The procedure described is one method of removing the thyroid gland. There may be differences that are equally effective.
During thyroidectomy, one or both lobes of the thyroid gland and isthmus or pyramidal lobe, if present, are separated from the underlying tracheolaryngeal framework and removed via an anterior neck incision. Care is taken to avoid injury to the surrounding structures, including the external branch of the superior laryngeal nerve and recurrent laryngeal nerve, and to prevent devascularization of the parathyroid glands.
Indications for Surgery:
- Thyroid mass with unknown significance or suspicious for malignancy result on fine needle aspiration (FNA)
- Hyperthyroidism (particularly when refractory to medical therapy or radioactive iodine therapy)
- Malignant thyroid tumors
- Symptomatic thyroid goiter (causing respiratory compromise, dysphagia, or cosmetic deformity)
- Substernal goiter
- Genetic studies or strong family history indicating high likelihood of thyroid malignancy
Contraindications to Surgery:
- Medical comorbidities that would preclude surgical or anesthesia risk
- Thyroid malignancy involving structures such as bilateral carotid arteries, pre-vertebral fascia or circumferential involvement of trachea or esophagus. Involvement of some of these structures may be considered a relative contraindication.
- Thyroid function tests should be performed to assess for hyper- or hypothyroidism.
- Ultrasonography with FNA is the recommended diagnostic tool for thyroid nodules.
- Non-contrast computed tomography (CT) or magnetic resonance imaging (MRI) is indicated in cases of malignancy involving lateral neck nodes or trachea to determine extent of disease. (In cases of thyroid cancer, CT scans with contrast will delay the administration of radioactive iodine postoperatively.)
- Radionuclide scanning may be performed in isolated cases (e.g., thyroid nodule with hyperthyroidism on thyroid function testing).
- A flexible fiberoptic laryngoscopic exam should be performed to document pre-operative vocal cord function.
Nerve monitoring for vagal and recurrent nerve stimulation
- The patient is placed supine on the operating table and general anesthesia is induced via endotracheal intubation. Otolaryngologist confirms positioning of nerve monitoring tube. Using a videolaryngoscopy allows intubation and confirmation simultaneously or a direct laryngoscopy can be performed after intubation for confirmation of monitoring probe positioning as well.
- The table is rotated 180 degrees and a shoulder roll is placed to place neck in gentle extension without the head hanging. Nerve monitor is connected and with impedance measuring < 0.1 mV.
- The anterior neck is prepped and draped.
- After injection with local anesthetic, a transverse low anterior neck incision is made approximately 1 cm below the cricoid cartilage in an existing skin crease. If the thyroid alone is to be removed, the incision should not extend beyond the anterior border of the sternocleidomastoid muscle. For some malignant thyroid tumors, the incision may extend further to incorporate a lateral neck dissection.
- Subplatysmal flaps are elevated superiorly to the level of the thyroid cartilage notch and inferiorly to the clavicle.
- The strap muscles are dissected off the thyroid bluntly and retracted laterally.
- The thyroid lobe is retracted inferomedially to expose the superior pole vessels. Care is taken to ensure that the external branch of the superior laryngeal nerve is not damaged when the superior thyroid artery and vein are ligated. The external branch of the superior laryngeal nerve is identified approximately 10% of the time. Ligating the vessels as close as possible to the superior pole of the thyroid decreases the risk of injury to the nerve.
- The superior parathyroid gland is carefully dissected away from the trachea and pushed laterally to preserve the blood supply along its lateral aspect.
- Dissection is carried inferiorly along the lateral aspect of the thyroid gland. It is important to stay on the thyroid capsule as close as possible to the thyroid gland.
- If present, the middle thyroid vein is ligated.
- The thyroid lobe is dissected free and mobilized from the tracheolaryngeal framework, allowing the lobe to be rotated medially away from the tracheoesophageal groove.
- The recurrent laryngeal nerve (RLN) is identified and traced superiorly with care to preserve all of its branches. On the left side, the RLN is usually within the tracheoesophageal groove. In 50-55% of cases, it is deep to the inferior thyroid artery, in 30-33% it is between the branches of the inferior thyroid artery and in 11-12% it is deep to the inferior thyroid artery. On the right side, the RLN travels a more lateral course. In 47-50% of cases, the nerve travels between the branches of the inferior thyroid artery, in 26-33% of cases, it travels superficial to the inferior thyroid artery and in 18-25% the nerve is deep to the ninferior thyroid artery. In 10% of patients, the RLN may be a "non-recurrent" nerve and found higher at the cricothyroid joint. A non-recurrent RLN is associated with a retroesophageal sublclavian artery.
- The inferior thyroid artery and vein are ligated with the recurrent laryngeal nerve protected and inferior parathyroid in view to preserve its blood supply.
- If a parathyroid gland is resected or devascularized (turns dusky and brown), it may be cut into small pieces or morselized and reimplanted in the sternocleidomastoid muscle. If done, the pocket is marked with colored sutures or staples.
- The isthmus is transected and the thyroid lobe is removed from the posterior suspensory ligament or Berry's ligament. This ligament firmly attaches the gland to the cricoid cartilage and the 1st and 2nd tracheal rings.
- The surgeon inspects the specimen for parathyroid glands prior to passing off the specimen to pathology. If any parathyroid glands are found, they can be removed from the specimen, morselized and implanted within a pocket of the sternoleidomastoid muscle and labeled with a clip.
- If a total thyroidectomy is indicated, the identical procedure is performed on the contralateral thyroid lobe.
- After the specimen is removed, the wound bed is irrigated and checked for hemostasis.
- A drain may be placed in the thyroid bed.
- The strap muscles are reapproximated and closed in the midline. The incision is then closed in two layers.
- Care of the patient is returned to the anesthesiologist for extubation and recovery.
- Admission for thyroid lobectomy is at the discretion of the surgeon; most will admit patients after total thyroidectomy or completion thyroidectomy.
- If total or completion thyroidectomy is performed, the patient should be assessed for symptoms of hypocalcemia (e.g., perioral paresthesias, Chvostek's sign, Trousseau's sign) with monitoring of serum calcium levels every 6-8 hours, given the risk of hypoparathyroidism. Calcium (oral or IV) and vitamin D replacement are given as indicated.
- The postoperative physical exam should assess for hoarseness, voice changes, and airway compromise. If symptomatic, a flexible fiberoptic laryngoscopic exam can be performed to evaluate vocal fold mobility.
- Postoperative airway distress is an emergency requiring immediate patient evaluation. The differential diagnosis includes hematoma, bilateral recurrent nerve dysfunction, postobstructive pulmonary edema, pulmonary embolus, and myocardial infarction. If a hematoma is present, it should be evacuated at the bedside if respiratory compromise is life-threatening.
- Drain output is monitored, and the drain is removed when output has decreased sufficiently.
- Antibiotic ointment may be applied to the incision three times a day.
- If total or completion thyroidectomy is performed, the Endocrinology service should be consulted to provide recommendations for thyroid hormone replacement regimen. Cytomel (T3; liothyronine sodium) is often given in the immediate postoperative period in patients with thyroid cancer, because it can be withdrawn more readily than levothyroxine (T4) in preparation for radioactive iodine therapy.
- The patient may be discharged after drain removal. If the patient continues to be hypocalcemic, the Endocrinology service should be consulted for discharge recommendations regarding calcium and vitamin D supplementation.
- Bleeding or hematoma – an expanding hematoma is an emergency and should be opened to evacuate the blood.
- Wound seroma
- Vocal fold paralysis due to unilateral recurrent laryngeal nerve injury
- Stridor requiring tracheostomy due to bilateral recurrent laryngeal nerve injury
- Voice changes (e.g., problems with pitch variation) due to injury to external branch of superior laryngeal nerve
- Injury to parathyroid glands, hypocalcemia