The document summarizes various tumors and lesions that can occur in the cerebellopontine angle (CPA). The most common tumors are acoustic neuromas (schwannomas), which arise from the vestibular nerve. Other lesions include meningiomas, metastases, epidermoid tumors, dermoid cysts and lipomas. Imaging plays an important role in the diagnosis and treatment depends on the type and size of the lesion.

1. TUMOURS OF THE CPA Liew Boon Seng Master of Neurosurgery

18. (Samii and co-worker, 1995)

31. Imaging Melanoma in a 58-year-old woman with a left cerebellar syndrome. (a) Axial CT scan shows a hyperattenuating melanoma of the left CPA. (b) Axial T1-weighted MR image shows a well-defined extraaxial mass at the posterior edge of the petrous bone. The high signal intensity is suggestive of melanin. (c) Gadolinium-enhanced axial T1-weighted MR image shows a normal left internal auditory canal (arrow) and lack of dural tail enhancemen

39. House-Brackmann Grade (Facial Nerve Palsy) No movement Total paralysis 6 Barely perceptible motion Severe dysfunction 5 Obvious weakness and/or dysfiguring and assymetry Moderate-severe dysfunction 4 Obvious but not dysfiguring Moderate dysfunction 3 Slight weakness on close inspection Mild dysfunction 2 Normal function in all areas Normal 1 Description Function Grade

42. Imaging Lipoma in a 7-year-old boy with a polymalformation syndrome. (a) Axial CT scan shows a welldefined hypoattenuating lipoma of the left CPA. (b) Axial T1-weighted MR image shows that the lipoma has signal intensity similar to that of subcutaneous fat.

46. Imaging Brainstem glioma in a 23-year-old man with vertigo and hypoacusia. Contrast-enhanced axial T1-weighted MR image shows an unusual round grade III glioma located in front of the porus. The tumour demonstrates central enhancement.

57. Imaging Choroid plexus papilloma in a 49-year-old woman with vertigo and intracranial hypertension. (a) Axial T2-weighted MR image shows a right CPA papilloma extending through the foramen of Luschka. The tumour contains massive hypointense calcification (arrowhead). (b) Contrast- enhanced axial T1-weighted MR image shows intense enhancement of the hypervascularized tumour. Note the normal choroid plexus in the left foramen of Luschka.

63. Classification

68. Imaging Chordoma in a 61-year-old man with left trigeminal neuralgia and headaches. Contrast-enhanced axial T1-weighted MR image shows a chordoma invading the left CPA with unusual sparing of the clivus. There are suggestive enhanced septa (arrowheads).

73. Imaging Apex petrositis in a 50-year-old woman with Gradenigo syndrome at clinical evaluation. (a) Axial T1-weighted MR image shows an irregular lesion at the tip of the petrous apex (arrow). (b) Contrast-enhanced axial T1-weighted MR image shows right-sided apex petrositis as an enhancing lesion along the courses of cranial nerves V and VI (arrow).

76. Imaging Asymptomatic aneurysm in a 68-year-old man with lymphoma and right trigeminal neuralgia. a) Axial T2-weighted MR image shows an aneurysm of the left posterior inferior cerebellar artery with typical lack of signal (arrow). Note the lymphoma in the right pterygopalatine fossa (arrowheads), which explains the neuralgia. Aneurysm in a 75-year-old man with hypoglossal nerve palsy. b) Axial T2-weighted MR image shows a thrombosed aneurysm of the right posterior inferior cerebellar artery with focal calcification (arrowhead). Note the normal right hypoglossal canal (arrow), a finding inconsistent with a schwannoma. c) Contrast- enhanced coronal T1-weighted MR image shows homogeneous enhancement of the organized thrombus, which completely fills the aneurysm.

79. Thank You