CLINICAL RISK REDUCTION


Brain tumours T


Professor Paul Marks offers some key insights in dealing with suspected intracranial tumours


HIS article will highlight some of the difficulties that can arise when managing patients with intracranial tumours. Neuro-


oncology is a complex and constantly evolving subject but nevertheless certain fundamental principles apply which if attended to will avoid or minimise clinical and medico-legal problems. Interested readers are advised to consult standard texts and, in particular, the relevant NICE guidelines – Improving outcomes for people with brain and other CNS tumours (www.nice.org.uk/csgbraincns).


Scale of the problem It is important to point out that primary CNS tumours are rare, and the average general practitioner will be unlikely to see more than a handful of cases throughout his practising lifetime. CNS tumours account for 1.6 per cent of cancers in the UK. Despite their relative rareness, there are many


histological subtypes and classification is complex. Te use of terms such as benign or malignant which have a readily understandable and clear-cut meaning when discussing tumours outside the CNS are less helpful when considering brain tumours. Benign tumours tend to be extra-axial, that is they


do not arise in the substance of the brain but rather from the meninges, cranial nerves or other structures and produce their effects by compressing the brain from without. Tere are of course histologically benign intra-axial


tumours such as low-grade pilocytic astrocytomas which arise within the substance of the brain. Malignant tumours which can be primary or secondary tend to be intra-axial. Glioma is a generic term which suggests that a


tumour arises from one of the lines of glial cells such as astrocytes, oligodendrocytes or ependyma. High- grade gliomas, such as glioblastoma multiforme, are common malignant tumours that arise in adults and have a notoriously poor prognosis. A meningioma, which is a benign tumour, can


nevertheless prove fatal if it causes raised intracranial pressure or leads to status epilepticus. Pituitary adenomas are also benign and can cause blindness by compression of the optic apparatus.


14 It will be readily appreciated that the


classification of brain tumours is complex but the WHO 2007 classification is the most comprehensive and accepted system currently employed*. Treatment is complex and should


always be discussed in a multidisciplinary team setting but may consist of surgery alone or supplemented by adjuvantmeans such as radiotherapy or chemotherapy. Te gamma knife which provides focused irradiation in a single session is finding increased use, especially in the management of metastatic disease and small benign tumours such as acoustic neuromas in suitable patients.


Presentation of brain tumours Clinical presentations of brain tumours include:


• Symptoms and signs of raised intracranial pressure • Epilepsy • Focal neurological deficit • Endocrine disturbance •


Incidental finding.


Headache due to raised intracranial pressure typically has a diurnal variation and is worse in the morning. It can be associated with vomiting, and examination of the fundi may reveal papilloedema. Focal deficit is obviously variable and will be


determined by which area of the brain is involved. For example, a tumour in the right occipital lobe can produce a leſt homonymous hemianopia, a pituitary adenoma can cause chiasmatic compression, a bitemporal hemianopia or a leſt temporal lobe tumour may be associated with dysphasia and so forth. Epilepsy of new onset in an adult patient should raise


suspicion of an underlying tumour and investigation is mandated by CT or MRI scanning of the brain. If such tests suggest that the lesion is likely to be a metastasis then further imaging directed at locating the likely primary site is carried out and this typically should include a CT scan of the thorax, abdomen and pelvis.


SUMMONS


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