Complete resolution of vertebrobasilar dissection and aneurysm following treatment of subclavian steal physiology

Subclavian steal syndrome results from subclavian artery stenosis that results in retrograde blood flow through the ipsilateral vertebral artery. Rarely, this retrograde flow can affect the vertebrobasilar junction and cause vertebrobasilar insufficiency, ischemia, and even aneurysm formation. We describe a unique presentation of a vertebrobasilar aneurysm presenting with subarachnoid hemorrhage in the setting of subclavian steal syndrome. The subclavian stenosis was endovascularly managed, with complete resolution of both retrograde flow and the dissection itself. Reestablishment of native flow mechanics in the subclavian artery may treat aneurysms at the vertebrobasilar junction, potentially eliminating the need for further interventions.