Cerebellopontine Angle

Acoustic schwannoma Most common mass, up to 75% of cases

Meningioma Second most common lesion, up to 10% of cases

Ectodermal inclusion tumors

- Epidermoid

- Dermoid Metastases Paraganglioma

Other schwannomas

Vascular

- Dolichobasilar ectasia

- Aneurysm

- Vascular malformation

Choroid plexus papil-loma

Also known as "congenital cholesteatoma" or "pearly tumor"; 5-7%

Also known as "glomus jugulare tumor"; a chemodec-toma arising from the jugular foramen and extending into the CPA; 2-10%

2 - 5 %. The trigeminal and facial nerves are probably the most common sites of nonacoustic schwannomas. Other cranial nerves involved are: VI, IX, X, XI, and rarely XII

1 %; primary in the CPA or extension via the lateral foramina of Luschka

Ependymoma

Rare lesions

- Arachnoid cyst

- Lipoma

- Exophytic brain stem or cerebellar astrocytoma

- Chordoma

- Osteocartilaginous tumors

- Cysticercosis

1 %; extension from the fourth ventricle Incidence < 1 %

CPA: cerebellopontine angle.

temporal lobe -CPA cistern —

temporal bone AICA -

cochlea Pons CN VII -CN VIII

vestibule-

(semicircular canal)

4th ventricle cerebellum jugular-

foramen

Cerebellopontine Angle Anatomy

Fig. 7 Cerebellopontine angle. Diagram of the cerebellopontine angle anatomy

Fig. 8 Cerebellopontine angle lesions

1. Acoustic neurinoma. Axial CT with right acoustic neurinoma and erosion of the internal auditory meatus with a small protrusion of the tumor in the cerebellopontine angle.

2. Erosion of the auditory meatus. Bone windows of an axial CT of the same patient with an abnormal erosion of the right internal auditory meatus.

3. Acoustic neurinoma. A solid space-occupying mass with mild postcontrast enhancement producing erosion of the right acoustic meatus, protrusion into the right CP angle, and compression of the pons and cerebellar peduncles.

4. Chordoma. Axial T1 WI shows a solid, space-occupying lesion with postcontrast enhancement occupying the left middle temporal fossa and ipsilateral CP angle as well as erosion of the apex of the petrous and sphenoid bone.

Sphenoid Bone

5, 6. Meningioma. Axial and coronal T1 WI with a postcontrast enhancing meningioma of the right CP angle that extends into the right jugular foramen causing compression of the medulla oblongata and the right cerebellar hemisphere.

7. Epidermoid tumor. Coronal T1 WI with a cystic space-occupying, nonen-hancing lesion in the right CP angle with compression signs of the pons.

8. Epidermoid tumor. A solid and heterogeneous mass with smooth margins eroding the left occipital bone and compressing the left cerebellar hemisphere is seen on axial T1 WI.

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