Are toxic oxygen radicals involved in the pathogenesis of reflex sympathetic dystrophy?

A crossover study was performed for patients with RSD to evaluate the therapeutic efficacy of the hydroxyl radical scavenger DMSO. All patients were given DMSO locally 5 times a day during one week, and a placebo during one week. Before and after each treatment, subjective evaluation was performed by both the patient and the examinor as to clinical activity of RSD, and measurement was performed of the range of motion (ROM) of all joints in the affected extremity. DMSO was the most effective treatment as to improvement of ROM (p = 0.035) and as to overall improvement (p = 0.001). The efficacy of the hydroxyl radical scavenger DMSO indicates that RSD primarily involves an inflammatory process rather than a sympathetic reflex. As during the last 20 years no single report was published studying RSD in terms of inflammation, it is suggested that such studies are urgently needed to elucidate the real nature of RSD.