Complete recanalization via fibrinolytic therapy can reduce the number of ischemic territories that progress to infarction.

PURPOSE To clarify the clinical significance of fibrinolytic therapy for acute ischemic stroke.

METHODS We analyzed findings in 18 patients with occlusion of a major artery in respect to cerebral blood flow thresholds for infarction. Nine of these patients had shown complete recanalization just after the treatment, between 3.5 and 7.25 hours after symptom onset, and the other nine had shown no change. Cerebral blood flow was measured by single-photon emission CT using 99mTC-labeled hemamethylpropyleneamine oxime and assessed semiquantitatively: multiple regions of interest were placed on the section images and two parameters, the R/CL ratio and the R/CE ratio, were calculated (where R represents a mean count of the region of interest in the affected hemisphere, CL on the opposite side, and CE in the cerebellar hemisphere on the affected ischemic side).

RESULTS Reperfusion significantly reduced the development of infarction in the regions of interest with an R/CL ratio between 0.65 and 0.85 or an R/CE ratio between 0.55 and 0.75. No correlation was observed between the development of infarction and the duration of ischemia. The cerebral blood flow threshold in patients without recanalization was higher than that in patients with recanalization.

CONCLUSION Reperfusion achieved by fibrinolytic therapy in the acute stage can save ischemic brain within a limited cerebral blood flow value.