Articles: hyperalgesia.
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Pharmacological reviews · Jul 2012
ReviewHuman experimental pain models for assessing the therapeutic efficacy of analgesic drugs.
Pain models in animals have shown low predictivity for analgesic efficacy in humans, and clinical studies are often very confounded, blurring the evaluation. Human experimental pain models may therefore help to evaluate mechanisms and effect of analgesics and bridge findings from basic studies to the clinic. The present review outlines the concept and limitations of human experimental pain models and addresses analgesic efficacy in healthy volunteers and patients. ⋯ Assessment with neurophysiologic methods and imaging is valuable as a supplement to psychophysical methods and can increase sensitivity. The models need to be designed with careful consideration of pharmacological mechanisms and pharmacokinetics of analgesics. Knowledge obtained from this review can help design experimental pain studies for new compounds entering phase I and II clinical trials.
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Arch Orthop Trauma Surg · Jul 2012
Case ReportsKlippel-Trenaunay syndrome: a rare cause of disabling pain after a femoral fracture.
Klippel-Trenaunay syndrome (KTS) is characterized by a cutaneous vascular nevus of the involved extremity, as well as bone and soft tissue hypertrophy of the extremity and venous malformations. We present the case of a 52-year-old man with a femoral fracture and a history of haemangiomas, limb bone hypertrophy and varicosity. ⋯ According to our knowledge, this is the second case of KTS managed for femoral fracture. Unlike the previous report in literature, in this case a severe disabling neuropathic pain complicated the clinical management.
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Lidocaine is clinically widely used as a local anesthetic inhibiting propagation of action potentials in peripheral nerve fibers. Correspondingly, the functional magnetic resonance imaging (fMRI) response in mouse brain to peripheral noxious input is largely suppressed by local lidocaine administered at doses used in a clinical setting. We observed, however, that local administration of lidocaine at doses 100 × lower than that used clinically led to a significantly increased sensitivity of mice to noxious forepaw stimulation as revealed by fMRI. ⋯ Additional experiments with nociceptor-specific CB(1) receptor knockout mice indicated an involvement of the CB(1) receptors located on the nociceptors. We conclude that low concentrations of lidocaine leads to a sensitization of the nociceptors through a CB(1) receptor-dependent process. This lidocaine-induced sensitization might contribute to postoperative hyperalgesia.
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Neurogastroenterol. Motil. · Jul 2012
Randomized Controlled TrialThe autonomic response to human esophageal acidification and the development of hyperalgesia.
Distal esophageal acidification induces variable hyperalgesia in the non-acid exposed proximal esophagus. As the autonomic nervous system (ANS) modulates nociception, the aim was to determine whether autonomic reactivity to acid infusion predicted inter-individual differences in hyperalgesia. ⋯ Acid-induced esophageal hyperalgesia correlated with reduced parasympathetic tone, suggesting that the parasympathetic nervous system may have anti hyperalgesic properties. Additional studies on the autonomic modulation of esophageal hyperalgesia are required.