The effect of cerebral infarction on the regional cerebral blood flow of the contralateral hemisphere.

Regional cerebral blood flow (rCBF) measurements were performed over the contralateral hemisphere by the 133Xe intracarotid injection method in 20 patients with acute cerebral infarction in the territory of the internal carotid artery. The rCBF was found to be reduced, sometimes remarkably, in all of the patients. The mean reduction was 30 percent to 36 percent from the lowest normal value for the mean age of these patients. In the younger age group (40 to 59) the reduction was greater, 40 percent to 47 percent from the lowest normal value for this age. tthe rCBF depression was not related to cerebral dominance, previous hypertension or arterial PCO2 levels. The occurred in both patients who were fully alert and those with disturbances or consciousness, although it tended to be more diminished in the latter. tit can be assumed that the flow reduction in the nonaffected hemisphere is part of a general phenomenon affecting the entire brain and caused by globally reduced cerebral metabolism.