What techniques are used to identify all four glands during parathyroidectomy for primary hyperparathyroidism?

Updated: Oct 02, 2018
  • Author: Lawrence Kim, MD, FACS, FACE; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Answer

The most critical aspect to ensure success in this operation is identification of all 4 parathyroid glands and removal of all abnormal glands. In the case of 4-gland hyperplasia, a 3.5-gland (subtotal) parathyroidectomy is performed. Approximately 50-70 mg of the most normal-appearing tissue is left behind. A nonabsorbable suture is left as a tag to identify the gland should reoperation be necessary.

The patient is placed in the lawn-chair position with the neck extended over a transversely placed shoulder roll. This position allows full exposure of anterior neck structures and improves venous drainage.

A low transverse incision placed within the skin creases provides the best cosmetic result. The length of the incision must be adequate to allow thorough exploration of all potential locations of the parathyroid glands; however, given the elasticity of the neck skin flaps, a 2- to 5-cm incision allows safe identification of important structures.

After hemostasis of the skin incision is obtained, subplatysmal flaps are developed superiorly to the notch of the thyroid cartilage and inferiorly to the flat portion of the manubrium. The sternohyoid and sternothyroid (strap) muscles are separated in the midline to expose the thyroid gland. If preoperative localization studies suggest a parathyroid adenoma, that side is approached first.

Frequently, a middle thyroid vein may require ligation to ensure adequate mobilization of the thyroid lobe. The thyroid lobe is elevated off the common carotid artery and retracted medially. The inferior thyroid artery is identified after blunt and sharp dissection of the areolar tissue anteriorly and medially to the common carotid artery and posteromedially to the thyroid lobe. The recurrent laryngeal nerve is identified next, inferior and lateral to the lower lobe of the thyroid gland.

The intersection of the inferior thyroid artery and the recurrent laryngeal nerve is an important landmark because most parathyroid glands, superior and inferior, are located within 2 cm of this area. The superior parathyroid glands are located dorsal to the upper two thirds of the thyroid lobe and posterior to the recurrent laryngeal nerve. The inferior glands, which are less consistent in location, can usually be found inferior to the inferior thyroid artery and ventral to the recurrent laryngeal nerve. They are usually within 1 cm of the inferior lobe of the thyroid gland.

Occasionally, not all parathyroid glands can be identified. In such instances, the usual locations are reexamined first because most parathyroid glands are located in typical areas. If parathyroid glands are not identified in those locations, then a systematic search is performed, taking into consideration the path of descent of superior and inferior parathyroid glands.

Inferior glands may be located in the thyrothymic ligament. They may be difficult to identify, especially after division of the inferior thyroid vein, a maneuver that allows the gland to retract into the superior mediastinum. Another location for ectopic inferior parathyroid glands is the thymus. The thymus can be visualized through a transverse cervical incision by retracting the innominate vein dorsally while elevating the manubrium anteriorly. [28] Division of the interclavicular ligament improves visualization in the superior mediastinum.

Superior parathyroid glands are usually dorsal to the upper two thirds of the thyroid gland. Occasionally, these glands are adjacent to the superior thyroid vessels. Other locations include the carotid sheath or posterior to the esophagus or pharynx (retroesophageal). Finally, both superior and inferior parathyroid glands may be located aberrantly within the capsule of the thyroid gland. Some surgeons perform a thyroid lobectomy on the side harboring the abnormal gland after an exhaustive search is made in the aforementioned locations. Median sternotomy should generally not be performed during the initial neck exploration for hyperparathyroidism.

Abnormally enlarged glands are excised after confirmation of the normal size of other glands. During excision, avoiding capsular rupture of the abnormal gland is important because this may be associated with implantation of parathyroid cells in the operative site and subsequent parathyromatosis. Parathyroids may be identified by highly experienced surgeons based on appearance and location. In most cases, identification of the parathyroid glands should be confirmed histologically by frozen section examination. In cases of subtotal or total parathyroidectomy with autotransplantation, parathyroid tissue should be cryopreserved for future autotransplantation in case the initial transplant does not function adequately.


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