Overview of functional gut disorders: a challenge

The term 'functional disorder' has two main meanings in the clinical realm, neither mutually exclusive: (i) a demonstrable disorder of function that readily explains the symptoms (the common wisdom in the accepted biomedical model of disease); and (ii) a variable combination of chronic or recurrent symptoms not explained by structural or biochemical abnormalities. This is a broader view that incorporates the concepts of illness as well as disease, and one which recognizes that symptoms and behavior may be out of proportion to the objective evidence of abnormality. The challenge is to reconcile these two apparently different views of a patient presenting with symptoms. In this way, investigation and management of a patient's symptoms can be directed not only to the underlying motor and sensory disorders, but also to all of the other psychosocial and cognitive-behavioral factors that impact on the gut through the brain-gut axis and on patient behavior. These numerous aspects of functional gut disorders will be illustrated by a discussion of the factors involved in the pathophysiology of gastroesophageal reflux disease and of the behavior of individuals with this disorder.