Effect of bihemispheric transcranial direct current stimulation on distal upper limb function and corticospinal tract excitability in a patient with subacute stroke: a case study.

Only one patient was studied, so this describes what happened to her and does not show that any treatment works. There was no control period, and the authors state that spontaneous recovery must be considered. The patient was in the subacute period after stroke, when recovery can still be changing. Ongoing hospital rehabilitation included physical therapy, occupational therapy, and speech therapy, and the stimulation was delivered with occupational therapy, so the contribution of tDCS alone cannot be separated. The design was retrospective, and the stimulation periods were given in a fixed order: anodal, then bihemispheric, then anodal. The authors did not measure interhemispheric inhibition or the left-right difference index, so their explanation for the changes is speculative. The paper does not say which patients or tDCS settings would work, and it notes that no standardized washout duration has been established.

Do not conclude that bihemispheric tDCS caused the wrist and finger improvements. This was one patient with subacute stroke, no control period, and ongoing rehabilitation, so spontaneous recovery and other therapy cannot be ruled out.