Brain cells need a constant supply of oxygen and nutrients. They are delivered by a network of blood vessels that reach every part of the brain. When something cuts off that supply, brain cells downstream begin to die. The injury that follows is called a stroke.

Most strokes strike when a blood clot becomes lodged in one of the brain's arteries, blocking blood flow. In some cases, the clot forms inside the artery, usually because a cholesterol-filled plaque inside the artery breaks open. This is called a thrombotic stroke. In other cases, a blood clot or a solid mass of debris that originates elsewhere travels to the brain, where it blocks a brain artery. This is called an embolic stroke. A third type of stroke, hemorrhagic stroke, occurs when a blood vessel in the brain bursts.

Since different areas of the brain are responsible for different functions, symptoms of stroke vary. They can be changes in sensation, movement, sight, speech, balance, and coordination. Sometimes a stroke is preceded by one or more transient ischemic attacks (TIAs). These are brief episodes of stroke-like symptoms that last for a few minutes — or possibly up to 24 hours — but that go away on their own.

If you think that you, or someone you are with, is having a stroke, call 911 right away. The sooner you call, the sooner treatment can begin — "time is brain," as emergency room doctors say. The type of treatment depends on the type of stroke that has occurred. If the brain's blood supply is restored quickly and completely, a full recovery with little or no disability is possible. The more widespread the damage, and the greater delay of treatment, the more severe and long-lasting the damage.

Recovery after a stroke depends on how well healthy areas of the brain take over duties that had been performed by the damaged brain tissue. To some extent, especially in children and young adults, recovery is possible because of the brain's ability to compensate for damage in one area by working harder in another — by relying on alternate wiring for some functions or by rewiring around the injured site. When such rewiring isn't possible, rehabilitation techniques can help the brain recover function.

Stroke Articles

One in 10 men may be taking aspirin unnecessarily

A study found that one in 10 people who take protective aspirin may not really qualify, because the risk of heart attacks and strokes wasn't great enough to justify the risk of unwanted bleeding associated with aspirin. (Locked) More »

Can memory woes foretell a stroke?

Well-educated people who report memory problems may face a higher risk of stroke. Education helps people develop more widespread brain networks, which enables them to compensate for damage from tiny, unnoticed strokes. But these small strokes can foretell larger, more serious strokes. Because educated people are more likely to notice subtle memory changes, their memory complaints are a more reliable predictor of stroke than memory complaints in less-educated people. Controlling blood pressure and exercising regularly are important ways to prevent strokes.  (Locked) More »

Reduce your risk of silent strokes

Silent strokes occur without symptoms, yet have the potential to severely impair memory and brain health. A silent stroke is usually the result of a clot forming in a tiny artery supplying blood to a “silent” part of the brain. These areas don’t control vital functions, such as speech or walking, which is why the interruption of blood flow doesn’t result in obvious symptoms. But a person can experience multiple silent strokes, which can start to reveal themselves through memory lapses and mood changes. (Locked) More »

Carotid artery disease

The brain requires a constant supply of oxygen. Much of it comes from oxygen-rich blood delivered by the carotid arteries. These travel from the body's main artery, the aorta, up either side of the neck (where their pulses can be felt on either side of the trachea, or windpipe), and into the brain. A cholesterol-laden plaque can narrow a carotid artery. This is called carotid artery disease. A large plaque can slow blood flow to the brain. Even more worrisome is if a plaque breaks open. The blood clot that forms to seal the break can travel to the brain, causing a transient ischemic attack (mini-stroke) or stroke. More »

Ask the doctor: When a stroke has no immediate symptoms

A silent stroke happens when a clot blocks a blood vessel to part of the brain that doesn’t control any vital functions. Silent strokes don’t cause any noticeable symptoms, but they may lead to thinking and memory problems if several occur over time.  (Locked) More »

Atherosclerosis: symptoms and treatments

Every organ and tissue in the body needs a supply of fresh, oxygen-rich blood. That blood is delivered to all parts of the body through blood vessels called arteries. A healthy artery is like a clean pipe: It has a smooth lining and is free of blockages that interfere with blood flow. Atherosclerosis is the buildup of cholesterol-filled deposits called plaque on the inner walls of arteries. Plaque narrows the vessels and slows down blood flow. Atherosclerosis can occur in any artery in the body, from those nourishing the heart (coronary arteries) to those supplying the brain, intestines, kidneys, and legs. Atherosclerosis begins as microscopic damage to the inner lining of an artery wall. Many forces can cause this damage, including high blood pressure, cigarette smoke, diabetes, high cholesterol, conditions that cause blood to clot more easily, drugs such as cocaine and androgens, and possibly infections of the inner linings of the arteries. More »