[Multiple system atrophy with Lewy bodies].
The term multiple system atrophy has been used to define a unique sporadic neurodegenerative disease, usually occurring in midlife, pathologically characterized by degeneration of the nigro-striato-pallidal and olivo-ponto-cerebellar systems and autonomic neurons of the spinal cord, and by the presence of characteristic oligodendroglial inclusions. In many cases, this disease can be readily distinguished, both clinically and pathologically, from idiopathic Parkinson's disease. However, often clinical differentiation is difficult, and in a few autopsied cases the presence of Lewy bodies, the characteristic inclusion of idiopathic Parkinson's disease, can lead to diagnostic confusion. Such a pathological association, named the "transitional variant" by some authors, is of unknown clinical and pathological significance. We here report three new cases of such an association from the United Kingdom Parkinson's Disease Society Brain Bank. Clinical and pathological data derived from these new observations, as well as from literature cases, tend to suggest that this pathological association is of no particular clinical significance. The comparison of the prevalence of Lewy bodies in normal elderly individuals and in multiple system atrophy suggests a chance association of the two pathologies. However, the small number of cases so far studied as well as the heterogeneity of series analyzed does not exclude the presence of common susceptibility factors for both diseases.