Overview

In ongoing research that’s seeking to restore motor functions to people with paralysis, researchers have identified a group of nerve cells that are key to helping people with spinal cord injuries walk again.

The science and other stuff to know

For years, electrical stimulation has often been used in patients with spinal cord injuries to relieve pain. But a new study, published in Nature, has shown that this technique can also accelerate walking recovery among individuals with paralysis. The groundbreaking breakthrough is the work of a research team at the Swiss Federal Institute of Technology Lausanne (EPFL).

In 2018, the same team showed that delivering electrical pulses to lower-spine nerves — a technique known as epidural electrical stimulation (EES) — could help people with this type of spinal cord injury walk again when combined with training. Three participants in the trial at the time went from having severe or complete motor paralysis and minimal sensation in their legs to being able to take steps on their own, or with a walker or crutches, Nature reported.

EPFL researchers have now extended the work, showing EES can also work in people who’ve lost all leg sensations.

To demonstrate this, the team implanted electrical devices into the spinal cords of nine patients who had injuries in a similar area. Three of the participants had complete paralysis and no sensation in their legs. Five months into the trial, all the participants regained their mobility after training paired with EES.

To better understand how this occurred, the team conducted similar experiments with mice that had received similar spinal cord injuries. The team noticed that a certain type of neuron, Vsx2, became more active after electrical stimulation.

So what?

Researchers concluded that similar neurons could be the key to restoring motor functions in patients with paralysis.

“After spinal cord injury, you have a lot of chaotic activity where a lot of neurons are trying to function,” Jocelyne Bloch, study co-author and EPFL researcher, told New Scientist. “The electrical rehabilitation organizes the network of cells and you actually increase the activity of a specific type of cell, while all the other cells are not activated.”

“These cells are important for recovery of walking in injured mice. But when we switch them off in healthy mice without injury, it hardly affected their ability to walk.”

What’s next?

This study is crucial as it could pave the way for more targeted treatments for paralyzed patients, as scientists can now aim to manipulate these neurons to regenerate the spinal cord. In addition, researchers acknowledge that walking is controlled by numerous neural populations throughout the brain and spinal cord. In future research, the team aims to unearth those neurons’ locations and connectivity.