Shocked into walking

[DA]

http://www.nature.com/nsu/020128/020128-9.html


A partially paralysed man has walked to the shops with the help of tiny electric shocks to his spine. With training, doctors hope to help other paraplegics walk again.

Richard Herman and his colleagues helped a wheelchair-bound quadriplegic follow a walking rhythm by holding him over a moving treadmill. He paced 50 metres slowly - but the effort was exhausting.

Zapping his spine while he was walking, slashed his pace time. The team planted pen-width electrodes in his lower back and gave low-level electrical stimulation1. "He began to walk 100, 200 metres," says Herman, of Arizona State University in Tempe.

After months of training, the patient can now walk up to a kilometre. About 230,000 people have spinal cord injuries in the United States. Herman hopes the technique could help up to 35% of these to lead relatively normal lives at home and in the community.

"It's encouraging - because it's do-able now," says Edgar Garcia-Rill of the University of Arkansas in Fayetteville. Unlike more speculative research into paralysis treatments, Herman's "low-tech" approach could be applied immediately to those who have partially damaged spinal cords.

But patients with complete paralysis might not benefit as they are unable to stand in the first place.

Back to basics

An injured spinal cord regresses to resemble that of a newborn baby, believes Garcia-Rill, who tested the stimulation method in animals. Like toddlers, some paralysed people can learn how to walk again. This involves reactivating an innate walking program in the spinal cord that coordinates muscle movement and the left-right leg sequence.

It's naive to think one treatment will be sufficient
Hugues Barbeau, McGill University, Canada



Soft, constant stimulation of the spinal cord appears to excite this circuit and amplify the learned gait, Herman suggests - and it cuts the energy cost of walking. Unused muscle wastes, so movement tires it easily. Stimulation and training are like a daily jog, they force the muscles to switch into a more energy efficient mode, the Arkansas team showed.

Drugs that replace lost nerve signals in the spinal cord are also being put through clinical trials. Combining these with Herman's techniques is likely to prove the most effective therapy predicts Hugues Barbeau, who studies rehabilitation methods at McGill University in Montreal, Canada: "It's naive to think one will be sufficient," he says.

Efforts to regrow damaged nervous tissue using drugs, or to repair wounds using fetal tissue or stem-cell grafts are "very exciting", but still experimental, says Barbeau.


References
Herman, R. et al. Spinal cord stimulation facilitates functional walking in a chronic incomplete spinal cord injured. Spinal Cord, 39, (2002).


© Nature News Service / Macmillan Magazines Ltd 2002



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