A brain abscess is a serious disorder that occurs when micro-organisms, such as bacteria or fungi enter the brain.
An abscess is formed when bacteria or fungi, along with infected cells and pus, mass together in one area of the brain. This mass is then joined by white blood cells that have been trying to fight the infection. The body's immune system responds to such an infection by creating a membrane around this infected portion of the brain, which in turn creates an abscess.
The swelling inside the brain caused by a developing abscess can put harmful pressure on delicate brain tissue and block blood vessels. If left untreated, abscesses can cause permanent brain damage, seizures or death.
Most brain abscesses occur when infection spreads to the brain from elsewhere in the body, such as the ears or from a head injury or following surgery.
Brain abscesses are a medical emergency because they can raise the pressure on the brain to a point that may be fatal. Medication is usually the first line of treatment if:
- the abscess is small
- there is more than one abscess
- the abscess is situated deep within the brain
- the abscess is accompanied by meningitis
- surgery would be dangerous due to an underlying condition.
For a bacterial infection a large dosage of antibiotic medication is injected directly into a vein, such as Penicillin or Metronidazole. Alternatively, if a fungal infection is suspected then antifungal medications will also be given.
Surgery is an option if:
- antibiotic and antifungal medications don't work
- the pressure inside the brain is rising, or
- the abscess may burst and spill fluid into the rest of the brain.
Surgery is carried out to open up an abscess and drain it. At this stage, it is useful to take a sample of the fluid drained, to test it and make sure the correct antibiotic or antifungal medications are being given.
If the abscess is near the surface it may be possible to remove the mass of infected pus and cells. If it is deep in the brain, this may be drained using a needle guided by a CT or MRI scan. Alternatively, antibiotics or antifungals may be injected directly into the abscess.
If the infection has spread from elsewhere in the body, such as the ear or lungs, it is necessary to also treat that site to prevent further infection or re-infection.
In some cases, corticosteroid drugs such as dexamethasone are used to ease the swelling and reduce intracranial pressure (pressure inside the skull).