Control of an Ambulatory Exoskeleton with a Brain–Machine Interface for Spinal Cord Injury Gait Rehabilitation

Frontiers in Neuroscience, 2016 · DOI: 10.3389/fnins.2016.00359 · Published: August 3, 2016

Simple Explanation

Brain-machine interfaces (BMIs) can be used as a natural control method for rehabilitative technologies in patients suffering from paralysis. BMI provides a continuous association between the brain activity and peripheral stimulation, with the potential to induce plastic changes in the nervous system. This paper proposes a closed-loop BMI system to control an ambulatory exoskeleton—without any weight or balance support—for gait rehabilitation of incomplete spinal cord injury (SCI) patients. The integrated system was validated with three healthy subjects, and its viability in a clinical scenario was tested with four SCI patients. Using a cue-guided paradigm, the electroencephalographic signals of the subjects were used to decode their gait intention and to trigger the movements of the exoskeleton. We designed a protocol with a special emphasis on safety, as patients with poor balance were required to stand and walk.

Study Duration

Not specified

Participants

3 healthy subjects and 4 SCI patients

Evidence Level

Not specified

Key Findings

1
For the three healthy subjects, 84.44 ± 14.56% of the trials were correctly decoded, indicating the viability of the setup.
2
Three out of four patients performed at least one successful BMI session, with an average performance of 77.6 1 ± 14.72%.
3
A shared control strategy was effective in preventing unexpected movements, which could lead to patient falls.

Research Summary

This paper presents an integrated system for the closed-loop control of an ambulatory exoskeleton with a BMI. The exoskeleton works under an assist-as-needed control paradigm, which can be adapted to the capabilities of each patient and assist him/her only to the extent he/she needs. The EEG neural correlates of movement are used to decode the intention of gait initiation, which is used as a volitional control signal for the exoskeleton movement. The feasibility of the proposed system is validated with two sets of experiments. The first experiment shows the viability of the whole set-up with three healthy subjects. The second experiment demonstrates the viability of the system in a realistic clinical environment, involving four incomplete SCI patients.

Practical Implications

Rehabilitation Potential

The study serves as a proof-of-concept for using BMI-controlled ambulatory exoskeletons for gait rehabilitation in incomplete paraplegia.

Clinical Integration

The implemented safety measures and the therapist interface highlight the potential for integrating BMI technology into clinical setups.

Personalized Therapy

The assist-as-needed control paradigm of the exoskeleton can be adapted to the individual capabilities of each patient, enabling personalized rehabilitation interventions.