Nineteen patients with strictly unilateral
ischemic stroke as determined by clinical examination, computed tomography, magnetic resonance imaging, and standard angiography underwent cerebral blood flow (CBF) analysis using
fluorine 18
fluoromethane and positron emission tomography. Mean flow values for averaged hemispheric,
infarct, and homologous contralateral regions of interest (ROIs) were determined. All patient CBF values were significantly below comparable CBF ROIs in neurologically normal controls using Wilcoxon's two-sample rank testing. Multiple regression analysis disclosed a significant correlation between contralateral CBF are both localized CBF in the
infarct ROI and patient age. Correlations between contralateral CBF and dependency score or severity of
neurologic deficit at time of positron emission tomography, expired PCO2, mean arterial blood pressure, serum
glucose or hematocrit, risk factor score, and number of days studied after
stroke were not statistically significant. Although we did not identify the
biologic mechanisms involved, we conclude that CBF reduction contralateral to a strictly unilateral ischemic
infarction is due to a combination of aging and transhemispheric
diaschisis.