An introduction for parents, guardians and older children.
What is an EEG?
EEG stands for Electroencephalogram, a recording of the electrical signals produced by the brain. In the media it is sometimes referred to as recording brainwaves.
The EEG gives information about the brain that is useful to the doctor in making a diagnosis in several different conditions. It is the only test that can produce this sort of information, but your doctor may also want to get information from other tests.
About our Department
West Surrey Clinical Neurophysiology is a specialist department, one of only a few in the country. We are based at St Peter’s Hospital in Chertsey but we provide our services to patients from several other hospitals too.
Please make sure you come to the right hospital!
Preparing for the EEG
Unless we ask you to change your child’s medication, make sure that they carry on taking all their usual medication as recommended by the doctor. If possible bring a list of the medications with you.
He or she should eat as normal, including meals on the day of the test and have a normal night’s sleep before the test.
We can only do the test if your child’s hair is clean, dry and we have easy access to the scalp. Please do not use any hair styling products. Please call us for advice if your child has a wig, hair extensions, braids or weaves.
Arriving at St Peter’s Hospital
If you are unable to keep the appointment for your child, please do let us know, using the contact details at the bottom of this webpage.
Our department is in the main outpatient block at St Peter’s Hospital. Please make your way to level two. Ours is the first clinical area on the right in the main outpatient corridor with green dots on the corridor walls. If you know St Peter’s, this area is just behind the W H Smith Shop and to the right of the Pharmacy. The signs say ‘EEG / EMG’ and ‘West Surrey Clinical Neurophysiology’.
The nearest car park is the main outpatient car park at the front of the hospital. Please note St. Peters Hospital operates payment parking systems.
Further details are available online here.
It is helpful if you can arrive about 10 – 15 mins before the appointment time shown on the accompanying letter. We have only limited space in our waiting room, if you arrive earlier at the hospital you will be asked to wait elsewhere. There is a café at the main outpatient entrance nearby. We aim to keep to our appointment times, but if we are running late we shall let you know and we ask for your patience.
What happens during the EEG?
The test will be carried out by a clinical physiologist, who will meet you and your child in our waiting room and take you to the recording room. We shall explain the test and this is a good time to ask any questions you still have. The clinical physiologist will also ask you about your child’s particular problem and about their health in general. He or she will also ask you to sign a consent form.
The clinical physiologist will measure the child’s head and make marks with a skin pen. At each mark, he or she will rub the skin and then attach a small metal disc through which the recording is made. It is held in place with a sticky paste.
The investigation is painless and in general school age children will be lying down for the recording and will be asked to follow instructions, such as to close and open their eyes. Younger children and babies can sit on a parent’s lap playing with toys and in this age group most of the recording is obtained with the eyes open with only brief periods with the eyes closed needed. No needles or electricity are used and we only record the signals which are produced naturally by the brain. You can bring any favourite toy with you or bring a drink or snack if you feel this will help to settle your child.
In general we use 'activation procedures' to improve the recording in school age children, including overbreathing and photic stimulation. The clinical physiologist will explain these to you and your child, and ask for consent at the start of the test from the parent or guardian present.
Sedation for Sleep EEG
In some cases it is useful to record the EEG whilst asleep. We make this decision with the doctor who refers your child. For this a drug called melatonin is used to help them sleep. This is a naturally occurring drug that alters the body clock so that they sleep gently for a short period. It is unlike other sleeping tablets that “knock you out” and your child should have no real side effects, although younger children may well be drowsy.
- Older children may be asked to come straight to the department and the melatonin tablets will be given by the Clinical Physiologist.
- Babies and young children will be asked to go the paediatric day ward (Oak Ward) and the melatonin will be given by the staff there. Once the melatonin has been given you and your child will be brought down to the department.
- If a sleep EEG is required for an infant we should have contacted you prior to the appointment to try to arrange things so that a feed can be given either just before we start the test or whilst we are getting the small discs onto the infants head and then hopefully a natural period of sleep can be recorded.
If we need to do this part of the test it will say so on the appointment letter – your letter will say “Routine and Sleep EEG” with clear instructions on where to go. Otherwise the letter will just say “Routine EEG.
The clinical physiologist will ask you, the parent or guardian, to sign a consent form for the following two areas of the test.
Video recording - this is a useful tool in helping the medical consultant report on the EEG recording. The video is time locked to the recording, which means that the consultant can at any time play the video and see exactly what the child is doing. This allows for a more detailed report which can be very useful for some conditions.
Photic stimulation – this part of the test involves a flashing light, similar to a strobe light. This part of the test can be diagnostic for specific types of epilepsy. In a very small number of people there is a very slight risk of this triggering an event.
This is not the aim of the procedure and we take all possible steps to stop this happening.
We will discuss both of these areas further with you and older children at the time of the appointment and the clinical physiologist will try to answer any questions you or they may have.
What happens after the recording?
After the recording the small discs will be painlessly removed and the paste dissolved by rubbing the area with clean warm water.
The hair will still feel sticky afterwards.
There are no after effects from the EEG recording, which will take around one hour and your child will can leave immediately afterwards. A sleep EEG takes a little longer, about one and a half hours, but your child can still go home afterwards.
What happens next?
The EEG recording is reported at a later time by both the clinical physiologist, who gives a technical report which involves measuring all the different waveforms recorded, and the medical consultant who gives a clinical report.
This report is sent to your child’s hospital consultant and he or she will give you the result of the EEG test at a later date.
A copy may be sent to your child’s GP.
We aim to prepare these reports in good time.
If you have any questions before your appointment please contact us and we will try our best to answer them.
You can phone us on 01932 722543. We are open from 9am to 5 pm. There is an answering machine outside these hours or if we are unable to take your call.
Our postal address is:
West Surrey Clinical Neurophysiology
St Peter’s Hospital