New Insights into the Pathogenesis of Irritable Bowel Syndrome

Irritable Bowel Syndrome is one of the most frequently seen functional bowel diseases characterized by recurrent abdominal pains and change in bowel habits (diarrhea/constipation). IBS is a long-term illness in which patients suffer from chronic or recurrent gastrointestinal symptoms despite the fact that routine clinical investigations are normal. Although regional variation exists, the prevalence of IBS ranges from 10–15% in population-based studies in North America and Europe. The prevalence of IBS is most common between 20 and 40 years of age with a significant female predominance (1). Irritable bowel syndrome is divided into four sub-groups by evaluation of the patient’s stool according to BSFS (Bristol Stool Form Scale) as diarrheapredominant, constipation predominant, mixed type and the ungroupable. Constipation predominant IBS diagnosis (IBS-C) is made if more than 25% of bowel movements are type 1 or type 2 and less than 25% is type 6 or 7. Whereas in the diarrheapredominant IBS (IBS-D); while more than 25% of the bowel movements are type 6 or type 7, less than 25% are type 1 or type 2. In mixed-type IBS (IBS-M); in more than 25% of the bowel movements type 1 or type 2 and again in more than 25% type 6 or type 7 coexistence is seen. The patients that do not fall into any of these three categories are included to the unsubtyped group (IBS-U). And in time, inter-type transitions may be observed in 75% of these patients. IBS is associated with decreased quality of life, Abstract: Irritable Bowel Syndrome is one of the most frequently seen functional bowel diseases. Despite its high prevalence, the etiology and pathogenesis of IBS could not still be explained completely and diagnosing is quite difficult in some cases. IBS, being a multisymptomatic functional gastrointestinal system disease, has a broad clinical spectrum and in general, the symptoms are associated with gastrointestinal dysmotility and visceral hypersensitivity. The true diagnosis is based on four key factors: medical history, physical examination, minimal laboratory tests and colonoscopy or other appropriate tests in some cases. However, a homogeneous pathophysiological pattern has not been defined for IBS and this situation, with a high degree of probability, reflects that IBS is a multifactorial disorder that involves abnormalities in brain-gut interactions, visceral hypersensitivity, intestinal motility and secretion, psychosocial factors, composition of the gut microbiota, disturbed intestinal permeability and low grade immune activity.