Nonrecurrent Laryngeal Nerve in the Era of Intraoperative Nerve Monitoring.

Emin Gurleyik,Gunay Gurleyik

doi:10.1155/2016/1606029

Abstract

Nonrecurrent laryngeal nerve (non-RLN) is an anatomical variation increasing the risk of vocal cord palsy. Prediction and early identification of non-RLN may minimize such a risk of injury. This study assessed the effect of intraoperative neuromonitoring (IONM) on the detection of non-RLN. A total of 462 (236 right) nerves in 272 patients were identified and totally exposed, and all intraoperative steps of IONM were sequentially applied on the vagus nerve (VN) and RLN. Right predissection VN stimulation at a distal point did not create a sound signal in three cases (3/236; 1.27%). Proximal dissection of the right VN under IONM guidance established a proximal point, creating a positive signal. The separation point of non-RLN from VN was discovered in all three patients. Non-RLNs were exposed from separation to laryngeal entry. Positive IONM signals were obtained after resection of thyroid lobes, and postoperative period was uneventful in patients with non-RLN. Absence of distal VN signal is a precise predictor of the non-RLN. IONM-guided proximal dissection of the right VN leads to identification of the non-RLN. The prediction of non-RLN by the absence of the VN signal at an early stage of surgery may prevent or minimize the risk of nerve injury.

Highlights

Identification and full exposure of the recurrent laryngeal nerve (RLN) are mandatory for safer thyroid surgery
Safer thyroid surgery depends on the preservation of the motor activity of the RLN; it is extremely important to determine the integrity of the motor function
We aim to present our results of Intraoperative neuromonitoring (IONM) in our cases of non-RLN to determine electrophysiological parameters for the early and safe detection of the nonrecurrent nerve

Summary

Introduction

Identification and full exposure of the recurrent laryngeal nerve (RLN) are mandatory for safer thyroid surgery. Knowledge of the anatomy of the RLN, including its anatomical variations, good surgical skill, and experience are required for preserving anatomical integrity and motor activity of the nerve. Based on the association with vascular abnormality, researchers have attempted to identify this vascular variation by radiological methods to predict the associated non-RLN. Some imaging methods were found useful for the detection of vascular abnormality that can accurately predict the existence of non-RLN [1,2,3,4,5]. Safer thyroid surgery depends on the preservation of the motor activity of the RLN; it is extremely important to determine the integrity of the motor function. Intraoperative neuromonitoring (IONM) is a widely accepted method to evaluate the motor activity of the RLN during thyroid surgery [6,7,8]. We hypothesize that IONM provides additional findings for the early detection of non-RLN during thyroid surgery

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