Gastrointestinal sensory abnormalities in functional dyspepsia

Symptoms of functional dyspepsia, such as epigastric pain, bloating or earl y satiety and nausea, are non-specific and are likely to arise from differe nt mechanisms. Current evidence suggests the presence of at least two subgr oups: patients who respond to a prolonged course of acid suppression and pa tients who show a significant overlap of symptoms with other functional gas trointestinal disorders such as irritable bowel syndrome. An enhanced sensi tivity of visceral afferent pathways with or without associated autonomic d ysregulation appears to play an important role in the aetiology of symptoms in the second group. In the absence of visceral hypersensitivity, neither the slowing of gastric emptying nor the presence of chronic gastritis appea rs to be sufficient to cause symptoms of functional dyspepsia. The mechanis ms and aetiology of visceral hypersensitivity are incompletely understood. An alteration in the interplay between vagal and spinal afferents, and the inadequate activation of antinociceptive systems in response to tissue irri tation, may play a role in symptom generation.