24 hour Ambulatory EEG

24 hour Ambulatory EEG (Electro-encephalogram)

What is an EEG examination?

EEG (electro-encephalogram) is an ambulatory EEG is a recording of the electrical signals from your brain made over 24 hours.  An ambulatory EEG is used to help the doctor in diagnosing your condition.  You will be given two appointments, one day apart.  The first will be to fit the equipment to you which will take between 60-90 minutes; the second appointment will be to remove the equipment from you which can take upto one hour.    The results will be sent to the referring GP/clinician and are usually available within seven days.


How is the test performed?

A physiologist will measure your head and up to 23 leads are then attached to your scalp using a special type of glue.    A bandage may be placed around your head to keep the leads in place.  Your heartbeat will also be recorded by attaching two leads to your shoulders.  It will take approximately 30-45 minutes to attach the leads to you.  The leads are plugged into a small recording device that you will take home with you.  The device will be recording your electro-encephalogram (EEG) all the time you are wearing it. You will not feel anything.  You will need to return to the department the following day to have the leads removed.


You will be given a diary to fill in whilst you are wearing the recorder and you need to record your activities e.g. when you are eating, when you are relaxing/watching TV, when you are active and when you go to bed.  If you experience any of your attacks you must write this down.  There is an event button on the recorder which you will be shown, this needs to be pressed either by you or someone with you if you have an attack.  This marks the recording so we can identify the part of the recording where the attack occurred.


Whilst wearing the recorder you will not be able to have a bath or shower or go swimming.  

Please wear loose fitting, comfortable clothes.


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 wash your hair either the same day or the evening before the test, and ensure your hair is dry, clean and free from hairspray and oil. 


If you are taking medication please continue to take it and bring a list of your medication with you. You may continue to eat meals as normal.


It is helpful, where possible, to attend with someone who has witnessed any seizures or clinical events under investigation in order to gain a good description of them.


There are no side effects from the test.


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 Ambulatory 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.