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Fig 2. The ischemic penumbra. Occlusion of a major cerebral artery such as the proximal right MCA, illustrated here, results in changes in the hemodynamics of the brain that vary from patient to patient. With occlusion, collateral vascular channels can provide blood flow to ischemic regions. Here, collateral circulation from the right anterior cerebral artery distribution to the right MCA territory is depicted. The perfusion within the vascular territory of the occluded artery varies with some areas receiving little blood flow, whereas other areas receive near-normal amounts of blood flow. This results in 2 regions: an infarction core that represents irreversibly injured brain and an ischemic penumbra that may be clinically symptomatic but can be rescued if blood flow is restored.
