Transient epileptic amnesia secondary to hippocampal dysplasia mimicking transient global amnesia

Abstract

Transient epileptic amnesia (TEA) is a recently recognized sub-type of temporal lobe epilepsy. TEA is characterized by brief, recurrent attacks of amnesia in late middle to old-aged subjects, averaging 60 years of age [ 1 Mosbah A. Tramoni E. Guedj E. Aubert S. Daquin G. Ceccaldi M. et al. Clinical, neuropsychological, and metabolic characteristics of transient epileptic amnesia syndrome. Epilepsia. 2014; 55: 699-706 Crossref PubMed Scopus (37) Google Scholar , 2 Bartsch T. Butler C. Transient amnesic syndromes. Nat Rev Neurol. 2013; 9: 86-97 Crossref PubMed Scopus (63) Google Scholar ]. In nearly half the cases, patients complain of long term accelerated forgetting and autobiographical memory impairment in 70% [ [2] Bartsch T. Butler C. Transient amnesic syndromes. Nat Rev Neurol. 2013; 9: 86-97 Crossref PubMed Scopus (63) Google Scholar ]. Bartsch and Butler proposed diagnostic criteria [ [2] Bartsch T. Butler C. Transient amnesic syndromes. Nat Rev Neurol. 2013; 9: 86-97 Crossref PubMed Scopus (63) Google Scholar ]. However, diagnosis may be difficult because TEA is an epileptic syndrome where seizures can be subtle and may not be recognized. Furthermore, amnestic attacks represent a wide clinical spectrum and may result from other causes, including transient global amnesia (TGA), functional amnesia, closed head injury, limbic encephalitis, or drug use. Differentiation between TEA and TGA can be difficult because these two entities share common symptoms and common diagnostic criteria [ [2] Bartsch T. Butler C. Transient amnesic syndromes. Nat Rev Neurol. 2013; 9: 86-97 Crossref PubMed Scopus (63) Google Scholar ]. Here, we report the case of a 63 year old woman who presented with what was taken to be an episode of TGA and who then consulted for memory complaints a few years later. Diagnosis of TEA secondary to hippocampal dysplasia was made.