Complex regional pain syndrome

Last reviewed: 2 Sep 2023
Last updated: 01 Aug 2023



History and exam

Key diagnostic factors

  • history of trauma
  • history of immobilization
  • female sex
  • chronic pain
  • limb pain with radiation
  • allodynia and hyperalgesia
  • body scheme changes
  • edema
  • trophic skin and nail changes
  • erythema or bluish appearance
  • local sweating changes or sweating asymmetry
  • muscle weakness
More key diagnostic factors

Other diagnostic factors

  • tremors
  • dystonic posturing
  • contractures
  • sensory loss in glove and stocking distribution
  • local changes in hair growth
  • skin bullae
Other diagnostic factors

Risk factors

  • trauma
  • immobilization
  • female sex
More risk factors

Diagnostic investigations

1st investigations to order

  • no test required: diagnosis is clinical
More 1st investigations to order

Investigations to consider

  • electromyogram
  • nerve conduction studies with surface electrodes
  • punch skin biopsy
  • radiograph of affected limb
  • bone scintigraphy with technetium 99m
  • dual-energy x-ray absorptiometry (DXA)
  • quantitative CT scan
  • MRI
  • vascular studies
  • sympathetic nerve blocks
  • intravenous regional or selective anesthetic blocks
More investigations to consider

Emerging tests

  • autonomic testing

Treatment algorithm


early CRPS (within 6 months of onset)

chronic CRPS (>6 months since onset)



Anuj Aggarwal, MD

Clinical Assistant Professor

Anesthesiology, perioperative and pain medicine

Stanford University

Redwood City



AA declares that he has no competing interests.


Dr Anuj Aggarwal would like to gratefully acknowledge Dr Nicholas Shenker, Dr Gaurav Chhabra, and Dr Steven H. Horowitz, previous contributors to this topic.


NS is medical adviser to Cambridge Nutraceuticals with stock options. He has received consultancy fees from Roche to provide unrestricted sponsored educational meetings, and grants from Versus Arthritis, the National Institute for Health Research Clinical Research Network, and the Medical Research Council. NS is an author of references cited in this topic. GC has been sponsored by Medtronic, Boston Scientific, Abbott, Nevro, Stimwave, and Polar Medical for attending various conferences and cadaveric workshops relevant to pain medicine and neuromodulation. GC is an associate examiner for the European Society of Regional Anaesthesia & Pain Therapy European Diploma of Pain Medicine exam and is also the regional advisor for pain medicine for the South West Severn deanery. SHH declares that he has no competing interests.

Peer reviewers

Andre Tomasino, MD

Department of Neurological Surgery

Weill Cornell Medical College

New York-Presbyterian Hospital

New York



AT declares that he has no competing interests.

Ari Weinreb, MD, PhD

Associate Chief of Rheumatology

VA Greater Los Angeles Healthcare System

Associate Professor of Medicine

David Geffen School of Medicine


Los Angeles



AW declares that he has no competing interests.

Jonathan Berman, MBBS

Consultant in Pain Management and Anaesthesia

Pain Management Department

Royal National Orthopaedic Hospital NHS Trust




JB has been reimbursed by Pfizer for lectures given at Pfizer-sponsored meetings and courses.

  • Complex regional pain syndrome images
  • Differentials

    • Infection
    • Arterial compromise
    • Bone pathology
    More Differentials
  • Guidelines

    • Complex regional pain syndrome: practical diagnostic and treatment guidelines, 5th edition​
    • Complex regional pain syndrome: practical diagnostic and treatment guidelines, 5th edition
    More Guidelines
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