The patient has a thoracic outlet syndrome (TOS), which is an abnormal compression of the aeries, veins, or nerves in the neck. TOS is more common in adults than in children, and may occur in either sex. The compression may be caused by a cervical rib, the scalenus anticus muscle, or positional changes. The diagnosis is confirmed with an aeriogram. Nerve conduction studies do not distinguish TOS from cervical disc disease, since the nerves are also involved in TOS.