The duration and the degree of oxygen deprivation dictates the subsequent degree of injury to the brain, but the exact duration and degree are often unknown so the extent of injury may not be recognized until days, weeks or months following the event. Brain Tumors Growths or tumors in the brain may be single or multiple. They may invade or compress brain cells. Infections Infections of the brain may be caused by bacteria or by viruses. A bacterial infection may be localized, forming an abscess, or diffuse, causing a cerebritis or encephalitis.
Viral infections tend to be diffuse, causing a viral encephalitis.
If the coverings of the brain are infected, the term meningitis is used. When an infection involves the ventricles, a ventriculitis is diagnosed. These infections may occur in association such as in a meningo-encephalitis. The severity of the injury to the brain depends on the virulence of the bacteria or virus and the degree of inflammation and swelling that it provokes in the brain. Sleepy, but arousable.