The Differential Diagnosis of RSD (CRPS 1) Vs Other Disorders

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The Differential Diagnosis of RSD (CRPS 1) Versus

Other Disorders

Reprinted from the American Academy of Pain Management

Newsletter, June,2000 Hendler, M.D., M.S.

Severe burning pain, with extreme sensitivity to

touch, was first reported by Weir- in the

1860's based on his experience with soldiers who had

received " high velocity missile " wounds during the

Civil War. (1) Ghostine reported similar findings in

combatants during the wars in Lebanon in the 1970's.

(2). However, most reports in the literature indicate

that Reflex Sympathetic Dystrophy (RSD) or Complex

Regional Pain Syndrome Type I (CRPS 1), can be caused

by minor injuries to susceptible individuals. These

injuries range from twisting an ankle, to striking the

back of the hand, to wearing a new pair of shoes. (3)

Obviously, the development of a disorder, that affects

an entire limb, based on minor trauma, is

disproportionate to the trauma, very often resulting

in accusations of psychosomatic disease, as espoused

by

Achoa.

(4) The patho-physiology of RSD (CRPS 1) suggests

that there is sensitization of the wide dynamic range

neurons in the spinal cord by altering the activity of

NMDA receptors (5). This produces the clinical

feature of allodynia. Allodynia is defined as a

painful response to a normally non-painful stimulus

(6). There are three types of allodynia. a) thermal,

chemical, and c) mechanical.

These can easily be tested by the Hendler Alcohol Drop

and Swipe Test (7). In this test, a physician squeezes

an alcohol swab so that a drop of alcohol lands on the

patient's affected area. If the patient immediately

withdraws the limb and complains of a burning pain,

the

physician has demonstrated thermal allodynia, i.e. a

painful response to the cooling effects of a drop of

alcohol on a limb. After two minutes, if there has

been no response to the thermal test, a patient may

begin

to experience burning pain in the affected limb. This

occurs as the fat soluble alcohol permeates the skin

and begins to chemically irritate the hypersensitive C

fibers, which conduct the message of pain. If the

patient then experiences pain, this demonstrates

chemical allodynia. Then, with the leftover alcohol

swab, the physician gently strokes the affected area.

If this produces pain, this clearly demonstrates

mechanical allodynia. In order to establish the

diagnosis of RSD (CRPS 1), Raja and

have reported that thermal allodynia is the essential

criteria (8). Hendler has reported chemical allodynia

(9). However, mechanical allodynia can be found in

many types of neuropathic pain, such as post herpetic

neuralgia, trigeminal neuralgia due to vascular

compression, nerve entrapment syndromes, and

radiculopathies (10).

The clinical manifestations of RSD (CRPS 1) are

varied. Wu has called this the chameleon disease,

since the symptoms change over time (11). Schwartzman

has described three stages, which are not temporal

stages,

but rather severity stages (12). In the first mild

stage, there is burning in the affected limb and the

sensation of coolness or heat. In the second stage,

swelling, and changes in hair growth, nail growth,

and color of the skin appear, with the limb appearing

dark purplish or blue, or sometimes red. In the third

stages, contractures, dystonic reactions, muscle

spasms, and other muscle disorders can be noted, in

association with the other symptoms.

Most importantly, the pain is circumfrential, meaning

that it encircles the entire affected hand or foot, or

arm or leg. It does not follow a discreet nerve

distribution, because if it does, the appropriate

diagnosis would be causalgia, or Complex Regional Pain

Syndrome Type II, nerve entrapment, or radiculopathy.

In an article recently submitted for publication,

Hendler found that 71% of the patients referred with

the diagnosis of RSD (CRPS 1) did not have it, but

rather had nerve entrapment syndromes. Of the

remaining 29% of the patients, only one patient had

pure CRPS I (RSD), while the remainder had a

combination of nerve entrapments, as well as CRPS I

(RSD).

Therefore, at a minimum, in order to establish the

diagnosis of CRPS I (RSD) , a patient should have a) a

bone scan, b)EMGINCV studies, c) somato-sensory evoked

potential or neurometer studies, d) a trial with

sympathetic blocks, e) a trial with peripheral nerve

blocks or root blocks (7).

While some authors have advocated the use of

thermography as a diagnostic tool, it is not specific

enough to lend credibility to the diagnosis of CRPS I

(RSD). In an article by Uematsu, Hendler, Long,

Hungerford, and Ono, reviewing 803 cases of patients

with EMG/NCV study findings versus RSD findings, the

authors found that patients clinically diagnosed with

Reflex Sympathetic Dystrophy also had abnormalities on

thermography. (13).

However, in 89% of the patients diagnosed with having

radiculopathies or nerve entrapment syndromes,

confirmed by positive EMG/NCV study findings, they

also had abnormal thermographies.

Therefore, the presence of a cold limb does not

necessarily establish the diagnosis of CRPS I (RSD).

Treatment for RSD is as varied as the disorder itself.

Early on, in the stage I process, patients may respond

to high doses of steroids, beginning at 80 mg of

Prednisone and tapering it at the rate of 10 mg a

day associated with physical therapy (14). However,

aggressive physical therapy alone, in the absence of

the steroid therapy, has not been documented as

efficacious.

Sympathetic blocks, of the lumbar plexus, for CRPS I

(RSD) of the leg, or stellate ganglion blocks, for

CRPS I (RSD) of the arms, both are a diagnostic

procedure, and can prove to be a treatment. This is

especially true if the disorder is being treated

during the stage I or stage 11 process. If there is a

progressive longer

positive response to the sympathetic block, than it is

conceivable that a series of six sympathetic blocks

administered over a two to four week period of time

may actually provide permanent pain relief.

However, if the blocks provide warming of the limb,

and 100% relief of the pain, but then a return of the

pain, even after a series of six to twelve blocks,

then the patient would be a candidate for a

sympathectomy

(15). An open, surgically performed sympathectomy, is

far preferable than a blind procedure, such as

injecting an ablating agent, such as phenol or radio

frequency lesions. Both of these latter mentioned

procedures are fraught with more potential

complications than the open surgical sympathectomy,

where there is direct visualization of the sympathetic

chain.

By the third stage, their wide dynamic range neurons

in the dorsal horn of the spinal cord have changed to

such a degree that the NMDA receptors become resistant

to treatment.

This loss of plasticity of the neuronal receptors in

the spinal cord results in long term, and even

permanent, CRPS I (RSD) in patients who have not been

properly diagnosed, nor adequately treated (16).

Unfortunately, at this stage, oral narcotics are of

little or no use, since the CRPS I (RSD), like

many other neuropathic pain states, is notoriously

resistant to the analgesic effect of mu 1 and mu 2

receptor site agonist drugs.

The only pharmacologic intervention of narcotic drugs

proven efficacious is the use of kappa-2 agonists,

and this research has only been conducted in rats

(17). By the time the patient reaches stage III,

the use of epidural stimulators, dorsal column

stimulators, or epidural morphine pumps using

morphine,

baclofen, clonidine, or SNX-111 (a conotoxin) seem to

be the only available treatments (18).

In summary, the most essential component of treating

CRPS I (RSD) is to establish an accurate

iagnosis,being certain that this really is the

disorder that you are going to treat. Once accurate

diagnosis has been

established, then the sequence of treatment modalities

should be tried, as early as possible in the course of

the disease. Delays in treatment may allow progression

of the disease, or the spread of the disease, to

the countralateral limb or the ipsilateral limb.

References:

Eliav, E., Herzberg, U., Caudle, RM. The kappa opioid

agonist GR89 696 blocks hyperalgesia and allodynia in

rat models of peripheral neuritis and neuropathy.

Pain, vol. 79, pp. 255-264, 1999.

Rauck, RI, Eisenach, JC, , K., Epidural

clonidine treatment for refractory reflex sympathetic

dystrophy, Anesthesiology, Vol. 79, 1163-9, 1993.

Copyright © 2000

Last modified: February 06, 2001

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