Who is Madeleine J. from The Man Who Mistook His Wife for a Hat and Other Clinical Tales and what is their importance?

Madeleine J. is a delightful patient in her sixties. She has been taken care of by others since her earliest childhood because she does not have use of her hands. When she arrives in the hospital she tells Sacks she does not even recognize that she has hands. In Madeleine's eyes, her hands are just useless lumps.