Stroke – Definition and Types of Strokes
Stroke, or also known as brain attack, is a disease that affects the blood vessels that supply blood to the brain. It occurs when a blood vessel is clogged by a blood clot (ischemic) or a rupture of the blood vessel (hemorrhage).
When one of these things happens, the brain cells do not get blood and oxygen they need. As a result, nerve cells in areas affected by the brain can not work properly, and die within a few minutes (usually 3 to 4 minutes). And when nerve cells can not work, abilities controlled by that area of the brain are lost. These abilities include speech, movement and memory.
Types of Strokes
There are two major types of stroke: Ischemic stroke and Hemorrhagic stroke
Ischemic stroke is the most common type of stroke, accounting for approximately 80% of all stroke cases. This type of stroke is caused by a blockage of blood flow to areas of the brain. The most common types of ischemic stroke include:
- Embolic stroke
Embolic stroke occurs when blood clots or cholesterol plaques travels through bloodstream into the brain. Once in the brain, the clot eventually travels to a small blood vessel to block its passage. This leads to clogged arteries and prevent blood reaching the part of the brain.
- Thrombotic stroke
In this type of Ischemic stroke, blood clots form throughout the inside of blood vessels causing disruption of blood flow to areas of the brain. The process leading to this blockage is known as Thrombosis, it usually affects very small blood vessels in the brain, especially in people with high cholesterol.
Hemorrhagic stroke is often caused by a ruptured blood vessels such as aneurysms or arteriovenous malformations. In many cases this is the result of uncontrolled high blood pressure. There are two types of hemorrhagic stroke: Intracerebral and Subarachnoid
- Intracerbral hemorrhage: Bleeding occurs from vessels inside the brain tissue. High blood pressure (Hypertension) is the primary cause of this type of hemorrhage.
- Subarachnoid hemmorrhage(SAH): Bleeding occurs in a large artery along a space between two of the membranes that surrounding the brain.
Blood spills into the area around the brain that is filled with protective fluid, causing very severe headache, which is typically described by people as the worst headache of their lives.
As blood accumulates in the brain, normal brain tissue push against the skull wall. This process will increase the pressure inside the brain, to the point that blood flow to the highest pressure area is completely disrupted. This area ceases to function, and causes symptoms that can range from dizziness, nausea to a headache accompanied by a typical stroke symptoms. Hemorrhagic stroke symptoms should not be overlooked as they can develop rapidly and in the worse cases they can cause sudden death.