3. Clinical use of anorectal biofeedback

## 3.1. Anorectal biofeedback in terminal constipation

Chronic constipation is defined as the evacuation of stools from the bowel less frequently than once every 3 days [11]. It also corresponds to the types 1 and 2 of the Bristol Stool Form Scale [12]. Two main factors may cause chronic constipation: slow transportation or difficult evacuation [13]. Therefore, we may encounter two types of constipation: transportation constipation and terminal constipation or dyskesia. Sometimes both factors are contributing to constipation. In this case, we speak of mixed constipation. The indication to use biofeedback in terminal constipation relies first on the identification of this kind of constipation. The diagnosis of terminal constipation is assessed by the measurement of colonic transit time with radiopaque markers [14]. This is a simple method allowing the estimation of total colonic transit time, as well as of segmental transit times for proximal colon, distal colon and rectosigmoid. A normal transit time of the colon rules out the transportation constipation. It is not uncommon to observe a difference between patients' symptoms and real transit time when assessed by radiopaque markers. This difference might be explained either by over reporting of anxious constipated patients or by variability of transit from day to day in same subject.

Terminal constipation has to be confirmed by anorectal manometry. Anorectal manometry is able to diagnose terminal constipation when rest anal pressures are high or when the anal sphincter does not relax after the dilation of an intrarectal balloon. This is caused by the lack of the inhibitory recto-anal reflex. In some cases, the fecal bolus is not perceived because of altered visceral sensitivity or of the enlargement of the rectal ampulla.

If the terminal constipation cannot be managed with normal dietary and pharmacological measures, one should proceed to anorectal biofeedback. The first session starts with the routine anorectal manometry just to identify the pathogenic background and to explain it to the patient. This investigation represents the baseline for consecutive measurements during next sessions. The patient has the possibility to look to the screen of the manometric device and to find out pressure and relaxation alterations.

The sessions are grouped in four steps [15]. During the first step, the patient learns how to try to expel the fecal bolus; during these exercises, the patient tries to relax the anal sphincter to allow to the stool to pass through out. Simultaneously the patient learns how to increase the abdominal pressure. These exercises should be repeated after at least 1 min, several times, for 30 min. If fatigue occurs, the rhythm of exercises should be diminished. During this exercise, one shows to the patient how the correct modality to expel the stool is and is encouraged to continue practicing. In the second step, the patient is helped to become aware of the independence of abdominal and anal contractions. The patient has to contract the anal sphincter without contracting the abdominal muscles and later to contract the abdominal muscles without contracting the anal sphincter. During the third step, the anal relaxation is practiced. After few exercises with the anorectal balloon, the patient is instructed to perform the Valsalva maneuver. The fourth and last step is the forced push to correctly expel the balloon. This movement starts with a diaphragmatic aspiration followed by a respiratory blocking; pushing the balloon has to be energic, progressive and direct. The abdomen of the patient has to become convex. The aim of this maneuver is to obtain three steps elimination of the rectal content: balloon during feedback exercises, feces in real life. The three steps are: anal sphincter relaxation, aspiration of the diaphragm and apnea, correct pushing maintaining the sphincter in relaxed state.

These sessions of anorectal biofeedback should be repeated weekly. Patients can perform also at home these exercises, either without computer, or with transportable biofeedback devices. The length of the therapy is at least 3 months of weekly sessions followed by monthly sessions for another interval of 3–6 months.
