Reclaiming Hand Functions after Complete Spinal Cord Injury with Epidural Brain-Computer Interface

Abstract Background Spinal cord injuries significantly impair patients’ ability to perform daily activities independently. While cortically implanted brain-computer interfaces (BCIs) offer high communication bandwidth to assist and rehabilitate these patients, their invasiveness and long-term stability limit broader adoption. Methods We developed a minimally invasive BCI with 8 chronic epidural electrodes above primary sensorimotor cortex to restore hand functions of tetraplegia patients. With wireless powering and neural data transmission, this system enables real-time BCI control of hand movements and hand function rehabilitation in home use. A complete spinal cord injury (SCI) patient with paralyzed hand functions was recruited in this study. Results Over a 9-month period of home use, the patient achieved an average grasping detection F1-score of 0.91, and a 100% success rate in object transfer tests, with this minimally invasive BCI and a wearable exoskeleton hand. This system allowed the patient to perform eating, drinking and other daily tasks involving hand functions. Additionally, the patient showed substantial neurological recovery through consecutive BCI training, regaining the ability to hold objects without BCI. The patient exhibited a 5-point improvement in upper limb motor scores and a 27-point increase in the action research arm test (ARAT). A maximal increase of 12.7 μV was observed in the peak of somatosensory evoked potential (SEP), which points to a considerable recovery in impaired spinal cord connections. Moreover, a high-frequency component (200-300 Hz) in SEP that was initially undetectable gradually emerged and became significant, indicating notable reorganization of the underlying neural circuits. Conclusions In a tetraplegia patient with complete spinal cord injury, an epidural minimally invasive BCI assisted the patient’s hand grasping to perform daily tasks, and 9-month consecutive BCI use significantly improved the hand functions.