1. 2025;28;E287-E327Diagnostic Guidance for Chronic Complex Regional Pain Syndrome Type I and Type II from The American Society of Interventional Physicians (ASIPP)
   Guidelines
   Christopher Gharibo, MD, Miles Day, MD, Steve M. Aydin, DO, Alan D. Kaye, MD, PhD, Salahadin Abdi, MD, PhD, Sudhir Diwan, MD, Lisa V. Doan, MD, Danielle Feng, MD, Kris Ferguson, MD, Kirolos Georges, MD, Andrew Kaufman, MD, Nebojsa Nick Knezevic, MD, PhD, Sean Li, MD, Franzes A. Liongson, MD, Devi Nampiaparampil, MD, Annu Navani, MD, Mahendra Sanapati, MD, Michael E. Schatman, PhD, Amol Soin, MD, Peter S. Staats, MD, Giustino Varrassi, MD, PhD, Jing Wang, MD, PhD, and Laxmaiah Manchikanti, MD.

BACKGROUND: Complex Regional Pain Syndrome (CRPS) is a challenging and often disabling condition marked by persistent pain, most commonly in a limb following injury or surgery. It presents with a wide array of symptoms, including intense pain, swelling, alterations in skin color and temperature, motor dysfunction, and trophic changes such as skin and tissue atrophy. While the precise cause of CRPS is not fully understood, it is thought to stem from abnormal nervous system activity, leading to heightened pain sensitivity and inflammatory responses. A thorough understanding of CRPS is essential for accurate diagnosis, effective treatment, and enhancing patients’ quality of life.

Although attempts have been made to distinguish between acute and chronic CRPS, there are currently no established diagnostic criteria specific to chronic CRPS in medical literature.

OBJECTIVE: This ASIPP guidance document offers updated, evidence-based recommendations for the diagnosis and management of Chronic Complex Regional Pain Syndrome (CRPS), with a primary focus on introducing novel, time-based diagnostic criteria specific to the chronic phase. These proposed criteria address significant gaps in the current literature, where existing standards, such as the Budapest Criteria, do not sufficiently differentiate between the acute and chronic stages of the condition.

METHODS: An expert panel convened by the American Society of Interventional Pain Physicians (ASIPP) conducted a comprehensive literature review and employed a structured consensus process to develop recommendations. Acknowledging that the clinical and pathological characteristics of CRPS change significantly beyond 12 months, the panel proposed chronic-specific diagnostic criteria based on disease duration, clinical history, physical examination findings, and optional diagnostic tests. These draft criteria were refined through multidisciplinary input and expert consensus.

RESULTS: The diagnostic framework for chronic CRPS consists of four key components:
General Criteria – Require fulfillment of the Budapest Criteria for at least 12 months, continued recognition of CRPS as a diagnosis of exclusion, and differentiation from generalized nociplastic pain syndromes.
History-Based Criteria – Mandate the presence of at least three out of five specific historical features.
Physical Examination Criteria – Include asymmetric limb findings, sensory disturbances, and musculoskeletal changes.
Optional Diagnostic Testing – May involve assessments such as intraepidermal nerve fiber density (IENFD) and imaging evidence of regional bone demineralization.

This framework builds upon the Budapest Criteria by incorporating time-dependent features of chronic CRPS, including musculoskeletal dystrophy, neurogenic inflammation, and sympathetic dysfunction. Emerging objective tools—such as quantitative sensory testing (QST), skin biopsy for IENFD, functional MRI, and serum biomarkers of neuroinflammation—may further support diagnosis in complex or uncertain cases.

Treatment recommendations highlight a multimodal strategy that integrates physical rehabilitation, pharmacologic management of neuropathic pain, sympathetic nerve blocks, and advanced neuromodulation. Emphasis is placed on individualized care pathways tailored to disease stage and patient-specific characteristics.

CONCLUSIONS: This article presents the first structured, time-sensitive diagnostic criteria for chronic CRPS, aimed at improving diagnostic accuracy and informing treatment strategies. Adoption of these criteria may enhance clinical outcomes and promote further research into the natural history and pathophysiology of CRPS progression.

KEY WORDS: CRPS I and II, reflex sympathetic dystrophy, causalgia, Budapest Diagnostic Criteria, sympathetically mediated pain, sympathetic blocks