Ambulatory Electroencephalography: Patient Information 

What is an Ambulatory EEG? 

The brain’s electrical activity changes every second.  A routine electroencephalography (EEG) test gives a 20 to 40 minute sample of electrical brain activity, which is often enough.  In some patients with epilepsy however, this sample is normal or shows only minor, general findings. For example, in some people, epileptic waves happen only every 3 or 4 hours or only after an hour of sleep. In such cases, it is more helpful to have a longer sample that includes long periods of time both while you are awake and while you are asleep.

An Ambulatory EEG can record up to 72 hours of brain activity.  It uses a special recorder that is slightly larger than an iPhone. This device lets you do your normal daily routine while the EEG is being recorded.

You will be video recorded during the beginning of your ambulatory study while you are in the examination room. The viewing and use of this video recording is limited to medical or teaching purposes. The recording is the property of NYU Langone Hospitals.

Are There Any Risks To The Test?

The Ambulatory EEG test has been used for many years and is considered a safe and painless procedure. The electrodes do not produce any electric current. They only record activity.

You may have skin irritation or redness at the places where the electrodes were attached, but this usually goes away within several hours. If you feel any discomfort during the EEG hookup, notify your EEG technician immediately. If you have any burning or soreness at an electrode site, please notify your epilepsy doctor, PCP or neurologist.

Why Do I Need This Test?

Some of the reasons your doctor may order an Ambulatory EEG are:

• To know if you are having fainting spells or events that are different to seizures.
• To diagnose epilepsy and understand the types of seizure(s) you are having.
• To count the number of abnormal discharges or seizures you may be having.
• To better understand times when you are unconscious or have memory loss.
• To track how well your medications are working.
• To study events that may happen at random.

How Do I Prepare For The Ambulatory EEG?

• Shampoo your hair before the appointment.  Do not use conditioner.
• Do not use any products on your hair.
• Please do not wear any clothing that pulls over your head.  You should wear a button down shirt or a top with a zipper.
• Bring a hat or scarf to cover your head, if you would like.

How Is The Test Done?

Setting up the Ambulatory EEG takes about an hour. The EEG technologist puts 16 to 25 flat metal discs, known as electrodes, on specific areas of the scalp, using special cement known as EC2 to keep the electrodes in place. The electrodes are connected to a small device that records the brain’s electrical activity. You can wear the device on your waist, under or outside your clothing.  For people with a full head of hair, the electrodes can be fairly well hidden.  Even so, you may prefer not to go to work or school while you have the electrodes attached.

An Ambulatory EEG study lasts 24, 48 or 72 hours. Please do not take a shower during this time as water will damage the equipment.

You will be asked to keep a diary of your activities on the day(s) of the Ambulatory EEG.  In addition, your device will most likely have an Event Button for you to press if you have any of the symptoms you are being tested for, such as feeling “spacey” or confused. A family member should press the button if you are unable to do so.

Please avoid using other electrical equipment when it is plugged into the power (i.e. laptops, phones, remote controlled video games). You may use this equipment when unplugged.

What Do I Need to Do During the Test?

The box you will be wearing has a device which records your brain activity for 24, 48 or 72 hours. For the test to work, the electrodes need to stay firmly attached. Here are some things to remember:

• Be careful when handling your device.  DO NOT lift it by the wires.
• Do not remove the electrodes, cable or wires from the box.
• Do not get the box wet.  Do not take a shower or bath.
• Do not chew gum.
• Do not scratch your scalp.
• Avoid vigorous activities or those that may make you sweat.

Please avoid using other electrical equipment when it is plugged into the power (i.e. laptops, phones, remote controlled video games). You may use this equipment when unplugged.

How Do I Mark Events?

These are the things to write down on the Event Sheet:

• Any time you pushed the Event Button, even if accidental.
• If you start to feel a seizure, spell, or one of your typical events, or if you think you had one of these events.
• If you feel dizzy or lightheaded.

You should also write down these things on the Event Sheet (but do not push the Event Button):

• When you eat and drink (you do not have to describe what you are eating and drinking).
• When you take your medication.
• Anything unusual that may happen.

How Do I Remove The Electrodes? 

• Start by removing the bandage. 
• Cut the electrodes anywhere along the wrapped cable between the head and the machine. These are disposable and can be thrown away.
• Dampen a washcloth with warm water, and apply to each electrode site. The adhesive gel will soften after a few minutes and the electrodes will lift off the head.  Take a warm shower or bath and wash your hair with shampoo. This will help remove remaining gel.
• Return the equipment to the Epilepsy Center at your allotted time. It is important for the equipment to be returned on time as it is booked for another patient..

Returning Your Equipment

You will have been given a time to return your device. Please return your Event Sheet and all test equipment at or before this scheduled time. It is important that the ambulatory device is returned at or before this time so that we can download your EEG for reviewing by our doctors.

Questions or Concerns

If you have any technical questions regarding your ambulatory machine, please call us, 24 hours, at: (212) 263-8300. Note that this is the inpatient EEG Lab; at times, the phone may be unattended as our staff responds to inpatient needs.

If you have scheduling questions, please call us, during business hours, at (646) 558-0800.

© NYU Langone Health. All rights reserved. Reviewed for health literacy. This information is not intended as a substitute for professional medical care. Always follow your health care provider's instructions.