Vascular: Brain Perfusion

Abstract

In western countries, the incidence of acute stroke is about 200 / 100,000 per year and represents the third most common cause of death. Cerebral ischemia, caused by an occlusion of a cerebral artery, is the usual cause of stroke (85%) and has to be differentiated from intracranial hemorrhage (15%), typically occurring in the region of the basal ganglia. While therapy for intracranial hemorrhage focuses on the control of the space-occupying effect, an acute or hyperacute ischemic stroke offers the chance to recanalize the occluded vessel and to restore the neurological deficits at least to a certain extent. Due to the very limited tolerance of brain tissue to hypoxia, the patient benefits most if appropriate therapy starts immediately — “Time is brain”. While interventional endovascular treatment such as local chemical intra-arterial thrombolysis or mechanical thrombolysis is limited to certain specialized centers and is typically not available around the clock, intravenous chemical thrombolysis (e.g. with rt-PA) offers a viable option to treat hyperacute ischemic strokes. However, the time frame available for intravenous thrombolysis is limited: Currently, therapy is restricted to the first 3 hours after the onset of symptoms. Furthermore, the extent of the cerebral infarction limits the use of intravenous thrombolysis due to an increased risk of secondary bleeding in large territorial infarctions. An expansion of the therapeutic time window is desirable to offer this option to more patients suffering from ischemic stroke.1