Mastoiditis and brain hernia (mastoiditis cerebri).

Ten patients with brain hernia occurring as an insidious complication of chronic mastoiditis coincidentally discovered at the time of surgery are described. Four had previous surgery, six did not. A history of trauma was othwise absent. Cerebrospinal fluid otorrhea did not occur. Our method of management is described. Pathology and pathogenesis are discussed. Three patients had pedunculated brain hernias, while seven had diffuse (fungoid) herniation. Granulation tissue appeared as an important part of the disease process. These may represent abortive attempts at brain abscess formation since the widespread use of antibiotics. Pacchionian bodies may also play a role in the pathogenesis.