A careful evaluation is key to successful treatment: the treatment team typically consist of a neurologist, neuroradiologist, neuropsychologist, neurosurgeon, and anesthesiologist. The following are treatment options to be considered:
There is some debate over whether or not to treat AVMs that have not ruptured and are not causing any symptoms. The risks and benefits of treatment need to be weighed on an individual basis, taking into account factors such as:
- General health
- Size and location of the AVM
- Additional risks of treatment
Antiseizure medications, pain relievers for headaches, and migraine medications may provide adequate symptom control for many patients.
Removing the AVM is the surest way of preventing it from causing future problems. Often surgery is recommended for AVMs that are close to the surface. If the AVM is very large or deeply located it may be too difficult or risky to remove it surgically.
Stereotactic radiosurgery is particularly useful for treating small malformations deep within the brain. This approach can often destroy the AVM without damaging the surrounding tissue. However, the success or failure of radiation often takes time to be evident called the latency period which is often two to three years. During that time the patient is at risk for hemorrhage.
This approach involves blocking the blood flow to the malformation through the placement by way of a catheter of a hardening polymer. In the event that embolization is being used in advance of surgery, at least 2 or 3 embolization procedures may be necessary delivered at intervals of 2 to 6 weeks. The procedure alone can in some circumstances provide complete blockage of the AVM and potential cure when the AVM is small.
Approximately 10 percent of AVM hemorrhages are fatal. Seizures and neurological changes may be permanent in another 10 to 30 percent of cases of AVM rupture. If an AVM bleeds once, it is about 6 percent likely to bleed again in the next year if it is not treated.
As time passes from the initial hemorrhage, the risk for further bleeding drops to about 3 to 4 percent, the baseline natural history risk. If the AVM has not bled, it is possible that it will bleed at a natural history risk rate of 3 to 4 percent per year. Some AVM’s have features that make them more likely to bleed. Untreated AVMs can grow larger over time and rarely go away by themselves.
In adults, once an AVM is surgically removed it is likely to be cured. In children surgical removal can cure the AVM but long term angiographic follow up is recommended even though the recurrence of an AVM is rare. Long-term follow-up angiography is also recommended for AVM’s that have been treated radiosurgically and have been documented to vanish on 2- to 3-year post treatment angiogram to ensure a cure.