The options for surgical approach to a substernal goiter include collar incision, median (partial) sternotomy, thoracotomy, or a combined approach utilizing minimally invasive access (VATS or robot) to mobilize the intrathoracic portion of the gland (Fig. 157-2). Past reviews confirm that most substernal goiters (>90%) can be removed via a collar incision exclusively.5–8 Exceptions that may best be approached by median sternotomy (partial), thoracotomy (posterolateral or anterior), or minimally invasive techniques (robot) include a primary retrosternal goiter, atypical anatomy, dense adhesions from prior neck or thyroid surgery, inability to deliver the gland into the neck, overt or extracapsular extension of malignancy in the mediastinum, recurrence after previous resection of an intrathoracic goiter, goiters that extend to the tracheal carina or pose significant life-threatening compression of mediastinal structures, and patients who develop significant mediastinal bleeding intraoperatively (Table 157-2).6 Thoracoscopic approaches (VATS or robotic) to an ectopic thyroid mass may be considered if deemed accessible and safe by the operating surgeon, and the details of VATS approach have been reported previously.1 We have approached an ectopic thyroid using a robotic approach via the right chest and three arms (Fig. 157-3).
Resection of substernal goiter may require a partial sternal incision.
A. The three ports via the right chest are shown for robotic access for ectopic or substernal components of a thyroid goiter. B. Also shown is the angle in which the robot crosses the patient for optimal maneuverability.
Table 157-2Situations for Consideration of An Intrathoracic Approach ||Download (.pdf) Table 157-2Situations for Consideration of An Intrathoracic Approach
|Primary retrosternal/ectopic goiter |
Dense adhesions from prior surgery
Inability to deliver the gland into the neck
Extracapsular extension or known mediastinal malignancy
Recurrent intrathoracic goiter
Prior thyroid surgery, especially for cancer
Goiters that extend to the tracheal carina
Goiters that cause life-threatening compression of mediastinal structures
Significant intraoperative mediastinal bleeding
Adherence to mediastinal pleura
A total or near-total thyroidectomy is performed. Prophylactic antibiotics are administered intravenously. The surgeon should be present in the OR on induction of anesthesia in the event of complete airway obstruction. Patients with significant airway compression or deviation should undergo awake, fiberoptic intubation with variable sedation. Tracheostomy is rarely needed.9
The patient is positioned supinely with the arms tucked at the sides. A transverse shoulder roll is positioned behind the upper chest to extend the neck. The anterior neck, chest, and upper abdomen are prepped in their entirety. Access for complete median sternotomy, if necessary, is achieved. The reverse Trendelenburg position is used to diminish venous congestion.
A collar (Kocher) incision approximately 2 cm above the sternal notch is used for initial exploration of thyroid goiter. The platysma is divided using electrocautery, and skin/soft tissue flaps deep to the durable platysma are developed superiorly and inferiorly to the level of the hyoid and sternal notch, respectively. Exposure extends to the sternocleidomastoid muscles bilaterally. The strap muscles are exposed for their length and divided in their midline to expose the thyroid capsule. Frequently, the initial position of the neck in extension elevates the substernal goiter from an intrathoracic position to a predominantly extrathoracic position, facilitating complete extirpation of the thyroid gland through the collar incision.
Once access to the thyroid has been completed and exposure optimized, mobilization of the gland is facilitated by elevating the intrathoracic portion of the thyroid and by using blunt finger dissection circumferentially around the gland immediately on the capsule of the thyroid inferior to the middle thyroid vessels. Blunt dissection on the posterior aspect of the manubrium is performed (Fig. 157-4). Some advocate the use of several large sutures (1 or 0 PROLENE noncutting sutures in a figure-of-eight pattern) for traction as the mediastinal portion of the gland is mobilized, whereas others describe the use of a sterile spoon to aid in goiter delivery into the neck (Fig. 157-5). If additional exposure is needed, the strap muscles or medial portions of the sternocleidomastoid muscles can be divided transversely.
Goiters usually can be removed via cervical incision with the use of careful blunt finger dissection to mobilize the gland from its attachment to mediastinal structures. Most large goiters can be removed through a 2-cm collar incision.
Traction stitches (as shown) can be most helpful in delivering a substernal extension of thyroid tissue into the neck incision.
Ligation of the superior and middle thyroid vessels is next accomplished as close to the thyroid capsule as possible. This procedure should be begin on the smaller or most straightforward side of the goiter. Once the superior and middle vessels are ligated, the lateral thyroid is bluntly and sharply medialized by the development of areolar planes along the sides of the goiter. Care should be taken to identify and preserve, if possible, the superior parathyroid glands because the inferior glands may be more difficult to identify. The RLN is identified and preserved. Only careful retraction is used during this portion of the procedure to avoid injury.
The inferior thyroid vessels are ligated close to the thyroid capsule, and the inferior parathyroid glands are identified, if possible. It is not uncommon for parathyroid glands to be removed inadvertently or devascularized during the mobilization of large substernal goiters, especially the bilateral inferior glands. If parathyroid glands are identified and appear to have been injured, incidentally removed, or devascularized, autotransplantation of the minced gland into the sternocleidomastoid mass should be performed. A small frozen section of the presumed parathyroid tissue is obtained before autotransplantation to ensure that parathyroid gland and not lymph node or cancer is being autotransplanted. Once the goiter has been mobilized to the midline, sharp dissection is used to release its attachment to the trachea to avoid inadvertent tracheotomy or airway fire (Fig. 157-6).
Sharp dissection is safest when dissecting the gland off the trachea to avoid inadvertent tracheal injury and airway fire.
There will be times when an intrathoracic extension of a thyroid goiter cannot be delivered safely into the neck via a collar incision. This may not be obvious during preoperative planning or before an attempt at resection is made. An additional approach, including partial (manubrial split) or full sternotomy, thoracotomy, or thoracoscopy (VATS or robot) may be necessary. Incision choice is a clinical decision dictated by the anatomy of the remaining mediastinal component and the comfort level and skill set of the surgeon and should be evident from preoperative scanning coupled with the intraoperative findings and limitations. Primary ectopic thyroid goiters recurring after previous thyroid surgery tend to parasitize mediastinal blood vessels, making cervical resection more hazardous. If a thoracoscopic approach is undertaken, resection is accomplished with isolation and ligation of the arterial supply, safe dissection, and identification of the phrenic and/or vagus nerves. The tumor should be removed en bloc and should only be cautiously grasped directly with instruments to ensure complete resection. Thoracoscopic approaches can typically be performed through three ports, with the patients right side bumped and the arm apposed (see Fig. 157-3). A double lumen endotracheal tube is needed and CO2 insufflation may be utilized. The gland should be positioned directly in a line between the camera and the boom of the docking robot if that approach is undertaken. An intraoperative photograph of an ectopic thyroid removed robotically y is shown in Figure 157-7.
An intraoperative photograph of a robotic removal of an ectopic thyroid via the right chest.
Soft suction drains may be placed at the discretion of the surgeon at the conclusion of the procedure.
Mortality is less than 1% with appropriate preoperative planning, management of the airway, and good surgical technique. Length of stay for an uncomplicated procedure is overnight, and patients can be discharged uneventfully with calcium or calcitriol supplementation as dictated by laboratory values and/or clinical symptoms of hypocalcemia. If a thoracotomy or sternotomy is required, length of stay is increased, although morbidity is not affected.
Occasionally, postoperative hemorrhage has been reported, necessitating a return to the OR for control and hematoma evacuation. The major complications after thyroidectomy for substernal goiter involve injury to the trachea, parathyroid glands, or RLNs. The length of stay for patients with marked intrathoracic extension is increased, as is the need for prolonged intubation. Historically, tracheomalacia was reported as a significant problem in patients with long-standing tracheal compression, although, in more modern series, this appears to be a rare phenomenon (0.001–1.5%). When present, tracheomalacia may result in an extended period of postoperative intubation. One study reported that 10% of patients required extended intubation for airway issues postoperatively, with all patients eventually being extubated by postoperative day 10. However, these patients required multiple attempts at intubation preoperatively, making their need for prolonged postoperative intubation harder to simply attribute to tracheomalacia, as some authors have done. Postoperative airway complications are more likely to occur in older patients with large goiters (>200 g) who demonstrate significant tracheal compression on preoperative imaging. The presence or absence of clinically significant tracheomalacia is best assessed at the time of resection by finger palpation and evaluation of the tracheal walls. The need for tracheostomy at the time of thyroidectomy is rare, and it should be performed only in cases of tracheal infiltration by an undifferentiated cancer or when it can be expected that there is bilateral vocal cord paresis postoperatively. This typically occurs when a patient has a known preoperative unilateral vocal cord palsy from prior thyroid surgery and intraoperative dissection has placed the remaining RLNs at risk.
Transient and permanent hypoparathyroidism has been noted to occur postoperatively in fewer than 10% and 2% of cases, respectively. This is the most frequent complication after total thyroidectomy and is more likely to occur when the goiter is extensive, displacing normal anatomic landmarks and requiring marked dissection for gland resection. There is a higher risk for hypoparathyroidism after resection of intrathoracic goiter compared with removal of a cervical goiter alone because the lower parathyroid glands tend to be at increased risk. These glands are situated along the thyrothymic ligament and can be devascularized more readily or even not identified at all. This complication can be minimized by careful and meticulous dissection on the thyroid capsule and performing autotransplantation when the viability of the parathyroid gland appears marginal. The postoperative use of oral and IV calcium as needed, as well as calcitriol, can avoid prolonged hospitalization for this complication. Difficult cases of hypoparathyroidism should be managed with the help of an endocrinologist, who will taper these medications appropriately. In most cases, transient hypoparathyroidism from parathyroid stunning will resolve by 6 months postoperatively.
Transient unilateral vocal cord paralysis has been reported to occur after substernal goiter resection in up to 4% of patients and, if suspected postoperatively, warrants consultation with otolaryngology. Permanent RLN paralysis should occur in fewer than 2% of patients with careful surgical technique and dissection. This is more likely to occur in patients with large or extensive intrathoracic goiters or those with extracapsular extension of malignancy.