Structural Mechanisms of Dual-Target tDCS in Stroke Hemiparetic Hand

Multimodal MRI-Based Study of the Structural Mechanisms Underlying Interhemispheric Network Reorganization Induced by Dual-Target tDCS in Stroke Hemiparetic Hand

This is a single-center, randomized, single-blind study investigating the effects of dual-target transcranial direct current stimulation (tDCS) combined with task-oriented functional electrical stimulation on upper limb recovery in patients with non-acute post-stroke hemiplegia. A total of 56 participants will be recruited and randomly assigned (1:1) to the dual M1 tDCS group or sham stimulation group. The intervention is delivered five times per week for four weeks, with 20 sessions in total. Multimodal MRI (T1W, T2W, and DTI) will be used to assess structural and network-level reorganization of sensorimotor pathways, including the corticospinal tract, in response to tDCS.

The primary outcome is the Broetz hand function score, evaluated at baseline, post-intervention, and six-month follow-up. Secondary outcomes include Fugl-Meyer Assessment of the upper extremity (FMA-UE) and multimodal MRI-derived measures of white matter integrity. This study aims to elucidate the structural constraints underlying sensorimotor network lateralization and to identify responder and non-responder profiles based on corticospinal tract damage, providing mechanistic insight into individualized tDCS-based neurorehabilitation after stroke.

Inclusion Criteria:

1. Diagnosed with stroke according to the "Diagnostic Criteria for Major Cerebrovascular Diseases in China, 2019", confirmed by cranial CT or MRI.
2. First-ever unilateral subcortical stroke (involving the corona radiata, basal ganglia, thalamus, internal capsule, etc.).
3. Age 30-75 years.
4. Right-handed prior to stroke onset.
5. Stroke onset ≥ 2 weeks.
6. Hemiplegic hand function at Brunnstrom Stage I-III.
7. Written informed consent provided by the patient or legally authorized representative.

Exclusion Criteria:

1. Any contraindications to MRI.
2. History of other neurological disorders or substance abuse.
3. Unstable conditions or rapidly progressive/malignant diseases, e.g., severe atrial fibrillation.
4. Severe skin allergies.
5. Inability to cooperate with basic communication or assessments, such as severe aphasia.