Spinal cord injury (SCI) can cause paralysis and functional disability, resulting in changes in strength and sensation. Rehabilitation is important for regaining independence, but short hospital stays and limited access to specialized clinics pose challenges. Telerehabilitation offers a solution by providing remote rehabilitation services.

Physical exercise and functional training are important for improving functional activity and endurance after SCI. Telerehabilitation has shown significant improvements in functional activity. However, the most effective gains occur within the first year after the injury, and rehabilitation training alone may not achieve full recovery. Impairments below the injury level can lead to changes in brain organization. Combining training with a top-down approach may promote motor recovery after SCI.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique used in neurorehabilitation. It can modulate neural activity in the primary motor cortex at both cortical and spinal levels and induce synaptic plasticity. Studies have shown that adjusting the intensity or duration of tDCS can enhance its effectiveness, with anodal stimulation increasing cortical excitability and cathodal stimulation decreasing it. Home-based tDCS is a safe, accessible, and convenient alternative to hospital-based tDCS. Previous research has suggested a positive trend for combining anodal tDCS with rehabilitation training in individuals with incomplete spinal cord injury. Strong arm endurance is crucial for individuals with complete SCI who require independent transfers and wheelchair use. Studies in healthy adults have demonstrated that tDCS combined with exercise can improve upper arm endurance. However, there is currently no research on the effects of tDCS combined with rehabilitation in improving functional skills for individuals with complete SCI, especially when applied through home-based tDCS with telerehabilitation.

In the early stages of spinal shock following a severe spinal cord injury (SCI), the H-reflex, a reflex measure of spinal cord excitability, is typically absent or significantly reduced below the injury site. The degree and duration of this reflex suppression indicate the severity of the injury. This loss of reflex activity is thought to result from decreased excitability of motoneurons due to the sudden loss of input from the brain. However, the H-reflex gradually starts to recover after the initial spinal shock phase. In patients with chronic complete spinal cord lesions, an increased H-reflex amplitude in the soleus muscle suggests heightened central synaptic excitability, which may contribute to the development of hyperreflexia after SCI. Recent research has shown that anodal tDCS can decrease the H/M ratio (the ratio of H-reflex to M-response) and H-reflex latency, leading to improved spasticity in patients with neurological conditions.

This study aims to investigate the impact of combining tDCS with self-exercise at home over a one-month training period. The training will involve three sessions per week for four weeks. The assessment will include measures of motor function, functional activity, spasticity (evaluated through neurological assessment of H-reflex latency and H/M amplitude ratio), and quality of life. The participants will interact with a physical therapist through a video online platform for each of the 12 sessions. Assessments will be conducted before and after the intervention, as well as at a one-month follow-up.