Selective gastric hypersensitivity and reflex hyporeactivity in functional dyspepsia

British Society of Gastroenterology guidelines on the management of functional dyspepsia

Functional dyspepsia (FD) is a common disorder of gut-brain interaction, affecting approximately 7% of individuals in the community, with most patients managed in primary care. The last British Society of Gastroenterology (BSG) guideline for the management of dyspepsia was published in 1996. In the interim, substantial advances have been made in understanding the complex pathophysiology of FD, and there has been a considerable amount of new evidence published concerning its diagnosis and classification, with the advent of the Rome IV criteria, and management. The primary aim of this guideline, commissioned by the BSG, is to review and summarise the current evidence to inform and guide clinical practice, by providing a practical framework for evidence-based diagnosis and treatment of patients. The approach to investigating the patient presenting with dyspepsia is discussed, and efficacy of drugs in FD summarised based on evidence derived from a comprehensive search of the medical literature, which was used to inform an update of a series of pairwise and network meta-analyses. Specific recommendations have been made according to the Grading of Recommendations Assessment, Development and Evaluation system. These provide both the strength of the recommendations and the overall quality of evidence. Finally, in this guideline, we consider novel treatments that are in development, as well as highlighting areas of unmet need and priorities for future research.

Altered Vagal Signaling and Its Pathophysiological Roles in Functional Dyspepsia

The vagus nerve is crucial in the bidirectional communication between the gut and the brain. It is involved in the modulation of a variety of gut and brain functions. Human studies indicate that the descending vagal signaling from the brain is impaired in functional dyspepsia. Growing evidence indicate that the vagal signaling from gut to brain may also be altered, due to the alteration of a variety of gut signals identified in this disorder. The pathophysiological roles of vagal signaling in functional dyspepsia is still largely unknown, although some studies suggested it may contribute to reduced food intake and gastric motility, increased psychological disorders and pain sensation, nausea and vomiting. Understanding the alteration in vagal signaling and its pathophysiological roles in functional dyspepsia may provide information for new potential therapeutic treatments of this disorder. In this review, we summarize and speculate possible alterations in vagal gut-to-brain and brain-to-gut signaling and the potential pathophysiological roles in functional dyspepsia.

United European Gastroenterology (UEG) and European Society for Neurogastroenterology and Motility (ESNM) consensus on functional dyspepsia

BACKGROUND

Functional dyspepsia (FD) is one of the most common conditions in clinical practice. In spite of its prevalence, FD is associated with major uncertainties in terms of its definition, underlying pathophysiology, diagnosis, treatment, and prognosis.

METHODS

A Delphi consensus was initiated with 41 experts from 22 European countries who conducted a literature summary and voting process on 87 statements. Quality of evidence was evaluated using the grading of recommendations, assessment, development, and evaluation (GRADE) criteria. Consensus (defined as >80% agreement) was reached for 36 statements.

RESULTS

The panel agreed with the definition in terms of its cardinal symptoms (early satiation, postprandial fullness, epigastric pain, and epigastric burning), its subdivision into epigastric pain syndrome and postprandial distress syndrome, and the presence of accessory symptoms (upper abdominal bloating, nausea, belching), and overlapping conditions. Also, well accepted are the female predominance of FD, its impact on quality of life and health costs, and acute gastrointestinal infections, and anxiety as risk factors. In terms of pathophysiological mechanisms, the consensus supports a role for impaired gastric accommodation, delayed gastric emptying, hypersensitivity to gastric distention, Helicobacter pylori infection, and altered central processing of signals from the gastroduodenal region. There is consensus that endoscopy is mandatory for establishing a firm diagnosis of FD, but that in primary care, patients without alarm symptoms or risk factors can be managed without endoscopy. There is consensus that H. pylori status should be determined in every patient with dyspeptic symptoms and H. pylori positive patients should receive eradication therapy. Also, proton pump inhibitor therapy is considered an effective therapy for FD, but no other treatment approach reached a consensus. The long-term prognosis and life expectancy are favorable.

CONCLUSIONS AND INFERENCES

A multinational group of European experts summarized the current state of consensus on the definition, diagnosis and management of FD.

United European Gastroenterology (UEG) and European Society for Neurogastroenterology and Motility (ESNM) consensus on functional dyspepsia

Background

Functional dyspepsia (FD) is one of the most common conditions in clinical practice. In spite of its prevalence, FD is associated with major uncertainties in terms of its definition, underlying pathophysiology, diagnosis, treatment, and prognosis.

Methods

A Delphi consensus was initiated with 41 experts from 22 European countries who conducted a literature summary and voting process on 87 statements. Quality of evidence was evaluated using the grading of recommendations, assessment, development, and evaluation (GRADE) criteria. Consensus (defined as >80% agreement) was reached for 36 statements.

Results

The panel agreed with the definition in terms of its cardinal symptoms (early satiation, postprandial fullness, epigastric pain, and epigastric burning), its subdivision into epigastric pain syndrome and postprandial distress syndrome, and the presence of accessory symptoms (upper abdominal bloating, nausea, belching), and overlapping conditions. Also, well accepted are the female predominance of FD, its impact on quality of life and health costs, and acute gastrointestinal infections, and anxiety as risk factors. In terms of pathophysiological mechanisms, the consensus supports a role for impaired gastric accommodation, delayed gastric emptying, hypersensitivity to gastric distention, Helicobacter pylori infection, and altered central processing of signals from the gastroduodenal region. There is consensus that endoscopy is mandatory for establishing a firm diagnosis of FD, but that in primary care, patients without alarm symptoms or risk factors can be managed without endoscopy. There is consensus that H. pylori status should be determined in every patient with dyspeptic symptoms and H. pylori positive patients should receive eradication therapy. Also, proton pump inhibitor therapy is considered an effective therapy for FD, but no other treatment approach reached a consensus. The long‐term prognosis and life expectancy are favorable.

Conclusions and Inferences

A multinational group of European experts summarized the current state of consensus on the definition, diagnosis and management of FD.

Current knowledge

Functional dyspepsia is one of the most common conditions encountered in clinical practice.

There is a lack of guidance for clinicians in guiding diagnosis and treatment of this prevalent condition.

No treatments are currently approved for the treatment of functional dyspepsia in Europe.

What is new here

A Delphi panel consisting of 41 experts from 22 European countries established the level of consensus on 87 statements regarding functional dyspepsia.

The statements reaching consensus serve to guide clinicians in recognizing, diagnosing and treating FD in clinical practice.

Endoscopy is mandatory for establishing a firm diagnosis of functional dyspepsia D, but in primary care patients without alarm symptoms or risk factors can be managed without endoscopy.

Helicobacter pylori status should be determined in every patient with dyspeptic symptoms and H. Pylori positive patients should receive eradication therapy.

Proton pump inhibitor‐therapy is considered an effective therapy for FD, but no other treatment approach reached consensus support.

Gastrointestinal Contributions to the Postprandial Experience

Food ingestion induces homeostatic sensations (satiety, fullness) with a hedonic dimension (satisfaction, changes in mood) that characterize the postprandial experience. Both types of sensation are secondary to intraluminal stimuli produced by the food itself, as well as to the activity of the digestive tract. Postprandial sensations also depend on the nutrient composition of the meal and on colonic fermentation of non-absorbed residues. Gastrointestinal function and the sensitivity of the digestive tract, i.e., perception of gut stimuli, are determined by inherent individual factors, e.g., sex, and can be modulated by different conditioning mechanisms. This narrative review examines the factors that determine perception of digestive stimuli and the postprandial experience.

Joint Hypermobility Syndrome in Patients With Functional Dyspepsia

INTRODUCTION:

The pathophysiology underlying functional dyspepsia (FD) is multifactorial and focuses on gastric sensorimotor dysfunction. Recent studies demonstrated that joint hypermobility syndrome (JHS) is strongly associated with unexplained dyspeptic symptoms in patients attending gastrointestinal clinics. We aimed to study the relationship between symptoms, gastric sensorimotor function, and JHS in FD patients.

METHODS:

Tertiary care FD patients who underwent a gastric barostat study and a gastric emptying breath test with 13C-octanoic acid were recruited for assessment of JHS. The presence of JHS was evaluated by a 2-phase interview and clinical examination that included major and minor criteria of the Brighton classification.

RESULTS:

A total of 62 FD patients (68% women, age 44 ± 1.8 years, and body mass index: 21.7 ± 0.7 kg/m²) accepted to participate in the study. JHS was diagnosed in 55% of FD patients. Assessed symptom profiles during the visit did not differ between the groups. Delayed gastric emptying was not significantly more common in JHS group compared with non-JHS group (JHS group 32% vs non-JHS group 16%, P = 0.31). Prevalence of hypersensitivity to distention (JHS group 24% vs non-JHS group 29%, P = 0.76) and impaired gastric accommodation (JHS group 38% vs non-JHS group 42%, P = 0.79) was similar in patients with or without JHS. No correlations were found between the Beighton hypermobility score and gastric compliance (r = 0.09).

DISCUSSION:

A large subset of this study cohort of tertiary care FD patients has coexisting JHS. We did not identify any specific differences in gastric sensorimotor function between patients with and without JHS. Further prospective research will be required to elucidate the relationship between JHS, a multisystemic disorder with widespread manifestations, and FD symptoms.

The Role of Diet in Functional Dyspepsia Management

Functional dyspepsia is a common functional gastrointestinal disease that is characterized by postprandial fullness, early satiation, epigastric pain, and/or epigastric burning. Eating a meal is a key factor in the occurrence of symptoms during functional dyspepsia, and patients frequently request dietary advice that could relieve these symptoms. Eating behaviors, irregular meal patterns, and moderate-to-fast eating rates are significantly associated with functional dyspepsia. The role of diet is complex; fat ingestion increases the occurrence of symptoms in dyspeptic patients, which might be affected by cognitive factors and palatability. Data concerning the role of carbohydrates are conflicting. Wheat may induce symptoms in patients with nonceliac gluten/wheat sensitivity, and gluten-free diets might be beneficial. Data concerning the role of FODMAPs (Fructo, Oligo, Di-, Monosaccharides, And Polyols) in functional dyspepsia are lacking; however, as there is a frequent overlap between functional dyspepsia and irritable bowel syndrome, a diet that is low in FODMAPs might be useful in relieving some symptoms. Data concerning alcohol are also conflicting. Adherence to a Mediterranean diet seems to be associated with a decrease in dyspepsia symptoms. Finally, data concerning diet modifications are conflicting, and the impact of diet modifications on symptom intensity or frequency has never been reported in randomized prospective studies. Common sense dietary recommendations, such as eating slowly and regularly, as well as decreasing the fat content of meals, can be provided in daily clinical practice.

The Diagnosis and Treatment of Functional Dyspepsia

BACKGROUND

Functional dyspepsia (FD) is one of the more common functional disorders, with a prevalence of 10-20%. It affectsthe gastrointestinal tract.

METHODS

This article is based on publications retrieved by a selective search of PubMed, with special attention to controlled trials, guidelines, and reviews.

RESULTS

Typical dyspeptic symptoms in functional dyspepsia include epigastric pain, sensations of pressure and fullness, nausea, and early subjective satiety. The etiology of the disorder is heterogeneous and multifactorial. Contributory causes include motility disturbances, visceral hypersensitivity, elevated mucosal permeability, and disturbances of the autonomic and enteric nervous system. There is as yet no causally directed treatment for functional dyspepsia. Its treatment should begin with intensive patient education regarding the benign nature of the disorder and with the establishment of a therapeutic pact for long-term care. Given the absence of a causally directed treatment, drugs to treat functional dyspepsia should be given for no more than 8-12 weeks. Proton-pump inhibitors, phytotherapeutic drugs, and Helicobacter pylori eradication are evidence-based interventions. For intractable cases, tricyclic antidepressants and psychotherapy are further effective treatment options.

CONCLUSION

The impaired quality of life of patients with functional dyspepsia implies the need for definitive establishment of the diagnosis, followed by symptom-oriented treatment for the duration of the symptomatic interval.

Association between delayed gastric emptying and upper gastrointestinal symptoms: a systematic review and meta-analysis

BACKGROUND

The relationship between delayed gastric emptying and upper GI symptoms (UGI Sx) is controversial.

OBJECTIVE

To assess association between gastric emptying and UGI Sx, independent of treatment.

DESIGN

We performed a systematic review and meta-analysis of the literature from 2007 to 2017, review of references and additional papers identified by content expert. We included studies evaluating the association between gastric emptying and nausea, vomiting, early satiety/postprandial fullness, abdominal pain and bloating. Covariate analyses included optimal gastric emptying test method, gastric emptying type (breath test or scintigraphy) and patient category. Meta-regression compared the differences based on type of gastric emptying tests.

RESULTS

Systematic review included 92 gastric emptying studies (26 breath test, 62 scintigraphy, 1 ultrasound and 3 wireless motility capsule); 25 of these studies provided quantitative data for meta-analysis (15 scintigraphy studies enrolling 4056 participants and 10 breath test studies enrolling 2231 participants). Meta-regression demonstrated a significant difference between optimal and suboptimal gastric emptying test methods when comparing delayed gastric emptying with nausea and vomiting. On evaluating studies using optimal gastric emptying test methodology, there were significant associations between gastric emptying and nausea (OR 1.6, 95% CI 1.4 to 1.8), vomiting (OR 2.0, 95% CI 1.6 to 2.7), abdominal pain (OR 1.5, 95% CI 1.0 to 2.2) and early satiety/fullness (OR 1.8, 95% CI 1.2 to 2.6) for patients with UGI Sx; gastric emptying and early satiety/fullness in patients with diabetes; gastric emptying and nausea in patients with gastroparesis.

CONCLUSIONS

The systematic review and meta-analysis supports an association between optimally measured delayed gastric emptying and UGI Sx.

DA-9701 (Motilitone): A Multi-Targeting Botanical Drug for the Treatment of Functional Dyspepsia

Functional dyspepsia (FD) is the most common functional gastrointestinal disorder (FGID). FD is characterized by bothersome symptoms such as postprandial fullness, early satiety, and epigastric pain or burning sensations in the upper abdomen. The complexity and heterogeneity of FD pathophysiology, which involves multiple mechanisms, make both treatment and new drug development for FD difficult. Current medicines for FD targeting a single pathway have failed to show satisfactory efficacy and safety. On the other hand, multicomponent herbal medicines that act on multiple targets may be a promising alternative treatment for FD. DA-9701 (Motilitone), a botanical drug consisting of Corydalis Tuber and Pharbitidis Semen, has been prescribed for FD since it was launched in Korea in 2011. It has multiple mechanisms of action such as prokinetic effects, fundus relaxation, and visceral analgesia, which are mediated by dopamine D₂ and several serotonin receptors involved in gastrointestinal (GI) functions. In clinical studies, DA-9701 has been found to be beneficial for improvement of FD symptoms and GI functions in FD patients, while showing better safety compared to that associated with conventional medicines. In this review, we provide updated information on the pharmacological effects, safety, and clinical results of DA-9701 for the treatment of FGIDs.

Definition, Pathogenesis, and Management of That Cursed Dyspepsia

Dyspepsia is an umbrella term used to encompass a number of symptoms thought to originate from the upper gastrointestinal tract. These symptoms are relatively nonspecific; not surprisingly, therefore, a myriad of conditions may present with any one or a combination of these symptoms. Therein lays the clinician's first challenge: detecting the minority who may have a potentially life-threatening disorder, such as gastric cancer, from a population whose symptoms are, for the most part, considered functional in origin. The second challenge lies in the definition and management of those individuals with functional dyspepsia (FD); the major focus of this review. The Rome process has addressed the issue of FD definition and a look back at the evolution of Rome criteria for this disorder illustrates the complexities that have so frustrated us. There has been no shortage of hypotheses to explain symptom pathogenesis in FD; initially focused on gastric sensorimotor dysfunction, these have now strayed well into the duodenum and have come to entertain such factors as immune responses and the microbiome. FD has proven to be an equally challenging area for therapeutics; while the staple approaches of acid suppression and eradication of Helicobacter pylori have some limited efficacy in select populations, strategies to ameliorate symptoms in the majority of sufferers based on presumed pathophysiology have largely foundered. Lacking a validated biomarker(s) FD continues to be an elusive target and is likely to remain so until we can better define the various phenotypes that it must surely contain.

Bidirectional brain-gut interactions: Involvement of noradrenergic transmission within the ventral part of the bed nucleus of the stria terminalis

Introduction

Although the important roles of bidirectional interactions between the brain and gut in stress and emotional responses have long been recognized, the underlying neuronal mechanisms remain unclear. The bed nucleus of the stria terminalis (BNST) is a limbic structure involved in stress responses and negative affective states, such as anxiety and depression. We have previously demonstrated that noradrenergic transmission within the ventral part of the BNST (vBNST) plays a crucial role in anxiety‐like behaviors and pain‐induced aversion.

Objectives

This study aimed to examine the involvement of noradrenergic transmission via β‐adrenoceptors within the vBNST in bidirectional brain‐gut interactions.

Methods

We measured the gastric distention (GD)‐induced noradrenaline release within the vBNST of freely moving rats using an in vivo microdialysis technique. Gastric emptying and intestinal transit were examined following intra‐vBNST injections of isoproterenol, a β‐adrenoceptor agonist, in the absence or presence of the coadministration of timolol, a β‐adrenoceptor antagonist.

Results

Gastric distention at a higher pressure (45 mm Hg) but not at a lower pressure (25 mm Hg) resulted in a significant increase in extracellular noradrenaline levels within the vBNST. Intra‐vBNST injections of isoproterenol (30 nmol/side) induced significant reductions in gastric emptying and small intestinal transit, both of which were reversed by the coadministration of timolol (30 nmol/side).

Conclusion

Noradrenergic transmission via β‐adrenoceptors within the vBNST was involved in bidirectional brain‐gut interactions. These findings suggest that gastric dysfunction may induce negative affective states via the enhanced release of noradrenaline within the vBNST which, in turn, may cause gastrointestinal impairments.

In vivo microdialysis experiments demonstrated that gastric distention induced an increase in noradrenaline release within the vBNST. Intra‐vBNST injections of isoproterenol, a β‐adrenoceptor agonist, reduced gastric emptying and small intestinal transit, and these reducing effects were reversed by the coadministration of timolol, a β‐adrenoceptor antagonist. The present findings demonstrated important roles of noradrenergic transmission via β‐adrenoceptors within the vBNST in the bidirectional brain‐gut interactions.

Functional dyspepsia

Functional dyspepsia is one of the most prevalent functional gastrointestinal disorders. Functional dyspepsia comprises three subtypes with presumed different pathophysiology and aetiology: postprandial distress syndrome (PDS), epigastric pain syndrome (EPS) and a subtype with overlapping PDS and EPS features. Functional dyspepsia symptoms can be caused by disturbed gastric motility (for example, inadequate fundic accommodation or delayed gastric emptying), gastric sensation (for example, sensations associated with hypersensitivity to gas and bloating) or gastric and duodenal inflammation. A genetic predisposition is probable but less evident than in other functional gastrointestinal disorders, such as irritable bowel syndrome (IBS). Psychiatric comorbidity and psychopathological state and trait characteristics could also play a part, although they are not specific to functional dyspepsia and are less pronounced than in IBS. Possible differential diagnoses include Helicobacter pylori infection and peptic ulceration. Pharmacological therapy is mostly based on the subtype of functional dyspepsia, such as prokinetic and fundus-relaxing drugs for PDS and acid-suppressive drugs for EPS, whereas centrally active neuromodulators and herbal drugs play a minor part. Psychotherapy is effective only in a small subset of patients, whereas quality of life can be severely affected in nearly all patients. Future therapies might include novel compounds that attempt to treat the underlying gastric and duodenal inflammation.

Upper GI Disorders: Pathophysiology and Current Therapeutic Approaches

Symptoms referable to the upper digestive tract are associated with abnormalities of upper gastric neuromuscular function including abnormalities of motility, sensation, and absorption. Of the upper digestive tract, the stomach is of particular importance in its role in symptom generation and is highlighted in this chapter. Gastric symptoms can be associated with alterations in the rates of gastric emptying, impaired accommodation, heightened gastric sensation, or alterations in gastric myoelectrical activity and contractility. Treatment of gastric neuromuscular disorders requires an understanding of pathophysiology of the disorders, the appropriate use and interpretation of diagnostic tests, and the knowledge of effective treatment options. This chapter covers the pathophysiology and current treatment approaches to disorders of the upper gastrointestinal tract, focusing on classic disorders of the stomach, particularly gastroparesis and functional dyspepsia.

Fundamentals of Neurogastroenterology: Physiology/Motility - Sensation

The fundamental gastrointestinal functions include motility, sensation, absorption, secretion, digestion and intestinal barrier function. Digestion of food and absorption of nutrients normally occurs without conscious perception. Symptoms of functional gastrointestinal disorders are often triggered by meal intake suggesting abnormalities in the physiological processes are involved in the generation of symptoms. In this manuscript, normal physiology and pathophysiology of gastrointestinal function, and the processes underlying symptom generation are critically reviewed. The functions of each anatomical region of the digestive tract are summarized. The pathophysiology of perception, motility, mucosal barrier, and secretion in functional gastrointestinal disorders as well as effects of food, meal intake and microbiota on gastrointestinal motility and sensation are discussed. Genetic mechanisms associated with visceral pain and motor functions in health and functional gastrointestinal disorders are reviewed. Understanding the basis for digestive tract functions is essential to understand dysfunctions in the functional gastrointestinal disorders.

Impact of Overlapping Functional Gastrointestinal Disorders on the Presentation and Quality of Life of Patients with Erosive Esophagitis and Nonerosive Reflux Disease

OBJECTIVE

The aim of this study was to investigate the impact of overlapping functional gastrointestinal disorder (FGID) on the quality of life of patients with nonerosive reflux disease (NERD) and erosive esophagitis (EE).

MATERIALS AND METHODS

Data from patients with NERD and EE were collected between January 2009 and March 2010. These cases were further stratified into the subgroups of overlapping NERD-functional dyspepsia (FD), NERD-irritable bowel syndrome (IBS), EE-FD, EE-IBS, and NERD or EE alone according to the symptoms. All patients completed the modified Chinese GERDQ and the SF-36 questionnaires.

RESULTS

Of the 222 enrolled patients, 96 (43.2%) had NERD and 126 (56.8%) had EE. Overlap of FGID occurred in 43.8-45.8% of the NERD patients, and in 41.3-44.4% of EE cases. The impact of overlapping FGID on patient quality of life was greater in the patients with overlapping NERD-FD compared to those with NERD alone (mean SF-36 total scores 59 vs. 72, adjusted p = 0.025) and the cases with overlapping EE-FD compared to those with EE alone (mean SF-36 total scores 53.19 vs. 73.11, adjusted p = 0.047). There were no significant differences between the individuals with overlapping NERD/EE-IBS and those with NERD/EE alone.

CONCLUSIONS

There was a high prevalence of overlapping FGID, with both FD and IBS, among the GERD patients. The individuals with overlapping GERD and FD had lower quality of life scores than those with GERD alone.

Change in DNA methylation patterns of SLC6A4 gene in the gastric mucosa in functional dyspepsia

Background

The neurochemical serotonin (5-HT) is an important signaling molecule in the gastrointestinal motor and sensory functions. A key regulator of 5-HT levels is the transmembrane serotonin transporter (5-HTT; SLC6A4) that governs the reuptake of 5-HT. Recent studies have indicated 5-HTT expression may be regulated by epigenetic mechanisms. We investigated DNA methylation status of SLC6A4 gene in the gastric mucosa from functional dyspepsia (FD) because of their potential role in dyspeptic symptoms.

Methods

Endoscopic gastric biopsies were obtained from 78 subjects with no upper abdominal symptoms and 79 patients with FD. Bisulfite Pyrosequencing was carried out to determine the methylation status of promoter CpG islands (PCGIs), promoter non-CpG islands (PNCGIs) and gene body non-CpG islands (NPNCGIs) in the SLC6A4 gene. Gene expression was examined by real-time PCR.

Results

In overall, methylation level of PCGIs was significantly lower in FD compared to control subjects (p = 0.04). On the other hand, methylation level of NPNCGIs was significantly higher in FD compared to control subjects (p = 0.03). Lower methylation level in PNCGIs was highlighted in the patients with PDS (p = 0.01), while higher methylation level in NPNCGIs was more prominent in the patients with EPS (p = 0.017). Methylation levels of PCGIs and PNCGIs were inversely correlated, while methylation levels of NPNCGIs was positively correlated with SLC6A4 mRNA levels in FD patients.

Conclusions

Our data suggest that change in DNA methylation pattern of SLC6A4 in the gastric mucosa may have a role for developing FD. A role of epigenetics for developing FD needs to be further evaluated.

Mechanisms of postprandial abdominal bloating and distension in functional dyspepsia

OBJECTIVE

Patients with irritable bowel syndrome and abdominal bloating exhibit abnormal responses of the abdominal wall to colonic gas loads. We hypothesised that in patients with postprandial bloating, ingestion of a meal triggers comparable abdominal wall dyssynergia. Our aim was to characterise abdominal accommodation to a meal in patients with postprandial bloating.

DESIGN

A test meal (0.8 kcal/ml nutrients plus 27 g/litre polyethylenglycol 4000) was administered at 50 ml/min as long as tolerated in 10 patients with postprandial bloating (fulfilling Rome III criteria for postprandial distress syndrome) and 12 healthy subjects, while electromyographic (EMG) responses of the anterior wall (upper and lower rectus, external and internal oblique via bipolar surface electrodes) and the diaphragm (via six ring electrodes over an oesophageal tube in the hiatus) were measured. Means +/- SD were calculated.

RESULTS

Healthy subjects tolerated a meal volume of 913±308 ml; normal abdominal wall accommodation to the meal consisted of diaphragmatic relaxation (EMG activity decreased by 15±6%) and a compensatory contraction (25±9% increase) of the upper abdominal wall muscles (upper rectus and external oblique), with no changes in the lower anterior muscles (lower rectus and internal oblique). Patients tolerated lower volume loads (604±310 ml; p=0.030 vs healthy subjects) and developed a paradoxical response, that is, diaphragmatic contraction (14±3% EMG increment; p<0.01 vs healthy subjects) and upper anterior wall relaxation (9±4% inhibition; p<0.01 vs healthy subjects).

CONCLUSIONS

In functional dyspepsia, postprandial abdominal distension is produced by an abnormal viscerosomatic response to meal ingestion that alters normal abdominal accommodation.

Gastric sensitivity and reflexes: basic mechanisms underlying clinical problems

Both reflex and sensory mechanisms control the function of the stomach, and disturbances in these mechanisms may explain the pathophysiology of disorders of gastric function. The objective of this report is to perform a literature-based critical analysis of new, relevant or conflicting information on gastric sensitivity and reflexes, with particular emphasis on the comprehensive integration of basic and clinical research data. The stomach exerts both phasic and tonic muscular (contractile and relaxatory) activity. Gastric tone determines the capacity of the stomach and mediates both gastric accommodation to a meal as well as gastric emptying, by partial relaxation or progressive recontraction, respectively. Perception and reflex afferent pathways from the stomach are activated independently by specific stimuli, suggesting that the terminal nerve endings operate as specialized receptors. Particularly, perception appears to be related to stimulation of tension receptors, while the existence of volume receptors in the stomach is uncertain. Reliable techniques have been developed to measure gastric perception and reflexes both in experimental and clinical conditions, and have facilitated the identification of abnormal responses in patients with gastric disorders. Gastroparesis is characterised by impaired gastric tone and contractility, whereas patients with functional dyspepsia have impaired accommodation, associated with antral distention and increased gastric sensitivity. An integrated view of fragmented knowledge allows the design of pathophysiological models in an attempt to explain disorders of gastric function, and may facilitate the development of mechanistically orientated treatments.

Dietary and lifestyle factors in functional dyspepsia

Dietary factors are increasingly recognized to have an important role in triggering symptoms in a large proportion of patients with functional dyspepsia. Fatty foods seem to be the main culprits, but other foods (including carbohydrate-containing foods, milk and dairy products, citrus fruits, spicy foods, coffee and alcohol) have also been implicated. However, blind challenge tests do not provide consistent results. Moreover, although patients identify specific foods as triggers of their symptoms, these patients often do not seem to make behavioural adjustments in an attempt to improve symptoms; that is, any differences in dietary intake and lifestyle between patients and healthy individuals are small. Patients with functional dyspepsia exhibit mixed sensory-motor abnormalities, such as gastric hypersensitivity and impaired gastric accommodation of a meal. Nutrients, particularly fat, exacerbate these abnormalities and might thereby trigger postprandial symptoms. Cognitive factors, including anticipation related to previous negative experience with certain foods, might also have a role in triggering symptoms. Studies evaluating the potential beneficial effect of dietary interventions and changes in lifestyle are lacking, and this Review outlines a number of options that could be used as starting points for meaningful large-scale studies in the future.

G-Protein Beta3 Subunit C825T Polymorphism in Patients With Overlap Syndrome of Functional Dyspepsia and Irritable Bowel Syndrome

Background/Aims

Guanine nucleotide binding protein (G-protein) beta polypeptide 3 (GNB3) C825T polymorphism alters intracellular signal transduction, which may lead to motor or sensory abnormalities of the gastrointestinal tract. The aim of the present study was to evaluate the association of the GNB3 C825T polymorphism with susceptibility to overlap syndrome of functional dyspepsia (FD) and irritable bowel syndrome (IBS) in a Korean population.

Methods

One hundred sixty-seven patients with FD alone, 60 patients with IBS alone, 85 patients with the overlap of FD and IBS, and 434 asymptomatic healthy subjects participated in the study. Genotyping for GNB3 C825T polymorphism was performed using their blood samples.

Results

No association of GNB3 genotypes in patients with FD alone, IBS alone or overlap phenotype, when compared to genotypes in controls, was detected. The frequency of CT and TT genotypes relative to the CC genotype for the phenotypes of FD alone, IBS alone and the coexistence of FD and IBS did not significantly differ. Comparison of the TT genotype with the CC/CT genotype showed no significant association for each phenotype group.

Conclusions

There is no apparent association of the GNB3 C825T polymorphism with the susceptibility to FD, IBS or the overlap of FD and IBS. Larger-scale studies and further investigation on other candidate genes are required.

The dopaminergic system in patients with functional dyspepsia analysed by single photon emission computed tomography (SPECT) and an alpha-methyl-para-tyrosine (AMPT) challenge test

Purpose

Functional dyspepsia (FD) is a chronic condition characterized by upper abdominal symptoms without an identifiable cause. While the serotonergic system is thought to play a key role in the regulation of gut physiology, the role of the dopaminergic system, which is important in the regulation of visceral pain and stress, is under-studied. Therefore, this study investigated the dopaminergic system and its relationship with drinking capacity and symptoms in FD patients.

Methods

In FD patients and healthy volunteers (HV) the dopaminergic system was investigated by in-vivo assessment of central dopamine D2 receptors (D2Rs) with [¹²³I]IBZM SPECT and by an acute, but reversible, dopamine depletion alpha-methyl-para-tyrosine (AMPT) challenge test. A nutrient drink test was performed to investigate the association between maximal ingested volume, evoked symptoms, and D2Rs.

Results

The HV subjects comprised 12 women and 8 men (mean age 31 ± 3 years), and the FD patients comprised 5 women and 3 men (mean age 39 ± 5 years). The FD patients had a lower left plus right average striatal binding potential (BP_NP) for the caudate nucleus (p = 0.02), but not for putamen (p = 0.15), which in the FD patients was correlated with maximal ingested volume (r = 0.756, p = 0.03). The D2R BP_NP in the putamen was correlated with nausea (r = 0.857, p = 0.01). The acute dopamine depletion test, however, failed to reveal differences in prolactin release between the FD patients and the HV subjects.

Conclusion

These preliminary data suggest that chronic rather than acute alterations in the dopaminergic system may be involved in the pathogenesis of FD. Further studies are required to reproduce our novel findings and to evaluate to what extent the dopaminergic changes may be secondary to abnormalities in serotonergic pathways.

Electronic supplementary material

The online version of this article (doi:10.1007/s00259-011-2015-6) contains supplementary material, which is available to authorized users.

Functional Gastrointestinal Disorders Diagnosed by Rome III Questionnaire in Korea

Background/Aims

Rome criteria classifying functional gastrointestinal disorder (FGID) were updated. The aims of this study were to assess the spectra of FGID and to evaluate the applicability of Rome III criteria in Korea.

Methods

New patients who visited 2 primary clinics and 2 tertiary care hospitals were consecutively invited to complete questionnaires. These consisted of questionnaires for FGID based on Rome III criteria and symptom checklist-90-revised for somatization, depression and anxiety.

Results

A total of 786 patients was participated. Among them, FGID was observed in 49.7%. In the patients with FGID, functional dyspepsia was most common (46.0%) followed by irritable bowel syndrome (IBS, 40.2%). Functional dyspepsia was most common both in the primary care clinics and tertiary care hospitals. Postprandial distress syndrome was the most common subtype and the frequency of epigastric pain syndrome was low. There were few responders for constipation as Bristol types 1 and 2 and for diarrhea as types 6 and 7 in subtype classification using the Bristol Stool Form Scale. Thereby, unspecified IBS defined by stool form was unexpectedly common in 43.9% of IBS, whereas unspedified IBS defined by Rome III definition was 5.1%. Patients with overlap FGIDs had higher score of anxiety, depression or somatization.

Conclusions

FGIDs were common both in primary care clinics and tertiary care hospitals of Korea. Overlap FGIDs is still common by Rome III criteria, which may limits its wide application.

The dysfunctional gut

After many decades debating whether the clinical manifestations of patients with functional digestive symptoms originate "in their minds" or "in their guts," arguments remain strong on both sides of the controversy. However, advances in understanding of gut physiology and pathophysiology, and persuasive evidence on the bidirectionality of the regulatory traffic between the enteric and central nervous systems, are helping to characterize clinical situations in which we can legitimately speak of gut dysfunction, as opposed to others where symptoms are not associated with apparent or detectable gut disturbances and may truly represent somatization of an affective disorder. In this review, we describe available clinically applicable technology, albeit in specialized clinical research units, that may be used to discern whether or not challenging patients have gut sensory or motor disturbances. The practical yield of applying such methods to diagnostic investigation may be substantial, because it establishes a plausible mechanism of disease that may be used in patient management and patient persuasion, to remove uncertainties and to prevent futile repetition of conventional diagnostic tests. By evolving from symptom analysis to mechanism-based diagnosis, our gastroenterology community may progress toward the goal of delivering the full diagnostic spectrum from altered morphology to disturbed function.

Overlap of Erosive and Non-erosive Reflux Diseases With Functional Gastrointestinal Disorders According to Rome III Criteria

Background/Aims

Gastroesophageal reflux disease (GERD) is increasing in Asian countries. Functional dyspepsia (FD) or irritable bowel syndrome (IBS) are also prevalent and commonly overlapped with GERD. This study was conducted to compare the proportion and risk factors for overlapping reflux esophagitis (RE) and non-erosive reflux disease (NERD) with functional gastrointestinal disorders (FGIDs).

Methods

A total of 2,388 [male, 55.9%; mean age (± SD), 43.2 years (± 8.4)] Korean subjects who underwent the upper endoscopy for health screening were prospectively included. The subjects were asked about demographic, medical and social history by using a structured questionnaire, and FD and IBS were assessed according to the Rome III criteria.

Results

The subjects with RE were 286 (12.0%, male 88.5%, 42.8 years) and 74 subjects had NERD (3.1%) while the prevalence of FD and IBS were 8.1% and 10.1%, respectively. The proportion of FD and IBS in NERD was higher than that of RE (74.3% vs. 10.5%, p = 0.000; 41.9% vs. 11.2%, p = 0.000, respectively). The epigastric pain syndrome (EPS) was more prevalent than postprandial distress syndrome in NERD. According to multiple regression analysis, high somatization score and the presence of FD increased the odd ratio for NERD. However, male gender and current smoker were significant risk factors for RE.

Conclusions

Compared to RE, NERD is more frequently overlapped with FD, especially EPS, and also are associated with significantly increased frequency of IBS. Our data draws attention to the possibility of subgrouping FGIDs and GERD to be important in understanding the pathophysiology of these conditions.

Relationship between symptom pattern, assessed by the PAGI-SYM questionnaire, and gastric sensorimotor dysfunction in functional dyspepsia

The patient assessment of upper gastrointestinal symptom severity index (PAGI-SYM) questionnaire was recently developed and validated for the evaluation of therapeutic responsiveness in functional dyspepsia (FD). Functional dyspepsia is a heterogeneous disorder, with different pathophysiological mechanisms underlying the symptom pattern. The relationship between PAGI-SYM scores and putative pathophysiological mechanisms has not been studied. The aim of this study was to evaluate the relationship between PAGI-SYM subscales and gastric emptying, gastric sensitivity and gastric accommodation in FD. A total of 161 consecutive FD patients underwent Helicobacter pylori (HP), gastric barostat and standardized gastric emptying testing (n = 126), and completed the PAGI-SYM questionnaire. Relationships between scores for the six subscales (heartburn/regurgitation, nausea/vomiting, fullness/satiety, bloating, upper abdominal pain, lower abdominal pain) and gastric function were analysed using Pearson's linear correlation, multiple regression analysis, chi-square and Student's t-tests. Gastric emptying was significantly correlated with scores for heartburn/regurgitation (r = 0.26), nausea/vomiting (r = 0.19), fullness/satiety (r = 0.20), bloating (r = 0.21) and lower abdominal pain (r = 0.22; all P < 0.05). Patients with delayed emptying had significantly higher scores for each of these subscales (all P < 0.05). Discomfort volume during gastric distension was significantly correlated with scores for fullness/satiety (r = -0.27), bloating (r = -0.23), heartburn/regurgitation (r = -0.21), and upper abdominal pain (r = -0.20). Patients with hypersensitivity to distension had significantly higher scores for fullness/satiety (P < 0.05). At different cut-off levels of symptom severities, consistent associations were found between fullness/satiety and gastric discomfort volume, between preprandial volumes and upper abdominal pain, compliance and upper abdominal pain, and between bloating and gastric discomfort volume. Multiple regression analysis revealed that gastric emptying rate contributed significantly to models for the severity of these subscales. The importance of discomfort volume disappeared in favour of gender when sex was included in the model. No significant correlations were found with HP status or with gastric accommodation. PAGI-SYM scores are mainly correlated with gastric emptying rate and with gastric hypersensitivity. Multivariate analysis suggests that the questionnaire may be useful in the evaluation of gastroprokinetics. Its role in the evaluation of drugs that alter gastric sensitivity is less clear.

Whither dyspepsia? A historical perspective of functional dyspepsia, and concepts of pathogenesis and therapy in 2009

Functional dyspepsia is a highly prevalent but heterogeneous disorder; multiple pathogenetic mechanisms are likely involved but the underlying causal pathways in functional dyspepsia remain obscure. The term functional dyspepsia was popularized by the famed Walter Alvarez at the Mayo Clinic early last century. Prominent Australian gastroenterologists who have contributed to our understanding of functional dyspepsia include Peter Baume, Barry Marshall, Douglas Piper, Nick Talley, John Kellow, and Gerald Holtmann. Specific dyspeptic symptoms have not generally correlated very well with any particular physiologic disturbance, although gastric disaccommodation and duodenal eosinophilia have been linked to early satiety in this condition. Genetic markers have been tentatively identified, and functional dyspepsia can follow bacterial gastroenteritis. No objective diagnostic tools for functional dyspepsia are currently agreed upon, although meal induction of symptoms appears reproducible and may have diagnostic utility. The symptomatic criteria for functional dyspepsia (Rome III criteria) are based on expert consensus and the exclusion of organic causes. Various therapeutic modalities for functional dyspepsia have been explored; however, empirical approaches are still employed for the treatment of functional dyspepsia. Better approaches for functional dyspepsia are likely to follow an improved understanding of the underlying pathophysiological abnormalities.

Visceral sensitivity testing

Visceral hypersensitivity is regarded as an important factor in the pathogenesis of functional gastrointestinal disorders. Assessment of visceral sensitivity has several important aims: increasing the understanding of normal and abnormal visceral sensory mechanisms and participating sensory pathways, serving as diagnostic tool to detect patients with abnormal visceral sensitivity, and evaluating therapeutic interventions directed towards modification of visceral sensitivity. Current stimulation modes in sensitivity tests include mechanical distension by barostat or tensostat, nutrient drink or water load, chemical stimulation, e.g. acid provocation or capsaicin ingestion, electrical, or thermal stimulation. Multimodal probes incorporating several stimulation modes in one device have recently been developed. Assessment of visceral sensation can be based on subjective responses of conscious perception or on objective parameters such as visceromotoric responses or central sensory processing patterns. All methods face the challenge that visceral sensitivity may be influenced by a wide spectrum of different factors, including the test techniques themselves, and improved, preferably non-invasive sensitivity tests with a greater standardisation and a broader applicability are still needed.

Clinical effects of STW 5 (Iberogast) are not based on acceleration of gastric emptying in patients with functional dyspepsia and gastroparesis

STW 5, a herbal extract, is effective for the treatment of symptoms in patients with functional dyspepsia (FD). However, its mode of action is still unclear and a modulation of gastric motility is hypothesized. This multicentre, placebo-controlled double-blind study addressed the question of whether STW 5 accelerates gastric emptying in patients with FD and gastroparesis. One-hundred and three patients diagnosed with FD were randomly assigned to a treatment with either STW 5 or a liquid placebo for 28 days. The primary end point of the study was a change of a validated gastrointestinal symptom (GIS) score under treatment. Additionally, patients underwent a (13)C octanoic acid breath test for the assessment of the gastric half-emptying time (t(1/2)). Patients with prolonged t(1/2) were diagnosed with gastroparesis and requested to repeat the test at the end of treatment. A change of t(1/2) was defined a secondary study end point. t(1/2) was prolonged in 48.6% of patients in the STW 5 group and in 43.8% of the placebo group. During treatment, t(1/2) increased non-significantly in patients treated with STW 5 (+23 +/- 109 min; P = 0.51) and slightly accelerated among patients in the placebo arm (-26 +/- 51 min; P = 0.77) (P = 0.49). The improvement of the GIS (P = 0.08) and the proportion of patients with a treatment response (P = 0.03) were more pronounced in the STW 5 group. Our findings suggest that the clinical effects of STW 5 in patients with FD and gastroparesis are not directly mediated by an acceleration of gastric emptying. A clear-cut correlation with symptom improvement is still lacking.

Relation between clinical symptoms and experimental visceral hypersensitivity in pediatric patients with functional abdominal pain

OBJECTIVE

The association between clinical symptoms and laboratory visceral sensitivity remains poorly defined and controversial. It has even been suggested that laboratory observations of visceral sensitivity are irrelevant to the clinical presentation of chronic visceral pain. To better understand this association, gastrointestinal and psychological features of pediatric patients' clinical presentation were examined in relation to a laboratory-based measure of visceral sensitivity.

PATIENTS AND METHODS

At the time of their medical evaluation, 101 patients with medically unexplained abdominal pain (ages 8-15 years) completed validated questionnaires assessing recent depressive symptoms, functional disability, pain efficacy beliefs, gastrointestinal (GI), and non-GI symptoms. These clinical features were examined in relation to visceral sensitivity assessed 2 months later in the laboratory. The measure of visceral sensitivity was based on increases in GI complaints in response to the water load symptom provocation task.

RESULTS

More severe GI symptoms and functional disability in the weeks before patients' clinical evaluation were associated with significantly greater increases in GI symptoms in the laboratory in response to the water load symptom provocation task (all P < 0.04). Patients believing that they had the ability to alleviate their pain (high problem-focused pain efficacy) had significantly lower laboratory visceral sensitivity (P < 0.01). Clinical depressive symptoms and non-GI symptoms were not associated with laboratory visceral sensitivity.

CONCLUSIONS

Clinical presentations of more severe GI symptoms and disability as well as low perceived pain efficacy are significant predictors of laboratory visceral sensitivity in children with functional abdominal pain. Depression does not account for the association between clinical presentation of GI symptoms and a laboratory measure of visceral sensitivity.

Association of endoscopic appearances with dyspeptic symptoms

BACKGROUND

The relationship between endoscopic appearances such as endoscopic gastritis and duodenitis and dyspeptic symptoms has not been clearly demonstrated. We aimed to clarify the association of endoscopic appearances with Helicobacter pylori infection, histological severity of gastritis, and dyspeptic symptoms in a Japanese population.

METHODS

We enrolled 87 dyspeptic and 93 nondyspeptic subjects in this study. All subjects underwent gastroscopy, and patients with active peptic ulcer disease, reflex esophagitis with erosion, polyps >1 cm, or cancer were excluded. Endoscopic appearances in patients with dyspeptic symptoms and in those without were assessed retrospectively on the basis of endoscopic images. The degree of atrophy by the Kimura-Takemoto classification system was also assessed. Helicobacter pylori infection status was examined by histology or antibody against H. pylori. Histological severity of inflammation and glandular atrophy in the antrum were assessed according to the updated Sydney System. The odds ratio (OR) and 95% confidence interval (CI) were calculated by logistic regression using the variables age, sex, H. pylori infection status, and all endoscopic appearances.

RESULTS

The degree of atrophy tended to be lower among dyspeptic patients (P = 0.06). Among all endoscopic appearances, the liner redness (friability) in the antrum (OR = 3.90, 95% CI = 1.20-12.64) and duodenal ulcer (DU) scarring (OR = 3.41, 95% CI = 1.08-10.79) were independently associated with dyspepsia. Histological severity of inflammation and glandular atrophy were not associated with dyspeptic symptoms. Also, no correlation was found between endoscopic appearances and any of the different subgroups of dyspeptic symptoms. Patients with friability in the antrum and DU scar, which correlated with dyspeptic symptom showed some of communal symptoms such as epigastric pain, epigastric discomfort, hypochondriac pain, early satiation/postprandial fullness, and belching, but they differed considerably with respect to H. pylori positivity and the histological severity of gastritis.

CONCLUSIONS

Some endoscopic appearances such as friability in the antrum and DU scarring may be associated with dyspeptic symptoms, and endoscopic appearances may be useful markers to perform clinical implementation reflecting an individual's pathophysiology of dyspeptic symptoms.

Reproducibility and symptomatic predictors of a slow nutrient drinking test in health and in functional dyspepsia

Impaired accommodation to a meal has been recognized as a pathophysiological mechanism in functional dyspepsia (FD). Based on observations in tertiary care patients, the drinking test has been proposed as a non-invasive tool to estimate accommodation. Our aim was to assess the reproducibility of the drinking test and its correlation with demographic, symptomatic and pathophysiological parameters in secondary care FD patients and healthy controls. Thirty-four healthy controls and 78 FD patients completed a drinking test (3 respectively 2 times), a gastric emptying study and an FD symptom questionnaire. Factors influencing maximal volume and gastric emptying were determined, and the reproducibility of the drinking test was investigated. The maximal satiety was reached at a lower volume in patients (489 +/- 276 and 503 +/- 248 mL for first and second test respectively vs 937 +/- 428 and 1048 +/- 421 mL, P < 0.0001). The ingested amount depended on age, sex and baseline FD symptom score. Patients' sex, final satiety score, total score for stomach complaints at screening and total symptom score before test accounted for the total symptom score after the test. The slow nutrient drinking test confirms its possible role as an attractive non-invasive and reproducible tool for the diagnosis of impaired accommodation and for the assessment of treatment responsiveness.

Homozygous 825T allele of the GNB3 protein influences the susceptibility of Japanese to dyspepsia

The role of genetics in the susceptibility to functional dyspepsia (FD) is not well established. Recently, two different associations were reported between FD and G-protein beta3 (GNB3) subunit gene polymorphism. We aim to clarify the association between GNB3 protein C825T polymorphism and dyspepsia in the Japanese population. Eight-nine dyspeptics and 94 nondyspeptic subjects enrolled in this study. All subjects underwent gastroscopy and patients with significant upper gastrointestinal findings were excluded. Other diseases were also excluded by face-to-face history and physical examination. GNB3 protein C825T polymorphisms were determined by polymerase chain reaction-restriction fragment-length polymorphism. H. pylori infection status was examined by histology or antibody against H. pylori. Nonsignificant correlation was found between GNB3 protein homozygous 825T and unexplained dyspepsia (OR = 1.65, 95% CI: 0.87-3.13). However, among H. pylori-negative subjects, homozygous GNB3 protein 825T significantly increased the risk of dyspepsia (16.7% versus 40.5%; CC versus TT; OR = 5.10, 95% CI: 1.21-21.43, CC versus others; OR = 3.40, 95% CI: 1.16-9.93, respectively). This significant association remained after logistic regression analysis with adjustment for sex and age (CC versus TT; OR = 5.73, 95% CI: 1.27-25.82, CC versus others; OR = 3.08, 95% CI: 1.02-9.25). No significant correlation was found between GNB3 polymorphism and any dyspeptic symptoms. Our data suggest that the homozygous 825T allele of GNB3 protein is associated with dyspepsia in the H. pylori-negative Japanese population. The role of genetics in the development of dyspepsia needs further evaluation.

Drinking capacity and severity of dyspeptic symptoms during a water load test after Nissen fundoplication

Up to 30% of subjects undergoing Nissen fundoplication develop dyspeptic symptoms. Previous studies using the water load test have shown that functional dyspepsia patients have a diminished drinking capacity due to increased visceral sensitivity. Here we investigate drinking capacity and severity of symptoms in 9 patients with dyspeptic symptoms after fundoplication, 9 patients without symptoms after surgery, 18 functional dyspepsia patients, and 18 controls. The water load test was performed by having subjects drinking room-temperature tap water at a predetermined rate of 15 ml/min. The presence and severity of symptoms during the test were evaluated every 5 min using a Likert scale. We found that patients with dyspeptic symptoms after fundoplication had a significantly lower drinking capacity and higher symptoms scores than controls (P<0.05) but values similar to those of functional dyspepsia patients (P>0.05). In contrast, drinking capacity in patients without symptoms after surgery was similar to that in controls (P>0.05). These findings suggest that, as in functional dyspepsia, severe dyspeptic symptoms after Nissen fundoplication are associated with an impaired drinking capacity, reflecting visceral hypersensitivity or impaired gastric accommodation or both.

Comparison of clinical features and patient background in functional dyspepsia and peptic ulcer

To elucidate the clinical features of functional dyspepsia (FD), patients with FD were compared with patients with peptic ulcer. Fifty-eight FD and fifty-nine peptic ulcer patients were compared with respect to clinical features and patient background. In the FD group, symptoms of dyspepsia, especially upper abdominal fullness and nausea, were more common than in the peptic ulcer group. The FD group complained greater distress (severity of the most distressing symptom; P < .001) and showed higher State-Trait Anxiety Inventory (STAI) scores (trait-anxiety score; P < .05). A higher proportion of FD patients had consulted another physician (P < .01). Even when subjects from the FD and peptic ulcer group in this study were matched for age and gender and compared with respect to these variables, almost the same characteristics were seen. These results indicate that FD markedly decreases quality of life in a variety of aspects.

Breathing exercises with vagal biofeedback may benefit patients with functional dyspepsia

OBJECTIVE

Many patients with functional dyspepsia (FD) have postprandial symptoms, impaired gastric accommodation and low vagal tone. The aim of this study was to improve vagal tone, and thereby also drinking capacity, intragastric volume and quality of life, using breathing exercises with vagal biofeedback.

MATERIAL AND METHODS

Forty FD patients were randomized to either a biofeedback group or a control group. The patients received similar information and care. Patients in the biofeedback group were trained in breathing exercises, 6 breaths/min, 5 min each day for 4 weeks, using specially designed software for vagal biofeedback. Effect variables included maximal drinking capacity using a drink test (Toro clear meat soup 100 ml/min), intragastric volume at maximal drinking capacity, respiratory sinus arrhythmia (RSA), skin conductance (SC) and dyspepsia-related quality of life scores.

RESULTS

Drinking capacity and quality of life improved significantly more in the biofeedback group than in the control group (p=0.02 and p=0.01) without any significant change in baseline autonomic activity (RSA and SC) or intragastric volume. After the treatment period, RSA during breathing exercises was significantly correlated to drinking capacity (r=0.6, p=0.008).

CONCLUSIONS

Breathing exercises with vagal biofeedback increased drinking capacity and improved quality of life in FD patients, but did not improve baseline vagal tone.

Distension-induced gastric accommodation in functional dyspepsia: effect of autonomic manipulation

Functional dyspepsia (FD) is associated with impaired gastric accommodation and autonomic dysregulation. The aim of this study was to investigate the effects of autonomic manipulation on distension-induced gastric accommodation in subjects with and without FD, using a newly developed gastric barostat paradigm. Twelve healthy subjects (HS) and 18 subjects with FD had four barostat examinations each: no intervention, intravenous atropine (1 mg), vagal stimulation (mental relaxation with deep breathing) and acute stress stimulation (serial subtraction task). Intrabag pressure increased from 1 to 15 mmHg in 5 min (ramp phase), and was maintained at 15 mmHg for 5 min (tonic phase). Volume responses were analysed using predefined parameters. There were no significant group differences in accommodation variables between HS and subjects with FD. The FD group could be subdivided into two distinct subgroups: subgroup 1 (n = 7, 38%) with low maximum volume and accommodation rate, and subgroup 2 with normal accommodation (n = 11). In subgroup 1, but not in subgroup 2 atropine increased maximum volume and accommodation rate substantially. Neither mental stress nor mental relaxation changed any of the accommodation variables. In a subgroup of subjects with FD, impairment of distension-induced gastric accommodation can be improved by cholinergic blockade, but not by acute physiological autonomic manipulation.

Somatic referral of visceral sensations and rectal sensory threshold for pain in children with functional gastrointestinal disorders

OBJECTIVE

To test the hypothesis that abdominal pain related to functional gastrointestinal disorders is associated with visceral hypersensitivity and abnormal perception of visceral sensations.

STUDY DESIGN

We examined 35 children (10-17.6 years old) fulfilling the Rome II criteria with irritable bowel syndrome (IBS; n = 21), functional abdominal pain (FAP; n = 8) or functional dyspepsia (FD; n = 6) compared with 10 control subjects (10.2-16.1 years). All underwent a rectal barostat examination. Painful sensations were reported on a human body diagram. The projections of sensations induced by rectal distension, the rectal sensory threshold for pain (RSTP) and the diagnostic value of RSTP measurements were measured.

RESULTS

Rectal distension induced sensations that projected to the S3 dermatome in the control subjects and FD and to aberrant sites in children with IBS and FAP. The RSTP was decreased in children with IBS and FAP compared with control subjects (P <.002) and was not different in children with FD compared with control subjects. At 30.8 mm Hg, the 5th percentile for the control subjects, the RSTP had a sensitivity rate of 89% and a specificity rate of 83% for IBS and FAP diagnosis.

CONCLUSION

Children with IBS and FAP are characterized by the association of rectal hypersensitivity and abnormal pain referral after rectal distension.

Gastric accommodation and motility are influenced by the barostat device: Assessment with magnetic resonance imaging

The barostat is considered the gold standard for evaluation of proximal gastric motility especially for the accommodation response to a meal. The procedure is invasive because it involves the introduction of an intragastric catheter and bag and is not always well tolerated. Moreover, the barostat bag itself may influence motility. Nowadays magnetic resonance imaging (MRI) is able to measure several aspects of gastric motility noninvasively. To evaluate whether the accommodation response of the stomach, observed with the barostat, is present during MRI and whether the barostat interferes with gastric physiology, gastric accommodation, motility, and emptying were studied twice in 14 healthy subjects with MRI using three-dimensional volume scans and two-dimensional dynamic scans once in the presence of a barostat bag and once when the barostat bag was not present. Fasting and postprandial intragastric volumes were significantly higher in the experiment with barostat vs. without barostat (fasting: 350 +/- 132 ml vs. 37 +/- 21 ml, P < 0.0001; postprandial: 852 +/- 126 ml vs. 361 +/- 62 ml, P < 0.0001). No significant differences were found in gastric emptying (88 +/- 41 vs. 97 +/- 40 ml/h, not significant) and contraction frequency between both experiments. The accommodation response observed in the presence of the barostat bag was not observed in the absence of the barostat bag. In conclusion, the presence of an intragastric barostat bag does not interfere with gastric emptying or motility, but the accommodation response measured with the barostat in situ is not observed without the barostat bag in situ. Gastric accommodation is a nonphysiological barostat-induced phenomenon.

Rapid initial gastric emptying and hypersensitivity to gastric filling in functional dyspepsia: effects of duodenal lipids

OBJECTIVE

Impaired distension-induced gastric accommodation and hypersensitivity to distension have been demonstrated by gastric barostat in patients with functional dyspepsia (FD). In this study we investigated distension-induced responses to gastric filling with water in healthy volunteers and FD patients, using non-invasive ultrasonography.

MATERIAL AND METHODS

Eighteen healthy volunteers and 18 FD patients were given infusions of 10 ml saline or lipid (3 kcal/ml) through a nasoduodenal tube. After tube retraction, the stomach was filled with 1000 ml water during 10 min. Intragastric volume was monitored by 3D ultrasonography, and fullness, pain and nausea were assessed.

RESULTS

Compared with healthy volunteers, patients with FD had faster gastric emptying at 5 min (p = 0.0008) and reported more fullness (p = 0.006) during gastric filling with water. Prior duodenal lipid exposure reduced initial gastric emptying rate in FD patients to the level seen in healthy volunteers. However, despite similar gastric volumes, the patients still reported greater fullness (p = 0.002) and nausea (p = 0.01).

CONCLUSIONS

Patients with FD had abnormally rapid initial gastric emptying of water and hypersensitivity to gastric filling. Though normalizing gastric emptying rate and volumes, duodenal lipid exposure did not improve hypersensitivity. Rapid initial gastric emptying of water might be a sign of impaired distension-induced gastric accommodation.

Effect of repeated capsaicin ingestion on intestinal chemosensation and mechanosensation

BACKGROUND

Ingestion of capsaicin reduces symptoms in functional dyspepsia but induces upper abdominal symptoms initially.

AIMS

To evaluate the effects of one week of oral dosing with capsaicin on mechanonociception and chemonociception.

METHODS

Healthy subjects ingested capsules containing 0.5 mg capsaicin t.d.s (n = 8) or placebo (n = 5) for 7 days. Before (day 0) and after (day 8) capsule ingestion the jejunum was distended with a balloon and perfused with a capsaicin solution. A graded questionnaire evaluated distension- and capsaicin-induced sensation, aggregate perception scores were calculated.

RESULTS

Infusion of capsaicin induced sensations similar to distension. In subjects receiving capsaicin capsules, mean +/- S.E.M. perception scores at 24 mL distension volumes were 4.7 +/- 1.2 (day 0) and 3.2 +/- 1.3 (day 8, N.S.). Distension with 40 mL induced perception scores of 10.3 +/- 1.0 vs. 8.2 +/- 1.0 (P < 0.05). During capsaicin perfusion, first sensation was reported after 13.2 +/- 1.9 min (day 0) and 8.1 +/- 0.8 min (day 8, N.S.), discomfort thresholds after 44.1 +/- 6.0 and 31.2 +/- 5.7 min (P < 0.05). In the placebo group, mechano- and chemonociception remained unaltered on days 0 and 8.

CONCLUSIONS

One week of ingestion of capsaicin sensitized chemonociceptors, while sensitivity of mechanonociceptors for distension decreased. Painful sensations during the first week of treatment with capsaicin can be attributed to a sensitizing effect of capsaicin on vanilloid receptors.

Dietary factors in functional dyspepsia

Functional dyspepsia (FD) is characterized by upper gastrointestinal symptoms, which are frequently exacerbated by meal ingestion. While subgroups of FD patients exhibit a range of disturbances in upper gastrointestinal motor function, including delayed gastric emptying and abnormal intragastric meal distribution, which may reflect impaired proximal gastric relaxation and/or antral dysmotility, the association between symptoms and abnormalities in motor function appears to be relatively weak. More recently, the concept of visceral hypersensitivity to mechanical and chemical/nutrient stimuli has been promoted as important in the aetiology of dyspeptic symptoms. Somewhat surprisingly, the role of 'dietary' factors, that is, those factors, related directly to food ingestion, including patterns of nutrient intake, potential intolerance to specific foods or macronutrients, as well as cognitive factors, have been largely ignored. Moreover, presently available treatments fail to take into account the fact that symptoms are frequently induced by eating. This review focuses on the relevance of 'dietary' factors to FD.

Central serotonergic and noradrenergic receptors in functional dyspepsia

Functional dyspepsia is a symptom complex characterised by upper abdominal discomfort or pain, early satiety, motor abnormalities, abdominal bloating and nausea in the absence of organic disease. The central nervous system plays an important role in the conducting and processing of visceral signals. Alterations in brain processing of pain, perception and affective responses may be key factors in the pathogenesis of functional dyspepsia. Central serotonergic and noradrenergic receptor systems are involved in the processing of motor, sensory and secretory activities of the gastrointestinal tract. Visceral hypersensitivity is currently regarded as the mechanism responsible for both motor alterations and abdominal pain in functional dyspepsia. Some studies suggest that there are alterations in central serotonergic and noradrenergic systems which may partially explain some of the symptoms of functional dyspepsia. Alterations in the autonomic nervous system may be implicated in the motor abnormalities and increases in visceral sensitivity in these patients. Noradrenaline is the main neurotransmitter in the sympathetic nervous system and again alterations in the functioning of this system may lead to changes in motor function. Functional dyspepsia causes considerable burden on the patient and society. The pathophysiology of functional dyspepsia is not fully understood but alterations in central processing by the serotonergic and noradrenergic systems may provide plausible explanations for at least some of the symptoms and offer possible treatment targets for the future.

Functional dyspepsia: The role of visceral hypersensitivity in its pathogenesis

Functional, or non-ulcer, dyspepsia (FD) is one of the most common reasons for referral to gastroenterologists. It is associated with significant morbidity and impaired quality of life. Many authorities believe that functional dyspepsia and irritable bowel syndrome represent part of the spectrum of the same disease process. The pathophysiology of FD remains unclear but several theories have been proposed including visceral hypersensitivity, gastric motor dysfunction, Helicobacter pylori infection and psychosocial factors. In this review, we look at the evidence, to date, for the role of visceral hypersensitivity in the aetiology of FD.

Pressure-induced gastric accommodation studied with a new distension paradigm. Abnormally low accommodation rate in patients with functional dyspepsia

OBJECTIVE

A new distension paradigm, by which the gastric volume response to ramp-tonic distension can be analysed in detail, has been developed. The aim of this study was to investigate the applicability of this new paradigm in man, and to compare pressure-induced gastric accommodation in healthy volunteers (HV) and patients with functional dyspepsia (FD).

MATERIAL AND METHODS

Ten HV, and 11 FD patients were examined twice; once in the fasting state and once postprandially. Intragastric bag pressure was raised from 1 to 12 mmHg in 4 min (ramp phase) and then kept constant for 5 min (tonic phase).

RESULTS

Compared to HV, fasting FD patients had lower gastric accommodation rates (0.9+/-0.2 versus 2.5+/-0.4 ml/s, p=0.002), lower maximum volume (239+/-39 versus 428+/-64 ml, p=0.01) and a longer accommodation time (157+/-26 versus 92+/-15 s, p=0.03). A test meal prior to distension tended to normalize the response in FD patients.

CONCLUSIONS

This new barostat paradigm allowed detailed analysis of short-term pressure-induced accommodation in man. Impaired gastric distension-induced accommodation is a novel abnormality in FD.

Acupuncture for functional gastrointestinal disorders

Functional gastrointestinal (GI) symptoms are common in the general population. Especially, motor dysfunction of the GI tract and visceral hypersensitivity are important. Acupuncture has been used to treat GI symptoms in China for thousands of years. It is conceivable that acupuncture may be effective in patients with functional GI disorders because it has been shown to alter acid secretion, GI motility, and visceral pain. Acupuncture at the lower limbs (ST-36) causes muscle contractions via the somatoparasympathetic pathway, while at the upper abdomen (CV-12) it causes muscle relaxation via the somatosympathetic pathway. In some patients with gastroesophageal reflux disease (GERD) and functional dyspepsia (FD), peristalsis and gastric motility are impaired. The stimulatory effects of acupuncture at ST-36 on GI motility may be beneficial to patients with GERD or FD, as well as to those with constipation-predominant irritable bowel syndrome (IBS), who show delayed colonic transit. In contrast, the inhibitory effects of acupuncture at CV-12 on GI motility may be beneficial to patients with diarrhea-predominant IBS, because enhanced colonic motility and accelerated colonic transit are reported in such patients. Acupuncture at CV-12 may inhibit gastric acid secretion via the somatosympathetic pathway. Thus, acupuncture may be beneficial to GERD patients. The antiemetic effects of acupuncture at PC-6 (wrist) may be beneficial to patients with FD, whereas the antinociceptive effects of acupuncture at PC-6 and ST-36 may be beneficial to patients with visceral hypersensitivity. In the future, it is expected that acupuncture will be used in the treatment of patients with functional GI disorders.

Prokinetic effect of gut-oriented hypnosis on gastric emptying

BACKGROUND

No data are available on the effect of hypnosis on gastric emptying.

AIM

To determine the effect of a hypnosis session on gastric emptying and dyspeptic symptoms.

METHODS

We studied emptying by ultrasonography and epigastric sensations in 11 healthy subjects and in 15 patients affected by functional dyspepsia under three conditions according to a fixed schedule: (a) basal, (b) after cisapride and (c) during a 90 min hypnotic trance. Eight healthy subjects repeated an emptying study listening to relaxing music. Statistical analysis was performed using the Friedman test or RM-ANOVA.

RESULTS

In dyspeptics, the postprandial increase in the antral area was significantly smaller during the hypnosis trance than under the basal and the cisapride conditions. For the patients gastric emptying was significantly shortened by cisapride, and even more by hypnosis (basal 274 +/- 16.8 min; cisapride 227 +/- 13.2; hypnosis 150 +/- 9.7) whereas for healthy subjects it was shortened only by hypnosis. The repeated study in healthy subjects listening to relaxing music showed no significant difference compared with the basal. Epigastric sensations were improved in dyspeptics by hypnosis, but not by cisapride.

CONCLUSIONS

Gut-oriented hypnosis is effective in shortening gastric emptying both in dyspeptic and in healthy subjects.

Visceral hypersensitivity in irritable bowel syndrome: a summary review

We examined published reports from 1970 to the present to evaluate the theory that abnormal visceral sensitivity characterizes the irritable bowel syndrome. Evidence to support claims that abnormal visceral sensitivity defines the irritable bowel syndrome falls short because of cognitive deficits in gastrointestinal neurobiology, limitations in experimental design and execution, and the interpretation of results.