noun
retrograde amnesia
Medical term for loss of memory of events that occurred before a trauma or disease onset.
事故の後、彼は逆行性健忘症になり、事故前の数時間を思い出せなくなった。
After the accident, he developed retrograde amnesia and couldn't remember the hours before it.
Anterograde amnesia: inability to form new memories after the event, whereas 逆行性健忘症 affects memories from before the event.
Compound of 逆行性 (retrograde) + 健忘症 (amnesia), a direct medical term.