Task-specific Epidural Stimulation Study

Overview

The investigators propose to understand the role of lumbosacral spinal cord epidural stimulation (scES) in recovery of autonomic nervous system function, voluntary movement, and standing in individuals with severe spinal cord injury (SCI). Thirty-six individuals with severe SCI who have cardiovascular and respiratory dysfunction and who are unable to voluntarily move the legs or stand will receive scES for cardiovascular function, voluntary movement, or standing with and/or without weight-bearing standing. Training will consist of practicing voluntary movements or standing in the presence of specific scES configurations designed for the voluntary movements of the legs and trunk (Vol-scES), or epidural stimulation configurations specific for standing (Stand-scES). Specific configurations epidural stimulation for cardiovascular function (CV-scES) will be provided during sitting and supine and during maneuvers of orthostatic or cardiovascular stress. The ability to move voluntarily, stand, as well as cardiovascular, respiratory, bladder, bowel and sexual function will be assessed in these individuals with chronic severe spinal cord injury. Quality of life and costs of health care also will be assessed.

Experimental Design The investigators will enroll, implant and complete the interventions in 36 research participants who have sustained a SCI in the proposed experiments. The investigators anticipate they will need to screen 108 potential research participants to enroll 36 individuals who will complete the study. This sample size will provide sufficient replication per study group (n=4) from which variance and effect size estimates for each study hypothesis can be calculated, and hypothesis tests conducted. The investigators will also select individuals to assure that there are a minimum of 25% (n=9) women to adequately represent the percentage in the SCI population. The investigators will study each cohort of patients comprehensively, and each individual will be allocated to the group interventions based on the method of minimization. Research participants will be randomized into group interventions. This novel approach of conducting repeated experiments with comprehensive assessments in a smaller cohort of patients, rather than a more traditional approach of including a large number of patients and focusing on a single outcome, will advance both clinical and scientific knowledge in this highly complex population. The investigators have found success with the smaller cohort approach because they can employ more rigorous, quantitative and sensitive outcomes that not only inform them about the potential clinical efficacy, but also provide further knowledge of the mechanisms of neural control of movement and other physiological mechanisms related to cardiovascular, respiratory, bladder, bowel and sexual function. Group A: * Vol-scES during voluntary leg movement training while sitting or lying supine (A1). * CV-scES during sitting or lying supine (A2). Group B: * Vol-scES during voluntary leg movement training + Stand-ES during stand training (B1). * CV-ES during sitting or lying supine + Stand-ES during stand training (B2).