the same level of positional movement on each pig to evoke the displacement of tube electrodes. Examining differences in outcomes after repositioning revealed significant decrease in amplitude in all nerves in the ETT group, indicating that head reposition may impact the configuration of the ETT recording electrode. The effect of head reposition was eliminated, however, by LLE use. Study limitations included the porcine model and the small sample size.

CITATION: Kandil E, Al-Qurayshi Z, Randolph G, et al. Comparison of recording electrode arrays in endotracheal thyroid monitoring tubes in a porcine model Laryngoscope. 2020;130:2499-2505.