New Imaging Technology Aids Brain Bypasses

Techniques allow docs to determine best candidates

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By
HealthDay Reporter

SATURDAY, Sept. 15, 2001 (HealthDayNews) -- In the vascular network ofthe body, the heart and the legs aren't the only places where bypassescan be essential.

The advanced techniques of bypass surgery are now being studied for use on the brain.

Brain bypasses -- in which a patient's own healthy blood vessels areused to circumvent vessels with aneurysms and provide a new route forblood supply to the brain -- gained some popularity in the 1980s but fell out of favor when a study indicated that patients were not better off after the bypass.

But experts have since argued that the main reason why low rates of success were previously seen was because technology was not available to determine which people had the specific vascular problems and characteristics to make them the best candidates for the bypass.

Among the primary techniques that now allow that, however, are positron emission tomography, or PET, which looks at the metabolism of the brain, and CT Xenon scans, which map the blood flow to the brain.

The techniques allow doctors to better evaluate conditions such as brain aneurysms and atherosclerosis, or hardening of the arteries, to see if they might be treated with brain bypass surgery.

"We're finding that these diagnostic tests help us select patientswho will benefit," explains Dr. Greg Thompson, director ofcerebral-vascular surgery at the University of Michigan Health System.

Thompson's hospital is one of several health centers in the countrybeing funded by the National Institutes of Health to assess theeffectiveness and long-range durability of brain bypass surgery.

Thompson says the new research is necessary because now that the right candidates can be pinpointed, effectivenessshould substantially increase.

Such candidates, he explains, would be potential stroke patients who have a lack of blood flow to the brain that might be caused by a lack of profusion in the vessels, rather than by a small clot in an artery or a piece of plaque, such as that which causes a thrombolic stroke.

"(The previous study's results) probably reflected the fact that thepatients weren't selected well -- there just wasn't the technology atthat time as there is now," he says. "Predictably, we're already showinggood results with the patients being selected with the imagingtechniques."

"We need more patients to statistically prove this, but we're veryoptimistic that this is going to be a real advance for patients," headds.

According to Dr. Anthony Furlan, a clinical neurologist at the Cleveland Clinic Foundation in Ohio, the procedure has indeed offered new hope in the medical community, but there is still skepticism.

"There are other special situations where (the) bypass is still done, such as patients with giant aneurysms or patients with carotid artery occlusion and progressive retinal ischemia. However, the procedure remains unproven and is done in only a handful of selected patients, compared to the hundreds of patients who underwent surgery in the early 1980s," he says.

Because of the complexity of performing the bypass, such surgery will probably never be as common as coronary bypass surgery, Thompson says, adding, however, that it still has an important place for the right patients.

"The operation certainly has a risk, but the key is selecting theoperation for the right person so that we can minimize risk in patientswho don't need it, and clearly maximize the benefits for those patientswho do need to restore blood flow to the brain," he says.

What To Do

Visit the American Stroke Association for more information on research and stroke issues.

Visit the American Heart Association's Heart and Stroke Guide for extensive information on stroke symptoms and treatments.

SOURCES: Interviews with Greg Thompson, M.D., director of cerebral-vascular surgery, University of Michigan Health System; Anthony Furlan, M.D., clinical neurologist, Cleveland Clinic Foundation, Ohio; University of Michigan press release

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