Brain-Controlled Epidural Spinal Stimulation for Upper-Limb Motor Function after Tetraplegia

Spinal cord injury (SCI) disrupts descending motor pathways, leaving individuals with tetraplegia dependent on residual neural connections to generate voluntary movement, with limited recovery despite extensive rehabilitation. Epidural spinal cord stimulation (ESCS) has emerged as a promising neuromodulation strategy that can amplify spinal sensorimotor pathways, enabling residual circuits to respond more effectively to attempted voluntary commands. However, most approaches deliver stimulation continuously rather than in response to volitional intent, limiting the integration of cortical commands and spinal activation that may enhance both neuroprosthetic utility and the potential for recovery. Here, we present an implantable brain-computer interface (BCI) that decodes attempted movement from electrocorticography signals to trigger cervical ESCS during upper-limb motor tasks in an individual with chronic, motor-complete cervical SCI. We demonstrated that both BCI-driven and tonic ESCS immediately enhanced motor function compared to no stimulation, with BCI-ESCS producing greater improvements in grip force and reaching accuracy. Parallel to these assistive effects, BCI-ESCS facilitated corticospinal and spinal excitability after a single session, whereas tonic stimulation did not, suggesting the utility of BCI-driven neuromodulation for activity-dependent plasticity. Four weeks of BCI-ESCS use further drove meaningful improvements in hand motor function exceeding clinical improvement thresholds, with selected gains persisting at one-month follow-up. Together, these findings establish a translational proof-of-concept for an implantable BCI-ESCS, demonstrating the feasibility of intent-driven neuromodulation as a restorative strategy that provides both neuroprosthetic assistance and therapeutic benefit following chronic complete tetraplegia.