Voices in Pain Medicine: ASIPP Update: Diagnosing and Treating Chronic CRPS
Complex Regional Pain Syndrome (CRPS) remains one of the most challenging pain conditions encountered in clinical practice, characterized by disproportionate and persistent pain following injury or surgery. It manifests through a constellation of sensory, motor, autonomic, and trophic abnormalities that evolve over time. Traditionally, CRPS has been divided into two subtypes: Type I (formerly reflex sympathetic dystrophy), which occurs without identifiable nerve injury, and Type II (formerly causalgia), which is associated with a confirmed peripheral nerve lesion. While acute CRPS is relatively well-defined by the Budapest Criteria established by the International Association for the Study of Pain (IASP), the chronic phase has lacked clear diagnostic parameters. Recognizing this gap, the American Society of Interventional Pain Physicians (ASIPP) developed new evidence-based guidelines to delineate chronic CRPS as a distinct clinical entity. These guidelines aim to improve diagnostic accuracy, inform management decisions, and support the evolution of CRPS care across disciplines.
The ASIPP task force that produced the guidance included 24 multidisciplinary experts representing anesthesiology, pain medicine, neurology, psychiatry, epidemiology, and psychology. The process followed recognized standards for trustworthy guideline development established by the Institute of Medicine (IOM) and the AHRQ’s NEATS framework. No external or industry funding was involved. The resulting recommendations were peer-reviewed by the Pain Physician Journal and published in April, 2025.
The central purpose of these guidelines is to define time-dependent diagnostic features that can distinguish chronic CRPS from acute disease and other chronic pain syndromes. The panel noted that chronic CRPS, typically defined by symptoms persisting beyond 12 months, is characterized by irreversible neurobiological and structural changes. These include progressive muscle wasting, contractures, dystonia, joint stiffness, and trophic skin or nail alterations, often accompanied by cold, cyanotic extremities and altered sweating patterns. The acute inflammatory signs, such as erythema, edema, and warmth, commonly diminish as the disorder transitions to its chronic phase, where neurodegenerative and sympathetic dysfunction become dominant.
Despite the widespread use of the Budapest Criteria, the ASIPP panel concluded that these standards are optimized for diagnosing acute CRPS. The Budapest framework emphasizes pain disproportionate to an inciting event and requires both reported symptoms and observed signs across sensory, vasomotor, sudomotor, and motor/trophic domains. However, its dependence on early inflammatory indicators and the linkage to an inciting trauma limit its specificity for chronic cases. As a result, chronic CRPS is often misdiagnosed or confused with other nociplastic pain disorders such as fibromyalgia, chronic post-surgical pain, or peripheral neuropathies.
ASIPP proposed a four-part diagnostic framework that retains the Budapest foundation while integrating time-based and chronic-specific features. First, patients must continue to meet the Budapest Criteria for at least 12 months, and other causes of pain must be excluded. Second, clinicians should identify at least three of five characteristic historical features, including persistent regional pain, evolving functional decline, and documented fluctuations in skin color or temperature. Third, physical examination should reveal at least two categories of objective findings, such as sensory disturbance, motor weakness, or asymmetric trophic changes. Finally, optional diagnostic tests may provide confirmatory evidence—these include intraepidermal nerve fiber density (IENFD) analysis, imaging showing regional bone demineralization, and advanced tools such as quantitative sensory testing and thermography.
The ASIPP framework also highlights the potential utility of emerging biological and imaging biomarkers to support diagnosis, though these remain adjunctive rather than definitive. Chronic CRPS appears to involve ongoing immune dysregulation and neuroinflammation, reflected in elevated inflammatory mediators such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), mast cell tryptase, and certain microRNAs. Skin biopsies and experimental imaging modalities, including functional MRI and infrared thermography, have shown promise in distinguishing chronic from acute presentations by revealing patterns of nerve loss, altered sympathetic activity, and cortical reorganization.
A major theme in the ASIPP guidance is the importance of recognizing CRPS as an evolving condition rather than a static diagnosis. Over time, acute inflammatory pain can transform into chronic nociplastic pain, sustained by central sensitization and maladaptive motor control. This shift requires clinicians to modify diagnostic thinking and treatment strategies accordingly. The document underscores the risk of maintaining a CRPS label without verifying chronic-specific features, as this may obscure alternative or concurrent diagnoses. Conversely, premature dismissal of a chronic CRPS diagnosis may deprive patients of appropriate interventional or rehabilitative care.
The guideline also addresses the problem of diagnostic delay, noting that patients often experience an average of nearly four years before accurate identification. Such delays contribute to functional decline, psychological distress, and treatment resistance. Early recognition and documentation of disease progression from the acute to chronic phase are therefore essential for optimizing outcomes.
In terms of management, ASIPP recommends a multimodal and stage-adapted approach emphasizing rehabilitation, pharmacologic therapy, interventional procedures, and psychological support. Early and continuous physical therapy remains the cornerstone of treatment, preventing disuse and preserving mobility. Pharmacologic management should target the underlying pain mechanisms: anticonvulsants and antidepressants for neuropathic pain, bisphosphonates for bone demineralization, and short courses of corticosteroids or anti-inflammatory agents for persistent inflammation. Ketamine infusions and alpha-adrenergic blockers may be considered for refractory pain, while immunomodulatory therapies—such as TNF-α inhibitors, intravenous immunoglobulin, or IL-1 antagonists—show potential in selected cases with immune-mediated features.
For patients unresponsive to conservative therapies, interventional techniques such as sympathetic nerve blocks or neuromodulation (spinal cord or dorsal root ganglion stimulation) may provide substantial relief and functional improvement. Behavioral and psychological interventions are also emphasized, as chronic CRPS is frequently associated with anxiety, depression, and post-traumatic stress symptoms. Addressing these comorbidities is essential to comprehensive care.
Ultimately, the ASIPP guidelines represent a significant advance in the understanding and management of CRPS. By distinguishing chronic CRPS as a distinct, time-dependent condition, they encourage clinicians to apply more nuanced diagnostic criteria that reflect disease evolution and to integrate emerging objective measures into assessment.
These guidelines also carry broader implications for research and policy. Establishing consistent chronic-phase criteria lays the foundation for future clinical trials, facilitates longitudinal tracking of disease progression, and helps define more precise endpoints for therapeutic studies. As objective biomarkers mature and diagnostic technology advances, it is anticipated that CRPS classification will evolve toward a more biologically informed model.
In summary, the 2025 ASIPP Chronic CRPS Guidelines provide the first structured, time-sensitive diagnostic framework for this condition, complementing the Budapest Criteria while addressing its limitations in chronic disease. They reaffirm CRPS as a diagnosis of exclusion, emphasize the importance of duration, structural and sensory changes, and support multimodal, patient-specific management. Adoption of these recommendations will ideally improve diagnostic consistency, guide therapeutic decisions, and ultimately enhance quality of life for patients living with chronic CRPS.
Timothy R. Mason, MD
AAPM Resident Ambassador
Resident Physician, PGY-3
Physical Medicine & Rehabilitation, Northwestern Medicine Marianjoy
References
Gharibo C, Day M, Aydin SM, Kaye AD, Abdi S, Diwan S, Doan LV, Feng D, Ferguson K, Georges K, Kaufman A, Knezevic NN, Li S, Liongson FA, Nampiaparampil D, Navani A, Sanapati M, Schatman ME, Soin A, Staats PS, Varrassi G, Wang J, Manchikanti L. Diagnostic Guidance for Chronic Complex Regional Pain Syndrome Type I and Type II from The American Society of Interventional Physicians (ASIPP). Pain Physician. 2025 Jul;28(4):E287-E327. PMID: 40773629.
As part of our commitment to advancing pain care across disciplines, AAPM periodically highlights significant work from across the field. Articles written by our guest blog authors are their own and do not necessarily reflect those of their institutions or the American Academy of Pain Medicine.