Intrathoracic Goiter

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Mediastinal extension is common in large, bulky, multinodular goiters. Negative intrathoracic pressure and gravity facilitate the descent of an enlarged thyroid gland. Intrathoracic goiter is rarely (<2%) a purely mediastinal tumor developing in an embryonic ectopic remnant or in a fragment of goiter left behind after an initial thyroidectomy.32'33 Because lateral and medial expansion may be limited after previous surgery, recurrent goiters often have more mediastinal prolongation. Between 3% and 20% of all intrathoracic goiters have undergone previous thyroid resections and are recurrent goiters.24,33"37

Definition and Prevalence

Review of the definitions of intrathoracic goiter shows no consensus on when a goiter should be considered intrathoracic. The most commonly accepted definition would include all goiters with a lower pole lying below the thoracic outlet.34 Other groups refer to substernal goiter only in cases in which at least 50% of the thyroid mass is located below the thoracic inlet.33'34 The Lahey Clinic group defined mediastinal goiters as "those with a major intrathoracic component that required reaching into the mediastinum for its dissection."36 This lack of agreement is reflected in the reported prevalences for intrathoracic goiter, which range from 4% to 20% of all operations for multinodular goiters. Intrathoracic goiters are also referred to as substernal goiters. Although the majority of intrathoracic goiters are anteriorly situated and thus are truly substernal, others may lie in the posterior mediastinum. Consequently, the term intrathoracic is preferred.

Clinical Presentation

Intrathoracic goiters usually occur late in life and have a peak incidence in the sixth decade. The average ratio between females and males is 3 to 4:1.38,39 In 20% to 30% of patients, the thyroid can be barely palpable or not palpable at all in the neck (grades I and II), and the thoracic extension represents most of the bulk of the goiter.35 36 Between 6% and 40% of patients reported in surgical series have no symptoms but have undergone thyroidectomy as prophylaxis against the potentially severe complications of a large intrathoracic thyroid mass. In these asymptomatic cases, substernal goiters are usually incidentally discovered on a plain chest radiograph.40 The most common clinical manifestations of substernal goiters are related to compression or displacement of the adjacent visceral, neural, and vascular structures (Table 33-3). Tracheal obstruction and resulting upper airway compression symptoms were observed in 20% to 56% of the patients operated on for intrathoracic goiter in some reports. Ranging from mild to severe, these symptoms are isolated dyspnea, dyspnea with cyanosis, dyspnea with cyanosis prohibiting physical efforts, suffocation, and choking requiring immediate resuscitation.41 Dyspnea or cough may be worsened by some positions, such as lying flat or rolling on one side.

The mechanism leading to airway obstruction is compression of the trachea by a goiter expanding between bone structures (spine, sternum, and first rib). Melliere and colleagues41 observed severe airway compression by goiters in 58 patients (2% of their thyroidectomy cases). Fifteen were thyroid malignancies and 43 were benign goiters, of which 16 had an intrathoracic substernal extension compressing the airway. Shaha and coworkers42 cared for 24 patients admitted during a 4-year period with acute life-threatening airway distress resulting from thyroid enlargement (in 9 patients, immediate intubation was required). Twenty of these patients had benign goiter, 15 of them with marked substernal extension. In patients requiring emergency care for acute airway obstruction, surgery should be performed as soon as possible, and patients should not be weaned from the ventilator before surgery because this may be followed by acute asphyxia.41 Occasionally, dyspnea resulting from upper airway obstruction can mimic lung disease. In these cases, it may be difficult to determine precisely which component is the main reason for the dyspnea. Lung function tests aided by flow-loop studies may be very helpful in determining the degree of airway obstruction.

Stephenson and associates43 determined peak expiratory flow to investigate the functional impact of substernal goiters. The preoperative peak expiratory flow ratio (observed to predicted) was significantly lower in patients with intrathoracic goiter, with a positive predictive value of 90%. This reduced peak expiratory flow improved after thyroidectomy. This test, along with failure of the peak airflow and forced expiratory volume to respond to bronchodilators, may be helpful in identifying the patients with respiratory disease and associated intrathoracic goiters who may benefit from thyroidectomy. The following is an illustrative example.

CASE 3

A 72-year-old woman, had been diagnosed with chronic pulmonary disease 10 years before referral, At the same time, a high-grade cervicothoracic calcified euthyroid goiter had been noted but not treated. She complained about progressive dyspnea and was sent for surgical assessment. There was an apparent swelling of the face and neck vein distention. Laryngoscopy was normal. Arterial blood carbon dioxide partial pressure was 48 mm Hg, and arterial blood oxygen partial pressure ranged from 60 to 75 mm Hg. The peak expiratory flow was reduced to 38% of normal, and the forced expiratory volume was reduced to 23% of normal, They were not improved by bronchodilators. On computed tomography (CT) scan, a calcified cervicothoracic goiter with marked reduction of the tracheal lumen and extension down to 2 cm above the carina was observed (Fig. 33-1), Total thyroidectomy (thyroid weight, 175 g) was carried out by cervical incision. The patient was immediately extubated after operation. She was discharged home on the third postoperative day.

Entrapment of the recurrent laryngeal nerve or laryngeal distortion may be the major cause of hoarseness found in about one third of patients who have undergone thyroidectomy for intrathoracic goiter. Cho and coauthors24 reported that vocal cord paralysis from benign thyroid conditions may be particularly prevalent among patients with large substernal goiters, and they attributed this to nerve compression, ischemia, or stretching. The true prevalence of preoperative vocal cord paralysis in substernal goiters,

TABLE 33-3. Presenting Symptoms and Incidence of Thyroid Autonomy in Patients Operated on for

Intrathoracic Goiter

Dyspnea

Dysphagia

Dysphonia

Caval

Hyperthyroidism

Study

N

(%)

(%)

(%)

Compression (%)

(%)

Alio and Thompson34

50

45

26

8

10

20

Michel and Bradpiece36

34

20

26

26

NTt

44

Sanders et al36

52

37

26

12

8

NR

Maruotti et al37

51

56

12

14

10

NR

Katlic et al33

80

28

33

16

3

0

Cho et al2í

70

41

33

7

5

NR

NR - not reported.

Peak Flow Year Old

FIGURE 33-1. A, Chest radiograph of a 72-year-old woman with dyspnea, reduced peak expiratory flow, and a massively calcified cervicothoracic goiter.

B, Computed tomography (CT) scan section at the level of the subcricoid trachea showing narrowing of the airway lumen.

C, CT scan section showing marked narrowing of the trachea at the thoracic outlet. D, Downward extension of the goiter to the aortic arch 2 cm above the carina.

FIGURE 33-1. A, Chest radiograph of a 72-year-old woman with dyspnea, reduced peak expiratory flow, and a massively calcified cervicothoracic goiter.

B, Computed tomography (CT) scan section at the level of the subcricoid trachea showing narrowing of the airway lumen.

C, CT scan section showing marked narrowing of the trachea at the thoracic outlet. D, Downward extension of the goiter to the aortic arch 2 cm above the carina.

however, is difficult to determine because laryngoscopy has been carried out very selectively in symptomatic patients. Furthermore, the rate of hoarseness is probably higher than that of well-documented vocal cord dysfunction. As discussed earlier, vocal cord paralysis can be reversed by thyroidectomy.^24.28.35,37 when operating on patients with intrathoracic goiter and dysphonia, the surgeon should identify the nerve and free it from surrounding fibrosis and adjacent compressive structures. Occasionally, however, nerve injury during a previous procedure or infiltration by an adjacent malignancy makes the recovery of vocal cord function impossible.

Lateral and posterior displacement of the esophagus causes dysphagia in about one fourth of patients being operated on for bulky intrathoracic goiters. However, these symptoms do not severely interfere with swallowing; aspirative complications and malnutrition have not been reported. Esophagograms show esophageal compressions and displacement by the thyroid mass but add little information to the management of these patients. Less frequently (10% of cases), obstruction of venous return gives rise to a fully or partially developed superior vena cava syndrome. This can be obvious with cyanosis, dilation of superficial facial and neck veins, and descending collateral venous circulation (Fig. 33-2). Subclinical venous compression can be diagnosed by having the patient raising the arms (Maranon's maneuver or Pemberton's sign) and observing distention of the external jugular and superficial neck veins. Collateral circulation may rarely involve the upper esophagus with "downhill" varices developing44'45 and causing an upper gastrointestinal hemorrhage. Superior vena cava syndrome is reversed by thyroidectomy and is considered to be an absolute indication for surgery.34

Gross multinodular goiters, whether in the neck or mediastinum, tend to develop autonomous nodules, particularly in patients with a prolonged history.15'25 Although in some reports no patients with hyperthyroidism were observed,2433-36 in others biochemical or clinical evidence of thyroid hyper-function was found in a significant (15% to 40%) proportion of patients.34 35 40 Hyperthyroidism is more common in elderly patients. In Cougard and colleagues' series of 218 intrathoracic goiters,40 hyperthyroidism developed in 35% of patients 70 years or older and in only 17% of those younger than 70 years. Hyperthyroidism in elderly patients can have potentially lethal cardiac complications such as congestive heart failure, arrhythmias, and worsening of

Intrathoracic Goiter

FIGURE 33-2. A and B, Superior vena cava syndrome in a patient with intrathoracic goiter. A pyramid-shaped bilateral intrathoracic goiter could not be retrieved through a collar incision, and thyroidectomy through a combined cervicomediastinal approach was carried out, with complete relief of caval compression.

FIGURE 33-2. A and B, Superior vena cava syndrome in a patient with intrathoracic goiter. A pyramid-shaped bilateral intrathoracic goiter could not be retrieved through a collar incision, and thyroidectomy through a combined cervicomediastinal approach was carried out, with complete relief of caval compression.

ischemic heart disease. Thyrotoxicosis may develop simultaneously as a result of hyperfunctioning "hot" nodules (Plummer's disease), after administration of iodinated contrast medium, or after T4 is given in an attempt to inhibit further growth of the goiter. Thus, it is important to identify patients with hyperthyroidism because they should receive definitive treatment, preferably surgical, as soon as possible. Radioactive iodine has been used to control hyperthyroidism in multinodular goiters, but it is often ineffective, repeated doses are required, and long periods of time elapse before obtaining the desired effects. Furthermore, radiation thyroiditis may occur soon after the administration of iodine 131 and may precipitate an emergency situation in the patient with airway obstruction.34

In several series, the prevalence of cancer in intrathoracic goiters ranged from 3% to 17% (Table 33-4), including both overt malignancies and occult papillary carcinomas. It is difficult to make an accurate preoperative diagnosis of carcinoma because the intrathoracic component cannot be reached by a fine needle. Furthermore, the exact location of the malignant nodule is difficult to ascertain. A relatively high proportion of thyroid lymphomas (6 of 102 substernal goiters) has been observed in the two series with the highest prevalence of malignancy.34-36 Advanced intrathoracic thyroid carcinoma

TABLE 33-4. Incidence of Carcinoma in Operated Multinodular Intrathoracic Goiters

Study

No. of Operations % with Cancer

Katlic et al33

80

3.0

Cougaid et al40

218

3.7

Maruotti et al37

51

5.8

Daou5í

60

7.0

Cho et al2í

70

10.0

Michel and Bradpiece35

34

12.0

Alio and Thompson34

50

16.0

Sanders et al36

52

17.0

may pose significant surgical problems if infiltrating surrounding structures; biopsy plus tracheostomy, palliative resection, and total thyroidectomy with or without laryngeal or segmental tracheal resection have all been performed in these circumstances.

Review of unusual clinical presentations of intrathoracic goiters reveals a fair number of severe, albeit rare, complications. The following cases were collected from the literature by Lawson and Biller38: hematemesis from downhill esophageal varices, abscess formation, Horner's syndrome, chylothorax from thoracic duct occlusion, and transient ischemic attacks resulting from a "thyroid steal syndrome." Fatal hematemesis has been described in a patient with full-thickness ulceration of the esophagus by a posterior substernal goiter.46 Axillosubclavian vein thrombosis was found in one patient with substernal goiter compressing the innominate vein.47 Injury to the membranous portion of the trachea at intubation for general anesthesia has occurred in at least two patients as a result of the trachea being angulated anteriorly by a posterior intrathoracic goiter48 (J. M. Rodriguez, personal communication); thyroidectomy and tracheal repair were performed through sternotomy in both cases.

Preoperative Imaging and Assessment

Various reports have emphasized the usefulness of chest radiographs and airway films in assessing the extent of tracheal displacement and obstruction caused by intrathoracic goiters.4142 Chest radiographs were abnormal in 60% to 90% of patients included in four studies.33'35"37 Lateral chest radiographs should also be taken to demonstrate any anterior displacement of the trachea, which may render orotracheal intubation dangerous (Fig. 33-3). Occasionally, lung metastasis from a thyroid carcinoma can be observed.35-42 Extrinsic pressure on mediastinal structures is best shown by CT scanning, which is the most sensitive imaging technique for diagnosing intrathoracic goiter extension.36-38^-42 It should be obtained in patients with a history suggesting

Intrathoracic Goiter
FIGURE 33-3. Lateral cervicothoracic radiographic projection showing marked anterior displacement of the trachea, widening of the tracheovertebral space, and airway compression against the sternal manubrium by a large (580 g) intrathoracic goiter.

compression symptoms and in those with nonpalpable lower thyroid borders, particularly if chest radiographs show an abnormal mediastinal outline or marked tracheal deviation. CT scanning gives important information to the surgeon regarding (1) the precise location of the intrathoracic extension; (2) the presence, extent, and situation of the continuity between the cervical and the thoracic components of the goiter; (3) definition of the limits of the lesion; (4) areas of calcification; (5) degree of heterogeneity and cystification of the intrathoracic portion; and (6) level and degree of tracheal lumen reduction.

Nuclear magnetic resonance imaging may be superior35 because, in addition to the information provided by CT scanning, it has two advantages: it offers sagittal and coronal tomographic cuts, which further clarify the anatomy of the intrathoracic goiter, and it delineates more precisely the relations among the goiter, the whole length of the trachea, and the mediastinal vessels. Vascular invasion by a thyroid malignancy may also be detected.

Thyroid scintigraphy has limited value in the preoperative assessment of intrathoracic goiters. Iodine 131 scintigraphy often fails to show the mediastinal prolongation24,36'38'40 and adds little to the management of intrathoracic goiter. In patients with subclinical or overt hyperthyroidism, it may show hot hyperfunctioning nodules. The most useful indication for 131I scintigraphy is to clarify the nature of an isolated mediastinal mass, and it should be ordered for patients in whom CT scanning does not show mass continuity between the mediastinum and the neck. The following is an example.

CASE 4

A 62-year-old woman, was to undergo elective cholecystectomy. Her history revealed subtotal thyroidectomy at the age of 40 years for multinodular goiter. The chest x-ray film showed a mediastinal mass with no cervical continuity that was positive on iodine scanning. It was resected by median sternotomy (Fig. 33-4).

Iodine 131 scintigraphy should always precede CT scanning because intravenous iodine administered for vascular enhancement blocks iodine uptake by the goiter. Technetium 99m scintigraphy does not depend on iodine uptake by

Neck Exercises For Goiter

FIGURE 33-4. Chest radiograph (A) and iodine 131 scintigram (B) in a case of recurrent intrathoracic goiter independent of the neck approached through a median sternotomy. Subtotal thyroidectomy was performed 22 years before. The mass was situated behind the ascending aorta.

FIGURE 33-4. Chest radiograph (A) and iodine 131 scintigram (B) in a case of recurrent intrathoracic goiter independent of the neck approached through a median sternotomy. Subtotal thyroidectomy was performed 22 years before. The mass was situated behind the ascending aorta.

the goiter, but because of the proximity of the goiter to the thoracic cardiovascular blood pool, the findings may be difficult to interpret. Its sensitivity has been reported to be only 33%.49

Laryngoscopy should be carried out in patients presenting with hoarseness or dysphonia and in those who have had prior neck surgery. Vocal cord paralysis may result from (1) previous surgery, (2) compartmental syndrome, or (3) invasion of the recurrent laryngeal nerve by a thyroid malignancy. These different possibilities should be borne in mind during operation.

Thyroid function tests must be performed before surgery because hyper- or hypothyroidism may be associated with large intrathoracic goiters. Hyperthyroid patients should be treated with antithyroid drugs before surgery. Some authors40 add steroids to the antithyroid drugs to prevent worsening of compartmental syndromes resulting from goiter inflammation. This practice, however, is not widespread, and most surgeons would prefer to operate on patients not receiving steroids. Failure to measure a recent thyroid hormone concentration may precipitate perioperative metabolic problems. One of our patients experienced postoperative acute myxedema despite a near-normal hormone concentration 1 month before surgery.

CASE 5

An 89-year-old woman with a history of congestive heart failure, was referred because of progressive dyspnea resulting from a hyperfunctioning multinodular cervi-cothoracic goiter present for 25 years. Surgical treatment had been ruled out at two other hospitals because of her poor cardiac condition, and she was treated with methimazole (10 mg/day). T4 was 4.7 (ig/dL (normal, 4.5 to 12.4 (ig/dL), and TSH was 5.8 mU/mL (normal, 0.5 to 5 mU/mL) 1 month before surgery. The patient underwent total thyroidectomy; a 580-g goiter with bilateral mediastinal extension was delivered through a collar incision. On the 10th postoperative day she started to hypoventilate (partial pressure of carbon dioxide, 78 mm Hg) and became lethargic. A blood sample was drawn for thyroid hormone determination, and intravenous treatment with L-thyroxine and hydrocortisone was started. The patient recovered in a few hours. T4 was undetectable and TSH was 20 mU/mL.

Surgical Treatment

Thyroidectomy is the preferred treatment for intrathoracic goiter (Table 33-5). T4 treatment has repeatedly proved ineffective in reducing goiter volume38 and may result in hyperthyroidism. A clinical trial using suppressive doses of L-thyroxine (2.5 pg/kg per day) to reduce the size of sporadic nontoxic goiters has shown that after 9 months of continued treatment 58% of the patients responded (as determined by ultrasonography). The mean reduction of goiter size was 25%. This benefit, however, was short lasting; 9 months after

TABLE 33-5. Reasons for Surgical Treatment of Intrathoracic Goiter

No effective medical treatment Progressive chronic compartmental syndromes Airway obstruction Hoarseness Vocal cord paralysis Vena cava obstruction Hyperthyroidism (heart disease) Risk of undiagnosed malignancy Low operative morbidity {>90% removed via collar incision)

Unexpected acute complications (asphyxia, thyrotoxicosis) Severe unusual complications (tracheal injury at intubation, erosion of mediastinal structures, infection, Horner's syndrome, chylothorax)

Modified with permission from Alio MD, Thompson NW. Rationale lor the operative management of substernal goiters. Surgery 1983;94;969.

the treatment was discontinued, the goiter volume regained its basal value.50 Evidence supports a growing consensus against the use of L-thyroxine treatment for goiter size reduction or goiter growth prevention.51

CERVICAL APPROACH

More than 90% of intrathoracic goiters can be removed through a standard collar incision. Several maneuvers facilitate approaching, dissecting, and delivering huge goiters into the cervical wound. These are summarized in the following description of a "standard" bilateral resection for multinodular intrathoracic goiter.

The best position of the patient on the operating table is the semisitting Kocher position with hyperextension of the neck. This reduces venous pressure in the upper trunk and helps to minimize blood loss. To reduce further the pressure in the neck, it may be helpful to divide the sternal head of the sternocleidomastoid muscle and the strap muscles. This maneuver also gives a wide exposure for approaching the upper pole and the laterodorsal aspects of the goiter. Before any attempt is made to mobilize the intrathoracic extension, the upper thyroid vessels and lateral middle veins should be divided on both sides. The surgeon then decides which is the smaller of the two lobes and rotates it medially to identify and encircle its inferior thyroid artery. The posterolateral surface of the lower pole should be carefully inspected to detect any subcapsular parathyroid gland that may require autotransplantation in the sternocleidomastoid muscle. During mobilization of bulky thyroid lobes, we have found it useful to apply a small bulldog vascular clamp to the trunk of the inferior thyroid artery. Peri thyroid and hilar dissection can then be carried out with a minimal blood supply to the thyroid; the clamp is released after lobectomy is finished. Pressure in the neck is greatly relieved at this stage, and resection of the mobilized lobe can be accomplished. Tracheal attachments of the dorsum of the thyroid are severed as completely as possible without endangering the contralateral recurrent laryngeal nerve. Having freed as many cervical attachments as possible, the surgeon now approaches the lobe with a major intrathoracic component. Access to the hilum may be difficult before the intrathoracic extension has been brought up. If this is the case, no heroic efforts should be made to identify the recurrent nerve at this stage; attention is focused instead on delivering the thoracic goiter extension into the neck. This is done by gently pulling up the thyroid lobe while the surgeon frees loose adhesions surrounding the mediastinal portion of the goiter with the index finger and applies caudal to cephalad pressure onto it.

If this proves difficult, two additional maneuvers may be helpful: (1) the finger of the surgeon can be replaced by a sterile "soup spoon," which breaks negative intrathoracic pressure, reaches lower, and occupies less space than the surgeon's finger34,52; and (2) intracapsular fragmentation of the thyroid (morcellation) was proposed by Lahey to reduce the size and soften the intrathoracic goiter extension and facilitate its removal through the neck. This technique has two drawbacks: major bleeding and tumor spillage. When the goiter is obviously cystic and no fear of malignancy exists, Alio and Thompson34 occasionally used a variation of this technique by introducing a metal suction device through small capsular incisions. Katlic and colleagues33 also used morcellation, aspiration, or both, in 5 of their 80 operations for intrathoracic goiter, with good results. After the intrathoracic portion has been delivered into the neck, the operation proceeds in a standard manner, identifying the recurrent laryngeal nerve and the upper parathyroid gland. Use of closed suction drains is advisable to evacuate blood from the large remaining mediastinal cavity.

If the intrathoracic part is very difficult to mobilize before the recurrent nerve is identified and the tracheal attachments of the thyroid lobe are severed, the surgeon may identify the nerve close to the inferior horn of the thyroid cartilage where it enters the larynx and dissect it downward. This is followed by section of the tracheal attachments. By so doing, the cervical part is completely free and more efficient upward traction, without fear of injuring the nerve, can be exerted on the thoracic part of the goiter. Identification of the recurrent nerve at the level of the cricoid cartilage, however, is technically demanding and should not be attempted by the less experienced surgeon.

STERNOTOMY AND COMBINED MEDIASTINAL APPROACH

The anterior chest wall should be prepared and draped in all patients undergoing thyroidectomy for large intrathoracic goiters should sternotomy be required. Sternotomy can be carried out as a last resort or maneuver, or, better, it should be planned electively for patients in whom preoperative imaging demonstrates very bulky, low-lying, solid goiters with complex anatomic relations.

Between 2% and 11% of intrathoracic goiters have required removal through a combined cervical and sternotomy approach.3242,49,53 Indications for this combined approach include a large discrepancy between the diameter of the thoracic inlet and that of the goiter (pyramidal or pear-shaped intrathoracic extensions; see Fig. 33-5), superior vena cava syndrome, retroesophageal extension, deep-seated tumors reaching the carina, invasive carcinoma, and acute respiratory distress. The specific reasons for performing sternotomy given in a number of studies are summarized in Table 33-6. The main advantage of sternotomy is widening of the thoracic inlet. Widening facilitates deeper blunt dissection and exteriorization of large thyroid masses that otherwise would require fragmentation. It may also help to control bleeding in the occasional case in which mediastinal vessels to the goiter are identified. If a carcinoma is present, invading the lower trachea, sternotomy may be required to achieve a radical resection.34,35

If sternotomy is used, the cervical part of the operation is done first to control the major thyroid vessels. Leaving sternotomy to the end of the operation also has the advantage of shortening the wound exposure time, thus reducing the risk of infection. In cases of superior vena cava syndrome, however, early sternotomy may be required to decompress the large neck veins effectively. Partial or full median sternotomy is carried out. Partial sternotomy has the advantage of being more cosmetic. It can be done by raising the lower skin flap over the sternal manubrium, thus sparing a prester-nal skin wound.

TABLE 33-6. Reasons for Performing Sternotomy in Operations for Intrathoracic Goiter

Study

Reason

Katlic et al33

Shaha et al42 Alio and Thompson34

Michel and Bradpiece35

Sanders et al36

Meniere et al41 Cougard et al40

Large diameter (12 cm), weight of 237 g (1); large diameter (10 cm), previous surgery (thoracotomy) (1) Recurrent goiter, extension to the carina

Superior cava syndrome, low-lying goiter (fifth intercostal space), adhesions to the pleura Retrotracheal extension (3); invasive papillary carcinoma involving the trachea and larynx (1) Hurthle cell carcinoma invading the lower trachea (1); left lobe mass passing into the right posterior mediastinum behind the trachea and esophagus (cervicotomy plus right thoracotomy) (1) Necessary to deliver the goiter into the cervical incision (two goiters, two carcinomas) Invasive carcinoma (3); purely thoracic goiters without cervical continuity (2); nonmobile massive goiters (4); absence of dissection plane (four recurrent goiters) (5); intraoperative hemorrhage (one recurrent goiter) (2)

'Patients with airway compression.

The following case history represents a good example of a patient with recurrent giant intrathoracic solid goiter who underwent total thyroidectomy through a combined cervico-mediastinal approach.

Widening the thoracic outlet by sternum splitting may decrease the risk of recurrent laryngeal nerve injury in difficult cases. In a study by Cougard and colleagues,40 no permanent nerve palsy was observed in 16 patients who had sternotomy, whereas a 6.8% palsy rate was noted in patients operated on through only a cervical incision.

THORACOTOMY

A half-century ago, there was uncertainty as to the best route for resecting large intrathoracic goiters when access to the chest was required.54 Thoracotomy (usually right) was proposed mainly by thoracic surgeons such as Clagett, Sweet, and Ellis in the belief that most intrathoracic goiters represented isolated thoracic masses and that posterior goiters could not be safely removed through a neck incision. Since then, experience has shown that approaching the intrathoracic goiter through posterolateral thoracotomy should be discouraged. There are several reasons for this. Posterior thoracic goiters are no longer per se an indication for thoracotomy because they can usually be delivered through collar incision or median sternotomy. Major thyroid vessels cannot be appropriately controlled from the thorax, and the cervical extension of the goiter cannot be dissected free from the adjacent structures. It is because of these

CASE 6

A 45-year-old woman, was referred for surgical treatment of recurrent multinodular goiter. At 18 years of age, she had a "thyroid operation." Ten years later, a mediastinal mass was noted in a routine chest radiograph. No treatment was indicated. Seventeen years later, the patient was referred for definitive surgical treatment after admission to another hospital for an unrelated cause. When first seen, she had a large cervi-cothoracic mass causing dyspnea on exertion. CT and nuclear magnetic resonance scans (Fig. 33-5) showed a large intrathoracic homogeneous goiter extending down to the right main bronchus. Sternotomy was required for safe total thyroidectomy (thyroid weight, 378 g). From findings at cervical exploration, she probably had had an enucleation of an isthmic nodule.

Intrathoracic Goiter

FIGURE 33-5. Recurrent goiter with a large intrathoracic extension of the right lobe. A, Chest radiograph film shows lateral displacement of the trachea by a large mediastinal mass. B, Computed tomography scan shows downward prolongation of the goiter past the aortic arch. C, Sagittal section in a nuclear magnetic resonance scan shows the relationship of the intrathoracic goiter with the venous innominate trunk, the spine, and the right main bronchus. D, Coronal section shows tracheal compression, pleural thickening around the goiter, and relationship with the carina. Median sternotomy was performed to allow blunt finger dissection of the lower pole of the right lobe lying behind the vena cava on the right main bronchus.

technical difficulties that thoracotomy is associated with substantial risk of recurrent laryngeal nerve injury.37'55 56 If a thoracotomy is carried out because an incorrect diagnosis of purely posterior mediastinal "tumor" has been made, it often requires conversion to a neck incision.37 Shahian and Rossi57 made the case for exceptional circumstances that may require thoracotomy: at the Lahey Clinic, two patients had a cervical and thoracotomy approach in a 20-year period. Both presented with a right posterosuperior mediastinal goiter extending from a left thyroid lobe passing behind the trachea and the esophagus. In our experience, however, these "corkscrew goiters" can also be approached by a full median sternotomy and opening of the right pleural cavity. Gentle pressure on the posterior thyroid mass helps to untwist the goiter around the tracheoesophageal axis.

SUMMARY

It is usually difficult to foresee which patients will require a thoracic approach when operating on an intrathoracic goiter. It is therefore advisable to prepare the surgical field for sternotomy in cases of huge thoracic thyroid masses, especially if they are posterior, suspicious of being malignant, or recurrent.58 Further studies based on preoperative imaging techniques, anatomic landmarks, and volumetric studies may serve to delineate further the subset of patients who require a thoracic approach.

Postoperative Complications

The morbidity rate after surgery for intrathoracic goiters ranges between 4% and 12% in various series from referral institutions. The most common significant complications are listed in Table 33-7. Patients with the highest complication rates are those with thyroid malignancies and those undergoing a combined cervicomediastinal approach. Despite the extensive perithyroidal dissection required to resect these large goiters, permanent hypoparathyroidism is unusual in the hands of experienced surgeons. To achieve these results, knowledge of the altered anatomy is essential, as is proper identification and eventually autotransplantation of any parathyroid gland in the surface of the thyroid whose blood supply cannot be guaranteed.

Recurrent laryngeal nerve paralysis results from not identifying the nerve and inadvertent injury or from stretching during blunt dissection of large intrathoracic masses. As previously stated, efforts to identify the nerve before the intrathoracic goiter is fully mobilized may result in inadvertent injury. If the nerve is not transected, vocal cord paralysis is usually (75%) temporary.

Tracheal softening leading to tracheal collapse and respiratory failure (tracheomalacia) is being reported exceptionally, even in series of patients operated on for airway compression. In several major studies32"36'4142 encompassing 298 patients (including two series of patients operated on for respiratory distress), only 2 patients were diagnosed with tracheomalacia and required postoperative tracheostomy.36 42 Of the seven patients with tracheomalacia reported by Geelhoed,59 three had recurrent goiters and one had a longstanding multinodular goiter. Methods for management of tracheomalacia are extensively reviewed in this study. External splinting by custom-made rings or Marlex mesh has also been tried.59 Tracheostomy, however, remains the standard treatment whenever tracheal softening is identified at surgery.

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