# Irritable Bowel and Fibromyalgia



## eric (Jul 8, 1999)

FYIwith permissionThe Association of Irritable BowelSyndromeand FibromyalgiaLin Chang, MDAssociate Professor of Medicine,Co-Director of the UCLA/CURE Neuroenteric Disease Program,Director of the UCLA Motility UnitIrritable bowel syndrome (IBS) is a very common gastrointestinal condition, which is present in8-20% of the general population. Several population-based studies have demonstrated IBSsymptoms to be more common in women, with prevalence ratios ranging from 2 to 3:1. It hasbeen estimated to affect 14-24% of women and 5-19% of men. The classic gastrointestinalsymptoms of IBS are chronic or recurrent abdominal pain and/or discomfort and associatedalterations in bowel habits. However, many individuals with IBS also suffer from nongastrointestinalsymptoms. Rheumatologic symptoms, such as skin rashes, muscle contractionheadache and myalgias, have been reported in two-thirds of IBS patients. Previous studies havefound that IBS typically overlaps with fibromyalgia syndrome (FM) in the same patient,suggesting a common cause. FM occurs in up to 60% of patients with irritable bowel syndrome(IBS). Up to 70% of patients with a diagnosis of FM have symptoms of IBS.FM belongs to a general class of chronic musculoskeletal pain syndromes. It is a common paindisorder in which the presence of multiple muscular tender points is associated withcharacteristic symptoms of generalized muscle aching, stiffness, fatigue and an abnormal sleeppattern. Following osteoarthritis and rheumatoid arthritis, FM is the most common disorder seenin community rheumatologic practice. In rheumatology clinics, the proportion of new patientswith FM syndrome ranges from 10% to 20%, while in non-specialized settings, the reportedprevalence is less, 2.1% to 5.7%. FM affects 2% for both sexes, 3.4% for women and 0.5% formen. The diagnosis of FM is presently defined by criteria, which consists of widespread painand presence of painful tender points established by the American College of Rheumatology in1990.Although IBS is a chronic gastrointestinal pain condition and FM is a chronic muscular paindisorder, IBS and FM have common clinical characteristics: (1) both are functional paindisorders which cannot be explained by structural or biochemical abnormalities, (2) both occurpredominantly in women, (3) the majority of patients associate stressful life events with theonset or exacerbation of symptoms, (4) the majority of patients complain of disturbed sleep andfatigue, (5) psychotherapy and behavioral therapies are efficacious in treating symptoms, and(6) certain medications can treat symptoms of both conditions. It has been suggested that IBSand FM have a common cause and that specific physiologic alterations may be responsible forthe symptoms seen in these two conditions.2While IBS is a condition characterized by visceral (intestinal) hypersensitivity, FM is acondition of somatic (skin and muscle) hypersensitivity. There have been several studies, whichhave shown that IBS patients have normal or decreased somatic sensitivity. We have recentlycompleted somatic perception studies in female patients with IBS alone, both IBS + FM, andhealthy individuals (see Chang et al.). The response to pressure which was placed on particularmuscle tender points was measured. Like FM patients, patients with IBS + FM demonstratesomatic hyperalgesia (increased somatic pain sensation). However, patients with IBS alone havesomatic hypoalgesia (decreased somatic pain sensation). This study demonstrates that while IBSpatients have increased sensitivity to visceral pain, they are less sensitive to somatic pain.Only a couple of studies have evaluated visceral sensation in FM patients using a ballooncatheter placed in the rectum and lower large intestine (colon). The balloon catheter isconnected to a computerized pump which inflates the balloon and thus reaches specific pressurelevels in the bowel. The patient's sensations in response to the balloon inflation can bemeasured. These studies have reported that patients with FM with or without IBS have visceralperception in between that of healthy controls and IBS patients. These data suggest that IBShave altered perceptual responses to visceral and somatic pain/discomfort and the coexistence ofFM alters these perceptual responses.Recent studies using brain-imaging techniques have found alterations in how the brainprocesses visceral information in IBS. To determine if similar altered responses to visceral andsomatic pain information occurs in patients with IBS and FM, we have compared the brainresponses to visceral and somatic stimuli in patients with IBS alone, IBS + FM, and healthyindividuals. Brain responses are assessed by positron emission tomography (PET), which canmeasure blood flow to brain areas in response to a particular stimulus. Results have shown thatpatients with both IBS and FM have greater brain responses in areas which are involved in pain,memory retrieval of past pain experiences and increased attention or awareness to a stimulusthan the other subject groups. Recent functional brain imaging studies have suggested thatalterations in the processing of sensations by the brain play an important role in IBS and FM.In summary, clinical characteristics and a significant overlap of symptoms suggest that thefunctional syndromes IBS and FM may have a common etiology. Visceral and somaticperception studies and brain imaging have demonstrated that each of these conditions havespecific responses to painful stimuli and that patients with both IBS and FM may haveresponses to somatic and visceral stimuli that are uniquely different from that of IBS alone andFM alone. Further studies are being performed in these common conditions to further ourunderstanding of chronic visceral and somatic pain conditions and lead to more effectivetreatment.Selected References:1. Veale, D., Kavanagh, G., Fielding, J.F. and Fitzgerald, O. Primary fibromyalgia and the irritable bowelsyndrome: different expressions of a common pathogenetic process, British Journal of Rheumatology, 30(1991) 220-222.2. Whitehead, W.E., Holtkotter, B., Enck, P., Hoelzl, R., Holmes, K.D., Anthony, J., Shabsin, H.S. andSchuster, M.M. Tolerance for rectosigmoid distention in irritable bowel syndrome, Gastroenterol., 98(5 Pt1) (1990) 1187-1192.3. Cook, I.J., Van Eeden, A. and Collins, S.M. Patients with irritable bowel syndrome have greater pain3tolerance than normal subjects, Gastroenterol., 93 (1987) 727-733.4. Moldofsky, H. and Franklin, L.A. Disordered sleep, pain, fatigue, and gastrointestinal symptoms infibromyalgia, chronic fatigue and irritable bowel syndromes. In: E.A. Mayer and H.E. Raybould (Eds.),Basic and Clinical Aspects of Chronic Abdominal Pain, Elsevier, New York, 1993, pp. 249-256.5. Chang, L. The association of functional gastrointestinal disorders and fibromyalgia. Eur J Surg (Suppl583) 164: 32-36, 1998.6. Chang, L., Mayer, E.A., FitzGerald, L., Stains, J., Naliboff, B. Differences in somatic perception inpatients with irritable bowel syndrome with and without fibromyalgia. Pain 84:297-307, 2000.7. Chun A, Desautels S, Slivka A, Mitrani C, Starz T, DiLorenzo C, Wald A. Visceral algesia in irritablebowel syndrome, fibromyalgia, and sphincter of oddi dysfunction, type III. Dig Dis Sci 1999;44(3):631-6.8. Silverman, D.H., Munakata, J.A., Ennes, H., Mandelkern, M.A., Hoh, C.K. and Mayer, E.A., Regionalcerebral activity in normal and pathological perception of visceral pain, Gastroenterol., 112 (1997) 64-72.9. Mertz H, Morgan V, Tanner G, Pickens D, Price R, Shyr Y, et al. (2000): Regional cerebral activation inirritable bowel syndrome and control subjects with painful and nonpainful rectal distension.Gastroenterology 118:842-848.10. Chang, L., Mayer, E.A., Munakata, J., et al. Differences in left prefrontal activation to visceral andsomatic stimuli assessed by O15-water PET in female patients with irritable bowel syndrome (IBS) andfibromyalgia. Gastroenterology 114: A732, 1998.11. Wolfe, F. et al. The American College of Rheumatology 1990 criteria for the classification offibromyalgia, a report of the Multicenter Criteria Committee, Arthritis Rheum., 33 (1990) 160-172.


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