Stroke

What is stroke?

A stroke occurs when a blocked vessel or artery prevents blood from getting to part of the brain, or when a vessel or artery bursts and spills blood into the brain. The blood supplies the brain with the oxygen and nutrients it needs to work properly. When part of the brain cannot get the blood it needs, it becomes damaged or dies. The sudden flooding of blood into the brain also can cause damage or death to the brain cells (neurons).

There are two types of stroke:

• Ischemic stroke
  Ischemic stroke happens when an artery carrying blood to the brain becomes blocked and cannot supply enough blood to the brain. Usually, a blood clot causes the blockage. Sometimes the blockage occurs when an artery becomes too narrow for enough blood to pass through it. This narrowing is called stenosis. Stenosis is caused by a buildup of plaque—a mixture of fatty substances, including cholesterol—that forms on the inner walls of the artery.
• Hemorrhagic stroke
  Hemorrhagic stroke occurs when an artery bursts and spills blood into part of the brain. In a healthy brain, the blood remains in the arteries and does not come into contact with neurons. When blood bursts into the brain during a hemorrhagic stroke, the normal flow of blood to the brain is upset, and the blood interferes with the normal chemical balance that neurons need to function.

Transient Ischemic Attack

Sometimes called a mini-stroke, a transient ischemic attack (TIA) starts with the same symptoms of a full stroke but does not progress and cause the damage of a full stroke. A TIA is a warning that a person is at risk for a more serious stroke in the future.¹

Stroke symptoms come on suddenly and include:

• Numbness or weakness of the face, arm, or leg, especially on one side of the body
• Confusion, trouble talking, or trouble understanding what others are saying
• Dizziness, trouble walking, or loss of balance or coordination
• Trouble seeing in one or both eyes
• Sudden severe headache with no known cause

If you believe you or someone you know is having any of these symptoms, do not wait. Call 911 immediately. A person suffering a stroke must receive medications as soon as possible at a hospital to prevent or minimize brain damage.

The symptoms of a transient ischemic attack (TIA) are similar to those of a more serious stroke, but unlike a serious stroke, a TIA usually lasts only a few minutes and goes away within an hour. However, it is impossible to tell the difference between the symptoms of a TIA and a more serious stroke. You should not wait to see if the symptoms go away. Assume that all stroke symptoms signal an emergency.

The National Institute of Neurological Disorders and Stroke (NINDS) provides detailed information about stroke and stroke symptoms.^1,2

Each year, about 795,000 people in the United States have strokes, and of these incidents, 137,000 of the people die. About 610,000 of these cases are first strokes, and 185,000 people who survive a stroke will have another stroke within 5 years.

Ischemic strokes make up about 87% of all strokes. Hemorrhagic strokes make up the remaining 13%.

Stroke is a leading cause of death and disability in the United States. People of all ages and backgrounds can have a stroke. However, some demographic factors put certain people at higher risk of stroke or death from stroke. These include:

• Race/ethnicity. African Americans have almost two times the risk of white people of having a first stroke. Hispanic Americans and American Indian/Alaska Natives are at greater risk than whites are for having a stroke but are at less risk than African Americans. African Americans and Hispanics are more likely than whites to die after having a stroke.
• Age. Stroke risk increases with age. Three-quarters of strokes occur in people ages 65 and older.
• Geography. The highest U.S. death rates from stroke occur in the southeastern United States.
• Gender. Men are more likely than women to have a stroke.

Certain lifestyle factors and conditions also increase the risk for stroke. The most important of these include:

• High blood pressure
• Diabetes
• Heart disease (such as atrial fibrillation)
• Previous stroke or transient ischemic attack
• Cigarette smoking

Additional risk factors include:

• Physical inactivity
• Overweight or obesity
• High cholesterol
• Sickle cell disease
• Drinking too much alcohol
• Family history of stroke
• Drug abuse
• Genetic conditions, such as blood-clotting or vascular disorders (for example, Factor V Leiden or CADASIL)
• Certain medications (such as hormonal birth control pills)
• Being pregnant
• Menopause

Lesser risk factors include:

• Head and neck injuries
• Recent viral or bacterial infections

Amplification of risk occurs when a person has more than one of the risk factors listed above. This means that the combined risk of two or more risk factors is greater than simply adding their effects.^1,2

Ischemic Stroke

Ischemic stroke is caused by a blockage in an artery carrying blood to the brain. The blocked artery cuts off the blood supply to part of the brain. Usually, a blood clot causes the blockage. Sometimes the blockage occurs when an artery becomes too narrow for enough blood to pass through it. This narrowing is called stenosis. Stenosis is caused by a buildup of blood clots and plaque—a mixture of fatty substances, including cholesterol—on the inner walls of the artery.

Problems with blood clotting become more frequent as people age. Certain medications, such as hormonal birth control pills, also can increase the risk of blood clots. Stenosis is caused most commonly by a blood vessel disease called atherosclerosis. In atherosclerosis, plaque builds up on the inner walls of arteries. This causes the artery walls to become thick, hard, and less flexible, and decreases blood flow. The presence of plaque also leads to the formation of blood clots. Eating foods high in saturated fat and cholesterol can make the amount of cholesterol in the body too high. Having high cholesterol can lead to its buildup in plaque in the artery walls. High blood pressure also contributes to atherosclerosis.

Hemorrhagic Stroke

Hemorrhagic stroke is caused by a burst artery that spills blood into part of the brain. In a healthy brain, the blood remains in the arteries and does not come into contact with neurons. When blood bursts into the brain during a hemorrhagic stroke, the normal flow of blood to the brain is upset, and the blood interferes with the normal chemical balance that neurons need to function.

High blood pressure can weaken artery walls and make them more likely to break or burst. Poor blood clotting also can increase the risk of bleeding in a hemorrhagic stroke. Poor blood clotting may be caused by blood disorders or medications that decrease clotting. Another cause of hemorrhagic stroke is abnormalities in the structure of blood vessels that form during brain development.^1,2

Recovery from a stroke may take months or years. Many people who have had a stroke never fully recover.

A person who has had a stroke may have the following temporary or permanent symptoms:

• Inability to move on one side of the body
• Weakness on one side of the body
• Problems with thinking, awareness, attention, learning, judgment, and memory
• Problems understanding or forming speech
• Problems with controlling or expressing emotions
• Numbness or strange sensations
• Pain in the hands and feet that worsens with movement and temperature changes
• Depression

Types of Treatment for Stroke

Stroke treatment includes:

• Emergency treatment
• Preventing another stroke
• Rehabilitation

Emergency Treatment

When a person is able to get to the hospital within a few hours of having a stroke, health care providers will treat a stroke with medications, surgery, or both, depending on the type of stroke.

Medication for Ischemic Stroke

• Thrombolytic agents
  These medications are used to treat an ongoing ischemic stroke caused by a blocked artery. They stop the stroke by dissolving the blood clot that has blocked blood flow to the brain.
• Blood-thinning medications
  These drugs include antiplatelet drugs and anticoagulants and work to prevent blood clotting that causes ischemic stroke.

Surgery

In the case of ischemic stroke, a surgeon can clear out the clogged artery to allow blood to resume flowing to the affected part of the brain. Surgery can also repair structural abnormalities in arteries in the case of hemorrhagic stroke.

Preventing Another Stroke

A patient who has had a stroke may continue taking blood-thinning medications, referred to as blood thinners, to prevent another stroke. Surgery performed to treat a stroke may also help to prevent another stroke. Health care providers will also advise stroke survivors to make lifestyle changes, such as eating a healthy diet, exercising, and treating related medical conditions.

For more information on preventing stroke, see the Other FAQs within the Stroke topic.

Rehabilitation

Stroke is the leading cause of serious adult disability in the United States. Several types of therapies can help a stroke survivor regain some or all of the functions damaged by the stroke. These therapies include:

• Physical therapy
  A physical therapist uses training and exercises to help a patient relearn physical activities such as walking, sitting, standing, and lying down. A special type of physical therapy called constraint-induced movement therapy (CIMT) can improve the use of a weakened or paralyzed arm. CIMT involves training and exercise for the affected arm while the unaffected arm is restrained by a special mitt.
• Occupational therapy
  Occupational therapy involves exercise and training to help a patient relearn daily activities such as eating, drinking, dressing, bathing, cooking, reading, writing, and using a toilet.
• Speech therapy
  Speech therapy helps patients relearn language and speaking, including swallowing.
• Psychological therapy
  Stroke survivors may suffer from depression, anxiety, frustration, and anger. Talk therapy, medications, or both can treat these symptoms.^1,2