Introduction

There is increasing interest in outcome measurement associated with the management of patients with tumours affecting the central nervous system. This interest is largely the result of the significant costs of diagnosis and therapy, and also relates to the nature and extent of neurological disabilities which have a tremendous impact on both public health and economic productivity.

Brain tumours rank second in relative incidence of tumours of childhood and from sixth to eighth among tumours of adults, depending upon whether pituitary tumours and tumours metastic to the brain are included (Berens et al. 1990, Black 1990, Walker et al. 1985). The most common primary brain tumours are the gliomas. These include the astrocytoma which appears in benign and malignant forms, the glioblastoma which is a highly malignant astrocytoma and the oligodendroglioma. The gliomas comprise approximately 40–60% of primary brain tumours, and of these about half fall into a relatively benign category and half into a rapidly progressive, more malignant, classification. Other tissues within the brain also give rise to tumours and these include the ependyma and the choroid plexus. Primitive developmental tumours such as the primitive neuroectodermal tumour (PNET), medulloblastoma, ependymoblastoma and the pineoblastoma may occur, usually appearing in infancy and childhood.

The second most common type of intracranial tumour is the meningioma (Barbaro et al. 1987) that arises from the lining of the skull and produces symptoms by external pressure on the brain. These tumours are considered ‘extra-axial’ lesions and occur more commonly in women and in older patients.

As neurology and neurosurgery become more and more concerned with therapy there is a need to consider the results of the different treatment options in a strictly comparative mode. As new strategies for treatment of these disorders are devised the question has to be asked whether any new treatment supersedes, becomes part of the management of a condition, or is used only in certain circumstances. Since much treatment in neurology and neurosurgery has been developed empirically, evidence for efficacy is, in many instances, surprisingly sparse. Other treatments, for example, the treatment of cerebral aneurysms, or the use of aspirin in stroke prevention have been subjected to rigorous evaluation in multi-centre and, in some instances, in international clinical trials. In this book most conditions treated by neurologists or neurosurgeons are discussed in relation to the outcome of treatment. Only when the outcome of a given therapy is known can its value in relation to other treatments be considered, and full, informed advice be given to a patient. In a sense, this process is an extension of knowledge about prognosis. The reader will notice in this book the different approaches to the problem of outcome taken by the authors of the different chapters, and reflect that these relate to the differing levels of effectiveness of treatment, or of understanding of the disease under discussion. In some areas it is apparent that there is much data but, in others, the data are more descriptive than analytical. Clearly, there is a long way to go in the search for conquest of neurological disease.

Viral meningitis

Viral meningitis is a common illness, particularly amongst children, and is most often caused by enteroviruses. There is a tendency to equate the syndrome of aseptic meningitis with that of viral meningitis. A distinction should be made, however, since a large number of disorders with varying and sometimes serious outcomes can mimic viral meningitis. On the other hand, the prognosis of viral meningitis is very good, and the disease is rarely fatal, though death due to concurrent myocarditis has been reported in patients with coxsackievirus meningitis. Almost all patients with viral meningitis recover spontaneously; in those who develop serious neurological sequelae, care should be taken to exclude other aetiologies, such as partially treated bacterial meningitis.

The acute illness may be complicated by either complex partial seizures, physical evidence of increased intracranial pressure, or coma in approximately 9.0% of cases. The risk of acute neurological complications is slightly higher in neonates than in older children or adults, but appears to be similar among patients infected with group B coxsackie viruses and echoviruses, the two major enteroviruses causing viral meningitis. Follow-up studies have shown that 5–20% of patients with viral meningitis develop transient post-meningitic disorders, especially prolonged episodes of stress-induced headache. The risk of long-term neurological sequelae, however, is very small indeed (Table 21.1). Long-term prognosis in patients who develop acute complications appears to be as favourable as that for patients who do not experience acute complications.

Although the neurological outcome of viral meningitis is generally good, infection with certain viruses carries a less favourable outcome.