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Types of Stroke

Ischemic Stroke

An ischemic stroke occurs if an artery that supplies oxygen-rich blood to the brain becomes blocked. Blood clots often cause the blockages that lead to ischemic strokes.

The two types of ischemic stroke are thrombotic (throm-BOT-ik) and embolic (em-BOL-ik). In a thrombotic stroke, a blood clot (thrombus) forms in an artery that supplies blood to the brain.

In an embolic stroke, a blood clot or other substance (such as plaque, a fatty material) travels through the bloodstream to an artery in the brain. (A blood clot or piece of plaque that travels through the bloodstream is called an embolus.)

With both types of ischemic stroke, the blood clot or plaque blocks the flow of oxygen-rich blood to a portion of the brain.

Ischemic Stroke

The illustration shows how an ischemic stroke can occur in the brain. If a blood clot breaks away from plaque buildup in a carotid (neck) artery, it can travel to and lodge in an artery in the brain. The clot can block blood flow to part of the brain, causing brain tissue death.

The illustration shows how an ischemic stroke can occur in the brain. If a blood clot breaks away from plaque buildup in a carotid (neck) artery, it can travel to and lodge in an artery in the brain. The clot can block blood flow to part of the brain, causing brain tissue death.

Hemorrhagic Stroke

A hemorrhagic stroke occurs if an artery in the brain leaks blood or ruptures (breaks open). The pressure from the leaked blood damages brain cells.

The two types of hemorrhagic stroke are intracerebral (in-trah-SER-e-bral) and subarachnoid (sub-ah-RAK-noyd). In an intracerebral hemorrhage, a blood vessel inside the brain leaks blood or ruptures.

In a subarachnoid hemorrhage, a blood vessel on the surface of the brain leaks blood or ruptures. When this happens, bleeding occurs between the inner and middle layers of the membranes that cover the brain.

In both types of hemorrhagic stroke, the leaked blood causes swelling of the brain and increased pressure in the skull. The swelling and pressure damage cells and tissues in the brain.

Hemorrhagic Stroke

The illustration shows how a hemorrhagic stroke can occur in the brain. An aneurysm in a cerebral artery breaks open, which causes bleeding in the brain. The pressure of the blood causes brain tissue death.

The illustration shows how a hemorrhagic stroke can occur in the brain. An aneurysm in a cerebral artery breaks open, which causes bleeding in the brain. The pressure of the blood causes brain tissue death.

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Stroke Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Stroke, visit www.clinicaltrials.gov.


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March 26, 2014 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.