European journal of pain : EJP
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It was previously shown that morphine more potently reduces the affective as compared to the sensory component of nociception, and this effect is independent of morphine's rewarding properties. Here we investigated whether this finding can be generalized to other classes of anti-nociceptive drugs. The effect of oxycodone (0-10 mg/kg, i.p.), tramadol (0-10 mg/kg, i.p.), ibuprofen (0-300 mg/kg, i.p.) and pregabalin (0-31.6 mg/kg, i.p.) on negative affect and mechanical hypersensitivity accompanying carrageenan-induced (0.5% intraplantar) inflammatory nociception was assessed using conditioned place aversion (CPA) and Randall Selitto paw pressure test, respectively. ⋯ Ibuprofen and pregabalin also showed a dissociation of anti-aversive and anti-nociceptive potency, but less pronounced (i.e. three times more potent against the affective component). However, pregabalin showed no dissociation between rewarding potency under normal versus painful conditions. Taken together, these data suggest that the dissociation of rewarding potency in animals under normal versus painful conditions is limited to drugs with an opioid mechanism of action, while the dissociation of anti-aversive and anti-nociceptive potency applies to anti-nociceptive drugs with different mechanisms of action.
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Multicenter Study
Validation of an acute pain-behavior scale for older persons with inability to communicate verbally: Algoplus.
To compensate for poor acute pain detection in elderly inpatients with inability to communicate verbally (ICV), the Doloplus Collective team devised the 5-item Algoplus behavior-assessment scale specifically aimed at quickly detecting acute pain in these individuals. Algoplus was developed in three successive phases, including expert opinions, caregivers interviews, patient video recordings and statistical procedures. Among the 1500 recorded primary pain behaviors, 48 were selected and clustered into a 5-item scale. ⋯ Excellent correlations were observed between Algoplus and experts' clinical judgment, acute pain clinical situations or each comparator self-rating-pain score. For patients with acute pain conditions, a score ⩾2 out of 5 on the Algoplus scale was retained as the threshold for the presence of acute pain in elderly ICV inpatients, with 87% sensitivity and 80% specificity. In addition, the very brief rating time of ∼1min is particularly relevant in acute-care settings, where repetitive pain-monitoring is required.
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Neuropathic pain following peripheral nerve lesion is highly resistant to conventional pain treatments but may respond well to direct electrical peripheral nerve stimulation (PNS). In the 1980s, we treated a series of 11 peripheral neuropathic pain patients with PNS. A first outcome assessment, conducted after a 52-month follow-up, revealed that the majority of the patients were significantly improved. ⋯ PNS led to increased blood flow not only in primary somatosensory cortex, but also in anterior cingulate and insular cortices, suggesting that besides activation of the dorsal column lemniscal system, other mechanisms may play a role in its analgesic effects. These data show that PNS can provide truly long-term pain relief in carefully selected patients and they provide some objective quantitative data in support of this. They encourage the planning of future prospective studies in a larger cohort of patients.
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Tonic pain in one body segment can inhibit the perception of pain in another body segment. This phenomenon is mediated by diffuse noxious inhibitory controls (DNIC), and its efficacy in craniofacial regions is investigated in this study. A compressive device that evoked a tonic, moderate/severe, headache-like, conditioning pain (∼8/10 on a visual analogue scale) was applied for 15min. ⋯ PPTol was unchanged. In the period after the painful conditioning stimulation PPT was depressed compared to control. This study shows that pain evoked from the craniofacial region evokes DNIC-like mechanisms on segmental as well as heterosegmental sites.
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The objective was to investigate the 3-year course of secondary chronic headaches (⩾15days per month for at least 3months) in the general population. An age and gender stratified random sample of 30,000 persons aged 30-44years from the general population received a mailed questionnaire. All with self-reported chronic headache, 517 in total, were interviewed by neurological residents. ⋯ The headache index (frequency×intensity×duration) was significantly reduced from baseline to follow-up in chronic posttraumatic headache and HACRS, but not in CEH. We conclude that secondary chronic headaches seem to have various course dependent of subtype. Recognizing the different types of secondary chronic headaches is of importance because it might have management implications.