Superior laryngeal nerve identification and preservation in thyroidectomy

Abstract

Injury to the external branch of the superior laryngeal nerve (EBSLN) can result in detrimental voice changes, the severity of which varies according to the voice demands of the patient. Variations in its anatomic patterns and in the rates of identification reported in the literature have discouraged thyroid surgeons from routine exploration and identification of this nerve. Inconsistent with the surgical principle of preservation of critical structures through identification, modern-day thyroidectomy surgeons still avoid the EBSLN rather than identifying and preserving it. We sought to describe the anatomic variations of the EBSLN, particularly at the junction of the inferior constrictor and cricothyroid muscles; to propose a systematic approach to identification and preservation of this nerve; and to describe the author's experience with SLN identification. A retrospective review of thyroid lobectomies and total thyroidectomies performed between 1978 and 2008 was performed. Three anatomic variations of the distal aspect of the EBSLN as it enters the cricothyroid were encountered and are described. The total identification rate during the 30-year period was 85.1%. Operations performed in recent years have a higher identification rate of more than 90%. Understanding the 3 anatomic variations of the distal portion of the EBSLN and its relation to the inferior constrictor muscle allows for high rates of identification of this nerve. The EBSLN should be explored during thyroid surgery, and identification is possible in most cases. Preservation of the EBSLN maintains optimal function of the larynx.