The Pathophysiology of Irritable Bowel SyndromeCME - Medscape

The Pathophysiology of Irritable Bowel Syndrome CMESlide 3.In the past, the predominant pathophysiologic mechanisms in IBS were thought to be abnormalities in the gut smoothmuscle function, visceral hypersensitivity, and central nervous system (CNS) hypervigilance. However, hypersensitivity and CNSdysfunction are not ubiquitous. In many respects, IBS is not always all in the patient’s head. We now recognize that symptoms ofIBS are manifestations of several peripheral mechanisms that perturb the motor and sensory functions of the gut. During the past10 years, there has been a renaissance in our understanding of IBS.The mechanisms underlying IBS include the traditionally recognized CNS hypervigilance, altered sensitivity, altered motility, aswell as psychosocial factors. We now recognize, however, the existence of peripheral mechanisms that initiate perturbation ofgastrointestinal (GI) motor and sensory functions that lead to IBS symptoms. These irritants include the products of digestion,neurotransmitters, transporters, a history of gastroenteritis, changes in the microbiome, mucosal immune activation, andincreased mucosal permeability. In addition, it is recognized that disorders of rectal evacuation mimic the symptoms ofconstipation-predominant irritable bowel syndrome (IBS-C).The relevance of these advances in our understanding is that the identification of these peripheral irritants provides anopportunity to prevent or reverse the symptoms of IBS.Pg.6