Decrease in cerebral blood flow with blood pressure reductions in patients with chronic stroke.

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Abstract
Possible effects of changes in blood pressure on the cerebral circulation were studied in patients with chronic stroke and age-matched nonstroke control subjects at 28 +/- 10 months (mean +/- SD) (range, 18 to 54 months) and 27 +/- 6 months (range, 19 to 44 months), respectively, after the first measurement. Cerebral blood flow was measured by the 133Xe inhalation method in 55 patients (mean +/- SD age, 62 +/- 11 years; 39 with brain infarction and 16 with hemorrhage) and 10 control subjects (mean +/- SD age, 61 +/- 9 years). Correlations between changes in cerebral blood flow and blood pressure were evaluated. Among brain infarctions, average cerebral blood flow did not change from the first study; however, changes in cerebral blood flow in each individual were closely related to changes in systolic and mean arterial blood pressures (P < .01 and P < .05, respectively). Of these, in 10 patients with cerebral blood flow decreased more than 15% from the initial levels, systolic and mean arterial blood pressures decreased by 25 +/- 32 mm Hg and 16 +/- 14 mm Hg (P < .05 and P < .005, respectively). In contrast, in 29 patients with unchanged or increased cerebral blood flow, changes in systolic (0 +/- 19 or -2 +/- 12 mm Hg, respectively) and mean arterial blood pressures (3 +/- 22 or -1 +/- 11 mm Hg, respectively) were not significant, and their systolic blood pressure levels were maintained above 110 mm Hg. Blood pressure importantly correlates with cerebral circulatory changes among patients with chronic brain infarction. Early detection of cerebral hemodynamic changes should be useful for determining the most favorable levels of blood pressure and for selecting appropriate therapy.