Failure of MR imaging to detect reflex sympathetic dystrophy of the extremities

Reflex sympathetic dystrophy of the extremities is a disease with a wide spectrum of clinical manifestations. It is characterized by pain, hyperthermia, and cutaneous changes and has been linked to an abnormality of regional blood flow. The disease is associated with previous injury or trauma including surgery, but also has been found in association with myocardial infarctions and tumors. The final diagnosis can be made only on the basis of the clinical course, which is characterized either by regression without sequel or the appearance of aponeurotic and tendinous retractions including bony sclerosis in the affected region occurring over many months to years. The literature and our own results show that MR imaging has high sensitivity for diagnosing transient osteoporosis of the hip, which is generally thought to be a form of reflex sympathetic dystrophy. Therefore we investigated the usefulness of MR imaging for diagnosing sympathetic dystrophy of the extremities. Twenty-five patients underwent T1- and T2-weighted MR imaging of the affected body region. They were selected on the basis of the initial clinical findings and positive findings on scintigraphy, which is known to be a sensitive, but not very specific, imaging method for sympathetic dystrophy. The final diagnosis was established on the basis of the clinical course in 17 of the 25 patients. In 10 of these, findings on MR images were completely normal, in six the MR images showed only nonspecific soft-tissue changes or bone marrow sclerosis, and in one patient they showed changes in bone marrow signal. Of the remaining eight patients without a final diagnosis of sympathetic dystrophy, MR showed soft-tissue or bone marrow alterations in six. MR imaging appears to be of little value in establishing the diagnosis of sympathetic dystrophy, but it may improve diagnostic specificity when used in conjunction with scintigraphy.