An AVM (arteriovenous malformation) is a tangle of blood vessels with a higher rate of bleeding than normal blood vessels, an abnormal connection between veins and arteries in the central nervous system. AVM areas in the brain tissue lack the tiny capillaries needed for dispensing a healthy amount of oxygen through the blood. Brain AVMs cause devastating damage when they hemorrhage.
Brain AVMs affect less than 1% of the general population and are usually discovered when a person is between 20 and 40 years of age, although many babies are born with AVMs.
AVMs often do not cause any symptoms, but can sometimes cause epilepsy, headache and dizziness.
AVM areas are diagnosed using imaging tests, such as:
AVM Treatment Options
AVM treatment depends on the size and location of the AVM. Sometimes the best strategy is to monitor the AVM if symptoms are not severe or the AVM is discovered later in the individual's life.
However, when an AVM hemorrhages there are several treatments to stop the bleeding and prevent another hemorrhage.
A small plastic tube, or catheter, is inserted through the groin and is guided up to the brain vessels and into the AVM. A glue, non-reactive liquid, is injected into the AVM. The adhesive material hardens as it is injected and blocks the blood flow through the AVM. If the AVM is larger in size, AVM embolization must be done in stages to ensure that all of the AVM is blocked off. AVM embolization is performed with the patient under general anesthesia.
Doctors often recommend AVM embolization prior to other AVM treatment options; embolization can reduce the size of the AVM and make it more responsive to radiation or suitable for surgical removal. AVM embolization often does not completely block the hemorrhage and must then be combined with other treatments after the AVM has been reduced in size. Once the AVM's blood flow is reduced through embolization, surgical removal is faster and more successful.
AVM Radiation Treatment
For smaller AVMs, x-rays are used to thicken the blood vessels of the AVM and cut off the hemorrhage. The AVM often requires about 2 years to fully clot, and the risk of bleeding persists until the AVM has been completely eliminated.
AVM Surgery (Resection)
The neurosurgeon opens the patient's skull in order to see the AVM and clip the blood vessels that feed into it, in order to remove the AVM from the surrounding brain tissue. The arteries supplying the surrounding brain tissue are left intact; only scar tissue is removed with the AVM.
Surgically removing the AVM cures the patient immediately. AVMs do not grow back, and so the risk of bleeding is eliminated. However, only some AVMs may be safe for operation, depending on the size and location within the brain. AVM surgery is performed with the patient under general anesthesia.