Overview

A stroke is a medical emergency that occurs when blood supply to the brain is blocked or when a blood vessel bleeds in the brain. When blood flow becomes blocked or reduced, it's known as an ischemic stroke. 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.

It's crucial to get medical treatment right away for a stroke. Emergency medical help can reduce brain damage and other stroke complications.

The good news is that effective treatments can help prevent disability from stroke.

Symptoms

It's important to be able to spot the symptoms of a stroke. If you or someone you're with may be having a stroke, try to note the time the symptoms begin. Tell this time to emergency responders. 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. When trying to raise both arms overhead, one arm may fall. Also, one side of the mouth may droop when trying to smile.
  • Problems seeing in one or both eyes. A stroke can cause blurry or blackened vision in one or both eyes. It also can cause double vision.
  • 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 medical attention right away if you notice any symptoms of a stroke, even if they seem to come and go or if they go away completely. Think F.A.S.T. 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 not able 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.

It's essential to call 911 or your local emergency number right away. Don't wait to see if symptoms stop. Every minute counts. The longer a stroke is not treated, the greater the chance of brain damage and disability.

If you're with someone you think 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 a blood vessel in the brain leaking or bursting. 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

Ischemic stroke 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.

Some early research shows that coronavirus disease 2019 (COVID-19) infection may be linked to 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 brief period of symptoms similar to those of a stroke. A TIA is caused by a temporary decrease in blood supply to part of the brain. This can happen because of a blood clot or fatty deposit. The decrease in blood supply may last as little as five minutes and doesn't cause permanent damage. A TIA is sometimes known as a ministroke.

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. 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

  • Physical inactivity.
  • Cigarette smoking or secondhand smoke exposure.
  • Heavy or binge drinking.
  • Use of illegal drugs, such as cocaine and methamphetamine.

Medical risk factors

  • Having obesity.
  • High blood pressure.
  • 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 risk factors

Other factors associated with a higher risk of stroke include:

  • Being age 55 or older.
  • Being of African American or Hispanic descent.
  • Being assigned male at birth.
  • Taking hormone therapy that includes estrogen.

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. Only one side of the face or one arm may be affected.
  • 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 with emotions or 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.
  • 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 can help 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-intensity aerobic activity a week. Moderate-intensity activities can include walking, jogging, swimming and bicycling.
  • 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.

These steps are also important for lowering the risk of stroke:

  • Quit tobacco use. Smoking and exposure to secondhand smoke raises the risk of stroke. Quitting lowers this risk.
  • 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. But 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 right for you.
  • Don't use illicit drugs. Certain illicit drugs such as cocaine and methamphetamine are known 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:

  • Antiplatelet drugs. Platelets are cells in the blood that form clots. Antiplatelet medicines make these cells less sticky and less likely to clot. The most common antiplatelet 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 antiplatelet 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 antiplatelet 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 with warfarin.

By Mayo Clinic Staff