Complex Regional Pain Syndrome (CRPS)

At the 2018 American Academy of Pain Management Annual Meeting, a panel discussed approaches to diagnosis and treatment of complex regional pain syndrome (CRPS). The speakers included:

• R. Norman Harden, MD – Northwestern University, Athens, GA
• Viviana Tawfik, MD, PhD – Stanford University School of Medicine

Complex regional pain syndrome, formerly known as reflex sympathetic dystrophy, is a form of chronic pain affecting the limbs often resulting from minor trauma or surgery. CRPS is a bio psycho social disease. There is a significant psychological component to it.

Diagnosis is based on signs of four types:

• Sensory (pain)
• Vasomotor (temperature)
• Sudomotor (edina/sweating)
• Motor (decreased range of motion, tremors)

There are about 50,000 new cases in the U.S. every year. Prevalence is twice as high in women. Many of the CRPS symptoms approximate acute inflammation. Patient trajectory is key to early diagnosis. If the patient is getting worse instead of better they should be evaluated for CRPS.

The pathology of CRPS is complex and could include nerve injury, oxidative stress, peripheral or central sensitization, altered sympathetic nervous symptom function, brain changes, and psychological factors.

Casting alone is a risk factor for CRPS. About half the patients who develop CRPS were immobilized after the injury. At cast removal, several symptoms of CRPS were present including hair growth and nail growth differences.

The presenter summarized an extensive study into causes of CRPS which are summarized as follows:

• The etiology of complex regional pain syndrome is likely to involve multiple mechanisms including sympathetic and immune dysfunction.
• Further clinically informed basic science research is ongoing to understand the mechanisms.
• New approaches in imaging can contribute to the evaluation of patients with CRPS or peripheral nerve injury.

There is now an internationally agreed upon diagnostic criteria for CRPS, but there continues to be debate over whether this is accurate. It is a very broad diagnosis. The thought is there could be multiple diseases being put under the umbrella of CRPS and there is a need to focus more on the specific symptoms presenting in the particular patient.

Physical therapy and occupational therapy are key to the treatment of CRPS. There are several studies that support this, the most recent is the TREND study done from 2005-2012 in the Netherlands.

As expected, there is extensive money being put into pharmaceutical research on the treatment of CRPS. Nothing is conclusive on this yet but steroids seem to be the most useful treatment.

The evidence base for CRPS treatment is challenging. The final conclusion of the presentation was that after over 30 years of research there is little in terms of widespread acceptance on the evidence-based treatment of this disease.