[Aneurysmal bone cyst of the petrous bone. A rare cause of recurrent bacterial meningitis].

Occult malformations of the skull base are very rare disorders which cannot initially be diagnosed clinically. They become first symptomatic, if complications arise. The most frequent clinical manifestation is a recurrent bacterial meningitis. Based on the unique case of a presumably congenital aneurysmal bone cyst of the petrosal bone, which imposed clinically as hearing loss and recurrent bacterial meningitis, we have evaluated the extensive literature on this theme. Considering mostly atypical clinical findings, solely coronal thin-section computed tomographic scans of the skull base allow a reliable diagnosis. The possible risks of this investigation (necessary sedation up to insufflation anesthesia and the radiation exposure of the child's lens) are justifiable and subordinate to the diagnostic importance.