Sacral Nerve Neuromodulation for the Treatment of Lower Bowel Motility Disorders

Abstract

INTRODUCTION Incontinence and constipation are common and cause a high degree of physical, social and psychological impairment. Maximal conservative therapy may improve some patients but many remain symptomatic. Surgical options are often unsatisfactory, with variable result and further options are limited. Sacral nerve stimulation uses electrical stimulation applied to the sacral nerves, eliciting a physiological effect on the lower bowel, anal sphincter and pelvic floor, resulting in clinical benefit. The objective of this study was to investigate whether sacral nerve neuromodulation can improve patients with disorders of bowel motility, when current maximal treatment has failed and to investigate the underlying physiological mechanism of action. RESULTSIncontinence: Nineteen patients, age 58 years (range, 37-71 years), with resistant incontinence for 6 years (range, 2-21 years) underwent stimulation. Continence improved in all at 24 months (range, 3-60 months), fourteen fully continent. Incontinent episodes decreased; 12 (range, 2-30) versus 0 (range, 0-4), P < 0.001. Urgency ( P < 0.01) and quality of life improved ( P < 0.05). Anal squeeze pressure ( P = 0.001) and rectal sensation ( P < 0.01) improved.Constipation: Four women, (aged 27-36 years) with resistant idiopathic constipation for 8-32 years underwent the first worldwide implants. Symptoms improved in all with temporary, and in three with permanent, stimulation at 8 months (range, 1-11 months). Bowel frequency increased: 1-5 versus 6-28 evacuations/3-weeks. Symptom scores and quality of life improved.Placebo effect: A double-blind, cross-over study was performed to examine placebo effect and efficacy. Once stimulation was removed, in a blinded manner, symptoms, physiological parameters and quality of life measures rapidly returned to baseline levels.Autonomic neuromodulation: Sixteen patients, median age 59 years (range, 38-71 years), were studied at 27 months (range, 2-62 years) using laser Doppler flowmetry. Chronic stimulation was at 2.8 V (range, 0.3-3.9 V). Median flux differed between none and chronic stimulation (P = 0.001).Step-wise increments caused an immediate, dose-dependent rise in flux ( P < 0.0001) up to 1.0 V. CONCLUSIONS This research provides strong evidence that sacral nerve stimulation can improve patients with resistant incontinence and shows proof-of-concept for the treatment of constipation. The effect is unlikely to be due to placebo and the mechanism is rapidly reversible and involves a dose-dependent effect on the autonomic nerves.

Sacral Nerve Neuromodulation Is Effective Treatment for Fecal Incontinence in the Presence of a Sphincter Defect, Pudendal Neuropathy, or Previous Sphincter Repair

“…This modulation of afferent and autonomic pathways may also explain why SNS may be effective for slow transit constipation and rectal urgency. 11 PNTML is often measured in patients with fecal incontinence. It is a controversial measure, and a pudendal nerve trace can be difficult to elicit, even in patients without fecal incontinence, and it has a high interobserver variation.…”

Secondary changes in bowel function after successful treatment of voiding symptoms with neuromodulation

“…Improvements in comorbid pelvic pain and bowel symptoms 1,2 after sacral and more recently, chronic pudendal neuromodulation for voiding complaints 3,4 have already been observed. Studies have also reported encouraging results after treating fecal incontinence (FI), 5 constipation, 6,7 irritable bowel syndrome (IBS), 8 and anorectal pain 9 with neuromodulation.…”

Sacral nerve stimulation for fecal incontinence

“…The precise pathophysiological mechanism why the procedure is effective is unknown, and this may be seen in the medical literature for a variety of anorectal manometry values, both pre-and post-operatively, where various irreproducible effects are described for all series: increased maximum tolerated volume, increased volume at which sensation takes place, and increased sphincter resting pressure (18)(19)(20)(21). In our study, following the procedure we saw that voluntary contraction pressure improved in a statistically significant manner.…”