Study of Inferior Thyroid Artery and its Relation to the Sympathetic Chain in Full Term Fetuses

Abstract

Introduction: Familial dysautonomia and Sudden Infant Death Syndrome (SIDS) are amongst the most frequently encountered dysautonomias were sympathetic cardiac dysfunction is indicated by prolonged corrected QT interval. The therapy for long QT includes left cervical sympathectomy and administration of beta adrenergic receptor antagonists. Also, cervical and cervicothoracic sympathectomies are emerging as choices of treatment for epilepsies, Raynauds syndrome and vascular disorders of the upper extremities. There have been few studies in fetuses, inspite of the various structural anomalies encountered in the vicinity of the thyroid gland and this warrants the need of a fetal study. Aim: The present work was undertaken to study the anatomy of the thyroid gland and its neighboring structures in fetuses with a special focus on the relation of the sympathetic chain and inferior thyroid artery. Materials and Methods: A total of 54 still born fetuses procured from the Department of Obstetrics and Gynecology, SSSMCRI and KGH, Vishakapatnam after getting informed consent from the parents and getting the approval from the ethical commitee. An observational (cross sectional) study was conducted over a period of 3 years from 2013 to 2015. All the fetuses included in this study were over 36 weeks. Fetuses with neural tube defects were excluded from this study. The fetuses were embalmed by injecting 10% formalin into the serous cavities of the abdomen, cranial cavities through the orbit and into the muscles and limbs. Result: Of the 54 fetuses studied, the inferior thyroid artery had a course behind the sympathetic chain on both the sides in 24 (44%) and anterior to it on both sides in 10 (18.5 %) fetuses. The inferior thyroid artery was anterior to it on the right and posterior to it on the left in 5 (9.25%) cases and anterior to it on the left and posterior to it on the right in 13 (24%).The inferior thyroid artery passed through the sympathetic chain on the left side in 3 (5.5%) cases. In one fetus, the inferior thyroid artery was lying parallel to the sympathetic chain .The artery was absent on the left side in 2 (3.7%) and on the right in 1(1.8 %) fetus. Conclusion: Knowledge of the varied relations of the inferior thyroid artery to the sympathetic chain encountered study may act as a cornerstone for safely performing cervical sympathectomies in infants if indicated.

Keywords

• cervical sympathectomy
• middle cervical ganglion (mcg)
• sudden infant death syndrome (sids)