Pathology of idiopathic encephaloceles into the middle ear.

Meningoencephalic herniations into the middle ear and mastoid are rare and histologic information has been supplied only in few reports. Sections from two idiopathic encephaloceles were compared with those from encephaloceles associated with previous trauma, infection or surgery described in the literature. In the idiopathic encephaloceles, the herniated tissue consisted of cortical neural tissue with degenerative changes and gliosis like that described in cases with a history of chronic infection, previous surgery or trauma, but no inflammatory cells were present.