Complex Regional Pain Syndrome
described a syndrome that occurred in patients who had suffered gunshot
injuries to major nerves.120 Noting that a leading feature was burning pain, he called the condition causalgia.
At the beginning of the 20th century, Paul Südeck, a clinician in
Hamburg, Germany, used the newly invented technique of roentgenology to
investigate patients with severe pain after injury.145,146
He described a posttraumatic 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.121 In an intriguing vignette, Channon and Lloyd32
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 as CRPS.
sudomotor dysfunction, contracture, and osteoporosis. It 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 review will specifically examine CRPS within the
context of orthopaedic 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.
perception, which are mainly foreign to orthopaedic surgeons. They have
been codified by Merskey and Bogduk119 and because they will be used throughout this text, they are described here.
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Allodynia
(literally “other pain”) is a painful perception of a stimulus that
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 further subdivided into static mechanical allodynia, implying pain in response to light touch or pressure, and dynamic mechanical allodynia, where the pain occurs as a result of brushing.107
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In thermal (hot or cold) allodynia, the pain is caused by mild changes in skin temperature in the affected area.
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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.
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Secondary hyperalgesia describes pain sensitivity that occurs in surrounding undamaged tissues.
Rarely, hyperalgesia is seen in a more diffuse, bodywide form. -
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Hyperpathia
is a temporal and spatial summation of an allodynic or hyperalgesic
response. Thus, 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 period (up to 30 minutes) after the stimulus has been withdrawn.
In severe cases, the pain may be accentuated by unusual and extraneous
things such as the sudden noise of a door shutting or a draft of cold
air.
that these patients are not malingering or mad. These are absolutely
real perceptions of pain.
much confusion that 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 23-1) reflecting site affected, cause and clinical features. During the American Civil War, Mitchell et al.120 noted the burning nature of pain following nerve trauma and described this as causalgia (from the Greek “burning pain”). In contrast, in the 1900s, Südeck145,146 investigated conditions characterized by severe osteoporosis, including some cases of CRPS. The condition was named Südeck’s atrophy by Nonne in 1901.123 Leriche99,100 demonstrated that sympathectomy could alter the clinical features associated with posttraumatic osteoporosis, and De Takats38 first suggested reflex dystrophy in 1937. Evans46 introduced the term reflex sympathetic dystrophy,
based on the theory (following Leriche’s observations) that sympathetic
hyperactivity was involved in the pathophysiology, and this term was
popularized by Bonica.18 In 1940, Homans85 proposed minor causalgia to imply a relationship between Mitchell et al.’s causalgia, renamed major causalgia, and similar conditions arising without direct nerve injury. Causalgic state37 and mimo causalgia126 followed to add to the confusion. Today the term causalgia is reserved for Mitchell et al.’s original use, in which a major nerve injury produces burning pain.141
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TABLE 23-1 Synonyms for Complex Regional Pain Syndrome
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consists of pain, hyperpathia, and allodynia, which are relieved by
selective sympathetic blockade. The relationship between CRPS and
sympathetically maintained pain is disputed.141
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 that leads to initial tissue edema
followed by severe contracture. This is not an inevitable part of
sympathetically maintained pain.91
Sympathetically maintained pain is not a particularly helpful concept
for the orthopaedic surgeon; however, it will be explored further when
the etiology of CRPS is considered.
interest. The International Association for the Study of Pain (IASP)
has undertaken a major work in analyzing the features of CRPS and
reclassifying the condition.119 A
brief history of this work will help to understand the current
position. The name of the condition was changed to complex regional
pain syndrome (CRPS) at a consensus workshop in Orlando, Florida, in
1994,16,141 and a new set of standardized diagnostic criteria was established119 (Table 23-2). To complement the diagnostic criteria, a broad description of CRPS was offered later22,80:
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.
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TABLE
23-2 The Original International Association for the Study of Pain Diagnostic Criteria for Complex Regional Pain Syndrome (CRPS) |
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the cause was believed to be damage to a major nerve, and CRPS type 1,
where it was not.
must be clinical and therefore precise descriptions of symptoms and
signs acquire great importance. Classic descriptions of the condition
describe three stages occurring sequentially.17,38,44,68,137,138 Modern evidence, however, suggests that CRPS does not invariably pass through these stages13,157,173,174
and supports the clinical impression that this evolution is seen in
more severe cases (as might be expected from historic series).
Nevertheless, the classic descriptions provide the greatest information
concerning the clinical features, and the description that follows
draws on these and will therefore refer to the staging system where it
is helpful to the description.
through the three classic stages, it is essential to grasp the concept
that CRPS is a biphasic condition with early swelling and vasomotor
instability giving way over a variable timescale to late contracture
and joint stiffness.44 The hand and foot are most frequently involved, although involvement of the knee is increasingly recognized.35,36,93 The elbow is rarely affected, whereas shoulder disease is common and some cases of frozen shoulder are probably CRPS.143 The hip is affected in transient osteoporosis of pregnancy.
precipitating trauma, although the delay may be greater. Antecedent
trauma is not essential but within an orthopaedic context it is almost
invariable.44 As the direct effects of injury subside, a new diffuse, unpleasant, neuropathic pain arises.168
Neuropathic pain is pain that occurs without any precipitating noxious
stimulus, and spontaneous or burning pain, hyperalgesia, allodynia, and
hyperpathia are common but not universal features.119
Pain is unremitting (although sleep is often unaffected), worsening and
radiating with time. The pain may be increased by dependency of the
limb, physical contact, emotional upset, or even by extraneous factors
such as a sudden loud noise or a blast of cold air.
Vasomotor instability (VMI) and edema dominate the early phase (Fig. 23-1),
although this is less marked with more proximal CRPS. The classic
description of the temporal evolution of the condition divides the
early phase of CRPS into two stages depending on the type of the
vasomotor instability.44 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, this classic
evolution is rarely seen. Most commonly, especially in more mild cases,
the vasomotor instability is 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.13,21,157,175
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FIGURE 23-1
A patient with early complex regional pain syndrome type 1 affecting the leg. Note the swelling of the leg and the discoloration of the shin. |
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, however
(in the classic description, passing from stage 1 to stage 2), the
edema becomes more fixed and indurated with coalescence of tissue
planes and structures.
mobility is caused by swelling and pain combined with an apparent
inability to initiate movement or state of neglect or denial with
respect to the limb.27,28,29,61,62 Weakness, dystonia, spasms, tremor, and myoclonus have also been reported15,56,106,137;
however, these are not usually prominent within an orthopaedic context.
As the early phase progresses, loss of joint mobility will increasingly
be the result of the development of contracture. Only if the disease
can be halted in the early phase before fixed contracture has occurred
can complete resolution occur.