Overview

Embolic stroke is a type of ischemic stroke, which is a stroke that happens when blood flow to part of the brain is blocked. In embolic stroke, the blockage is caused by material that forms somewhere else in the body, travels in the bloodstream and then blocks an artery in the brain. This traveling material is called an embolus. A brain embolism, also called a cerebral embolism, refers to this kind of blockage.

Embolic stroke is different from thrombotic stroke. In embolic stroke, a clot or other material forms somewhere other than the blocked brain artery and then travels to it. In thrombotic stroke, a clot forms in the blood vessel at the site of the blockage itself. It does not travel.

Healthcare professionals also may use the term cardioembolic stroke. This means the embolus came from the heart. Common heart-related sources include atrial fibrillation and blood clots in the heart.

Some ischemic strokes are called cryptogenic strokes because the cause is still not found after the usual evaluation. A related term is embolic stroke of undetermined source, also called ESUS. This means the stroke pattern suggests an embolic cause, but initial testing does not show a major narrowed artery or a clear high-risk heart source.

Embolic stroke is serious. It can cause disability and can be deadly. Early recognition of stroke symptoms and fast treatment improve the chances of survival and may reduce complications.

Symptoms

If you or someone you're with may be having an embolic stroke, pay close attention to when the symptoms began, or when the person was last known to be well. Some treatments work best when given as soon as possible after stroke symptoms start.

Symptoms of an embolic stroke are similar to other types of stroke. Symptoms usually begin suddenly. They can 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.

Can you catch a brain embolism early?

Usually embolic strokes happen very quickly. Occasionally symptoms may develop over hours. Sometimes strokelike symptoms last only a short time and then go away. This can be a transient ischemic attack, also called a TIA. A TIA is a brief blockage of blood flow to the brain.

Both embolic stroke and TIAs are medical emergencies. A TIA can be a warning sign of stroke. Getting evaluated quickly may help you lower the risk of a stroke. And if you're already having a stroke, getting treatment quickly may help prevent brain damage and other complications.

When to seek emergency care

Get emergency help right away if you notice possible stroke symptoms, even if they go away.

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 down? Or is one not able to rise?
  • Speech — Ask the person to repeat a simple sentence. Is speech slurred or different than usual?
  • Time — Call 911 or emergency medical help right away if you see any of these signs.

Causes

Embolic stroke happens when a blood clot or other material forms an embolus that travels through the bloodstream and blocks an artery in the brain. Clots often come from the heart. This is called cardioembolic stroke. Clots also can come from the aorta or another blood vessel. Less common types of emboli include fat and air.

Blood clots

Conditions that cause blood clots can lead to embolic stroke. Examples include:

  • Atrial fibrillation (AF). This irregular heart rhythm is a common cause of cardioembolic stroke, where the clot travels from the heart to the brain.
  • Other heart conditions. Cardioembolic stroke also can be caused by other heart conditions that cause clots. These include recent heart attack, endocarditis caused by an infection, valve disease, clots in the heart, mechanical heart valves and some heart tumors.
  • Atherosclerosis, a buildup of plaque on artery walls. Plaques made of fats, cholesterol and other substances can build up in large arteries. These plaques can cause a clot to form. Or material can break off from the plaques and travel to the brain.
  • Blood-clotting conditions. These include conditions such as antiphospholipid syndrome, factor V Leiden and hyperhomocysteinemia.
  • Anatomy. When born, babies have a small opening in the heart that usually closes after birth. That opening is called a patent foramen ovale (PFO). In some people, the PFO does not close as usual. When this happens, it makes it possible for a clot in a vein to pass from the right side of the heart to the left side of the heart. From there, the clot can enter an artery that sends blood to the brain. When this is the cause, the embolism is called a paradoxical embolism.
  • Infections. Sometimes infections can cause blood clots. Examples include COVID-19 and sepsis.

Other types of emboli

Though less common, other materials also can cause embolic stroke. These include:

  • Fat embolism. This happens when fat droplets enter the bloodstream and travel to the brain. This can happen with some bone fractures, orthopedic procedures or when there's severe trauma to large fat deposits.
  • Air embolism. This happens when air enters the bloodstream and travels to the brain. This is usually a complication of a medical procedure, such as a cardiopulmonary bypass, central venous catheter removal or cardiac catheterization.

When the cause cannot be found

You may hear certain terms if the stroke looks to be caused by an embolism but the source cannot be found. These terms include:

  • Cryptogenic stroke. This is a broad term for any ischemic stroke where the cause is not known even after the usual testing.
  • Embolic stroke of undetermined source (ESUS). This is a type of cryptogenic stroke. It means an embolism is suspected as the cause, but the cause of the embolism can't be identified after standard testing. You might sometimes hear this called a cryptogenic embolism or cryptogenic emboli.

Risk factors

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

Lifestyle risk factors

  • Being overweight or obese.
  • Physical inactivity.
  • Cigarette smoking or secondhand smoke exposure.
  • Heavy or binge drinking.
  • Use of illegal drugs such as cocaine.

Medical risk factors

There also are some risk factors for stroke that you can't change. For example, age is another risk factor. Older people have a higher risk of stroke than do younger people.

Complications

Complications of embolic stroke can be temporary or permanent. They depend on how long the brain goes without blood flow and which part of the brain is affected.

Possible complications include:

  • Loss of muscle movement, known as paralysis. You may lose movement or muscle control on one side of the body or in part of the face, arm or leg.
  • 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 and thinking problems. Some people have trouble with memory, reasoning, judgment or understanding.
  • Emotional and mood changes. Stroke can make it harder to control emotions. Depression also can happen after stroke.
  • Pneumonia and other medical concerns during recovery. Trouble swallowing can raise the risk of inhaling food or liquid into the lungs. This is called aspiration and can lead to pneumonia. Other complications during recovery can include trouble breathing. This can happen as a result of aspiration or when the stroke directly affects the parts of the brain that control breathing. Skin breakdown and pressure sores also can happen if the stroke affects the ability to move and be mobile.
  • Another stroke. Another stroke can happen after an embolic stroke.

Some people recover well after stroke. Others may have lasting disability or need help with daily activities.

Prevention

You cannot prevent every embolic stroke. But you may be able to lower your risk by managing or treating common causes of embolism. If you've already had an embolic stroke or a TIA, these measures also might be recommended to help prevent another stroke.

Manage conditions that increase risk

  • High blood pressure. Lowering blood pressure is one of the most important ways to reduce stroke risk. Healthy lifestyle changes and medicines often are used to treat high blood pressure.
  • Diabetes. Diet, exercise and maintaining a healthy weight can help you keep your blood sugar in a healthy range. This is part of lowering the risk of stroke. If lifestyle factors aren't enough to manage blood sugar, you may be prescribed diabetes medicine.
  • High cholesterol and atherosclerosis. Lifestyle changes and medicines, such as statins, can help manage cholesterol. They also can help reduce the buildup of plaques in the arteries called atherosclerosis. Sometimes, atherosclerosis may need treatment with surgery or other procedures on the heart or blood vessels.
  • 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.

Maintain a healthy lifestyle

  • 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 and secondhand smoke raise stroke risk. Quitting lowers your risk of stroke.
  • Exercise regularly. Aerobic exercise can help lower stroke risk. It 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.
  • Maintain a healthy weight. Being overweight raises stroke risk and can worsen other 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.
  • Drink alcohol in moderation, if at all. Large amounts of alcohol increase the risk of high blood pressure and ischemic strokes. Alcohol also may interact with other medicines. But 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.
  • Do not use illicit drugs. Certain illicit drugs such as cocaine are risk factors for a TIA or a stroke.

Medicines that can help prevent stroke

  • Antiplatelet medicines. Platelets are cells in the blood that form clots. Antiplatelet medicines make these cells less sticky and less likely to clot. A commonly used 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. They often are used to help prevent a first stroke or another stroke when there's a clotting risk related to the heart, such as with atrial fibrillation.

    Slower acting warfarin (Jantoven) may be used longer term, for example to reduce the risk of clots from a mechanical heart valve. 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. Because of the increased risk of bleeding and the need for monitoring, many choose newer blood-thinning medicines.

    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