Recurrent Encephalomyelitis in Childhood

Acute disseminated encephalomyelitis, with its histological appearance of perivenous demyelination and cellular infiltration, has been recognized for more than 30 years, but opinions regarding its aetiology have changed considerably during this time. At first it was thought that a direct virus infection of the central nervous system was respon-sible. Later, when it was found that the same histological picture occurred if the disease followed vaccination, any of the exanthemata or a respiratory infection, it was suggested that these precipitating causes had activated a latent virus. This theory was discarded when it was realized that the changes were unlike those of any known neurotropic virus disease and could be reproduced in experimental