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Although this syndrome occurs in both the upper and lower extremities, it is of interest that the success of pharmacologic and other treatment modalities differs between the upper and lo

Trang 1

The normal physiologic response of

an extremity to a painful injury

in-volves humoral and neural signals

that give rise to increased blood

flow, edema, limited joint excursion,

and hypersensitivity to pain These

signs and symptoms are usually

proportional to the severity of the

injury and resolve with healing of

the damaged tissues When this

injury response is prolonged, a

chronic pain syndrome results

With time, painful symptoms may

expand from the site of injury to

involve the entire extremity, leading

to a persistently swollen, painful,

and ultimately functionless limb

This progressive pain pattern

has been recognized for over 100

years and has been described

vari-ously as causalgia, minor causalgia,

major causalgia, mimocausalgia,

pseudocausalgia, reflex sympathetic

dystrophy, algodystrophy,

algo-neurodystrophy, posttraumatic dystrophy, Sudeck’s atrophy, and sympathetically maintained pain syndrome To minimize the confu-sion in terminology, the Interna-tional Association for the Study of Pain coined the term complex re-gional pain syndrome (CRPS) to describe this constellation of symp-toms Within this diagnosis are two subtypes, which differ only by the presence of a definable peripheral nerve injury in type II

CRPS involving the lower ex-tremity presents a diagnostic and therapeutic challenge to the ortho-paedic surgeon Often discomfort is severe and patients are unable to gain relief Although this syndrome occurs in both the upper and lower extremities, it is of interest that the success of pharmacologic and other treatment modalities differs between the upper and lower extremities.1-5

Frequently, the symptoms in the lower extremity are more refractory

to intervention than those in the upper extremity.6 This differential response has led some to suggest that CRPS of the legs and feet is a discrete clinical entity.1,7-10 Narcotic pain medications are of little restorative value and, if used, fre-quently result in drug dependence without improving limb function Complicating management are social issues, such as liability or worker’s compensation or disability, that may provide a financial disincentive for patients to report improvement Often there is overlying psychologi-cal dysfunction, as well Because of the many physiologic and psycho-logical factors involved in pain, a multidisciplinary approach should

be developed for each patient, in-tegrating the efforts of the ortho-paedic surgeon, anesthesiologist, physiatrist, physical therapist, occu-pational therapist, and psychiatrist

Dr Hogan is Orthopaedic Surgeon, United States Navy, Norfolk, VA Dr Hurwitz is S Ward Casscells Professor, Department of Orthopaedic Surgery, University of Virginia Health Sciences Center, Charlottesville, VA Reprint requests: Dr Hurwitz, University of Virginia Health Sciences Center, Department

of Orthopaedics, PO Box 800159, Charlottes-ville, VA 22908.

Copyright 2002 by the American Academy of Orthopaedic Surgeons.

Abstract

Complex regional pain syndrome, formerly known as reflex sympathetic

dystro-phy or causalgia, is a difficult therapeutic problem for the orthopaedic surgeon

treating an affected lower extremity Despite many divergent and often

con-flicting theories, the cause of the severe pain, alterations in regional blood flow,

and edema is unknown Interventions that have proved successful for treating

similar conditions in the arm and hand frequently do not relieve pain similarly

in the lower extremity Common treatment regimens target individual

compo-nents of this symptom complex, namely, sympathetic or afferent nerve

hyperac-tivity, vasomotor instability, or regional osteoporosis Despite widespread use

of some of these treatments, few controlled clinical trials quantify their

effective-ness This challenging syndrome is best managed by a multidisciplinary team,

including chronic pain management specialists, physical therapists, and

orthopaedic surgeons.

J Am Acad Orthop Surg 2002;10:281-289

of the Lower Extremity

Christopher J Hogan, MD, and Shepard R Hurwitz, MD

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The pathophysiology of CRPS

re-mains unknown, and little clinical

evidence explains why certain

treat-ment protocols appear to be

suc-cessful Divergent theories abound,

likely because the spectrum of

pre-sentations of this syndrome is so

diverse This suggests that responses

to treatment vary because

heteroge-neous conditions are being treated

The older term reflex sympathetic

dystrophy describes a pathologic

reflex of the sympathetic nerves that

causes blood flow irregularities,

resulting in constant pain, muscle

atrophy, and fibrosis The

propo-nents of this etiology cited the pain

relief from sympathetic block as

supportive evidence They also

ad-vocated the use of calcium channel

blockers to counteract the

vasocon-striction of increased

sympathetic-adrenergic activity Sympathetic

block, however, did not prove to be

a reliable predictor of treatment

re-sponse and for this reason, the term

reflex sympathetic dystrophy was

discarded.11,12

Several other theories were

offered based on response of

periph-eral or systemic antagonism to α- or

β-adrenergic agonists.1,5,13-16 The theories of injury-induced hypersen-sitivity to circulating catecholamines are based on many reports of posi-tive clinical response to pharmaco-logic block using phentolamine, phenoxybenzamine, or propranolol

A subset of the catecholamine hypersensitivity theories suggested that the site of the pathologic recep-tors is in the skin rather than in the small vessels

Local inflammatory factors were the rationale for the use of high-dose corticosteroids.17,18 This seemed a logical explanation for the swelling and pain in an area that was physi-cally traumatized The advocates of this theory suggested that the pain-ful inflammation, in turn, disrupted local autoregulation of blood flow, and thus explained the classic phases

of reflex sympathetic dystrophy

A group of regional pain syn-dromes is associated with known nerve injury, previously referred to

as causalgia The concept of a pain-ful local nerve injury establishing constant pain through a central mechanism in the spinal cord or spinothalamic network was an

explanation that did not involve cate-cholamines or the sympathetic nerves A variation on the centrally mediated pain mechanism was the proposal that peripheral nerve in-juries created aberrant neuronal connections between peripheral sensory and sympathetic nerves To support their theory, advocates of neural injuries cited success with membrane-stabilizing medications, such as bretylium, gabapentin, and calcium channel blockers.3,10,19-22

Diagnosis and Clinical Course

The diagnosis of CRPS is based on physical examination findings be-cause no laboratory or radiologic tests can reliably confirm or exclude the diagnosis Traditionally, the clinical course of CRPS has been divided into three stages that de-scribe the physical characteristics of the syndrome (Table 1) In the hand, these stages are relevant to the effectiveness of intervention, with earlier intervention more likely

to result in successful outcomes Whether early intervention

im-Table 1

Stages of Complex Regional Pain Syndrome

Usual Time Stage Course (mo) Clinical Features Radiographic Findings

Acute 0 to 3 Warm, red, edematous extremity; Normal plain radiographs; may

aching, burning pain; intolerance have abnormal uptake of imaging

to cold; altered sweat pattern; agent on bone scan joint stiffness without any significant

effusion; hyperesthetic skin; no fixed joint contractures

Dystrophic 3 to 6 Cool, cyanotic, edematous extremity; Subchondral osteopenia; patellar and

shiny, hyperesthetic skin; fixed medial femoral condyle osteopenia contractures; fibrotic changes occur on sunrise view; may have abnormal

in the synovium uptake of imaging agent on bone scan Atrophic 6 to 12 Loss of hair, nails, skin folds; Bone demineralization

fixed contractures; muscle wasting

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proves the prognosis in CRPS of the

lower extremity, however, is

disput-ed.1,7-10

In the acute stage (within 3

months after the injury), patients

report a burning or aching pain that

generally does not respond to

nar-cotics and is considerably more

in-tense than expected for the degree

of injury Symptoms typically begin

soon after the injury—within hours

or days—but may develop more

in-sidiously over several weeks One

of the first clinical signs is an extreme

intolerance to cold, and patients

often state that motion, dependency

of the limb, and touch aggravate

their symptoms The skin is usually

warm and hyperemic and frequently

demonstrates an altered pattern of

perspiration that ranges from dry to

increased sweating Early in its

course, the pain may follow the

dis-tribution of a cutaneous nerve, but

with time this may progress to

involve the entire extremity Mild

edema around the joints is common,

but true joint effusions are rare (Fig

1) Although patients report a

sensa-tion of joint stiffness, examinasensa-tion

under anesthesia usually reveals a full range of motion

Plain radiographs help determine whether other definable lesions, such

as stress fractures, are responsible for the symptoms, but for CRPS in the acute phase, there are neither radio-graphic changes nor evidence of osteoporosis Technetium 99m bone scans are commonly used to attempt

to confirm the diagnosis of CRPS, but they have a specificity of 75% to 98% and a sensitivity of only 50% for this condition.11 The most common finding is increased periarticular uptake of the imaging agent in each phase, although decreased flow has been reported in the acute setting.2,23

As a result, bone scan findings are generally reported as “abnormal”

compared with those for the unaf-fected contralateral extremity

In the dystrophic stage, which begins approximately 3 months after the initial injury, pain is con-stant and aggravated by any stimu-lus If the ankle is involved, a fixed equinovarus deformity of the hind-foot may develop, with firm indura-tion around the tibiotalar joint.11

The skin is frequently cool to the touch, cyanotic, and shiny, and hair may be scant Radiographs of the involved extremity may reveal patchy subchondral osteopenia from both the disuse and the hyper-emia of the acute stage (Fig 2), although this finding may be absent

in up to 20% of patients who meet the diagnostic criteria for CRPS.11 If the knee is involved, osteopenia of the patella and medial femoral condyle on the sunrise view charac-teristically is present.7,24-26 Bone scan imaging at this time frequently demonstrates altered uptake of the imaging agent in the affected limb, particularly in the periarticular region.27 Synovial biopsies demon-strate increased fibrosis and synovial proliferation without any evidence

of inflammatory changes.25 This degree of fibrosis increases with the duration of symptoms

The atrophic stage begins about 6 months to 1 year after the onset of symptoms, when the skin and per-fusion changes become fixed, lead-ing to the clinical appearance of cyanotic, shiny, pale skin, with loss

Figure 1 Left foot of a woman with CRPS

after sustaining what she described as a

“slight sprain” of the ankle.

Figure 2 Anteroposterior (A) and lateral (B)

radio-graphs of the right foot of a middle-aged woman 3 months after open reduction and fixation for a talar neck fracture She had pain in the entire foot and stiffness of the ankle and all joints She could not tol-erate bearing weight or wearing shoes The amount

of osteopenia is beyond that expected from disuse, a finding typical of the dystrophic stage.

A

B

Trang 4

of the usual skin folds The joint

motion is severely restricted, and

fixed contractures are common

Sig-nificant muscle wasting is apparent

on inspection, and there is

radio-graphic evidence of profound bone

demineralization

Treatment

No current consensus exists

regard-ing the most effective treatment

regi-men for CRPS of the lower extremity

Several studies report treatment

re-sults with the modalities used in

upper extremity cases However,

these studies had either small

num-bers of patients or limited clinical

follow-up.11-13,28 In addition, the

heterogeneity of the patient

popula-tions precludes a single algorithm to

guide treatment Clinical trials for

CRPS of the lower extremity are

list-ed in Table 2

The use of intravenous regional

sympathetic blocks was first

popu-larized by Hannington-Kiff in 1974, who suggested that guanethidine might relieve pain for patients with CRPS The goal of this therapy is to reduce the sympathetic input to the limb, based on the theory that chronic pain results from either a central hyperactivity of the sympa-thetic nervous system33or a periph-eral hypersensitivity to circulating catecholamines.34,35 To achieve a block, the affected extremity is exsanguinated and placed under tourniquet control, and a sympa-tholytic agent is infused into a vein

The medication suffuses the tissues via the venous pathways while the tourniquet prevents the circulation

of the medication into the systemic vasculature The drugs that have been used in intravenous regional blocks are guanethidine, reserpine, and bretylium, all of which inhibit release of norepinephrine by dis-placing it from neuronal storage vesicles In the United States, intra-venous preparations of

guanethi-dine and reserpine are no longer available, leaving bretylium as the only option

The efficacy of intravenous re-gional sympathetic blocks in the treatment of CRPS is unclear because separate studies dealing with very similar patient populations report contradictory levels of response to treatment Some studies showed no difference between guanethidine, reserpine, and saline control,5,36,37 whereas some demonstrated pain relief in about half of the lower ex-tremity patients,33,38and others, improvement in approximately 75%

of patients.29 None of these studies mentioned the duration of benefit Similarly, the efficacy of bretylium for intravenous regional sympathetic blocks is uncertain Although bre-tylium has been reported to be an effective treatment for CRPS, the largest published series does not discriminate between upper and lower extremity involvement.39 Of two studies that used bretylium,

Table 2

Clinical Trials for Treatment of Complex Regional Pain Syndrome of the Lower Extremity

No of Patients With Lower Duration of Study Drug Extremity Symptoms Results Relief

Intravenous

regional block

Eulry et al29 Guanethidine 87 Improvement, 64 Not given

Lumbar

sympathetic block

O’Brien et al8 Bupivacaine 60 Good, 34; fair, 21 Not given

Wang et al1 Bupivacaine 43 Initial improvement, 30 Not given

Cooper et al30 Epidural bupivacaine 14 Complete resolution, 11 7 to 48 mo

and narcotic

Oral agents

Cortet et al31 Pamidronate 17 Improvement/resolution in all >90 days

Devogelaer et al32 Pamidronate 15 Improvement/resolution in all Not given

Ghostine et al14 Phenoxybenzamine 17 Improvement/resolution in all No recurrences in 6 mo

to 6 yr follow-up

Intravenous agents

Poplawski et al6 Lidocaine and 8 Excellent results, 4 Not given

methylprednisolone Poor results, 4

Trang 5

comprising a total of five cases, one

claimed total resolution of

symp-toms3 and the other, no benefit.19

Such conflicting reports of treatment

response are difficult to reconcile,

especially with the small number of

patients included

Several authors have used

lum-bar sympathetic blocks with either

lidocaine or bupivacaine to manage

CRPS of the knee.1,8,10,40 This

tech-nique involves introducing a needle

into the region of the paravertebral

lumbar sympathetic ganglia under

either fluoroscopic or computed

to-mographic guidance and infiltrating

the area with the local anesthetic

As an essential criterion for the

diagnosis of CRPS, three of these

protocols required that patients

demonstrate pain relief following

the administration of phentolamine,

a criterion that may favorably bias

the patient population toward this

therapy Although 93 of 112 total

patients had some degree of pain

relief, most had residual symptoms

In one series, only 12% of patients

were pain free at 3 years’

follow-up,1 whereas in another, only 57%

of patients had a good response,

al-though there was no mention of the

duration of pain relief.8 With

lum-bar sympathetic block, in contrast to

most other types of treatments,

there appears to be no correlation

between the duration of symptoms

and the response to treatment.1,8,10,40

Use of either continuous epidural

anesthesia or an intrathecal narcotic

pump allows either low-dose

nar-cotics or local anesthetics to be

ad-ministered locally, resulting in fewer

systemic side effects than are seen

with intravenous administration

When delivered locally, narcotics can

help break the pain cycle, whereas

the anesthetic agents provide a

rela-tively selective sympathetic

block-ade The narrow diameter of the

unmyelinated sympathetic fibers

allows for a block of these nerves

with minimal inhibition of the motor

or sensory fibers

Two published series report suc-cessful treatment with this interven-tion, either through placement of an indwelling morphine pump41or ad-ministration of continuous epidural anesthesia in conjunction with con-tinuous passive motion.30 Despite this success, the risks and costs of these treatments are considerable

Continuous epidural anesthesia requires hospitalization for the duration of treatment and carries the risks of urinary retention, skin breakdown, and hypotension Intra-thecal morphine pumps are rela-tively expensive and require periodic refilling of the narcotic reservoir

The use of α-adrenergic blocking agents is based on addressing the altered blood flow demonstrated in patients with CRPS, which is theo-rized to result from increased local secretion of norepinephrine and vas-cular endothelial hypersensitivity to this neurotransmitter Normally, peripheral blood flow is determined largely by sympathetic activity at the α1-adrenergic receptors, with increased stimulation leading to vasoconstriction Inhibition of the receptors leads to dilation of the arterioles and increased blood flow

Phentolamine is an α1-adrenergic sympathetic blocking agent with a very short duration of action Pain relief following intravenous admin-istration has been proposed as a diagnostic test for CRPS as well as a prognostic guide for favorable re-sponse to sympathetic block.15,42 The 15-minute plasma half-life of this medication, however, precludes its use as a therapeutic intervention

Phenoxybenzamine and prazosin have been used successfully in patients with lower extremity CRPS, although none of these reports states whether patients required long-term treatment.14,43,44 In contrast, another

α-adrenergic antagonist, droperidol, had no clinical benefit.45

Intravenous or oral clonidine or the combination is commonly used

as an intervention, likely on a

theo-retical basis because no published series documents its efficacy One small series demonstrated temporary relief with topical use.42

There is some clinical evidence that an oral beta blocker may im-prove symptoms Although the most dramatic property of propran-olol is its peripheral beta blockade, this drug also demonstrates central nervous system activity via antago-nism of serotonin A total of five patients with acute CRPS treated with oral propranolol has been re-ported Three of the patients were free of symptoms at their last

follow-up,16,46 and two demonstrated no change in their symptoms.47 Pain relief occurred several weeks after beginning treatment in those who had relief We found no reports of the use of intravenous beta blocker therapy or the use of any other beta blocker

Oral calcium channel blockers oppose the vasoconstriction medi-ated by the sympathetic nervous system by causing smooth-muscle relaxation in arteriole walls, leading

to increased peripheral blood flow These drugs have been used success-fully in vasospastic conditions, such

as Reynaud’s disease The largest reported clinical series of CRPS pa-tients treated with oral calcium chan-nel blockers did not distinguish between the results of treating upper and lower extremity symptoms, although a high degree of pain relief was reported.43 Prough et al20 re-ported success in three patients with lower extremity CRPS with this intervention, but two required main-tenance doses of nifedipine to pre-vent a recurrence of symptoms Reports of the efficacy of the se-lective serotonin blocker ketanserin

in treating CRPS mostly have not differentiated between upper or lower extremity involvement This use is based on the fact that sero-tonin demonstrates significant vaso-constrictive properties, and low concentrations of this

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neurotrans-mitter applied topically have been

shown to cause pain Bounameaux

et al48 stated that, although oral

ketanserin effectively increased

blood flow to the involved leg in the

majority of patients, none of the

eight patients with lower extremity

involvement reported any lasting

pain relief From this finding, the

authors concluded that decreased

peripheral blood flow might not be

the crucial factor in some patients

with CRPS

Treatment with bisphosphonates

is based on the concept that pain

results from the osteopenia created

by blood flow derangements and

chronic disuse Adami et al49reported

that alendronate was effective in

treating patients with long-standing

CRPS, but their results did not

dis-tinguish between upper and lower

extremity involvement Rehman et

al50showed that these patients have

lower than normal bone density and

that this relative osteoporosis

im-proves with the use of pamidronate

The time to improvement in bone

density in this study parallelled the

time to improvement of symptoms

seen by Cortet et al31and Devogelaer

et al.32 These studies, comprising a

total of 32 patients symptomatic for

at least 6 months, reported

improve-ment in symptoms in all cases but

did not mention the duration of pain

relief or whether patients required

chronic therapy

The rationale for the clinical use

of anticonvulsants in patients with

CRPS is that injured neurons have

abnormal sensitivity and may send

impulses spontaneously that lead to

the perception of pain Although

review articles have reported

treat-ment of lower extremity CRPS with

carbamazepine, clonazepam,

val-proic acid, and phenytoin,11,12we

have uncovered no clinical studies

substantiating the effectiveness of

these drugs

The only anticonvulsant studied

clinically and reported in the

litera-ture to date is gabapentin, which

acts both peripherally and centrally

to depress the excitatory pathways and stimulate the inhibitory path-ways This drug increases central nervous system levels of serotonin, which is an inhibitory neurotrans-mitter Mellick and Mellick21 reported that gabapentin relieved pain in a series of six patients with CRPS, two of whom had symptoms

in the lower extremity for 3 years

They did not mention the duration

of pain relief or whether these patients required chronic treatment with the medication

Antiarrhythmic medications also have been used to suppress the spon-taneous discharge of injured neu-rons and depress C fiber–mediated reflexes at the level of the spinal cord The efficacy of bretylium, a class III antiarrhythmic, has been discussed Mexiletine is an oral agent similar in action to lidocaine, which was used by Chabal et al22to treat three patients with chronic type

II CRPS of the lower extremity

They found improvement in two of three patients but did not mention the duration of benefit or whether the patients required long-term treatment

Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit the enzyme cyclooxygenase This inhibition leads to a decreased production of prostaglandins and thromboxanes, substances that increase the sensitiv-ity of nociceptors to painful stimuli and promote vascular constriction

Despite the widespread use of this class of medications, no published trials report the use of oral NSAIDs

to treat CRPS The benefits of intra-venous ketorolac were reported in a single small series.17 All three pa-tients with lower extremity symp-toms demonstrated temporary pain relief, which increased in duration with serial doses The average dura-tion of benefit was 15 days, allowing most patients to begin edema con-trol measures and attempt to regain joint motion

The potent anti-inflammatory effects of corticosteroids make these drugs an attractive option for treatment of CRPS because, theoretically, decreased tissue edema will lessen pain and im-prove joint motion Use of pred-nisone, prednisolone, or methyl-prednisolone is commonly cited in the treatment of lower extremity CRPS,11,13,28 but most studies sup-porting their use combine the re-sults of patients with upper and lower extremity involvement or in-clude only those with upper ex-tremity symptoms.18

Poplawski et al,6 however, re-ported on a series of 27 patients with CRPS, 8 of whom had lower extremity involvement Using intra-venous regional lidocaine and meth-ylprednisolone, they found that 60% of patients with upper extrem-ity involvement had a good or ex-cellent result compared with 50%

of those with lower extremity symptoms No definitive studies support the benefit of oral cortico-steroids in the treatment of lower extremity CRPS

Gentle physical therapy both to control edema and prevent joint contracture is beneficial in all stages

of CRPS Activity is thought to improve function, but it has little proven effect on pain There is no compelling evidence that any exer-cise or activity is curative Overly ag-gressive therapy should be avoided because this can exacerbate the patient’s sense of loss of control in the treatment process Although the use of transcutaneous electrical nerve stimulation (TENS) units is widespread, their usefulness has been demonstrated only in a small series in the pediatric literature,51 and there is no published report of the efficacy of this intervention in adults In a small study, other modalities, such as daily ultrasound treatments, have been shown to be beneficial in treatment of CRPS of the foot.40

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Treatment Overview

Several conclusions can be drawn

about CRPS of the lower extremity

There are no defined risk factors for

developing CRPS, and this

syn-drome has been described after both

major and incidental trauma to the

lower extremity The pain and

edema generally do not resolve

without treatment, and patients

fre-quently have residual symptoms,

despite prompt intervention.1 The

treating orthopaedic surgeon who

suspects CRPS should keep in mind

that these patients may have other

mechanical derangements

contribut-ing to their pain, such as a stress

fracture or degenerative arthritis A

careful, detailed history and

physi-cal examination should be done in

every case to eliminate the

possibili-ty of concomitant pathology

Intra-articular pathology requiring

surgi-cal intervention should be addressed

after the symptoms of CRPS have

subsided; even in this setting, CRPS

recurs after surgery in up to 47% of

patients.7,8,30 Because of this high

reported risk of recurrence,

explor-atory surgery should be avoided

Radiographs and nuclear bone scans

are helpful in confirming the

diag-nosis but may be falsely negative

early in the course of the syndrome

Magnetic resonance imaging has no

proven diagnostic value

When the patient has no

appar-ent mechanical derangemappar-ent,

ancil-lary services should be recruited

within 4 weeks to 3 months to break

the pain-impairment cycle of CRPS

A multidisciplinary approach, using

physical therapy and pain control

measures, is preferred to a single

physician dispensing treatment

Physical therapy is useful in all

stages, but forced motion should be

avoided because patients’ sense of

losing control can be exacerbated by

overly aggressive manipulation

Edema control can most effectively

be accomplished with compression,

gentle motion, and distal-to-proximal

massage Ice or ultrasound may be helpful, but often patients do not tolerate extremes of heat and cold well, limiting the usefulness of these modalities Progressive tactile desensitization may provide a use-ful adjunct, although this is less important than in patients with upper extremity CRPS because ambulation commonly provides adequate stimulation

Many different medications have been used in the treatment of CRPS

of the lower extremity, with varying degrees of success Narcotic pain medications should come from one physician to minimize the risk of drug dependence and drug interac-tions Orthopaedic surgeons do not commonly prescribe these medica-tions and therefore should consult early with a specialized pain clinic

Patients should be referred to pain clinic services within 3 months of the diagnosis of CRPS Gabapentin, prazosin, propranolol, nifedipine, and mexiletine all have been used in successful treatment protocols, but studies with these drugs involved fewer than five patients with lower extremity symptoms, making it dif-ficult to draw conclusions regarding the efficacy of each intervention

The greatest clinical experience is with the use of intravenous regional administration of sympatholytic agents, NSAIDs, or corticosteroids

Considered as one large group, pa-tients treated with guanethidine, reserpine, or bretylium responded similarly to those treated with ketorolac, prednisolone, or methyl-prednisolone, with approximately half reporting relief This suggests that other mechanisms may con-tribute to the clinical response

Some of the controversy surround-ing intravenous regional techniques comes from studies suggesting that the pain relief results, not from the infusion of a sympatholytic agent, but from the tourniquet-induced ische-mia Rocco et al5and Blanchard et

al36demonstrated no difference in

results between guanethidine, reser-pine, and normal saline infusion administered to patients with lower extremity CRPS, a finding supported

by Jadad et al,37who demonstrated

no difference between guanethidine and saline infusions These authors suggest that tourniquet-induced ischemia may provide enough pain relief to allow for increased physical therapy, but no studies have tested this hypothesis

More encouraging results were seen after paravertebral sympathetic blocks and after treatment with con-tinuous epidural anesthesia All of the studies of these two interven-tions used response to phentolamine

as a diagnostic criterion for CRPS, a factor that may select for a better response to treatment with anti–α -adrenergic agents

Pamidronate, a bisphosphonate, has demonstrated encouraging re-sults in the treatment of CRPS of the lower extremity Although it is difficult to ascribe all of the clinical features of CRPS to osteopenia, this medication reportedly led to im-provement or resolution of symp-toms in all patients in the study populations

Summary

CRPS of the lower extremity poses a management challenge The etiology

is unclear, and theories to explain the condition, as well as proposed therapies, abound Therapies that may be effective for upper extremity CRPS are often not as effective for lower extremity CRPS, leading some to conclude that it is a differ-ent differ-entity

No laboratory or radiologic tests can reliably confirm the diagnosis

In the acute stage, burning or aching pain that cannot be controlled by narcotics is the major feature In the dystrophic stage, beginning approx-imately 3 months after injury, bone scans often demonstrate altered

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up-take of the imaging agent in the

affected limb In the atrophic stage,

6 months to 1 year after injury, fixed

contractures, significant muscle

wasting, and profound bone

de-mineralization are common

The greatest clinical experience in

managing CRPS is with intravenous

regional administration of

sympa-tholytic agents, NSAIDs, and

corti-costeroids Numerous systemic

medications have been studied for

relief of pain in CRPS, but no clear evidence advocates the use of any of these drug therapies for lower extremity CRPS Published evi-dence seems best to support the use

of the anticonvulsant gabapentin, the α-adrenergic blocking agent pra-zosin, the oral beta blocker propran-olol, the calcium channel blocker nifedipine, and the antiarrhythmic mexiletine Results with bisphos-phonates have been encouraging

Gentle physical therapy is bene-ficial in all stages of CRPS both to control edema and prevent joint contracture, but it has little proven effect on pain Overly aggressive therapy can increase pain A multi-disciplinary team approach to management is recommended, including chronic pain manage-ment specialists and physical thera-pists as well as orthopaedic sur-geons

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