© Springer Science+Business Media New York 2015
Amy L. Halverson and David C. Borgstrom (eds.)Advanced Surgical Techniques for Rural Surgeons10.1007/978-1-4939-1495-1_1717. Thyroid Surgery
(1)
General Surgery, Gwinnett Surgical Associates, Lawrenceville, GA 30046, USA
Introduction
Surgeons have performed thyroid surgery safely since the changes developed and instituted by Theodore Kocher in the late nineteenth century for which he was awarded the Nobel Prize in 1909. Thyroid diseases can be treated with minimal risk of complication by experienced high volume surgeons as well as the excellent and careful rural surgeon who may not perform as many thyroidectomies in their practice. Understanding the indications of the procedure; knowing the anatomy of the thyroid gland, recurrent laryngeal and superior laryngeal nerve and parathyroid glands; performing the procedure meticulously; and avoiding the complications can lead to a successful outcome in these sometimes challenging patients.
Indications
Thyroid surgery is indicated for the treatment of thyroid diseases that can be classified into malignant disease, thyroid nodular disease including symptomatic or increased risk of cancer development, or hyperthyroid disease states. The clearest indication is for thyroid malignancy that has been determined with preoperative fine needle aspiration. Papillary cancer can often be diagnosed on FNA, but follicular carcinoma commonly requires removal of the nodule with histological determination of capsule invasion for follicular cancer to be diagnosed. Hurthle cells can also be seen, which are a type of follicular cells with an increased risk of malignancy. Thyroid nodules can also be classified as atypical or indeterminate on the cytological evaluation of the FNA specimen with surgery being a viable plan of care as well as observation or repeat biopsy. Nodules which have increased in size, are larger than 4 cm, are “cold” on nuclear scan, or occur in patients with a strong family history or exposure to radiation all have an increased risk of developing malignancy. A complex cyst may be indicative of a degenerating tumor and does not convey the sense of benign disease seen with other cysts seen throughout the body. Thyroidectomy is indicated if a large cyst recurs or persists after aspiration. In addition to malignant or potentially malignant disease, thyroidectomy may be indicated in patients with symptomatic thyroid enlargement becoming symptomatic goiters as they interfere with swallowing and eventually airway obstruction. A toxic thyroid adenoma is a clear indication for thyroid lobectomy with an excellent cure rate of these patients’ hyperthyroidism. Thyroidectomy, thyroid medications, and/or I 131 therapy can treat Graves disease or hyperthyroidism. Near total or total thyroidectomy provides an excellent cure rate, avoids the risk associated with radioactive iodine therapy, achieves its result quickly immediately after surgery, and avoids the risk of malignancy developing in a nodule exposed to radioactive therapy in the future.
Operative Technique
Patient is placed under a general anesthetic and in the semi-fowler (beach chair) position with the neck extended gently. A standard Kocher incision is made approximately 2 fingerbreadths above the sternal notch in or along the direction of a skin crease. The thin platysma muscle is divided in the same direction as the skin incision. Subplatysmal flaps are then raised with electrocautery in the avascular plane below the muscle while elevating the muscle with several Allis clamps. The dissection is carried superior to the thyroid cartilage and inferiorly to the sternal notch. The next layer, the investing fascia of the strap muscles, is opened in the midline from sternal notch to thyroid cartilage staying between the muscles and blood vessels and above and on top of the thyroid isthmus. Next the strap muscles are freed from the thyroid gland in another avascular plane. As this plane is developed, the strap muscles are elevated and retracted laterally exposing the surface of the thyroid gland. The middle thyroid vein is then divided as the gland is rotated medially between right angle clamps and ligated with silk suture. As the strap muscles are retracted laterally with retractors, the gland is mobilized medially after division of the middle thyroid vein. The superior pole is then dissected free with a right angle clamp and divided between 2- silk suture ties or right angles. This can be a potential site of bleeding postoperatively and secure ligation is imperative. A newer technique using a harmonic scalpel or blood vessel coagulating device can be used, but we prefer to at least ligate the superior thyroid artery to prevent bleeding. Above the superior aspect of the gland lies the external branch of the superior laryngeal nerve, which should be looked for to prevent injury during the superior dissection and take down of the superior pole. After take down of the superior pole the gland is rotated medially and inferiorly. The recurrent laryngeal nerve is next identified in the tracheal esophageal groove. The gold standard is to identify the nerve and trace it up to the thyroid cartilage as the thyroid gland is dissected away. The nerve is identified with blunt dissection and classically has a blood vessel traveling along its superior surface, the so-called racing stripe. The use of a nerve monitor may assist in identifying the nerve but it has not replaced the visualization of the nerve as a means to prevent injury. We do not routinely use a nerve monitor, having found that it is not needed to locate the nerve in our cases and requires some experience and training for the monitoring device and endotracheal tube to become useful. After careful dissection of the gland away from the nerve, identification of the superior and inferior parathyroid glands is necessary. The superior glands are commonly located along the back and side of the gland superior to the nerve. The inferior glands are more variable and often found within a centimeter of the recurrent laryngeal nerve. They are identified by their characteristic brown pigmentation and are small with a tenuous blood supply, which needs to be preserved and handled delicately. Multiple branches of the inferior thyroid artery are divided as they enter the gland. Commonly we dissect the gland away from the recurrent laryngeal nerve and divide the vessels as they enter along the inferior aspect of the gland. As the gland is mobilized away from the nerve, it is retracted medially and superiorly and off of the trachea as Berry’s ligament is divided. The pyramidal lobe extends superiorly above the isthmus and is removed with the gland. The isthmus may be divided and the lobe removed. In a total thyroidectomy we often leave the isthmus intact and place the gland on top of the skin as we operate on the opposite lobe. A total thyroidectomy should remove the entire gland. A near total thyroidectomy may leave a small portion of the gland near the nerve and parathyroid glands to lessen the likelihood of injury. A subtotal thyroidectomy can leave a rim of normal thyroid tissue along the trachea and near the recurrent laryngeal nerve. Although leaving a moderate amount of tissue may decrease the likelihood of the need for thyroid replacement, this needs to be weighed against the chance of enlargement and growth in the future resulting in recurrent hyperthyroidism in patients with Graves disease. As the thyroid gland can be vascular, especially in the Graves disease patient, care is taken to carefully dissect the gland without entering its capsule with the result of brisk bleeding. When performing a subtotal procedure, we will over sew the remaining parenchyma prior to division with interrupted 3-0 silk sutures. After completion of the resection, the neck is irrigated and inspected carefully for hemostasis with any bleeding sites suture ligated to prevent a postoperative bleed or hematoma. We do not use drains even in enormous gland resections, and drains should not be relied upon to prevent a postoperative hematoma if hemostasis is not adequate. Rarely will we use Surgicel if oozing occurs, but will not close the neck if any bleeding or oozing is seen. The neck is then closed with interrupted 3-0 silk sutures in the investing fascia, which was opened in the midline. The platysma muscle is reapproximated with interrupted 3-0 Vicryl sutures. The skin is closed with a running 4-0 Vicryl subcuticular suture. The scrub nurse maintains her sterile instruments and field until the patient is extubated and the airway is proven to be adequate. A bilateral recurrent laryngeal nerve injury will leave the vocal cords paralyzed rendering the airway inadequate requiring an emergency tracheostomy. A rapidly developing hematoma may obstruct the airway and require immediate evacuation to relieve an airway obstruction. We do not routinely have the anesthesiologist examine the cords on extubation. We have a sterile trach tray accompany the patient in the recovery room and surgical floor as a postop hematoma bleed can obstruct the airway rapidly.