Publication:

A descriptive study on the surgical anatomy of external laryngeal nerve in patients undergoing thyroidectomies at a tertiary care center in South India

Background The superior laryngeal nerve divides into two branches, external and internal at the level of the hyoid bone. The relationship of the external branch with the superior thyroid artery and the upper pole of the thyroid gland is variable. Due to this it is at risk of injury while ligating the superior pedicle during thyroidectomy.

Methods The position of the external laryngeal nerve in 110 patients undergoing thyroidectomy in a tertiary care center in south India over a period of one year was assessed. The nerves were identified by opening up the Reeve’s avascular plane near the superior pole of the thyroid gland. The positions were identified and classified based on Cernea’s classification. Data was analyzed using SPSS 16.0 version.

Results The nerve could be identified on the left side in 109 cases (99.1%) and 106 cases (96.4%) on the right side. Cernea’s IIa was the most common position on the left side (46.4%), followed by IIb (35.5%) and I (17.3%). On the right side IIb was the most common position (40%), followed by IIa (36.4%) and I (20%). Overall the most common position was IIa (41.36%).

Conclusions It is possible to identify the external laryngeal branch of the superior laryngeal nerve with careful dissection. Large proportion of the position of the external laryngeal nerve is IIB, which would be at very high risk of injury if the superior pedicle is ligated without identifying it.