Functional Pain Syndromes: Presentation and Pathophysiology.

Abstract

The University of Michigan Health Systems, Ann Arbor, Michigan. paulhill@med.umich.eduFunctional Pain Syndromes: Presentation and Pathophysiology. Edited by Emeran A. Mayer, M.D., M. Catheine Bushnell, Ph.D. Seattle, Washington, IASP Press, 2009. Pages: 580. Price: $95.00.From a purely pragmatic standpoint, it is clear that chronic pain disorders are prevalent and response to treatment is often negligible. Unlike the “organic” pain process in which symptoms are directly related to noxious stimulus, functional pain disorders, such as fibromyalgia, irritable bowel syndrome, and interstitial cystitis lack a well-defined cause. The lack of a clear therapeutic target in “functional” pain disorders can become the source of frustration for the clinician and despair for the patient. Over time, it is common for these patients to become marginalized from meaningful treatment because of a poor understanding of functional pain and associated comorbidities by the treating physicians.The connection between somatic and visceral functional pain disorders and other common comorbidities, including anxiety, depression, chronic fatigue syndrome, and posttraumatic stress disorder, is the theme of this informative and thought-provoking book. This well-organized book consists of 25 chapters divided among seven sections: Somatic Pain Syndromes; Visceral Pain Syndromes; Common Comorbid Syndromes in Relation to Pain; Neurobiological Mechanisms Contributing to Symptoms; Environment–Gene Interactions and Chronic Pain; Treatment Strategies; and Synthesis. The book explores and summarizes the current state of our understanding of functional pain and common comorbid syndromes and, at the same time, acknowledges the shortcomings and limitations of available research. Implicit in each chapter is the difficulty in conducting pain-related research, especially as it pertains to functional pain states.The first two sections review the mechanisms of somatic and visceral pain disorders and provide insight into why patients may develop these problems. The book then explores the relationship between pain and anxiety, depression, somatization, and chronic fatigue. It concludes with a review of reasonable treatment strategies for these vexing clinical problems. Each chapter of the book is written by recognized experts in the field. Figures of pertinent research and proposed mechanisms of the development of functional pain support the text well but are kept to a minimum. Some chapters include color lithographs of functional brain imaging studies in patients with one or more functional pain syndrome. In this way, the central components of functional pain are highlighted in a visually dramatic way.I found the chapters on Environment–Gene Interactions and Chronic Pain to be especially thought provoking. This section explores the genetics of pain as well as early-life trauma and factors that may lead to the development of chronic pain. Much of the section on early-life trauma deals with the neonatal experience and the effects of early-life events on the developing nervous system.As a pain clinician, I find functional pain disorders to be among the most difficult types of pain to treat. Often patients need validation as well as a treatment strategy. This book does an excellent job in familiarizing the clinician with the known processes related to fibromyalgia, interstitial cystitis, and functional cardiac pain, to name a few. Ultimately, these may all be the same syndrome, and the book makes a strong case for the Specific End-Organ Concept and the Pain Matrix, which provides a framework to unify many of the functional pain syndromes and common comorbidities.This book provides a realistic look at our current understanding of functional pain and examines the challenges ahead. It provides the clinician with a rational approach to clinical management based on the synthesis of current research. For these reasons, I recommend this book to anyone who treats patients with chronic pain.The University of Michigan Health Systems, Ann Arbor, Michigan. paulhill@med.umich.edu