CEREBRAL extension into the mastoid has been present in three of my patients since 1957. One developed after labyrinthine fenestration surgery, one after a radical mastoidectomy with tympanoplasty, and one was found in the mastoid when a mastoidectomy was being done as a preliminary to a myringoplasty. The singular feature of the postsurgical ears was the presence of mistakenly diagnosed "blue-domed" or "chocolate cysts." Unhappily, each proved to be intracranial extensions into the mastoid. None appeared with a cerebrospinal fluid otorrhea.
The first patient had her fenestration surgery done by a very competent and experienced otologist in the Middle West. The second patient's radical mastoid surgery was done by me. The operative report of each recorded an exposure of the dura adjacent to the tegmen antri, but in neither was there overt evidence of a dural tear or a cerebrospinal fluid leak. In the third patient, one with a