Arteriovenous malformations (AVMs) are tangles of blood vessels that cause abnormal artery-to-vein connections. Most occur in your brain and spinal cord, but they can happen anywhere in your body. Some people have symptoms; others only have symptoms after an event like a brain bleed. Surgery to remove the AVM is a cure. Other treatments can be highly successful, as well.
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.
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Blood moves through your body within an organized closed circuit of blood vessels. Your arteries carry oxygen-rich blood from your heart to your brain and to the rest of your body’s organs and tissues. Your veins return oxygen- and nutrient-depleted blood and waste products from tissues back to your heart and lungs. The exchange takes place in your capillaries, where the smallest blood vessel units of arteries and veins connect with each other. This is how normal blood circulation works
If you have an AVM, this “bridge” of capillaries between your arteries and veins is missing. The malformation can begin anywhere along the vascular tree, from the arterial (arteries) side to the arterial-capillary and the venous (veins) side.
The force of the blood flow from your arteries brings a lot of pressure to the AVM. Veins have weak walls and can’t always adjust to the pressure of blood flow. If your veins can’t handle the blood pressure, it might burst and bleed, which can cause significant health problems.
Brain AVMs are AVMs that develop anywhere within your brain tissue or on the surface of your brain. AVMs most commonly occur in your brain, brainstem and spinal cord.
We have about 100,000 miles of blood vessels in our bodies. So, it’s possible for arteriovenous malformations (AVMs) to form anywhere in your body — on your face, arms or legs, and in your tissues and organs like your heart, liver, lungs, genital or reproductive tract. These AVMs are called peripheral arteriovenous malformations.
Arteriovenous malformations are rare. They’re present in about 1 in 100,000 people.
Anyone can be born with an AVM. They’re mainly discovered in younger people from age 20 to 40. Risk of symptoms is highest between ages 40 and 50. AVMs happen in an equal number of males and females.
AVMs cause harm in the following ways:
They can be. The greatest danger is bleeding (hemorrhage). If you feel a sudden, severe headache (“worst in your life”), call 911. You might have a bleeding brain AVM. About 2.2% of unruptured brain AVMs and 17% of previously ruptured AVMs burst (rupture) every year.
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:
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:
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.
No, AVMs can’t be prevented because researchers believe they’re congenital, meaning you’re born with them. But if you develop any of the symptoms listed in this article, see your healthcare provider right away. Responding quickly to developing symptoms is the best approach.
Each person’s AVM is a unique situation. If you’ve had surgery and your AVM has been successfully removed, you’re cured of this condition.
The outcome of other AVM treatments is very good, but there are many variables, including:
Your healthcare team can best discuss your AVM and the likely expected outcome.
If you have an arteriovenous malformation and don’t get treatment, there’s a 2.2% chance it will burst.
If you experience a sudden, severe headache (“worst in my life”), seizures, weakness in your arms or legs, vision problems, balance problems or memory and attention problems, call 911. These are signs of a life-threatening emergency. This could be a brain bleed.
No. Some arteriovenous malformations never cause a bleed and may not even cause symptoms or any health problems your entire life. Some are only discovered during an imaging test for another reason or after death during an autopsy.
AVMs can cause other health issues other than bleeds. Some AVMs that grow and become large can press on an area of tissue and cause tissue damage, nerve cell damage and other cell damage in that area. If large enough and in a vital area, the lack of the capillaries between your arteries and veins can cause a lack of oxygen, nutrients and waste exchange in tissue in this area. This can lead to tissue death.
Yes, unfortunately, they can be. How deadly or severe an arteriovenous malformation might be depends on its size and location. A massive bleed from a ruptured AVM in your brain can be fatal. However, some people have AVMs and never have any symptoms or health problems.
Not necessarily. It may, but most often, the location you feel headache pain isn’t specific to the area of the AVM.
Because of the increase in blood volume and blood pressure that comes with pregnancy, being pregnant with an AVM can increase the risk of an AVM bleed. In some people, the changes brought on by pregnancy can cause the sudden appearance or worsening of AVM symptoms.
AVMs can cause small changes in your child’s ability to learn, or cause behavioral changes. These changes might happen before more obvious symptoms develop when your child is older (if symptoms develop).
No. Some very small brain bleeds, called microbleeds, cause limited damage and few symptoms. But over time, many microbleeds can increase the risk of dementia and impair thinking functions.
An aneurysm is a weakened, ballooned-out area in an artery. It most commonly forms at the point where two arteries branch. An aneurysm can develop as a complication of an AVM.
Hemangiomas are vascular (blood vessel) malformations that are visible on the skin. They’re also known as a strawberry mark. They aren’t dangerous and don’t require treatment.
Cavernous malformations are a type of vascular lesion. Unlike an AVM, they’re filled with slow-moving blood that’s usually clotted. They can leak but usually don’t leak as severely as AVMs and are often don’t cause symptoms.
A fistula is a general term for an abnormal connection of blood vessels. Arteriovenous fistulas are found in the tissue that covers your brain and spinal cord (the dura mater or arachnoid). AVMs are found inside the tissues of your brain.
A note from Cleveland Clinic
An arteriovenous malformation (AVM) is a serious medical condition. Some people have no symptoms of an AVM until they have a bleeding event. AVMs are mostly found in your brain and spinal cord, but can be present anywhere in your body. The decision to treat an AVM depends on many factors, including consideration of the risk that an AVM may bleed and result in significant or even life-threatening damage if left untreated (especially if located in your brain). Available treatments are highly effective. Your healthcare team will discuss with you the details of your AVM — its size and location — and other factors to develop treatment options that are best for you.
Last reviewed by a Cleveland Clinic medical professional on 02/27/2022.
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