A stroke occurs when the body stops supplying blood to the brain. Ischemic stroke is the most common type of stroke, and it develops due to a blockage in the arteries around the brain.

According to the Centers for Disease Control and Prevention (CDC), strokes are the fifth leading cause of death in the United States.

Around 87% of all strokes are ischemic strokes.

In this article, we explain the causes of ischemic stroke, how to recognize when one is occurring, and ways to prevent and treat it.

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Ischemic stroke is the most common type, and early intervention is vital.

An ischemic stroke occurs due to atherosclerosis, which causes fatty deposits and a buildup of cholesterol plaque in the blood vessels.

When too much plaque collects in one spot, it can block the blood flow to vital organs.

A blood clot may stick to a plaque buildup while passing through the blood vessels, which also creates a blockage.

The neck contains carotid arteries, which are blood vessels that supply blood to the brain. If plaque blocks a carotid artery (carotid artery disease), a stroke might occur.

Atherosclerosis is largely symptomless. Therefore, many people do not know they have atherosclerosis until they have a stroke or experience the other effects of blocked arteries near different organs, such as a heart attack.

The major risk factors for an ischemic stroke and carotid artery disease are the same.

They include:

  • High blood pressure: This is the primary cause of stroke.
  • Diabetes: People with diabetes are four times more likely to have carotid artery disease.
  • Atherosclerosis or carotid artery disease: Having either of these conditions or a family history of these conditions can increase the risk of stroke.
  • Atrial fibrillation (Afib): Approximately 15% of strokes occur in people who have Afib.
  • Cholesterol levels: High levels of "bad" low-density lipoprotein (LDL) cholesterol or low levels of "good" high-density lipoprotein (HDL) cholesterol can contribute to plaque buildup in the arteries.
  • A sedentary lifestyle: A lack of physical activity can lead to high blood pressure, high cholesterol, and being overweight. These increase the risk of arterial plaque buildup.
  • Being overweight or obese.
  • An unhealthful diet: Consuming too many saturated or trans fats and foods high in cholesterol, sodium, and sugar can lead to diabetes, plaque buildup, high blood pressure, and high cholesterol.
  • Being over 55 years of age: The risk of stroke increases in people aged over 55 years and increases with each additional decade of life.

People who have had a previous transient ischemic attack (TIA) are also at risk of ischemic stroke. A TIA, or "mini-stroke," is a temporary blockage of blood to the brain.

Symptoms of a TIA are the same as those of an ischemic stroke, but they usually last less than 5 minutes and do not cause permanent damage. About one-third of all people who have a TIA will experience a more severe stroke within 1 year.

Smoking and ischemic stroke

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Smoking increases the risk of ischemic stroke in several ways.

Smoking is another risk factor that contributes to ischemic stroke by:

  • increasing plaque buildup in the blood vessels
  • making blood more likely to clot
  • pushing up cholesterol levels
  • narrowing blood vessels
  • damaging the lining of blood vessels

All of these factors also put someone at higher risk of a stroke.

An interruption of blood supply to the brain causes all ischemic strokes. However, ischemic strokes can start in different areas of the body and may occur due to various types of blockage:

  • Embolic stroke: This occurs when a blood clot, piece of plaque, or another object forms in a different part of the body and travels to the brain's blood vessels.
  • Thrombotic stroke: This type of stroke occurs when a thrombus or clot forms inside a blood vessel in the brain.

Learn about other types of stroke here.

Strokes can be life-threatening, so it is important to seek medical care immediately if symptoms appear.

Ischemic stroke symptoms often affect one side of the body and develop quickly.

The American Stroke Association (ASA) recommend that people remember F.A.S.T. This stands for:

F = Face drooping: People may notice one side of the face drooping or feeling numb. Another person can check for this symptom by asking the person to smile or stick out their tongue.

If their smile is uneven, or their tongue moves to one side of the mouth instead of the middle, this could be a warning sign for ischemic stroke.

A = Arm weakness: Being unable to lift one arm or feeling weakness or numbness in one arm may suggest that an ischemic stroke is occurring.

S = Speech problems: These might include being unable to speak or repeat a sentence clearly.

T = Time to call 9-1-1: Contact emergency services immediately on noting the other indicators of ischemic stroke.

Beyond F.A.S.T., a stroke may also cause the following symptoms to develop suddenly:

  • difficulty walking
  • dizziness
  • falling without an identifiable cause
  • a sudden inability to understand speech
  • confusion
  • rapidly developing vision problems
  • a severe headache without an apparent cause

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An emergency medical team will administer clot busting medication.

The brain relies upon a constant supply of oxygen-rich blood, so a blockage that lasts for just a few minutes can begin to damage and destroy brain cells.

With a stroke, every minute counts, and prompt treatment is essential for survival.

A person who is experiencing an ischemic stroke requires emergency treatment, which may include the following:

Medication: A member of the emergency team will inject tissue plasminogen activator (tPA), which is a clot busting medication, through a vein in the arm.

Doctors must administer this medication within 4 hours from the beginning of stroke symptoms to have the desired effect. The chances of a positive outcome improve depending on how soon a person receives a shot of tPA.

Surgery to remove the clot: After a shot of tPA, a person experiencing an ischemic stroke may undergo a mechanical thrombectomy.

This involves removing the clot with a catheter, and doctors must carry out this procedure within 6 hours of symptoms starting.

Even people with risk factors or a history of stroke can take steps to improve cardiovascular health and reduce the risk of ischemic stroke.

The following measures can help prevent a stroke and improve overall health:

  • Having regular check-ups: High blood pressure and cholesterol do not have visible symptoms. Regular health tests are the only way to know if these are present. Blood tests and health checkups can help detect these problems early and allow for timely treatment.
  • Getting regular exercise: An active lifestyle reduces the risk of diabetes, high blood pressure, high cholesterol, and other conditions that increase the risk of ischemic stroke.
  • Following a heart-healthy diet: A diet should be low in "bad" fats, such as saturated and trans fats. People should also limit their sodium intake. Eating more fruits, vegetables, whole grains, healthful fats, and lean proteins can help them preserve cardiovascular health.
  • Managing body weight: If a person is overweight or has obesity, reaching a healthy body weight can bring down their risk for stroke.
  • Avoiding first-hand or secondary smoking: Smoking and inhaling smoke from others can cause damage to blood vessels and increase the risk of stroke-related health problems.
  • Being aware of family history: Always discuss a family history of stroke or TIA with a doctor.
  • Taking daily aspirin: A doctor may recommend that a person who has an especially high risk of a heart attack or stroke and a low risk of bleeding take a daily aspirin. Guidelines no longer recommend the widespread use of aspirin for this purpose, due to the high risk of bleeding.
  • Getting enough sleep and managing stress: Getting 7–8 hours of sleep and taking steps to reduce stress, such as relaxation techniques, may help to prevent stroke and improve overall health and well-being.

A stroke can be frightening and may occur in a person who seems to be in good health.

Knowing the warning signs and seeking emergency medical care are the most important ways to improve a person's outlook after a stroke.

If a stroke is happening to a friend or family member, people should not drive them to a hospital. Instead, they should call an ambulance, so that paramedics can provide medical care as quickly as possible.

An ambulance can also take the person to the hospital that can provide the best stroke care, which is not always the closest facility.

A rapid response significantly improves a person's chances of survival after a stroke.

Q:

Is ischemic stroke the most dangerous type?

A:

Not always — it depends on how much of the brain is deprived of oxygen. “Big” strokes, i.e. strokes that cause lack of blood flow to a large part of the brain can be life-threatening.

Seunggu Han, MD Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.