Nerve Stimulation Enhances Task-Oriented Training for Moderate-to-Severe Hemiparesis 3-12 Months After Stroke: A Randomized Trial

Abstract

Objective: The aim of the study was to determine whether somatosensory stimulation affects outcomes of motor training for moderate-to-severe upper limb hemiparesis less than 12 mos before stroke.

Design: Fifty-five adults participated in 18 intervention sessions pairing 2 hours of active (n = 33) or sham (n = 22) somatosensory stimulation with 4 hours of intensive task-oriented motor training. Wolf Motor Function Test, Action Research Arm Test, Fugl-Meyer Assessment, and Stroke Impact Scale were administered at baseline, postintervention, and 1- and 4-mo follow-up.

Results: Statistically significant between-groups differences favored the active condition on Wolf Motor Function Test at post (P = 0.04) and Action Research Arm Test at post (P = 0.02), 1 mo (P = 0.01), and 4 mos (P = 0.01) but favored the sham condition on Stroke Impact Scale at 1 mo (P = 0.03). There were no significant between-groups differences on Fugl-Meyer Assessment.

Conclusions: Somatosensory stimulation can improve objective outcomes of motor training for moderate-to-severe hemiparesis less than 12 mos after stroke, although it needs to be determined whether the magnitude of between-groups differences in this study is clinically relevant. Future studies should investigate the intervention's impact on disability and functional recovery for this population as well as neurophysiological mechanisms underlying intervention effects.

Trial registration: ClinicalTrials.gov NCT03124186.

Conflict of interest statement

There are no conflicts of interest related to this research or this manuscript. The clinical trial registration number with

Figures

Figure 1

Electrode Position and Pulse Train. This figure illustrates the placement of electrodes on the paretic upper extremity (UE) for delivery of somatosensory stimulation (SS) to the targeted nerves. The image in the lower left corner illustrates the timing of the pulse train.

Figure 2

Study Flow.

Figure 3

Graphs of Change on All Outcomes. Intervention-related changes on Wolf Motor Function Test (WMFT), Action Research Arm Test (ARAT), Fugl-Meyer Assessment (FMA), and Stroke Impact Scale (SIS) are shown. All graphs indicate mean change in score relative to baseline for each group. Change associated with active somatosensory stimulation is shown in the darker shade. To ensure the appropriateness of statistical assumptions, the square root was applied to ARAT and log(mean WMFT) values. WMFT and ARAT values were back-transformed to raw values to calculate the means and standard errors shown in order to facilitate interpretation of the results. However, the statistics shown are based on the transformed values. For WMFT, improvement is represented as a negative change along the y-axis. For ARAT, FMA, and SIS, improvement is depicted as positive change along the y-axis. Significant within-group change is denoted with a single asterisk. Significant between-groups difference is denoted with a double asterisk. Error bars denote 1 standard error of the mean (SEM).