Authors: Kriti Bhayana, MD, Cleveland Clinic, Cleveland, OH; Stuart Fraser, MD, Director, Pediatric Stroke Program, UTHealth Institute for Stroke and Cerebrovascular Disease, Houston, TX 

Reviewed: November 2023 

SUMMARY 

An arteriovenous malformation (AVM) is an abnormal tangle of blood vessels connecting the arteries and veins. Patients with AVMs are usually born with this condition. AVMs can also appear shortly after birth.  

Patients can present with:  

• Headaches 
• Seizures 
• Learning difficulty 
• Muscle weakness 
• Tingling 
• Numbness 
• Dizziness 
• Brain bleeds (sometimes)  

In some cases, there may be no symptoms at all.  

AVMs are diagnosed by taking images of the brain. They are usually treated with surgery. Some AVMs are treated with radiation as well.   

Disorder Overview

DESCRIPTION

Arteries carry oxygen-rich blood from the heart to all tissues. Veins carry the blood returning from tissues back to the lungs and heart. Veins have weaker walls than arteries.  

Capillaries are thin blood vessels that connect arteries to veins as they go through the tissues. They allow the oxygen-rich blood to seep through the tissues. They also decrease the pressure of blood as it goes back to the veins.  

An arteriovenous malformation (AVM) is an abnormal tangle of blood vessels connecting the arteries directly to veins. There are no normal capillaries in between.  

When this happens, the oxygen-rich blood is unable to reach the tissues. The blood returning to the veins is also under high pressure. If the veins are unable to handle this increased pressure, they can burst. This can lead to bleeding.  

AVMs can occur anywhere in the body but are common in the brain and around the spinal cord.  

There can be other types of malformations of the blood vessels in the brain. These include: 

Not all AVMs bleed. It depends on their size, type, and location in the brain. Some people can have AVMs all their life and not experience any symptoms. Unfortunately, large AVMs that bleed can be fatal.  

SIGNS AND SYMPTOMS

Brain AVMs can present with symptoms resulting from irritation of the neurological tissue. These symptoms include: 

• Seizures 
• Headaches 
• Weakness of the muscles 
• Tingling and/or numbness 
• Changes in vision, balance, and speech 
• Dizziness  

There can also be subtle signs of learning difficulty or behavioral issues. 

CAUSES

Mostly, these malformations are congenital. This means the person is born with them. Sometimes, they can appear shortly after birth or even later in life. In some cases, they may be passed from one generation to the next.  

The cause of these malformations is not well understood. In some situations, changes in the genetic code can result in them. This has to do with the formation of blood vessels in a developing baby. There may be problems with the chemicals responsible for their formation, resulting in such a malformation.  

In a few situations, AVMs have also been reported to result from injury to the brain. Sometimes, a reason is never found.  

LABORATORY INVESTIGATIONS

Often, the malformation is found incidentally when the patient gets scans of their brain due to another reason. 

If a patient is experiencing symptoms, a neurologist will review those symptoms and perform a neurological exam.  

AVMs are diagnosed using imaging tests. These include:  

• Computed tomography (CT).  
• Magnetic resonance imaging (MRI). 
• Computed tomography angiography (CTA) or magnetic resonance angiography (MRA). The blood vessels are assessed using CTA or MRA.  
• Catheter angiogram or digital subtraction angiography (DSA). Sometimes, a test involving a catheter (an instrument inserted through the groin or wrist) and dye is used. This is called a catheter angiogram or DSA.  

If a genetic cause is suspected, a blood test to check for the change in the genetic code may be done.  

People who have their AVMs treated surgically need regular testing. They should be tested every year after the procedure for up to five years.  

A disease called hereditary hemorrhagic telangiectasia (HHT) can increase the risk for AVMs. People who have HHT are screened with imaging tests from time to time to check for any AVMs.  

TREATMENT AND THERAPIES

A neurologist and neurosurgeon work together to decide on the optimal treatment plan for the patient.   

The treatment will depend on the size, location, and type of AVM. This can be done through various techniques: 

All treatments for AVMs come with risks and possible complications that should be discussed with the patient’s doctor. Complications of surgery include:  

• Brain bleeds 
• Seizures 
• Aneurysms 
• Permanent brain problems (like weakness or difficulty with speech) 
• Death 

Treatment with radiosurgery can be associated with seizures and brain swelling.  

Every patient’s situation is unique. The risks and benefits of all treatment options should be discussed with the family and treatment team. 

OUTLOOK

For children who have their AVM surgically removed, the AVM usually does not return. However, the surgeon will often follow up for several years to make sure. For those who undergo radiosurgery, monitoring will be needed to look for shrinkage of the malformation.  

Children who do not have any symptoms can grow up to be independent adults. Sometimes, they may have to take medications to manage complications related to either the malformation or its treatment. For example, they may use anti-seizure medications for seizures or pain medications for headaches.  

AVMs can sometimes affect learning or behavior. Some children have mild learning difficulties due to their AVM.  

Those who do not get surgery are generally advised to avoid excessive exercise. They may also need to stay away from blood thinners. Diet has not been proven to cause or prevent symptoms.  

RELATED DISORDERS

There are other kinds of malformations of the blood vessels of the brain. They can result in similar symptoms. It is important to identify them so they can be managed.  

Related disorders include:  

Arteriovenous Malformations (AVMs) [Internet]. Bethesda, MD: National Institute of Neurological Disorders and Stroke; [cited 2023 Oct 10]. Available from: https://www.ninds.nih.gov/health-information/disorders/arteriovenous-malformations-avms#toc-who-is-more-likely-to-get-arteriovenous-malformations-. 

What is an Arteriovenous Malformation [Internet]. Dallas, TX: American Heart Association; 2018 Dec 4 [cited 2023 Oct 10]. Available from: https://www.stroke.org/en/about-stroke/types-of-stroke/hemorrhagic-strokes-bleeds/what-is-an-arteriovenous-malformation. 

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