Factors Associated With Injury to Recurrent Laryngeal Nerve in Patients Undergoing Surgery for Thyroid Cancer: A Single-centre Study Using Translaryngeal Ultrasound

Aims: Intraoperative injury to the recurrent laryngeal nerve (RLN) is a serious complication occurring more frequently in patients with thyroid cancer than in those with benign thyroid diseases. However, data on the risk factors for RLN injury among patients with thyroid cancer are scarce. Currently, RLN injury is diagnosed by laryngoscopy, but translaryngealultrasonography (TLUS), which is less invasive, appears to have a similar accuracy. Herein, we analysed risk factors ofintraoperative RLN injury in patients with thyroid cancer and assessed the diagnostic performance of TLUS.

Patients and methods: In this prospective study, we enrolled patients undergoing surgery for thyroid cancer from October 2020 to October 2021. Medical and surgical variables were analysed as risk factors of RLN injury. TLUS was compared with laryngoscopy in diagnosing RLN injury.

Results: There were 185 patients who underwent 196 surgeries. Of all surgeries, 23 (11.7%) caused RLN injury ascertained on laryngoscopy. Compared with laryngoscopy, TLUS displayed high sensitivity (97.7%; 95%CI: 94.3%-99.4%) and specificity (100%; 95% CI: 82.4%-100%). Before surgery, medical and surgical characteristics did not differ significantly between patients with or without RLN injury, but RLN entrapment by tumour was more frequent in those with the injury (P < 0.001). The risk of RLN injury was increased in patients undergoing thyroidectomy with lateral neck dissection (OR = 4.53; 95% CI: 1.29-14.32) and in those with lymph node metastases (OR = 2.76; 95% CI: 1.03-7.01).

Conclusion: Intraoperative RLN injury in patients with thyroid cancer is more common after operations requiringgreater resections and with lymph node involvement. TLUS could be used to diagnose RLN injury.