Precise electrical stimulation helps to treat paralysis in three patients

This week’s video comes from Switzerland where three patients with chronic paraplegia have walked again thanks to precise electrical stimulation of their spinal cords via a wireless implant.

electrical stimulation
David Mzee at EPFL’s Rolex Learning (EPFL/ Jamani Caillet)

The treatment works by implanting an array of electrodes over the spinal cord, allowing the surgical team to target individual muscle groups in the legs. After a few months of training, the patients could control previously paralysed leg muscles, even in the absence of electrical stimulation.

“Selected configurations of electrodes are activating specific regions of the spinal cord, mimicking the signals that the brain would deliver to produce walking,” said Prof Jocelyne Bloch, a neuroscientist at Lausanne University Hospital (CHUV/Unil).

The breakthrough, led by Prof Grégoire Courtine (EPFL/ CHUV/Unil) and Prof Bloch, is published in Nature and Nature Neuroscience.

All patients involved in the STIMO (STImulation Movement Overground) study recovered voluntary control of leg muscles that had been paralysed for many years.

“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 Courtine. “The exact timing and location of the electrical stimulation are crucial to a patient’s ability to produce an intended movement. It is also this spatiotemporal coincidence that triggers the growth of new nerve connections.”

According to EPFL, the challenge for the patients was to learn how to coordinate their brains’ intention to walk with the targeted electrical stimulation, but all the participants were able to walk with body-weight support after one week of calibration.

Algorithm tailors walking rehab to individual needs

“Voluntary muscle control improved tremendously within five months of training”, said Courtine. “The human nervous system responded even more profoundly to the treatment than we expected.”

During rehabilitation sessions, the three participants were able to walk hands-free over 1km with the help of targeted electrical stimulation and an intelligent bodyweight-support system.

These sessions helped to trigger activity-dependent plasticity, which is the nervous system’s inherent ability to reorganise nerve fibres. This then led to improved motor function, even when the electrical stimulation is turned off.

GTX medical, a start-up, co-founded by Courtine and Bloch, will use these findings to develop tailored neurotechnology with the aim of making the treatment available to all hospitals and clinics.

“We are building next-generation neurotechnology that will also be tested very early post-injury, when the potential for recovery is high and the neuromuscular system has not yet undergone the atrophy that follows chronic paralysis,” said Courtine.