Microcirculatory obstruction in focal cerebral ischemia. Relationship to neuronal alterations.

The cerbral microcirculation in squirrel monkeys was studied by the carbon perfusion technique after middle cerebral artery occlusion. No filling impairment was detected with 90 minutes of ischemia, and only slight impairment was detected with 3 hours of ischemia. Severe microcirculatory obstruction was found after ischemia longer than 3 hours. The obstruction appeared to be at the capillary level and seemed partly the result of narrowing of cappillary channels by perivascular glial swelling and developing cerebral edema. The relationship between the developing microcirculatory obstruction and the distribution and severity of the neuronal alterations was studied. The results of this investigation using the same experimental model suggest that obstruction of parenchymal vessels does not play a major role in the production of an infarct in areas of acute focal ischemia.