Isolated and focal retrograde amnesia: A hiatus in the past

Two cases of isolated retrograde amnesia were reported. Both showed the sam e clinical pattern in development and resolution of amnesia despite of diff erent etiologies. Sudden insult to the brain (trauma in Case 1 and viral en cephalitis in Case 2) caused concurrent antero- and retrograde amnesia. For tunately both recovered from the anterograde amnesia completely. However, b oth were left with a period of postictal amnesia of a few months and retrog rade amnesia of up to 14 months' duration. The analysis of their pattern of temporal evolution and dissolution of amnesia support the hypothesis that recently acquired episodic information requires a certain amount of constan t activation for a certain period of time in order to be organized into a d urable memory. The nature of this activation as well as its origin remains to be solved. - isolated retrograde amnesia; anterograde amnesia; postictal amnesia; memory trace; memory activation (C) 2001 Tohoku University Medica l Press.