A cerebral arteriovenous malformation is a birth defect in which there is an abnormal connection between the arteries and veins in the brain.

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 their size and location within the brain.

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. Depending on the location and the severity of the bleed, the hemorrhage can be very disabling or even deadly.

Symptoms of an AVM rupture are similar to a stroke, and occur because of a lack of blood flow to the brain. Symptoms may also occur when large AVMs press on the brain tissue, which can cause nerve damage and blood flow problems.

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 aged 15 - 20, but can also occur later in life. Some patients with an AVM also have a cerebral aneurysm.

• Headache
  • Sudden and severe
  • Localized or general
  • Resembles migraine headache in some cases
• Vomiting that occurs with headache
• Vision changes
  • Decreased vision
  • Double vision
  • Blurred vision
• Seizures
  • Partial (focal) seizure
  • Generalized tonic-clonic seizure
• Muscle weakness, any part of the body
• Decreased sensation, any part of the body
• Mental status change
  • Sleepy, stuporous, lethargic
  • Confused, disoriented
  • Irritability
• Stiff neck

Additional symptoms:

• Speech impairment
• Smell - impaired
• Movement - dysfunctional
• Fainting
• Facial paralysis
• Eyelid drooping
• Ear noise/buzzing
• Dizziness
• Consciousness - decreased

A complete physical examination and neurologic examination are required.

Tests that may be used to diagnose an AVM include:

• Head CT scan
• Cerebral angiogram
• Cranial MRI
• MRA (magnetic resonance angiography)
• EEG (electroencephalogram) if symptoms include seizures

A bleeding AVM is a medical emergency. The goal of treatment is to prevent further complications by controlling bleeding and seizures and, if possible, removing the AVM.

Treatments include open brain surgery, endovascular treatment, and radiosurgery. Some treatment options are used together.

Open brain surgery is removes the malformation through an opening made in the skull. It must be done by a highly skilled vascular neurosurgeon. Possible complications include brain swelling, hemorrhage, stroke, or seizure.

Embolization (endovascular treatment) is the injection of a glue-like substance into the abnormal vessels to stop bleeding into the AVM. This may be an alternative if surgery can not be done.

Stereotactic radiosurgery is another alternative. This procedure delivers radiation directly to the area of the AVM. It is particularly useful for small deep AVMS which are difficult to remove by surgery.

Anti-convulsant medications, such as phenytoin, are usually prescribed if seizures occur.

Approximately 10% of cases in which hemorrhage is the first symptom are deadly. Some patients may have permanent seizures and neurological problems.

• Intracerebral hemorrhage
• Subarachnoid hemorrhage
• Seizures
• Permanent neurologic changes such as paralysis or sensory problems
• Focal weakness
• Numbness of any part of the face/body
• Vision changes
• Language difficulties
• Persistent headache
• Hydrocephalus (dilated cavities of the brain - "water on the brain")

Go to the emergency room or call the local emergency number (such as 911) if you have a severe headache, vomiting, seizures, weakness or numbness of parts of the body, or other symptoms of a ruptured arteriovenous malformation.