Cerebral neoplasia
Description
- Metastases are the commonest intracranial tumour overall - roughly 10x the incidence of primary brain tumours
- Primary brain tumours essentially never metastasise outside the CNS - they kill by local progression
Vestibular schwannoma - the classic exam lesion
- Arises from the vestibular division of CN VIII in the internal auditory meatus, growing into the cerebellopontine angle
- As it enlarges it compresses, in order:
- CN VIII - unilateral sensorineural hearing loss and tinnitus (speech discrimination worse than the audiogram predicts), imbalance rather than true vertigo
- CN V - loss of the corneal reflex (the earliest trigeminal sign), facial numbness
- Cerebellum - ipsilateral ataxia, nystagmus
- Brainstem - long tract signs, hydrocephalus
- *CN VII is remarkably resistant - facial weakness is late. A facial palsy early in a CPA mass suggests a facial nerve schwannoma or malignancy*
- Bilateral vestibular schwannomas = neurofibromatosis type 2
Other CPA masses
- Meningioma, epidermoid cyst, facial nerve schwannoma, metastasis, glomus jugulare
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