Surgical management

Abstract

Abstract The surgical treatment of secondary hyperparathyroidism is based on a perfect knowledge of parathyroid anatomy and embryology. Whatever the procedure chosen it is necessary to find and expose all parathyroid glands. The parathyroid glands arise as proliferation of endodermal cells at the lateral tip of the third and fourth pharyngeal pouches. The third pouch gives rise to the inferior parathyroid (PIII) gland and to the thymus. This common origin explains the tight anatomical links of both inferior parathyroids and thymus. The fourth pouch gives rise to the superior parathyroid (PIV) gland. The parathyroid bodies migrate in the 13–14 mm embryonic stage. An important anatomical event occurs with the deflexion of the neck and the descent of the heart and the large vessels. The inferior parathyroid gland (PIII) dragged by the thymic sketch descends toward the upper mediastinum. It is abandoned more or less at the same height as the lower thyroid pole or within the thyro-thymic ligament. During its migration the inferior gland may be left very high above the upper thyroid pole (parathymus) or very low into the anterior and upper mediastinum with the thymus. The migration of the superior gland (PIV) is short and this gland remains close to the posterior part of the middle thyroid lobe. The superior glands are never far from the lower thyroid artery. In 85% of cases they are located less than 2 cm from the crossing between the lower thyroid artery and the inferior laryngeal nerve. This crossing explains the more or less tight links of the superior and inferior glands near the lower thyroid artery.