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

Abstract

Background The rectosigmoid brake, characterised 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 fibreoptic 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‐ 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 post meal increase in propagating contractions (mean 17 ± 6/h premeal 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 premeal vs. 14 ± 3/h premeal 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.

The role of colonic motility in low anterior resection syndrome

“…Rectosigmoid dysmotility may be associated with disrupted continence. In a recent HRCM study, a suppressed rectosigmoid brake (i.e., fewer retrograde propagating contractions in the distal colon) was observed in patients with medicallyrefractory faecal incontinence compared to healthy controls (41). While this study was in participants with a native rectum, it is conceivable that a similar attenuation of the rectosigmoid brake may contribute to incontinence and soiling in LARS (41).…”

“…In a recent HRCM study, a suppressed rectosigmoid brake (i.e., fewer retrograde propagating contractions in the distal colon) was observed in patients with medicallyrefractory faecal incontinence compared to healthy controls (41). While this study was in participants with a native rectum, it is conceivable that a similar attenuation of the rectosigmoid brake may contribute to incontinence and soiling in LARS (41). Numerous studies have demonstrated that sacral neuromodulation (SNM), an established and highly successful treatment for faecal incontinence, upregulates retrograde motility of the sigmoid colon, restoring rectosigmoid brake function (41,65,66).…”

“…While this study was in participants with a native rectum, it is conceivable that a similar attenuation of the rectosigmoid brake may contribute to incontinence and soiling in LARS (41). Numerous studies have demonstrated that sacral neuromodulation (SNM), an established and highly successful treatment for faecal incontinence, upregulates retrograde motility of the sigmoid colon, restoring rectosigmoid brake function (41,65,66). Successful application of SNM to relieve symptoms in patients with LARS could also function through this mechanism, by upregulating propagating sequences with a braking function in the remnant colon or neorectum (67).…”

“…External anal sphincter (EAS) and pelvic floor muscle tone then contribute to the maintenance of continence. The role of the cyclic motor pattern has been reviewed previously (40), but in brief: the cyclic motor pattern originates throughout the distal colon, most frequently at the rectosigmoid junction, and predominantly propagating in the retrograde direction after meals, thereby preventing rectal filling and aiding in bowel continence (40)(41)(42). Voluntary passage of flatus and anorectal differentiation of gaseous, liquid, and solid contents; important functions for the voluntary control of defecation, are mediated through the recto-anal inhibitory reflex whereby rectal distension causes transient internal sphincter relaxation before recovery of anal pressures (43).…”

“…The importance of neural innervation in regulating rectosigmoid motor activity is evidenced by its relative absence in spinal cord injury (59,60), systemic sclerosis (61), and diabetes mellitus (62). Similarly, as stimulation of the pelvic splanchnic nerves through sacral neuromodulation (SNM) can be highly efficacious even in cases of anal sphincter incompetence (63,64), it has also been posited that neurally-mediated colonic motility pathways are a primary mechanism for regulating continence via SNM (41,65).…”