Electro-Neuromodulation for Colonic Disorders-Review of Meta-Analyses, Systematic Reviews, and RCTs.

BACKGROUND: In the last 20 years, studies have shown that large bowel function can be modified by neural stimulation. While still in its infancy, this area of research is beginning to show promise. METHODS: This overview brings together systematic reviews and meta-analyses of electrical stimulation used to treat colonic disorders (fecal incontinence, constipation, slow transit constipation [STC], irritable bowel syndrome [IBS-C], and spina bifida-neurogenic bowel). Different methods of electrical stimulation including through sacral nerves, paraspinal, transabdominal, and using electroacupuncture over the ankle or knee and direct stimulation of the bowel are reviewed. RESULTS AND DISCUSSION: Most evidence is low level (pilot and small cohort studies) but with more RCTs appearing. Sacral nerve stimulation (SNS) does improve urinary dysfunction and fecal incontinence but not constipation. It is expensive with high rates of reoperation. Transcutaneous stimulation with interferential current (IFC, alternating current at KHz frequency with 2 channels out of phase) does improve constipation and may provide benefit as an adjuvant to behavioral or exercise therapies. Acupuncture and electro-acupuncture (low/very low-level evidence) may have a benefit for constipation. CONCLUSION: SNS is effective but expensive and limited to extreme patients. Transcutaneous stimulation is noninvasive and cheap and IFC may be effective for constipation, but many parameters need to be optimized and higher level evidence provided from studies (sham, blinding, and larger patient numbers). The next 20 years should be exciting in the field as higher level studies are performed.