Observations during transient global amnesia. A behavioural and neuropsychological study of five cases

The clinical and behavioural features of 5 patients examined during transient global amnesia (TGA) are described. All underwent extensive neuropsychological testing during and sequentially after the attack. Our results show that in TGA there is a characteristic neuropsychological deficit which parallels that in the permanent amnesic syndrome. Personality, complex cognition and problem solving, semantic knowledge, language and visuospatial function remained intact. Immediate memory was preserved. Longer-term verbal and nonverbal memory was severely disrupted in all cases. In contrast, the extent of retrograde amnesia was highly variable. A famous faces test showed an extensive deficit in 3 cases, with improvement in all cases following the attack. Analysis of group data confirmed the presence of a reversible temporal gradient, in that more distant memories were relatively spared. On a famous events test, recognition was normal across all decades, but dating of events from the 1960s and 1970s was consistently impaired. The Crovitz test of remote personal episodic memory was given to 3 subjects; all showed impaired uncued autobiographical memory and in contrast to normal controls, had a virtual absence of recent memories. During recovery from TGA there was progressive shrinkage of retrograde amnesia but a permanent short retrograde gap of around 1 h remained in all cases. Although subjectively normal within 24 h, all cases demonstrated persisting impairment of new learning for at least a week post-TGA. The relevance of the neuropsychological data to theories concerning the amnesic syndrome is discussed. We postulate a temporary deficit in retrieval of remote memories which appears to be dissociable from the anterograde amnesia.