Thoracic outlet syndrome is a medical condition where the nerves, arteries, and/or veins are compressed as they pass from the chest to the upper extremities. This can be caused by an abnormality of the chest, such as extra ribs or narrowing of the space between the ribs and clavicle, or by muscle growth impinging on the thoracic outlet. People with thoracic outlet syndrome will have symptoms depending on which structures are affected most. Neurogenic thoracic outlet syndrome can cause weakness, pain, or numbness in the arm. Arterial thoracic outlet syndrome can product pain, cold hands, and weakness. Venous thoracic outlet syndrome can cause swelling of the affected arm. Typically, a combination of symptoms will be present due to compression of numerous structure. Thoracic outlet syndrome is diagnosed by physical findings, X-rays, and specific tests of the arteries, veins, and nerves. Many people with thoracic outlet syndrome will improve with physical and occupational therapy. Those people who have persistent symptoms may benefit from surgery to relieve the compression of the thoracic outlet.