thoracic outlet syndrome Definition

any of a group of neurovascular disorders that are marked by the compression of nerves (as the brachial plexus) or blood vessels (as the subclavian artery or vein) as they pass from the neck toward the armpit or proximal arm through a space in the upper thorax between the clavicle and the first rib, that typically result in pain, numbness, weakness, or intolerance to cold, and that are usually caused by a congenital anatomical anomaly, traumatic injury, or repetitive motion of the shoulder and arm