Pain
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Comparative Study
Changes in the expression of tetrodotoxin-sensitive sodium channels within dorsal root ganglia neurons in inflammatory pain.
Nociceptive neurons within dorsal root ganglia (DRG) express multiple voltage-gated sodium channels, of which the tetrodotoxin-resistant (TTX-R) channel Na(v)1.8 has been suggested to play a major role in inflammatory pain. Previous work has shown that acute administration of inflammatory mediators, including prostaglandin E2 (PGE2), serotonin, and adenosine, modulates TTX-R current in DRG neurons, producing increased current amplitude and a hyperpolarizing shift of its activation curve. In addition, 4 days following injection of carrageenan into the hind paw, an established model of inflammatory pain, Na(v)1.8 mRNA and slowly-inactivating TTX-R current are increased in DRG neurons projecting to the affected paw. ⋯ The results demonstrate that, following carrageenan injection, there is increased expression of TTX-S channels Na(v)1.3 and Na(v)1.7 and a parallel increase in TTX-S currents. The previously reported upregulation of Na(v)1.8 and slowly-inactivating TTX-R current is not accompanied by upregulation of mRNA or protein for Na(v)1.9, an additional TTX-R channel that is expressed in some DRG neurons. These observations demonstrate that chronic inflammation results in an upregulation in the expression of both TTX-S and TTX-R sodium channels, and suggest that TTX-S sodium channels may also contribute, at least in part, to pain associated with inflammation.
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Comparative Study
Adolescent chronic pain: patterns and predictors of emotional distress in adolescents with chronic pain and their parents.
Adolescents with chronic pain also report severe disability and emotional distress. A clinical sample of 80 adolescents and accompanying parents were investigated to first measure the extent of distress, and second to investigate the relationships between adolescent distress, parental distress and adolescent coping. Measures of pain intensity, anxiety, depression, disability and coping were obtained from adolescents. ⋯ There were no clear predictors of parental anxiety or depression but the specific pattern of parenting stress was best predicted by the younger age of the adolescent, the greater the chronicity of the problem, and the greater the extent of adolescent depression. These findings suggest that emotional coping is a critical variable in the distress associated with adolescent chronic pain. It is argued that adolescent emotional coping may best be understood within a relational context of seeking emotional support.
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Case Reports
Some cases of severe post-mastectomy pain syndrome may be caused by an axillary haematoma.
Post-mastectomy pain syndrome (PMPS) is experienced by 20-65% of patients who undergo breast surgery for cancer. The etiology of this chronic neuropathic pain syndrome is unclear and most likely multi-factorial. Symptoms may be mild, not requiring treatment, or severe, considerably restricting quality of life. ⋯ In these cases the symptoms were completely relieved by the aspiration or formal drainage of an encapsulated haematoma in the axilla. The removal of a minimal amount of blood brought instant improvement suggesting that pressure within the haematoma could be an etiological factor. An axillary haematoma, which may not be clinically obvious, should be considered as a possible cause of PMPS.
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Randomized Controlled Trial Clinical Trial
The cyclooxygenase isozyme inhibitors parecoxib and paracetamol reduce central hyperalgesia in humans.
Non-steroidal antiinflammatory drugs (NSAIDs) are known to induce analgesia mainly via inhibition of cyclooxygenase (COX). Although the inhibition of COX in the periphery is commonly accepted as the primary mechanism, experimental and clinical data suggest a potential role for spinal COX-inhibition to produce antinociception and reduce hypersensitivity. We used an experimental model of electrically evoked pain and hyperalgesia in human skin to determine the time course of central analgesic and antihyperalgesic effects of intravenous parecoxib and paracetamol (acetaminophen). ⋯ In conclusion, our results provide clear experimental evidence for the existence of central antihyperalgesia induced by intravenous infusion of two COX inhibitors, parecoxib and paracetamol. Since the electrical current directly stimulated the axons, peripheral effects of the COX inhibitors on nociceptive nerve endings cannot account for the reduction of hyperalgesia. Thus, besides its well-known effects on inflamed peripheral tissues, inhibition of central COX provides an important mechanism of NSAID-mediated antihyperalgesia in humans.
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The SF-36 is a well-validated health status instrument measuring eight different health concepts. One aim of this study was to compare health status as measured by SF-36 in subjects from the general population with no chronic pain (NCP), chronic regional pain (CRP), and chronic widespread pain (CWP). A second aim was to assess if SF-36 could reflect changes in pain status over time. ⋯ Changes in SF-36 over the 3-year follow up time coincided with improvement or deterioration of pain status. Baseline SF-36 scores predicted pain outcome 3 years later. These results support that both physical and mental aspects of health status as measured by SF-36 are affected by the burden of musculoskeletal pain, are sensitive to changes in pain status, and also predict the further development of pain.