Brain Abscess Fast Facts

Brain abscesses are very rare: less than 20,000 US cases are reported yearly. A brain abscess is often the result of an infection in the head or body that spreads to the brain. Prompt treatment of a brain abscess is essential to prevent long-term damage or fatal consequences.

Without treatment, a brain abscess can lead to long-term neurological problems or even death.

Having a compromised immune system can put you at risk of developing a brain abscess. People with HIV/AIDS or other conditions that affect the immune system and those using immune-suppressant drugs are at increased risk.

United Brain Association

Prompt treatment of a brain abscess is essential to prevent long-term damage or fatal consequences.

What is a Brain Abscess?

A brain abscess, sometimes also called a cerebral abscess, is an infection in the brain usually caused by bacteria or other microorganisms. The infection creates a pocket within the brain tissue filled with bacteria, white blood cells from the patient’s immune system, pus, and fluid. As the pocket of infection grows, it can put pressure on sensitive brain tissue and cause damage. It can also block blood flow to other parts of the brain, causing even more widespread damage. In the worst cases, the condition can be fatal.


Symptoms of a brain abscess include:

  • Dull, Achy, Persistent Headache
  • Fever and/or chills
  • Vomiting
  • Seizures
  • Dizziness
  • Sleepiness, fatigue, or loss of consciousness
  • Confusion or disorientation
  • Neck stiffness
  • Weakness on one side of the body
  • Speech difficulties
  • Vision difficulties
  • Movement difficulties
  • Changes in personality

Most often, the symptoms develop within days or weeks as the abscess grows, but sometimes the signs aren’t noticeable until the abscess is well advanced. Some symptoms such as fever and chills may occur early in the course of an infection, even before an abscess begins putting pressure on the brain tissue.

What Causes A Brain Abscess?

A brain abscess develops when bacteria, fungi, or other microorganisms invade brain tissue, and the area of infection is contained by surrounding tissue. This causes an expanding capsule of pus and fluid to put pressure on healthy tissue. Sometimes the infection spreads from an area of infection elsewhere; common origin points include sinus infections, ear infections, dental infections, and endocarditis (an infection of the lining of the heart).

A head injury that penetrates the skull can result in an infection in the brain. An infection leading to an abscess can also occur as a result of invasive neurosurgery.

The type of bacteria (or other microorganisms) that causes a brain abscess can vary depending on the source of the original infection:

  • Staphylococci (staph) infections are often associated with head injuries, endocarditis, or infections arising after surgeries.
  • Enterobacteriaceae are often associated with ear infections, and the bacteria may migrate to the brain if the infection is left untreated.
  • A protozoa called toxoplasma gondii is common in patients with HIV/AIDS. The organism is a common culprit in brain abscesses.

Is A Brain Abscess Hereditary?

The most common causes of infections that lead to brain abscesses come from external environmental sources, and family history plays no part in developing an abscess. However, certain inherited conditions may make an infection more likely and put a patient at increased risk of a brain abscess.

For example, an inherited condition called hereditary hemorrhagic telangiectasia (HHT)–also called Osler-Weber-Rendu syndrome–causes abnormal blood-vessel formation in the skin, mucous membranes, and internal organs. When this condition causes blood-vessel abnormalities in the lungs, patients are about 400 times more likely to develop a brain abscess than the general population.

How Is A Brain Abscess Detected?

Early detection of a brain abscess is essential because long-term damage is more likely to occur if treatment is delayed until symptoms are advanced. Unfortunately, early diagnosis of a brain abscess is difficult because the first symptoms are usually vague and may be caused by a wide variety of problems other than an abscess.

For more than three-quarters of brain abscess patients, the first sign is a dull headache. Sometimes the headache is confined to one side of the head, and it is often the only symptom that occurs during the early stages of the problem. As the abscess grows, the headache usually becomes more severe, and over-the-counter pain relievers typically don’t make the pain go away.

Another common early symptom of an abscess is a low-grade fever.

If the abscess is left untreated, more severe symptoms, such as vomiting, stiff neck, seizures, personality changes, and weakness on one side of the body may develop.

How Is A Brain Abscess Diagnosed?

Because the early symptoms of a brain abscess are typically so non-specific, doctors don’t often suspect an abscess until more pronounced and definitive symptoms begin to emerge. This can delay diagnosis by as much as two weeks from the onset of the initial symptoms.

When your doctor suspects a brain abscess may be present, he or she may follow a diagnostic procedure that includes:

  • Medical history questions. Your doctor will look for signs that you may be at increased risk for certain kinds of infections. The doctor will also look for evidence of a prior infection that could have migrated to your brain.
  • Blood tests. These laboratory tests will look for signs of infection in your bloodstream.
  • Imaging tests. Magnetic resonance imaging (MRI) and computerized tomography (CT) scans can be used to produce an image of your brain. An abscess is likely to show up on these scans.
  • Testing of the abscess. Doctors may remove a sample of the abscess using a fine needle. Tests of this sample can identify the source of the infection and allow for more effective treatment.

How Is A Brain Abscess Treated?

Treatment of a brain abscess usually involves drugs aimed at eliminating the infection source and relieving the pressure caused by the growing abscess.

  • Antibiotics such as cefotaxime, ceftriaxone, or metronidazole are often used to treat bacterial infections.
  • Vancomycin is often used to treat staph infections.
  • Corticosteroids are sometimes used to reduce inflammation and swelling caused by the abscess.
  • Anti-seizure medications may be used to treat or prevent seizures.

Unless the abscess is very small, the drainage of the abscess is usually necessary. This will require surgery, and the abscess is usually removed, if possible, during the surgery. If the abscess is not easily accessible, it may be drained using a needle guided by CT or MRI imaging.

How Does A Brain Abscess Progress?

Brain abscesses often grow very quickly, and they may become large enough to cause significant symptoms within two weeks. As the growing abscess exerted pressure on healthy brain tissue, symptoms will likely become more severe, and long-term damage is possible.

Treatment of brain abscesses is usually successful. However, long-term effects such as seizures, personality changes, or difficulties with a function elsewhere in the body are common even after successful treatment.

Left untreated, a brain abscess may be fatal.

How Is A Brain Abscess Prevented?

The most effective way to prevent a brain abscess is to prevent the infections that can lead to an abscess.

  • Practice good dental and oral hygiene. Brush and floss correctly and regularly, and see a dentist on a regular schedule.
  • If you have a sinus infection, use a decongestant to prevent the infection from becoming more severe.
  • See a doctor if a dental or sinus infection won’t go away. You may need prescription antibiotics to eliminate the infection.
  • If you have HIV, use antiviral medications to decrease your susceptibility to infections, and take the medicines regularly as prescribed.
  • Go to your doctor if you have a headache that lasts (and/or gets worse) for days or weeks.
  • Seek emergency treatment if you have seizures, vomiting, nausea, muscle weakness, or personality changes.

Brain Abscess Caregiver Tips

In severe cases, brain abscesses can result in profound symptoms and personality changes that may prevent the sufferer from functioning effectively in their daily lives. An abscess may also occur in conjunction with a brain injury or surgery that introduces their own demands and responsibilities on caregivers.

If you are a caregiver for a loved one with a brain abscess, keep these tips in mind:

  • Attend doctor appointments with your loved one so that you can understand the diagnosis, the treatment plan, and the expectations for recovery.
  • During recovery, provide a comfortable space for the sufferer free from noise, excessive stimulation, and stress.
  • Work with your loved one’s medical providers after treatment to learn how you can best support them as they recuperate. Understand the goals of any long-term therapies, and be realistic about expectations.
  • Call upon family and community to help out whenever possible. Don’t try to take sole responsibility for caregiving.

Brain Abscess Brain Science

Some recent research into the diagnosis and treatment of brain abscesses has focused on treating unusual cases and assessing current treatment.

  • One study examined cases of “cryptogenic brain abscess,” in which the symptoms and the patient’s medical history didn’t fit the typical pattern associated with abscesses, and the source of the infection was unknown. Cryptogenic brain abscesses often elude diagnosis, and their prognosis is consequently poor. The research aims to help practitioners recognize unusual patterns of presentation to improve the outcome in these cases.
  • A recent survey looked at the advances made in the diagnosis and treatment of brain abscesses over the past several years to determine whether or not medical advances have positively impacted the treatment of the disease. The survey concluded that advances in imaging technologies, antibiotic therapies, and neurosurgery techniques have significantly improved brain abscess patients’ prognosis.

Brain Abscess Research

Title: BIGlobal Intervention Study: Improving Diagnosis and Management of Suspected Brain Infections Globally

Stage: Recruiting

Principal investigator: Tom Solomon, PhD

Institute of Infection & Global Health, University of Liverpool

Liverpool, UK

Background: Patients with suspected brain infections pose major challenges to low and middle-income countries, including their disproportionately high burden, diverse causes with inadequate surveillance, the requirement for invasive and expensive tests, and the difficulty of management without a clear diagnosis. This is all compounded by resource and system constraints. Few studies have attempted to improve the care of these people in resource-limited settings.

Aim: This study sets out to improve the diagnosis and early management of people with suspected acute (<28 days of symptoms) brain infections in low and middle-income countries, using a coordinated thematic approach.

Outcomes: The primary outcome will be a proportion of people with suspected acute brain infection receiving a diagnosis. Secondary outcomes will include mortality, length of stay in the hospital, quality of life, degree of disability, and proportion having a lumbar puncture test.

Title: Partial Oral Antibiotic Treatment for Bacterial Brain Abscess (ORAL)

Stage: Recruiting

Principal investigator: Jacob Bodilsen, MD

Aalborg University Hospital

Aalborg, Denmark

Treatment of brain abscess remains a considerable challenge due to the infection’s precarious location and the impenetrability of the blood-brain barrier for most drugs. Thus, cure usually requires a combination of neurosurgical evacuation of abscess material and 6-8 weeks of high-dose intravenous (IV) antibiotic therapy to eradicate bacteria within the abscess cavity. Disadvantages include risks of nosocomial infections and line-associated complications (e.g., bleeding, venous thrombosis, or need for replacement due to malfunction) in addition to the considerable costs of such long-term admission. However, improved insights into the pharmacokinetic properties and favorable bioavailability of some oral antibiotics may allow such treatment at an early stage. To date, there are no randomized controlled trials to guide the treatment of bacterial brain abscesses.

The investigators wish to determine whether a treatment strategy of transition to oral antibiotics after two weeks of treatment is non-inferior to continued IV antibiotics in clinically stable brain abscess patients assessed by the proportion with a favorable outcome at six months since randomization.

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