Arteriovenous malformations (AVM)

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What are arteriovenous malformations (AVM)?

Arteriovenous malformations, or AVMs, are irregular connections between arteries and veins. They can occur anywhere in the body but are most common in the brain and spinal cord. The greatest risk of an AVM is that it will rupture and cause a stroke. 

Your arteries carry blood from your heart to the rest of your body. As the arteries move farther away from the heart, they branch off and get smaller. Very small arteries turn into capillaries that carry blood to your cells and tissues. As the capillaries leave the tissue, they empty into larger veins that carry blood back to the heart. An AVM is a tangle of blood vessels that bypasses the capillaries and connects the arteries directly to the veins. 

At Penn Medicine, we have extensive experience managing conditions like arteriovenous malformations. Our collaborative approach to cerebrovascular disease care helps you receive careful monitoring and timely treatment to lower your stroke risk related to an AVM.

The impact of arteriovenous malformations 

An AVM can damage brain or spinal cord tissues through: 

  • Bleeding (hemorrhage): Because of the direct connection with arteries, blood pressure inside the veins of the AVM is higher than normal. This extra force can cause the wall of the vein to bulge (aneurysm) and, eventually, rupture and bleed. In the brain, this can cause a dangerous hemorrhagic stroke. 
  • Compression of the brain and spinal cord structures: AVMs can grow to over 2.5 inches. A large AVM pressing on the brain or spinal cord can cause a range of neurological symptoms. This pressure can also disrupt the flow of cerebrospinal fluid (CSF), a clear liquid that surrounds the brain and spinal cord. A buildup of CSF can lead to hydrocephalus or intracranial hypertension. 
  • Reduced blood flow: AVMs divert blood flow from brain and spinal cord tissues, leaving them deprived of oxygen and nutrients. As a result, the tissue may deteriorate or die, impairing normal function. 

Arteriovenous malformations are rare. Doctors diagnose about 3000 new cases of AVM each year in the U.S. 

Understanding the symptoms of AVM

Arteriovenous malformation symptoms vary based on their location and size. You might not have any symptoms, especially when you’re young. Most people are in their mid-30s when they first notice signs. Symptoms can also appear or get worse during pregnancy because of increases in blood volume and blood pressure.

Vein of Galen malformation

A vein of Galen malformation is an AVM in the vein of Galen, which lies deep in the brain. Symptoms occur at or shortly after birth. In some infants, the malformation leads to a rapid flow of blood to the heart that causes heart failure within the first few days of life.

Other symptoms in infants and children with vein of Galen malformations include:

Many children with vein of Galen malformations do not survive past infancy. Children who receive treatment may have a good prognosis. Others may have long-term developmental problems.

What causes arteriovenous malformations?

It is unclear what causes AVMs. Most doctors believe they develop during pregnancy and people are born with it (congenital). But AVMs rarely run in families, so it’s unlikely you will pass the condition to your child.

Diagnosing arteriovenous malformations

To perform an AVM diagnosis, your doctor will ask about your symptoms and medical history and perform a physical exam. Some AVMs cause turbulent blood flow inside your blood vessels that causes a noise called a bruit. Your doctor may hear this noise through a stethoscope during the physical exam.

If you have a known or suspected AVM, your doctor will likely perform a cerebral angiogram. This test helps your doctor assess your condition and plan for treatment. A thin tube (catheter) is inserted into a blood vessel into your groin or wrist. Your doctor advances the catheter to the neck or head and releases a contrast dye. Imaging taken after the release of dye highlights any abnormalities. In some cases, endovascular AVM treatment can occur right away during the angiography.

Your provider may order imaging tests to look at the blood vessels in your spine, neck and head.

CT scan
A CT scan helps diagnose traumatic injuries, cancer, vascular diseases, and many other conditions.
MRA
A magnetic resonance angiogram (MRA) detects blood vessel problems quickly and accurately.
MRI
An MRI provides high-resolution images of the brain, spine, and many other structures in the body.
CT angiography (CTA)
CT angiography (CTA)

AVM treatment options

Treatment for an AVM depends on its size, location, and whether it has ruptured. If the AVM has not bled, your care team will help you weigh the risk of future hemorrhage against the risks of treatment. Factors that may influence this decision include pregnancy, the size and location of the AVM, your symptoms, and your age and overall health. Your provider may also use the Spetzler-Martin grading scale to estimate surgical risk and help determine the safest approach.

Medications can help manage symptoms like seizures and headaches. For some AVMs, minimally invasive or surgical procedures may be recommended.

Gamma Knife
Gamma Knife radiosurgery is a blade-free surgical option for brain tumors and disorders.
Endovascular embolization
Endovascular embolization

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