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Arteriovenous Malformation (AVM)

What is Arteriovenous Malformation?

An Arteriovenous Malformation (AVM) is an abnormal, complex tangle of blood vessels connecting arteries and veins directly, usually in the brain or spine. The condition means there are no capillaries to slowly deliver oxygen-rich blood to normal tissue. The high pressure of the blood flow can cause serious problems. AVMs are rare. Fewer than 200,000 AVMs are diagnosed in the U.S. each year, and brain AVMs impact less than 1 percent of the population. Brain or spine AVMs – sometimes called neurological AVMs – are the most likely type to have long-term effects.

Causes of Arteriovenous Malformation

The cause is unknown, but for most people, the blood vessels formed incorrectly during fetal development. One type, called the Galen defect, has symptoms that show up soon after birth. In this type, fluid builds up in the brain, causing the head to swell. The condition can cause swollen veins, seizures, failure to thrive, and congestive heart failure.

AVMs can also develop later in life. Most people experience symptoms between the ages of 10 and 40. Ruptures are more likely between the ages of 15 and 20. In middle age, AVMs are more likely to remain stable. Pregnant women, however, could experience difficulties because of increased blood volume.

Males are more likely to have arteriovenous malformations (AVMs).

Signs of Arteriovenous Malformation

Most people with AVMs experience no symptoms or problems. Some people with brain AVMs will experience seizures, headaches, numbness, tingling, or muscle weakness in one part of the body.  Depending on the location, symptoms could include vision trouble, difficulty speaking, dizziness, hallucinations, and coordination problems. See a doctor if you experience those symptoms. An AVM that bleeds is a medical emergency. They account for 2 percent of hemorrhagic strokes per year.


AVMs are commonly discovered in brain scans for other medical conditions since they may not cause any symptoms until they rupture. In about half of patients for brain AVMs, the first sign is hemorrhage. Your doctor will learn as much as they can about your symptoms, medical history, and physical condition before making a diagnosis.

Several options exist for brain imaging that would help confirm a diagnosis. During an angiography, technicians will insert a safe dye into an artery that allows the path of blood flow to the brain to be tracked by X-ray. A CT image of the brain could be taken to determine whether a hemorrhage has occurred.  An image generated by an MRI could also help detect an AVM. 

Treatment for AVMs

Surgery is the most common treatment for AVMs, but the location of the mass will be an important consideration. Medication may be offered to control symptoms. Early neurosurgical treatment may be recommended to prevent a rupture or re-rupture of an AVM. Your UTHealth Houston Neurosciences team may also consider endovascular embolization and stereotactic radiotherapy. The goal would be to either remove the AVM or create an artificial clot. Endovascular embolization is a minimally invasive procedure that uses small catheters to deliver a material that will stop the blood from flowing through the malformation. In a Gamma Knife treatment, a high dose of radiation is targeted at the AVM, damaging and eventually closing the wall of the blood vessel.

Clinical trials are also being performed to assess new treatment options.

What You Can Expect at UTHealth Houston Neurosciences

At UTHealth Houston Neurosciences, our dedicated team of neurosurgeons and other specialists uses the latest technology to accurately diagnose and treat AVMs. We work in multidisciplinary teams to share insights, leading to better treatment decisions and outcomes. Throughout the treatment process, we will work closely with the doctor who referred you to ensure a smooth transition back to your regular care. While you are with us, you will receive expert care, excellent communication, and genuine compassion.

Cerebrovascular and Stroke Care

Contact Us

At UTHealth Houston Neurosciences, we offer patients access to specialized neurological care at clinics across the greater Houston area. To ask us a question, schedule an appointment, or learn more about us, please call (713) 486-8000, or click below to send us a message. In the event of an emergency, call 911 or go to the nearest Emergency Room.