Head and Neck Imaging

Petrous apex, pathology

- Congenital cholesteatoma presents as an expansile lesion in the petrous apex, mostly well demarcated. It cannot be distinguished from cholesterol granuloma on CT images. On MR, it shows low to intermediate signal intensity on T1-weighted and relative high signal intensity on T2-weighted images (see cholesteatoma ).
- Inflammation. When pneumatized, a similar spectrum of inflammatory disease can be seen in the petrous apex as in the middle ear and mastoid. Active infection may cause acute apical petrositis; when associated with osteomyelitis, this may cause Gradenigo's syndrome . In the case of osteomyelitis, CT shows destructive bone changes in the petrous apex; on MRI, meningeal enhancement will be visible ( Fig. 2). Further complications include thrombosis of the cavernous sinus or other intracranial venous sinuses, or formation of an intracranial abscess.
Inflammation in the petrous apex may trigger the formation of a cholesterol granuloma .
- Trauma. The petrous apex may be involved by a transverse fracture, temporal bone ; this may be associated with lesions of the adjacent cranial nerves (facial, trigeminal and abducens nerve).
- Tumour. A variety of benign and malignant tumoral lesions may be encountered, either originating in the petrous apex or secondarily growing into this structure (Table 1).

Petrous apex, Table 1. Petrous apex tumours (adapted from J.D. Swartz, H. Ric Harnsberger: Imaging of the temporal bone. 3 Ed., Thieme, New York, 1998, p. 453).

Originating in petrous apexSecondarily invading petrous apex
metastasisschwannoma, acoustic
giant cell tumour , giant cell tumourglomus tumour
aneurysmal bone cystmeningioma
Langerhans histiocytosis Xchordoma
rhabdomyosarcoma, head and neckchondrosarcoma, head and neck
plasmacytomanasopharyngeal cancer
haemangioma, head and neckpituitary adenoma
papillary adenomatous tumour 

 

RH

 

RH

To view high resolution images,
please register first.

Click  here to register.

Already registered? Enter your e-mail in the window below.
Re-register

Fig. 02a

Nine-year-old girl with chronic otitis media and mastoiditis, not responsive to antiobiotics. Axial gadolinium-enhanced T1-weighted spin-echo image of temporal bones. Pronounced enhancement is seen in the left middle ear and mastoid cavity; there is similar inhomogeneous and pronounced enhancement in the left petrous apex (arrow). Meningeal extension of the process along the clivus and into the internal auditory canal (arrowhead). Tuberculosis (courtesy by Bert De Foer, MD, Antwerp, Belgium).
Petrous apex, pathology, Fig. 01a
Petrous apex, pathology, Fig. 02a