Effects of transcranial direct current stimulation of primary motor cortex on cortical sensory deficits and hand dexterity in a patient with stroke: A case study

Fine motor and manual dexterity deficits are the main causes of significant physical and psychosocial impairments in stroke survivors. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique used to modulate brain activity and improve clinical outcomes. This study was performed to investigate the efficacy of dual-hemispheric tDCS of the primary motor cortex (M1) in a patient with stroke exhibiting cortical sensation deficits. A double-blind, sham-controlled, single-case study was conducted. The patient underwent 30 sessions of sham tDCS followed by 30 real-stimulation sessions over both M1 cortices. Each session involved 20 minutes of 2-mA stimulation (current density, 0.08 mA/cm(2); total charge density, 0.096 C/cm(2)). Functional measures were assessed using the Action Research Arm Test, grooved pegboard test, nine-hole peg test, and box and block test at several time points. Structural and diffusion tensor imaging data were acquired before (t(0)) and after (t(1)) stimulation. Slight improvements following sham tDCS were observed. However, following real stimulation, all results at all time points were clinically significant. Higher fractional anisotropy of the corticospinal tract and regional gray matter density were positively correlated with better recovery of fine motor skills. tDCS intervention induced functional improvement and structural changes in this patient with stroke.