Interleaving stand-step training with spinal cord epidural stimulation effectively improved standing in individuals with chronic complete spinal cord injury

Dr. Enrico Rejc University of Louisville

We have recently shown that approximately 80 sessions of stand training with spinal cord epidural stimulation (scES) optimized for standing promoted standing ability improvements in four individuals with chronic complete spinal cord injury (SCI). In particular, two individuals were able to stand without any external assistance, while other two individuals needed assistance for hip extension. Also, all individuals assisted balance with their upper limbs. Interestingly, 80 sessions of step training performed after stand training remarkably impaired standing in three of these four participants. These findings led us to investigate whether standing and stepping can be concurrently trained without limiting the recovery of standing in individuals with chronic complete SCI using scES. In particular, this study examined the effects of an interleaving stand-step training with scES on motor function for standing in three individuals with chronic complete SCI. Stand training and step training alternated every session, and the total number of training sessions remained the same as in the previous protocol (N=160). During this training paradigm we also were more focused on increasing the volitional involvement of the participant, and allowed longer seated rest (up to 30 minutes per session).After approximately 80 sessions of stand-step training, the ability to stand without external assistance was observed in all 3 individuals, for up to 11.4 minutes within a 60-minute standing session. After 160 sessions of stand-step training, standing time without external assistance further increased in all participants (up to 60 minutes within a 60-minute session). Throughout training, participants were also able to stand using less stable upper limb supports (from a standing frame to a walker as well as holding the hands of a trainer). Standing ability improvements were accompanied by adaptations in muscle activation pattern. For example, training promoted less variable electromyographic patterns during standing, and generally increased the evoked potentials amplitude modulation induced by the sit-to-stand transition.

In conclusion, the interleaving stand-step training with scES performed in this study promoted significant recovery of standing ability in three chronic complete SCI individuals, and seemed more effective than the previous paradigm in which stand training was completed prior to step training. This indicates that the human spinal circuitry can learn standing while also stepping, as long as standing is practiced. These findings also underline the importance of task-specificity in driving training-induced plasticity of spinal neural networks.

Authors: *E. REJC, C. ANGELI, S. HARKEMA; Univ. of Louisville, Louisville, KY
Disclosures: E. Rejc: None. C. Angeli: None. S. Harkema: None.
Grant Support
NIH (NIBIB)R01EB007615
The Christopher & Dana Reeve Foundation
Leona M. and Harry B. Helmsley Charitable Trust
Kessler Foundation
Medtronic Inc
LINK: Society for Neuroscience

LAB LINK and PUBLICATIONS

Nature Article

New Update on scES study: Kate WilletteSpinal cord stimulation (scES) involves planting an array of electrodes into the epidural space in the lumbar area of the cord. By way of a wireless control, those electrodes allow a researcher to send a pulse on command into the lower spine. The idea of scES isn’t to stimulate a muscle or two, but to activate whole networks of neurons that injury to the spinal cord has left without useful input.”

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