Petrous apex cephalocele and empty sella/arachnoid cyst coexistence: a clue for cerebrospinal fluid pressure imbalance?

PURPOSE To reveal the magnetic resonance imaging (MRI) properties of incidental petrous apex cephalocele (PAC) and coexisting empty sella-arachnoid cyst. MATERIALS AND METHODS We reviewed our archive from June 2005 to July 2008. Four patients were diagnosed with PAC (four females; age range, 41-60 years; mean, 48.5). All patients underwent MRI examination of the cranium. We evaluated the lesions for extension into the neighboring structures, content, signal intensity, enhancement, and relation to Meckel's cave, petrous apex and for the presence of empty sella. RESULTS The presenting symptoms included headache for three patients and diplopia for one patient. All patients had bilateral PAC, more prominent on one side. All lesions were centered posterolateral to the Meckel's cave. They were isointense to cerebrospinal fluid signal intensity and continuous with Meckel's cave on T1W, T2W and FLAIR sequences. In two patients, there was no diffusion restriction on diffusion-weighted MR images and the ADC map. Three patients had empty sella. One patient had arachnoid cyst. CONCLUSION Coexistence with empty sella-arachnoid cyst raises the possibility of cerebrospinal fluid inbalance in the etiology.