When the virus of measles attacks the central nervous system the resulting clinical picture has one outstanding characteristic, namely, variability. Results of physical examinations and laboratory tests are so bizarre and inconstant that in respect to them one case has little in common with another, save that all results indicate involvement of the central nervous system. No more specific common denominator is available.Encephalitis complicating measles has long been known and reported, but in no instance has any considerable series of cases been analyzed by a single observer ; consequently, the clinical data have been limited to the observations in small groups of cases. Even terminology has been confused, because the widely varying clinical picture tends to encourage nomenclature descriptive of individual observations. Thus one finds "encephalitis," "encephalomeningitis," "serous meningitis," "paraplegia," "meningoencephalitis" and other terms used in case reports. Because the term encephalitis seems best fitted to the condition in the large majority of cases and to avoid confusion, we shall use it, even though in an occasional case it is not the best descriptive name.
REPORT OF STUDYThis report is an attempt to correlate the findings in 241 cases reported by 110 authors during the past decade, together with data from 44 other cases observed by us. Naturally, such a study cannot be statistically accurate, both because the number of cases is too small for statistical significance and because many items were not mentioned in all the cases recorded, but it may shed some light on a confused subject which seems to be assuming increasing importance.