What is an Arteriovenous Malformation?
An arteriovenous malformation (AVM) is an abnormal connection between arteries and veins in the brain.
Normally, blood flows from arteries → into smaller vessels (capillaries) → and then into veins.
In an AVM, this normal pathway is disrupted, and blood flows directly from arteries to veins without the usual buffering system.
Why Does This Matter?
Because there is no capillary network:
- Blood flows through the AVM at higher pressure than normal
- The vessels within the AVM are often fragile and prone to rupture
Over time, this abnormal flow can place stress on surrounding brain tissue and increase the risk of bleeding.
What Causes an AVM?
AVMs are typically considered congenital, meaning they are present from birth, although they may not be diagnosed until later in life.
They are not caused by lifestyle or injury, but rather by abnormal development of blood vessels.
Do All AVMs Have the Same Risk?
No. AVMs vary significantly in:
- Size
- Location
- Structure (complexity of the vessel network)
- Pattern of venous drainage
One of the most important considerations is the risk of rupture (bleeding).
On average, AVMs carry an estimated annual rupture risk of approximately 1–3% per year, although this risk can be higher depending on specific features such as:
- Prior hemorrhage
- Deep location
- Certain venous drainage patterns
What Happens if an AVM Ruptures?
If an AVM ruptures, it can cause bleeding in the brain (hemorrhagic stroke).
This may lead to:
- Sudden severe headache
- Neurological deficits (weakness, speech difficulty, vision changes)
- Seizures
- Loss of consciousness
A rupture can be life-threatening and may result in long-term neurological impairment.
Symptoms of AVM
Some AVMs are discovered incidentally, but others may cause symptoms such as:
- Headaches
- Seizures
- Neurological deficits depending on location
In some cases, the first presentation is a hemorrhage.
Treatment Options
Management of AVMs is often complex and highly individualized.
Factors that influence treatment include:
- Size and location of the AVM
- Patient age and overall health
- Whether the AVM has previously ruptured
- Estimated risk of treatment versus natural history
In some cases, careful observation may be appropriate. In others, treatment is recommended to reduce the risk of future hemorrhage.
Endovascular, Surgical, and Multimodal Treatment
Modern treatment of AVMs may involve one or more approaches:
Endovascular Treatment
A minimally invasive, catheter-based approach used to reduce blood flow to the AVM or treat specific high-risk features. Often used as part of a staged or combined treatment plan.
Microsurgical Resection
Open surgery to remove the AVM completely, which can offer definitive treatment in selected cases.
Radiosurgery
Focused radiation used to gradually close off the AVM over time, typically for smaller or surgically challenging lesions.
Why the Discussion is So Important
There is no single best treatment for every AVM.
Some AVMs are best treated with:
- Surgery
Others with:
- Radiosurgery or endovascular therapy
And some may be best managed with:
- Observation
Choosing the right approach requires a thorough discussion of all available options, weighing the risks of treatment against the natural risk of rupture.
Our Approach
We take a comprehensive, multidisciplinary approach to AVM management.
Every case is carefully evaluated to determine:
- Whether treatment is necessary
- Which modality—or combination of modalities—is most appropriate
We work closely with endovascular and radiation specialists to ensure that patients receive a fully informed recommendation, with consideration of all modern treatment options.
Our goal is to provide a safe, individualized strategy that balances effectiveness with long-term outcomes.
View the approach