Subclavian Steal Syndrome

Uncommon entity with a variably reported clinical significance

Male:female ratio: 2:1

Stroke from a plaque originating from vertebral artery system

Stroke from a plaque originating from subclavian artery

Worsening neurologic symptoms

Upper limb ischemia

Retrograde blood flow from vertebral artery to distal subclavian secondary to proximal ipsilateral subclavian or innominate artery stenosis or occlusion occurs when the pressure at the subclavian end of the vertebral artery drops below the basilar artery pressure.

Presence of other extracranial arterial disease is a prerequisite to development of symptoms.

Criteria for diagnosis (must be symptomatic):

• Cerebral ischemia causing neurologic symptoms associated with ipsilateral arm exercise.

• Decreased BP or arm claudication in ipsilateral arm secondary to occlusion or stenosis of subclavian artery proximal to vertebral artery.

Ratio of left-sided to right-sided SSP is 3:1. The left subclavian artery at increased risk for atherosclerosis secondary to more acute angle of takeoff and turbulent flow.

Symptoms may be obscured by concomitant carotid insufficiency.

Spontaneous resolution of vertebrobasilar symptoms may be related to the establishment of extracranial collaterals to the subclavian circulation.