European journal of pain : EJP
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In the scientific approach to central processing of pain, the habituation phenomenon has been frequently described. Recent studies mentioned electrophysiological habituation during the recording of laser-evoked potentials (LEP). In this study we intended to test whether habituation can be reproducibly induced by repetitive painful laser stimuli and simultaneously measured with LEP. Inspired by findings from previous imaging studies that showed bilateral activation of the operculo-insular cortices, we hypothesized that repetitive painful laser stimuli applied to one hand lead to bihemispheral LEP amplitude habituation. ⋯ Habituation (in the electrophysiological sense) is a physiological phenomenon that indicates normal central processing of pain in healthy controls. We showed bihemispheral N2P2 amplitude habituation after repetitive painful stimulation of the right hand. Our findings propose a bihemishperal contribution to central pain processing and pain modulation when electrophysiological habituation occurs.
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Chronic pain is associated with generalized hypersensitivity and impaired endogenous pain modulation (conditioned pain modulation; CPM). Despite extensive research, their prevalence in chronic pain patients is unknown. This study investigated the prevalence and potential determinants of widespread central hypersensitivity and described the distribution of CPM in chronic pain patients. ⋯ Although prevalent in chronic pain, generalized central hypersensitivity is not present in every patient. An individual assessment is therefore required in order to detect altered pain processing. The broad basic knowledge about central hypersensitivity now needs to be translated into concrete clinical consequences, so that patients can be offered an individually tailored mechanism-based treatment.
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Observer-rated pain assessment instruments for people with dementia have proliferated in recent years and are mainly effective in identifying the presence of pain. The objective of this study was to determine whether these tools can also be used to evaluate intensity of pain. ⋯ The use of the Abbey Pain Scale, PAINAD or NOPPAIN improves both the recognition of pain presence/absence as well as rating pain severity in older people with impaired cognition.
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Electroacupuncture (EA) has been widely accepted and applied as an important acupuncture-related technique for acupuncture analgesia (AA) research. The involvement of opioid peptides and receptors in acute AA has been shown via pre-EA application of opioid receptor/peptide antagonists. In this study, we intended to reproducibly institute acupoint position and needling excluding influences from anaesthesia or restrainers on rats with complete Freund's adjuvant (CFA) hind paw inflammatory pain, as well as to explore opioid-dependency and anti-inflammatory effects in sustained acupuncture analgesia. ⋯ By employing a reproducible EA treatment model on GB30 in free-moving rats, we demonstrated the involvement of peripheral opioid receptors mediated EA-induced long-term antinociception. Future studies should examine the specific neuroimmunological connection of EA-induced sustained antinociception in inflammation.
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Two transient receptor potential (TRP) channels, TRPV1 and TRPA1, have been physiologically studied with regard to noxious heat transduction. Evidence argues against these channels as sole transducers of noxious heat or cold, respectively. Moreover, in submammalian species the TRPA1 orthologue shows heat sensitivity. ⋯ Our results indicate that in addition to TRPV1, TRPA1 plays a role in heat nociception, in particular in definition of the heat threshold, and might therefore serve as a therapeutic target in acute inflammatory pain.