Alternate Names : Abscess – brain, Cerebral abscess, CNS abscess
A brain abscess is a collection of immune cells, pus, and other material in the brain, usually from a bacterial or fungal infection.
Overview, Causes, & Risk Factors
Brain abscesses commonly occur when bacteria or fungi infect part of the brain. Swelling and irritation (inflammation) develops in response. Infected brain cells, white blood cells, live and dead bacteria, and fungi collect in an area of the brain. A membrane forms around this area and creates a mass.
While this immune response can protect the brain by isolating the infection, it can also do more harm than good. The brain swells. Because the skull cannot expand, the mass may put pressure on delicate brain tissue. Infected material can block the blood vessels of the brain.
The bacteria or fungi that cause a brain abscess commonly reach the brain through the blood. The source of the infection is often not found. However, the most common source is a lung infection. Bacteria or fungi may also travel from a nearby infected area (for example, an ear infection) or be introduced into the body during an injury (such as a gun or knife wound) or surgery.
In children with heart disease or a birth defect, such as those born with Tetralogy of Fallot, infections are more able to reach the brain from the intestines, teeth, or other body areas.
The following raise your risk of a brain abscess:
- A weakened immune system (such as in AIDS patients)
- Chronic disease, such as cancer or Osler-Weber-Rendu syndrome
- Drugs that suppress the immune system (corticosteroids or chemotherapy)
- Right-to-left heart shunts
Pictures & Images
Amebic brain abscess
Amebiasis, normally an infection of the intestinal tract, may spread and infect other organs such as the liver or brain. Infection of the brain can be fatal. In this slide, ameba are shown in a sample of brain tissue. Ameba represent a serious infection in immunocompromised individuals. (Image courtesy of the Centers for Disease Control and Prevention.)
The brain is that part of the central nervous system contained in the skull and is composed of cerebrum, cerebellum, pons and medulla oblongata.
Review Date : 9/17/2008
Reviewed By : David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Jatin M. Vyas, PhD, MD, Instructor in Medicine, Harvard Medical School, Assistant in Medicine, Division of Infectious Disease, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.