What are causes of abnormal eeg results?

EEGs are hard: An abnormal eeg can mean many things. Intermittent changes in eeg, like theta discharges or spikes, can be associated with epileptic seizures or other intermittent symptoms like migraine. Continuous changes, like slow background, can be an effect of drugs or internal disorders like liver or kidney disease. Changes in one spot of the head could mean damage like stroke or tumor.