Brain abscess

Definition

A brain abscess is a mass of immune cells, pus, and other material due to a bacterial or fungal infection.

Alternative Names

Causes

Brain abscesses commonly occur when bacteria or fungi infect part of the brain. Inflammation develops in response. Infected brain cells, white blood cells, and live and dead microorganisms collect in a limited area of the brain. This area becomes enclosed by a membrane that forms around it 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 and 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 common reach the brain through the blood. The source of the infectious organism is often not found. When identified, 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 congenital heart disease or 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:

• Right-to-left heart shunts
• Chronic disease, such as cancer or Osler-Weber-Rendu syndrome
• A weakened immune system (such as those seen in AIDS patients
• Immunosuppressants (corticosteroids)