The “rectosigmoid brake”: Review of an emerging neuromodulation target for colorectal functional disorders

Abstract

SummaryThe regulation of gastrointestinal motility encompasses several overlapping mechanisms including highly regulated and coordinated neurohormonal circuits. Various feedback mechanisms or "brakes" have been proposed. While duodenal, jejunal, and ileal brakes are well described, a putative distal colonic brake is less well defined.Despite the high prevalence of colonic motility disorders, there is little knowledge of colonic motility owing to difficulties with organ access and technical difficulties in recording detailed motor patterns along its entire length. The motility of the colon is not under voluntary control. A wide range of motor patterns is seen, with long intervals of intestinal quiescence between them. In addition, the use of traditional manometric catheters to record contractile activity of the colon has been limited by the low number of widely spaced sensors, which has resulted in the misinterpretation of colonic motor patterns. The recent advent of high-resolution (HR) manometry is revolutionising the understanding of gastrointestinal motor patterns. It has now been observed that the most common motor patterns in the colon are repetitive two to six cycles per minute (cpm) propagating events in the distal colon. These motor patterns are prominent soon after a meal, originate most frequently in the rectosigmoid region, and travel in the retrograde direction. The distal prominence and the origin of these motor patterns raise the possibility of them serving as a braking mechanism, or the "rectosigmoid brake," to limit rectal filling. This review aims to describe what is known about the "rectosigmoid brake," including its physiological and clinical significance and potential therapeutic applications. K E Y W O R D Scolon, gastrointestinal motility, gastrointestinal tract, high-resolution manometry, rectosigmoid brake | INTRODUCTIONColonic motility disorders are prevalent in the general population and can have a significant impact on quality of life.1-3 Gastrointestinal transit and the act of defaecation require a coordinated interplay between intrinsic neurohormonal circuits acting on a morphologically intact gastrointestinal tract. These are highly auto-regulated and coordinated events, optimised for ideal transit, maximum absorption, and timely elimination of waste products.Networks of gastrointestinal "brakes" have long been proposed to provide negative feedback controls on gastrointestinal motility. 4-12Duodenal and jejunal brakes are recognised responses to the arrival of nutrient-dense chyme into the upper small intestine, triggering neurohormonal circuits that impart feedback control on gastric emptying, gastric distention and satiety. 6,8 Distally, the ileal brake is capable of a potent inhibition of intestinal motility following the arrival of nutrients, with additional effects including delaying gastric emptying and promoting satiety. 7,10 Motility brakes within the colon and rectum have also been described, though they remain less well established.Published examples include withholding de...

Hyperactive cyclic motor activity in the distal colon after colonic surgery as defined by high-resolution colonic manometry

“…Cyclic motor patterns are known to be a normal feature of human colonic motor activity. In previous studies under non‐operative conditions, cyclic motor patterns were shown to occur in the distal colon and rectum, primarily in response to a meal, and mainly propagated in a retrograde direction, potentially contributing to a ‘rectosigmoid brake’ that limits rectal filling. The postoperative cyclic activity had both similarities and differences to the normal postprandial cyclic pattern.…”

“…The postoperative event rate was much higher (nearly continuous), with a faster antegrade velocity and occurring nearly synchronously in some traces, but events were comparable in frequency and amplitude. The authors consider cyclic motor patterns to be synonymous with what others have variously termed ‘periodic rectal motor activity’ or ‘rectal motor complexes’, and these have notably been observed to occur at 2–4 c.p.m. in low‐resolution studies of the healthy human colon.…”

Development and feasibility of an ambulatory acquisition system for fiber‐optic high‐resolution colonic manometry

“…High‐resolution (HR) colonic manometry is an emerging technique, enabling recordings up to the full length of the colon with sensors spaced at 1 cm intervals, yielding improved spatiotemporal detail . This novel technology has provided new insights into colonic motility in health, and in a range of motility disorders including bowel dysfunction in the early postoperative period following abdominal surgery …”

“…5This novel technology has provided new insights into colonic motility in health, and in a range of motility disorders including bowel dysfunction in the early postoperative period following abdominal surgery. 3,[7][8][9][10][11] Ambulatory colonic manometry recordings have previously been described; however, these have all used low-resolution Abstract Background: High-resolution colonic manometry is an emerging technique that has provided new insights into the pathophysiology of functional colorectal diseases.Prior studies have been limited by bulky, non-ambulatory acquisition systems, which have prevented mobilization during prolonged recordings.…”

Contouring pudendal nerves

“…Moreover, members of the author group show in separate articles that the colon moves in retrograde direction, possibly helping us to reabsorb fluid [12][13][14]. Dysfunction of this 'large-bowel brake' may be important for contracting the urgency syndrome.…”