Comparison of EMG responses obtained from endotracheal tube and thyroid cartilage surface electrodes in thyroidectomies performed with intraoperative nerve monitoring.

OBJECTIVE

Comparison of electromyographic (EMG) responses obtained from endotracheal tube electrodes (ETE) and thyroid cartilage surface electrodes (TCSE) in patients undergoing thyroidectomy and/or parathyroidectomy with intraoperative recurrent laryngeal nerve monitoring. MATERIALS AND

METHODS

Fifty-one recurrent laryngeal nerves (RLNs) at risk during 28 surgical procedures on 27 consecutive patients operated between 5 September 2022 and 21 August 2023 at Dokuz Eylül University, Department of Otorhinolaryngology were evaluated. Patients’ age, gender, body mass index (BMI), vocal cord mobility, RLN EMG signal amplitudes recorded with ETE and TCSE, and surgery-related complications were documented and analyzed.

RESULTS

EMG signal amplitudes obtained with TCSE were significantly higher than ETE amplitudes (p = 0.001). Female patients showed higher EMG amplitudes than males with both methods (p = 0.002 and p < 0.001, respectively). TCSE measurements yielded higher amplitudes than ETE in both genders (p = 0.007 and p = 0.035, respectively). Patients < 50 years of age had significantly higher TCSE amplitudes than ETE (p < 0.001), while no significant difference was found for patients ≥ 50 years of age (p = 0.214). Left-sided TCSE amplitudes were considerably higher than right-sided ones (p = 0.004), while there was no side difference for ETE amplitudes (p > 0.05). TCSE values were considerably higher than ETE in BMI groups of < 25 kg/m² and > 30 kg/m² (p = 0.001 and p = 0.038), while no significant difference was found in the 25–30 kg/m² group (p > 0.05). One case (3.57%) experienced false loss of signal in ETE recordings due to endotracheal tube rotation, while TCSE readings remained stable. Among the 51 RLNs at risk, there was one (1.96%) transient vocal cord paralysis, and another (1.96%) transient partial vocal cord paresis. Hematoma and permanent vocal cord paralysis complications were not observed in any of the patients.

CONCLUSION

Compared to the conventional ETE method, TCSE yielded higher and more stable EMG amplitudes during intraoperative nerve monitoring. TCSE was found to be a reliable and practical alternative to ETE either as a primary method or as a rescue method when false loss of signal is suspected in ETE recordings.