Preservation of the colo‐anal reflex in colonic transection and post‐operative Hirschsprung's disease: Potential extrinsic neural pathway

Abstract

Background The colo‐anal reflex is a distinct reflex whereby the internal anal sphincter (IAS) relaxes in association with colonic high amplitude propagating contractions (HAPCs) in contrast to the recto‐anal inhibitory reflex (RAIR), which is characterized by IAS relaxation upon rectal distension. The RAIR is mediated by the myenteric plexus and therefore absent in Hirschsprung disease. We retrospectively assessed the presence and the characteristics of the colo‐anal reflex in children in whom large bowel continuity had been surgically disrupted to assess the role of the extrinsic nervous system in the reflex. Methods High‐resolution (HR) colonic manometry and HR‐anorectal manometry were used to evaluate both colonic and anal motor activity in ten children with treatment‐unresponsive slow transit constipation (STC), who had previously undergone left‐sided colostomy formation with consequent disruption of the bowel continuity, and in two children with Hirschsprung's disease (HSCR), who had previously undergone distal colon resection followed by Duhamel pull‐through. Eight children with STC, normal colonic motor activity, and preserved large bowel continuity served as a control group. The presence and characteristics of colo‐anal reflex were analyzed. Key Results In the study group, all patients showed the presence of both normal HAPCs and the presence of the colo‐anal reflex. In two cases of HSCR, RAIR was absent; however, both patients demonstrated a colo‐anal reflex. Conclusions In children with disrupted continuity of the colon and/or abnormal anal reflex, the colo‐anal reflex is still preserved suggesting that it is mediated by a different pathway from the RAIR, possibly an extrinsic neural pathway.

Intraluminal Prucalopride Increases Propulsive Motor Activities in the Human Colon

“…The propagating motor patterns in the present study induced by prucalopride show a close temporal association with anal sphincter relaxation indicative of the colo-anal reflex, an independent neurally-controlled reflex involving autonomic sacral neural pathways (29, 30) (46) (43) (35) (37). The relaxation was often complete unlike the recto-anal inhibitory reflex (RAIR) which is characterized by a transient involuntary relaxation of the internal anal sphincter in response to rectal balloon distension.…”

On the nature of high-amplitude propagating pressure waves in the human colon

“…HAPWs are associated with anal sphincter relaxation, defined as the colo-anal reflex (19,34,48,49,52). Here, we show that this relaxation occurred with all categories of HAPW and was, on average, 66% of its baseline anal pressure.…”

“…The RAIR only involves enteric nitrergic relaxation of the internal anal sphincter (42,48), and usually 24 mmHg of resting pressure remains during balloon distention (47). Consistently, in children with disrupted continuity of the colon, which abolishes RAIR, the colo᎑anal reflex was preserved, indicating that it is mediated by a different pathway from the RAIR, likely an extrinsic neural pathway (49). In dogs, anal relaxation upon proximal colon distention was mediated by sympathetic nerves (16).…”

High-resolution colonic manometry and its clinical application in patients with colonic dysmotility: A review

“…After the excision of the abnormal intestinal segment in the treatment of Hirschsprung disease, a large proportion of patients still experience abnormal defecation patterns. Colonic manometry can stratify patients with Hirschsprung disease requiring surgical treatment into four groups with different physiological characteristics[60-62]. The first group includes patients with HAPCs, in whom the HAPCs can pass through the rectum to the anal margin, but the amplitude of HAPCs is greater than the voluntary contraction of the external anal sphincter.…”