Restoring Sensation After Lower-limb Amputations to Improve Balance and Gait

People with a lower-limb amputation rely heavily on vision for balance to compensate for the lack of sensory feedback from their missing limb. As sensory feedback from the foot activates neural pathways that maintain stability and promote healthy gait patterns, restoring this sensation is vital to improve function and reduce fall risk in people with an amputation. Sensory neuroprostheses stimulate the remaining afferent pathways, in either the periphery or the spinal cord, to evoke sensations in the missing limb in real-time during balance and gait. While studies using peripheral nerve stimulation have set the precedent for these devices, these approaches are not easily translatable to clinical practice. Regardless of the stimulation approach, determining the effectiveness of sensory neuroprostheses has remained a significant challenge. Because standard clinical outcome measures used to assess balance and gait in this population are intended to provide an overall picture of an individual’s functional status, they fail to isolate more specific aspects of balance or gait, such as reliance on sensation. Additionally, more intuitive sensations over unnatural sensations have shown promise in providing additional functional benefits, however we lack reliable measures of intuitiveness or multi-sensory integration of stimuli to systematically evaluate these advancements. In this dissertation, I address some key challenges and barriers to advancement of sensory neuroprosthetics. Here we will use a lumbosacral spinal cord stimulation, a clinically available stimulation method for sensory neuroprostheses, which will provide an additional pathway of clinical translation. Furthermore, we will evaluate the relationship between sensation and standard clinical measures, the effects of sensory neuroprostheses on both standard clinical measures and more robust measures of balance and gait, and evaluate a measure of multi-sensory integration of sensory stimuli for future studies to evaluate the functional effects of different stimulus types