The dynamic time course of memory recovery in transient global amnesia
- 1Inserm E0218, Laboratoire de Neuropsychologie, Université de Caen, CHU Côte de Nacre, Caen, France
- 2Ecole Pratique des Hautes Etudes, Université René Descartes, Paris, France
- 3Institut de Psychologie, Université René Descartes, Paris, France
- 4Service de Neurologie Vastel, CHU Côte de Nacre, Caen, France
- Correspondence to: Professor F Eustache Inserm E0218-Université de Caen, Laboratoire de Neuropsychologie, CHU Côte de Nacre, 14033 Caen Cedex, France;
- Received 30 July 2003
- Accepted 26 January 2004
- Revised 23 January 2004
Aims: To investigate the dynamic time course of transient global amnesia (TGA)—that is, the process of recovery and the interindividual variability—by testing four patients during the day of TGA itself (on three occasions) and at follow up (on two occasions).
Methods: A specially designed protocol focusing on semantic (both conceptual and autobiographical knowledge) and episodic (both anterograde and retrograde components) memory.
Results: Every patient showed marked impairment of both anterograde and retrograde episodic memory during the acute phase, with a relative preservation of personal and conceptual semantic knowledge. During the following phase, the authors observed similarities and differences among the patients’ patterns of recovery. In general, retrograde amnesia recovered before the anterograde amnesia and anterograde episodic memory was recovered gradually in every case. In contrast, shrinkage of retrograde amnesia was more heterogeneous. In two of the patients, this shrinkage followed a chronological gradient and the most remote events were recovered first. In the two other patients, it depended more on the strength of the trace, and there was no temporal gradient. For the latter, an executive deficit could account for difficulties in accessing both conceptual knowledge and autobiographical memories.
Conclusions: This profile of recovery suggests a “neocortical to medial temporal” process in every case, and the possibility of an additional frontal dysfunction in some cases. Hence, the acute phase seems to be characterised by a common episodic impairment. This variability between subjects appears in the recovery phase with two different patterns of impairment.