EEG and SPECT Changes in Acute Ischemic Stroke

Acute cerebral ischemia is one of the leading causes of mortality and morbidity with age-adjusted incidence rate accounting for around 200 cases per 100,000 population/years [1]. Ischemic stroke may manifest in the form of thrombotic stroke, embolic stroke, systemic hypoperfusion or venous thrombosis [2]. If hemodynamic instability is severe and prolonged, it may produce focal as well as diffuse cerebral changes where the effect of ischemia whether reversible or irreversible, is dependent on the degree and duration of blood flow. In stroke, paradoxical increment of cerebral blood flow (CBF) can be witnessed at the involved site and is referred to as luxury perfusion [3]. Core ischemic regions (blood flow<15%), penumbral regions (blood flow<40%) and extrapenumbral cortical regions (blood flow rate>40%) can result both proximal and distal to arterial occlusion. This approximate flow based definition of core and of penumbra as well as extrapenumbral region is generally agreed upon but still ample argument exists [4]. Ischemic penumbra generally arises in the periphery of the brain when blood flow is significantly reduced to cause hypoxia, but not severe enough to cause irreversible failure of energy metabolism and cellular necrosis [5].