The ten minutes before the fall
A 52-year-old man is seen the day after falling from a ladder and striking his head. He is alert, oriented, and able to hold a normal conversation, forming new memories of the assessment without difficulty. When asked about the fall itself, however, he cannot recall anything from roughly the ten minutes before it happened; his last clear memory is of starting to climb the ladder, but the specific task he was doing at the top, which his wife says he had just finished, is entirely missing for him. He is not distressed by this gap and accepts that it happened without trying to invent an account of it.
This is retrograde amnesia: loss of memory specifically for a period before the onset of the causal event, here the head injury from the fall, while his ability to form new memories afterward remains intact. The gap being brief (roughly ten minutes) and confined to the period immediately preceding the injury is typical of straightforward acute head injury, and his simple acceptance of the gap, without inventing material to fill it, distinguishes this from confabulation.
References
- Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 5, 'Disorders of Memory'.