Transient amnesia linked to epilepsy

Frequent episodes of temporary loss of memory could be a symptom of a distinct type of epilepsy.Besides the association with other mental problems, temporary loss of memory occurring on awakening can be a manifestation of transient epileptic amnesia. This is a distinctive epilepsy syndrome, typically misdiagnosed at presentation and associated with accelerated long-term forgetting and autobiographical amnesia. There can be other manifestations of epilepsy during its attack, like a hallucination of a smell, or a brief period of loss of awareness, but often the amnesia is the only manifestation of the seizure. To study this condition, researchers at the Peninsula Medical School in Exeter studied 50 patients over an 18-month period who had recurrent episodes of amnesia that were witnessed by another person; otherwise intact mental functioning; and evidence suggesting epilepsy, including EEG abnormalities, response to anticonvulsant therapy; or clinical features, such as hallucinations involving the sense of smell.The results indicated that such a condition usually develops in later life. Amnestic episodes were frequent (average, 12/year), brief (average duration, 30-60 minutes), and often occur on waking (37/50 cases). Epilepsy was the initial specialist diagnosis in only 12 of 50 cases. Attacks ceased on anticonvulsant medication in 44 of 47 treated patients. A total of 40 of 50 cases described persistent memory difficulties. The patients demonstrated a loss of autobiographical memory for events extending back over 40 years. They had a normal performance on standard memory tests, but they exhibited accelerated forgetting of verbal and visual material over three weeks by comparison with matched control subjects. Often misdiagnosed as some form of a mental problem, transient amnesic epilepsy is a distinctive epilepsy syndrome, associated with accelerated long-term forgetting and autobiographical amnesia.