Cerebral blood flow in acute and chronic ischemic stroke using xenon‐133 inhalation tomography

Abstract Serial measurements of cerebral blood flow (CBF) were performed in 12 patients with acute symptoms of ischemic cerebrovascular disease. CBF was measured by xenon-133 inhalation and single photon emission computer tomography. Six patients had severe strokes and large infarcts on the CT scan. They showed in the acute phase (Days 1-3) very large low-flow areas, larger than the hypodense areas seen on the CT scan. The cerebral vasoconstrictor and vasodilator capacity was tested in the acute phase following aminophylline and acetazolamide, respectively. A preserved but reduced reactivity was seen at both tests in all 6 cases in the infarct and the peri-infarct areas. On Days 5-25, 4 of the patients had transitory increases (59-108%) of CBF, probably corresponding to lysis of an intracerebral embolic occlusion. The other 2 patients showed on Days 7-15 only a moderate CBF increase (appr. 20%), both had occlusion of the relevant internal carotid artery. In all 6 patients, CBF studies at 2 and 6 months resembled the acute phase, showing large areas with reduced flow. At the 6 months follow-up, the vasodilatory stress test was repeated, and all but one showed a preserved but reduced vasoreactivity in the infarct and peri-infarct tissue. Of the remaining 6 patients, one had a pontine infarct and one had no lesions on the CT scan, both having normal angiograms and CBF maps. Four patients had small deep or subcortical CT lesions, and showed a slight, but persistent CBF reduction of about 6-8% in the parietal region on the affected side. No changes in the flow pattern were seen at the vasoreactive studies. A likely explanation for the finding of superjacent low-flow areas is an intrahemispheric uncrossed diaschisis. This interpretation is discussed in relation to the peri-infarct low-flow area seen in the 6 cases with large infarcts.