RESUMO
We studied the ability to defecate water-filled balloons in 16 healthy and 37 chronically constipated children with encopresis. The act of bearing down for defecation was evaluated by measuring intra-abdominal pressure, rectal pressure, anal pressure, external anal sphincter EMG activity, and rectal sensation and rectal volume necessary to inhibit the anal sphincters. Fifteen control children and 20 constipated children were able to defecate rectal balloons. External sphincter activity decreased during the act of bearing down for defecation in 100% of controls, in 58% of constipated children able to defecate balloons, and in only 7% of patients unable to defecate balloons. Constipated children unable to defecate balloons were significantly less likely to recover after conventional laxative treatment than constipated children able to defecate balloons (P less than 0.02). Increased external sphincter activity during defecation appears to be the factor that prevents balloon expulsion in constipated children and could be the cause of their chronic fecal retention.
Assuntos
Constipação Intestinal/fisiopatologia , Defecação , Encoprese/fisiopatologia , Canal Anal/fisiopatologia , Criança , Doença Crônica , Eletromiografia , Humanos , Masculino , Manometria , Reto/fisiopatologiaRESUMO
Using a strain gauge, we measured anal sphincter function in 116 chronically constipated and 18 healthy children. Eighteen constipated children were re-evaluated two months later (receiving laxative), and 15 were again studied seven to 12 months later. The anal resting tone varied along the length of the anal canal and was highest at 1 to 1.5 cm from the anal verge. This region was used to study the resting motor activity of the internal anal sphincter, the amplitude of the rectosphincteric reflex after 30 and 60 ml rectal distension, and the rectosphincteric reflex threshold. The mean and resting tone was significantly lower in constipated than in control children (P less than 0.001), but normalized in patients who recovered. Resting motor activity of the internal anal sphincter and the amplitude of RSR were significantly lower in constipated patients than were the corresponding values in control children (P less than 0.001), and remained lower during and after treatment, even in patients who recovered. The length of the anal canal and the RSR threshold were comparable in control and constipated children. Thus, the basic problem in chronically constipated children appears to be an abnormal internal anal sphincter, which is weaker and less responsive to rectal distension than in nonconstipated children.