Combining neuromodulation strategies in spinal cord injury gait rehabilitation: A proof of concept, randomized, crossover trial.

OBJECTIVE: To evaluate if acute intermittent hypoxia (AIH) coupled with transcutaneous spinal cord stimulation (tSCS) enhance task-specific training and lead to superior and more sustained gait improvements as compared to each of these strategies used in isolation in persons with chronic, incomplete spinal cord injury (SCI). DESIGN: Proof of concept, randomized crossover trial SETTING: Outpatient, rehabilitation hospital INTERVENTIONS: Ten participants completed 3 intervention arms: 1) AIH, tSCS, and gait training (AIH + tSCS), 2) tSCS plus gait training (SHAM AIH + tSCS), and 3) gait training alone (SHAM + SHAM). Each arm consisted of 5 consecutive days of intervention with a minimum of a 4-week washout between arms. The order of arms was randomized. The study took place from December 3, 2020 to January 4, 2023. MAIN OUTCOME MEASURES: 10-meter walk test (10MWT) at self-selected velocity (SSV) and fast velocity (FV), 6-minute walk test (6MWT), Timed Up and Go (TUG) SECONDARY OUTCOME MEASURES: Isometric ankle plantarflexion and dorsiflexion torque RESULTS: TUG improvements were 3.44 seconds (95% CI: 1.24-5.65) significantly greater in the AIH + tSCS arm than the SHAM AIH + tSCS arm at post-intervention (POST) and 3.31 seconds (95% CI: 1.03-5.58) greater than the SHAM + SHAM arm at 1-week follow up. SSV was 0.08 m/s (95% CI: 0.02-0.14) significantly greater following the AIH + tSCS arm than the SHAM AIH + tSCS at POST. Although not significant, the AIH + tSCS arm also demonstrated the greatest average improvements compared to the other two arms at POST and 1WK for the 6MWT, FV, and ankle plantarflexion torque. CONCLUSIONS: This pilot study is the first to demonstrate that combining these three neuromodulation strategies leads to superior improvements in the TUG and SSV for individuals with chronic incomplete SCI and warrants further investigation.

Noninvasive spinal stimulation improves walking in chronic stroke survivors: a proof-of-concept case series.

BACKGROUND: After stroke, restoring safe, independent, and efficient walking is a top rehabilitation priority. However, in nearly 70% of stroke survivors asymmetrical walking patterns and reduced walking speed persist. This case series study aims to investigate the effectiveness of transcutaneous spinal cord stimulation (tSCS) in enhancing walking ability of persons with chronic stroke. METHODS: Eight participants with hemiparesis after a single, chronic stroke were enrolled. Each participant was assigned to either the Stim group (N = 4, gait training + tSCS) or Control group (N = 4, gait training alone). Each participant in the Stim group was matched to a participant in the Control group based on age, time since stroke, and self-selected gait speed. For the Stim group, tSCS was delivered during gait training via electrodes placed on the skin between the spinous processes of C5-C6, T11-T12, and L1-L2. Both groups received 24 sessions of gait training over 8 weeks with a physical therapist providing verbal cueing for improved gait symmetry. Gait speed (measured from 10 m walk test), endurance (measured from 6 min walk test), spatiotemporal gait symmetries (step length and swing time), as well as the neurophysiological outcomes (muscle synergy, resting motor thresholds via spinal motor evoked responses) were collected without tSCS at baseline, completion, and 3 month follow-up. RESULTS: All four Stim participants sustained spatiotemporal symmetry improvements at the 3 month follow-up (step length: 17.7%, swing time: 10.1%) compared to the Control group (step length: 1.1%, swing time 3.6%). Additionally, 3 of 4 Stim participants showed increased number of muscle synergies and/or lowered resting motor thresholds compared to the Control group. CONCLUSIONS: This study provides promising preliminary evidence that using tSCS as a therapeutic catalyst to gait training may increase the efficacy of gait rehabilitation in individuals with chronic stroke. Trial registration NCT03714282 (clinicaltrials.gov), registration date: 2018-10-18.