A Pilot Study of Brain-Triggered Electrical Stimulation with Visual Feedback in Patients with Incomplete Spinal Cord Injury

Improvement of upper extremity function is one of the greatest needs in patients with tetraplegia. Functional electrical stimulation (FES) directly controlled by the patient's intention, through a brain-machine interface (BMI), could be used with a rehabilitative purpose. To date, there is scarce evidence about the feasibility of these systems in patients with incomplete spinal cord injury (iSCI), as studies usually focus on assistive technologies for complete injuries. The aim of this work is to design a system combining BMI, FES and realistic visual feedback, and test its feasibility as a therapeutic tool for hand rehabilitation of iSCI patients. A system integrating a BMI with FES and visual realistic feedback was developed as a neurorehabilitation tool. Movement-related cortical potentials and event-related desynchronization were used as features and a sparse discriminant analysis (SDA) to classify between rest and motor attempt. Four patients with iSCI performed five therapy sessions with that system in one of their hands only. Initial and final clinical assessments were fulfilled, as well as usability and exertion tests. The system showed a high accuracy, with an average success of 79.13% in rewarding the patients according to their brain activity. There were higher improvements of their prehension in the stimulated hand than in the non-stimulated. All patients reported that they would like to use this application in therapy and they felt very motivated. Our results suggest the feasibility of this integration of technologies to be considered as a therapeutic tool for upper limb rehabilitation. The results, despite being preliminary, provide promising insights for the use of BMI rehabilitation in incomplete SCI patients.