A Pilot Study of Intensive Locomotor-Related Skill Training and Transcranial Direct Current Stimulation in Chronic Spinal Cord Injury

Brief High-Velocity Motor Skill Training Increases Step Frequency and Improves Length/Frequency Coordination in Slow Walkers With Chronic Motor-Incomplete Spinal Cord Injury

OBJECTIVE

To quantify spatiotemporal coordination during overground walking among persons with motor-incomplete spinal cord injury (PwMISCI) by calculating the step length (SL)/step frequency (SF) ratio (ie, the Walk Ratio [WR]) and to examine the effects of motor skill training (MST) on the relationship between changes in these parameters and walking speed (WS).

DESIGN

Between-day exploratory analysis.

SETTING

Research laboratory in a rehabilitation hospital PARTICIPANTS: PwMISCI (N=26).

INTERVENTIONS

3-day high-velocity MST.

MAIN OUTCOME MEASURES

Overground WS, SL, SF, and WR measured during the 10-Meter Walk Test.

RESULTS

Among the full sample, MST was associated with increases in WS, SL, SF, and a decrease in the WR. Relative change in WS and SF was higher among slow (ΔWS=↑46%, ΔSF=↑28%) vs fast (ΔWS=↑16%, ΔSF=↑8%) walkers. Change in the WR differed between groups (slow: ΔWR=↓10%; fast: ΔWR=0%). Twenty-six percent of the variability observed in ΔWR among slow walkers could be explained by ΔSF, while ΔSL did not contribute to ΔWR. Among fast walkers, ΔSL accounted for more than twice the observed ΔWR (43%) compared to ΔSF (15%).

CONCLUSIONS

On the whole, WR values among PwMISCI are higher than previous reports in other neurologic populations; however, values among fast walkers were comparable to noninjured adults. Slow walkers demonstrated greater variability in the WR, with higher values associated with slower WS. Following MST, increases in WS coincided with a decrease in the WR among slow walkers, mediated primarily through an effect on SF. This finding may point to a specific mechanism by which MST facilitates improvements in WS among PwMISCI with greater mobility deficits.

Walking and Balance Outcomes Are Improved Following Brief Intensive Locomotor Skill Training but Are Not Augmented by Transcranial Direct Current Stimulation in Persons With Chronic Spinal Cord Injury

Motor training to improve walking and balance function is a common aspect of rehabilitation following motor-incomplete spinal cord injury (MISCI). Evidence suggests that moderate- to high-intensity exercise facilitates neuroplastic mechanisms that support motor skill acquisition and learning. Furthermore, enhancing corticospinal drive via transcranial direct current stimulation (tDCS) may augment the effects of motor training. In this pilot study, we investigated whether a brief moderate-intensity locomotor-related motor skill training (MST) circuit, with and without tDCS, improved walking and balance outcomes in persons with MISCI. In addition, we examined potential differences between within-day (online) and between-day (offline) effects of MST. Twenty-six adults with chronic MISCI, who had some walking ability, were enrolled in a 5-day double-blind, randomized study with a 3-day intervention period. Participants were assigned to an intensive locomotor MST circuit and concurrent application of either sham tDCS (MST+tDCS_sham) or active tDCS (MST+tDCS). The primary outcome was overground walking speed measured during the 10-meter walk test. Secondary outcomes included spatiotemporal gait characteristics (cadence and stride length), peak trailing limb angle (TLA), intralimb coordination (ACC), the Berg Balance Scale (BBS), and the Falls Efficacy Scale-International (FES-I) questionnaire. Analyses revealed a significant effect of the MST circuit, with improvements in walking speed, cadence, bilateral stride length, stronger limb TLA, weaker limb ACC, BBS, and FES-I observed in both the MST+tDCS_sham and MST+tDCS groups. No differences in outcomes were observed between groups. Between-day change accounted for a greater percentage of the overall change in walking outcomes. In persons with MISCI, brief intensive MST involving a circuit of ballistic, cyclic locomotor-related skill activities improved walking outcomes, and selected strength and balance outcomes; however, concurrent application of tDCS did not further enhance the effects of MST.