Stephen J. Schueler, M.D.

Brain Attack Types

There are two main types of stroke:

  • Ischemic strokes:
    • Caused by a blood clot that blocks an artery in the brain
    • The clot cuts off the blood flow to an area in the brain
  • Hemorrhagic strokes:
    • Caused by bleeding from an artery in the brain
    • This interrupts the blood flow to an area of the brain

Brain cells are very sensitive to a lack of blood flow. Without oxygen and glucose from the bloodstream, they begin to die within minutes.

Brain Attack Hemorrhagic

Hemorrhagic Stroke
Hemorrhagic strokes are caused by rupture of small blood vessels that supply blood to the brain. Hemorrhagic strokes are more common in those who have high blood pressure. This type of stroke tends to be much more serious than an ischemic stroke.

Hemorrhagic strokes damage the brain in two ways:

  • Loss of blood supply
  • Effects of bleeding:
    • Bleeding within brain tissue causes swelling and increases the pressure against the brain.
    • The pressure directly injures brain cells.

Hemorrhagic strokes account for about 15 percent of all strokes. One type of hemorrhagic stroke, a subarachnoid hemorrhage, accounts for about 5 to 7 percent of all strokes.

Brain Attack Ischemic

Ischemic Stroke
Ischemic strokes account for nearly 80 percent of all strokes. There are two types of ischemic strokes: thrombotic strokes and embolic strokes.

Thrombotic Stroke
Thrombotic strokes are caused by a blood clot that forms in a narrowed artery. Blood clots usually form in larger arteries. Thrombotic strokes account for about 2 percent of all strokes.

Blood clots may also develop in very small arteries. These are called lacunar strokes. Lacunar strokes cause tiny strokes in the brain. They are most common in people with high blood pressure.

Embolic Stroke
Emboli are abnormal pieces of material that move through the bloodstream.

An embolus may be a blood clot or a small fragment of tissue that breaks away from the wall of a diseased artery. Embolic strokes represent about 10 to 15 percent of all strokes.

Emboli move (embolize) from a location outside the brain, such as the heart or a carotid artery. They travel through the bloodstream and eventually become lodged in a brain artery, which blocks blood flow and causes a stroke.

Sometimes a small clot will block the flow of blood for a short time, and then dissolve. This causes stroke symptoms that disappear within 24 hours. It is called a transient ischemic attack (TIA or 'mini stroke').

An embolus may arise from:

Continue to Brain Attack Anatomy

Last Updated: Jul 10, 2009 References
Authors: Stephen J. Schueler, MD; John H. Beckett, MD; D. Scott Gettings, MD
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