Research progress on the effects of epidural electrical stimulation on lower extremity function in patients with spinal cord injury

Lower extremity motor dysfunction after spinal cord injury (SCI) represents a major determinant of long-term disability and reduced quality of life. Although conventional pharmacotherapy and rehabilitation training may partially attenuate secondary injury and preserve residual function, their capacity to restore motor networks below the level of injury remains limited. In recent years, epidural electrical stimulation (EES), through targeted modulation of lumbosacral dorsal root afferents and local interneuronal circuits, has been shown to increase the excitability of spinal motor networks and augment residual descending input. Moreover, when integrated with task-specific training, EES has been associated with improvements in lower extremity motor functions, including standing, stepping, walking, and spasticity control. This study narratively reviews the pathophysiological basis of SCI, the neural mechanisms underlying EES, its clinical efficacy, combined therapeutic approaches, individualized parameter optimization, and current limitations. Available evidence, though currently limited by small sample sizes and study heterogeneity, indicates that EES may promote functional recovery in patients with chronic incomplete SCI and in a subset of those clinically classified as having "motor-complete" SCI; however, its therapeutic benefit is influenced by the complex interaction of multiple factors, including the integrity of spared pathways, the level of injury, stimulation parameters, electrode configuration, and rehabilitation intensity. Further progress is required, particularly in multicenter randomized controlled trials, standardized outcome assessments, closed-loop programming, and long-term safety evaluation, to support the translation of EES from an investigational neuromodulation strategy into a broadly applicable, precision-oriented rehabilitation modality.