Preservation of parathyroid vascularization in thyroid surgery: morphological study and surgical implications

The aim of this work was to study the vascularization of parathyroid glands (PTG) and determine the features that may influence its preservation. Based on those findings we propose surgical strategies to preserve the parathyroid vascular supply in thyroid surgery.

A study of the vascular supply of 110 PTG was performed in 30 cadaver specimens. The thyroid arteries were cannulated and injected with an isoprene polymer. Data collection included: number and location of PTG and information about their vascular supply: origin, number of arteries, length, course, relation with recurrent laryngeal nerve (RLN) and thyroid lobe. There were determined the most variable features and the most consistent features about PTG arteries.

The vascular supply of PTG was provided by a terminal artery. The PTG's hilum was related to the thyroid surface. The PTG received 1 vessel in most cases, with no significant difference between the superior and inferior PTG (P = 0.111). The superior PTG received a vessel from the posterior branch of inferior thyroid artery (ITA) in 49 cases (87.5%) and the inferior PTG received a vessel from the anterior branch of ITA in all 54 cases (100%). The length of the arteries was on average 7 mm and the arteries to inferior PTG were smaller (P = 0.004). The artery to superior PTG described a cranial course in 40 cases (71.4%) and the artery to the inferior PTG described a caudal course in 31 cases (57.4%) (P < 0.001). The parathyroid arteries were located anterior to the RLN in most cases. The arteries to superior PTG were all posterior to the thyroid lobe and the arteries for inferior PTG were posterior to the thyroid lobe in 48 cases (88.9%) and course through the thyroid parenchyma in 6 cases (11,1%). All PTG arteries were located lateral to the attachment of the pretracheal layer of the deep cervical fascia to the trachea.

The origin, number, course and length of the parathyroid arteries are variable, which influence its preservation. There are some consistent features that can guide thyroidectomy. The PTG should be retracted from medial-to-lateral direction from the thyroid surface to protect their hilum. The PTG located anterior to the thyroid lobe may need to be re-implanted, once their artery crosses thyroid parenchyma. The area posterior to the thyroid lobe, anterior to the recurrent laryngeal nerve and lateral to the pretracheal layer of the deep cervical fascia should be spared from dissection and vessel ligation, once is the main territory for PTG arteries.