Our grandfather who is an elderly patient is also undergoing treatment after a severe brain operation. He is sometimes conscious and alert. He asked to be helped by to count the Omer as he did all his life. He can’t count himself, but he will repeat the words said to him including the bracha. We just want to know how we can tell that he’s mind is good enough for it.

Horav Shlomo Miller’s Shlit’a opinion is that for the purpose of counting Sefira if he responds correctly to some common questions it suffices.