The journal of pain : official journal of the American Pain Society
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Widespread hyperalgesia is well documented among adult patients with irritable bowel syndrome (IBS), but little is known about pain sensitivity among adolescents with IBS. We examined pain sensitivity in 961 adolescents from the general population (mean age 16.1 years), including pain threshold and tolerance measurements of heat (forearm) and pressure pain (fingernail and shoulder) and cold pressor tolerance (hand). Adolescents with IBS symptoms (Rome III criteria) had lower heat pain thresholds compared to controls after adjustments for sex, comorbid pain, and psychological distress (mean difference = -.8 °C; 95% confidence interval [CI] = -1.6 to -.04). Similar results were found for pressure pain threshold at the shoulder (mean difference = -46 kPa; 95% CI = -78 to -13) and fingernail (mean difference = -62 kPa; 95% CI = -109 to -15), and for an aggregate of all 3 threshold measures (z-score difference = -.4; 95% CI = -.6 to -.2), though pressure pain threshold differences were nonsignificant after the final adjustments for psychological distress. No difference of pain tolerance was found between the IBS cases and controls. Our results indicate that adolescents in the general population with IBS symptoms, like adults, have widespread hyperalgesia. ⋯ This is the first report of widespread hyperalgesia among adolescents with IBS symptoms in the general population, with lower pain thresholds found to be independent of sex and comorbid pain. Our results suggest that central pain sensitization mechanisms in IBS may contribute to triggering and maintaining chronic pain symptoms.
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Most studies on pain focus on specific disorders, which makes it difficult to compare characteristics across different types of pain symptoms. In this large population-based study, we examine the prevalence and comorbidity patterns among pain symptoms across a wide range of anatomic sites (back, neck, head, abdomen, joints, chest, face, teeth, and "other") in relation to anxious depression and a range of demographic, health, and lifestyle variables. Self-report data were collected in 11,787 adult participants of The Netherlands Twin Registry (mean age 44.5 years, 62% female), including twins and relatives of twins. Headache and abdominal pain were strongly associated with female sex, whereas chest pain and toothache were not. Joint pain strongly increased with age, whereas headache and abdominal pain decreased with age. Most other pain sites were only weakly associated with age. A highly consistent pattern of comorbidity was observed: All pain symptoms were correlated with all other pain symptoms, as well as with anxious depression. Frequent and widespread pain (ie, pain at multiple sites) was most strongly associated with anxious depression. These observations reflect important differences between specific pain symptoms, suggesting partly separate etiologies, but also highlight the importance of shared mechanisms underlying pain symptoms in general. ⋯ The association of pain with sex and age strongly depends on pain location. However, all pain sites are consistently associated with other pain sites as well as with anxious depression. This provides important clues with respect to both similarities and differences in the mechanisms underlying different types of pain.
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Temporomandibular disorder and irritable bowel syndrome are comorbid functional chronic pain disorders of unknown etiology that are triggered/exacerbated by stress. Here we present baseline phenotypic characterization of a novel animal model to gain insight into the underlying mechanisms that contribute to such comorbid pain conditions. In this model, chronic visceral hypersensitivity, a defining symptom of irritable bowel syndrome, is dependent on 3 factors: estradiol, existing chronic somatic pain, and stress. In ovariectomized rats, estradiol replacement followed by craniofacial muscle injury and stress induced visceral hypersensitivity that persisted for months. Omission of any 1 factor resulted in a transient (1 week) visceral hypersensitivity from stress alone or no hypersensitivity (no inflammation or estradiol). Maintenance of visceral hypersensitivity was estradiol dependent, resolving when estradiol replacement ceased. Referred cutaneous hypersensitivity was concurrent with visceral hypersensitivity. Increased spinal Fos expression suggests induction of central sensitization. These data demonstrate the development and maintenance of visceral hypersensitivity in estradiol-replaced animals following distal somatic injury and stress that mimics some characteristics reported in patients with temporomandibular disorder and comorbid irritable bowel syndrome. This new animal model is a powerful experimental tool that can be employed to gain further mechanistic insight into overlapping pain conditions. ⋯ The majority of patients with temporomandibular disorder report symptoms consistent with irritable bowel syndrome. Stress and female prevalence are common to both conditions. In a new experimental paradigm in ovariectomized rats with estradiol replacement, masseter inflammation followed by stress induces visceral hypersensitivity that persists for months, modeling these comorbid pain conditions.
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Review Meta Analysis
Incidence and severity of chronic pain at 3 and 6 months after thoracotomy: meta-analysis.
This systematic review was performed to determine the incidence and the severity of chronic pain at 3 and 6 months after thoracotomy based on meta-analyses. We conducted MEDLINE, Web of Science, and Google Scholar searches of databases and references for English articles; 858 articles were reviewed. Meta-regression analysis based on the publication year was used to examine if the chronic pain rates changed over time. Event rates and confidence intervals with random effect models and Freeman-Tukey double arcsine variance-stabilizing transformation were obtained separately for the incidence of chronic pain based on 1,439 patients from 17 studies at 3 months and 1,354 patients from 15 studies at 6 months. The incidences of chronic pain at 3 and 6 months after thoracotomy were 57% (95% confidence interval [CI], 51-64%) and 47% (95% CI, 39-56%), respectively. The average severity of pain ratings on a 0 to 100 scale at these times were 30 ± 2 (95% CI, 26-35) and 32 ± 7 (95% CI, 17-46), respectively. Reported chronic pain rates have been largely stable at both 3 and 6 months from the 1990s to the present. ⋯ This systematic review's findings suggest that reported chronic pain rates are approximately 50% at 3 and 6 months and have been largely stable from the 1990s to the present. The severity of this pain is not consistently reported. Chronic pain after thoracotomy continues to be a significant problem despite advancing perioperative care.
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The aim of this study was to assess the economic cost of chronic pain among adolescents receiving interdisciplinary pain treatment. Information was gathered from 149 adolescents (ages 10-17) presenting for evaluation and treatment at interdisciplinary pain clinics in the United States. Parents completed a validated measure of family economic attributes, the Client Service Receipt Inventory, to report on health service use and productivity losses due to their child's chronic pain retrospectively over 12 months. Health care costs were calculated by multiplying reported utilization estimates by unit visit costs from the 2010 Medical Expenditure Panel Survey. The estimated mean and median costs per participant were $11,787 and $6,770, respectively. Costs were concentrated in a small group of participants; the top 5% of those patients incurring the highest costs accounted for 30% of total costs, whereas the lower 75% of participants accounted for only 34% of costs. Total costs to society for adolescents with moderate to severe chronic pain were extrapolated to $19.5 billion annually in the United States. The cost of adolescent chronic pain presents a substantial economic burden to families and society. Future research should focus on predictors of increased health services use and costs in adolescents with chronic pain. ⋯ This cost of illness study comprehensively estimates the economic costs of chronic pain in a cohort of treatment-seeking adolescents. The primary driver of costs was direct medical costs followed by productivity losses. Because of its economic impact, policy makers should invest resources in the prevention, diagnosis, and treatment of chronic pediatric pain.