Jean-Baptiste Mignardot/EPFL

Three patients with partial or complete lower-limb paralysis can now walk with support thanks to electrical epidural stimulation, or EES, applied to the surface of their spinal cords.

For centuries, experts thought recovery from spinal injury paralysis could never surpass progress made during the first six months following injury. Now, the latest of three recent studies might prove them wrong.

The study appears in the journal Nature, along with a companion study in Nature Neuroscience.

The two previous studies appeared in Nature Medicine and The New England Journal of Medicine.

Three patients with partial or complete lower-limb paralysis can now walk with support thanks to electrical epidural stimulation, or EES, applied to the surface of their spinal cords.

All three patients had received their injuries years earlier.

With rehabilitation, the patients eventually regained voluntary leg movement even without EES, but whether that means the brain and spinal cord had restored neural links remains to be seen.

Co-author Grégoire Courtine of the Swiss Federal Institute of Technology in Lausanne emphasized the importance of timing, both in the electrical stimulation process and in its future uses on patients:

"The key will be to apply this type of optimized technology very early after the spinal cord injury, when the potential for growth of new nerve connections is more pronounced, the neuromuscular system has not yet undergone all the atrophy that follows chronic paralysis, and you have not lost what it means to walk."

Jean-Baptiste Mignardot/EPFL

Three patients with partial or complete lower-limb paralysis can now walk with support thanks to electrical epidural stimulation, or EES, applied to the surface of their spinal cords.

Previous EES trials have proven less successful in humans than in animals, possibly because they used a continuous neural signal that collided with neural messages from the lower body. Such noise could have interfered with how the human subjects sensed the position of parts of their body.

The new approach eliminated the interference by instead pulsing signals in rhythm with the subject's nervous system.

Regarding future research, Courtine said moving the technique forward will mean going bigger.

"Academically, we're going to be stuck. This field has moved forward very rapidly, I would say, and it is time to take it to a more global level."

Courtine plans to move trials into Europe and America over the next five years, and to continue improving the precision on the technology.