Since Schilder1described in 1912 the first case of encephalitis periaxialis diffusa, considerable attention has been paid by investigators to demyelinating processes leading to either patchy or diffuse sclerosis. Numerous cases have been described under the most varied headings: Schilder's disease, encephalitis periaxialis diffusa, symmetrical cerebral central lobar sclerosis (Marie and Foix2), encephalopathia scleroticans (Flatau3), encephalomyelomalacia chronica diffusa (Hermel4), progressive degenerative subcortical encephalopathy (Globus and Strauss5), leuko-encephalopathia diffusa (Austregesilo, Gallotti and Borges6), sclerotic inflammation of the white matter of the hemispheres (Spielmeyer7), leuko-encephalopathia myeloclastica primitiva (Patrassi8), encephalopathia extracorticalis diffusa, "Schilder's type" (d'Antona9), diffuse sclerosis with preserved myelin islands (Löwenberg and Hill10) and encephalitis periaxialis concentrica (Baló11). To these cases must be added those of the familial type described under various headings: by Krabbe,12as a new familial infantile form of diffuse cerebral sclerosis occurring in childhood; by Scholz,