Postoperative Complications of Thyroid Surgery RICHARD B. CATTELL
GREAT improvements have been made in the surgical treatment of diseases of the thyroid. The good results that have been obtained by this method of therapy are best reflected in the satisfactory results that are obtained following adequate procedures for proper indications yet with a low morbidity and operative mortality. The low incidence of complications following thyroid operations is due to a number of important factors. Among the most important is the improved preparation of patients with hyperthyroidism for thyroidectomy by use of the antithyroid drugs so that even the most toxic patient after proper preparation comes to surgery in an euthyroid state. The acceptance of general anesthesia administered through an endotracheal tube is an important aid in carrying out thyroidectomy. It not only provides for the comfort of the patient but also permits control of the respiratory exchange which under other circumstances may be less well controlled. General anesthesia also has made possible improvements in the technical conduct of thyroidectomy under the best possible conditions. Surgical removal is the only treatment of the discrete adenoma of the thyroid as well as of diffuse nodular or adenomatous goiter when an operative indication is present. Similarly, surgical treatment offers the best chance for eradication of malignant disease of the thyroid and this may be combined with postoperative roentgen therapy. Subtotal thyroidectomy for hyperthyroidism has long been recognized as a satisfactory treatment for hyperthyroidism and should be employed for the diffuse toxic goiter as well as for nodular goiter with hyperthyroidism. At the Lahey Clinic approximately 2,700 patients with hyperthyroidism of both types have been prepared for operation with antithyroid agents and submitted to subtotal thyroidectomy. This experience has enabled us to determine the incidence of complications and surgical mortality in a large group of unselected patients with hyperthyroidism so treated, as well as to evaluate the end results of such therapy. 867
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Postoperative complications are common to all types of thyroid surgery but by proper surgical management will be infrequent. A study of the postoperative complications permits one to determine their cause so that greater emphasis may be placed on their prevention. In general, technical complications of thyroidectomy may be avoided by an anatomical approach to the gland and the nearby structures. It can be done successfully only by deliberate dissection with full identification of all the structures that must be dealt with. The technique of the various thyroid operations will not be discussed but it should be stated that structures such as the recurrent laryngeal nerve, major blood vessels to the gland and the parathyroid glands must be identified and dealt with satisfactorily. Any operative method which is designed to stay away from and avoid identification of such structures is considered less satisfactory. Complications may be encountered during the operative procedure and the immediate postoperative period in the hospital, as well as at any time subsequently. Those occurring during the operative procedure are not part of this discussion and we are most concerned relative to those that endanger the life of the patient during the immediate postoperative period. The complications following thyroid operations can be divided into those of (1) the wound, (2) those altering respiration and (3) those due to abnormal function. WOUND COMPLICATIONS
Edema
The most common difficulty encountered with the thyroid incision is edema of the skin flap. This is usually of little importance and subsides within a few days. It is no doubt increased by the use of absorbable suture material and by the division of the prethyroid muscles, yet it can be minimized by good hemostasis, careful suture of the divided muscles and by means of a pressure dressing. It is most noticeable following operations for thyroiditis, when the entire flap may become brawny and indurated. This edema may extend to the deeper layers of the neck, particularly following operations for thyroiditis, intrathoracic goiter or malignancy. Edema may be a very conspicuous feature following radical neck dissection with ligation of the cervical branches of the main lymphatic trunks. It may become quite troublesome when bilateral neck dissection with ligation of both the internal jugular veins is done concomitantly or even as an interrupted procedure. Edema of the flap or neck is unrelated to whether wound drainage is employed. It is best treated by the application of heat with flaxseed poultices beginning the third or fourth day.
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Accumulation of Serum
The accumulation of serum in the wound occurs in proportion to the extent of the operative procedure, being most marked following neck dissection where wide dissection of skin flaps is necessary. Careful observation of the wound is necessary during the first two weeks after operation to make certain that serum accumulation does not occur without being released since negligence in this matter may result in a broader scar or an adherent unsightly one. If serum tends to accumulate with or without previous wound drainage, it is best to insert a small rubber tissue drain for a few days to prevent its reaccumulation. Infection
Infection in a thyroid wound is quite rare, yet an occasional instance will occur in the presence of unrecognized infection in the skin of the neck. It may follow operations for the rare acute inflammations of the thyroid, and some degree of infection is found in all patients requiring tracheotomy. Infection in thyroid wounds occurs less frequently than in other clean surgical wounds. Treatment is the same as for any other infected wound. Hemorrhage
Postoperative hemorrhage is one of the most serious postoperative complications and unless recognized early, is fraught with grave danger. This complication and respiratory obstruction constitute the two most important dangers during the immediate postoperative period. The danger of secondary hemorrhage decreases in an inverse proportion to the time after operation so that one must be most alert during the first and second postoperative days. The least serious type of hemorrhage following operation is evidenced by ecchymosis and fullness of the skin flap and is usually due to uncontrolled venous bleeding from the flap and the veins in the cervical fascia. Infrequently, a patient will be encountered who has an unrecognized low prothrombin synthesis which is readily controlled by the use of vitamin K. Fullness of the flap with or without ecchymosis with any noticeable change in respiratory exchange should lead to immediate reoperation. If respiratory obstruction is increasing, the patient should not be left unobserved and the surgeon must always consider opening the wound in bed. Arterial hemorrhage, usually from the superior thyroid artery, is often accompanied by respiratory difficulty, and immediate opening of the wound is essential and life-saving. Any delay must not be countenanced since complete respiratory obstruction may ensue within a few minutes.
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It has been found necessary to open the thyroid wound in approximately 1 in 300 patients. In most of these the bleeding is of venous origin, and it may not be possible to determine the point of bleeding on exploration of the neck. Capillary bleeding can be effectively controlled by the use of Gelfoam. Whenever the neck is opened, the muscles should be separated in the median line to make certain that clots are not forming in the thyroid compartment. About one in 750 patients has arterial hemorrhage of serious import. The most frequent site is from the superior thyroid artery. Postoperative hemorrhage is a preventable complication and should occur infrequently, but it must always be remembered as a possibility after any thyroid operation and recognized immediately. Ligation of both superior and inferior thyroid arteries is performed routinely in all subtotal thyroidectomies and decreases the danger of postoperative hemorrhage. Scars
Unsightly scars are a rare occurrence if proper care is exercised during the immediate postoperative period. If when the incision is made the lower flap of the incision is released somewhat so that it permits accurate approximation to the widely dissected upper flap, increased prominence of the upper flap can be avoided. In those patients in whom drainage has been used, the incision may be caught at that point, but this may be dealt with satisfactorily by neck exercises and by pulling down beneath the point of attachment at frequent intervals. Subsequent excision of unsightly scars is occasionally necessary but this further operative intervention is usually confined to the patient who forms keloid scars. If secondary excision of such keloid scars is done, it may be helpful to give a light dose of roentgen therapy to the scar during the immediate postoperative period. The use of hyaluronidase injected into such an incision scar during the postoperative period has been recommended but has not been utilized sufficiently to evaluate it. The incision scars of a radical neck dissection need not be unsightly if they are properly placed and a good plastic closure is effected. RESPIRATORY OBSTRUCTION
Inadequate respiratory exchange can occur any time during the operative procedure or during the postoperative period. By use of the endotracheal tube a free airway is maintained during operation and it is used for all thyroid operations except for the removal of small, discrete adenomas. It is essential in operations for hyperthyroidism, thyroiditis, intrathoracic goiter, recurrent hyperthyroidism and for malignant disease.
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Edema of Larynx
The commonest cause of postoperative respiratory obstruction is edema of the larynx resulting in a diminution of the glottic space, with or without limitation of the motion of one or both cords. During recovery from general anesthesia after removal of the endotracheal tube, the patient must be closely observed to be certain that spasm does not occur. Usually, by observation for a few minutes following removal of the tube the surgeon can make certain that this does not occur. Edema of the larynx usually develops on the second or third postoperative day and is suspected when hoarseness or voice change occurs at this time with an unaltered voice the first day. Indirect laryngoscopy permits one to determine whether there is an adequate airway between the cords. If an undue amount of stridor is present, tracheotomy should be done and it is possible to remove the tube by the fifth postoperative day. Limitation of one or both cords under such circumstances may disappear quickly but a temporary paralysis of one cord may be present for as long as four weeks. In the presence of myxedema, edema of the cords may persist for a considerable period. In the presence of thyroiditis, the edema of the larynx is also accompanied by edema of the entire incision area. Nerve Injury
Injury to the recurrent laryngeal nerve is an inherent danger in every thyroid operation. In an attempt to reduce this complication to a minimum, exposure of the recurrent laryngeal nerves throughout their course in the neck, as proposed by Dr. Lahey* in 1938, has been routine in this clinic. In approximately one in 1000 operations the nerve is not recurrent on one side but passes into the larynx directly from the vagus. One must be aware of this possibility in order to avoid injury under these unusual circumstances. The greatest danger to the recurrent nerve is in operations for recurrent hyperthyroidism, carcinoma of the thyroid and intrathoracic goiter. In order to carry out adequate subtotal thyroidectomy for hyperthyroidism it is essential to be able to visualize the course of the nerve during the removal of the thyroid. Temporary paralysis may result from rough handling of the nerve, but permanent paralysis is usually due to inclusion in the suture or actual division. If the nerve is inadvertently cut and recognized, immediate resuture is unsuccessful. When unilateral cord paralysis is present there is always change in the voice, but there mayor may not be any accompanying respiratory diffi-
* Lahey, F. H.: Routine dissection and demonstration of the recurrent laryngeal nerve in subtotal thyroidectomy. Surg., Gynec. & Obst. 66: 775-777 (Apr.) 1938.
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culty. It is impossible to determine the temporary or permanent nature of the paralysis in less than six weeks, as the patient may recover from temporary paralysis at any time during this period. If immobility of the cord persists for longer than six weeks it can be assumed to be permanent. Injury to both recurrent nerves with rare exceptions produces respiratory obstruction of sufficiently severe degree to demand tracheotomy. No attempt at correction of this condition other than the use of tracheotomy should be made for a period of three months, following which submucous resection of one cord, as proposed by Hoover, or fixation of one arytenoid in a partial lateral position (King operation) can then be planned. Either of these operative procedures provides an adequate glottic space with reasonable preservation of the voice. In our experience, injury of one recurrent nerve occurs in 1 per cent of thyroid operations, not including the incidence occurring in operations for carcinoma in which the thyroid is completely removed for invasive malignancy, and elective division of the recurrent nerve is carried out in those cases in which the nerve is found to be invaded by the growth. Nerve injury is five times as frequent in operations for recurrent hyperthyroidism as in primary operations for this condition. It becomes quite essential because of this incidence to be certain that the nerve is identified during operations for recurrent hyperthyroidism. Mild degrees of obstruction postoperatively are tolerated well in the usual patient but there is one group of patients who do not tolerate obstruction. The thyrocardiac patient who has established auricular fibrillation or past cardiac decompensation will not stand any degree of respiratory obstruction. Early tracheotomy may be lifesaving under such circumstances, since oxygen deprivation or reduction in the coronary arteries for only a short time may result fatally. Because of this, prophylactic tracheotomy at the conclusion of thyroidectomy has been practiced in a number of severe thyrocardiacs. Half of the mortality in thyroid surgery falls in this group of patients and prophylactic tracheotomy offers the only means of reducing this mortality. We have observed hemiplegia postoperatively in 2 patients in whom no arteriosclerosis was present; this complication was attributed to anoxia resulting from reduced cerebral circulation. Both of these patients recovered from operation but one was left with weakness in the right arm. Early tracheotomy might have prevented paralysis in these 2 cases. Collapse of the Trachea
Collapse of the trachea following operation is rare, if it occurs at all. We have observed it only when portions of several tracheal rings have been removed for malignant disease, when malignancy invaded and
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compressed the trachea without the possibility of removing it surgically, or in patients with Riedel's struma. It is well recognized in patients with large nodular goiters which compress the trachea, that when the goiter is removed, irrespective of the duration of the distortion of the trachea, the tracheal rings spring back into normal position and the tracheal aperture is adequate. Except for the circumstances mentioned, collapse of the trachea does not occur, but when it is thought to have occurred, it is most likely due to a recurrent nerve injury, to massive edema or to arterial hemorrhage beneath the muscles. Injury to the superior laryngeal nerve is rarely observed but may occur in the removal of any large goiter, and especially in radical neck dissection. Except under the latter circumstance, isolation and division of the superior thyroid vessels are carried out approximately 1.5 cm. below any portion of the nerve's course into the larynx. This complication can be suspected when two groups of symptoms are present: first, change in the voice, and second, difficulty in swallowing. The voice change is the result of paralysis of the single motor branch to one of the tensors of the cords. This voice change persists only a few days. The difficulty in swallowing is the result of injury to the sensory component, which is the main portion of the nerve, which produces anesthesia to that side of the larynx so that in swallowing fluids, the reflex for closure of the glottis is absent and the fluid passes into the trachea. Under these circumstances swallowing can be accomplished without difficulty by holding fluid in the mouth, leaning well forward with the chin down and swallowing in that position. The cross sensory innervation takes over function so that there is no difficulty in swallowing by the fifth or sixth day. Tracheotomy
Constant awareness of the possible necessity for tracheotomy after any thyroid operation is one of the most important details of postoperative care. Any case which exhibits increasing stridor with or without swelling in the neck calls for a decision relative to the need for tracheotomy. If adequate respiratory exchange is present, indirect laryngoscopy may show tracheotomy to be unnecessary. If stridor increases, however, preparations should be made for tracheotomy and with rare exceptions, it should be accepted. Delay in its acceptance is the most frequent cause of a surgical fatality following thyroid operations. We accept prophylactic tracheotomy in certain thyrocardiac patients, an appreciable number of patients operated upon for recurrent hyperthyroidism, as part of many radical neck dissections, and finally in any patient in whom rapidly increasing respiratory obstruction develops during the immediate postoperative period.
Richard B. Cattell
874 ALTERED FUNCTION
Recurrence
Following the removal of a discrete adenoma of the thyroid, there should be no recurrence. In such an individual, however, there is the same opportunity to develop a new adenoma as in any other. Should a nodular recurrence be found, it usually means a mistake in the initial diaghosis, as most of these are diffuse nodular goiters at the initial procedure that could not be demonstrated by careful examination of both lobes. Diffuse nodular or adenomatous goiter has a very low incidence of recurrence in spite of the fact that not all of the nodular tissue is removed. Some hypertrophy of the remnants occurs and unless the enlargement is rapid, suggesting malignancy, further operative interference is rarely indicated. In diffuse nodular goiter with 'hyperthyroidism the incidence of recurrence of hyperthyroidism similarly is low. In a recent study of 1600 patients with hyperthyroidism observed over a period of years no recurrence of hyperthyroidism was noted in patients operated upon for diffuse nodular goiter with secondary hyperthyroidism. In our experience, approximately 2 per cent of patients operated upon for primary hyperthyroidism or diffuse hyperplastic goiter have recurrent symptoms. This incidence undoubtedly is related to the amount of thyroid tissue removed at the original operation although this is not the sole factor in its development. The recurrence rate increases the longer patients are followed. Undoubtedly, recurrent symptoms in the future with the type of subtotal thyroidectomy done today will occur in few instances. Over half of the patients with recurrent symptoms can be relieved by nonoperative methods, by the intermittent use of iodine, antithyroid agents, or by radioactive iodine. If large recurrent remnants are encountered, it is our practice to advise subtotal excision of thyroid remnants. If operation is done, minute remnants are left and if inadequate thyroid function is thus provided the patients can be managed easily with thyroid extract. Hypothyroidism
With the exception of patients with thyroiditis, postoperative hypothyroidism occurs as a result of removal of too much gland. Hypothyroidism is rarely observed in patients who have subtotal thyroidectomy for diffuse nodular goiter, with or without hyperthyroidism. This alteration of thyroid function may be temporary or permanent. Postoperative hypertrophy of the remnants with increased function may occur any time up to a year after operation. The administration of thyroid extract is usually delayed for at least six months. One to 2 grains of thyroid extract daily will usually be sufficient to maintain adequate function with disappearance of symptoms and diminution of the elevated blood cholesterol to a normal level.
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As a result of more radical subtotal thyroidectomies for primary hyperthyroidism, there has been an increased incidence of postoperative hypothyroidism. This incidence will vary between 4 and 6 per cent. It is essential to follow all cases of radical subtotal thyroidectomy for several years in order that no instances of postoperative hypothyroidism go unrecognized. The condition can easily be recognized clinically by loss of hair, dry, rough skin, edema of the face and eyes, enlargement of the tongue, irritability, mental retardation and intolerance to cold. The diagnosis can be verified by the lowered basal metabolic rate and elevated fasting blood cholesterol level. Hypothyroidism occurs in the majority of patients submitted to operation for the various forms of thyroiditis. In the patients with chronic, nonspecific thyroiditis in whom excision of the isthmus or conservative subtotal thyroidectomy is done, less than one half require thyroid extract postoperatively. In the majority of patients with Hashimoto's struma and all of those with Riedel's struma hypothyroidism develops irrespective of the extent of the operative procedure. It must be appreciated that hypothyroidism develops in patients with long-standing chronic thyroiditis without operative interference. Hypoparathyroidism
Hypoparathyroidism is a preventable complication. It is usually due to removal of two or more of the parathyroid glands. The incidence of this complication does not seem to be related to ligation of all four superior and inferior thyroid arteries. In order to prevent this complication the parathyroids should be identified at the time of operation. It is usually easy to demonstrate the inferior one on each side and somewhat more difficult to demonstrate the superior glands which usually lie on the inside of the superior poles. Every effort should be made to identify at least two parathyroids in every subtotal thyroidectomy. With adequate exposure their demonstration is not technically difficult. Their recognition is based on their physical characteristics of size, shape, color, discreteness and arterial supply. Biopsy for verification should be unnecessary. Application of dry gauze to the surface of the parathyroid is followed by a change of color from golden brown to black because of subcapsular capillary bleeding. This is an important positive means of identification. In approximately 2 per cent of patients who have subtotal thyroidectomy symptoms or signs of parathyroid insufficiency develop. They do not develop until the third postoperative day and if present previous to this time they probably are not due to this cause. Paresthesias, tingling and muscle cramps are early symptoms, with carpopedal spasm and positive Chvostek's and Trousseau's signs being readily elicited. The diagnosis can be confirmed by demonstration of lowered blood calcium.
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Symptoms are rarely present unless the blood calcium is depressed below 8 mg. per 100 cc. Postoperative hypoparathyroidism is most common following secondary operations on the thyroid or following total thyroidectomy for malignant disease or any other indication. Less than half the patients have symptoms which persist longer than three months, and adequate function may be resumed as long as one year after operation. Symptoms may be relieved immediately by the intravenous administration of calcium and the patient can be maintained free of symptoms on large doses of vitamin D and calcium lactate by mouth, with the use of active parathyroid hormone rarely being necessary. Patients with permanent tetany must be carefully followed and satisfactory function maintained indefinitely. Unless adequate therapy is maintained, opacities of the lens will be observed, and at times mature cataracts will develop under such uncontrolled conditions. The seriousness of this complication of permanent parathyroid insufficiency is such that every precaution should be taken at operation to identify the parathyroid glands and avoid their removal. Malignant Exophthalmos
This complication fortunately is rare. It may occur preoperatively during the development of primary hyperthyroidism or exophthalmic goiter but may be observed at any time during the postoperative period. No definite relation to postoperative hypothyroidism can be established. It occurs in approximately 0.5 per cent of patients with exophthalmic goiter. Any patient with pronounced exophthalmos should be kept under careful observation and the degree of exophthalmos, as determined by the Hertel exophthalmometer, recorded. When a permanent degree of exophthalmos exists, associated with epiphora, conjunctivitis, chemosis, corneal ulcer or failing vision, operative relief is indicated. Partial suture of the lids may be necessary to protect the cornea. The modified Naffziger operation as described by Poppen * has now been carried out in this clinic on 79 patients with progressive malignant exophthalmos. The operation can be done safely, with preservation of function and a good cosmetic result. MORTALITY
Thyroid surgery can be done with a very low mortality. In the total experience with thyroid surgery at the Lahey Clinic, 30,907 operations have been done with an over-all mortality of 0.7 per cent. The highest mortality occurs following operations for thyroid carcinoma, particu-
* Poppen, J. L.: The surgical treatment of progressive exophthalmos. J. Clin. Endocrinol. 10: 1231-1236 (Oct.) 1950.
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larly in those cases with advanced lesions in which partial excision of the carcinoma and tracheotomy are done. There should be no mortality following the removal of the discrete adenoma or in nontoxic diffuse nodular goiter. In an unselected group of patients with diffuse nodular goiter with hyperthyroidism an occasional fatality will occur following subtotal thyroidectomy as a result of co-existing cardiovascular disease, since many of these patients are in the elderly age group. In a series of 2700 patients with hyperthyroidism prepared with antithyroid drugs followed by subtotal thyroidectomy, there have been 5 deaths, a mortality rate of 0.18 per cent. Two of these deaths were the result of cardiac complications and 3 followed respiratory obstruction and the resultant anoxia in thyrocardiac patients. SUMMARY
Complications may be encountered following any operative procedure on the thyroid. Fortunately, they are infrequent. They may be of minor significance or of the greatest importance. These complications may be divided into wound complications, those associated with respiratory obstruction and those manifested by altered thyroid function. The various complications encountered during the postoperative period, both immediate and remote, are discussed, their prevention is emphasized and their' treatment briefly presented. A positive anatomical approach, identifying all important structures, is urged to maintain postoperative complications at a minimum. The operative mortality can be maintained today even in an unselected group of patients below 0.5 per cent.