The pathologic changes in localized intracranial suppuration vary widely and, for the sake of accuracy, the type of abscess should be speci fied before advantages for any particular method of surgical treatment are claimed. Multiple pyemic abscesses are nearly always fatal and do not present any aspects of great surgical interest (figs. 1 and 2). Abscesses due to gunshot wounds, if solitary, have a better prognosis, but even these have essential causes for a high mortality (fig. 3). Infec tion by highly virulent organisms may produce a rapid necrosis which the tissues of the brain are unable to encapsulate and resist. Treatment for this type of abscess is generally unsuccessful.
The material in this paper is restricted entirely to the encapsulated, subcortical abscess which usually arises from infection of the accessory sinuses. These abscesses, if successfully resisted by the brain tissues, pass through a stage of encephalitis which is followed