When do patients forget their seizures? An electroclinical study.

Accurate knowledge of the frequency of epileptic seizures is a precondition for evaluating the efficacy of pharmacotherapy. It is a well-known fact that the information provided by epilepsy patients about the number of seizures they experience is often unreliable. In the present study, we aimed to identify predictors of a higher risk of unrecognized events. Thirty patients who underwent presurgical evaluation in a video/EEG monitoring unit were recruited. As soon as the patient became aware of a seizure, he or she completed a standardized questionnaire on the subjective perception of the seizure, which was then compared with the video/EEG findings. Of the 138 seizures recorded, 49.3% were reliably detected by the patient, whereas 44.2% went unnoticed; the remainder were incompletely or uncertainly perceived. Subjects in whom events occurred during sleep or originated in (or propagated to) the left temporal lobe had a significantly higher percentage of unrecognized events.