The journal of pain : official journal of the American Pain Society
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The demographic factors of sex, age, and race/ethnicity are well recognized as relevant to pain sensitivity and clinical pain expression. Of these, sex differences have been the most frequently studied, and most of the literature describes greater pain sensitivity for women. The other 2 factors have been less frequently evaluated, and current literature is not definitive. Taking advantage of the large Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study cohort, we evaluated the association of sex, age, and self-reported race with 34 measures of pressure, mechanical, and thermal pain sensitivity encompassing threshold and suprathreshold perception. Women were significantly more pain-sensitive than men for 29 of 34 measures. Age effects were small, and only significant for 7 of 34 measures, however, the age range was limited (18-44 years of age). Race/ethnicity differences varied across groups and pain assessment type. Non-Hispanic white individuals were less pain-sensitive than African-American (for 21 of 34 measures), Hispanic (19 of 34), and Asian (6 of 34) individuals. No pain threshold measure showed significant racial differences, whereas several suprathreshold pain measures did. This suggests that racial differences are not related to tissue characteristics or inherent nociceptor sensitivity. Rather, the differences observed for suprathreshold pain ratings or tolerance are more likely related to differences in central nociceptive processing, including modulation imposed by cognitive, psychological, and/or affective factors. ⋯ The influence of sex, age, and race/ethnicity on various aspects of pain sensitivity, encompassing threshold and suprathreshold measures and multiple stimulus modalities, allows for a more complete evaluation of the relevance of these demographic factors to acute pain perception.
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Although many studies have investigated the overlap between pain phenotypes and chronic fatigue syndrome (CFS) in adults, little is known about the relationship between these conditions in adolescents. The study's aim was therefore to identify whether a relationship exists between chronic widespread pain (CWP) and CFS in adolescents and investigate whether the two share common associations with a set of covariates. A questionnaire was administered to offspring of the Avon Longitudinal Study of Parents and Children (ALSPAC) at age 17, asking about site, duration, and pain intensity, from which participants with CWP were identified. ⋯ Female adolescents were approximately twice as likely to have CFS or CWP, with multinomial regression revealing a greater sex effect for CWP compared with CFS. Those with exclusive CFS were more likely to report higher levels of pain and greater effect of pain compared with those without CFS, although associations attenuated to the null after adjustment for covariates, which did not occur in those with exclusive CWP. Multinomial regression revealed that relative to having neither CFS nor CWP, a 1-unit increase in the depression and anxiety scales increased the risk of having exclusive CFS and, to a greater extent, the risk of having comorbid CFS and CWP, but not exclusive CWP, which was only related to anxiety.
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Acute pain arises from activation of myelinated (A delta) and unmyelinated (C) nociceptive afferents, leading to first (A-fiber) or second (C-fiber) pain sensations. The current study sought to investigate first and second pain within glabrous and hairy skin sites in human upper limbs. Fifty healthy adults (25 male/25 female, 18-30 years old, mean = 20.5 ± 1.4 years) participated in a psychophysical study investigating electronically rated, thermal first and second pain sensations within the glabrous skin at the palm and hairy skin of the forearm. ⋯ Hairy skin presented a steeper slope for testing, whereas there were no differences in slope between first and second pain. The study findings support assumptions associated with mechanistic differences between first and second pain sensations, while offering a novel method for producing first and second pain with the same thermal stimulus. Efforts to understand abnormalities among people with clinical pain and development of new therapeutic agents will benefit from specific psychophysical methods.
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Patients with complex regional pain syndrome (CRPS) display various abnormalities in central motor function, and their pain is intensified when they perform or just observe motor actions. In this study, we examined the abnormalities of brain responses to action observation in CRPS. We analyzed 3-T functional magnetic resonance images from 13 upper limb CRPS patients (all female, ages 31-58 years) and 13 healthy, age- and sex-matched control subjects. ⋯ A pattern-classification analysis was applied to characterize brain areas where the activation pattern differed between CRPS patients and healthy subjects. Brain areas with statistically significant group differences (q < .05, false discovery rate-corrected) included the hand representation area in the sensorimotor cortex, inferior frontal gyrus, secondary somatosensory cortex, inferior parietal lobule, orbitofrontal cortex, and thalamus. Our findings indicate that CRPS impairs action observation by affecting brain areas related to pain processing and motor control.
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Pain intensity is often measured in clinical and research settings using the 0 to 10 numeric rating scale (NRS). NRS scores are recorded as discrete values, and in some samples they may display a high proportion of zeroes and a right-skewed distribution. Despite this, statistical methods for normally distributed data are frequently used in the analysis of NRS data. ⋯ We examined model fit, interpretability of results, and whether conclusions about the predictor effects changed across models. In this study, models that accommodate zero inflation provided a better fit than the other models. These models should be considered for the analysis of NRS data with a large proportion of zeroes.