stroke

A stroke is kind of a strange word for a health problem. You probably think of a stroke as something good. You might stroke your dog's fur. Or maybe someone has told you: "That's a stroke of good luck." But if someone has a stroke it means something has stopped the normal blood flow to the brain. Strokes usually happen to older people, like grandparents. Kids don't typically get them.
Blood is circulating through your body all the time in tubes called arteries and veins. Usually, these blood vessels work fine and there's no problem. That's important because blood carries oxygen to all the cells in your body. And without oxygen, the cells would die.
A stroke can happen if something keeps the blood from flowing as it should. A person might have a clogged blood vessel, so the blood can't get through. Or a blood vessel may burst and a part of the brain is suddenly flooded with blood. Either way, with a stroke, brain cells die because they don't get the oxygen they need.
There are two main types of strokes:
Ischemic (say: iss-kee-mik) strokes happen when a blood vessel going to the brain becomes blocked, and the blood can't get where it's supposed to be. This type of stroke is the most common. A blood clot - a clump of blood that sticks together - is usually to blame for ischemic strokes. They can also happen when arteries become narrow and clogged with plaque. Plaque is a mix of cholestero and other fatty stuff that sticks to the walls of blood vessels.
Hemorrhagic (say: heh-muh-rah-jik) strokes happen when a weak or thin blood vessel bursts and the blood spills out, killing brain cells and affecting how the brain works. High blood pressure can weaken the walls of vessels and make a hemorrhagic stroke much more likely.
There are also "mini strokes" called transient ischemic attacks (TIAs). These are not full-blown stokes because the blood flow is only cut off for a short amount of time and they don't cause the same kind of damage right away, however, they are a warning sign that something is wrong and that a real stroke may be on its way. Strokes are serious. People who have strokes can get really sick, have brain damage, or die. But many people recover from strokes, especially if they know the warning signs and can get help quickly.