European journal of pain : EJP
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Why traumatic injuries to the peripheral nervous system infrequently result in neuropathic pain is still unknown. The aim of this study was to examine the somatosensory system in patients with traumatic peripheral nerve injury with and without pain to try to unravel possible links to mechanisms underlying development and maintenance of pain. Eighteen patients with spontaneous ongoing pain and 16 patients without pain after unilateral partial peripheral traumatic nerve injury were studied. ⋯ There were no side differences in stimulus-response functions using painful heat stimuli in any of the groups. In addition, no significant difference could be demonstrated in any sensory modality comparing side-to-side differences between the two groups. In conclusion, increased pain sensitivity to cold and pressure was found on the injured side in pain patients, pointing to hyperexcitability in the pain system, a finding not verified by a more challenging analysis of side-to-side differences between patients with and without pain.
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The novel analgesic tapentadol combines mu-opioid receptor agonism and noradrenaline reuptake inhibition in a single molecule and shows potent analgesia in various rodent models of pain. We analyzed the contribution of opioid and monoaminergic mechanisms to the activity of tapentadol in rat models of nociceptive and neuropathic pain. Antinociceptive efficacy was inferred from tail withdrawal latencies of experimentally naive rats using a tail flick test. ⋯ Ritanserin did not affect antinociceptive or antihypersensitive ED(50) values of tapentadol. Activation of both mu-opioid receptors and alpha2-adrenoceptors contribute to the analgesic effects of tapentadol. The relative contribution is, however, dependent on the particular pain indication, as mu-opioid receptor agonism predominantly mediates tapentadol's antinociceptive effects, whereas noradrenaline reuptake inhibition predominantly mediates its antihypersensitive effects.
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Previous evaluations of the 20-item Neck Pain and Disability Scale (NPAD) were indicative of excessive redundancy of the measure. The aim of this study was to develop a shortened version of the NPAD (sf-NPAD) based on results of item-to-total-score correlations and factor analysis as published by the developers of the original NPAD. Two items with the highest item-to-total score correlation were selected per factor subscale with the exception of one factor consisting of only one item. ⋯ The sf-NPAD scores of patient subgroups were significantly different showing good discriminative validity. In conclusion, the sf-NPAD demonstrated good validity and internal consistency in this general practice setting. The abbreviated version may facilitate applicability of the scale in clinical and research settings.
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Two studies are reported that tested the fear-avoidance (FA) model using path analytic techniques. In study 1, 429 employees with back pain at baseline and back pain at 18 months follow-up completed questionnaires assessing sociodemographic information, pain severity, negative affect, pain-related fear, and disability. Results indicated that pain severity at baseline predicted pain-related fear and disability at follow-up, and that pain-related fear is rather a consequence than an antecedent of pain severity. ⋯ A similar model as in study 1 was tested. Overall, results are in line with those of study 1. Results are discussed in terms of theoretical relevance and clinical implications.