Articles: hyperalgesia.
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Spinal glial activation has been implicated in sustained morphine-mediated paradoxical pain sensitization. Since activation of glial CB2 cannabinoid receptors attenuates spinal glial activation in neuropathies, we hypothesized that CB2 agonists may also attenuate sustained morphine-mediated spinal glial activation and pain sensitization. ⋯ A CB2 (AM 630) but not a CB1 (AM 251) antagonist mitigated this effect. AM 1241 co-treatment also attenuated spinal astrocyte and microglial marker and pro-inflammatory mediator (IL-1β, TNFα) immunoreactivities in morphine-treated rats, suggesting that CB2 agonists may be useful to prevent the neuroinflammatory consequences of sustained morphine treatment.
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Most post-herpetic neuralgia (PHN) patients suffer from tactile allodynia (pain evoked by lightly touching the skin) and it is frequently the dominant clinical manifestation. The pathophysiology of tactile allodynia in PHN patients is poorly understood and this is one of the major limits to the development of appropriate therapies. Epidermal nerve fibres (ENFs) are free nerve endings of small-diameter A-delta and C primary afferents, which can easily be assessed by neurodiagnostic skin biopsy (NSB). ⋯ Results showed that epidermal innervation was lower in the allodynic skin than in the contralateral skin, although there was great variability among patients. There was no correlation between severity of allodynia and epidermal innervation of the PHN skin. In conclusion, the present study further indicates peripheral nervous system involvement in PHN but does not support a direct correlation between epidermal innervation changes and tactile allodynia.
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The purpose of this systematic review was to summarize and critically appraise the results of 10 years of human laboratory research on pain and sex/gender. An electronic search strategy was designed by a medical librarian and conducted in multiple databases. A total of 172 articles published between 1998 and 2008 were retrieved, analyzed, and synthesized. ⋯ The majority of the studies that measured pain intensity and unpleasantness showed no sex difference in many pain modalities. In summary, 10 years of laboratory research have not been successful in producing a clear and consistent pattern of sex differences in human pain sensitivity, even with the use of deep, tonic, long-lasting stimuli, which are known to better mimic clinical pain. Whether laboratory studies in healthy subjects are the best paradigm to investigate sex differences in pain perception is open to question and should be discussed with a view to enhancing the clinical relevance of these experiments and developing new research avenues.
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Randomized Controlled Trial Comparative Study
A comparison of the hypoalgesic effects of transcutaneous electrical nerve stimulation (TENS) and non-invasive interactive neurostimulation (InterX(®)) on experimentally induced blunt pressure pain using healthy human volunteers.
Non-invasive interactive neurostimulation (InterX(®)) delivers high amplitude electrical pulsed currents at points of low impedance on the skin. This study compared the hypoalgesic effect of non-invasive interactive neurostimulation with transcutaneous electrical nerve stimulation (TENS). ⋯ Given the limited power of this study, we show that there were no significant differences in hypoalgesia between non-invasive interactive neurostimulation and TENS. Unlike our previous studies we also failed to detect a change pain threshold during TENS. Nevertheless, our findings can be used to inform the design of an appropriately powered study on pain patients.
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The objective of this study was to investigate whether pressure hypersensitivity over deep tissues is a feature of acute inversion ankle sprain. ⋯ This study showed the presence of localized pressure pain hypersensitivity over ankle ligaments in patients with unilateral acute inversion ankle sprain, confirming the presence of localized peripheral sensitization.