The puborectal continence reflex: a new regulatory mechanism controlling fecal continence

Abstract

PurposeFecal continence is maintained by voluntary and involuntary contraction of the anal sphincter, and voluntary contractions of puborectal muscle. We investigated whether the puborectal muscle can control fecal continence not only by voluntary contractions but also by involuntary contractions.MethodsWe performed anorectal function tests in 23 healthy subjects. The anorectal pressure test was used to investigate voluntary contractions of the puborectal muscle. The balloon retention test was used to assess if the puborectal muscle can contract involuntarily.ResultsDuring the balloon retention test, we observed an involuntary contraction of the puborectal muscle, which gradually increased during progressive filling of the rectum. The maximal involuntary contraction of the puborectal muscle was significantly stronger and longer than its maximal voluntary contraction (150 versus 70 mmHg, P < 0.001 and 5.8 versus 1.5 min, P < 0.001).ConclusionsWe found that the puborectal muscle is able to contract involuntarily during rectal dilatation. It is a new regulatory mechanism, called the puborectal continence reflex, which controls fecal continence by involuntary contraction of the puborectal muscle. It seems to be initiated by dilatation at the level of the puborectal muscle. Presumably, the puborectal continence reflex protects many patients with anal sphincter dysfunctions from fecal incontinence.

Pelvic floor rehabilitation to improve functional outcome and quality of life after surgery for rectal cancer: study protocol for a randomized controlled trial (FORCE trial)

“…This score covers the five most bothersome issues in terms of prevalence and impact of QoL, namely incontinence for flatus and liquid stool, frequency, clustering, and urgency. Scores range from 0 to 42, with subdivisions in three categories: no (0-20), minor (21-29), and major LARS (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42). A statistically significant association exists between a higher LARS score and an impaired QoL.…”

“…Having patients fully examined with regard to manometry and anorectal functioning and objectively measuring what the effects of PFR are after rectal surgery [36] would have been interesting. Especially since rectal (cancer) surgery with the construction of a low anastomosis might interfere with the puborectal continence reflex [37,38] and could induce clinical symptoms of fecal incontinence. However, such an examination turned out to be logistically infeasible for all patients due to the geographical spread of hospitals throughout the country and limited accessibility of anorectal function centers.…”

The puborectal continence reflex functions independently of the pudendal nerve

“…There is a normal voluntary contraction of the external anal sphincter and puborectal muscle. In addition, there is activation of the anal external sphincter continence reflex and the puborectal continence reflex which regulate the involuntary contractions of the external anal sphincter and the puborectal muscle, respectively . (b) Voluntary and involuntary contraction of a patient with pudendal neuropathy (woman 52 years old).…”

“…For these subjects, the median maximum pressure observed during the voluntary puborectal muscle contraction was 70 (25–245) mmHg and took a median of 1.5 min. The median value of the maximal pressure during involuntary contractions of the puborectal muscle was 150 (70–260) mmHg and the median duration of the contractions was 5.8 min .…”

“…The puborectal muscle can also contract voluntarily, which results in a sharper anorectal angle to maintain continence . Recently, we have shown that the puborectal muscle can also contract involuntarily and that these contractions are regulated by the puborectal continence reflex .…”