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Table of Contents    
Year : 2017  |  Volume : 65  |  Issue : 1  |  Page : 217-219

Incidentally detected bilateral petrous apex cephaloceles: CT and MRI features

Clinic of Radiology, Antalya Ataturk State Hospital, Antalya, Turkey

Date of Web Publication12-Jan-2017

Correspondence Address:
Dr. Arzu Canan
Clinic of Radiology, Antalya Ataturk State Hospital, Antalya
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.198215

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How to cite this article:
Canan A, Çıra K, Özbilek &, Koç K, Aksoy C. Incidentally detected bilateral petrous apex cephaloceles: CT and MRI features. Neurol India 2017;65:217-9

How to cite this URL:
Canan A, Çıra K, Özbilek &, Koç K, Aksoy C. Incidentally detected bilateral petrous apex cephaloceles: CT and MRI features. Neurol India [serial online] 2017 [cited 2021 Apr 20];65:217-9. Available from:


A 61-year-old woman was referred to our service with complaint of tinnitus on the left side. Neurological examination showed no significant abnormality. High-resolution temporal bone computed tomography (CT) in the axial and coronal planes with a slice thickness of 1 mm and a bone algorithm was performed. CT images showed bilateral smoothly marginated expansile lesions, which caused adjacent bone scalloping, especially on the right side [Figure 1]a. The right lesion was larger and more expansile than the left. Magnetic resonance imaging (MRI) of the brain, including axial T1 [Figure 1]b, T2 [Figure 1]c, and coronal T2 [Figure 2] images demonstrated cystic lesions located in bilateral Meckel's cave and extending into the petrous apex. The lesions had a similar signal intensity with cerebrospinal fluid on all sequences. There was no contrast enhancement. According to MRI findings, the lesions were diagnosed as bilateral petrous apex cephaloceles (PAC).
Figure 1: Axial CT scans (a) show bilateral smoothly marginated, lobulary cystic lesions of petrous apex. Axial T1 (b) and T2 (c) weighted images demonstrate bilateral cystic lesions that have similar signal intensity with CSF (hypointense on T1, hyperintense on T2). Also, the communications with Meckel's cave are identified (arrows)

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Figure 2: Coronal T2 weighted images show bilateral cystic lesions and association with bilateral Meckel's caves (arrows)

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PAC are uncommon developmental lesions of the petrous apex. They herniate from the posterolateral portion of the Meckel's cave into the petrous apex and erode the adjacent temporal bone. Pathologically, they are considered to be meningoceles and arachnoid cysts.[1] However, there are a few case reports in the literature which described symptoms of headache, hearing loss, otorrhoea, or pulsatile tinnitus due to PACs.[2] They are usually asymptomatic and can be unilateral or bilateral. These are detected incidentally by CT or MRI, and hence are considered “leave alone” lesions.[3],[4] Differential diagnosis includes other cystic lesions of the petrous apex such as a cholesteatoma, cholesterol granuloma, mucocele, apical petrositis, and petrous apex effusion. Misdiagnosis may cause unnecessary investigations and surgical interventions. PACs originate from the Meckel's cave, and it is this unique distinctive radiological feature that enables the establishment of the correct diagnosis.[1] Hence, the radiologist should be familiar with the distinctive radiological findings of PACs to differentiate them from other cystic petrous apex lesions and to avoid further investigations and surgery.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Cheung SW, Broberg TG, Jackler RK. Petrous apex arachnoid cyst: Radiographic confusion with primary cholesteatoma. Am J Otol. 1995;16:690-4.  Back to cited text no. 1
Isaacson B, Coker NJ, Vrabec JT, Yoshor D, Oghalai JS. 2006. Invasive cerebrospinal fluid cysts and cephaloceles of the petrous apex. Otol Neurotol 2006;27:1131-41.  Back to cited text no. 2
Moore KR, Fischbein NJ, Harnsberger HR, Shelton C, Glastonbury CM, White DK, et al. Petrous apex cephaloceles. AJNR Am J Neuroradiol 2001;22:1867-71.  Back to cited text no. 3
Razek AA, Huang BY. Lesions of the petrous apex: Classification and findings at CT and MR imaging. Radiographics 2011;32:151-73.  Back to cited text no. 4


  [Figure 1], [Figure 2]


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