Assessing and Diagnosing Complex Regional Pain Syndrome

Patients with Complex Regional Pain Syndrome (CRPS) might feel a hand doesn’t belong to them or that it’s grossly enlarged or out of place. If they close their eyes, they can’t exactly say where their hand is, said Andreas Goebel, PhD, FRCA, FFPMRCA, senior lecturer in pain medicine at Liverpool University, who spoke about recent advances and current thoughts on Complex Regional Pain Syndrome at the American College of Rheumatology/Association of Rheumatology Health Professionals 2012 annual meeting in Washington, DC.

Clinicians could do well to ask their patients whether they have these kinds of feelings, he advised. “People won’t necessarily tell you, because they’re afraid you’ll think they’re crazy,” he said.

Goebel suggests clinicians ask their patients whether they ever feel like this:

• If I don’t focus my attention on my painful limb, it would lie still, like a dead weight.
• My painful limb feels as though it is not part of the rest of my body.
• I need to focus all of my attention on my painful limb to make it move the way I want it to.
• My painful limb sometimes moves involuntarily, without my control.
• My painful limb feels dead to me.

CRPS can be tricky to diagnose, Goebel said. There are still no blood tests or radiologic tests. In the United Kingdom, rheumatologists, orthopedic surgeons, and pain physicians were among clinicians who have agreed to base clinical diagnoses on the Budapest Criteria, approved by the International Association for the Study of Pain.

All patients with CRPS have continuous pain, disproportionate to any inciting event.

It’s a disease of central sensitization, a molecular process in which a period of intense or repeated painful stimulation, which actually or potentially damages tissue, innocuous stimuli become painful and remain painful for a while even after the initial painful stimulation has subsided.

The criteria reference four categories: sensory, vasomotor, sudomotor/oedema, and motor/trophic. According to the guidance, the patient has at least one sign in two or more of the categories. The patient reports at least one symptom in three or more categories. And no other diagnosis can better explain the signs and symptoms.

In the sensory category, the most common sign is allodynia in response to light touch and/or temperature sensation and/or deep somatic pressure and/or joint movement and/or hyperalgesia to a pinprick.

The vasomotor category refers to temperature asymmetry and/or skin color changes and/or skin color asymmetry. The sudomotor/oedema category refers to oedema and/or sweating changes and/or sweating asymmetry. The motor/trophic classification refers to decreased range of motion and/or motor dysfunction including weakness, tremor, dystonia, and/or trophic changes to the hair, nails, or skin.

One issue with these criteria is that people often lose their initial color change or temperature change or swelling and they still have ongoing pain. “That shouldn’t be considered recovery” said Goebel. The pain is really what affects people’s quality of life most. They lose their Budapest diagnosis, and we’re not quite sure how to categorize those patients. One suggestion: CRPS NOS (not otherwise specified).

CRPS can be subdivided into CRPS I, which is much more common, and CRPS II, which is associated with damage to a major nerve.