Ischemic stroke happens when part of the brain is injured because it isn’t getting enough blood. The brain needs a constant supply of blood, which carries oxygen and other nutrients. The brain cannot survive for long without the oxygen carried by the blood. If a small part of the brain doesn’t get enough blood, that small part of the brain will die.
Normally, blood from the heart flows freely through arteries to the brain. In image 1 at right, you can see how blood flows up through arteries that fan out into smaller and smaller branches and carry blood to every part of the brain. In the second image, the arrow points to a clot that blocks one of the arteries that feeds part of the brain. The pale-colored part of the brain depended on that artery, and is injured as a result of the blockage.
Hemorrhagic stroke happens when part of the brain is injured because there is bleeding inside the brain. The brain needs a constant supply of blood, which carries oxygen and other nutrients. Inside the brain, there is a large network of arteries and small blood vessels that carry blood from the heart to all parts of the brain. If one of these arteries or small blood vessels is injured, blood will leak out into the brain and cause swelling and other damage.
What causes hemorrhagic stroke?
Malformed Blood Vessels
Blood flows from the heart to the body through blood vessels called arteries. Arteries are thick and strong, like a fire hose. Arteries have to be strong because blood flows from the heart to the body quickly with a lot of pressure. In the body, big arteries branch off into smaller and smaller blood vessels that help to slow the blood down before it enters the veins and travels back to the heart. Veins are thin and floppy, like a water balloon. Veins do not have to be strong like arteries because blood flows through veins to the heart very slowly. In a normal body, the fast-moving, high-pressure blood in the arteries always slows down before it gets to the veins. Some children are born with big arteries that connect directly to veins without any small branches to slow the blood down. This is like filling a water balloon with a fire hose — the thin, floppy vein cannot handle the fast-moving, high-pressure blood coming from the thick, strong artery. Under this sort of pressure, the vein can leak or burst. If this happens inside the brain, it can cause a hemorrhagic stroke. There are other ways that blood vessels can be malformed in a way that can lead to stroke. Your doctor will explain to you what the specific problem was that led to your child’s stroke.
Usually, blood cells flow freely through arteries to carry oxygen and nutrients to every part of the body. However, these blood cells also must be able to clump together and form a clot if we are injured. This is what happens when a scab forms over a cut. The body has a very complicated system that tells the blood when to flow and when to clump together and clot. In most people, this system keeps the blood flowing freely, but allows clots to form when we need them. Some children have illnesses that affect their bodies’ ability to form clots. In these cases, clots cannot always form when they are needed. Children whose bodies have trouble forming clots often bleed very easily. If bleeding happens in the brain, then a hemorrhagic stroke happens. Your doctor will let you know if thin blood may have caused your child’s stroke.
Leaky blood vessels
Blood flows to the brain through thick, strong arteries. Some children have diseases that can damage the walls of their arteries. When this happens, the arteries can start to leak blood. If this happens in the brain, it can cause a hemorrhagic stroke. Your doctor will explain to you if your child has an illness that can damage the blood vessels and cause a stroke.
Sometimes, severe injury to the head or neck can cause bleeding inside the brain, or hemorrhagic stroke.