Electroencephalogram
What is an electroencephalogram?
An electroencephalogram (EEG) is an electrical function test of the brain. It is a non-invasive test similar to the EKG/ECG of the heart. While the heart provides relatively high electrical signals, the brain provides very small electrical signals in the order of 30 to 90 micro volts that are recorded and graphed onto the computer screen for the doctor to interpret. The EEG helps the doctor to determine the health of the brain and often uses it in conjunction with imaging tests such as an MRI. And EEG is one of the only tests capable of helping the doctor to diagnose seizure activity and is often ordered when a patient's symptoms resemble either seizure or epileptiform activity.
What do I need to do to prepare for my EEG?
For a normal awake/sleep EEG it is advised that the patient has clean, dry hair. This includes no hair products such as hairspray, oils or gels. We also request that women do not wear facial makeup. Additionally, no caffeine products such as coffee, tea or chocolate, among others, should be consumed to allow the patient to get drowsy and/or reach stage two sleep. For outpatients, we ask that the patient get no more than five hours of sleep prior to the EEG. You may eat prior to the test if your condition allows. Please consult with your doctor about any medications you take, and which ones you shouldn't take prior to your EEG.
What should I expect?
A trained EEG technologist performs the examination. Generally, EEGs are completed within 90 minutes. The study itself takes approximately 20 minutes of recording, while set up and patient history can take anywhere from 30 to 60 minutes depending upon the needs of the patient. Clean up takes approximately 10 minutes.
In our EEG set up, we use 26 electrode wires. These are surface electrodes that sit on the skin of the scalp while the hair is parted and not cut in any way. Electrode sites are identified with a tape measure and a non-permanent marking crayon is used to locate sites on the scalp for placement. Gelatin prep is used to prepare the sites on the scalp, which exfoliates the skin at the site to receive the electrode. Once the site is prepared, the electrode is applied with electrolytic paste and stabilized with a piece of paper tape. These steps are done to provide optimal electrical connectivity for the small voltage signals and provide the highest quality recording for the study.
Three activations are used during the exam if they are not contraindicated include hyperventilation (deep breathing), drowsy/sleep, and photic stimulation.
After the exam the electrodes are removed. Clean up is usually done with a warm wet washcloth. Any residual product can be removed by washing the hair and scalp with shampoo.
When will I receive the results of my EEG?
The EEG technologist is not able to interpret or read the study for you. A neurologist will read the EEG either later in the evening on the same day your had your study or the following morning. The reading neurologist's interpretation is then dictated, transcribed and charted in a day or so. Usually on the fourth or fifth business day after your study, a copy of the dictated report is available for your prescribing doctor. Any urgent readings interpreted by the neurologist will be communicated with you sooner.
If you have any questions, please ask the technologist. For more information, please call (480) 728-7208.
<< Back to Cardiopulmonary Services
