Ambulatory EEG

Reviewed by: HU Medical Review Board | Last reviewed: November 2023 | Last updated: November 2023

Detecting electrical activity in the brain is crucial to diagnosing and treating epilepsy. An EEG (electroencephalograph) is a test that identifies abnormal electrical activity in your brain, which can cause seizures.1,2

Over the years, EEG technology has evolved, allowing doctors to capture longer and more detailed snapshots of brain activity.

What is ambulatory EEG? In medical terms, "ambulatory" means a service provided outside of a hospital. An ambulatory EEG is a test you take at home.1,2

How does ambulatory EEG help with epilepsy?

An ambulatory EEG records seizures at any point during the day or night versus a routine EEG that only records a 20- to 40-minute sample.2

You may need an ambulatory EEG if medicine does not control your seizures or if doctors need more information about your seizures. The test can help doctors figure out if epilepsy or another process is causing your symptoms. It can also tell doctors how your are responding to your anti-seizure medicine.2

What can I expect during an ambulatory EEG?

An ambulatory EEG can last anywhere from 24 to 72 hours. Using a special paste, hospital or lab staff will attach electrodes to your scalp then cover them with a cap or gauze. Wires running from the electrodes connect to a small portable recorder, which you can wear around your waist.2

It may feel strange wearing EEG equipment all day, but you can still live your day-to-day life. You will need to keep a journal of your activities, including whether you had any seizures.2

You should also record whether you feel an aura, which is an unusual sensation that can precede a seizure. Auras can be different for everyone but may include changes in sensation (hearing or tasting things) or simply feeling different than usual. An accurate journal will help your doctor distinguish between unusual brain activity and unrelated movements like scratching your head.2

If you have a seizure or feel any unusual sensations, you or someone else will press the recorder’s "event" button, which notes the time of the episode. In general, it is better to push the event button too much rather than too little, since seizures may have subtle signs and symptoms. Newer recorders automatically pinpoint epilepsy waves and attacks and record a video of an event.2

When you have finished the test, you will use acetone, oil (coconut, olive, or baby), or multiple rounds of clarifying shampoo to get rid of leftover paste on your scalp.2

What are the possible risks?

Ambulatory EEG places more responsibility on the user. You will need to remember to press the event button and keep a diary. If there is a technical problem with the EEG equipment, you may have to fix it yourself. Usually, EEG staff will provide you with contact information if you have any technical problems with the EEG. Plus, some equipment can now be monitored by hospital staff at a remote location.3

If you do not perform the test correctly, the doctor will not be able to interpret your results. You may then have to retake the EEG at the hospital. In the hospital, staff can also monitor you as they do things to trigger seizures, such as stopping seizure drugs.

These are not all the possible risks of ambulatory EEG. Talk to your doctor about what to expect. You also should call your doctor if you have any changes that concern you about ambulatory EEG.

Things to know about at-home EEGs

There are some benefits of ambulatory EEG. One is cost, since it is less expensive to do the test at home. You provide your own bed and meals at home, which are expenses that add up in a hospital or lab.3

Many insurance plans will fully cover the cost of an inpatient EEG admission since they are often considered medical necessities. However, you should check with your insurance provider.4

An ambulatory EEG is also more convenient for those with work, school, or family commitments. And, your home may simply be a more comfortable and familiar environment than a hospital. There is a lot to consider, and your doctor can help walk you through your options.3

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Treatment results and side effects can vary from person to person. This treatment information is not meant to replace professional medical advice. Talk to your doctor about what to expect before starting and while taking any treatment.