Overview

An ischemic stroke occurs when the blood supply to part of the brain is blocked or reduced. This prevents brain tissue from getting oxygen and nutrients. Brain cells begin to die in minutes. Another type of stroke is a hemorrhagic stroke. It occurs when a blood vessel in the brain leaks or bursts and causes bleeding in the brain. The blood increases pressure on brain cells and damages them.

A stroke is a medical emergency. It's crucial to get medical treatment right away. Getting emergency medical help quickly can reduce brain damage and other stroke complications.

The good news is that fewer Americans die of stroke now than in the past. Effective treatments also can help prevent disability from stroke.

Symptoms

If you or someone you're with may be having a stroke, pay attention to the time the symptoms began. Some treatments are most effective when given soon after a stroke begins.

Symptoms of stroke include:

  • Trouble speaking and understanding what others are saying. A person having a stroke may be confused, slur words or may not be able to understand speech.
  • Numbness, weakness or paralysis in the face, arm or leg. This often affects just one side of the body. The person can try to raise both arms over the head. If one arm begins to fall, it may be a sign of a stroke. Also, one side of the mouth may droop when trying to smile.
  • Problems seeing in one or both eyes. The person may suddenly have blurred or blackened vision in one or both eyes. Or the person may see double.
  • Headache. A sudden, severe headache may be a symptom of a stroke. Vomiting, dizziness and a change in consciousness may occur with the headache.
  • Trouble walking. Someone having a stroke may stumble or lose balance or coordination.

When to see a doctor

Seek immediate medical attention if you notice any symptoms of a stroke, even if they seem to come and go or they disappear completely. Think "FAST" and do the following:

  • Face. Ask the person to smile. Does one side of the face droop?
  • Arms. Ask the person to raise both arms. Does one arm drift downward? Or is one arm unable to rise?
  • Speech. Ask the person to repeat a simple phrase. Is the person's speech slurred or different from usual?
  • Time. If you see any of these signs, call 911 or emergency medical help right away.

Call 911 or your local emergency number immediately. Don't wait to see if symptoms stop. Every minute counts. The longer a stroke goes untreated, the greater the potential for brain damage and disability.

If you're with someone you suspect is having a stroke, watch the person carefully while waiting for emergency assistance.

Causes

There are two main causes of stroke. An ischemic stroke is caused by a blocked artery in the brain. A hemorrhagic stroke is caused by leaking or bursting of a blood vessel in the brain. Some people may have only a temporary disruption of blood flow to the brain, known as a transient ischemic attack (TIA). A TIA doesn't cause lasting symptoms.

Ischemic stroke

This is the most common type of stroke. It happens when the brain's blood vessels become narrowed or blocked. This causes reduced blood flow, known as ischemia. Blocked or narrowed blood vessels can be caused by fatty deposits that build up in blood vessels. Or they can be caused by blood clots or other debris that travel through the bloodstream, most often from the heart. An ischemic stroke occurs when fatty deposits, blood clots or other debris become lodged in the blood vessels in the brain.

Some early research shows that COVID-19 infection may increase the risk of ischemic stroke, but more study is needed.

Hemorrhagic stroke

Hemorrhagic stroke occurs when a blood vessel in the brain leaks or ruptures. Bleeding inside the brain, known as a brain hemorrhage, can result from many conditions that affect the blood vessels. Factors related to hemorrhagic stroke include:

  • High blood pressure that's not under control.
  • Overtreatment with blood thinners, also known as anticoagulants.
  • Bulges at weak spots in the blood vessel walls, known as aneurysms.
  • Head trauma, such as from a car accident.
  • Protein deposits in blood vessel walls that lead to weakness in the vessel wall. This is known as cerebral amyloid angiopathy.
  • Ischemic stroke that leads to a brain hemorrhage.

A less common cause of bleeding in the brain is the rupture of an arteriovenous malformation (AVM). An AVM is an irregular tangle of thin-walled blood vessels.

Transient ischemic attack

A transient ischemic attack (TIA) is a temporary period of symptoms similar to those of a stroke. But a TIA doesn't cause permanent damage. A TIA is caused by a temporary decrease in blood supply to part of the brain. The decrease may last as little as five minutes. A transient ischemic attack is sometimes known as a ministroke.

A TIA occurs when a blood clot or fatty deposit reduces or blocks blood flow to part of the nervous system.

Seek emergency care even if you think you've had a TIA. It's not possible to tell if you're having a stroke or TIA based only on the symptoms. If you've had a TIA, it means you may have a partially blocked or narrowed artery leading to the brain. Having a TIA increases your risk of having a stroke later.

Risk factors

Many factors can increase the risk of stroke. Potentially treatable stroke risk factors include:

Lifestyle risk factors

  • Being overweight or obese.
  • Physical inactivity.
  • Heavy or binge drinking.
  • Use of illegal drugs such as cocaine and methamphetamine.

Medical risk factors

  • High blood pressure.
  • Cigarette smoking or secondhand smoke exposure.
  • High cholesterol.
  • Diabetes.
  • Obstructive sleep apnea.
  • Cardiovascular disease, including heart failure, heart defects, heart infection or irregular heart rhythm, such as atrial fibrillation.
  • Personal or family history of stroke, heart attack or transient ischemic attack.
  • COVID-19 infection.

Other factors associated with a higher risk of stroke include:

  • Age — People age 55 or older have a higher risk of stroke than do younger people.
  • Race or ethnicity — African American and Hispanic people have a higher risk of stroke than do people of other races or ethnicities.
  • Sex — Men have a higher risk of stroke than do women. Women are usually older when they have strokes, and they're more likely to die of strokes than are men.
  • Hormones — Taking birth control pills or hormone therapies that include estrogen can increase risk.

Complications

A stroke can sometimes cause temporary or permanent disabilities. Complications depend on how long the brain lacks blood flow and which part is affected. Complications may include:

  • Loss of muscle movement, known as paralysis. You may become paralyzed on one side of the body. Or you may lose control of certain muscles, such as those on one side of the face or one arm.
  • Trouble talking or swallowing. A stroke might affect the muscles in the mouth and throat. This can make it hard to talk clearly, swallow or eat. You also may have trouble with language, including speaking or understanding speech, reading or writing.
  • Memory loss or trouble thinking. Many people who have had strokes experience some memory loss. Others may have trouble thinking, reasoning, making judgments and understanding concepts.
  • Emotional symptoms. People who have had strokes may have more trouble controlling their emotions. Or they may develop depression.
  • Pain. Pain, numbness or other feelings may occur in the parts of the body affected by stroke. If a stroke causes you to lose feeling in the left arm, you may develop a tingling sensation in that arm.
  • Changes in behavior and self-care. People who have had strokes may become more withdrawn. They also may need help with grooming and daily chores.

Prevention

You can take steps to prevent a stroke. It's important to know your stroke risk factors and follow the advice of your healthcare professional about healthy lifestyle strategies. If you've had a stroke, these measures might help prevent another stroke. If you have had a transient ischemic attack (TIA), these steps can help lower your risk of a stroke. The follow-up care you receive in the hospital and afterward also may play a role.

Many stroke prevention strategies are the same as strategies to prevent heart disease. In general, healthy lifestyle recommendations include:

  • Control high blood pressure, known as hypertension. This is one of the most important things you can do to reduce your stroke risk. If you've had a stroke, lowering your blood pressure can help prevent a TIA or stroke in the future. Healthy lifestyle changes and medicines often are used to treat high blood pressure.
  • Lower the amount of cholesterol and saturated fat in your diet. Eating less cholesterol and fat, especially saturated fats and trans fats, may reduce buildup in the arteries. If you can't control your cholesterol through dietary changes alone, you may need a cholesterol-lowering medicine.
  • Quit tobacco use. Smoking raises the risk of stroke for smokers and nonsmokers exposed to secondhand smoke. Quitting lowers your risk of stroke.
  • Manage diabetes. Diet, exercise and losing weight can help you keep your blood sugar in a healthy range. If lifestyle factors aren't enough to control blood sugar, you may be prescribed diabetes medicine.
  • Maintain a healthy weight. Being overweight contributes to other stroke risk factors, such as high blood pressure, cardiovascular disease and diabetes.
  • Eat a diet rich in fruits and vegetables. Eating five or more servings of fruits or vegetables every day may reduce the risk of stroke. The Mediterranean diet, which emphasizes olive oil, fruit, nuts, vegetables and whole grains, may be helpful.
  • Exercise regularly. Aerobic exercise reduces the risk of stroke in many ways. Exercise can lower blood pressure, increase the levels of good cholesterol, and improve the overall health of the blood vessels and heart. It also helps you lose weight, control diabetes and reduce stress. Gradually work up to at least 30 minutes of moderate physical activity on most or all days of the week. The American Heart association recommends getting 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous aerobic activity a week. Moderate intensity activities can include walking, jogging, swimming and bicycling.
  • Drink alcohol in moderation, if at all. Drinking large amounts of alcohol increases the risk of high blood pressure, ischemic strokes and hemorrhagic strokes. Alcohol also may interact with other medicines you're taking. However, drinking small to moderate amounts of alcohol may help prevent ischemic stroke and decrease the blood's clotting tendency. A small to moderate amount is about one drink a day. Talk to your healthcare professional about what's appropriate for you.
  • Treat obstructive sleep apnea (OSA). OSA is a sleep disorder that causes you to stop breathing for short periods several times during sleep. Your healthcare professional may recommend a sleep study if you have symptoms of OSA. Treatment includes a device that delivers positive airway pressure through a mask to keep the airway open while you sleep.
  • Don't use illicit drugs. Certain illicit drugs such as cocaine and methamphetamine are established risk factors for a TIA or a stroke.

Preventive medicines

If you have had an ischemic stroke, you may need medicines to help lower your risk of having another stroke. If you have had a TIA, medicines can lower your risk of having a stroke in the future. These medicines may include:

  • Anti-platelet drugs. Platelets are cells in the blood that form clots. Anti-platelet medicines make these cells less sticky and less likely to clot. The most commonly used anti-platelet medicine is aspirin. Your healthcare professional can recommend the right dose of aspirin for you.

    If you've had a TIA or minor stroke, you may take both an aspirin and an anti-platelet medicine such as clopidogrel (Plavix). These medicines may be prescribed for a period of time to reduce the risk of another stroke. If you can't take aspirin, you may be prescribed clopidogrel alone. Ticagrelor (Brilinta) is another anti-platelet medicine that can be used for stroke prevention.

  • Blooding-thinning medicines, known as anticoagulants. These medicines reduce blood clotting. Heparin is a fast-acting anticoagulant that may be used short-term in the hospital.

    Slower acting warfarin (Jantoven) may be used over a longer term. Warfarin is a powerful blood-thinning medicine, so you need to take it exactly as directed and watch for side effects. You also need regular blood tests to monitor warfarin's effects.

    Several newer blood-thinning medicines are available to prevent strokes in people who have a high risk. These medicines include dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis) and edoxaban (Savaysa). They work faster than warfarin and usually don't require regular blood tests or monitoring by your healthcare professional. These medicines also are associated with a lower risk of bleeding complications compared to warfarin.

By Mayo Clinic Staff