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What is a stroke?

A stroke is the sudden death of brain cells due to a problem with the blood supply. When blood flow to the brain is impaired, oxygen and important nutrients cannot be delivered. The result is abnormal brain function. Blood flow to the brain can be disrupted by either a blockage or rupture of an artery to the brain. There are many causes for a stroke, as shown in the table and discussed below. A stroke is also referred to as a cerebrovascular accident or CVA.

Causes of Stroke

Blockage of artery

• Clogging of arteries within the brain (e.g. lacunar stroke)
• Hardening of the arteries leading to the brain (e.g. carotid artery occlusion)
• Embolism to the brain from the heart or an artery

Rupture of an artery (i.e. hemorrhage)

• Cerebral hemorrhage (bleeding within the brain substance)
• Subarachnoid hemorrhage (bleeding between the brain and the inside of the skull)

What causes a stroke?

The blockage of an artery in the brain by a clot (thrombosis) is the most common cause of a stroke. The part of the brain that is supplied by the clotted blood vessel is then deprived of blood and oxygen. The cells of that part of the brain die as a result. Typically, a clot forms in a small blood vessel within the brain that has been previously narrowed due to the long-term, damaging effects of high blood pressure (hypertension) or diabetes.