TGA is a syndrome that is characterized by anterograde amnesia, loss of short term memory and loss of orientation regarding time, place and situation without loss of long term memory or procedural memory that lasts for 1 to 24hours. Usually there is a retrograde amnesia for the time of the attack. Althought diffusion-weighted magnetic resonance imaging has been able to show small foci of restricted diffusion the reason causing this diffusion defects remains still unclear. Possible explainations inculde vascular events like transitory ischemic attacs, a process similar to migraine or epilepsy as well as psychologic stress.
See:
M?gevand P, Landis T.
Eur Neurol. 2011;66(5):294-5. Epub 2011 Oct 26.
Recognition memory without awareness during transient global amnesia.
Kirshner HS.
Curr Neurol Neurosci Rep. 2011 Dec;11(6):578-82.
Transient global amnesia: a brief review and update.
Johannes Heymer