Learning objectives
To review the normal imaging anatomy and the most frequent pathologies of cerebellopontine angle (CPA).
To ilustrate the imaging features of cerebellopontine angle lesions and the role of computer tomography (CT) and magnetic resonance imaging (MRI) in the differential diagnosis.
Background
The cerebellopontine angle is a subaracnoid space bounded by the pons,
cerebellum and temporal bone ( Fig. 1).
Expansive CPA lesions usually produce nonspecific symptoms related to mass effect above adjacent structures.
The most frequent symptoms are hearing loss,
tinnitus,
facial motor (VII) or sensitive (V) dysfunction,
headache and ataxia.
Cerebellopontine angle tumors are frequent and represent approximately 5-10% of all intracranial tumors.
The most common masses of the CPA are vestibular schwannomas (70-80%),
meningiomas (10-15%) and epidermoid cysts (5%).
Findings and procedure details
Computerized tomography (CT) and magnetic resonance imaging (MRI) are the primary modalities for diagnosis of cerebellopotine lesions.
The main imaging features to analyze in a cerebellopontine angle mass are: CT attenuation,
signal characteristics at MR imaging,
origin,
shape,
presence of calcifications and adjacent bone reaction.
It is important to classify CPA lesions based on its intra or extra-axial origin to narrow the differential diagnosis (Fig. 2).
CPA masses can arise from:
Cerebellopontine angle contents (cranial nerves,
vessels,
CSF,
arachnoid tissue).
Extension from the osseous boundaries...
Conclusion
Understanding of the anatomy and pathological processes of CPA combined with imaging characteristics (CT and MRI) is the key to establish an accurate diagnosis for cerebellopontine angle lesions.
References
Osborn,
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Bonneville F,
Sarrazin JL,
Marsot-dupuch K et-al.
Unusual lesions of the cerebellopontine angle: a segmental approach.
Radiographics.
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Bonneville F1,
Savatovsky J,
Chiras J.
Imaging of cerebellopontine angle lesions: an update.
Part 1: enhancing extra-axial lesions.
Eur Radiol.
2007 Oct;17(10):2472-82.
Bonneville F1,
Savatovsky J,
Chiras J.
Imaging of cerebellopontine angle lesions: an update.
Part 2: intra-axial lesions,
skull base lesions that may invade the CPA region,
and non-enhancing extra-axial lesions.
Eur Radiol....