title: Synthesis of optimal electrical stimulation patterns for functional motion restoration: applied to spinal cord-injured patients.
abstract: We investigated the synthesis of electrical stimulation patterns for functional movement restoration in human paralyzed limbs. We considered the knee joint system, co-activated by the stimulated quadriceps and hamstring muscles. This synthesis is based on optimized functional electrical stimulation (FES) patterns to minimize muscular energy consumption and movement efficiency criteria. This two-part work includes a multi-scale physiological muscle model, based on Huxley's formulation. In the simulation, three synthesis strategies were investigated and compared in terms of muscular energy consumption and co-contraction levels. In the experimental validation, the synthesized FES patterns were carried out on the quadriceps-knee joint system of four complete spinal cord injured subjects. Surface stimulation was applied to all subjects, except for one FES-implanted subject who received neural stimulation. In each experimental validation, the model was adapted to the subject through a parameter identification procedure. Simulation results were successful and showed high co-contraction levels when reference trajectories were tracked. Experimental validation results were encouraging, as the desired and measured trajectories showed good agreement, with an 8.4 % rms error in a subject without substantial time-varying behavior. We updated the maximal isometric force in the model to account for time-varying behavior, which improved the average rms errors from 31.4 to 13.9 % for all subjects.
authors.affiliation: DEMAR Group, LIRMM, INRIA, University of Montpellier 2, CNRS, 860 Rue Saint Priest, 34095, Montpellier Cedex 5, France, mourad.benoussaad@enit.fr.
authors.forename: Mourad
authors.initials: M
authors.lastname: Benoussaad
authors.forename: Philippe
authors.initials: P
authors.lastname: Poignet
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Hayashibe
authors.forename: Christine
authors.initials: C
authors.lastname: Azevedo-Coste
authors.forename: Charles
authors.initials: C
authors.lastname: Fattal
authors.forename: David
authors.initials: D
authors.lastname: Guiraud
mesh_terms: D000328:Adult; D004558:Electric Stimulation / Q000379:methods; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009038:Motion; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology; D020127:Recovery of Function / Q000502:physiology*; D013116:Spinal Cord / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000628:therapy*; D055815:Young Adult