Abstract
Meningitis is usually caused by a virus, in which case the prognosis is good and the treatment usually symptomatic. Bacterial meningitis is far less common, but its progression is far more severe. Encephalitis or meningoencephalitis also involves inflammation of the brain parenchyma. The key symptoms of all these infections are headache and fever. Both of these are non-specific symptoms and need not both be present, and by no means every patient with these symptoms will have an intracranial infection. Diagnosing infections of the central nervous system and meninges can therefore be difficult, especially in very young and very old patients, who generally display far less classic symptoms.