Combining Neuromodulation Strategies to Improve Locomotor Function in SCI: A Proof of Concept Case Study

Abstract

<h3>Research Objectives</h3> Acute intermittent hypoxia (AIH) and transcutaneous spinal cord stimulation (tSCS) are two non-invasive neuromodulation treatments that have been shown to individually induce spinal plasticity in persons with chronic incomplete spinal cord injury (iSCI). However, these two interventions have never been tested in combination to see if their combined effect is greater than each intervention alone. This proof of concept case study investigated how AIH combined with tSCS during ambulation training may facilitate improvements in walking function in individuals with iSCI. <h3>Design</h3> Single-blind, randomized, crossover trial. <h3>Setting</h3> Outpatient, Rehabilitation Hospital. <h3>Participants</h3> 1 participant (male, 70 years) with chronic iSCI. <h3>Interventions</h3> The participant completed 3 arms, in random order: 1. AIH+tSCS 2. Sham-AIH+Sham-tSCS 3. Sham-AIH+tSCS Each arm consisted of 5 treatment sessions on consecutive days. <h3>Main Outcome Measures</h3> Assessments were performed at Baseline, Post-intervention (Post), and 1-week follow-up (1WFU), with a 4-week wash out between arms. Changes in gait performance were measured using the 10-meter walk test (10MWT) for fast and comfortable speeds, and the 6-minute walk test (6MWT). <h3>Results</h3> Overall, the participant showed potential improvements in his walking performance with AIH+tSCS at Post, relative to Baseline (10MWT-Fast: 5.6%; 10MWT-Comfortable: 7.0%; 6MWT: 15.6%), with further improvements at 1WFU (10MWT-Fast: 6.9%; 10MWT-Comfortable: 19.2%; 6MWT: 19.3%). The participant also showed potential improvements at Post, relative to Baseline with Sham-AIH+Sham-tSCS (10MWT-Fast: 12.2%; 10MWT-Comfortable: 6.6%; 6MWT: 15.1%) and with Sham-AIH+tSCS (10MWT-Fast: -2.5%; 10MWT-Comfortable: 15.3%; 6MWT: 6.0%). However, sustained improvements were not present at 1WFU with the Sham-AIH+Sham-tSCS (10MWT-Fast: 3.8%; 10MWT-Comfortable: -2.5%; 6MWT: 8.3%) or Sham-AIH+tSCS (10MWT-Fast: -3.9%; 10MWT-Comfortable: -5.5%; 6MWT: -2.1%), suggesting the combined intervention yielded retention effects. <h3>Conclusions</h3> AIH +tSCS with gait training may promote persistent improvements in walking function compared to tSCS with gait training or gait training alone in persons with iSCI. Further studies are warranted to investigate this novel, combinational neuromodulation strategy. <h3>Author(s) Disclosures</h3> The authors have no conflicts of interest to disclose.