Identification of External Branch of the Superior Laryngeal Nerve in Thyroid Surgery: Is it Always Possible?

Uma Patnaik Ajith Nilakantan

doi:10.4172/2167-7948.1000127

Abstract

The External Branch of the Superior Laryngeal Nerve (EBSLN), which innervates the cricothyroid muscle, is important for voice quality. However, different identification rates for the nerve have been reported in thyroid surgery, with few surgeons not being able to identify the nerve at all. Different variants of the nerve have been described and various techniques have been used in order to identify the nerve. Our study aims to quote the identification rate of the EBSLN in thyroid surgery using standard dissection techniques. We feel that the definite prevalence of the Type III Friedman variant explains why the nerve may not be identified in a definite number of patients. The clinically relevant message of our study is that, even though it may not be possible to routinely identify the EBSLN in all cases of thyroid surgery, yet this nerve would be preserved by the standard extra capsular dissection techniques.

Highlights

Though all surgeons routinely identify and preserve the Recurrent Laryngeal Nerve (RLN) using standard dissection techniques, this is not so for the External Branch of Superior Laryngeal Nerve (EBSLN)
The EBSLN is described as passing superficial to inferior constrictor muscle and piercing it to supply cricothyroid muscle [10,11]
The voice symptoms associated with injury of the nerve are mild to moderate breathy voice, reduction in the average pitch of voice and a reduced voice range [1,2] with difficulties in high pitch and singing voice, which is very important in a professional voice user

Summary

Introduction

Though all surgeons routinely identify and preserve the Recurrent Laryngeal Nerve (RLN) using standard dissection techniques, this is not so for the External Branch of Superior Laryngeal Nerve (EBSLN). Different variants of the nerve have been described and various techniques have been described to identify it (see below). This muscle increases the longitudinal tension of vocal folds and raises the pitch of voice [1]. The nerve runs in close relation to the upper pole of the thyroid gland and is definitely at risk of injury during dissection [3]. The identification and preservation of the EBSLN should be a routine principle of thyroid surgery

Methods

Results

Discussion

Conclusion