What is an EEG?
An electroencephalogram (EEG) is a safe and pain-free test which records the electrical activity of the brain. This is recorded on a computer and interpreted by a neurologist
What does the EEG show?
The EEG recording shows rhythmical electrical activity, often called brain waves. The brain waves may be normal or show abnormalities in certain regions. In people with epilepsy, there may be "epileptic activity" on the EEG indicating their predisposition to seizures. This epileptic activity can take several forms and be either generalised (recorded over all regions) or focal (recorded in one or more localised regions). Many types of childhood epilepsy have characteristic epileptic activity on the EEG that leads to a specific diagnosis and treatment. Focal abnormalities seen on an EEG occasionally warrant a child having a brain scan.
Does an abnormal EEG confirm epilepsy?
Minor irregularities of no significance are frequently seen in EEG recordings of normal children, especially infants and young children. Non-epileptic abnormalities and even epileptic activity may be recorded in children with neurological and behavioural problems (eg. cerebral palsy, autism, speech delay) and do not mean that the child has epilepsy. Furthermore, about 2% of normal school-age children who do not have seizures have epileptic activity on EEG.
Conversely, a normal EEG does not exclude epilepsy. Many types of epilepsy may be associated with a normal EEG between seizures. A normal EEG during a "seizure" usually excludes epilepsy as the cause.
The interpretation of EEG findings in children can be difficult and it is recommended that EEGs in children are recorded and interpreted by clinicians experienced in paediatric EEG.
How does the EEG help?
The main roles of EEG in the evaluation of children with epilepsy are to:
- help distinguish focal from generalised seizures and epilepsies
- help make a specific (syndrome) diagnosis in a child with epilepsy.
EEG is occasionally used to:
- help confirm or exclude epilepsy, following a thorough clinical evaluation (usually with EEG recording during episodes)
- monitor treatment in some types of epilepsy
- help localise the site of seizure activity in a child with focal epilepsy
An EEG can occasionally lead to confusion, especially if non-specific abnormalities or epileptic activity is seen in a child without seizures.
Requirements for an EEG
- We need your child to have clean, dry hair with no extra products such as oil or gel. If your child has hair lice, please make a new appointment, as health precautions prevent us from carrying out an EEG on a child with lice.
- Recent chicken pox must be completely healed in order for the EEG to occur.
- Ideally we need your child to be fairly still during the recording. Toddlers may not enjoy the experience, much like a hair cut or hair wash. The EEG technologist is experienced in helping children to relax. Distractions such as toys and DVDs are provided. Younger children may benefit from dummies, bottles and other comforters. Please bring these with you.
- If your child has special needs or you think he/she may not be able to cooperate with the procedure, please contact our EEG staff to discuss your concerns and the best course of action.
- If your child has episodes during specific situations, such as during sleep, please speak to your doctor or our EEG staff about the implications for the EEG recording, as it may be possible to provoke these episodes.
What happens during an EEG?
- Before testing, the EEG scientist will ask a few questions about your child even though you may have given this information to your doctor.
- Your child will either sit in a reclining chair or be nursed by you.
- After explaining the procedure, the scientist will measure your child's head and mark the scalp with a soft pencil where electrodes will be placed.
- The scientist will clean these areas lightly with a cotton bud before placing the electrodes (usually 23 small metal discs) on the scalp, and keep them in place with a sticky paste (not glue) and some light tape.
- After the electrodes have been placed, your child needs only to remain reasonably still while the scientist sits at the computer watching the screen.
- A video is recorded in case an event occurs. This gives the neurologist an accurate visual record in conjunction with the EEG recording. If no typical events are recorded, the video is deleted.
- Children old enough to cooperate will be asked to open and close their eyes during the recording.
- Later they will be asked to hyperventilate (do some deep breathing).
- The last part of the EEG test involves your child looking at a controlled flashing light.
Where to go and how long will it take?
Neurodiagnostics is located on the Ground Floor, just off Main Street, at Specialist Clinics, Reception A3. The test usually takes an hour, but may take longer, especially if a sleep recording is needed.
Obtaining the results of the test
The EEG scientist has been specially trained for this work and will be pleased to answer any questions about the procedure. However, the scientist cannot tell you the results of the test and administration staff are unable to provide results over telephone. You must make arrangements with your doctor to receive the results. In urgent situations, your doctor may obtain a preliminary report by telephoning one of our neurologists.
Some questions that your child might ask about an EEG
Q: Does it hurt?
A: No. Some children might find the procedure irritating, but it does not hurt.
Q: Do they cut my hair?
A: No. The metal disk electrodes are put on the scalp between the hair.
Q: Will they give me a needle?
A: No. You might be given a medicine to drink to make you sleepy but there are no needles.
Q: Will they give me an electric shock?
A: No. The metal discs record electricity coming from the brain but you do not feel this.
Q: Are there any after effects?
A: No. You will feel the same after the recording as you did before it.
Q: Can it read my mind?
A: No. Your thoughts are private and cannot be discovered by this test.
Key points about EEG
- EEG is completely safe and pain free for your child
- Wash your child's hair the night before
- Bring your Medicare care and the EEG request card or referral letter (if it has not already been sent)
- Arrange child-minding for other children, as they cannot be present for the EEG
- If sleep recording is required, follow the instructions we will provide separate to this fact sheet and do not let your child sleep on the way to the EEG
EEG appointments are made by the Specialist Clinics. The booking office is open from 8:15am to 4:30pm Monday to Friday and can be contacted by telephone on 9345 6180.