After they completed the 12 sessions, the people who received electrical stimulation had gained upper limb control, on average doubling the number of blocks they could move, although they still could not move as many blocks as senior citizens who were not impaired. They also performed better on a test of how much force they exerted when pushing up on a small wooden platform with their wrist, exerting more force and holding it for longer. In contrast, members of the control group did not show significant improvement.
The nature of the lesion in the brain that caused the stroke can be so severe that the signals from the brain to the muscles that straighten the elbow and raise the wrist and fingers are profoundly impaired or inhibited, said Dr. Steven Wolf, professor and director of the clinical program in restorative neurology at Emory University School of Medicine.
"The idea is if they can generate the slightest of muscle activity, the EMG-triggered electrical stimulation can then try to help those muscles that are weak contract, so those that are hyperactive -- the ones that bend the elbow, wrist and fingers -- don't simply take over, making it harder for patients to use their arms at all and leading to more pain and discomfort," Wolf said.
Cauraugh speculates the electrical impulses may help reactivate the blocked communication pathway between the brain and the wrist or finger muscles, or encourage alternate pathways to form.
"Many patients were able to move better than when they came in, and it was real dramatic for a few folks," Cauraugh said. "It opened up that avenue of 'Wow, maybe I really can do something with that limb."