Amnesia, memory disturbances and epilepsy

Abstract

The epileptic syndromes, notably the temporal lobe epilepsy, frequently include memory disturbances. These memory disturbances may occur during seizures, i.e. ictal memory disturbances, or between seizures, i.e. interictal memory disturbances. Two atypical clinical epileptic syndromes should be pointed out in the elderly: the transient epileptic amnesia and the epileptic pseudodementia. Both represent potentially reversible memory disturbances and have a treatment based on antiepileptic drugs. Transient epileptic amnesia (TEA) is a subtype of medial temporal lobe epilepsy with late onset. TEA is characterized by recurrent episodes of acute transient amnesia lasting less than one hour. The main differential diagnosis is transient global amnesia (TGA). Conversely to TGA, TEA have a shorter duration, is recurrent but have a clear-cut response to antiepileptic drugs. Interictal memory disturbances consist of autobiographic memory disorders and long term forgetting. Epileptic pseudodementia is a pure disturbance of verbal episodic memory, stable over time. It is due to very frequent and recurrent subtle temporal lobe seizures. Response to antiepileptic drugs is less evident.

Keywords: epileptic pseudodementia; memory disturbances; temporal lobe epilepsy; transient epileptic amnesia.