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The term stroke is a bit misleading. It's better known by doctors as a cerebrovascular accident or CVA. Cerebral means ‘of the brain' and vascular refers to arteries and veins. In a stroke, theres a disruption of the normal blood supply to the brain (either a blockage or a bleed) due to disease of the arteries in the brain. And what we call 'stroke' is a consequence of the damage to the brain that follows.

Some doctors argue it should be called a brain attack in the same way that a heart attack is caused by disease of the arteries in the heart. Now, the brain controls many different functions – movement, speech, vision, thinking, consciousness, to name a few.

Damage to the brain from a stroke can disrupt some or even all of these functions, depending where the damage occurs. That's why a stroke varies in its effects and in its severity from person to person. Nearly 50,000 Australians every year suffer a stroke. It is our third largest killer after cancer and heart disease. But many people recover and with rehabilitation can resume a useful life.

What happens?

Stroke is caused by disease of the arteries inside and on the outside surface of the brain, rather than of brain tissue itself. It's almost always caused by a condition called atherosclerosis, in which there's a build-up of fatty deposits in the lining of the walls of arteries.

These fatty deposits – called plaques – can thicken, calcify and narrow the arteries, constricting the flow of blood until brain tissue normally supplied by that artery is starve of oxygen and dies. This is called an 'ischaemic' stroke (ischaemic means lack of oxygen).

Sometimes a blood clot (called a thrombus) forms at the site of the plaque, causing a sudden abrupt blockage. This is called a thrombotic stroke. Sometimes the blood clot originates not in the brain but somewhere else, for example a diseased heart valve or a diseased heart which has an irregular beat called atrial fibrillation. The clot may dislodge and travel in the blood up to the arteries of the brain and block and artery, causing a stroke. This 'travelling clot' is called an embolus.

Sometimes an artery in the brain can so become damaged by atherosclerosis that it weakens and balloons out. This balloon is called an aneurysm. It can burst, especially if the blood pressure is high at the same time. Blood from the burst aneurysm escapes into the brain tissue and damages and destroys it. This type of stroke is called a haemorrhagic stroke. It's less common than the other types, but is often severe.