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Flashcards in Chapter 50 Complex Regional Pain Syndrome Deck (57):

Complex regional pain syndrome (CRPS) Types I and II
(formerly known as reflex sympathetic dystrophy [RSD]
and causalgia, respectively)

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.



a constant burning pain


The radiographic changes started
as a

“patchy osteoporosis of the small bones of the hands
or feet and the distal metaphysis of the forearm or tibial bones,”


term complex regional pain
syndrome was therefore considered broad enough to allow the inclusion of patients who

may show varying levels of sympathetic nervous system involvement in maintaining pain
through the course of the disease process, hence the term sympathetically mediated pain (SMP) or sympathetically independent pain (SIP)


CRPS commonly occurs

younger females and often results from workrelated
injuries or surgery


CRPS is associated with

sleep disturbance, functional impairment, and suicidal ideation


CRPS Type I and Type II differ only by

the presence
(Type II) or absence (Type I) of evidence of nerve injury.


hallmark of the condition

Pain is the hallmark of the condition, and commonly manifests as spontaneous pain, with hyperalgesia and allodynia.


Associated signs include

vasomotor and, sudomotor active
disturbances and passive movement disorders in addition to
trophic changes


CRPS Type I and Type II difference

CRPS Type II develops after defined nerve injury, whereas CRPS Type I develops following minor or major injuries with little or no obvious damage to the nerves
in the involved extremity.


Peripheral sensitization

resulting from the persistent nociceptive
afferent activity as a result of the initial tissue
trauma is thought to occur


Following local injury, the
primary afferent fibers in the traumatized area release

neuropeptides such as bradykinin and substance P, which result in increased firing of nociceptors to noxious stimuli and reduced firing threshold to mechanical and thermal stimuli; this may account for the hyperalgesia and allodynia pathognomonic of CRPS



Persistent nociceptive input associated with nerve injury from tissue trauma results in increased activity of nociceptive neurons in the spinal cord


The central sensitization is mediated by

the induced release of neuropeptides such as bradykinin and substance P and the excitatory neurotransmitter glutamate
acting at the spinal N-methyl-d-aspartic acid receptors. This activity results in enhanced response to non-noxious
stimuli (allodynia) and noxious stimuli (hyperalgesia)


There has been an indication of an interaction between
the sympathetic noradrenergic neurons in the periphery

the primary afferent neurons as part of the underlying mechanism of sympathetically maintained pain (SMP)
in patients with CRPS I.


mechanisms may be responsible for the acute phase of
CRPS. This may occur either through the classic cascade
of release of pro-inflammatory cytokines

IL-2, IL-6, and tumor necrosis factor-a) from mast cells
and lymphocytes following tissue trauma, or secondary to
neurogenic inflammation causing the release of cytokines and neuropeptides (including substance P and calcitonin
gene–related peptide [CGRP])


The neuropeptides can increase

tissue permeability and cause vasodilatation,
giving rise to the “warm CRPS” with edema


Substance P and TNF-a can engender

osteoclastic activity, which may
contribute to the osteoporosis seen in CRPS


Cortical reorganization in central somatosensory
and motor networks that may result in

altered central processing of tactile and nociceptive stimuli and cerebral organization of movement


Diagnostic Criteria for CRPS I Reflex Sympathetic Dystrophy

1. The presence of an initiating
noxious event or a cause of
2. Continuing pain, allodynia, or
hyperalgesia with which the
pain is disproportionate to
any inciting event
3. Evidence at some time of
edema, changes in skin blood
flow, or abnormal sudomotor
activity in the region of the
4. This diagnosis is excluded by
the existence of conditions
that would otherwise account
for the degree of pain and


Diagnostic Criteria for CRPS II

1. The presence of continuing
pain, allodynia, or hyperalgesia
after a nerve injury, not
necessarily limited to the
distribution of the injured
2. Evidence at some time of
edema, changes in skin blood
flow, or abnormal sudomotor
activity in the region of the
3. This diagnosis is excluded by
the existence of conditions
that would otherwise account
for the degree of pain and


key feature for both CRPS I and II



With CRPS I, the pain and associated clinical signs and symptoms are typically

out of proportion to the inciting event. The pain is typically described as a burning deep-seated ache with a shooting quality and associated
allodynia or hyperalgesia


To make the clinical diagnosis, the following criteria
must be met:

1. Continuing pain, which is disproportionate to any inciting
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: Evidence 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)


To make the clinical diagnosis, the following criteria
must be met:

3. Must display at least one sign at 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


diagnostic criteria for CRPS Types I and II

based on the patient’s symptoms and signs.


the IASP criteria suggest that patients should demonstrate
at least one symptom in each of the following categories:

sensory (hyperesthesia—increased sensitivity to sensory stimulation), vasomotor changes (temperature abnormalities,
including skin and color changes), sudomotor (fluid
retention—sweating abnormalities, edema), or motor (decreased
range of motion, weakness, tremor, dyskinesia, or neglect).In addition, signs in at least two of the four categories
indicated above should be noted on physical examination
of the patient.


help differentiate from more common conditions that may mimic CRPS

A complete history and physical examination, including a through neurologic and vascular examination.


Differential Diagnosis of CRPS

These include neurologic
conditions such as painful diabetic neuropathy, entrapment syndromes, discogenic disease, and thoracic outlet syndrome. In addition, vascular conditions should be considered
as possible causes in the differential diagnosis,
including deep venous thrombosis, cellulitis, vascular
insufficiency, lymphedema, and erythromelalgia.


gold standard or objective test that is specific for CRPS

there is no diagnostic test



This involves the use of standardized psychophysical tests of thermal, thermal pain, and vibratory thresholds to assess the function of large fiber, myelinated small fiber, and unmyelinated small afferent fibers. Static and dynamic allodynia, allodynia associated with pinprick, hyperalgesia related to mechanical and heat stimuli, and temporal summation
(increased pain to repeated stimuli) may be abnormal
in patients with CRPS. Since no specific sensory pattern has been recognized with CRPS, assessment of the
signs and changes over time may provide a tool to track
response to treatment



This includes infrared thermometry and thermography,
quantitative sudomotor axon reflex test (QSART), thermoregulatory
sweat test (TST), and laser Doppler flowmetry.



The limitation of these tests is that most require special
equipment and a setup that make clinical applications less



The use of infrared thermometry and infrared thermography
to assess small skin temperature differences between
the sides of the body is reported to achieve sensitivity in
the order of 76% and specificity of 100%


this test clinically is dependent on

The utility of
maintaining controlled
thermoregulation during measurements. This is difficult
to achieve in most clinical situations. Therefore the measurements
should be made under conditions where thermoregulation
can be controlled to detect differences on
both side for enhanced accuracy of the test.


The direction
of the temperature difference is dependent on the duration
of the disease

Earlier in the disease process the affected limb may demonstrate elevated temperatures, while later on in the more chronic phase of the disease the affected
side may show lower temperature compared to the unaffected



In patient with the disease of less than 4 months’ duration,
vascular reflex responses may be assessed using Doppler
flowmetry. The affected extremity may demonstrate higher perfusion. In patients with duration of disease less than 15 months, skin perfusion was found to be either higher or lower, while in patients with a mean duration of 28 months
the affected limb demonstrated a lower perfusion and ultimately lower temperatures



The value of a three-phase bone scintigraphy is in
the ability to

detect pathologic delayed uptake in the distal bones, such as metacarpophalangeal or metacarpal bones. Most of these changes have been reported to occur within the first year of the



X-ray bone densitometry has also been reported to have

a high sensitivity and specificity for CRPS.


NSAIDs in the treatment of CRPS

NSAIDs can provide mild to moderate pain relief.



widely for the treatment of neuropathic pain. Norepinephrine and
serotonin blockers and selective norepinephrine blockers like amitriptyline and desipramine respectively, may exert
their influence by modulating the noradrenergic and serotonergic
descending pathways.


Antidepressants usual dose

range for
these drugs is about 10 to 75 mg by mouth at night time



Gabapentin and pregabalin have been
shown to be effective in diabetic neuropathy and postherpetic
neuralgia (PHN). Studies in patients with CRPS
have also demonstrated analgesic effect of gabapentin



The Food and Drug Administration (FDA) has approved
carbamazepine for trigeminal neuralgia and may be considered
as a second-tier option for CRPS



The analog of
carbamazepine, oxcarbazepine, which does not exhibit the
side effects of liver and bone marrow toxicity, may be used as an alternative drug



should therefore be used as part of a multimodal
pharmacologic treatment regimen, particularly if other single agents do not provide optimum analgesia


Antidepressants and doses

Amitriptyline 10–75 mg/day qd at night
Nortriptyline 10–75 mg qd at night
Desipramine 10–75 mg/day qd at night
Venlafaxine 37.5–340 mg/day BID-TID


Anticonvulsants and doses

Gabapentin 900–3600 mg/day TID
Pregabalin 150–600 mg/day BID–TID
Carbamazepine 100–1000 mg/day BID–QID


Opioids and doses

Morphine (extended release) 15–60 mg BID–TID
Oxycodone (extended release) 10–60 mg BID–TID
Methadone 5–20 mg BID–TID



provide pain relief in patients with CRPS. its analgesic properties are derived from the release of b-endorphins.


Intrathecal Baclofen

CRPS can lead to dystonia often refractory
to standard treatment, and baclofen a GABA (type
B) receptor agonist that inhibits sensory input into the
spinal cord has been shown to be effective in some patients
with dystonia.


Spinal Cord Stimulation

There is increasing evidence to support the value of spinal cord stimulation (SCS) in the
treatment of patients with CRPS who have experienced
suboptimal benefit from conventional therapy


Functional Restoration

remains is the hallmark of successful treatment of CRPS. This is best
achieved in a multidisciplinary setting with the occupational
therapist initiating the early desensitization process and the physical therapist addressing muscle strength, flexibility, gait training, and overcoming the kinesophobia typically associated with advanced CRPS.


In Functional Restoration
a recreational therapist may be involved in the later stages of restoration
to help

the patient return to socialization and engagement
in recreational activities that may have been neglected in
the course of the disease.


Motor Imagery Program

A motor imagery program (MIP)
incorporates recognition of the limb laterality, imagined
movements, and mirrored movements using a mirror box



Depression and anxiety commonly occur
in patients with chronic pain. This is amplified in CRPS as
a result of the uncertainty associated with the cause,
course, and treatment of the disorder


post-traumatic stress disorder

The risk of developing
post-traumatic stress disorder is present in this patient population amid fears that the disease may progress or recur without warning. Instituting cognitive-behavioral therapy is the most effective psychological intervention found to produce long-lasting reduction in psychological symptoms in both children and adults with CRPS.

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