Arteriovenous malformation (AVM)

An arteriovenous malformation (AVM) is a tangle of blood vessels that creates an abnormal connection between arteries and veins, bypassing the normal capillary network. When that happens, blood can move too quickly through the area, and nearby brain or spinal cord tissue may not get the oxygen it needs. AVMs can occur in the brain or spine and may lead to serious problems when they rupture or interfere with normal circulation.

Some AVMs are found only after imaging for another issue, while others are discovered after symptoms such as headaches, seizures or bleeding. Because AVMs can raise the risk of stroke or brain hemorrhage, early evaluation is important.

AVMs are often described by where they are located and how they affect nearby tissue.

• Brain AVM: Forms in the brain and may affect movement, speech, vision, sensation or thinking
• Spinal AVM: Develops in or around the spinal cord and may cause pain, weakness, numbness or walking problems
• Ruptured AVM: Has bled and may cause a medical emergency, including sudden severe headache, neurological changes or loss of consciousness
• Unruptured AVM: Has not bled but may still cause seizures, headaches or other neurological symptoms depending on its size and location

Specialists may also classify an AVM by its size, the blood vessels feeding it and how close it is to critical brain or spinal cord structures. These details help determine whether monitoring, embolization, surgery or another treatment approach is most appropriate.

Symptoms vary based on the AVM’s size and location. Some people have no symptoms until the AVM bleeds.

Common symptoms may include:

• Headaches, sometimes severe or persistent
• Seizures
• Weakness, numbness or paralysis in part of the body
• Blurred vision, double vision or other vision changes
• Trouble speaking or understanding language
• Problems with balance, coordination or walking
• Sudden neurological changes caused by bleeding

A ruptured AVM can trigger emergency symptoms that may resemble subarachnoid hemorrhage or other forms of stroke. Seek emergency care right away for sudden severe headache, seizures, confusion, weakness, facial droop or difficulty speaking.

Most AVMs are thought to be present at birth, although many people do not know they have one until symptoms develop later in life. AVMs form when blood vessels develop abnormally, allowing blood to pass directly from arteries to veins without the normal capillary bed in between.

Risk factors and related considerations include:

• Being born with the malformation
• Rare inherited disorders that affect blood vessel formation
• A prior AVM bleed, which may raise the risk of future bleeding
• Location in a part of the brain or spine where the AVM places pressure on nearby tissue

Even when an AVM does not rupture, it can still affect normal blood flow and irritate surrounding brain or spinal tissue. That is one reason Baptist Health Brain & Spine Care’s cerebrovascular specialists evaluate each case individually rather than assuming every AVM should be treated the same way.

Diagnosing an AVM usually starts with a neurological exam and a review of symptoms, followed by imaging to confirm the diagnosis and map the blood vessels involved. Baptist Health Brain & Spine Care uses advanced imaging and diagnostic testing to evaluate cerebrovascular conditions and plan treatment.

Tests may include:

• CT scan: Often used in urgent situations, especially when bleeding is suspected
• MRI: Helps define the AVM’s location and its effect on nearby brain or spinal tissue
• Cerebral angiography: A detailed blood vessel study that can help show feeding arteries and draining veins for treatment planning
• Additional vascular imaging: In selected cases, teams may use specialized angiographic studies to better understand blood flow patterns

Accurate diagnosis is important because AVM symptoms can overlap with other cerebrovascular conditions, including aneurysm, hemorrhagic stroke and other vascular malformations.

AVM treatment depends on whether the malformation has bled, where it is located, the symptoms it is causing and the risks of treatment versus observation.

Treatment options may include:

• Monitoring: Some unruptured AVMs may be watched closely with imaging and follow-up visits.
• Medications: Medicines may help control symptoms such as headaches or seizures, even if they do not remove the AVM itself.
• Endovascular embolization: A minimally invasive catheter-based procedure used to reduce blood flow into the AVM. This may be used on its own in selected cases or before surgery.
• Microsurgical removal: Surgery may be recommended when the AVM can be reached safely and removing it offers the best chance of preventing future bleeding.
• Radiosurgery: Focused radiation may be considered for certain AVMs, especially when open surgery is not the best option.

Some patients may need staged treatment that combines embolization with surgery or radiosurgery. When an AVM is discovered after bleeding, treatment planning may also involve urgent stroke and hemorrhage care.

An untreated AVM can lead to serious complications, especially if it ruptures. The most significant concern is bleeding in the brain or around the spinal cord.

Potential complications include:

• Brain hemorrhage or spinal bleeding
• Seizures
• Stroke-like symptoms or confirmed stroke
• Reduced oxygen delivery to nearby tissue
• Lasting problems with movement, speech, vision, memory or sensation
• Formation of related vascular weakness, including an associated aneurysm

Because complications can be life-changing, evaluation by a specialized cerebrovascular team is important even when symptoms seem mild.

There is no proven way to prevent a congenital AVM from forming. However, early evaluation and ongoing care may help reduce the risk of complications.

You can lower the chance of delayed treatment by:

• Getting medical attention for unexplained seizures, severe headaches or new neurological symptoms
• Seeking emergency care for sudden symptoms that could signal bleeding
• Keeping follow-up appointments and imaging studies if you have a known AVM
• Working with a specialist team to understand whether observation or treatment is safer in your situation

For people living with a diagnosed AVM, prevention focuses less on stopping the AVM from existing and more on reducing the risk of bleeding, neurological injury and avoidable delays in care.

If you have been diagnosed with an arteriovenous malformation or have symptoms that could point to a cerebrovascular problem, the next step is a specialist evaluation. Baptist Health Brain & Spine Care Brain & Spine Care offers access to neurologists, neurosurgeons, neuroradiology experts and advanced treatment options across the region.

To schedule a visit with a Baptist Health Brain & Spine Care provider, fill out an appointment request form or call 833-596-3876.