Non-invasive neuromodulation for bowel, bladder and sexual restoration following spinal cord injury: A systematic review

Bowel, bladder and sexual dysfunctions are widespread among people with spinal cord injury (SCI) and significantly impact their health and quality of life. Any non-invasive intervention which offers clinical benefits and safety is an advantage in restoring these functions. Despite the potential of non-invasive neuromodulation to improve the clinical outcomes in people with SCI, its characteristics are poorly defined, and reviews of efficacy are scarce in the literature. This study aimed to perform a systematic literature review of clinical studies investigating the use of non-invasive neuromodulation in restoring bowel, bladder and sexual functions following SCI. Electronic databases were searched, including the PubMed/Medline, EMBASE, Web of Science, Scopus and Cochrane databases, along with the reference lists of retrieved publications. Studies were eligible for inclusion if they adopted a clinical design based on participants with SCI, had main outcomes of restoration of bowel, bladder or sexual function and the intervention investigated was non-invasive neuromodulation. A total of 46 studies (combined sample of 1,801) were included in this systematic review, comprising studies of transcutaneous electrical nerve stimulation, magnetic stimulation and vibratory stimulation. Of the 46 studies, 7 were randomized controlled trials (RCTs), 36 were non-RCTs and 3 were case reports. Most studies (43/46) reported improvements in bowel (5/5), bladder (32/35) and sexual (6/6) dysfunction after SCI. However, the quality of the included studies was variable and associated with a high risk of bias. Thus, well-designed, blinded and sham-controlled RCTs with larger populations are required to establish clinical efficacy of these methods.