Evaluation of Anal Continence Function by Analysis of the Rectoanal Reflex

Seong, Moo Kyung; Yoo, Young Bum

Abstract

PURPOSE
The rectoanal reflex is a response of the anal sphincter to rectal distension, reflecting the functional nature of the anal sampling mechanism of rectal discrimination. The role of this reflex in the continence mechanism is believed to be important, but it exact role still remains to be proven, and the stratification of this reflex, along to the degree of functional impairment of the anal sphincter, is rarely performed. The aim of this study was to assess the differences between various parameters of this reflex among healthy volunteers and incontinent and constipated patients. METHODS: The rectoanal contractile and inhibitory reflexes were recorded in 20 normal controls (group A) and 25 constipated (group B) and 19 incontinent patients (group C). The latencies, areas under the reflex curves, amplitudes and recovery times of each reflex were individually estimated, and differences between the groups statistically analyzed. RESULTS: The inhibitory reflex was not detected in 2 cases from group B (8.0%) and 1 from group C (5.26%). The contractile reflex was not detected in 2 cases from group A (10.0%), 8 from group B (32.0%) and 10 from group C (52.63%). There were no significant differences in any of the parameters in a comparison of the three groups. In a two group comparison, the amplitude and area under the reflex curves of the inhibitory reflex differed significantly between groups B and C (P=0.0373, 0.0238), and the latency of the contractile reflex differed significantly between groups A and C (P=0.0476). CONCLUSION: Both the rectoanal reflexes showed significant differences between the three patient groups, although this was not the case with all parameters. An analytical assessment of the various parameters of those reflexes would, therefore, make it possible to stratify the functional impairment of anal continence.