Spinal cord injuries (SCI) are a devastating reality for millions worldwide, with the number of cases rising annually. Beyond the immediate paralysis, patients face a host of challenges, including muscle wasting, stiffness, abnormal bone growth, and issues with their body's automatic functions, all severely impacting their quality of life. Current treatments primarily focus on rehabilitation, with medications, physical therapies, and surgeries offering little hope for reversing neural damage. However, a new approach called epidural electrical stimulation (EES) has emerged as a potential game-changer in neurorehabilitation.
Previous studies on animals and humans suggest that EES, delivered through electrodes implanted in the epidural space, can activate neural circuits below the injury site and increase network excitability. This stimulation can potentially trigger standing and walking patterns and promote the recovery of sensory and motor functions. But here's where it gets controversial: while EES shows promise, its effectiveness for people with incomplete SCI is still up for debate. The evidence is limited due to small sample sizes, uncertain long-term outcomes, and a focus primarily on motor function, making it difficult to separate the effects of concurrent physical therapy (PT).
Yihang Ren, a researcher at Beijing Tiantan Hospital, Capital Medical University, recognized this gap and proposed a larger, controlled study to evaluate the combined effects of EES and PT on multiple outcome domains, including sensation, muscle strength, spasticity, and autonomic function, in individuals with incomplete SCI. The study, conducted at Beijing Tiantan Hospital from October 2020 to April 2024, was approved by the institutional ethics committee and involved written informed consent from all participants.
Eligible adults with incomplete spinal cord injury (ASIA grade ≥B), an injury level above L1–L2, and at least six months post-injury were included. Demographic, clinical, and radiological baselines were obtained preoperatively. Patients self-selected into two groups: an intervention arm (EES + PT) and a comparison arm (PT only). All patients received standardized physical therapy, and the intervention arm underwent surgery to implant a thoracolumbar epidural electrode and a temporary stimulator. If a favorable response with no adverse effects was confirmed after 7–10 days, an implantable stimulator was placed. Stimulation protocols were tailored to ensure coverage of major lower-limb muscle groups.
Outcomes were assessed at three time points: baseline, within 14 days post-EES surgery, and at 19–25 months. The assessments included ASIA sensory and motor scores, spasticity scales, urinary and bowel function composites, and visual-analog pain ratings. The results showed that the EES + PT group experienced significant improvements in sensation and muscle spasticity within 14 days post-surgery, while changes in strength, urinary and bowel function, and pain were not significant at the group level. However, individual improvements were noted, with some patients reporting lower pain scores and increased lower-limb strength.
Over the long-term follow-up period of 19–25 months, the EES + PT group continued to show significant gains in sensation, spasticity, and urinary control. All patients in this group improved in sensation and spasticity, with some also showing improvements in strength, bowel function, and pain. When compared to the PT-only group, the EES + PT group demonstrated superior results in sensory function, strength, spasticity, and urinary control. While bowel outcomes showed a higher recovery rate with EES + PT, it did not reach statistical significance.
Importantly, no electrode-related infections or displacements were reported among the implanted patients during the follow-up period.
This study provides comprehensive insights into the combined effects of EES and PT on sensory, motor, and autonomic functions in SCI patients. The results indicate that EES, when combined with PT, significantly enhances long-term sensory function, muscle strength, spasticity, and urinary function compared to PT alone. Additionally, the combined treatment improved bladder control and pain relief for some patients.
Looking ahead, Yihang Ren and the research team plan to conduct further single-center studies to control the content and intensity of rehabilitation. They aim to evaluate the long-term sustainability of rehabilitation by extending the follow-up period. Incorporating objective sensory measurements, such as electrophysiological assessments, and exploring neuroplasticity mechanisms will deepen our understanding. Controlling for confounding factors like age and comorbidities and comparing EES + PT with other interventions will validate its efficacy. Finally, they plan to customize treatment plans to meet individual patient needs, maximizing the effectiveness of this innovative approach.
The paper, titled "Epidural Electrical Stimulation for Functional Recovery in Incomplete Spinal Cord Injury," was published in the journal Cyborg and Bionic Systems on July 22, 2025. The research was supported by various grants and foundations, including the National Natural Science Foundation of China and the Project of Sanya Yazhou Bay Science and Technology City.
This groundbreaking study offers hope and a potential new path forward for individuals living with incomplete spinal cord injuries.
