Abstract: Background and purpose: Nonrecurrent laryngeal nerve (NRLN) is rare but important for thyroid surgery. This study aimed to explore the anatomical characteristics of NRLN and the clinical significance of intraoperative neuromonitoring (IONM), so that surgeons could better protect the function of NRLN during surgery and reduce the risk of nerve injury. Methods: A total of 1 600 patients with recurrent laryngeal nerve (RLN) exposure in thyroid surgery who were treated at Department of General Surgery in First People's Hospital of Anqing, from January 2015 to September 2020, were selected as the study subjects. The exposure and injury of NRLNs were analyzed retrospectively. IONM of vagus nerve and RLN was used for detecting the function of nerves. Results: The total number of RLNs exposed during the operation was 2 312 in 1 600 patients, of which 5 patients with NRLNs (0.31%) were found. All NRLNs were found on the right side, including 2 cases of type Ⅰ, 1 case of type ⅡA and 2 cases of type ⅡB. The exposure time of NRLN was (11.38±1.59) minutes. All the 5 patients had aberrant subclavian artery that arose directly from the aortic arch detected by preoperative CT scanning. No related postoperative complication occurred. Conclusion: The incidence of NRLN is low, and most of them exist on the right side. If preoperative examination indicates the variation of subclavian artery, the existence of NRLN should be considered. With the help of IONM, NRLN can be found in time, and complications can be effectively avoided.

Key words: Thyroid surgery, Nonrecurrent laryngeal nerve, Nerve monitoring