Bacterial, Fungal and Parasitic Infections of the Central Nervous System

Abstract

There are acute and chronic forms of bacterial infections of the CNS. The infection may be primarily localised in the subarachnoid space and ventricular system, i.e. bacterial meningitis and ventriculitis, or may involve the parenchyma of the brain itself leading to the formation of a cerebral abscess. On rare occasions, infections may cause subdural abscesses or involve the epidural spaces with secondary spread to the subarachnoid space or to the parenchyma of the brain. Bacterial infections may spread to the brain and spinal cord either by haematogenous routes or by direct spread from surrounding tissue. Thus bacterial meningitis or cerebral abscess may occur as complications of head injury when fractures at the base of the skull perforate the meninges or even perforate the brain itself. Furthermore, infection in the bones of the skull, as in chronic otitis media or chronic petrositis may lead to secondary invasion of the brain. Infection may also spread to the subarachnoid space from a primary site of infection in the paranasal air sinuses. In some cases, bacterial infections of the CNS are a complication of malignant disease in which erosion of the bones of the skull or spine has occurred; the infection thus enters the brain through a break in the meninges.