Thyroidectomy, Subtotal

The indications for subtotal thyroidectomy are decreasing because of the lower incidence of endemic goiters, both colloid and nodular, and the increasing effectiveness of medical therapy in patients who present with thyrotoxicosis, whether this is due to Graves' disease or to nodular toxic goiter.

A definite indication for subtotal thyroidectomy is the removal of a solitary nodule in a young person, especially female, when the mass does not take up radioiodide on thyroid scan and hence is suspected of being malignant. A simple fine needle aspiration may yield a suspicious cytology. Total lobectomy ensures a better margin and allows pathologic examination of the excised thyroid lobe for multicentric foci should a malignant tumor be found. Many surgeons combine a total lobectomy on the involved side with a subtotal lobectomy on the alternate side.

The controversy as to whether surgical or medical treatment for thyrotoxicosis is desirable in patients younger than 35 to 40 years and in pregnant patients has yet to be resolved, but it is generally agreed that the use of radioactive iodine is contraindicated. Surgical removal should be considered if antithyroid drugs are tolerated poorly or required in large, prolonged doses and if thyrotoxicosis recurs after an apparently successful medication regimen. In the poor-risk patient or one who has had a recurrence of toxicity following previous thyroid surgery, medical therapy is usually the treatment of choice. Also, some pregnant patients may be best treated with antithyroid drugs in order to defer surgery until after the patient has delivered. However, thyroid replacement is given daily once the patient is euthyroid to prevent the development of a goiter in the fetus.

Subtotal thyroidectomy or total thyroidectomy is performed for an enlarged thyroid gland that produced pressure symptoms or an undesirable cosmetic effect (endemic goiter), for toxic goiters, and occasionally for inflammatory conditions such as Riedel's struma and Hashimoto's disease.

The only indication for emergency thyroidectomy is in that exceedingly rare situation where pressure symptoms develop rapidly due to intrathyroid hemorrhage. In all other situations thyroidectomy should be considered an elective procedure performed when the patient is in optimal physical health. This is true particularly in thyrotoxicosis.

Patients with thyrotoxicosis should be treated with antithyroid drugs until an euthyroid state is reached. Because the (thiourea) compounds block the synthesis of thyroxine but do not inhibit the release of the hormone from existing colloid stores, the time required for symptomatic improvement may vary widely from 2 weeks to as long as 3 months. The variability is in part related to the size of the gland, since large goiters usually contain more colloid. When the patient has become euthyroid, iodine—given as Lugol's solution, potassium iodide solution, or tablets or syrup of hydriodic acid—can be administered for 10 days before surgery (optional). If this procedure is followed, almost any thyroidectomy can be performed under optimal conditions. If significant tachycardia due to an increased intraoperative or postoperative release of thyroid hormone is encountered, propranolol should be used to control it.

Endotracheal intubation is preferred, particularly if there has been long-standing pressure against the trachea, substernal extension, or severe thyrotoxicosis. For the severely toxic or apprehensive patient, a short-acting intravenous barbiturate may be given in the patient's room to avoid undue excitement. General inhalation anesthetic agents are used.

The patient is placed in a semierect position with a folded sheet underneath the shoulders so that the head is sharply angulated backward (Figure 1). The head rest of the table can be lowered to hyperextend the neck further. The anesthetist should make certain that the head is perfectly aligned with the body before the line of incision is marked. Any deviation to the side may cause the surgeon to make an inaccurately placed incision.

The patient's hair may be covered with a mesh cap to avoid contamination of the field. The skin is prepared routinely. Before the incision is made, it may be accurately outlined by compressing a heavy silk thread against the skin. The incision should be made about two fingers above the sternal notch and should be almost exactly transverse, extending well onto the borders of the sternocleidomastoid muscles (Figure 2). In the presence of a large goiter, it should be made a little higher so that the final scar will not lie in the suprasternal notch. A short midline crosshatch may be made across the outlined incision to provide a guide to accurate approximation of the skin at closure (Figure 2). The site for the incision is then draped with sterile towels secured with towel clips at the four corners, similar to a routine abdominal draping. Transfixing sutures or staples may be placed through the towel into the skin in the middle of the incision on either side. This secures the towel at the center of the incision and avoids contamination when the flaps are reflected upward and downward. Skin towels sutured or clipped to the field may be eliminated by the use of a sterile transparent plastic drape that is made adherent to the skin with an adhesive spray. A large sterile sheet with an oval opening completes the draping.

The surgeon stands at the patient's right side, since it is customary to commence the procedure at the right upper pole. He or she should be thoroughly familiar with the anatomy of the neck, especially with the blood supply and anatomic relationships of the thyroid gland (Figures 3, 4, and 5). A thorough understanding of the anatomy of this region should lessen the complications of hemorrhage or injury to the recurrent laryngeal nerve, which may course through the bifurcation of the inferior thyroid artery, and injury to the parathyroids. A dry field is maintained if the various fascial planes are carefully considered during the procedure (Figure 3). The locations of the major blood vessels, the parathyroids, and recurrent laryngeal nerve are shown in Figures 3 and 5.

The surgeon applies firm pressure over gauze sponges to one margin of the wound, while the first assistant applies similar pressure to the opposite margin. In this manner the active bleeding from subcutaneous tissue is controlled and the margins of the wound are evenly separated. The skin incision is made with a deliberate sweep of the scalpel, dividing the skin and subcutaneous tissue simultaneously if the panniculus is not too thick. The belly of the scalpel should be swept across the tissues but not pressed into them. Bleeding vessels in the subcutaneous tissues are seized with hemostats; the large vessels are ligated, while small vessels are merely clamped and released or cauterized. Hemostats with finely tapered jaws that can be applied to the vessel alone are the best type to use, because they permit ligation without strangulation of a tab of surrounding fat. One or two mass ligatures may do no harm, but many strangulated bits of tissue cause induration and inflammation during healing since the avascular tabs must be absorbed. Electrocautery is preferred to control bleeding.

The incision is deepened to the areolar tissue plane just below the platysma muscle where an avascular space is reached. All active bleeding points are grasped with curved, pointed hemostats that are reflected upward or downward depending upon to which side of the incision they have been applied (Figure 6). Active bleeding and danger of air embolus may occur from accidental openings made into the anterior jugular vein if too deep an incision is made. Sharp dissection may be used alternately with blunt gauze dissection to facilitate the freeing of the upper flap (Figures 7 and 8). Usually, a small blood vessel will be encountered, high up beneath the flap on either side, which will produce troublesome bleeding unless it is ligated (Figures 8 and 9). The dissection goes up to the thyroid notch, exposing all of the thyroid cartilage, as well as down to the suprasternal notch. Outward and downward traction is then applied to the lower skin flap as it is freed from the adjacent tissue down to the suprasternal notch (Figure 9). At the very lowest part of the wound, care should be taken to avoid damage to the communicating arch connecting the two anterior jugular veins. If the veins or the arch is entered, the descending branches of the anterior jugular vein should be ligated below the level of the communicating arch in order to minimize the chance of air embolism (Figure 9).

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This operation is based on careful dissection of various tissue planes between the muscles, vessels, and thyroid gland. Some type of self-retaining retractor is inserted to hold apart the skin flaps. In the presence of a large thyroid gland that necessitates division of sternohyoid and sternothyroid muscles, it is advisable to free the anterior margins of the sternocleidomastoid muscles. The margins of these muscles run diagonally across the outer limits of the wound and can be identified easily. The incision is made into the fascia along the margins of the sternocleidomastoid muscle (Figure 10). The handle of the scalpel is used as a dissecting tool to develop the correct plane of cleavage between the sternocleidomastoid muscle and the outer boundaries of the sternothyroid muscle (Figures 11 and 12).

To avoid bleeding, a vertical incision is placed exactly in the midline of the neck between the sternohyoid muscles, extending from the thyroid notch to the level of the sternal notch. All bleeding points are controlled by the application of hemostats. The tissues on either side of the incision are lifted up so that the incision is not carried directly through into the thyroid gland (Figure 13). The blunt handle of the knife is inserted beneath the exposed sternohyoid muscles (Figures 14 and 15). At this point the loose fascia over the thyroid gland should be picked up with forceps and incised with the scalpel in order to develop a cleavage plane between the thyroid gland and the sternothyroid muscle (Figures 16, 17, and 18). This is one of the most important steps in a thyroidectomy. Many difficulties may be encountered unless the proper cleavage plane is entered at this time. When the fascia of the sternothyroid muscle has been completely incised and reflected, the blood vessels in the capsule of the thyroid gland are clearly visible (Figure 18). After the proper cleavage plane is developed, the sternohyoid and sternothyroid muscles are pulled outward from the thyroid gland by means of a retractor, so that any unusual blood vessel communication between the sternothyroid muscle and the thyroid gland can be clamped and ligated (Figure 18). Once the surgeon is working in the proper cleavage plane, the delivery of the gland may be facilitated by inserting the two forefingers side by side to the outer edge of the thyroid gland and separating them, thus freeing the gland without injuring blood vessels (Figures 19 and 20). If an effort is made to free the entire lateral surface of the gland by finger dissection, it must be remembered that in some instances the middle thyroid vein is quite large and may be torn accidentally by this maneuver, resulting in troublesome bleeding.

If the thyroid is only moderately enlarged, retraction of the prethyroid muscles forward and laterally by narrow retractors will give adequate exposure for the subsequent procedure; however, if the mass of thyroid tissue is large, it may be wiser to divide the prethyroid muscles between muscle clamps. There is no difficulty with healing or function after transverse incision of the prethyroid muscles if this is done in the upper third to avoid injury to the motor nerve supply. The freed margin of the sternocleidomastoid muscle on either side is retracted laterally to avoid its inclusion in the muscle clamp (Figures 20 and 21). The muscle clamps are applied over the surgeon's finger as a guide to avoid including any part of the contents of the carotid bundle. The muscle is divided between the clamps, and an incision is made upward and downward from the end of either clamp to facilitate the retraction of the divided muscles (Figure 21). If large anterior jugular veins are present, it is advisable first to ligate them with transfixing sutures of fine silk adjacent to the upper and lower clamps. The muscle clamps can then be lifted out of the wound and will not hinder the subsequent procedure. The muscles on the left side are similarly divided.

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Occasionally, as the upper muscle clamp is retracted upward and outward, a branch of the superior thyroid artery may be encountered, extending from the muscle to the surface of the thyroid gland in the region of the upper pole. This vessel should be carefully clamped and tied (Figure 22).

It is customary to begin a subtotal thyroidectomy at the right upper pole or on the larger side. Some surgeons prefer to divide the middle thyroid vein first (Figure 26), so as to improve mobility and exposure of the upper pole vessels. A narrow retractor is placed in the wound at the superior pole. Blunt dissection, which allows the thyroid capsule to be pushed away from the larynx, is best accomplished by opening a small, curved hemostat in the membranous tissue at this point (Figure 23). At the uppermost portion of the gland there is a thin fascia that almost encircles the trachea. This area must be clamped carefully, since it contains a small blood vessel that, if allowed to retract, is very dangerous to secure because of its proximity to the superior laryngeal nerve. Traction should be maintained on the thyroid gland by means of a curved hemostat or an umbilical tape snugged around the gland in the region of the upper pole. There is less chance of tearing a friable gland if curved hemostats or the umbilical tape, rather than a toothed tenaculum are used for traction. By sharp and blunt dissection the superior thyroid vessels are exposed well above their point of entry into the gland (Figure 23). The surgeon now decides whether to leave any thyroid tissue at the upper pole region and places the next clamp either at the upper limits of the gland or in the substance of the gland, perhaps 1 cm below the top of the pole. Hemostasis is effected more easily if the superior thyroid arteries are ligated extracapsularly. Moreover, if much glandular tissue is to be retained, it should be on the posterior surface at the level of the inferior thyroid arteries, as there is more likely to be a recurrence at the superior pole. Three small straight or curved hemostats are applied to the superior thyroid vessels. The vessels are divided, leaving one clamp on the thyroid side and two clamps on the vessels (Figure 24). The application of two clamps to the upper pole vessels permits a double ligation and lessens the possibility of active troublesome bleeding. Some surgeons prefer to make the second ligation a transfixing suture of fine silk (Figure 25).

If the middle thyroid vein has not already been identified and ligated, an effort should be made to locate this vessel. Often it is stretched to a thin strand as a result of traction applied to the gland in order to displace it (Figure 26). After the superior vessels and middle thyroid vein have been ligated, the narrow retractor is moved to the right lower pole, where the lower pole vessels enter the gland. These vessels are carefully freed from the adjacent structures, either with a small curved clamp or by finger dissection (Figure 27). Care must be taken not to injure the trachea at the time these vessels are divided and doubly tied (Figure 28). Occasionally, a venous plexus (or thyroidea ima) is found over the trachea entering the inferior surface of the gland in the region of the isthmus. This is carefully separated from the trachea with a blunt-nosed hemostat and ligated in the usual fashion.

As an alternative method, the surgeon may decide to start at the lower pole and luxate the gland before the upper pole is ligated. The thyroid tissue over the trachea is divided, and the right lobe is reflected outward (Figure 29). The lower pole vessels then are clamped and ligated. The middle thyroid vein is brought into view by medial retraction and can be tied easily. The upper pole is now freed by pushing the index finger behind the superior thyroid vessels. As the superior pole is pushed forward with the finger, a curved clamp may be inserted between the trachea and the medial surface of the superior pole, and the vessels can be doubly clamped (Figure 30).

After the middle and inferior veins have been ligated and the superior pole freed by either method, the next step is to expose the inferior thyroid artery. Traction is maintained anteriorly and medially as the artery is exposed on the lateral inferior surface of the gland (Figure 31). A narrow retractor is inserted laterally, and by gauze dissection the lateral aspect of the gland in the region of the inferior thyroid artery is visualized clearly. It should be remembered, especially in the presence of a large gland that has been displaced outward, that the recurrent laryngeal nerve may be much higher in the wound than ordinarily is anticipated. If a total lobectomy or extensive removal of thyroid tissue is indicated, it is necessary, by careful dissection, to identify this nerve, which may run between the bifurcation of the inferior thyroid artery as it enters the gland. The fossa posterior of the gland should also be inspected to determine, if possible, the location of the parathyroid glands, which are usually a pinkish chocolate color. Before commencing this dissection, it is wise to place hemostats on the vessels at the margins of the gland where the major branches of the inferior thyroid artery lie. The application of paired clamps to the major blood vessels at a safe distance from the region of the recurrent laryngeal nerve (Figure 32) defines the amount of thyroid tissue that will remain and lessens the chance of accidental injury to the nerve. With the trachea in view and the gland lifted into the wound, another row of small, curved hemostats is placed well into the parenchyma so that the desired amount of thyroid tissue is retained along with the posterior capsule (Figure 33). The amount of thyroid tissue allowed to remain in relation to recurrent laryngeal nerve is illustrated in Plate 184.

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With the lateral hemostats in place, the right lobe is pushed laterally, and the isthmus is exposed. If this has not already been done, the isthmus is divided. The inferior border immediately over the trachea is grasped with mouse-toothed forceps and pulled upward as a curved clamp is inserted between the trachea and the posterior portion of the gland (Figure 34). A similar clamp is inserted from the upper side. After the cleavage plane between the thyroid gland and the anterior surface of the trachea has been developed, the entire isthmus is divided between curved clamps. If the clamps enter the tracheal fascia, there will be added discomfort in the postoperative period. The isthmus is divided close to the right side of the clamps (Figure 35). The clamps remain on the left portion of the thyroid as the right lobe margin is retracted laterally (Figure 36). Curved clamps are inserted across the trachea into the parenchyma of the gland and pointed toward the lateral row of clamps (Plate 183, Figure 32). If the clamps are placed horizontally across the trachea, the points will not injure the recurrent laryngeal nerve (Figure 37). The portion to be removed is now lifted and dissected free (Figure 38). The bleeding points in the center of the remnant are clamped. Only small amounts of tissue are included. Actively bleeding points that retract, especially along the tracheal margin of the remnant, are controlled by lateral compression with the index finger. Blind clamping of thyroid tissue, particularly at the superior edge, may result in injury to the recurrent laryngeal nerve (Figure 39, point x). All bleeding points are carefully ligated. Blind, deep placement of transfixing sutures is avoided because of the risk of injury to the underlying structures. The surgeon must tie beneath these clamps with great care, preferably using a surgeon's knot on the first throw of the tie, so that the subsequent knots can be tied without keeping the ligature under tension. As a rule, the tissues have been clamped under tension, and the vessels tend to retract unless securely held by the first throw of the tie. If transfixion is required, it should be done with a small curved needle, and great care should be exercised to prevent penetration of the posterior capsule and possible injury to the recurrent laryngeal nerve.

When no bleeding points remain, the cavity may be irrigated with saline. The pyramidal lobe, which may be variable in size, is entirely removed. There is usually a bleeding point at the top of this lobe; hemostats are applied and the vessel is ligated (Figure 40). In freeing the isthmus, great care is taken to avoid injury to the thin tracheal fascia. If this fascia is torn, postoperative tracheitis and undue soreness may be encountered.

The left side is freed similarly. The additional space left by the removal of a large right lobe somewhat simplifies the removal of the left lobe. The surgeon moves to the left side and takes every precaution to protect the recurrent laryngeal nerve and effect complete hemostasis. The field is inspected for evidence of bleeding (Figure 41).

The folded sheet is removed from beneath the neck, and the tension on the chin is relaxed. The wound is repeatedly irrigated with large amounts of saline, and the field is again inspected for any bleeding.

The wound is carefully protected while the anesthesiologist introduces the laryngoscope to inspect the position of the vocal cords. If the position of the vocal cords suggests injury to either nerve, the surgeon should visualize the nerve on the involved side throughout its course and release any sutures that may have included or damaged the nerve. While the anesthesiologist is inspecting the vocal cords, the surgeon should inspect the specimen very carefully for adherent parathyroid glands. Questionable tissue must be closely inspected; any parathyroid substance found should be transplanted, preferably into the sternocleidomastoid muscle.

The operator must be familiar with the appearance of the parathyroid gland, which is a pinkish-brown flattened node about 3 to 4 mm in diameter. The superior glands are usually found on the posterior surface of the thyroid at about the level of the lower portion of the thyroid cartilage. The inferior glands are seen at the lower portion of the thyroid, usually underneath the inferior pole or lying in the fat a little below and deeper than the thyroid substance. Usually, the inferior parathyroids are seen and can be left behind when the small inferior thyroid veins and thyroidea ima vessels are first divided. Regardless of the fact that the surgeon may be certain that the parathyroid glands remain in the wound, any suspected tissue attached to the specimen is transplanted into the neck or forearm muscles.

The prethyroid muscles are then approximated. If the anterior jugular veins have not previously been ligated, they should be tied with a transfixing suture adjacent to the muscle clamps. The anterior margins of the sternocleidomastoid muscles are retracted laterally as the sutures are placed beneath the muscle clamps (Figure 42). After closure of the transverse incision, the prethyroid muscles are approximated in the midline with interrupted sutures (Figure 43). Drainage is unnecessary in a dry field; however, if a large cavity has resulted following the removal of a large nodular gland, a small closed-suction Silastic drain may be brought out through the center of the incision or through a small stab wound beneath the incision.

The hemostats are removed from the subcutaneous tissue, and all active bleeding points are ligated with fine 0000 silk ligatures or cauterized. The skin flaps are approximated, and the platysma and subcutaneous tissue are repaired in separate layers in order to mound up the tissues and obviate the necessity for tension on the skin sutures (Figure 44). The skin may be approximated with an absorbable fine subcuticular suture or with a nonabsorbable subcuticular running pull-out suture that is removed the next day. Skin tapes and a loose dry sterile dressing are applied.

The patient is immediately placed in a semi-sitting position. Adequate precautions should be taken to prevent hyperextension of the neck. Oxygen therapy is administered, 4 to 5 L per minute, until the patient has reacted. A sterile tracheotomy set should always be available in the event of acute collapse of the trachea. Parenteral fluids are given until the patient can take adequate fluids by mouth. The addition of sodium iodide and calcium gluconate depends on the patient's general condition. Liquids by mouth are permitted as tolerated. Opiates or sedatives are used as necessary.

Early complications include hemorrhage into the wound, hoarseness and temporary aphonia, vocal cord paralysis, and postoperative thyroid “storm.”

The most important postoperative complication is hemorrhage in the wound. If wound hemorrhage is suspected, the dressing is removed, several skin sutures are taken out, the blood is evacuated under aseptic conditions, and major bleeding points are ligated.

Bilateral injury of the recurrent laryngeal nerve may result in paralysis of both vocal cords and may require tracheotomy.

The salient symptoms of postoperative crisis are high fever, severe tachycardia, extreme restlessness, excessive sweating, sleeplessness, vomiting, diarrhea, and delirium. Ice caps or cooling blankets, sedation, and parenteral high-calorie fluids, to which 1 g of sodium iodide and 100 mg of corticoids have been added, are indicated. The continued administration of approximately 15 mg of a satisfactory corticoid preparation per hour in an intravenous drip is recommended. Oxygen, antipyretics, and multivitamin preparations are also administered. Propanolol may be given for the tachycardia.

Postoperative hypoparathyroidism requires calcium gluconate 10% intravenously. Vitamin D2 is administered at a dosage sufficient to maintain a normal serum calcium level. No added oral calcium other than a glass of milk with each meal is required. Thyroid replacement with levothyroxine is given daily to prevent the recurrence of nontoxic nodular goiter.

Any drains are removed on the first postoperative day. The patient is allowed to go home as soon as he or she is self-sufficient.