Cortical Neural Plastic Changes Post-stroke Using Bicephalic Transcranial Direct Current Stimulation: A Prospective Non-randomized Study.

Background Transcranial direct current stimulation (tDCS) has attracted attention among researchers as it has significant neurorehabilitative effects post-stroke. The purpose of the study was to investigate the safety, feasibility, and probable efficacy of bicephalic tDCS in improving hand function after stroke. Methods We conducted a prospective non-randomized controlled study involving two groups of participants with chronic stroke. Participants were allocated to real tDCS (r-tDCS) and age-matched controls to sham tDCS (s-tDCS). The treatment session was for 20 minutes, along with physiotherapy for four weeks. The primary outcome measure was the Fugl-Meyer assessment (FMA), while secondary outcomes were the Action Research Arm Test (ARAT), modified Barthel Index (mBI), Brunnstrom stage, and functional magnetic resonance imaging (fMRI) measures. All the assessments were done at baseline, four weeks, and three months. Results Ninety-five patients were recruited. No side effects were reported. FMA (d=0.75; 95% CI: 1.17 to 0.34; p=0.03) and mBI (d=0.70; 95% CI: 1.11 to 0.19; p=0.04) showed significant improvement at three months, although mean FMA was higher in r-tDCS than s-tDCS at four weeks. ARAT and Medical Research Council (MRC) were statistically insignificant between the groups at all time points. A mild increase in the cluster counts of premotor and primary motor cortex (Brodmann area (BA) 4 and BA 6) in group 1 was observed at four weeks and three months. Conclusion The novel intervention tDCS was safe and compliant among subjects but failed to report a significant efficacy between the two groups. A greater neural activation of ipsilesional primary motor regions (BA 4 and BA 6) and a weak positive correlation of FMA with laterality index (LI) were observed in the r-tDCS group than the s-tDCS group which may have led to improved hand function.