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What is a stroke?

A stroke is a sudden loss of brain function. It is caused by the interruption of flow of blood to the brain (ischemic stroke) or the rupture of blood vessels in the brain (hemorrhagic stroke). The interruption of blood flow or the rupture of blood vessels causes brain cells (neurons) in the affected area to die.

The effects of a stroke depend on where the brain was injured, as well as how much damage occurred. A stroke can impact any number of areas including your ability to move, see, remember, speak, reason and read and write.

Stroke is a medical emergency. Recognizing and responding immediately to the stroke warning signs by calling 9-1-1 or your local emergency number can significantly improve survival and recovery.


What causes brain damage from stroke?

Blood vessels called arteries carry blood that is rich in oxygen and nutrients through the body. When an artery to the brain becomes blocked or bursts, the blood supply to a part of the brain is cut off. The longer the brain goes without oxygen and nutrients supplied by blood flow, the greater the risk of permanent brain damage. Brain injuries can also result in uncontrolled bleeding and permanent brain damage. This is usually referred to as an Acquired Brain Injury.


What are the types of stroke?

There are two main types of stroke: those caused by blood clots (ischemic stroke) and those caused by bleeding (hemorrhagic stroke). When clots stop blood from flowing to the brain for a short time, a TIA (transient ischemic attack) or “mini-stroke” can happen. Stroke can happen to anyone including babies and children (pediatric stroke).


Understanding the brain and the effects of stroke

Your brain is the most complex organ in your body. It consists of more than 100 billion specialized nerve cells called neurons and it acts as a command centre for everything you do, think, sense and say. These neurons depend on the blood vessels in your brain for oxygen and nutrients. Neurons cannot duplicate or repair themselves.

Different parts of the brain control different functions. Learning what the parts of the brain do can help you understand why stroke can affect people so differently.

 

Last reviewed: April 2014
Last modified: July 2014