Endocrine Abstracts

Background: The effectiveness of intraoperative neuromonitoring (IONM) in reducing the risk of vocal cord palsy (VCP) after thyroidectomy is controversial. This study aimed to evaluate the impact of IONM on VCP rates, identify risk factors, and assess the trend of VCP rates over time.

Methods: This retrospective observational study included consecutive patients who underwent thyroidectomy for thyroid cancer between March 2014 and June 2022. VCP rates were compared between non-IONM and IONM patients stratified based on the date of surgery. Univariate and multivariate analyses were conducted to identify risk factors associated with VCP, and the prevalence of VCP was observed over time.

Results: A total of 712 patients (485 females and 227 males) were included in the analysis. The mean age was 52.6 years. Final pathology consisted of 688 papillary thyroid carcinomas, 31 follicular thyroid carcinomas, five oncocytic carcinomas, four medullary thyroid carcinomas, two poorly differentiated carcinomas, and two anaplastic carcinomas. Transient and permanent VCP did not significantly differ between non-IONM and IONM groups. Transient VCP occurred in 7/151 (4.6%) patients in the non-IONM group and 24/561 (4.3%) patients in the IONM group (p = 0.878). Permanent VCP occurred in 1/151 (0.7%) patient in the non-IONM group and 2/561 (0.4%) patients in the IONM group (p = 0.607). Among the nerves at risk in the non-IONM and IONM patients respectively, transient damage occurred in 7/246 (2.8%) and 24/800 (3.0%) cases (p = 0.901); and permanent damage occurred in 1/246 (0.4%) and 2/800 (0.3%) cases (p = 0.688). Univariate analysis identified N1b stage (odds ratio [OR] 3.038, 95% confidence interval [CI] 1.285 - 7.182, p = 0.011) and extrathyroidal extension (OR 2.691, 95% CI 1.064 - 6.805, p = 0.036) as significant risk factors for VCP. Multivariate analysis did not reveal any significant risk factors for VCP. There was a statistically significant decreasing trend in VCP rates over time as the cumulative number of cases increased (p = 0.017).

Conclusions: IONM did not significantly reduce the risk of VCP. However, the surgeon’s experience may have a role in reducing risk, as evidenced by the decreasing trend of VCP rates over time.

Keywords: Intraoperative Neuromonitoring, Risk Factors, Thyroid Cancer, Thyroidectomy, Vocal Cord Palsy