Articles: hyperalgesia.
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Brain Behav. Immun. · May 2013
Randomized Controlled TrialLow-dose endotoxin potentiates capsaicin-induced pain in man: evidence for a pain neuroimmune connection.
Despite the wealth of evidence in animals that immune activation has a key role in the development and maintenance of chronic pain, evidence to support this in humans is scant. We have sought such evidence by examining the effect of a subtle immunological stimulus, low dose intravenous endotoxin, on the allodynia, hyperalgesia, flare and pain produced by intradermal capsaicin in healthy volunteers. ⋯ These data demonstrate clinically a significant role for the neuroimmune pain connection in modifying pain, thus providing evidence that immune priming may produce pain enhancement in humans and hence offer a novel range of pharmacological targets for anti-allodynics and/or analgesics. Additionally, the simplicity of the model makes it suitable as a test-bed for novel immune-targeted pain therapeutics.
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Randomized Controlled Trial
Experimental myalgia induced by repeated infusion of acidic saline into the human masseter muscle does not cause the release of algesic substances.
Animal studies have shown that two repeated intramuscular injections of acidic saline induce mechanical allodynia that lasts for 4 weeks with spread to the contralateral side. In this study, we tested the hypothesis that two repeated intramuscular infusions of acidic saline into the human masseter muscle is associated with pain, mechanical allodynia and release of algesic substances. Eighteen healthy volunteers participated. On day 1, 2.5 mL of acidic saline (pH 3.3) was infused into one of the masseter muscles and isotonic saline (pH 6.0) into the other (randomized and single-blind). Two days later, intramuscular microdialysis was performed to sample serotonin, glutamate, pyruvate, lactate and glucose, during which the saline infusions were repeated. Pain and pressure pain thresholds (PPTs) were recorded before and after infusions on both days. ⋯ Infusion of acidic saline caused low levels of muscle pain, but no mechanical allodynia and no increased release of algesic substances. The value of this model appears modest, but future studies could be performed with larger sample size and higher flow rate before definite conclusions about the validity of the model for craniofacial myalgia can be drawn.
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Randomized Controlled Trial
The impact of intra-operative sufentanil dosing on post-operative pain, hyperalgesia and morphine consumption after cardiac surgery.
There is an ongoing debate whether opioids when used for intra-operative analgesia may enhance post-operative pain. We studied the effect of two different intra-operative dosings of sufentanil on post-operative morphine consumption, pain and hyperalgesia after cardiac anaesthesia. ⋯ Intra-operative dosing of sufentanil significantly influenced post-operative morphine consumption, pain and hyperalgesia. For cardiac anaesthesia in combination with propofol, a sufentanil target concentration of 0.4 ng/mL may be preferable.
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Clin. Exp. Pharmacol. Physiol. · Mar 2013
Randomized Controlled TrialEvaluation of the analgesic efficacy and psychoactive effects of AZD1940, a novel peripherally acting cannabinoid agonist, in human capsaicin-induced pain and hyperalgesia.
The aim of the present study was to investigate the effects of AZD1940, a novel peripherally acting cannabinoid CB(1) /CB(2) receptor agonist, on capsaicin-induced pain and hyperalgesia, as well as on biomarkers of cannabinoid central nervous system (CNS) effects. The present study was a randomized, double-blind, placebo-controlled, four-sequence, two-period, cross-over study in 44 male healthy volunteers aged 20-45 years. The effects of two single oral doses of AZD1940 (400 and 800 μg) were compared with placebo. ⋯ Dose-dependent mild-to-moderate CNS-related and gastrointestinal adverse events were reported following treatment with AZD1940. No evidence of analgesic efficacy was found for a peripherally acting CB(1)/CB(2) receptor agonist in the human capsaicin pain model. The emergence of mild dose-dependent CNS effects suggests that the dose range predicted from preclinical data had been attained.
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Scand J Med Sci Sports · Feb 2013
Randomized Controlled TrialElite swimmers with and without unilateral shoulder pain: mechanical hyperalgesia and active/latent muscle trigger points in neck-shoulder muscles.
Our aim was to investigate the presence of mechanical hypersensitivity and active trigger points (TrPs) in the neck-shoulder muscles in elite swimmers with/without unilateral shoulder pain. Seventeen elite swimmers with shoulder pain; 18 swimmers without shoulder pain; and 15 elite athletes matched controls were recruited. Pressure pain thresholds (PPT) were assessed over the levator scapulae, sternocleidomastoid, upper trapezius, infraspinatus, scalene, subscapularis and tibialis anterior muscles. ⋯ The mean number of TrPs for elite swimmer with and without shoulder pain was, respectively, 4.7 ± 1 (2.1 ± 1.5 active; 2.6 ± 1.4 latent) and 4.7 ± 1.3 (1.3 ± 1.3 active; 3.4 ± 1.5 latent), whereas healthy athletes only showed latent TrPs (2.4 ± 1.2). Elite swimmers with shoulder pain showed higher number of active TrPs than swimmers without pain, whereas it was the opposite for the number of latent muscle TrP (P<0.05). The reported mechanical hypersensitivity suggests that active TrPs play a role in the development of shoulder pain in elite swimmers.