a condition in which someone is unable to remember things that happen before the event that caused the condition, which may be a brain injury, a serious illness, a stroke (= a change in the blood supply to the brain that can make you unable to move particular parts of the body), etc.

Diseases such as dementia cause gradual retrograde amnesia. 像痴呆这样的疾病会渐渐导致逆行性遗忘症。

An epileptic fit may be followed by a brief period of retrograde amnesia. 在癫痫发作之后可能会发生短暂的逆行性遗忘症。