The Man Who Mistook His Wife for a Hat by Oliver Sacks
Oliver Sacks is an amazing neurologist; he approaches his patients from different takes than anyone else, which is what makes this book so stunning. Who would think that a man who had problems walking upright almost like someone suffering from Parkisons' was actually having problems with his inner ear? Sacks writes engagingly, and unlike many medical books his are the complete opposite of long winded authors.
I would recommend this book to anyone who finds medical problems interesting in the slightest or for those of you who simply think that the fact that someone can think their wife is a hat is hilarious.
His other books include Awakening, which includes his descriptions on how catatonic patients can dance to music, sing to music yet can't walk for themselves or talk.
Note: On NOVA pbs Oliver Sacks did a show called Musical Minds, it shows how some people really get music and how some don't. He interviews an autistic patient who is blind yet who can replicate a musical piece he heard after the piece is finished playing.