Stroke
Wingspan Intra-Cranial Stent, Alternative to Brain Surgery?
By University of Michigan Health System
Jul 4, 2006, 00:15

New technologies, delivered to the brain via the bloodstream and guided by more powerful brain scans, are making it easier to clear up clogged blood vessels inside our heads, or shore up weakened ones.

It�s brain surgery without the surgery, also called minimally invasive, or endovascular treatment. And according to University of Michigan Health System doctors who perform such procedures on hundreds of patients a year, it�s allowing many patients to reduce their risk of a stroke � including those who wouldn�t be able to withstand a brain operation.

One of the newest options is the first device designed to help doctors open up clogged blood vessels in the brain. Called the Wingspan intracranial stent, it�s a tiny wire mesh tube that can be fed into the body through an incision in the leg, threaded up through the blood vessels in the chest and neck, and inserted into the brain.

The U-M team is one of the first in the United States to treat patients with this device, which can help people who have not yet suffered a stroke or who have had a �mini-stroke�, also called a TIA. It�s designed for patients with a condition called intracranial stenosis, or cerebral atherosclerosis: a narrowing or hardening of the arteries in the brain. The condition is linked to the same factors � high cholesterol, high blood pressure, smoking, obesity, diabetes � that play a role in many heart attacks. Just like in the heart, the condition causes narrowing or blockage in brain blood vessels.

�This offers us the first option designed specifically to treat this condition,� says Joseph Gemmete, M.D., director of interventional neuroradiology at U-M and an assistant professor of radiology. �This is a very high-risk condition, with patients facing as much as a one-in-three chance of suffering a stroke in the next year. We had been using stents designed for arteries in the body, but this is specifically for the brain.�

Another common cause of stroke is burst blood vessels, which cause massive bleeding (hemorrhage) inside the brain and rob the brain of oxygen, causing a stroke. The vessels usually burst open at weak spots in their walls, often at a bulging spot called an aneurysm or a tangled web of abnormal vessels called an arteriovenous malformation or AVM.

"These, too, can be treated without open surgery, says U-M neurosurgeon B. Gregory Thompson, M.D., head of cerebrovascular and endovascular neurosurgery at U-M who performs both open-cranial microsurgery and minimally invasive endovascular procedures.

�An aneurysm is a ballooning, a little weak spot like one on a tire when it�s about to blow. When aneurysms rupture, about half the patients don�t survive. That�s why we would really like to prevent the first hemorrhage,� he explains. �Traditionally, they were treated with open surgery, through the skull. But now we can offer many patients a minimally invasive treatment using coils and stents.�

As many as 30 percent of all brain aneurysm patients treated through U-M�s Endovascular Surgical Neuroradiology program receive minimally invasive procedures, a dramatic increase in just the last few years. The opportunity to have the condition remedied without surgery is a tremendous relief to many patients, says Thompson, especially those whose families seem �cursed� by an inherited risk for aneurysms that have killed many of their relatives suddenly and without warning.

�Because it�s a relatively new technique, and the technology is changing very rapidly, techniques that we didn�t have even three years ago are now available to make endovascular treatment safer than ever,� says Thompson, an associate professor of neurosurgery who directs the U-M Neurovascular Program. �An example is the use of stents, which bolster the coils that we place inside the aneurysm to seal it off. They reduce the risk of a stroke related to the coils.�

Another new technology just became available for patients with AVMs, which occur in more than 300,000 Americans and can also rupture suddenly and cause permanent disability or death.

This new treatment is a liquid material called Onyx that can be injected directly into the AVM through a tiny tube that is fed into the brain through the bloodstream. The liquid quickly solidifies and cuts off the blood flow into the AVM, reducing the risk of rupture. It can also be used in aneurysms. After the procedure, the AVM can be more safely removed in open surgery if needed.

More than two dozen AVM patients and over a hundred patients with aneurysms come to the U-M for minimally invasive procedures each year, including patients who might otherwise have had to live with the knowledge that they had the condition but couldn�t withstand surgery to correct it. �One of the real advantages to endovascular treatment of aneurysms and AVMs is it allows us to treat patients who, because of their age or other medical conditions, could not have been treated before,� says Thompson.

Another major cause of stroke is blockage or narrowing of the carotid arteries, the relatively large vessels that carry blood from the neck into the lower part of the brain. Many people with carotid artery disease, also called carotid artery stenosis, don�t know they have it until they have a mini-stroke or stroke. Others are fortunate enough to catch it early by having an ultrasound scan of their neck that reveals the blockage.

Often, drugs and lifestyle changes like quitting smoking and eating healthier can help open up the carotid arteries again. But when one or more carotid arteries is severely blocked, some sort of intervention is needed. Just like in the brain, there are minimally invasive and open-surgical procedures available to open up the blockage and keep it open.

The minimally invasive approach to treating carotid artery disease has helped many patients who cannot withstand surgery, reducing their risk of stroke. But it has not yet been proven to be better than open surgery (called an endarterectomy) in patients who are able to have surgery.

So, a new research trial being conducted at U-M and sites around the U.S. and Canada is trying to determine what advantages and disadvantages the two different treatments might have for patients who are candidates for either option. Called the CREST trial, it assigns patients to one or the other treatment randomly, and will track their progress for the next four years.

At U-M, the CREST trial involves interventional neuroradiologists like Gemmete, and surgeons from the Section of Vascular Surgery. Patients between the ages of 18 and 80 who have been diagnosed with carotid artery disease are now being enrolled. The study is being funded by the National Institutes of Health, to determine the answer to a question that will become increasingly important as more Americans grow older and experience a narrowing of their carotid arteries due to a lifetime of unhealthy eating, overweight, high blood pressure, smoking and/or diabetes.

Even as the newest technologies for minimally invasive brain treatment are tested and used in patients, new ones are on the horizon, says the U-M team. Emergency treatments delivered directly to the brain during a stroke, new devices and substances for blocked or weakened blood vessels, and better brain imaging are all emerging as potential tools for preventing strokes or reducing the devastating disability and high risk of death that they pose.

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