Offline effects of transcranial direct current stimulation on reaction times of lower extremity movements in people after stroke: a pilot cross-over study.
Milou J M Coppens, Wouter H A Staring, Jorik Nonnekes and 2 others
PMID 31699109WHAT IT FOUND
Single-session tDCS did not improve reaction times for lower-limb movements in people with chronic stroke.
Participants with poor leg function actually showed slower reaction times with cathodal stimulation, while those with good function showed minor, likely clinically irrelevant gains.
Key findings
01Neither anodal nor cathodal tDCS accelerated tibialis anterior reaction times during voluntary ankle dorsiflexion, gait initiation, or balance recovery compared to sham.
02Individual effects of cathodal tDCS on ankle dorsiflexion reaction times correlated with leg motor function: participants with poorer function experienced detrimental effects (slower reactions), while those with better function experienced modest gains.
03A small increase in body sway after anodal tDCS during balance perturbation was statistically significant but considered clinically irrelevant by the authors.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study was a small pilot with only 13 participants, resulting in low statistical power and a high risk of type II error (missing a true effect). The authors note that despite low power, the trend for active tDCS was slightly slower than sham, making a missed benefit unlikely. The study only tested single-session offline effects; it does not rule out benefits from repeated sessions combined with training. Participants were relatively high-functioning (Berg Balance Scale mean 54/56), so results may not generalize to those with severe balance impairments.
Declared interests
Funded by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO). The authors declared no conflicts of interest.
The easy way to misread this
Do not interpret the correlation between leg function and cathodal tDCS effects as evidence that tDCS can be personalized to improve gait. The overall primary outcome was null, and the 'benefit' in high-functioning patients was small (16 ms) and not clinically significant, while low-functioning patients worsened.