An incision is made in a skin crease about 2 cm cephalad to the clavicles. Once a surgeon gains more experience with this procedure, the transverse incision decreases in length from about 8 cm to about 4-5 cm. This generally results in an imperceptible scar, and negates the benefits of endoscopic assisted thyroidectomy, a much more complex and lengthy procedure. Superior and inferior flaps are raised in a subplatysmal plane. These really only need to be done in between the sternocleidomastoid muscles as more lateral dissection does not improve visualization. This is the basis for reducing the size of the incision to 4 cm in primary cases.
The strap muscles are separated in the midline and elevated off of the thyroid gland. Only in rare circumstances (extremely enlarged goiter, direct cancer invasion) are the strap muscles divided. These muscles assist in swallowing and so are preserved intact when possible. The thyroid gland is now exposed. We prefer to divide the superior pole vessels primarily, as this allows improved mobilization of the thyroid gland and facilitates dissection of the RLN. The initial step is to separate the thyrotracheal fascia between the medial aspect of the superior pole and the upper trachea and larynx. Blunt dissection forms a plane between these structures that allows mobilization of the superior pole, allowing it to be brought inferiorly into the surgical field. This mobilization is another method that permits the use of small incisions. The external branch of the superior laryngeal nerve can usually be seen entering the cricothyroid muscle. Blunt dissection ensures that it is free of the superior thyroid artery and veins as they enter the thyroid gland. The vascular bundle is divided and ligated, allowing the superior pole to be mobilized inferiorly and medially.
Dissection on the thyroid capsule inferiorly encounters the middle thyroid vein, which is now divided. The gland is now freely mobile in its superior half, facilitating further dissection. Medial retraction on the gland exposes the fibrofatty plane between the carotid artery and the trachea. Blunt dissection just above the most inferior aspect of the gland and at approximately a 60-degree angle referenced to the trachea will quickly expose the pulsating inferior thyroid artery. This can be followed medially. Just lateral to the tracheoesophageal groove, the RLN follows a course of variable reference to the artery: generally deep but it can also intertwine or be superficial to it. At this time the parathyroid glands can usually be identified. As long as meticulous dissection has freed all tissue of the thyroid capsule, the parathyroid glands are generally found within a 2 cm circumference based at the junction of the inferior thyroid artery and the RLN. The nerve is then followed to its entry into the larynx near the cricothyroid joint. During this dissection, it is imperative to make sure the parathyroid glands retain their vascular supply. It is quite easy to expose the nerve and leave the parathyroid glands medially, thus robbing them of their blood supply resulting in hypoparathyroidism.
As the nerve enters the larynx, there is routinely a fine tongue of thyroid tissue that is intimately involved with the nerve. Careful dissection in this area will reduce the amount of residual uptake seen in posttreatment 131I scans. Also, there are several thin-walled vessels that accompany the nerve and gland in this area which bleed persistently until controlled. It is important to use bipolar cautery in this region to prevent damage to the RLN by the dissipated energy from a unipolar cautery. Once the nerve has been dissected free, the inferior thyroid veins are ligated and unipolar cautery is used to free the gland from the trachea (separate Berry's ligament). If a cancer operation is to be performed, the contralateral lobe is dissected similarly. If there is doubt as to the pathology of the lesion, it is sent for frozen section. If cancer cannot be confirmed, then the isthmus is dissected free and a right angle clamp is passed between the isthmus and the contralateral lobe. The ipsilateral lobe and isthmus is then removed and the stump of thyroid is suture ligated.
The wound is copiously irrigated and meticulous hemostasis is achieved. Small suction drains can be placed with no deleterious effects to the RLN, but they are not always necessary. We now close our wounds with 4-0 Vicryl sutures to reapproximate the platysmal layer and then 4-0 Biosyn subcuticular sutures. This allows the patient to have no sutures removed, reduces the chances of hypertrophic scar, and once a Tegaderm dressing is applied, lets the patient shower in the first postoperative day.
Was this article helpful?