The patient initially presented with a stroke which was visualized on CT and confirmed on MRI. The MRI also demonstrated extensive leptomeningeal FLAIR hyperintensity. This finding alone lends itself to a wide differential diagnosis 3. In conjunction with the occlusive MRA findings (which were confirmed with catheter angiography), the FLAIR signal abnormalities are most consistent with the "ivy sign" of Moyamoya. This sign has been attributed to slow flow through pial collateral arteries4. Although, more recently, it has been concluded to result from dilated pial vasculature compensating for decreased perfusion pressure 1. In this case, the FLAIR signal abnormality nearly completely resolves after surgery.