[Chronic pain after surgery]

The frequency of chronic postsurgical pain is high, ranging from 10 to 80%. Among the factors promoting it are the existence of preoperative pain, the intensity and duration of postoperative pain, and the type of surgery. It frequently has a neuropathic aspect. Because intraoperative nerve injuries are commonly associated with severe postoperative pain, and as neuropathic and inflammatory pain share neuroplasticity mechanisms, it is usually difficult to know which is responsible for the development of these mechanisms after surgery. Few studies have thus far evaluated methods for preventing chronic postsurgical pain, and their results are conflicting. Recent studies indicate, however, that the use of perioperative regional analgesia is associated with a reduced incidence of chronic postsurgical pain, compared with patient-controlled intravenous morphine. Antihyperalgesic drugs, such as NMDA antagonists, may also decrease chronic postsurgical pain by reducing its perioperative hyperalgesic component.