Electroencephalogram (EEG)

An EEG is a painless test that provides important information about the health and functioning of your brain. To do this we measure changes in the electrical activity generated by your brain's nerve cells. EEG is used for the most part in the evaluation of patients with seizures and those suspected of having seizures. It is also used as an indicator for brain function in metabolic disorders, head trauma, infectious diseases of the nervous system, cerebrovascular accidents and in the evaluation of organic causes of psychiatric problems. Neurologists, neurosurgeons and pediatricians use the service of EEG most widely.

EEG does not measure intelligence or mental status and there is no danger of electric shock. EEG provides information primarily on brain function but can also compliment the information gained from other medical tests.

We hope that the following information will help you understand more about the electroencephalogram (EEG). If you have additional concerns please feel free to contact the EEG Department at (613) 548-7835. Our office hours are Monday to Friday 8:00 a.m. to 4:00 p.m.

What to bring to your appointment

Please bring your Health Card to your appointment. If you are employed with the military, please bring any necessary military paperwork. It is also helpful to bring a list of your current medications because this information will be used by the electroencephalographer when interpreting your EEG results.

Who conducts my EEG and what does it involve?

A Registered Electroencephalographic Technologist will conduct your EEG. The procedure usually takes approximately 60 minutes but may take as much as 90 minutes to complete. The technologist will explain the procedure and will have you sit or lie down to ensure that you are comfortable and relaxed. Your head will be measured and a minimum of 21 small metal discs, called electrodes, will be applied to your scalp. Once the electrodes are in place, you will be asked to close your eyes and relax. The brain signals recorded through the electrodes will be displayed on a computer as “waves." The technologist will sit near you and monitor the EEG machine. 

During the recording, you will be asked to keep very still because movement can obscure the EEG recording. You may be asked to perform simple tasks such as opening and closing your eyes, taking deep breaths for a few minutes or looking at a flashing light. Once the EEG is complete, the technologist will simply remove the electrodes with warm water. There are no after effects of the EEG and you will be able to drive and continue your normal activities.

How to prepare for an EEG

You should wash your hair the night before to ensure that it is clean and dry for the test. Any oil on your scalp will reduce the quality of the recording. Please do not use conditioners or hair styling products, they should be removed before the test.

Please continue taking your medication as normal, unless your doctor has told you otherwise.

It is also recommended that you eat a regular meal or light snack prior to your EEG test. This will help stabilize your blood sugar level.

If you are to undergo a sleep deprived EEG, your doctor will instruct you to stay awake for all or a portion of the night before your test. For example, adults may be told to have a nap in the evening then remain awake from midnight on. Before undergoing a sleep deprived EEG, please avoid caffeine such as coffee, tea or cola. Do not take any sedatives before the sleep recording. Also remember to bring a friend or relative to the hospital with you as you should not drive when you are sleep deprived. 

Your results

The technologist will not be able discuss the test results with you. They will prepare a preliminary report for the electroencephalographer who then reviews and interprets your EEG. Their final report will be sent to your doctor. This process usually takes no more than two weeks.   

Ambulatory EEG

Ambulatory Monitoring is an EEG that is recorded while you are following your normal routine at home, at work or at school.

You will come to the EEG Department on Connell 7 at KGH to get set up for your test. This setup will involve measuring your head and applying 21 electrodes to your scalp. Your hair will not be cut and at the end of the recording the technologist can easily remove the electrodes. Two additional electrodes will be taped to your chest to monitor your heartbeat.

The electrodes will be arranged as discreetly as possible and will be plugged into a battery operated recording device, which will be secured in a pouch at your waist. It's suggested that you wear a shirt that buttons on the front to your appointment because it makes it much easier to set-up the EEG. You will be completely free to move around and continue your daily activities with some minor exceptions. The technologist will explain these to you on the day of your test.

This procedure takes approximately one hour to complete. The technologist will give you a diary in which you will be asked to record your activities and describe any spells that may occur. A time will then be arranged for you to return to the department the next morning. At that time, it will be decided if the electrodes are to be removed or if the recording needs to continue for another day. 

If the electrodes are to be removed, this will take about 30 minutes to complete. We will use an oil-based product to loosen the glue on the electrodes. We will clean your hair as much as possible, but it will look a little bit oily when you leave the hospital. 

If the recording is to be continued, you may have to wait for approximately 20 minutes while the information is downloaded from the recording device. If you have any questions or concerns about this test, please feel free to call the EEG Department at (613) 548-7835.

Intensive Monitoring EEG

Intensive Monitoring is a continuous Video and EEG recording taken while you are an inpatient in the hospital. The main reason this test is done is to help diagnose and manage seizures. Our goal with this type of testing is to simultaneously record the behavioural and EEG phenomena that occur when you experience symptoms.

For information on how to prepare for and what to expect during your EEG/video monitoring, please see the Epilepsy Monitoring booklet.

If you have any questions after reading the booklet, please feel free to call the Senior Technologist’s office at 613-548-6123 Monday to Friday, 8 a.m. to 4 p.m.

Please note that the scheduled appointment date is subject to bed availability. If a bed is not available, Admitting will advise you on that date and the test will be rescheduled as soon as possible.