PLASMA-EXCHANGE IN NEUROLOGICAL DISEASES

The objective of therapeutic plasma exchange(1) is to remove plasma fr om toxic substances, either autoantibody, alloantibody, immune complex , monoclonal protein or toxin. Plasma exchange can also act through re plenishment of a specific plasma factor. Pathophysiology was the first rationale for the use of plasma exchange. Its first indication was in deed the hyperviscosity syndrome,(1) on the single basis of pathogenes is. However, pathogenesis alone does not convince physicians to use su ch a costly and potentially unsafe treatment. Therefore, randomized cl inical trials have been conducted for the last 15 years to ascertain t he effectiveness and tolerance of plasma exchange, especially in neuro logical diseases. In myasthenia gravis, the recommended use of plasma exchange was mainly based on the theoretical argument of elimination o f anti-acetylcholine receptor antibodies. However, even if clinical im provement was observed after plasma exchange, this was also observed i n myasthenia gravis associated with no circulating antibodies. In cont rast, numerous randomized clinical trials have been initiated in the G ullain-Barre syndrome, although the pathogenesis of the disease is unk nown. Nevertheless, the large number of trials assessing plasma exchan ge in the last 15 years, especially in neurological. diseases, explain s the increased indications for plasma exchange in the national base o f the French register of plasmapheresis.(2) The demonstrated clinical benefit of plasma exchange through randomization may be an initial ste p in the understanding of disease. Plasma exchange probably does not s imply act through removal of toxic substances, but also, as high doses of intravenous immune globulins,(3) through immunomodulation. This co uld at least explain the competition and the complementarity of these two treatments. The objective of this paper is to present the main ind ications for plasma exchange in neurological diseases, complementing t he conclusions of the consensus conference that met in 1996.(4) We foc us on the assessments through randomized clinical trials, though uncon trolled studies in rare diseases are also reported. Copyright (C) 1996 Elsevier Science Ltd.