Chronic pain after surgery.

Chronic pain after surgery has until recently been a neglected topic. The extent of the problem ®rst came to light in a survey of patients attending pain clinics in Scotland and the north of England. This survey showed that about 20% of patients attending chronic pain clinics implicated surgery as one of the causes of their chronic pain and, in about half of these, it was the sole cause. An extensive literature search failed to produce any references on the general topic of chronic pain after surgery. There were, however, almost 400 references on chronic pain after speci®c operations, such as mastectomy, cholecystectomy and thoracotomy. The information from this literature search formed the basis of a chapter, entitled `Chronic postsurgical pain', in Epidemiology of Pain, edited by I. K. Crombie and published by the IASP Press in 1999. Much of the information in this review is published in greater detail in that chapter and I am grateful to IASP Press for permission to use some of the material included in it. One of the problems facing anyone reviewing this topic is the quality of the publications. Many of the studies identi®ed by the literature search were of poor quality. For example, in some of the papers the methods section explained how to do the surgical operation but, in some cases, did not clearly identify the number of patients investigated, the de®nitions used, the follow-up time or the outcome measures. Many of the problems that will be addressed below (see De®ning chronic post-surgical pain) were simply ignored in most studies. One of the interesting ®ndings from the literature is that studies which are designed speci®cally to investigate the incidence of chronic pain after any operation always ®nd a higher incidence than studies in which chronic pain is studied only as part of a much broader investigation. It also has to be said that these broader studies tend to be less well conducted, often with serious methodological ̄aws. The content of this review will be as follows. An attempt will be made to de®ne chronic post-surgical pain and to discuss some of the dif®culties in reaching a workable de®nition. The pain syndromes associated with many individual types of operation will be discussed brie ̄y, with reference to some of the publications in each category. Where appropriate, information will be displayed in table form. The management of patients with chronic postsurgical pain will be mentioned, but not reviewed in detail. Lastly, the reasons for the neglect of the subject of chronic post-surgical pain will be explored and some suggestions made about how this could be recti®ed.