Neuromodulation Techniques After SCI

Restoring locomotion following spinal cord injury (SCI) has been the focus of years of research aimed at ameliorating several of health-related comorbidities. Spinal cord epidural stimulation (SCES) exhibits the rehabilitation potential of restoring locomotion in individuals with SCI when combined with intensive locomotion training. Despite this potential, such protocols are likely impractical when applied across large clinical SCI populations due to high monetary costs. Similar to SCES, transspinal stimulation (TS) has also exhibited neuromodulatory benefits by externally stimulating lumbro-sacral neural circuity to generate step-like activities in persons with complete SCI; however, these techniques also require intense gait training. Recently robotic exoskeletons have been used as a promising tool to circumvent limitations associated with labor-intensive locomotor training, and have been safely used as an effective approach in improving levels of physical activity in persons with complete SCI.

Recent work has demonstrated the benefits of combining EAW and neuromodulatory techniques. Following 12-weeks of EAW+SCES training, improvements in locomotion led researchers to decrease the amount of EAW swing assistance to 35% in a person with a C7 complete SCI. This was accompanied by 573 unassisted steps, which represents 50% of the total number of steps taken during that session. Electromyographic (EMG) activity also increased during both stance and swing phases, reflecting the individual's ability to rhythmically fire paralyzed muscles during EAW+SCES. Additionally, cardio-metabolic loads were increased during exoskeletal stepping when combined with SCES as compared to stepping without SCES. The participant also showed a modest decrease in his total and regional absolute fat mass. These preliminary findings suggest that neuromodulation using SCES with exoskeletal ambulation may provide a feasible rehabilitation approach for persons with SCI. The goal of the current study is to examine and compare the effects of EAW combined with SCES or TS in persons with motor complete SCI. The data generated from this application will also enable larger clinal trials to explore ways to optimize exoskeletal assisted gait training through the use of different neuromodulation modalities with SCI.

Following a repeated-measure design, 10 participants with chronic, motor complete (AIS A and B) SCI (age:18-60 years) will be randomly assigned to participate in either 6-months of EAW+SCES (n=5) or EAW+TS (n=5) training. The entire duration of the trial will be approximately 1 year for each participant. Initially, participants will undergo 3-months of EAW training (3 sessions/week), which will be followed by randomization into either a EAW+SCES group or EAW+TS group for an additional 6-months of training (both groups: 3 sessions/week) and a 3-month follow-up period for both groups. Measurements at baseline (BL: prior to EAW) and 4 post-intervention timepoints will occur every 3-months (P1: following 3-months of EAW; P2: following 3-months of EAW+TS or EAW+SCES; P3: after completing 6-months of EAW+TS or EAW+SCES; P4: 3-months after termination of EAW+TS or EAW+SCES).

This pilot work will have 3 specific aims: Aim 1. The investigators will determine and compare improvements to locomotor control following 6 months of EAW+TS and EAW+SCES as measured by 10-meter walking speed, the number of unassisted EAW steps, and EMG activity.

Aim 2. The investigators will determine and compare improvements to cardio-metabolic risk factors following 6 months of EAW+TS and EAW+SCES as measured by total and regional body composition, oxygen uptake, and fasting lipid profile.

Aim 3. The investigators will determine and compare improvements in bladder health following 6 months of EAW+TS and EAW+SCES as measured by bladder filling and emptying

Inclusion criteria

• All participants will be between 18-70 years old, male, with traumatic motor complete SCI and level of injury of T10 and above, as determined by EMG testing and International Standards for Neurological Classification of SCI (ISNCSCI) exam
• All participants will undergo ISNCSCI examination for neurological level and function and only those with American Spinal Injury Classification (AIS A and B; i.e. motor deficit below the level of injury) will be included

Exclusion criteria

Participants with any of the following pre-existing medical conditions will be excluded from the current trial:

• Diagnosis of neurological injury other than SCI, including cauda equina or distal conus injuries resulting in limb or sacral areflexia
• Unhealed fracture in either lower or upper extremities
• Severe scoliosis, hip knee range of motion (ROM) or flexion knee contractures preventing positioning in an exoskeleton or plantarflexion contracture greater than 20 degrees
• Untreated or uncontrolled hypertension defined as high resting blood pressure greater than 140/90 mmHg and severe orthostatic hypotension (drop greater than 20 mmHg compared to resting supine blood pressure) or incapable to maintain a sitting or EAW standing posture
• Other medical conditions including cardiovascular disease, uncontrolled type II DM, uncontrolled hypertension, and those on insulin, pressures sores stage 3 or greater, or symptomatic urinary tract infection
• Unable to fit in the device for any reason
• Taking anti-coagulants or anti-platelet agents, including aspirin if unable to be off this medication for medical reasons
• Implanted pacemakers and/or implanted defibrillator devices
• DXA T-Score less than -2.5. Scans done will include total body, dual hips and knees. Total hip BMD T-scores < -3.5 and knee BMD scores of less than 0.6 g/cm2
• Functional upper and lower extremity ROM, strength, spasticity and skin integrity will also have assessed prior to enrollment in the program.

• The Modified Ashworth Scale will be used to ensure safety of the participants prior to engagement in the rehabilitation program

• Participants with severe spasticity or limited ROM will be excluded from the trial
• This is based on the Ekso manufacturer's recommendations
• Untreatable severe spasticity judged to be contraindicated by the site Physician
• Pressure ulcer of the trunk, pelvic area, or lower extremities of grade 3 or more
• Psychopathology documentation in the medical record or history that may conflict with study objectives
• Any condition that, in the judgment of the principal investigator or medical provider, precludes safe participation in the study and/or increases the risk of infection