Bleeding strokes are not so common and make up for around 15% of all strokes.
If you want to avoid having a stroke you are probably asking yourself, how is this clot formed and what can I do to prevent it. In very simplified terms, blood clots are in most cases caused by one of two things: Sick arteries and Blood that clots more than normal.
There are various reasons why blood could become more likely to form a blood clot. These include genetic or hormonal imbalances or damage to blood vessels that activate clotting systems.
Blood that does not flow and is forced to stay static has a very high tendency to clot. The main organ that is responsible for your blood flowing, is your heart. As can be seen in the image on the left if your heart functions normally the electrical impulses flow in a consistent way. This means that your heart can pump rhythmically and send all blood it receives back into your body. A disease called Atrial Fibrillation could cause the heart to send irregular electrical impulses across your heart which means that it does not pump rhythmically as can be seen in the image on the right.
The biggest problem with this is that as a result the heart does not always empty all the blood out of the heart on every beat, resulting in some blood that stays behind and pools in the heart.
Pooling blood is bad and what could now very easily happen is that a clot could form and then the next time the heart beats this clot could be pumped into the brain, causing a stroke.
Patients with this disease have to take blood-thinning medication on a chronic basis to prevent blood clots from forming.