Brain abscess is a serious disorder that occurs when germs that produce pus get into the inner parts of the brain. The great majority of brain abscesses occur when infection spreads to the brain from elsewhere in the body, mostly from infections in nearby areas.
About one-third of them occur by spread of germs in the blood from a septic area in the lungs, or from a serious heart condition called bacterial endocarditis.
In children, most brain abscesses are associated with congenital heart disease.
Symptoms of an infection in the brain
The effects of a brain abscess depend on its position and on the amount of damage or local compression caused. Some abscesses cause no symptoms (silent abscesses), but most will cause some of the following effects, in order of decreasing frequency:
- Slowness of thinking
- Seizures (fits)
- Loss of sensation
- Speech disorder
- Sight loss (of field of vision)
Abscesses in the lower rear brain (the cerebellum) cause loss of balance, staggering walk and a coarse jerkiness of the eyes.
Causes of brain infection
The organisms may have spread through the bone following middle-ear infection (otitis media and mastoiditis) or severe sinusitis, or may have spread by way of the blood, often as a complication of lung abscess. A brain abscess may also arise when the brain has been injured by penetration with an infected object or missile.
How to diagnose brain abscess?
Brain abscesses are identified by a computerized tomography scan (CT scan) or magnetic resonance imaging (MRI scan).
Brain abscesses are treated with intensive antibiotic therapy at a very large dosage. The doses used are many times those customary for other infections. 24 million units of penicillin and 6 grams of chloramphenicol are commonly given directly into a vein. Metronidazole is also often given in large doses.
Surgery is avoided in the early stages as it is likely to do more harm than good, but rising pressure within the skull may make it necessary to drain away pus. In cases where treatment is begun before the patient lapses into coma, the survival rate is 85-90%.