[Clinical types of memory disorders and their diagnosis]

Three major types of amnesia, i.e. selective deficit of memory formation without disturbance of immediate memory have been recognized clinically. The hippocampal type is characterized by relatively short retrograde amnesia and preserved insight into his own amnesic trouble. Persistent amnesia is always associated with bilateral lesion. The diencephalon type usually shows longer retrograde amnesia and poor insight. Unilateral lesion is usually modal in deficit, i.e. verbal in the left and non-verbal in the right, and lacks clear evidence of retrograde amnesia. Responsible locus within the thalamus is still controversial. Our experience point to the mammilothalamic tract. The basal forebrain type is characterized by disorganized and confused recollection of the memorized items. Cued recall is fair compared to voluntary recall. Two special types of amnesic syndrome, i.e. transient global amnesia and isolated focal retrograde amnesia are also important clinical entities, although their etiologies and responsible lesions are not clear yet.