A tangle of blood vessels that leads to an irregular connection between the brain’s veins and arteries is called a brain arteriovenous malformation (AVM). In normal circumstances, the arteries carry oxygen-rich blood from the heart to the brain, and the veins carry oxygen-poor blood back to the lungs and heart. When this condition occurs, the process of blood circulation is disrupted.
Furthermore, this condition may appear anywhere in the body, but it mostly happens in the brain and spinal cord. Generally, a brain AVM is a rare condition. Usually, it is not possible to determine the exact cause of this condition. While most people have it at birth, it may develop later in life. Therefore, experts think some abnormal genes that run in families could play a role.
Once a person is diagnosed with this condition, treatment focuses on preventing complications (including permanent brain damage and stroke).
Symptoms
Some people with a brain AVM may not experience symptoms until it bursts or bleeds (hemorrhage). In approximately 50% of cases, bleeding is the first symptom of the condition. Check below for other symptoms of a brain AVM:
Depending on the severity and location of the condition, people may also experience other symptoms. For example:
- Severe headaches
- Speaking or walking problems
- Vision changes (such as blindness)
- Weakness
- Numbness or paralysis
- Confusion
While symptoms may appear at any age, they often appear between 10 and 40 years old. Without treatment, a brain AVM may cause damage to the brain tissue. In any case, a brain AVM tends to be stable in middle age and is less likely to cause symptoms.
If you experience any of the previous symptoms or others that cause concerns, do not hesitate to see a doctor.
Causes
Healthcare providers cannot identify the exact cause of a brain AVM, but they believe certain genes play a role. In most cases, people are born with a brain AVM, which means it develops during pregnancy. Sometimes, brain AVMs appear later in life.
Moreover, a brain AVM is common in some people with hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome. This is a disease in which blood vessels do not develop properly in different body parts.
Normally, the heart sends oxygen-rich blood to the brain through the arteries. Thereafter, the blood flow slows by passing through multiple small blood vessels, also known as capillaries. The oxygen-poor blood returns to the lungs and heart through the veins.
In people with a brain AVM, the network of capillaries is missing, which leads to a quick blood flow from the arteries to the veins. As a result, the brain does not get enough oxygen.
Risk Factors
While anyone may develop this condition, there are some factors that may increase the risk of developing it. Examples include:
- Sex – Males are more likely to develop a brain AVM than females.
- Family history of HHT – Some families with a hereditary hemorrhagic telangiectasia (HHT) have an increased risk of developing brain AVMs.
- Aneurysms
- Deep venous drainage
- Smoking
What Are The Possible Complications of Brain AVM?
Without treatment, people with brain AVMs may experience some complications. These include:
- Bleeding – Extra pressure on the walls of the veins and arteries caused by a brain AVM may lead to thinning and weakness of these blood vessels. As a result, it may lead to bursts or ruptures that cause bleeding into the brain (also called hemorrhage). Generally, the risk of brain AVMs bleeding is approximately 2% to 3%. Some studies have shown that pregnancy significantly increases the risk of bleeding in people with a brain AVM.
- Low oxygen levels in the brain tissue – The blood flows too quickly because it does not go through the network of capillaries in the brain. As a result, the brain tissue does not get enough oxygen. Continuous lack of oxygen may lead to permanent damage to the brain or stroke. When it occurs, you may experience the following symptoms. For example, speaking or walking problems, vision changes, numbness, weakness, or paralysis.
- Weak or thin blood vessels – Extra pressure on the walls of arteries and veins may lead to thinning and weakness of these blood vessels. Therefore, an aneurysm may form.
- Brain damage – When the blood flows too quickly, it may prevent protective fluids from flowing freely around the brain. As a result, it may lead to fluid buildup that causes damage to the brain tissue.
There is a serious type of brain AVM that involves a major blood vessel (called the brain of Galen). This type of condition may cause serious complications in babies. While symptoms are usually present at birth, some babies experience symptoms shortly after delivery. These include swollen veins on the scalp, seizures, congestive heart failure, and others.
Diagnosis
To diagnose this condition, physicians usually perform a physical examination to check for abnormalities linked with the condition and may ask some questions about your family history and symptoms. However, they may perform some tests to confirm the condition and exclude others that cause similar symptoms. Check below some tests often involved in a brain AVM diagnosis:
- Cerebral Angiography – This test involves a catheter (a long and flexible tube) that is inserted into a major blood vessel, usually in the groin, and then guided to the brain using X-ray imaging. It helps determine the location and draining veins.
- Computerized tomography (CT) scan – This test is used to get cross-sectional images of different body structures and organs.
- MRI (magnetic resonance imaging) scan – This is another imaging test that uses a magnetic field and radio waves to make detailed pictures of the brain and nearby structures. It may identify the exact location of the brain AVM and show hemorrhages.
Treatment
Physicians usually recommend different treatments for people with brain AVMs because it depends on multiple factors. These include the severity and location of the AVMs, your age, existing health problems, and others. Generally, the goal of the treatment is to prevent life-threatening complications and lessen the symptoms. However, the primary treatment for people with a brain AVM is surgery. Check below some types of surgery used to treat this condition:
- Resection (surgical removal) – This treatment involves the removal of a part of the skull to access the AVM. Then, surgeons will use a high-powered microscope to seal off the AVM and remove it from the brain tissues. After that, physicians will reattach the skull bone and close the incision. Furthermore, discuss with your healthcare professional about the risks and benefits of resection.
- Endovascular embolization – This treatment involves a substance that is injected into the arteries that feed the brain AVM. It helps block the artery and reduce blood flow into the AVM. Endovascular embolization is a less invasive treatment often used to reduce the risk of complications (such as stroke) and reduce the AVM size.
- SRS (stereotactic radiosurgery) – It is a specific treatment used to destroy the AVM. It involves precisely focused radiation delivered directly to the AVM. This radiation damages the blood vessels and causes scarring. However, these scars usually close slowly within 3 years. Healthcare professionals often recommend this treatment when resection and endovascular embolization are not an option.
When the condition is mild and does not cause symptoms, physicians may recommend to monitor it rather than treating. This includes regular checkups.
Frequently Asked Questions
What is the life expectancy of someone with AVM?
Usually, this condition does not affect life expectancy, but some forms of AVM may slightly reduce life expectancy.
Can you fully recover from an AVM?
This condition can be cured through surgery, and people may recover completely within 6 months after surgery. In addition, more than 90% of people who have an AVM bleed survive.
What are the initial signs of AVM?
The following symptoms usually indicate AVMs. For example:
- Numbness or tingling sensations
- Nausea
- Vomiting
- Headaches (sometimes severe headaches)
- Seizures
- Dizziness
- Problems with memory, thinking, balance, or speech
- Vision loss
If any of the previous symptoms occur, immediately contact your healthcare professional. Ask your doctor if you have additional questions.
