How are EEGs used to diagnose epilepsy?

An electroencephalogram (EEG) is a procedure in which a neurologist measures and views your brain waves in order to help diagnose brain diseases. Epilepsy is a syndrome which causes seizures to occur in the brain. You are correct in that an EEG is used to diagnose seizures, and therefore epilepsy. However, it is not quite that simple. An EEG can only detect a seizure when seizure like waves, or seizures themselves are occurring in the brain. A typical EEG only measures brain activity for 1-2 hours up to 24 hours (if you are in the hospital). If your brain is quiet of seizure like activity during this time, the EEG will be unable to diagnose a seizure. This is why so many people that have had a seizure don't officially get diagnosed with epilepsy by EEG. However, it is still very worth while to have an EEG if you have had a seizure. I suggest that you schedule an appointment with your neurologist. He or she can take a history of your seizures and perform a comprehensive neurological exam. If it is seen as necessary, your neurologist will have you come back for an outpatient EEG to look for any seizure activity in your brain.