Approach Considerations
Most substernal goiters can be excised via a cervical approach; however, in cases of very inferior extent or increased vasculature or in cases of recurrent goiters or thyroid cancer, a midline sternotomy may be necessary for exposure, safety, and completion of the excision. [5, 14, 6, 67]
Transcervical Excision of Substernal Goiter
After obtaining informed consent, the patient is brought to the operating room and placed on the bed in the supine position. The patient undergoes endotracheal intubation with laryngeal nerve monitoring electrodes, if desired by the surgeon. General anesthesia is administered. The head of the bed is rotated 180° from the anesthesiologist.
A headrest and shoulder roll with neck extension can be used to help raise the thyroid gland in some cases.
A horizontal incision is planned with an ink marker across the lower anterior neck in a relaxed skin tension line, if possible, and to a length that is appropriate for safe dissection and removal of the size of the goiter. If a partial midline sternotomy becomes necessary, plan for a midline vertical limb from the horizontal incision to the halfway point along the sternum toward the xiphoid process.
A local anesthetic and vasoconstrictive solution (such as 1% lidocaine with 1:100,000 epinephrine) is injected into the planned incision area.
The patient is prepared with sterile soap (eg, chlorhexidine) and draped in a sterile fashion.
An incision is made with a sharp blade through the skin, dermis, subcutaneous tissue, and platysma (where present). A superior subplatysmal flap is made to the level of the thyroid notch. An inferior subplatysmal flap is made to the level of the clavicles and manubrium. The skin/platysmal flaps are secured open to the drapes with either elastic hooks or suture with clamps. Attention to the location of the anterior jugular veins at this point is important since their course is deep to the platysma and superficial to the strap musculature (sternohyoid and sternothyroid).
When the thyroid gland is enlarged in a horizontal fashion, defining and dissecting out the course of the anterior border of the sternocleidomastoid on both sides may be helpful in liberating some of the lateral aspect of the goiter and generating more anatomic landmarks. This may be unnecessary depending on the size and shape of the thyroid gland.
The midline of the strap muscles (sternohyoid and sternothyroid) is then dissected and defined. On each side, individual strap muscles (or both together) are dissected free lateral to the thyroid gland. Retractors are used to pull the strap muscles away from the thyroid gland to enable continued capsular dissection. If necessary for increased exposure, the strap muscles may be incised horizontally midway down the latitude of the thyroid gland. After the thyroid has been excised, they should be reapproximated with absorbable suture.
Capsular dissection of the thyroid is important when freeing any part of the thyroid from the contents of the central lymph node compartment to reduce the risk of damaging the surrounding structures, which include the following:
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Recurrent laryngeal nerves
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External branch of the superior laryngeal nerves
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Vagus nerves
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Parathyroid glands
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Cricothyroid muscle
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Larynx
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Trachea
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Major blood vessels (superior, middle, inferior thyroid veins; superior and inferior thyroid arteries; brachiocephalic artery and vein; subclavian artery and veins; carotid arteries; internal jugular veins)
Surgeons and surgical authors vary in the sequence they follow for excising the thyroid gland and in the need for identifying the recurrent laryngeal nerves and parathyroid glands.
Regardless of sequence, careful dissection, ligation, and division of the superior, lateral, and inferior pole vessels releases the gland from the central compartments bilaterally. Preservation of inferior thyroid vessels increases the likelihood of maintaining parathyroid function. Once the gland has been retracted anteromedially beyond the region of the recurrent laryngeal nerve and on to the trachea, disconnection of the thyroid gland from the trachea by dividing Berry ligament completes the excision (see image below). A lateral-to-deep dissection course is likely much safer than a medial deep dissection with regard to the recurrently laryngeal nerves.
The superior pole vessels (superior thyroid artery/vein) and middle thyroid veins can be ligated prior to substernal/mediastinal dissection in an effort to liberate the gland and increase the mobility of the inferior aspect of the gland. The safety of inferior thyroid border dissection without a partial midline sternotomy must be judged taking into consideration the possible position of the inferior thyroidal blood vessels, parathyroid glands, and the recurrent laryngeal nerves.
If the inferior aspect of the thyroid gland is safely reachable from the neck, no partial midline sternotomy is necessary. If the dissection of the inferior aspect of the gland appears to be risky, a midline sternotomy should be performed. Prior to the surgery, a surgeon must explain to the patient the possibility of a sternotomy and have available or be a surgeon experienced with sternotomy. (For more information, see Midline Sternotomy)
Once the thyroid lobe or gland is excised, it should be oriented for the pathologist with sutures (see images below).
Midline sternotomy with a self-retaining retractor exposing the mediastinal component of a substernal thyroidectomy. Photograph taken after dissection of gland from surrounding attachments.
The gland should be examined along its entire surface for the presence of parathyroid glands. If found, obtain a frozen section confirmation of parathyroid tissue by a pathologist. Once confirmed, the parathyroid tissue is minced with a sharp blade. The minced tissue is then inserted into a sternocleidomastoid, strap, or forearm muscle and marked with a thick colored suture or a series of metal clips (to make it locatable for possible excision in the future).
After excision of the thyroid lobe or gland, the trachea is assessed for any residual displacement or distortion. If tracheomalacia with residual narrowing or kinking of the lumen is present, the tracheal airway may be improved by using traction sutures placed around cartilaginous rings. The sutures can be secured to strap muscles or even brought out through the skin tied over a button.
The wound bed is irrigated, and hemostasis is achieved, where necessary.
If a midline sternotomy is performed, a sternal wire closure or plates-and-screws closure of the chest is necessary to encourage appropriate symmetrical bone healing.
An active drain(s) may be placed into the mediastinum through the thyroid bed and out the neck. A drain from the mediastinum and another drain from the thyroid bed is a reasonable possibility. The neck drain is secured in place with a monofilament nonabsorbable suture to the skin.
The strap muscles should be closed vertically (and horizontally, if necessary) with absorbable suture in order to prevent the tracheal rings from adhering to the skin, which can cause the tracheal rings to be visible through the skin and can move the skin when the patient swallows, both of which are considered noncosmetic. The skin flaps are then closed in 3 layers with a braided absorbable suture for the platysma layer, a monofilament absorbable suture for the dermal layer, and a monofilament nonabsorbable suture or set of staples for the skin layer.
The patient is then cleaned up, awakened, extubated, and wheeled to the recovery room.
Midline Sternotomy
If a partial midline sternotomy is performed, the following steps should be taken:
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Dissection and isolation of the suprasternal notch
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Careful longitudinal division of the superior half of the sternum with a sternal saw
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Control of bone marrow bleeding (with cautery and/or bone wax)
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Lateral retraction of the sternum with a self-retaining device
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Dissection of the anterior fascia layer of the superior mediastinum (see image below)
The left thyroid lobe being retracted anteromedially beyond the region of the left recurrent laryngeal nerve (pointed out by metal rod) with Berry ligament still connecting the lobe to the trachea.
With the increased exposure of a sternotomy, the goiter can continue to be dissected free of the surrounding tissue in the mediastinum and neck. Once the goiter or lobe has been excised and all bleeding is controlled, the sternum should be closed with metal wires.
The steps preceding and following performance of the sternotomy are described in Transcervical Excision of Substernal Goiter.
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Chest radiograph of substernal goiter with tracheal deviation to the right.
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CT scan of substernal goiter with tracheal compression.
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Photograph showing a goiter as a noticeable bilateral anterior inferior neck mass.
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Photograph showing a goiter as an extensive neck mass suggestive of malignancy.
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A vocal cord examination via flexible fiberoptic laryngoscopy.
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The left thyroid lobe being retracted anteromedially beyond the region of the left recurrent laryngeal nerve (pointed out by metal rod) with Berry ligament still connecting the lobe to the trachea.
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Midline sternotomy with a self-retaining retractor exposing the mediastinal component of a substernal thyroidectomy. Photograph taken after dissection of gland from surrounding attachments.
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Thyroid specimens from substernal thyroidectomy.
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Closure of neck wound with sutures and active drains.
