Occult malformations of the skull base.

Occult malformations of the skull base are rare anomalies. They are often not detected until they give rise to complications such as meningitis or cerebrospinal fluid rhinorrhea. We used high-resolution computed tomography, fluorescein endoscopy, cisternography, magnetic resonance imaging, and duraplasty to diagnose occult malformations of the skull base in 4 patients. The four patients had had between 4 and 6 attacks of meningitis. Cerebrospinal fluid rhinorrhea was confirmed in 3 cases. The following occult malformations were found: (1) an encephalocele of the glabella/cribriform plate and a meningocele at the petrous bone apex, (2) a meningoencephalocele at the petrous bone apex, (3) dural lesions in the regions foramen rotundum/sphenoid sinus and frontal sinus/cribriform plate, and (4) a dural lesion of the sphenoid sinus. In patients presenting with recurrent meningitis, meningitis with isolation of upper airway pathogens, or cerebrospinal fluid rhinorrhea, modern diagnostic methods should be used to search for dural lesions. Diagnosis of an occult malformation makes it possible to perform the necessary surgical repair and thus prevent the further occurrence of potentially fatal episodes of meningitis.