Electroencephalogram (EEG)

For Neurology related requests:

For all other requests:: 1-800-777-8442

An electroencephalogram (EEG) is a test that measures electrical currents in your brain.

The information gathered during an EEG shows whether your brain cells are working properly. It can help your provider confirm whether you have a medical condition like epilepsy. And it can show whether your brain function has been affected by a stroke or head injury.

University of Iowa Health Care’s EEG program is accredited by the American Board of Registered Electroencephalographic and Evoked Potential Technologists.

Accreditation is only given to medical centers that meet strict criteria related to quality of studies performed by highly trained providers while maintaining utmost patient safety. When you have an EEG with UI Health Care, you can have confidence in the accuracy of your test results.

How an EEG works

A standard EEG is a noninvasive procedure.

Small metal discs (electrodes) placed on your scalp connect by wires to a special machine. The electrodes detect your brain’s electrical activity—also known as brain waves. The machine records these brain waves, which create predictable patterns when you’re asleep, awake and resting, or awake and thinking.

One of our neurologists will review your EEG recording. They will look for abnormal brain wave patterns that indicate a problem inside your brain.

Other types of EEG

In some cases, your provider may need more information than a standard EEG can provide. Below are other types of EEG we offer.

Video EEG

If you have seizures that are hard to control with medication, your provider may admit you to the hospital for video EEG testing. This advanced type of EEG takes place in our inpatient epilepsy monitoring unit.

During your stay, your brain waves will be recorded around the clock via EEG. You’ll also be monitored by a video camera.

The purpose of this test is to capture—on video and EEG—the exact moment you have a seizure. The video footage lets us see what time your seizure occurred, how long it lasted, and what happens to you (better description of bodily movement and your cognitive abilities) during a seizure. And the EEG recording lets us see how that seizure affected your brain waves.

Together, this information helps us confirm:

Whether your seizures are caused by epilepsy or another disorder
Where in the brain your seizures occur
Which treatment (either a new medication or surgery) is likely to work best

Most people stay in our epilepsy monitoring unit for 3-5 days. That’s because we need you to stay long enough to have at least one seizure while you’re here.

Intracranial EEG

If your provider has recommended surgery to treat your epilepsy, you may need to have an intracranial EEG.

Unlike standard EEG tests, which are noninvasive, intracranial EEG requires surgery. Instead of placing electrodes on your scalp, your provider will place them directly on your brain or deeper inside your brain.

UI Health Care offers two types of intracranial EEG:

Stereo EEG (SEEG): Your surgeon drills tiny holes in your skull, then inserts small wires (depth electrodes) through the holes. These depth electrodes monitor and record your brain waves.
Electrode grid placement: Your surgeon temporarily removes a small piece of your skull (craniotomy). Then, they lay plastic strips or sheets containing many electrodes across your brain’s surface.

For many patients, intracranial EEG is an important step before surgery. It pinpoints where in the brain your seizures start. And it creates a map of the “functional” areas in your brain (the spots that control speech, movement, and more). This helps your surgeon see where they need to operate and which areas to avoid.

What to expect during a standard EEG

Most standard, outpatient EEGs take an hour or two from start to finish.

EEG preparation

An EEG doesn’t require a lot of special preparation.

Generally speaking, you can eat and drink before your EEG as you normally would. However, you should not have any caffeine the day of your test.

It’s also okay to shampoo your hair the night before (or the day of) your procedure, but do not use conditioner or styling products. These items can make it harder for the electrodes to stick to your scalp.

During your procedure

An EEG usually includes the following steps:  

First, we’ll mark the areas on your head where the electrodes will be placed. We may gently scrub these areas with a gritty cleanser.
Next, we’ll attach the electrodes to your scalp using an adhesive material. This material washes out of your hair easily.
During the test, you’ll sit or recline in a special chair, in a comfortable position.
Your EEG technician may occasionally ask you to take deep breaths or look at a flashing light. This helps us make sure we capture certain brain waves.
Once your EEG is complete, we’ll remove the electrodes. You can then go home or return to your normal activities.

After your procedure

The brain waves recorded during your procedure will be read by a neurologist with special training in EEG. They will write a report summarizing your results and send it to the provider who ordered your test.

Your provider will help you understand what the test showed and discuss next steps, including further testing or potential treatments.

Who can benefit from an EEG?

If your provider thinks you might have a neurological illness or injury, an EEG can offer answers. It shows changes or abnormalities in your brain waves that are commonly associated with certain conditions.

These include: