Anatomic Characteristics, Identification, and Protection of the Nonrecurrent Laryngeal Nerve during Thyroidectomy

Abstract

Objective We aimed to investigate the anatomical features and variation pattern of the nonrecurrent laryngeal nerve (NRLN), summarize the methods for identifying the NRLN before and during thyroidectomy, and share experiences regarding preventing and treating its injury. Study Design Retrospective case data analysis. Setting First Affiliated Hospital of Harbin Medical University. Subjects and Methods Between January 2002 and May 2016, 7392 patients underwent thyroidectomy in our hospital. Of them, 28 patients with NRLN were identified, and their clinical data were retrospectively analyzed. Results This study included 7392 patients in which the recurrent laryngeal nerves (RLNs) were routinely identified during surgery. The presence of NRLN was intraoperatively confirmed in 28 patients. All the NRLNs were located on the right side and its overall incidence was 0.37%. Five of the NRLNs were classified as type I, 19 as type IIa, and 4 as type IIb. Of the 28 cases, 4 NRLNs were injured during surgery, in which primary end-to-end anastomosis or local seal with corticosteroid injection was performed as a remedy. In the 4 patients with NRLN injury, 2 presented with postoperative hoarseness that indicated vocal cord paralysis confirmed by laryngoscope; the other 2 patients' voices had no significant changes. Conclusion The NRLN, which is rare in clinical practice and predominantly right-sided, is anatomically more complex and variant at a higher risk of surgical injury. The key factors to accurately identify NRLN and to effectively prevent its injury include careful interpretation of auxiliary examination results before surgery, raising awareness of its presence, meticulous dissection, and routine exposure of the RLN during surgery.

Surgical Skills and Technological Advancements to Avoid Complications in Lateral Neck Dissection for Differentiated Thyroid Cancer

“…During re-operations, it is also good practice to search for the nerve in the so-called “free segment”, that is, in the anatomical area not affected by the first operation. The incidence of non-recurrent inferior laryngeal nerve is low but can be prevented with a pre-operative CT study which can highlight an abnormal course of the right subclavian artery [ 13 ]. In this case, IONM seems to be very useful in identifying the nerve [ 14 ].…”

Non-recurrent inferior laryngeal nerve: a case report

“…7 NRILN are classified as: type 1: arises directly from vagus and runs together with superior thyroid vessels; type 2A: parallel transverse path, over the trunk of inferior thyroid artery; and type 2B, parallel transverse path, under the trunk or between the inferior thyroid artery branches. 8 Computed tomography (CT) diagnosis of arteria lusoria is based on the identification of an aberrant vessel that passes behind the esophagus. It is possible to predict the presence of a nonrecurrent inferior laryngeal nerve by identifying the presence of an arteria lusoria and the absence of the brachiocephalic artery on a preoperative CT scan.…”

Successful Prediction of a Left Nonrecurrent Laryngeal Nerve in a Patient With Right-Sided Aorta and Aberrant Left Subclavian Artery

“…The risk of iatrogenic injury to a NRLN is significantly increased during thyroid surgery, which is mainly due to the surgeon's unawareness of the presence of such anatomic variant. 4 While intraoperative nerve monitoring with an algorithm to identify the NRLN has been advocated by some surgeons, an important way to minimize risk of nerve injury is to understand situations in which such an anatomic variant might exist. 3,4 During embryogenesis, there are 6 pairs of primitive aortic arches between the ventral and dorsal aorta, 1 for each branchial arch.…”

“…While the overall incidence of RLN injury is low, especially in experienced hands, the risk of intraoperative injury to a nonrecurrent laryngeal nerve (NRLN) is significantly higher, with reported incidence ranging from 12.9% to 14.3%. 1,4 Preoperative prediction of such anatomic variation might reduce the risk of this complication. 2 The incidence of right-sided NRLN is about 0.3% to 1%.…”