Dietary treatment of IBS consists of avoiding foods that are associated with symptoms, including alcohol, caffeine, sorbitol, and foods that increase gas production. Although increased dietary fiber or fiber supplementation has been shown to improve the constipation-predominant form of this illness, fiber supplementation has little effect on the diarrhea variant associated with fecal incontinence. Pharmacologic therapy is directed toward the predominant symptom. Loperamide and Lomotil tend to be useful first-line agents for treating diarrhea. Tricyclic antidepressants improve abdominal discomfort and are also valuable in diarrhea-predominant patients because of their constipating effect. The serotonin type 3 (5HT3) antagonist alosetron (Lotronex) has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of severe diarrhea-predominant IBS refractory to treatment. It has shown improvement in global assessment measures, but its use is limited because of multiple isolated case reports of ischemic colitis. The recommended dose is 1 mg once or twice daily. It does not appear to be effective for the spastic-pain variant of IBS. Anticholinergics (dicyclomine, hyoscyamine) and antispasmodics (mebeverine, pinaverine) are targeted at the pain and bloating symptoms but may also be useful for the diarrhea variant because of their constipating side effects. Studies comparing anticholinergic medications to placebo show inconclusive results with only modest benefits. Antispasmodic agents may also be of value and are available in many countries but are not approved for use in the United States. Currently, additional 5HT3 antagonists and 5HT4 antagonists are under development and are approved for use in Europe but not in the United States. Most studies are poorly designed and difficult to interpret because of a high placebo response rate that often exceeds 30% (95,96).
Biofeedback can be an effective therapeutic modality provided patients are motivated and comprehend instructions. The two proposed mechanisms through which biofeedback improves fecal continence are afferent and efferent training. Afferent training focuses on improving sensation in the anorectal canal through recruitment of adjacent neurons to decrease the sensory threshold of volume stimulation. The goal of this training is to enhance and restore anal sensation and the rectoanal inhibitory reﬂex. Efferent training enhances and restores voluntary contraction of the EAS, which permits additional recruitment of motor units and stimulates muscle hypertrophy. These two methods of training can be performed independently but are often combined for additional therapeutic benefit. The most common training method uses an intrarectal balloon. The balloon acts to stimulate rectal distention and provide pressure feedback from coordinated or synchronized contraction of the pelvic ﬂoor muscles. Other techniques focus on strength training of the EAS alone using anal pressure feedback or EMG or afferent training alone using an intrarectal balloon without pelvic ﬂoor muscle contraction in response to the stimulus.
More than 35 studies have been done to evaluate the efficacy of biofeedback for treatment of fecal incontinence, and several excellent review articles and meta-analyses have determined the effects of individual treatments and predictors of patient response to treatment (97–99). The results of all of these studies uniformly agree that biofeedback and pelvic ﬂoor exercises improve fecal incontinence and have a role in clinical practice. They also agree that the existing literature is fraught with methodologic problems and lacks validated outcomes and controls. Thus it is difficult to compare directly the study results.
Biofeedback is an ideal first-line therapy because it offers an effective, minimally invasive treatment without any reported adverse events. Biofeedback also appears to provide a higher probability of successful outcome than standard medical care for treating functional fecal incontinence (67% vs. 36%, respectively, P < .001) (97).