Transient epileptic amnesia differentiated from psychogenic "fugue": neuropsychological, EEG, and PET findings.

A patient had repeated episodes of transient loss of memory, which had been attributed to psychogenic causes. Preservation of his sense of personal identity and the presence of repetitive questioning indicated an organic basis, however, and the multiplicity of the attacks and their brief duration suggested an epileptic aetiology. Although three standard EEGs, CT and MRI were all normal, two sleep EEGs confirmed bilateral foci in the temporal lobes. The attacks responded to an anticonvulsant. A fluoro-deoxyglucose PET scan, performed a few months after the most recent attack, was normal. The patient also had impaired anterograde memory that persisted six months after recovery from the acute attacks.