A critical analysis of 33 patients with substernal goiter surgically treated by neck incision

摘要

Haller was the first to describe substernal goiter in 1749 as the extension of thyroid tissue below the upper opening of the chest1,2. Today, substernal goiter is characterized when more than 50% of the gland is extended into the chest, thus requiring dissection of the upper mediastinum.2 Variations on the definition include thyroid extensions greater than 3cm below the furculum or extensions below the fourth thoracic vertebra, however with no impact on disease classification or prevalence rates. A preoperative method to determine the need to perform sternotomy in substernal goiter patients is not established. Therefore, cases in which higher morbidity procedures may be required are seen with doubt and insecurity by both physicians and patients. One should mention that some patients suffering from substernal goiter have no symptoms and the mere hint of a sternotomy makes the procedure even less accepted. Besides, although thyroidectomy is an established procedure with low complication rates, the same cannot be said of substernal goiter3-15. The treatment for substernal goiter is eminently surgical. This paper aims to confirm the standard surgical technique and analyze its complications, comparing it against data found in the literature.   MATERIALS AND METHOD Between May of 2002 and July of 2007, 316 patients underwent surgical treatment for goiter at our institution. Thyroidectomy for substernal goiter was performed in 33 (10%) of them. Patient mean age was 51 years (ages ranged between 32 and 83 years). Twenty-five were women and 7 were men, a ratio of 3.5:1. Reported clinical findings were as follows: 10 (30%) patients had dyspnea, 7 (21%) had dysphagia, 7 (21%) had dyspnea and dysphagia, and only 2 (6%) had hyperthyroidism. Seven (21%) did not report clinical complaints. Neck and chest CT scans were ordered for all patients suspected for substernal goiter to confirm the diagnosis and plan for surgery. Thyroid extension into the mediastinum and tracheal deviation were seen in all suspected cases. Clinical suspicion is established during physical examination when the lower border of the gland cannot be palpated or found in preliminary images. Additional findings include tracheal deviation and mediastinal mass in chest X-ray images. Figures 1 and 2 show respectively X-ray finding in patient suspected for substernal goiter and confirmation through CT scan. Tracheal deviation and/or large size goiter are indicative of the need for surgery.         All patients with preoperative clinical and imaging findings compatible with substernal goiter were included. Patients not meeting the criteria, others diagnosed with substernal goiter intraoperatively, and poor thyroidectomy candidates were excluded. The planned procedure was a neck approach followed by a thyroidectomy. The same surgical procedure was performed in all patients. This paper was approved by the Research Ethics Committee of our university under permit 0725/05. Surgical Technique Surgery starts with a broad transverse neck incision to provide good visualization of the structures (Figure 3). Then the platysma muscle is sectioned and cranial and caudal subplatysmal flaps are dissected. The median raphe is opened until the plan of the thyroid.     It is important that the procedure is initiated on the side where substernal goiter is larger. Then the sternocleidomastoid muscle (Figure 4) and the prethyroid muscles (Figure 5) are released, the latter being sectioned in its upper third and retracted laterally, thus enhancing lateral exposure.         The upper pole is then ligated through the usual technique and loose tissues adhered to the gland are bluntly dissected, with special attention given to the ones in the upper mediastinum. The diving lobe is then pulled and dislocated (Figure 6). The laryngeal nerve and the parathyroid glands are then identified and spared. The lower pole is ligated and the tracheal gland released.     After the lower substernal lobe is resected the surgical site is usually broad enough not to require the release of the muscles in the contralateral side during the resection of the contralateral lobe. The procedure is concluded with the usual hemostasis technique, draining using a closed drain tube system, and suture by layers.   RESULTS Thirty of the 33 patients underwent total thyroidectomy; all had bilateral multi-nodular goiter; only three were treated with hemithyroidectomy as they had unilateral benign disease. Postoperative pathology tests revealed that 2 (6%) patients had well-differentiated malignant disease, both cases of follicular variant of papillary carcinoma with sizes ranging between 1 and 2 centimeters. These patients had been previously undergone total thyroidectomy. As mentioned above, all patients were submitted to the described surgical technique and none required sternotomy or thoracotomy. After surgery, the patients stayed at the hospital