Who Is More Likely to Get Arteriovenous Malformations?

Arteriovenous malformations (AVMs) are abnormalities in the blood vessels. Under normal conditions, the bloodstream flows from arteries to capillaries to veins. Blood must flow from arteries to capillaries – a network of smaller blood vessels with thin walls that allow oxygen and nutrients to enter the bloodstream – to decelerate its speed, among other reasons, and lower blood pressure before it enters the veins.

With arteriovenous malformation, there are no capillaries. The arteries connect directly to the veins through fistulas, which are abnormal connections between two body parts that aren’t supposed to be directly linked. As blood pumps through the veins at high pressure, the veins eventually weaken and rupture, causing brain hemorrhage.

Arteriovenous malformations can occur anywhere in the body but are more common in the spinal cord and brain. Brain arteriovenous malformation is particularly dangerous because bleeding can lead to stroke or brain damage. 

The lack of capillaries in AVM also means tissues and cells don’t get enough oxygen and nutrients. A patient may not suffer a hemorrhage but experience other serious side-effects related to injury of brain tissues.

The cause of AVM is still unclear today. Specialists believe it is in some cases congenital (it exists at birth), but it doesn’t appear to run in families, so it’s not hereditary. If you discover you have AVM, you don’t have to worry about your children having it.

With no known and definitive cause of arteriovenous malformations, it’s difficult to pinpoint who is most likely to develop them. However, neurosurgeons and specialists recognize two risk factors that can help determine if a patient is at high risk of having AVM.

People with the following risk factors will have a higher risk of having AVMs than people who don’t:

• Hereditary Hemorrhagic Telangiectasia (HHT)

Genetics being a risk factor is specific to a condition called Hereditary Hemorrhagic Telangiectasia (HHT), also known as Osler-Weber-Rendu disease. A person with HHT can have multiple AVMs and minor malformations called telangiectasias.

The telangiectasias are prominent on the face – nose, lips, and between the eyes – and fingers, appearing as pink lesions on the skin. The AVMs in a person with HHT can occur in the liver and lungs, apart from the brain, and show more diverse symptoms depending on their location.

HHT is an inherited disorder, and the severity of the AVMs can be mild or severe. It bears mentioning, however, that AVMs associated with HHT constitute only 5% of recorded cases and that 95% are sporadic and thus deemed as congenital. 

• Gender

Arteriovenous malformations can happen to anyone, but it is observed that they happen more often to men than women.

Although AVMs are widely accepted as congenital, new research suggests that AVMs may also be acquired.

“De novo” is a Latin term meaning “anew” or “from the beginning.” When affixed to a medical condition, it suggests that the illness isn’t congenital and has developed due to one or more factors acquired during childhood or adulthood.

A study published in 2021 identified 58 de novo arteriovenous malformations and studied their demographic data and underlying pathologies. These cases were named “de novo” because the AVMs appeared in imaging studies after previous tests showed negative results. Here are their key findings:

• The gender data is consistent with the current-known fact sheet that AVMs are more common among males (32 out of 58 or 55.17%) than females (25 out of 58 or 43.01%).
• AVMs can happen at any age. The period between the initial imaging study and the second, which confirmed the occurrence of AVMs, ranged from three months to 25 years and averaged 7.67 years.
• More than half (64.91%) of the patients diagnosed were less than 30 years old.
• The underlying issues associated with the de novo AVMs were as follows:
  • Pre-existing cerebrovascular malformations (i.e., aneurysms and cavernomas) or degenerative lesions - 22.41% of patients
  • Hemorrhagic stroke - 20.69%
  • Epileptic seizures - 15.52%
  • Brain tumors - 10.34%
  • Ischemic stroke - 8.62%
  • Moyamoya disease - 6.9%
  • Traumatic brain injury - 5.17%
  • Genetic syndromes - 3.45%
  • Liver cirrhosis - 3.45%
  • Inflammatory diseases - 3.45%
• A closer examination of the patient’s medical histories revealed that many were exposed to stereotactic radiosurgery (SRS) radiation as treatment for another pre-existing condition.

Researchers theorized that therapeutic exposure to radiation may have produced gene mutations and spurred AVM development, resulting in de novo arteriovenous malformations where there used to be none.

More research and studies about de novo or acquired AVMs are needed before we can conclusively say that AVMs are congenital and acquired. Discovering the associated pathologies for acquired AVMs can help determine their true nature, which will be helpful in determining preventative measures against arteriovenous malformations.

In the meantime, we recommend being vigilant for hemorrhage symptoms or HHT if you already experienced any underlying diseases associated with acquired AVMs in the study above.

If you or someone you know recently experienced a hemorrhage and want to rule out AVM, consult a noted neurosurgeon or get a second opinion to verify your primary physician’s findings.

The clinic of Dr. Aaron Cohen-Gadol can help. Dr. Cohen is an expert in taking on the most complex and challenging neurosurgical cases and favoring minimally invasive surgical treatments for his patients. If you or yourself want to know more about AVMs in the brain, Dr. Cohen is the best specialist to consult about it.

Schedule an appointment with Dr. Cohen or request a second opinion via our website.

• The Aneurysm and AVM Foundation 
• AVM Research Foundation
• Brain Aneurysm Foundation 
• Child Neurology Foundation 
• National Institute of Neurological Disorders and Stroke