Position the patient with neck extended on a donut cushion with a bean bag beneath the shoulders in a modified “beach-chair” position. Make an incision approximately 1 cm below the cricoid cartilage and carry this through the subcutaneous tissues and platysma. Develop subplatysmal flaps superiorly to the thyroid cartilage notch and inferiorly to the suprasternal notch using electrocautery. After placing a self-retaining retractor, divide the strap muscles in the midline and mobilize them off the thyroid gland (see Figs. 6.2, 6.3, 6.4 and 6.5 and accompanying discussion).

Dissect the sternothyroid muscle off the thyroid and prethyroidal fascia by blunt and sharp dissection. Then retract the strap muscles laterally to expose the middle thyroid vein. Ligate and divide this vein and retract the thyroid lobe medially. Sometimes, several branches, rather than one middle thyroid vein, are encountered. These branches may be similarly ligated and divided. A Kitner or 2-0 silk suture placed in the surface of the thyroid gland may be used to help retract the thyroid gland medially. Develop the space between the thyroid gland and carotid sheath bluntly or with gentle sharp dissection. Identify and protect the recurrent laryngeal nerve, using a neurostimulator if desired.

Most PTH glands are found within 1 cm of the junction of the inferior thyroid artery and the recurrent laryngeal nerve. The superior PTH glands are usually found dorsal to the recurrent laryngeal nerve and posterior to the upper thyroid capsule. The inferior PTH glands are usually located anterior to the recurrent laryngeal nerve near the lower thyroid pole and thyrothymic ligament. Location of glands can vary widely, reflecting differences in degree of embryologic migration and extent of displacement as glands enlarge. Any fat lobule at a typical PTH gland location could be harboring a PTH gland. A fine, curved Jacobsen hemostat and a scalpel can be used to incise the fascia overlying a suspicious fat lobule allowing an underlying PTH gland to come into view. A Kitner may also be used to gently dissect in the space between the carotid sheath and the thyroid gland. This gentle dissection often causes an underlying PTH gland to come into view, the so-called “float sign.”

After identification of the PTH glands on one side, the exploration should be continued on the contralateral side. When glands on one side are located in their normal position, the contralateral gland is usually located in a similar position. Contralateral symmetry is observed 80% of the time with superior PTH glands and 70% of the time with inferior PTH glands. Ideally in a four-gland exploration, all PTH glands are identified before removing any PTH tissue. During thyroidectomy, vessels are dissected and ligated on the surface of the thyroid gland (extrathyroidal dissection). However, during parathyroidectomy, the dissection is carried out more laterally to facilitate identification of the PTH glands and avoid inadvertent devascularization. As in the case of thyroidectomy, careful dissection and meticulous hemostasis are essential.

The superior PTH gland generally resides at the posterior aspect of the thyroid lobe approximately 1 cm superior to the intersection of the inferior thyroid artery and the recurrent laryngeal nerve (Fig. 7.2A). The gland is often found within a
globule of fat. Careful dissection with a Jacobsen or right angle clamp of the fascial layers covering the gland usually aids in identification. Gentle probing with a Kitner often causes the gland to pop into view (the so-called “float sign”). If differentiation between a fat lobule and gland is still in question, a fine scissors or scalpel can be used to cut a small piece from the nonhilar aspect of the gland. A PTH gland diffusely oozes from its cut surface where fat generally bleeds from distinct small blood vessels. The sample of tissue obtained can also be sent for frozen section analysis if there is still a question.