It was just a hope for people paralysed for years by severe spinal cord injury would ever be able to walk again. But with a groundbreaking effort to restore walking movement among three paraplegic patients, published their findings this year.

The treatment, which combined intense physical therapy with a targeted electrical stimulation to the spinal cord was successful in letting the patients walk with the aid of crutches or a walker, and let them regain control over paralyzed muscles even without stimulation, a literal and metaphorical step forward for neuroscience.

The study, conducted by F.B. Wagner et al. at Ecole Polytechnique Federale de Lausanne (EPFL) and the Lausanne University Hospital (CHUV) in Switzerland, was published in Nature 563, 65-71:2018 and is not just controlled laboratory conditions, actually patients are able to walk outside again.

 Surgeons implanted electrodes at specific points of the spinal cord. This triggered signals to the brain that told it to walk. This activation led to the development of new nerve fibres, which is thought to be what allowed the patients to walk even after the stimulation was turned off

Researchers have long pursued diverse strategies to repair and reactivate the spinal cord after injury. Many approaches are remarkably effective in regenerating and achieving functional recovery in mice and other animals, but fail to translate to human therapies.

The neurology advanced Research in the current study was that, rather than delivering a constant electric current as had been tried before the researchers applied patterns of stimulation calculated to activate the correct groups of leg muscles at the correct time during stepping.

In this way, specific locations in the spinal cord could be targeted, to activate the muscles in a coordinated fashion. This patterned stimulation protocol not only allowed the unprecedented restoration of walking ability, but also enabled the individuals to regain control over previously paralysed muscles when electrical stimulation was turned off. This indicates that the brain and spinal cord had re-established functional connections, revealing an unexpected degree of plasticity.

The Ecole Polytechnique Federale de Lausanne researchers connected 16 electrodes onto a pulse generator. This device was then surgically implanted over the patients’ spinal cords in the regions that control their leg muscles

In light of neurology advanced research, spinal injuries vary enormously in their location, severity and outcome, and it will take many more studies to understand who will benefit from this technology. The current research is a proof of concept in a small number of participants who had a range of residual leg function at the start of the study.

 A major challenge is to understand what determines successful recovery. For example, one source of variability might be how much sensory information the damaged spinal cord can still transmit to the brain.

According to the World Health Organization, between 250,000 and 500,000 people around the globe are affected by a spinal-cord injury each year most caused by road accidents, falls or violence. Spinal stimulation is a complex and expensive medical procedure, and recovery also seems to require intensive rehabilitation. It will not be available to all at least, any time soon. But it is a first step.

Pictured are the study’s three paraplegic patients who have walked due to the revolutionary treatment. Sebastian Tobler (left) can walk hands free after being told no treatment was available, Gert-Jan Oskam (centre) can move with crutches after being told he would never walk again and David Mzee (right) can even walk up to a kilometre or for two hours without breaks. They are pictured with the study’s co-lead Professor Gregoire Courtine.

Source & Reference – Wagner, F. B., Mignardot, J.-B., Goff-Mignardot, C. G. L., Demesmaeker, R., Komi, S., Capogrosso, M., … Courtine, G. (2018). Targeted neurotechnology restores walking in humans with spinal cord injury. Nature, 563(7729), 65. https://doi.org/10.1038/s41586-018-0649-2