An ischemic stroke is a condition whereby the blood flow to a part of the brain is interrupted. The interruption of blood flow may be for a brief few seconds or it may be prolonged, lasting hours. It is more likely that a stroke will occur if the blood flow is interrupted for a prolonged period of time, although even symptoms lasting for seconds may cause a stroke. Generally, if symptoms resolve completely within the first hour, the event is referred to as a TIA, or transient ischemic attack. This terminology does not mean that the process is benign, but rather, that the process caused no deficits. Even brief symptoms will require a full evaluation. The type of evaluation depends on the type of stroke.
The window of opportunity to treat an ischemic stroke is extremely brief. Some ischemic strokes are treatable with drugs that destroy clots (clot busters). The Food and Drug Administration (FDA) has approved the use of t-PA (clot buster) for use in patients presenting within three hours of symptoms. However, because of the potential for bleeding, the drug is given selectively even in those patients arriving within the first three hours. Occasionally, patients presenting after three hours are treated with a clot buster. Usually those patients have a large clot blocking flow in a large artery. In these cases, a catheter may be put into the artery, the clot is mechanically disrupted and a clot-busting drug is given into the clot. Sometimes a stent is placed in the artery to keep it open.