Pain
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The aim of this study was to investigate the relationship between psychosocial work characteristics and neck and upper limb symptoms and to examine to what extent this relationship could be explained by other risk factors. Data were used from a prospective cohort study in a working population, with a follow-up period of 3 years. ⋯ Partly, but not exclusively, these relationships were intermediated by an increased exposure to physical risk factors and increased stress symptoms. Personal characteristics did not considerably influence the main effects of the identified risk factors.
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Electrical tooth stimulation was used to investigate whether humans develop tolerance to nitrous oxide (N(2)O) analgesia within a single administration as well as over repeated administrations. In a double-blind cross-over experiment, 77 subjects received a 40-min administration of 38% N(2)O at one session and placebo gas at the other. The sessions were separated by 1 week and the order of gas administration was counterbalanced. ⋯ For both detection and pain threshold measures, acute tolerance developed during the initial N(2)O exposure and chronic tolerance developed over repeated administrations. Although chronic tolerance developed, a test for Pavlovian drug conditioning found no evidence of conditioned effects on sensory thresholds. In conclusion, acute and chronic tolerance develop to N(2)O's analgesic effects in humans.
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Activation of extracellular signal-regulated kinase (ERK), a mitogen activated-protein kinase (MAPK), in dorsal horn neurons contributes to inflammatory pain by transcription-dependent and -independent means. We have now investigated if ERK is activated in the spinal cord after a spinal nerve ligation (SNL) and if this contributes to the neuropathic pain-like behavior generated in this model. An L5 SNL induces an immediate (<10 min) but transient (<6 h) induction of phosphoERK (pERK) restricted to neurons in the superficial dorsal horn. ⋯ Intrathecal injection of the MEK (ERK kinase) inhibitor PD98059 on Day 2, 10 or 21 reduces SNL-induced mechanical allodynia. Our results suggest that ERK activation in the dorsal horn, as well as in the DRG, mediates pain through different mechanisms operating in different cells at different times. The sequential activation of ERK in dorsal horn microglia and then in astrocytes might reflect distinct roles for these two subtypes of glia in the temporal evolution of neuropathic pain.
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Effective verbalization of pain requires progressive cognitive development and acquisition of social communication skills. Use of self-report in pediatric pain assessment assumes children have acquired a capacity to understand and use common words to describe pain. The current investigation documented the language most commonly used by young children to describe pain and the age of onset of use of these words. ⋯ The word-stem 'pain' was used relatively infrequently and gradually emerged in children's vocabularies. The findings indicate that young children rely on a select number of words to describe pain, with these words appearing in children's vocabularies at an early age. These results have implications for developmentally appropriate pain assessment in young children.