Chapter 25: Complex Regional Pain Syndrome

Roger M. Atkins

Chapter Outline

Introduction

During the American Civil War, Silas Weir Mitchell et al.137 described a syndrome which occurred in patients who had suffered gunshot injuries to major nerves. Noting that a leading feature was burning pain, he called the condition causalgia. At the beginning of the 20th century, Paul Sudeck,170,171 a clinician in Hamburg, Germany, used the newly invented technique of roentgenology to investigate patients with severe pain after injury. He described a post-traumatic pain syndrome with edema, trophic changes, and osteoporosis. In 1979, the AO group advocated open reduction and rigid internal fixation to prevent fracture disease, which was defined as a combination of circulatory disturbance, inflammation, and pain as a result of dysfunction of joints and muscles.138 In an intriguing vignette, Channon and Lloyd35 noted that finger stiffness after Colles fracture could be either simple or associated with swelling and changes in hand temperature. In the latter case it did not respond well to physiotherapy. The modern term for the syndrome described in different circumstances by these researchers is complex regional pain syndrome, usually abbreviated to CRPS. 
CRPS is characterized by abnormal pain, swelling, vasomotor and sudomotor dysfunction, contracture, and osteoporosis. It is used to be considered a rare, devastating complication of injury, caused by abnormalities in the sympathetic nervous system (SNS), and seen mainly in psychologically abnormal patients. Modern research is altering this view radically. This chapter will specifically examine CRPS within the context of orthopedic trauma surgery. For this reason, the emphasis, descriptions, and concepts differ slightly from those routinely found in publications from the International Association for the Study of Pain (IASP). It is important to appreciate that these apparent differences are merely counterpoints. The theme is identical. 

Some Important Definitions

A cardinal feature of CRPS is abnormalities of pain perception which are mainly foreign to orthopedic surgeons. They have been codified by Merskey and Bogduk,135 and since they will be used throughout this text, they are described here. 
Allodynia (literally “other pain”) is a painful perception of a stimulus which should not usually be painful. Thus, for example, a patient will find gentle stroking of the affected part painful. Allodynia differs from referred pain, but allodynic pain can occur in areas other than the one stimulated. There are several forms of allodynia: 
Mechanical (or tactile) allodynia implies pain in response to touch. It may be subdivided into static mechanical allodynia, implying pain in response to light touch or pressure, and dynamic mechanical allodynia, where pain is due to brushing.121 
In thermal (hot or cold) allodynia, the pain is caused by mild changes in skin temperature in the affected area. 
Hyperalgesia is an increased sensitivity to pain, which may be caused by damage to nociceptors or peripheral nerves. Thus the patient finds gentle touching with a pin unbearably painful. Hyperalgesia is usually experienced in focal, discrete areas, typically associated with injury. Focal hyperalgesia may be divided into two subtypes: 
  •  
    Primary hyperalgesia describes pain sensitivity that occurs directly in the damaged tissues.
  •  
    Secondary hyperalgesia describes pain sensitivity that occurs in the surrounding undamaged tissues.
Rarely, hyperalgesia is seen in a more diffuse, body-wide form. 
Hyperpathia is a temporal and spatial summation of an allodynic or hyperalgesic response. The patient finds gentle touching painful, but repetitive touching either on the same spot or on another part of the affected limb becomes increasingly unbearable, and the pain continues for a prolonged period after the stimulus has been withdrawn. In severe cases the pain may be accentuated by unusual, extraneous things such as the sudden noise of a door shutting or a draft of cold air. 
It is important for the orthopedic surgeon to realize that these patients are not malingering or mad. These are genuine perceptions of pain. 

A Historic View of Taxonomy

A historic review of nomenclature will help to elucidate much confusion which surrounds this condition. In the past, CRPS was diagnosed using a variety of nonstandardized and idiosyncratic diagnostic systems derived solely from the authors’ clinical experiences, none of which achieved wide acceptance. The condition was given a number of synonyms (Table 25-1) reflecting the site affected, cause, and clinical features. During the American Civil War, Mitchell137 noted the burning nature of pain following nerve trauma and described this as causalgia (from the Greek “burning pain”). In contrast, in the 1900s, Sudeck170,171 investigated conditions characterized by severe osteoporosis, including some cases of CRPS. The condition was named Sudeck atrophy by Nonne140 in 1901. Leriche113,114 demonstrated that sympathectomy could alter the clinical features associated with post-traumatic osteoporosis, and De Takats43 suggested reflex dystrophy in 1937. Evans52 introduced the term reflex sympathetic dystrophy (RSD) based on the theory (following Leriche’s observations) that sympathetic hyperactivity was involved in the pathophysiology, and this term was popularized by Bonica.21 In 1940, Homans95 proposed minor causalgia to imply a relationship between Mitchell’s causalgia, renamed major causalgia, and similar conditions arising without direct nerve injury. Causalgic state42 and mimo-causalgia144 followed to add to the confusion. Today the term causalgia is reserved for the original Mitchell’s use in which a major nerve injury produces burning pain.166 
 
Table 25-1
Synonyms for Complex Regional Pain Syndrome
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Table 25-1
Synonyms for Complex Regional Pain Syndrome
Complex regional pain syndrome
Reflex sympathetic dystrophy
Sudeck atrophy
Causalgia
Minor causalgia
Mimo-causalgia
Algodystrophy
Algoneurodystrophy
Post-traumatic pain syndrome
Painful post-traumatic dystrophy
Painful post-traumatic osteoporosis
Transient migratory osteoporosis
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Steinbrocker168 introduced the term shoulder hand syndrome for a condition which may be separate from true CRPS, and algoneurodystrophy was suggested by Glick and Helal.75,76 Algodystrophy, from the Greek “painful disuse,” was introduced by French rheumatologists in the late 1970s.49 
Sympathetically maintained pain (SMP) is characterized by pain, hyperpathia, and allodynia which are relieved by selective sympathetic blockade. The relationship between CRPS and SMP is disputed.166 In CRPS a proportion of the pain is usually sympathetically maintained and is therefore relieved by sympathetic blockade. However in CRPS a process is also taking place which leads to initial tissue edema followed by severe contracture. This is not an inevitable part of SMP.102 SMP is not a particularly helpful concept for the orthopedic surgeon; however, it will be explored further when the etiology of CRPS is considered. 

Modern Taxonomy and Diagnosis

Fortunately, all the above confusion is now of historic interest. The IASP has undertaken a major work in analyzing the features of CRPS and reclassifying the condition.135 IASP changed the name of the condition to CRPS at a consensus workshop in Orlando, Florida, in 199419,166 and proposed new standardized diagnostic criteria (Table 25-2).135 A broad description of CRPS is as follows25,88
Table 25-2
The Original IASP Diagnostic Criteria for Complex Regional Pain Syndrome
  1.  
    The presence of an initiating noxious event, or a cause of immobilization
     
    (Not required for diagnosis; 5–10% of patients will not have this).
  2.  
    Continuing pain, allodynia, or hyperalgesia in which the pain is disproportionate to any known inciting event.
  3.  
    Evidence at some time of edema, changes in skin blood flow, or abnormal sudomotor activity in the region of pain (can be sign or symptom).
  4.  
    This diagnosis is excluded by the existence of other conditions that would otherwise account for the degree of pain and dysfunction.

If the condition occurs in the absence of “major nerve damage,” the diagnosis is CRPS-1.
If “major nerve damage” is present, the diagnosis is CRPS-2.
 

(Adapted from Merskey H, Bogduk N. Classification of Chronic Pain: Descriptions of Chronic Pain Syndromes and Definitions of Pain Terms. Seattle, WA: IASP Press; 1994.)

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“CRPS describes an array of painful conditions that are characterized by a continuing (spontaneous and/or evoked) regional pain that is seemingly disproportionate in time or degree to the usual course of any known trauma or other lesion. The pain is regional (not in a specific nerve territory or dermatome) and usually has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings, including osteoporosis. The syndrome shows variable progression over time.” 
CRPS was divided into CRPS type 2 (CRPS-2), where the cause was direct nerve damage, and CRPS type 1 (CRPS-1), where it was not. These syndromes may have different clinical features,24; however, the distinction becomes blurred since postsurgery CRPS, where one might assume peripheral nerves to be damaged, is invariably classified as CRPS-1.129 Furthermore, in amputation and biopsy specimens from CRPS-1 cases, small (C and Aδ) nerve fiber degeneration is seen.1,141 From a surgeon’s perspective, the most useful distinction would be a diagnosis of CRPS-2 where nerve damage susceptible to surgical intervention was causative, for example, sural nerve entrapment following a percutaneous tendo Achilles repair. 

Clinical Features

Since the etiology of CRPS is obscure, the diagnosis must be clinical, and therefore, precise descriptions of symptoms and signs acquire great importance. Classical descriptions emphasize three sequential stages.20,43,49,74,161,162,183 Modern evidence suggests that CRPS does not always follow this course14,24,183,200,201 and supports the clinical impression that this evolution is seen in more severe cases (as might be expected from historic series). Since the classical descriptions provide the greatest information concerning clinical features, the following description will refer to the staging system where helpful. 
CRPS is a biphasic condition with early swelling and vasomotor instability (VMI) giving way over a variable timescale to late contracture and joint stiffness.49 The hand and foot are most frequently involved, although the knee is increasingly recognized.38,39,104 The elbow is rarely affected, whereas shoulder disease is common and some cases of frozen shoulder are probably CRPS.168 The hip is affected in transient osteoporosis of pregnancy. 
CRPS usually begins up to a month after the precipitating trauma, although the delay may be greater. Antecedent trauma is not essential, but within an orthopedic context it is almost invariable.49 As the direct effects of injury subside, a new diffuse, unpleasant, neuropathic pain arises.194 Neuropathic pain is a pain which occurs without any precipitating noxious stimulus; and spontaneous or burning pain, mechanical or thermal hyperalgesia, allodynia, and hyperpathia are common but not universal features.51,125,135,163 Pain is unremitting (although sleep may be unaffected), worsening, and radiating with time and may be increased by limb dependency, physical contact, emotional upset, or even by extraneous factors such as sudden loud noise or a blast of cold air. 

Early Phase of CRPS

VMI and edema dominate the early phase (Fig. 25-1), although this is less marked with more proximal CRPS. The classical description of the temporal evolution of the condition divides the early phase of CRPS into two stages depending on the type of the VMI.49 In this description, initially the limb is dry, hot, and pink (vasodilated, stage 1), but after a variable period of days to weeks, it becomes blue, cold, and sweaty (vasoconstricted, stage 2). As noted above, this classical evolution is rarely seen. Most commonly, especially in more mild cases, the VMI is characterized by an increase in temperature sensitivity, with variable abnormality of sweating. Alternatively, some patients remain substantially vasodilated, while others are vasoconstricted with no history of vasodilatation.14,24,183,199 
Figure 25-1
A patient with early CRPS-1 affecting the leg.
 
Note the swelling of the leg and the discoloration of the shin.
Note the swelling of the leg and the discoloration of the shin.
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Figure 25-1
A patient with early CRPS-1 affecting the leg.
Note the swelling of the leg and the discoloration of the shin.
Note the swelling of the leg and the discoloration of the shin.
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In the early phase of CRPS, edema is marked, particularly where the distal part of the limb is affected. Initially the edema is simple tissue swelling and may be overcome by physical therapy and elevation if the patient will permit. With time (in the classical description, passing from stage 1 to stage 2), the edema becomes more fixed and indurated with coalescence of tissue planes and structures. 
Initially, in the early phase of CRPS, loss of joint mobility is due to swelling and pain combined with an apparent inability to initiate movement or state of neglect or denial with respect to the limb.3032,64,6668,111,151 Weakness, dystonia, spasms, tremor, and myoclonus have also been reported17,161,178,179; however, these are not usually prominent within an orthopedic context. As the early phase progresses, loss of joint mobility is increasingly due to development of contracture. Only if the disease can be halted before fixed contracture has occurred can complete resolution occur. 

Late Phase of CRPS

Passing into the late phase, VMI recedes, edema resolves, and atrophy of the limb occurs (Fig. 25-2), affecting every tissue. The skin is thinned, and joint creases and subcutaneous fat disappear. Hairs become fragile, uneven, and curled, while nails are pitted, ridged, brittle, and discolored brown. Palmar and plantar fascias thicken and contract simulating Dupuytren disease.49,120 Tendon sheaths become constricted causing triggering and increased resistance to movement. Muscle contracture combined with tendon adherence leads to reduced tendon excursion. Joint capsules and collateral ligaments become shortened, thickened, and adherent, causing joint contracture. 
Figure 25-2
The late phase of CRPS.
 
A: Detail of the thumbs of a patient with late CRPS-1 of the right hand. There is spindling of the digit particularly distally. The nail is excessively ridged and is discolored. B: The hand of a patient with late CRPS-1. The patient is trying to make a fist. Note the digital spindling and extension contractures with loss of joint creases.
A: Detail of the thumbs of a patient with late CRPS-1 of the right hand. There is spindling of the digit particularly distally. The nail is excessively ridged and is discolored. B: The hand of a patient with late CRPS-1. The patient is trying to make a fist. Note the digital spindling and extension contractures with loss of joint creases.
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Figure 25-2
The late phase of CRPS.
A: Detail of the thumbs of a patient with late CRPS-1 of the right hand. There is spindling of the digit particularly distally. The nail is excessively ridged and is discolored. B: The hand of a patient with late CRPS-1. The patient is trying to make a fist. Note the digital spindling and extension contractures with loss of joint creases.
A: Detail of the thumbs of a patient with late CRPS-1 of the right hand. There is spindling of the digit particularly distally. The nail is excessively ridged and is discolored. B: The hand of a patient with late CRPS-1. The patient is trying to make a fist. Note the digital spindling and extension contractures with loss of joint creases.
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It is important to restate that the progression of CRPS is very variable. Within orthopedic practice, the large majority of patients who demonstrate the features of the early phase of CRPS after trauma will not go on to develop severe late-phase contracture, although a significant proportion will show chronic subclinical contracture.61 

Bone Changes

Bone involvement is universal with increased uptake on bone scanning in early CRPS (Fig. 25-3). This was originally thought to be periarticular, suggesting arthralgia94,109,124; however, CRPS does not cause arthritis, and more recent studies have shown generalized hyperfixation,6,37,45 confirming the view of Doury.49 Increased uptake is not invariable in children.192 Later, the bone scan returns to normal, and there are radiographic features of rapid bone loss: Visible demineralization with patchy, subchondral, or subperiosteal osteoporosis; metaphyseal banding; and profound bone loss (Fig. 25-4).110 Despite the osteoporosis, fracture is uncommon, presumably because the patients protect the painful limb very effectively. 
Figure 25-3
Bone scan changes in CRPS.
 
The delayed phase of a bone scan of a patient with early CRPS-1 of the lower leg. There is increased uptake throughout the affected region. The bone scan will usually revert to normal after 6 months.
The delayed phase of a bone scan of a patient with early CRPS-1 of the lower leg. There is increased uptake throughout the affected region. The bone scan will usually revert to normal after 6 months.
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Figure 25-3
Bone scan changes in CRPS.
The delayed phase of a bone scan of a patient with early CRPS-1 of the lower leg. There is increased uptake throughout the affected region. The bone scan will usually revert to normal after 6 months.
The delayed phase of a bone scan of a patient with early CRPS-1 of the lower leg. There is increased uptake throughout the affected region. The bone scan will usually revert to normal after 6 months.
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Figure 25-4
Radiographic features of CRPS.
 
A: Oblique radiograph of a patient with CRPS-1 of the foot. There is patchy osteoporosis with accentuation of the osteoporosis beneath the joints. B: Profound osteoporosis in a patient with late severe CRPS-1 affecting the hand.
A: Oblique radiograph of a patient with CRPS-1 of the foot. There is patchy osteoporosis with accentuation of the osteoporosis beneath the joints. B: Profound osteoporosis in a patient with late severe CRPS-1 affecting the hand.
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Figure 25-4
Radiographic features of CRPS.
A: Oblique radiograph of a patient with CRPS-1 of the foot. There is patchy osteoporosis with accentuation of the osteoporosis beneath the joints. B: Profound osteoporosis in a patient with late severe CRPS-1 affecting the hand.
A: Oblique radiograph of a patient with CRPS-1 of the foot. There is patchy osteoporosis with accentuation of the osteoporosis beneath the joints. B: Profound osteoporosis in a patient with late severe CRPS-1 affecting the hand.
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Incidence

It is the common experience of orthopedic surgeons that patients such as shown in Figure 25-2 are extremely rare. Thus severe, chronic CRPS associated with severe contracture is uncommon with a reported prevalence of less than 2% in historic retrospective series.9,82,116,122,147 Two recent population-based studies have yielded contrasting results with 5.5 cases per 100,000 person-years in the United States155 and 26.2 per 100,000 person-years in the Netherlands41 In contrast, prospective studies designed to look specifically for the early features of CRPS show that they occur after up to 30% of fractures and surgical trauma (e.g., total knee replacement)3,4,8,14,15,56,90,156,157,164 where the features of CRPS have been actively sought. Furthermore, statistically, the features tend to occur together.4,156 These common early cases of CRPS are usually not specifically diagnosed,164 and some would, controversially, dispute the diagnosis.16 They resolve substantially either spontaneously or with standard treatment by physical therapy and analgesia within a year.14,15,119,164 Some features, particularly stiffness, may remain suggesting that CRPS may be responsible for significant long-term morbidity even when mild.14,61 The truly intriguing question is, if CRPS is so common, why is it not a universal finding after trauma or orthopedic surgery? 

Etiology

CRPS may occur after any particular trauma while an identical stimulus in a different limb does not cause it. The incidence is not changed by treatment method and open anatomic reduction, and rigid internal fixation does not abolish it.157 It is unclear whether injury severity or quality of fracture reduction alters the incidence.4,15 There is, however, an association with excessively tight casts,60 and there may be a genetic predilection.46,105,108,127,128 The following etiologies have been proposed. 

Psychological Abnormalities

A psychological cause for chronic pain was first suggested by Breuer and Freud,22 and historically, it has been suggested that CRPS may be purely a psychological problem.36 Most orthopedic clinicians immediately recognize a “Sudecky” patient, that is, broadly speaking, a patient who appears to the clinician to be somebody who is likely to fare poorly after surgical intervention or trauma perhaps due to their inability to cooperate fully with physical therapy. In fact, the literature fails to identify this sort of patient and the evidence does not support the notion that CRPS is primarily psychological.27 Studies of premorbid personality show no consistent abnormality.139,198 Most patients are psychologically normal184 although emotional lability, low pain threshold,44 hysteria,145 and depression169 have been reported. There is an association with antecedent psychological stress23,27,58,6972,182 which probably exacerbates pain in CRPS, as in other diseases.26 It seems likely that the severe chronic pain of CRPS causes depression and that a “Sudecky” type of patient who develops CRPS is at risk of a poor outcome because they will not mobilize in the face of pain. 

Abnormal (Neuropathic) Pain

CRPS is characterized by excessive and abnormal pain. Pain is usually caused when an intense noxious stimulus activates high-threshold nociceptors, and it prevents tissue damage. Neuropathic pain in CRPS occurs without appropriate stimulus and has no protective function. However, injured peripheral nerve fibers undergo cellular changes which cause usually innocuous tactile inputs to stimulate the dorsal horn cells via A-β fibers from low-threshold mechanoreceptors, causing allodynia in CRPS-2.103,195 Similar C-nociceptor dysfunction explains causalgia. Furthermore, axonal injury prevents nerve growth factor transport which is essential for normal nerve function.118,194 In CRPS-1, covert nerve lesions with artificial synapses have been postulated.48 These “ephases” have not been demonstrated and are unnecessary since inflammatory mediators released by the initial trauma (and possibly retained due to a failure of free radical clearance) can sensitize nociceptors to respond to normally innocuous stimuli.137,138 

Sympathetic Nervous System (SNS) Abnormalities

That CRPS is associated with apparent abnormalities in the SNS is obvious. Hence the popularity of the eponym RSD. Furthermore, since Leriche’s early studies,113,114 generations of therapists have treated CRPS with sympathetic manipulation, noting an acute change in the clinical features,34,77,8487,97 although recent studies cast some doubt on whether sympathetic manipulation improves the long-term outcome of the condition.98,119 
The features of CRPS which suggest SNS dysfunction include abnormalities in skin blood flow, temperature regulation and sweating, and edema. However, SNS activity is not usually painful.99,100 In CRPS, however, some pain (termed SMP166) is SNS-dependent. This accounts for spontaneous pain and allodynia, which may therefore be relieved by stellate ganglion blockade148 and then restored by noradrenalin injection.2,173 Furthermore, there is an abnormal difference in cutaneous sensory threshold between the limbs, which is reversed by sympathetic blockade,59,63,149,150 while increasing sympathetic activity worsens pain.101 
What then is the cause of SMP in CRPS? It is due to the body’s reaction to injury. After partial nerve division, injured and uninjured somatic axons express α-adrenergic receptors,33 and sympathetic axons come to surround sensory neuron cell bodies in dorsal root ganglia.134,186,194 These changes, which may be temporary,173,185,187 make the somatic sensory nervous system sensitive to circulating catecholamines and noradrenalin released from postganglionic sympathetic terminals. 

Abnormal Inflammation

CRPS resembles an inflammatory state leading to gross scarring. Therefore, the orthopedic differential diagnoses are occult causes of inflammation such as soft tissue infection or stress fracture. CRPS is associated with inflammatory changes including macromolecule extravasation143 and reduced oxygen consumption.80,175 Serum concentrations of substance P, a neuropeptide associated with inflammatory processes and pain,159 and calcitonin gene-related peptide (CGRP)18 are higher in CRPS patients than controls, causing an augmented flare response129 and excessive protein extravasation.112 Substance P stimulates keratinocytes to express cytokines in vitro,40 and keratinocytes in skin biopsies from CRPS-affected limbs show increased substance P receptors.107,129 This suggests that excess neuropeptide activity causes extravasation, limb edema, and increased cytokine expression that characterize CRPS. However, how the immune and nervous systems interact in the bones, muscles, and connective tissue is not understood. 
Cytokine levels are higher in CRPS-affected limbs than in the contralateral limb or control patients.83,96,174 These changes do not correlate well with the clinical features except in mechanical hyperalgesia.126 
In animals, infusion of free radical donors causes a CRPS-like state,176 and amputated human specimens with CRPS show basement membrane thickening consistent with overexposure to free radicals.177 This suggests that CRPS is an exaggerated local inflammatory response to injury79,81 and that CRPS represents a local form of the systemic free radical disease that causes adult respiratory distress syndrome and multiple organ failure after severe trauma. This concept is supported by the preliminary evidence that the free radical scavenger vitamin C is an effective prophylaxis against post-traumatic CRPS.196,197 
An alternative explanation for the inflammatory changes in early CRPS is a primary capillary imbalance causing stasis, extravasation, and consequent local tissue anoxia.54,55,131,153 
The aberrant inflammatory response to tissue injury in CRPS does not seem to be caused by a cellular-mediated immune response since ESR, antigen titers, autoimmune antibody concentrations, and blood cell counts are all normal, and in histologic studies there is minimal inflammatory cell infiltrate.154,160,183 

Immobilization and Failure to Use the Affected Limb

The popular French term for CRPS, algodystrophy, means painful disuse.49 It is a common clinical observation that patients who appear to be at risk of developing CRPS are unable or unwilling to cooperate with physical therapy to mobilize their limb after trauma or orthopedic surgery. Indeed, undue immobilization has traditionally been believed to be at least an important contributory factor in the generation of CRPS or even the sole cause.10,53,138,189 
CRPS obviously involves a significant abnormality of afferent sensory perception, but only recently has the possibility of abnormal efferent motor function been systematically explored. Classically, it was believed that the “immobile RSD limb” was guarded by the patient in order to prevent inadvertent painful movement or sensory contact.49,67 In fact, CRPS is associated with an abnormality of motor function which is often overlooked partially due to patient embarrassment and partly because in the past it has been labeled as hysterical.36,179 In 1990, Schwartzman and Kerrigan161 reported a subgroup of CRPS patients with a variety of motor disorders, and a minority of patients with CRPS demonstrate obvious dystonia or spasms.11,12,50,130 A prospective study of 829 CRPS patients showed that abnormalities of motor function were reported by 95%, varying from weakness to incoordination and tremor.183 Objective testing in small numbers of patients shows that CRPS patients have impaired grip force coordination, target reaching, and grasping.158,190 
Interviews with patients suggest further possible reasons for the lack of movement in CRPS. Patients demonstrate evidence of “neglect” of the affected limb, similar to that seen after parietal lobe stroke. When asked about moving the limb, statements are made such as “… my limb feels disconnected from my body …” and “… I need to focus all my mental attention and look at the limb in order for it to move the way I want …”.66 Another study revealed bizarre perceptions about a body part including a desperate desire for amputation. There was a mismatch between limb sensation and appearance with mental erasure of the affected part. These authors suggested the term “body perception disturbance” rather than “neglect” to describe this phenomenon.115 There appears to be a central sensory confusion, in that when a non-noxious stimulus is provided, which the patient finds painful due to allodynia, the patient is unable to determine whether it is truly painful, and by impairing integration between sensory input and motor output, movement is impaired.93,132 
Overall, in CRPS, patients tend to ignore their affected limb and find it difficult to initiate or accurately direct movement, and there is a mismatch between sensation, perception, and movement.32,67,179 Failure to use the limb appears to relate to this rather than the traditional view of learned pain avoidance behavior in response to allodynia. Whatever the exact cause, failure of mobilization may be central to the etiology of CRPS since all the features of phase 1 CRPS, except pain, are produced in volunteers after a period of cast immobilization.3032 This may be explained by the fact that activity-dependent gene function is common in the nervous system,194 and normal tactile and proprioceptive input are necessary for correct central nerve signal processing.117,129 
A study of the treatment with mirror visual feedback (MVF) supports the central role of movement disorder in CRPS.132 The rationale for MVF is restoration of the congruence between sensory and motor information, and it was originally used for the treatment of phantom limb pain.152 Patients are instructed to exercise both the unaffected and the affected limb. However, a mirror is placed so that they cannot see the affected limb, and when they think they are looking at it, they are actually observing the mirror image of their normal limb. As might be expected, MVF resulted in improvement in range of movement; however, in addition, in early CRPS, MVF also abolished or substantially improved pain and VMI.133 

Making a Diagnosis

Considerable confusion has been generated by a failure to understand the recent work from the IASP. In 1994, when the IASP produced the new diagnostic entity of CRPS, it was descriptive and general and based on a consensus.135 Deliberately, it did not imply any etiology or pathology (including any direct role for the SNS). The intention was to provide an officially endorsed set of standardized diagnostic criteria to improve clinical communication and facilitate research.136 In other words, this was intended as a starting point from which individual researchers could move forward. It was not thought of as a mature clinical diagnostic device, and further validation has been carried out.89 
Since their original publication, the diagnostic criteria have been validated, refined, and developed. The validation studies suggest that the original criteria are adequately sensitive within the context of a pain clinic (i.e., they rarely miss a case of actual CRPS); however, the criteria cause problems of over-diagnosis due to poor specificity.65,88 Comparison of CRPS patients to other proven pain states such as chronic diabetic patients with ascending symmetrical pain, whose neuropathy is confirmed by nerve conduction studies, also shows that the criteria are very sensitive but have low specificity, so that a diagnosis of CRPS may be erroneous in up to 60% of cases.25 
Other problems are evident. For example, the criteria assume that any sign or symptom of vasomotor, sudomotor, and edema-related change is sufficient to justify the diagnosis, and there is no possibility of providing greater diagnostic or prognostic accuracy by observing more than one of these features. An additional weakness is the failure to include motor or trophic signs and symptoms. Numerous studies have described various signs of motor dysfunction (e.g., dystonia, tremor) as important characteristics of this disorder, and trophic changes have frequently been mentioned in historical clinical descriptions.161,162 These differentiate CRPS from other pain syndromes.65,162 Finally, the wording of the criteria permits diagnosis based solely on patient-reported historical symptoms. This may be inappropriate in the context of litigation. 
Factor analysis of 123 CRPS patients has indicated that the features cluster into four statistically distinct subgroups.88 
  1.  
    A set of signs and symptoms indicating abnormalities in pain processing (e.g., allodynia, hyperalgesia, hyperpathia)
  2.  
    Skin color and temperature changes, indicating vasomotor dysfunction
  3.  
    Edema and abnormalities of sweating
  4.  
    Motor and trophic signs and symptoms
The statistical separation of edema and sudomotor dysfunction from VMI and the finding of motor and trophic abnormalities are at variance with the original IASP criteria which were therefore modified (Table 25-325,65,88) The important changes are inclusion of clinical signs, their separation from symptoms, and the inclusion of features of motor abnormalities and trophic changes. Intriguingly these sub-groups are virtually identical to those suggested by our group a decade earlier.4 
 
Table 25-3
The Modified IASP Diagnostic Criteria for CRPS
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Table 25-3
The Modified IASP Diagnostic Criteria for CRPS
General definition of the syndrome: CRPS describes an array of painful conditions that are characterized by a continuing (spontaneous and/or evoked) regional pain that is seemingly disproportionate in time or degree to the usual course of any known trauma or other lesion. The pain is regional (not in a specific nerve territory or dermatome) and usually has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings. The syndrome shows variable progression over time.
To make the clinical diagnosis, the following criteria must be met (sensitivity 0.85, specificity 0.69):
  1.  
    Continuing pain, which is disproportionate to any inciting event
  2.  
    Must report at least one symptom in three of the four following categories:
     
    Sensory: Reports of hyperesthesia and/or allodynia
     
    Vasomotor: Reports of temperature asymmetry and/or skin color changes and/or skin color asymmetry
     
    Sudomotor/edema: Reports of edema and/or sweating changes and/or sweating asymmetry
     
    Motor/trophic: Reports of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)
  3.  
    Must display at least one sign at the time of evaluation in two or more of the following categories:
     
    Sensory: Evidence of hyperalgesia (to pinprick) and/or allodynia (to light touch and/or temperature sensation and/or deep somatic pressure and/or joint movement)
     
    Vasomotor: Evidence of temperature asymmetry (>1°C) and/or skin color changes and/or asymmetry
     
    Sudomotor/edema: Evidence of edema and/or sweating changes and/or sweating asymmetry
     
    Motor/trophic: Evidence of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia)and/or trophic changes (hair, nail, skin)
  4.  
    There is no other diagnosis that better explains the signs and symptoms
     
    For research purposes, the diagnostic decision rule should be at least one symptom in all four symptom categories and at least one sign (observed at evaluation) in two or more sign categories (sensitivity 0.70, specificity 0.94).
 

(Data from Bruehl S, et al. External validation of IASP diagnostic criteria for complex regional pain syndrome and proposed research diagnostic criteria. International Association for the Study of Pain. Pain. 1999;81(1–2):147–154; Harden RN, et al. Complex regional pain syndrome: Are the IASP diagnostic criteria valid and sufficiently comprehensive? Pain. 1999;83(2):211–219.)

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Statistical analysis has been undertaken to investigate sensitivity and specificity of decision rules for diagnosis of CRPS compared to neuropathic pain of a proven non-CRPS cause using these criteria (Table 25-425). These propose different diagnostic criteria depending on the clinical circumstances. Thus for purely clinical diagnosis, the criteria provide a sensitivity of 0.85 and a specificity of 0.69, whereas for research diagnosis, the criteria provide a sensitivity of 0.7 and a specificity of 0.94, since in the former circumstance, one wishes to avoid failing to offer treatment to a possible candidate, while in the latter situation one is more concerned to be investigating a homogeneous group in whom the diagnosis cannot be in doubt. 
 
Table 25-4
Diagnostic Sensitivity and Specificity for the IASP Modified Criteria (Table 25-3) in Distinguishing CRPS from Patients with Neuropathic Pain from a Documented Non-CRPS Cause
View Large
Table 25-4
Diagnostic Sensitivity and Specificity for the IASP Modified Criteria (Table 25-3) in Distinguishing CRPS from Patients with Neuropathic Pain from a Documented Non-CRPS Cause
Decision Rule Sensitivity Specificity
2+ sign categories & 2+ symptom categories 0.94 0.36
2+ sign categories & 3+ symptom categories 0.85 0.69
2+ sign categories & 4 symptom categories 0.70 0.94
3+ sign categories and 2+ symptom categories 0.76 0.81
3+ sign categories and 3+ symptom categories 0.70 0.83
3+ sign categories and 4 symptom categories 0.86 0.75
 

(From Bruehl S, et al. External validation of IASP diagnostic criteria for complex regional pain syndrome and proposed research diagnostic criteria. International Association for the Study of Pain. Pain. 1999;81(1–2):147–154.)

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It is critical to understand that the Bruehl modification of the original IASP criteria25 given in Table 25-3 applies to the diagnosis of CRPS within a pain clinic setting and is therefore intended to differentiate CRPS from other causes of chronic pain within that setting. They do not apply directly to the diagnosis of CRPS within the context of an orthopedic practice. The reason for this apparent conundrum is that the precise nature of CRPS remains unclear, and it is therefore a diagnosis of exclusion. Conditions from which CRPS must be distinguished in a pain clinic (e.g., neuropathic pain in association with diabetic neuropathy) are different from those which apply in an orthopedic or fracture clinic (e.g., soft tissue infection or stress fracture). Therefore, the diagnostic criteria must be slightly different, just as slightly different criteria are required within a pain clinic for diagnosis of CRPS depending on whether the diagnosis is being made for clinical or research purposes. 
Atkins et al.3 proposed a set of diagnostic criteria for CRPS specifically in an orthopedic context (Table 25-535). These were derived empirically in a manner similar to the IASP approach but critically in a fracture clinic rather than a pain clinic environment. The criteria were designed to be as far as possible objective but the patient’s veracity was assumed, so no attempt was made to separate reports of vasomotor or sudomotor abnormalities from observation of them. A number of criteria are quantifiable,3,4,62 which allows their powerful use to investigate treatment.57,59,119 The original criteria were developed in the context of CRPS of the hand following Colles fracture of the wrist, but they have subsequently been generalized for use in the diagnosis of CRPS in other orthopedic scenarios and in the lower limb.14,157 Diagnosis by these criteria, when used after Colles fracture, maps virtually exactly with the Bruehl criteria suggesting their reliability.172 
Table 25-5
Suggested Criteria for the Diagnosis of CRPS Within an Orthopedic Setting
The diagnosis is made clinically by the finding of the following associated sets of abnormalities:
  1.  
    Neuropathic pain. Nondermatomal, without cause, burning, with associated allodynia and hyperpathia.
  2.  
    Vasomotor instability and abnormalities of sweating. Warm red and dry, cool blue, and clammy or an increase in temperature sensitivity. Associated with an abnormal temperature difference between the limbs.
  3.  
    Swelling.
  4.  
    Loss of joint mobility with associated joint and soft tissue contracture, including skin thinning and hair and nail dystrophy.
These clinical findings are backed up by:
  1.  
    Increased uptake on delayed bone scintigraphy early in CRPS
  2.  
    Radiographic evidence of osteoporosis after 3 months
The diagnosis is excluded by the existence of conditions that would otherwise account for the degree of dysfunction.
 

Modified from Atkins RM, Duckworth T, Kanis JA. Algodystrophy following Colles’ fracture. J Hand Surg Br. 1989;14(2):161–164; Atkins RM, Duckworth T, Kanis JA. Features of algodystrophy after Colles’ fracture. J Bone Joint Surg Br. 1990;72(1):105–110.

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Clinical Diagnosis in an Orthopedic Setting

  •  
    1. Pain
     
    A history of excessive pain is elicited. Abnormalities of pain perception are examined in comparison with the opposite normal side. Excessive tenderness is found by squeezing digits in the affected part between thumb and fingers. This may be quantitated using dolorimetry, but this is usually a research tool.5,7 Allodynia is demonstrated by fine touch and hyperalgesia using a pin. Hyperpathia is examined by serial fine touch or pin prick.
  •  
    2a. Vasomotor instability
  •  
    VMI is often transitory, and so it may not be present at the time of examination. If the patient is reliable, then a history confirms its presence. Visual inspection is the usual means of diagnosis.
     
    Thermography can be used to quantitate temperature difference between the limbs. This is greater in CRPS than other pain syndromes,146,188 and this can be used to distinguish CRPS from other causes of neuropathic pain. However, thermography has not been validated within an orthopedic context and must therefore be employed with caution. It is not usually used in an orthopedic context.
  •  
    2b. Abnormal sweating
     
    Whether this feature should be considered with VMI as proposed by Atkins4,7 or should be with edema as suggested recently by Harden88 is as yet unclear. As for VMI, the feature is inconstant, and it may be necessary to rely on history. Excessive sweating is usually clinically obvious. In a doubtful case, the resistance to a biro or a pencil gently stroked across the limb is useful. The extent of sweating can be quantified by iontophoresis, but this is rarely undertaken.
  •  
    3. Edema and swelling
     
    This is usually obvious on inspection. In the hand it may be quantified by hand volume measurement. Similarly, skinfold thickness and digital circumference may be measured.4,7
  •  
    4. Loss of joint mobility and atrophy
     
    Loss of joint mobility is usually diagnosed by standard clinical examination. The range of finger joint movement may be accurately quantified.4,7,62 As outlined above, atrophy will affect every tissue within the limb.
  •  
    5. Bone changes
     
    X-ray appearances and bone scans are discussed above. CRPS does not cause arthritis, and joint space is preserved. Sudeck’s technique of assessing bone density by radiographing two extremities on one plate170,171 remains useful, but densitometry is not usually helpful.13 A normal bone scan without radiographic osteoporosis virtually excludes adult CRPS.

Other Clinical Examinations

Making a diagnosis of “neglect”-like phenomena is relatively easy clinically but may not as yet be useful. Sensory neglect can be elucidated either by history or direct sensory examination with the patient watching or looking away from the affected limb. Motor neglect is examined by asking the patient to undertake a simple task initially while looking away and then while watching the limb. In the upper limb this can be repetitively opening the closing the fingers, or in the lower limb tapping the foot. If there is a significant improvement when the patient is watching the limb, a degree of motor neglect is present.67 

Investigations

CRPS is a clinical diagnosis and there is no single diagnostic test. The classic case is obvious, and direct effects of trauma, fracture, cellulitis, arthritis, and malignancy are common alternative diagnoses. The patient is systemically well with normal general clinical examination, biochemical markers, and infection indices. 
The MRI shows early bone and soft tissue edema with late atrophy and fibrosis but is not diagnostic. However in CRPS-2 an MRI scan may be useful to demonstrate nerve thinning with poststenotic dilatation due to compression and may even demonstrate a fibrous band causing the compression. It may also demonstrate neuroma formation; however, many neuromas are too small to be adequately shown. 
CT scanning may also be useful in demonstrating a bony compressing lesion. 
EMG and nerve conduction studies are normal in CRPS-1 but may demonstrate a nerve lesion in CRPS-2. 

Differential Diagnosis

Pain, swelling, and VMI are common associations of trauma and orthopedic surgery. The following are common differential diagnoses. 
  1.  
    Soft tissue infection. The clinical features are usually clear. The patient is systemically unwell with raised inflammatory markers.
  2.  
    “Mechanical” problems. Classical examples are incorrect sizing of a total knee replacement causing pain, swelling, and stiffness; overlong screws impinging on a joint; or malreduction of an intra-articular fracture (Fig. 25-5). In accordance with category 4 of the original IASP criteria for CRPS, all mechanical causes for the symptoms and signs must be excluded before making a diagnosis of CRPS. However, it must be borne in mind that the chronic pain of a mechanical problem can itself be the precipitating cause of CRPS.
  3.  
    Conscious exaggeration of symptoms. This is usually seen in the context of litigation, but the secondary gain from exaggeration may also relate to complex and pathologic interpersonal relationships. This problem has been accidentally made more acute and severe by the IASP criteria for CRPS diagnosis. The original criteria (Table 25-2) are readily mimicked by a patient determined to deceive the examining clinician. Unfortunately, the modified criteria may also provide a diagnosis of CRPS in a deceitful patient. Categories 1 and 2 are simple. The patient merely has to report these problems. Category 3 refers to objective criteria. However, sensory abnormalities rely on the patient’s subjective response to stimulus. Skin color change can be caused by deliberate dependency and immobility of the limb. Loss of joint range of movement can be caused by conscious resistant to movement; and dystonia, tremor, and weakness can likewise be produced artifactually. The rise of the internet means that any reasonably determined patient can have a very great knowledge of the features of CRPS and the diagnostic criteria. The solution to this problem is to remember that the IASP criteria are designed to differentiate CRPS from other chronically painful conditions; they are not intended to deal with a patient whose veracity is open to question. CRPS is a condition which inevitably leads to dystrophy,24,49,65,162 and in a patient who has suffered from significant CRPS for any significant length of time, objective features of dystrophy such as nail or hair dystrophy, skin and subcutaneous tissue atrophy, fixed joint contracture, and radiographic features of significant osteoporosis with abnormalities of bone scanning should be present. If the patient’s veracity is in doubt, the astute clinician will give only limited or no credence to those features which can be mimicked and look for incontrovertible physical signs.
  4.  
    Psychiatric disease. Separately from the conscious exaggeration described above, psychiatric disease may cause a patient subconsciously to exaggerate the level or impact of physical disease. Somatoform disorders describe conditions in which patients subconsciously exaggerate physical symptoms, and conversion disorders refer to subconscious exaggeration of physical signs. These patients are often psychologically fragile, they may have a history of an unusually severe reaction to multiple minor medical problems, and they may show a tendency to “catastrophize” life events. In addition to this direct influence on a diagnosis of CRPS, patients with CRPS may be depressed due to chronic pain, and psychiatric disease may play an indirect part in the condition. It is often very useful to obtain formal psychiatric or psychological opinion and treatment.180182
  5.  
    Neuropathic pain. This has been defined and discussed. Neuropathic pain is part of CRPS, but a patient may have neuropathic pain without having CRPS. However, neuropathic pain may give rise to CRPS.
  6.  
    Chronic pain state. Patients with long-lasting and unremitting pain may become depressed, particularly when there is a neuropathic element. They learn to avoid activities which cause pain, and their relatives and carers act to protect them from perceived injury. This generates a complex psychosocial situation which may require psychological, psychiatric, pain therapeutic, and orthopedic combined management.
Figure 25-5
A patient referred with a diagnosis of CRPS.
 
This patient with severe pain in his foot was referred some years after internal fixation of a talar body fracture. He has severe pain and dysfunction. The lateral radiograph shows no evidence of significant osteoporosis, which is inconsistent with the diagnosis. The talar body fracture is not reduced which renders the ankle and sub-talar joints incongruous. Furthermore the screws are overlong and impinge on the ankle joint. This patient does not have CRPS; he has a mechanical cause for his severe pain, which was resolved by talar osteotomy, anatomic reduction, and refixation. It is important to exclude mechanical causes for pain before invoking the diagnosis of CRPS.
This patient with severe pain in his foot was referred some years after internal fixation of a talar body fracture. He has severe pain and dysfunction. The lateral radiograph shows no evidence of significant osteoporosis, which is inconsistent with the diagnosis. The talar body fracture is not reduced which renders the ankle and sub-talar joints incongruous. Furthermore the screws are overlong and impinge on the ankle joint. This patient does not have CRPS; he has a mechanical cause for his severe pain, which was resolved by talar osteotomy, anatomic reduction, and refixation. It is important to exclude mechanical causes for pain before invoking the diagnosis of CRPS.
View Original | Slide (.ppt)
Figure 25-5
A patient referred with a diagnosis of CRPS.
This patient with severe pain in his foot was referred some years after internal fixation of a talar body fracture. He has severe pain and dysfunction. The lateral radiograph shows no evidence of significant osteoporosis, which is inconsistent with the diagnosis. The talar body fracture is not reduced which renders the ankle and sub-talar joints incongruous. Furthermore the screws are overlong and impinge on the ankle joint. This patient does not have CRPS; he has a mechanical cause for his severe pain, which was resolved by talar osteotomy, anatomic reduction, and refixation. It is important to exclude mechanical causes for pain before invoking the diagnosis of CRPS.
This patient with severe pain in his foot was referred some years after internal fixation of a talar body fracture. He has severe pain and dysfunction. The lateral radiograph shows no evidence of significant osteoporosis, which is inconsistent with the diagnosis. The talar body fracture is not reduced which renders the ankle and sub-talar joints incongruous. Furthermore the screws are overlong and impinge on the ankle joint. This patient does not have CRPS; he has a mechanical cause for his severe pain, which was resolved by talar osteotomy, anatomic reduction, and refixation. It is important to exclude mechanical causes for pain before invoking the diagnosis of CRPS.
View Original | Slide (.ppt)
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Management

A bewildering array of treatments have been proposed, but proper, scientifically constructed, prospectively randomized blinded studies are few,106 and uncontrolled investigations are particularly unreliable in CRPS because of the variety of symptoms and the trend toward self-resolution in the majority of cases. This is well illustrated by a series of publications investigating the treatment of early CRPS after Colles fracture with intravenous regional guanethidine blockade (IVRGB). An initial investigation showed that IVRGB caused improvement in objective criteria of CRPS severity.59 A subsequent pilot study appeared to confirm that the immediate improvement induced by IVRGB was associated with sustained symptomatic improvement.57 However, a full prospectively randomized double-blind controlled study demonstrated that IVRGB actually seemed to worsen the condition.119 The lesson is that these potentially fragile patients must be approached with caution. 
This chapter has presented evidence that CRPS is very common in orthopedic trauma practice. Most sufferers are sensible people, concerned at the development of inexplicable pain, but the occasional “Sudecky” patient fares poorly and should be treated vigorously. Early treatment, begun before contractures occur, gives optimal results, so a high index of clinical suspicion must be maintained. It is not reprehensible to have caused a case of CRPS through surgery or nonoperative management of injury. However, delay in diagnosis and treatment may contribute to a poor outcome. 
Modern CRPS treatment emphasizes functional rehabilitation of the limb to break the vicious cycle of disuse,91,92,165 rather than SNS manipulation.29 Initial treatment from the orthopedic surgeon is by reassurance, excellent analgesia, and intensive, careful physical therapy avoiding exacerbation of pain.73 Nonsteroidal anti-inflammatory drugs may give better pain relief than opiates, and a centrally acting analgesic such as amitriptyline is often useful even at this early stage. Immobilization and splintage should generally be avoided, but if used, joints must be placed in a safe position, and splintage is a temporary adjunct to mobilization. It seems sensible to give the patients vitamin C in view of the early evidence of its efficacy.196,197 
Abnormalities of pain sensation will often respond to desensitization. The patient is asked to stroke the area of allodynia, where stroking is painful. They are reminded that simple stroking cannot by definition be painful, and they are instructed to stroke the affected part repetitively while looking at it and repeatedly saying “this does not hurt, it is merely a gentle touch.” The earlier this is begun, the more effective it is. A similar attitude can be taken with early loss of joint mobility due to perceived pain rather than contracture. 
The use of mirror virtual therapy is an exciting new concept which is as yet unproven in an orthopedic context.133,152 
If the patient does not respond rapidly, a pain specialist should be involved and treatment continued on a shared basis. Psychological or psychiatric input may be important.28 Second-line treatment is often unsuccessful, and many patients are left with pain and disability. Further treatments include centrally acting analgesic medications such as amitriptyline, gabapentin, or carbamazepine; regional anesthesia; calcitonin; the use of membrane-stabilizing drugs such as mexiletine; sympathetic blockade and manipulation; desensitization of peripheral nerve receptors with capsaicin; transcutaneous nerve stimulation; or an implanted dorsal column stimulator.123,142,167 Behavioral therapy may be necessary in children.191193 Where the knee is affected, epidural anesthesia and continuous passive motion may be appropriate.38,39 
It is important to ensure that a patient with CRPS within an orthopedic context under the management of a pain clinic is reviewed by an orthopedic surgeon with an interest in CRPS to ensure that there is no treatable orthopedic condition which better explains the symptoms (Tables 25-2, 25-3, 25-578). 
The role of surgery is limited and hazardous. These patients are very fragile and difficult. They respond abnormally to pain, and because of sensory and motor neglect, they rehabilitate poorly. Where the cause of CRPS is a surgically correctable nerve lesion, treatment should be cautiously directed at curing the nerve lesion. Occult nerve compression should be sought and dealt with. For example, decompression of a median nerve at the wrist which is causing CRPS of the hand may abort the CRPS and should be undertaken cautiously in the presence of active disease. 
Surgery is rarely indicated to treat fixed contractures which usually involve all of the soft tissues. Surgical release must therefore be radical and expectations limited. Surgery for contracture should be delayed until the active phase of CRPS has completely passed, and ideally there should be a gap of at least a year since the patient last experienced pain and swelling. 
Amputation of a limb affected by severe CRPS should be approached with great caution. Dielissen et al.47 reported a series of 28 patients who underwent 34 amputations in 31 limbs. Surgery was usually performed for recurrent infection or to improve residual function. Pain relief was rare and unpredictable, and neither was infection always cured nor function universally improved. CRPS often recurred in the stump, especially if the amputation level was symptomatic at the time of surgery. For this reason only two patients wore a prosthesis. 
Generally, surgery represents a painful stimulus which may exacerbate CRPS or precipitate a new attack. This risk must be balanced carefully against the proposed benefit. The risk of surgically precipitated recurrence is greatest when the same site is operated upon in a patient with abnormal psychology in the presence of active disease and lowest when these conditions do not apply. Surgery must be performed carefully with minimal trauma with excellent and complete postoperative analgesia. The surgery may be covered by gabapentin. Ideally the anesthetist will have a particular interest in the treatment of CRPS. 

Conclusion

This chapter has presented the proposal that CRPS in a mild form, which is often not formally diagnosed, is very common but not universal in an orthopedic trauma practice. Although the majority of cases will resolve with simple management, CRPS is responsible for significant acute disability and may cause long-term problems. 

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