Three patients with spinal cord injuries are able to walk again with targeted electrical stimulation of the spinal cord, reports a paper published this week in Nature. These results establish a technological framework to improve neurological recovery after spinal cord injuries.
Spinal cord injuries disrupt communication within the nervous system, leading to the loss of essential neurological functions and paralysis. Epidural electrical stimulation (EES) - stimulation applied to the spinal cord - restores locomotion in animal models of spinal cord injury, but is less effective in humans for reasons that have remained unclear.
Gregoire Courtine and colleagues administered targeted EES to three male patients with chronic spinal cord injury (sustained more than four years previously) and partial or complete lower-limb paralysis. Motor neuron activation maps and simulated models were used to identify the optimum patterns of stimulation to different muscle groups. The EES was delivered by a pulse generator controlled in real-time via wireless communication, and was timed to coordinate with intended movement. Within a few days of starting treatment, patients progressed from stepping on a treadmill to supported walking on the ground (while receiving EES), and were able to adjust their step elevation and stride length. Eventually, patients could walk for up to one hour on the treadmill with EES. Following rehabilitation, the three patients could walk independently (either partially supported or with a walker) with EES, and regained voluntary leg movements without EES.
In an associated Nature Neuroscience paper, the same authors demonstrate that previous stimulation protocols to restore walking may have been less effective as they interfered with the patients’ perception of limb position. Stimulation in bursts promotes locomotion while preserving sensory signals coming from the legs.
In an accompanying Nature Neuroscience News & Views article, Chet Mortiz said: “This most recent pair of papers from the Courtine group clearly demonstrates the bright future for the treatment of spinal cord injury.”