A 62-year-old hypertensive man develops blurring of vision and dizziness confined to episodes when he uses his right arm above shoulder height. Right radial pulse is weak, and there is a 30 mmHg difference in systolic blood pressure between the two arms. A bruit is heard above the right clavicle. Duplex shows retrograde flow in the right vertebral artery during arm exercise. What is the diagnosis?

• A Subclavian steal syndrome ✓
• B Neurogenic thoracic outlet syndrome
• C Vertebral artery hypoplasia
• D Giant cell arteritis

Explanation

C proximal subclavian artery stenosis lowers pressure beyond the vertebral origin, so arm exercise diverts blood retrogradely down the ipsilateral vertebral artery, stealing flow from the vertebrobasilar circulation and causing posterior circulation symptoms. The hallmarks are an inter-arm systolic pressure difference greater than 20 mmHg, a supraclavicular bruit, and demonstrated retrograde vertebral flow. Neurogenic thoracic outlet causes positional nerve root symptoms without vertebrobasilar events or reversed vertebral flow, which kills that distractor.

Reference: Bailey and Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.