Thoracic Outlet Syndrome

Thoracic Outlet Syndrome (TOS) is a result of compression of the nerves and blood vessels that supply the upper extremity. The nerves and blood vessels can be compressed between the anterior and middle scalene muscles in the neck and the first rib. It is commonly caused by sagging of the shoulder girdle due to large breasts, obesity and aging. Also, poor posture, repetitive motions of some occupations, and overly built muscle from physical activity (ie. weight lifting, baseball pitching) can cause TOS.

TOS often presents in the upper extremity as a combination of pain, numbness, weakness and swelling. The onset can be gradual or sudden. TOS pain radiates from the area of compression on the lower neck and may radiate to the armpit, shoulder girdle, arms and hands. Dull pain and numbness is often felt in the fourth and fifth fingers.

Signs and symptoms may be worse at night or after prolonged use of the upper extremity. Weakness and decreased muscle mass may also be seen in the upper extremity.



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