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Retraining walking after spinal cord injury: functional gains and neuroplasticity
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- Author / Creator
- Khan, Atif S
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Physical training can affect the excitability of spinal reflexes in a training-specific manner in uninjured humans. Therefore, the first part of this thesis examined the changes in the excitability of a polysynaptic and a monosynaptic reflex in an ankle plantarflexor, after contrasting forms of walking retraining in humans with chronic incomplete spinal cord injury: 1) Endurance training, which emphasized walking speed and distance, and 2) Precision training, which emphasized skilled stepping movements over ground. We determined that both reflexes responded in a training-specific manner, wherein the excitability of only the polysynaptic reflex was reduced after Endurance training. Furthermore, the reduced excitability of the polysynaptic reflex before Endurance training and the decrease in the excitability of the monosynaptic reflex across all the training were related to improvements in walking ability.
Over ground powered exoskeletons are a recent development and have provided individuals with motor complete spinal cord injuries the ability to walk. Therefore, the second part of this thesis examined the changes in walking ability, other functional capabilities and neuroplasticity after walking retraining using the ReWalk powered exoskeleton. We determined that individuals who could not walk before the training were able to walk using the ReWalk after the training. Furthermore, some individuals who could walk before the training improved their walking ability without the ReWalk, after the training. We also observed improvements in other functional capabilities such as improved postural stability and reduced physiologic exertion during walking, and some neuroplasticity within sensory and motor pathways. Finally, field tests of walking in the ReWalk were performed in- and outdoors, and revealed that while some tasks were possible in the ReWalk, others were not, either due to the ReWalk’s design features or safety issues.
Spinal reflexes play a significant role in the regulation of locomotion in humans. Maladaptive neuroplasticity after spinal cord injury leads to the hyperexcitability of spinal reflexes, resulting in spasticity. Before studying the effects of any form of intervention on spinal pathways that, for example, share the Ia-motoneuronal pathway, we first need to establish the variability of the reflexes across multiple days. Therefore, in the third part of this thesis, we determined that spinal reflexes that share the Ia-motoneuronal pathway exhibit differential changes in day-to-day variability within and across individuals with chronic incomplete spinal cord injury.
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- Graduation date
- Fall 2018
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
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