What Is AVM?

Normally, arteriescarry blood containing oxygen from the heart to the brain, and veinscarry blood with less oxygen away from the brain and back to the heart. When an arteriovenous malformation (AVM)occurs, a tangle of blood vessels in the brain or on its surface bypasses normal brain tissue and directly diverts blood from the arteries to the veins.

AVM: Types & Stages

Are there different types of brain AVMs?

All blood vessel malformations involving the brain and its surrounding structures are commonly referred to as AVMs. But several types exist:

  • True arteriovenous malformation (AVM).This is the most common brain vascular malformation. It consists of a tangle of abnormal vessels connecting arteries and veins with no normal intervening brain tissue.
  • Occult or cryptic AVM or cavernous malformations.This is a vascular malformation in the brain that doesn’t actively divert large amounts of blood. It may bleed and often produce seizures.
  • Venous malformation.This is an abnormality only of the veins. The veins are either enlarged or appear in abnormal locations within the brain.
  • Hemangioma.These are abnormal blood vessel structures usually found at the surface of the brain and on the skin or facial structures. These represent large and abnormal pockets of blood within normal tissue planes of the body.
  • Dural fistula.The covering of the brain is called the “dura mater.” An abnormal connection between blood vessels that involve only this covering is called a dural fistula. Dural fistulas can occur in any part of the brain covering. Three kinds of dural fistulas are:
  • Dural carotid cavernous sinus fistula.These occur behind the eye and usually cause symptoms because they divert too much blood toward the eye. Patients have eye swelling, decreased vision, redness and congestion of the eye. They often can hear a “swishing” noise.
  • Transverse­Sigmoid sinus dural fistula.These occur behind the ear. Patients usually complain of hearing a continuous noise (bruit) that occurs with each heartbeat, local pain behind the ear, headaches and neck pain.
  • Sagittal sinus and scalp dural fistula.These occur toward the top of the head. Patients complain of noise (bruit), headaches, and pain near the top of the head; they may have prominent blood vessels on the scalp and above the ear

Physicians do not categorize states of arteriovenous malformation (AVM) as it is not a progressive disease. The condition is congenital – occurring at birth – and continues through life unless treated. In many cases, symptoms never appear and the person leads a normal life unaware of the condition. However, an AVM can grow, creating pressure on surrounding areas of the brain, leading to headaches, dizziness and confusion. In addition, the AVM can reach a stage of development where it may burst.

AVM Treatment Options

Arteriovenous malformations (AVMs) are abnormal, snarled tangles of blood vessels that cause multiple irregular connections between the arteries and veins. While they are most common in the spinal cord and the brain, they can develop elsewhere in the body. It is unclear why AVMs form. Most often they are inherited, but they can sometimes appear sporadically. ATMs can cause seizures and severe headaches as well as muscle weakness, paralysis, dizziness, vision loss, back pain, confusion, and more. Most dangerously, AVMs can cause significant neurological damage and brain hemorrhaging. Orange County CyberKnife and Radiation Oncology Center offers the most comprehensive array of radiation treatments in Southern California including the CyberKnife Radiosurgery System, an effective treatment for AVMs.

How are AVMs and other vascular lesions treated?

There are several treatment options for patients with AVM, but each involves various dangers depending on the individual. A hemorrhage from an untreated AVM can cause serious neurological damage or death, leading many specialists to recommend surgery. However, surgery on any part of the central nervous system carries risk of serious complications or death. An AVM grading system developed in the mid-80s can help healthcare professionals estimate the risk of surgery based on the size of the AVM, location in the brain and surrounding tissue involvement, and any leakage. Treatment options include:

  • Medication. Although medicines can often lessen general symptoms, such as headache, back pain, and seizures, the definitive treatment for AVMs is either surgery or focused radiation therapy.
  • Conventional surgery – Surgery involves entering the brain or spinal cord and removing the central portion of the AVM, including the fistula. This surgery is most recommended when an AVM is located in a superficial portion of the brain or spinal cord and is relatively small in size. AVMs located deep inside the brain generally cannot be approached through conventional surgical techniques because there is too great a possibility that functionally important brain tissue will be damaged or destroyed.
  • Endovascular embolization – For this treatment, a surgeon guides a catheter through the arterial network until the tip reaches the site of the AVM, then injects a fast-drying glue-like substance, fibered titanium coils or a tiny balloon) that will travel through blood vessels and create an artificial blood clot in the center of an AVM. Since embolization usually does not permanently obliterate the AVM, it is usually used in conjunction with surgery or to radiosurgery to reduce the blood flow through the AVM and make the surgery safer.
  • CyberKnife Radiosurgery – A non-invasive therapeutic approach often used to treat small AVMs that haven’t ruptured is radiosurgery, in which a beam of highly focused radiation is aimed directly on the AVM and damages the walls of the blood vessels making up the lesion. Orange County CyberKnife utilizes the newest technology in radiosurgery – the CyberKnife Radiosurgery System – to effectively treat AVMs. CyberKnife combines a flexible robotic arm with state-of-the-art imaging system to pinpoint the exact location of the AVM minimizing damage to surrounding tissue or organs. The flexibility allows CyberKnife to reach AVMs at hundreds of different angles. Over the course of the next several months, the irradiated vessels gradually degenerate and eventually close, leading to the resolution of the AVM.

Find Out More About CyberKnife Treatment of AVMs

If you want to learn more about the CyberKnife Radiosurgery System at Orange County CyberKnife and how it can treat your AVM, reach out to our medical oncology experts by phone at (714) 962-7100 or by completing our convenient online appointment form. Our cancer specialists are ready to answer all of your questions in detail and your first phone consultation is free. You can trust the specialists at Orange County to provide individualized treatment for your AVM. Call today.


Answer :

Brain AVMs occur in less than 1 percent of the general population. It’s estimated that about one in 200–500 people may have an AVM. AVMs are more common in males than in females.

Answer :

We don’t know why AVMs occur. Brain AVMs are usually congenital, meaning someone is born with one. But they’re usually not hereditary. People probably don’t inherit an AVM from their parents, and they probably won’t pass one on
to their children.

Answer :

Brain AVMs can occur anywhere within the brain or on its covering. This includes the four major lobes of the front part of the brain (frontal, parietal, temporal, occipital), the back part of the brain (cerebellum), the brainstem, or the ventricles (deep spaces within the brain that produce and circulate the cerebrospinal fluid).

Answer :

Most AVMs don’t grow or change much, although the vessels involved may dilate (widen). Some AVMs may shrink due to clots in part of the AVM. Some may enlarge to redirect blood in adjacent vessels toward an AVM.

Answer :

A brain AVM contains abnormal and, therefore, “weakened” blood vessels that direct blood away from normal brain tissue. These abnormal and weak blood vessels dilate over time. Eventually they may burst from the high pressure of blood flow from the arteries, causing bleeding into the brain.

Answer :

The chance of a brain AVM bleeding is 1 percent to 3 percent per year. Over 15 years, the total chance of an AVM bleeding into the brain — causing brain damage and stroke — is 25 percent.

Answer :

The risk of recurrent intracranial bleeding is slightly higher for a short time after the first bleed. In two studies, the risk during the first year after initial bleeding was 6 percent and then dropped to the baseline rate. In another study, the risk of recurrence during the first year was 17.9 percent. The risk of recurrent bleeding may be even higher in the first year after the second bleed and has been reported to be 25 percent during that year. People who are between 11 to 35 years old and who have an AVM are at a slightly higher risk of bleeding.

Answer :

The risk of death related to each bleed is 10 percent to 15 percent. The chance of permanent brain damage is 20 percent to 30 percent. Each time blood leaks into the brain, normal brain tissue is damaged. This results in loss of normal function, which may be temporary or permanent. Some possible symptoms include arm or leg weakness/paralysis, or difficulty with speech, vision or memory. The amount of brain damage depends on how much blood has leaked from the AVM.