Central nervous system vascular malformations are rare abnormalities of blood vessels in your brain or spinal cord and their membranes.

There are several types of central nervous system vascular malformations, including:

• Arteriovenous malformations (AVMs). Arteriovenous malformations are abnormal tangles of blood vessels connecting arteries and veins. AVMs may occur anywhere in the body but most often occur in or near the brain or the spine.
• Capillary telangiectasias. Capillary telangiectasias are small dilated blood vessels (capillaries).
• Cavernous malformations. Cavernous malformations are abnormally formed blood vessels in your brain or spinal cord that have the appearance of a mulberry.
• Dural arteriovenous fistulas. Dural arteriovenous fistulas are abnormal connections between arteries and the tough covering over the brain or spinal cord (dura) and a draining vein.

Venous malformations. Venous malformations, also known as developmental venous anomalies, are abnormally enlarged veins in your brain or spinal cord.