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ur evolving understanding of complex regional pain
syndrome (CRPS) has reached another milestone. CRPS,
or what was initially referred to as “reflex
sympathetic dystrophy,” has been extensively
studied. The International Association for the Study
of Pain (IASP) convened a multispecialty physician
consensus workshop in 1993 to redefine and reclassify
reflex sympathetic dystrophy. Hence the new nomenclature
“CRPS” was born and presented in a journal
article1
and a textbook publication.2
Since those publications, basic science and clinical
research continued. Several authors have questioned
whether the criteria drawn from the 1993 conference
were sufficiently stringent to correctly diagnosis
CRPS with appropriate sensitivity and specificity.
This research as well as the past decade’s
worth of clinical experience provided stimulus to
re-examine the pathophysiology and codify the treatment
options into a clinical algorithm.
IASP convened a second task force in 2003 to address
this newer additional body of research and observations.
Many of the same physicians (including several ASA
members) who were present a decade earlier were
present as well as others who were newly invited
physicians with broad clinical experience in treating
CRPS. The net result of this 2003 consensus workshop
was a refinement of the diagnostic criteria and
description of appropriate avenues for treatment.
These are presented in a new publication.3
The diagnostic changes that are being recommended
have resulted from prospective, multicenter epidemiological
studies that have identified four clinically distinct
subcategories of symptoms that cluster together.
Each factor consists of subjective symptoms and/or
objective physical examination findings consisting
of:
1. Hyperalgesia and hyperesthesia;
2. Temperature asymmetry and color changes;
3. Edema and sweating dysfunction; and
4. Muscle dysfunction, movement disorders and
trophic changes.3
The proposed changes to the diagnostic criteria
would create a category describing the clinical
diagnostic criteria and another category describing
the research criteria. The clinical version
maximizes diagnostic sensitivity while the research
version is intended to more equally balance optimal
sensitivity and specificity for research purposes
so that there is less variability in describing
patient conditions. The clinical criteria stipulate
that there be at least one symptom in three of the
four factor categories and at least one sign or
physical examination findings in two of the four
factor categories. The research criteria stipulate
that patients should report at least one symptom
in each of the four factor categories and again
one physical examination finding in two or more
of the factor categories.
While the proposed changes were reached by consensus,
there was not unanimous agreement. As a result,
there was another subtype of CRPS that was added
out of concern that changing the sensitivity would
leave some previously diagnosed cases without any
applicable pain diagnosis. This subtype is defined
as CRPS-NOS (not otherwise specified), which indicates
a condition that it partially meets CRPS criteria
and is not better explained by any other condition.
In summary these changes are preliminary and are
being proposed to the IASP Committee for the Classification
of Pain for future revisions of their formal taxonomy
and diagnostic criteria for pain states.
References:
1. Stanton-Hicks M, Janig W, Hassenbusch S, et al.
Reflex sympathetic dystrophy: Changing concepts
and taxonomy. Pain. 1995; 63:127-133.
2. Janig W, Stanton-Hicks M, eds. Reflex Sympathetic
Dystrophy: A Reappraisal. Seattle: IASP Press;
1996.
3. Wilson PR, Stanton-Hicks M, Harden RN, eds. CRPS:
Current Diagnosis and Therapy. Progress in Pain
Research and Management. Seattle: IASP Press.
2005; Vol. 32.
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Timothy R. Lubenow, M.D., is Professor of Anesthesiology,
Rush Medical College, and Director, Section
of Pain Management, Rush University Medical
Center, Chicago, Illinois. |
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