Diagnosis of RSD is a complex process of clinical observations of signs and symptoms couples with objective tests that measure such things as body temperature, sweat output, bone density and response to sympathetic block. Unfortunately there is not single test that determines whether a person has Reflex Sympathetic Dystrophy and most tests rule out other diseases instead of specifically diagnosing RSD, causalgia or sympathetically maintained pain (SMP). Diagnosis of RSD, unfortunately, is not done through one simple test - such as a blood test. It is much more complex and involved than that relying on observation, neurologic examination, temperature measurements, bone scans, radiography, sometimes nerve blocks and more. As with many medical procedures, some are done to "rule out" other problems, rather than to definitively determine that a patient has RSD.
The purpose of this document is to give an overview of the types of tests used in determining whether a patient has RSD and references where you can find out more information about these tests and their effectiveness is diagnosing RSD. Please read the disclaimer for RSDNet.org and remember that you should talk to your doctor about any information that you may learn here or elsewhere.
Radiography
Conventional radiography, such as X-rays, is used to diagnose bony abnormalities, such as pathologic fractures seen in bony metastases, spine pathology like spondylolisthesis and spur formation, and bone tumors. Some soft tissue tumors and bowel abnormalities can also be seen. A CT scan is most often used to define bony abnormalities and MRI for soft-tissue pathology.
Bone Scintigraphy (Bone Scanning)
Bone scanning is the use of a radioactive compound to detect a number of bone lesions, including neoplastic, infectious, arthritic, traumatic, Paget's, and reflex sympathetic dystrophy. The radioactive compound accumulates in areas of increased bone growth or turnover. It is a very sensitive test for subtle bone abnormalities that may not show up on conventional radiographs.
Thermography
Thermography is a noninvasive way of looking at the body's thermal patterns. A normal thermal pattern is symmetric, from one side of the body to the other. Tissue pathology is associated with chemical and metabolic changes that can cause abnormal thermal patterns by altering vascularity. Certain pain syndromes, such as neuropathic, musculoskeletal, vascular, visceral, and cancer disorders, have a specific thermal pattern and can thus be diagnosed thermographically. Sympathetic dysfunction, as in reflex sympathetic dystrophy, is easy diagnosed by thermography, although the authors have not found it to be useful in the evaluation of patients with pain.
Thermal Sensory Testing
Various machines are now available that can measure the response to heat and cold pain, and determine noxious thresholds to hot and cold stimuli. Although currently at an experimental stage, these analyzers should become more frequently used in the near future as standards for assessing C- and A-delta fiber responses are obtained. (MGH)
Diagnostic Blocks
Diagnostic blocks may differentiate somatic from visceral pain and confirm the anatomic location of peripheral nerve pain and also define possible therapeutic approaches (e.g. the use of neuropathic medications or sympatholytic medications).
General Reading
This page was last updated on January 28, 1997.