Ictus amnésique

Transient global amnesia (TGA) is an acute impairment of episodic anterograde and retrograde memory that lasts less than 24 hours and recovers completely. It affects mostly people over 50 years, often after a physical or emotional stress. It recurs in about 10% of cases. Its cause is unknown. The diagnosis is based on clinical grounds but can be confirmed by DWI magnetic resonance imaging that shows punctate lateral hippocampal hyperintensities. TGA must be differentiated from transient amnestic epilepsy, in which crises are shorter and recur systematically. It has also to be distinguished from stroke, but in exceptional cases it may be symptomatic of potentially serious vascular diseases. The cause of TGA is unknown but it is thought to involve a glutamatergic stress of neurons located in the CA1 field of the hippocampus. There is no specific treatment apart from reassurance and clinical monitoring, provided alternative causes of acute amnesia have been properly ruled out.