Brain abscess

What causes a brain abscess?

Brain abscesses are caused by infections reaching the brain. Infections can either come from the bloodstream or from a nearby infected site, such as one in the skull, ear or sinuses. They can also develop following a head injury in which the skull has been damaged, allowing an infection to reach the brain.

Infections that cause brain abscesses are usually bacterial. In rare cases they are fungal. In some cases, the cause of a brain abscess is unknown.

In very rare cases, a brain abscess can develop following neurosurgery.

What happens in a brain abscess?

When an infection reaches the brain, the body tries to stop it from spreading by forming an abscess. An abscess is a swelling filled with infected fluid (pus). As the abscess grows, it puts increasing pressure on the surrounding brain tissue. This can disrupt the supply of blood and oxygen in the brain. There is also a risk that the abscess could burst, releasing the infected fluid in the brain.

Symptoms of a brain abscess include:

• A severe headache that usually does not improve with painkillers and may be in one specific area of the head;

• Confusion;

• Problems with speaking or moving, such as slurred speech or paralysis;

• Problems with vision;

• Seizures;

• Neck stiffness;

• Feeling or being sick.

Any slurred speech, new muscle weakness or paralysis, or a first-time seizure suggest that there is a problem in the brain requiring immediate medical attention. Call 999 and ask for an ambulance.

If a person has symptoms of an infection that are not getting better, or getting worse, such as having a high temperature or being sick, they should contact their GP, NHS 111 or local out-of-hours service immediately.

How is a brain abscess treated?

A brain abscess is a medical emergency, so antibiotics may be given before a diagnosis is fully confirmed.

Diagnosis of a brain abscess may involve a medical assessment, reviewing the person’s medical history, blood tests, brain scans or testing a sample of pus.

Once an abscess is confirmed, it may continue to be treated with medication. This will usually be antibiotics as most brain abscesses are bacterial, but an antifungal may be used if the abscess is caused by a fungal infection.

Surgery may be needed to drain the brain abscess or remove it completely. There are two main surgical procedures that can be performed:

• Simple aspiration – a computerised tomography (CT) scan is used to locate the abscess in the brain. A small hole (called a ‘burr hole’) is then drilled into the skull to reach the abscess and drain it. The hole is then closed again.

• Craniotomy – part of the skull is temporarily removed to create an opening in the skull. The piece of bone removed is called a ‘bone flap’, which allows access to the brain. Surgical tools are used to either drain the abscess or completely remove it from the brain. The bone flap is replaced afterwards.

The type of treatment used will depend on factors such as the size, location and number of abscesses in the brain, as well as the person’s overall condition.

What happens after a brain abscess is treated?

Following treatment for a brain abscess, a person will usually need to stay in hospital for several weeks to recover from their treatment. They will continue to be monitored by the medical team.

The person may need to undergo a period of rehabilitation to cope with the physical, cognitive or emotional impact of the brain abscess. This can take place within the hospital, at a specialist brain injury rehabilitation unit or through community-based teams.

A person may be able to return directly home from hospital, but they will need to continue resting. The time needed to recover and return to usual activities varies from person to person, and this may take several weeks or longer.

For more information on these next stages, visit Treatment and rehabilitation.