Acute and chronic pain: where we are and where we have to go.

In recent years, increasing attention has been focused on the treatment of acute and chronic pain with a considerable number of publications about it. Nevertheless all the attention focused on it, the evidence of pain treatments is still unfolding, and occasionally conflicting. Hence it is still necessary that we point out our research efforts in trying to obtain a better understand of pathophysiology of pain and of real efficacy and safety of acute and chronic pain treatments. Our goal with this review is to summarize the latest research trends and the most advanced therapeutic standards for pain syndromes described in the literature, the discussion will be divided in four main topics, as these topics were treated during the SIMPAR (Study In Multidisciplinary PAin Research) meeting, held on December 2010 in Pavia: pathophysiology of pain, acute postoperative pain, opioids and pain, and chronic pain (Failed Back Surgery Syndrome). In the chapter of pathophysiology of pain we analyzed how to obtain a more personalized treatment through the study of the genetic and neurophysiological characteristics of patients and how to select the right local anesthetic according to anatomic and metabolizing patterns of patients. In acute postoperative pain we focalized our attention on the evidence supporting the use of continuous peripheral nerve blocks in the treatment of postoperative pain and in the prevention of chronic persistent post-operative pain, with a special attention in preventing side effects of regional anesthesia. We also reviewed the current evidence about the use of new very interesting modality to control postoperative pain after laparoscopy: pre-emptive nebulization of local anesthetic in abdominal cavity. As opioids are currently widely used to control chronic oncologic and non-oncologic pain, in this review we analyzed the level of evidence for their use, how to manage them better and psychological factors that can affect their success and/or determine addiction. Finally, we summarized the current evidence about Failed Back Surgery Syndrome focalizing our attention both in diagnosing it correctly and treating this syndrome with specific knowledge of the anatomic space that we have to approach and applying the possible treatments depending on pain pathophysiology and patient characteristics. In conclusion, it is important to try to personalize even better the therapy of patients with acute and chronic pain through a more accurate knowledge of anatomy, pathophysiology of pain, pharmacokinetic of pain drugs and of new device/therapies available.