There is not a specific test available for complex regional pain syndrome. It is primarily diagnosed through observation of the symptoms. However, thermography, sweat testing, x-rays, electrodiagnostics, and sympathetic blocks can be used to build up a picture of the disorder. Three phase bones scans have been thought of as one of the most specific diagnostic studies for RSD, but they are not very sensitive and therefore delay recognition of the disease. A delay in the diagnosis and/or treatment for this syndrome can result in severe physical and psychological problems. Early recognition and prompt treatment provide the greatest opportunity for recovery.

Abnormal sweating can be detected by several tests. A powder that changes color when exposed to sweat can be applied to the limbs; however, this method does not allow for quantification of sweating. Two quantitative tests that may be used are the resting sweat output test and the quantitative sudomotor axon reflex test. These quantitative sweat tests have been shown to correlate with clinical signs of CRPS.^[1]