Subclavian steal syndrome is retrograde blood flow into the vertebral artery due to occlusion or stenosis of the ipsilateral subclavian artery proximal to the origin of the vertebral artery. It is most commonly due to atherosclerotic vascular disease. Rarely, it can be due to vasculitis, aortic dissections, external compression of the subclavian artery, and congenital anatomic anomalies of the vascular system.

Prevalence of subclavian steal syndrome is approximately 1%-6%. It is most common in patients over 50 years of age, and males are affected twice as often as females. The most common risk factors for development of this syndrome include smoking, hyperlipidemia, hypertension, and diabetes.

Patients are often asymptomatic, and only 5% of patients experience neurological symptoms. Symptomatic patients typically have a decreased pulse or blood pressure in the affected arm. Symptoms may include arm pain or numbness, particularly after vigorous exercise of the arm. The left arm is affected 4 times as often as the right arm. Some patients may have transient vertebrobasilar insufficiency symptoms including dizziness, vertigo, syncope, dysarthria, diplopia, or vision loss due to posterior circulation ischemia.

Most patients can be managed conservatively; however, surgical revascularization may be needed to restore anterograde blood flow. Prognosis is generally good.