Types of Stroke
Understanding ischemic & hemorrhagic stroke
For the brain to function properly, it needs a constant supply of blood. During a stroke, blood stops flowing to part of the brain and the affected area is damaged. The functions that relate to that part of the brain are harmed or even lost completely.
There are two main categories of stroke: ischemic and hemorrhagic. Most strokes are ischemic and are caused by a blockage in a blood vessel that supplies the brain. Strokes can also be hemorrhagic, which occur if a blood vessel in the brain ruptures (breaks open).
The heart is a pump that sends oxygen-rich blood out through blood vessels called arteries. If there is a blockage in an artery between the heart and the brain, the brain cannot get enough oxygen.
Some artery blockages are caused by plaque, which are fatty deposits, or by blood clots. Clots can form on the plaque or in the heart — especially in people with atrial fibrillation (irregular heart rhythm). If a piece of the plaque or clot breaks off and enters the bloodstream, it can flow into the brain, block the blood supply and cause a stroke.
How an ischemic stroke occurs
Ischemic stroke occurs when an artery that supplies the brain is narrowed or even blocked. This narrowing or blockage can either be caused by a buildup of plaque or by small pieces of plaque or blood clot (called emboli) breaking off into the bloodstream.
The emboli flow in the blood until they reach a narrowed blood vessel in the brain and get stuck. This stops the blood flow to that part of the brain and causes a stroke.
This is why it is important to have healthy arteries. In healthy arteries, the lining of the artery wall is smooth and allows blood to flow freely from the heart to the rest of the body. The brain can get all of the blood it needs to function well.
If you have damaged arteries caused by high blood pressure or other problems, your artery walls are roughened. These rough artery walls allow plaque to build up. Blood clots may also form on the plaque. This can narrow the artery and limit blood flow to the brain, increasing your risk of stroke.
What is TIA?
TIA is a transient ischemic attack, which is an early warning that a stroke is coming. A TIA is a temporary stroke that causes no lasting damage. You need to pay attention to the symptoms of TIA in order to seek medical attention right away to avoid the potentially serious, lasting effects of a stroke.
The symptoms may come on suddenly, and they could last for a few seconds or a few hours. You may have symptoms just once, or they could come and go for days. Regardless, if you notice any of the symptoms below, please call 911 or emergency services immediately.
Symptoms of TIA and stroke include:
- Sudden, severe headache
- Weakness, tingling, numbness or loss of feeling in your face, arm, or leg
- Trouble talking, slurred speech or problems understanding others when they speak
- Trouble seeing in one or both eyes, double vision
- Loss of balance or falling
- Dizziness or a feeling of spinning
Hemorrhagic stroke occurs when a blood vessel in the brain ruptures, or breaks open. This rupture allows blood to spill into nearby brain tissues, which damages the cells.
Other brain cells die because the normal blood supply they usually receive has been cut off by the rupture. Blood from a ruptured artery puts pressure on the brain and damages brain cells.