Obtaining a CRPS diagnosis can be very difficult because there is no one specific test to confirm CRPS and identify the injured nerve. Symptoms may also fluctuate periodically, which complicates the diagnosis.
Diagnosis is principally based on a detailed examination and an extensive patient history taken by a qualified physician such as a neurologist, orthopedist, or plastic surgeon familiar with CRPS and the normal patterns of sensory nerve anatomy.
With CRPS in a limb or multiple limbs, having a patient draw the outline of where their abnormal skin sensations begin can help reveal the location of a damaged nerve. Patients may also note abnormal growth of hair or nails in the affected limb.
Thermography, using an accurate non-contact infrared heat scanner, can also be very useful since the affected limb typically has a significantly different skin temperature than the opposing limb.
Budapest Criteria for Diagnosis
The Budapest Criteria, outlined in 2004, is currently still the principal guide used to diagnose CRPS (but could use some updating).
The diagnostic criteria include:
1. Continuing pain which is disproportionate to the inciting initial injury
2. Must show at least one of the symptoms in three out of the four following categories:
- Reports of hyperalgesia (disproportionate pain with pinprick) and/or allodynia (severe pain with a light touch) on the affected area
- Vascular changes resulting in temperature asymmetry and/or skin color changes
- Edema (swelling) and sweating changes in the affected area
- Decreased range of motion of the affected limb.
Other less useful studies may be conducted in order to rule out other causes but are not specific to CRPS.
- Nerve conduction studies may detect some but not all CRPS-associated nerve injuries (many injuries involve tiny nerve branches that cannot be detected this way).
- Imaging nerves by ultrasound or magnetic resonance imaging (MRI), also called magnetic resonance neurography (MRN), sometimes reveals underlying nerve damage. Characteristic bone and bone marrow abnormalities on MRI may help identify the injured nerve.
- Triple-phase bone scans (using a dye) may demonstrate later-stage CRPS-associated excess bone resorption (the normal breakdown and absorption of bone tissue back into the body), which can help with diagnosis and localization.
Very Important: CRPS is more likely to improve over time when diagnosed and treated early.
Therefore, it is critical to find a qualified medical practitioner soon after symptoms begin to appear. If you suspect you may have CRPS, don’t hesitate to get another opinion if your current practitioner dismisses your concerns. Prognosis and diagnosis are both easiest early in the disorder.