Non-invasive, Brain-controlled Functional Electrical Stimulation for Locomotion Rehabilitation in Individuals with Paraplegia

Aurelie Selfslagh,Mohamed Bouri,Solaiman Shokur,Debora S. F. Campos,Sabrina Almeida,Ana R. C. Donati,Seidi Y. Yamauti,Daniel B. Coelho,Miguel A. L. Nicolelis

doi:10.1038/s41598-019-43041-9

Abstract

Spinal cord injury (SCI) impairs the flow of sensory and motor signals between the brain and the areas of the body located below the lesion level. Here, we describe a neurorehabilitation setup combining several approaches that were shown to have a positive effect in patients with SCI: gait training by means of non-invasive, surface functional electrical stimulation (sFES) of the lower-limbs, proprioceptive and tactile feedback, balance control through overground walking and cue-based decoding of cortical motor commands using a brain-machine interface (BMI). The central component of this new approach was the development of a novel muscle stimulation paradigm for step generation using 16 sFES channels taking all sub-phases of physiological gait into account. We also developed a new BMI protocol to identify left and right leg motor imagery that was used to trigger an sFES-generated step movement. Our system was tested and validated with two patients with chronic paraplegia. These patients were able to walk safely with 65–70% body weight support, accumulating a total of 4,580 steps with this setup. We observed cardiovascular improvements and less dependency on walking assistance, but also partial neurological recovery in both patients, with substantial rates of motor improvement for one of them.

Highlights

Spinal cord injury (SCI) impairs the flow of sensory and motor signals between the brain and the areas of the body located below the lesion level
We demonstrated the validity of each aspect of our approach: a custom 16 channel surface functional electrical stimulation (sFES) system, a closed-loop proportional- integral (PI) controller to cope with muscle fatigue, the integration of a portable haptic device to cope with the lack of lower-limb sensory functions and a novel brain-machine interface (BMI) protocol based on the detection of left and right leg motor imagery
This paper introduces a novel, non-invasive neurorehabilitation protocol for locomotion training for patients with severe chronic paraplegia resulting from spinal cord injuries, which targets both musculoskeletal training and corticospinal plasticity

Summary

Introduction

Spinal cord injury (SCI) impairs the flow of sensory and motor signals between the brain and the areas of the body located below the lesion level. A variety of new approaches for SCI rehabilitation have been introduced[4,5] These efforts aimed at inducing activity-dependent plasticity[5] by the utilization of robotic trainers[6,7,8], epidural electrical stimulation[9,10,11], body-weight support trainers[12], brain-machine interfaces[11,13,14,15], transcranial magnetic stimulation[16,17] and surface functional electrical stimulation (sFES)[18,19]. The BFNR (BMI, sFES, NeuroRehabilitation) protocol described here integrates four key elements to potentiate recovery in patients with SCI: muscle activation through sFES21–23 (see[24] for a review), balance control through body weight support[25], real-time decoding of motor command (BMI)[14,20] and sensory feedback through a portable haptic device[26]. BMI-FES (systems that use BMI to detect patients’ voluntary motor commands to trigger their muscle contractions through an FES) have been extensively studied as rehabilitation tools (some researchers call it therapy or partial restoration) for patients with severe cases of stroke[27,28,29], to potentiate recovery of upper-limb[28,30,31] or lower-limb motor function[32] (see[33] for a review)

Methods

Results

Conclusion