A prospective double-blind study of plasma exchange therapy for the acroparesthesia of Fabry's disease

During a study of the effect of plasma exchange on glycosphingolipid metabolism, a patient with Fabry's disease noted a dramatic improvement in his painful acroparesthesia. A controlled study was therefore undertaken. Observations were made of nerve conduction times, graded exercise testing, and psychometric evaluations during and after two planned series of three plasma exchanges: one a true plasma exchange and the other a "sham' control in which the patient received his own plasma. All observers and the patient were blinded and unanimously attributed beneficial results to the sham procedure. This study demonstrates the need for controlled studies in diseases prone to unpredictable exacerbation or spontaneous remission and outlines one possible technique of controlling studies involving plasma exchange.