Pain
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Complex Regional Pain Syndrome (CRPS) is clinically characterized by pain in combination with sensory, autonomic, and motor symptoms that may include weakness, tremor, myoclonus and dystonia of the affected limb(s). The syndrome is multifactorial in origin and mostly attributed to tissue injury. There is some evidence that the human leukocyte antigen (HLA) system plays a role in the pathophysiology of CRPS, but previous studies lacked power. ⋯ HLA-B62 (OR=2.05 [95% CI 1.41-2.99], P=0.0005) and HLA-DQ8 (OR=1.75 [95% CI 1.20-2.57], P=0.005) were found significantly associated with CRPS and dystonia. The association remained significant after correction (HLA-B62 P(corrected) [P(c)] = 0.02 and HLA-DQ8 P(c)=0.04). The involvement of HLA-B62 and HLA-DQ8 in CRPS with dystonia may indicate that these HLA loci are implicated in the susceptibility or expression of the disease.
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Clinical Trial
Functional and structural nerve fiber findings in heterozygote patients with Fabry disease.
Fabry disease is an X-linked inherited lysosomal disorder with dysfunction of the lysosomal enzyme alpha-galactosidase A causing accumulation of glycolipids in multiple organs including the nervous system. Pain and somatosensory disturbances are prominent manifestations of this disease. Until recently disease manifestations in female carriers of Fabry disease have been questioned. ⋯ Sensory nerve action potential amplitude and maximal sensory conduction velocity were not different, whereas there was a highly significant reduction in intraepidermal nerve fiber density. We found no correlation between pain VAS score, quantitative sensory testing and intraepidermal nerve fiber density. Our study demonstrates that careful evaluation of symptoms in female Fabry patients is important as small fiber disease manifestations are present, which in some cases is only detected by skin biopsy.
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Recent meta-analyses find various magnitudes of placebo analgesia effects in placebo mechanism trials versus placebo control trials, which have led to debate. To further investigate the magnitude of placebo analgesia in placebo mechanism trials the databases "PubMed", "PsycINFO" and "Web of Science" (2002-2007) were searched with the term "placebo analgesia". Twenty-one articles including 24 studies fulfilled the selection criteria (concerning: mechanisms, control, placebo treatment, randomization and pain measures). ⋯ The magnitude of placebo effects was larger in studies that used long-term pain stimuli >20s (d=0.96) as opposed to short-term stimuli (d=0.81) and the largest placebo effects were found in studies wherein hyperalgesia was present (d=1.88). These results replicate our previous finding that placebo analgesic effects are higher in mechanism studies than in placebo control studies. However, since magnitudes of placebo analgesic effects are highly variable it may be valuable to investigate the factors and mechanisms that contribute to this variability as well as differences in magnitudes across types of studies.
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Many people with hemophilia are affected by chronic arthritic joint pain as well as acute bleeding pain. In this cross-sectional study, 209 men with hemophilia A or B completed the Hemophilia Pain Coping Questionnaire (HPCQ), the Chronic Pain Acceptance Questionnaire (CPAQ), and the RAND 36-item Health Survey (SF-36), a measure of health-related quality of life. Multiple regression was used to test the influence of active pain coping, passive adherence coping, and negative thoughts about pain (HPCQ scales), and activity engagement and pain willingness (CPAQ scales), on physical and mental components of quality of life (SF-36 PCS and MCS scales), taking account of age, hemophilia severity, use of clotting factor, and pain intensity. ⋯ Negative thoughts moderated and partly mediated the influence of pain intensity on mental quality of life. There was no evidence that active pain coping influenced quality of life. The findings suggest that quality of life in hemophilia could potentially be improved by interventions to increase pain acceptance and reduce negative thoughts about pain.
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Pain is a largely subjective experience, and one which is difficult to convey to others, and relies significantly on language to be communicated. The language used to describe pain is therefore an important aspect of understanding and assessing another's pain. A growing body of research has reported differences in the pain experienced by men and women. ⋯ Men used fewer words, less descriptive language, and focused on events and emotions. Common themes were the functional limitations caused by pain, difficulty in describing pain, and the dual nature of pain. Clinical implications include the value of gathering free pain descriptions as part of assessment, and the use of written pain descriptions.