A stroke occurs when blood supply to a part of the brain is blocked or reduced. This can be due to a blockage in a blood vessel, or a ruptured blood vessel.p>

Stroke is a leading cause of disability and death in the United States. It’s the third leading cause of death in women, and the fifth leading cause of death in men, according to the Centers for Disease Control and Prevention (CDC).

Within the first 30 days, 1 in 8 strokes is fatal and 1 in 4 strokes is fatal within the first year, according to the Stroke Association. The CDC also estimates that strokes kill about 140,000 Americans each year.

Medical emergency

A stroke is a medical emergency. If you think you or someone else is having a stroke, call 911 or your local emergency services immediately.

While strokes are a leading cause of death, not all strokes are fatal.

How you’re affected by a stroke depends on its location, it’s severity, and how fast you receive treatment.

The brain requires a constant supply of blood and oxygen. When there’s an interruption of blood flow, brain cells begin to die within minutes.

When brain cells die, so does brain function. This can lead to permanent disability if you’re unable to do activities controlled by this part of the brain. A stroke can affect language, moods, vision, and movement.

Death occurs when the brain is deprived of oxygen and blood for too long. Early treatment raises the chance of surviving a stroke, and can result in little or no disability.

Strokes are classified into three main categories.

Ischemic strokes

An ischemic stroke is the most common type, making up about 87 percent of all strokes. It’s caused by a blockage in an artery supplying the brain with blood. These types of stroke include thrombotic and embolic strokes.

  • Thrombotic. These involve a blood clot forming within the blood vessels inside the brain. Thrombotic strokes are more common in older people and often due to high cholesterol or diabetes. These strokes can occur suddenly or gradually over hours or days.
  • Embolic stroke. These involve a blood clot forming outside of the brain. The clot travels to a blood vessel in the brain, causing a blockage. These strokes are often due to heart disease and can occur suddenly.

Hemorrhagic strokes

With this type of stroke, a blood vessel in the brain ruptures or leaks. Hemorrhagic strokes can be caused by high blood pressure or an aneurysm.

Hemorrhagic strokes account for about 40 percent of all stroke deaths, according to the National Stroke Association.

Two types of hemorrhagic strokes include:

  • Intracerebral. These strokes are caused by a ruptured artery in the brain.
  • Subarachnoid. These involve a rupture or leak that causes bleeding in the space between the brain and the tissue that covers the brain.

Transient ischemic attack (TIA)

Also called a ministroke, a TIA is a short interruption of blood flow to a part of the brain. The interruption is brief because the blood clot dissolves quickly on its own.

TIAs cause traditional stroke-like symptoms, but symptoms typically disappear within 24 hours and don’t cause permanent brain damage.

Having a TIA increases the risk of an ischemic or hemorrhagic stroke. In fact, about 40 percent of people who have a ministroke will have an actual stroke later.

It’s estimated that about 14 percent of all strokes occur during sleep, with some people visiting the emergency room after waking up with stroke symptoms.

People who have strokes while asleep are at risk of death because they’re unable to benefit from treatment early. It’s unknown how many people die in their sleep from a stroke each year.

For those who survive having a stroke while asleep, there’s a risk of permanent disability due to delayed treatment. Clot-busting drugs administered within the first three hours of an ischemic stroke can reduce brain damage and disability.

In fact, those who arrive at the hospital within three hours of the first stroke symptom have less disability three months after a stroke, compared to those who don’t receive immediate care.

The problem, however, is that a person waking up with stroke symptoms can’t always pinpoint when symptoms began. So they might not be eligible for clot-busting drugs.

Every minute counts, so recognizing the signs and symptoms early can potentially save a life and prevent permanent brain damage.

Some people have a severe headache, while others don’t have any pain. Other symptoms include:

  • numbness or weakness in the face, or on one or both sides of the body
  • difficulty speaking or understanding speech
  • inability to see out of one or both eyes
  • difficulty walking, loss of balance, or loss of coordination

A stoke can happen to anyone. Common causes and risk factors include:

  • being overweight or having obesity
  • lack of physical activity
  • high blood pressure
  • high cholesterol
  • diabetes
  • heart disease, including irregular heart rhythm
  • family history of stroke
  • having a previous stroke or ministroke
  • sleep apnea
  • smoking

The goal of stroke treatment is to restore blood flow to the brain and control any bleeding in the brain.

You’ll receive a brain scan upon arrival at the hospital to determine the type of stroke. Medication can help dissolve a clot and restore blood flow if you arrive at the hospital within three hours of the onset of an ischemic stroke.

Surgery can remove a blood clot that doesn’t dissolve, or remove plaque in a blocked artery.

If you have a hemorrhagic stroke, surgery can repair a weak or damaged blood vessel, remove blood from the brain, and reduce pressure in the brain.

After you’re stabilized, treatment involves recovery and rehabilitation. Depending on the severity of brain damage, you may need occupational therapy, physical therapy, and speech therapy to help you regain lost abilities.

Up to 80 percent of strokes are preventable with a healthy lifestyle and treatment of certain medical conditions. Tips to prevent a stroke include:

Stroke is a leading cause of death and disability, but you can protect yourself. Prevention starts with knowing the risks, and then taking steps to improve your overall health.

It’s also important to recognize the early signs so that you can receive prompt treatment in the event of a stroke.