bihemispheric-tDCS and Upper Limb Rehabilitation Improves Retention of Motor Function in Chronic Stroke: A Pilot Study

Abstract

Background: Single sessions of bihemispheric transcranial direct-current stimulation (bihemispheric-tDCS) with concurrent rehabilitation improves motor function in stroke survivors, which outlasts the stimulation period. However few studies have investigated the behavioral and neurophysiological adaptations following a multi-session intervention of bihemispheric-tDCS concurrent with rehabilitation.Objective: This pilot study explored the immediate and lasting effects of 3-weeks of bihemispheric-tDCS and upper limb (UL) rehabilitation on motor function and corticospinal plasticity in chronic stroke survivors.Methods: Fifteen chronic stroke survivors underwent 3-weeks of UL rehabilitation with sham or real bihemispheric-tDCS. UL motor function was assessed via the Motor Assessment Scale (MAS), Tardieu Scale and grip strength. Corticospinal plasticity was indexed by motor evoked potentials (MEPs), cortical silent period (CSP) and short-interval intracortical inhibition (SICI) recorded from the paretic and non-paretic ULs, using transcranial magnetic stimulation (TMS). Measures were taken at baseline, 48 h post and 3-weeks following (follow-up) the intervention.Results: MAS improved following both real-tDCS (62%) and sham-tDCS (43%, P < 0.001), however at 3-weeks follow-up, the real-tDCS condition retained these newly regained motor skills to a greater degree than sham-tDCS (real-tDCS 64%, sham-tDCS 21%, P = 0.002). MEP amplitudes from the paretic UL increased for real-tDCS (46%: P < 0.001) and were maintained at 3-weeks follow-up (38%: P = 0.03), whereas no changes were observed with sham-tDCS. No changes in MEPs from the non-paretic nor SICI from the paretic UL were observed for either group. SICI from the non-paretic UL was greater at follow-up, for real-tDCS (27%: P = 0.04). CSP from the non-paretic UL increased by 33% following the intervention for real-tDCS compared with sham-tDCS (P = 0.04), which was maintained at 3-weeks follow-up (24%: P = 0.04).Conclusion: bihemispheric-tDCS improved retention of gains in motor function, which appears to be modulated through intracortical inhibitory pathways in the contralesional primary motor cortex (M1). The findings provide preliminary evidence for the benefits of bihemispheric-tDCS during rehabilitation. Larger clinical trials are warranted to examine long term benefits of bihemispheric-tDCS in a stroke affected population.

Non-Invasive Brain Stimulation to Enhance Post-Stroke Recovery

“…Moreover, cerebral functional magnetic resonance imaging (fMRI) showed a stronger activation of the ipsilesional primary and premotor cortex during paced movements of the affected limb in the real stimulation group only. The same gain of function was obtained by others (Stagg et al, 2012 ; Goodwill et al, 2016 ), but in this last study, patients were separated into three groups evaluating separately the three conditions (cathodal vs. anodal vs. sham stimulation) although a lesser effect on hand motor deficit was observed (5–10%). In the same line, Rocha et al ( 2016 ) compared these three strategies to constraint induced movement therapy, in order to reinforce the “rebalancing” of cortical excitability between the two hemispheres.…”

Home-based transcranial direct current stimulation plus tracking training therapy in people with stroke: an open-label feasibility study

“…Rabadi and Aston (2017) demonstrated large effect size improvements in motor function in eight participants with severe motor impairments after acute stroke after applying tDCS for 30 min with 3 h of inpatient rehabilitation therapy, compared to a control group who received sham tDCS and therapy [ 53 ]. Several studies have demonstrated retained improved motor abilities between 3 weeks and 3 months post-intervention in chronic stroke after a treatment that combined physical therapy with tDCS stimulation [ 12 , 54 , 55 ].…”

Gamma absolute power reveals activation of motor areas after hand immobilization

“…39 The inter-hemispheric differences in gamma band absolute power after immobilization are justified by the ability of the hemispheres to mutually influence their functions through the corpus callosum. 4,40,41 These findings may have a bearing on the applicability of therapies such as transcranial magnetic stimulation, constraintinduced movement therapy, which are widely used in the rehabilitation of stroke [42][43][44] and cerebral palsy. [45][46][47] Some studies even indicate the possibility of using the EEG as a central nervous system dysfunctions marker.…”