Laboratory Studies

A single, reliable, sensitive, and specific diagnostic test for complex regional pain syndrome (CRPS) is not available.

Quantitative sensory testing and quantitative sudomotor axon reflex test (QSART) may be performed to look for sensory and sweating abnormalities.^[37]

And as noted above, experts agree that diagnostic studies are not necessary to make the diagnosis.^{[29, 30]}

Imaging Studies

Although not required for diagnosis, these studies have been advocated for a variety of reasons.

Three-phase bone scan and gadolinium magnetic resonance imaging (MRI) have been used to diagnose and stage the disease.
Standard radiographic findings are normal in as many as 30% of patients. However, they may show osteoporosis as soon as 3-5 weeks of onset.
Laser Doppler flow studies have been used to monitor background vasomotor control.
A cold pressor test performed in conjunction with thermographic imaging observes vasoconstrictor response.
Functional MRI (fMRI) has been used to demonstrate that allodynic stimulation produces objective findings.^[37]
Magnetic resonance neurography (MRN) can be used to evaluate specific areas of nerve damage.
Structural MRI may be useful for the measurement of gray matter volume, which was directly correlated to pain intensity in one study^[38]
Triple-phase bone scans with dye can evaluate excess bone resorption

Procedures

Some authors believe that the best diagnostic approach for complex regional pain syndrome (CRPS) involves use of differential neural blockade. In those with sympathetically mediated pain (as opposed to those whose pain is sympathetically independent), response to neural blockade may help guide medical therapy.

For cases involving an upper extremity, a stellate ganglion block may aid the diagnostic process and may be therapeutic. However, failure to relieve pain does not eliminate the diagnosis.^{[5, 33]}
Differential blockade has been performed using Bier blocks with a variety of agents, including local anesthetics, bretylium, steroids, ketorolac, reserpine, and guanethidine and clonidine.^{[33, 39]}
The rationale for selective neural blockade is to interrupt stimulation to the sympathetic nervous system. Again, this is effective only in those whose pain is sympathetically dependent.^[33]

Treatment & Management

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Media Gallery

Updated IASP diagnostic guidelines for CRPS.

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Author

Marcella L Ruffo, MD Resident Physician, Department of Emergency Medicine, University of Kentucky College of Medicine

Marcella L Ruffo, MD is a member of the following medical societies: American College of Emergency Physicians, American College of Physicians, American Medical Association, Emergency Medicine Residents' Association, Palm Beach County Medical Society

Disclosure: Nothing to disclose.

Coauthor(s)

Christopher I Doty, MD, MAAEM, FAAEM, FACEP Tenured Professor of Emergency Medicine, University of Kentucky College of Medicine; Vice Chair of Education, Department of Emergency Medicine, University of Kentucky Chandler Medical Center

Christopher I Doty, MD, MAAEM, FAAEM, FACEP is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, Council of Residency Directors in Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Andrew K Chang, MD, MS Vincent P Verdile, MD, Endowed Chair in Emergency Medicine, Professor of Emergency Medicine, Vice Chair of Research and Academic Affairs, Albany Medical College; Associate Professor of Clinical Emergency Medicine, Albert Einstein College of Medicine; Attending Physician, Department of Emergency Medicine, Montefiore Medical Center

Andrew K Chang, MD, MS is a member of the following medical societies: American Academy of Emergency Medicine, American Academy of Neurology, American Academy of Pain Medicine, American College of Emergency Physicians, American Geriatrics Society, American Pain Society, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Additional Contributors

J Stephen Huff, MD, FACEP Professor of Emergency Medicine and Neurology, Department of Emergency Medicine, University of Virginia School of Medicine

J Stephen Huff, MD, FACEP is a member of the following medical societies: American Academy of Neurology, American College of Emergency Physicians, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Steven J Parrillo, DO, FACOEP, FACEP Clinical Adjunct Professor, Medical Director and Faculty, Disaster Medicine and Management Masters Program, Philadelphia University College of Health Sciences; Associate Professor, Clinical and Educational Scholarship Track, Jefferson Medical College of Thomas Jefferson University; Director, Division of EMS and Disaster Medicine, Albert Einstein Healthcare Network

Steven J Parrillo, DO, FACOEP, FACEP is a member of the following medical societies: American College of Emergency Physicians, American College of Osteopathic Emergency Physicians, American Osteopathic Association, World Association for Disaster and Emergency Medicine

Disclosure: Nothing to disclose.