European journal of pain : EJP
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Concerning chronic low back pain (CLBP), different cognitive-behavioral models have hypothesized that coping strategies play a role in the chronification of pain by changes in physical activity. Strategies such as avoidance - or persistent coping may be related to changes in (lumbar) muscle activity. ⋯ In CLBP, a maladaptive coping strategy like "catastrophizing" is related to increased lumbar muscle activity, and an adaptive strategy like "distraction" to increased lumbar muscle relaxation during walking.
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Patients with neuropathy, report changes in sensory perception, particularly mechanical and thermal allodynia, and spontaneous pain. Similar sensory changes are seen in experimental neuropathies, in which alteration in primary afferent properties can also be determined. The neural correlate of spontaneous pain is ongoing activity in sensory afferents. ⋯ The afferent barrage associated with mechano-cooling-sensitive afferents was increased 26-fold 7 days after nerve injury. We observed no differences in the properties of intact A fibre mechanosensitive afferents. These studies demonstrate for the first time that the altered nociception seen after PSNI is associated with ongoing activity and enhanced cooling-evoked activity in intact C fibre afferents in the saphenous nerve, with no concurrent alteration in A fibre afferents.
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Randomized Controlled Trial
Clarithromycin, a potent inhibitor of CYP3A, greatly increases exposure to oral S-ketamine.
Oral ketamine is used as an adjuvant in the treatment of refractory neuropathic and cancer-related pain. Drug interactions may alter the analgesic or other effects of ketamine. ⋯ Clarithromycin strongly increases plasma concentrations of oral S-ketamine probably by inhibiting its CYP3A-mediated N-demethylation. This increase is reflected as modest changes in behavioral effects of oral S-ketamine.
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Patients with chronic pain are not only faced with disabilities but are also challenged to maintain a valued sense of self. This sense of self is in part determined by the extent to which patients can accomplish their identity-related goals. The present study explores the content of three domains of the self, namely the ideal, ought and feared self and examines how the content relates to disability and depression. ⋯ None of the other goal-domains was related to disability or depression. The present study provides additional insight into the goals of patients with chronic pain at the level of identity and has shown that these are, at least in part, related to the level of functional disability. These results might be useful for future studies incorporating the role of identity in chronic pain, such as psychological interventions.
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Electrical low-frequency stimulation (LFS) of cutaneous afferents reliably induces long-term depression (LTD) of nociception and pain in man. In this study LFS effects on cerebral activation were investigated by functional magnetic resonance imaging (fMRI). In 17 healthy volunteers, nociceptive fibers of right hand dorsum were electrically stimulated via a concentric electrode. ⋯ The study revealed LTD of pain-related cerebral activation, involving sensory, affective, cognitive, and attentional processes. Positive correlation between pain relief and increased brain activation after LFS may indicate involvement of endogenous pain control mechanisms in LTD. These experiments may help to judge the potency of LTD for future chronic pain treatment.