[Changes in clinical diagnostic criteria for multiple system atrophy]

Multiple system atrophy (MSA) is a clinical and pathological entity characterized by the variable combination of autonomic failure, parkinsonism, cerebellar and pyramidal signs and by cell loss with gliosis and oligodendroglial cytoplasmic inclusions in the nigrostriatal, olivopontocerebellar systems and the spinal cord. Beyond nosology there has been a need for reliable clinical diagnosis criteria for MSA. Such criteria should ideally combine good sensitivity and specificity to diagnose MSA at different stages and should be good predictors (high positive predictive value) of the pathological diagnosis. Difficulties encountered in establishing MSA clinical diagnosis criteria were, among others, the variable expression of the disease, the definition of autonomic failure, of the cerebellar syndrome and of the poor levodopa response of parkinsonism. Quinn in 1989 proposed 3 sets of criteria (revised in 1994) to diagnose "possible", "probable" and "definite" MSA. These criteria are quite simple and partially validated. More recently these criteria evolved towards consensus criteria in which autonomic failure had a more central position. The consensus conference, held in 1998, proposed a precise definition of the various clinical domains and the combination needed for the clinical diagnosis, as well as exclusion criteria. In this article, we review and comment the different criteria for the clinical diagnosis of MSA.