Complex Regional Pain Syndrome (CRPS) is a chronic condition marked by severe, persistent pain, often in a limb after injury or surgery. Diagnosing CRPS is challenging since no single test confirms it. Instead, healthcare providers use clinical evaluations and diagnostic exams to rule out other conditions and support a CRPS diagnosis. A multi-faceted approach is necessary, combining symptom analysis with imaging and physiological tests to build a comprehensive picture of the condition.
A thorough physical exam is the first step in diagnosing CRPS. Physicians assess the affected limb for changes in skin color, temperature, swelling, and abnormal sweating. They also evaluate muscle strength, joint function, and sensitivity to touch. A key indicator is allodynia, where a normally non-painful stimulus, such as light touch, causes discomfort. Another sign is hyperalgesia, an exaggerated response to pain.
Additional signs include decreased range of motion, skin texture changes, and abnormal nail or hair growth patterns. Doctors may also compare the affected limb to the unaffected one, noting differences in circulation or mobility. Because symptoms can evolve, repeated examinations may be necessary to track changes over time and confirm consistency with CRPS.
CRPS often leads to abnormal temperature regulation in the affected limb, making thermography a useful diagnostic tool. This non-invasive imaging test measures skin temperature differences between limbs. Infrared cameras capture heat patterns, revealing discrepancies that may indicate autonomic nervous system dysfunction. A temperature difference greater than 1°C can suggest CRPS, especially when combined with other clinical findings.
Thermography is particularly useful when symptoms fluctuate, as it can capture temporary changes in blood flow that might not be evident during a physical exam. Additionally, repeated thermographic assessments can help monitor disease progression and evaluate responses to treatment. Although thermography alone does not confirm the diagnosis, it provides useful supplementary evidence when considered alongside other tests.
A Triple-Phase Bone Scan is a nuclear imaging test that evaluates blood flow, bone metabolism, and inflammation. A small amount of radioactive tracer is injected into a vein, and images are taken over several hours. In CRPS cases, the scan often shows increased tracer uptake in the affected area, particularly in later stages.
This test is particularly beneficial in differentiating CRPS from other conditions like fractures, arthritis, or deep vein thrombosis. The three distinct phases of imaging provide insight into vascular changes, tissue damage, and abnormal bone activity. While not definitive, this test helps distinguish CRPS from other musculoskeletal disorders and is often used when physical exams and symptom evaluations yield inconclusive results.
MRI scans assess soft tissues, bones, and nerves in suspected CRPS cases. High-resolution images help identify signs of inflammation, muscle atrophy, and joint abnormalities. Though MRI findings are not exclusive to CRPS, they help rule out other conditions with similar symptoms, such as infections, arthritis, or nerve compression.
In some CRPS patients, MRI scans reveal bone marrow edema, a condition where excess fluid accumulates in the bone, causing pain and stiffness. This finding, while not unique to CRPS, adds to the diagnostic puzzle and supports a more accurate assessment when combined with clinical evaluation and other tests. Physicians may also use MRI to assess structural abnormalities that contribute to pain, ensuring a targeted treatment plan.
