Neurophysiological signatures of hand motor response to dual-transcranial direct current stimulation in subacute stroke: a TMS and MEG study.
I-Ju Kuo, Chih-Wei Tang, Yun-An Tsai and 8 others
PMID 32527268WHAT IT FOUND
Dual tDCS shifted brain activity in subacute stroke patients: it increased excitability in the damaged-side motor cortex and decreased it in the healthy-side cortex.
These neurophysiological changes mirrored those in healthy controls and correlated with the patients' existing hand function.
Key findings
01In stroke survivors, dual tDCS increased motor evoked potentials in the anode-targeted (ipsilesional) hemisphere and decreased them in the cathode-targeted (contralesional) hemisphere.
02The change in alpha-band event-related synchronization (ERS) in the ipsilesional motor cortex after real tDCS correlated positively with concurrent hand function scores (ARAT and FMA-UE).
03Baseline interhemispheric inhibition imbalance (iSP ratio) predicted the magnitude of the tDCS effect: patients with greater imbalance showed smaller increases in ipsilesional excitability.
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 mechanistic investigation of neurophysiological changes, not a clinical trial of functional recovery; it did not measure behavioral outcomes after repeated sessions. The sample size was small (18 patients), and the population was highly homogeneous (subacute, subcortical infarcts, mild-moderate paresis), limiting generalizability to other stroke profiles. The study only examined upper limb effects; lower limb responses and long-term retention of effects were not assessed.
Declared interests
Funded by the Ministry of Science and Technology (Taiwan), Taipei Veterans General Hospital, National Yang-Ming University, Wellcome Trust, and Royal Society. No specific conflicts of interest regarding commercial tDCS devices were declared in the text.
The easy way to misread this
Do not interpret these neurophysiological changes as evidence that dual tDCS improves hand function. The study measured immediate brain responses in a small, homogeneous group of subacute patients and did not assess functional outcomes or long-term recovery.