Acute respiratory failure caused by neglected giant substernal nontoxic goiter.

Substernal goiter is usually defined as a goiter in which the thyroid mass has descended the plane of the thoracic inlet or if more than 50% of the thyroid mass is located below the thoracic inlet. Substernal goiters may be asymptomatic or may present with symptoms caused by compression of adjacent organs. Acute respiratory failure is rare in cases of substernal goiter.