Variations in the topographical anatomy of the recurrent laryngeal nerve and the inferior thyroid artery

Abstract

OBJECTIVE: Thyroidectomy is a commonly performed surgery. Comprehensive knowledge in anatomical variation of the inferior thyroid artery (ITA) in relation to the recurrent laryngeal nerve (RLN) is mandatory for safe thyroid surgery. Data on variations in Sri Lankans is incomplete. DESIGN, SETTING AND METHODS: Thirty cadavers (20 male:10 female; range 56-87 years) were dissected to study the anatomical variations of the ITA in relation to the RLN. RESULTS: In 22 cadavers the right ITA originated from thyrocervical trunk, and in 8 it was a branch of the transverse cervical artery. On left, ITA originated from the thyrocervical trunk in 26 and from the transverse cervical artery in 4 cadavers. Branching of the artery was extra-capsular in 22(72%) on the right and 23(75%) on the left. On the right, the RLN was seen posterior to all the extra-capsular divisions of the ITA in 18(60%) cadavers, while in 7(22%) it was anterior. In 5(18%) cadavers it was between the divisions of ITA. On the left, it was 28(95%) and 2(5%) respectively (Z=2.74, P=0.006). The right RLN was seen in the tracheo-oesophageal groove in 26 cadavers (85%), while in 4(15%) it was on the antero-lateral side of die trachea. On the left, all the recurrent laryngeal nerves was seen in the tracheo-oesophageal groove. CONCLUSION: The anatomical variation is common in relation to the right RLN. These have implications in thyroid surgery and follow up.