A 62-year-old man experienced seizure episodes and left-sided neurological symptoms. Brain imaging showed right-hemispheric stroke and isolated, proximal right middle cerebral artery stenosis of moyamoya type (
Figures 1,2
). CT perfusion imaging confirmed perfusion anomaly with increased time to maximum bloodflow (Tmax) bilaterally but accentuated in the right middle cerebral artery territory (
Figures 1,3
). Left-hemispheric perfusion anomaly was likely due to extensive right-hemispheric collateralization from the anterior cerebral artery (
Figure 2
) further increasing the risk for ischemic events.