Dr King responds:
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.1 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.