Making Sense Out of an EEG

Lately a number of questions have arisen in our Connect Community about the meaning of EEG findings. It can be very confusing when someone has an EEG and is told that it was normal. Yet, it’s equally confusing when a person is told there was a lot of activity or specific kinds of activity found. The main question in both situations – What does this mean for your unique situation?

Let’s start with the normal EEG.

A routine EEG or an EEG of any kind that is read as normal when a person is not having any observed or subjective symptoms may not mean much. It does mean that during that period of time, seizure activity as evidenced by bursts of abnormal electricity was not seen.

It’s important to remember that seizures are episodic, meaning they are events with a beginning and end. They don’t occur all the time, so changes on an EEG won’t be seen all the time.

If a person continues to have episodic events and the diagnosis is not clear, then EEG telemetry may be recommended. This test tries to record the EEG when the person is having symptoms thought to be seizures. Then the electrical activity of the brain at the time of the symptoms can be looked at in detail. This is the best way to tell if an episode or event is an epilepsy seizure.

What does it mean when an EEG shows spikes, sharp, or slow waves?

First it’s important to realize that it may mean something very different for each person.

• Some waveforms or activity on an EEG are normal, while others may be within normal limits for some people but not others.
• Spikes or sharp waves are terms commonly seen in EEG reports. If these happen only once in a while or at certain times of day, they may not mean anything. If they happen frequently or are found in specific areas of the brain, it could mean there is potentially an area of seizure activity nearby.
• EEG reports can be confusing when terms refer to where seizure activity may be arising or spreading.
  • Generalized activity would mean that the electrical activity is affecting both sides of the brain. It may or may not be able to report where activity is starting.
  • Areas that give a specific location (such as temporal, frontal, parietal, or occipital) are referring to specific parts of the brain. Again, when a specific brain area is mentioned, it does not necessarily mean that seizures are starting there. It may suggest that this area is involved in some way and that further testing may be needed to know for sure.

How can I learn more about EEGs?

When you or your loved one has an EEG or any kind of test, schedule an appointment to talk about the results and what they mean.

• Ask for examples, pictures, or whatever may help you understand what it means.
• Don’t assume you know what the medical terms mean – ask! The words used in reports can be very confusing.

Ask what the next step should be.

• Does the initial test results suggest other tests are needed?
• Or is this enough to say you should be taking medication or may need a change in treatment?

Connect with others

Use friends and online communities to share experiences and concerns, but don’t look for medical advice online. Remember, each person is an individual and test results of any kind need to be interpreted by someone knowing your medical history, symptoms, and other health issues.

Visit the Epilepsy Foundation Connect Forums.

• Forum Topics
• Diagnostic Dilemmas and Testing

Check out the Chat Room anytime from anywhere in our Connect section.

• Visit Thursday nights from 8 to 9pm east coast time to ask questions and find resources from a Community Moderator.

Hope this helps! Each month we’ll highlight common questions or discussions from our community.

Best wishes for a safe and happy week,

Patty Osborne Shafer RN, MN
Associate Editor/Community Manager