1. Dr/ ABD ALLAH NAZEER. MD.
Radiological imaging of cerebello-
pontine angle mass lesions.

2. The cerebellopontine angle is
the anatomic space between
the cerebellum and the pons.
Borders:
-Medial- Lateral surface of the
brain stem.
- Lateral- Petrous bone.
-Superior- Middle cerebellar
peduncle and cerebellum.
-Inferior- Arachnoid tissue
of lower cranial nerve.
-Posterior- Cerebellar
peduncle.
-Contents- CSF, arachnoid
tissue, cranial nerves and
their associated vessels.
Anatomy.

7. A. Solid Masses:
Schwannoma
The schwannoma is a benign tumor, composed entirely of
Schwann cells. The neurofibroma is a well-differentiated
nerve sheath tumor composed predominantly of Schwann
cells and, to a lesser extent, fibroblasts and perineural
cells. In small lesions, the parent nerve can be detected
within the tumor; in larger tumors the relationship between
the nerve and the tumor becomes obscured.
Diagnostic elements:
•Centered on Porus Acousticus
•"Ice cream on cone" pattern (intracanalicular extension)
•Acute angles to petrous bone
•Often involves the IAC
•Homogeneous enhancement
•No dural tail
No calcifications

8. RIGHT ICA NEUROFIBROMA of the VIII nerve: mass lesion with inhomogeneous
enhancement due to small necrotic areas, developed in the right CPA centered on the
IAC with intracanalicular extension associating slight enlargement (confirmed by CT scan)

9. Left vestibular schwannoma.

10. Right vestibular schwannoma.

11. NEUROFIBROMATOSIS TYPE II: bilateral acoustic schwannoma; left CPA meningioma.

12. NEUROFIBROMATOSIS TYPE II: bilateral acoustic schwannoma.

13. (typical “ice cream on cone” appearance). Bilateral vestibular
schwannomas are diagnostic of neurofibromatosis type 2.

14. Trigeminal schwannoma.

15. Trigeminal schwannoma.

16. Schwannoma with left ear pain.

17. Meningioma
Meningiomas are well-circumscribed, globular
or lobulated, vascular, non-glial tumors of the
central nervous system arising from arachnoidal
cells, clearly demarcated from the brain
Diagnostic elements:
• Arise from surface of petrous bone Obtuse angles
to petrous bone
Uncommonly involves the IAC
Frequently with "dural tail" sign (linear enhancement
along the dura matter on either side of the tumor)
Calcifications common
Pial vessel flow voids

18. LEFT PCA MENINGIOMA: nodular lesion with intense
enhancement and extra-axial topography developed in the left
CPA, with a broad base and obtuse angles to the petrous bone.

19. Left CP angle Meningioma.

20. GIANT MENINGIOMA of the left sphenoidal region, with multiple extensions to both
sphenoidal sinuses, posterior ethmoidal cells, engulfing the left internal carotid artery, and
with extension to the posterior fossa (left CPA) including nerves V, VI, and VII on the left side.

21. B. Cystic Masses:
Arachnoid cyst
Loculated collections of CSF within a reduplication of
arachnoidal membrane.
Erosion of the adjacent calvarium is often present.
Diagnostic elements:
•Avascular cystic mass
•Nonenhancing
•Smooth regular shape
•Homogeneous, identical signal to CSF in all
weightings
•No calcifications
•FLAIR sequence shows intense signal suppresion
Diffusion weighting will show a hipointensity (no restriction of
diffusion).

22. RIGHT PCA ARACHNOID CYST: cystic lesion at the level of the right CPA, with identical signal
to the CSF in all weightings, with slight mass effect on the right cerebellar hemisphere.
Right side cranial nerves VIII and VII appear enveloped in the cysternal segment, but with
no significant course alteration

23. Left arachnoid cyst.

24. Large cystic lesion of the left posterior cerebellopontine angle.

25. Epidermoid cyst
Extra-axial lesions which typically spread along the basal
surface. Rupture can produce aseptic meningitis.
Overwhelmingly benign.
Diagnostic elements:
•May dumbbell into middle fossa or contralateral cistern
•Nonenhancing (25% mild peripheral enhancement
•CT usually shows a mass hypodense to CSF
•Inhomogeneous lesion, highly variable in shape with a
cauliflower surface appearance
•T1 -hypo-isointense; T2 -hyperintense (if it has a high
protein content, it may have high signal
•on T1 and low signal on T2 MR sequences = "white
epidermoid.”
•FLAIR sequence shows iso-hyperintensity
•Diffusion weighting will show a characteristic moderate
intensity (restriction of diffusion)

26. LEFT PCA EPIDERMOID CYST: well delineated lesion, which involves the left prepontine
cistern and CPA, with slight mass effect on the left pons, and engulfing of the cranial
nerves V to VIII on the left side, in the cisternal segment. The lesion has a fluid-type signal,
slightly heterogenous, but with important water diffusion restriction.

27. Right epidermoid cyst.

28. Left epidermoid cyst.

30. Large left epidermoid cyst.

31. C. Lipomatous Masses:
Lipoma
Anomalously developed masses that arise from abnormal
differentiation of the meninx
Primitive Signal intensity similar to that of fat on all sequences -> high
signal on T1-weighted images;
would be of intermediate signal on T2-weighted images, similar to
subcutaneous and marrow fat; and
would not be visible, "disappear," on fat-saturated sequences
Nonenhancing (thick peripheral capsule that may enhance
Dermoid cyst
Midline lesions that rarely invade the CPA laterally, contain elements
from all layers of the skin FLAIR, CISS and DWI
certify diagnostic MR appearance depends on the amount of fat
present, although generally they are of increased signal
on both T1-and T2-weighted images
Cholesterol granuloma
Results from the chronic obstruction of air cells and accumulation of secretions
Expansile lytic lesions of the temporal bone
Central region of high signal intensity and a peripheral hypointense rim on both
T1-and T2-weighted images Nonenhancing

32. Left CP angle lipoma.

33. Lipoma at the CP angle.

34. Right lipoma at the CP angle. Left lipoma at the CP angle.

35. Cholesterol granuloma with right trigeminal neuralgia.

36. Cholesterol granuloma.

37. D. Flow void masses:
Vascular loop syndrome
Affected nerves may by V (at root entry zone) or VII (at root exit zone)
Vessel may by atherosclerotic -serpiginous, irregular MR Angiography -
source images are most helpful
Vertebrobasilar dolichoectasia may be one of the causes (atherosclerotic
finding especially in the elderly)
Venous anomaly
Various developmental anomalies, which may involve the CPA as a
drainage route, but rarely with clinical impact 2D and 3D Time of
Flight sequences are useful for evaluating the vascular axes Contrast
administration shows more detail
VB, PICA, AICA aneurysms
Non-neoplastic lesions, but with mass effect Thrombosis associates
hyperintensity in T1 (methemoglobin); possible enhancement of the
thrombus Pulsation artifacts may also be present in cases of aneurysm.
Secondary involvement:
Glomus tumor Sphenoid meningioma Lymphoma Ependymoma Choroid
plexus papilloma

38. NEURO-VASCULAR CONFLICT: megadolico-vertebral and basilar arteries, with significant
mass defect on the pons, which appears displaced medially and to the posterior. Note the
segmentary contact with the left-side VII and VIII cranial nerves, in the cisternal segment,
with their slight displacement to the posterior.

39. PICA aneurysm.

40. Aneurysm with hypoglossal palsy.

41. CAVERNOMA and VENOUS DEVELOPMENT ANOMALY of the left middle cerebellar
peduncle. Left cerebellar venous development anomaly made of a series of small venules
with deep topography which converge to a venous collector, in the immediate vicinity of
the described cavernoma, which then crosses the left CPA cistern to connect through a left
temporal cortical vein to the left transverse sinus.

42. CP Angle AV malformation.

43. AGGRESSIVE PARAGANGLIOMA (*) with invasion of the right CPA.

44. Paraganglioma with right facial nerve palsy, vertigo, and tinnitus.

45. Chondrosarcoma with intracranial hypertension.

46. Melanoma with a left cerebellar syndrome.

47. Metastases with lung cancer and right-sided hypoacusia, vertigo, and ear pain.

48. Endolymphatic sac tumor man with von Hippel-Lindau disease and vertigo.

49. Apex porosities with Gradenigo syndrome at clinical evaluation.

50. Choroid plexus papilloma with vertigo and intracranial hypertension.

51. Lymphoma with acquired immunodeficiency syndrome, vertigo, and headaches

52. Hemangioblastoma with von Hippel-Lindau disease and vertigo.

53. Ependymoma with vertigo, headaches, and left facial nerve palsy.

54. Dysembryoplastic neuroepithelial tumor with mild, long-lasting headaches

55. Atypical teratoid–rhabdoid tumor of cerebellopontine angle region.

56. Meningeal hemangiopericytoma of cerebellopontine angle.

57. Two cases of multiple hemangioblastomas.

58. Intra-ventricular ependymoma with extension to the CP angle.

59. Right side brain stem glioma with right CP angle extension.

60. Thank You.