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Alternative namesAbscess - brain; Cerebral abscess; CNS abscess
A brain abscess is a mass of immune cells, pus, and other material that can occur when the brain is infected by bacteria or fungus.
Causes, incidence, and risk factors
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 in response to the inflammation, and the mass may put pressure on delicate brain tissue. Infected material can block the blood vessels of the brain, further damaging tissues by causing cell death and swelling of additional cells. Multiple abcesses are uncommon except in immunocompromised patients.
Infectious agents gain access to the brain in several ways. The most common way is through infected blood. Ear and sinus infections may also spread directly to the brain because of their close proximity.
Symptoms may develop gradually or suddenly. There may be little or no sign of general infection throughout the body. Early symptoms are usually headache , muscle weakness , visual changes, difficulty with balance or coordination, or seizures .
People at higher risk include those with congenital heart diseases , such as Tetralogy of Fallot , and people with congenital blood vessel abnormalities of the lungs, such as Osler-Weber-Rendu disease. These disorders carry a high risk of infection of the heart or lungs, which can then spread to the brain. People with HIV infection or other conditions that compromise the immune system are also at higher risk.
Note: Symptoms may develop gradually, over a period of 2 weeks, or they may develop suddenly. Once symptoms occur, they progressively worsen.
Signs and tests
A neurologic examination will usually reveal increased intracranial pressure and problems with brain function causing confusion or other problems. The problems will relate to the area of the brain where the abscess is located. The physician will look for the possible source of the infection.
Cerebral abscess is a medical emergency. Intracranial pressure may become high enough to cause death. Hospitalization is required until the condition is stabilized.
Antimicrobials are given, initially through a vein, then by mouth. Antibiotics which work against a number of different bacteria (broad spectrum antibiotics) are the most common antimicrobial prescribed. It is not uncommon for multiple antibiotic medications to be used in order to ensure effective treatment of the infection. Antifungal medications may also be prescribed if fungal infection is likely.
The presence of a compressive lesion (which is injuring brain tissue by pressing on it) or a large abscess with a high degree of swelling around it can raise intracranial pressure to the point where immediate treatment is needed.
Surgery is required if there is persistent or progressive increase in intracranial pressure, if the mass does not reduce after use of antimicrobial medications, or if the mass contains gas (produced by some types of bacteria). Surgery may also be needed if there are signs of impending rupture of the abscess into the fluid containing system of the brain (the ventricles).
Osmotic diuretics and steroids may also be used to reduce swelling of the brain.
If untreated, the disorder is almost always fatal. The outcome is usually improved with the use of CT and MRI scans for accurate diagnosis and by the administration of broad-spectrum antimicrobials.
The death rate is around 10% with treatment. Neurologic changes may be chronic or may resolve over time. Seizures or neurologic losses (inability to move, speak, see) may occur after surgery.
Calling your health care provider
Go to the emergency room or call the local emergency number (such as 911) if symptoms suggestive of brain abscess occur. Cerebral abscess is a medical emergency!
The risk of developing a cerebral abscess may be reduced by treating any disorders that can cause them. Such treatment should include a follow-up examination after infections are treated.
Preventive antibiotics given for people with congenital or rheumatic heart disorders prior to dental or urologic procedures may reduce the risk.
Update Date: 2/20/2003Elaine T. Kiriakopoulos, M.D., M.Sc., Department of Neurology, Beth Israel Deaconess Medical Center, Harvard University, Boston, MA. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT