Effect of Transcranial Direct Current Stimulation on Postural Stability and Lower Extremity Strength in Hemiplegic Stroke Patients

OBJECTIVE To evaluate the effect of anodal transcranial direct current stimulation (tDCS) over the lesioned leg motor cortex, which can enhance the strength and coordination of the contralateral lower extremity and furthermore, enhance the postural stability of the hemiplegic subject. METHODS Anodal or sham stimulation on the lesioned cortex of a lower extremity was delivered to 11 ambulatory hemiplegic patients. The stimulation intensity was 2 mA. All subjects took part in two 10-minute tDCS sessions consisting of anodal stimulation and sham stimulation. The interval period between real and sham stimulation was 48 hours. The order was counter-balanced among the subjects. Before and after each stimulation session, static postural stability was evaluated with eyes opened and closed. Also, the isometric strength of the hemiplegic side of the treated knee was measured before and after each stimulation session. Repeated measure ANOVA was used to determine the statistical significance of improvements in postural stability and strength. RESULTS There was significant improvement for overall stability index with eyes opened and closed after anodal tDCS (p<0.05). Isometric strength of the lesioned quadriceps tended to increase after anodal tDCS (p<0.05). Postural stability and quadriceps strength were not changed after sham stimulation. CONCLUSION Anodal tDCS has potential value in hemiplegic stroke patients to improve balance and strengthen the affected lower extremity.