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Last reviewed: 18 Mar 2025
Last updated: 01 Aug 2023

Summary

Definition

History and exam

Key diagnostic factors

  • presence of risk factors
  • chronic pain
  • limb pain with radiation
  • allodynia and hyperalgesia
  • body scheme changes
  • oedema
  • trophic skin and nail changes
  • erythema or bluish appearance
  • local sweating changes or sweating asymmetry
  • muscle weakness

Other diagnostic factors

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

Risk factors

  • trauma
  • immobilisation
  • female sex

Diagnostic investigations

1st investigations to order

  • no test required: diagnosis is clinical

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 anaesthetic blocks

Treatment algorithm

Contributors

Authors

Anuj Aggarwal, MD

Clinical Assistant Professor

Anesthesiology, perioperative and pain medicine

Stanford University

Redwood City

CA

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

NY

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

CA

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

UK

Disclosures

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

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