Independent Perspective News

TOKYO, Japan (Reuters) -- People partially paralyzed can hope to move again with the aid of a system developed by Japanese researchers that uses signals from a healthy leg to help control a damaged one.

But it will be at least five years before the system, featured in the most recent issue of U.K. magazine New Scientist, can be used outside the laboratory, researcher Wenwei Yu said.

Work done by Yu and others at Hokkaido University, on Japan's northernmost main island, allowed two men paralyzed by strokes on one side of their bodies, who previously could not walk unaided, to sit, stand, and walk.

The system is promising because it uses computerized sensors to take over from damaged nerves, allowing motion without the patient first making a direct command via a keyboard or switch, said Yu, one of the project's key researchers.

"Other systems have used electrical impulses to send signals to muscles, but the biggest problem has been that somebody has to push a button to get things started," he said in a recent interview. "This allows them to move much more naturally."

Muscle sensors are used to monitor signals in the patient's healthy leg and trigger electrical impulses in 11 electrodes implanted near nerves in the paralyzed leg, so that the paralyzed leg takes its cues from the healthy one.

Other researchers have found ways to move paralyzed limbs by electrically stimulating nerves or muscles, but this may set off involuntary muscle spasms, a problem Yu has avoided by timing the stimulation so that the muscles work smoothly together.

"Our system actually helps to keep the muscles more toned as well," he said.

Yu said the system at present can only aid those paralyzed on one side of the body, and more work is needed to help those who cannot move more of the body or can only move the head.

"A lot more research is needed," he said. "But this system has tremendous possibilities."