Nonrecurrent laryngeal nerve in thyroid surgery: Frequency, anatomical variations according to a new classification and surgery consideration
Van Quang Le MD Quoc Duy Ngo MD Xuan Quy Ngo MD
First published: 17 April 2019 https://doi.org/10.1002/hed.25771

Abstract

Background

The nonrecurrent laryngeal nerve (NRLN) is a rare embryologically derived variant of the RLN. We aimed to identify the proportion of NRLN (during thyroidectomy), classify clinical NRLN types, and recommend some surgical considerations.

Method

In this prospective study, from May 2017 to September 2018, our hospital carried out 2158 thyroid operations. We reported the NRLN rate and distinguished NRLN into four types.

Results

Overall, NRLN had an incidence rate of 0.74% (16 out of 2158 total thyroid surgeries). We did not detect any patient with left‐sided NRLN. The traveling patterns of the nerves could be classified as descending (12.5%), vertical (25%), ascending (37.5%), or V‐shaped (25%).

Conclusion

The NRLN is a rare variation of the RLN. From our experience, we recommend the guidelines will help surgeons to avoid NRLN injury.

Classification of the NRLN

During surgery, the course of the NRLN from the vagus nerve trunk was evaluated. Cases were classified according to the following four NRLN traveling pattern types: (a) descending—the nerve descends from the vagus nerve trunk; (b) vertical—the nerve runs vertically to the cricothyroid joint; (c) ascending—the nerve runs upward to the cricothyroid joint; and (d) V‐shaped—the nerve takes a downward course and runs upward to the cricothyroid joint (Figure 2) [5].

our types of nonrecurrent laryngeal nerve (NRLN): A, descending—the nerve descends from the vagus nerve trunk; B, vertical—the nerve runs vertically to the cricothyroid joint; C, ascending—the nerve runs upward to the cricothyroid joint; and D, V‐shaped—the nerve takes a downward course and runs upward to the cricothyroid joint.