Table of Contents
Cover
Table of Contents
Dedication
Title page
Copyright page
List of contributors
Foreword
Part 1: Basic Understanding of Pain Medicine
Chapter 1 The challenge of pain: a multidimensional phenomenon
Introduction
Chapter 2 Epidemiology and economics of chronic and recurrent pain
Introduction
Epidemiology of chronic and recurrent pain
Musculoskeletal pain
Chronic widespread pain
Headache
Factors associated with chronic and recurrent pain
Economic impact of chronic pain
Conclusions
Chapter 3 Basic mechanisms and pathophysiology
Introduction
Primary afferent neurons
Nociceptor subtypes
Nociceptors and noxious stimulus detection
Organization of the “pain system”
Sensitization and persistent pain
Analgesic targets
Chapter 4 Psychosocial perspectives on chronic pain
Introduction
Modeling the network of biological, psychological and social determinants of pain
Psychosocial factors in best practice
The person in pain
Caregivers
Pain management
Conclusions
Chapter 5 Identification of risk and protective factors in the transition from acute to chronic post surgical pain
Introduction
Definition and epidemiology of CPSP
Understanding risk and attributing causality to outcomes
Factors associated with CPSP
Preventive analgesia
Summary and conclusions
Chapter 6 Placebo/nocebo: a two-sided coin in the clinician’s hand
Introduction
Before we begin: a few facts on placebo/nocebo
Proposed mechanisms of placebo/nocebo effects
Neurobiology of placebo analgesia
Neurobiology of nocebo hyperalgesia
The coin in the clinician’s hand
Conclusions
Acknowledgments
Part 2: Assessment of Pain
Chapter 7 Clinical assessment in adult patients
Introduction
The history
Physical examination
Musculoskeletal examination
Neurological examination
Conclusions
Chapter 8 Measurement and assessment of pain in pediatric patients
Introduction
Assessing pain in children
Obtaining a pain history
Approaches to measuring pain in children
Tools for assessing pain in children
Choosing the right pain assessment measure
Frequency of pain assessment and documentation
Conclusions
Acknowledgments
Chapter 9 Laboratory investigations, imaging and neurological assessment in pain management
General principles
Common laboratory, imaging and neurological investigations for the patient with chronic pain
Conclusions
Acknowledgments
Chapter 10 Psychological assessment of persons with chronic pain
Introduction
Components of a psychological assessment
Assessment measures
Substance abuse assessment
Electronic diaries and web-based assessment
Future directions
Part 3: Management
Chapter 11 Introduction to management
Overview
Start with the basics
Conclusions
Chapter 12 Managing chronic pain in primary care
Introduction
Basic mechanisms and the scientific basis for understanding the subject
Impact on clinical practice
Features of best clinical practice for managing chronic pain in primary care
Conclusions
Part 4: Pharmacotherapy
Chapter 13 Nutrition and pain management: dietary soy as an analgesic modality
Diet as an analgesic modality
Soybeans: their significance and destiny in the human diet
Hyponociceptive effect of soy: preclinical evidence
Hyponociceptive mechanisms of soy
Analgesic effect of soy protein: clinical evidence
Clinical considerations in using soy protein
Current and future research endeavors
Acknowledgments
Chapter 14 Antidepressant analgesics in the management of chronic pain
Introduction
Basic mechanisms
Basic understanding of mechanisms and their impact on clinical practice
Best clinical practice for antidepressants in some CNCP conditions
Fibromyalgia
Headache
Low back pain
Arthritis
Adverse events
Choice of agent
Approach to therapy
Chapter 15 Anticonvulsants in the management of chronic pain
Introduction
Anticonvulsants in chronic pain: mechanisms of action
Anticonvulsants in neuropathic pain
Anticonvulsants in migraine
Anticonvulsants in fibromyalgia
Other anticonvulsants currently not used for chronic pain treatment
Safety and dosing
Conclusions
Acknowledgement
Chapter 16 Opioids
Introduction
Mechanism of action
Clinical pharmacology
Patient selection and risk stratification
Monitoring and management
Conclusions
Chapter 17 Topical analgesics
Introduction
Topical NSAIDs
Topical local anesthetics
Topical capsaicin
Topical rubefacients
Peripheral and topical opioids
Investigational topical agents
Chapter 18 Other pharmacological agents
Introduction
Non-steroidal anti-inflammatory drugs
Acetaminophen
Skeletal muscle relaxants
Cannabinoids
Part 5: Interventional
Chapter 19 Diagnostic and therapeutic blocks
Introduction
Diagnostic blocks
Peripheral nerve blocks
Occipital nerve blocks
Lateral femoral cutaneous nerve block
Sympathetic blocks
Diagnostic and therapeutic blocks for neck and back pain
Conclusions
Chapter 20 Neuromodulation therapy
Introduction
Types of neuromodulation therapy
Conclusions
Chapter 21 Neurosurgical management of pain
Introduction
Anatomic
Neuromodulatory
Neuroablation
Peripheral nervous system
Spinal cord
Brainstem
Intracranial
Conclusions
Acknowledgment
Part 6: Physical Therapy and Rehabilitation
Chapter 22 Physical therapy and rehabilitation
Chronic pain and rehabilitation
Treatment approaches
Part 7: Psychological
Chapter 23 Pain self-management: theory and process for clinicians
Introduction
What is self-management?
Background: Stanford self-management program model
Content, process and strategies to enhance self-efficacy
Effectiveness of pain self-management programs: main findings
Getting started: conducting a needs assessment
Focus groups
Conclusions and resources
Acknowledgments
Chapter 24 Psychological interventions: cognitive behavioral and stress management approaches
Introduction
Mechanisms underlying and evidence supporting psychological interventions
Best clinical practice
Conclusions
Chapter 25 Pain catastrophizing and fear of movement: detection and intervention
Introduction
Pain catastrophizing (maladaptive coping)
Fear of movement associated with pain
Assessment of catastrophizing
Treatments aimed at reducing catastrophizing
Assessment of fear of movement
Treatments aimed at reducing fear of movement
Conclusions
Part 8: Complementary Therapies
Chapter 26 Complementary and alternative medicines
Introduction
Definition of CAM
Asking about CAM
Absence of evidence or evidence of absence
Why do patients use CAM?
A question of quality
Making sense in the information age
Finding the evidence base
Integrating CAM into pain medicine
Part 9: Specific Clinical States
Chapter 27 Chronic low back pain
Introduction
Clinical evaluation
Trivial findings and the “pseudo-diagnosis”
Natural history
Progression to chronic low back pain
Treatment of chronic LBP with only common degenerative changes
Conclusions
Chapter 28 Fibromyalgia syndrome and myofascial pain syndromes
Introduction
Definition and classification
Prevalence
Course and prognosis
Diagnosis of fibromyalgia syndrome
Diagnosis of myofascial pain syndrome
Basic mechanisms
Impact of basic understanding on clinical management
Treatment of fibromyalgia syndrome
A stepwise treatment approach to fibromyalgia syndrome
Treatment of myofascial pain syndrome
Conclusions
Chapter 29 Clinical pain management in the rheumatic diseases
Introduction
Basic mechanisms in rheumatic pain
Clinical practice
Treatment
Obstacles to optimal pain management
Conclusions
Chapter 30 Headache
Introduction
Evaluation and diagnostic testing
Migraine
Chronic daily headache
Tension-type headache
Cluster headache and other trigeminal autonomic cephalgias
Trigeminal neuralgia
Conclusions
Chapter 31 Orofacial pain
Introduction
Orofacial nociceptive processes
Clinical aspects
Chapter 32 Visceral pain
Introduction
Basic mechanisms of visceral pain
Evidence-based treatment strategies
Management of common visceral pain syndromes
Conclusions
Chapter 33 Pelvic and urogenital pain
Introduction
Pain-specific treatment
Disease-specific treatment
Conclusions
Chapter 34 Neuropathic pain
Introduction
Basic mechanisms
Clinical picture
Clinical examination
Other diagnostic procedures
Management of neuropathic pain
Pharmacotherapy of neuropathic pain
Conclusions
Chapter 35 Complex regional pain syndrome
Introduction
Development of the validation process
CRPS and genetics
Sensory characteristics and pathophysiology of CRPS
Autonomic nervous system
Inflammatory characteristics
Behavioral–premorbid psychological aspects
Functional restoration
Pharmacologic and interventional therapies
Conclusions
Chapter 36 Cancer pain management
Introduction
Basic mechanisms
Assessment
Management
Adjuvant therapies
Continuity of care and multidisciplinary management
Part 10: Special Populations
Chapter 37 Pain in older persons: a brief clinical guide
Introduction
Age-related change in pain sensitivity and nociceptive processing
Clinical pain assessment of the cognitively intact older adult
Clinical approach to pain assessment in persons with dementia
Psychosocial interventions
Other non-pharmacological approaches to pain management
Pharmacological therapies
Acknowledgments
Chapter 38 Pain in children
Introduction
Significance of recurrent and chronic pain in children
Basic mechanisms
Clinical practice: evaluation and management
Evidence base for pharmacological treatments
Evidence base for psychological treatments
Evidence base for physical therapy interventions
Evidence base for complementary and alternative medicine therapies
Putting it all together: a treatment algorithm
Chapter 39 Pain in individuals with intellectual disabilities
Introduction and overview
Defining ID and conceptual issues
Scope of the problem of pain in individuals with ID
Pain assessment tools
Pain management
Conclusions
Acknowledgments
Chapter 40 Pain and addiction
Introduction
Prevalence, neurobiology and definitions
Neurobiology of addiction
Defining opioid addiction in a patient with pain
Screening and risk stratification
Universal Precautions in pain management
Strategies for treating the high risk patient
Chapter 41 Pain and psychiatric illness
Introduction
Conclusions
Index
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Library of Congress Cataloging-in-Publication Data
Clinical pain management : a practical guide / edited by Mary E. Lynch, Kenneth D. Craig, Philip W.H. Peng.
p. ; cm.
Includes bibliographical references.
ISBN 978-1-4443-3069-4
1. Pain. 2. Pain–Treatment. I. Lynch, Mary E. II. Craig, Kenneth D.,
1937- III. Peng, Philip W. H.
[DNLM: 1. Pain–therapy. 2. Palliative Care–methods. WL 704 C6415 2011]
RB127.C593 2011
616'.0472–dc22
2010024524
ISBN: 978-1-4443-3069-4
A catalogue record for this book is available from the British Library.
This book is published in the following electronic formats: ePDF 9781444329728; Wiley Online Library 9781444329711; ePub 9781444329735
Lene Baad-Hansen Associate Professor, Department of Clinical Oral Physiology, Aarhus University, Aarhus, Denmark
Cathrine Baastrup MScPharm, Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark
Misha Ba
konja MD, Professor, Department of Neurology, University of Wisconsin, Madison, USA
Diaa Bahgat MD, Instructor, Department of Neurological Surgery, Oregon Health & Science University, Portland, USA
Allan I. Basbaum PhD FRS, Department of Anatomy, University of California at San Francisco, San Francisco, USA
Fabrizio Benedetti MD, Professor of Physiology and Neuroscience, Department of Neuroscience, University of Torino Medical School, Torino, Italy; National Institute of Neuroscience, Torino, Italy
Klaus Bielefeldt MD PhD, University of Pittsburgh Medical Center, Division of Gastroenterology, Pittsburgh, USA
Sharon Bishop BNurs MHlthSci, Clinical Nurse Specialist, Department of Neurosurgery, Regina General Hospital, Regina, Canada
Eduardo Bruera MD, Professor and Chair, Department of Palliative Care and Rehabilitation Medicine Unit 008, University of Texas M.D. Anderson Cancer Center, Houston, USA
Kim J. Burchiel MD FACS, Professor and Chair, Department of Neurological Surgery, Oregon Health and Science University, Portland, USA
Chantel C. Burkitt BA, Department of Educational Psychology, University of Minnesota, Minneapolis, USA
Eugene J. Carragee MD, Professor and Vice Chairman, Department of Orthopedic Surgery, Stanford University School of Medicine, Redwood City, USA
Daniel J. Cavanaugh PhD, Department of Anatomy, University of California at San Francisco, San Francisco, USA
Stéphanie Chevalier PhD, McGill Nutrition & Food Science Centre, McGill University Health Centre, Montreal, Canada
Alexander J. Clark MD FRCPC, Professor of Anesthesia, Dalhousie University, Halifax, Nova Scotia, Canada
Alexis Codrington PhD, Alan Edwards Pain Management Unit, McGill University Health Centre, Montreal, Canada
Beverly Collett FRCA FFPMRCA, Consultant in Pain Medicine, University Hospitals of Leicester, Leicester, UK
Kenneth D. Craig PhD, Professor Emeritus, Department of Psychology, University of British Columbia, Vancouver, Canada
Gilbert J. Fanciullo MD MS, Professor of Anesthesiology, Dartmouth Medical School, Lebanon, NH, USA; Director, Head of Pain Medicine, Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, Lebanon, NH, USA
Perry G. Fine MD, Professor of Anesthesiology, Pain Research Center, School of Medicine, University of Utah, Salt Lake City, USA
Nanna Brix Finnerup MD PhD, Associate Professor, Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark
Mary-Ann Fitzcharles MB ChB FRCP(C), Montreal General Hospital Pain Center, Montreal General Hospital, McGill University, Montreal, Canada; Division of Rheumatology, McGill University, Montreal, Canada
Gerald F. Gebhart PhD, Professor and Director, Center for Pain Research, Department of Anesthesiology, University of Pittsurgh, Pittsburgh, USA
Stephen Gibson PhD, Deputy Director, National Ageing Research Institute, Caulfield Pain Management Center, Royal Melbourne Hospital, Melbourne, Australia
Padma Gulur MD, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, and Harvard Medical School, Boston, USA
Maija Haanpää MD PhD, Chief Neurologist, Rehabilitation Orton, Helsinki, Finland; and Pian Consultant, Department of Neurosurgery, Helsinki University Hospital, Helsinki, Finland
Heather D. Hadjistavropoulos PhD, Professor, Department of Psychology, University of Regina, Regina, Canada
Thomas Hadjistavropoulos PhD ABPP, Professor, Department of Psychology and Center on Aging and Health, University of Regina, Regina, Canada
Winfried Häuser MD, Associate Professor, Department Internal Medicine I and Interdisciplinary Center of Pain Medicine, Klinikum Saarbrücken, Germany
Peter Henningsen MD, Professor, Department of Psychosomatic Medicine and Psychotherapy, Technische Universität München, München, Germany
Fred M. Howard MD MPH, Professor of Obstetrics & Gynecology, University of Rochester School of Medicine, Rochester, USA
David Hui MD MSc FRCPC, Palliative Oncology Fellow, Department of Palliative Care & Rehabilitation Medicine Unit 1414, University of Texas M.D. Anderson Cancer Center, Houston, USA
Gordon Irving MB BS FFA(SA) MSc MMed, Clinical Assistant Professor, University of Washington Medical School, Seattle, USA
Robert N. Jamison PhD, Associate Professor, Departments of Anesthesia and Psychiatry, Brigham and Women’s Hospital, Harvard Medical School, Chestnut Hill, USA
Troels Staehelin Jensen MD PhD, Professor, Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark; Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
Roman D. Jovey MD, Medical Director, CPM Centers for Pain Management; Physician Director, Addictions and Concurrent Disorders Center, Credit Valley Hospital, Mississauga, Canada
Joel Katz PhD, Department of Psychology, York University, Toronto, Canada; Department of Anesthesia and Pain Management, Toronto General Hospital, Toronto, Canada; Department of Anesthesia, University of Toronto, Toronto, Canada
Jeffrey L. Koh MD, Professor, Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, USA
Krishna Kumar MB MS FRCS(C) FACS, Clinical Professor of Neurosurgery, University of Saskatchewan; Medical Office Wing, Regina General Hospital, Regina, Canada
Sandra M. LeFort Professor, School of Nursing, Memorial University of Newfoundland, St. John’s, Canada
Mary Lynch MD FRCPC, President Elect Canadian Pain Society; Professor Anesthesia, Psychiatry and Pharmacology, Dalhousie University, Haifax, Nova Scotia, Canada; Director, Pain Management Unit, Queen Elizabeth II Health Sciences Center, Halifax, Nova Scotia, Canada
Anjali Martinez MD, Assistant Professor, Obstetrics and Gynecology, George Washington University, Washington DC, USA
Michael McGillion RN PhD, Assistant Professor, Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, Canada
Patrick J. McGrath OC PhD FRSC FCAHS, Vice President Research, IWK Health Center; Professor of Psychology, Pediatrics and Psychiatry, Canada Research Chair, Dalhousie University, Halifax, Nova Scotia, Canada
Ronald Melzack Professor Emeritus, Department of Psychology, McGill University, Montreal, Canada
Harold Merskey DM FRCPC, Professor Emeritus of Psychiatry, University of Western Ontario, London, Canada
Tim F. Oberlander MD FRCPC, Professor, Pediatrics, University of British Columbia, Vancouver, Canada; R. Howard Webster Professor in Early Child Development, University of British Columbia, Vancouver, Canada; Complex Pain Service, BC Children’s Hospital, Vancouver, Canada
M. Gabrielle Pagé Department of Psychology, York University, Toronto, Canada
Tonya M. Palermo PhD, Associate Professor, Anesthesiology, Pediatrics and Psychiatry, Seattle Children’s Hospital, University of Washington School of Medicine, Seattle, USA
Don Young Park MD, Clinical Instructor, Department of Orthopedic Surgery, Stanford University School of Medicine, Redwood City, USA
Philip W.H. Peng MBBS FRCPC, Director, Anesthesia Chronic Pain Program, University Health Network and Mount Sinai Hospital, Toronto, Canada; Associate Professor, University of Toronto, Toronto Western Hospital, Toronto, Canada
Antonella Pollo MD, Assistant Professor, Department of Neuroscience, University of Torino Faculty of Pharmacy, Torino, Italy; National Institute of Neuroscience, Torino, Italy
James P. Rathmell MD, Chief, Division of Pain Medicine, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Boston, USA; Associate Professor, Department of Anesthesia, Harvard Medical School, Boston, USA
Jana Sawynok PhD, Professor, Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
Marcus Schiltenwolf MD, Professor, Universität Heidelberg, Stiftung Orthopädische Universitätsklinik, Heidelberg, Germany
Barry J. Sessle Professor and Canada Research Chair, Faculties of Dentistry and Medicine, University of Toronto, Toronto, Canada
Yoram Shir MD, Director Alan Edwards Pain Management Unit, McGill University Health Centre, Montreal, Canada
Christine Short MD FRCPC, Assistant Professor, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Medicine, Division of Physical Medicine and Rehabilitation, Halifax, Nova Scotia, Canada; Department of Surgery, Division of Neurosurgery, Queen Elizabeth II Health Science Center, Halifax, Nova Scotia, Canada
Stephen D. Silberstein MD, Professor of Neurology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, USA
Maureen J. Simmonds PhD PT, Professor and Director, School of Physical and Occupational Therapy, Associate Dean, (Rehabilitation), Faculty of Medicine, McGill University, Montreal, Canada
Blair H. Smith MD MEd FRCGP FRCP Edin, Professor of Primary Care Medicine, University of Aberdeen, Scotland, UK
Dawn A. Sparks DO, Assistant Professor of Anesthesiology, Pain and Pediatrics, Dartmouth Medical School, Hanover, NH; Pain Clinic, Dartmouth-Hitchcock Medical Center, and Pediatric Pain Specialist, Children’s Hospital at Dartmouth (CHad), Lebanon, NH, USA
Boris Specktor MD, Center for Pain Medicine, Massachusetts General Hospital, Boston, USA; Assistant Professor, Department of Anesthesiology, Emory University School of Medicine, Atlanta, USA
Pam Squire MD CCFP CPE, Assistant Clinical Professor, University of British Columbia, Vancouver, Canada
Michael Stanton-Hicks MBBS DrMed FRCA ABPM FIPP, Pain Management Department, Center for Neurological Restoration, Cleveland, USA; Consulting Staff, Children’s Hospital CCF Shaker Campus, Pediatric Pain Rehabilitation Program, Cleveland Clinic, Cleveland, USA; Chair, Department of Palliative Care & Rehabilitation Medicine, University of Texas, Houston, USA
Jennifer N. Stinson RN-EC PhD CPNP, Scientist, Child Health Evaluative Sciences, and Department of Anesthesia and Pain Medicine, The Hospital for Sick Children, Toronto, Canada; Assistant Professor, Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, Canada
Michael J.L. Sullivan PhD, Professor, Department of Psychology, McGill University, Montreal, Canada
Peter Svensson Professor and Chairman, Department of Clinical Oral Physiology, Aarhus University, Aarhus, Denmark; Department of Maxillofacial Surgery, Aarhus University Hospital, Aarhus, Denmark
Frank J. Symons PhD, Associate Professor, Department of Educational Psychology, Center for Neurobehavioral Development, University of Minnesota, Minneapolis, USA
Brian R. Theodore PhD, Department of Anesthesiology & Pain Medicine, University of Washington, Seattle, USA
Rolf-Detlef Treede MD, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
Dennis C. Turk PhD, Department of Anesthesiology & Pain Medicine, University of Washington, Seattle, USA
Judith Versloot PhD, Faculty of Dentistry, Toronto, Canada
Ashwin Viswanthan MD, Instructor, Department of Neurological Surgery, Oregon Health & Science University, Portland, USA
David Walk MD, Associate Professor, Department of Neurology, University of Minnesota, Minneapolis, USA
Mark A. Ware MBBS MRCP(UK) MSc, Assistant Professor, Departments of Anesthesia, Family Medicine, Pharmacology and Therapeutics, McGill University, Montreal, Canada
C. Peter N. Watson MD FRCP(C), Department of Medicine, University of Toronto, Toronto, Canada
Karen Webber MN RN, Associate Professor, School of Nursing, Memorial University of Newfoundland, St. John’s, Canada
Timothy H. Wideman PT, Department of Psychology, McGill University, Montreal, Canada
Amanda C. de C. Williams Reader in Clinical Health Psychology, University College London, London, UK
Lonnie K. Zeltzer MD, Director of Pediatric Pain Program, Mattel Children’s Hospital at UCLA, Los Angeles, USA; Professor of Pediatric Anesthesiology, Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, UCLA, Los Angeles, USA
Part 1: Basic Understanding of Pain Medicine
Chapter 1
The challenge of pain: a multidimensional phenomenon
Mary Lynch1, Kenneth D. Craig2 & Philip W.H. Peng3
1 Dalhousie University, Pain Management Unit, Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia
2 Department of Psychology, University of British Columbia, Vancouver, Canada
3 Department of Anesthesia, Wasser Pain Management Center, Mount Sinai Hospital, University of Toronto, Ontario, Canada
Pain is one of the most challenging problems in medicine and biology. It is a challenge to the sufferer who must often learn to live with pain for which no therapy has been found. It is a challenge to the physician or other health professional who seeks every possible means to help the suffering patient. It is a challenge to the scientist who tries to understand the biological mechanisms that can cause such terrible suffering. It is also a challenge to society, which must find the medical, scientific and financial resources to relieve or prevent pain and suffering as much as possible.
(Melzack & Wall The Challenge of Pain, 1982)
Introduction
The International Association for the Study of Pain (IASP) taxonomy defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage” [1]. Pain is divided into two broad categories: acute pain, which is associated with ongoing tissue damage, and chronic pain, which is generally taken to be pain that has persisted for longer periods of time. Many injuries and diseases are capable of instigating acute pain with sources including mechanical tissue damage, inflammation and tissue ischemia. Similarly, chronic pain can be associated with other chronic diseases, terminal illness, or may persist after illness or injury. The point at which chronic pain can be diagnosed may vary with the injury or condition that initiated it; however, for most conditions, pain persisting beyond 3 months is reasonably described as a chronic pain condition. In some cases one can identify a persistent pain condition much earlier, for example, in the case of post-herpetic neuralgia subsequent to an attack of shingles, if pain persists beyond rash healing it indicates a persistent or chronic pain condition is present.
Exponential growth in pain research in the past four decades has increased our understanding regarding underlying mechanisms of the causes of chronic pain, now understood to involve a neural response to tissue injury. In other words, peripheral and central events related to disease or injury can trigger long-lasting changes in peripheral nerves, spinal cord and brain such that the system becomes sensitized and capable of spontaneous activity or of responding to non-noxious stimuli as if painful. By such means, pain can persist beyond the point where normal healing takes place and is often associated with abnormal sensory findings. In consequence, the scientific advances are providing a biological basis for understanding the experience and disabling impact of persistent pain. Table 1.1 presents definitions of pain terms relevant to chronic pain.
Table 1.1 Definitions of pain terms.
Source: Based on Merskey H, Bogduk N, eds. (1994) Classification of Chronic Pain, Descriptions of Chronic Pain Syndromes and Definitions of Pain Terms, 2nd edn. Task Force on Taxonomy, IASP Press, Seattle.
| Allodynia | Pain due to a stimulus that does not normally provoke pain |
| Anesthesia dolorosa | Pain in a region that is anesthetic dolorosa |
| Dysesthesia | An unpleasant abnormal sensation, whether spontaneous or evoked |
| Hyperalgesia | An increased response to a stimulus that is normally painful |
| Hyperpathia | A painful syndrome characterized by an abnormally painful reaction to a stimulus, especially a repetitive stimulus as well as an increased threshold |
| Neuropathic | Pain initiated or caused by a primary pain lesion or dysfunction in the nervous system |
| Nociceptor | A receptor preferentially sensitive to a noxious stimulus or to a stimulus that would become noxious if prolonged |
| Pain | An unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage |
| Paresthesia | An abnormal sensation, whether spontaneous or evoked (use dysesthesia when the abnormal sensation is unpleasant) |
Traditionally, clinicians have conceptualized chronic pain as a symptom of disease or injury. Treatment was focused on addressing the underlying cause with the expectation that the pain would then resolve. It was thought that the pain itself could not kill. We now know that the opposite is true. Pain persists beyond injury and there is mounting evidence that “pain can kill.” In addition to contributing to ongoing suffering, disability and diminished life quality, it has been demonstrated that uncontrolled pain compromises immune function, promotes tumor growth and can compromise healing with an increase in morbidity and mortality following surgery [2,3], as well as a decrease in the quality of recovery [4]. Clinical studies suggest that prolonged untreated pain suffered early in life may have long-lasting effects on the individual patterns of stress hormone responses. These effects may extend to persistent changes in nociceptive processing with implications for pain experienced later in life [5]. Chronic pain is associated with the poorest health-related quality of life when compared with other chronic diseases such as emphysema, heart failure or depression and has been found to double the risk of death by suicide compared to controls [6]. Often chronic pain causes more suffering and disability than the injury or illness that caused it in the first place [7]. The condition has major implications not only for those directly suffering, but also family and loved ones become enmeshed in the suffering person’s challenges, the work place suffers through loss of productive employees, the community is deprived of active citizens and the economic costs of caring for those suffering from chronic pain are dramatic.
Chronic pain is an escalating public health problem which remains neglected. Alarming figures demonstrate that more than 50% of patients still suffer severe intolerable pain after surgery and trauma [8]. Inadequately treated acute pain puts people at higher risk of developing chronic pain. For example, intensity of acute postoperative pain correlates with the development of persistent postoperative pain, which is now known to be a major and under-recognized health problem. The prevalence of chronic pain subsequent to surgery has been found in 10–50% of patients following many commonly performed surgical procedures and in 2–10% this pain can be severe [9].
The epidemiology of chronic pain has been examined in high-quality surveys of general populations from several countries which have demonstrated that the prevalence of chronic pain is at least 18–20% [10–12]. These rates will increase with the aging of the population. In addition to the human suffering inflicted by pain there is also a large economic toll. Pain accounts for over 20% of doctor visits and 10% of drug sales and costs developed countries $1 trillion each year [13].
Chronic pain has many characteristics of a disease epidemic that is silent yet growing; hence addressing it is imperative. It must be recognized as a multidimensional phenomenon involving biopsychosocial aspects. Daniel Carr, in a recent IASP Clinical Updates, expressed it most succinctly: “The remarkable restorative capacity of the body after common injury … is turned upside down (and) hyperalgesia, disuse atrophy, contractures, immobility, fear-avoidance, helplessness, depression, anxiety, catastrophizing, social isolation, and stigmatization are the norm” [14].
Such is the experience and challenge of chronic pain and it is up to current and future generations of clinicians to relieve or prevent pain and suffering as much as possible. The challenges must be confronted at biological, psychological and social levels. Not only is a better understanding needed, but reforms of caregiving systems that address medical, psychological and health service delivery must be undertaken.
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