Thoracic outlet syndrome: A condition that is due to compromise of blood vessels or nerve fibers between the armpit (axilla) and the base of the neck, because of compression by adjacent tissues. Symptoms include pain, arm weakness, and numbness in the hands and fingers. Thoracic outlet syndrome can be caused by muscle development from some types of manual work or exercise, injury, or malformation. Treatment involves physical therapy and use of anti-inflammatory medication, and sometimes by surgery.
Via:: Daily medical word