International Physician Update

A Safer Way to Navigate Brain A-V Malformations

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.

But now there’s hope: A team of Johns Hopkins specialists has developed a fairly 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 a recent issue of the American Journal of Neuroradiology, the team used a microcatheter to administer the sedative sodium amobarbital 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 mimicked what would occur in a brain area if blood flow was blocked by sealing the vessel with N-butyl cyanoacrylate glue.

Currently, the standard treatment is to seal off 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 postoperative brain damage, and as many as three percent of patients die, according to Kieran Murphy,  director of Hopkins’ 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 effects. 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 should help minimize the potentially disabling outcomes of this invasive procedure,” says Hopkins clinical neurology fellow Lauren Moo, co-author of the study.