Effects of anodal and cathodal transcranial direct current stimulation combined with robotic therapy on severely affected arms in chronic stroke patients

The purpose of this study was to examine the effects of combined therapy using transcranial direct current stimulation (tDCS) with robot-assisted arm training (AT) for impairment of the upper limb in chronic stroke patients, and to clarify whether differences exist in the effect of anodal tDCS on the affected hemisphere (tDCS(a) + AT) and cathodal tDCS on the unaffected hemisphere (tDCS(c) + AT). Subjects in this randomized, double-blinded, crossover study comprised 18 chronic stroke patients with moderate-to-severe arm paresis. Each patient underwent 2 different treatments: tDCS(a) + AT; and tDCS(c) + AT. Each intervention was administered for 5 days, and comprised AT with 1 mA of tDCS during the first 10 min. Outcomes were identified as changes in Fugl-Meyer Assessment (FMUL), modified Ashworth scale (MAS) and Motor Activity Log (MAL) for the upper limb. Both interventions showed significant improvements in FMUL and MAS, but not in MAL. Distal spasticity was significantly improved with tDCS(c) + AT compared with tDCS(a) + AT for right hemispheric lesions (median -1 vs 0), but not for left hemispheric lesions. Although this study demonstrated that combined therapy could achieve limited effects in the hemiplegic arm of chronic stroke patients, a different effect of polarity of tDCS was seen for patients with right hemispheric lesions.