Most strokes happen suddenly and damage the brain within minutes. In rarer cases, a stroke may get worse for several hours to a day or two as a steadily enlarging area of the brain dies (stroke in evolution). In this case, the stroke is usually (although not always) interrupted by stable periods when the area temporarily stops getting bigger or some improvement occurs.
The common symptoms of stroke include:
- Loss of (or abnormal) sensations in an arm, leg or one side of the body
- Weakness or paralysis of an arm or leg or one side of the body
- Partial loss of vision or hearing
- Double vision
- Slurred speech
- Problems thinking of or saying the right word
- Inability to recognize parts of the body
- Imbalance and falling
Causes and Risk Factors
This type of stroke can be caused by a blockage anywhere along the arteries feeding the brain. The blockages can occur for many reasons, including:
- The build up of fatty material (atheroma) along artery walls that cuts down blood flow
- Breaking off of an atheroma from the artery wall. It can flow with the blood getting stuck in a smaller artery causing a blockage.
- Blood clots that break loose from the heart or one of its valves, known as an emboli. They can go through the arteries to the brain, where they lodge causing an embolic stroke or cerebral embolism. This is most common in people who have recently had heart surgery or who have defective heart valves or abnormal heart rhythms.
- Blood clots that may break loose from a ruptured aneurysm in the brain or from bleeding
- Inflammation or an infection that narrows blood vessel that leads to the brain
- Drugs such as cocaine and amphetamines, which can narrow blood vessels
- Sudden drop in blood pressure. Although a sudden drop in blood pressure usually causes a person to faint, it can lead to a stroke if it is severe and lasts a long time. This happens when someone loses a lot of blood from an injury or surgery, has a heart attack or has an abnormal heart rate or rhythm.
Strokes may also cause swelling in the brain. The resulting pressure can damage brain tissue more, making neurologic problems worse even if the stroke itself doesn't enlarge.