Acute suppurative conditions, either in the accessory sinuses of the cranium or in the ear and its related structures, and in the brain, very frequently cause a reaction in the cerebrospinal fluid. This reaction is characterized by: (1) an increase in the amount of the fluid; (2) an increase in the albumin content, which may be moderate or considerable; (3) pleocytosis, in which generally there is an increase of polymorphonuclear leukocytes, but occasionally an increase in the number of lymphocytes; (4) turbidity of the fluid. These changes in the cerebrospinal fluid may be associated with the symptoms of meningitis, such as rigidity of the neck and the presence of Kernig's symptom. This reaction has received the name of meningitis sympathica by Plaut, Rehm and Schottmüller.1 The most frequent etiologic factor is inflammation of the ear, with or without mastoid sinus or labyrinth involvement, and in these