Ineffective voluntary motor improvement through non-invasive BCI-FES with static magnetic field in complete spinal cord injury: A pilot study

In response to the challenge of spinal cord injury (SCI) rehabilitation, this study aimed to investigate the effect of applying a non-invasive interface of surface neuroelectrical signals and functional electrical stimulation (sNES-sFES) with a static magnetic field on the motor outcome of the quadriceps femoris muscle in an individual with a complete SCI. The participant, who had a complete SCI in the chronic stage, was evaluated before (pre) and after nine (post) interventions using surface electromyography (sEMG). In addition, spasticity (modified Ashworth scale [MAS]) was observed in all sessions. Moreover, the user learning curve process (classifier percentage and correct success of the sFES hits) was evaluated. In general, we observed: (i) No voluntary muscle contraction (pre- and post-root mean square of sEMG = 0%) improvement; (ii) spasticity decrease (average one point in MAS); (iii) gradual improvement in the user learning effect on the interface, reaching 84% in classifier accuracy and a maximum percentage of correct sFES activation of 53%. In conclusion, no improvement in voluntary muscular contraction was observed within 9 weeks of the intervention (1 session/day; 1 h/week). However, our study demonstrates the safety and feasibility of our methodology for future research involving continuous physical rehabilitation training and the implementation of assistive technology.