Brain stimulation restores walking ability in paralyzed people

A study published in ‘Nature Medicine’ shows that deep brain stimulation of the lateral hypothalamus improves walking and promotes recovery in humans and rodents with spinal cord injuries.

This brain region, involved in wakefulness, eating, and motivation, plays a key role in movement recovery. The researchers observed immediate improvements in walking ability in mice and rats with various injuries, and in two human patients with chronic spinal cord injuries, who also showed improvement in walking tests.

The study, carried out by researchers from the Federal Polytechnic School of Lausanne (EPFL) and the University Hospital of Lausanne (CHUV), led by Grégoire Courtine and Jocelyne Bloch, have achieved an important advance in the treatment of spinal cord injuries (SCI). By applying deep brain stimulation (DBS) to an unexpected region of the brain, the lateral hypothalamus (LH), the team has improved the recovery of lower extremity movements in two people with partial SCI, significantly improving their autonomy and well-being.

Wolfgang Jäger, a 54-year-old Austrian who has been in a wheelchair since 2006 due to a skiing accident that caused a spinal cord injury, participated in the clinical trial and experienced firsthand how deep brain stimulation was able to restore his mobility and independence. “Last year, during the holidays, it was not a problem to walk a few steps towards the sea using stimulation,” said Jäger, describing the newfound freedom thanks to DBS. Beyond walking, the therapy has improved everyday tasks. “Now I can reach things in the kitchen cabinets,” he added.

DBS is a well-established neurosurgical technique that involves implanting electrodes in specific regions of the brain to modulate neuronal activity. Traditionally, it has been used to treat movement disorders such as Parkinson’s and essential tremor by targeting areas of the brain responsible for motor control. However, applying DBS to the lateral hypothalamus to treat partial paralysis is a novel approach. By focusing on the LH, .Neurorestore researchers have tapped into an unexpected neural pathway not previously considered for motor recovery.

In the study published in Nature Medicine, not only did DBS show immediate results in improving gait during rehabilitation, but patients also showed long-term improvements that persisted even when the stimulation was turned off. These findings suggest that the treatment promoted a reorganization of residual nerve fibers that contribute to sustained neurological improvements.

«This research shows that the brain is necessary to recover from paralysis. Surprisingly, the brain cannot fully take advantage of the neuronal projections that survive after spinal cord injury. “Here, we discovered how to access a small region of the brain that was not known to be involved in the production of gait to activate these residual connections and increase neurological recovery in people with spinal cord injuries,” explains Courtine, professor of neuroscience at EPFL. , the University Hospital of Lausanne (CHUV) and UNIL, and co-director of the .NeuroRestore center.

The success of this DBS therapy was based on two complementary approaches: discoveries facilitated by novel methodologies in animal studies and the translation of these findings into precise surgical techniques in humans. For the surgery, the researchers used detailed brain scans to guide the precise placement of the small electrodes in the brain, performed by Bloch at CHUV, while the patient was fully awake.

“Once the electrode was in place and we performed the stimulation, the first patient immediately said, ‘I feel my legs.’ When we increased the stimulation, he said, ‘I feel the need to walk!’ This real-time feedback confirmed that we had targeted the correct region, even if this region had never been associated with leg control in humans. At that moment, I knew that we were witnessing an important discovery about the anatomical organization of brain functions,” says Bloch, neurosurgeon and professor at the University Hospital of Lausanne (CHUV), UNIL and EPFL, and co-director of the .NeuroRestore center.

The role of the lateral hypothalamus in gait recovery

The identification of the LH as a key player in motor recovery after paralysis is, in itself, an important scientific discovery, given that this region had traditionally been associated with functions such as alertness and feeding. This advance arose from the development of a novel multi-step methodology that began with anatomical and functional mapping of the whole brain to establish the role of this region in gait, followed by experiments in preclinical models to establish the precise circuits involved in recovery. . Ultimately, these results led to clinical trials in human participants.

“It was fundamental research, through the creation of detailed maps of the entire brain, that allowed us to identify the lateral hypothalamus in gait recovery. Without this fundamental work, we would not have discovered the unexpected role that this region plays in gait recovery,” says Jordan Squair, one of the study’s lead authors.

Combining DBS with spinal implants for improved recovery

These remarkable results open the way to new therapeutic applications to improve recovery from spinal cord injuries. Future research will explore the integration of DBS with other technologies, such as spinal implants that have already shown potential to restore movement after spinal cord injuries. “Integrating our two approaches, brain and spinal stimulation, will offer a more comprehensive recovery strategy for patients with spinal cord injuries,” says Courtine.