Interictal memory manifestations consist of accelerated long-term forgetting as well as autobiographical and topographical amnesia.

Transient epileptic amnesia usually affects middle-aged or elderly subjects, men (60%) more than women, and the attacks often occurring on waking.Documentation of the epileptic nature of transient epileptic amnesia requires meticulous clinical assessment and EEG.Two third of patients also present with brief seizures of mesial temporal lobe epilepsy.The attacks are frequent, usually around 20 times each year in untreated patients.The duration of episodes of amnesia is usually less than an hour (median duration 30 to 60 minutes).Transient epileptic amnesia has been considered a syndrome of mesial temporal lobe epilepsy with recurrent episodes of amnesia (ictal or postictal).Patients with transient epileptic amnesia usually have an excellent prognosis seizures respond extremely well to monotherapy with small doses of lamotrigine or levetiracetam though interictal memory disturbances may persist. Transient epileptic amnesia is considered rare though it is frequently underdiagnosed or misdiagnosed as transient global or psychogenic amnesia. In most cases of transient epileptic amnesia, no clear cause for the epilepsy is identified though MRI may show hippocampal atrophy or focal structural lesions in the temporal lobes. Interictal EEG, particularly when recorded in sleep, shows temporal lobe spikes whereas EEG during attacks of amnesia demonstrates either ictal discharges or postictal features.

In addition, brief seizures typical of mesial temporal lobe epilepsy are detected in two thirds of patients. The duration of episodes of amnesia is usually less than an hour with usual recurrence of around 20 times each year in untreated patients. Transient epileptic amnesia has been considered a syndrome of mesial temporal lobe epilepsy characterized by (1) recurrent episodes of isolated memory impairment of epileptic cause (ictal or postictal) while other cognitive functions remain intact (2) interictal memory disturbances of accelerated long-term forgetting and autobiographical and topographical amnesia and (3) late age of onset with a mean of 57 years.

Temporary transient global amnesia