EEG Test

An EEG, or electroencephalogram, is a safe and painless test that checks your brain activity. The test records the electrical activity in your brain. Baptist Health providers use EEGs to learn about your brain and to guide treatment.

How an EEG works

Your brain has billions of cells that give off tiny electrical signals when they talk to each other. Together, these signals form brain waves. Your neurology technician will place small sensors on your scalp that pick up these signals. The sensors display the signals as wavy lines on a screen. Your neurologist will study these brain wave patterns. Different patterns can have different meanings. An abnormal pattern can help your provider make a diagnosis.

An EEG does not send electricity into your brain. Instead, it records your natural brain activity.

Why a Provider May Order an EEG

An EEG is a common test for epilepsy. Providers use it to look for the reason for seizures. It can also let them know what type of seizure you experienced. However, an EEG can also help providers with other health conditions.

A provider might order an EEG for these conditions:

• Brain tumors
• Dementia
• Head injuries
• Headaches
• Brain swelling
• Dizziness
• Sleep problems
• Memory loss
• Fainting

Your provider might use an EEG to check the brain activity of someone in a coma. If you take medication for seizures, an EEG can tell your provider how well it is working. An EEG can also confirm brain death.

Types of EEG Tests

There are several types of EEG tests. Your provider will choose the one that best fits you and your symptoms.

Types of EEG tests:

• Routine EEG. This is a standard test most likely performed in an office or clinic. It usually takes between 20 and 40 minutes.
• Prolonged EEG. This type of EEG takes longer than a standard test. You can expect the test to last 1 to 2 hours. The longer test gives your provider more data about your brain.
• Ambulatory EEG. An ambulatory EEG is done at home. Your provider will give you a small monitor to wear. You will wear it for 1 to 3 days. Otherwise, you will go about your day as usual. You will return the monitor once the test is completed.
• Video EEG. A video EEG occurs at the hospital. It can take a few days. During the test, a camera records you while the test records your brain activity.
• Sleep EEG. As the name suggests, this type of EEG is done while you sleep.

How to Prepare for an EEG

Your care team will explain what you need to know to get ready for an EEG.

Follow these general guidelines:

• Wash your hair the night before. Avoid using conditioner or styling products. They can make it harder for the sensors to stick.
• Do not drink caffeine for 8 to 12 hours before the test.
• Eat normally. Low blood sugar can affect the test.
• Tell your provider about any medications or supplements you take.
• Follow any sleep instructions from your provider.
• Remove any hair extensions that use glue.

What to Expect During an EEG

An EEG is a simple, painless test. You usually sit in a chair or lie down on a hospital bed. A technician will first measure your head. Then they make small marks on your scalp. Those marks indicate where they will place the sensors.

Next, the technician will apply a cream that helps the sensors work better. They will place about 20 sensors on your scalp. Sometimes, the technician will use a soft cap with sensors.

During the EEG, you can keep your eyes open or closed. Your technician might ask you to go through a few breathing exercises. They might ask you to look at a light that flashes. Another possibility is that they ask you to open and close your eyes. Each action can change your brain waves.

After an EEG

After an EEG test, the technician will remove the sensors. Most people go home and can resume normal daily activities right away. If you took medicine to help you sleep, you may still feel the effects for a little while.

A neurologist will examine the test results. Then, they send those results and their recommendations to the provider who ordered the test. This could be your primary care provider. Your results will also show up in MyChart.

Your provider will go over the test results with you and explain what they mean. For example, an unusual pattern can point to a health condition.

Is an EEG Safe?

An EEG is safe and painless. The test records your brain waves. It does not send any electricity into your brain or body. One rare risk applies to those with a history of seizures. For those individuals, the flashing light or breathing activities could trigger a seizure. The technician and care team will be closely monitoring you during the test for your safety.