Abstracts

Rationale: There is little published data on the ictal characteristics of patients with transient epileptic amnesia (TEA). The cause of accelerated long-term forgetting (ALF) or remote memory impairment (RMI) in TEA is unclear. This report highlights the finding of frequent subclinical seizures as a potential contributing factor for cognitive concerns in TEA. Methods: Summaries of two patient cases presenting with similar memory complaints who underwent prolonged video electroencephalogram (EEG) monitoring in the epilepsy monitoring unit (EMU) at Mayo Clinic Hospital in Rochester, Minnesota. Results: Two patients with focal bitemporal lobe epilepsy shared features of anterograde and retrograde autobiographical amnesia, sleep-activated epileptiform activity, and frequent subclinical seizures. Memory impairment improved in both patients with successful treatment of their seizures. Case 1: A 59 year old woman presented with memory impairment. Over 18 months, she had 3 distinct episodes of confusion and disorientation lasting approximately 8 hours each along with persistent anterograde and retrograde autobiographical amnesia. Video-EEG recorded frequent interictal bitemporal sharp waves during sleep and 14 subclinical seizures (1 left and 13 right temporal; 11 from N2 sleep, 2 awake, and 1 unstated). Successful treatment of the seizures documented in a subsequent seizure-free EMU admission resulted in subjective cognitive and memory improvement to near baseline at 2 month follow-up. Case 2: A 50 year old woman with known focal epilepsy presented with memory complaints. Over the course of 1 year, she had two discrete episodes of amnesia lasting 2 hours each, with ongoing anterograde and retrograde autobiographical amnesia. Video-EEG recorded independent bitemporal sharp waves, and 14 seizures (2 left and 12 right temporal onset; 11 during light NREM sleep, 2 during drowsiness, and 1 during sleep-wake transition). Successful treatment of the seizures with a subsequent normal 48 hour ambulatory EEG resulted in improvement in memory and work performance. Conclusions: While the etiology of ALF and RMI in TEA is unknown, these cases suggest that frequent sleep-related seizures may contribute to cognitive impairment, and highlight the importance of diagnostic video-EEG monitoring. Analysis of ictal characteristics of TEA in a larger series of patients may further clarify potential associations of sleep-related seizures with cognitive impairment. Funding: None