Pathological differences in acute inflammatory demyelinating diseases of the central nervous system.

This article reviews the different pathological and immunological features of MS, acute variants of MS and acute disseminated encephalomyelitis (ADEM). T-cell-mediated inflammatory reactions are involved in all acute inflammatory diseases of the central nervous system, but the diseases discussed also exhibit distinct immunopathological features. The perivascular infiltrate of T-cells and macrophages seen in ADEM resembles the pathological pattern found in experimental autoimmune encephalomyelitis. In addition, there is evidence that humoral mechanisms play a crucial role in some acute MS lesions, Devics syndrome and Marburgs syndrome. Analysis of acute MS lesions shows many different structural and immunological features, indicating that different mechanisms may be involved in lesion formation. Distinct subtypes of acute lesions exhibit either similarities with T-cell-mediated autoimmune encephalomyelitis or signs of primary oligodendrocyte damage.