An AVM or an arteriovenous malformation, is a tangle of blood vessels within the brain.
Normally, blood travels to the brain by arteries and spreads out once it gets to the brain through small networks called capillaries which provide blood to the brain. It then pools back together into veins which take the blood back to the heart.
Arteries are thick as they have to withstand strong blood pressure that comes directly from the heart. Veins, on the other hand, are very thin walled because they see very low blood pressure
after the blood travels through the capillaries.
In an AVM, that capillary bed has been replaced, creating a direct connection between the arteries and the veins by some abnormal blood vessels. Similar to the veins, these blood vessels are relatively thin walled. There’s a high risk of bleeding or rupture because these irregular blood vessels are seeing the high blood pressure coming directly from the arteries.
AVM’s can present one of two ways: we either find them when they are unruptured (which means they haven’t bled yet) or after they have ruptured (which means they have bled). Depending on how they present, they are treated in different ways.
There are 3 ways to treat an AVM.
The first is called Gamma Knife radiosurgery. A patient receives a single dose of radiation that works to shrink the AVM over time, but it can take two years to fully treat the lesion. This treatment is a reasonable option for an unruptured AVM.
Another option is embolization, which is blocking the AVM from the inside. The surgeon snakes his or her way up from either the wrist or the groin into the AVM and injects it with substances that will block it off.
The final option for treating an arteriovenous malformation is surgical resection. This involves making an incision in the scalp and a small window in the bone; finding the AVM itself. The arterial feeders to the tangled blood vessels are then removed and the vein draining into the AVM is removed. The malformation is taken out in its entirety and it’s cured at the time of surgery.