EEG Testing Information
Your doctor has recommended that you undergo EEG (electroencephalogram) testing. This test measures the electrical activity in the brain, using electrodes applied to the scalp. The EEG test is most often used to assist in the diagnosis of epilepsy and plays a role in diagnosing other brain disorders.
EEG testing is performed by an EEG technician. Unless you have an appointment to also see the neurologist following the test you will not see a doctor at the time of the test.
BEFORE THE TEST
Please ensure hair is clean and dry with no hair products left in.
Please continue to take all of your regular medications unless your doctor has instructed otherwise.
If your child was referred for this test by a neurologist you may have extra instructions regarding medication and sleep/nap times. Please follow these instructions if this is the case.
If you have been referred for a Sleep-Deprived EEG you will need to remain awake for 24 hours prior to testing, and not take stimulants such as caffeine or No-Doz. If you fall asleep for a short period please still attend the appointment. Do not drive to and from the appointment due to increased seizure risk when sleep-deprived.
TEST PREPARATION
Children may be accompanied by either or both parents or carers, however we ask that siblings or other family members do not come into the room as it is important that the child is quiet and not distracted.
Adults may bring one person to accompany them during the test if they wish.
The test can be performed either in a chair or on the bed. A parent may hold the child on their lap or sit next to them on the bed as it is important that the child is settled to ensure correct placement of electrodes.
During preparation and application of the electrodes, which takes around 15 minutes, parents may use books, toys or devices to help distract children and keep them settled. Babies may have a bottle or breast feed if needed. If a small child or baby is unsettled a sheet may be used to swaddle them.
First the head is measured and a soft pencil is used to mark the position of each electrode.
Each position is then rubbed with a gritty lotion which prepares the skin so the electrodes conduct the electrical signals well.
The electrodes are then applied in order, using a special glue. There are 23 electrodes applied for this test. Tape may be used to help keep electrodes in place, and for small children a bandage may then be wrapped around the head to cover the electrodes once in place.
DURING THE TEST
Once the electrodes are in place and checked the test can commence. EEG testing usually runs for about 20 minutes. If sleep-deprived testing has been requested the patient will go to sleep during the test and it will last approximately 1 hour.
The patient should remain quiet and still with eyes closed for optimal test quality. Small children and people with some types of cognitive or movement disorder may not be able to achieve this, but we will attempt to get at least a short period of quiet resting.
After the first few minutes of testing the patient will be required to breathe fast (hyperventilate) for a period of 3 minutes.
The patient will also be asked to look at a series of flashing lights.
Once the test is complete the electrodes will be removed and a washcloth used to remove some of the glue. The remainder of the glue will need to be removed at home under the shower with shampoo. The glue is water soluble but requires some gentle scrubbing with fingers to remove fully.
EEG Frequently Asked Questions
The neurologist will read the EEG and report on the test. Your referring doctor will have the results of the EEG test within a few days. The technician cannot report on the test or give you any results.
It is possible, although rare, for a seizure to occur during EEG testing. Hyperventilation and photic (flashing light) stimulation can provoke some abnormal electrical activity, but the likelihood of a seizure occurring is low. If a seizure occurs the technician will ensure the safety of the patient during and after the seizure.
Certain types of epilepsy show abnormal patterns of electrical activity much of the time, even when there is no seizure activity. It is also possible for many people with epilepsy to have a normal EEG pattern unless they are actually having a seizure. This is why it is important for the result of the EEG to be interpreted in conjunction with the clinical examination by your doctor.
EEG testing is painless. Sometimes the gritty lotion used to prepare the skin is uncomfortable to apply.
No, EEG testing records electrical activity coming from your brain, it does not send electricity to your brain at all.
It is normal for small children and people with conditions that affect movement or cognition to have trouble sitting still. The EEG technicians expect this and accept that some movement is inevitable. The technician will let you know if movement is affecting the test recording.
If you think your child might need extra time to settle for the test due to cognitive or behavioural reasons please let the staff know before the test day if possible so we can allow some extra time.