Identification and Preservation of External Branch of Superior Laryngeal Nerve in Thyroidectomy

Abstract

The basic principle of head and neck surgery is based on the identification and preservation of important structures, rather than avoidance. This principle is also applicable to identification and preservation of external branch of the superior laryngeal nerve (EBSLN) as a standard routine in all thyroid surgeries. During thyroid surgery, the EBSLN is clearly at risk due to its close proximity to the superior thyroid artery (STA) and its branches that need to be ligated during dissection of the superior pole of the thyroid gland. Injury is detrimental to the patient by causing paralysis of the cricothyroid muscle which is the main tensor and pitch controlling mechanism of the vocal folds. Injury to the EBSLN during surgery can result in the voice changes, loss of upper range and easy fatigability of voice, the severity of which varies according to the vocal demand of the patient. Total 45 cases of thyroid swellings were treated with surgery, in the Department of ENT at a tertiary care hospital during the period from 1st October 2009 to 30th October 2010. Hemithyroidectomy was the most common operative procedure implemented in 24 patients (53.33%) in which right sided was common. Next common procedure performed was that of total thyroidectomy in 14 patients (31.11%). Four patients underwent total thyroidectomy with neck dissection. The position of EBSLN was classified according the Cernea et al classification. In our study we found the EBSLN to be type I in 46.66%, type IIa in 73.33% and type IIb in 02.22%. The anatomical landmark taken into consideration to identify EBSLN was the Joll’s triangle with its relation to the superior pole of the thyroid gland and STA.