Faecal incontinence is associated with an impaired rectosigmoid brake and improved by sacral neuromodulation

Abstract

AbstractBackground and aimsThe rectosigmoid brake, characterized by retrograde cyclic motor patterns on high-resolution colonic manometry has been postulated as a contributor to the maintenance of bowel continence. Sacral neuromodulation (SNM) is an effective therapy for faecal incontinence, but its mechanism of action is unclear. This study aims to investigate the colonic motility patterns in the distal colon of patients with faecal incontinence, and how these are modulated by SNM.MethodsA high-resolution fibre-optic colonic manometry catheter, containing 36 sensors spaced at 1-cm intervals, was positioned in patients with faecal incontinence undergoing Stage 1 SNM. One hour of pre-meal and post-meal recordings were obtained followed by pre- and post-meal recordings with suprasensory SNM. A 700-kcal meal was given. Data were analysed to identify propagating contractions.ResultsFifteen patients with faecal incontinence were analysed. Patients had an abnormal meal response (fewer retrograde propagating contractions compared to controls; p=0.027) and failed to show a postmeal increase in propagating contractions (mean 17 ± 6/h pre-meal vs 22 ± 9/h post-meal, p = 0.438). Compared to baseline, SNM significantly increased the number of retrograde propagating contractions in the distal colon (8 ± 3/h pre-meal vs 14 ± 3/h pre-meal with SNM, p = 0.028). Consuming a meal did not further increase the number of propagating contractions beyond the baseline upregulating effect of SNM.ConclusionThe rectosigmoid brake was suppressed in this cohort of patients with faecal incontinence. SNM may exert a therapeutic effect by modulating this rectosigmoid brake.What You Need to KnowBackground and contextThe rectosigmoid brake, characterized by retrograde propagating motility patterns, has been postulated to contribute to the maintenance of continence. The mechanisms of action of sacral neuromodulation remain inadequately understood and may include modulation of the rectosigmoid brake.New findingsWe found that patients with faecal incontinence had an impaired rectosigmoid brake, characterized by a reduced frequency of colonic motor patterns in response to a meal. Rectosigmoid brake activity was upregulated by sacral neuromodulation.LimitationsThis was a small cohort of patients with heterogenous faecal incontinence subtypes.ImpactAttenuation of the rectosigmoid brake is a biomarker of faecal incontinence. Rectosigmoid brake responses offer a therapeutic target to evaluate and refine sacral neuromodulation protocols.Lay summaryPatients with faecal incontinence had an attenuated rectosigmoid brake, characterised by fewer postprandial retrograde propagating contractions in the distal colon, however, the rectosigmoid brake function was improved by sacral neuromodulation.