Effects of bihemispheric transcranial direct current stimulation on motor recovery in subacute stroke patients: a double-blind, randomized sham-controlled trial

Abstract

Background Bihemispheric transcranial direct current stimulation (tDCS) of the primary motor cortex (M1) can simultaneously modulate bilateral corticospinal excitability and interhemispheric interaction. However, how tDCS affects subacute stroke recovery remains unclear. We investigated the effects of bihemispheric tDCS on motor recovery in subacute stroke patients. Methods We enrolled subacute inpatients who had first-ever ischemic stroke at subcortical regions and moderate-to-severe baseline Fugl-Meyer Assessment of Upper Extremity (FMA-UE) score 2–56. Participants between 14 and 28 days after stroke were double-blind, randomly assigned (1:1) to receive real (n = 13) or sham (n = 14) bihemispheric tDCS (with ipsilesional M1 anode and contralesional M1 cathode, 20 min, 2 mA) during task practice twice daily for 20 sessions in two weeks. Residual integrity of the ipsilesional corticospinal tract was stratified between groups. The primary efficacy outcome was the change in FMA-UE score from baseline (responder as an increase ≥ 10). The secondary measures included changes in the Action Research Arm Test (ARAT), FMA-Lower Extremity (FMA-LE) and explorative resting-state MRI functional connectivity (FC) of target regions after intervention and three months post-stroke. Results Twenty-seven participants completed the study without significant adverse effects. Nineteen patients (70%) had no recordable baseline motor-evoked potentials (MEP-negative) from the paretic forearm. Compared with the sham group, the real tDCS group showed enhanced improvement of FMA-UE after intervention (p < 0.01, effect size η2 = 0.211; responder rate: 77% vs. 36%, p = 0.031), which sustained three months post-stroke (p < 0.01), but not ARAT. Interestingly, in the MEP-negative subgroup analysis, the FMA-UE improvement remained but delayed. Additionally, the FMA-LE improvement after real tDCS was not significantly greater until three months post-stroke (p < 0.01). We found that the individual FMA-UE improvements after real tDCS were associated with bilateral intrahemispheric, rather than interhemispheric, FC strengths in the targeted cortices, while the improvements after sham tDCS were associated with predominantly ipsilesional FC changes after adjustment for age and sex (p < 0.01). Conclusions Bihemispheric tDCS during task-oriented training may facilitate motor recovery in subacute stroke patients, even with compromised corticospinal tract integrity. Further studies are warranted for tDCS efficacy and network-specific neuromodulation. Trial registration: This study is registered with ClinicalTrials.gov: (ID: NCT02731508).

Transcranial direct current stimulation for upper extremity motor dysfunction in poststroke patients: A systematic review and meta-analysis

“…The included studies 18–61 involved 1555 patients (experimental group: 820, control group: 715) and were published between 2010 and 2024 in 20 countries. The top three countries based on the number of research studies were Italy ( n = 10), China ( n = 9), and the United States ( n = 5).…”

“…Taud et al 53 utilized anodal and bilateral stimulation for the experimental groups, while Qu et al 46 employed 1 and 2 mA of cathodal stimulation for the experimental groups. Fifteen studies 21,22,24–26,29,32,37,38,42,47,50,55,56,61 exclusively utilized anodal stimulation for the experimental group, 19 18–20,23,28,31,34–36,39,41,43,45,51,52,54,57,58,62 exclusively utilized bilateral stimulation for the experimental group, and four 27,40,48,59 exclusively utilized cathodal stimulation for the experimental group (Table 1). Additionally, 39 studies 18–23,26–28,30–40,42…”

“…Fifteen studies 21,22,[24][25][26]29,32,37,38,42,47,50,55,56,61 exclusively utilized anodal stimulation for the experimental group, 19 [18][19][20]23,28,31,[34][35][36]39,41,43,45,51,52,54,57,58,62 exclusively utilized bilateral stimulation for the experimental group, and four 27,40,48,59 exclusively utilized cathodal stimulation for the experimental group (Table 1). Additionally, 39 studies [18][19][20][21][22][23][26][27][28][30][31]…”

Dual‐tDCS combined with sensorimotor training promotes upper limb function in subacute stroke patients: A randomized, double‐blinded, sham‐controlled study

“…presented that dual‐tDCS combined with constraint‐induced movement therapy can significantly improve FMA–UE scores in patients with chronic stroke. Hsu et al 26 . indicated that bihemispheric tDCS during task‐oriented training may facilitate motor recovery in subacute stroke patients.…”

“…24 Studies have shown that bilateral dual-tDCS can more effectively regulate cortical excitability and improve upper limb function than unilateral tDCS. [25][26][27] Furthermore, a recent systematic review and meta-analysis indicated that stimulation of the primary somatosensory cortex (PSC) showed significant therapeutic potential to improve sensorimotor function in patients with stroke. 28 Accordingly, dual-tDCS over PSC has the potential to amend inter-hemispheric imbalance in subacute stroke.…”