A Comprehensive Narrative Review on Autonomic Nervous System Pathophysiology in Spinal Cord Injury and the Use of Invasive and Non-Invasive Electrical Stimulation for Recovery

Spinal cord injury (SCI) significantly reduces both quality of life and life expectancy due to the loss of motor and sensory function, as well as its impact on autonomic dysfunction (AD). Complications related to AD include impaired sphincter control and thermoregulation, orthostatic hypotension, respiratory difficulties, sexual dysfunction, and gastrointestinal complications, among others. These complications limit physical rehabilitation capacities, exacerbating SCI-related challenges and increasing healthcare costs. Currently, no effective clinical treatments exist to restore impaired autonomic neural control. However, invasive and non-invasive neuromodulation strategies such as epidural spinal cord stimulation (eSCS) and transcutaneous spinal cord stimulation (tSCS), respectively, have demonstrated promising results in improving autonomic function. Despite these advances, drawing definitive conclusions remains challenging because studies vary in sample size, stimulation parameters, session numbers, and assessment methods. This narrative review outlines the primary consequences of SCI on the autonomic nervous system (ANS) and evaluates the effects of eSCS and tSCS on cardiovascular, respiratory, gastrointestinal, sphincter control, thermoregulation, and sexual function, while highlighting the diversity of approaches in current studies.