The word “paralysis” is starting to lose its gloomy permanence, as researchers at top-end institutions around the world have been getting some people back on their legs who were previously thought to have to spend the rest of their lives in wheelchairs. Well targeted electrical nerve stimulation, coupled with specialized rehab training, has been the key to these achievements. The hits keep coming, though. A team at École polytechnique fédérale de Lausanne (EPFL) in Switzerland has managed to get three people with serious spinal cord injuries to walk and to even move their legs without any electrical stimulation at all. Though crutches or walkers were used, at least one of the participants has even been able to take multiple steps without holding onto anything at all.

The progress we wrote about earlier this year is similar to what EPFL achieved, but because of the nature of the new stimulation method, benefits persisted even after neurostimulation was shut off. “Our findings are based on a deep understanding of the underlying mechanisms which we gained through years of research on animal models. We were thus able to mimic in real time how the brain naturally activates the spinal cord,” said Grégoire Courtine, one of the researchers involved in the study.

The researchers identified the fact that the timing and where the neurostimulation happens play a big part in making muscles move as desired. But, what is even more important, it looks like nerves actually grow and make new connections when the timing matches what the brain wants to do.

This was done thanks to a large electrode array that was able to stimulate various parts of the spinal cord and control different groups of muscles at the same time. Programming the sequencing of the signals is not easy, but it was so well done that after a week of practice each of the three “paralyzed” volunteers were walking using a walker. After a few months of training, walking improved and the three were able to walk, with some support, for long periods of time. When stimulation was turned off, they still maintained some abilities, compared to subjects in previous studies that simply reverted to being truly paralyzed again.