Epidemiology
Brain tumours account for 2–5% of all cancers and 2% of cancer deaths. Metastases to the brain are more common than primary brain tumours and often arise from cancers of the lung, breast, skin (melanoma) and kidney. Furthermore, nasopharyngeal cancers can extend directly through the foramina of the skull and involve the brain. Meningeal metastases occur with systemic spread from leukaemia, lymphoma, breast cancer and small-cell lung cancer, and from local extension of medulloblastoma and ependymal gliomas. Fewer than 20% of CNS tumours occur in the spinal cord. The types of cancer of the CNS are outlined in Table 47.1.
Aetiology
The cause of most adult brain tumours is not known. Several inherited phakomatoses are associated with brain tumours that tend to occur in children or young adults and include:
- tuberous sclerosis (gliomas, ependymomas);
- Li–Fraumeni syndrome (glioma);
- Turcot syndrome (gliomas);
- neurofibromatosis type I (cranial and root schwannomas, meningiomas, ependymomas, optic gliomas);
- von Hippel–Lindau disease (cerebellar and retinal haemangioblastoma);
- Gorlin’s basal naevus syndrome (medulloblastoma).
Clinical presentation
Glial tumours
General symptoms include those produced by mass effect; increased intracranial pressure, oedema, midline shift and herniation can all produce a progressive altered mental state, personality changes, headaches, seizures and papilloedema. Focal symptoms depend on the location of the tumour. Fewer than 10% of primary seizures are due to tumours and only 20% of supratentorial tumours present with seizures.
Meningioma
These tumours present as a slowly growing mass that can produce headache, seizures, motor and sensory disturbance, and depending on their site, cranial neuropathies. Meningiomas can produce characteristic changes on plain skull radiographs with bone erosion, calcification and hyperostosis. They are more common in women.
Spinal axis tumours
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