What causes a stroke?
Stroke is a disease that affects the blood vessels that supply blood to the brain.
A stroke occurs when a blood vessel that brings oxygen and nutrients to the brain bursts (hemorrhagic stroke) or is clogged by a blood clot or some other blocks (ischemic stroke due to locally). When faults or blockages happen, a part of the brain does not receive enough blood and oxygen needed. Without oxygen, nerve cells in the affected area of the brain cannot work normally, and necrosis within a few minutes (usually from 3 to 4 minutes). And when nerve cells do not work, the body by which cells control cannot operate. The devastating impact of severe stroke are often permanent because prolonged brain dead cells cannot be replaced.
There are two main types of stroke. One kind (ischemic stroke due to locally) due to blockage of a blood vessel caused; the other (hemorrhagic stroke) caused by bleeding. Hemorrhagic stroke have higher mortality risk than stroke due to blockage.
Ischemic stroke due to what is local?
Ischemic stroke due to locally is the most common type. It accounts for about 87% of all strokes. It occurs when a blood clot (thrombus) forms and blocks blood flow in an artery bringing blood to part of the brain. Blood clots usually form in arteries damaged by fatty buildups, called hardening of the arteries.
When a clot forms in an artery of the brain, it is called a thrombotic stroke. This type usually occurs at night or early morning. Another distinctive feature is that it is often preceded by a transient ischemic attack. This is called a TIA or “warning stroke”. TIA has the same symptoms as a stroke but lasts only a few minutes; the symptoms of stroke occur much longer and usually permanent. If someone experiences a TIA, they should get emergency care immediately.
What is a cerebral embolism?
A move clot (embolus) or other material forming the brain, usually in the heart, can cause ischemic stroke due to locally. This is called a cerebral embolism. Blood clots move through the blood stream until it lodges in an artery leading to or in the brain, blocking blood flow.
The most common cause of these emboli is blood clots formed during atrial fibrillation (AF). AF is a disorder found in about 2.2 million Americans. It causes 15-20% of all strokes. During atrial fibrillation, the two small upper chambers of the heart (the atria) quiver like a bowl of jelly instead of pounding and efficiency. Some blood is not pumped completely out of the atrium when the heart beats, so blood pools and clots can. When clot went into circulation and lodges in a narrowed artery of the brain, a stroke occurs. This is called a stroke caused by cerebral ischemia due to cardiac vascular embolism, or a type of stroke occurs due to a heart problem.
Hemorrhagic stroke is what?
There are two types of brain hemorrhage, subarachnoid hemorrhage and intra-cerebral hemorrhage. Subarachnoid hemorrhage occurs when a blood vessel on the brain’s surface ruptures and bleeds into the space between the brain and skull (but not into the brain).
A cerebral hemorrhage occurs when an artery disease (typically a very small arteries) in the brain bursts, flooding the surrounding tissue with blood.
Hemorrhage (or bleeding) from an artery in the brain can be caused by the bursting of a small blood vessel or a ruptured aneurysm. Aneurysms are blood-filled pouches that balloon out from weak spots in the artery wall. They are often caused by high blood pressure or worsening. Aneurysms are not always dangerous, but if one bursts in the brain, they cause a hemorrhagic stroke.
When bleeding occurs in the brain, the loss of blood supply continuity will mean that some brain cells cannot function anymore. Accumulated blood from burst artery may put pressure on the surrounding brain tissue and interfere with how the brain activity. These symptoms may be serious or light generated, depending on the high or low pressure.
The amount of bleeding determines the severity of brain hemorrhages. In many cases, people with intra-cerebral hemorrhage deaths increased pressure in the brain. But the survivors tend to recover faster than many people who had a stroke caused by a clot. That’s because when a blood vessel is blocked, part of the brain dies – and the brain does not regenerate itself, in other words, the brain cells cannot be replaced. But when a blood vessel in the brain bursts, pressure from the blood compresses part of the brain. If the person survives, pressure will gradually disappear. Then the brain may regain some original function.