[Reading Science] Even Patients with Complete Lower Body Paralysis Can Walk Again

Swiss Federal Institute of Technology Research Team Experiment Results
All 9 Patients Successfully Walked After 5 Months of Electrical Stimulation Therapy Despite No Sensation

Paraplegic patient / Photo by Swiss Federal Institute of Technology

[Asia Economy Reporter Kim Bong-su] Scientists have confirmed that even when nerve cells completely lose function due to spinal cord injury, recovery is possible through electrical stimulation.

The research team from the ?cole Polytechnique F?d?rale de Lausanne (EPFL) in Switzerland published a paper detailing these experimental results in the international academic journal Nature on the 9th (local time). They conducted experiments on a total of nine patients who had completely lost motor function in their legs and had no sensation at all due to lumbar spinal cord injury. However, after implanting electrodes in the spinal cord for five months, these patients received epidural electrical stimulation (ESS), a treatment that applies electrical stimulation to the lower spinal nerves, along with muscle strengthening training, and succeeded in regaining walking ability. Notably, four of them showed remarkable results, being able to walk independently without further ESS treatment.

Nature explained, "These experimental results suggest that electrical stimulation can induce remodeling of spinal nerves, reactivating the motor network." Mark Luijtenberg, a neuroscience professor at the University of Queensland in Australia and part of the research team, also said, "This has given tremendous hope to spinal cord injury patients that they can walk again."

The research team also identified nerve cells presumed to be responsible for motor function recovery. They got a hint from the fact that nerve cell activity in the stimulated area decreased when the ESS switch was turned on. After conducting animal experiments and using deep learning techniques, the team identified 'excitatory interneurons,' nerve cells that connect motor neurons and sensory neurons. When the team removed these cells from mice with spinal cord injuries, ESS treatment no longer worked. This confirmed that these cells play a certain role in restoring the function of motor and sensory neurons stimulated by electrical signals. Although this is only an animal experiment, scientists analyze that the same applies to humans. Ayman Azim, a researcher at the Salk Institute for Biological Studies, explained, "Because the spinal cord structure is very similar among vertebrates, including humans and mice, it is believed that the same neurons perform such roles in humans as well."

Previously, the research team announced results in 2018 and earlier this year showing success in restoring walking ability in patients with lower body paralysis using similar methods. However, those experiments involved patients who still had some sensation in their legs, whereas the significance of this recent study lies in successfully restoring nerve cell function through electrical stimulation in patients whose motor and sensory nerves were completely dead, with no sensation at all.