Subclavian Steal Syndrome from the Carotid Artery after Carotid-Subclavian Bypass Graft

Subclavian steal syndrome (SSS) is typically because of a subclavian artery occlusion located proximal to the origin of the ipsilateral vertebral artery. Increased blood demand in the subclavian distribution then leads to retrograde flow and stealing of the blood from the ipsilateral vertebral artery (i.e., steal).1 SSS is uncommon, but may have an incidence of up to 2.5%.2 A pressure gradient drives blood flow resulting in retrograde flow within the vertebral artery, which is distal to and ipsilateral to the subclavian stenosis.3 SSS causes symptoms of vertebrobasilar insufficiency, especially during the vigorous exercise of the arm or sudden sharp turning of the head in the direction of the affected side.2 Patients can present with dizziness, syncope, vertigo, ataxia, upper limb weakness, and nystagmus.1,2 In addition to these posterior circulation symptoms, the ophthalmologist or neuro-ophthalmologist should be aware that bilateral visual loss may occur in SSS.