`
`
`
`CLASSIFICATION OF CHRONIC PAIN
`
`i
`
`
`
`Grun. Exh. 1022
`PGR for U.S. Patent No. 9,867,839
`
`1
`
`Grün. Exh. 1020
`PGR for U.S. Patent No. 10,052,338
`
`

`

`
`
`
`
`IASP Subcommittee on Taxonomy 1986
`*Harold Merskey, DM (Canada, Chair)
`*Michael R. Bond, PhD, MD (UK)
`John J. Bonica, MD, DSc (USA)
`*David B. Boyd, MD (Canada)
`Amiram Carmon, MD, PhD (Israel)
`A. Barry Deathe, MD (Canada)
`Henri Dehen, MD (France)
`Ulf Lindblom, MD (Sweden)
`James M. Mumford, PhD, MSc (UK)
`William Noordenbos, MD, PhD (The Netherlands)
`Ottar Sjaastad, MD, PhD (Norway)
`Richard A. Sternbach, PhD (USA)
`Sydney Sunderland, MD, DSc (Australia)
`
`*Subcommittee on Classification
`
`IASP Task Force on Taxonomy 1994
`Harold Merskey, DM (Canada, Chair)
`Robert G. Addison, MD (USA)
`Aleksandar Beric, MD, DSc (USA)
`Helmut Blumberg, MD (Germany)
`Nikolai Bogduk, MD, PhD (Australia)
`Jorgen Boivie, MD (Sweden)
`Michael R. Bond, PhD, MD (UK)
`John J. Bonica, MD, DSc (USA)
`David B. Boyd, MD (Canada)
`A. Barry Deathe, MD (Canada)
`Marshall Devor, PhD (Israel)
`Martin Grabois, MD (USA)
`Jan M. Gybels, MD, PhD (Belgium)
`Per T. Hansson, MD, DMSc, DDS (Sweden)
`Troels S. Jensen, MD, PhD (Denmark)
`John D. Loeser, MD (USA)
`Prithvi P. Raj, MB BS (USA)
`John W. Scadding, MD, MB BS (UK)
`Ottar M. Sjaastad, MD, PhD (Norway)
`Erik Spangfort, MD (Sweden)
`Barrie Tait, MB ChB (New Zealand)
`Ronald R. Tasker, MD (Canada)
`Dennis C. Turk, PhD (USA)
`Arnoud Vervest, MD (The Netherlands)
`James G. Waddell, MD (USA)
`Patrick D. Wall, DM, FRS (UK)
`C. Peter N. Watson, MD (Canada)
`
`ii
`
`2
`
`

`

`
`
`CLASSIFICATION OF CHRONIC PAIN
`DESCRIPTIONS OF CHRONIC PAIN SYNDROMES
`AND DEFINITIONS OF PAIN TERMS
`Second Edition
`
`prepared by the
`Task Force on Taxonomy
`of the
`International Association for the Study of Pain
`
`Editors
`Harold Merskey, DM
`Department of Psychiatry
`The University of Western Ontario
`Department of Research
`London Psychiatric Hospital
`London, Ontario, Canada
`
`Nikolai Bogduk, MD, PhD
`Faculty of Medicine
`The University of Newcastle
`Newcastle, New South Wales, Australia
`
`IASP PRESS • SEATTLE
`
`iii
`
`3
`
`

`

`
`
`© 1994 IASP Press (Reprinted 2002)
`International Association for the Study of
`Pain
`
`All rights reserved. No part of this publication may be reproduced, stored in a
`retrieval system, or transmitted, in any form or by any means, electronic,
`mechanical, photocopying, recording, or otherwise, without the prior written
`permission of the publisher.
`
`No responsibility is assumed by IASP for any injury and/or damage to persons or
`property as a matter of product liability, negligence, or from any use of any
`methods, products, instruction, or ideas contained in the material herein. Because
`of the rapid advances in the medical sciences, the publisher recommends that there
`should be independent verification of diagnoses and drug dosages.
`
`Library of Congress Cataloging-in-Publication Data
`
`Classification of chronic pain : descriptions of chronic pain syndromes and
`definitions of pain terms / prepared by the International Association for the
`Study of Pain, Task Force on Taxonomy ; editors, Harold Merskey,
`N. Bogduk. - 2nd ed.
`p.
`cm.
`Includes bibliographical references and
`index. ISBN 0-931092-05-1
`1. Chronic pain-Classification. 2. Pain-Terminology.
`I. Merskey, Harold. II. Bogduk, Nikolai. III. International Association for
`the Study of Pain. Task Force on Taxonomy.
`[DNLM: 1. Pain-classification. 2. Chronic Disease-classification.
`WL 704 C614 19941
`RB127.C58 1994
`616'.0472'012-dc20
`DNLM/DLC
`for Library of Congress 94-8062
`
`IASP Press
`International Association for the Study of
`Pain 909 NE 43rd St., Suite 306
`Seattle, WA 98105 USA
`Fax: 206-547-1703
`www.iasp-pain.org
`www.painbooks.org
`
`Printed in the United States of America
`
`iv
`
`4
`
`

`

`
`
`CONTENTS
`
`Combined List of Contributors to First and Second Editions
`Introduction
`Future Revisions
`Abbreviations
`
`Part I Topics and Codes
`Scheme for Coding Chronic Pain Diagnoses
`List of Topics and Codes
`A. Relatively Generalized Syndromes
`B. Relatively Localized Syndromes of the Head and Neck
`C. Spinal Pain, Section 1: Spinal and Radicular Pain Syndromes
`Note on Arrangements
`Definitions of Spinal Pain and Related Phenomena
`Principles
`Radicular Pain and Radiculopathy
`D. Spinal Pain, Section 2: Spinal and Radicular Pain Syndromes of the Cervical
`and Thoracic Regions
`E. Local Syndromes of the Upper Limbs and Relatively Generalized
`Syndromes of the Upper and Lower Limbs
`F. Visceral and Other Syndromes of the Trunk Apart from Spinal and
`Radicular Pain
`G. Spinal Pain, Section 3: Spinal and Radicular Pain Syndromes of the Lumbar,
`Sacral, and Coccygeal Regions
`H. Local Syndromes of the Lower Limbs
`
`Part II Detailed Descriptions of Pain Syndromes
`List of Items Usually Provided in Detailed Descriptions of Pain Syndromes
`A. Relatively Generalized Syndromes
`I. Relatively Generalized Syndromes
`B. Relatively Localized Syndromes of the Head and Neck
`II. Neuralgias of the Head and Face
`III. Craniofacial Pain of Musculoskeletal Origin
`IV. Lesions of the Ear, Nose, and Oral Cavity
`V. Primary Headache Syndromes, Vascular Disorders, and
`Cerebrospinal Fluid Syndromes
`Headache Crosswalk
`VI. Pain of Psychological Origin in the Head, Face, and Neck
`VII. Suboccipital and Cervical Musculoskeletal Disorders
`VIII. Visceral Pain in the Neck
`
`
`
`vii
`ix
`xvi
`xvi
`
` 1
`3
`5
`6
`8
`11
`11
`11
`14
`15
`17
`
`23
`
`25
`
`29
`
`36
`
`37
`38
`39
`39
`59
`59
`68
`72
`77
`
`90
`93
`93
`98
`
`
`
`
`
`
`
`v
`
`5
`
`

`

`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`C. Spinal Pain, Section 1: Spinal and Radicular Pain Syndromes
`D. Spinal Pain, Section 2: Spinal and Radicular Pain Syndromes of the Cervical
`and Thoracic Regions
`IX. Cervical Spinal or Radicular Pain Syndromes
`X. Thoracic Spinal or Radicular Pain Syndromes
`E. Local Syndromes of the Upper Limbs and Relatively Generalized
`Syndromes of the Upper and Lower Limbs
`XI. Pain in the Shoulder, Arm, and Hand
`XII. Vascular Disease of the Limbs
`XIII. Collagen Disease of the Limbs
`XIV. Vasodilating Functional Disease of the Limbs
`XV. Arterial Insufficiency in the Limbs
`XVI. Pain of Psychological Origin in the Lower Limbs
`F. Visceral and Other Syndromes of the Trunk Apart from Spinal and
`Radicular Pain
`XVII. Visceral and Other Chest Pain
`XVIII. Chest Pain of Psychological Origin
`XIX. Chest Pain Referred from Abdomen or Gastrointestinal Tract
`XX. Abdominal Pain of Neurological Origin
`XXI. Abdominal Pain of Visceral Origin
`XXII. Abdominal Pain Syndromes of Generalized Diseases
`XXIII. Abdominal Pain of Psychological Origin
`XXIV. Diseases of the Bladder, Uterus, Ovaries, and Adnexa
`XXV. Pain in the Rectum, Perineum, and External Genitalia
`G. Spinal Pain, Section 3: Spinal and Radicular Pain Syndromes of the Lumbar,
`Sacral, and Coccygeal Regions
`XXVI. Lumbar Spinal or Radicular Pain Syndromes
`XXVII. Sacral Spinal or Radicular Pain Syndromes
`XXVIII. Coccygeal Pain Syndromes
`XXIX. Diffuse or Generalized Spinal Pain
`XXX. Low Back Pain of Psychological Origin with Spinal Referral
`H. Local Syndromes of the Lower Limbs
`XXXI. Local Syndromes in the Leg or Foot: Pain of Neurological Origin
`XXXII. Pain Syndromes of the Hip and Thigh of Musculoskeletal Origin
`XXXIII. Musculoskeletal Syndromes of the Leg
`
`Part III Pain Terms: A Current List with Definitions and Notes on Usage
`
`Index
`
`vi
`
`101
`103
`
`103
`112
`121
`
`121
`128
`131
`132
`134
`136
`137
`
`137
`145
`146
`149
`151
`160
`163
`163
`172
`175
`
`175
`187
`191
`192
`195
`197
`197
`204
`205
`
`207
`
`215
`
`6
`
`

`

`
`
`COMBINED LIST OF CONTRIBUTORS
`TO FIRST AND SECOND EDITIONS
`
`D.C. Agnew
`Pasadena, CA, USA
`
`M. Backonja
`Madison, WI, USA
`
`H.J.M. Barnett
`London, ON, Canada
`
`P. Barton
`Calgary, AL, Canada
`
`R.W. Beard
`London, England, UK
`
`W.E. Bell *
`Dallas, TX, USA
`
`J.N. Blau
`London, England, UK
`
`L.M. Blendis
`Toronto, ON, Canada
`
`R.A. Boas
`Auckland, New Zealand
`
`N. Bogduk
`Newcastle, NSW, Australia
`
`J. Boivie
`Linkoping, Sweden
`
`M.R. Bond
`Glasgow, Scotland, UK
`
`J.J. Bonica
`Seattle, WA, USA
`
`D.B. Boyd
`London, ON, Canada
`
`R.I. Brooke
`London, ON, Canada
`
`G.W. Bruyn
`Leuven, Belgium
`
`J.G. Cairncross
`London, ON, Canada
`
`A. Carmon
`Jerusalem, Israel
`
`J.E. Charlton
`Newcastle upon Tyne, England, UK
`
`M.J. Cous ins
`St. Leonards, NSW, Australia
`
`A.B. Deathe
`London, ON, Canada
`
`S. Diamond
`Chicago, IL, USA
`
`M.B. Dresser
`Chicago, IL, USA
`
`R.J. Evans
`Toronto, ON, Canada
`
`T. Feasby
`London, ON, Canada
`
`C. Feinmann
`London, England, UK
`
`W. Feldman
`Halifax, NS, Canada
`
`H.L. Fields
`San Francisco, CA, USA
`
`N.L. Gittleson
`Sheffield, England, UK
`
`J.M. Gregg
`Blacksburg, VA, USA
`
`M. Grushka
`Toronto, ON, Canada
`
`J.M. Gybels
`Leuven, Belgium
`
`A. Hahn
`London, ON, Canada
`
`P. Hansson
`Stockholm, Sweden
`
`vii
`
`P.A.J. Hardy
`Gloucester, England, UK
`
`M. Harris
`London, England, UK
`
`M. Inwood
`London, ON, Canada
`
`G.W. Jamieson
`London, ON, Canada
`
`F.W.L. Kerr
`Rochester, MN, USA
`
`I. Klineberg
`Sydney, NSW, Australia
`
`T. Komusi
`St. John's, NF, Canada
`
`D. W. Koopman
`Leiden, The Netherlands
`
`L. Kudrow
`Encino, CA, USA
`
`P.L. LeRoy
`Wilmington, DE, USA
`
`U. Lindblom
`Stockholm, Sweden
`
`S. Lipton
`Liverpool, England, UK
`
`J.D. Loeser
`Seattle, WA, USA
`
`D.M. Long
`Baltimore, MD, USA
`
`D.G. Machin
`Liverpool, England, UK
`
`G. Magni
`Paris, France
`
`A. Mailis
`Toronto, ON, Canada
`
`7
`
`

`

`
`
`
`
`J. Marbach
`New York, NY, USA
`
`G. J. Mazars
`Paris, France
`
`P. McGrath
`Halifax, NS, Canada
`
`M. Mehta
`Norwich, England, UK
`
`J. Miles
`Liverpool, England, UK
`
`N. Mohl
`Buffalo, NY, USA
`
`F. Mongini
`Turin, Italy
`
`D. Moulin
`London, ON, Canada
`
`J.A. Mountifield
`Toronto, ON, Canada
`
`J.M. Mumford
`Liverpool, England, UK
`
`J. W. Scadding
`London, England, UK
`
`B. Sessle
`Toronto, ON, Canada
`
`J. Shennan
`Liverpool, England, UK
`
`F. Sicuteri
`Florence, Italy
`
`0. Sjaastad
`Trondheim, Norway
`
`A.E. Sola
`Seattle, WA, USA
`
`E. Spangfort
`Huddinge, Sweden
`
`F.G. Spear
`Sheffield, England, UK
`
`R.H. Spector
`Chicago, IL, USA
`
`D.M. Spengler
`Nashville, TN, USA
`
`W. Noordenbos *
`Amsterdam, The Netherlands
`
`J. Spierdijk
`Leiden, The Netherlands
`
`C. Pagni
`Turin, Italy
`
`I. Papo
`Ancona, Italy
`
`C.W. Parry
`London, England, UK
`
`P. Procacci
`Florence, Italy
`
`A. Rapoport
`Stamford, CT, USA
`
`M. Renaer
`Leuven, Belgium
`
`W.J. Roberts
`Portland, OR, USA
`
`
`
`E.L.H. Spierings
`Boston, MA, USA
`
`R.A. Sternbach
`La Jolla, CA, USA
`
`L.-J. Stovner
`Trondheim, Norway
`
`A. Struppler
`Munich, West Germany
`
`Sir S. Sunderland *
`Melbourne, VIC, Australia
`
`M. Swerdlow
`Manchester, England, UK
`
`W.H. Sweet
`Boston, MA, USA
`
`viii
`
`B. Tait
`Christchurch, New Zealand
`
`R.R. Tasker
`Toronto, ON, Canada
`
`M. Trimble
`London, England, UK
`
`E. Tunks
`Hamilton, ON, Canada
`
`F. Turnbull
`Baltimore, MD, USA
`
`G.S. Tyler
`Scottsdale, AZ, USA
`
`J. Van Hees
`Leuven, Belgium
`
`A.C.M. Vervest
`Sneek, The Netherlands
`
`A.P.E. Vielvoye-Kerkmeer
`Leiden, The Netherlands
`
`P. Walker
`Toronto, ON, Canada
`
`H. Wallach
`London, ON, Canada
`
`C.P.N. Watson
`Toronto, ON, Canada
`
`M.V. Wells
`Campbell River, BC, Canada
`
`F. Wolfe
`Wichita, KS, USA
`
`K.J. Zilkha
`London, England, UK
`
`D. Zohn
`McLean, VA, USA
`
`* Deceased
`
`
`
`8
`
`

`

`
`
`INTRODUCTION
`
`“You are not obliged to complete the work,
`but neither are you free to desist from it.”
`—Rabbi Tarphon, Talmud, Avot, 2:21
`
`
`The first two, and largest, parts of this volume
`contain explanatory material and a collection of de-
`scriptions of syndromes. These parts have been up-
`dated from the first edition. In the third part, the
`opportunity has been taken now, as before, to present
`some definitions of pain terms that were published
`previously in Pain and revised in 1986. Two new
`terms have been added
`to
`these definitions—
`Neuropathic Pain and Peripheral Neuropathic Pain—
`and the definition of Central Pain has been altered
`accordingly. Small changes have also been made in
`the notes on Allodynia and Hyperalgesia. Notes on
`the terms Sympathetically Maintained Pain and
`Sympathetically Independent Pain have also been
`introduced in a separate section, in connection with
`revised descriptions of what were formerly called
`Reflex Sympathetic Dystrophy and Causalgia and are
`now called Complex Regional Pain Syndromes,
`Types I and II, respectively.
`The list of those who have contributed with drafts
`or with revisions of drafts precedes this introduction.
`Some have provided descriptions of a syndrome or
`comments on it; others have described a whole group
`or groups of syndromes. Some have also made theo-
`retical contributions in working out how we should
`proceed. Dr. John J. Bonica, in particular, was in-
`strumental in providing ideas from which the present
`volume has grown. Many contributors gave substan-
`tial portions of their time to the work. The range of
`contributions was such that it would be impossible to
`set up a precise scale of gratitude in proportion to the
`different amounts of help given, but the editors be-
`lieve they can express thanks to all contributors, not
`only from the Task Force on Taxonomy of the Inter-
`national Association for the Study of Pain (IASP), but
`on behalf of the association as a whole.
`In addition, Ms. Louisa E. Jones, Executive Offi-
`cer, IASP, Mrs. J. Duncan, Mrs. C. Hanas, Ms. G.
`Hudson, and Ms. P. Serratore have been unfailingly
`patient and helpful in the production of the manu-
`script and in the associated correspondence over sev-
`eral years. Ms. Mai Why, M.L.S., provided much
`bibliographical assistance. Mr. Bryan Urakawa un
`
`
`
`
`
`dertook the difficult task of merging the old and new
`material in an updated text. The production editor,
`Ms. Leslie Nelson Bond, has made detailed improve-
`ments to the wording and helped to establish the new
`format.
`In the first edition it was observed that the vol-
`ume was provisional. It contained gaps and, no doubt,
`some inaccuracies and inconsistencies. Its printing
`and distribution, however, marked the end of a stage
`in what is fundamentally a continuous process or se-
`quence of scientific endeavor. It was offered as a pro-
`visional compilation for scrutiny and correction by all
`who have the expertise and the will to devote some
`effort to developing this statement of our existing
`knowledge of pain syndromes. Everyone who read it
`was invited to check it within his or her own field of
`knowledge for completeness and accuracy and to send
`any recommendations for additions or corrections to
`the chairperson of the Subcommittee on Taxonomy
`(now the Task Force on Taxonomy). The same invita-
`tion accompanies this edition, which in its turn should
`undergo development and modification.
`
`THE NEED FOR A TAXONOMY
`
`
`The need for a taxonomy was expressed in 1979
`by Bonica, who observed: “The development and
`widespread adoption of universally accepted defini-
`tions of terms and a classification of pain syndromes
`are among the most important objectives and respon-
`sibilities of the IASP. It is possible to define terms
`and develop a classification of pain syndromes which
`are acceptable to many, albeit not all, readers and
`workers in the field; even if the adopted definitions
`and classifications are not perfect they are better than
`the Tower of Babel conditions that currently exist;
`adoption of such classification does not mean that it is
``fixed’ for all time and cannot be modified as we ac-
`quire new knowledge; and, the adoption of such tax-
`onomy with the condition that it can be modified will
`encourage its use widely by those who may disagree
`with some part of the classification. This in fact has
`been the experience and chronology of such widely
`
`ix
`
`9
`
`

`

`
`
`accepted classifications as those pertaining to heart
`disease, hypertension, diabetes, toxemia of preg-
`nancy, psychiatric disorders, and a host of others. I
`hope therefore that all IASP members will cooperate
`and use the classification of pain syndromes after this
`is adopted by IASP to improve our communications
`systems. This will require that they be incorporated in
`the spoken and written transfer of information, par-
`ticularly scientific papers, books, etc., and in the de-
`velopment of research protocols, clinical records, and
`data banks for the storage and retrieval of research
`and clinical data.”
`It calls for very little special knowledge, actually,
`to recognize that we could benefit from a classifica-
`tion of chronic pain syndromes. The need arises be-
`cause specialists from different disciplines all require
`a framework within which to group the conditions
`that they are treating. This framework should enable
`them to order their own data, identify different dis-
`eases or syndromes, and compare their experience and
`observations with those of others. Studies of epidemi-
`ology, etiology, prognosis, and treatment all depend
`upon the ability to classify clinical events in an agreed
`pattern. The delivery of medical services is also facili-
`tated if both the type and number of conditions and
`patients to be treated can be established in a system-
`atic fashion. In some centers, payment by insurance
`companies for medical care of the insured creates a
`demand for a classification system.
`In regard to chronic pain, it is important to estab-
`lish such a system of classification that goes beyond
`what is available in the general international systems
`such as the International Classification of Diseases.
`The need is not to replace but to supplement the new
`ICD-10. Specialist workers in various fields usually
`require a more detailed structure for classification
`than is provided by the overall system. The Ad Hoc
`Committee on Headache of the American Medical
`Association developed such an extensive system for
`one set of pain syndromes (Friedman et al. 1962), and
`the International Headache Society has now replaced
`that with another for headache disorders, cranial neu-
`ralgias, and facial pains (IHS 1988). Stroke has
`brought forth a schedule of its own (Capildeo et al.
`1977), the American Rheumatism Association (1973)
`has produced its own system with criteria for diagno-
`sis, hematologists have continuously developed the
`numbering of clotting factors, and so forth. In the
`field of chronic pain, two requirements spring readily
`to mind. The first is that we should be able to identify
`all the chronic pain syndromes we encounter. The
`second is that we should have as good a description of
`
`x
`
`each as can be obtained, at least with respect to the
`pain. It would be expecting too much and also would
`probably be unnecessary to hope for a complete text-
`book description. But the members of the IASP
`should obviously be the most suitable experts to de-
`scribe in full the pains of the syndromes we so often
`seek to relieve. Accordingly, a classification system
`for pain syndromes has been attempted which, with-
`out being a textbook, will provide standard descrip-
`tions of all the relevant pain syndromes and a means
`toward codifying them.
`The present descriptions and coding systems have
`been developed in the light of the above considera-
`tions. They should allow the standardization of obser-
`vations by different workers and the exchange of
`information. In the first edition it was remarked that
`when articles began to appear that used them as a
`point of reference, they would have achieved their
`first aim, and that if other articles emerged that re-
`vised or criticized them, they would be achieving
`their second aim, which was to stimulate a continuing
`effort at updating and improvement. Both these de-
`velopments occurred, but more revisions have been
`generated internally within the Task Force on Taxon-
`omy, or in response to communications from mem-
`bers of the IASP. In the spirit of the quotation at the
`head of this introduction, the work will still not be
`complete and it will not be interrupted.
`
`THE NATURE OF CLASSIFICATION
`
`
`Reassurance may be needed for those who feel
`that the classification should reflect some sort of ul-
`timate truth and universal consistency. It is indeed
`correct that classifications should be true, at least so
`far as we know, but complete consistency is beyond
`the hopes of any medical system of classification. In
`an ideal system of classification, the categories should
`be mutually exclusive and completely exhaustive in
`regard to the data to be incorporated. The classifica-
`tion should also use one principle alone. No classifi-
`cation in medicine has achieved such aims, nor can it
`be expected to do so (Merskey 1983). Classification
`in medicine is a pragmatic affair, and we may con-
`sider briefly how classifications can be devised. Clas-
`sifications may be natural if they reflect or presume to
`reflect an order of nature. Alternatively, they may be
`artificial but convenient. The simplest type of classifi-
`cation into animate or inanimate objects is a natural
`one. An extreme example of an artificial classification
`is provided by a telephone directory (Galbraith and
`
`10
`
`

`

`
`
`Wilson 1966). The sequence of letters of the alphabet
`is used as the criterion for classification. That se-
`quence bears little or no relation to the contents that it
`arranges, namely the people, their addresses, and their
`telephone numbers. By contrast, a phylogenetic clas-
`sification by evolutionary relationships is a very supe-
`rior form of classification. Impressive natural and
`phylogenetic classifications exist in chemistry, bot-
`any, and zoology.
`Things are very different in medicine. In the
`ICD10, conditions are classified by causal agent, e.g.,
`infectious diseases or neoplasm; by systems of the
`body, e.g., gastrointestinal or genito-urinary; by sys-
`tem pattern and type of symptom, as in psychiatric
`illnesses; and by whether or not they are related to the
`artificial intervention of an operation. They may be
`grouped by time of occurrence, such as congenital
`anomalies or conditions originating in the perinatal
`period, or even grouped as symptoms, signs, and ab-
`normal clinical and laboratory findings. There is a
`code (080) for delivery in a completely normal case,
`including spontaneous breech delivery. Within major
`groups there are subdivisions by (a) symptom pattern,
`such as epilepsy or migraine; (b) the presence of he-
`reditary or degenerative disease, e.g., Huntington’s
`disease and hereditary ataxia; (c) extrapyramidal and
`movement disorders, e.g., Parkinson’s disease and
`dystonia; (d) location, e.g., polyneuropathies and
`other disorders of the peripheral nervous system; and
`(e) infectious causes, e.g., meningitis. Overlapping
`occurs repeatedly in such approaches to categoriza-
`tion. Pain appears in the group of symptoms, signs,
`and abnormal clinical and laboratory findings as R52
`Pain Not Elsewhere Classified. This code excludes
`some 19 other labels that reflect pain in different parts
`of the body and also “psychogenic” pain (F45.4) and
`renal colic (N23). Thus pain occurs at various levels
`of diagnosis and categorization in the ICD-10. In a
`sense this is inevitable. There must always be some
`provision for conditions that are not well described
`and which will overlap with others that are well de-
`scribed.
`Operational considerations often have to be em-
`ployed in classification, and indeed operational defi-
`nitions are implicit in most classification activities in
`medicine. These definitions will suit one purpose and
`not another. Thus, in psychiatry we may diagnose
`operationally from biochemistry (phenylketonuria),
`serology (general paresis), genetics (Huntington’s
`chorea), symptom pattern (schizophrenia, depression),
`mechanisms and site (tension headache), and even the
`presence or absence of irrationality (psychosis, neuro-
`
`xi
`
`sis). With regard to internal medicine, the same ap-
`plies. It has been said that “acute nephritis” may be
`diagnosed on the basis of etiology, pathogenesis, his-
`tology, or clinical presentation (Houston et al. 1975).
`Pain syndromes are distinguished particularly often
`on the basis of duration, site, and pattern, some of
`which are frequently similar to different conditions.
`Accordingly, we can aim only at practical categories,
`largely defined operationally, but these can neverthe-
`less be very useful. For some further consideration of
`this see Merskey (1983). Here we have aimed espe-
`cially at describing chronic pain syndromes and at
`coding them.
`
`THE PRESENT CLASSIFICATION
`
`
`It has been mentioned that the present volume is
`not a textbook. Instead it deals with syndromes of
`chronic pain. Chronic pain has gradually emerged as a
`distinct phenomenon in comparison with acute pain.
`First, studies were undertaken that explored the spe-
`cial features of patients with persistent pain. Later,
`specific emphasis was given to the distinction be-
`tween the two situations (Sternbach 1974). Chronic
`pain has been recognized as that pain which persists
`past the normal time of healing (Bonica 1953). In
`practice this may be less than one month, or more
`often, more than six months. With nonmalignant pain,
`three months is the most convenient point of division
`between acute and chronic pain, but for research pur-
`poses six months will often be preferred. Those who
`treat cancer pain find that three months is sometimes
`too long to wait before regarding a pain as chronic.
`Moreover, the definition related to the time of normal
`healing is not sufficient, nor is it honored consis-
`tently. Many syndromes are treated as examples of
`chronic pain although normal healing has not oc-
`curred. Pain that persists for a given length of time
`would be a simpler concept. This length of time is
`determined by common medical experience. In the
`first instance it is the time needed for inflammation to
`subside, or for acute injuries such as lacerations or
`incisions to repair with the union of separated tissues.
`A longer period is required if we wait for peripheral
`nerves to grow back after trauma. In these circum-
`stances, chronic pain is recognized when the process
`of repair is apparently ended. Some repair, for exam-
`ple, the thickening of a scar in the skin and its chang-
`ing color from pink (or dark) to white (or less dark),
`may be painless. Other repair may never be complete;
`for example, neuromata in an amputation stump con-
`
`11
`
`

`

`
`
`stitute a permanent failure to heal that may be a site of
`persistent pain. Scar tissue around a nerve may be
`fully healed but can still act as a persistent painful
`lesion.
`Many syndromes are treated as examples of
`chronic pain although it is well recognized that nor-
`mal healing has not occurred. These include rheuma-
`toid arthritis, osteoarthritis, spinal stenosis, nerve
`entrapment syndromes, and metastatic carcinoma.
`Others, such as persistent migraine, remit or heal and
`then recur. Moreover, the increasing knowledge about
`plasticity of the nervous system (Wall 1989) in re-
`sponse to injury indicates that CNS changes may pro-
`long and maintain pain long after the usual time of
`response to acute lesions. Such changes can make it
`difficult to say that normal healing has taken place.
`Other less obvious failures to heal can last indefi-
`nitely (Macnab 1964, 1973); some of these lesions are
`not detectable even by modern imaging techniques
`(Taylor and Kakulas 1991) but will still give rise to
`persistent chronic pain. Chronic pain thus remains
`important, even if we must understand it slightly dif-
`ferently as a persistent pain that is not amenable, as a
`rule, to treatments based upon specific remedies, or to
`the routine methods of pain control such as non-
`narcotic analgesics. Given that there are so many dif-
`ferences in what may be regarded as chronic pain, it
`seems best to allow for flexibility in the comparison
`of cases and to relate the issue to the diagnosis in par-
`ticular situations. As it happens, the coding system
`has always allowed durations to be entered as less
`than one month, one month to six months, and more
`than six months. This is probably the best solution for
`the purpose of comparing data within a diagnostic
`category, or even between some diagnoses.
`In this volume only a small number of acute pain
`syndromes is included. Some are of theoretical impor-
`tance or are helpful in pointing out a contrast (e.g.,
`acute tension headache versus chronic tension head-
`ache) or are recurrent. Conditions have been selected
`where pain is prominent and pain management is also
`a leading problem-for example, causalgia. Sometimes,
`as with spinal stenosis, the main problem with the
`chronic syndrome is to recognize it reasonably early.
`After that, the treatment is specific and not one of
`pain management per se. Syndromes or states that do
`not meet one of the above characteristics are omitted.
`Thus, thyroiditis, which can be very painful, is not
`included, because its recognition and treatment are
`not usually problems for pain experts and do not pre-
`sent a major problem in acute pain management.
`Similarly, cerebral tumor is excluded because pain
`
`associated with it is not a focus of attention once the
`patient has consulted a physician or surgeon and the
`condition has been properly diagnosed. Other condi-
`tions, like facet tropism, are included because they
`reflect the existence of a condition that may or may
`not be painless.
`After quite protracted discussion and correspon-
`dence, it was agreed that there were a number of pain
`syndromes that were best seen as generalized condi-
`tions, for example, peripheral neuropathy or radiculo-
`pathy, causalgia and reflex dystrophies (now called
`complex regional pain syndromes), central pain,
`stump pain and phantom pain, and pain purely of psy-
`chological origin. The majority of pain conditions,
`even including some of the foregoing, have a fairly
`specific localization, albeit such localization may be
`in different parts of the body at different times. A root
`lesion may be anywhere along the spinal column, and
`postherpetic neuralgia may affect any dermatome.
`Nevertheless, it seemed worthwhile to divide the de-
`scriptions of pain into two groups. First a smaller one,
`in which there is recognition of a general phenome-
`non that can affect various parts of the body, and sec-
`ond, a very much larger group, in which the
`syndromes are described by location. As a result,
`there is some repetition and redundancy in descrip-
`tions of syndromes in the legs which appear also in
`the arms, or in descriptions of syndromes in abdomi-
`nal nerve roots which appear in cervical nerve roots.
`The present arrangement has been adopted be-
`cause it offers a particular advantage. That advantage
`stems from the fact that the majority of pains of
`which patients complain are commonly described first
`by the physician in terms of region and only later in
`terms of etiology. An arrangement by site provides
`the best practical system for coding the majority of
`pains dealt with by experts in the field. After thor-
`ough discussion, the original Subcommittee on Tax-
`onomy
`therefore agreed
`that
`the majority of
`syndromes would be described in this fashion.
`The descriptions were elicited by sending out re-
`quests to appropriate colleagues, of whom enough
`replied to get this work underway. The pattern of de-
`scriptions requested was systematic. Although ini-
`tially it did not begin with a request for a definition,
`this was added later. Each syndrome then was to be
`described in terms of the following items: definition;
`site; system involved; main features of the pain in-
`cluding its prevalence, age of onset, sex ratio if
`known, duration, severity, and quality; associated
`features; factors providing relief; signs characteristic
`of the condition; usual course; complications; social
`
`xii
`
`12
`
`

`

`
`
`and physical disabilities; specific laboratory findings
`on investigations; pathology; treatment where it was
`very special to the case; the diagnostic criteria if pos-
`sible; differential diagnosis; and finally, the code. For
`this edition criteria have been sought for a variety of
`the conditions.
`Emphasis was placed on the description of the
`pain. By contrast, this volume cannot provide a guide
`to treatment, but where the results of treatment may
`be relevant to description or diagnosis they are noted.
`Each colleague approached was asked to exchange his
`or her descriptions with others who were looking at
`the same topics. Accordingly, the majority of descrip-
`tions-but not quite all of them-have been scrutinized
`by colleagues in the same field. The descriptions vary
`in length. This reflects the decisions of the individual
`contributors. The senior editor’s func