Intraoperative nerve monitoring in thyroidectomies for malignancy: Does it matter?

Introduction: Recurrent laryngeal nerve injury (RLNI) and postoperative hypocalcemia are potential complications of thyroidectomy, especially in cases of malignancy. Intraoperative nerve monitoring (IONM) remains controversial. We sought to evaluate the impact of IONM on these complications using a national dataset. Methods: The American College of Surgeons National Surgical Quality Improvement Program thyroidectomy targeted dataset was queried for patients who underwent open thyroidectomies from 2016 through 2017. Primary outcomes were 30-day readmission (RA), 30-day hypocalcemic events (HCE), and RLNI. Patients were grouped by IONM use. Demographic, clinicopathologic, intraoperative, and postoperative variables were compared. Univariate and multivariable logistic regression models were constructed to evaluate associations of variables with each primary outcome, measured by adjusted odds ratios (AOR) and 95% confidence intervals (95CI). Subgroup analysis with similar methods was performed on patients with malignant pathology. Significance was established at p\u3c0.05. Results: A total of 9527 patients were identified, 3558 (37.3%) without IONM, and 5969 (62.7%) with. The IONM group had higher BMI (31.0±7.8 kg/m2 vs 30.3±7.7 kg/m2; p\u3c0.001), more benign pathology (38.9% vs 35.4%; p\u3c0.001), more use of vessel sealing devices (73.6% vs 57.9%; p\u3c0.001), and more neck dissections (28.1% vs 18.9%; p\u3c0.001). By multivariable analysis, IONM was not associated with RA, but was protective against HCE (AOR=0.81, 95CI=0.68-0.96; p=0.013) and RLNI (AOR=0.83, 95CI=0.69-0.98; p=0.033). Malignant pathology was a risk factor for HCE (AOR=1.21, 95CI=1.01-1.45; p=0.038) and RLNI (AOR=1.22, 95CI=1.02-1.46; p=0.034). In the subgroup analysis of patients with malignancy (5943/9527, 62.4%), IONM continued to be protective against HCE (AOR=0.73, 95CI=0.60-0.90; p=0.003) and RLNI (AOR=0.76, 95CI=0.62-0.94; p=0.012). Conclusion: Malignancy was a risk factor for HCE and RLNI. IONM was protective against HCE and RLNI. both overall, and in the malignant subgroup. This suggests that patients undergoing thyroidectomy may benefit from treatment at centers that offer IONM, especially if the indication is malignancy