Evaluation of Critical Blood Flow in the Acute Stage of Ischemic Cerebrovascular Disease

Twenty-nine patients were admitted to Osaka Neurological Institute with symptoms of acute cerebral ischemia. On admission, cerebral blood flow (CBF) was evaluated by CT with inhalation of stable xenon (XeS), followed by cerebral angiography. The latter disclosed occlusion of the main trunk of the internal carotid artery, middle cerebral artery, or else M2 segment. Twenty-one patients underwent superficial temporal-middle cerebral artery anastomosis on the day of admission, and the other patients with relative or definite low density area on CT scans on admission were treated conservatively. Within 6 hours of onset, the critical cerebral blood flow level, which was defined as a value to induce cortical infarction, decreased in proportion to the time between the onset and XeS CT-CBF study (time- and residual flow-dependent period). After this period, the critical level existed at about 19 ml/100g/min (time-independent period) within 24 hours. And the patients' prognosis had a significant positive correlation with the residual CBF. In summary, the measurement of CBF is mandatory to select the best choice of therapy for patients with acute ischemic cerebrovascular disease.