Resting-state hemodynamic changes and effects on upper limb function after multi-channel transcranial direct current stimulation to the ipsilesional primary motor cortex and anterior intraparietal sulcus in stroke patients: an fNIRS pilot study

BackgroundStroke results in substantial long-term disability, necessitating effective recovery interventions. This study explored the effects of multi-channel transcranial direct current stimulation (tDCS) on hemodynamic responses and upper limb motor function in stroke patients, targeting the ipsilesional primary motor cortex (M1) and anterior intraparietal sulcus (aIPS).MethodsA double-blind, randomized, sham-controlled trial was conducted with 24 stroke patients (18 men; mean age, 57.3x14.2 years), who underwent 10 sessions of real or sham multi-channel tDCS combined with upper limb exercises. Functional near-infrared spectroscopy (fNIRS) measured resting-state cerebral hemodynamic responses for 5 min before and after each session. Motor function was evaluated using the Fugl-Meyer assessment for upper extremity (FMA-UE), box and block test (BBT), and other motor function tests before and after the interventions.ResultsThe real multi-channel tDCS group exhibited increases in regional accumulation of oxyhemoglobin (HbOAcc) and stronger seeded connectivity networks within the motor cortex poststimulation. In contrast, the sham group exhibited disassociation from these areas. The group x time interaction was significant for the Box and Block Test (BBT), indicating greater improvements in gross manual dexterity in the real-tDCS group compared to the sham group. While poststimulation changes in HbOAcc were examined in relation to FMA-UE scores, no strong linear relationship was observed in the real-tDCS group.ConclusionsMulti-channel tDCS targeting the ipsilesional M1 and aIPS, combined with upper limb exercises, showed potential effects on cerebral hemodynamics and motor function in stroke patients. These findings suggest that multi-channel tDCS may have a role in motor rehabilitation, but further research is needed to validate its efficacy and clinical applicability.ClinicalTrials.govThis study was registered at ClinicalTrials.gov (NCT05275114).