Thoracic Outlet Syndrome

Thoracic outlet syndrome (TOS) is a group of symptoms that relates to not only the upper extremity, but also the chest, neck, shoulders and head. The thoracic outlet is a space between the first rib and the collarbone (clavicle) through which the main blood vessels and nerves pass from the neck and thorax into the arm. The symptoms can range from mild numbness and tingling of the fingers to more severe functional disability and incapacitation. A simple objective test can be done to assess the positional vascular obstruction at the thoracic outlet: observation of the change in color of the hands when the patient elevates the hands above the shoulder girdle, with the fingers pointed to the ceiling and the palms facing the observer. The appearance of paleness in one or both hands is called the White Hand Sign.

There are several causes of thoracic outlet syndrome. The common underlying cause of the syndrome is compression of the nerves and arteries of the arm in the thoracic outlet. In some cases the cause of compression is evident – an extra first rib or an old fracture of the clavicle, which reduces the space of the outlet. In other cases the cause is not clear. Compression may occur with repetitive activities that require the arms to be held overhead.

Thoracic outlet syndrome has been described as occurring in a diverse population. It is most often the result of poor or strenuous posture, but can also result from trauma or constant muscle tension in the shoulder girdle. The most frequent manifestation of thoracic outlet syndrome involves the brachial plexus, which is the network of motor and sensory nerves that supply the arm, the hand and the region of the shoulder girdle. Patients with thoracic outlet syndrome may experience muscle spasm and tenderness particularly across the top of the shoulder, over the shoulder blade, neck, collar bone area, upper arm and/or armpit areas. The trapezius, sternocleidomastoid, and scalene anticus muscles are affected.

Certain tests help to establish the diagnosis of thoracic outlet including ultrasound, chest and/or cervical spine x-rays and electrical nerve studies. Some patients may require x-ray exams of the arteries or veins to fully diagnose the problem.

Thoracic outlet may be treated conservatively with physical therapy, avoiding repetitive arm motion, practicing proper posture and/or pain medication. Despite the effectiveness of conservative therapy, ten to thirty percent of these patients will eventually require surgery to control their symptoms. When necessary the surgical therapy consists of removing the first rib.

If you have questions about the treatment for thoracic outlet syndrome, please e-mail Dr. George Sheng at