The journal of pain : official journal of the American Pain Society
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Randomized Controlled Trial
The Influence of Placebo Analgesia Manipulations on Pain Report, the Nociceptive Flexion Reflex, and Autonomic Responses to Pain.
Expectations for pain relief and experience/conditioning are psychological factors that contribute to placebo analgesia, yet few studies have studied the physiological mechanisms underlying their effects. This study randomized 133 participants to 4 groups: an expectation only (E-only) group, a conditioning only (C-only) group, an expectation plus conditioning (E+C) group, and a natural history (NH) control group. Painful electric stimulations were delivered before and after an inert cream was applied to the site of stimulation. ⋯ PERSPECTIVE: This study assessed whether placebo analgesia manipulations that include expectations, conditioning, or both modulate the NFR (measure of spinal nociception). Only the manipulation that involved expectations and conditioning inhibited pain, but both expectation manipulations facilitated NFR. This suggests a complex modulation of spinal neurons by placebo manipulations.
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Randomized Controlled Trial Multicenter Study
The Relationship of Endocannabinoidome Lipid Mediators With Pain and Psychological Stress in Women With Fibromyalgia: A Case-Control Study.
Characterized by chronic widespread pain, generalized hyperalgesia, and psychological stress, fibromyalgia (FM) is difficult to diagnose and lacks effective treatments. Endocannabinoids-arachidonoylethanolamide (AEA), 2-arachidonoylglycerol (2-AG), and the related oleoylethanolamide (OEA), palmitoylethanolamide (PEA), and stearoylethanolamide (SEA)-are endogenous lipid mediators with analgesic and anti-inflammatory characteristics, in company with psychological modulating properties (eg, stress and anxiety), and are included in a new emerging "ome," the endocannabinoidome. This case-control study compared the concentration differences of AEA, OEA, PEA, SEA, and 2-AG in 104 women with FM and 116 healthy control subjects. ⋯ Thus plasma lipids alone are not good biomarkers for FM. PERSPECTIVE: This study reports about elevated plasma levels of endocannabinoidome lipid mediators in FM. The lipids' suitability to work as biomarkers for FM in the clinic were low; however, their altered levels indicate that a metabolic asymmetry is ongoing in FM, which could serve as a baseline during explorative FM pain management.
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Heightened anticipation and fear of movement-related pain has been linked to detrimental fear-avoidance behavior in chronic low back pain (cLBP). Spinal manipulative therapy (SMT) has been proposed to work partly by exposing patients to nonharmful but forceful mobilization of the painful joint, thereby disrupting the relationship among pain anticipation, fear, and movement. Here, we investigated the brain processes underpinning pain anticipation and fear of movement in cLBP, and their modulation by SMT, using functional magnetic resonance imaging. ⋯ This study sheds light on the brain processing of anticipated pain and fear of back-straining movement in cLBP, and suggests that SMT may reduce cognitive and affective-motivational aspects of fear-avoidance behavior, along with corresponding brain processes. PERSPECTIVE: This study of cLBP patients investigated how SMT affects clinical pain, expected pain, and fear of physical exercises. The results indicate that one of the mechanisms of SMT may be to reduce pain expectancy, fear of movement, and associated brain responses.
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Randomized Controlled Trial
Exploring the Role of Negative Cognitions in the Relationship Between Ethnicity, Sleep, and Pain in Women With Temporomandibular Joint Disorder.
Negative cognitions are central to the perpetuation of chronic pain and sleep disturbances. Patients with temporomandibular joint disorder (TMJD), a chronic pain condition characterized by pain and limitation in the jaw area, have a high comorbidity of sleep disturbances that possibly exacerbate their condition. Ethnic group differences are documented in pain, sleep, and coping, yet the mechanisms driving these differences are still unclear, especially in clinical pain populations. ⋯ These findings identify pain catastrophizing as a potentially important link between ethnicity and clinical pain and suggest that interventions targeting pain-related helplessness could improve both sleep and pain, especially for African American patients. Perspective:Pain-related helplessness and insomnia severity contribute to ethnic differences found in clinical pain among woman with TMJD. Findings can potentially inform interventions that target insomnia and catastrophizing to assist in reducing ethnic disparities in clinical pain.
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Observational Study
Parent Responses to Child Pain During Intensive Interdisciplinary Pain Treatment and 1-Year Follow-Up.
Targeting parents' responses to their child's pain during intensive interdisciplinary pain treatment (IIPT) could influence child functioning. This longitudinal, observational study investigated changes in these responses and concurrent relationships between parent responses and changes in levels of child functioning and pain. Parents of youths 10 to 19 years of age (mean = 15 years, SD = 1.98 years) participated in twice weekly, parent-only groups while their teens were enrolled in IIPT (mean length of treatment = 3.93 weeks, SD = 1.16 weeks). ⋯ PERSPECTIVE: During intensive IIPT, parents made statistically significant changes in responses to their child's pain, which was associated with improvements in child disability, but not child pain. Changes were sustained through 1-year follow-up. Targeting parental responses to child pain is feasible and may relate to improved child functioning.