Transient global amnesia represents an episode of acute onset of transient global anterograde amnesia, with a variable degree of impairment of retrograde memory, which is not associated with any other major neurologic signs or symptoms. Resolution is gradual, with subjective recovery occurring in two thirds of patients within 2 to 12 hours and, in almost all, within 24 hours. It has been suggested that not only is memory affected, but executive functions are diminished as well. The etiology is still controversial, and there are a few posited hypotheses, which will be discussed herein.
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• Transient global amnesia is characterized by acute onset of transient global anterograde amnesia that is not associated with any other major neurologic signs or symptoms.
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• Amnesia episodes typically last less than 10 hours, but some can last up to 24 hours.
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• Recurrence is low, probably around 5% per year.
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• In a significant percentage of cases, a precipitant factor (physical or psychological) can be identified.
Historical note and terminology
Neurologists C Miller Fisher and Raymond D Adams coined the term "transient global amnesia," but this syndrome was first described in 1956 by Bender as the "syndrome of [an] isolated episode of confusion with amnesia" and by Guyotat and Courjon as "l’ictus amnesique" or amnestic ictus (15; 54; 38). Probably before 1950 it was interpreted either as a psychogenic amnesia or as an amnesia occurring after an emotional shock (45). Criteria for the clinical syndrome of transient global amnesia were formulated by Hodges and Warlow (62), and since then, these criteria have been the foundation for diagnosis (141). The essential features are an episode of acute onset of transient global anterograde amnesia, with a variable degree of impairment of retrograde memory, which is not associated with any other major neurologic signs or symptoms (15). Since this syndrome’s recognition, controversy has surrounded its pathogenesis, treatment, and prognosis.