Two spinal cord injured people recover movement thanks to deep brain stimulation

It is paradoxical that the brain, our most complex organ, has a very limited capacity to repair itself when it suffers damage. Every year, 1,000 new cases of spinal cord injury due to trauma occur in Spain. according to data from the Ministry of Healthwhich means that between 25,000 and 30,000 affected people live in our country.

Precisely ‘helping’ the brain to recover from these damages is the objective of the group of neuroscientist Grégoire Courtine (Dijon, France, 1975), trained in physics and mathematics, and a doctorate in Medicine. For almost two decades they have presented, from the Federal Polytechnic School of Lausanne (EPFL), pioneering research who try to reverse this paralysis.

Thus, in 2016 the group managed to monkeys will walk after spinal cord injury thanks to a brain-spinal interface. And in May 2023 they managed to a 40-year-old quadriplegic man walked again. Two unprecedented milestones.

Today, the magazine Nature Medicine shows its latest advance: improving walking immediately and lastingly in two people with incomplete spinal cord injuries, through deep brain stimulation of the lateral hypothalamus, an area of the brain that until now was not associated with movement.

“Brain stimulation of the lateral hypothalamus promotes the lasting reorganization of neuronal networks and allows recovery even after this intervention is turned off,” Quentin Barraud, director of the Mechanistic Division of the Defitech Center for Interventional Neurotherapies (NeuroRestore), which Courtine runs.

News about this discovery

Additionally, as Barraud explains, brain stimulation can complement spinal stimulation to provide a more complete recovery strategy. “It also offers an option for patients with injuries where spinal stimulation may not be applicable, such as lumbosacral injuries. “It is a valuable addition to the therapeutic toolkit for spinal cord injuries,” he adds.

“The novelty of this research is not deep brain stimulation, which is already done in humans in other diseases and in animal models for spinal cord injury. What is new is the target of the stimulation, the lateral hypothalamus, which is not among the brain regions directly related to motor activity,” says Juan de los Reyes Aguilar, head of the Experimental Neurophysiology Group at the National Hospital for Paraplegics ( Toledo).

What is new is the target of the stimulation, the lateral hypothalamus, which is not among the brain regions directly related to motor activity.

Juan de los Reyes Aguilar
— National Hospital for Paraplegics (Toledo)

“This nucleus has traditionally been related to thermoregulation, appetite or states of alertness,” details the researcher, who has not participated in the Swiss group’s research.

“The identification of the lateral hypothalamus as the protagonist of motor recovery after paralysis constitutes in itself an important scientific discovery,” highlights Courtine. And it has been possible thanks to the anatomical and functional mapping of the entire brain with cellular resolution in large organisms.

Mapping with cellular resolution

Using 3D imaging, the researchers mapped the brain activity of mice with spinal cord injuries during recovery phases to identify brain regions involved in walking during recovery. Among them, a group of neurons in the lateral hypothalamus seemed to play an important role in recovery. In this way, they tested and developed the deep brain stimulation of this new target in rodents.

In this new pilot clinical study in two participants with incomplete spinal cord injury, it was shown that deep brain stimulation therapy of the lateral hypothalamus, together with rehabilitation, immediately improved walking, without serious adverse effects.

Furthermore, it favored functional recovery, which persisted when brain stimulation was suspended.

Make everyday tasks easier

“This method is designed for people with incomplete spinal cord injuries, in which some neural pathways remain intact, but are underused. Deep brain stimulation requires the surgical implantation of electrodes in the brain, an invasive procedure guided by images, which allows it to be carried out with high precision to minimize risks,” Barraud points out.

This method is designed for people with incomplete spinal cord injuries, in which some neural pathways remain intact.

Quentin Barraud
— NeuroRestore Researcher

Austrian Wolfgang Jäger, 54, is one of two patients who have benefited from this technique, traditionally used to treat Parkinson’s and essential tremor, and which has now, in a novel approach, been applied to the lateral hypothalamus to reverse partial paralysis.

Jäger has been in a wheelchair since 2006, due to a spinal injury in a skiing accident. Now, with this new advance by Courtine’s group, it has gained mobility and independence. “Last year, during the holidays, it was easy for me to go down a couple of steps and return to the sea thanks to the stimulation,” he points out. The therapy has made his daily tasks easier: “I can reach things in the kitchen cabinets.”

“This research demonstrates that the brain is necessary to recover from paralysis, but surprisingly it is not able to fully take advantage of the neuronal projections that survive after spinal cord injury. Thanks to this discovery we can activate these residual connections and increase neurological recovery in people with spinal cord injury,” states Courtine.

Effective treatments for the injured

Concepción Serrano López-Terradas, from the Institute of Materials Science of the CSIC, works on the development of biomaterials based on reduced graphene oxide to repair the injured spinal cord and on the development of an active bypass to reestablish the nerve connection (ByAxon). “This is just the beginning of a new line of work in which it will be necessary to verify, among other things, the short, medium and long-term impact of deep brain stimulation,” he estimates.

Given the variety of functions in the control of behavior of the lateral hypothalamus, both Serrano López-Terradas and Juan de los Reyes Aguilar point out the importance of ruling out adverse effects that brain stimulation could cause.

For the specialist, “the question that remains open is how many patients with spinal cord injury will be able to benefit from these reparative therapies and if that day is near. Despite this uncertainty, it is impossible not to be happy with such hopeful achievements for everyone as those described in this article.”