Background and aims: The 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.
Methods: A 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.
Results: Fifteen 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.
Conclusion: The rectosigmoid brake was suppressed in this cohort of patients with faecal incontinence. SNM may exert a therapeutic effect by modulating this rectosigmoid brake.
Faecal incontinence is associated with an impaired rectosigmoid brake and improved by sacral neuromodulation