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Complex Regional Pain Syndrome The Anatomy Of Controversy

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                     Complex Regional Pain Syndrome:
                      The Anatomy Of A Controversy
                                       Samuel D. Hodge, Jr., Esquire
                                        Jack E. Hubbard, PhD, MD


Q. What do a blood draw, a rear-end collision, a gun-           troversial and least understood of all chronic pain
shot wound, carpal tunnel syndrome, and a sprained              problems.”4
ankle have in common?                                                 Although CRPS usually affects an arm or leg,
A. They are all ways of developing complex regional             there are reports of this condition occurring in other
pain syndrome.                                                  parts of the body such as the face5 and penis.6 Seen
                                                                more often in female patients than male patients in
INTRODUCTION • Complex regional pain syn­                       a ratio of 2:1 to 4:1, CRPS occurs in approximately
drome (CRPS), a painful condition previously known              26.2 cases per 100,000 persons each year.7 This disor-
as reflex sympathetic dystrophy (RSD), has been de-             der does occur in children but is rare before six years
scribed by the court as an uncommon, chronic con-
                                                                of age, usually starting in the 10- to 12 year-old range
dition that usually affects the arm or leg.1 The sufferer
                                                                and continuing into adolescence.8 The legs are more
may experience intense burning or aching pain along
                                                                likely to be involved than arms in a ratio of between
with skin discoloration, swelling, abnormal sweating,
altered temperature, and hypersensitivity in the af-            6:1 and 8:1, and girls are affected six times more of-
fected portions of the body. The nature of the condi-           ten than boys.9 Few physicians question the legitima-
tion is most puzzling, and the cause is still not clearly       cy of this diagnosis, although some physicians who
understood.2 In fact, the condition remains clinically          are not pain specialists reportedly still consider CRPS
challenging both in terms of accurate diagnosis and             a “psychosomatic illness.”10 Understanding this disor-
effective treatment.3 This led one speaker at a confer-         der and the criteria used for its diagnosis has changed
ence on pain sponsored by Harvard Medical School                over the past few years, creating much confusion and
in June 2009 to opine that CRPS is the “most con-               controversy in both medical and legal circles.

                                                        163
164 | Anatomy For Litigators

      The basic diagnostic problem of this condition              With further research and experience with
– severe, unrelenting pain that is out of proportion        RSD, however, a growing discomfort with this pro-
to the inciting injury – is significantly complicated       posed mechanism developed among clinicians and
by the subjective nature of the pain and the lack of        research physicians,15 resulting in a re-evaluation of
a clear objective basis of the problem. Added to this       the terminology. In 1994, a consensus workshop of
mix is the fact that there is no diagnostic test specific   investigators and other experts in the field coined
for CRPS. In a medical setting, these issues create         the term complex regional pain syndrome or CRPS.16
considerable debate over the accuracy of the diag-          The reason for this change was descriptive and not to
nosis and appropriate treatment. In a compensation          imply any pathophysiologic basis for the disorder.17
setting, subjective pain that is out of proportion to       Complex regional pain syndrome was further sub-
the injury is a recipe for unrelenting controversy and      divided into two types: CRPS I and CRPS II. The
protracted litigation.                                      former term was to replace RSD; CRPS II was to
      This chapter examines CRPS from two different         replace causalgia.18 In turn, this new terminology
perspectives. The first part provides a medical over-       was codified by the International Association for the
view of CRPS with a brief historical review, a detailed     Study of Pain (IASP).19
examination of the diagnostic criteria, an explanation            The medical community, however, has been
of the current theory of causation, and a discussion        slow to accept this new nomenclature, and subse-
of available treatments. The second section analyzes        quent validation studies using the new CRPS diag-
how the courts have viewed this disorder in a claim         nostic criteria reveal that the disorder is being over-
or benefits setting, a very diverse topic with varied       diagnosed.20 In addition, pressures from nonmedical
results.                                                    groups, such as personal injury lawyers, are calling
                                                            for a new reevaluation:
MEDICAL CONSIDERATIONS • The issue of
                                                                  … certain influential groups have resisted the
severe, unrelenting pain caused by trauma was first
                                                                  change (e.g., personal injury lawyers, who may
noted in 1872 by Silas Weir Mitchell, M.D.11 A
                                                                  benefit by a “looser” criteria, and some ill in-
Union Army physician during the American Civil
                                                                  formed patient advocacy organizations that fear
War, Dr. Mitchell reported the occurrence of dis-
abling pain in the limbs of soldiers due to bullet or             a “tighter” criteria may cause many previously
shrapnel wounds. Most of these cases resulted from                diagnosed patients to be thrown into diagnostic
large, low-velocity projectiles, also known as minié              limbo…). As a consequence, the full benefits of
balls, utilized by the Confederate Army; Mitchell                 the common consensus­defined IASP criteria
termed this disorder causalgia.12 Over the subsequent             have not been completely realized.21
years, a number of other phrases such as Sudeck’s at-             In response to these concerns, a workshop was
rophy, post-traumatic dystrophy, chronic traumatic          held in Budapest in 2003 to re-examine this disor-
edema, reflex neurovascular dystrophy, algodystro-          der. The attendees, medical experts in the field of
phy, peripheral trophoneurosis, and idiopathic neu-         CRPS, published their consensus findings in 200522
rodystrophic disorder have been applied to identify         and submitted them to the IASP for approval. As of
this malady.13                                              this writing, however, the IASP has not published the
      In 1946, James A. Evans coined the phrase reflex      new criteria and they are being revalidated.23 These
sympathetic dystrophy (RSD) in an effort to describe        proposed diagnostic criteria for CRPS, listed in Ta-
the problem based on a theory of its pathophysiol-          ble 2, are to replace the previously used ones from
ogy, concluding that the sympathetic nervous system         Table 1. The main difference between the two sets
is the key to this condition.14 The term RSD stuck as       of diagnostic criteria is the additional requirement
a mechanistic description, implying that the malady         that at the time of evaluation, there must be objective
resulted from a reflex arc of abnormal firings by the       evidence of abnormalities in the painful area such as
sympathetic nervous system causing disabling pain           swelling, sweating and/or temperature changes, mo-
and loss of function to an extremity.                       tor dysfunction, and exquisite hypersensitivity.
                                                                                     Complex Regional Pain Syndrome | 165
CRPS Diagnosis: Clinical Criteria                                                     TABLE 1
       Physicians can detail the symptoms associated
with patients with CRPS and make some comments
                                                                IASP Diagnostic Criteria For Complex Regional
as to the likelihood that the condition exists based on
                                                                Pain Syndrome (CRPS): 1994 Consensus
the symptoms a patient exhibits. However, the scien-
                                                                Workshop35
tific community does not know precisely the patho-
logic process at work.24                                              1. The presence of an initiating noxious event,
                                                                or a cause of immobilization;
       The correct diagnosis of a medical problem is
the cornerstone for successful care and treatment of                  2. Continuing pain, allodynia, or hyperalgesia
any patient. This point is especially important when            in which the pain is disproportionate to any known
the patient is seeking compensation based on that di-           inciting event;
agnosis. Further, researchers investigating the disor-                3. Evidence at some time of edema, changes in
der need assurance that their subjects have the same            skin blood flow, or abnormal sudomotor activity in
medical problem as those patients who are being seen            the region of pain (can be sign a or symptom);
in doctors’ offices. To understand the development                    4. This diagnosis is excluded by the existence of
and importance of accurate diagnostic criteria for              other conditions that would otherwise account for
CRPS, one needs to consider the concepts of sensi-              the degree of pain and dysfunction; and
tivity and specificity. These parameters are useful for               5. If seen without “major nerve damage,” diag-
determining the accuracy of clinical criteria as well as        nose CRPS I; if seen in the presence of “major nerve
diagnostic testing for CRPS.25                                  damage,” diagnose CRPS II.
       Sensitivity refers to the ability to detect a disorder         A similar analysis of the more restrictive 2003
when it is present, thereby eliminating the possibility         Budapest criteria was discussed by Harden et al.36
of false-negatives.26 Specificity refers to identifying the     These requirements, based on symptoms (what the
normal population, and eliminating false-positives.27           patient reports) and signs (what is observed at the
These parameters are determined by statistical data             time of examination), are listed in Table 2. The in-
analyses and are scored based on mathematical for-              clusion of signs (i.e., objective findings) at the time
mulae.28 Ideally, the sensitivity and specificity values        of examination is an important addition to the crite-
should both be 1.0 (or 100 percent), such that every            ria, providing objective measures of pathology rather
patient with the disorder is identified (sensitivity)           than relying solely on subjective history and com-
and no one without the condition is diagnosed (spec-            plaints of pain by the patient. By requiring two of the
ificity).29 For practical purposes, as the sensitivity ap-      four sign categories and three of the four symptoms,
proaches 1.0, the probability of under-diagnosis is re-         the sensitivity rate dropped somewhat (0.85) but the
duced.30 Likewise, as the specificity value approaches          specificity improved (0.69).37 When the criteria are
1.0, the likelihood of over-diagnosis is reduced.31             modified to require that two of the four signs and all
       This statistical analysis has been applied to the        four of the symptom categories be positive, the speci-
diagnostic criteria for CRPS as developed by both               ficity significantly increased to 0.94 but the sensitiv-
consensus workshops. Following the first workshop               ity dropped to 0.70.38 At the time of this writing, the
in 1994, Bruehl et al. evaluated 117 patients meet-             more recent Budapest consensus group has proposed
ing those IASP criteria (Table 1) and compared them             both of these two sets of criteria for CRPS: one for
with 43 patients with neuropathic pain but not                  clinical application and the other (with the enhanced
CRPS.32 They found the criteria to be very sensitive            specificity) for research work.39 In an accompanying
(0.98) in identifying CRPS patients, but the speci-             editorial, Rollin Gallagher makes the point that the
ficity or elimination of false-positives was quite low          one set of criteria for clinical use will “support our
(0.36).33 Accordingly, these authors determined that            patients’ claim to a legitimate disease or obtain ap-
the diagnosis of CRPS is correct in only 40 percent             propriate treatment.”40 In addition, “we can use the
of the cases.34                                                 new research criteria to refine our samples in clinical
166 | Anatomy For Litigators
research to establish the efficacy of these and other              • Sudomotor/edema: evidence of edema and/or
new and promising treatments.”41                                      sweating changes and/or sweating asymmetry
                                                                   • Motor/trophic: evidence of decreased range
                         TABLE 2                                      of motion and/or motor dysfunction (weak-
                                                                      ness, tremor, dystonia) and/or trophic chang-
                                                                      es (hair, nail, skin)
Proposed Clinical Diagnostic Criteria For CRPS:
2003 Consensus Workshop42                                          4. There is no other diagnosis that better ex-
                                                             plains the signs and symptoms
      General definition of the syndrome – CRPS de-
scribes an array of painful conditions that are charac-            For research purposes, the diagnostic decisions
terized by a continuing (spontaneous and/or evoked)          rule should be at least one symptom in all four symp-
regional pain that is seemingly disproportionate in          tom categories and at least one sign (observed at eval-
time or degree to the usual course of any known              uation) in two or more sign categories.
trauma or other lesion. The pain is regional (not in               However, it is possible that if these dual sets
a specific nerve territory or dermatome) and usually         of criteria are validated and accepted by the IASP, a
has a distal predominance of abnormal sensory, mo-           much more confusing situation will exist than what
tor, sudomotor, vasomotor, and /or trophic findings.         is current, as physicians struggle to identify which pa-
The syndrome shows variable progression over time.           tient does or does not have CRPS. From a law­related
      To make the clinical diagnosis, the following crite-   standpoint, this ambiguity as to which criteria to use
ria must be met:                                             to make the diagnosis of CRPS further complicates
      1. Continuing pain, which is disproportionate          resolution of the issues in a compensation setting.
to any inciting event.                                             The consensus workshop approach, as a meth-
      2. Must report at least one symptom in three of        od of formulating the CRPS diagnostic criteria, has
the four following categories:                               been criticized as a valid method as opposed to ev-
      • Sensory: reports of hyperesthesia and/or al-         idence-based medicine, which relies on application
         lodynia                                             of the scientific method to arrive at diagnostic and
                                                             treatment recommendations.43 Although the par-
      • Vasomotor: reports of temperature asymme-
                                                             ticipants of the consensus workshops are respected
        try and/or skin color changes and /or skin
                                                             experts in the field, each contributes from their own
        color asymmetry
                                                             experiences and biases. As stated by Harden et al.,
      • Sudomotor/edema: reports of edema and/or             “consensus­derived criteria that are not subsequently
         sweating changes and or sweating asymme-            validated may lead to over- or under-diagnosis, and
         try                                                 will reduce the ability to provide timely and optimal
      • Motor/trophic: reports of decreased range of         treatment.”44 Because the recent concepts of CRPS
         motion and/or motor dysfunction (weakness,          are newly defined, “there has been an almost com-
         tremor, dystonia) and/or trophic changes            plete absence of evidence-based information about
         (hair, nail, skin)                                  this condition.”45 It is hoped that future research will
      3. Must display at least one sign at the time of       provide the needed evidence-based information to
evaluation in two or more of the following catego-           provide more definitive diagnostic and treatment pa-
ries:                                                        rameters for CRPS.
      • Sensory: evidence of hyperalgesia (to pin-                 The older articles on RSD specified a series
         prick) and/or allodynia (to light touch and/or      of three progressive stages that each patient went
         temperature sensation and/or deep somatic           through leading to the terminal state of a useless ex-
         pressure and/or joint movement)                     tremity.46 Each of the stages was detailed and defined
      • Vasomotor: evidence of temperature asym-             as to increasing severity of symptoms.47 Further, each
        metry (less than 1 degree centigrade) and/or         stage had a specified duration.48 The recent CRPS
        skin color changes and/or asymmetry                  consensus panels, however, have recommended
                                                                               Complex Regional Pain Syndrome | 167
elimination of the concept of stages, preferring not       porting evidence supplied by the MRI and cerebro-
to characterize the disorder in such restrictive, arti-    spinal fluid evaluation.
ficial constraints, but rather as a continuum of signs           CRPS faces a similar dilemma. The diagnosis
and symptoms49 or possibly a series of subtypes of         is initially made by the clinical history and physi-
CRPS.50                                                    cal examination. Additional laboratory tests help to
       In addition to pain and the associated changes      confirm the diagnosis and eliminate other possible
in limb appearance, abnormalities in motor function        conditions. Of the different types of medical tests
have been described. As reported by Schwartzman            available, imaging procedures such as plain x-rays,
and Kerrigan51 in 43 patients with CRPS, movement          MRI scanning, bone scans, and infrared thermal im-
disorders include tremor of the affected limb as well      aging provide useful, but not conclusive, diagnostic
as difficulties with increased muscle tone, cramping,      information.
and spasm. Further, more complex movement disor-                 Plain film x-rays. An x-ray of an affected limb
ders, such as the inability to initiate movement and       may reveal CRPS by way of bony demineralization
dystonic (i.e., sustained twisting movements) pos-         and deformity of the bony structure due to immobi-
turing, have been noted. These movement disorders          lization from pain. Usually seen with more advanced
support the growing belief that CRPS is not just a         forms of CRPS, patchy regions of osteoporosis are
problem in the affected limb, but rather in parts of       evident in the affected limb.
the brain that controls the limb.52                              MRI scan. Magnetic resonance imaging (MRI)
       In up to 40 percent of the cases in both adults53   provides much greater information about structure
and children,54 CRPS signs and/or symptoms can             and also allows imaging of the soft tissue, not well
“spread” either up the same extremity or appear later      seen with plain x­rays. Various abnormalities seen in
in the same region of the opposite extremity. How-         CRPS include edema (swelling) of the bone marrow,
ever, claims of “total body CRPS” are not due to this      edema of the skin, as well as fluid accumulation of
condition but most likely represent another, unre-         the joints.
lated problem.55                                                 Triple-phase bone scan. A bone scan involves ra-
                                                           dioactive imaging following the injection of a tagged
CRPS Diagnosis: Laboratory Testing                         radioisotope, displaying the isotope uptake in bony
      Physicians order medical tests and diagnostic        structures. This test can identify a number of bone
procedures to answer specific questions, such as: is       disorders such as stress fractures, inflammation, or
there a herniated disc on an MRI, or does the patient      cancer. A triple-phase bone scan refers to imaging
have high cholesterol or triglyceride levels? Medical      performed at three different times after the radioiso-
testing can generally be divided into several types:       tope injection. Characteristic findings in CRPS in-
laboratory testing of body fluids (e.g., blood, spinal     clude diffuse uptake in the affected extremity as well
fluid, urine), electrophysiologic testing (e.g., elec-     as localized uptake in and around the joints of the
trocardiogram, electromyogram, electroencephalo-           extremity.
gram), examination of body tissue (e.g., biopsy, sur-            Thermal imaging. Thermography employs an
gical specimens), and imaging (e.g., x­ray, CT scan,       infrared sensing camera that captures the body’s sur-
MRI scan). At the present time, unfortunately, there       face temperature and displays it on a video monitor,
is no diagnostic test specific for CRPS.                   mapping out in coded colors the various body sur-
      Although this limitation may seem difficult to       face temperature gradients. This is a unique imaging
understand, it is not an unusual situation. For ex-        test because it displays a physiologic function (body
ample, multiple sclerosis (MS), a neurologic disorder      surface temperature) superimposed on an anatomic
that often leads to progressive disability, has no spe-    part of the body. In the normal condition, body tem-
cific laboratory test that conclusively identifies this    perature is symmetric; that is, the temperature of one
diagnosis. A finding of this disorder is made primar-      side of the body is within one degree centigrade of
ily by the clinical history and examination with sup-      the corresponding opposite side. In CRPS, sympa-

				
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