What is Brain AVM?
In this video, Dr. Karimi discusses Brain AVM or brain arteriovenous malformation, shedding light on this condition and its treatments that should only be done by experienced vascular neurosurgeons who are skilled in all available treatments.
What is a brain AVM?
An AVM is an arteriovenous malformation which is a tangle or nest of blood vessels that can occur anywhere in the body.
Brain AVMs are no different.
The same tangle of blood vessels but they tend to occur within the substance of the brain.
They are high flow carrying pressurized blood from the heart directly into the venous part of the AVM and then the blood travels back down to the heart.
Since that blood is under pressure and flowing through veins that are not designed to carry such pressure, there is a risk of AVMs bleeding in the brain and a brain AVM hemorrhage is always a very serious event.
We think around 1% of the population has a brain AVM and the vast majority of those patients are asymptomatic.
No symptoms at all.
No headaches, no seizures but in some patients they can cause those initial symptoms and ultimately be discovered on an MRI or CAT scan of the brain.
In those cases we’ll typically recommend a diagnostic angiogram to be done that’ll give us the best view of the blood flow to the brain, blood flow to the AVM, the exact size, the exact shape, what are the arteries going to the AVM, what are the veins draining the AVM and those are really critical in determining the best safest treatment strategy going forward.
Brain AVMs do have a risk of bleeding.
We look at that as a yearly probability of bleeding which we feel is about 2-4% risk of bleeding per year.
There are some factors that convey a higher risk of bleeding such as a very small AVM.
An AVM that contains what we call intranidal aneurysms which are actual aneurysms within the AVM itself.
Those have a higher risk of bleeding.
Arteriovenous malformations that have only one vein draining all that blood flow also have a higher risk of bleeding and AVMs in the back of the brain, the cerebellum or the brain stem also have a higher risk of bleeding.
There is some data to suggest that pediatric AVMs that occur in the very young patients also have a higher risk of bleeding compared to adult brain AVMs.
What happens if an AVM bleeds?
Well, bleeding from a brain AVM is a life-threatening condition.
There will be severe symptoms, headaches, nausea, vomiting or if the amount of bleeding in the brain is large, patients can have weakness, paralysis or in severe cases, confusion, even a coma if there’s severe bleeding in the brain.
Bleeding from a brain AVM can be fatal in about 10% of cases and in about 40% of cases permanent disability will result.
Once an AVM has bled, the risk of it rebleeding is elevated.
Some data suggests it’s about 6% within the first 6 months and then about 4% yearly after that.
There are two basic ways to treat a brain AVM.
Option one is to just observe, don’t offer any treatment and monitor it over time for any symptoms, any signs of bleeding or any growth over time.
The second way to treat an AVM is to use one of multiple tools to cure the AVM and ultimately lead to zero blood flow through the malformation for the rest of the patient’s life.
There are several treatment options available to accomplish that.
One is to perform embolization which is an endovascular procedure where we will infuse glue or a special type of glue into the malformation into the arteries feeding it to shrink it down and decrease the blood flow to the AVM.
That’s called embolization.
Another option for brain AVM treatment is to remove it surgically, especially for AVMs that are on the surface of the brain that are small in size in a safe area of the brain, these can be approached surgically with really good safety and really good results.
The third option for brain AVM treatment is radiation.
Typically that’s called stereotactic radiosurgery (SRS) where a very precise dose of radiation is delivered to the AVM in one treatment and will cause the AVM to shrink and ultimately disappear usually within 2 to 3 years.
A physician who treats a brain AVM should be comfortable with all three treatment options and be able to perform those themselves personally in order to affect the best outcomes.
