Primum non nocere… The fact that a surgical procedure can leave any kind of pain casts a shadow over this tenet, which is seen as the basis of medical practice and anchor of its principle ethic…It is all the more surprising in that medicine has only paid attention to this paradoxical chronic pain situation for the past few years. Clarifying the knowledge acquired in this field has become all the more urgent for any care-giver today confronted by a legitimate request from patients: Why and how can a surgical procedure, which is supposed to bring relief, leave behind an unacceptable sequela?This is the approach which the contributors to this new subject of major clinical interest invite you to follow as you work your way through this book.