Delayed re-opening of an STA-MCA bypass graft.

We describe the case of a 47-year-old female with symptomatic right MCA stenosis who had undergone cerebral revascularization through a superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass. Despite clear patency in the operating room, post-operative angiography showed no flow in the bypass. Her ipsilateral internal carotid artery (ICA) was widely patent. She remained asymptomatic and follow-up angiography four years later showed a widely patent bypass graft in the setting of critical stenosis of the ipsilateral ICA. That the graft was found opened up and supplying the hemisphere was presumably stimulated by an increased "demand" and flow gradient promoting its patency.