[Reflex sympathetic dystrophy syndrome. Contribution of magnetic resonance].

An attempt was made to establish Magnetic Resonance Imaging (MRI) diagnostic criteria for the study of the reflex sympathetic dystrophy syndrome (RSDS). Five patients with hip and knee pain were studied. The radiographic pattern was "positive" only in two patients, while radionuclide studies showed increased activity in the painful joint in all; only in three cases Computed Tomography was performed. In all patients MRI demonstrates the lesions and defines their extension. MRI allows a differential diagnosis between RSDS and other bone lesions such as osteonecrosis and tumors. The relation between anatomopathological findings of RSDS and MRI features is discussed. MRI proved to be a reliable technique in showing and characterizing RSDS better than radiographic examination (often "negative" in early phases), and radionuclide study (a sensitive but not specific technique).