A 57 year old woman presents to her family physician complaining of numbness and tingling in her right thumb, index and long finger for the past four weeks. She repos that she wakes up in the middle of the night with these symptoms and needs to shake her hands to "wake" them up. She denies numbness or tingling in her other hand or either leg. She has no neck or upper arm pain. On physical examination, her symptoms are reproduced by Tinel testing. Her symptoms are also exacerbated by hyperflexion of the wrist. There is decreased sensation over the palmar aspects of the thumb, index and middle fingers. There is no apparent motor weakness. Which of the following is the most likely diagnosis?