Transient global amnesia: characterization of anterograde and retrograde amnesia.

Five patients with transient global amnesia (TGA) were given neuropsychological tests during and after their episode. During TGA, all patients were impaired on tests of new learning ability for both verbal and nonverbal material. Retrograde amnesia was patchy and covered a variable period of time before the onset of the episode: from about 36 hours in one case to 4 years in two cases. Some cognitive impairment in addition to amnesia was present during the episode. For example, patients copied a complex figure more poorly during the episode than afterwards. All patients had normal memory at follow-up testing. These data are consistent with the idea that the amnesic symptoms of TGA are caused by transient bilateral dysfunction of medial temporal brain structures important for memory.