A Cerebral Arteriovenous Malformation (AVM) is a rare tangle of blood vessels in the brain that carries a high risk of hemorrhaging. Brain surgeons have found that “gluing” or blocking off the blood supply to these malformations before surgery cuts down on blood loss and patients do better. Dr. Robert Solomon along with several other neurosurgeons from the Department of Neurosurgery recently took a close look at the risks associated with this procedure, and the results were encouraging.
This process of “gluing” is actually called embolization, a procedure that starts by inserting a tube into an artery in the patient’s groin. Through this tube surgeons use tiny instruments to snake their way through arteries to the problem area in the brain. Once there, they inject a glue like substance that blocks off the blood supply to the AVM.
Embolization was first developed in 1968 and for a long time it was used as a primary treatment for AVM. Used alone however, it wasn’t as successful as surgeons wanted. Over the next couple of decades, advances in microsurgery (that is surgery with tiny instruments and the use of a microscope) enabled surgeons to completely remove the AVM.
By 1997, with the opening of the Gamma Knife Center, surgeons were using a multi step, multi-technique approach that was resulting in better outcomes and saving more lives. It became standard practice at Columbia Medical Center to perform an AVM embolization before either microsurgery or Radiosurgery with the Gamma Knife.
Of course, the story does not stop there. Medicine is ever evolving and surgeons are always looking for better ways to help their patients. One of the ways they do this is by performing retrospective studies. They look at surgical cases over a period of several years and correlate the procedures done with the outcomes. By doing this, they come up with ways to further refine and improve their methods.
Dr. Solomon and his team did just that when they looked at the outcomes of over 200 AVM patients since 1997 who underwent embolization. They knew that embolization before surgery was beneficial but they wanted to quantify any downside.
They looked to see if the procedure itself was the cause of any neurological problems. Using this data they also hoped to find any patterns that could predict the occurrence of deficits in patients to better control for them.
What they found overall was that the risk of performing the embolization itself was low. Of the 202 patients only five had any lasting deficits, that is only about 2%.
Furthermore, they were able to come up with a number of predictors for these problems. One was the size of the AVM. When the AVM was larger than 6 cm in diameter the risk increased. There was also a slightly increased risk when the AVM was smaller than 3 cm.
Another risk factor they found was the number of procedures needed to complete the job. In some cases, it was necessary to perform more than one embolization in which case the risk of poor side effect went up. But only minimally.
The last two factors that they discovered were the location of the AVM and whether or not it had a large venous drainage.
Having predictive factors like these will help surgeons choose more carefully who receives exactly what kind of treatment and improve the patients chances of a good outcome. In the end, the risk proved to be quite small and, by a long shot, didn’t outweigh the benefits of this procedure.
To learn more see their paper, Adjuvant Embolization With N-Butyl Cyanoacrylate in theTreatment of Cerebral Arteriovenous Malformations in the on-line journal Stroke (2009;40:2783)
This study was multi-institutional and included the following co-authors from the Department of Neurosuregy: Michael Sisti, MD from the Gamma Knife Center; and Robert Solomon, MD ; Sean Lavine, MD; E. Sander Connolly, MD; and Philip Meyers, MD from the Cerebrovascular Center.
Other blogs about AVM: A Protein In The Blood May Be A Clue To Arteriovenous Malformations In The Brain, How Does A Neurosurgeon Know What To Say When An AVM Patient Asks, “What Are My Chances Doc?”, One Picture Speaks A Thousand Words, These Radiosurgeons Use Two
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