These clots can come from pieces of plaques in the bigger arteries that break off or from the heart. Hemorrhagic strokes occur when the wall of a blood vessel becomes weak and blood leaks out into the brain. In addition to having decreased blood flow below the leak, the blood in the brain damages brain cells as it decomposes. If a lot of blood leaks out, it can cause a build-up of pressure in the brain because the brain is enclosed in the skull. There is not room for it to expand.
Hemorrhagic strokes tend to be more serious than ischemic strokes.
The symptoms of a stroke depend on what part of the brain and how much of the brain tissue is affected. Stroke symptoms usually come on suddenly in minutes to an hour. There is usually no pain associated with the symptoms. The symptoms may come and go, go away totally, or get worse over the course of several hours. A third of all strokes occur during sleep, so people first notice the symptoms when they wake up.