Mechanisms of recurrent laryngeal nerve injury in endoscopic thyroidectomy for papillary thyroid carcinoma: A large data from China

Purpose: To investigate the mechanisms of recurrent laryngeal nerve (RLN) injury during endoscopic thyroidectomy via breast approach (ET-BA) in patients with papillary thyroid carcinoma (PTC).Methods: The records of 416 PTC patients who underwent ET-BA with intraoperative neural monitoring (IONM) from May 2015 to May 2021 in Beijing Friendship Hospital affiliated to Capital Medical University were retrospectively analyzed.Results: All patients were women. Mean age was 37.80 (7.87) years. The ET-BA was performed in 416 patients. Overall incidence of RLN injury was 4.3% (18 patients). Injury was transient in 13 patients (3.1%) and permanent in five (1.2%). Macroscopic physical changes were apparent in the injured nerve in five patients (27.8%) and postoperative hoarseness or cough after drinking water were present in 11 (61.1%). Two RLN injuries occurred during nerve identification at the RLN laryngeal entry point into the surgical field, 15 during early nerve dissection somewhere between the first 0.5 and 2 cm of the nerve's course through the surgical field, and one occurred distal to 2 cm. The percentage of patients with separation, transection, traction and thermal mechanisms of injury was 27.8%, 22.2%, 22.2%, and 16.7%, respectively. The mechanism of injury was unknown in 11.1%.Conclusions: RLN injury may still occur during ET-BA despite endoscopic magnification and early nerve identification even when IONM is used. Separation, transection, and traction injuries were the most frequent causes of injury.