Thoracic outlet syndromes are a group of disorders caused by pressure on nerves as they pass between the neck and chest. These disorders cause pain and pins-and-needles sensations (paresthesias) in the hand, shoulder, and arm.
The thoracic outlet is the passageway between the neck and the chest for the esophagus, major blood vessels, trachea, and many nerves. Because this passageway is very crowded, blood vessels or nerves to the arm may be squeezed between a rib and the overlying muscle, resulting in problems. Nonetheless, the exact cause of thoracic outlet disorders is often unclear. Very rarely, the cause is a clear-cut anatomic abnormality, such as an extra little rib in the neck (cervical rib) that puts pressure on an artery, a badly healed fracture of the collar bone, or a blockage of one of the subclavian arteries. (The subclavian arteries are located under the collar bone and carry blood to the arms.)
Thoracic outlet syndromes are more common among women and usually develop between the ages of 35 and 55.
Pain and pins-and-needles sensations usually begin in the neck or shoulder, then spread along the inner surface of the arm into the hand and sometimes down the side of the torso.
If pressure is put on one of the subclavian arteries, the hand, arm, and shoulder on the affected side may swell, or the overlying skin may look bluish because the oxygen supply is inadequate (a condition called cyanosis). Sometimes the pressure is severe enough to cause Raynaud syndrome, in which the fingers become pale or blue and often numb when exposed to cold.
Doctors base the diagnosis on symptoms and results of a physical examination and several diagnostic tests. Nerve conduction studies and electromyography (see Symptoms and Diagnosis of Brain, Spinal Cord, and Nerve Disorders: Electromyography and Nerve Conduction Studies) may detect abnormalities characteristic of thoracic outlet syndrome. Through a stethoscope placed on the collar bone or near the top of the armpit, doctors may hear sounds indicating abnormal blood flow (bruits) in an artery that is being squeezed by nearby structures.
Angiography of the arteries in the arm (brachial arteries) may be done to detect abnormal blood flow. In this test, x-rays are taken after a dye that is visible on x-rays (radiopaque dye) is injected into the bloodstream. Magnetic resonance imaging (MRI) may be done to look for anatomic abnormalities. However, none of these tests can definitively confirm or rule out the diagnosis of thoracic outlet syndrome.
For most people with symptoms of thoracic outlet syndrome, physical therapy and exercise result in improvement. Nonsteroidal anti-inflammatory drugs (NSAIDs) and antidepressants given in low doses may also help.
Surgery may be needed if an anatomic abnormality or blockage of the subclavian artery is confirmed or if symptoms continue to progress. However, because a definitive diagnosis is difficult to make and because symptoms often persist after surgery, most doctors try to avoid surgery.
Last full review/revision September 2012 by Michael Rubin, MDCM