Interrupting the sympathetic outflow in causalgia and reflex sympathetic dystrophy

Causalgia and reflex sympathetic dystrophy are poorly understood disorders that most commonly follow trauma to a limb, although they are also seen in other medical conditions. Patients typically develop chronic burning pain, together with various combinations of sensory disturbances, swelling, and vasomotor, sudomotor, and trophic changes.1-3 Traditionally, the pain is treated by interrupting the sympathetic supply to the painful area. Is this an effective approach? Periarterial sympathectomy was first used to treat causalgia, in which, by definition, major nerve injury occurs. Various forms of surgical sympathectomy have subsequently been carried out, 3 4 especially during war time, when controlled trials were not feasible, and so whether surgery was truly effective will never be known. Open surgical sympathectomy to relieve pain in causalgia and related conditions is rarely recommended now, not least because less invasive procedures—including endoscopic sympathectomy and percutaneous radiofrequency lesioning of the sympathetic trunk—have been developed, although critical evaluation of efficacy is awaited.4 For several decades, …