Objective - The objective of this feasibility study of safety and effectiveness of an implanted multichannel functional electrical stimulation (FES) gait system is to correct gait instability and increase walking speed to improve ambulatory community access of persons with lower extremity paralysis due to incomplete spinal cord injury (ISCI). Research Plan - Individuals with lower extremity weakness from ISCI will be screened for difficulty initiating a step and inefficien forward propulsion. These include individuals with weak hip and knee flexors and ankle dorsiflexors for initiating a step and weak hip flexors, ankle plantar flexor and hip extensors for generating the power for forward propulsion. If meeting inclusion criteria they will undergo baseline gait evaluation and have an 8-channel implantable pulse generator (IPG) and intramuscular electrodes surgically installed to correct their gait deficit. After a period of recoery they will begin with FES exercise and 18 sessions of FES- assisted gait training. They will be reevaluated before discharged for home use and again at 3, 6, 9, and 12 month follow-up for ability to initiate a step and for ability to generate power to move the body forward for improved walking speed. Methodology - In this study each of the six subjects with lower extremity paresis will serve as their own control. Extent of gait correction with IPG will be compared to individual'residual function without FES at pre- and post intervention. Number of trials for testing walking speed, distance, and physiologic cost was determined based on statistical power of 90% for a 0.2m/s improvement in walking speed. Analysis will be applied to parameters from volitional function versus FES assisted gait to determine clinically and statistically significant improvements (p<0.05). To capture a user's measure of participation and quality of life, instruments that address various aspects of community ambulation including SF-36, Subjective Index of Social Outcome, and the Sickness Impact profile will be administered to assess community ambulation. Clinical Significance - Gait impairments in individuals with lower extremity paresis have been associated with increased complications such as injury from falls, social isolation from immobility and decreased quality of life measures. This project will demonstrate the feasibility of a multichannel implanted FES gait system as a neuroprosthetic tool for correction of stepping and increasing walking speed with improved community access and quality of life. The results will provide foundations for applying implanted FES technology to a much larger population in a clinical trial within VA health care and civilian population.
Lower extremity weakness due to paresis or increased extensor tone with lack of coordination places severe limitations on person's ability to walk, thus compromising the ability to work, engage in social or leisure activities, pursue an education or participate in other activities of a independent and productive lifestyle. A novel application of implanted functional electrical stimulation to correct their gait deficits will allow disabled veterans to walk faster and farther ith less effort and with less chance of tripping and falling, thus providing them with improved community access. Being able to walk should significantly improve their quality of life by reducing their disability.