And the good news! Doctors can do more than ever to find and fix the problems that cause many strokes — before a stroke ever happens. And they can do it without ever having to open up the skull.
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.
Still, the doctors say, more information is needed on how durable these treatments are, compared with the handiwork of an experienced surgeon in an open-skull operation. Only time will tell. But in the meantime, these new options are giving new hope to those who might not have had any.
Facts about strokes, aneurysms, AVMs, and carotid artery disease, and their treatment:
• A stroke is the loss of brain function due to an interruption in the flow of blood to all or part of the brain. Strokes are the third leading cause of death in the United States, and a leading cause of permanent disability.
• There are two kinds of stroke: Ischemic, caused by a clot that has traveled to the brain or within the brain and blocked the flow of blood, and hemorrhagic or bleeding, caused by the rupture of a blood vessel within the brain.
• Mini-strokes, or TIAs, occur when a temporary decrease in blood flow occurs because of a blockage or small blood leak. They usually last a few minutes or hours, and those who survive them are far more likely than other people to have a full-blown stroke.
• Symptoms of strokes and mini-strokes come on suddenly. They include loss of control over a part of the body, numbness, partial blindness, and loss of ability to speak or think clearly.
• Ischemic strokes can be caused by narrowing, hardening or blockage in the blood vessels within the brain (cerebral atherosclerosis), or leading to the brain (carotid artery disease). They can also be caused by clots that form in or near the heart.
• Hemorrhagic strokes are often caused by the rupture of an existing weak spot in a blood vessel in the brain, either an aneurysm (bulging weak spot) or arteriovenous malformation (tangle of abnormally formed blood vessels), also called an AVM. Both can run in families.
• Open-skull surgery is still the standard for treating most of these conditions, but not all patients can withstand surgery because of their age, their other health conditions, or other reasons. For them, and increasingly for other patients, minimally invasive procedures that don't require the skull to be opened are being offered at major hospitals.
• People who have a family history of strokes, or of aneurysms and AVMs, should talk to their doctors about having screening tests and brain imaging that could determine their risk of a stroke. The same is true for people who have suffered a TIA, and people who have already had heart- or leg-bypass surgery.