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Photo: Tim Vernon, LTH NHS TRUST / Science photo library

Walking after paralysis: clinical trials on patients

Researchers at the Swiss Federal Institute of Technology in Lausanne (EPFL) have successfully helped a paralysed rat regain the ability to walk through electrical stimulation of the severed section of the rodent’s spinal cord. They were able to control, in real time, the way the rat moved and how high it lifted its limbs. A new laboratory created at the Lausanne University Hospital (CHUV) will test this technology on human patients starting next summer using a brand new force platform for analysing gait. These clinical trials are part of the European NEUWalk project.

Scientists at the EPFL have succeeding in controlling the limbs of a paralysed rat in real time, enabling it to walk. The results of their research were published today in the journal Science Translation Medicine.

Supported by previous research carried out on rats, this latest breakthrough is part of a more general treatment which could one day be used in re-education programmes for patients suffering from spinal cord injuries. Clinical trials are currently being developed as part of the European NEUWalk project. They could start as soon as next summer by using the new, recently installed force platform at the CHUV.

“By reactivating and stimulating the severed spinal cord, we have managed to control the back limbs of a rat in real time, enabling it to walk normally again,” says Grégoire Courtine, neuroscientist at the EPFL.

The body needs electricity

The human body needs electricity in order to function. When the human brain emits a signal, it uses around 30 watts. When the circuits in the nervous system are damaged, the transmission of electrical signals is reduced, which often leads to devastating neurological disorders such as paralysis.

We know that electrically stimulating the nervous system can relieve these neurological problems on many levels. When applied to deep brain cells, it can treat trembling associated with Parkinson’s, for example. Electrical signals can also act upon nerves, thereby enabling patients to regain feeling in an amputated limb. Electrical stimulation of the spinal cord can also restore a patient’s motor control. But can it go as far as helping a paraplegic patient to walk normally? The answer is yes, at least in rats.

“By reactivating and stimulating the severed spinal cord, we have managed to control the back limbs of a rat in real time, enabling it to walk normally again,” says Grégoire Courtine, neuroscientist at the EPFL. “We can control the way it moves and how high it raises its feet.”

The scientists at the EPFL studied rats whose spinal cord had been completely severed in the middle, thereby preventing any transmission of brain signals to the spinal cord, which controls the leg muscles. By placing flexible electrodes along the spinal cord and attaching them to an electrical current, the neural circuits which control walking ability were reactivated.

YouTube video (EPFLnews)

These experiments have also succeeded in establishing a direct link between the parameters of electrical stimulation and the movement of the rat’s limbs. The researchers used this discovery to develop algorithms to adjust the parameters of electrical stimulation based on the rat’s movements. They managed to control the rat’s stride, enabling it to navigate obstacles in front of it such as fences and stairs.

“This research shows that understanding how the central nervous system functions can lead to the development of more effective neuroprosthetic technology,” says Silvestro Micera, neuroengineer and co-author of the study. “We believe this technology could one day significantly improve quality of life for people suffering from neurological disorders.”

In the long term, Courtine, Micera and their colleagues at the EPFL Centre for Neuroprosthetics are trying to decode the brain signals that directly control leg movement. This information could be used to stimulate the spinal cord.

Cutting-edge equipment

The electrical stimulation described in this study will be tested on patients suffering from incomplete spinal cord injuries. These clinical trials will likely begin next summer and will be carried out using a new force platform which combines rehabilitation robotics and innovative systems used to adjust the parameters for electrical stimulation of the spinal cord in real time.

The infrastructure was designed and produced by Grégoire Courtine’s team and includes a robotic support system enabling motor rehabilitation in natural conditions. Infrared cameras are used to detect reflective markers placed on the patient’s body to analyse movement, and sensors are used to record muscle activity. This information is synchronised and integrated in real time to adjust the robotic system and the parameters of electrical stimulation of the spinal cord to meet the specific needs of the patient.

The force platform is in a 100 sq. m room at the CHUV, which already has a re-education centre for translational research focusing on orthopaedic and neurological pathologies.

“This platform is not a rehabilitation centre,” says Grégoire Courtine. “It’s a research laboratory where we study and develop new therapies using innovative technologies and working closely with medical experts from the CHUV, such as physiotherapists, neurologists and neurosurgeons.”