[Viral diseases of the nervous system].

Study of nervous system viral diseases is not limited to descriptions of the topography of the infection in man : it also includes studies of animal models which can help in the understanding of the physiopathology of the diseases.It is unlikely than all viruses which can infect nervous tissues are known, and new human viruses have been discovered by Neurologists. Analysis of the route of viral penetration into the brain, and of differing cell susceptibility can help our understanding of disease.Pathological modalities, other than acute infection, have been recently described.Slow virus infections can result from an atypical relationship between the virus and the cell, or the infected cell and the immunological response of the host, as well as from infection by a new category of unconventional agents which nervertheless share some common properties with known viruses.