Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Petrous apex cephalocele is a rare lesion representing the protrusion of arachnoid or dura mater from Meckel’s cave into the petrous apex. It is thought to be caused by increased intracranial pressure, and it is associated with an empty sella. Axial FIESTA MRI shows bilateral extension of Meckel’s cave to the petrous apex (A, arrows). The lesions are isointense to the CSF and appear more prominent on the right side. Axial T2WI and sagittal T1WI show coexistent bilateral optic nerve sheath CSF space enlargement (B, arrows) and a partially empty sella (C, arrow) due to chronic intracranial hypertension.