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Stroke
What is it?
There are two main types of strokes:
- An ischemic stroke occurs when there is a decrease in the amount of oxygen that is delivered to the brain by the blood vessels.
- A hemorrhagic stroke occurs when a blood vessel wall is torn and bleeding occurs in the brain as a result of the tear in the blood vessel.
About 88% of all strokes are ischemic in nature, with hemorrhagic stroke occurring only 12% of the time. Ischemic strokes are more common because there are more causes or risk factors associated with ischemic strokes, such as high cholesterol, heart disease, other heart conditions (heart failure), and high blood pressure, as opposed to a hemorrhagic stroke, where trauma to the head or high blood pressure are the main causes or risk factors.
Transient ischemic attacks (TIAs) are a condition related to strokes. A TIA is a "mini" ischemic stroke that lasts only a few minutes. It occurs when the blood supply to the brain is temporarily interrupted. TIA symptoms, which usually occur suddenly, are similar to those of a full-blown ischemic stroke, but they don't last as long. Most symptoms of a TIA disappear within an hour, although they may persist for up to 24 hours. Symptoms of a TIA can include sudden difficulty with vision, speech, behavior, and thought.
TIAs occur before an ischemic stroke in about 60% of cases, and 35% of untreated patients will develop a stroke within 5 years of a TIA. The greatest risk for stroke is early, within the first year after the TIA, with about 20% occurring within the first month and 50% within the first year after the TIA. The more frequently TIAs occur, the higher the possibility of stroke.
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What is it?
