Irritable Bowel Is Treatable
But expert says it must first be diagnosed accurately using the Rome II criteria for presenting symptoms
Exert effort to diagnose it. And diagnose it precisely.
Dr. W. Grant Thompson, professor emeritus of the University of Ottawa, Canada asked Filipino physicians to consider this piece of advice when confronted with a patient showing symptoms of irritable bowel syndrome (IBS).
Speaking at a symposium on Changing Perceptions on IBS organized by Novartis Healthcare Philippines, Dr. Thompson said diagnosing IBS isn't easy, as there are no tests to confirm it and a physician has to rely on the presenting symptoms. He described IBS as a symptom complex characterized by chronic or recurrent abdominal pain, a chaotic bowel habit that may manifest as constipation or diarrhea or both alternately, and bloating without any change in the structure of the gut. No recognizable pathology has been found.
Dr. Thompson said a diagnosis of IBS can safely be made using the Rome II criteria (abdominal pain or discomfort for at least 12 weeks, not necessarily consecutive, in the preceding 12 months with two of these features: relieved by defecation, changes in stool frequency, form, or appearance).
For as long as the patient has no history of other GI pathologies (colon cancer, inflammatory bowel disease, or celiac disease) and has no alarm symptoms (bleeding, anemia, fever or weight loss), physicians need not fear making a diagnosis of IBS sans the security blanket of superfluous tests, he added.
Dr. Thompson said IBS has been reported in practically all continents with a global prevalence of seven to 25 percent. The 32nd Annual Digestive Disease Week 2001 says IBS is next only to the common cold as cause of work absence.
Various hypotheses as to its pathophysiology have been put forward. IBS was formerly attributed to poor diet. As such, a host of IBS diets formulated by both doctors and alternative medicine practitioners came into fashion. Physiologists held that a motility disorder accounted for the diarrhea and constipation. Psychologists and psychiatrists theorize that the disease was a manifestation of a psychological disturbance. Some believe that a chemical inflammation from the release of mediators in the gut could explain the abdominal pain and irregular bowel symptoms. None of these has been been proved.
Dr. Thompson said the most popular IBS hypothesis suggests a hypersensitive gut or visceral hyperalgesia. It is believed that distention of the intestinal tract causes pain and discomfort in IBS patients. Since the gut is hypersensitive to distention, it also hyperreacts to meals. And because IBS sometimes follows an attack of gastroenteritis or acute emotional trauma, stress becomes a factor. The gut-brain connection has been invoked to explain this phenomenon in that the enteric nervous system is also linked to the central nervous system such that a disturbance in one area could cause a malfunction in the other.
Management
For management purposes, IBS can be classified into three subtypes-diarrhea-dominant, constipation-dominant, and alternating IBS-which most patients experience alternately or at at the same time. The classification helps a physician determine what treatment to adopt.
Dr. Thompson said a balanced diet should be encouraged but there is no such thing as an IBS diet. Fat, artificial sugar, caffeine, and alcohol should be avoided. There have been attempts to use loperamide to control diarrhea, low-dose amitriptyline for chronic pain, and bulking agents and bran for constipation. But no single study has convincingly shown any therapeutic agent effective.
Dr. Thompson said there is hope with drugs that act on the serotonin receptors. There are 12 types of serotonin all tickling different receptors in the body. In the gut there is the 5-HT3 and 5-HT4 receptors. In fact, serotonin is found in the enteric nervous system in greater concentrations than in the CNS.
New drug tegaserod (Zelnorm) is the first among serotonin-4 receptor partial agonists (5-HT4 agonists) developed for treatment of multiple symptoms associated with IBS and constipation. By activating the receptor in the gastrointestinal tract, tegaserod stimulates motility and intestinal secretion. It also appears to decrease visceral sensitivity to relieve abdominal pain.
Dr. Thompson said a 12-week tegaserod trial showed that compared with placebo, tegaserod had a statistically significant therapeutic gain measured every week. When the drug was withdrawn after 12 weeks, the effects fell for both the placebo and tegaserod but the statistical difference between the two groups remained.
Researchers are also exploring the possibility of using tegaserod in other GI disorders like gastroesophageal reflux disease, gastroparesis, fuctional dyspepsia, GI pseudoobstruction, and slow transit constipation.
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