Complex regional pain syndrome

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 22 Jun 2025

Last updated: 20 Nov 2024

Complex regional pain syndrome (CRPS) is prolonged pain, disproportionate to the initiating event, most frequently following minor trauma and most commonly affecting the distal aspect of an extremity.

Pain is often described as spontaneous, burning, lancinating, sharp, shooting, or electric. It characteristically develops dull, boring, and aching qualities with chronicity. Allodynia and hyperalgesia are almost always present.

Local edema, erythema, sweating abnormalities, and trophic skin and nail changes are often, but not always, present.

The affected extremity is often held immobile, and this can be associated with dystonia, focal weakness, and contractures.

Diagnosis is clinical. No specific tests are diagnostic; investigations may be useful to support the diagnosis or rule out alternative pathology.

The treatment goal is functional restoration of a limb by using adequate pain management techniques, with patient education, physical therapies, pharmacotherapy, and appropriate psychological techniques tailored to the individual patient. Interventional therapies may be considered for chronic CRPS when other treatments have failed to provide sufficient relief to allow physical therapy and functional rehabilitation.

Definition

Complex regional pain syndrome (CRPS) is defined as continuing (spontaneous and/or evoked) regional pain that is out of proportion to the severity of the inciting event and beyond the normal time frame expected following the event. The pain is usually regional (not in a specific nerve territory or dermatome) and has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings with variable progression over time.

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

Full details

Other diagnostic factors

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

Full details

Risk factors

trauma
immobilization
female sex

Full details

Diagnostic tests

1st tests to order

no test required: diagnosis is clinical

Full details

Tests 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

Full details

Emerging tests

autonomic testing

Treatment algorithm

ONGOING

early CRPS (within 6 months of onset)

chronic CRPS (>6 months since onset)

Contributors

Authors

Anuj Aggarwal, MD

Clinical Assistant Professor

Anesthesiology, perioperative and pain medicine

Stanford University

Redwood City

Disclosures

AA declares that he has no competing interests.

Acknowledgements

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

Disclosures

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

Disclosures

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

UCLA

Los Angeles

Disclosures

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

Middlesex

Disclosures

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

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

Merskey H, Bogduk N, eds. Classification of chronic pain: descriptions of chronic pain syndromes and definitions of pain terms. 2nd ed. Task force on Taxonomy of the International Association for the Study of Pain. Seattle, WA: IASP Press; 1994:39-43.

Goebel A, Birklein F, Brunner F, et al. The Valencia consensus-based adaptation of the IASP complex regional pain syndrome diagnostic criteria. Pain. 2021 Sep 1;162(9):2346-8.Full text Abstract

Goebel A, Barker C, Birklein F, et al. Standards for the diagnosis and management of complex regional pain syndrome: results of a European Pain Federation task force. Eur J Pain. 2019 Apr;23(4):641-51.Full text Abstract

Harden RN, McCabe CS, Goebel A, et al. Complex regional pain syndrome: practical diagnostic and treatment guidelines, 5th Edition. Pain Med. 2022 Jun 10;23(suppl 1):S1-53.Full text Abstract

Cruccu G, Aziz TZ, Garcia-Larrea L, et al. European Federation of Neurological Societies (EFNS) guidelines on neurostimulation therapy for neuropathic pain. Eur J Neurol. 2007 Sep;14(9):952-70.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

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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Complex regional pain syndrome

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Emerging tests

Treatment algorithm

early CRPS (within 6 months of onset)

chronic CRPS (>6 months since onset)

Contributors

Authors

Anuj Aggarwal, MD

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Andre Tomasino, MD

Disclosures

Ari Weinreb, MD, PhD

Disclosures

Jonathan Berman, MBBS

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice