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Transient amnesia can be a form of epilepsy

23 Aug 2007

Episodes of transient amnesia, which frequently occur on awakening
and are associated with other memory problems, may be a symptom of a
distinct type of epilepsy.

A British team describes this condition they
call "transient epileptic amnesia" in a study published in the Annals
of Neurology.

Adam Z. J. Zeman described transient epileptic amnesia as "repeated
short episodes of transient amnesia, occurring about once a month,
usually lasting about half an hour, often occurring on waking,
typically in middle-aged people around the age of 60."

Zeman and colleagues, from the Peninsula Medical School in Exeter,
recruited 50 patients who had had recurrent episodes of amnesia and
evidence of epilepsy, including EEG abnormalities, response to
anticonvulsant therapy; or clinical features, such as hallucinations
involving the sense of smell.

can be other manifestations of epilepsy during the attack, like a
hallucination of a smell, or a brief period of loss of awareness, but
often the amnesia is the sole manifestation of the seizure."

team found that the condition was often misdiagnosed: only 12 of the 50
patients in the study had received an initial diagnosis of epilepsy.

medication was effective in 44 of the 47 patients treated. "Most of our
patients were treated with carbamazepine, sodium valproate or
lamotrigine and the response to treatment was generally excellent,"
Zeman said.

the 50 patients, 40 described persistent memory difficulties. 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,"
the researchers report.

propose that transient amnesic epilepsy is a distinctive epilepsy
syndrome, typically misdiagnosed... and associated with accelerated
long-term forgetting and autobiographical amnesia," Zeman and his
colleagues concluded.