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Assessing peripheral fibers, pain sensitivity, central sensitization, and descending inhibition in Native Americans: main findings from the Oklahoma Study of Native American Pain Risk (OK-SNAP).

Native Americans (NAs) have a higher prevalence of chronic pain than other U.S. racial/ethnic groups, but there have been few attempts to understand the mechanisms of this pain disparity. This study used a comprehensive battery of laboratory tasks to assess peripheral fiber function (cool/warm detection thresholds), pain sensitivity (eg, thresholds/tolerances), central sensitization (eg, temporal summation), and pain inhibition (conditioned pain modulation) in healthy, pain-free adults (N=155 NAs, N=150 non-Hispanic Whites, NHW). Multiple pain stimulus modalities were used (eg, cold, heat, pressure, ischemic, electric), and subjective (eg, pain ratings, pain tolerance) and physiological (eg, nociceptive flexion reflex) outcomes were measured. There were no group differences on any measure, except that NAs had lower cold pressor pain thresholds and tolerances, indicating greater pain sensitivity than NHWs. These findings suggest that there are no group differences between healthy NAs and NHWs on peripheral fiber function, central sensitization, or central pain inhibition, but NAs may have greater sensitivity to cold pain. Future studies are needed to examine potential within-group factors that might contribute to NA pain risk.

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Assessing peripheral fibers, pain sensitivity, central sensitization, and descending inhibition in Native Americans: main findings from the Oklahoma Study of Native American Pain Risk.

Native Americans (NAs) have a higher prevalence of chronic pain than other U.S. racial/ethnic groups, but there have been few attempts to understand the mechanisms of this pain disparity. This study used a comprehensive battery of laboratory tasks to assess peripheral fiber function (cool/warm detection thresholds), pain sensitivity (eg, thresholds/tolerances), central sensitization (eg, temporal summation), and pain inhibition (conditioned pain modulation) in healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). Multiple pain stimulus modalities were used (eg, cold, heat, pressure, ischemic, and electric), and subjective (eg, pain ratings and pain tolerance) and physiological (eg, nociceptive flexion reflex) outcomes were measured. There were no group differences on any measure, except that NAs had lower cold-pressor pain thresholds and tolerances, indicating greater pain sensitivity than NHWs. These findings suggest that there are no group differences between healthy NAs and NHWs on peripheral fiber function, central sensitization, or central pain inhibition, but NAs may have greater sensitivity to cold pain. Future studies are needed to examine potential within-group factors that might contribute to NA pain risk.

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Association between Itch and Cancer in 3836 Pediatric Pruritus Patients at a Tertiary Care Center.

: Pruritus is a well-recognized paraneoplastic phenomenon. Previous studies have examined the association of itch with a variety of malignancies in adults. However, no large study has examined this association in a pediatric population. : A retrospective study was conducted of patients age 18 or less seen at Johns Hopkins Health System between 2012 and 2019. : A pediatric hospital population of 1,042,976 patients was reviewed. Pruritus was observed in 3836 pediatric patients of whom 130 also had cancer. Pediatric patients with pruritus were significantly more likely to have concomitant malignancy compared to pediatric patients without pruritus (OR 12.84; 95% CI 10.73-15.35, < 0.001). Malignancies most strongly associated with pruritus included neoplasms of the blood (OR 14.38; 95% CI 11.30-18.29, < 0.001), bone (OR 29.02, 95% CI 18.28-46.06, < 0.001) and skin (OR 22.76, 95% CI 9.14-56.72, < 0.001. : Pruritus is significantly associated with malignancy in the pediatric hospital population. Clinicians should also be aware of the high burden of itch in pediatric malignancies and the variation in pruritus across malignancies.

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Self-motion perception is sensitized in vestibular migraine: pathophysiologic and clinical implications.

Vestibular migraine (VM) is the most common cause of spontaneous vertigo but remains poorly understood. We investigated the hypothesis that central vestibular pathways are sensitized in VM by measuring self-motion perceptual thresholds in patients and control subjects and by characterizing the vestibulo-ocular reflex (VOR) and vestibular and headache symptom severity. VM patients were abnormally sensitive to roll tilt, which co-modulates semicircular canal and otolith organ activity, but not to motions that activate the canals or otolith organs in isolation, implying sensitization of canal-otolith integration. When tilt thresholds were considered together with vestibular symptom severity or VOR dynamics, VM patients segregated into two clusters. Thresholds in one cluster correlated positively with symptoms and with the VOR time constant; thresholds in the second cluster were uniformly low and independent of symptoms and the time constant. The VM threshold abnormality showed a frequency-dependence that paralleled the brain stem velocity storage mechanism. These results support a pathogenic model where vestibular symptoms emanate from the vestibular nuclei, which are sensitized by migraine-related brainstem regions and simultaneously suppressed by inhibitory feedback from the cerebellar nodulus and uvula, the site of canal-otolith integration. This conceptual framework elucidates VM pathophysiology and could potentially facilitate its diagnosis and treatment.

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Association of Length of Time Spent in the United States With Opioid Use Among First-Generation Immigrants.

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Pain-free resting-state functional brain connectivity predicts individual pain sensitivity.

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Cornea nerve fiber state determines analgesic response to tapentadol in fibromyalgia patients without effective endogenous pain modulation.

Tapentadol is a centrally acting analgesic with μ-agonistic activity combined with noradrenaline reuptake inhibition. Its mechanism of action relies on improvement of descending pain inhibition. In the current study, tapentadol's ability to enhance conditioned pain modulation (CPM, an experimental measure of descending pain inhibition) was evaluated in fibromyalgia patients with absent or reduced CPM responses.

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Effectiveness, cost-utility, and benefits of a multicomponent therapy to improve the quality of life of patients with fibromyalgia in primary care: A mixed methods study protocol.

Fibromyalgia (FM) is a chronic condition characterized by chronic pain, fatigue and loss of function which significantly impairs quality of life. Although treatment of FM remains disputed, some studies point at the efficacy of interdisciplinary therapy. This study aims to analyze the effectiveness, cost-utility and benefits of a multicomponent therapy on quality of life (main variable), functional impact, mood and pain in people suffering from FM that attend primary care centers (PCCs) of the Catalan Institute of Health (ICS).

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Antipruritic effects of transient heat-stimulation on histaminergic and non-histaminergic itch.

Chronic itch is notoriously difficult to treat. Counter-stimuli are able to inhibit itch, but this principle is difficult to apply in clinical practice, and the mechanisms behind counter-stimulation-induced itch suppression in humans are unclear.

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Age-related differences in patient-reported and objective measures of chemotherapy-induced peripheral neuropathy among cancer survivors.

While older adults with cancer are more likely to develop chemotherapy-induced peripheral neuropathy (CIPN), the study aimed to determine if patient-reported and objective measures of CIPN differ by age among cancer survivors.

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