Positive effects of tDCS cortical stimulation on the walking performance of chronic hemiplegic patients

Abstract

To evaluate the effect of a single session of stimulation of the primary motor cortex (M1) with tDCS versus placebo (SHAM) on the walking performance of hemiplegic patients at a chronic stage. Randomized, cross-over, double-blind study. Eighteen patients (6 women, 12 men, mean age: 60 years) were included. They suffered an initially complete hemiplegia due to a single stroke older than 6 months (min: 14 months, max: 11 years). Each patient participated in a single anodal stimulation session (2 mA, 20 minutes) of the area of the lower limb ipsilesional M1 (STIM condition) and a pseudo-stimulation session (SHAM condition). The order of the two sessions was randomly assigned, with an 11-day interval between the two sessions. The anodal electrode was positioned on the hotspot previously identified with TMS. The cathode was placed above the contralesional orbit. The walking performances were evaluated with the Wade Test and the 6-Minute Walking Test (6MWT). These tests were performed during the stimulation and after 1 h, and 2 days before and 10 days after each session. The Wade Test and 6MWT showed a linear progression from the first pre-stimulation evaluation until the last evaluation (Wade average + 20% + 21% average 6MWT). To overcome this progression, comparisons were based on the linearly corrected data of each patient. The comparison between the 6MWT under STIM versus SHAM conditions demonstrated a significant positive effect of the stimulation by 11% during stimulation (Wilcoxon matched pairs, P = 0.019) and 6% 1 hour after stimulation (Wilcoxon matched pairs, P = 0.025). There is no significant difference regarding the Wade Test. These results show a significant positive effect of a single session of anodal tDCS of the M1 ipsilesional area of the lower limb in chronic hemiplegic patients. This improvement affects the endurance (6MWT) but not the walking speed (Wade Test). This proof of principle study supports a follow-up study assessing the training of walking under iterative tDCS stimulation.