Neuroplasticity is believed to be an important mechanism related to motor improvement of spinal cord injury (SCI) during rehabilitation program, which may be enhanced using transcranial direct-current stimulation (tDCS). The better understanding of this process is important for the improvement of rehabilitation therapy since it can be used as a prognostic biomarker, surrogate outcome and to guide the parameters of tDCS.

Functional Near Infrared Spectroscopy (fNIRS) is an instrument to measures hemodynamic responses in the brain, which allows studying functional brain connectivity reorganization. So, this study aims to demonstrate the feasibility of fNIRS to evaluate real-time activation of motor cortex SCI patients during robot-assisted gait. Besides, to compare changes induced by active vs. sham tDCS.

It is a preliminary analysis of SCI patients enrolled in a randomized double-blind clinical trial, with two arms (active tDCS vs. sham tDCS). Both groups received 30 sessions of tDCS for 20 minutes immediately before gait training with robotic-assisted device Lokomat-Pro® (Hocoma).

For fNIRS, 32 optodes was positioned parallel to the coronal plane. Software and hardware are from NIRX Medical Technologies. The differential hemoglobin index at rest (standing) and during movement were evaluated using paired T-test. The null hypothesis was that during gait, metabolic consumption would increase in the primary motor cortex (M1).

Patients had an enhanced activation of M1, next to Cz, C1 and C2 (10-20 EEG system) during gait, when compared with standing position. This activation seems to be higher in active group comparing to sham group ( Fig. 1 ).

This study shows the viability of use fNIRS to measure brain activity of SCI patients during robot-assisted gait. Future analyses, with a larger sample, are necessary to confirm these findings and correlate it with clinical outcomes.