Petrous apex cephalocele and empty sella: is there any relation?

OBJECTIVE: To document the presence of incidental petrous apex cephalocele (PAC) in association with empty sella in a group of patients and propose an etiologic/pathologic relation between the two lesions.

MATERIALS AND METHODS: Retrospective review of our imaging archive for the period from October 2001 to October 2006 revealed five patients with PAC (four females and one male; age range, 25-60 years; mean, 47 years). All patients underwent enhanced MR examination of the skull base and four of them underwent CT examination. Lesions were evaluated for size, content, signal intensity, enhancement, and relation to Meckel's cave and petrous apex. Images were also evaluated for the presence of empty sella.

RESULTS: The presenting symptoms in all patients were not attributable to PAC. None of the patients had symptoms related to the trigeminal nerve or history of CSF leak. Four patients had bilateral PAC and one had left PAC (total nine lesions). The lesions ranged from 6 mm to 15 mm (mean 9 mm) in the maximum diameter. All lesions were centered posterolateral to Meckel's cave and had low attenuation on CT with sharply demarcated margins. No lesion reached the inner ear structures, internal auditory canal, or mastoid air cells. On MR imaging, all lesions demonstrated CSF signal intensity that is continuous with that of the Meckel's cave. Only the periphery of the lesions demonstrated mild enhancement. All patients had empty sella. One patient had small arachnoid cysts in the middle cranial fossa, bilaterally.

CONCLUSION: PAC and empty sella are similar mechanically in terms of CSF extension and erosion into petrous apex and sella, respectively. Both conditions are seen predominantly in females and have been reported in association with CSF leak, which raises a possibility of etiologic/pathologic relation between the two.