Imaging of the petrous apex: a pictorial review

Abstract

A wide variety of pathologies arise from the petrous apex. Such lesions may present with symptoms caused by mass effect or cranial nerve palsies, or may be detected during an investigation for an unrelated disease. CT and MRI are complementary in providing an appropriate differential diagnosis and in aiding surgical planning. This pictorial review appraises the anatomy and contents of the petrous apex. Benign (e.g. cholesterol granuloma, cholesteatoma), inflammatory (e.g.apical petrositis) and dysplastic (e.g. Pagets disease) lesions of the petrous apex are discussed and illustrated. Whilst it is more frequent for neoplastic lesions to extend from adjacent structures, we demonstrate a variety of aggressive tumours and tumour-like conditions (e.g. metastasis, rhabdomyosarcoma, Langerhan's cell histiocytosis, endolymphatic sac tumour) that directly involve the petrous apex. A range of normal radiological appearances are seen, some of which may be mistaken for significant pathology (e.g. asymmetric marrow space development, simple effusions, cephaloceles). An imaging algorithm to aid the formulation of a differential diagnosis is also presented.

Petrous apex cephalocoele: contribution of coexisting intracranial pathologies to the aetiopathogenesis

“…1,2 Mucocele, trapped fluid, cholesterol granuloma, cholesteatoma, trigeminal cystic schwannoma and petrous apicitis may be considered in the differential diagnosis of petrous apex lesions. 3,4 The coexistence of PAC and empty sella or arachnoid cyst has been reported in the literature and was suggested to support the possible role of disturbance of CSF circulation in pathophysiology. 2,5 In this study, we report the largest series of patients with PAC and other coexistent intracranial pathologies.…”

Altıncı kraniyal sinir felci oluşturan ve ölümle sonuçlanan petröz kemik yerleşimli anevrizmal kemik kisti

“…Neoplasms constitute a much less frequent cause of sixth nerve palsy than hypertension or diabetes. The differential diagnosis of a petrous apex lesion include pseudolesions (asymmetric marrow space development), infectious and inflammatory pathologies (cholesterol granuloma, cholesteatoma, mucocele), vascular lesions (arteriovenous malformation), dysplasias and neoplasms (8). As our case report indicates, petrous apex ABC, although rare, should be considered in the differential diagnosis of isolated or coexistent sixth nerve palsy or a petrous apex mass, especially in the presence of typical MRI findings.…”

Gradenigo Syndrome Caused by Nontuberculous Mycobacteria

“…CT is useful for evaluating the bony cortex: a subperiosteal lucency implies abscess formation in the periosteum in an acute case; opacification or the coalescence of air cells and bony destruction suggests a chronic case, and erosion of the cortical bone of the petrous pyramid and the skull base implies petrositis [González-García et al, 2009;Marianowski et al, 2001;Sherman and Buchanan, 2004]. MR imaging is sensitive in detecting early marrow changes and intracranial complications, and is helpful in differentiating petrous apicitis from other petrous diseases, including cholesteatoma, mastoiditis, chondroma, clival chordoma, epidural abscess, cholesterol cyst, and metastasis [Connor et al, 2008;Moerman et al, 1993;Sherman and Buchanan, 2004]. The abnormalities that are observed in the MR images may persist [Gibier et al, 2009], and gallium-67 scintigraphy can be utilized to monitor the resolution of infections [Vijayananthan et al, 2008].…”