Risk factors for recurrent laryngeal nerve injury in microwave ablation of thyroid nodules: A multicenter study

Background and purpose: This study aimed to investigate the risk factors for recurrent laryngeal nerve (RLN) injury after microwave ablation (MWA) of thyroid nodules and to identify factors influencing the recovery time of post-procedure hoarseness. Materials and methods: We retrospectively analyzed data from patients who underwent MWA for thyroid nodules at five hospitals between November 2018 and July 2022. Patients were divided into malignant and benign nodule groups. Variables analyzed included nodule size and location, the shortest distance from nodules to the thyroid capsule and tracheoesophageal groove (TEG-D), and ablation parameters. Univariate and multivariate analyses were performed to identify risk factors. Kaplan-Meier and Cox analyses were used to evaluate the recovery time of hoarseness after MWA. Results: The study included 1,216 patients (mean age 44 +/- 12 [SD] years; 901 women) with 602 malignant nodules and 614 benign nodules. The posterior capsule distance (PCD) and TEG-D were identified as independent influencing factors for hoarseness in all patients (P = 0.014, OR = 0.068; P < 0.001, OR = 0.005; AUC = 0.869). TEG-D was a significant risk factor for hoarseness, with safe thresholds identified at 4.9 mm for malignant nodules and 2.2 mm for benign nodules. Among patients who developed hoarseness, those in the close-distance group (TEG-D <= 2 mm) had a longer recovery time compared to the distant-distance group. TEG-D was an independent factor influencing recovery time (P = 0.008, HR = 11.204). Conclusion: Clinicians should consider several factors, particularly TEG-D and PCD, when assessing the risk of RLN injury before MWA. TEG-D was a vital independent factor influencing recovery time. Summary: Clinicians should pay attention to several influencing factors for RLN injury before MWA and TEG-D was an independent influencing factor for recovery time of hoarseness after MWA.