Hybrid 12-Month Exoskeleton Training with Percutaneous Epidural Stimulation After Spinal Cord Injury

Background: Exoskeleton-assisted walking (EAW) is an effective method of rehabilitation that improves ambulation as well as independence in individuals with chronic spinal cord injury (SCI). Percutaneous spinal cord epidural stimulation (SCES) is another strategy that has shown promising results for promoting locomotor recovery in persons with SCI. We hypothesized that the hybrid application of SCES with EAW for 12 months would further enhance motor performance after SCI. Methods: Four males with chronic motor complete SCI underwent permanent implantation with percutaneous SCES. Participants were assigned to either 12 months of EAW + SCES or EAW without SCES [three times weekly] for the first 6 months, followed by an additional 6 months of EAW + SCES + resistance training (RT) or EAW+ delayed SCES + no RT [3-5 times per week]. Weekly exoskeleton data were captured and averaged for every 2-3 sessions using the Ekso Pulse platform to measure exoskeleton performance parameters. Exoskeleton assistance modes started with fixed assistance for the first six months of the trial and were followed by another six months of adaptive assistance. Results: The four participants completed 41 ± 7 weeks of the designated 48 weeks (85%). The up time across the entire study was 61 ± 6 min, and the EAW time was 46 ± 3 min. The overall number of steps, distance, and speed were 1315 ± 291, 426 ± 113 m, and 0.16 ± 0.04 m/s, respectively. Steps per minute, EAW distance, and speed were higher during sessions with the adaptive-assistance mode compared to the fixed mode. However, this was accompanied by a decrease in the level of assistance or percentage of minimum assistance provided by the exoskeleton. Conclusions: Twelve months of hybrid EAW with SCES resulted in an increase in steps per minute, distance, and EAW speed during adaptive mode in persons with SCI. The findings may serve as the basis for future studies to consider hybrid integration of exoskeletons with neuromodulation techniques to further enhance rehabilitation potential after SCI.