Petrous apex cephalocoele (PAC) is a rare form of cephalocoele centered typically in the posterolateral part of Meckel cave with variable extension into the petrous apex. They can be unilateral or bilateral (commoner).
There may be a slight female predilection.
The lesions are incidentally detected and are asymptomatic most of the times. Though they may present with trigeminal neuralgia, headache, CSF otorrhoea, and sensorineural hearing loss.
Recognised associations include
- homogenously low density area is noted in the petrous apex with sharply defined margins
MRI can demonstrate the continuation with Meckel cave and hence helps in providing a confident diagnosis thereby preventing unnecessary surgical intervention. The signal intensities follow that of CSF.
- T1: hypointense
- T2: hyperintense
- FLAIR: typical CSF suppression
- DWI: no restriction
As a general differential consider
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- 2. Razek AA, Huang BY. Lesions of the petrous apex: classification and findings at CT and MR imaging. Radiographics. 2012;32 (1): 151-73. doi:10.1148/rg.321105758 - Pubmed citation
- 3. Stark TA, McKinney AM, Palmer CS et-al. Dilation of the subarachnoid spaces surrounding the cranial nerves with petrous apex cephaloceles in Usher syndrome. AJNR Am J Neuroradiol. 2009;30 (2): 434-6. doi:10.3174/ajnr.A1283 - Pubmed citation