Published: Oct. 17, 2006
Updated: Mar. 26, 2010
Its very name suggests something impossible to control: A swift, unavoidable assault. Perhaps that’s part of the reason that stroke has often inspired a fatalistic response among both the general population and the health care professions. The conventional wisdom has been that stroke just happens, and that survival and recovery are simply additional strokes -- of luck.
The truth, however, is turning out to be quite different: Not only is stroke eminently treatable, it’s surprisingly preventable.
“There’s been a revolution in the area of cerebrovascular disease in recent years,” says Larry B. Goldstein, MD, director of the Duke Stroke Center. “A tremendous amount of research over the past decade has allowed us to be incredibly more proactive in stroke prevention as well as in acute interventions.”
The timing couldn’t be better. The third leading cause of death in the U.S., stroke affects an estimated 790,000 Americans each year, and kills more than 140,000 of them.
Certain parts of the nation are hit harder by stroke than others, notably the eight Southeastern states known as the “stroke belt,” where stroke death rates significantly exceed the national average. North Carolina is one of the states so severely affected by stroke that it’s considered, along with South Carolina and Georgia, to be part of the belt’s high-risk “buckle.”
Stroke occurs when blood vessels carrying oxygen and other nutrients to a specific part of the brain suddenly burst or become blocked. These blockages halt the flow of blood, cutting off the brain’s oxygen supply, and brain cells begin to die.
Cells immediately in the affected region die soon after the stroke starts, followed by a chain reaction that endangers brain cells in a larger, surrounding area of brain tissue. This cascade of cell death progresses rapidly, making the window of opportunity for truly effective acute stroke treatment less than three hours.
That’s because, as Dr. Goldstein says, “Time lost is brain lost.” When brain cells die, abilities controlled by the corresponding area of the brain -- such as speech, memory, and movement -- are diminished or lost.
The type and severity of these losses depend on where in the brain the stroke occurs and on the amount of brain that has been damaged. Someone who has a small stroke affecting certain areas of the brain may experience only minor effects, such as weakness in an arm or leg. A larger stroke may leave its victim mute or paralyzed on one side; very severe strokes can be fatal.
Some strokes really do seem to come from out of the blue, taking the form of a catastrophic brain hemorrhage caused by bursting of an abnormal blood vessel near or inside the brain. But most strokes are due to blood vessel blockages associated with atherosclerosis, a disease in which rough, fatty deposits build up on the walls of the arteries and project into the bloodstream.
The key culprit in coronary artery disease, atherosclerosis -- when it occurs within cerebral blood vessels -- is also responsible for thousands of strokes every year. These devastating blockages can also occur when atherosclerotic material within the heart breaks loose and clogs a brain blood vessel.
The atherosclerosis connection means that, just as in heart disease, certain risk factors for stroke can be identified. As in heart disease, these risk factors include both things you can’t do anything about -- like your age, gender, family history, and ethnic group -- and those you can.
While strokes can occur at any age, the risk of stroke doubles for every decade of life over age 55; two-thirds of strokes occur in persons over 65. The disease is 25 percent more common in men than in women (but women account for 60 percent of all stroke deaths). African-Americans have a higher rate of stroke than Caucasians. Another risk factor is atrial fibrillation -- irregular beating of the upper chambers of the heart -- which may affect as much as 6 percent of people over 65.
According to Goldstein, those non-modifiable risk factors should be taken seriously, precisely because they’re out of your control. “They indicate you need to take more aggressive measures than you would otherwise,” he says. “If, for example, a first-degree family member such as a parent, brother, or sister had a stroke under 65, they’re not the only one at risk for future events. So are all their close relatives.”
Even if you don’t have any non-modifiable risk factors for stroke, Goldstein recommends taking every possible precaution to head these calamitous events off at the pass. “You simply can’t start prevention early enough,” he says. “Between lifestyle interventions and drug therapy, the key is to take a comprehensive approach to preventing both new and recurrent strokes.”
For anyone who wants to avoid stroke, smoking -- the single least healthful habit anyone can have -- is the first thing to give up. It creates blockages in the body’s blood supply, makes blood more prone to clotting, and damages the lining of the arteries, which is associated with atherosclerosis.
What’s more, Goldstein says, “Second-hand smoke also appears to increase the risk of stroke -- which means smokers are putting family members at risk.” The good news is that, when you do stop smoking, your risk for stroke decreases to that of a non-smoker after just two to four years.
The next step is to get your weight under control. The healthful diet that helps you achieve that also seems to lower the risk of stroke on its own merits. A varied diet including three to five servings of fruit and vegetables each day -- at least three of them vegetables -- is important, as is avoiding saturated fats and trans-fatty acids in particular.
If you’re not sure what your blood pressure is, get it checked; if it’s high, get it treated. Ditto with cholesterol; statin drugs can minimize high “bad” cholesterol and recent research suggests that a healthful vegetarian diet that allows high-quality fats (such as almonds) in moderation can do nearly as good a job.
The details of such recommendations and guidelines are adjusted periodically, says Goldstein, and newer “emerging” risk factors are also being scrutinized for their association with stroke. These include blood factors such as an amino acid called homocysteine (which can be lowered with B vitamins), a cholesterol-like compound called lipoprotein A (which requires special treatment), and c-reactive protein, a marker of inflammation.
Still, he says, the basic message is clear: For the best chance at a long, healthy life free of stroke, get your weight, blood cholesterol, and blood pressure under control, and get some regular exercise.
Sometimes, medications to lower cholesterol, reduce blood pressure, or minimize the likelihood of blood clotting can be used to complement these healthy lifestyle changes and further reduce stroke risk. Yet they’re often drastically under-utilized. For example, says Goldstein, “Many people with atrial fibrillation could benefit from warfarin, an anti-coagulant [blood-thinning and clot-preventing] drug, yet only 40 to 50 percent of them are getting it.”
As for the aspirin a day taken by a growing number of people to prevent heart attack, Goldstein says that it can help against stroke as well in people who have had symptoms of stroke: “It’s a cheap, easy way to discourage blood clotting.”
For certain people at especially high risk, the best insurance against stroke may come in the form of surgery. A procedure called a carotid endarterectomy can clear dangerous atherosclerotic buildup in the carotid artery, which supplies the brain. Angioplasty and stenting of vessels in the neck and brain and cerebrovascular bypass graft surgery, which creates arterial detours like those often used to treat severe coronary artery disease, are other surgical prevention strategies against stroke that are still being studied and available at only a few institutions nationwide, including Duke.
For a condition with such devastating effects, stroke can start small.
About a third of all strokes are preceded by one or more "mini-strokes," known as transient ischemic attacks (TIAs). Caused by temporary interruptions in the brain’s blood supply, TIAs can occur days, weeks or even months before a stroke. They don’t last long -- anywhere from a few minutes to several hours -- but their appearance is ominous. “If you’ve ever experienced a stroke or TIA, you’re at increased risk for having a stroke in the following weeks or months,” Goldstein says. “TIA is a warning sign that needs to be taken very seriously.”
For both stroke and TIA, the most common symptoms are sudden weakness, numbness or paralysis of the face, arm or leg (especially on one side of the body); loss of speech or trouble talking or understanding language; sudden loss of vision, particularly in only one eye; sudden, severe headache with no apparent cause; and unexplained dizziness, loss of balance or coordination (especially if associated with any of the above symptoms). Other less common symptoms include very sudden nausea, fever, and vomiting, or fainting, confusion, and/or convulsions.
Doctors’ ability to quickly pinpoint the precise location of a stroke and determine the extent of damage is crucial to making appropriate treatment decisions during a stroke emergency. Duke is one of the few places in the country that has more than a dozen state-of-the-art brain diagnostic devices available to obtain in-depth information about a stroke or TIA. These highly sensitive tools are also of critical importance in diagnosing blood vessel abnormalities that place a patient at high risk for stroke.
Once a TIA or full-blown stroke has been diagnosed, a number of different therapies may be employed. Because much of the damage caused by a thrombotic or embolic stroke occurs in the first hours, much research has been focused on the use of clot-dissolving drugs (such as tissue plasminogen activator, or tPA) and medications that make the brain more resistant to stroke (neuroprotective agents).
Not every hospital offers these interventions, however, so if you live in a more rural or smaller metro area, you might want to find out how your community hospitals treat stroke should you or a loved one ever need stroke care.
After the acute phase of a stroke comes a period of recovery. Once thought to be complete after six months or so, stroke recovery is now believed to continue for years after the event. “There’s a lot of compelling research going on in stroke recovery,” says Goldstein. “A growing body of evidence suggests that the brain can literally rewire itself and create new neural connections to affected parts of the body.”
Therapeutic strategies now being studied at Duke and at its health system rehabilitation facilities within Durham Regional Hospital include the use of certain drugs that may enhance post-stroke recovery. “We’re currently leading an NIH-supported clinical trial to find out if these medications really work,” Goldstein says.
Other new approaches include robot-assisted upper-limb therapy, which assists or resists elbow and shoulder movements in three-dimensional space; constraint-induced therapy, which confines a normal limb so that the weaker limbs must be used to perform tasks; and mirror therapy, in which a mirror image of a healthy limb seems to “fool” the brain into reestablishing contact with the hidden, weakened one.
Ultimately, what’s perhaps most striking about stroke is that it responds as well to routine, common-sense preventive strategies as it does to rapid state-of-the-art treatment. “We need to get both of those messages out,” says Goldstein. “If we do our job right, we’ll not only deliver more effective emergency care, we’ll have fewer stroke patients showing up in the emergency departments in the first place.”