Published online by Cambridge University Press: 05 November 2015
This chapter describes the management of tumours in adults in the following anatomical areas: cerebral convexity and cerebral hemispheres, the skull base, the pituitary, the pineal region and the spinal cord.
Central nervous system (CNS) tumours are heterogeneous. The terms malignant and benign are not very useful because:
• even small slowly growing tumours can cause severe symptoms because the brain is enclosed in a rigid skull;
• surgery can be diffi cult because many tumours are infi ltrating and oft en lie close to critical structures;
• most of these tumours rarely, if ever, metastasise outside the CNS;
• slow-growing tumours may transform into a much more aggressive variant.
This chapter does not deal with metastatic disease to the CNS that is considered in other relevant chapters, although management of cerebral metastases that require specialist neuro-oncology input is discussed briefly. CNS tumours in children are considered in Chapter 40.
The tentorium separates the supratentorial from the infratentorial areas of the brain. The motor and sensory cortices lie at the central sulcus. Broca's area (frontal above the lateral sulcus) is responsible for expressive speech, and Wernicke's area (temporal, posterior end of the lateral sulcus) is responsible for receptive speech. The ventricular system is lined with ependymal cells. CSF travels from the third to the fourth ventricle through the cerebral aqueduct and from the fourth ventricle to the subarachnoid space through the foramina of Magendie (median) and Luschka (lateral).
The anterior and intermediate lobes of the pituitary arise from Rathke's pouch. The cavernous sinuses transmit cranial nerves IIV, IV, VI and the maxillary branch of V.
Incidence and epidemiology
Primary brain and CNS tumours are fairly common. The incidence of disease is approximately 15 in 100,000 per annum. In 2011, 9365 primary tumours of the brain and CNS were registered in the United Kingdom, where brain tumours account for 3% of all cancers. Approximately 5000 deaths occur per year in the UK that are attributable to primary brain and CNS tumours. (http://www.cancerresearchuk.org/cancer-info/cancerstats/, accessed October 2014). On an average, GPs in England see one patient with a brain tumour every 7 years.
For high-grade brain tumours the peak disease incidence occurs in the 70–80-year-old age group. There has been an increase in recent years, probably because of increased investigation.