European journal of pain : EJP
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The purpose of this study was to examine differences in heat pain threshold (HPTh) and heat pain tolerance (HPTo) between temporomandibular joint disorder (TMJD) patients and healthy controls. Using suprathreshold heat pain, this study also examined between-group (i.e. TMJD vs. healthy controls) differences in hyperalgesia and temporal summation (TS) of heat pain. ⋯ Data analysis revealed a significant simple mediation effect whereby the presence of TMJD was strongly associated with poorer self-reported sleep quality, which, in turn, was related to enhanced hyperalgesia at 46 °C. These findings support the hypothesis that the thermal hyperalgesia demonstrated by TMJD patients may be related to poor quality of their self-reported sleep. The ability of interventions that improve sleep quality to also affect pain sensitivity is currently the topic of ongoing investigation.
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Randomized Controlled Trial
Sex differences in analgesic response to ibuprofen are influenced by expectancy: a randomized, crossover, balanced placebo-designed study.
To determine whether there is a sex difference in placebo and ibuprofen analgesia expectancy. ⋯ We found no sex difference in baseline pain threshold or tolerance levels. When partitioned by sex and expectancy state, analgesia only occurred in males during positive expectancy states at 2, 3 and 4 h post-placebo, and at 1 and 2 h post-ibuprofen. The time course of analgesic action in males was as expected considering the pharmacokinetic profile of ibuprofen. Our study found that dosages of 800 mg of ibuprofen are ineffective in producing analgesia in women regardless of their expectations. We hypothesize that ibuprofen analgesia is produced by a combination of specific pharmacological effects and a non-specific beta endorphin-mediated placebo effect. Whatever the mechanism responsible for the analgesic response seen in males, this research re-emphasizes the importance of psychological factors in determining drug response. It also shows that these factors can differ between men and women, and thus the contribution of psychological factors on analgesia needs to be seriously re-evaluated.
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The COMT enzyme metabolizes catecholamines and thus modulates adrenergic, noradrenergic and dopaminergic signaling. A functional polymorphism in the gene encoding this enzyme, i.e. the COMT Val158Met SNP that reduces enzyme activity, has previously been linked to pain sensitivity. ⋯ We conclude that the functional COMT Val158Met SNP contributes to long lasting low back pain, sciatica and disability after lumbar disc herniation.
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It is not known whether general practitioners (GPs) prescribe analgesic medication according to intensity of pain or a hierarchical prescribing regimen. ⋯ GPs do not always issue prescriptions for musculoskeletal pain. In cases where a prescription is issued, this is more strongly influenced by previous prescriptions than the patient's pain level. GPs adopt an individualized approach to the treatment of musculoskeletal pain in older adults.
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The rodent acidic saline model of hyperalgesia uses repeat injections of acidic saline in the right lateral gastrocnemius muscle, spaced five days apart, to induce a persistent decrease in hindpaw withdrawal thresholds. The objective of this study was to determine if alternate injection sites would permit development of hyperalgesia. ⋯ These data indicate that anatomically diverse peripheral stimuli can converge within the central nervous system to produce hyperalgesia.