Brain Abscess Symptoms, Causes & Treatment Options

Brain abscesses are the result of infection and inflammation in the brain due to a virus, bacteria, fungi, or a parasite. Symptoms of a brain abscess include severe headache, fever, neck stiffness, nausea, vomiting, double vision, confusion, weakness, lethargy, and seizures.

What Is a Brain Abscess?

A brain abscess is a collection of inflammatory and infected material in the brain. Bacteria, viruses, fungi, and parasites are all capable of causing infections that may lead to brain abscesses.

Brain abscesses will usually cause severe headaches and fever. They may also cause other symptoms like neck stiffness, nausea, vomiting, double vision, confusion, weakness, lethargy, seizures, and other mental changes.

Brain abscesses can be very dangerous and require prompt evaluation and treatment. Treatments for brain abscesses vary based on the size, location, and cause of the abscess, but will usually require hospitalization for some combination of antimicrobial medications and surgical removal of the infection.

Call 911 immediately. A brain abscess is a medical emergency, as pressure inside the skull may become high enough to be life threatening.

Symptoms of a Brain Abscess

The symptoms of brain abscesses can be described by main symptoms as well as other symptoms that are likely in some people.

Main symptoms

The main symptoms of brain abscesses include the following.

  • Headache: The most common symptom seen in brain abscesses is headache. The headache can start suddenly or gradually and is usually located on the side of the head where the abscess is located. It tends to be severe and will not be relieved with over-the-counter pain medications.
  • Fever: About half of people with brain abscesses will develop a fever.
  • Neck stiffness: Some people with brain abscesses may develop neck stiffness. This can occur when the abscess is located in the back of the brain, or if the abscess leaks into a normally fluid-filled space in the brain.
  • Numbness or weakness in a part of the body: Some people with brain abscesses may develop new numbness or weakness in a part of the body, usually occurring on one side of the body only. This can occur if the brain abscess pushes on a part of the brain that is important for movement or sensation.

Other symptoms

Other symptoms that can occur in some people with brain abscesses include the following.

  • Double vision or difficulty speaking: Some people with brain abscesses may develop double vision or difficulty speaking if the brain abscess pushes on certain nerves in the brain that are important for movement of the eyes or for normal speech.
  • Seizures: In the typical type of seizures (grand mal seizure) caused by brain abscesses, the person's whole body will shake for a while and the seizure may be followed by a period of confusion.
  • Confusion or lethargy: Some people with brain abscesses may develop confusion or lethargy, where they seem to be thinking and acting slower than usual. This is a sign of a severe brain abscess that is causing swelling of the brain and increasing the pressure in the head.
  • Nausea and/or vomiting: Some people with brain abscesses may feel nauseous or throw up. This indicates the brain abscess is causing swelling of the brain and increasing the pressure in the head.

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What Causes a Brain Abscess?

A brain abscess occurs when bacteria or fungi infect a specific part of the brain. The infectious organism can get to the brain by either spreading directly from an adjacent area or through the bloodstream. Brain abscesses are more common in people who have weakened immune systems. This can happen if they have certain diseases such as HIV/AIDS or are taking certain medications such as steroids or other immunosuppressant medications. Specific common causes include the following.

  • Ear, sinus, or dental infection: The inside of the ear (near the eardrum), the sinuses, and the mouth are all located close to the brain, so an infection in one of these areas can spread directly into the brain if not properly treated.
  • Bullet wound or foreign body in the brain: Any foreign bodies that enter the brain, such as a pencil or a dart, can cause damage to the brain that then becomes infected, causing a brain abscess.
  • Brain surgery: Brain surgery can be complicated by a brain abscess. Although all efforts are made to keep the surgery sterile, any time a surgery is done there is always a risk of infection.
  • Infection in the blood: Any infection in the blood can lead to a brain abscess by spreading the infection through the bloodstream to the brain. The infection in the blood can originally start as a lung infection, skin infection, abdominal infection, or infection of the heart valves, among others. In these cases, there will usually be multiple brain abscesses, as the bacteria spread to multiple locations.

Treatment Options and Prevention for a Brain Abscess

For those with brain abscesses, antibiotics and the drainage of abscess contents are often necessary.

  • Antibiotics: People who have brain abscesses will require antibiotic medications to treat the infection. These antibiotic medications will need to be given for four to eight weeks and will need to be given through an IV because medications taken by mouth cannot reach high enough levels in the brain. A broad combination of antibiotics to cover many possible infectious organisms will be used to start and then subsequently narrowed down to a few antibiotics that target the specific organisms causing the infection. Possible antibiotic medications that may be given include metronidazole (Flagyl), ceftriaxone, meropenem, or vancomycin, among others. In some cases, the physician may add an antifungal medication in case a fungal organism is causing the infection.
  • Aspiration of abscess contents: All people who have a brain abscess will also need either a procedure or surgery to remove the contents of the brain abscess. The less invasive way to do this is to aspirate the contents of the brain abscess using a needle. Anesthesia is given, a small hole is placed in the skull, and a needle is guided to the location of the abscess to drain the contents.

Treatment for some brain abscesses

Some people with brain abscesses may require the following.

  • Glucocorticoid medications: These medications reduce inflammation and swelling in the brain. The physician may recommend this medication if the imaging of the brain shows increased pressure in the head. The medication given is usually dexamethasone, which is given through an IV until the swelling goes down.
  • Surgery: This may be required in more severe cases or in people who are not responding to initial treatment.

When to Seek Further Consultation for Brain Abscess

You should go to the emergency department or call an ambulance right away if you experience a severe headache, neck stiffness, or confusion. This is especially important if you have any risk factors for developing a brain abscess, such as an ongoing infection or recent brain surgery. A brain abscess is a medical emergency, and getting treatment promptly is important to prevent adverse outcomes.

Questions Your Doctor May Ask to Determine Brain Abscess

  • Are you sick enough to consider going to the emergency room right now?
  • Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
  • Have you experienced any nausea?
  • How long has your current headache been going on?
  • How has/have your headache(s) been changing over time?

Self-diagnose with our free if you answer yes on any of these questions.

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