Neurorehabilitation in spinal cord injury: Increased cortical activity through tDCS and robotic gait training

Abstract

Objective: This study investigates the neurophysiological outcomes of combining robot-assisted gait training (RAGT) with active transcranial direct current stimulation (tDCS) on individuals with spinal cord injury (SCI).

Methods: This randomized, double-blind, parallel clinical trial included 26 individuals with incomplete SCI. Participants were allocated to receive either active (n = 13) or sham (n = 13) tDCS followed by RAGT using the Lokomat system. The anode was placed over the leg motor representation region of the primary motor cortex (M1). Functional near-infrared spectroscopy (fNIRS) assessed the cerebral cortex's hemodynamic response before and after 30 sessions of intervention (3 times a week over 12 weeks or 5 times a week over 6 weeks). The clinical outcome was the change in the Walking Index Spinal Cord Injury II (WISCI-II) scale.

Results: The active tDCS group showed significant improvements in oxyhemoglobin (oxy-Hb) concentration in the Supplementary Motor Area (SMA) and the Primary Motor Cortex (M1) post-intervention. These changes were positively correlated with improvements in the WISCI-II scale, indicating enhanced gait recovery. No significant differences were observed in the Dorsolateral Prefrontal Cortex (DLPFC) and Primary Somatosensory Cortex (S1). The lower proportion of tetraplegic participants in the active compared to the sham should be acknowledged as a limitation.

Conclusion: The combination of RAGT and active tDCS leads to increased neural activity in the M1 and SMA, regions critical for motor planning and execution. This enhanced activity is associated with improved gait recovery.

Significance: These findings suggest that integrating neuromodulation with physical rehabilitation may optimize recovery outcomes, potentially through mechanisms involving increased cortical excitability.

Keywords: Brain; Motor function recovery; Neuromodulation; Walking; fNIRS.