An arteriovenous malformation (AVM) is an abnormal tangle (like a bird’s nest) of blood vessels. The tangle is made of arteries that would normally supply brain tissue and veins that would normally drain brain tissue.
Scientists aren’t sure what causes arteriovenous malformations. They believe they develop during pregnancy, so you’re born with an AVM (they’re congenital). Some cases have been reported in people with head trauma or certain infections. Only in rare cases are AVMs thought to be hereditary (run in families).
You may or may not have symptoms if you have an arteriovenous malformation. Up to 15% of people with AVMs don’t have symptoms. Often, the first sign you have an AVM is after it bleeds.
Brain AVM: If you have a brain AVM and it leads to a blood vessel bleed (rupture), it can cause a stroke and brain damage. About 50% of people with a brain AVM have a brain bleed (hemorrhage) as their initial symptom.
AVMs can irritate the surrounding tissue, causing neurologic symptoms, including:
Spinal cord AVM: If you have a spinal cord AVM, symptoms include:
AVMs in other locations: If you have AVMs in other locations in your body (other than your brain and spine), you may or may not have symptoms depending on their size and the significance of the location. General symptoms may include:
Treatment choices depend on the type, size and location of the AVM, risk of AVM rupture, your symptoms, your age and your general health. Ideally, the goal of treatment is to reduce the chance of bleeding or make it permanently go away. Surgery on your brain and spinal cord is serious, with risks including complications and death. Each person, and each person’s AVM, is unique and there aren’t any perfect decision-making tools in all cases. In general, though, treating an arteriovenous malformation as soon as possible is usually the best way to avoid serious complications.
One or more of these approaches might be tried:
AVMs can be complicated. There may be times when the AVM might be located in an area where the dangers of surgery or other treatments are of greater concern and pose a greater risk than doing nothing at all. If this is the case, your healthcare team may choose to carefully monitor your AVM with imaging tests over time. If the AVM begins showing signs of change, indicating an increased risk of bleeding, treatment may be considered at that time. Each person and each arteriovenous malformation is unique. Your healthcare team will talk to you and your family about your particular situation and the best way to approach your AVM.
You’ll have a brain scan to make sure the AVM has been completely removed or destroyed. You’ll also have a short hospital stay (a few days) and undergo some short-term rehabilitation.
If you have the gamma knife treatment, you’ll have scans from time to time to see if the AVM is shrinking.
Medications can be given to relieve some of the symptoms of AVMs. These include:
The biggest risk of having an AVM is that it might bleed. If the AVM is in your brain, a brain bleed causes a stroke, brain damage or seizures. Because these areas are enclosed, AVMs can also press on and displace parts of your brain and spinal cord.
AVMs reduce the amount of oxygen in the areas in which they exist. A reduced oxygen level damages tissue.
Your healthcare provider will ask you about your symptoms and conduct a physical exam. They’ll sometimes listen for a bruit, which is a rapid blood flow sound heard in arteries and veins when an AVM is present.
Imaging tests used to detect arteriovenous malformations include:
Brain imaging tests for suspected brain AVMs may include:
Because many AVMs don’t cause symptoms, some are only discovered during an imaging test for another condition (such as injuries, vision problems or headaches) or after they bleed and cause symptoms.
Complications of brain AVMs include: