Symptoms and gastric function in dyspepsia--goodbye to gastroparesis?

Plausibility criteria for putative pathophysiological mechanisms in functional gastrointestinal disorders: a consensus of experts

BACKGROUND AND AIMS

The functional gastrointestinal disorders (FGIDs) are extremely common conditions associated with a considerable personal, social and health economic burden. Managing FGIDs in clinical practice is challenging because of the uncertainty of symptom-based diagnosis, the high frequency of overlap between these conditions and the limited efficacy of available therapies. It has often been argued that successful drug development and management of FGIDs requires knowledge of the underlying pathophysiology. Numerous and highly variable candidate pathophysiological mechanisms have been implicated in the generation of FGID symptoms, but there is no current consensus on how to best define the relevance of these disturbances.

METHODS

A group of international experts on FGIDs developed plausibility criteria that should be fulfilled by relevant pathophysiological mechanisms in FGIDs.

RESULTS

Five criteria are proposed: (1) the presence of the abnormality in a subset of patients, (2) temporal association between proposed mechanism and symptom(s), (3) correlation between the level of impairment of the mechanism and symptom(s), (4) induction of the symptom(s) by provoking the pathophysiological abnormality in healthy subjects and (5) treatment response by a therapy specifically correcting the underlying disorder or congruent natural history of symptoms and dysfunction in the absence of specific therapy. Based on strength of evidence for these five criteria according to the Grading of Recommendations Assessment, Development and Evaluation system, a plausibility score can be calculated for each mechanism.

CONCLUSION

Evaluation of the strength of evidence for candidate pathophysiological abnormalities fulfilling these five plausibility criteria will help to identify the most relevant mechanisms to target for novel diagnostic approaches and for the development of new therapies.

Electrical bioimpedance and other techniques for gastric emptying and motility evaluation

The aim of this article is to identify non-invasive, inexpensive, highly sensitive and accurate techniques for evaluating and diagnosing gastric diseases. In the case of the stomach, there are highly sensitive and specific methods for assessing gastric motility and emptying (GME). However, these methods are invasive, expensive and/or not technically feasible for all clinicians and patients. We present a summary of the most relevant international information on non-invasive methods and techniques for clinically evaluating GME. We particularly emphasize the potential of gastric electrical bioimpedance (EBI). EBI was initially used mainly in gastric emptying studies and was essentially abandoned in favor of techniques such as electrogastrography and the gold standard, scintigraphy. The current research evaluating the utility of gastric EBI either combines this technique with other frequently used techniques or uses new methods for gastric EBI signal analysis. In this context, we discuss our results and those of other researchers who have worked with gastric EBI. In this review article, we present the following topics: (1) a description of the oldest methods and procedures for evaluating GME; (2) an explanation of the methods currently used to evaluate gastric activity; and (3) a perspective on the newest trends and techniques in clinical and research GME methods. We conclude that gastric EBI is a highly effective non-invasive, easy to use and inexpensive technique for assessing GME.

Influence of delaying gastric emptying on meal-related symptoms in healthy subjects

BACKGROUND

Although delayed gastric emptying is often found in functional dyspepsia, a causal role for delayed emptying in inducing symptoms has not been demonstrated.

AIM

To investigate the influence of delaying gastric emptying rate in healthy volunteers on the occurrence of meal-related symptoms.

METHODS

Fourteen healthy subjects (six men, mean age 23 +/- 1) underwent gastric emptying studies twice using the 14C octanoic acid and 13C glycin breath test after pre-treatment with saline or sumatriptan 6 mg s.c. Breath samples were taken before meal and at 15-min intervals for a period of 360 min postprandially. At each breath sampling, the subject was asked to grade the intensity (0-6) of four dyspeptic symptoms.

RESULTS

Sumatriptan pre-treatment significantly delayed solid but not liquid gastric emptying (t1/2 respectively 159 +/- 11 vs. 112 +/- 9 min, P < 0.005 and 134 +/- 11 vs. 116 +/- 12 min, N.S.). Sumatriptan significantly decreased the mean cumulative symptom score (21.3 +/- 5.5 vs. 8.0 +/- 2.6, P = 0.01), as well as scores for each individual symptom.

CONCLUSION

A moderate delay in gastric emptying in health is not associated with an increase of meal-related symptoms. This observation argues against a causal role for delayed gastric emptying in the pathogenesis of dyspeptic symptoms.

Review article: gastric emptying in functional gastrointestinal disorders

Although delayed gastric emptying has been described in several functional gastrointestinal disorders, and appears to be especially common in functional dyspepsia, the relationship of this finding to symptoms and basic pathophysiology is difficult to define. The delineation of the interactions between delayed gastric emptying, on the one hand, and symptom pathogenesis, on the other, has been hampered by several factors. These include the limitations of the methodology itself, the extent of overlap between the various functional disorders and the sensitivity of gastric emptying to factors external to the stomach, be they elsewhere within the gastrointestinal tract, in the central nervous system or in the environment. In many instances, delayed gastric emptying is an epiphenomenon, reflecting the overlap between inadequately defined functional syndromes, shared pathophysiology or the activation of physiological interactions between the various organs of the gut. In others, it may imply a truly diffuse motor disorder. The disappointments attendant on attempts to alleviate symptoms through approaches designed to accelerate gastric emptying should therefore not come as a surprise. Pending the definition of the true significance of delayed gastric emptying in all functional gastrointestinal disorders, caution should be exerted in the interpretation of this finding in a patient with functional symptoms.

Gastric emptying in myotonic dystrophic patients

BACKGROUND

Myotonic dystrophy is often associated with digestive symptoms that can precede the clinical appearance of skeletal muscle involvement. Although motility disorders may be observed in these patients at any level of the gastrointestinal tract, upper gastrointestinal symptoms have up to now usually been considered to be due to oesophageal rather than gastric dysmotility.

AIMS

To evaluate: a) gastric emptying in myotonic dystrophic patients without dyspeptic symptoms, and b) relationship between gastric emptying and severity and duration of the disease.

PATIENTS AND METHODS

Gastric emptying was evaluated in 11 non-dyspeptic dystrophic patients and in 22 healthy volunteers by means of computerised ultrasound scan, assessing the variation in the antral area over time after ingestion of a meal.

RESULTS

The final emptying time was higher in patients than in healthy volunteers (373' +/- 35' vs 270' +/- 47'; p < 0.001). Basal and maximal post-prandial antral areas were similar in the two groups. There was a significant correlation between gastric emptying and the duration of the disease (rs = 0.62; p = 0.04). No relationship was found between gastric emptying and severity of the disease.

CONCLUSIONS

Gastric emptying may be abnormally delayed in myotonic dystrophy patients, even in absence of dyspeptic symptoms. This delay is correlated with duration but not with severity of the disease. However there is no difference in either basal or maximal postprandial antral areas between myotonic dystrophy patients and healthy volunteers.

Functional gut disorders: from motility to sensitivity disorders. A review of current and investigational drugs for their management

Functional gut disorders include several clinical entities defined on the basis of symptom patterns (e.g., functional dyspepsia, irritable bowel syndrome, functional abdominal pain, functional abdominal bloating), for which there is no established pathophysiological mechanism. Because there is no well-defined pathophysiological target, treatment should be aimed at symptom improvement. Prokinetics and antispasmodics have been widely used in the treatment of functional gut disorders on the assumption that disordered motility is the underlying cause of symptoms, and symptom improvement is indeed achievable with these compounds in some, but not all, patients with features of hypo- or hypermotility, respectively. In the first part of this review, we cover the basic pharmacology and discuss the rationale for the clinical use of prokinetics and antispasmodics. On the other hand, in the past few years, the explosive growth in the research focusing on visceral sensitivity and visceral reflexes has suggested that at least some patients with functional gut disorders have altered visceral perception. Thus, the second part of the review covers these developments and focuses on studies addressing the issue of drugs modulating visceral sensitivity.