title: Targeting Lumbar Spinal Neural Circuitry by Epidural Stimulation to Restore Motor Function After Spinal Cord Injury.
abstract: Epidural spinal cord stimulation has a long history of application for improving motor control in spinal cord injury. This review focuses on its resurgence following the progress made in understanding the underlying neurophysiological mechanisms and on recent reports of its augmentative effects upon otherwise subfunctional volitional motor control. Early work revealed that the spinal circuitry involved in lower-limb motor control can be accessed by stimulating through electrodes placed epidurally over the posterior aspect of the lumbar spinal cord below a paralyzing injury. Current understanding is that such stimulation activates large-to-medium-diameter sensory fibers within the posterior roots. Those fibers then trans-synaptically activate various spinal reflex circuits and plurisegmentally organized interneuronal networks that control more complex contraction and relaxation patterns involving multiple muscles. The induced change in responsiveness of this spinal motor circuitry to any residual supraspinal input via clinically silent translesional neural connections that have survived the injury may be a likely explanation for rudimentary volitional control enabled by epidural stimulation in otherwise paralyzed muscles. Technological developments that allow dynamic control of stimulation parameters and the potential for activity-dependent beneficial plasticity may further unveil the remarkable capacity of spinal motor processing that remains even after severe spinal cord injuries.
authors: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria. karen.minassian@gmail.com.
authors: Karen
authors: K
authors: Minassian
authors: Hulse SCI Research Lab, Crawford Research Institute, Shepherd Center, Atlanta, GA, USA.
authors: W Barry
authors: WB
authors: McKay
authors: Neurological Center, Otto-Wagner-Hospital, Vienna, Austria.
authors: Heinrich
authors: H
authors: Binder
authors: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.
authors: Ursula S
authors: US
authors: Hofstoetter
mesh_terms: D006801:Humans; D008159:Lumbar Vertebrae; D009068:Movement / Q000502:physiology; D009415:Nerve Net / Q000503:physiopathology; D013116:Spinal Cord / Q000503:physiopathology; D013119:Spinal Cord Injuries / Q000503:physiopathology / Q000628:therapy*; D062187:Spinal Cord Stimulation / Q000379:methods
keywords: Epidural spinal cord stimulation; Human; Motor recovery; Residual supraspinal control; Spinal circuitry; Spinal cord injury