Aetiology and pathogenesis of acute sporadic disseminated encephalomyelitis and multiple sclerosis.

THE investigation of nervous diseases caused by viruses requires close co-operation between clinical and experimental workers. The present paper is the summary of such co-operative work performed by a neuro-histologist and a team of workers in virus diseases. Its chief purpose is to throw some light upon the etiology and pathogenesis ofacute disseminated encephalomyelitis and multiple sclerosis, because up to now many unsolved problems remain, not only in the field of etiology but also in that of their morphology and pathogenesis. Some authors are still inclined to doubt the infectious origin of multiple sclerosis, and offer a number of theories attempting to explain the pathogenesis of this disease, such as Putnam's obstruction theory, and toxic, allergic, lipolytic, and other theories. We shall not dwell on the non-infectious hypothesis of multiple sclerosis, because the authors advocating this theory take the effect of the pathological process for its cause. These hypotheses are based on changes occurring in individual morphological elements (glia) or on individual normal or abnormal responses of the organism, and so fail to yield an outline of the whole pathological process; they thus cannot give a true idea of pathogenesis. The result of virus and post-mortem investigation of many patients suffering from acute disseminated encephalomyelitis and multiple sclerosis was that two strains of filtrable viruses were isolated from two cases of acute disseminated encephalomyelitis. These strains appeared to be identical, but differed from other known strains of neurotropic viruses encountered in man.