But physicians confirmed a condition that was much more severe -- a condition that caused Floyd to progressively lose his vision over a period of years.

"I knew that something was going to have to be done," Floyd says. "If I were to lose my vision, I would not be able to see my daughter walk down the aisle one day in a wedding dress."

At the University of Michigan Health System, Greg Thompson, M.D., director of cerebral-vascular surgery, found that Floyd had developed giant aneurysms -- bulging blood vessels caused by weak vessel walls -- in both the right and left carotid arteries in his brain. The carotid arteries supply blood to about two-thirds of the brain.

"In his case, the aneurysms were so large that they extended from all the way in his neck to well up inside his head and they compressed the nerves responsible for vision," says Thompson, assistant professor of neurosurgery at the U-M Medical School.

Thompson recommended a brain bypass, a procedure that -- like a heart bypass surgery -- uses transplanted sections of the patient's own healthy blood vessels to circumvent those with aneurysms and provide a new route for blood supply to the brain.

Although the procedure was rarely performed in the past, new imaging techniques have given neurosurgeons greater diagnostic tools, allowing them to select patients best suited for the procedure. These technological advances gave Floyd a chance.

UMHS is one of a few health centers in North America being funded by the National Institutes of Health to assess the effectiveness and long-range durability of brain bypass surgery. So far, UMHS neurosurgeons are seeing excellent results.

Brain bypass surgery is most commonly used to treat otherwise inoperable brain aneurysms and to prevent stroke in patients who have had transient ischemic attacks, or "mini-strokes."

When there's a blocking or reduction of blood flow to the brain, as in a mini-stroke, the typical symptoms are weakness of one arm or weakness of a leg, loss of vision in the eye or numbness on one side of the body. All of these are stroke-like symptoms, but, in a mini-stroke, they usually don't last very long.

"Obviously, if the symptoms do last, that's a stroke -- but we're trying to avoid that by reestablishing flow before those symptoms become permanent," Thompson says. "Brain bypass is best when it's preventing stroke. It's not really used for patients who had strokes so much as it is for patients who are at high risk of having stroke."

Two relatively new tests are used to select the patients best suited for brain bypass surgery -- Positron Emission Tomography, or PET, scans, and CT Xenon scans. The PET scan is a test to look at the metabolism of the brain. CT Xenon maps the blood flow to the brain.

Thompson says that two conditions in particular may be treated with brain bypass surgery -- brain aneurysms and atherosclerosis, or hardening of the arteries. Atherosclerosis is a condition in which the vessel in the brain develops a plaque on the inside of the vessel wall that narrows it and prevents adequate flow of blood.

"Although most cases of brain aneurysms can be treated with other surgical approaches, in certain cases where the aneurysm is so large that it can't be directly repaired, we have to go around it and establish a brand new blood supply to the brain," Thompson says.

That was the case with Floyd. In the early 1990s Floyd noticed some changes in his vision. Although he thought it was fatigue, his ophthalmologist noticed abnormalities in the blood vessels going to Floyd's brain. Enlarged carotid arteries both on the left and right sides of the brain were pressing on Floyd's optic nerve.

He describes his vision as "a gray field" in his left eye and "as if someone smeared Vaseline on my glasses" in the right eye. Doctors monitored the condition closely, but then Floyd's vision started to degrade more quickly and he noticed that his field of vision was becoming smaller.

"I had to do something because I'd gotten accustomed to seeing my whole life," he says. Thompson felt Floyd was a good candidate for bypass surgery and in 1998, Floyd underwent the surgery.

Thompson says Floyd had a very good outcome. "His vision was improved in the eye with remaining vision and the artery was completely replaced successfully."

Based on the technological tools physicians now have available, they are better able to select patients who are appropriate for brain bypass, making the chance of success greater.

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

Thompson says this surgery probably will never be used in as many people as coronary bypass for blocked heart arteries, but it will have a definite population that it will serve well.

"It will be used for patients who have a clear history of neurologic symptoms and confirmation from tests that show that they lack blood flow to the brain," Thompson says.

The National Institutes of Health trial is specifically investigating the effectiveness of brain bypass in preventing stroke in at-risk patients.

"Because this procedure hasn't been done widely using the most recent selection techniques, we don't yet know the durability of the treatment, that is, how well it stands up over time," Thompson says. "That's one of the things that the trial will look at."

Facts about brain bypass surgery:

· Brain bypass is similar to a heart bypass because it uses sections of a patient's own healthy blood vessels to provide a route for improved blood flow to the brain.

· New imaging techniques such as CT Xenon and PET scans have given neurosurgeons new tools to determine which patients could benefit from this procedure.

· Symptoms of a lack of blood flow to the brain are weakness of one arm or leg, loss of vision in an eye, numbness on one side of the body. These are stroke-like symptoms that often don't last very long.

· Brain bypass surgery is an option for treatment of atherosclerosis, or hardening of the arteries that serve the brain, as well as for aneurysms of the brain. - By Valerie Gliem

Related websites:

U-M Health Topics A to Z: Stroke

U-M Health Topics A to Z: CT Scan

U-M Health Topics A to Z: Carotid Angiograph

U-M Health Topics A to Z: Atherosclerosis

U-M Department of Neurosurgery

American Stroke Association

National Stroke Association

[Contact: Valerie Gliem]

10-May-2001