European journal of pain : EJP
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Experimental animal pain models involving peripheral nerve lesions have expanded the understanding of the pathological changes caused by nerve damage. However models for the pathogenesis of chronic pain patients lacking obvious nerve injuries have not been developed to the same extent. Guided by clinical observations, we focused on the initiating noxious event, the context when applying nociceptive stimulation targeting long-lasting pain elicited by muscle insult. ⋯ However, increasing the dose of LPS (20 μg/kg) before applying HS5 eliminated the development of mechanical hypersensitivity in the chronic phase, while the hypersensitivity in the acute phase was significantly more severe than with low-dose LPS-pretreatment. In this model, the development of hypersensitivity could be modulated by manipulating LPS-doses prior to noxious stimulation. This novel chronic pain model based on a preceding 'priming' myalgic stimulus provides an intriguing means for studying the pathogenesis of chronic pain.
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Randomized Controlled Trial
The anticonvulsant levetiracetam for the treatment of pain in polyneuropathy: a randomized, placebo-controlled, cross-over trial.
Levetiracetam is an anticonvulsant which is assumed to act by modulating neurotransmitter release via binding to the vesicle protein SV2A. This could have an impact on signaling in the nociceptive system, and a pilot study indicated relief of neuropathic pain with levetiracetam. ⋯ This study indicates that the anticonvulsant levetiracetam has no clinically relevant effect on painful polyneuropathy.
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Randomized Controlled Trial
Self-reported sleep duration associated with distraction analgesia, hyperemia, and secondary hyperalgesia in the heat-capsaicin nociceptive model.
Although sleep deprivation is known to heighten pain sensitivity, the mechanisms by which sleep modifies nociception are largely unknown. Few studies of sleep-pain interactions have utilized quantitative sensory testing models that implicate specific underlying physiologic mechanisms. One possibility, which is beginning to receive attention, is that differences in sleep may alter the analgesic effects of distraction. ⋯ Individuals who slept less than 6.5 h/night in the month prior to the study experienced significantly less behavioral analgesia, increased skin flare and augmented secondary hyperalgesia. These findings suggest that reduced sleep time is associated with diminished analgesic benefits from distraction and/or individuals obtaining less sleep have a reduced ability to disengage from pain-related sensations. The secondary hyperalgesia finding may implicate central involvement, whereas enhanced skin flare response suggests that sleep duration may also impact peripheral inflammatory mechanisms.
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The current study interviewed patients with chronic pain to: (1) identify the most common words used by patients in the samples to describe the "quality" of their pain (i.e. sharp, dull) and (2) evaluate the validity of existing pain quality measures. Two-hundred and thirteen individuals with pain associated with spinal cord injury (SCI) or multiple sclerosis (MS) were asked to describe their pain. Consistent with previous research that has shown that patients with different types of pain problems describe their pain using different pain quality descriptors, there was variability in the frequency of pain descriptors used by the study participants. ⋯ Regarding the validity of existing pain measures, only one pain quality measure assessed all 14 of the most common pain descriptors volunteered by the sample. Also, although a number of pain quality measures have been developed to discriminate neuropathic from nociceptive pain, there was surprisingly little overlap in descriptors between these measures. The results of the current study and other studies using similar procedures would be useful for evaluating and developing existing and future pain quality measures.
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The demand-control-support "job strain" model is frequently used in occupational health research. We sought to explore the relationship between job strain and back pain. ⋯ Our results support the findings linking back pain to job strain. Moreover, the relationship between back pain and job strain is much stronger if job strain includes both psychological and physical demands. Results of this study suggest that workplace interventions that aim to reduce job strain may help prevent back pain and may alleviate the personal, social, and economic burden attributable to back pain.