Transient global amnesia

The syndrome of transient global amnesia (TGA) is defined and described. Characteristic features, epidemical data, variables possibly provoking TGA, its possible etiology and anatomical basis are reviewed. A transient disturbance in the formation of lasting new memories (usually of less than one day) and a retrograde amnesia (which includes the period of the attack and possibly a short time before) are considered as the main features of TGA. A further trait of TGA is the high age of most of the patients subjected to it (58 years on the average). TGA most likely is based on a transient change in the blood supply of certain regions of the brain. The mechanism by which this change happens is still hypothetical. Regions of the limbic system, in particular the area of the temporal lobe and the hippocampal formation, appear to be affected most likely. Uncertain are: the existence of factors provoking the outbreak of an amnesic attack, the likeliness of multiple episodes of TGA and the neuropsychological alterations in patients who suffered a transient global amnesic attack. The outcome of this review suggests, however, that the incidence of recurrent attacks of TGA is higher than previously assumed and that a transient global amnesic attack may be followed by lasting behavioral deteriorations.