What is a Stroke?

A friend of mine recently died after sustaining a stroke. What is a stroke, and what are the causes and common symptoms of a stroke?

A stroke is a brain attack, which occurs when the blood supply to part of the brain is cut off. Blood carries essential nutrients and oxygen to the brain. Without a blood supply, brain cells can be damaged or destroyed and won’t be able to do their job. Because the brain controls everything the body does, damage to the brain will affect body functions. For example, if a stroke damages the part of the brain that controls how limbs move, limb movement will be affected. The brain also controls how we think, learn, feel and communicate. A stroke can also affect these mental processes. Stroke can cause brain tissue to die, and this is called cerebral infarction. An infarct is an area of dead tissue. It can be tiny or affect a larger part of the brain.

There are two main causes of a stroke:

The most common type of stroke is a blockage. This is called an ischaemic stroke, which happens when a clot blocks an artery that carries blood to the brain. It may be caused by:

• a cerebral thrombosis, when a blood clot (thrombus) forms in a main artery to the brain;
• a cerebral embolism, when a blockage caused by a blood clot, air bubble or fat globule (embolism) forms in a blood vessel somewhere else in the body and is carried in the bloodstream to the brain; or
• a blockage in the tiny blood vessels deep within the brain (lacunar stroke).

The second type of stroke is a bleed, when a blood vessel bursts, causing bleeding (haemorrhage) into the brain. This is called a haemorrhagic stroke. It may be caused by:

• an intracerebral haemorrhage, when a blood vessel bursts within the brain; or
• a subarachnoid haemorrhage, when a blood vessel on the surface of the brain bleeds into the area between the brain and the skull (subarachnoid space).

Common Symptons, the first signs that someone has had a stroke are very sudden. Symptons include:

• numbness, weakness or paralysis on one side of the body (signs of this may be a drooping arm, leg or lower eyelid, or a dribbling mouth)
• slurred speech or difficulty finding words or understanding speech
• sudden blurred vision or loss of sight
• confusion or unsteadiness
• a severe headache.

Use the Face–Arm–Speech Test (FAST)
Three simple checks can help you recognise whether someone has had a stroke or mini-stroke (transient ischaemic attack – TIA).
F – Facial weakness: Can the person smile? Has their mouth or an eye drooped?
A – Arm weakness: Can the person raise both arms?
S – Speech problems: Can the person speak clearly and understand what you say?
T – Test these symptoms.