Some reports in the 1970s described disturbances of gut perception in patients with the irritable bowel and related syndromes, but these studies remained largely ignored. These classic observations were later reconfirmed and expanded, clearly showing a colonic and rectal hypersensitivity in these patients. Further studies tested whether symptoms after meal ingestion in patients with functional dyspepsia were due to a sort of gastric rigidity, that is, to altered compliance and an abnormal response of the stomach to distension. Gastric accommodation to a meal was experimentally reproduced by distending the stomach with an air-filled bag, either with fixed volumes or at fixed pressure levels maintained by a barostat. With both the methods, the results were equivalent. Gastric distension studies showed that the pressure-volume relationship, that is, compliance, was normal. However, the patients developed their customary symptoms at distending levels that were largely unperceived by healthy subjects. It is important to note that these studies were performed in fasted subjects, and hence, did not entirely reproduce the conditions of meal accommodation. Nevertheless, these data suggested that dyspeptic symptoms could be related to gastric hypersensitivity. Similar type of gut hypersensitive responses were also recognized in patients with noncardiac chest pain, and these data altogether suggested that patients with functional gut disorders could have a sensory dysfunction, so that physiological stimuli induced symptoms. Increased sensitivity to mechanical stimuli may arise from reduced compliance of the gut wall, but this hyper-sensitivity mechanism has been systematically ruled out, because in most studies, gut compliance was shown to be normal. Hence, hypersensitivity seems related to a dysfunction of afferent perception pathways. Over the past decade, the initial observations of visceral hypersensitivity in functional gastrointestinal disorders have been expanded, and the sensory dysfunctions have been further characterized by an extensive series of studies.
Was this article helpful?