Irritable bowel syndrome. Streamlining the diagnosis

IBS is one of the most common of the gastrointestinal disease, but it can be a diagnostic challenge because of the many symptoms that overlap with other such diseases. Most common among the symptoms are abdominal pain, a feeling of intestinal distention or bloating, and either diarrhea or constipation. Patients may be found to have an exacerbation of symptoms with stress, and they may have an increased sensitivity to bowel distention. History and physical examination findings often can be relied on to make the diagnosis, avoiding overuse of laboratory testing. Treatment consists of patient education and support, lifestyle and dietary changes, and use of several pharmacologic agents for symptom relief. Antidepressants are being investigated as a possible additional form of treatment.

Functional dyspepsia and irritable bowel syndrome: is there a common pathophysiological basis?

OBJECTIVES

Alterations of mechanosensitive thresholds occur in a subset of patients with functional dyspepsia and irritable bowel syndrome (IBS). However, symptoms associated with these two conditions frequently overlap. It is not known how often subjects with and without symptom overlap have abnormal intestinal sensory thresholds. Our objective was to assess the pattern of symptoms and small intestinal sensory thresholds in patients with functional disorders.

METHODS

We studied 157 consecutive patients who had undergone extensive diagnostic work-up to exclude organic disease. Abdominal symptoms were assessed with a validated instrument, and patients were categorized as having functional dyspepsia, IBS, or both. With a barostat device, we tested small intestinal mechanosensitive function in 22 randomly selected patients from this population (with functional dyspepsia, IBS, or both) and 22 healthy controls.

RESULTS

Sixty-seven patients (43%) reported simultaneous symptoms of functional dyspepsia and IBS, whereas symptoms of functional dyspepsia or of IBS alone occurred in 68 (43%) and 22 (14%) patients, respectively. Thresholds for first perception and maximum tolerated pressure (mm Hg +/-SD) were significantly lower in patients (21.0 +/- 2.0 and 31.0 +/- 1.0) than in controls (32.0 +/- 1.8 and 39.0 +/- 0.9, p < 0.001). However, thresholds for first perception and maximum tolerated pressure did not differ (p > 0.6) in patients with functional dyspepsia alone (20.1 +/- 3.2 and 28.9 +/- 2.5, n = 9), functional dyspepsia and concomitant IBS (19.9 +/- 2.7 and 30.7 +/- 2.2, n = 8), or IBS alone (23.5 +/- 2.3 and 33.3 +/- 3.0, n = 5).

CONCLUSIONS

Small intestinal mechanosensitive pathways are disturbed in patients with functional dyspepsia and IBS. Differences in the pattern and localization of symptoms probably do not reflect differences in small intestinal sensory thresholds. Functional dyspepsia and IBS cannot be distinguished on the basis of altered small intestinal sensory thresholds.

Sigmoid afferent mechanisms in patients with irritable bowel syndrome

Up to 60% of patients with IBS have lowered perception thresholds in the rectum to balloon distension. The current study sought to test the hypothesis that IBS patients with normal perception thresholds in the rectum show hypersensitivity of afferent pathways in the sigmoid colon. Eleven healthy normal subjects and eight IBS patients with normal rectal perception thresholds underwent a balloon distension protocol in the sigmoid and rectum. Discomfort thresholds, receptive relaxation, compliance, and referral patterns were measured. Although IBS patients had significantly lower discomfort thresholds in the sigmoid when measured as volume, pressure, and wall tension, thresholds were similar to normals. Receptive relaxation and dynamic compliance were significantly decreased in IBS patients in the sigmoid. Referral patterns were similar during sigmoid distention in IBS patients in comparison to normals. Despite normal perception thresholds in rectum and sigmoid, IBS patients show evidence for alterations in rectosigmoid afferent mechanisms. In the sigmoid, this is seen in the form of reduced reflex relaxation and compliance and in the rectum in the form of altered viscerosomatic referral.

Rapid gastric emptying in patients with functional diarrhea

OBJECTIVE

To analyze our experience in patients with chronic diarrhea by using a noninvasive transit study that measures gastric emptying as well as small bowel and colonic transit.

MATERIAL AND METHODS

Results from 94 consecutive transit tests, for which diarrhea was the main indication, were reviewed and correlated with the final classification of patients as having an organic or nonorganic disorder.

RESULTS

Sixty patients were considered to have a nonorganic cause of diarrhea, of whom 15 had previously undergone cholecystectomy. The other 34 patients were considered to have diarrhea on the basis of an organic diagnosis. Gastric emptying was more often rapid in patients with a nonorganic cause (P < 0.05), but not if cholecystectomy had been performed previously. Small bowel transit was fast more often in patients with organic diarrhea than in those with no organic cause of the diarrhea (P < 0.05); colonic transits showed no significant differences among groups.

CONCLUSION

The findings implicate a motor abnormality of the upper gut, rapid gastric emptying, as a pathophysiologic mechanism of functional bowel disorders with diarrhea. The results imply that additional prospective observations should be worth-while.

The short-term natural history of irritable bowel syndrome: a time-series analysis

Although researchers have studied irritable bowel syndrome (IBS), including its physiological and psychological characteristics and treatments' effectiveness, basic descriptive information about IBS has been limited to lists of symptoms and explanations of what IBS is not. The purpose of the present study is to describe how core IBS symptoms vary over time. Twenty-five subjects (17 females, 8 males), who were not receiving treatment for IBS, rated the severity of their IBS symptoms daily for 8 weeks. Four symptoms' (abdominal pain, abdominal tenderness, constipation and diarrhea) ratings were slimmed to create a primary IBS symptom score. The data were detrended, then a time-series analysis was performed. Many subjects' IBS severity was predictable over more than one day, and symptoms tended to occur in clusters rather than randomly. Anxiety and depression were slightly to moderately correlated with IBS variables, but virtually all of these correlations were nonsignificant.

Pain from rectal distension in women with irritable bowel syndrome: relationship to sexual abuse

The aims of this study were to determine whether increased pain sensitivity in patients with irritable bowel is due to physiological differences in perceptual sensitivity or psychological influences on perception, and whether prior sexual abuse accounts for increased pain sensitivity. Seventeen sexually abused and 15 nonabused women with irritable bowel were compared to 13 sexually abused and 14 nonabused women without irritable bowel. Among the nonabused subjects, the volume of rectal distension that produced moderate pain was lower in IBS patients than in controls, replicating earlier studies, but these thresholds were correlated with psychological measures of anxiety and somatization. The ability to discriminate between painful distensions (perceptual sensitivity) was not different between groups. Sexual abuse was not associated with lower pain thresholds. Thus, differences in pain sensitivity appear to be due to psychological influences on perception, but a history of sexual abuse does not contribute significantly to this pain sensitivity.

Belching, bloating, and flatulence. How to help patients who have troublesome abdominal gas

Gaseous belching, bloating, and flatulence are common complaints. These symptoms may herald the onset of important and treatable gastrointestinal diseases or may represent functional bowel disorders. The clinical challenge is to identify a cause so as to exclude serious gastrointestinal diseases and provide symptomatic relief. Detailed history taking and examination provide the basis for appropriate testing that may provide vital clues. Among otherwise healthy patients, intolerance to lactose or other food items is a common source of symptoms. This cause can be evaluated noninvasively using the breath hydrogen test. A clear understanding of the underlying pathophysiology paves the way for a rational approach to treatment, such as withdrawal of an offending food item, enzyme supplementation, simple reassurance, or psychotherapy.

Irritable bowel syndrome. A cost-effective approach for primary care physicians

Recognition and appropriate treatment of IBS can be challenging. A rational approach to management focuses on a positive diagnosis based on the characteristic pattern of symptoms and the exclusion of organic disorders. Dietary modification and pharmacologic therapy may be useful for relieving symptoms. Patient education and reassurance about the benign course of the disease are important aspects of effective treatment. In severe cases, referral to a psychologist or psychiatrist may be warranted. As our understanding of the pathophysiologic processes in IBS increases, more effective therapies will likely emerge.

Thermal therapy of functional dyskinesias of the alimentary tract

There are described the studies performed in Italy-especially at Montecatini-about activity of certain mineral waters, administered by mouth, in functional troubles of the digestive apparatus. The illnesses especially considered have been: idiopathic chronic constipation, irritable colon syndrome, biliary dyskinesias, correlated pathological conditions. The mineral waters analyzed had been: salso-sulphate-alkaline, bicarbonate, sulphate, bicarbonate-sulphate-alkaline, sulphate-bicarbonate waters and others. There are reported: research methods employed, the obtained results, the possible mechanisms of effect. The hydrological favourable influences about pathophysiology of digestive motor activity and in therapeutics of correlated diseases are demonstrated. The clinical results, and particularly their duration in time, are affermatif about therapeutic usefulness of thermal treatment by mouth. It's possible to suggest and to stress their better knowledge in Medicine and their increased employment in the treatment of functional dyskinesias of the alimentary tract.

[The irritable bowel syndrome. The prospects for improving the quality of life]

The lecture focuses on current concepts of etiology and pathogenesis of irritable colon syndrome and deals extensively with clinical manifestations of symptoms of the disease. Recommendation are given as to diagnosis and choice of optimal approaches to therapy with special reference to prospects for improvement of quality of the patients' life.

Diagnosis and treatment of irritable bowel syndrome

Irritable bowel syndrome is a common disorder characterized by symptoms of abdominal pain with diarrhea and/or constipation. It is associated with significant disability and health care costs. A practical approach to diagnosis utilizes the symptom-based Rome criteria. Management of patients has been helped by recent findings relating to the pathophysiology of the disorder. Dysregulation of intestinal motor functions, sensory functions and central nervous system functions is currently believed to be the basis for irritable bowel symptoms. Symptoms are a result of both abnormal intestinal motility and enhanced visceral sensitivity. Psychosocial factors can affect the illness experience and the clinical outcome. An effective physician-patient relationship is required for a successful outcome. Individualized treatment involves an integrated pharmacologic and behavioral approach determined by the predominant symptom type, the severity of the symptoms and the degree of disability.

A pilot study of motility and tone of the left colon in patients with diarrhea due to functional disorders and dysautonomia

OBJECTIVE

Our aim was to identify qualitative or quantitative colonic motor patterns induced postprandially in a pilot study of patients with diarrhea due to functional disease or dysautonomia to identify objective endpoints for future studies.

METHODS

In patients with functional diarrhea (n = 5) or dysautonomia (n = 4) in whom GI transit was documented by scintigraphy, we studied colonic motility by combined manometry and barostat measurements for 1 h fasting and 2 h postprandially (1000-kcal meal). Data were compared with those of healthy control subjects.

RESULTS

There were no differences in compliance, overall phasic motility of the left colon, fasting tone, or maximal change in postprandial tone in the diarrhea group as compared with the control group. The diarrhea group showed more high amplitude propagated contractions 4.4 +/- 3.6 (SD)/2 h, p < 0.05) compared with the control group (0.7 +/- 1.4/2 h); the mean postprandial tonic response (12 +/- 14%, p < 0.05) and its duration were reduced in the diarrhea group compared with the control group (27 +/- 17%). Two dysautonomic patients showed a paradoxical relaxation of the colon postprandially.

CONCLUSION

Reduced duration of increased colonic tone postprandially and increased number of high amplitude propagated contractions seem to be useful objective endpoints for future studies.

Defaecography in patients with irritable bowel syndrome and healthy volunteers

BACKGROUND

In patients with IBS, many symptoms have their origin in the recto-anal segment, with motility changes in the rectum and in the internal anal sphincter, and alterations in rectal sensitivity. However, up to now, it is not known if these clinical and physiological changes are equated with morphological changes in the recto-anal segment.

METHODS

Sixteen consecutive patients with IBS (mean age 22, range 18-33 years; 13 females) and 10 healthy volunteers (mean age 34.5, range 19-50 yr.; 6 males) were evaluated prospectively with defaecography.

RESULTS

1) Anorectal angle: No significant differences were observed in the anorectal angle during rest (91.6 +/- 3.5 degrees vs 92.6 +/- 2.5 degrees) and during defaecation (92 +/- 5.5 degrees vs 98.7 +/- 2.6 degrees) between patients with IBS and healthy volunteers. However, patients with IBS were unable to widen the angle during defaecation, remaining the same at rest (91.6 +/- 3.5 degrees) as during defaecation (92 +/- 5.5 degrees). IBS patients with constipation (n = 2) compared to those with normal frequency defaecation (n = 13) showed no significant differences at rest (95 +/- 6 vs 89.8 +/- 4.1 degrees) and during defaecation (100 +/- vs 88.9 +/- 6.4 degrees). Healthy volunteers widened the angle by more than 5 degrees during defaecation. 2) Perineometry: although not significant, patients with IBS had less perineal descent during the simulated defaecation (1.98 +/- 0.37 cm) than healthy subjects (2.1 +/- 0.3 cm). Nevertheless, during squeeze there was significantly less mobility or perineal descent in patients with IBS than in control subjects (0.21 +/- 0.17 vs 0.95 +/- 0.21 cm; P = 0.01).

CONCLUSIONS

The findings of this study suggest that patients with IBS as a whole, whether constipation predominant or not, showed changes in pelvic-floor mobility.

Large-scale ambulatory study of postprandial jejunal motility in irritable bowel syndrome

BACKGROUND

The relationship of small-bowel dysmotility to dietary intake in irritable bowel syndrome (IBS) is obscure.

METHODS

This study evaluated postprandial jejunal motility in IBS patients classified as constipation-predominant (n = 25) or diarrhoea-predominant (n = 35) and compared results against 18 volunteers. Twenty-four-hour ambulatory jejunal manometry was carried out in all subjects, and recordings were analysed by microcomputer and visual assessment.

RESULTS

By means of analysis of variance (fitting factors for channels, meals, and time periods) postprandial contraction frequency was greater in both patient groups compared with normal (constipation-predominant versus normal, diarrhoea-predominant versus normal; P < 0.001). In the constipation-predominant cohort, contraction amplitudes were lower (constipation-predominant versus normal; P < 0.002). Discrete cluster contractions occurred with similar frequency and duration in both patient and volunteer groups.

CONCLUSIONS

Quantitative differences of postprandial jejunal contraction characteristics have been shown between patients with IBS and healthy volunteers. Contraction frequency is greater than normal in both diarrhoea- and constipation-predominant categories, whereas contraction amplitudes are lower in constipation-predominant patients.

Repetitive sigmoid stimulation induces rectal hyperalgesia in patients with irritable bowel syndrome

BACKGROUND & AIMS

Only a fraction of patients with irritable bowel syndrome (IBS) show hypersensitivity to rectal distention. The current study sought to determine if repetitive high-pressure stimulation of sigmoid mechanoreceptors modulates perception of rectal pain and discomfort.

METHODS

In 14 patients with IBS and 11 healthy controls, perception thresholds for discomfort and pain during rectal sensory tracking and verbal descriptor ratings of the perceived intensity of a rectal tonic stimulus were obtained before and after repetitive high-pressure mechanical sigmoid stimulation. Gastrointestinal and psychological symptoms were assessed by questionnaires.

RESULTS

Despite heterogeneity in baseline rectal sensitivity in patients with IBS, after sigmoid stimulation, 100% of patients, regardless of baseline sensitivity, developed rectal hyperalgesia manifested by at least two of the following three criteria: lowered thresholds for pain and discomfort and increased viscerosomatic referral and lower abdominal discomfort outlasting the experimental stimulation. This pattern of responses was not observed in any of the healthy controls.

CONCLUSIONS

In patients with IBS, repetitive stimulation of sigmoid splanchnic afferents results in the development of central sensitization manifested as hyperalgesia and increased viscerosomatic referral during rectal distention and as spontaneous rectosigmoid hyperalgesia in the absence of applied stimuli. Repetitive sigmoid contractions may induce rectosigmoid hyperalgesia in patients with IBS.

Regional cerebral activity in normal and pathological perception of visceral pain

BACKGROUND & AIMS

To characterize the cerebral processing of noxious visceral events, changes in regional cerebral blood flow associated with perception of intestinal pain were examined.

METHODS

The effects of rectal pressure stimuli on regional cerebral blood flow were assessed with 15O-water positron emission tomography (PET) in 12 subjects, half with irritable bowel syndrome (IBS). PET scans were obtained at baseline and during both actual and simulated delivery of anticipated stimuli. Changes in regional cerebral blood flow were interpreted using statistical parametric mapping and region of interest methods of analysis.

RESULTS

In healthy subjects, perception of pain during actual or simulated delivery of painful stimuli was significantly associated (P < 0.01) with activity of the anterior cingulate cortex (ACC; Brodmann's areas 24 and 32), whereas no ACC response to perception of nonpainful stimuli was observed. In patients with IBS, the ACC failed to respond to the same stimuli, whereas significant activation (P < 0.01) of the left prefrontal cortex (maximal in Brodmann's area 10) was seen.

CONCLUSIONS

The perception of acute rectal pain is associated with activation of the ACC in healthy subjects, and patients with IBS show an aberrant brain activation pattern both during noxious rectal distention and during the anticipation of rectal pain.

The irritable bowel syndrome

Irritable bowel syndrome is a common disorder varying in severity from trivial to incapacitating. The pathophysiology and epidemiology are gradually being unravelled and it is now becoming apparent just how poor the quality of life of some of these patients can be. It is no longer acceptable practice to diagnose the condition and discharge the patient on a high fibre diet, particularly as the latter can often make the situation worse. Although hard to treat, worthwhile responses can be achieved by careful targeting of therapy to the many different facets of the disorder.

Rectal hypersensitivity in the irritable bowel syndrome

Studies of rectal sensory thresholds and compliance in patients with the irritable bowel syndrome have produced conflicting results though there is persistent evidence of rectal hypersensitivity particularly in those with diarrhoea-predominant symptoms. This study examined rectal sensation and compliance in 31 patients with constipation-predominant irritable bowel syndrome (mean age 41 years, 27 female) and 17 healthy volunteers (mean age 45 years, 17 female). A rectal balloon was inflated with fluid at a constant rate and the volume and intrarectal pressure at sensory threshold was recorded. The volumes at first (129 +/- 8 vs 229 +/- 24 ml, P < 0.001 Mann-Whitney-U test), constant (159 +/- 12 vs 286 +/- 21, P < 0.001) and maximum tolerated sensation (290 +/- 13 vs 509 +/- 19, P < 0.001) were all significantly less in the irritable bowel group. There was no significant difference in intrarectal pressures at any of these volumes (29.0 +/- 2.2 cmH2O vs 29.0 +/- 2.5, 35.0 +/- 2.5 vs 34.0 +/- 2.8, 71 +/- 2.5 vs 65.0 +/- 3.0 respectively). Rectal compliance was significantly less in the irritable bowel group (3.6 +/- 0.2 ml/cmH2O vs 8.7 +/- 0.4, P < 0.001). Twenty two patients complained of abdominal pain on balloon inflation, mimicking that experienced as part of their symptoms. Patients with constipation-predominant irritable bowel syndrome have rectal hypersensitivity and reduced compliance.

5-Hydroxytryptamine and functional bowel disorders

The possibility that 5-hydroxytryptamine (5-HT) acts as a key sensitising agent in the aetiology of irritable bowel syndrome (IBS) is reviewed. The strategic locations of 5-HT and its receptors are described, the most dominant being the 5-HT3 and 5-HT4 type. 5-HT, acting mostly at 5-HT3 or 5-HT3-like receptors, enhances the sensitivity of visceral neurones projecting between the gut and the central nervous systems. 5-HT, acting at 5-HT4 receptors promotes the sensitivity of enteric neurones that react to luminal stimuli. 5-HT4 and 5-HT3 receptors also mediate, respectively, sensitising and physiological actions of 5-HT on gastro-intestinal motor and secretory functions. This distribution implies that some 5-HT3 receptor antagonists might reduce certain symptoms of IBS, such as pain, by reducing the reactivity of the visceral afferent neurones linking the gut with the brain and spinal cord. However, such antagonists are not likely to find widespread clinical acceptance because they can also affect normal lower bowel function and promote constipation. 5-HT4 receptor antagonists, by contrast, reduce 5-HT-induced enteric nerve hypersensitivity without notably affecting the function of the normal bowel. Accordingly, these agents may reduce the symptoms of IBS directly, by reducing the incidence of defecation and diarrhoea and indirectly, by reducing both 'rebound' constipation and the post-prandial discomfort and pain associated with gastrointestinal hyper-reactivity.

Challenges in the treatment of colonic motility disorders

The pathophysiology and treatment of colonic motility disorders are reviewed. Colonic dysfunction is a common reason for patients to seek medical care, although patients' perceptions may not reflect abnormal function. Abnormalities in colonic function can result from a primary disorder of the large intestine or from metabolic, neurologic, collagen vascular, neoplastic, or infectious diseases. Irritable bowel syndrome, a common disorder of colonic motility, can be caused by alterations in colonic neuromuscular functions, afferent neural function, or psychosocial factors. Colonic dysmotility can also result from malabsorption of carbohydrates. The most severe form of altered colonic motility is acute colonic pseudo-obstruction. Diagnostic studies should be limited to tests appropriate for the patient's symptoms and apparent severity of disease. Most motility disorders are functional disorders and do not result in abnormal studies. Pharmacotherapy should be directed by objective measures, the most useful of which are measurement of whole gut transit time and quantification of the water content of stools. Treatment should be determined by the nature of the disorder and the symptoms involved. For constipation, treatment should begin with changes in diet, fluid and fiber intake, and concurrent medications. Irritant laxatives can have damaging effects and should not be used habitually; however, polyethylene glycol-based purgatives can be helpful. Newer prokinetic agents, such as cisapride, have been shown to promote colonic motility. For selected patients with intractable constipation, surgery has a good success rate. For patients with functional diarrhea, opioid analogues can increase fluid absorption and delay transit.

Symptoms of irritable bowel in school children: prevalence and psychosocial effects

INTRODUCTION

This study was to ascertain the prevalence of symptoms of irritable bowel in a sample of school children 11 to 17 years of age and to determine whether children with such symptoms differed from children without symptoms on various psychosocial questions.

METHOD

Eight hundred fifty-one school children completed a 20-item questionnaire consisting of questions related to symptoms of irritable bowel, psychosocial questions, and filler questions. Questions referred to a 1-week time frame to minimize memory distortion.

RESULTS

Of the sample, 133 (16.2%) had one or more symptoms of irritable bowel. A significant association was found between bowel symptoms and other factors. Children with symptoms were more likely to report that they felt different from other children (chi 2 analysis = 10.06, p = 0.002), were embarrassed about their health (chi 2 analysis = 16.14, p = 0.0001), and felt their health prevented them from going out with their friends (chi 2 analysis = 4.69 p = 0.03).

DISCUSSION

The study suggests that a large number of children have symptoms of irritable bowel and that having such symptoms can have a significant impact on children's lives beyond the immediate physical effects. Because children with symptoms of irritable bowel are likely to come to the attention of health professionals, nurses are in an ideal position to give such children both information and reassurance about their condition.