Vascular malformations are abnormal formations of blood vessels, which can occur in the brain. They can occur in the arteries, veins, or capillaries.
Types of vascular malformations include:
Arteriovenous malformation (AVM)
Dural arteriovenous malformation
Under normal circumstances, the brain's arteries connect to a network of tiny capillaries that distribute blood throughout the brain's tissue and return it to the veins. Arteries have thick, strong walls to handle the high pressure at which blood is flowing, but veins are thin-walled, low pressure blood vessels.
In an arteriovenous malformation, arteries and veins are directly connected without the buffer of capillaries: a so-called "short circuit." There is significant risk of bleeding (hemorrhage) with AVMs. Dural AVMs are located in the dura, the brain's leathery outer covering. When a single artery and vein are involved, it is called an arteriovenous fistula (AVF).
Symptoms of a vascular malformation vary depending on its size and location. Symptoms can include stroke, seizure, headache, enlarged blood vessels, memory problems, anxiety and depression. Dural AVMs may also cause vision problems and sounds, like pulsing, inside the head. Some vascular malformations may not produce any symptoms at all.