Stroke’s Global Burden of Death and Disability Highlights Need for Awareness, Prevention, and Rehabilitative Strategies


by Brenda Patoine

December, 2013

BRIEFING PAPER

Ann Whitman                                                                                  
(212) 223-4040
awhitman@dana.org
           

Few medical conditions, neurological or otherwise, exact a greater public-health toll than stroke, a fact underscored by a new published report on the global burden of stroke. An acute brain injury that may begin insidiously years prior, stroke is now the second leading cause of death and the third most common cause of disability worldwide. Nearly 17 million people in the world will have a first stroke in the next year, and 33 million people are stroke survivors.

In the U.S., stroke is the No. 1 cause of serious long-term disability. Approximately 800,000 strokes occur annually in this country, and about 130,000 people die annually from stroke. The risk of stroke has decreased by roughly 70 percent in the U.S. since incidence was first tracked in the mid-1900’s, a downward trend that has not plateaued, suggesting there is still room for improvement. Stroke risk factors are well known, and experts estimate that 80 percent of strokes could be prevented with better management of hypertension, blood lipids, and glucose.

Getting Aggressive About Prevention

“Most people believe there could be substantial, dramatic stroke reduction if we just really aggressively managed the risk factors we currently know about,” says Walter Koroshetz, M.D., deputy director of the National Institute for Neurological Disorders and Stroke and a member of the Dana Alliance for Brain Initiatives. “In many diseases, you need a major scientific breakthrough to make a difference. That’s not true with stroke.”

In the U.S., as in many countries worldwide, hypertension is the major driver of stroke risk, Koroshetz says, so early detection and treatment of high blood pressure is a priority. NIH-sponsored clinical trials have shown that aggressive management of blood pressure, blood lipids, and lifestyle factors such as diet and exercise can cut stroke risk in half. The message from these trials is that it isn’t enough to merely prescribe drugs and send patients home; the best results are seen when patients are closely followed by healthcare professionals who proactively contact patients to ensure they are following doctors’ recommendations.

Opening the Window for Acute Treatment

Public-health advocates have tried for years to drive home the message that strokes require immediate medical attention, ever since a treatment became available that could help some people with ischemic stroke, which occurs when blood flow to part of the brain is restricted by a clot or narrowed blood vessel. Tissue plasminogen activator, or tPA, is still the only drug approved for treating acute stroke, but its use is severely limited, largely because published guidelines call for it to be administered within three hours of stroke onset for most patients. Some experts have criticized these guidelines and are calling for them to be revised.

Dana Alliance member Louis Caplan, M.D., a pre-eminent stroke expert and senior neurologist at Harvard’s Beth Israel Deaconess Medical Center, is among those who believe the three-hour window for tPA use is a false limitation. He says it is based on decades-old research that excluded too many patients and relied on technology far less advanced than what is now available.

“The whole idea that you turn from a queen to a pumpkin when the clock strikes three [hours] is ridiculous,” Caplan says. The guidelines for tPA treatment are meant to “provide a recipe” for healthcare practitioners who have no experience treating stroke, he says. The real focus, he argues, should be on getting patients to stroke centers that have the personnel and technology to evaluate them properly and decide on a best course of action based on the patient’s complete clinical picture. Time since stroke onset is just one piece of the puzzle, and may not be the most important one, Caplan contends.

Public Awareness Still Lacking

The advent of tPA has triggered a system-wide reorganization of stroke urgent care that is still evolving nearly 17 years later. For example, specialized stroke centers have been established where expert care, along with the tools and technologies for swift, accurate diagnosis, is readily available. A tiered system based on minimum requirements, much like the system that designates hospitals as Level 1-4 trauma centers depending on their capabilities, is being put in place for stroke care as well, so that patients can be transported to the most advanced center in their area. While there have been vast improvements, a number of obstacles remain. Primary among them is public awareness, experts say.

“Public knowledge about stroke is still very low,” says Caplan. “This is the more difficult problem, because a lot of people don’t know they’ve had a stroke.”

Part of the problem is that stroke symptoms are so variable depending on what part of the brain is involved. People may recognize paralysis on one side of the body as a stroke, but they are less likely to realize that tingling in the hand or speech problems could be a stroke.

“As opposed to a heart attack, where everyone knows that chest pain means get to a hospital, with stroke, people often think they need to rest, so they go and take a nap,” Koroshetz says.

Better Rehab Through Brain Science

The Global Burden of Disease report underscores the dichotomy between richer, developed countries like the U.S., where the majority of people who suffer a stroke survive, and poorer, developing countries where people are more likely to die from a stroke. While cutting stroke deaths is a major global-health goal, better recovery and rehabilitation strategies are desperately needed to address the ever-growing population of stroke survivors who struggle to function with varying degrees of disability.

“We have in the U.S. alone 800,000 people who have a stroke each year. So the question becomes, what can be done to return functional recovery to those patients?” says Koroshetz. “That’s where the really interesting science is, because it intersects with the area of neuroplasticity–how the brain learns to function for a particular purpose and how it rewires itself to get lost function back.”

Until recently, Koroshetz says, “rehab studies have been few and far between.” As neurology and neuroscience have become more involved in stroke recovery, more rigorous scientific investigations are being undertaken. Caplan says this trend is driven in part by advances in brain imaging, including CT and MR angiograms to analyze blood flow in the brain, functional MRI to investigate changes in brain activity, and diffusion tensor imaging (DTI) to examine how white-matter tracts in the brain might be involved.

“Once you have the ability to localize where the brain lesion is, whether there is vascular blockage, and what part of the brain is doing what, you can then examine someone acutely and follow them over time, so you can tell how those things change and how other parts of the brain may be taking over for injured areas,” says Caplan.

Brain Recovery Not Passive

Armed with such investigational tools, neuroscience has already revealed some fundamental principles of recovery in the brain. “The general rule, at least in the cortex, is that somehow the brain recovers function after an initial injury, whether it’s a stroke or some other lesion,” says Koroshetz. “Now people are studying how that happens, and the hope is that we can translate that to therapeutic strategies.”

One key finding already, Koroshetz says, is that recovery from injury is not “passive.” Rather, it requires enhancement by active exposure to sensory stimuli or motor practice. He points to the LEAPS study, which was the first large randomized, controlled clinical trial that investigated recovery of locomotor function in people who had had a stroke. The NIH-funded study compared two fairly intensive therapies: treadmill walking vs. strength and balance training performed at home with a physical therapist. A third group, serving as controls, received “standard of care”–whatever physical therapy or rehab they were getting as part of their regular medical care.

‘Standard of Care’ Substandard?

The results showed that both intensive therapies–treadmill walking and in-home PT–were equally as effective in restoring locomotor function, but people who received standard of care were considerably worse in their ability to walk. After six months of treatment, when most people’s recovery plateaus, the standard-care patients were transferred to one of the intensive therapy groups, where their walking ability also improved.

“The takeaway message from LEAPS is that our standard of care for rehab is really not acceptable,” Koroshetz says. “People can benefit from much more intensive practice.” Moreover, since treadmill walking wasn’t any better than balance and strength training in the home, he says it may not be the type of therapy that’s important so much as the intensity level. 

That conclusion is also supported by the EXCITE trial, the first multisite, randomized, controlled rehab trial funded by the NIH, which evaluated upper extremity functional recovery in stroke survivors. The study examined constraint-induced movement therapy, in which the less impaired arm or hand is constrained through the use of a padded mitt that restricts hand usage while the patient repeats a motor task with the other, more impaired arm.  The regimen was intensive but condensed, with therapy continuing up to 6 hours per day for two weeks straight.  An analysis of results showed significant improvements in function two years after therapy was completed, even in patients who didn’t begin the therapy until 15 to 21 months after their stroke.

These results are in line with the neuroplasticity literature, Koroshetz says, which consistently shows that practice and stimulation drive the brain’s rewiring. “It just tells you that practice works,” he says. “How do you improve function? You practice.”