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Ability to Walk Restored for Man Paralyzed for Five Years

The ability to walk has been restored following a spinal cord injury, using one’s own brain power, according to research published in the open access Journal of NeuroEngineering and Rehabilitation. The preliminary proof-of-concept study shows that it is possible to use direct brain control to get a person’s legs to walk again.

This is the first time that a person with complete paralysis in both legs (paraplegia) due to spinal cord injury was able to walk without relying on manually controlled robotic limbs, as with previous walking aid devices.

The participant, who had been paralyzed for five years, walked along a 3.66m long course using an electroencephalogram (EEG) based system. The system takes electrical signals from the participant’s brain, which then travel down to electrodes placed around his knees to create movement.

Dr. An Do, one of the lead researchers involved in the study, from University of California, Irvine, USA, says: “Even after years of paralysis the brain can still generate robust brain waves that can be harnessed to enable basic walking. We showed that you can restore intuitive, brain-controlled walking after a complete spinal cord injury. This noninvasive system for leg muscle stimulation is a promising method and is an advance of our current brain-controlled systems that use virtual reality or a robotic exoskeleton.”

Mental training was initially needed to reactivate the brain’s walking ability. Seated and wearing an EEG cap to read his brainwaves, the participant trained to control an avatar in a virtual reality environment. He also required physical training to recondition and strengthen his leg muscles.

The participant later practiced walking while suspended 5cm above ground, so he could freely move his legs without having to support himself. On his 20th visit, he translated these skills to walk on the ground and wore a body-weight support system for aid and to prevent falls. Over the 19 week testing period, he gained more control and performed more tests per visit.

Image shows the man in a walking harness.

Experimental setup. Left: The suspended walking test. In response to “Idle” or “Walk” cues displayed on a computer screen (not shown) the participant modulates his EEG by idling or attempting to walk. EEG is sent wirelessly (via Bluetooth communication protocol) to the computer, which processes the data and wirelessly sends a decision to either “Idle” or “Walk” to a microcontroller. The microcontroller (placed in the belt-pack) drives the FES of the femoral and deep peroneal nerves to perform either FES-mediated standing or walking (in place). Right: The overground walking test. In response to verbal cues, the participant performs BCI-FES mediated walking and standing to walk along a linear course and stop at three cones positioned 1.8 m apart. The basic components are: the BCI-FES system, motion sensor system (two gyroscopes and a laser distance meter), and the ZeroG body weight support system to prevent falls. The information flow from EEG to FES is identical to that of the suspended walking test. Note that the participant’s face was scrambled due to privacy concerns Credit: King et al. Journal of NeuroEngineering and Rehabilitation 2015.

This proof-of-concept study involved a single patient so further studies are needed to establish whether these results are true for a larger population of individuals with paraplegia.

Dr. Zoran Nenadic, the senior lead researcher of the study, from University of California, Irvine, USA, says: “Once we’ve confirmed the usability of this noninvasive system, we can look into invasive means, such as brain implants. We hope that an implant could achieve an even greater level of prosthesis control because brain waves are recorded with higher quality. In addition, such an implant could deliver sensation back to the brain, enabling the user to feel their legs.”

About this neurology research

Source: Alanna Orpen – BioMed Central
Image Source: The image is credited to King et al. / Journal of NeuroEngineering and Rehabilitation 2015
Original Research: Full open access research for “The feasibility of a brain-computer interface functional electrical stimulation system for the restoration of overground walking after paraplegia” by Christine E. King, Po T. Wang, Colin M. McCrimmon, Cathy CY Chou, An H. Do and Zoran Nenadic in Journal of NeuroEngineering and Rehabilitation. Published online September 23 2015 doi:10.1186/s12984-015-0068-7


Abstract

The feasibility of a brain-computer interface functional electrical stimulation system for the restoration of overground walking after paraplegia

Background
Direct brain control of overground walking in those with paraplegia due to spinal cord injury (SCI) has not been achieved. Invasive brain-computer interfaces (BCIs) may provide a permanent solution to this problem by directly linking the brain to lower extremity prostheses. To justify the pursuit of such invasive systems, the feasibility of BCI controlled overground walking should first be established in a noninvasive manner. To accomplish this goal, we developed an electroencephalogram (EEG)-based BCI to control a functional electrical stimulation (FES) system for overground walking and assessed its performance in an individual with paraplegia due to SCI.

Methods
An individual with SCI (T6 AIS B) was recruited for the study and was trained to operate an EEG-based BCI system using an attempted walking/idling control strategy. He also underwent muscle reconditioning to facilitate standing and overground walking with a commercial FES system. Subsequently, the BCI and FES systems were integrated and the participant engaged in several real-time walking tests using the BCI-FES system. This was done in both a suspended, off-the-ground condition, and an overground walking condition. BCI states, gyroscope, laser distance meter, and video recording data were used to assess the BCI performance.

Results
During the course of 19 weeks, the participant performed 30 real-time, BCI-FES controlled overground walking tests, and demonstrated the ability to purposefully operate the BCI-FES system by following verbal cues. Based on the comparison between the ground truth and decoded BCI states, he achieved information transfer rates >3 bit/s and correlations >0.9. No adverse events directly related to the study were observed.

Conclusion
This proof-of-concept study demonstrates for the first time that restoring brain-controlled overground walking after paraplegia due to SCI is feasible. Further studies are warranted to establish the generalizability of these results in a population of individuals with paraplegia due to SCI. If this noninvasive system is successfully tested in population studies, the pursuit of permanent, invasive BCI walking prostheses may be justified. In addition, a simplified version of the current system may be explored as a noninvasive neurorehabilitative therapy in those with incomplete motor SCI.

“The feasibility of a brain-computer interface functional electrical stimulation system for the restoration of overground walking after paraplegia” by Christine E. King, Po T. Wang, Colin M. McCrimmon, Cathy CY Chou, An H. Do and Zoran Nenadic in Journal of NeuroEngineering and Rehabilitation. Published online September 23 2015 doi:10.1186/s12984-015-0068-7

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