Brain Abscess

What Is It?

A brain abscess is a bacterial brain infection. Also called a cerebral abscess, these infections are destructive lesions within the substance of the brain itself. An abscess is a general term for a walled off area of infection which includes the surrounding ring of tissue containing a liquified center filled with bacteria, white blood cells and fluid. This purulent fluid is also known as puss.

In the brain, an abscess can occur if bacteria is introduced into the brain. First leading to cerebritis, a local area of inflamed, infected brain tissue, as the infection grows it destroys brain tissue, leading to liquefaction and the formation of the puss-filled abscess.

The brain is usually sterile, without bacteria in or around it. But there are a number of things that can introduce bacteria into the brain which can lead to a brain abscess.

Sinusitis or Mastoiditis - One of the most common causes of cerebral abscess in otherwise normal patients is spread of infection from a local site of infection. Severe bacterial sinusitis or mastoiditis (infection of the mastoid air cells behind the ear) can lead to infiltration of the brain and a resulting abscess. Other infections from the head (such as oral infections) can also seed the brain occasionally.
Other Distant Infections - Other sources of infection can seed the brain, presumably from bacteria that travel in the blood and then are able to penetrate the brain tissue. For example, patients with bacterial endocarditis (infection of the heart valves) can flick off pieces of infectious material which can end up in the brain. Additionally, intravenous drug users can often introduce bacteria into their bloodstream which can lead to abscesses in various parts of the body.
Penetrating Injury or Surgery - Anything that directly deposits bacteria into the brain tissue can cause a resulting abscess. For example, a penetrating traumatic injury (knife, gunshot wound, etc.) that penetrates the skull into the brain. Abscess can also be a complication of surgery of the brain, although this is rare (superficial wound infections are much more common than actual brain infections).

The types of bacteria involved in a cerebral abscess varies depending on the cause and source of the infection.

What Types of Symptoms Are Typical?

Cerebral abscess can present with a number of different symptoms. General, non-specific symptoms that are common can include headache, fever, seizures, nausea and vomiting. More specific neurological symptoms depend on the size and location of the abscess. As it grows, damaging the brain tissue and causing swelling of the surrounding brain, it can cause focal neurological symptoms such as weakness, numbness, language difficulties, visual symptoms, etc. Large abscesses can increase intracranial pressure and can lead to a deteriorating level of consciousness and coma. If not treated, brain abscess can often be fatal.

How Is The Diagnosis Typically Made?

In a patient that presents with symptoms suggestive of abscess, a general neurological evaluation generally includes some form of imaging study, such as CT scan and/or MRI scan with contrast, to visualize the abscess. Contrast agents enhance the surrounding ring of the abscess and makes the diagnosis fairly straightforward, although some tumors and other infections can mimic a bacterial abscess.

Definitive diagnosis usually involves drainage of the abscess, allowing collection of the purulent fluid to be examined microscopically and to be cultured to identify the causative organism.

What Are Some Common Treatments?

Very early infections, including cerebritis and very small abscesses, may sometimes be given a trial of only medical treatment, consisting of intravenous antibiotics. However, because systemically administered antibiotics generally do not get into the abscess cavity, most brain abscesses require surgical drainage. The abscess is opened surgically and the infectious material is removed and washed out thoroughly. Any abnormal infectious tissue can be removed as well. Intravenous antibiotics are generally continued for a period of time following surgery. Additional treatment of the source of infection (sinusitis, mastoiditis, endocarditis, etc.) may be indicated.

Each patient is different. Discuss your appropriate treatment options with your own treating physicians.

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Important Note: This site is not intended to offer medical advice. Every patient is different, and only your personal physician can help to counsel you about what is best for your situation. What we offer is general reference information about various disorders and treatments for your education.

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