Substernal goiter may be detected incidentally on chest x-ray or CT scan or found because of obstructive symptoms such as dyspnea, wheezing, or cough. The most common obstructive symptom is exertional dyspnea, which is present in 30 to 60 percent of cases, and usually occurs when the tracheal diameter is under 8 mm.
The treatment of obstructive and substernal goiters will be reviewed here. The clinical manifestations and evaluation of substernal goiter, and the management of benign goiter are reviewed separately. (See "Clinical manifestations and evaluation of obstructive or substernal goiter" and "Thyroid hormone suppressive therapy for thyroid nodules and benign goiter".)
Enlarging thyroid lobes usually grow outward, because of their location in the anterior neck in front of the trachea, covered only by thin muscles, subcutaneous tissue, and skin. In patients with substantial enlargement of one lobe or asymmetric enlargement of both lobes, the trachea, esophagus, or blood vessels may be displaced or, less often, compressed. Bilateral lobar enlargement, especially if the goiter extends posterior to the trachea, may cause either compression or concentric narrowing of the trachea or compression of the esophagus or jugular veins. (See "Surgical anatomy of the thyroid gland".)
With some goiters, there is growth of one or both lobes through the thoracic inlet into the thoracic cavity, which can result in obstruction of any of the structures in the inlet (image 1A-B and figure 1). Such goiters are referred to as substernal.
We recommend surgery once obstructive symptoms are present because of the risk of further thyroid growth and progressive tracheal compression, which in some instances (eg, hemorrhage) may be rapid and fatal. (See "Clinical manifestations and evaluation of obstructive or substernal goiter".)