Effects of electrode configurations in transcranial direct current stimulation after stroke

Abstract

Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation that can modulate neuroplasticity (the capacity for brain reorganization). Neuroplastic change correlates with upper extremity (UE) recovery after brain lesions. Different electrode configurations of tDCS paired with UE motor training can have different effects in distinct populations. We are conducting the first randomized, double-blind, placebo-controlled trial to investigate which tDCS configuration may best enhance outcomes of UE motor training for stroke survivors with chronic, severe hemiparesis (i.e., little or no wrist or hand movement). We have assigned subjects to 1 of 4 groups: 1) "Anodal": anodal tDCS to excite ipsilesional motor cortex; 2) "Cathodal": cathodal tDCS to inhibit contralesional motor cortex; 3) "Dual": a simultaneous combination of anodal and cathodal tDCS; or 4) "Sham" tDCS. Intervention (10 sessions) consists of tDCS followed by 3 hours of intensive, task-oriented UE training in each session. Our primary outcome measure is Fugl-Meyer Assessment. Our secondary outcome measures are Action Research Arm Test and Stroke Impact Scale. We have conducted evaluations at baseline and post-intervention. Preliminary results from 26 of (projected) 44 subjects indicate substantially greater improvement for the "Cathodal" group than other groups. These findings differ from evidence about tDCS in rehabilitation of mild-to-moderate hemiparesis. Completion of our study will include full analysis of neuroplastic change associated with intervention.

The efficacy of transcranial direct current stimulation on upper extremity motor function after stroke: A systematic review and comparative meta‐analysis of different stimulation polarities

“…The mean age of the patients included in the studies in this review was 55 years, including men and women, with hemorrhagic and ischemic, cortical and subcortical strokes, in all stages of the disease (acute/ subacute 21,25,28,29 and chronic [21][22][23][24][25][26][27][30][31][32][33][34][35] ). Regarding stimulation polarity, four studies compared the effectiveness of a-tDCS, c-tDCS, and bihemispheric tDCS, as well as sham stimulation, 23,25,27,30 nine studies compared a-tDCS versus c-tDCS (of which seven included sham stimulation, 22,26,28,29,32,33,35 and two did not include sham stimulation 21,31 ), one study compared c-tDCS versus bihemispheric stimulation, 24 and one compared a-tDCS versus bihemispheric stimulation, including sham stimulation. 34 Among the included studies, eight performed UE motor training in addition to stimulation, 21,23,28,29,[31][32][33][34] whereas seven performed only tDCS stimulation.…”

“…Regarding stimulation polarity, four studies compared the effectiveness of a-tDCS, c-tDCS, and bihemispheric tDCS, as well as sham stimulation, 23,25,27,30 nine studies compared a-tDCS versus c-tDCS (of which seven included sham stimulation, 22,26,28,29,32,33,35 and two did not include sham stimulation 21,31 ), one study compared c-tDCS versus bihemispheric stimulation, 24 and one compared a-tDCS versus bihemispheric stimulation, including sham stimulation. 34 Among the included studies, eight performed UE motor training in addition to stimulation, 21,23,28,29,[31][32][33][34] whereas seven performed only tDCS stimulation. 22,[24][25][26][27]30,35 Sessions ranged from a single session 22,[25][26][27]30 to 3, 5,24,31,34,35 10, 23,29 12, 21,32 15, 33 and 30 sessions.…”

“…34 Among the included studies, eight performed UE motor training in addition to stimulation, 21,23,28,29,[31][32][33][34] whereas seven performed only tDCS stimulation. 22,[24][25][26][27]30,35 Sessions ranged from a single session 22,[25][26][27]30 to 3, 5,24,31,34,35 10, 23,29 12, 21,32 15, 33 and 30 sessions. 28 The duration of tDCS application was 10 minutes in one study, 31 15 minutes in one study, 27 20 minutes in 11 studies, [21][22][23][24][25][26][28][29][30]33,35 and 23 minutes in one study.…”

“…22,[24][25][26][27]30,35 Sessions ranged from a single session 22,[25][26][27]30 to 3, 5,24,31,34,35 10, 23,29 12, 21,32 15, 33 and 30 sessions. 28 The duration of tDCS application was 10 minutes in one study, 31 15 minutes in one study, 27 20 minutes in 11 studies, [21][22][23][24][25][26][28][29][30]33,35 and 23 minutes in one study. 34 Rocha et al 32 applied 13 minutes in the case of a-tDCS and 9 minutes in the case of c-tDCS.…”

“…33 The stimulation site was over the primary motor cortex (M1) in all studies. [29][30][31][32][33][34][35] The change in UE function was measured with the FMA-UE scale in seven studies, 21,23,28,29,31,32,34 the Jebsen Taylor hand function Test in four studies, 22,25,26,30 the Action Research Arm Test in one study, 24 the Wolf Motor Function Test in one study, 33 and the nine Hole Peg Test in one study. 27…”