The Clinical journal of pain
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Sex differences in the response threshold to painful stimuli and the higher number of chronic pain syndromes in women than in men have prompted a series of studies on lower animals and humans aimed at clarifying the role of gonadal hormones in pain. ⋯ This article examines the morphologic and functional aspects of gonadal hormone systems and the relations between gonadal hormones and pain circuits, to identify areas deserving of increased attention in elucidating the endocrine mechanisms that contribute to abnormal pain states.
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Numerous experimental studies, conducted primarily over the past 10 years, show that there are sex differences in opioid analgesia. This review summarizes the published literature on sex differences in analgesia produced by acute administration of drugs acting at mu-, kappa-, and delta-opioid receptors, in animals and humans. Additionally, methodological issues in research into opioid sex differences are discussed. ⋯ Procedural variables that may influence the outcome of studies examining sex differences in opioid analgesia include modality and intensity of the noxious stimulus used in the pain test, opioid type (efficacy and selectivity), and experimental design and data analytic techniques. Subject variables that may be important to consider include subject genotype and gonadal steroid hormone state of the subject at the time of analgesia testing. Evidence is provided for multiple mechanisms underlying sex differences in opioid analgesia, including both pharmacokinetic and pharmacodynamic factors. Future research directions are suggested, such as examining sex differences in opioid tolerance development, sex differences in opioid analgesia using models of acute inflammatory pain and chronic pain, and sex differences in effects of opioids other than analgesia, which may limit their therapeutic use.
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The aim of this study is to describe the incidence and characteristics of pain, sensory abnormalities, abnormal body sweating, and pathologic gustatory sweating in pain patients with persistent post-sympathectomy pain. ⋯ The present study does not allow for conclusions about the effectiveness of surgical sympathectomy for neuropathic pain. However, our findings indicate that if the pain persists after the procedure, the complications may be quite serious and at times worse than the problem for which the surgery was originally performed.