What is the role of sacral nerve stimulation (SNS) in treating severe, treatment-resistant constipation?

Sacral Nerve Stimulation for Constipation: Limited Evidence for Efficacy

Based on current evidence, sacral nerve stimulation (SNS) should not be used for managing constipation in clinical practice due to limited efficacy and insufficient supporting data. 1

Current Recommendations for Constipation Management

Constipation management should follow a stepwise approach:

1. First-line: Conservative measures

   • Dietary modifications (increased fiber)
   • Adequate fluid intake
   • Regular physical activity
   • Bowel training programs
   • Medications (laxatives, stool softeners)

2. Second-line: Biofeedback therapy

   • Biofeedback therapy is the treatment of choice for defecatory disorders 1
   • Particularly effective for dyssynergic defecation

3. Third-line: Consider structural abnormalities

   • Evaluate for pelvic floor structural abnormalities
   • Consider appropriate surgical management for significant rectoceles or enteroceles

Evidence Against SNS for Constipation

The Clinical Gastroenterology and Hepatology guidelines explicitly state that "sacral nerve stimulation should not be used for managing defecatory disorders in clinical practice" (Best practice advice 13) 1. This recommendation is based on:

• A prospective, 18-week randomized, double-blind, placebo-controlled crossover study showing that neither sub- nor supra-sensory SNS increased the proportion of complete bowel movements compared to sham SNS in patients with medically-refractory slow transit constipation 1

• Limited long-term efficacy data in larger studies

• An intention-to-treat analysis showing only 29.2% of patients had a successful outcome at median follow-up of 25.6 months 2

Limited Positive Evidence for SNS in Constipation

Some smaller studies have shown modest benefits:

• In a study of 19 patients with severe constipation, 8 patients (42%) reported improvement during test stimulation and received permanent implants, with significant improvement in Wexner constipation scores 3

• Another small study of 4 women with idiopathic constipation showed marked improvement in 3 patients with permanent stimulation, including increased bowel frequency and improved quality of life 4

• A review of literature found that in patients who proceeded to permanent SNS, up to 87% showed improvement in symptoms at median follow-up of 28 months 5

SNS for Fecal Incontinence: A Different Story

It's important to distinguish between constipation and fecal incontinence, as SNS has demonstrated efficacy for fecal incontinence:

• SNS is recommended for moderate to severe fecal incontinence that has failed conservative measures and biofeedback therapy 1, 6

• In the pivotal US multicenter trial for fecal incontinence, 90% of patients proceeded from temporary to permanent stimulation, and among those with 5-year follow-up data, 36% reported complete continence 1

• SNS has demonstrated significantly better outcomes than medical treatment for fecal incontinence 1

Common Pitfalls to Avoid

1. Premature progression to surgical interventions before adequate trials of conservative therapy and biofeedback 1, 6

2. Confusing indications - using SNS for constipation when evidence supports its use primarily for fecal incontinence

3. Failure to identify and treat underlying causes of constipation 6

4. Not addressing anatomic defects that may contribute to constipation 1, 6

Conclusion

For severe, treatment-resistant constipation, current evidence does not support the routine use of sacral nerve stimulation. Biofeedback therapy remains the treatment of choice for defecatory disorders, and other options should be explored before considering SNS. The disparity between small positive studies and larger controlled trials suggests that patient selection may be critical if SNS is to be considered in exceptional cases.