Complex Regional Pain Syndrome (CRPS)

19 July 2010

Complex Regional Pain Syndrome (CRPS) is a chronic pain and sensory condition.  Over the years, CRPS has been known by a number of different names including Sudecks atrophy, causalgia, reflex sympathetic dystrophy (RDS), shoulder-hand syndrome, post- traumatic dystrophy, and reflex neurovascular dystrophy.

Complex Regional Pain Syndrome is most frequently seen after trauma to an arm or leg.  Other inciting factors include recent surgery, infection, and fractures; all of which can lead to complex regional pain syndrome.

Complex regional pain syndrome can be further characterized as CRPS I and CRPS II.  CRPS 1 refers to when pain stems from an initial painful event that did not result in a known nerve injury; whereas CRPS 2 is from an identifiable traumatic event WITH known nerve injury. Each form of CRPS causes severe, unending pain that cannot be correlated with the extent of the injury.

Women are more likely to be affected than men and the disease is most common between the ages of 40-60.  Although the pain can be experiences anywhere in the body, most commonly it affects the distal upper and lower extremities.

Symptoms

Often beginning in the foot or the hand, CRPS eventually will begin to cause pain to the related arm or leg. Sometimes, CRPS will cause pain and spread to the opposite extremity.  Some theorize that CRPS is maintained by the sympathetic nervous system. Others have thought that CRPS may be linked to an immune response, which would cause the usual inflammatory response of swelling, warmth and a red, rash like representation in the painful area.

With CRPS, a patient will present two symptoms: allodynia and hyperalgesia. Allodynia can be simply explained as something causing pain that should not, for example, the sensation of your clothing touching your skin causing pain. Most people do not experience pain from that sensation – those with CRPS would. In hyperalgesia, a patient with CRPS responds severely to a painful experience, for example, the pulling off of a bandage will cause a momentary sensation of discomfort for those without CRPS. For a patient with CRPS, it would cause an excruciating pain sensation.

These abnormal reactions to normal sensations are thought to be caused by accelerated reactivity of neurons within the central nervous system, which in turn causes the normal reactions from the peripheral nervous system to be out of the ordinary. This accelerated reactivity causes an outside stimulus to cause extreme pain in conjunction with what should be a normal stimulus.

Some additional common symptoms include drastic changes in the temperature and color of the skin over the affected limb or body part, accompanied by severe burning pain, skin sensitivity, sweating, and swelling.

Three symptomatic stages have been described in the literature.  Staging is not important to clinical management; however it described the disease progression.

Stage I

Pain is more severe with a burning or aching sensation.  The affected area becomes edematous and can have temperature changes.

Stage II

Edematous tissue becomes indurated. Skin begins to atrophy and occasionally cyanotic.  Hair may fall out and the nails become brittle.

Stage III

Pain spreads proximally. Although it may diminish in intensity, pain remains a prominent feature. Skin further atrophies and becomes friable and shiny without edema. Late in the disease contractures may form.

Diagnosis

CRPS is a very multifaceted pain disorder, which can be very difficult to diagnose and treat.  Medical research has not yet determined the single cause of CRPS, but a number of precipitating factors are linked to the onset of this pain condition.  No one specific medical test or tool is currently available to diagnose CRPS with 100% specificity. Even if a combination of tests is performed, a physician can only state that the symptoms the patient is experiencing are indicative of CRPS.

The most important key to diagnosing CRPS is a detailed medical history and physical exam.  There are many guidelines and recommendations that describe potential diagnostic criteria. As there is no test to indicate CRPS, medical tests and exams should still be performed to eliminate other diagnoses. Blood testing can be done to rule out other inflammatory or rheumatologic conditions. Nerve tests should also be performed to be sure the patient does not have peripheral neuropathy or nerve entrapment issues.

Although there is not a solidified diagnostic criteria, common signs and symptoms have been described giving generalized diagnostic parameters for CRPS.  The 3 diagnostic parameters, each with a subcategory, are listed below:

• Pain
• Hyperesthesia
• Hyperalgesia
• Allodynia
• Signs
• Edema
• Color
• Mobility
• Motor change
• Range of motion
• Strength

Although diagnosis is largely done with physical exam and clinical history, other modalities are available in equivocal cases. Standard radiographic findings are normal in as many as 30% of patients.  However, they may show osteoporosis as soon as 3-5 weeks of onset.

For cases involving an upper extremity, a stellate ganglion block may aid the diagnostic process and may be therapeutic. If a patient sees no results with first-line minimally invasive or conservative treatments, Spinal Cord Stimulation may be indicated.