As we come towards the end of IASP's Global Year Against Pain in Women we may wish to take time to think about the differences and similarities between men and women's suffering of pain and to consider the role of sex and gender. Sex is the classification of living things, generally as male or female according to their reproductive organs and functions assigned by the chromosome compliment. Gender is a person's self-representation as male or female, or how that person is responded to by social institutions on the basis of the individuals' gender presentation.
To help us in this thought process, in this special edition of Reviews in Pain, we have collected a number of papers. Firstly the paper by Edmund Keogh examines what the differences are both for the conditions and the treatment outcomes. Many of the mechanisms for these differences are still not understood. Pain related to the specific sex organs might be thought to be an obvious possibility. Beverly Collett provides us with an insight into that for women's pelvic and vulvar pain complimented by an article on the mechanisms of labour pain and its management from Simona Labor and Simon Maguire. Male urogenital pain is explored in a paper by Natasha Curran
By looking at these models of pain we begin to have greater clarity in relation to the causes and one important consideration is the interaction of hormones and pain experience; this is covered in a chapter by Katy Vincent and Irene Tracey. To pull this edition together we have a report on current research concepts in the field of urogenital pain by one of the editors of this edition of Reviews in Pain, Andrew Baranowski.
As we the editors pulled this edition together and our thoughts became more crystallised, it is quite clear that many of the mechanisms that maintain the pain for men and women are the same. That these mechanisms are generally not in the periphery but that the central nervous system is important. In many cases abnormalities of the periphery may be the initiating factors but by the time that patients present to specialist pain clinics the nature of these initiating factors may be lost in time; some recent data does support peripheral factors as maintaining the central changes in certain cases (endometriosis may be an example here). Differences in the sex organs may affect the nature of the trigger, as may sexual behaviour and activities as determined by gender. The particular sex organs will affect the expression of the pain condition, for instance, only men can have testicular pain; but gender-specific psychosocial responses to pain differ too.
Why certain patients develop chronic pain and others do not will depend upon multiple factors. It is this complex interaction between the triggers (initiating factors - see within) and those factors that tend to produce a chronic pain condition from the triggers (progression and maintenance factors, see within) that needs to be studied. Sex and gender will have a very important influence upon these factors, either directly or indirectly, and by studying sex and gender differences we may get a better understanding of all the mechanisms involved.