Pain
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Previously, we demonstrated, in a randomized clinical trial, the effectiveness of a psychoeducational intervention to decrease pain intensity scores and increase patients' knowledge of cancer pain management with a sample of oncology patients with pain from bone metastasis. In the present study, we evaluated for changes in mood states (measured using the Profile of Mood States), quality of life (QOL; measured using the Medical Outcomes Study Short Form-36 (SF-36)), and pain's level of interference with function (measured using the Brief Pain Inventory (BPI)) from baseline to the end of the intervention first between the intervention and the standard care groups and then within the intervention group based on the patients' level of response to the intervention (i.e., patients were classified as non-responders, partial responders, or responders). ⋯ Differences in the physical and mental component summary scores on the SF-36 and the interference items on the BPI, among the three respondent groups, were not only statistically significant but also clinically significant. The use of responder analysis in analgesic trials may help to identify unique subgroups of patients and lead to the development of more effective psychoeducational interventions.
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Nociceptive mechanisms in tension-type headache are poorly understood. The aim was to investigate the pain sensitivity of pericranial muscles and a limb muscle in patients with tension-type headache. Experimental muscle pain was induced by standardized infusions of 0.5 ml of 1 M hypertonic saline into two craniofacial muscles (anterior temporalis (TPA) and masseter (MAS)) and a limb muscle (anterior tibial (TA)) in 24 frequent episodic tension-type headache patients (FETTH), 22 chronic tension-type headache patients (CTTH) and 26 age and gender matched healthy subjects. ⋯ There was no difference in pain sensitivity between FETTH and CTTH or between patients with or without headache. In conclusion, the present study demonstrates the presence of generalized pain hypersensitivity both in FETTH and CTTH compared to controls which is unrelated to actual headache status and extends to include responses to longer-lasting stimuli which are clinically highly relevant. Gender differences in deep pain sensitivity seem to be a consistent finding both in healthy controls and patients with tension-type headache.
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Clinical Trial
Ethnic identity predicts experimental pain sensitivity in African Americans and Hispanics.
The aim of this study was to examine experimental pain sensitivity in three ethnic groups, African Americans, Hispanic Americans and non-Hispanic White Americans, and to determine whether ethnic identity is differentially associated with pain sensitivity across ethnic groups. Participants included sixty-three African American, sixty-one Hispanic and eighty-two non-Hispanic white participants who were assessed using three experimental pain measures: thermal, cold-pressor and ischemic. Participants' ethnic identity was assessed using the Multi-group Ethnic Identity Measure (MEIM). ⋯ Statistically controlling for ethnic identity rendered some of the group differences in pain range non-significant. These findings indicate that ethnic identity is associated with pain sensitivity in ethnic minority groups, and may partially mediate group differences in pain perception. The results of the present investigation provide evidence of ethnic group differences in responses to experimental pain across multiple noxious stimuli, with both minority groups exhibiting greater sensitivity to laboratory evoked pain compared to non-Hispanic White Americans.
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Comparative Study
ASIC3 in muscle mediates mechanical, but not heat, hyperalgesia associated with muscle inflammation.
Peripheral initiators of muscle pain are virtually unknown, but likely key to development of chronic pain after muscle insult. The current study tested the hypothesis that ASIC3 in muscle is necessary for development of cutaneous mechanical, but not heat, hyperalgesia induced by muscle inflammation. Using mechanical and heat stimuli, we assessed behavioral responses in ASIC3-/- and ASIC3+/+ mice after induction of carrageenan muscle inflammation. ⋯ Injection of ASIC3-encoding virus into muscle or skin of ASIC3-/- mice resulted in ASIC3 mRNA in DRG and protein expression in DRG and the peripheral injection site. Injection of ASIC3-encoding virus into muscle, but not skin, resulted in development of mechanical hyperalgesia similar to that observed in ASIC3+/+ mice. Thus, ASIC3 in primary afferent fibers innervating muscle is critical to development of hyperalgesia that results from muscle insult.
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This study evaluated the contribution of condition-specific helplessness and loss to depression in fibromyalgia (FM). Two models were tested. The first model examined whether loss, measured by the West Haven-Yale Multidimensional Pain Inventory (WHYMPI) Interference Scale, would mediate the relationship between disability and depression. ⋯ In Model 1, loss fully mediated the relationship between disability and depression. In Model 2, condition-specific helplessness mediated the relationship between pain and depression, but the contribution of loss was not significant. The findings confirm the importance of helplessness and demonstrate that the cognitive meaning of having FM plays a more central role in predicting depressive symptomatology than illness-related stressors, such as pain or disability.