Pain
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Review Meta Analysis
Cognitive and affective reassurance and patient outcomes in primary care: A systematic review.
In the context of uncertainty about aetiology and prognosis, good clinical practice commonly recommends both affective (creating rapport, showing empathy) and cognitive reassurance (providing explanations and education) to increase self-management in groups with nonspecific pain conditions. The specific impact of each of these components in reference to patients' outcomes has not been studied. This review aimed to systematically evaluate the evidence from prospective cohorts in primary care that measured patient-practitioner interactions with reference to patient outcomes. ⋯ Cognitive reassurance was associated with higher satisfaction and enablement and reduced concerns directly after the consultations in 8 studies; with improvement in symptoms at follow-up in 7 studies; and with reduced health care utilization in 3 studies. Despite limitations, there is support for the notion that cognitive reassurance is more beneficial than affective reassurance. We present a tentative model based on these findings and propose priorities for future research.
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Nerve growth factor (NGF) is involved in the long-term sensitization of nociceptive processing linked to chronic pain. Functional and structural ("sprouting") changes can contribute. Thus, humans report long-lasting hyperalgesia to mechanical and electrical stimulation after intradermal NGF injection and NGF-induced sprouting has been reported to underlie cancer bone pain and visceral pain. ⋯ At the structural level, however, IENF density was not increased by NGF. In conclusion, intradermal NGF induces long-lasting axonal and mechanical sensitization in porcine C nociceptors that corresponds to hyperalgesia observed in humans. Sensitization is not accompanied by increased IENF density, suggesting that NGF-induced hyperalgesia might not depend on changes in nerve fiber density but could be linked to the recruitment of previously silent nociceptors.
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Pain is a ubiquitous yet highly variable experience. The psychophysiological and genetic factors responsible for this variability remain unresolved. We hypothesised the existence of distinct human pain clusters (PCs) composed of distinct psychophysiological and genetic profiles coupled with differences in the perception and the brain processing of pain. ⋯ Brain activity differed (P ≤ 0.001); greater activity occurred in the left frontal cortex in PC1, whereas PC2 showed greater activity in the right medial/frontal cortex and right anterior insula. In health, 2 distinct reproducible PCs exist in humans. In the future, PC characterization may help to identify subjects at risk for developing chronic pain and may reduce variability in brain imaging studies.
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Randomized Controlled Trial
Targeted alteration of dietary n-3 and n-6 fatty acids for the treatment of chronic headaches: A randomized trial.
Omega-3 and n-6 fatty acids are biosynthetic precursors to lipid mediators with antinociceptive and pronociceptive properties. We conducted a randomized, single-blinded, parallel-group clinical trial to assess clinical and biochemical effects of targeted alteration in dietary n-3 and n-6 fatty acids for treatment of chronic headaches. After a 4-week preintervention phase, ambulatory patients with chronic daily headache undergoing usual care were randomized to 1 of 2 intensive, food-based 12-week dietary interventions: a high n-3 plus low n-6 (H3-L6) intervention, or a low n-6 (L6) intervention. ⋯ In intention-to-treat analysis, the H3-L6 intervention produced significantly greater improvement in the HIT-6 score (-7.5 vs -2.1; P<0.001) and the number of Headache Days per month (-8.8 vs -4.0; P=0.02), compared to the L6 group. The H3-L6 intervention also produced significantly greater reductions in Headache Hours per day (-4.6 vs -1.2; P=0.01) and the n-6 in HUFA score (-21.0 vs -4.0%; P<0.001), and greater increases in antinociceptive n-3 pathway markers 18-hydroxy-eicosapentaenoic acid (+118.4 vs +61.1%; P<0.001) and 17-hydroxy-docosahexaenoic acid (+170.2 vs +27.2; P<0.001). A dietary intervention increasing n-3 and reducing n-6 fatty acids reduced headache pain, altered antinociceptive lipid mediators, and improved quality-of-life in this population.