Complex Regional Pain Syndrome (CRPS)
The three most prevalent chronic pain syndromes are:
- Temporomandibular joint disease (TMD) presenting as chronic myofascial pain
- Chronic pelvic pain syndrome (CPPS)
- Fibromyalgia (FM)
Each of these disorders is included in a broader list of prevalent conditions often referred to as the “functional syndromes.” Among the major prevalent disorders under this heading are chronic fatigue syndrome (CFS), irritable bowel syndrome (IBS), the migraine syndromes, functional dyspepsia, etc.
Unlike these others, however, complex regional pain syndrome (CRPS) is typically off the home office underwriter’s “radar screen.”
What is complex regional pain syndrome (CRPS)?
“Complex regional pain syndrome (CRPS) is a painful disorder that usually develops as a disproportionate consequence of trauma.”
George Groeneweg, et al.
Erasmus Medical Center
BMC Musculoskeletal Disorders
What are the two main types of CRPS?
CRPS I and CRPS II.
The distinction is that CRPS II patients have an obvious nerve lesion and those with CRPS I do not. [Baron]
What are old names used for CRPS?
- Reflex sympathetic dystrophy (RMD)
- Sudeck atrophy
What is the cause of CRPS?
“The cause of CRPS is unknown, and it is not clear what distinguishes patients who recover early from those who do not improve.”
Andreas Goebel, MD, PhD; et al
University of Liverpool Medical School, UK
Annals of Internal Medicine
CRPS is the result of pathological changes in nervous system processing of noxious, tactile and thermal information, and there is evidence that at least in some cases may be autoimmune in origin. [Jäing, Kohr]
CRPS is often associated with herpes zoster, where the term Sudeck atrophy/syndrome was previously used. [Berry]
How common is CRPS?
A recent population-based study pegged the incidence at 26 cases per 100,000 person years. CRPS is most common in females, ages 61-70. [de Mos]
What brings on CRPS?
The most common precipitating factor is trauma to the distal portion of an extremity. The trauma may result from fracture (#1 cause), dislocation, strain, sprain, contusion or as a postsurgical complication.
In some cases, spinal cord injury, stroke and, rarely, myocardial ischemia culminate in CRPS. [Baron, Wasner]
Does CRPS ever arise spontaneously, without an antecedent disease-related traumatic or psychological event?
Yes. [de Mos]
What type of pain is linked to CRPS?
The pain is neuropathic (nerve related), rather than inflammatory, nociceptive (overt tissue damage) or purely functional in nature. [Groeneweg]
What distinguishes the pain associated with CRPS?
The following features are associated with CRPS pain: [Groeneweg, Wasner]
- Intense and burning
- Asymmetric, affecting the distal portion of the involved limb
- Increases when the limb is in the dependent position
- Provoked by sensory disturbances such as light touch (allodynia)
- Disproportionately more severe than the pain associated with the initiating event (if any)
What other symptoms/findings are often present?
There is a wide range of symptoms and findings that may be present, including:
[Baron, Galer, Peterlin, van den Berg, Wasner and Backonja, Wasner and Heckmann]
- Weakness, impaired muscle strength
- Swelling, edema
- Abnormal nail and hair growth
- Hyperhidrosis (excessive sweating)
- Skin fibrosis
- Localized osteoporosis
- Abnormal vasodilation with skin warming in the early phase; then, vasoconstriction in later stage (CRPS I)
- Significant sleep disturbance is present in 80%
- Both migraine (3.6-fold) and chronic daily headache (2-fold) are more common in CRPS than in the general population
- Physiologic tremor is present in 50% of upper limb cases
- Menstrual cycles disorders are 5 times more common in women with CRPS I than in the general female population
What common condition is often mistaken for CRPS?
Repetitive strain injury. [Marinus]
Do any medications exacerbate the symptoms in CRPS?
Yes – ACE inhibitors used for high blood pressure, etc. [Borsook]
Do CRPS patients develop pains in other body areas?
Yes, in some but not all cases. Rarely, chronic widespread pain (CPW) and even fibromyalgia (FM) may be mistaken for CRPS. [Marinus]
How is CRPS I diagnosed?
It is a primarily a clinical diagnosis.
Some studies suggest that CRPS I is overdiagnosed. [Wasner]
Are any tests done in the context of making a CRPS diagnosis?
Pathological uptake on bone scintigraphy, localized to the fingers or toes, is indicative of CRPS I – but we need to be alert to the context in which this test is done because it is also used in both osteoporosis and primary/metastatic cancer.
Plain x-rays and MRI scans may be used as well.
Two further tests sometimes used in CRPS diagnosis are:
- QSART (quantitative sudomotor axon reflex test)
- Skin temperature measurements
Is there any association between psychological issues and CRPS?
Adverse life events have been convincingly linked to the onset of CRPS I…and we know adverse life events play a major role in the onset and chronicity of all chronic pain and other functional syndromes. [Beerthuizen]
Three studies have shown that CRPS is more prevalent in persons with posttraumatic stress disorder (PTSD) than in the general population. [Asmundson, Grande, Otis]
How is CRPS treated?
There is no one consistently successful treatment in CRPS.
[Cacchio, Groeneweg, Goebel, Hsu, Munts, Slobodin, van Rijn]
Medications that can be effective in some cases include:
- Bisphosphonates, especially pamidronate – used mainly to treat osteoporosis
- Tricyclic antidepressants – which are generally effective in neuropathic pain
- Anticonvulsants – especially gabapentin and others used in treating chronic neuropathic pain
- Tadalafil (and possibly other PDE-5 inhibitors such as sildenafil)
- Nitrates of the same type used to treat myocardial ischemia
- Opioids (when the pain is severe or unresponsive to other Rx)
- Botulin toxin
- Intravenous ketamine
- Intravenous immunoglobulin G
- Intrathecal methylprednisolone, glycine or baclofen
- Epidural clonidine injection
Other therapies include:
- Local anesthetic blockade
- Spinal cord and peripheral nerve stimulation
- So-called “mirror therapy” is prevalent in post-stroke CRPS
Surgical treatment of lower extremity CRPS is often successful, with significant reduction in pain in 85% of cases in one series. [Dellon]
When the patient is responsive to treatment early on, the course is much more likely to be favorable. Once the syndrome has been present for an extended period, treatment is relatively ineffective. [Goebel]
What is the prognosis in CRPS?
Patients who improve significantly within 6 months of onset of treatment often have a favorable outcome.
Conversely, the far more common scenario – where the symptoms are only partially manageable or are wholly unresponsive to Rx – tends to be associated with long-term consequences affecting both quality of life and capacity to sustain gainful employment. [Goebel]
Patients who have an innate fear of injury are at greater risk for disability, as are those with heightened sensitivity to pain. [Groeneweg]
In a series of 102 patients followed for 6 years, de Mos and Huygen reported that:
- 16% had progressive CRPS involving wider areas of the body.
- 31% could not work.
- Those with upper extremity involvement had a worse outcome than where symptoms were confined to the lower extremities.
In another study, Vogel found that after 5 years, 2/3rd of CRPS-I patients with upper extremity manifestations continued to have significant pain and sustained major deterioration in functioning of the affected hand.
In a follow-up study of 656 patients diagnosed with CRPS for at least 12 months, the extent of symptoms was fully developed within one year, no subjects had spontaneous remissions and pain symptoms were largely refractory to medical or other treatments. [Schwartzman]
Is the morbidity prognosis unfavorable with CRPS?
It is for those who have symptoms at least 6+ months. The substantial majority of these cases tend to be chronic and result in significant disability.
Therefore, the few cases likely to be considered for long-term disability insurance would be those:
- Affecting a lower extremity
- Highly responsive to treatment within a few months of onset
- Fee of psychological or other significant comorbidities
- And, where there was no significant loss of time from work
Would a rider on the affected limb be sufficient to cover the risk in health underwriting?
No – because of the high prevalence of comorbidities and the risk of developing pain at other sites over time
CRPS does not appear to be a satisfactory health insurance risk in the vast majority of cases.
Are there any mortality implications with CRPS?
Only if one or more of the following are present:
- Serious underlying cause (stroke, cancer) known or suspected
- Paralysis or other significant impediment to ambulation
- Major psychiatric comorbidity, especially with cases with protracted disability
- Notable risks associated with potential future treatment – mainly high-dose/long term use of opioids, steroids, etc.
Note: there are 2 courses in our 2010 Continuing Education Program which address more prevalent chronic pain disorders, including an overall underwriting approach to chronic pain and underwriting-salient aspects of neuropathic pain, low back pain and three prevalent chronic pain syndromes: temporomandibular joint disease (TDM), chronic pelvic pain syndrome (CPPS) and fibromyalgia (FM).
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