[Basal encephalomeningocele occurring in an aged woman; a case report and the usefulness of MRI in diagnosis].

The usefulness of MRI in diagnosis of a basal encephalomeningocele case is reported. A 72-year-old woman with a several-year history of occasional watery rhinorrhea and previous histories of meningitis at the ages of 55 and 65 is the subject of this report initially. After referring to the department of otorhinolaryngology, she was admitted to our department for close examination. CT scan showed only a mass forming a cyst in the nasal cavity, but MRI demonstrated part of the left rectal gyrus invaginating into the ethmoid sinus and nasal cavity. The mass was concluded to be a basal encephalomeningocele of a transethmoidal type, and dural plasty by bifrontal craniotomy was performed for the CSF rhinorrhea. MRI has numerous advantages over CT, e.g. the multiplanar capability without artificial dilution of the image of surrounding bones makes it the most valuable image technique for skull base lesions, making the diagnosis of basal encephalomeningocele much easier than it would be using conventional methods.