Epidemiology and clinical phenomenology of visceral pain

Visceral pain is characterized by a subjectively painful perception located in the abdominal area. Distinct structural lesions or biochemical abnormalities which could serve as explanation for these painful sensations can be only detected in a proportion of patients. In the absence of precise causes for visceral pain, the symptoms are attributed to functional disorders. The two major single entities among functional disorders of the gut are functional dyspepsia and irritable bowel syndrome. Patients with functional dyspepsia characteristically localize the symptoms in the upper abdomen. Functional gastrointestinal disturbances which are localized in the lower abdomen are summarized as irritable bowel syndrome. Interestingly, both functional dyspepsia and irritable bowel syndrome may overlap.