with IBS have higher rates of absenteeism from work and school. In one U.S.-based study, the direct healthcare costs for patients with IBS were estimated at $8billion, while indirect costs were estimated at $25 billion per year. Such studies overlook the significant societal impact of IBS in terms of physical and emotionalfunction, interpersonal relationships and psychological distress.What is Irritable Bowel Syndrome?Irritable Bowel Syndrome is a chronic condition of the lower gastrointestinal tract. The symptoms of IBS may include abdominal pain, distention, bloating, indigestionand various symptoms of defecation. There are three subcategories of IBS, according to the principal symptoms. These are pain associated with diarrhea; painassociated with constipation; and pain and diarrhea alternating with constipation (Figure 3). Each patient’s symptoms are unique. While IBS may occur as anoccasional nuisance for some people, others may experience intense pain that compromises their quality of life.Figure 3.The three symptom subcategories of Irritable Bowel Syndrome.IBS does not lead to more serious disease, nor does it shorten the life span of those affected. It is not an inflammatory, infectious or malignant condition and has not
been found to lead to colitis. Furthermore, IBS is not a psychiatric disorder, although it is tied to emotional and social stress, which can affect both the onset andseverity of symptoms. While IBS is not considered a life-threatening disease, IBS patients suffer from a disproportionately higher rate of co-morbidity with otherdisorders, such as fibromyalgia, chronic fatigue, pelvic pain and psychiatric disorders.Primary features of the syndrome include motility, sensation and central nervous system dysfunction. Motility dysfunction may be manifest in muscle spasms;contractions can be very slow or fast. An increased sensitivity to stimuli causes pain and abdominal discomfort. Researchers also suspect that the regulatory conduitbetween the central and enteric pathway in patients suffering from IBS may be impaired.Research suggests that many patients with Irritable Bowel Syndrome have disorganized and appreciably more intense colonic contractions than normal controls. Astudy at Johns Hopkins reported that healthy volunteers had 6–8 peristaltic contractions in the colon in a 24-hour period. In contrast, IBS volunteers in whom theprimary symptom was constipation had almost no contractions, and IBS volunteers in whom the primary symptom was diarrhea had as many as 25 contractions aday. Researchers have also found that pain is frequently associated with irregular motor activity of the small intestine when compared with either normal controls orpatients with Inflammatory Bowel Disease. Patients with this disease appear to have a defect of visceral pain processing—although whether or not this is a truehypersensitivity or hyper-vigilance remains controversial. Interestingly, however, ileal and rectosigmoid balloon-distention studies have demonstrated that patients withIBS experience pain and bloating at balloon pressures and volumes that are significantly lower than those which cause symptoms in normal controls.