European journal of pain : EJP
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The overall aim of this study was to explore the natural course of pain-related fear during the early stage of a new low back pain episode, using a prospective case series design. Specific research questions addressed the existence of typical patterns in individual time series of pain-related fear and sequential relationships between the occurrence of pain-related fear, pain and pain catastrophizing. Forty-four general practice patients who consulted their physician with a new episode of non-specific low back pain were recruited. ⋯ In summary, these results fit in with previous findings in chronic patients. A relevant subgroup of patients who might benefit from early intervention could be identified. These findings support the need for further research into fear mechanisms in acute low back pain.
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The overarching reason that pain patients seek medical attention is because their pain interferes with some or all aspects of their quality of life (QOL). Interventions are considered successful by the patient if QOL is improved. Simple pain scores, although providing important information, do not capture the patient's total pain experience, which includes the effect on QOL. A focus on patient QOL should be adopted by all clinicians treating patients with neuropathic pain to work toward successful outcomes.
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Systemic morphine selectively depresses a thalamic link of widespread nociceptive inputs in the rat.
The lateral part of the ventromedial thalamus (VM l) relays nociceptive inputs from the whole body surface to the dorsolateral frontal cortex. The aim of the present study was to investigate the effects of systemic morphine on nociceptive activity evoked in VM l neurones either by thermal (48 degrees C) or by supramaximal percutaneous electrical stimuli. The noxious thermal evoked responses were depressed by 10.8 +/- 10.1%, 48.3 +/- 23.0% and 67.3 +/- 10.1%, 5 min after i.v. injections of 1.0, 1.73 and 3.0 mg/kg of morphine, respectively. ⋯ The dose of morphine that reduced VM l neuronal nociceptive responses by 50% (1.73 mg/kg) was around 3.5 times lower than that necessary to inhibit the responses of its spinal or medullary relays under similar experimental conditions. These results, added to the data of the literature, suggest that supraspinal effects of morphine are primarily mediated at the thalamic level. It is tempting to speculate that morphine-induced reductions of attentional or psychomotor responses related to pain may be mediated by its action on VM l.
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Clinical Trial Controlled Clinical Trial
Pavlovian conditioning of opioid and nonopioid pain inhibitory mechanisms in humans.
Learning processes such as respondent or Pavlovian conditioning are believed to play an important role in the development of chronic pain, however, their influence on the inhibition of pain has so far not been assessed in humans. The purpose of this study was the demonstration of Pavlovian conditioning of stress-induced analgesia in humans and the determination of its opioid mediation. In a differential classical conditioning paradigm two different auditory stimuli served as conditioned stimuli and mental arithmetic plus white noise as unconditioned stimulus. ⋯ Pain tolerance was affected by naloxone whereas pain threshold was not. The data of this study show that stress analgesia can be conditioned in humans and that it is at least partially mediated by the endogenous opioid system. Learning processes also influence pain inhibitory processes in humans and this effect might play a role in the development of chronic pain.
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The aim of this study was to investigate whether pain itself or pain-related fear is crucial in eliciting attentional bias towards pain-related information in healthy individuals. The results from two successive experiments provide evidence that attentional bias does not take place as a function of pain-related fear or as a function of pain per se. Attentional bias for pain words was neither found to be related to trait variables like anxiety, depression, catastrophising, fear of pain, and pain vigilance. Implications of the results are discussed and directions for future research are provided.