title: A novel command signal for motor neuroprosthetic control.
abstract: BACKGROUND
  Neuroprostheses can restore functions such as hand grasp or standing to individuals with spinal cord injury (SCI) using electrical stimulation to elicit movements in paralyzed muscles. Implanted neuroprostheses currently use electromyographic (EMG) activity from muscles above the lesion that remain under volitional control as a command input. Systems in development use a networked approach and will allow for restoration of multiple functions but will require additional command signals to control the system, especially in individuals with high-level tetraplegia.
  
  
  OBJECTIVE
  The objective of this study was to investigate the feasibility of using muscles innervated below the injury level as command sources for a neuroprosthesis. Recent anatomical and physiological studies have demonstrated the presence of intact axons across the lesion, even in those diagnosed with a clinically complete SCI; hence, EMG activity may be present in muscles with no sign of movement.
  
  
  METHODS
  Twelve participants with motor complete SCI were enrolled and EMG was recorded with surface electrodes from 8 muscles below the knee in each leg.
  
  
  RESULTS
  Significant activity was evident in 89% of the 192 muscles studied during attempted movements of the foot and lower limb. At least 2 muscles from each participant were identified as potential command signals for a neuroprosthesis based on 2-state, threshold classification.
  
  
  CONCLUSIONS
  Results suggest that voluntary activity is present and recordable in below lesion muscles even after clinically complete SCI.
authors.affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA. caw30@case.edu
authors.forename: Christa W
authors.initials: CW
authors.lastname: Moss
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Kilgore
authors.forename: P Hunter
authors.initials: PH
authors.lastname: Peckham
mesh_terms: D004599:Electric Stimulation Therapy / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D058117:Neural Prostheses / Q000592:standards* / Q000639:trends; D011782:Quadriplegia / Q000503:physiopathology / Q000534:rehabilitation; D015398:Signal Transduction / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000503:physiopathology / Q000534:rehabilitation*