This is a device study that will evaluate the effect of an implanted stimulator on improving walking in stroke survivors. There are two phases in the study: 1) Screening - this phase determines if the individual is a good candidate to receive an implanted system, 2) Implantation, controller development, and evaluation - this phase includes installing the device and setting the individual up for home use, creating advanced controllers for walking and evaluating the effect of the device over several months.

The purpose of this study is to evaluate the effects of neural stimulation for improving walking after stroke. Participants will undergo surgery to implant a stimulator and electrodes to activate muscles used during walking. The device delivers electrical pulses to the nerves causing the muscles to contract to perform functional movements. The system coordinates assistance based on external sensors. After receiving the implanted device, participants undergo training to use the device to assist walking. Evaluations are completed prior to surgery as well after training and at later follow up sessions.

Inclusion Criteria:

• At least 6-months post stroke
• Age 21 to 75 years old
• Able to ambulate, but does not require the assistance of more than one person
• Walk slower than 0.8m/s during a 10m walk test
• Lower extremity Fugl-Meyer Motor Assessment (FMA) <= 20
• Reduced peak hip, knee and/or ankle range of motion during stance or swing phases
• Modified Ashworth Scale (MAS) <= 2 at the above joints during passive flexion and extension
• Innervated and excitable lower extremity and trunk musculature
• Appropriate body habitus (height and weight within acceptable limits as determined by study physician)
• Adequate social support and stability
• Willingness to comply with follow-up procedures
• Neurologically stable as determined by a physician

Exclusion Criteria:

• Non-English speaking
• Significant range of motion limitations (lacking hip extension, etc.)
• History of spontaneous fractures or other evidence of excessively low bone density
• Acute orthopedic problems (severe scoliosis, joint dislocations, etc.)
• Medical complications (cardiac abnormalities, skin breakdowns, uncontrolled seizures, immunological/pulmonary/renal/circulatory compromise, additional neurologic conditions etc.)
• Cardiovascular or pulmonary disease
• Uncontrolled diabetes or hypertension
• Presence of a demand pacemaker or cardiac defibrillator
• Pregnancy
• Complications of stroke that result in an increased risk of falls (apraxia, uncompensated hemineglect, hemianopsia etc.)
• Significant history of repeated falls
• Severely impaired cognition and communication
• Any other medical or psychological condition that would be a contraindication

De-identified assessment data will be shared via NICHD DASH

Data will become available after study completion

De-identified data will be available anyone with access to the NICHD DASH repository