In an AVM, the flow of blood between arteries and veins, which normally occurs through capillary vessels, is shortcut by the development of a network of larger vessels connecting directly from arteries to veins. The higher arterial pressure connecting to the smaller veins can cause them to burst.

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An aneurysm is a balloon-shaped structure, which forms at a weak spot in the wall of the blood vessel and fills with blood. Aneurysms typically grow over time, and due to the pressure placed on the weakened wall of the aneurysm may cause them to burst.

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Hemorrhagic stroke is generally caused by a blood vessel bursting in the brain resulting from a vessel defect such as an aneurysm or an AVM. AVM's and aneurysms also occur in blood vessels situated peripherally (outside the brain and the heart) and, if undetected or left untreated, may also burst causing life threatening internal bleeding.

Embolic agents are widely used to fill and seal both neurovascular (in the brain) and peripheral AVM's and aneurysms.

Related Sites

:::	Beth Israel Medical Center Institute for Neurology and Neurosurgery
	Disorders in adults and children explained, including aneurysms, stroke, Parkinson's, Syringomyelia-Hydromyelia, and headaches.
:::	Center for Inherited Neurovascular Diseases
	Research to determine which genes are responsible for selected forms of neurovascular disease.
:::	Neurology and Neurosurgery Forum
	Interactive medical question and answer format about all neurological diseases and conditions. Includes an archive of articles.
:::	What you should know about AVMs
	A Patient's Guide to Endovascular Therapy: Embolization of Arteriovenous Malformations brought to you by the UCLA Medical Center.

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