Transient Epileptic Amnesia - Symptoms

Symptoms

A person experiencing a TEA episode has very little short-term memory, so that there is profound difficulty remembering events in the past few minutes (anterograde amnesia), or of events in the hours prior to the onset of the attack, and even memories of important events in recent years may not be accessible during the amnestic event (retrograde amnesia). Some people report short-lived retrograde amnesia so deep that they do not recognize their home or family members, though personal identity is preserved. The amnestic attack has a sudden onset. Three-fourths of cases are reported upon awakening. In attacks that begin when an individual is fully alert, olfactory hallucinations or a "strange taste" or nausea have been reported. Somewhat less than half the cases include olfactory or gustatory hallucinations, and slightly more than a third involve motor automatisms. A quarter of attacks involve a brief period of unresponsiveness. Frequently, however, there is no warning.

During the attack the person's cognitive functions are not generally impaired; perception, communication, attention are normal for most of the duration of the event. In half the cases reported, behavior includes repetitive questioning to attempt to orient experience as the brain fails to lay down new memories or recall a range of recent experiences. The website of the UK-based organization The Impairment of Memory in Epilepsy (TIME) describes an attack this way:

During an attack, the person is usually unable to remember things that have happened over the past days or weeks. Sometimes, the memory loss may affect events from much further back in the past. In addition, the individual often finds it difficult to retain new information and may ask the same question, such as "What day is it?" or "What are we supposed to be doing today?" repetitively. There is, however, no loss of personal identity and close friends or relatives are usually recognised. The physical appearance of the person is normally unchanged. Observers may, however, notice some pallor of the skin, a brief ‘loss of contact’ such as not seeming to be aware of the person witnessing the attack, or some automatic movements such as swallowing, lip smacking or fidgeting of the hands. In most cases, however, the person responds appropriately to the situation they are in. They carry on conversations and can continue with activities such as getting dressed, walking or even playing a game of golf."

Attacks typically last 20 to 60 minutes. Some attacks may be less than five minutes in duration. Much longer attacks have been reported; in the 2007 study of 50 TEA cases, one lasted four days and one lasted two days. Such unusual presentations "may be due to ongoing seizure activity (non-convulsive status epilepticus) or persistent post-ictal dysfunction of memory related brain structures."

As the amnesia resolves, the person may recall very little about it, although some memory may be retained of the fact of an episode. Of greater consequence than this brief gap are three common persistent memory complaints among people who have experienced TEA: difficulty recalling knowledge recently gained (accelerated forgetting); difficulty recalling events in one's personal life over a period of decades (autobiographical amnesia); and difficulty with spatial memory, recalling routes or places and the navigational cues that are associated with them (topographical amnesia), discussed below.