What Happens in a Stroke: Types, TIAs and Why Speed Matters

A stroke, sometimes called a brain attack, happens when something blocks the blood supply to part of the brain or when a blood vessel in the brain bursts. Either way, parts of the brain are damaged or die. A stroke can cause lasting brain damage, long-term disability or death, so quick treatment is critical.

What happens in the brain

The brain controls movement, stores memories and is the source of thought, emotion and language. It also runs many body functions, such as breathing and digestion. To work, it needs oxygen, carried to every part by the arteries. If blood flow is blocked, brain cells begin to die within minutes.

The two types

Ischemic stroke. Most strokes are ischemic: blood clots or other particles block the blood vessels leading to the brain. Fatty deposits called plaque can also build up in the vessels and block them.

Hemorrhagic stroke. An artery in the brain leaks blood or bursts, and the leaked blood puts damaging pressure on brain cells. High blood pressure and aneurysms, balloon-like bulges in an artery that can stretch and burst, are among the causes.

Transient ischemic attack

A transient ischemic attack (TIA), sometimes called a "mini-stroke" or "warning stroke," is different from the major types. Blood flow to the brain is blocked only briefly, usually no more than 5 minutes, and, as with ischemic strokes, clots are often the cause. But:

• A TIA is a warning sign of a future stroke.
• It is a medical emergency, just like a major stroke. Call 9-1-1 right away if you have stroke symptoms or see signs in someone else.
• At first there is no way to tell whether symptoms come from a TIA or a major stroke.
• More than a third of people who have a TIA and go untreated have a major stroke within a year, and as many as 10% to 15% have one within 3 months.

Recognizing and treating a TIA lowers the risk of a major stroke: a health care team can find its cause and take steps to prevent one.

Lowering your risk

CDC's work on stroke includes programs on high blood pressure, heart disease and cholesterol, and the Paul Coverdell National Acute Stroke Program. With the CDC Foundation, its Million Hearts initiative runs "Heart-Healthy Steps," encouraging adults 55 and older to schedule medical appointments, get active and eat well, and "Live to the Beat," which helps Black adults pursue heart-healthy lifestyles in ways that work for them.

Sources

• Centers for Disease Control and Prevention, "About Stroke." https://www.cdc.gov/stroke/about/index.html
• CDC, "Signs and Symptoms of Stroke": https://www.cdc.gov/stroke/signs-symptoms/index.html; "Preventing Stroke": https://www.cdc.gov/stroke/prevention/index.html; NINDS Stroke Information: https://www.ninds.nih.gov/Disorders/All-Disorders/Stroke-Information-Page