Functional dyspepsia. Symptoms and underlying mechanism.

We define the concept of functional dyspepsia and analyze the putative mechanisms involved in its pathogenesis. We consider the evidence for gastroduodenitis, including the relationship of spiral organisms and viruses in this entity, and for functional dyspepsia as a manifestation of gastric secretory dysfunction and upper gut dysmotility. Functional dyspepsia is probably a heterogeneous condition in which multiple etiopathogenetic mechanisms are involved. Nevertheless, patients with functional dyspepsia constitute a sizable fraction of gastroenterological practice and therefore this disorder deserves intense research.