EEG in Epilepsy

The purpose of this article is to review the fundamentals and limitations of EEG, guide the selection of EEG type to answer clinical questions, and provide instruction on the interpretation of results within the patient's clinical context.

EEG is the single most useful ancillary test to support the clinical diagnosis of epilepsy, but if used incorrectly it can cause great harm. Misapplication of EEG findings can lead to misdiagnosis and long-term mental and physical health sequelae. Although all neurologists may not have sufficient training for independent EEG interpretation, most should be able to review and apply the findings from the report accurately to guide patient care. Longer-term EEGs with similar recording electrodes tend to have higher diagnostic yields. Common EEG findings are described in this article, along with diagnostic limitations of some classically described patterns. There is an updated definition for an epileptiform discharge, along with a consensus on EEG patterns in the critically ill.

EEG continues to be the most useful ancillary test to assist in the diagnosis of epilepsy. Its application requires proper understanding of its limitations and variability of testing results.