The symptoms of encephalitis can havea number ofpossible causes, so several tests may be needed to diagnose it.

The main tests used are outlined below.

Brain scans

A scan of the brain can help show whether you have encephalitis or another problem such as a Heat exhaustion and heatstroke , brain tumour or brain aneurysm (a swelling in an artery).

The two main types of scan used are:

  • a CT scan several X-rays are taken from different angles and are put together by a computer to create a detailed image of the brain
  • an MRI scan strong magnetic fields and radio waves are used to produce a detailed image ofthe brain

Lumbar puncture

A lumbar puncture is a procedure to removesome fluid from around the spinal cord (the nerves running upthe 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 spineand asample of fluid is removed

Thesample will be checked for signs of infection or a problem with your immune system, which are the main causes of encephalitis .

Other tests

Several other tests may also be needed to help diagnose encephalitis and check for an underlying cause.

These may include:

  • an electroencephalogram (EEG) 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
Content supplied by the NHS Website

Medically Reviewed by a doctor on 20 Dec 2016