ABSTRACT
The response of the nervous system to acute tissue injury is a sensitization of the tissues including and surrounding the injury. This permits recuperation and recovery because it produces behavior that avoids contact with all external stimuli. This response is common to all animals with a nervous system and is present in humans. Clearly, this response has a survival advantage, but evolution has not anticipated the development of the ‘‘controlled injury’’ in the form of surgery. In the context of modern surgical techniques and practice the sensitization that leads to pain and inactivity is no longer desirable. The rational management of acute pain is designed to anticipate and suppress this defense mechanism, and postoperative pain gives us the opportunity to plan analgesia from before the injury occurs.
