Irritable Bowel Syndrome: A Clinical Review

Symptoms of irritable bowel syndrome (IBS) are common in population studies including chronic abdominal pain associated with altered bowel habits. Patients often have associated gastrointestinal and somatic symptoms suggesting a possible common contributing mechanism, but the heterogeneous symptom patterns of individual patients make generalizations difficult. The pathophysiology of IBS is incompletely understood but includes disturbances of the brain-gut axis. Central mechanisms are: the psychosocial history and environment, dysfunctional brain processing of peripheral signals attributed to the intestine including the enteric nervous system, the microbiome and the innate and adaptive immune system. As a result there is visceral hypersensitivity and disturbed intestinal secretory and motor activity. Some mechanisms of visceral pain hypersensitivity may overlap with other pain syndromes including fibromyalgia (FMS). Central Sensitization (CS) would offer a way to conceptualize an integration of life experience and psychologic response into a biopsychosocial framework of pathophysiology, diagnosis and treatment of IBS. Corticotropin-releasing factor, a principle regulator in the stress and pain response may contribute to a neuroendocrine mechanism for the brain-gut interaction. The positive diagnostic approach to IBS symptoms to avoid excess testing and enhance the patient-provider therapeutic relationship requires the recognition of the "cluster" of IBS symptoms while identifying "alarm" symptoms requiring specific attention. The severity of the symptoms and other individual psychosocial factors characterize patients who seek medical care. The presence of significant psychosocial comorbidities adds to the complexity of management which often requires a multidisciplinary approach. Several treatment options exist but no single method is effective for all the symptoms of IBS. The therapeutic benefit of the well-executed physician-patient relationship is considered essential to success in managing IBS symptoms over the long term.