Substernal goiters are diagnosed most often in the fifth or sixth decade of life and are more common in women. Published reports describe myriad symptoms related to substernal goiters, including dyspnea, stridor, cough, hoarseness, dysphagia, superior vena cava syndrome, Pemberton's sign, thyrotoxicosis, and Horner's syndrome. However, 50% of patients are asymptomatic, with the mass found incidentally on routine physical examination coupled with either a chest x-ray or CT scan performed for other indications. The most common symptoms attributable to substernal goiters are respiratory in nature4 (Table 133-1). Asymptomatic patients may demonstrate abnormal flow-volume loops on spirometry. In advanced cases, patients may have profound respiratory insufficiency. Many patients acknowledge exertional dyspnea on questioning (present in up to 60% of patients), and some have been treated for presumed asthma for years. A choking sensation with or without swallowing is also described commonly by patients. Dysphagia may result from compression of the esophagus. Compression of neural structures can lead to hoarseness owing to vocal cord paralysis that may be transient, permanent Horner's syndrome when the cervical sympathetic chain is affected, or even less commonly phrenic nerve paralysis. If superior vena cava compression is present, patients can demonstrate Pemberton's sign or even signs of superior vena cava syndrome. Pemberton's sign is evidence of venous engorgement of the face or neck when a patient raises his or her arms above the head. If suspected, the examiner should hold both the patient's arms above his or her head for 1 minute and watch for distention of neck veins, facial plethora, difficulty swallowing, or worsening of respiratory status, including wheezing and stridor. Patients suffering from superior vena cava syndrome demonstrate these findings without provocative maneuvers. Compression of the carotid artery rarely can result in a transient ischemic attack.