STIMO study participant David Mzee is now able to take a few steps of his own -...
STIMO study participant David Mzee is now able to take a few steps of his own - even without stimulation.
Source: EPFL/Jamani Caillet

Neurotechnology allows chronic paraplegia to walk again

Three patients with chronic paraplegia were able to walk over ground thanks to precise electrical stimulation of their spinal cords via a wireless implant. In a double study published in Nature and Nature Neuroscience, Swiss scientists Grégoire Courtine (École Polytechnique Fédérale de Lausanne/EPFL and CHUV/Unil) and Jocelyne Bloch (CHUV/Unil) show that, after a few months of training, the patients were able to control previously paralyzed leg muscles even in the absence of electrical stimulation.

Three paraplegics who sustained cervical spinal cord injuries many years ago are now able to walk with the aid of crutches or a walker thanks to new rehabilitation protocols that combine targeted electrical stimulation of the lumbar spinal cord and weight-assisted therapy. This latest study, called STIMO (STImulation Movement Overground), establishes a new therapeutic framework to improve recovery from spinal cord injury. All patients involved in the study recovered voluntary control of leg muscles that had been paralyzed for many years. Unlike the findings of two independent studies published recently in the United States on a similar concept, neurological function was shown to persist beyond training sessions even when the electrical stimulation was turned off.

As precise as a Swiss watch

“Our findings are based on a deep understanding of the underlying mechanisms which we gained through years of research on animal models. We were thus able to mimic in real time how the brain naturally activates the spinal cord,” says EPFL neuroscientist Grégoire Courtine. “The exact timing and location of the electrical stimulation are crucial to a patient’s ability to produce an intended movement. It is also this spatiotemporal coincidence that triggers the growth of new nerve connections.”

“All the patients could walk using body weight support within one week. I knew immediately that we were on the right path,” adds CHUV neurosurgeon Jocelyne Bloch, who surgically placed the implants in the patients. This study achieves an unprecedented level of precision in electrically stimulating spinal cords. “The targeted stimulation must be as precise as a Swiss watch. In our method, we implant an array of electrodes over the spinal cord which allows us to target individual muscle groups in the legs,” explains Bloch. “Selected configurations of electrodes are activating specific regions of the spinal cord, mimicking the signals that the brain would deliver to produce walking.”

The challenge for the patients was to learn how to coordinate their brains’ intention to walk with the targeted electrical stimulation. But that did not take long. “All three study participants were able to walk with body-weight support after only one week of calibration, and voluntary muscle control improved tremendously within five months of training”, says Courtine. “The human nervous system responded even more profoundly to the treatment than we expected.”

Helping the brain help itself

The new rehabilitation protocols based on this targeted neurotechnology lead to improved neurological function by allowing the participants to actively train natural overground walking capabilities in the lab for extensive periods of time, as opposed to passive training like exoskeleton-assisted stepping.

During rehabilitation sessions, the three participants were able to walk hands-free over more than one kilometer with the help of targeted electrical stimulation and an intelligent bodyweight-support system. Moreover, they exhibited no leg-muscle fatigue, and so there was no deterioration in stepping quality. These longer, high-intensity training sessions proved crucial for triggering activity-dependent plasticity – the nervous system’s intrinsic ability to reorganize nerve fibers – which leads to improved motor function even when the electrical stimulation is turned off.

Previous studies using more empirical approaches, such as continuous electrical stimulation protocols, have shown that a select few paraplegics can indeed take steps with the help of walking aids and electrical stimulation, but only over short distances and as long as the stimulation is on. As soon as the stimulation is turned off, the patients immediately return to their previous state of paralysis and are no longer able to activate leg movements.

Next steps

The startup GTX medical, co-founded by Courtine and Bloch, will use these findings to develop tailored neurotechnology with the aim to turn this rehabilitation paradigm into a treatment available at hospitals and clinics everywhere. “We are building next-generation neurotechnology that will also be tested very early post-injury, when the potential for recovery is high and the neuromuscular system has not yet undergone the atrophy that follows chronic paralysis. Our goal is to develop a widely accessible treatment,” adds Courtine.

Related articles

Implants: Next-generation brain interfaces

Implants: Next-generation brain interfaces

Next-generation brain implants with more than a thousand electrodes can survive for more than six years.

How 5 upper body exoskeletons support natural movements

How 5 upper body exoskeletons support natural movements

We present five upper body exoskeletons that might help restore natural hand or limb movements.

Converting human body motions into electricity

Converting human body motions into electricity

Bioengineers have invented a novel soft and flexible self-powered bioelectronic device that converts human body motions into electricity.

Wearable devices can reduce collision risk in blind people

Wearable devices can reduce collision risk in blind people

A wearable computer vision device can reduce collisions for both people who are blind or those who are visually impaired and using a long cane and/or guide dog by 37 percent, compared to using other mobility aids alone.

Neuroprosthesis decodes speech for paralyzed man

Neuroprosthesis decodes speech for paralyzed man

Researchers have developed a "speech neuroprosthesis" that has enabled a man with severe paralysis to communicate in sentences.

Self-powered implant stimulates fast bone healing

Self-powered implant stimulates fast bone healing

Reseachers have developed a self-powered implantable and bioresorbable electrostimulation device for biofeedback bone fracture healing.

Transient pacemaker dissolves in body

Transient pacemaker dissolves in body

Researchers have developed the first-ever transient pacemaker — a wireless, battery-free, fully implantable pacing device that disappears after it’s no longer needed.

Stereotactic systems from the 3D printer

Stereotactic systems from the 3D printer

Researchers have developed a way of manufacturing stereotactic systems from plastic using a 3D printer – a cost-effective method that opens up new design potential.

Brain-computer interface turns mental handwriting into text

Brain-computer interface turns mental handwriting into text

Scientists have used an implanted sensor to record the brain signals associated with handwriting, and used those signals to create text on a computer in real time.

Popular articles

Subscribe to Newsletter