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Pathophysiology of functional dyspepsia

https://doi.org/10.1016/j.bpg.2004.04.007Get rights and content

Abstract

Functional dyspepsia is a highly prevalent symptom complex and a heterogenous disorder. Recent studies showed potential associations between specific pathophysiologic disturbances and dyspeptic symptoms. Delayed gastric emptying reported in about 30% of patients with functional dyspepsia is associated with the symptoms of postprandial fullness, nausea, and vomiting. Impaired gastric accommodation present in 40% of functional dyspepsia patients is found to be associated with early satiety. Hypersensitivity to gastric distension is observed in 37% of functional dyspepsia patients and associated with the symptoms of postprandial pain, belching, and weight loss. Psychosocial factors and altered response to duodenal lipids or acid have also been identified as pathophysiologic mechanisms.

Section snippets

Delayed gastric emptying

Several studies have addressed the prevalence and role of gastric emptying in functional dyspepsia. In a meta-analysis of 17 studies involving 868 dyspeptic patients and 397 controls, significant delay of solid gastric emptying was present in almost 40% of patients with functional dyspepsia.7 However, most of the studies were performed on small groups of patients and small control groups. In recent large studies, gastric emptying of solids was delayed in about 30% of the patients with

Impaired gastric accommodation to a meal

The motor functions of the proximal and distal stomach differ remarkably. Whereas the distal stomach regulates gastric emptying of solids by grinding and sieving the content until the particles are small enough to pass the pylorus, proximal stomach serves mainly as a reservoir. Accommodation of the stomach to a meal consists of a relaxation of the proximal stomach, providing the meal with a reservoir and enabling a volume increase without an increase in pressure.

Scintigraphic and

Hypersensitivity to gastric distension

Physiological stimuli during the digestive process are not normally perceived but in some circumstances may induce conscious sensations. During the past decade, it has been suggested that patients with functional gastrointestinal diseases have a sensory dysfunction of the gut, allowing physiological stimuli to induce symptoms.29., 30. Several studies have clearly established that, as a group, patients with functional dyspepsia have enhanced sensitivity to gastric distension.31., 32., 33., 34.

H. pylori infection

Many studies have attempted to establish a link between H. pylori infection and functional dyspepsia, but the role of H. pylori in functional dyspepsia remains to be a subject of controversy. A critical review of epidemiological and therapeutic studies investigating the possible association of H. pylori infection and functional dyspepsia revealed that many of the studies had important weaknesses in design and execution. Even in the studies designed to avoid weaknesses of earlier studies, no

Altered response to duodenal lipids or acid

Dyspeptic symptoms in functional dyspepsia are commonly exacerbated by meals rich in fat. A previous study showed that duodenal lipid infusion exacerbated the hypersensitivity to gastric distension in patients with functional dyspepsia and most patients experienced nausea and bloating in contrast to healthy subjects who reported no symptoms during lipid infusion.47 This effect of fat appeared to be specific as infusion of an isocaloric glucose solution into the duodenum did not induce the same

Altered antroduodenojenunal motility

A number of studies using upper gastrointestinal manometry in functional dyspepsia have reported antral hypomotility as the most common finding.62., 63., 64., 65. It is presently unclear whether this reflects true hypomotility or a poor registration of contractions in a dilated antrum in patients with impaired accommodation, as manometry only registers lumen-obliterating contractions.18., 66., 67., 68. Small bowel motor alterations, usually hypermotility with burst activity or clusters and an

Abnormalities of gastric electrical rhythm

There is also evidence that abnormalities in the underlying gastric myoelectrical activity, as measured by cutaneous electrogastrography, are found in up to two thirds of patients with functional dyspepsia.69., 70., 71. The relevance of this finding for gastric emptying and symptom patterns remains to be established. No correlation was found between dyspeptic symptom pattern and the presence of findings on electrogastrography.70 A good correlation between the presence of delayed gastric

Unsuppressed postprandial phasic contractility in the proximal stomach

Besides the relaxatory response of the proximal stomach after a meal, other motor aspects of the proximal stomach have not been particularly frequently addressed in the literature. With the barostat technique it is also possible to detect phasic volume fluctuations from the baseline volumes (‘volume waves’), reflecting contractions superimposed on the background state of contractility or tone.72 Phasic fundic contractions induce transient increases in gastric wall tension and can be perceived

ANS-CNS dysregulation

Abnormalities within the autonomic nervous system have been suggested to be of importance in some patients with functional dyspepsia. More specifically, an efferent vagal dysfunction has been observed in several studies.27., 75., 76. This has been proposed to be one possible mechanism behind the impaired accommodation to a meal26 and antral hypomotility27 seen in this patient group. There is also indirect evidence for a relationship between psychological factors and emotions and gastric

Conclusions

Functional dyspepsia is a highly prevalent symptom complex and a heterogenous disorder with different pathophysiologic disturbances underlying different symptom profiles. The pathophysiologic mechanisms may interact to generate a variety of symptoms.

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