Background Functional recovery of independent arm movement typically plateaus within six months following a stroke, leaving chronic motor deficits. This feasibility study tested whether a wearable, powered exoskeletal orthosis, driven by a percutaneous, implanted brain–computer interface (BCI), using the activity of neurons in the precentral gyrus in the affected cortical hemisphere, could restore voluntary upper extremity function in a person with chronic hemiparetic subsequent to a cerebral hemispheric stroke of subcortical gray and white matter and cortical gray matter.
Methods One person with chronic hemiparetic stroke with upper-limb motor impairment used a powered elbow-wrist-hand orthosis that opened and closed the affected hand using cortical activity, recorded from four 64-channel microelectrode arrays implanted in the ipsilesional precentral gyrus, based on decoding of spiking patterns and high frequency field potentials generated by imagined hand movements using technology and decoding methods used for people with other causes of paralysis. The system was evaluated in a home setting daily for 12 weeks.
Results Robust single unit activity, modulating with attempted or imagined movement, was present throughout the precentral gyrus areas. The participant was able to acquire voluntary control over a hand-orthosis BCI, with a score of 10 points on the Action Research Arm Test (out of 53) using the BCI, compared to 0 without any device, and 5 using myoelectric control. Orthosis-powered hand-opening was faster with BCI control compared to myoelectric control, on a standardized object-movement task.
Conclusions The findings demonstrate the therapeutic potential of an implantable BCI system coupled to a brace to “electrically bypass” the stroke and promote neurally driven limb function. The participant’s ability to rapidly acquire voluntary control over otherwise paralyzed hand opening, more than 18 months after a subcortical stroke, lays the foundation for a fully implanted movement restoration system.