What happens during the test?
This part of the test takes about 1 to 1½ hours.
You will not feel anything whilst the EEG is being recorded.
Please note, we routinely video the test in case you have any symptoms that we might need to re-examine. Video clips of any symptoms are kept as part of your records. All remaining video is deleted after the doctor has completed the report. We will ask for your consent to do this. We may also ask for your permission to use the video for teaching purposes, you will be asked to give consent separately for this purpose.
During the test we will want you to be as comfortable as possible. Most people find that they are comfortable lying down on a couch.
You may go to sleep naturally for a short period whilst you are in the department.
During the test, the technician will ask you to do various simple actions like:
• Opening and closing your eyes.
• Hyperventilation - this is taking deep breaths in and forcing them out as if you are blowing a candle out.
You may feel dizzy or get pins and needles in your fingers, toes and face. These are normal side effects which will go a few minutes after you have stopped the deep breathing. We will ask about your general health (heart, asthma, etc) to make sure it is safe for you to do the deep breathing. The breathing causes a change in the blood flow which may change your brain waves and provide extra information to help with your diagnosis. If you are being investigated for seizures, there is a less than 3 in 100 risk that the deep breathing may cause a seizure. If that happens it could mean you are unable to drive for 1 year afterwards. You will be asked to give your consent to performing this; there are no alternatives to this part of the test.
• Photic stimulation - watching a flashing light. A lamp is placed in front of you which flashes on and off at different speeds. You will be asked to look at it. In a small percentage of patients, flashing lights trigger seizures (photosensitivity). If a patient has this response the light is turned off quickly and they do not usually go on to have a seizure. However there is a less than 1 in 10,000 risk that if you are having seizures, a seizure could be triggered by the flashing light. If that happens it could mean you are unable to drive for 1 year afterwards. The information we get from photic stimulation may lead to a definite diagnosis and help your consultant to decide on your treatment. You will be asked to give your consent to performing this; there is no alternative way to get this information.
• You will be left undisturbed for a while. Sleep deprivation is said to slightly increase the risk of a seizure. There are no definite figures available because of different methods in use but the risk
is small and falls between the risks quoted above for hyperventilation and photic stimulation.
What happens after the test?
Once the test is finished, we remove the discs from your head. You may find a small amount of paste left in your hair and this is easily washed out with shampoo. You may wish to bring a hat or cap to wear.
When will I get the results?
You will not get the results on the day of your test because it takes time to analyse them. The report will be posted to your referring consultant within 2-5 days.
Your consultant will then contactyou to discuss the results.
Some frequently asked questions
Are any needles involved?
No
Can you read my mind?
No, we can only pick up the electrical activity in your brain not any thoughts you have.
What if I want more information?
If you have any questions after reading this leaflet please ring the Department of Clinical Neurophysiology, Royal Hallamshire Hospital on:
• 0114 271 3237
Monday - Friday 8:30am-4:30pm
We must obtain your consent for any procedure or treatment beforehand. Staff will explain all the risks, benefits and alternatives before they ask for your consent.
If you are unsure about any aspect of the procedure or treatment proposed, please do not hesitate to ask for more information.
What is an EEG?
An EEG is a routine test carried out in specialist hospitals. The test records the electrical impulses that your brain produces whilst sending and receiving messages to and from your body. EEGs are carried out on patients of all ages and abilities.
What does EEG stand for?
EEG stands for Electroencephalograph.
Electro - the electrical impulses that are being measured
Encephalo - the head
Graph - the way the results of the test are presented
What is a sleep deprived EEG?
You may have already had a standard waking EEG.
Sleep deprivation may help in two ways. Firstly the tiredness may result in brain waves on the EEG which are not usually seen. Secondly, you may fall asleep during the EEG and this may reveal new information that would otherwise have been unseen. If you are being investigated for seizures, there is a slightly increased risk of you having a seizure when you are sleep deprived (see later).
How long will I be at the hospital?
You should expect to be at the hospital for about 2 hours.
Where is the test done?
The test is performed in a recording room on N Floor (tower block) of the Royal Hallamshire Hospital. The room contains a couch and the EEG equipment. There will be a technician present and there is also room for you to bring someone with you if you wish.
Please note (parents and guardians):
We have no provision for accompanying children to be supervised whilst you are having your EEG. If you have any problems arranging childcare, please ring the department to discuss this.
Is there anything I need to do before having the test?
Yes, you should:
• Stay awake throughout the whole of the night before your test.
• Have a good breakfast.
• Have clean hair that is free from hair-spray or gel.
• Wear comfortable loose clothing that you are happy to sleep in.
• Continue with any medication you are currently taking. It is helpful to bring a list of your medications with you.
• If you would usually drive to your appointment, please make alternative arrangements. It is not safe for the patient or anyone who stayed up with them, to drive after sleep deprivation.
What happens before the test?
To prepare you for the test, your head will be measured and then rubbed with a cotton bud and some abrasive paste. A sticky paste is then used to make it easier for the 23 discs that will be placed on your head to pick up the small impulses we are going to record.
Getting you ready for the test takes about 20 minutes.
You may ask any questions that you have at this time.
1. The discs are then connected to the EEG machine by wires.
2. The recording will be taken over 1½ hours while your child sits on your lap or lies on the bed, relaxing and trying to sleep. They will be asked to follow commands such as “open/ close your eyes”, or perform some of the following ‘activation techniques’ as they may produce changes in the brain wave activity:
• Deep breathing – Your child will be asked to breathe deeply for 3 minutes. To help them do this they may be asked to blow a windmill. This can cause a light - headed feeling or tingling of the lips or fingers but this is normal and will resolve by itself afterwards.
• Photic Stimulation – Your child will be asked to look at a bright flashing light with their eyes open and closed, for a few seconds at a time. This is an important part of the test for people who may have seizures or black-outs caused by flashing lights. We will be looking at the EEG at all times and will stop the light immediately if they appear sensitive. This is done under very controlled conditions.
What does the test feel like?
Your child will feel a cold rubbing sensation on their scalp when the discs are being applied, but there are no sensations during the recording. No needles are involved.
After the test
After the test the discs will be removed with warm water. Your child’s hair may be sticky and damp and some of the paste may be left in it afterwards; this will wash out and you will probably need to wash their hair after the test.
If your child has been sleep-deprived they will probably still feel sleepy after the test.
When will I get the results?
You won’t get the results straight after the test as the EEG has to be analysed. A full report will be sent to the doctor who referred your child for the test after about 2 – 3 weeks and they will discuss this with you at your next outpatient appointment.
Contact details
You will be able to ask any questions or tell us any concerns before the test is carried out but if you would like to contact us before your appointment please call:
Neurophysiology
0121 507 4319
Monday – Friday, 9am – 5pm
Further information
For more information about our hospitals and services please see our website www.swbh. nhs.uk or follow us on Twitter @SWBHnhs.
Sources used for the information in this leaflet
• National Institute for Health and Clinical Excellence, CG137 ‘The epilepsies: the diagnosis and management of the epilepsies in adults and children in primary and secondary care’, January 2012
• Journal of Neurology, Neurosurgery and Psychiatry, ‘EEG in the diagnosis, classification and management of patients with epilepsy’, June 2005
What is a sleep EEG?
EEG stands for electroencephalogram. A sleep EEG is a recording of the electrical activity of the brain while you are awake and then asleep. It involves having small discs (electrodes) which record the activity attached to your scalp using paste. Your child may also be asked to breathe deeply or look at bright flashing lights at some point during the recording (these are called activation techniques).
As part of the test your child will also be video recorded as this can help to diagnose the condition; you will be asked to sign a consent form to allow this at the beginning of the test.
There are different types of sleep EEG recordings:
• Baby sleep EEG – If your child is under 3 years old we will try to record the EEG during natural sleep. To help us achieve this please bring a dummy, bottle of milk, blanket or toy and do not let your child sleep before the test.
• Sleep Deprivation EEG – For this test your child will need to avoid sleeping or have less sleep on the night before the test. The amount of sleep your child can have will be detailed in the appointment letter.
• Sedation sleep EEG – On rare occasions your child’s doctor may ask for a mild sedative (Melatonin) to be used to induce sleep or calm a child for an EEG. A single dose of Melatonin is unlikely to cause any side effects.
What are the benefits of a sleep EEG?
The benefit of an EEG is that it will help your child’s doctor to diagnose if there are any problems and he/she will then be able to advise any appropriate treatment if required.
What are the risks of an EEG?
There is a small chance that your child may experience some reddening of the skin or soreness where the paste is applied. There is a small risk that some of the activation techniques or sleep deprivation can provoke their symptoms. In a few cases sleep deprivation can make some people’s symptoms more frequent.
The risk of a sedation sleep EEG is that the effects of the sedation can last for several hours so your child may still be sleepy for a while after the test but this is not dangerous.
What are the risks of not having the test?
If your child does not to have a sleep EEG, this may delay their doctor finding out what is causing their symptoms and starting treatment.
Are there any alternative tests?
There is usually no alternative to this test that will give your child’s doctor the information they need.
Preparing your child for the sleep test
• Follow the instructions on your appointment letter for the amount of sleep your child can have before the test.
• Avoid giving your child drinks with caffeine before the test.
• Please bring along anything you think might help them to sleep – dummies, milk, special blankets or toys to aid sleep.
• Do not let your child sleep before the test e.g. on the journey to the hospital.
• You child can eat and drink as normal before the test. Make sure they have something to eat within 1½ hours before the appointment as they are more likely to sleep if they feel full.
• Your child should arrive with clean, dry hair free from grease, hair spray and lacquers etc.
• Your child should continue to take any medicines as usual. Please bring a list of these with you to the appointment.
• Bring a comb or brush with you to tidy their hair after the test.
• If you don’t feel that the appointment is at a suitable time of day for sleep i.e. you feel they are more likely to sleep in the afternoon, please contact us to rearrange.
• If you are concerned about the amount of sleep we have suggested your child should have please contact us to discuss this.
If you are unable to keep this appointment please contact us on 0121 507 4319 so that alternative arrangements can be made and the appointment can be given to another patient waiting for the test.
Before the test we will ask you if you have read and understood this information and whether you consent to go ahead with it. We will also answer any questions you have.
During the test
The appointment will take around 2 hours. This is what happens:
1. The person doing the test will start by measuring your child’s head if they are cooperative.
2. They will then rub your child’s scalp and stick some small discs to it using sticky paste.
3. The discs are then connected to the EEG machine by wires.
