It happened to my father, who was suffering a severe mental decline because of hydrocephalus. After weeks of trying to figure out what happened, one day he was sitting in the hospital perfectly fine, talking normally. I remember being so relieved. But then the next day he was back to not knowing anything and being half aware. He died a few weeks later.

I'm sorry but it didn't happen to him.

The phenomenon being discussed here is terminal lucidity. Hours or a day or two before passing.

totally believe you, but i guess i feel like that is different from spontaneous temporary recovery from a long-term neurodegenerative disorder. i'm sorry for your loss.