Cerebellopontine angle tumour

Published on 05/05/2015 by admin

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Last modified 22/04/2025

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82 Cerebellopontine angle tumour

Instruction

Examine this patient’s cranial nerves.

Diagnosis

This patient has features of cerebellopontine angle tumour (lesion) usually caused by an acoustic neuroma (aetiology), and has severe hearing loss (functional status).

Advanced-level questions

Mention a few causes of cerebellopontine angle lesions

• Acoustic neuroma (now knowns as vestibular schwanommas) accounts for 70–80% of cerebellopontine angle tumours

• Meningioma, cholesteatoma, haemangioblastoma, aneurysm of the basilar artery

• Pontine glioma

• Medullablastoma and astrocytoma of the cerebellum

• Carcinoma of the nasopharynx

• Local meningeal involvement by syphilis and TB.

What do you understand by the term cerebellopontine angle?

It is the shallow triangular fossa lying between the cerebellum, lateral pons and the inner third of the petrous temporal bone. It extends from the trigeminal nerve (above) to the glossopharyngeal nerve (see below). The abducens nerve runs along the medial edge, whereas the facial and auditory cranial nerves transverse the angle to enter the internal auditory meatus.

There is a wide range of pathologic processes within the cerebellopontine angle. These processes may present because of mass effect on local structures, such as the fifth to twelfth cranial nerves, or because of mass effect on the pons or cerebellum, which may result in fourth ventricular obstruction.

What is the histology of acoustic neurofibroma?

It consists of elongated cells similar to spindle fibroblasts with much collagen and reticulum. They are believed to arise from Schwann cells and are also known as schwannomas. These lesions most often arise from the inferior vestibular nerve within the internal auditory canal and present with hearing loss or tinnitus. Schwannomas can be entirely intracanalicular or have intracanalicular and cisternal components, resulting in the description of an ‘ice-cream cone’ tumour (Fig. 82.1).

Fig. 82.1 (A) Axial T₁-weighted, postcontrast, fat-saturated imaging demonstrates a heterogeneously enhancing classic ‘ice-cream cone’ vestibular schwannoma of the right cerebellopontine angle and internal auditory canal (arrows). (B) Axial fast imaging using steady-state acquisition, thin-slice, T₂-weighted imaging of the same lesion (arrows) shows the contours of the schwannoma, clearly delineated from hyperintense CSF and with a ‘cap’ of CSF between the schwannoma and the cochlea.

(With permission from Lakshmi, Glastonbury 2009.)

What is the treatment in this condition?

• Microsurgical resection

• Stereotactic radiosurgery (N Engl J Med 1998;339:1426–33)

• Conservative approach.

Mention some tumours that occur in families with familial adenomatous polyposis

Papillary thyroid carcinoma, sarcomas, hepatoblastomas, pancreatic carcinomas, and medulloblastomas of the cerebellar–pontine angle of the brain.

FT Schwann (1810–1882), a German anatomist, was Professor of Anatomy in the Louvain. He was one of the first to demonstrate that fermentation was associated with living organisms. Independently from Schleiden, he concluded that plants are formed of cells; this is known as the Schleiden–Schwann cellular theory. Schwann also discovered that the upper oesophagus contains striated muscle. He discovered pepsin and showed that bile was essential for digestion.

The first surgical removal of an acoustic neuroma was performed in 1894 (N Engl J Med 1998;339:1471).

L Leksell was the first to use radiosurgery, what he called the ‘gamma knife’ (Acta Chir Scand 1971;137:763–5).

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