The journal of pain : official journal of the American Pain Society
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The dorsolateral prefrontal cortex (DLPFC) is a functionally and structurally heterogeneous region and a key node of several brain networks, implicated in cognitive, affective, and sensory processing. As such, the DLPFC is commonly activated in experimental pain studies, and shows abnormally increased function in chronic pain populations. Furthermore, several studies have shown that some chronic pains are associated with decreased left DLPFC gray matter and that successful interventions can reverse this structural abnormality. In addition, studies have indicated that noninvasive stimulation of the left DLPFC effectively treats some chronic pains. In this article, we review the neuroimaging literature regarding the role of the DLPFC and its potential as a therapeutic target for chronic pain conditions, including studies showing the involvement of the DLPFC in encoding and modulating acute pain and studies demonstrating the reversal of DLPFC functional and structural abnormalities after successful interventions for chronic pain. We also review studies of noninvasive brain stimulation of the DLPFC showing acute pain modulation and some effectiveness as a treatment for certain chronic pain conditions. We further discuss the network architecture of the DLPFC, and postulate mechanisms by which DLPFC stimulation alleviates chronic pain. Future work testing these mechanisms will allow for more effective therapies. ⋯ The structure and function of the DLPFC is abnormal in some chronic pain conditions. Upon successful resolution of pain, these abnormalities are reversed. Understanding the underlying mechanisms and the role of this region can lead to the development of an effective therapeutic target for some chronic pain conditions.
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Claims are made for the validity of some self-report pain scales for 3- and 4-year-old children, but little is known about their ability to use such tools. This systematic review identified self-report pain intensity measures used with 3- and/or 4- year-old participants (3-4yo) and considered their reliability and validity within this age span. The search protocol identified research articles that included 3-4yo, reported use of any pain scale, and included self-reported pain intensity ratings. A total of 1,590 articles were screened and 617 articles met inclusion criteria. Of the included studies, 98% aggregated self-report data for 3-4yo with data for older children, leading to overestimates of the reliability and validity of self-report in the younger age group. In the 14 studies that provided nonaggregated data for 3-4yo, there was no evidence for 3-year-old and weak evidence for 4-year-old children being able to use published self-report pain intensity tools in a valid or reliable way. Preschool-age children have been reported to do better with fewer than the 6 response options offered on published faces scales. Simplified tools are being developed for young children; however, more research is needed before these are adopted. ⋯ Some self-report pain scales have been promoted for use with 3- and 4-year-old children, but this is on the basis of studies that aggregated data for younger and older children, resulting in overestimates of reliability and validity for the preschool-age children. Scales with fewer response options show promise, at least for 4-year-old children.
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Individuals experiencing homelessness in the United States are aging; little is known about chronic pain in this population. In a cross-sectional, population-based study, we interviewed 350 homeless individuals aged 50 years and older to describe pain experienced by older persons experiencing homelessness and to assess factors associated with chronic moderate to severe pain, defined as pain lasting ≥3 months, with a past week average severity score of 5 to 10 (scale 0-10). The median age of participants was 58 years. Participants were predominantly African American (79.6%) and male (77.3%). Overall, 46.8% reported chronic moderate to severe pain. Almost half of participants reported a diagnosis of arthritis (44.3%) and one-third reported symptoms consistent with post-traumatic stress disorder (PTSD; 32.8%). Three-quarters (75.3%) endorsed a personal history of abuse. In multivariate analyses, PTSD (adjusted odds ratio [AOR]: 2.2, 95% confidence interval [CI], 1.4-3.7), arthritis (AOR: 4.8, 95% CI, 3.0-7.8), and history of experiencing abuse (AOR: 2.4, 95% CI, 1.3-4.3) were associated with chronic moderate to severe pain. HIV status, diabetes, depressive symptoms, and substance use were not associated with pain. Clinicians should consider the management of associated mental health conditions and the sequelae of experiencing abuse in the treatment of chronic pain in older adults experiencing homelessness. ⋯ This article describes the prevalence and factors associated with chronic pain in older homeless adults. Almost half report chronic pain, which was associated with PTSD, arthritis, and personal history of abuse. Clinicians should address chronic pain, trauma, and the associated mental health conditions in this high-risk population.
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Randomized Controlled Trial
Responsiveness and Minimally Important Differences for Four Patient-Reported Outcomes Measurement Information System (PROMIS) Short Forms: Physical Function, Pain Interference, Depression, and Anxiety in Knee Osteoarthritis.
Patient-Reported Outcomes Measurement Information System (PROMIS) instruments can provide valid, interpretable measures of health status among adults with osteoarthritis (OA). However, their ability to detect meaningful change over time is unknown. We evaluated the responsiveness and minimally important differences (MIDs) for 4 PROMIS Short Forms: Physical Function, Pain Interference, Depression, and Anxiety. We analyzed adults with symptomatic knee OA from our randomized trial comparing Tai Chi and physical therapy. Using baseline and 12-week scores, responsiveness was evaluated according to consensus standards by testing 6 a priori hypotheses of the correlations between PROMIS and legacy change scores. Responsiveness was considered high if ≥5 hypotheses were confirmed, and moderate if 3 or 4 were confirmed. MIDs were evaluated according to prospective change for people achieving previously-established MID on legacy comparators. The lowest and highest MIDs meeting a priori quality criteria formed a MID range for each PROMIS Short Form. Among 165 predominantly female (70%) and white (57%) participants, mean age was 61 years and body mass index was 33. PROMIS Physical Function had 5 confirmed hypotheses and Pain Interference, Depression, and Anxiety had 3 or 4. MID ranges were: Depression = 3.0 to 3.1; Anxiety = 2.3 to 3.4; Physical Function = 1.9 to 2.2; and Pain Interference = 2.35 to 2.4. PROMIS Physical Function has high responsiveness, and Depression, Anxiety, and Pain Interference have moderate responsiveness among adults with knee OA. We established the first MIDs for PROMIS in this population, and provided an important standard of reference to better apply or interpret PROMIS in future trials or clinical practice. ⋯ This study examined whether PROMIS Short Form instruments (Physical Function, Pain Interference, Depression, and Anxiety) were able to detect change over time among adults with knee OA, and provided minimally important change estimates for each measure. This standard of reference can help apply or interpret these instruments in the future.
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Comparative Study
Age differences in the time-course and magnitude of changes in circulating neuropeptides following pain evocation in humans.
This study tested the hypothesis that older adults would have a stronger response for substance P (facilitatory) but weaker response to β-endorphin (inhibitory), in magnitude as well as time course. Eight younger and 9 older adults underwent 3 experimental sessions using well validated laboratory pain models: cold pressor task, contact heat pain, and a nonpainful control. Blood was collected through an indwelling catheter at baseline and 3, 15, 30, 45, and 60 minutes after stimuli administration. Older adults had higher baseline levels of both neuropeptides suggesting increased peripheral activity compared with younger adults. After the cold pressor task, older adults demonstrated a quick and strong release of substance P with dramatic recovery, whereas young adults maintained a constant low-grade response. Unlike substance P, β-endorphin increased between 3 and 15 minutes for both groups with the upsurge substantially higher for older adults. After heat pain, younger adults had an immediate surge in circulating substance P and β-endorphin that was more pronounced than among older adults. However, levels of substance P for younger adults slowly tapered whereas they continued to climb for the older adults through 30 minutes. β-endorphin peaked at 30 minutes for both groups and returned to baseline. No changes were observed during the nonpainful control session. ⋯ Older adults had higher baseline levels of substance P and β-endorphin suggesting increased peripheral activity compared with younger adults. After pain evocation, older adults demonstrated a more intense early response for both neuropeptides suggesting peripheral mechanisms involved in the response to pain may change with age.