A stroke, or “brain attack,” occurs when a blood vessel in the brain becomes blocked or bursts.

The brain cannot store oxygen, so it relies on a network of blood vessels to provide it with blood that is rich in oxygen. A stroke results in a lack of blood supply, causing surrounding nerve cells to be cut off from their supply of nutrients and oxygen. When tissue is cut off from its supply of oxygen for more than three to four minutes, it begins to die.

Strokes can appear as hemorrhagic strokes, ischemic strokes or transient ischemic attacks.

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