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Current Research: identifying subtypes of crps

Each year, approximately 300,000 people worldwide are afflicted with Complex Regional Pain Syndrome (CRPS; also called Reflex Sympathetic Dystrophy or causalgia), a neuro-inflammatory disorder that occurs in response to physical trauma such as a severe sprain, bone fracture, crush injury or surgery. CRPS causes nerves to misfire, sending constant pain signals to the brain, even long after the original injury has healed. The resulting pain is chronic, intense, disabling, and disproportionate to the original injury. The level of pain is measured as one of the most severe on the McGill University Pain Scale.


CRPS is difficult to diagnose, and there is no known cure. It is life-altering, and negatively impacts daily activities, relationships, work and school. Yet, it remains one of the most widely under-recognized and misdiagnosed chronic pain conditions. Although significant strides have been made to better understand CRPS, more research must be done to fight this devastating disease.


Since 2015, we have made it our mission to find more effective diagnostic and treatment options. With over 100 individual members and 40 participating research sites, our members are international leaders in CRPS research, experienced and noted rising stars alike. By fostering collaboration and coordination between researchers on a global scale, together we can achieve more compelling and relevant research results.


In 2023, we have taken our research efforts to the next level.


Specifically, our current research strives to answer a primary question that may dramatically affect the development of treatment options: Do all patients experience the same signs and symptoms -- or does it vary by stage or group? Is CRPS a uniform phenomenon across individuals, or are there distinct subtypes and/or stages? In other words, why do treatments work for some, but not others?


Back in 2003, experts gathered in Budapest to make recommendations for CRPS protocols, the results of which were published as the “Budapest criteria”. Since then, the Budapest criteria has become the definitive standard by which clinicians diagnose and treat CRPS. The founders of our organization, R. Norman Harden and Stephen Bruehl, were instrumental in validating the criteria.


When it was originally established, the "Budapest criteria" was purposefully broad in its recommendations, and not designed for specific subtypes, stages or groups. This “umbrella” approach proved to be a vast improvement in CRPS research – but there’s more work to be done to develop more effective interventions.


Specifically, our current research focuses on developing the methodology to identify clinically significant subtypes of CRPS such as warm and cold CRPS; CRPS-Type I (without “major nerve damage”), CRPS-Type II (with “major nerve damage”); stage of remission; and others. Our research will also enable us to conduct the studies required to achieve statistically relevant results.

To make a tax-deductible donation to help further this research, please visit our Go Fund Me page. To learn more about our research, please contact us by emailing

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