European journal of pain : EJP
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Clinical Trial
Multi-modal induction and assessment of allodynia and hyperalgesia in the human oesophagus.
Experimental pain models based on single stimuli have to some degree limited visceral pain studies in humans. Hence, the aim of this study was to investigate the effect of multi-modal visceral pain stimuli of the oesophagus in healthy subjects before and after induction of visceral hyperalgesia. We used a multi-modal psychophysical assessment regime and a neurophysiological method (nociceptive reflex) for the characterisation of the experimentally induced hyperalgesia. ⋯ Visceral hyperalgesia/allodynia can be induced experimentally and assessed quantitatively by the newly introduced multi-modal psychophysical assessment approach. The significant changes of the experimentally evoked referred pain patterns and of the nociceptive reflex evoked from a distant somatic structure indicate that even short-lasting visceral hyperalgesia can generate generalised sensitisation.
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We investigated the literature of randomised placebo-controlled trials to find out if transcutaneous electrical nerve stimulation (TENS) or acupuncture-like transcutaneous electrical nerve stimulation (ALTENS) can reduce analgesic consumption after surgery. ⋯ TENS, administered with a strong, subnoxious intensity at an adequate frequency in the wound area, can significantly reduce analgesic consumption for postoperative pain.
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Randomized Controlled Trial Clinical Trial
Suppression of motor evoked potentials in a hand muscle following prolonged painful stimulation.
Earlier investigations have shown that stimulation of peripheral afferent nerves induces prolonged changes in the excitability of the human motor cortex. The present study compared the effect of experimental pain and non-painful conditioning stimulation on motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) in the relaxed first dorsal interosseous (FDI) and flexor carpi ulnaris (FCU) muscles. The MEPs were measured in 10 healthy subjects, and stimulus-response curves were generated before and after each of four stimulation paradigms conducted in random order on separate occasions: (a) control; (b) "dual stimulation" consisting of electrical stimulation of the FDI motor point paired with TMS; (c) painful infusion of hypertonic saline in the FDI muscle; and (d) pain combined with dual stimulation. ⋯ In two additional subjects, the responses evoked in FDI by direct stimulation of the descending corticospinal tracts were significantly depressed following painful stimulation of the FDI, although the ulnar-evoked M-waves remained constant. It is concluded that muscle pain is followed by a period with profound depression of MEPs amplitudes in the resting muscle, but that these changes are at least in part due to a lasting depression of the excitability of the motoneurones in the spinal cord. Hence, painful stimulation differs from non-painful, repetitive stimulation, which facilitates the corticomotor pathway.
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Comparative Study Clinical Trial Controlled Clinical Trial
Hypoalgesia to pressure pain in referred pain areas triggered by spatial summation of experimental muscle pain from unilateral or bilateral trapezius muscles.
Animal and human experimental studies have suggested the importance of spatial summation in the nociception processing and in the activation of descending inhibition. However, the relationship between the areas (size) of muscles stimulated and the recruitment of descending inhibition has not been addressed. Consequently, we tested whether bilateral versus unilateral injection of hypertonic saline into trapezius muscles caused hypoalgesia to pressure pain (pressure pain thresholds, PPTs) in the local pain areas (the trapezius muscles) and the referred pain areas (the posterolateral neck muscles). ⋯ In the referred pain areas, the PPTs 7.5 and 15 min after the second injection were significantly increased compared with the first injection, while no changes in the PPT were observed in local and referred pain areas after unilateral injection. This suggests that the induction of descending inhibition was triggered by spatial summation during the later phase of experimentally induced muscle pain. The present experimental model might be used for further investigation of descending inhibition related to the spatial characteristics of nociceptive stimuli in humans.
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For years enhancement of a patient's level of physical fitness has been an important goal in rehabilitation treatment in chronic low back pain (CLBP), based on the hypothesis that physical deconditioning contributes to the chronicity of low back pain. However, whether this hypothesis in CLBP holds is not clear. In this paper, possible mechanisms that contribute to the development of physical deconditioning in CLBP, such as avoidance behaviour and suppressive behaviour, are discussed. ⋯ The level of physical fitness of CLBP patients also appeared to be lower or comparable to the fitness level of healthy persons. A discriminating factor between fit and unfit patients with back pain may be the fact that fit persons more frequently are still employed, and as such may be involved more in physical activity. Lastly some suggestions are made for further research in the field of disuse and deconditioning in CLBP.