Brain Abscess

What is a brain abscess?

A brain abscess is a collection of pus enclosed in the brain tissue, caused by a bacterial or fungal infection. A brain abscess can develop as a complication of an infection, trauma, or surgery. They are rare, although people with weakened immune systems (such as people with HIV or those who have received an organ transplant) are more likely to get a brain abscess.

This type of infection usually begins in one of these ways:

It spreads from a nearby site, such as a middle ear infection, sinus infection, or dental abscess.
Blood carries the infection from another part of the body to the brain.
Infectious organisms enter the brain through a penetrating injury such as a gunshot wound, or from neurosurgical procedures or facial trauma.

Symptoms of brain abscess

Symptoms vary depending on the size and location of the abscess. More than 75% of people with a brain abscess have a dull, achy headache. For many people this is the only symptom. The pain usually is limited to the side of the brain where the abscess is, and the pain usually becomes worse until the abscess is treated. Aspirin and other pain medications do not relieve the pain.

About half of the people with a brain abscess have a low-grade fever. Other symptoms may include nausea and vomiting, neck stiffness, seizures, personality changes, and muscular weakness on one side of the body.

Diagnosing brain abscess

Diagnosing a brain abscess can be challenging because the early symptoms are so general. For example, there are many causes of headaches that are far more common than brain abscess. For this reason, the diagnosis of brain abscess is often not made until about two weeks after symptoms first develop. In some cases, people with brain abscesses develop seizures or neurological changes, such as muscle weakness on one side of the body, before the diagnosis is made.

If your doctor is concerned you have a brain abscess, he or she will ask about your medical and travel history to determine your risk of having certain infections. The doctor also will ask if you have any of the symptoms of brain abscess. If you do, he or she will ask when they started, how they've progressed, and whether you've had a recent infection or any trauma that could predispose you to a brain abscess.

To diagnose a brain abscess, you will need imaging tests such as computed tomography (CT) or magnetic resonance imaging (MRI) scans. These provide pictures of the inside of the brain, where an abscess often has a distinct appearance. Blood and other body fluids may be studied to find the original source of the infection. If the diagnosis remains uncertain, a neurosurgeon may sample the fluid within the abscess with a fine needle or surgically remove part of it.

Expected duration of brain abscess

A brain abscess can grow very quickly, typically becoming fully formed within about two weeks or so. Your doctor will begin treatment immediately after you are diagnosed. Prompt medical attention is the key to relieving your symptoms more quickly and minimizing damage to your long-term health. Surgical drainage of the abscess is often necessary as well.

Preventing brain abscess

Some brain abscesses are related to poor dental hygiene or complex sinus infections. You should floss daily, brush your teeth properly, and visit your dentist regularly. Treat sinus infections with decongestants. If symptoms of a sinus or dental infection persist, you may need an antibiotic.

People with untreated HIV infection are at increased risk of brain abscess. You may be able to prevent infection with HIV by not having sex, practicing safe sex, not sharing needles, and/or taking HIV prevention medicines. If you have HIV, you substantially reduce your chance of developing a brain abscess by taking antiviral medications regularly.

Treating brain abscess

Treatment of a brain abscess typically requires a two-pronged approach.

Treating the infection with antibiotics: If the specific type of bacterium is known, a targeted antibiotic is used; otherwise, broad-spectrum antibiotics are given to kill a large number of possible infectious agents. Antibiotics usually are continued for six weeks or more to make sure that the infection is eliminated.
Draining or removing the abscess: If the abscess can be reached easily and there is little danger of damaging the brain, the abscess may be surgically removed. In other cases, the abscess is drained, either by cutting it or by inserting a needle.

To confirm that the treatment was successful, you will be monitored by repeat magnetic resonance imaging (MRI) or computed tomography (CT) scans. If seizures are a problem you may need anticonvulsant medications, which may continue even after the abscess has been successfully treated.

When to call a professional

See your doctor if you experience a nearly constant headache that gets worse over several days or weeks. If you also have nausea, vomiting, seizures, personality changes, or muscle weakness, seek emergency care.

Prognosis

Without treatment, a brain abscess can be fatal. Most people with a brain abscess are treated successfully. Unfortunately, long-term neurological problems are common even after the abscess is removed and the infection is treated. For example, there may be lingering problems with body function, personality changes, or seizures due to scarring or other damage to the brain.