Three fully paralyzed people have had their independent motor activity restored by an implant that directly stimulates the nerves controlling trunk and leg movements.
Researchers reveal that patients were able to stand and walk within a day of initiating treatment, and could even perform recreational activities like swimming and cycling, describing this incredible breakthrough in the journal Nature Medicine.
Over the months that followed, the three individuals – all men between the ages of 29 and 41 – took part in extensive neurorehabilitation training using the technology, resulting in even greater voluntary control over their muscle movements.
“I’ve been through some pretty intense training in the past few months, and I’ve set myself a series of goals,” said patient Michel Roccati, who had been paralyzed for several years following a motorcycle accident, in a statement seen by IFLScience. “For instance, I can now go up and down stairs, and I hope to be able to walk one kilometer by this spring.”
Known as epidural electrical stimulation (EES), the technique involves stimulating spinal nerves using implanted multielectrode paddle leads. Previous research has demonstrated that continual stimulation of the dorsal column can restore movement in people with spinal cord injuries, yet gains have been hindered by the fact that the electrode arrays used were not sufficiently elegant to target specific nerves.
The study authors developed a more sophisticated implant that targets the dorsal roots involved in trunk and leg movements, plus a computational framework to guide the surgical positioning of the electrode paddles to ensure they correspond with the correct nerves.
At the same time, they created software that enables patients to select activity-specific stimulation programs that engage the necessary nerves for a particular type of movement.
“Our new, soft implanted leads are designed to be placed underneath the vertebrae, directly on the spinal cord. They can modulate the neurons regulating specific muscle groups,” explained study author Grégoire Courtine. “By controlling these implants, we can activate the spinal cord like the brain would do naturally to have the patient stand, walk, swim or ride a bike, for example.”
“All three patients were able to stand, walk, pedal, swim and control their torso movements in just one day, after their implants were activated!” he continues.
“That’s thanks to the specific stimulation programs we wrote for each type of activity. Patients can select the desired activity on the tablet, and the corresponding protocols are relayed to the pacemaker in the abdomen.”
After training with the technology for five months, all three individuals regained full weight-bearing capacities in their legs, which resulted in the ability to stand for extended periods. As their motor control improved over time, they began to partake in more advanced physical leisure activities outside of the lab, such as boxing and canoeing.
The study authors are in the process of conducting a clinical trial into the efficacy of this approach, and while the results of their ongoing investigation will undoubtedly illuminate aspects of the technology that require improvement, they maintain that their findings to date highlight “a realistic path to support everyday mobility with EES in people with [spinal cord injuries].”