News Article

Neuromuscular Rehabilitation Immediately After Stroke: the Barrett WAM™ arm
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Featured firm in this article: Barrett Technology Inc of Newton, MA

Researchers collaborating at the Rehabilitation Institute of Chicago (RIC) (Sandro Mussa-Ivaldi, James Patton, Michael Peshkin, and Zev Rymer of Northwestern University collaborating with Prof. Robert Kenyon at University of Illinois, Chicago) and a related but alternative approach at the University of Washington (led by Prof. Yoky Matsuoka) are using WAMs to perform highly effective stroke recovery during the critical first six months (acute stage) in the aftermath of a stroke.

After a person suffers a stroke, reaching for common objects like a cup of coffee can become difficult or impossible. As the person attempts to reach, the nervous system no longer perceives trajectory errors during reaching. Correcting immediately afterwards results in spilled cups and similar frustrations.

For decades physical and occupational therapists held a patient's arm to help guide them to the cup (or other task goal). The moral boost from task achievement notwithstanding, improvements appeared to be short lived.

Then researchers at RIC tried a counterintuitive approach that would challenge the best therapist. The patient grabs a gimbaled handle attached to the end of a WAM™ arm and is then encouraged to attempt to reach for the cup of coffee. As the reach is initiated, the WAM™ arm measures the (initially small) error between the actual and ideal path. It then amplifies this error by generating a lateral force away from the path in proportion to the error. The first time reaching for the cup, a patient's hand is forced grossly off path.

While this procedure might seem like a mean trick, it addresses the root problem, in which the patient's neuromuscular system has lost the ability to sense moderate errors. By amplifying the error, the patient senses the error early along the trajectory so that the neuromuscular system can begin to rewire itself to compensate.

To avoid limiting learning only in one direction, the patient is immersed in a 3-D graphically virtual environment. Then targets (like a virtual cup of coffee) are generated at random locations around the patient, who then operates in a video-game world attempting to find and reach for each new target.

The results have been striking. Not only can this game be fun, early clinical trials suggest that the neuromuscular effect may be long lasting.

Prof. Yoky Matsuoka at the University of Washington is an expert in using the WAM™ arm and has achieved similar results by generating the errors in the visual field. The enabling tool in common between the two teams (RIC and University of Washington) is the WAM™ arm.