for cells in the brain to function. Consumption of ATP continues in spite of insufficient production, this causes total levels of ATP to decrease and lactate acidosis to become established (ionic homeostasis in neurons is lost). The downstream mechanisms of the ischemic cascade thus begins. Ion pumps no longer transport Ca2+ out of cell, this triggers release of glutamate, which in turn allows calcium into cell walls. In the end the apoptosis pathway is initiated and cell death occurs. There are several arteries that supply oxygen to different areas of the brain, and damage or occlusion of any of them can result in stroke. The carotid arteries cover the majority of the cerebrum. The common carotid artery divides into the internal and the external carotid arteries. The internal carotid artery becomes the anterior cerebral artery and the middle central artery. The ACA transmits blood to the frontal parietal. From the basilar artery are two posterior cerebral arteries. Branches of the basilar and PCA supply the occipital lobe, brain stem, and the cerebellum. Ischemia is the loss of blood flow to the focal region of the brain. This produces heterogeneous areas of ischemia at the affected vascular region, furthermore, blood flow is limited to a residual flow. Regions with blood flow of less than 10 mL/100 g of tissue/min are core regions (cells here die within minutes of a stroke). The ischemic penumbra with a blood flow of <25 ml/100g tissue/min, remain usable for more time (hours). Types of stroke There are two main divisions of strokes: ischemic and hemorrhagic. Ischemic stroke involves decreased blood supply to regions of the brain, while hemorrhagic stroke is bleeding into or around the brain. Ischemic Ischemic stroke, the most common is caused by a blockage of a blood vessel in the brain, usually caused by thrombosis or emboli from a proximal arterial source or the heart, that leads to the brain being starved of oxygen. The neurologic signs and symptoms must last longer than 24 hours or the brain infarction is demonstrated, mainly by imaging techniques. Transient ischemic attack (TIA) also called a mini-stroke. This is a condition in which the blood flow to a region of the brain is blocked, but blood flow is quickly restored and the brain tissue can fully recover. The symptoms are only transient, leaving no sequelae, or long-term deficits. In order to diagnose this entity, all neurologic signs