Cranial bacterial infection.

Early diagnosis of cranial sepsis is mandatory if morbidity is to be avoided. In the case of structural integrity of the skull, haematogenous spread or extension from adjacent structures, especially the sinuses, are the most common sources of infection. Infections may be limited to compartments by the meninges or spread diffusely. Focal disease includes brain abscess as well as subdural and extradural empyaema. A history or signs of sinus disease should always be sought. Tuberculosis, lyme disease and listeriosis may present specific pathological findings. A series of cases is presented to illustrate the role of imaging in infective disease and to draw attention to diagnostic and management points of which radiologists should be aware.