Spinal Arteriovenous Malformation (AVM)

What is a spinal AVM?

A spinal arteriovenous malformation (AVM) is a tangle of blood vessels on or near your spinal cord. This happens when an artery connects directly to a vein, bypassing your capillaries.

Capillaries play an important role in moving blood through your body. Usually, your arteries carry oxygen-rich blood from your heart to your spine. Capillaries branch out of arteries to take blood to your spinal cord and tissues. Your spinal cord removes oxygen from your blood. Your blood then moves away from your spinal cord in your veins, back to your heart.

The rerouting of blood affects how much oxygen is delivered to cells, and it’s usually less than what they need. It can cause blood vessels to enlarge, change in pressure and burst, leading to a hemorrhage (excessive bleeding). This is life-threatening. Treatment is available to prevent this complication.

You might hear your healthcare provider refer to a spinal AVM as a “spinal arteriovenous shunt.”

What are the types of spinal AVM?

There are five types of spinal vascular (blood vessel) malformations, including both spinal arteriovenous malformations (AVM) and spinal arteriovenous fistulas (AVF). Both AVMs and AVFs are abnormal connections between an artery and a vein. AVMs happen in spinal cord tissue. AVFs happen in the dura mater. This is the material that surrounds your spinal cord.

The five types include:

• Type I: Dural AVF: Located in the dura mater, or the outer layer of your spinal cord.
• Type II: Intramedullary glomus AVM: Located inside of your spinal cord.
• Type III: Intramedullary juvenile AVM: Located inside of your spinal cord and outside, involving surrounding tissue. This most often affects children and young adults.
• Type IV: Perimedullary AVF: Located in the tissue surrounding your spinal cord.
• Type V: Extradural AVF: Located in the space outside the dura mater.

To note: An AVM rupture may cause more severe symptoms, as there isn’t a covering (the rupture goes directly into tissue) versus AVFs, which usually have a covering, as they reside in the dura matter.

How common is a spinal AVM?

A spinal AVM is the most common spinal blood vessel condition. The exact rate of occurrence is unknown because many people don’t know they have a spinal AVM unless they have symptoms or an unrelated medical test detects it. AVMs are considered uncommon.

What are the symptoms of a spinal AVM?

Symptoms of a spinal AVM happen because a tangle of blood vessels presses on your nerve roots and spinal cord. This type of compression is known as myelopathy. Common symptoms include:

• Back pain.
• Muscle weakness or stiffness (neck, arms and legs).
• Tingling, numbness or loss of feeling in your legs.
• Headache.
• Difficulty with balance and coordination.
• Trouble controlling your bladder and bowels.

Symptoms vary based on the type, severity and location. If the AVM is in your upper back or chest, you may have symptoms in your chest, torso, back, and arms and legs. If it’s in your middle or lower back, it may affect your lower abdomen, back or legs.

They can appear on one side or both sides of your body. You might notice they worsen over time, or your symptoms can come and go. You might not have any symptoms of a spinal AVM but still have one.

When symptoms do start, you should contact a healthcare provider right away. Sudden, severe symptoms like back pain may be a sign that the AVM ruptured (burst). This is a medical emergency and needs treatment immediately.

When do symptoms of a spinal AVM start?

AVM symptoms can happen at any age. Most people experience symptoms between ages 15 and 60. It can vary by type. Most spinal AVMs are present at birth (congenital). But you can develop an AVM as an adult (acquired).

What causes a spinal AVM?

Healthcare providers aren’t sure of the exact causes of spinal AVMs.

For congenital (present at birth) spinal AVMs, studies show that the blood vessels around your spine grow abnormally during fetal development. This changes the path that blood takes to move through your body to avoid an obstruction or blockage, for example.

Acquired spinal AVMs that aren’t present at birth can happen after trauma, like surgery or injury to your spine.

What are the complications of a spinal AVM?

Spinal AVM complications can be life-threatening and could include:

• Hemorrhage: The spinal AVM can rupture (break open) and cause internal bleeding.
• Ischemia: This is a disruption of blood flow. It can reduce how much oxygen and nutrients from blood get to parts of your body that need it. Cells may stop working as expected and damage can accumulate over time.
• Paralysis: Damage to your spinal cord can affect your ability to move parts of your body.

How is a spinal AVM diagnosed?

A healthcare provider will diagnose a spinal AVM after a physical exam, neurological exam and imaging tests.

Imaging tests show the size and location of the AVM in relation to your spine. Your provider may use the following imaging tests to find a spinal AVM:

• Magnetic resonance imaging scan (MRI).
• Magnetic resonance angiography (MRA).
• Myelogram and a computed tomography (CT) scan.

In addition, nerve conduction testing and electromyography tests may be an option if you have numbness, tingling or muscle weakness.

How is a spinal AVM treated?

Treatment options for spinal AVM include:

• Embolization: A surgeon uses a tiny catheter (a device to reach the affected area from the inside) on the treatment area to stop bleeding, close off a blood vessel or remove an abnormal connection.
• Surgery: A surgeon will remove the spinal AVM and make sure blood vessels flow correctly.
• Stereotactic radiosurgery: Beams of radiation directed at the AVM destroy and close blood vessel malformations.

Your provider will review what treatment options are available for your specific situation. The size and location of the AVM play a big role in what treatment option is safest and most effective. They’ll also discuss possible side effects so you can make an informed decision about your health.

Most spinal AVM cases require surgery to prevent complications. Your provider may offer pain medications or other types of treatment options until the date of your surgery to help you manage symptoms and stay comfortable.

How soon after treatment will I feel better?

You should feel relief from symptoms like pain or a headache shortly after surgery. Your recovery time varies based on what type of surgery your provider recommends. Recovery from surgery can take several weeks. You may need to participate in physical rehabilitation (physical or occupational therapy) to strengthen your muscles or improve your balance after the procedure.

Can a spinal AVM be prevented?

There isn’t a known way to prevent spinal AVMs. Research is ongoing to learn more about what causes them.

What’s the outlook for a spinal AVM?

Surgery can correct a spinal AVM. Your outlook is best when a healthcare provider diagnoses and treats this condition before complications begin. This isn’t always an easy task, as you might have a spinal AVM and not have symptoms right away. Not treating a spinal AVM can cause damaging and life-threatening complications like paralysis and bleeding.

What is the spinal AVM surgery success rate?

Spinal AVM surgery is usually successful. One study found that embolization and surgical removal treatment for a spinal AVM had a 74% and 88% success rate respectively. In the same study, 70% of people who underwent treatment saw symptom relief.

Many factors contribute to the surgery outcome, like your general health and the size and location of the AVM. Your provider can give you the best information about your situation.

How does a spinal AVM affect pregnancy?

While it’s possible to have a successful pregnancy with a spinal AVM, complications are possible. You may have a higher risk of the AVM rupturing (breaking open) or causing severe pain and paralysis. This can be life-threatening for both the birthing parent and the fetus. A healthcare provider will let you know what treatment options are safe for your situation and how you can prepare for a healthy pregnancy.

When should I see a healthcare provider?

If you notice symptoms of a spinal AVM, contact a healthcare provider.

Sometimes, an AVM can unexpectedly break open. This is a medical emergency. If you experience any of the following symptoms, visit the emergency room:

• Sudden, severe back pain.
• Pale, cool or clammy skin.
• Trouble breathing.
• Fast heart rate.
• Nausea or vomiting.
• Loss of balance.
• Confusion and memory loss.
• Difficulty moving or turning your neck.
• Severe headache.
• Loss of consciousness.

What questions should I ask my healthcare provider?

• Where is the spinal AVM?
• What treatment option do you recommend?
• What are the side effects of treatment?
• What is the recovery time after surgery?
• Can a spinal AVM happen again after removal surgery?
• Should I get genetic testing if a first-degree relative has a spinal AVM?