Using insights into how the brain is wired, scientists are exploring better ways to help stroke and other neurologically impaired patients regain motor skills, such as walking.
One technique uses a treadmill split in two to force patients' legs to walk at different speeds, in a movement like limping. A study published June 1 in the Journal of Neurophysiology found this treatment in the short term helps rewire the brain to correct uneven walking, especially if the patient's brain receives electrical stimulation in a particular region at the same time.
Millions of individuals need physical rehabilitation each year after impairments that result from damage to the brain. Stroke survivors in the U.S. number four million, according to the National Institute of Neurological Disorders and Stroke. Only about a third get any kind of rehab, according to the 2005 Washington Behavioral Risk Factor Surveillance Survey, the large telephone survey.
There are many forms of mainstream physical rehab but no consensus about which work best for which patients. "We know it's important to be engaged and to be practicing, but we don't know exactly what you need to be practicing," says Walter Koroshetz, deputy director of the institute, which funds other trials on rehabilitation but not this one.
In traditional rehab for lower limbs, known as "overground" training, a patient practices repeated movements, whether on a treadmill or other equipment or in a pool. It can take a lot of effort to walk for people whose gait isn't smooth, and they are more prone to falls, according to Amy Bastian, director of the Motion Analysis Lab at Kennedy Krieger Institute, Baltimore.
In the study published Friday, Dr. Bastian, Pablo Celnik from Johns Hopkins University and colleagues studied healthy individuals and whether brain stimulation and split-belt treadmill training, used simultaneously, can speed up progress in smoothing out walking gaits.
Making and correcting errors is important to how the brain adapts to a new task. In split-belt treadmill training, two bands moving at different speeds induce or exacerbate errors in walking. As an individual continues to walk, studies have shown, the brain eventually self-corrects errors and evens out the gait.
In the majority of stroke patients, damage is to the cerebrum, which governs speech and thinking; the cerebellum, which governs "lower order" functions like movement, still works. In theory, that means these stroke patients should respond to split-belt treadmill training, Dr. Bastian says.
The study exposed 40 healthy participants with a mean age of 27 to two minutes of slow split-belt walking, then to a 15-minute period in which one belt went much faster than the other so that participants began to drag one foot, simulating a limp. Typically participants corrected the limp within 10 minutes.
The subjects were randomized into five groups and received a mild, noninvasive electrical current, via a cap and electrodes, running either to or away from the part of the cerebellum that controlled either the faster or slower leg. The fifth group wore the cap but got no current.
All participants adapted to the different speeds, but the ones who received electrical current to the part of the brain corresponding to the leg that eventually changes its pattern adapted faster.
A study, conducted at the University of Maryland School of Medicine and published Monday in the journal Neurorehabilitation and Neural Repair, found that a noninvasive brain-stimulation technique alone, administered to a motor region of the brain, was effective at improving gait in patients with Parkinson's disease.
Researchers question how much effect new rehab treatments have, how long it will last and whether lab training translates to the real world, says Edward Taub, a researcher at the University of Alabama at Birmingham, who wasn't involved in Friday's work. In an unpublished study of post-stroke patients, Dr. Bastien and collaborators showed that four weeks of split-belt treadmill training led to improved walking gait for three months.
T. George Hornby, professor in the department of physical therapy at the University of Illinois at Chicago, says it's rare for a therapist to push a patient to the point of nearly falling. But making such errors can help accelerate treatment if the patient can learn to correct them. In a preliminary study he conducted in 22 post-stroke patients using error-type training, he found 15 consecutive days of intense treatment yielded as much improvement as what patients got from intense conventional treadmill training two to three times a week in 10 or more weeks. He currently is recruiting post-stroke patients for a randomized, controlled trial comparing error-type treatment to intensive treadmill training.
(Source: online.wsj.com)
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