What causes a brain abscess?
Brain abscess (or cerebral abscess) is an abscess caused by inflammation and collection of infected material coming from local (ear infection, infection of paranasal sinuses, infection of the mastoid air cells of the temporal bone, epidural abscess) or remote (lung, heart, kidney etc.) infectious sources within the brain tissue. The infection may also be
introduced through a skull fracture following a head trauma or surgical procedures. Brain abscess is usually associated with congenital heart disease in young children. It may occur at any age but is most frequent in the third decade of life.
Although the most common organism causing brain abscess is a bacteria named as Streptococcus, a wide variety of other bacteria (Proteus, Pseudomonas, Pneumococcus, Meningococcus, Haemophilus), fungi and parasites may also cause the disease. Fungi and parasites are especially associated with immunocompromised patients. Organisms that are most frequently associated with brain abscess in patients with AIDS are Toxoplasma gondii and Cryptococcus neoformans, though in infection with the latter organism, symptoms of meningitis generally predominate.
There are three ways a virus or bacteria can enter the body and infect the brain. Infection is spread from another area of infection in the body. This accounts for approximately 20 to 50 percent of brain abscess cases. Infection is spread through the blood stream from the lung or chest area. Viral or bacterial germs enter directly into the brain through an open wound in the head. A person with HIV is more likely to have brain abscesses due to his or her weakened immune system. Brain abscesses expand over time, placing the surrounding brain at risk. If left untreated, the increasing size of the abscess will cause death.