Figure 3.

Pathophysiological changes in cerebral infarction. At the onset of ischemia, the initial fall in regional cerebral blood flow (CBF) is mirrored by a rise in regional oxygen extraction fraction (OEF). Since the increase in OEF is no longer able to maintain the energy needs of the brain, regional cerebral oxygen metabolism (CMRO₂) falls to the level of oxygen delivery. With time, CMRO₂ falls further even though there is no further decrease in CBF, resulting in a decrease in OEF. Reperfusion via recanalization of the occluded artery or recruitment of collateral pathways results in an increase in CBF (“luxury perfusion”) and a concomitant fall in OEF below baseline with no change in CMRO₂. With evolution to the stage of chronic infarction, CBF progressively declines and OEF increases, but often remains below baseline values. (Reprinted from Powers.¹⁵⁶).