Reflex sympathetic dystrophy in the foot: clinical and scintigraphic criteria

To establish strict clinical criteria for reflex sympathetic dystrophy (RSD) of the foot and to characterize any associated scintigraphic pattern, the authors performed three-phase radionuclide bone scanning in 51 patients prospectively referred because RSD was a diagnostic consideration. To establish sensitivity and specificity data, the cases of an additional 100 consecutive patients referred for a variety of foot problems were retrospectively reviewed. The authors defined RSD of the foot as a pain syndrome characterized by diffuse nonanatomic, often unrelenting pain; autonomic-vasomotor signs including warm or cool skin temperatures and moist-sweaty or dry-scaly skin; and a positive response to a lumbar sympathetic block. Patients with RSD have a characteristic delayed bone-scan pattern consisting of diffuse increased tracer throughout the foot, with juxta-articular accentuation of tracer uptake. Overall, sensitivity in this study was 100%; specificity, 80%; positive predictive value, 54%; and negative predictive value, 100%. False-positive images were obtained in patients with infection, diabetes, and chronic pain. Specificity was 66% in the subgroup of patients who underwent sympathetic block, with a positive-predictive value of 88%. There were no differences in scan pattern related to duration of symptoms prior to imaging.