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School of Medicine
NeuroNow - Predicting life after stroke - and improving it
NeuroNow Spring 2011
Predicting life after stroke - and improving it
Date: June 1, 2011
John Krakauer’s research suggests that identifying a signature pattern in stroke patients may eventually help doctors know which patients to target for more aggressive therapies.
photo by Keith Weller
It’s no secret that recovery isn’t so simple for stroke patients. But finding the best way to help them can be tough for researchers too.
Recovery happens in two different ways, says stroke researcher John Krakauer. There’s spontaneous recovery, in which patients naturally regain some use of the affected limbs during the first three months after a stroke. Then there’s functional recovery, in which patients compensate by learning to do things in a different way—writing with their left hand instead of their right, for example.
In an ideal world, Krakauer explains, doctors and patients would try to get back as much function as possible during the spontaneous recovery period, because once that window closes, those original skills rarely return. However, understanding which patients might benefit from intensive recovery efforts, and which efforts work the best, has been unknown.
Those are the questions he and his colleagues are trying to answer. As a newcomer to Johns Hopkins—Krakauer arrived as an associate professor in January of this year—he’s continuing to pursue research he started in his previous position at Columbia University. There, in 2008, he and his colleagues had investigated whether patients’ abilities right after their strokes could predict how well they’d fare at the end of their spontaneous recovery periods.
Using a scale that assigned a total of 66 points to each limb, Krakauer and his colleagues measured 50 patients’ abilities soon after their stroke and again three months later. When impairments were mild to moderate, patients regained about 70 percent of their “missing” points. That is, if someone scored 20 points on the initial test, that person got back about 70 percent of the remaining 46 points over three months.
Patients who were severely disabled after their strokes were trickier to predict, however; some followed the 70 percent rule, but others didn’t. Looking for a better way to see how these patients might do during the spontaneous recovery period, Krakauer and his colleagues tried a new experiment. They recruited 23 stroke patients who agreed to have brain scans in a functional MRI machine within 48 hours after the stroke. The scan measures brain activity while the person performs a task. The researchers asked each patient to make, or at least try to make, a fist with the affected hand repeatedly during the scan. What they found was a signature pattern of brain activity that correlated with these patients’ abilities three months later.
The point isn’t to tell patients they will or won’t recover, Krakauer says. “We believe that if we can identify those at risk for a low response to current treatments,” he explains, “then this would be the group we’d want to target first for something aggressive and new.”
Coming up with that new treatment is his next focus. With a grant from the James S. McDonnell Foundation, Krakauer and his colleagues plan to work with patients during the magic three-month window using a combination of a robot that helps them move their affected limbs and noninvasive brain stimulation, an intervention shown in recent studies to increase skill learning in healthy subjects.
“We’re going to throw the whole kitchen sink at the brain to augment recovery,” he says.
Krakauer also hopes to recruit more talented researchers, trainees and students of all specialties—mathematicians, computer scientists, engineers, neurologists and rehabilitation therapists, for example—to tackle the problem of stroke recovery together.
“I want to create a Mecca for bright people to bring their expertise to this issue,” he says. “If we don’t make it easy for imaginative people to devote their time to this problem, we may have to wait some time until it’s solved.”
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