Routine EEG

Electro-encephalogram (EEG)

What is an EEG examination?

EEG is the abbreviation of Electro-encephalogram, which is the recording of electrical activity produced by the brain. It can help the doctor to make a diagnosis. The test takes upto 60 minutes to complete and your results will be sent to the referring GP/clinician and are usually available within seven days.

How is the test performed?

The physiologist will measure your head.  A minimum of 23 leads are then attached to your scalp using a sticky paste.  Your heartbeat will also be recorded by attaching two leads to your shoulders.  It will take 15-20 minutes to attach the leads to you.  You will be asked to lie on a couch for the recording.  The recording takes 20 to 30 minutes. During that time you will be asked to relax and to follow instructions, such as to open or close your eyes.  You will not feel anything.

During the recording you may be asked to do some deep breathing for up to 3 minutes.  This may cause some tingling of the hands and toes and may make you a little lightheaded – this is normal and will pass quickly. 

You may also be asked to watch a strobe light, this is a light that flashes on and off at different speeds.  This is particularly important if you have seizures caused by flashing lights.  However, rarely the light can trigger a seizure; if you appear to be sensitive the physiologist will stop the flashing light.  We will ask for your permission to use the strobe light at the beginning of the test.

A digital video recording will be made during the EEG recording.  This enables the doctor to compare your brainwaves with your movements and behaviour during the EEG.  However, the test can be performed without the video if you prefer.  We will ask for your permission to use the video at the start of the test.

There will be some sticky paste in your hair after the test.  We will wipe most of it out before you leave but there will be some residue.  This will wash out with shampoo.

After the test is finished and the discs are removed you will be free to continue as normal.

How do I prepare for the test?

Please ensure your hair is clean and free from hairspray and oils and continue to take your usual medications as normal.  Please bring a list of your medications with you.

You may eat and drink normally before the test.

It is helpful, where possible, for the patient to attend their appointment with a detailed and clear written account from someone who has witnessed any seizures or clinical events that are under investigation.

What happens if I have a seizure during the test?

You will be looked after until you are well enough to go home.  It is very unlikely that the investigation will cause a seizure, but if it does, and you hold a driving licence, you will be obliged to inform the DVLA (as for all attacks), this may affect your ability to hold a driving licence.

Paediatric EEG information

If your child has a favourite toy/book/snack please feel free to bring them along as these may help to keep him/her distracted whilst the leads are being applied.  We have a DVD player and a selection of DVD’s, or you can bring one of your own if you wish. 

We will need to obtain verbal consent for these procedures, and this can only be given by a person with parental responsibility.