RESUMO
BACKGROUND: Biofeedback based on anomanometric techniques has been shown to be effective in the treatment of children with encopresis. The long-term efficacy of biofeedback and which variables of anorectal manometry (anorectal manometry) could help to establish biofeedback indications are currently the subject of debate. OBJECTIVES: To identify which variables of anorectal manometry, in addition to symptoms, could be useful in deciding which patients could benefit from biofeedback therapy and to assess the outcome of this treatment. PATIENTS AND METHODS: Anorectal manometry was performed in 88 patients, who were referred to our service complaining of soiling at least once a month for a minimum of 6 months after a period of normal continence of 1 year or more. The chronological and mental age of the patients was 4 years. All patients were otherwise in good health and had shown no response to medical treatment. The following variables were studied: anal canal profile, rectoanal inhibitory reflex (RAIR), continence reflex, rectal sensitivity, external anal sphincter (EAS) activity and defecatory maneuver. The patients were divided into two groups, according to clinical and anomanometric impairment, and the most affected patients (n = 41) underwent biofeedback therapy. The indications and outcome of biofeedback were assessed through clinical course and anorectal manometry. In the statistical analysis, the mean and standard deviation were calculated. The chi-squared test with Yates' correction was used to compare clinical and manometric qualitative parameters; Student's t-test was used to compare quantitative parameters; nonparametric tests consisted of the Mann-Whitney test and the Wilcoxon test was used for paired data. RESULTS: Patients treated with biofeedback therapy presented shorter anal canal, greater pressure in the rectal ampulla (P < 0.001), decreased pressure in the anal canal (P < 0.05), lesser distension of the EAS on provoking RAIR, lower presence of the continence reflex (P < 0.01), lower rectal sensitivity, and a worse response of the striated sphincteric muscle and of the defecatory maneuver (P < 0.001). Seventy-eight percent of the patients had a good response to biofeedback therapy. Pressure in the anal canal and rectal sensitivity improved (P < 0.001) with normality on straining in 11 out of 15 patients. These good results persisted in a long-term follow-up of 10 patients. Eight of 10 patients who did not undergo biofeedback therapy showed persistent encopresis (P < 0.001). CONCLUSIONS: Anorectal manometry detected disturbances, chiefly in the activity of the EAS, which are useful in indicating biofeedback therapy in children with secondary encopresis. Biofeedback therapy seems to produce favorable long-term results in the majority of the most severely affected patients.