Vagal Nerve Stimulation for Chronic Constipation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

In 30 seconds

This systematic review and random-effects meta-analysis of six randomized controlled trials assessed transcutaneous auricular vagus nerve stimulation and transcutaneous electroacupuncture for chronic constipation. Across 356 participants, vagal nerve stimulation was associated with improvements in pain, stool form, bowel movement frequency, and irritable bowel syndrome symptom severity. The largest reported bowel-frequency result was an increase of 1.75 weekly spontaneous bowel movements (mean difference 1.75; 95% CI 0.93-2.58; p < 0.0001). Anxiety, depression, and anorectal function did not differ significantly between groups.

Key findings

• Weekly spontaneous bowel movements increased by a mean difference of 1.75 (95% CI 0.93-2.58; p < 0.0001).
• Weekly complete spontaneous bowel movements increased (MD 1.10 [95% CI 0.40-1.80], p = 0.002).
• Pain scores improved (MD -1.76 [95% CI -2.92 to -0.60], p = 0.003), as did Bristol stool form scores (MD 0.99 [95% CI 0.30-1.68], p = 0.005).
• No significant between-group differences were found for anxiety, depression, or anorectal function.

Why it matters

Chronic constipation can substantially affect quality of life, and this synthesis suggests vagal nerve-based neuromodulation may improve bowel frequency and related symptoms. The findings provide a quantitative overview of outcomes from randomized trials, while the absence of significant effects on psychological measures and anorectal function indicates that benefits were not demonstrated across all assessed domains.

What to keep in mind

The evidence base comprised only six trials and 356 participants; the abstract does not report follow-up duration or provide details on variation among trial protocols.