What is a stroke? Stroke, also called brain attack, cerebrovascular accident, or cerebral infarction, is a very serious condition in which the brain is not receiving enough oxygen to function properly. Stroke often results in serious and permanent complications and disability. It is the third leading cause of death in the United States, according to the American Stroke Association. (Source: ASA). The brain requires a steady supply of oxygen in order to function effectively. Oxygen is supplied to the brain from the blood that flows through arteries. A stroke occurs when an artery that supplies blood to the brain becomes blocked or ruptures and begins to leak. When this occurs, the area of the brain that is not getting enough oxygen-rich blood from that artery is damaged. The injury can become permanent within minutes and results in death of the affected brain tissue. Medically this is called cerebral necrosis. A stroke can also cause a buildup of pressure inside the skull, which can result in permanent injury to the brain. Stroke is a form of cardiovascular disease. There are two main types of strokes: Hemorrhagic stroke occurs when an artery in the brain ruptures or leaks blood. Ischemic stroke occurs when an artery in the brain has been blocked. The extent of the damage done to the brain during a stroke varies depending on such factors as the type of stroke, the area or areas affected, and how much time passes before the stroke is treated. A stroke is potentially an immediately life-threatening condition. Immediate emergency treatment best minimizes the risk of death and other serious complications, such as permanent neurological damage, paralysis, and disability. Seek immediate medical care (call 911) if you, or someone you are with, have one or more symptoms of a stroke, including confusion, disorientation, slurred speech, inability to move a part of the body, or passing out.