Classification of transient epileptic amnesia attacks: Two types of amnestic seizures, the pure amnesia type and partial amnesia type.

Aim: Transient epileptic amnesia (TEA) is a type of mesial temporal lobe epilepsy characterized by recurrent amnesia attacks. In 1998, Zeman et al. proposed the following diagnostic criteria for TEA: (1) recurrent, witnessed episodes of amnesia (TEA attacks); (2) other cognitive functions remain intact during attacks; and (3) evidence of epilepsy. It was also reported that patients with TEA often demonstrate two other types of memory symptoms: accelerated long-term forgetting (ALF) and autobiographical amnesia (AbA). Both ALF and AbA are persistent memory disorders, but transient epileptic seizures are not. Methods: We encountered two cases of TEA associated with two types of amnesia attacks. Therefore, we reviewed TEA cases in the literature to clarify the type of TEA attacks that occurred. Results: Based on the extracted TEA cases, including our two cases, we found that there are two main types of TEA attacks, and we discussed their clinical features. Conclusion: We propose two main types of TEA attacks; that is, pure amnesia-type and partial amnesia-type seizures. Furthermore, we also propose that topographical amnesia mainly manifests as a type of amnesia attack, rather than as a chronic memory disturbance, such as ALF or AbA.