P-EP023. Ictal video electroencephalogram of an amnesic attack on waking in a transient epileptic amnesia patient: evidence for postictal rather than ictal amnesia

Abstract

Introduction. There have been few reports on the ictal video electroencephalogram (VEEG) of amnesic attacks in patients with transient epileptic amnesia (TEA). TEA attacks often occur on waking, but the reason remains unclear. Results. A 65-year-old man had a three-month history of recurrent episodes of antero- and retrograde amnesia. The episodes lasted for 10–20 minutes and occurred 2-3 times per month. Brief episodes of behavioral arrest were also witnessed. TEA was suspected, but routine EEG was equivocal. Therefore, we performed a long-term VEEG monitoring. On the second night of the monitoring, a focal onset seizure with subtle motor manifestation occurred during N2 sleep. Following sudden onset tachycardia, EEG seizure patterns arose from the right temporal regions, spread to the left, and terminated in about 90 seconds. About 20 seconds after the seizure cessation, he awoke while EEG was almost normal. On awakening, he showed transient amnesia lasting around 30 minutes, which was confirmed by bystanders. Both antero- and retrograde amnesia were observed. The diagnosis of TEA was made. Lacosamide 50 mg twice daily resolved seizures. Conclusion. We provide the first evidence that TEA attacks on waking reflect postictal hippocampal dysfunction due to unrecognized seizures during sleep. This finding is in line with that the duration of TEA episodes is longer than typical temporal lobe seizures.