March 1, 2002
MEDIA CONTACT: Gary Stephenson
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Cognitive Testing Reduces Risks of Procedure for Brain Arteriovenous Malformations

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Imagine dropping a bowl of spaghetti. That's what AVMs (arteriovenous malformations) look like in the brain -- dense clusters of twisting and turning blood vessels that look more like a wrestling match among a hundred small snakes than part of the circulatory system. Many patients don't know they have one. Some have crippling headaches. For the more unfortunate, the AVM ruptures, causing brain damage or death.

Now, a team of Johns Hopkins specialists has developed a relatively simple and safe way to locate the right vessels to surgically seal off, or embolize, greatly reducing the risk of causing inadvertent damage to vital brain tissue.

In a study of 29 procedures performed on 14 patients, published in the March edition of the American Journal of Neuroradiology, the scientists used a microcatheter to administer sodium amobarbital (a sedative) one at a time to each of the vessels supplying blood to the AVM. By anesthetizing each area of the brain fed by each vessel, they essentially mimicked what would occur in a particular brain area if blood flow was blocked by sealing the vessel with N-butyl cyanoacrylate glue.

Currently, the standard treatment is to seal off the feeder vessels to the AVM with the glue without physicians being able to tell in advance if the vessels they are blocking will cause irreversible damage to the brain tissue fed by the vessels. Seven percent to 39 percent of patients experience post-operative brain damage and as many as 3 percent of patients die, according to Kieran Murphy, M.D., director of Hopkins' interventional neuroradiology program and one of the study's authors.

"This approach represents a major improvement in treatment," Murphy says. "It provides a relatively easy and accurate way to pinpoint the vessels feeding the AVM that can be safely embolized, and more importantly, those that need to be left alone in order to avoid brain damage."

Testing revealed that in 12 of the 14 patients in the study, the targeted feeder vessels were not vital to brain function and could be treated with minimal ill affects. However, in two patients, testing revealed that blocking certain feeder vessels would cause significant neurological damage. Armed with this advance warning, the clinicians avoided embolizing these critical vessels and were able to navigate the microcatheter into other vessels that further testing revealed could be more safely embolized.

"Based on our study, we think that widespread use of this technique by clinicians trained in cognitive assessment should help minimize the potentially disabling outcomes of this invasive and irreversible procedure," says Lauren Moo, M.D., a clinical fellow in Hopkins' Department of Neurology, and co-author of the study.


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