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Journal of Human Stress Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vzhs20
Diagnosis of the Patient with Chronic Pain Dr. Harold Merskey D.M., F.R.C.P. (C), F.R.C. Psych. a
a b
University of Western Ontario , London, Ontario
b
London Psychiatric Hospital Published online: 09 Jul 2010.
To cite this article: Dr. Harold Merskey D.M., F.R.C.P. (C), F.R.C. Psych. (1978) Diagnosis of the Patient with Chronic Pain, Journal of Human Stress, 4:2, 3-7, DOI: 10.1080/0097840X.1978.9934979 To link to this article: http://dx.doi.org/10.1080/0097840X.1978.9934979
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Diagnosis of the Patient with Chronic Pain Harold Merskey, D.M., F.R.C.P. (C), F.R.C. Psych.
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
The problems of classification of pain syndromes are briefly reviewed. A completely satisfactory taxonomy of pain has to be exhaustive and its categories must be mutually exclusive. This is not feasible in medicine in general and even less so in regard to pain which requires classification using several axes. Practical groupings of syndromes can be made which are helpful clinically. A list of these is provided, and principles which apply to the clinical investigation of patients with pain are stated.
THE PROBLEMS OF DIAGNOSIS AND CLASSIFICATION
Accurate diagnosis of any condition is highly valued but often elusive. Apart from the practical difficulties involved in explaining some symptoms there are theoretical problems in determining suitable systems of classification. Almost all peoples have concepts of illness. These relate to notions of discomfort, handicap, physical change, loss of function and altered social role. Fabrega' points out that for many peoples, especially primitive ones, disease is defined in these terms rather than biologically. A classification of disease may be created which thus handles illness as a sociomedical crisis2 and not as a consequence of biological change. This point of view could well be applied to chronic pain. It is often marked more by symptoms and incapacity than by precise knowledge of its origins. However, physicians are inevitably and rightly disposed - by training and by their experience of Dr. Merskey is Professor of Psychiatry at the University of Western Ontario in London. Ontario, and Director of Education and Research at London Psychiatric Hospital.
June, I978
the success of modern medicine - to look for fundamental scientific explanations which can be incorporated in a diagnostic system. Although this view is accepted by the writer, it still leaves substantial problems. A popular textbook of medicine3 points out that the classification of chronic nephritis may be by syndrome, etiology, pathogenesis or clinical presentation, and that there is no common agreement on the best method. Perhaps biochemical disturbances could also claim a place in the discussion of classification. Thus, even in the field of purely organic conditions, there are difficulties in defining an adequate approach to diagnosis. Those difficulties are enhanced when psychiatric aspects have to be considered. Pain is much affected by psychiatric and psychological factor^.^-^ Chronic pain patients frequently show a large element of emotional disturb a n ~ e . ~ , ' ~There , " is general agreement that pain can be produced by psychological mechanisms alone without a significant organic contribution.8 The difficulties of psychiatric diagnosis enter accordingly into any discussion of the diagnosis of chronic pain. Stengel12 points out that any system of taxonomy ought to involve classes which are mutually exclusive
3
DIAGNOSIS OF CHRONIC PAIN
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
and jointly exhaustive. In such a system any item to be classified should be capable of being allocated to one place which would describe it fully. This issue does not concern the question of disagreement as to the exact nature of a case, nor the problems of interobserver reliability. It has to do with the question, for example, of whether Huntington’s Chorea should be classified as a genetic disorder or an organic brain syndrome, and what denotation should be given to the depression which is often found with it.
“. . . we think of pain as purely physical disturbance. This is wrong.”
In psychiatry no international classification is wholly agreed upon. The American Psychiatric Association currently is working on Diagnostic and Statistical Manual-111 (D.S.M.111). It can safely be predicted that it will not be wholly approved even in the U.S.A. alone, even though it operates by principles of operational definition in most instances rather than by a specific classificatory system. Not only are there the problems attaching to conditions which have an organic basis, there are still more difficult issues to resolve in relation to personality disorder and the question of emotional influences upon both psychological and physical states. It has to be decided, as Stengel” points out, whether we are classifying diseases or people. The classification of pain provides us with identical or comparable problems. To take one example, we have to consider whether postherpetic neuralgia with consequent depression should be classed as a lesion of the nervous system, as a viral disorder, or as a regional disturbance depending on the part of the body involved, and then determine the linkage which has to be made between the physical and the emotional phenomena. There is no perfect taxonomy which tells us where to place the condition if pain is experienced with the herpetic lesions only when the patient is depressed (perhaps for some reasons other than the lesions) but not when he or she is cheerful. It has to be accepted that we cannot produce a neat classificatory system such as the Linnaean
4
flora. Some arrangement of the data is possible and has practical uses, even if the latter are not all that would be desired. Before considering this we should look at what is meant by pain. THE NATURE OF PAIN Normally, we think of pain as a purely physical disturbance. This is wrong. If we injure ourselves or are injured, the experience related to that injury, if unpleasant, is correctly described as pain. If we have a disease or a physical disturbance producing comparable experiences to injury, those experiences too are correctly called pain. But this is often not a oneto-one relationship. Anxiety magnifies the effects of physical lesions in causing pain, and some pains are independent of significant noxious stimulation. It seems likely that of all pains for which patients seek consultation, a minimum proportion of about onequarter is related to psychiatric illness.13There is reason to think that the proportion may be as high as one-third or more. We can even have experiences like those due to trauma without there being any physical in which case they will also be regarded - at least by us - as pain. The importance of these observations is that pain has to be seen as a psychological term referring to a subjective experience, whatever its etiology. There will, of course, be corresponding physiological or cerebral events. They can be characterized by terms like inflammation, discharges in nerve fibres, synaptic excitation, activation of spinothalamic pathways, and so on. Ordinarily there is a certain consonance between the physical disturbance peripherally and the subjective experience of pain. We cannot measure the central disturbance peripherally and the subjective experience of pain. We cannot measure the central disturbance except to a very limited extent by evoked potential studies. It is necessary to remark that we usually learn about the experience of pain in relationship to trauma. But once that experience has been identified and demarcated we mostly use the same words to describe it whether the pain is due to thought processes or to noxious stimulation. Pain caused by psychiatric illness employs many or all of the descriptive terms as pain caused by physical illness.“ For these reasons, pain has been defined as “An unpleasant experience which we primarily associate with tissue damage or describe in terms of such damage or both. “L5.16
Journal of Human Stress
M ERSK EY
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
This definition allows us to consider one or more causes for the experience - i.e., physical, psychological or both. It is relevant to the whole question of diagnosis because it helps to prevent us from wrongly supposing that patients do not have pain if we cannot find a physical cause for their complaint. That is a notorious error, which is nevertheless frequently made or implied when patients with symptoms like pain are told “there is nothing wrong with you.” This phrase is often taken to suggest that an experience was not truthfully or correctly reported. CHRONIC PAINFUL STATES We now can consider the types of condition or label which most often are found with chronic pain. Boyd et all’ have given a list which is set out in Table I. The table is a practical one. It provides a handy arrangement of labels for most of the chronic conditions which are seen in pain clinics. If we think of other painful conditions we can at once add rheumatoid arthritis and osteoarthritis. Additional diagnoses will occur depending on our particular clinical experience. It can also be seen at once that in terms of classification, for which it was not designed, the table (together with the extra diagnoses just mentioned) is completely arbitrary. It offers no pretense at systematic classification. Lesions of organic systems are distinguished from neoplasms which might involve any system, and from psychiatric disorders which might be associated with any lesion. Gout is present under “miscellaneous” and is both a metabolic and a connective tissue disorder. Facial pain, under “miscellaneous,” represents a category related to region, as does dental pain which is also a system category. There is no attempt at a mutually exclusive classification. However the grouping of diagnoses or syndromes in the table is useful in practice. It guides approaches at understanding illness and symptoms, and assists efforts in treatment and mangement . Many other authors provide their own lists of painful conditions like the foregoing. One of the most successful has been that of the American Medical Association Ad Hoc Committee on the Diagnosis of Headache.’* This deals only with headache. It is shown in reduced form in Table 2. An important classification which deserves notice is by Bonica.” This exhaustive classification first
June, I978
TABLE 1 DISORDERS SEEN IN PAIN CLINIC Neurological Disorders Nerve Lesions posttraumatic neuritis causalgia postoperative neuromas amputation stump pain coccydynia scar pain nerve entrapments Postherpetic Neuralgia (Shingles) Trigerninal Neuralgia (Tic douloureux) Sympathetic Dystrophy (e.g. Shoulder Hand Syndrome) Painful Spastic States Thalamic Pain Musculoskeletal Disorders Low Back Pain (Spondylitis, arthritis, failed disc surgery, etc.) Myofascial Pain Syndrome (e.g. Frozen Shoulder) Paget‘s Disease (with encroachment on nerves) Ischemic Disorders Peripheral Vascular Disease IClaudication) Angina Pectoris Neoplasms Direct Invasion or Compression of Painful Structures Metastases Psychiatric Disorders Neurotic Illness and Mixed Depressions Headache (Some types) Miscellaneous Dental Pain Myofascial Pain Dysfunction Syndrome Temporal Mandibular Joint Arthritis Other Facial Pain Chronic Pancreatitis Gout Obscure Pain of Unknown Cause (e.g. Obscure Abdominal Pain)
considers regional pains, such as pains in the head, shoulder, chest or abdomen. It then moves on to cover pain of neurogenic origin varying from polyneuritis to neuralgias. These may be of the face and head (e.g., trigeminal neuralgia), of the cervical nerves, or related to osteoarthritis or infection. Pain of neurogenic orgin is also classified under the headings of causalgia and other reflex dystrophies, pain after amputation and central pain. A further section deals with pain consequent on peripheral vascular disease, and another section with musculoskeletal pains and lesions of the skin. Pain of visceral origin is considered as a separate heading
5
DIAGNOSIS OF CHRONIC PAIN
TABLE 2
CLASSIFICATION OF HEADACHE* 1. Vascular headache of Migraine Type A. "Classic" Migraine B. "Common" Migraine C. "Cluster" Headache D. "Hemiplegic" and "Ophthalmoplegic" Migraine E. "Lower-Half'' Headache
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
2. Muscle Contraction Headache 3. Combined Headache: Vascular and Muscle-Contraction 4. Headache of Nasal Vasomotor Reaction
5. Headache of Delusional, Conversion, or Hypochondriacal States 6. Nonmigrainous Vascular Headaches 7. Traction Headache
8. Headache Due to Overt Cranial Inflammation
9-13,Headache Due to Disease of Ocular, Aural, Nasal and Sinusal, Dental, or Other Cranial or Neck Structures 14. Cranial Neuritides 15. Cranial Neuralgias
"Friedman et al'"
which includes some headaches such as migraine, angina, pain from pulmonary disease, pain of pancreatic origin (whose causes may naturally be diverse), diseases of the urinary tract, and so forth. A major subgrouping is for pain associated with cancer and other neoplastic diseases which in turn are related back to the various parts of the body that may be affected. The system covers virtually all the painful conditions known to man. For the reasons already given it cannot be a pure taxonomy, and categories overlap as much as they do in Table I. However, anyone wishing to work with it can state his material, cases and data in a way that others can parallel. Results may thus be compared, and that is perhaps the main reason for medical taxonomy.
Failing that, we seek to identify them as particular syndromes, e.g., headache, which have some known characteristics in regard to prognosis and treatment. With respect to chronic pain, it is axiomatic that such attempts at diagnosis shall have been made. If physical examination has not provided an adequate explanation then psychiatric assessment is mandatory. It is true that when a physical examination reveals no cause for a pain there may still be a physical cause. But in such cases, psychiatric examination ought to be considered, not with the view that it is the only possible remaining explanation, but with the idea that it will provide a possibly useful diagnosis which may indeed be the main explanation of the patient's pain. If the psychiatric assessment also proves negative, then it is necessary to suspend judgment and perhaps treat the patient empirically or with harmless physical and psychological measures. WaltersZ0summarizes this type of approach: "The necessary steps are (1) to look at the physical findings and the pain story: (2) to identify them as physiogenic or psychogenic: (3) to establish the relationship of the mental state, the life history, the past illnesses and the situational stresses; and (4) to test the correlation by treatment and further observation until all doubt is removed. Investigation should be thorough and accessory investigation should be pushed to the point where the physical and psychological states are known with enough certainty to make a reliable correlation. Special tests such as myelography and encephalography should not be withheld because the problem might be functional . . . everyone benefits from the knowledge that a thorough physical examination is negative as long as the patient is then skillfully taken to the psychological side of the matter and not left dangling with the impression that there is nothing wrong or that the patient should pull himself together and get rid of the pain by his own efforts." In this way, it remains open to the physician to treat the patient whether by specific relevant physical procedures, nonspecific analgesic measures or psychiatric techniques.
CLINICAL PRACTICE
Nothing has been said so far about how to diagnose patients with pain or how different conditions may be distinguished from each other. In a sense, those functions cover the whole of medicine. All symptoms should first be diagnosed if at all possible according to their probable cause or causes.
6
INDEXTERMS chromic pain (classification, diagnosis), pain clinic patients, taxonomy.
Journal of Human Stress
MERSKEY
REFERENCES 1. Fabrega, H., Jr. “The Biological Significance of Taxonomies of Disease,”J. Thwr. Biol.. Vol. 63, 1976, pp. 191-216. 2. D i s e a s e and Social Behaviour. The M.I.T. Press. Cambridge, 1974. 3. Houston, J.C., C.C. Joiner, and J.P. Trounce. A Short Texrhook oj’ Medicine. 5th edit. English Universities Press, London, 1975.
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
4. Barber. T. X. “Toward a Theory of Pain: Relief of Chronic
Pain by Pre-frontal Leucotomy, Opiates, Placebos and Hypnosis,” Psychol. Bull., Vol. 56. 1959, pp. 430-460. 5. Beecher, H.K. Measurement of Subjective Responses. Quantitative Effects of Drugs. Oxford University Press, New York, 1959. 6. Merskey, H., and F.G.Spear. Pain: Psychological and Psychiatric Aspects. Bailliere. Tindall & Cassell, London, 1967. 7. Sternbach, R.A. Pain: A Psychophysiological Analysis. Academic Press, New York, 1968. 8. Merskey, H. “Psychological Aspects of Pain,” Postgrad. Med. J . . Vol. 44. 1%8. pp. 297-306. 9. Woodforde, J.M., and H. Merskey “Personality Traits of Patients With Chronic Pain,” J. Psychosom. Res.. Vol. 16, 1972, pp. 167-172. 10. Sternbach, R.A. Pain Patients: Traits and Treatment. Academic Press, New York, 1974.
June, 1978
11. Pilowsky, I . , and N.D. Spence. “Is Illness Behaviour Related to Chronicity in Patients with Intractable Pain,” fain. Vol. 2, 1976, pp. 61-71.
E. “Classification of Mental Disorders,” Bull. WHO. Vol. 21, 1959, pp. 601-663. 13. Delaplaine, R.. 0.1. Ifabumuyi. J. Zarfas, and H. Merskey. “Significance of Pain in a Psychiatric Hospital Population,” Pain. In press. 14. Devine. R., H. Merskey. “The Description of Pain in Psychiatric and General Medical Patients,” J. Psychosom. Res.. Vol. 9, 1965. pp. 311-316. 15. Merskey, H. An Investigation of Pain in Psychological Illness. D.M. Thesis, Oxford, 1964. 16. Merskey, H., and F.G. Spear. “The Concept of Pain.” J. Psychosom. Res.. Vol. 11, 1967, pp. 59-67. 17. Boyd, D., H. Merskey, and 1. S. Nielsen. “The Pain Clinic: An Approach to the Problem of Chronic Pain.” Submitted for publication, 1978. 18. Friedman, A.P. “Classification of Headache” (special report of the A.M.A. Ad Hoc Committee). Arch. Neirrol.. Vol. 6. 1962, pp. 173-176. 19. Bonica, J.J. The Management of fain. Lea and Febiger. Philadelphia, 1953. 20. Walters, A. “The Psychogenic Regional Pain Syndrome and Its Diagnosis.” Pain. R.S. Knighton and P.R. Dumke, eds. Little Brown and Co.. Boston, Mass, 1966. 12. Stengel.
7
Journal of Human Stress Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/vzhs20
Diagnosis of the Patient with Chronic Pain Dr. Harold Merskey D.M., F.R.C.P. (C), F.R.C. Psych. a
a b
University of Western Ontario , London, Ontario
b
London Psychiatric Hospital Published online: 09 Jul 2010.
To cite this article: Dr. Harold Merskey D.M., F.R.C.P. (C), F.R.C. Psych. (1978) Diagnosis of the Patient with Chronic Pain, Journal of Human Stress, 4:2, 3-7, DOI: 10.1080/0097840X.1978.9934979 To link to this article: http://dx.doi.org/10.1080/0097840X.1978.9934979
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions
Diagnosis of the Patient with Chronic Pain Harold Merskey, D.M., F.R.C.P. (C), F.R.C. Psych.
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
The problems of classification of pain syndromes are briefly reviewed. A completely satisfactory taxonomy of pain has to be exhaustive and its categories must be mutually exclusive. This is not feasible in medicine in general and even less so in regard to pain which requires classification using several axes. Practical groupings of syndromes can be made which are helpful clinically. A list of these is provided, and principles which apply to the clinical investigation of patients with pain are stated.
THE PROBLEMS OF DIAGNOSIS AND CLASSIFICATION
Accurate diagnosis of any condition is highly valued but often elusive. Apart from the practical difficulties involved in explaining some symptoms there are theoretical problems in determining suitable systems of classification. Almost all peoples have concepts of illness. These relate to notions of discomfort, handicap, physical change, loss of function and altered social role. Fabrega' points out that for many peoples, especially primitive ones, disease is defined in these terms rather than biologically. A classification of disease may be created which thus handles illness as a sociomedical crisis2 and not as a consequence of biological change. This point of view could well be applied to chronic pain. It is often marked more by symptoms and incapacity than by precise knowledge of its origins. However, physicians are inevitably and rightly disposed - by training and by their experience of Dr. Merskey is Professor of Psychiatry at the University of Western Ontario in London. Ontario, and Director of Education and Research at London Psychiatric Hospital.
June, I978
the success of modern medicine - to look for fundamental scientific explanations which can be incorporated in a diagnostic system. Although this view is accepted by the writer, it still leaves substantial problems. A popular textbook of medicine3 points out that the classification of chronic nephritis may be by syndrome, etiology, pathogenesis or clinical presentation, and that there is no common agreement on the best method. Perhaps biochemical disturbances could also claim a place in the discussion of classification. Thus, even in the field of purely organic conditions, there are difficulties in defining an adequate approach to diagnosis. Those difficulties are enhanced when psychiatric aspects have to be considered. Pain is much affected by psychiatric and psychological factor^.^-^ Chronic pain patients frequently show a large element of emotional disturb a n ~ e . ~ , ' ~There , " is general agreement that pain can be produced by psychological mechanisms alone without a significant organic contribution.8 The difficulties of psychiatric diagnosis enter accordingly into any discussion of the diagnosis of chronic pain. Stengel12 points out that any system of taxonomy ought to involve classes which are mutually exclusive
3
DIAGNOSIS OF CHRONIC PAIN
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
and jointly exhaustive. In such a system any item to be classified should be capable of being allocated to one place which would describe it fully. This issue does not concern the question of disagreement as to the exact nature of a case, nor the problems of interobserver reliability. It has to do with the question, for example, of whether Huntington’s Chorea should be classified as a genetic disorder or an organic brain syndrome, and what denotation should be given to the depression which is often found with it.
“. . . we think of pain as purely physical disturbance. This is wrong.”
In psychiatry no international classification is wholly agreed upon. The American Psychiatric Association currently is working on Diagnostic and Statistical Manual-111 (D.S.M.111). It can safely be predicted that it will not be wholly approved even in the U.S.A. alone, even though it operates by principles of operational definition in most instances rather than by a specific classificatory system. Not only are there the problems attaching to conditions which have an organic basis, there are still more difficult issues to resolve in relation to personality disorder and the question of emotional influences upon both psychological and physical states. It has to be decided, as Stengel” points out, whether we are classifying diseases or people. The classification of pain provides us with identical or comparable problems. To take one example, we have to consider whether postherpetic neuralgia with consequent depression should be classed as a lesion of the nervous system, as a viral disorder, or as a regional disturbance depending on the part of the body involved, and then determine the linkage which has to be made between the physical and the emotional phenomena. There is no perfect taxonomy which tells us where to place the condition if pain is experienced with the herpetic lesions only when the patient is depressed (perhaps for some reasons other than the lesions) but not when he or she is cheerful. It has to be accepted that we cannot produce a neat classificatory system such as the Linnaean
4
flora. Some arrangement of the data is possible and has practical uses, even if the latter are not all that would be desired. Before considering this we should look at what is meant by pain. THE NATURE OF PAIN Normally, we think of pain as a purely physical disturbance. This is wrong. If we injure ourselves or are injured, the experience related to that injury, if unpleasant, is correctly described as pain. If we have a disease or a physical disturbance producing comparable experiences to injury, those experiences too are correctly called pain. But this is often not a oneto-one relationship. Anxiety magnifies the effects of physical lesions in causing pain, and some pains are independent of significant noxious stimulation. It seems likely that of all pains for which patients seek consultation, a minimum proportion of about onequarter is related to psychiatric illness.13There is reason to think that the proportion may be as high as one-third or more. We can even have experiences like those due to trauma without there being any physical in which case they will also be regarded - at least by us - as pain. The importance of these observations is that pain has to be seen as a psychological term referring to a subjective experience, whatever its etiology. There will, of course, be corresponding physiological or cerebral events. They can be characterized by terms like inflammation, discharges in nerve fibres, synaptic excitation, activation of spinothalamic pathways, and so on. Ordinarily there is a certain consonance between the physical disturbance peripherally and the subjective experience of pain. We cannot measure the central disturbance peripherally and the subjective experience of pain. We cannot measure the central disturbance except to a very limited extent by evoked potential studies. It is necessary to remark that we usually learn about the experience of pain in relationship to trauma. But once that experience has been identified and demarcated we mostly use the same words to describe it whether the pain is due to thought processes or to noxious stimulation. Pain caused by psychiatric illness employs many or all of the descriptive terms as pain caused by physical illness.“ For these reasons, pain has been defined as “An unpleasant experience which we primarily associate with tissue damage or describe in terms of such damage or both. “L5.16
Journal of Human Stress
M ERSK EY
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
This definition allows us to consider one or more causes for the experience - i.e., physical, psychological or both. It is relevant to the whole question of diagnosis because it helps to prevent us from wrongly supposing that patients do not have pain if we cannot find a physical cause for their complaint. That is a notorious error, which is nevertheless frequently made or implied when patients with symptoms like pain are told “there is nothing wrong with you.” This phrase is often taken to suggest that an experience was not truthfully or correctly reported. CHRONIC PAINFUL STATES We now can consider the types of condition or label which most often are found with chronic pain. Boyd et all’ have given a list which is set out in Table I. The table is a practical one. It provides a handy arrangement of labels for most of the chronic conditions which are seen in pain clinics. If we think of other painful conditions we can at once add rheumatoid arthritis and osteoarthritis. Additional diagnoses will occur depending on our particular clinical experience. It can also be seen at once that in terms of classification, for which it was not designed, the table (together with the extra diagnoses just mentioned) is completely arbitrary. It offers no pretense at systematic classification. Lesions of organic systems are distinguished from neoplasms which might involve any system, and from psychiatric disorders which might be associated with any lesion. Gout is present under “miscellaneous” and is both a metabolic and a connective tissue disorder. Facial pain, under “miscellaneous,” represents a category related to region, as does dental pain which is also a system category. There is no attempt at a mutually exclusive classification. However the grouping of diagnoses or syndromes in the table is useful in practice. It guides approaches at understanding illness and symptoms, and assists efforts in treatment and mangement . Many other authors provide their own lists of painful conditions like the foregoing. One of the most successful has been that of the American Medical Association Ad Hoc Committee on the Diagnosis of Headache.’* This deals only with headache. It is shown in reduced form in Table 2. An important classification which deserves notice is by Bonica.” This exhaustive classification first
June, I978
TABLE 1 DISORDERS SEEN IN PAIN CLINIC Neurological Disorders Nerve Lesions posttraumatic neuritis causalgia postoperative neuromas amputation stump pain coccydynia scar pain nerve entrapments Postherpetic Neuralgia (Shingles) Trigerninal Neuralgia (Tic douloureux) Sympathetic Dystrophy (e.g. Shoulder Hand Syndrome) Painful Spastic States Thalamic Pain Musculoskeletal Disorders Low Back Pain (Spondylitis, arthritis, failed disc surgery, etc.) Myofascial Pain Syndrome (e.g. Frozen Shoulder) Paget‘s Disease (with encroachment on nerves) Ischemic Disorders Peripheral Vascular Disease IClaudication) Angina Pectoris Neoplasms Direct Invasion or Compression of Painful Structures Metastases Psychiatric Disorders Neurotic Illness and Mixed Depressions Headache (Some types) Miscellaneous Dental Pain Myofascial Pain Dysfunction Syndrome Temporal Mandibular Joint Arthritis Other Facial Pain Chronic Pancreatitis Gout Obscure Pain of Unknown Cause (e.g. Obscure Abdominal Pain)
considers regional pains, such as pains in the head, shoulder, chest or abdomen. It then moves on to cover pain of neurogenic origin varying from polyneuritis to neuralgias. These may be of the face and head (e.g., trigeminal neuralgia), of the cervical nerves, or related to osteoarthritis or infection. Pain of neurogenic orgin is also classified under the headings of causalgia and other reflex dystrophies, pain after amputation and central pain. A further section deals with pain consequent on peripheral vascular disease, and another section with musculoskeletal pains and lesions of the skin. Pain of visceral origin is considered as a separate heading
5
DIAGNOSIS OF CHRONIC PAIN
TABLE 2
CLASSIFICATION OF HEADACHE* 1. Vascular headache of Migraine Type A. "Classic" Migraine B. "Common" Migraine C. "Cluster" Headache D. "Hemiplegic" and "Ophthalmoplegic" Migraine E. "Lower-Half'' Headache
Downloaded by [University of Iowa Libraries] at 06:06 05 October 2014
2. Muscle Contraction Headache 3. Combined Headache: Vascular and Muscle-Contraction 4. Headache of Nasal Vasomotor Reaction
5. Headache of Delusional, Conversion, or Hypochondriacal States 6. Nonmigrainous Vascular Headaches 7. Traction Headache
8. Headache Due to Overt Cranial Inflammation
9-13,Headache Due to Disease of Ocular, Aural, Nasal and Sinusal, Dental, or Other Cranial or Neck Structures 14. Cranial Neuritides 15. Cranial Neuralgias
"Friedman et al'"
which includes some headaches such as migraine, angina, pain from pulmonary disease, pain of pancreatic origin (whose causes may naturally be diverse), diseases of the urinary tract, and so forth. A major subgrouping is for pain associated with cancer and other neoplastic diseases which in turn are related back to the various parts of the body that may be affected. The system covers virtually all the painful conditions known to man. For the reasons already given it cannot be a pure taxonomy, and categories overlap as much as they do in Table I. However, anyone wishing to work with it can state his material, cases and data in a way that others can parallel. Results may thus be compared, and that is perhaps the main reason for medical taxonomy.
Failing that, we seek to identify them as particular syndromes, e.g., headache, which have some known characteristics in regard to prognosis and treatment. With respect to chronic pain, it is axiomatic that such attempts at diagnosis shall have been made. If physical examination has not provided an adequate explanation then psychiatric assessment is mandatory. It is true that when a physical examination reveals no cause for a pain there may still be a physical cause. But in such cases, psychiatric examination ought to be considered, not with the view that it is the only possible remaining explanation, but with the idea that it will provide a possibly useful diagnosis which may indeed be the main explanation of the patient's pain. If the psychiatric assessment also proves negative, then it is necessary to suspend judgment and perhaps treat the patient empirically or with harmless physical and psychological measures. WaltersZ0summarizes this type of approach: "The necessary steps are (1) to look at the physical findings and the pain story: (2) to identify them as physiogenic or psychogenic: (3) to establish the relationship of the mental state, the life history, the past illnesses and the situational stresses; and (4) to test the correlation by treatment and further observation until all doubt is removed. Investigation should be thorough and accessory investigation should be pushed to the point where the physical and psychological states are known with enough certainty to make a reliable correlation. Special tests such as myelography and encephalography should not be withheld because the problem might be functional . . . everyone benefits from the knowledge that a thorough physical examination is negative as long as the patient is then skillfully taken to the psychological side of the matter and not left dangling with the impression that there is nothing wrong or that the patient should pull himself together and get rid of the pain by his own efforts." In this way, it remains open to the physician to treat the patient whether by specific relevant physical procedures, nonspecific analgesic measures or psychiatric techniques.
CLINICAL PRACTICE
Nothing has been said so far about how to diagnose patients with pain or how different conditions may be distinguished from each other. In a sense, those functions cover the whole of medicine. All symptoms should first be diagnosed if at all possible according to their probable cause or causes.
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INDEXTERMS chromic pain (classification, diagnosis), pain clinic patients, taxonomy.
Journal of Human Stress
MERSKEY
REFERENCES 1. Fabrega, H., Jr. “The Biological Significance of Taxonomies of Disease,”J. Thwr. Biol.. Vol. 63, 1976, pp. 191-216. 2. D i s e a s e and Social Behaviour. The M.I.T. Press. Cambridge, 1974. 3. Houston, J.C., C.C. Joiner, and J.P. Trounce. A Short Texrhook oj’ Medicine. 5th edit. English Universities Press, London, 1975.
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4. Barber. T. X. “Toward a Theory of Pain: Relief of Chronic
Pain by Pre-frontal Leucotomy, Opiates, Placebos and Hypnosis,” Psychol. Bull., Vol. 56. 1959, pp. 430-460. 5. Beecher, H.K. Measurement of Subjective Responses. Quantitative Effects of Drugs. Oxford University Press, New York, 1959. 6. Merskey, H., and F.G.Spear. Pain: Psychological and Psychiatric Aspects. Bailliere. Tindall & Cassell, London, 1967. 7. Sternbach, R.A. Pain: A Psychophysiological Analysis. Academic Press, New York, 1968. 8. Merskey, H. “Psychological Aspects of Pain,” Postgrad. Med. J . . Vol. 44. 1%8. pp. 297-306. 9. Woodforde, J.M., and H. Merskey “Personality Traits of Patients With Chronic Pain,” J. Psychosom. Res.. Vol. 16, 1972, pp. 167-172. 10. Sternbach, R.A. Pain Patients: Traits and Treatment. Academic Press, New York, 1974.
June, 1978
11. Pilowsky, I . , and N.D. Spence. “Is Illness Behaviour Related to Chronicity in Patients with Intractable Pain,” fain. Vol. 2, 1976, pp. 61-71.
E. “Classification of Mental Disorders,” Bull. WHO. Vol. 21, 1959, pp. 601-663. 13. Delaplaine, R.. 0.1. Ifabumuyi. J. Zarfas, and H. Merskey. “Significance of Pain in a Psychiatric Hospital Population,” Pain. In press. 14. Devine. R., H. Merskey. “The Description of Pain in Psychiatric and General Medical Patients,” J. Psychosom. Res.. Vol. 9, 1965. pp. 311-316. 15. Merskey, H. An Investigation of Pain in Psychological Illness. D.M. Thesis, Oxford, 1964. 16. Merskey, H., and F.G. Spear. “The Concept of Pain.” J. Psychosom. Res.. Vol. 11, 1967, pp. 59-67. 17. Boyd, D., H. Merskey, and 1. S. Nielsen. “The Pain Clinic: An Approach to the Problem of Chronic Pain.” Submitted for publication, 1978. 18. Friedman, A.P. “Classification of Headache” (special report of the A.M.A. Ad Hoc Committee). Arch. Neirrol.. Vol. 6. 1962, pp. 173-176. 19. Bonica, J.J. The Management of fain. Lea and Febiger. Philadelphia, 1953. 20. Walters, A. “The Psychogenic Regional Pain Syndrome and Its Diagnosis.” Pain. R.S. Knighton and P.R. Dumke, eds. Little Brown and Co.. Boston, Mass, 1966. 12. Stengel.
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