Pain
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The intensity of experimental pain is known to be dependent on stimulation duration. However, it remains unknown whether this effect arises largely from the actual stimulus duration or is substantially influenced by the subject's perception of the stimulus duration. In the present study, we questioned this issue by misleading the perception of the duration of pain in a population of 36 healthy volunteers stimulated with a thermode. ⋯ Although the intensity and the real duration of stimulation were identical in both conditions, the intensity of pain was significantly reduced when the perception of time was misleadingly shortened by the manipulated clock. This study suggests that the perceived duration of a noxious stimulation may influence the perceived intensity of pain. The perceived duration of the length of a noxious stimulation influences (decreases) the intensity of perceived pain.
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The objective of this paper is to better understand the relationship of pain and mood in patients with fibromyalgia and comorbid major depressive disorder (MDD). Pooled data from 4 double-blind, placebo-controlled, randomized trials of duloxetine hydrochloride 60-120mg/day in patients with fibromyalgia were included (N=1332). Of these, 350 (26% [147 placebo, 203 duloxetine]) had comorbid MDD (per Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Text Revision criteria) and were included in these analyses. ⋯ Results indicated that 69% of improvement in pain was a direct effect of treatment, with improvement in mood accounting for 31% of pain response. In conclusion, consistent with our hypothesis, duloxetine produced a substantial direct effect on pain improvement and change in mood exerted a modest indirect effect on pain improvements in patients with fibromyalgia and MDD. Hence, both direct and indirect analgesic and antidepressant properties appear to be relevant for the treatment of these comorbid patients with duloxetine.
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This is a revision of guidelines, originally published in 2004, for the assessment of patients with neuropathic pain. Neuropathic pain is defined as pain arising as a direct consequence of a lesion or disease affecting the somatosensory system either at peripheral or central level. Screening questionnaires are suitable for identifying potential patients with neuropathic pain, but further validation of them is needed for epidemiological purposes. ⋯ Skin biopsy to measure the intraepidermal nerve fiber density should be performed in patients with clinical signs of small fiber dysfunction. The intensity of pain and treatment effect (both in clinic and trials) should be assessed with numerical rating scale or visual analog scale. For future neuropathic pain trials, pain relief scales, patient and clinician global impression of change, the proportion of responders (50% and 30% pain relief), validated neuropathic pain quality measures and assessment of sleep, mood, functional capacity and quality of life are recommended.
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Cross-sectional designs and self-reports of maltreatment characterize nearly all the literature on childhood abuse or neglect and pain in adulthood, limiting potential for causal inference. The current study describes a prospective follow up of a large cohort of individuals with court-documented early childhood abuse or neglect (n=458) and a demographically matched control sample (n=349) into middle adulthood (mean age 41), nearly 30 years later, comparing the groups for risk of adult pain complaints. We examine whether Post-Traumatic Stress Disorder (PTSD) mediates or moderates risk of pain. ⋯ However, across all pain outcomes other than medically unexplained pain, PTSD robustly interacted with documented childhood victimization to predict adult pain risk: Individuals with both childhood abuse/neglect and PTSD were at significantly increased risk (p<.001, η(2) generally=.05-.06) of pain. After accounting for the combined effect of the two factors, neither childhood victimization nor PTSD alone predicted pain risk. Findings support a view that clinical pain assessments should focus on PTSD rather than make broad inquiries into past history of childhood abuse or neglect.
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Chronic pain is more common in the elderly and impairs functioning and quality of life. Though obesity, defined by body mass index (BMI), has been associated with pain prevalence among older adults, the mechanism of this association remains unclear. We examined components of the metabolic syndrome, insulin resistance, a marker of inflammation, and the presence of painful comorbidities as possible mediators of this association. ⋯ Of the clinical components of metabolic syndrome, central obesity was significantly associated with pain (OR 2.03, 95% CI 1.36-3.01). After adjustment for insulin resistance, inflammation, and pain-related comorbidities, central obesity predicted higher TPI scores (OR 1.55, 95% CI 1.04-2.33) and nearly doubled the risk of chronic pain (OR 1.70, 95% CI 1.05-2.75). Central obesity is the metabolic syndrome component showing the strongest independent association with pain, and the relationship is not explained by markers of insulin resistance or inflammation, nor by the presence of osteoarthritis or neuropathy.