Which symptom is most characteristic of arterial thoracic outlet syndrome?

• A. Coldness of the hand
• B. Numbness of the fingers
• C. Weakness of intrinsic hand muscles
• D. Swelling

Answer: (A)

Arterial thoracic outlet syndrome causes reduced blood flow to the hand because the subclavian artery is compressed as it travels under the outlet structures. The hallmark consequence is ischemia in the distal hand, so the most characteristic symptom is coldness of the hand (often with pale color and diminished pulses). Numbness of the fingers can occur if nerves are involved, but that pattern is more typical of neurogenic TOS, where nerve compression produces sensory changes and sometimes weakness. Weak intrinsic hand muscle weakness points to nerve involvement or chronic ischemia affecting motor fibers, not the primary vascular insufficiency. Swelling suggests venous congestion, as seen in venous TOS, rather than arterial insufficiency. So coldness of the hand best reflects the arterial blood flow problem.