People with chronic weakness and partial paralysis who moved both arms simultaneously in conjunction with mild electrical stimulation to their affected limb regained significantly more motion than those who moved only their paralyzed arm or received no therapy at all, according to study published in the June 7 edition of Stoke: Journal of the American Heart Association.
Study participants who received combined therapies regained greater movement in their impaired arms, as well as improved their reaction times. They also were able to sustain muscle contractions longer, indicating they were capable of stronger and more consistent voluntary control.
Before therapy, many participants were unable to perform simple tasks, said James Cauraugh, co-director of the Center for Exercise Science at UF's College of Health and Human Performance.
"Most of these people just want to be independent. They don't want to depend on a significant other to help them eat, help them drink, hold the phone or use the remote control," said Cauraugh, lead investigator on the American Heart Association-funded study. "You can't regain a previous life because of this protocol, but you can be significantly better off than if your arm is just hanging at your side."
Many of the 600,000 Americans who suffer strokes annually experience a spontaneous recovery of motion within the first year afterward. For most - 60 percent or more - however, overcoming persistent disability on one side of the body proves elusive, particularly as time passes.
Mack Statham, 64, said he had little use of his right arm after his stroke four years ago, requiring that he learn to do everything with his left hand. After undergoing the combined therapy, however, he's been able to resume golfing and can now eat with his right hand.
"Everything except writing has improved 100 percent," Statham said. "I can do all the things I used to with my right arm. Even more important, my friends can tell a difference. I can't say enough good things about the program."
After finding in two prior studies that mild active electrical current restored motion to impaired fingers, wrists and hands - some of the most difficult movements to regain - Cauraugh wanted to determine if combining the therapy with motion training to both arms could enhance motor recovery.
When administered to the muscles of a paralyzed arm, mild electrical current - called electromyogram- or EMG-triggered neuromuscular stimulation - is thought to help the brain establish alternate pathways that activate the impaired limb to replace those disrupted by stroke damage and to boost the body's control so the arm can move through a full range of motion, he said.
In addition, although traditional rehabilitation focuses on treating paralyzed limbs only, evidence indicates working both arms together in a coordinated fashion also enhances motion because the brain's signal to the impaired arm is supplemented by its impulse to the unaffected one, Cauraugh said.
"We found the two protocols improved motor performance after just six hours of training," Cauraugh said. "It expedites motor recovery so these people can be more independent, and they feel good about the movements they can do. And if it improved this much with just six hours of training, then chances are that by extending the period of time, additional improvements would be found."
For the current study, 25 people with mild to moderate upper extremity paralysis from a stroke more than a year old were assigned randomly to one of three groups: those receiving electrical stimulation to their impaired arm while moving both arms, those receiving electrical stimulation and training only to the affected arm, and those getting no therapy.
Participants' impaired arms were tested before and after therapy using three tasks. In one measuring motor recovery, researchers counted the number of 1-inch blocks participants could grasp one at a time, move across a barrier and release over a minute's time. Reaction time was determined by how quickly they responded to a buzzer. Sustained muscle contraction force was charted by EMG.
During therapy, surface electrodes were attached to the forearms of people in both the bilateral- and unilateral-training groups that monitored their muscles' electrical activity as they attempted to voluntarily extend their wrists and fingers. The electrodes then transferred a small impulse to help participants complete the motion.
Participants started the test with equivalent motor capabilities. After four 90-minute training sessions over a two-week period, however, the group that used both arms coupled with electrical stimulation showed significant improvement in all three tests. They were able to move an average of seven more blocks, their median reaction times improved by 53 milliseconds and EMG showed they were able to sustain more forceful contractions than either the group that exercised only the only the affected arm or that received no training.
The group that trained with electrical stimulation using only their affected arms also fared considerably better than those receiving no therapy. Participants in the unilateral group were able to move an average of four more blocks and decreased their median reaction time by 14 milliseconds.
The group receiving no therapy moved one more block, but there was no other improvement.
"Seven blocks might not seem like a lot, but it's a multilevel task, so improvement by seven after such a short period of training time is rather dramatic." Cauraugh said. "Many of these movements we take for granted, but these people struggle incredibly to execute them."
Source: James Cauraugh
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