Arteriovenous malformation - cerebral Health Article

Definition

A cerebral arteriovenous malformation is an abnormal connection between the arteries and veins in the brain that usually forms before birth.

Alternative Names

AVM - cerebral

Causes, incidence, and risk factors

The cause of cerebral arteriovenous malformation (AVM) is unknown. The condition occurs when arteries in the brain connect directly to nearby veins without having the normal vessels (capillaries) between them.

Arteriovenous malformations vary in size and location in the brain.

An AVM rupture occurs because of pressure and damage to brain tissue, as well as a lack of blood flow to the brain. Symptoms may also occur when large AVMs that have not bled press on the brain tissue.

Cerebral arteriovenous malformations occur in less than 1% of people. Although the condition is present at birth, symptoms may occur at any age. Hemorrhages occur most often in people ages 15 - 20, but can also occur later in life. Some patients with an AVM also have cerebral aneurysms.

Symptoms

Symptoms that may occur with an AVM that has not bled include:

• Decreased sensation in any part of the body
• Headache
  • In one area (localized) or general
  • Resembles a migraine headache in some cases
• Muscle weakness, any part of the body
• Seizures
  • Generalized tonic-clonic seizure
  • Partial (focal) seizure
• Vision changes
  • Blurred vision
  • Decreased vision
  • Double vision

Additional symptoms:

• Decreased consciousness
• Dizziness
• Dysfunctional movement
• Ear noise/buzzing
• Eyelid drooping
• Facial paralysis
• Fainting
• Impaired smell
• Speech impairment

There are often no symptoms until the AVM ruptures. This results in sudden bleeding in the brain (hemorrhagic stroke). In more than half of patients with AVM, hemorrhage is the first symptom. Symptoms of AVM hemorrhage are the same as those of other intracerebral hemorrhage.