The Role of Clinical Factors in the Development of Loss of Signal During Thyroid Surgery
Abstract
Objectives: This study aims to identify clinical parameters beyond recurrent laryngeal nerve (RLN) anatomy contributing to loss of signal (LOS) during thyroid surgery.
Materials and Methods: We retrospectively analyzed the records of 171 initial thyroid surgery patients under intraoperative nerve monitoring (IONM) by a single surgeon. Patient characteristics, surgical details, and LOS data were recorded. All surgical procedures were performed using intermittent IONM in accordance with international guideline statements. Patients were categorized according to the presence of LOS (LOS+ and LOS-), and logistic regression analysis was used to identify LOS-related factors.
Results: Among 171 patients, 8 (4.7%) experienced LOS. LOS+ cases showed significantly lower tumor/nodule size and thyroid volume. No significant differences were observed in other variables between the LOS+ and LOS- groups. Logistic regression analysis identified tumor/nodule size ≤10 mm (p=0.006) and thyroid volume ≤12 mL (p=0.013) as significant factors. In 8 LOS+ patients, traction injuries were prevalent (87.5%), mainly at the level of Berry’s ligament, left-sided, and single-branch nerve anatomy in 87.5%. Complete recovery of LOS occurred in 37.5% of LOS+ cases after the termination of traction.
Conclusion: Small thyroid volume increases the risk of the development of LOS, due to excessive RLN stretching during surgery. Our findings highlight the importance of minimizing traction and using continuous IONM to prevent LOS and subsequent vocal cord paralysis.
Key Words: Thyroidectomy, Electromyography, Vocal Cord Paralysis, Loss of Signal, Intraoperative Neuromonitoring
Keywords
Thyroidectomy, Electromyography, Vocal Cord Paralysis, Loss of Signal, Intraoperative Neuromonitoring
Ethical Statement
This study has been approved by the Ankara University Faculty of Medicine, Human Research Ethics Committee (decision no: İ07-506-23, date: 21.08.2023).
References
- 1. Dionigi G, Wu CW, Kim HY, et al. Severity of Recurrent Laryngeal Nerve Injuries in Thyroid Surgery. World J Surg. 2016;40:1373-1381
- .2. Schneider R, Randolph G, Dionigi G, et al. Prediction of Postoperative Vocal Fold Function After Intraoperative Recovery of Loss of Signal. Laryngoscope. 2019;129:525-531.
- 3. Chiu KL, Lien CF, Wang CC, et al. Intraoperative EMG recovery patterns and outcomes after RLN traction-related amplitude decrease during monitored thyroidectomy. Front Endocrinol (Lausanne). 2022;13:888381.
- 4. Schneider R, Sekulla C, Machens A, et al. Postoperative vocal fold palsy in patients undergoing thyroid surgery with continuous or intermittent nerve monitoring. Br J Surg. 2015;102:1380-1387.
- 5. Lian T, Leong D, Ng K, et al. A Prospective Study of Electromyographic Amplitude Changes During Intraoperative Neural Monitoring for Open Thyroidectomy. World J Surg. 2023;47:1971-1977.
- 6. Liu N, Chen B, Li L, et al. Mechanisms of recurrent laryngeal nerve injury near the nerve entry point during thyroid surgery: A retrospective cohort study. Int J Surg. 2020;83:125-130.
- 7. Iscan Y, Aygun N, Sormaz IC, et al. Is craniocaudal dissection of recurrent laryngeal nerve safer than lateral approach: a prospective randomized study comparing both techniques by using continuous intraoperative nerve monitoring. Ann Surg Treat Res. 2022;103:205-216.
- 8. Liu MY, Chang CP, Hung CL, et al. Traction Injury of Recurrent Laryngeal Nerve During Thyroidectomy. World J Surg. 2020;44:402-407.
- 9. Randolph GW, Dralle H; International Intraoperative Monitoring Study Group, et al. Electrophysiologic recurrent laryngeal nerve monitoring during thyroid and parathyroid surgery: international standards guideline statement. Laryngoscope. 2011;121 Suppl 1:S1-S16.
- 10. Wu CW, Hao M, Tian M, et al. Recurrent laryngeal nerve injury with incomplete loss of electromyography signal during monitored thyroidectomyevaluation and outcome. Langenbecks Arch Surg. 2017;402:691-699.