Anatomical Variations in the Origin of Superior Thyroid Artery and its Relation with External Laryngeal Nerve and their Clinical Importance-A Cadaveric Study

INTRODUCTION The major arterial supply of thyroid gland is from superior and inferior thyroid arteries. The superior thyroid artery (STA) usually arises from the external carotid artery. The external laryngeal nerve runs in close proximity to the origin of the superior thyroid artery later leaves the artery by turning medially above or below the upper pole of the thyroid gland. MATERIAL AND METHODS A descriptive study was undertaken on 20 embalmed cadavers. The anterior triangle of neck was dissected bilaterally. The site of origin of STA level of origin in relation to the upper border of lamina of thyroid cartilage and relation of the STA with external laryngeal nerve were observed and noted. RESULTS The STA arises from the external carotid artery in 27.5%, common carotid artery in 62.5%, common carotid bifurcation in 5% and arises by a common trunk with lingual artery at common carotid bifurcation in 5%. The distance from the upper pole to the point where external laryngeal nerve turns medially is more than 10 mm in 50%, less than 10 mm in 25% and 10 mm in 25%. CONCLUSION The variations in the pattern of origin of the superior thyroid artery and its relation to external laryngeal nerve is a very common phenomenon. The head and neck surgeons must be aware of all possible variations to avoid postoperative complications and legal issues.

Origin of superior thyroid artery: under the surgeon’s knife

Background The major arterial supply to the thyroid gland is from the superior and inferior thyroid arteries, arising from the external carotid artery and the thyrocervical trunk respectively. The external laryngeal nerve runs in close proximity to the origin of the superior thyroid artery in relation to the thyroid gland. The superior thyroid artery is clinically important in head and neck surgeries. Objectives To locate the origin of the superior thyroid artery, because wide variability is reported. To provide knowledge of possible variations in its origin, because it is important for surgical procedures in the neck. Methods The origin of the superior thyroid artery was studied by dissecting sixty adult human hemineck specimens from donated cadavers in a Department of Anatomy. Results The highest incidence observed was origin of the superior thyroid artery from the external carotid artery (88.33%), whereas origin from the common carotid bifurcation only occurred in 8.33%. However, in 3.33% of cases, the superior thyroid artery originated from the common carotid artery and in a single case, the external laryngeal nerve did not cross the stem of the superior thyroid artery at all, but ran ventral and parallel to the artery. Conclusions It is important to rule out anomalous origin of superior thyroid artery and verify its relationship to the external laryngeal nerve prior to ligation of the artery in thyroid surgeries, in order to prevent iatrogenic injuries. Moreover, because anomalous origins of the superior thyroid artery are only anatomic variants, thorough knowledge of these is decisive for head and neck surgeries.

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.

SURGICAL MANAGEMENT OF MULTINODULAR GOITRE;

Background: A prospective, analytical study conducted to compare the results oftotal thyroidectomy with subtotal thyroidectomy in the management of multinodular goitre.Objective: comparison of total thyroidectomy and subtotal thyroidectomy for the managementof multinodular goitre in terms of postoperative complications. Patients and Methods: Aprospective review of 120 patients with benign multinodular goitre (bilateral) undergoing totalthyroidecotmy (Group A=60) and subtotal thyroidecotmy (Group B=60) during 2 years period(2011-12) was undertaken. Evaluation of results was done by analyzing the data in SPSS version17. Results: In group A, total thyoidectomy was done, the postoperative complications werelesser (13.33%) than group B in whom subtotal thyroidectomy was done (16.67%). Thecomplications seen in group A were seroma formation 1(1.67%), external laryngeal nerve (ELN)palsy 2 (3.34%), recurrent laryngeal nerve (RLN) palsy (temporary) 2 (3.34%) andhypoparathyroidism 3 (5.00%). The complications seen in group B were tension haematoma 01(1.67%), seroma formation 2 (3.34%), ELN palsy 2 (3.34%), RLN palsy (temporary) 3 (5.00%) andhypoparathyroidism 2 (3.34%). No mortality was seen in both groups. Conclusions: Totalthyroidectomy is better procedure than subtotal thyroidectomy for the treatment of benignmulitnodular goitre. This procedure also prevents future need of surgery for recurrence andincidental thyroid cancer.