The symptoms of encephalitis can have a number of possible causes, so several tests may be needed to diagnose it.
The 2 main types of scan used are:
A lumbar puncture is a procedure to remove some fluid from around the spinal cord (the nerves running up the spine) so it can be checked for signs of encephalitis.
For the procedure:
- you lie on one side and bring your knees up towards your chin
- local anaesthetic is used to numb your lower back
- a needle is inserted into the lower part of your spine and a sample of fluid is removed
The sample will be checked for signs of infection or a problem with your immune system, which are the main causes of encephalitis.
Other tests may include:
- an electroencephalogram (EEG) – where small electrodes are placed on your scalp, which pick up the electrical signals from your brain and show abnormal brain activity
- tests of your blood, urine or other bodily fluids to check for an infection