European journal of pain : EJP
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Focusing on pain while completing a pain diary might have detrimental effects on pain intensity. Inverted comfort ratings might be used instead. ⋯ The positive effects of pain diaries on pain trajectories appear to constitute a reliable effect and not a methodological artefact. Pain diaries should be investigated systematically to identify ways to optimize their effects on clinical outcomes. Comfort diaries, however, do not appear to be an efficacious substitute for pain diaries; if the current findings replicate, they indicate that primary care practitioners should continue to use pain diaries in clinical care.
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Experimental models of pain in humans are crucial for understanding pain mechanisms. The most often used muscle pain models involve the injection of algesic substances, such as hypertonic saline solution or nerve growth factor or the induction of delayed onset muscle soreness (DOMS) by an unaccustomed exercise routine. However, these models are either invasive or take substantial time to develop, and the elicited level of pain/soreness is difficult to control. To overcome these shortcomings, we propose to elicit muscle pain by a localized application of short-wave diathermy (SWD). ⋯ This study presents an experimental model to elicit sustained muscle pain based on short-wave diathermy. The main advantages of the model are its noninvasiveness, the possibility to control stimulation parameters in a reliable way and the convenience of the time frame in which pain and hyperalgesia are developed.
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Randomized Controlled Trial
Masseter corticomotor excitability is decreased after intramuscular administration of nerve growth factor.
Quantification of motor-evoked potentials (MEPs) can contribute to better elucidate the central modulation of motor pathways in response to nociceptive inputs. The primary aim of this study was to assess the modulatory effects of nerve growth factor (NGF) injection on masseter corticomotor excitability. ⋯ Intramuscular administration of nerve growth factor into masseter muscle causes inhibitory corticomotor plasticity, which likely occurs to prevent further damage and seems associated with lower pain intensity on function.
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Tapentadol is a centrally acting analgesic with μ-agonistic activity combined with noradrenaline reuptake inhibition. Its mechanism of action relies on improvement of descending pain inhibition. In the current study, tapentadol's ability to enhance conditioned pain modulation (CPM, an experimental measure of descending pain inhibition) was evaluated in fibromyalgia patients with absent or reduced CPM responses. ⋯ In this double-blind randomized placebo-controlled trial, we showed that tapentadol significantly enhanced the descending pain inhibition in fibromyalgia patients. Tapentadol-induced pain relief was only present in patients with a normal CNFS.