Mark A. Turner, MRCP, MRCPsych, PhD

Dr Steven King provided an interesting summary of complex regional pain syndrome (CRPS) in Psychiatric Times ("

," June 2006, page 9). We felt it would be useful to provide some additional observations on the relationship between CRPS type I and psychological causes of pain. The diagnosis of CRPS type I is based on 4 criteria

: (1) a noxious event; (2) subjective symptoms of pain, etc, disproportionate to this event; (3) objective physical changes; and (4) absence of other causes (including psychological).

The difficulty we want to draw attention to relates primarily to the use of "physical disproportionality" in the diagnostic criteria of  an ostensible physical condition. Studies of reflex sympathetic dystrophy, the predecessor of CRPS type I, show a high incidence of comorbid depression, anxiety, and posttraumatic stress disorder

; it is important that clinicians be vigilant because persons with symptoms disproportionate to a physical cause may in fact have either CRPS type I or one of the previously mentioned mental illnesses.

This not only makes the diagnosis of CRPS type I somewhat anomalous in that it effectively becomes a physical condition requiring a psychiatric assessment for diagnosis, but, as Dr King's reference to malingering reminds us, that the psychiatrist's job of deciding what proportion of a physically disproportionate pain is also disproportionate to mental illness is highly problematic. One might accept that it is possible to assess the severity of a familiar mental illness like depression and translate this to yield a proportionate relative etiologic contribution in a given pain presentation.

However, the difficulties do not end there because DSM-IV also includes a specific category of mental illness called "pain disorder," which-like CRPS type I-also involves pain that cannot be explained fully by a physiologic process or a physical disorder.

 Pain disorder was effectively introduced to capture cases in which pain is disproportionate to both physical factors and familiar mental illnesses. CRPS type I diagnostic criteria rely on excluding a diagnosis of pain disorder by criterion 4; however, there is the very real question of how to distinguish the 2 causes of "doubly" disproportionate pain from each other in practice.

DSM-IV maintains that pain disorder should be diagnosed only if "psychological factors are judged to have an important role in the onset, severity, exacerbation, or maintenance of the pain."

 Unfortunately, the utility of this depends first on the clinician's ability to distinguish psychological factors that are the cause of pain from those that are a consequence of it, and second, on adequately resolving the question of "proportionality" in relation to notoriously difficult to define emotional and other factors.

The literature on CRPS type I does not really address these issues, but therapy guidelines indicate that psychological factors may be important when pain has lasted for 2 months or more.

 This stipulative use of temporal factors to decide between physical (CRPS type I) and psychological (implicitly somatoform) causes of pain is effectively forced on us by the aforementioned  intractable problems of  identifying and then deciding causality and proportionality in relation to psychological factors.  Not surprisingly, this is inherently problematic. In particular, it is difficult to understand why the presumed physical factors causing CRPS type I-the nature of which is by definition unknown-cannot operate beyond 2 months, or indeed why the diagnosis of pain disorder should be implicitly dependent on a temporal criterion not mentioned in DSM-IV. The crucial point, however, is that without a nontemporal, and therefore, nonarbitrary way of distinguishing pain due to CRPS type I from that due to pain disorder, the possibility will always remain open that pain attributed to the former is in fact caused by the latter.

It is tempting to think that objective changes covered by criterion 3 will help. The difficulty here, however, is that the immobilization of a limb for whatever reason can itself lead to these changes.

 This indicates that, strictly speaking, the only circumstances in which objective changes can be used to differentiate CRPS type I from cases of pain disorder are those in which immobilization has not occurred. To restrict the diagnosis of CRPS type I to these extremely rare cases would clearly make it virtually useless. This, coupled with the realization that the psychological causes of immobilization that present the most challenging problem (ie, factitious disorder and malingering

) do not even involve pain, illustrates that introducing a set of diagnostic criteria for a medically unexplained condition like CRPS type I is a good deal less problematic than applying them in practice.

Dr Turner is a consultant psychiatrist at the Bamburgh Clinic, St Nicholas Hospital, in Newcastle upon Tyne, United Kingdom. Dr Neal is a consultant psychiatrist at the Bristol Priory Hospital in Bristol, United Kingdom.

Drs Turner and Neal raise several points that warrant further discussion.

The relationships between CRPS type I and mental illness has been the subject of much discussion and research. There are some who believe that CRPS type I is only a mental illness and has no physical basis. However, no one has yet been able to identify any psychological factors that consistently predispose someone to this disorder.

The diagnosis of CRPS type I does require health care professionals to determine whether the pain is disproportionate to the event. This reflects that no correlation exists between the development of this disorder and the severity of the initial noxious stimulus. This lack of correlation between objectively verifiable physical changes and the presence or severity of pain is not unique to CRPS type I. Multiple studies have demonstrated that there is little correlation between MRI findings and the presence or severity of back pain.

However, I disagree with several of Dr Turner and Neal's characterizations of the DSM-IV diagnosis of pain disorder. As the chair of the DSM-IV Committee on Pain Disorders, I am well acquainted with this diagnosis and the reasons that it was created. The diagnosis was not "introduced to capture cases in which pain is disproportionate to both physical factors and familiar illnesses." It was created because the DSM-III diagnosis of psychogenic pain disorder and its DSM-III-R replacement, somatoform pain disorder, were found to be of limited utility, primarily because they failed to address the many patients with pain who have both physical and psychological problems.

 Contrary to what Drs Turner  and Neal state, pain disorder does not require that psychological factors "cause the pain." The reason that the term "associated with" psychological factors, a general medical condition, or both, was chosen was to purposely avoid forcing caregivers to determine the cause of the pain. Doing so is especially problematic for psychiatrists treating patients with chronic pain, who usually do not evaluate these patients until long after the pain's onset.

Though Drs Turner and Neal indicate that one would have to make a choice between the DSM-IV diagnosis of pain disorder and CRPS type I, this is not so. If psychological factors appear to be playing a significant role  in the onset or maintenance of the pain, the diagnosis of pain disorder associated with both psychological factors  and a general medical condition identified as CRPS would be appropriate. Furthermore, by applying both diagnoses, health care professionals would ensure that psychological issues are  not overlooked.

Dr King is clinical professor of psychiatry at the New York University School of Medicine.

 Merskey H, Boqduk N, eds. Classification of Chronic Pain: Descriptions of Chronic Pain Syndromes and Definitions of Pain Terms. 2nd ed. Seattle: IASP Press; 1994:41-42.


 Bruehl S, Carlson CR. Predisposing psychological factors in the development of reflex sympathetic dystrophy. A review of the empirical evidence. Clin J Pain. 1992;8:287-299.


 Lynch ME. Psychological aspects of reflex sympathetic dystrophy: a review of the adult and paediatric literature. Pain. 1992;49:337-347.


 American Psychiatric Association. Diagnostic and Statistical Manual for Mental Disorders, 4th Edition. Washington, DC: American Psychiatric Press; 1994.	


 Stanton-Hicks M, Baron R, Boas R, et al. Complex regional pain syndromes: guidelines for therapy. Clin JPain. 1998;14:155-166.


 Butler SH. Disuse and CRPS. In: Harden RN, Baron R, Janig W, eds. Complex Regional Pain Syndrome: Progress in Pain Research and Management. Vol 22. Seattle: IASP Press; 2001.


 Shibata M, Abe K, Jimbo A, et al. Complex regional pain syndrome type 1 associated with amyotrophic lateral sclerosis. Clin J Pain. 2003;19:69-70.


 Chevalier X, Claudepierre P, Larget-Piet B, Lejonc JL. Munchausen's syndrome simulating reflex sympathetic dystrophy. J Rheumatol. 1996;23:1111-1112.


 Bujis EJ, Klijn FA, Lindeman E, van Wijck AJ. Reflex sympathetic dystrophy vs a factitious disorder [in Dutch]. Ned Tijdschr Geneeskd. 2000;144:1617-1620.

 King SA, Strain JJ. Somatoform pain disorder. In: Widiger TA, Francis AJ, Pincus HA, et al, eds. DSM-IV Sourcebook, Volume 2. Washington, DC: American Psychiatric Press; 1996.  

Articles

Dr Steven King provided an interesting summary of complex regional pain syndrome (CRPS) in Psychiatric Times (Complex Regional Pain Syndrome,  June 2006, page 9). We felt it would be useful to provide some additional observations on the relationship between CRPS type I and psychological causes of pain.

CRPS Type I and Mental Illness

Michael Blumenfield, MD, and James J. Strain, MD (eds); Philadelphia: Lippincott Williams & Wilkins, 2006 949 pages  $199.00 (hardcover)

Reviewed by Mark A. Turner, MRCP, MRCPsych, PhD

The publication of a major new textbook is an important event in any discipline, but the arrival of 

 is a particularly exciting development for clinicians working in the interface between psychiatry and medicine. Blumenfield and Strain have done a masterly job of synthesizing the contributions of numerous leading authorities to provide structure for an emerging subspecialty that reconciles the competing demands of utility and comprehensiveness; they have still managed to include a substantial first section on the conceptual issues that make psychiatry uniquely interesting.

In keeping with this approach, Berrios and Markov's analysis of symptoms and McHugh and Clark's description of their perspectival approach to psychiatric classification set the tone for what is to come. These chapters are fascinating condensations of years of original work, which are accessible to the trainee yet detailed enough to serve as a point of departure for further research.

If psychosomatic medicine is to prosper, at a theoretical level it needs a framework not borrowed from general psychiatry. At a practical level, clinicians need a thorough understanding of all aspects of the psychiatric-physical medicine interface.

In order to address what are ultimately 2 sides of the same coin, section 2 takes a physical systemic approach and consists of a series of state-of-the-art reviews of the psychiatric aspects of cardiovascular, renal, and other diseases. Here, the chapters on inconspicuous topics such as pulmonary disease and burn injuries by Thompson and Sullivan, and Stoddard and colleagues, respectively, are especially welcome. The end product-which will again prove indispensable to all grades of clinicians-constitutes a determined step toward the realization of the editors' vision that as the 21st century unfolds, there will be more of an amalgamation of medicine and psychiatry.

Depression and the somatoform disorders are the bread and butter of psychosomatic medicine, and it is therefore entirely fitting that these should be dealt with in the traditional way: as subjects in their own right. In keeping with this, the editors accord depression a special status and include an excellent review by Cowles and Nemeroff in the first theoretical section.

Other psychiatric conditions are introduced in section 3. Here again, the right balance is achieved and the contributions are uniformly useful and informative. It is perhaps worth drawing specific attention to Phillips' authoritative summary of the perennially fascinating body dysmorphic disorder and to Boettger and colleagues' discussion of delirium that places a refreshing emphasis on assessment.

By the end of these sections, the book has done most of its job. However, it would not be complete without discussions on treatment modalities, ethical considerations, and scientific advances such as genomic testing and brain imaging. These are covered in sections 4 and 5, which focus on Special Topics and Future Perspectives, respectively. Although several of the special topics might arguably have been better placed in sections 1 and 2, the final 2 sections as a whole reinforce what is obvious from the start: this is a marvelous book that deserves a place on the desk of every consultation- liaison psychiatrist. If we add to this that Psychosomatic Medicine comes with a CD-ROM of the entire text and useful trial software for patient care and medical student tracking, Blumenfield and Strain will surely play a central part in the training of psychiatrists in psychosomatic medicine for many years to come.

Dr Turner is a consultant psychiatrist at The Bamburgh Clinic, St Nicholas Hospital, in Newcastle upon Tyne, United Kingdom.

The publication of a major new textbook is an important event in any discipline, but the arrival of Psychosomatic Medicine is a particularly exciting development for clinicians working in the interface between psychiatry and medicine.

Mark A. Turner, MRCP, MRCPsych, PhD

Articles

CRPS Type I and Mental Illness

Book Review