COMPLEX REGIONAL PAIN SYNDROME
REFLEX SYMPATHETIC DYSTROPHY SYNDROME
DIAGNOSIS AND THERAPY- A REVIEW OF 824
Hooshang Hooshmand, M.D. and Masood Hashmi, M.D.
Neurological Associates Pain Management Center
1255 37th Street, Suite B
Vero Beach, FL 32960
*** This abstract is
summarized from the review article
Pain Syndrome-Reflex Sympathetic
Therapy-A Review of 824
( Pain Digest- 1999;
This is a study of 824 Complex regional
pain syndrome (CRPS) patients treated between January 1991 thru January 1996. The
diagnostic and therapeutic approaches are compared with medical literature. At least two
follow up visits was required to enable a patient to be included in the study. Problems of
terminology, over - and under -diagnosis are discussed.
For over a century, CRPS has been
recognized as a syndrome. This syndrome is a complex form of neuropathic pain associated
with hyperpathia; neurovascular instability, neuroinflammation, and limbic system
dysfunction. It is triggered by stimulation of neurovascular thermoreceptor c- fibers
sensitized to norepinephrine. This afferent sensory impulse leads to CRPS . The syndrome
involves extremities, head, back, shoulder, breast, as well as viscera.
The neurovascular dysfunction of CRPS
separates this condition from the somatic (unrelated to the sympathetic) system pain
syndromes. The standard somatic pain is a circumscribed, focalized pain sensation usually
not accompanied by neurovascular dysfunction. It does not generate an inflammatory
response. In somatic pain, the involved larger myelinated nerve fibres (somatosensory
nerve fibres) can be easily detected and studied by nerve conduction studies. This is in
contrast to the CRPS pain which is a disturbance of microcirculation generated by small c
fibres in the wall of arterioles which are not large enough in size to be detected by
nerve conduction studies. The neurovascular involvement in the form of temperature change,
poor circulation, and neurovascular instability separates this syndrome from the somatic
(non-sympathetic) type of painful conditions.
The disease affects young and old as
well. It is as common in children, usually with good prognosis; but it is not usually
diagnosed in time, if at all.
CRPS has a long list of etiologies,
including trauma. The trauma is usually minor. Major trauma is more likely to stimulate
somatic (non-sympathetic) nerves which tend to overshadow the sympathetic system type of
pain reducing the likelihood of development of CRPS. Certain traumatic events are more
common originators of CRPS: repetitive stress injury, unexpected injury such as stepping
off a curb, missing a step; or an injury to the dorsum of the hand or foot are some of the
For clinical examples, among our 824
consecutive CRPS patients, the following cases due to microvascular nerve dysfunction were
identified: lipid metabolism disturbance in the wall of the arterioles (Fabré Disease),
four patients; minor injury to the small blood vessels due to hypermobility of the joints
(Ehrler Danlos Syndrome), two patients; electrical injury with passage of electricity
through the path of the least resistance (arterioles) 63 patients; venipuncture CRPS due
to the rare complication of needle insertion causing selective damage to unmyelinated
small c-fibre nerves in the wall of the venules, 17 patients.
Due to a fluctuating clinical picture a
careful history taking helps identify the warning signs. CRPS should be considered
whenever a patient is having an unusual problem with excruciating pain, stiffness and
inflammation following a minor trauma. Instantaneous, severe edema immediately following a
minor trauma, in absence of bone, tendon, or ligament injury, is a strong warning sign of
onset of CRPS. When the trauma of surgery, arthroscopy, or application of cast to an
extremity causes acute edema and circulatory disturbance, the diagnosis of CRPS should be
considered. Persistent pain and swelling of unexplained origin, aggravated by bed rest, or
on arousal, is highly suspicious of CRPS.
Asymmetrical excessive sweating
(hyperhydrosis) in painful extremity, is a major warning sign. Other warning signs are
development of hyperpathia and allodynia after osteomy at the elbow, rib, or foot
There has been a lot of confusion
regarding proper terminology of CRPS. The complex clinical picture of RSD has eluded
simple terminology. Even at present time, the mere existence of the disease has been
denied by those who do not understand the disease. This flies in the face of documented
peripheral and central nervous system dysfunctions of the disease. Mitchell first labeled
the syndrome as erythromelalgia and later as causalgia. Sudeck reported atrophy and
inflammation. The sympathetic role in the development of causalgia was first reported by
LeRiche in 1916, who did the first sympathectomy. Other names have consisted of
trophoneurosis, traumatic angiospasm, traumatic vasospasm, mimocausalgia, and minor
causalgia. The French literature usually refers to it as algodystrophy.
The latest terminology is complex
regional pain syndrome (CRPS), which is a more descriptive and inclusive terminology.
However, it does not include inflammatory and neuropsychological aspects of the syndrome
in its terminology. The definition of CRPS does not exclusively limit the condition to the
syndrome of RSD. An example, brachial plexus damage due to radiotherapy for cancer of
breast is a CRPS without inflammation and vasomotor dysfunction.
Recently, Galer et al have pointed to
tendency for over- diagnosis of this disorder using CRPS criteria. They noted that 37% of
diabetic neuropathy patients met the diagnostic criteria of CRPS, which is an obvious
tendency for over-diagnosis.
CRPS II, which refers to the causalgic
form of RSD, points to the fact that in causalgia there is ectopic and ephaptic nerve
damage bypassing the synaptic transmission of electric current in nerve fibres between the
adjacent damaged smaller and larger myelinated nerves. The CRPS II is a more specific term
than causalgia which is nonspecific and can be present in conditions other than CRPS.
SYMPATHETICALLY MAINTAINED PAIN
SYMPATHETICALLY INDEPENDENT PAIN
The phenomenon of sympathetically
maintained pain (SMP), referring to selective diagnostic blockade of pain with alpha-1
blockers such as Phentolamine, and Guanethidine have been mistaken for exclusive
prerequisite for diagnosis of CRPS. In early phases of CRPS (a few weeks to a few months),
the pain is usually successfully blocked with Phentolamine alpha-1 sympathetic blockade
confirming the SMP nature of the pain. As the disease becomes chronic, and especially as
the condition becomes complicated by treatment modalities such as surgery or repetitive
application of ice, the pain changes its nature from SMP to SIP(sympathetic independent
In early stages, the disease is
characterized by up-regulation and supersensitivity of sensory nerves to norepinephrine.
In chronic stages, the disease is manifested by a dysfunctional rather than an
up-regulated sympathetic system. By then, the clinical picture also changes due to the
inflammatory nature of the neuropathic pain leading to edema, secondary entrapment
neuropathies, subcutaneous hemorrhages, or neurodermatitis. In addition, with passage of
time, neurovascular instability develops pointing to dysfunction and failure of the
sympathetic system to protect and to sustain normal vasomotor function. This phenomenon,
causing fluctuating changes of circulation and color of the extremity in a matter of a few
minutes (chameleon sign), reflects lack of sustained normal tonus of arteriolar
vasculature normally achieved by intact sympathetic function. The neurovascular
instability cannot be expected to be responsive to sympathetic blocks (SMP) due to
instability and random dysfunction of vasomotor tonus. This is one of the factors that
explain the SIP nature of CRPS after a few months.
There are other types of neuropathic pain
with neurovascular dysfunction which are SMP in nature, but do not have the rest of the
characteristics of CRPS. Examples: post-herpetic neuralgia, diabetic neuropathy, and
neuropathic pain seen in HIV or cancer patients. So, not every SMP is synonymous with
CRPS. Simple reliance on sympathetic nerve blocks for the diagnosis of RSD, especially in
later stages of the disease, can be misleading. The SMP-SIP confusion plays a major role
in over- and under-diagnosis of CRPS .
Lack of response to sympathetic block
should spare the patient from excessive repetitive sympathetic ganglion blocks (which
traumatize the ganglion cells). Instead, other nerve blocks which suppress both
sympathetic and somatic nerves such as regional BIER block, brachial plexus block,
epidural block, and paravertebral block are more effective and helpful.
LeRiche, first blamed the disease as
dysfunction and stimulation of the sympathetic system. However, it has become clear that
all CRPS is not SMP, ruling out simple stimulation and up-regulation of the sympathetic
system. Moreover, sympathectomy is usually a failure. Livingston postulated a
"vicious circle" of activated internuncial pools of spinal cord up-regulating
the efferent spinal cord sympathetic nerves with secondary ischemia (due to
vasoconstriction) restimulating the neural pools of the spinal cord. More recent research
has emphasized the supersensitization of the sensory afferent alpha adrenoreceptors rather
than the efferent sympathetic nerves as the causative factor.
The sympathetic system has three major
1. Regulation of body temperature.
2. Regulation of vital signs (BP, pulse,
3. Regulation of the immune system .
The above three functions are aimed at
protection of the internal environment of the body (milieu interne). Keeping the above
physiologic functions in mind, the complex symptoms and signs of CRPS make more sense and
help the clinician arrive at proper diagnosis of the syndrome based on the following four
minimal diagnostic criteria:
1. Afferent sensory dysfunction of
thermoreceptors, mechanoreceptors, and chemoreceptors (pain).
2. Efferent vasomotor response
3. Control of immune system as a
protective stabilizer of "milieu interne" (inflammation).
4. Limbic system modulation of
the sympathetic system (emotional disturbance).
THE FOUR CLINICAL PRINCIPLES OF
The neuropathic pain of CRPS is
manifested by: one or more of the following pain modalities: hyperpathia (protopathia),
allodynia ,ectopic or ephaptic pain of causalgia, and inactivity-
chemoreceptor-originated deep pain (Table 1).
Pain modalities in CRPS
Type of pain
||Myelinated A- beta
inactivity;avoidance of tactile sensory input
|Deep Burning Pain
cast application, wheel chair, heavy sedation
(Ephaptic) electric short between myelinated and unmyelinated nerve fibers
diagnostic or therapeutic needle injection in the nerve damage area
CRPS usually starts with microvascular
neuropathic pain, and is accompanied by a variety of pains depending on the nature of
This is an intense, usually persistent,
and burning regional pain. The hyperpathic pain was constant in 81% of our 824 patients.
Blümberg and Jänig reported the pain constant in 75%, and intermittent in 25% of their
patients. The pain is out of proportion to the severity of trauma.
Simple tactile stimulation of the
involved area originating the hyperpathia may be accompanied by objective signs of rise in
pulse and BP. In addition, the hyperpathic pain is accompanied by a regional mild
hypoesthesia to touch and pain. This hypoesthesia is not in the sensory distribution of
somatic nerve roots.
By virtue of exclusive function of
thermal regulation, these thermal sensory nerve fibres have an affinity to the anatomical
structures of arterioles and arteries (heat source). As a result, dysfunction of these
sensory nerve fibres does not show a dermatomal, but a thermatomal sensory nerve
distribution. This is a sensory loss usually in the distribution of brachial, femoral,
carotid, or mesenteric arteries.
There are actually three different types
of sensory loss:
3. Glove and stocking distribution .
The dermatomal sensory loss is seen in radiculopathies,
and other forms of somatic sensory nerve damages. The thermatomal, neuropathic
(microvascular) pain distribution is usually seen in CRPS, diabetic neuropathy, and post
herpetic neuralgia. This type of thermatomal sensory loss should not be mistaken for the
classical glove and stocking sensory loss - due to primary or secondary gain (malingering
or conversion reaction) - which limits itself to joints such as the wrist, knee, or
shoulders in a glove and stocking distribution. Only a careful examination of touch and
pain sensations separates each of these three sensory types.
SPREAD OF CRPS
The regional hyperpathia (protopathia) is
mainly due to summation of repetitive stimulation of the thermoreceptors, which results in
a tendency for spread of hyperpathia to proximal and distal portions of the extremities.
In advanced, complicated cases, it may lead to horizontal and vertical spread to other
extremities. This spread may play a major role in aggravation of CRPS. This phenomenon is
due to stimulation of the uninhibited c-fibres perpetuating the sensitization of afferent
receptor nerves in the spinal cord . Other factors such as sympathectomy and surgical
procedures are also instrumental in the spread of CRPS.
Activation of thermal c nociceptor
sensory pain fibres plays a major role in hyperpathic pain. The afferent small c-fiber
system has a tendency to be inhibited by the larger A-fiber myelinated somatosensory
nervous system. Lack of such inhibition (i.e., lack of simple touch or avoidance of
tactile contacts due to hyperpathic pain)can result in increased firing of the afferent
neuropathic pain fibres with secondary pathological efferent sympathetic discharge, and
further sensitization of the layers I and II of the gray matter of the spinal cord. This
is not a simple up-regulation, but a dysfunction of the sympathetic system. This
dysfunction explains the reason for failure of sympathectomy. Sympathectomy aggravates the
already existing sympathetic dysfunction.
Allodynic pain is elicited by a stimulus
that usually does not cause pain: e.g., a simple breeze, bed sheet contact, and other
types of mild tactile stimulation. In CRPS, there is a tendency for sensitization of the
involved skin surface. Typically, the patient avoids any type of sensory stimulation, and
protects the allodynic area with the help of wrapping the extremity with a cloth or a
glove. In extreme cases, the patient may avoid taking a shower or bathing for months.
Mechanoallodynia is usually mediated by A-beta low-threshold mechanoreceptors which are
small myelinated nerve fibres. They do not respond successfully to pure sympathetic
ganglion blocks. They are more likely to respond to epidural or paravertebral blocks.
Application of ice exaggerates
vasoconstriction, coagulates and damages the myelinated nerve fibres, aggravates the nerve
damage and enlarges the area of Mechanoallodynia resulting in bias toward SIP rather than
SMP. Procedures such as carpal tunnel surgery for inflammation due to CRPS, arthroscopy,
or exploratory surgical procedures, also aggravate the sensory damage and reproduce a
similar allodynic phenomenon.
In our study the application of ice for 2
months or longer resulted in a higher percentage of stage III-IV as compared to no ice or
less than 2 months treatment(P<0.001). As ice selectively damages and coagulates the
myelinated nerve fibers(which are rich in lipids), the allodynia is gradually transformed
to thermatomal hyposthesia augmented by ice induced hypothermia.
The causalgic pain in CRPS II syndrome,
is characterized by attacks of "lightning," "stabbing," "electric
shock," "prickling," "deep itching, " and "jerking "
type of pain. In later stages, the pain is accompanied by myelogenic response of myoclonic
jerks of the extremity or of the trunk - as well as atonic (akinetic) falling attacks -
due to myelopathic sensitization.
1D. DEEP PAIN OF INACTIVITY
Recently, Blümberg , Jänig and
Koltzenburg have discovered a new source of pain. It originates from the deep
chemoreceptor c-fibres in muscle and bone. These chemoreceptors become activated with
inactivity. Blümberg and Jänig reported incidence of pain with inactivity in 65% of
their patients. The deep spontaneous pain associated with inactivity showed a higher
incidence in 75% of their patients. In our series of 824 patients, the deep pain sensation
on arousal in the morning (associated with inactivity) was noted in 79% of patients vs
pain with activity in 63% of patients. The patients describe this type of pain as deep,
itching, and intolerable. With increasing inactivity (e.g., use of wheelchair), this deep
pain arouses the patient 2 ½ times more frequently than the ambulatory patients.
Intermittent walking reduces the incidence of deep pain.
FOUR PRINCIPLES OF CRPS
2. EFFERENT (MOTOR) RESPONSE
The second diagnostic principle is
efferent motor dysfunction in the form of vasoconstriction, flexor spasm, movement
disorder including dystonia and tremor. In more advanced cases, myoclonic jerks due to
spinal cord sensitization and de-afferentation develop. These myelogenic myoclonic jerks
are due to the enlargement of peripheral receptive fields of central pain projecting
neurons in superficial laminae I and II of the dorsal horn. The sensitization and the
enlargement of laminae I and II excitatory fields is due to relatively long-term,
uninhibited dysfunctional afferent sensory nerve input to the deeper layers 4 and 5 of
dorsal horn of the spinal cord. The deeper layers 4 and 5 exert inhibitory function on
superficial laminae I and II excitatory internuncial cells. The small granular primary
sensory neurons of the superficial layers 1 and 2 normally possess small receptor fields
that respond mainly to the c-nociceptors and A-delta fibres. These neurons synthesize
neuropeptides that are transported through the afferent fibres centrally and peripherally.
The chronic repetitive stimulation of these sensory nerve fibres is accompanied by release
of chemicals such as calcitonin G-related peptide (CGRP), substance P and Nitric Oxide
(NO). Excessive somatostatin and substance P release can potentially damage and reduce the
inhibitory function of the granular cells in the deeper layers 4 and 5 of dorsal horn
neurons leading to sensitization, deafferentation, and aggravation of hyperpathic pain and
allodynia. The same phenomenon leads to myelogenic myoclonus. CGRP exerts an inhibitory
effect on the excitatory neurokines substance P and somatostatin. Dynorphin activation and
break down by inflammation contributes to sensitization of the dorsal horn. Lack of
inhibition of the larger afferent nerve fibres and secondary disturbance of inhibition of
wide dynamic range function of the layers 4 and 5 results in increased excitation of the
efferent spinal cord nerve cells. The end result is disturbance of spinal cord plasticity,
deafferentation, attacks of myelogenic myoclonic jerks, akinetic attacks, as well as
tremor and other forms of movement disorder. Simple somatic peripheral nerve injury is not
enough to cause tremor. The above- mentioned central sensitization at spinal cord level is
required to lead to dystonia and tremor.
The motor dysfunction may manifest itself
in the form of dystonic flexor spasm, flexor deformity , toe walking, and pronation of the
hand or foot (equino varus). The dystonic flexor spasm seems to be due to the primitive
withdrawal response to the pain source. Tremor is not uncommon. Blümberg and Jänig have
reported tremor and other movement disorders in over 80% of CRPS patients. Veldman, et al,
have noted movement disorder in 95% of 829 patients. In our series of 824 patients, the
incidence was 78%. Application of cast causes immobilization and stimulation of the deep
mechanoreceptors. These "silent sleeping nociceptors" become activated with rest
and inactivity. This in turn, leads to pain, edema and movement disorder. Cardoso and
Jankovic have reported 11 cases of patients suffering from CRPS who developed Parkinsonian
type of tremor following application of cast to the extremity. The cast becomes harmful if
the extremity is edematous and inflamed due to neuroinflammation of the original trauma or
Myoclonic jerks may be a manifestation of
de-afferentation and sensitization of spinal cord due to long-term afferent cytokines
damage to the inhibitory granular cells in layers I and II. As such, they develop in later
stages of the disease. Any form of immobilization (cast, wheelchair, etc.)contributes to
this phenomenon. The myoclonic jerks are seen in patients undergoing withdrawal of opioids
In 38 of our 824 patients suffering from
CRPS due to spinal cord injury myoclonic jerks were invariably observed by the examiner.
Yet, more than 3/4 of the CRPS patients has a history of myoclonic jerks- not observed at
the time of examination. In addition, myoclonic jerks were present in 44 of 63 CRPS
patients secondary to electrical injury. This may be due to electricity going through the
path of least resistance (afferent c-fibers) and secondarily originating spinal cord
dysfunction. Myoclonic jerks are a long term complication of limb amputation (10 of 11
amputees among our 824 patients).
THE FOUR PRINCIPLES OF RSD
3. DISTURBANCE OF IMMUNE SYSTEM
The third diagnostic principle is
neuropathic pain, including CRPS I, is complicated by inflammation in varying degrees.
This inflammation was first reported by Mitchell (1864)as "shiny skin" and,
later on, by Sudeck (1942). The neurogenic inflammation results in bullbous lesions,
sterile abscess, edema and impingement of the nerves at the wrist, elbow, thoracic outlet
and ankle areas - resulting in the disease being mistaken for conditions such as carpal
tunnel, thoracic outlet (TOS), tarsal tunnel syndromes, and myofascial syndrome. The
well-intended surgical procedure to relieve such entrapment neuropathies may in turn
aggravate the inflammation by virtue of surgical trauma becoming a new source of
The inflammation is another manifestation of
dysfunctional sympathetic system. The sympathetic system is responsible for immune system
regulation (Arnason, 1993). As a result, the patient may develop bouts of unexplained
fever, edema, attacks of subcutaneous bleeding, neurodermatitis, bulbous lesions , pelvic
inflammatory disease (PID), or interstitial cystitis. Inflammation may cause development
of subcutaneous skin nodules, pulmonary nodules, laryngitis, difficulty with phonation,
attacks of hacking cough and hematemesis. In late stages it can cause elephantiasis,
subcutaneous bleeding, bullous deep ulcerative lesions involving the skin as a
manifestation of disturbance of the immune system. It can be mistaken for infection,
osteomyelitis, dermatitis, and cystitis. Treatment with antibiotics provides no relief.
The inflammation is usually intermittent,
and is not consistently present. Only a careful history taking can document previous
attacks of inflammation.
THE FOUR CLINICAL PRINCIPLES OF
4. EMOTIONAL ASPECTS OF CRPS:
LIMBIC SYSTEM DYSFUNCTION
The forth and final diagnostic principle
is emotional disturbance in CRPS. In contrast to somatic sensory nerves, the sensory
neuropathic nerve fibres responsible for the development of CRPS do not end up in the
contralateral neocortical parietal sensory cortex. Instead, according to Bennarroch, over
90% of these sensory nerve impulses terminate in the limbic system. More over, positron
emission tomography (PET) demonstrates a significant cerebral insular and limbic
activation during painful stimulation of neuropathic pain. The vicious circle of chronic
neuropathic pain leading to disturbance of plasticity, as well as inflammation, causes
further long term potentiation (LTP)of pain impulse and nerve stimulation in higher
centers in the limbic system. This leads to insomnia, agitation, depression, poor memory
and poor judgment. The above neurophysiological observations explain the fact that
practically every patient suffering from CRPS demonstrates some degree of limbic system
disturbance. In our study of 824 patients, one or more of the limbic system dysfunctions
were present in every case except three. These consisted of insomnia (92%), irritability,
agitation, anxiety (78%), (depression (73%), poor memory and concentration (48%), poor
judgment (36%), and panic attacks (32%). Understanding the nature of emotional components
of RSD spares the patient from misdiagnosis and improper treatment.
The majority of chronic pain patients
suffer from the somatic type of nerve damage or dysfunction, with no neurovascular
involvement, such as carpal tunnel syndrome (CTS), thoracic outlet syndrome (TOS), tarsal
tunnel syndromes, rotator cuff injury, disc herniation, Mortons neuroma,
fibromyalgia (FM), or myofascial syndrome(MFS). In a small minority of cases, the patients
suffer from similar syndromes caused by neuropathic/ neurovascular damage or dysfunction
mimicking the above syndromes. The clinician has a tendency to try to explain the
manifestation of such neuropathic pain (such as CRPS) by categorizing the disease as
somatic syndromes mentioned above. Even normal EMG/NCV tests do not convince the surgeon
to cancel the carpal tunnel surgery. Even the purplish skin discoloration or asymmetrical
sweating does not bring up a question about the presumptive presurgical diagnosis of CRPS.
The loser is the patient who has to cope with the new source of neuropathic pain at the
surgical scar area as well as the referred pain and the spread of CRPS to other parts of
the body due to the trauma of surgery.
The main hurdle in diagnosis is the fact
that majority of physicians do not consider CRPS in their list of differential diagnosis.
This syndrome is commonly over-or under- diagnosed. In our series of 824 patients, CRPS
was over-diagnosed in 134 (16%) of cases, and under diagnosed in 173 (21%) of cases (Table
2). The 134 over-diagnosed cases have already been excluded from this study.
A syndrome as complex - and as potentially
variable in symptomatology and temporal course as RSD- cannot be expected to be diagnosed
with a single laboratory test. CRPS is a syndrome and should be diagnosed by inclusion
(the above- outline 4 principles) rather than by exclusion.
1. Scintigraphic triphasic bone scanning
(SBS) has been the popular test of choice for the diagnosis of CRPS in the past three
decades. Whereas earlier literature has described the SBS as highly sensitive and specific
in establishing the diagnosis of CRPS, a recent review of medical literature by Lee and
Weeks has shown this test to be positive in approximately 55% of the cases, which is quite
close to a random statistical yield. Chelimsky et al found this test abnormal in no more
than 25% of CRPS patients.
2. Diagnostic nerve blocks phentolamine
and guanethidine are usually positive in the early stages and gradually lose their
3. EMG and NCV: A. CRPS I (RSD):
Realizing that CRPS I is due to dysfunction of poorly myelinated or unmyelinated sensory
nerve fibres, EMG and NCV cannot be expected to show any abnormality. NCV measures the
velocity and function of the large myelinated fibres, which are not usually involved in
CRPS I. EMG/NCV cannot identify disturbance of small sensory or autonomic nerve fibres .
Diagnosing CRPS with the help of EMG and NCV is similar to diagnosing a viral infection
with a standard- rather than an electron microscope.
4. Computed tomography and magnetic
resonance imaging (MRI) are not expected to detect the damage to the microscopic nerve
fibres in the wall of blood vessels, and usually do not show any abnormalities in CRPS.
5. Quantitative sudomotor axon reflex
test (QSART) studies the cholinergic sudomotor function of the sympathetic system. It does
not address the norepinephrine dysfunction. It has a high degree of sensitivity and
specificity in detecting post-ganglionic dysfunction of cholinergic (parasympathetic)
6. Infrared thermal imaging (ITI): The
infrared imaging has a limited application in neurology. It can study and compare subtle
temperature changes in different parts of the body. Like any other test outlined above, it
cannot "diagnose" CRPS, but can identify areas of damage(hyperthermia) versus
irritation (hypothermia) of sympathetic nerves. The ITI is quite sensitive in pointing to
the function of skin temperature which is the exclusive domain of sympathetic system. Cold
stress-ITI may provide additional useful information. Limitations of ITI: The thermal
imaging shows any old or new sympathetic nerve damage or dysfunction, thus confusing the
examiner and demanding careful and proper clinical correlation. In addition, as the
disease becomes chronic and the sympathetic dysfunction becomes bilateral, the ITI shows
identical bilateral temperature changes causing difficulty in diagnosis. The same
phenomenon causes confusion in interpretation of other tests in CRPS. Infrared thermal
imaging is useful in identifying the area of maximal damage as follows:
A. In the area of original nerve damage
(e.g., hand or foot), the hyperthermia points to damage and paralysis of vasoconstrictive
function of sympathetic system (the central hyperthermic area). The central hyperthermia
usually points to the apex of damaged tissue resulting in heat leakage, as well as
accumulation of substance P and nitric oxide. This is an important therapeutic clue to
avoid further trauma. Traumatic procedures such as surgical exploration, nerve blocks,
Clonidine Patch, Capsaicin, or EMG needle insertion should not be applied to the damaged
hyperthermic area in the extremity which may lead to further damage and aggravation of the
condition. In acute stage, the damaged area is hyperthermic. After a few weeks, the
hyperthermic area shrinks. In some cases the hyperthermia persists due to permanent damage
to sympathetic nerve fibers. This bodes a poor prognosis.
B. Hyperthermia in referred pain areas
(e.g., paravertebral nerves ) is due to SP and NO accumulation, but does not necessarily
point to the origin of the injury.
C. Virtual Sympathectomy: After more than
a dozen stellate, or lumbar ganglion nerve blocks, the repetitive needle insertion
traumatizes the ganglion enough to result in permanent hyperthermia in the extremity
("Virtual Sympathectomy"). Infrared imaging identifies this phenomenon, and
spares the patient from further damage.
7. Laser Doppler Flow Study is a
sensitive test for the study of capillary circulation. It studies a small area of the body
limiting its overall extent of information. This test has demonstrated sympathectomy to be
ineffective in providing increased circulation in extremity after exposure to cold.
8. Quantitative thermal sensory evoked
response test (QST) is sensitive and useful in studying the functions of c-thermoreceptors
and A-beta mechanoreceptors in CRPS. This test identifies the threshold of cold and heat
touch and pain sensations. This test may be abnormal in CRPS patients (cold hyperalgesia)
and in erythromelalgia (heat hyperalgesia). The test has been well standardized.
The CRPS has been divided into different
stages. Depending on nature of injury, the stages vary in their duration. In the 17
patients suffering from venipuncture CRPS in our series, deterioration from stage I to
stage III was measured in a few weeks up to less than 9 months. This is in contrast with
CRPS in children in whom stages would stagnate, reverse or improve slowly.
The STAGE I , is a sympathetic
dysfunction with typical thermatomal distribution of the pain . The pain may spread in a
mirror fashion to contralateral extremity or to adjacent regions on the same side of the
body. In stage one, the pain is usually SMP in nature.
In STAGE II, the dysfunction changes to
dystrophy manifested by edema, hyperhidrosis, neurovascular instability with fluctuation
of livedo reticularis and cyanosis - causing change of temperature and color of the skin
in matter of minutes. The dystrophic changes also include bouts of hair loss, ridging,
dystrophic, brittle and discolored nails, skin rash, subcutaneous bleeding,
neurodermatitis, and ulcerative lesions. Due to the confusing clinical manifestations, the
patient may be accused of factitious self-mutilation and "Münchausen syndrome."
All these dystrophic changes may not be present at the same time nor in the same patient.
Careful history taking is important in this regard.
In STAGE III, the pain is usually no
longer SMP and is more likely a sympathetically independent pain(SIP). Atrophy in
different degrees is seen. Frequently, the atrophy is overshadowed by subcutaneous edema.
The complex regional pain and inflammation spread to other extremities in approximately
1/3 of CRPS patients. At stage II or III it is not at all uncommon for CRPS to spread to
other extremities. At times, it may become generalized. The generalized CRPS is an
infrequent late stage complication. It is accompanied by sympathetic dysfunction in all
four extremities as well as attacks of headache, vertigo, poor memory, and poor
concentration. The spread through paravertebral and midline sympathetic nerves may be
vertical, horizontal, or both. The original source of CRPS may sensitize the patient to
later develop CRPS in another remote part of the body triggered by a trivial injury. The
ubiquitous phenomenon of referred pain to remote areas (e.g., from foot or hand to spine)
should not be mistaken for the spread of CRPS.
At STAGE III, inflammation becomes more
problematic and release of neuropeptides from c-fiber terminals results in multiple
inflammatory and immune dysfunctions. The secondary release of substance P may damage mast
cells and destroy muscle cells and fibroblasts.
1. Failure of the immune system, reduction of helper
T-cell lymphocytes and elevation of killer T-cell lymphocytes.
2. Intractable hypertension changes to orthostatic
3. Intractable generalized edema involving the abdomen,
pelvis, lungs, and extremities.
4. Ulcerative skin lesions which may respond
to treatment with I.V. Mannitol, I.V. Immunoglobulin, and ACTH
treatments.Calcium channel blockers such as Nifedipine may be effective in
5. High risks of cancer and suicide are increased.
6. Multiple surgical procedures seem to be precipitating
factors for development of stage IV.
The stage IV is almost the flip side of
earlier stages, and points to exhaustion of autonomic and immune systems. Ganglion blocks
in this stage are useless and treatment should be aimed at improving the edema and the
failing immune system. Sympathetic ganglion blocks, alpha blockers, including Clonidine,
are contraindicated in stage IV due to hypotension. Instead, medications such as
Proamantin (midodrin) are helpful to correct the orthostatic hypotension.
STAGING CAN BE MISLEADING
Dogmatic reliance on staging is somewhat
artificial in nature. Each patient follows a different course. In children and teenagers,
the prognosis is excellent and stages need not develop with passage of time due to the
fact that their rich cerebral growth hormone, sex hormone and endorphin formation prevent
deterioration. The same logic applies to pregnant women. With early treatment, the disease
is frozen at stage one. Even patients suffering from stages II or III revert to stage I
with proper treatments. The reverse is true: unnecessary surgery, as an stressor can cause
rapid regression from stage I to III, as well as spreading the disease to other
The main goal of treatment is reversal of
the course, amelioration of suffering, return to work if at all possible, avoiding
surgical procedures, and improvement of quality of life. The key to success is early
diagnosis and early assertive treatment. Lack of proper understanding and proper diagnosis
leads to improper treatment with poor outcome. There is a desperate need for future
research in the treatment of CRPS. Delay in diagnosis is a factor in therapeutic failure.
According to Poplawski, et al, treatment, and its results, are hampered by delay in
diagnosis. Early diagnosis (up to 2 years) is essential for achieving the goal of
successful treatment results. Simple monotherapy with only nerve block, only Gabapentin,
or otherwise, is not sufficient for management of CRPS. Treatment should be
multidisciplinary and simultaneous: effective analgesia, proper antidepressants to prevent
pain and insomnia, physiotherapy, nerve blocks, proper diet, when indicated channel
blockers, and anticonvulsant therapy should be applied early and simultaneously.
Administration of piece-meal, minimal treatments is apt to fail.
Proper physical therapy is at the top of
the list for proper treatment. In this regard, in neuropathic pain, "no pain is all
gain" - not the opposite. Any activity that aggravates the neuropathic pain, should
be avoided. Distress of pain aggravates the sympathetic dysfunction. The patient is
instructed to frequently change positions. Usually, the major aggravators of the pain are
inactivity, distressful overdoing of exercise, or repetitive strain injury(RSI).
ICE AND HEAT THERAPY
Basbaum, and others have demonstrated
extensive lesions affecting large myelinated axons secondary to ice exposure. These
lesions are in the form of Valerian degeneration and segmental demyelination. Cold
injuries, frost bites and heat burns are common iatrogenic causes of peripheral
neuropathic pain. Heat or cold therapy with warm or cold water should not be mistaken for
freezing ice or boiling water exposure. Obviously, ice and hot water are damaging and
should be avoided. Temporary use of ice is the treatment of choice for acute but not
chronic pain. The repetitive application of ice in chronic pain patients causes cold skin
due to vasoconstriction followed by vasodilation usually lasting about 15 minutes. In our
study of 824 patients, 34 patients were exposed to ice treatment for less than 2 months
versus 226 patients exposed to ice treatment for more than 2 months. The group with over
two months exposure to ice 52% ended up in Stages III-IV versus 30% in the less than 2
month exposer to ice (P<0.001). Conversely, only 7% of the group with longer exposer
were in Stage I versus 38% in the group with shorter exposure(P<0.001).
If at all possible, the CRPS patient
should not be hospitalized unless it is absolutely necessary (such as for emergency
surgery). The usual hospital policy of enforced bed rest aggravates the CRPS. The
inactivity results in up regulation and activation of the sleeping nociceptors (deep
chemoreceptors in bone and muscle), with secondary deep, intolerable pain. The patient is
instructed to stay in bed no more than 8-9 hours a night and to try to walk before going
to bed. If sitting or laying down cause pain, the patient is instructed to get up and move
around. If walking or any type of exercise causes pain, the patient is to rest frequently.
Treatment of osteopenia requires ambulation and weight bearing. The use of wheelchair,
walker and other assistive devices should be discontinued.
Opioids play a major role in management
of pain and inflammation in peripheral and central nervous system. The endogenous
ligands-opioid peptides (endorphins) are expressed by resident immune cells in peripheral
tissues. Depriving the patient of proper pain medication can aggravate the immune system
dysfunction. The selection of proper opiates for treatment of CRPS is quite critical. Both
opioid agonists and mixed opioid agonist-antagonists have been used for treatment of pain
in such patients. Opiates are considered effective in treatment of neuropathic pain.
However, due to the complexity and multiple origins of the pain in CRPS, in some patients
the opioid agonists are not as effective. Morphine does not consistently reduce the
Morphine (0.1-1mg per kg IV) may increase the
localization threshold of lesioned limb pressure and may decrease the chronic pain score.
Morphine may decrease mechanoallodynia in the diabetic rat, but the effective doses have
to be quite high in the range of 2-4mg per kg IV which are too high for human application.
Long term use of opioid agonists has the potential of tolerance and dependence, impairment
of physical function, and depression. Yet, 83% of pain specialists have been
reported in 1992 to maintain chronic non-cancer pain patients on these medications. This
percentage has grown far higher since then: of 824 patients in this study, only 36 (4.3%)
had not receive long term opioid agonists therapy. Moreover, the present trend is for
poly- pharmacy of opioids in high doses. Such high doses exceed the optimal therapeutic
window for analgesia.
The therapeutic window refers to the fact
that opiates, similar to anticonvulsants, are most effective in their therapeutic range.
Above and below this window they are ineffective.
The opioid agonists such as morphine,
fentanyl, etc, have been found ineffective against the abnormally fluctuating reaction to
thermal allodynia (neurovascular instability), while retaining anti-nociceptive activity
against painful thermal stimuli (heat hyperalgesia). Long term use of Morphine suppresses
many specific functions of the immune system. Both acute and chronic application of
Morphine strongly suppress the T-cell immune functions. Morphine may interfere with the
development of antibody - antigen immune function. Due to the fact that many cells and
organs related to the immune system have shown opiate receptors, Morphine has the
potential of directly affecting and altering many immune processes. Morphine may affect
and suppress noxious stimulus-evoked fos protein-like immunoreactivity. Morphine and other
similar opioid agonists bind to opioid receptors in limbic system (temporal lobe),
affecting memory and mood.
Long term application of opioid agonists (e.g. morphine)
suppresses the formation of endorphins (Table 2).
Contrary to the common concept, large doses of
opiates usually disrupt the natural sleep pattern. It is true that opiates induce
excessive sedation in 24 hours. However, the nocturnal sleep pattern is interrupted every
few hours due to withdrawal phenomenon , leaving the patient tired and sleepy during the
day. The use of proper antidepressants and adherence to the above mentioned therapeutic
window help correct this problem.
Endorphins (enkephalins, dynorphin)
on other hormones
sex hormones, thyroid hormone
secretion of hormones
rain" effect b
flooding the brain temporarily leaving the brain devoid of hormones on withdrawal
brief with no significant withdrawal
with drastic withdrawal
warm extremities and normalized BP
during withdrawal: cold extremities, hypertension follows initial hypotension
more BZs resulting in tranquility
ENDO-BZs resulting in withdrawal: anxiety, agitation
on sex hormones and steroids
on limbic system
and normalize: better sleep, better memory, better judgment
and flood the system: insomnia amnesia, poor judgment
a. There are two
types of cells in the brain. The nerves, and the glial cells protecting the nerves. The
nerve secrete hormones. The glial cells dont. The brain is endocrine
gland-controlling behavior with secretion of hormones. Endorphins are powerful hormones
controlling pain. Whereas, exorphins (e.g., morphine, Demerol, codeine, and heroin)
require large doses (e.g. 10-20 nanogram or billionth of gram). The similarities between
endorphins and exorphins end at pain relief. Otherwise they act in a diametrically
b. Acid rain effect: alcohol as
well as exorphins flood the brain cells and hamper their ability to form the dirunal
hormones needed for alertness, sleep, tranquility, and antidepressant effects.
c. Apparently the exorphins block
the activation of adenylatecyclase, resulting in chronic tolerance.
Table 2*- From:Chronic Pain: Reflex Sympathetic Dystrophy:
Prevention and Management. CRC Press, Boca Raton, Florida 1993.
The above side effects of long-term
treatment with opioid agonists leave the door open to search for more effective opiates.
Buprenorphine, an opiate agonist-antagonist, is a strong analgesic without causing
dysphoria, or dependence. Sublingual Buprenorphine has been used successfully for
detoxification from Cocaine, Heroin and Methadone dependence. Buprenorphine is a Class V
narcotic in contrast to Morphine, Methadone or Fentanyl, which are Class II. Within the
proper therapeutic window, Buprenorphine (2-6mg/day) and Butorphanol (up to 14 mg/day),
act as opioid antagonists by occupying only mu and delta receptors. In higher than
therapeutic doses, they fill the Kappa receptors as well, changing said drugs to pure
opioid agonists and resulting in problems of rebound and tolerance. Within 2-6mg per day,
Buprenorphine occupies mu and delta opioid receptors, but kappa receptor is not occupied
and is capable of receiving endorphins. When all 3 opioid receptors are occupied,
endorphins cannot bind to them. Consequently, endorphins formation is ceased, leading to
dependence and tolerance.
The Harvard group and others have found
Buprenorphine to act as an antidepressant leading to "clinically striking improvement
in both subjective and objective measures of depression." This is in contrast to the
common depressive effect of opioid agonists.
Antidepressants, similar to Carbamazepine, block
the NMDA receptors and improve cell membrane function. Antidepressants are important in
improving the eventual recovery, immune system function, and reduction of mortality and
morbidity in chronic pain patients.
Antidepressants possess pure analgesic
properties. Examples: Doxepin (Zonalon) topical cream is an excellent topical analgesic
for neuropathic pain. The analgesic effect of tricyclics is reversed by Naloxone. The
analgesic property makes the therapeutic use of antidepressants essential for treatment of
Antidepressants with properly balanced serotonin
and norepinephrine (Nor Ep) reuptake inhibition provide maximal analgesia.
Antidepressants, similar to Morphine pump, provide naloxone -reversible endorphin type
pain relief . Such drugs as desipramine, imipramine and trazodone are superior to mainly
serotonin inhibitors such as Mitrazepine (Remeron) and fluoxetine. Remeron is
a good hypnotic, but in our patients it has shown no significant analgesic value. On the
other hand, Venlafaxine (Effexor) is a weak inhibitor of serotonin and a strong inhibitor
of nor ep reuptake-aggravating hypertension and sympathetic vasoconstriction by augmenting
norepinephrine function. Venlafaxine has a high profile of adverse drug interaction with
P450 and CYP2D6 Isoenzymes inhibitors (which comprise a long list of medications). It is
best not to use this drug in CRPS. Buproprion (Wellbutrin) aggravates seizure disorder.
Myoclonic jerks (see Movement Disorders) being a common complication of CRPS is aggravated
by this drug. Its use is contraindicated in CRPS.
Certain antidepressants such as tricyclics and
Trazodone, increase the synaptic serotonin and nor ep concentrations. This balanced
phenomenon provides effective analgesia, natural sleep, and antidepressant effect.
Trazodone provides analgesic effect in less than 24 hours in contrast with five to seven
days for the same effective result with tricyclics. Trazodone does not cause weight gain
when compared to amitriptyline(see below).
Of the tricyclics, Amitriptyline has been the
most widely used analgesic, but it has strong anticholinergic and sedative side effects,
and my cause paranoid and manic symptoms. More importantly, it has a tendency to cause
weight gain. In our study of 824 CRPS patients, 612 had already been tried on
Amitriptyline. In the first year, these patients gained an average of over 7kg, and, in
the following year, an additional 3.6kg. Trial of Desipramine or Trazodone did not cause
any significant weight gain. Weight gain in a CRPS patient who already has difficulty with
ambulation is quite harmful. In addition, tricyclics have adverse cholinergic and
muscarinic properties resulting in complications of orthostatic hypotension and ECG
Anticonvulsant treatment is helpful in CRPS for
two types of symptoms: 1. Spinal cord sensitization leading to myoclonic and akinetic
attacks, and 2. In patients who suffer from ephaptic or neuroma type of nerve damage
characterized by stabbing, electric shock, or jerking type of pain secondary to damage to
the nerve fibres. In such cases, anticonvulsants, especially Tegretol (non-generic),
Depakene, Gabapentin, and Klonopin (non-generic), are quite effective. The ephaptic,
causalgic CRPS II is best managed with combination of an effective anticonvulsant,
antidepressant, and analgesics.
Clonazepam is effective in control of myoclonic
jerks. Decades of experience with Klonopin and Tegretol in neurology have taught the
lesson that brand Klonopin and Tegretol are superior to their generic forms (Clonazepam
and Carbamazepine) in controlling epileptic seizures. The American Academy of Neurology
has recommended that generic antiepileptic drugs not be prescribed. Gabapentin (Neurontin)
which is an adjunctive anticonvulsant, provides relief for burning type of neuropathic
pain. Similar to Tegretol, Gabapentin is also neuroleptic. Carbamazepine, similar to
Mexiletine, is an effective sodium channel blocker. It is far better tolerated than
NONSTEROIDAL ANTI-INFLAMMATORY DRUGS
The inflammatory complications of CRPS
respond properly to NSAIDS. The beneficial effects of NSAIDS may be related to correcting
the immune inflammatory damages in nerve death-be it neuropathic inflammation of CRPS,
nerve death due to Alzheimer, or cerebrovascular disease (e.g., benefits from aspirin
therapy). In Alzheimer, immune factors such as "membrane attack complex" play a
role in nerve death-this may explain the benefits of NSAIDS. Cox inhibitors (e.g.,
Celebrex or Vioxx) are very helpful for pain relief and detoxification from opioid
The alpha-1 blockers Phenoxybenzamine (Dibenzyline) and
Hytrin (Terazocin) are effective systemic nerve blocking agents. Forty soldiers suffering
from CRPS type II were treated with phenoxybenzamine with excellent results, eliminating
the need for sympathectomy. Clonidine in oral, intrathecal, or cutaneous patch forms,
Clonidine is quite effective as an alpha-2 blocker. Application of Clonidine patch to the
area of original damage in the extremity may aggravate the pain. It is effective when
applied topically to paravertebral area in cervical or lumbar region corresponding to the
referred pain of sensory nerve roots. After completion of sympathetic nerve block
injection, application of Clonidine patch is a complementary treatment and may prevent the
need for further invasive nerve block. Another effective alpha-2 blocker, Yohimbine, is
not as potent as alpha-1 blockers.
MANAGEMENT OF INFLAMMATION AND EDEMA
There are two different forms of edema:
1. extracellular hypervolemia such as seen with congestive heart failure. This is a
pitting edema due to increased plasma volume and 2. intracellular edema such as seen with
glaucoma and pseudotumor cerebri. This form of edema causes intracellular cytoplasmic
water retention leading to cerebral edema and indurated edema associated with
neurovascular instability (fluctuating rusty, reddish, or pale discoloration). Normally,
the perineurium is impenetrable to water. In inflamed tissue the peripheral nerve
terminals increase by ("sprouting"). As a result, edema sensitizes the tissue to
opioid peptides and to pain. Standard diuretics such as HCTZ (Hydrochlorothiazide) or
Furosemide dehydrate and reduce the volume of the extracellular space. They are most
effective in cardiovascular diseases. The osmotic diuretics such as Mannitol,
chlordiazepoxide or magnesium salts reduce the intracellular volume and reduce neurogenic
edema. The edema of CRPS due to normal cell membrane dysfunction leads to rise in
intracellular Na+ and Ca++ . Correction of sodium potassium pump with the help of NMDA
inhibitors such as mexiletine, Carbamazepine, and MK801also help reduce edema.
Magnesium sulfate (Epsom salt), in oral, IV,
enema, or bathing form, effectively reduces the edema. It acts similar to calcium channel
blockers which are also effective in neuropathic pain and headache . For the complication
of Neurogenic Bladder and Interstitial Cystitis, Nifedipine may be helpful.
TREATMENT OF OSTEOPENIA
Osteopenia, usually transient, is a
common complication of CRPS. Most commonly, it affects the hip, foot, shoulder, and wrist
areas. Treatment consists of combination of weight bearing, mobilization, estrogen
replacement, biphosphonates, and diet rich in calcium (e.g., cabbage, and dairy products).
Mobilization is the most indispensable form of treatment.
HORMONE REPLACEMENT THERAPY
"Ovarian steroids produce measurable
cognitive effects after ovariectomy and during aging" (McEwen, et,al). Hormone
replacement improves the cerebral cognitive functions. Estrogen plays a major role in
formation of new excitatory synapses and NMDA regulation both in male and in female
formative brains. Realizing that female CRPS patients, regardless of age, have a tendency
for menopausal symptoms (hot flashes and excessive sweating), serum estrogen levels were
measured in 60 of these patients in this study. The serum estrogen(mid-cycle estradiol)
was in the 87 to 195 PG/ml range as compared to the normal 100 to 395 PG/ml range.
Estrogen replacement therapy improved the cognitive function and reduced the tendency for
hyperhydrosis on these patients.
In 43 patients who underwent infusion pump
therapy for CRPS , a more significant drop in serum estrogen and testosterone levels were
noted. Forty one patients required hormone replacement therapy which improved pain
reduction by an average of 1.7 (on a basis of 0-10), and reduced or cleared up the edema
of lower extremities.
Nerve blocks may be diagnostic,
therapeutic, or both. The two types of blocks are not identical and interchangeable. The
diagnostic nerve blocks with simple local anesthetic injection last a few hours to a few
days. Unfortunately diagnostic ganglion nerve blocks are commonly mistaken to be a form of
therapy. The meta - analysis studies by Kozin , Carr, et al, and Schott, have emphasized
such blocks are indistinguishable from placebo. Simple pain relief from blocks (SMP) does
not prove CRPS.
There are three main forms of diagnostic
1. Sympathetic ganglion block.
2. Local anesthetic nerve block.
3. Compression regional block.
Diagnostic nerve blocks are hampered by a
significant incidence of false-positive and false-negative results, even in the best
hands. The ganglion nerve blocks with local anesthetics are mainly diagnostic. The local
anesthetic effect doesnt last more than two hours to maximum 1- 14 days. Ganglion
nerve block should be complimented with therapeutic nerve blocks such as brachial plexus,
regional, and epidural nerve blocks. Where as ganglion nerve blocks temporally improve the
circulation and relieve the pain, they do not improve flexor spasm and deformity of the
hands and feet. The brachial plexus and regional blocks are more beneficial in correcting
such movement disorders.
The relief from epidural, paravertebral,
regional and brachial plexus blocks with combination of Bupivacaine and Prednisolone lasts
about 8-12 weeks. It is effective for somatic radiculopathy and for
neuropathic pain . Repeated stellate ganglion blocks can permanently damage the
sympathetic nerve cells, and result in "Virtual Sympathectomy." In addition,
such repetitive trauma may be complicated by migraine headaches.
PARAVERTEBRAL VS ZYGOAPOPHYSEAL TREATMENTS
According to Cheema, paravertebral nerve
block provides effective pain relief for both SMP and SIP. This is in contrast with
articular facet (zygoapophyseal) blocks (ZAB) which are fraught with painful joint
The paravertebral nerve blocks are technically
similar to zygoapophyseal blocks (ZAB) but should not be mistaken for each other. The ZAB
invades the zygoapophyseal (ZA) joint. Insertion of needle, or radiofrequency treatment of
ZA joint is traumatic to the joint, and has the potential of adding new pathology with
additional source of pain. Bogduks team, et al, have reported only 40% pain relief
in patients undergoing such ZA joint neurotomy. The paravertebral nerve block does not
invade any joint structure, and should not be mistaken for ZA injection or neurotomy.
In our series of 824 CRPS patients, 22
had undergone surgical sympathectomy with temporary partial relief of 6 days to 38 weeks
in 9 patients: up to 54 weeks in 10 patients: and no relief in 3. Chemical sympathectomy
was done (prior to referral to our medical center) on 13 patients with temporary relief of
3 days to 29 weeks in 4 patients, no relief in 5 , and rapid deterioration of CRPS in 4
patients. Surgical, radiofrequency and chemical or (neurolytic), sympathectomies, have
been applied in treatment of CRPS since 1916. Sympathectomy may provide temporary pain
relief, but after a few weeks to months it loses its effect. The success has been limited
to the series that have had short-term patient follow-ups of a few months after surgery.
Sympathectomy and application of neurolytic agents should be limited to patients with life
expectancies measured in weeks or months - e.g., cancer and end stage advanced occlusive
vascular disease patients. On the other hand, CRPS patients usually have 3 to 5 decades of
life expectancy ahead of them. They should not be exposed to aggravation of pain due to
sympathectomy. The sympathectomized patients developed post operative spread of CRPS in 12
of our 35 patients (37%). This high incidence of spread is in contrast to the 18%
incidence in the rest of 824 cases.
REASONS FOR SYMPATHECTOMY FAILURE
1. Laser Doppler-vascular studies have
revealed the temporary benefits of vasoconstrictor reflexes lasting no
more than four weeks. The neurovascular instability in late stage RSD is not expected to
respond to sympathectomy. Sympathectomy is aimed at achieving vasodilation. The
neurovascular instability refers to vacillation and instability of vasoconstrictive
2. At no time the sympathectomy can be
complete - unless it is done at the time of autopsy with complete removal of the chains of
3. Due to extensive interconnection of
chains of sympathetic ganglia, removal of a short chain of sympathetic ganglia is easily
compensated by rerouting of the sympathetic impulses through the horizontal and vertical
connections of sympathetic nerve fibres in paraspinal chain of sympathetic ganglia as well
as through the midline connection of sympathetic ganglia via the midline sympathetic plexi
such as cardiac plexus, superior mesenteric plexus, etc.
4. The wide dynamic range of spread of
pain impulse in adjacent levels of spinal cord causes the spread of pain to adjacent
levels above and below the sympathectomized area.
5. The alpha-1 adrenoreceptor in the
sympathectomized area are hypersensitive to the smallest concentrations of circulatory or
adjacent tissue noradrenaline.
6. By the time the sympathectomy is
undertaken, the disease is usually too advanced and in late stages. The pain is mainly SIP
and is expected to be non-responsive to ablation of the sympathetic ganglia. Sympathectomy
aggravates the already existing sympathetic dysfunction.
7. Chemical and radiofrequency
sympathectomy cause chemical damage and scarring of the adjacent tissues. This is
especially true in the case of alcohol or phenol chemical sympathectomy. The scar of such
chemicals becomes a new source of neuropathic pain. Chemical or radiofrequency ablation
surgical procedures are justifiable as an act of mercy for advanced cancer patients, but
CRPS patients usually have a few decades of life expectancy and cannot be expected to live
with the pain due to the scar of such destructive procedures for several years.
8. The beneficial effects of
sympathectomy are reported in surgical series of patients followed for a few months - as
short as one to four months. The follow up of up to 5 years reveals a high incidence of
recurrence of symptoms and signs after sympathectomy.
SURGERY AND AMPUTATION
Elective surgery for presumptive
conditions such as carpal tunnel, tarsal tunnel, and thoracic outlet syndrome (TOS)- in
spite of normal nerve conduction studies - only adds a new source of neuropathic pain at
the surgical scar. According to Cherington, et al , there is a tendency for unnecessary
TOS surgery, elective surgery is the strongest predictor (P<0.001) of poor treatment
outcome (Please see " Treatment Outcome").
According to Rowbotham, "amputation
is not to be recommend as pain therapy." All 11 patients in our series who underwent
amputation showed marked deterioration post-op. The surgical stump was the source of
multiple neuromas with sever CRPS II type of intractable pain. Amputation should be
avoided by all means due to its side effects of aggravation of pain and tendency for
spread of CRPS.
SURGERY AND IMMUNE
Surgical procedures in neuropathic pain
patients, in general, are sources of stress and produce characteristic neuro-endocrine and
metabolic responses, local inflammation, and can cause disturbance of immune system
The body responds in opposite direction
to surgery for somatic versus neuropathic pain. An acute appendicitis or cholecystitis
responds quite nicely to surgery. On the other hand, surgery in the area of the extremity
involved with neuropathic pain has the potential of aggravating the condition. Tissue
damage from the surgical procedures results in the local release of inflammatory
neurokines. This biochemical and cellular chain of events leads to up-regulation of the
immune system and nervous system activation by releasing Substance P, histamine,
serotonin, CGRP, bradykinin, prostaglandins, and other agents. This leads to a local
vasodilation response in the area of the surgical scar, increased capillary permeability,
and sensitization of the peripheral afferent nerve fibers resulting in allodynia and
hyperpathia. Surgery can cause suppression of immune function aggravating the
manifestations of neuropathic pain. Post-operatively, there is a tendency for dysfunction
of the lymphocytic role in immune regulation. This is manifested by a decrease in number
of T-cell lymphocytes and the function of the T-cell lymphocytes. The disturbance and
suppression of the immune system due to surgery enhances the malignant tumor growth and
metastasis . Surgery "results in a perturbation of nervous, endocrine and immune
system as well as their interregulatory mechanisms leading to compromised immunity."
This disturbance of immunity may manifest itself in skin ulcerations noted in 2 of 11
amputees referred to our clinic during 1990-1995 period. A similar case of amputee with
skin ulcers has been recently reported .
There are times that surgery is
unavoidable. Examples: tear of ligament or cartilage in the knee joint that would preclude
weight bearing. In such patients, epidural nerve block with a combination of Bupivacaine
and 20 to 30 mg Prednisolone before, during, and after surgery (with the help of epidural
catheter) helps reduce the side effects of surgical trauma. Another example is extensor
deformity of a finger causing useless hand which in turn aggravates CRPS.
Four potential variants influencing the
treatment outcome were studied:
1. Modes of therapy.
2. The nature of pathology.
3. Patients age.
4. Delay in diagnosis and treatment.
1. The type of treatment was the critical
predictor of outcome. For example, in patients younger than 21 years, the surgical
treatment reversed the beneficial prognostic value of youth (P<0.001). Moreover,
application of ice over 2 months (P<0.001), application of ice less than 2 months
(P<0.001), amputation (P=0.025), and sympathectomy, were the strong predictors of poor
2. The nature of pathology was an
accurate predictor of outcome. Examples: Chemical Sympathectomy with neurolytic agents
(alcohol, phenol, or other agents) was done in 13 patients. Chemical sympathectomy was the
third group of poor prognosis after venipuncture and amputation regardless of other risk
factors. One probable reason explaining such a poor prognosis may be the fact that the
lytic agent may infiltrate beyond the target area of injection.
The venipuncture CRPS group of 17
patients showed the worst prognosis and the most rapidly deteriorating course regardless
of age at the onset, any delay in diagnosis or mode of therapy. The venipuncture CRPS is
the purest form of selective sensory nerve injury in the wall of skin and subcutaneous
microvasculature. The poor prognosis may be due to lack of simultaneous somatic sensory
nerve stimulation which would over-shadow the neuropathic microvascular sensory nerve
3. In regard to age at onset, prognosis
was good among the 138 patients with onset at 2-22 years. The exception to this rule was
32 patients in this group who had undergone surgical procedures with poor results, and 5
other patients ages 3-21 years having been accused of being Münchausen syndrome, followed
by years of no treatment.
4. Delay in diagnosis: as Poplawski, et
al have emphasized, early diagnosis is important in the management of CRPS. However, if
the disease is not diagnosed early, it is of no value if the patient is treated with
stressors such as ice, surgery, or cast application. Additionally, if the original
pathology is severe and irreversible in nature, early diagnosis is of little value.
The group with the best prognosis was
typified by CRPS patients with mainly cold extremity treated with no surgery or ice. The
patients with permanently warm extremity, due to sympathetic nerve damage, fared poorly.
CRPS/RSD is a complex chronic pain
syndrome with four main features of hyperpathic/allodynic pain, vasomotor dysfunction and
flexor spasms, inflammation, and limbic system dysfunction. Elective surgery, and
amputation are at the top of the list of aggravating factors. CRPS is usually caused by a
minor injury, and requires proper evaluation and multi-disciplinary treatment addressing
the multifaceted pathological processes that evolve during its chronic course.
Patients age, the nature of pathology, and mode of therapy influence the outcome of
treatment. If at all possible, surgery, ice and cast applications should be avoided. There
is a desperate need for research in proper management of CRPS.
Acknowledgment: We are grateful to Mr.
Eric Phillips for his enormous contributions in organization of patient materials and
references in this review.
To obtain a full text copy of this
article please send your requests to:
H. Hooshmand, M.D.
Neurological Associates Pain Management Center
1255 37th Street, Suite B
Vero Beach, Florida 32960