Internal anal sphincter relaxation associated with bisacodyl‐induced colonic high amplitude propagating contractions in children with constipation: a colo‐anal reflex?

Abstract

Objectives Describe the association of internal anal sphincter (IAS) relaxation with colonic high amplitude peristaltic contractions (HAPCs). Methods Retrospective review of colon manometry tracings of children with constipation to determine the IAS relaxation characteristics associated to HAPC’s (HAPC-IASR) events and compare them to the those seen during the performance of the anorectal manometry (ARM-RAIR) events. Results A total of 70 HAPC- IASRs were observed in 15 patients, 65 after bisacodyl, 2 during fasting and 3 after a meal. In 64% of events the IAS relaxation started when the HAPC reached left colon and in 36% as proximal as the hepatic flexure. HAPC propagation seems to be important in HAPC-IASR characteristics; those propagating distal to sigmoid colon demonstrated larger and longer IAS relaxation as well as lower residual pressure but equivalent resting pressure compared to HAPC’s ending proximal to sigmoid colon. While IAS resting pressure was comparable for ARM-RAIRs and HAPC-IASRs, the duration and magnitude of anal relaxation was higher and the anal residual pressure was lower in HAPC-IASRs. Conclusions We demonstrated that IAS relaxation in constipated children is associated with HAPCs migrating in the proximal and distal colon; in most cases starting when peristalsis is migrating through left colon and in an important proportion while migrating proximally. We also demonstrated that HAPC-IASRs are different from ARM-RAIRs suggesting a neurally mediated reflex. Lastly, the IAS relaxation characteristics are highly dependent on the degree of propagation of HAPCs, which could have important implications in the understanding of defecation disorders.

High amplitude propagated contractions

“…The relationship between HAPC and mass movements was verified by simultaneously assessing pan colonic isotope movement and pressure changes in 2000 5 . Over 100 years after the report by Holznecht, Rodriguez and colleagues now use the same approach (i.e., meticulous observation) to refine our understanding of the temporal relationship between HAPC and internal anal sphincter relaxation in children with chronic constipation 6 . These intriguing observations provide an opportunity to summarize our current understanding of HAPC in health and disease.…”

“…In addition to occurring spontaneously, HAPC can be induced by pharmacological agents, which are perhaps more potent stimuli than colonic distention in adults 15 and children 16 . Similar to lower esophageal sphincter relaxation at the onset of esophageal peristalsis, anal relaxation precedes the arrival of HAPC in the rectosigmoid colon 6,17–19 . While the lower esophageal sphincter relaxes due to a ‘flood’ of inhibition originating from the dorsal motor nucleus of the vagus, activation of intra‐colonic descending inhibitory pathways probably explains early anal relaxation (i.e., before HAPC arrive at the rectosigmoid colon) 20,21 .…”

An ANMS‐NASPGHAN consensus document on anorectal and colonic manometry in children

“…Both the postprandial response to a meal and the presence of HAPCs have been associated with preservation of the enteric nervous system and correlate with colonic fecal movement by cine‐MRI . A recent report highlighted the association between bisacodyl‐induced HAPC and anal canal relaxation (a “colo‐anal reflex”), with most contractions resulting in anal canal relaxation as HAPC reach the splenic flexure . After any type of colonic transection, CM has demonstrated that there is an increase in the number of HAPCs, probably due to the loss of a negative recto‐colonic feedback, with a higher frequency of propagated contractions occurring in those patients operated for Hirschsprung's disease compared to those undergoing surgery for other indications …”

Prospective evaluation of same day versus next day colon manometry results in children with medical refractory constipation

“…Colon manometry (CM) has been proven to be a useful tool in the evaluation and treatment of children with defecation disorders . CM has been instrumental in the identification of previously unrecognized normal physiologic patterns, including the association between the internal anal sphincter relaxation and the onset of proximal to distal colon contraction migration . In post‐surgical patients CM has not only helped to clarify the pathophysiology of recurrent symptoms, but has also been proven to predict therapeutic outcomes in patients treated with antegrade colonic enemas via cecostomy …”