Your circulatory system consists of your heart and blood vessels. There are three types of blood vessels in the circulatory system: veins, capillaries, and arteries. Arteriovenous malformations (AVMs) are defects in the blood vessels of the circulatory system.
A malformation is an abnormal connection between the veins and arteries. This interferes with your body’s ability to circulate blood. It’s usually congenital, which means the condition is present at birth. Although malformations can begin anywhere in your body, some develop in the brain and spinal cord region, causing seizures and headaches.
What causes AVMs?
What causes AVMs is unknown. Some doctors believe they occur in the womb or shortly after birth and appear later as the child ages.
Children born with an AVM condition may have a bluish tint to their skin. This is due to the absence of oxygenated blood circulating through the body. The skin tends to darken to a deep red or purple as children age and the condition worsens.
Who is at risk for arteriovenous malformations?
There are certain genetic syndromes that can put you at increased risk of having AVMs, such as hereditary hemorrhagic telangiectasia or Osler-Weber-Rendu syndrome. There have been rare reports of AVMs in several family members, though it’s unclear if this is genetic or coincidental.
What are the symptoms of AVM?
The symptoms of AVM vary, depending on:
- location of the AVM
- size of the AVM
- size of the blood vessels involved in the AVM
You may not have significant symptoms if you have an AVM in the brain. In some cases, brain AVMs cause headaches or seizures. Unfortunately, due to lack of symptoms, this type of AVM often goes undiagnosed or unnoticed until it presents life-threatening symptoms.
Common symptoms of brain AVMs include:
- bleeding in the skull, most commonly a subarachnoid hemorrhage
- focal neurologic deficits, such as weakness, numbness, or tingling to one part or side of the body
If the AVM is elsewhere in the body, the symptoms may be more pronounced.
Common symptoms for AVMs found in the limbs and spinal cord include:
- muscle weakness
- inability to move a limb
- lack of coordination
Common symptoms for AVMs found in the organs, chest, or abdomen include:
- abdominal pain
- back pain
- chest pain
- irregular sounds in the affected blood vessels
Some symptoms in children under age 2 include:
- congestive heart failure, where the heart is unable to pump out the blood that enters it
- hydrocephalus, an increase in fluid in the brain that causes swelling
How are AVMs diagnosed?
Your doctor will perform a physical examination and several tests to confirm an AVM. It’s important to rule out other health problems that can mimic the symptoms of AVMs.
Imaging tools used to diagnose AVMs include:
- CT scan: produces detailed images of the inside of the body
- MRI: produces images of the brain and its blood vessels (if you have a brain AVM, this is particularly useful for determining exactly where the AVM is and what brain structures it might be affecting)
- angiography: visualizes the blood vessels around the head and neck by injecting dye through a catheter (which is usually inserted through a blood vessel in the groin)
- magnetic resonance angiogram (MRA): produces images of the blood vessels
How are AVMs treated?
Your treatment plan will depend on your age, condition, and physical health. The most important goal is to prevent internal bleeding, which can lead to stroke or death.
Your doctor might prescribe medications even though they don't cure AVMs. Medications control pain and seizures.
Surgery to repair or remove damaged blood vessels is an option. The type of surgery you’ll need depends on your type of AVM. There are three options:
- conventional surgery
- endovascular embolization
Endovascular embolization is used for arteriovenous malformations deep in the brain or spinal cord tissue. In this procedure, a thin, flexible tube called a catheter is guided to the AVM to close up the abnormal connection. It doesn’t repair the AVM, but it reduces blood flow to it and makes surgery safer.
Radiosurgery involves using a highly concentrated beam of radiation and focusing it directly on the site of the AVM. The radiation damages the blood vessel walls and creates scar tissue, which will eventually stop flow of blood into the AVM.
What is to be expected in the long term?
AVMs can’t be prevented. However, you can manage and treat symptoms with proper medical care. Taking prescribed medications can help avoid bleeding problems, pain, and other complications.
Managing high blood pressure, avoiding medications that thin the blood, and keeping regular appointments with a neurologist can also help monitor your condition and prevent complications.