[Pathophysiology of chronic postoperative pain].

Chronic postoperative pain is a most serious, unrecognized problem. Acute postoperative pain can be viewed as the initial step of an extensive, persistent nociceptive and behavioural cascade triggered by tissue and nerve injury. As a result, neuronal plasticity in all parts of the nociceptive system leads to an increase in pain perception. In most patients, chronic postoperative pain resembles neuropathic pain, occasionally however, pain is caused by continuous inflammatory responses. Identification of the etiology of pain is essential for its successful treatment. Both postoperative pain and the risk for the development of chronic postoperative pain are determined by preoperative, intraoperative, and postoperative factors. To identify the contribution of relevant determinants and modulators of postoperative pain, large prospective controlled clinical studies are urgently required that include measurement and documentation of all risk factors and procedure-specific aspects.