What are the diagnostic criteria for Complex Regional Pain Syndrome (CRPS)?

From the Guidelines

Complex Regional Pain Syndrome (CRPS) is diagnosed using the Budapest Criteria, which requires the presence of continuing pain disproportionate to any inciting event along with specific symptom categories. For a clinical diagnosis, patients must have at least one symptom in three of four categories and at least one sign in two of four categories. The four categories are:

• sensory (hyperesthesia, allodynia)
• vasomotor (temperature asymmetry, skin color changes)
• sudomotor/edema (sweating changes, edema)
• motor/trophic (decreased range of motion, weakness, tremor, dystonia, hair/nail/skin changes). Additionally, there should be no other diagnosis that better explains the symptoms. CRPS is typically divided into two types: Type I (without nerve injury) and Type II (with nerve injury) 1.

Early diagnosis is crucial for better outcomes, as CRPS can progress from acute to chronic stages with increasing severity of symptoms. The diagnosis is primarily clinical, though supporting tests like bone scans, thermography, or quantitative sensory testing may help rule out other conditions. Laboratory tests are generally not diagnostic but may help exclude other disorders. The condition often follows trauma or surgery to an extremity, with symptoms extending beyond the area of initial injury. According to a meta-analysis by Cappello et al 1, 3-phase bone scan has a pooled sensitivity, specificity, NPV, and positive predictive value (PPV) of 78%, 88%, 88%, and 84%, respectively, and may be useful to rule out disease. However, bone scintigraphy does have high specificity and can be used to rule out CRPS 1.

The Budapest Criteria should be used for the diagnosis of CRPS, and imaging tests such as bone scans may be used to support the diagnosis or rule out other conditions. It is essential to note that the diagnosis of CRPS is primarily clinical, and early diagnosis is crucial for better outcomes. A study by Schürmann et al 1 found that contrast-enhanced MRI has a sensitivity of 13% to 43% and a specificity of 78% to 98%, resulting in low PPV and moderate NPV, suggesting that MRI cannot be used as a screening test. In contrast, Schweitzer et al 1 demonstrated higher sensitivity (87%) and PPV (100%) for contrast-enhanced MRI.

The diagnostic criteria for CRPS include:

• Continuing pain disproportionate to any inciting event
• At least one symptom in three of four categories (sensory, vasomotor, sudomotor/edema, and motor/trophic)
• At least one sign in two of four categories
• No other diagnosis that better explains the symptoms. By following these criteria and using supporting tests when necessary, clinicians can accurately diagnose CRPS and provide appropriate treatment to improve patient outcomes.

From the Research

Diagnostic Criteria of CRPS

The diagnostic criteria for Complex Regional Pain Syndrome (CRPS) are not strictly defined, but several studies have attempted to establish guidelines for diagnosis.

• The Budapest criteria are widely used for diagnosing CRPS, but their application can be variable 2.
• A study published in 2025 found that the Budapest criteria had been assessed in only 26% of patients prior to evaluation, highlighting the need for more consistent application of these criteria 2.
• The International Association for the Study of Pain (IASP) published diagnostic criteria for CRPS in 1994, but these criteria have been found to have poor specificity, leading to problems of overdiagnosis 3.
• A 2007 study proposed new diagnostic criteria for CRPS, which were developed through an international consensus group in Budapest, Hungary 3.
• Magnetic Resonance Imaging (MRI) can be a useful diagnostic modality in the early stages of CRPS, particularly when clinical diagnosis is most difficult 4.

Challenges in Diagnosing CRPS

Diagnosing CRPS can be challenging due to its diverse clinical presentation and the lack of a gold standard for diagnosis.

• A 2016 study noted that symptoms of CRPS are often out of proportion to the initiating event and not limited to a single peripheral nerve 4.
• A 2025 study found that the inter-rater reliability for CRPS diagnosis and type ranged from minimal to moderate, highlighting the need for more consistent diagnostic practices 2.
• The study also found that potentially treatable peripheral nerve injuries should be addressed prior to CRPS diagnosis 2.

Diagnostic Tests and Procedures

Several diagnostic tests and procedures can be used to support a diagnosis of CRPS.

• MRI is one of the most useful diagnostic modalities in the early stages of CRPS 4.
• Sympathetic nerve blocks, such as stellate ganglion and lumbar sympathetic blocks, can be used as a diagnostic tool and as a treatment for CRPS 5.
• Other diagnostic tests, such as physical and occupational therapy evaluations, psychological evaluations, and pharmacologic management, can also be used to support a diagnosis of CRPS 6.