During Adson's Test, which finding indicates Thoracic Outlet Syndrome?

• A. Radial pulse increases on the affected side.
• B. Radial pulse remains unchanged.
• C. Radial pulse disappears or markedly diminishes on the affected side.
• D. Numbness in fingers with no pulse change.

Answer: (C)

During Adson's test, you’re checking for a vascular compression component of Thoracic Outlet Syndrome. The maneuver narrows the costoclavicular space and compresses the subclavian artery when the patient turns the head toward the testing side and takes a deep breath. A positive sign is the radial pulse either disappearing or becoming markedly diminished on the affected side. This loss or severe weakening of the pulse reflects compromised blood flow due to arterial compression in the thoracic outlet.

If the radial pulse stays the same, it suggests no vascular compression detectable by this test. Numbness with no change in pulse points more toward a neural (brachial plexus) component rather than vascular, so it wouldn’t indicate a vascular TOS on this test. An increased pulse would not indicate compression and would argue against TOS in the vascular sense.