OHSU Doctors Use "Putty" to Prevent Hemorrhagic Stroke
10/30/03 Portland, Ore.
Oregon patients are first on West Coast to take part in clinical trial.
The patients, Joyce Turner, 68, of Kings Valley and Rob Pardee, 48, of Talent, underwent back-to-back procedures Oct. 23 at OHSU Hospital to repair aneurysms - weakened areas of an artery wall that balloon out and fill with fluid - that were at risk of rupturing. Both were able to go home the next day.
Stanley L. Barnwell, M.D., Ph.D., associate professor of neurological surgery in the OHSU School of Medicine and the Dotter Interventional Institute, performed the procedure on Turner and Pardee as part of a 120-patient clinical trial for the new Onyx Liquid Embolic System, developed by Irvine, Calif.-based Micro Therapeutics Inc. (MTI).
The Oregon Stroke Center at OHSU is one of 10 sites nationwide participating in the clinical trial for Onyx. Wayne M. Clark, M.D., professor of neurology in OHSU's School of Medicine and the Dotter Interventional Institute, as well as the Oregon Stroke Center's director, is the principal investigator of a study that will compare the Onyx procedure with other aneurysm treatments, such as coiling.
Using a catheter fed from the groin to a carotid artery in the brain, Barnwell locates the aneurysm and injects the Onyx liquid into the sac. When the liquid comes in contact with blood or body fluids, according to MTI, a solvent rapidly diffuses from the liquid, transforming it into a spongy, polymer mass that displaces the blood in the sac and seals off the defect. The solvent, dimethyl sulfoxide, or DMSO, is derived from lignin, a compound found in woody plants.
"It's a little bit like placing putty in a hole in the wall," Barnwell said. "If it stops an aneurysm from growing back, it'll be very useful."
Indeed, Turner and Pardee say, before-and-after images of their aneurysms - Turner's was in her right internal carotid artery, behind her eye under the frontal lobe, and Pardee's was in his left internal carotid artery, also behind the eye - appear to show the malformations are gone.
"My before-and-after pictures are incredible," Pardee said. "You can't tell it's there. I saw that and I thought, 'Yeah, OK, this is good!'"
Turner had a similar response: "I was amazed it made the aneurysm much smaller," she said of the procedure. "It did seem like it drew it down. Now there's just a hump instead of a balloon. It's good stuff."
Had the aneurysms burst, the likely result would have been a subarachnoid hemorrhage, a type of stroke in which blood escapes into the space between the brain and the skull, cutting off its flow to the brain.
A common treatment for an aneurysm is coiling, in which a tiny platinum coil is inserted into the sac through a catheter and deployed, restricting blood flow into the malformation. But the coil can fall out of the sac and back into the artery, and sometimes blood flow into the sac isn't fully restricted.
"Coils can stick out, and sometimes you can't get the coil where you need it," Clark said. And there is a 20 percent aneurysm recurrence rate among coiling patients.
But in the Onyx procedure, an angioplasty balloon can be used to hold the liquid inside the sac while it's being injected, preventing it from falling out before it solidifies.
"The balloon keeps it out of the artery and once it hardens, the balloon is deflated and it stays there," Barnwell said.
The other solution for an aneurysm is surgical clipping, in which a tiny metal clip is placed on the neck of the aneurysm to pinch off blood flow into the sac. But the clip stays in the patient forever, and the procedure requires brain surgery and months of recovery.
The Onyx procedure takes the same amount of time as coiling - about an hour - although it's more complex. "But once we get some experience with it, it'll become routine," Barnwell said.
Clark, who says the Onyx material looks and acts like "squishy rubber cement," believes the new procedure will have significant advantages over invasive brain surgery and, perhaps, coiling. "Whether it's better than coiling, that's what the study is evaluating," he said. "It certainly looks very promising."
In the meantime, Turner and Pardee look forward to speedy recoveries.
"From being active and doing everything to being down and not doing anything, I was ready for any cure," said Turner, who hopes the Onyx procedure helps alleviate the headaches, dizziness and fatigue she's been experiencing the last several months. "I just want my last few years to be quality time."
Said Pardee, who's also suffered from headaches: "Like the doctor says, 'Maybe it'll get rid of the headaches, maybe it won't. But (the aneurysm) will kill you someday.' Normally, you don't get a chance to take care of things like that ahead of time. It's phenomenal what they can do."