The thoracic outlet is an “opening” at the base of the neck, on both sides, where the nerves and artery that service the arm on that side exit through as they descend into the arm.  It is formed by the anterior and medial scalene muscles, the first rib, and the clavicle (collar bone).

If the thoracic outlet narrows in any way, due to one or more of these structures, neurovascular compression is possible (compression of the nerves and artery).  This can result in shoulder pain, neck pain, weakness in the affected arm and hand, numbness and tingling in the arm down to the hands, especially the last three fingers; and in some cases swelling of the arm.  Carrying something like a heavy bag on the affected shoulder makes the symptoms worse.

In thoracic outlet syndrome there is usually a history of prior injury/trauma to the shoulder girdle, such as a car accident or sports injury.  People with long necks and long arms are said to be more predisposed to this condition as the weight of the arm and length of the neck tend to put more stress in the thoracic outlet area.

Left alone without resolution, it is possible to develop permanent nerve damage resulting in chronic pain, weakness in the arm and hand, and reduced sensation in the inner arm area.

What to Do if You Suspect You Have Thoracic Outlet Syndrome

If you suspect you have thoracic outlet syndrome, see your doctor or an experienced chiropractor.  There are some simple orthopedic tests that can be done to see if you likely have TOS.  An MRI study can help visualize the thoracic outlet and identify if there is swelling; and needle electromyograph (EMG) can determine if the arm muscles are getting the proper amount of nerve flow.

If the diagnosis is confirmed, physical therapy exercises are usually prescribed to help open the thoracic outlet space.   In some cases, imaging studies show a fibrous band  responsible for compressing the neurovascular structure; in these cases surgery may be an option.  This involves the scalene muscles — three, short muscles that connect the lower neck vertebrae to the ribcage.

In the meantime, try doing this exercise.  It is designed to create more space between the collar bone and the ribcage.  If this is where your compression is occurring, it may help.