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4 Articles in this Series
Complex Regional Pain Syndrome (CRPS): A Screening & Treatment Update
Facial Pain: Recognizing & Treating Trigeminal Neuralgia, Temporomandibular Disorders
Multiple Mini Interviews: The New Approach to Pain Fellow Recruitment
Neuropathic Pain: An Update on Practical Management Including Neurostimulation and Mechanism-Based Pharmacotherapy

Complex Regional Pain Syndrome (CRPS): A Screening & Treatment Update

An AAPM 2021 Meeting Highlight with Steven P. Stanos, DO, R. Norman Harden, MD, and Jeannie A. Sperry, PhD

Complex regional pain syndrome (CRPS), a complex form of chronic pain, usually affects an arm or a leg after an injury, stroke, heart attack or other issue, with the pain presenting out of proportion to the severity of the original injury. At a 2021 AAPM virtual annual meeting session, three experts focused on CRPS, formerly called reflex sympathetic dystrophy (RSD) and causalgia, to discuss diagnostic criteria, research, and the need for interdisciplinary treatment approaches.

CRPS is rare, with about 5 of every 100,000 people a year developing it.

CRPS: A Look Back at the IASP and Budapest Criteria

R. Norman Harden, MD, professor emeritus at Northwestern University, Chicago, discussed the long history of how physicians have tried to develop criteria for diagnosing CRPS. In 1994, a consensus group gathered by the International Association for the Study of Pain (IASP) agreed on diagnostic criteria and renaming the condition CRPS. Those criteria, while sensitive, were criticized by experts for not being specific enough. The team then developed a modified version of the diagnostic criteria. In 2003, a workshop of experts met in Budapest, Hungary, to study the matter, ultimately publishing their findings in 2007, demonstrating that the second version of the IASP criteria, or the so-called Budapest criteria, were better.

Before the formal validated criteria, said Dr. Harden, the norm was doctors who claimed: “I know it when I see it.” Such assessments were often based on seeing severe pain and autonomic dysfunction in patients. Unfortunately, many still take this approach, he noted, and that leads to ''diagnostic chaos.”

The current criteria are meant to be used as a screen in any clinic, without the need for equipment or special training, to make a CRPS diagnosis.

In updating the criteria, he said, experts often point to four factors – pain, vasomotor factors, edema, and signs and symptoms of the original trophic changes but also motor changes. (Motor changes were not included in the original IASP criteria.)

Using the Budapest criteria, experts found that when 2 of 4 sign categories were present as well as 3 of 4 symptom categories (see below), the sensitivity was 0.85 and the specificity was 0.69 for a clinical diagnosis of CRPS. If you find these, you make the clinical diagnosis, he told the AAPM audience.

CRPS symptoms include

  • positive sensory symptoms
  • vascular symptoms
  • edema or sweating
  • motor changes

CRPS signs include

  • positive sensory signs
  • vascular signs
  • edema and swelling abnormalities
  • motor or tropic changes

The updated criteria weeds out outlier diseases, added Dr. Harden. ''When we tried to use the Budapest criteria as an entry into research, I have to say all heck broke loose.” There have been several trials that have failed, most likely because CRPS is a multifactorial, multi-mechanism disease. So the treatments under study are not likely to produce results with a significant P value because the population studied has different mechanisms underlying the disease.

He said that the Budapest criteria should be for clinical screening purposes, and less so for research. “If you are going to be recruiting for research you need to identify what factor you are dealing with, and that should be the focus.”

Current CRPS Research: Clinically Relevant Subsets

Some patients with CRPS experience more motor issues, others more inflammatory disease. Dr. Harden explains that “We are developing a research process whereby we identify the subset, based on mechanisms.” The treatment then is studied on that subset.

As for quantifying the results, he mentioned fMRI, PET, SPECT, and quantitative telethermography.

By focusing on subsets individually, researchers can get to better research outcomes, ultimately finding better treatments, he said. For instance: with the subset of people with vasomotor changes, empirical treatments may include paravertebral sympathetic blocks, bier blocks, biofeedback warming, calcium channel blockers. These objective tests may ultimately become the gold standard for testing various treatment approaches for different subsets.

Dr. Harden and a team are currently developing lists of ''empirical pharmacotherapy” medications to be tried with various symptoms. Among the suggestions to date:

  • simple analgesics for mild to moderate pain
  • sedatives for insomnia
  • calcium channel blockers for profound vasomotor disturbance.

While focusing on the type of pain or symptom for treatment, he said, it's also wise to bring these patients into the interdisciplinary treatment arena.

Using Treatment Pillars to Manage CRPS Symptoms

In a second talk at AAPM, Steven Stanos, DO, medical director of pain medicine and services at Swedish Healthcare System, Seattle, focused on how clinicians can improve CRPS diagnostic accuracy, better assess and treat CRPS, and pay heed to psychological factors.

CRPS as a condition is overdiagnosed, on one hand, he said, but many still don't recognize the condition. Experts know it's not simply sympathetically mediated but rather a disease of the CNS, with altered cutaneous innervation, inflammatory factors, and other factors at play.

When it comes to making differential diagnoses, Dr. Stanos advises that clinicians consider neuropathic pain syndromes, inflammation, myofascial pain, vascular disease or psychiatric disorder.

When psychological factors are present, Jeannie A. Sperry, PhD, a psychologist and former Mayo Clinic consultant who was also on the AAPM panel, noted that these factors “are not predictive of who is going to develop CRPS.” People in pain may become fearful and avoid movement, for instance, and anxiety can occur as the condition persists.

Options for improving diagnosis and treatment include considering a base treatment on ''peripheral” or “central” mediated signs, using the CRPS prediction score and symptom severity score. Most patients probably have a combination, he noted.

For a quick screening tool, clinicians can turn to the CRPS Prediction Score. If a patient scores higher than a 4, that specificity suggests CRPS, said Dr. Stanos. Then, weigh in the Budapest criteria.

Also of use is the severity score. If you have a change in your score greater than 5, it may indicate a true clinical change, Dr. Stanos said, which is helpful to monitor. As another resource, the European Pain Federation Task Force compiled standards for CRPS diagnosis that lists 17 steps to improve diagnosis and treatment.

CRPS Treatment Pillars

Overall, think of four pillars of treatment when managing CRPS, Dr. Stanos said. These include:

  • physical and vocational rehab
  • psychiatric interventions
  • patient information and education to support self-management
  • pain relief with medications or procedures

However, Dr. Stanos added, despite current thinking that multidisciplinary treatment is best for CRPS, “treatment really remains inconsistent and rarely multidisciplinary.” 

Clinical Takeaways

After the talk, Dr. Stanos told PPM: “Physicians can improve their ability to better diagnose CRPS by being knowledgeable [about the condition] and using the Budapest Criteria to rule in or rule out CRPS.” Tools such as the CRPS Symptom Severity Scale and CRPS Prediction Score can also help better determine severity of symptoms and response to therapy.

Dr. Sperry added, “It's crucial for clinicians to remember that although CRPS is linked with psychiatric comorbidity such as anxiety, depression and PTSD, these psychological factor are sequelae, not predictors of the onset of CRPS.”


Disclosures: Dr. Harden reported consultant work for Biohaven and Takeda Pharmaceuticals, is on the Board of Governor's RSDSA, and chair of the International Research Consortium for CRPS. Dr. Stanos reportd consulting for Emergent Biosolutions, Hisamitsu, Lilly, Pfizer, and Vertex. Dr. Sperry reported no disclosures.

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