Unusual dural fistulae.

The authors present seven cases of dural fistulae selected because of their difficulty in diagnosis or in the approach to treatment. The first case had a "delayed traumatic" CSF rhinorrhea and the diagnosis remained, to the end, presumptive. The second and the third were either "spontaneous" or "delayed traumatic" in origin. One of these fistulae was localized in a lateral recess of the sphenoid sinus. Both were approached through the ethmoid, and one of these had to be re-operated intracranially because of recurrence. The fourth had a congenital meningo-encephalocele. The fifth and sixth had fistulae secondary to fronto-ethmoidal osteomas, one presenting with an intracranial mucocele, the other with a cerebral abscess. The last one, a traumatic fistula had to be treated extracranially after two unsuccessful intracranial approaches.