Public Release: 

A helping hand: Healthy arm helps retrain stroke-impaired arm

American Heart Association

DALLAS, June 7 - In the first study of its kind, stroke survivors rehabilitated with a

technique that electrically stimulates the stroke-impaired arm and requires it to work in unison with the healthy arm regained motor skills better than those who stimulated the impaired arm alone, according to a report in the June issue of Stroke: Journal of the American Heart Association.

Many people who have had a stroke or cerebrovascular accident (such as head trauma) are unable to adequately move the wrist and fingers on one side of their body. Experts say that if these patients are to spontaneously regain their movement, it will happen only during the first year after stroke.

According to the study's lead author, James H. Cauraugh, Ph.D., a significant percentage of stroke patients have long-term movement disability and often have trouble performing simple tasks. "Many can't hold a bottle of water and move it to their mouths. It's difficult for them to eat or write if their dominant hand is affected," says Cauraugh, an associate professor in the Center for Exercise Science at the University of Florida, Gainesville.

Cauraugh and a colleague compared three research protocols to determine which would best help people with long-term movement disability recover some of their motor skills. Twenty-five patients, average age 64, who had strokes an average of 39 months prior, were randomly assigned to one of three therapy groups.

In one group, electrical stimulation known as electromyography (EMG)-triggered stimulation was coupled with bilateral movement, a therapy where the unaffected arm helps the affected arm by mimicking its movement. The second group had active neuromuscular stimulation and unilateral movement - therapy on the affected arm only. The third group, "the controls," had physical therapy on the affected limb without the aid of electrical stimulation or bilateral movement.

All participants completed six hours of rehabilitation during a two-week period.

EMG-triggered stimulation involves putting electrodes on the backs of participants' forearms. As patients attempt to move their hands in a certain way (e.g., extend their wrist), their voluntary movement is supplemented by electrical stimulation. The body responds to the stimulation by nearly going through a full range of motion.

Bilateral coordination training involves introducing stimulation on the affected side and movement on the healthy side to complement and assist the affected side.

The ability to voluntarily control wrist and finger extension movements is the goal of the therapy, according to Cauraugh.

The researchers measured each group's progress by having participants complete three tasks before and after therapy. In all three cases, the stimulation/bilateral group performed significantly better than the unilateral group, which did better than the controls.

Before therapy the three groups had comparable ability at grasping and moving one-inch cubes, transferring an average of 18 blocks in a minute. After therapy, the stimulation/bilateral group improved to an average of 27 blocks; the stimulation/unilateral group to 22 blocks; and the control group by one block to 19.

In a simple reaction-time task, participants were asked to react to a buzzer sound by moving as quickly as they could and then relaxing. "We wanted to compare how fast they 'turn on' their muscles before and after rehabilitation," Cauraugh says.

Again, the stimulation/bilateral group had faster reaction time - 227 milliseconds (ms) vs. 255 ms for the unilateral group.

The third test measured sustained muscle contraction by having patients lift their hands and push up against a wooden platform, and hold the action for six seconds. Researchers found that both stimulation/bilateral and stimulation/unilateral groups were much better at the task than the control group and could generate a stronger and more consistent force.

This research supports the idea that bilateral action allows the brain to recruit new neural pathways to help restore function and that electrical stimulation sparks the rewiring of neural circuits to restore connections lost to stroke-induced brain injury.

"This study shows that two motor-recovery protocols are better than one - that stimulation and bilateral movements are better than only stimulation. But stimulation is better than just sitting there and trying to move the arm yourself," Cauraugh says. "A combination of protocols helps people increase their motor repertoire."

Cauraugh says it is important to note that while the combination therapy approach significantly helped these patients, it did not completely restore their motor ability. Clinicians should understand that it is important to involve the unimpaired limb. "We supported the theory that moving the unimpaired limb along with the impaired limb is better," Cauraugh says.


Sangbum Kim, M.S. was co-author of the paper.

The work was funded in part by the American Heart Association.

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