The journal of pain : official journal of the American Pain Society
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Clinical Trial
Muscle pain differentially modulates short interval intracortical inhibition and intracortical facilitation in primary motor cortex.
Excitability of the motor cortex can be suppressed during muscle pain. Yet the mechanisms are largely unknown. Short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were examined as possible candidate mechanisms to underpin this change. SICI and ICF were investigated in 11 healthy individuals before, during and after infusion of hypertonic saline into right first dorsal interosseous (FDI). Using paired-pulse transcranial magnetic stimulation (TMS), interstimulus intervals of 2, 3, and 13 ms were investigated. Pain intensity and quality were recorded using a 10-cm visual analogue scale and the McGill Pain Questionnaire. Resting motor threshold and motor-evoked potentials (MEPs) to single TMS stimuli were recorded before and after pain. Electromyographic recordings were made from right FDI and abductor digiti minimi. Participants reported an average pain intensity of 5.8 (1.6) cm. MEP amplitudes decreased in both muscles. Compared with the pre-pain condition, SICI was increased following pain, but not during. ICF was decreased both during and after pain when compared with the pre-pain condition. These findings suggest that muscle pain differentially modulates SICI and ICF. Although the functional relevance is unknown, we hypothesize decreased facilitation and increased inhibition may contribute to the restriction of movement of a painful body part. ⋯ This article provides evidence for decreased intracortical facilitation and increased short interval intracortical inhibition in response to muscle pain. This finding is relevant to clinicians as a mechanism which may underlie restricted movement in acute and chronic pain.
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Historical Article
Time series analysis of California's prescription monitoring program: impact on prescribing and multiple provider episodes.
Prescription monitoring programs (PMPs) are designed to reduce medication diversion by identifying individuals obtaining the same medication from multiple providers (termed multiple provider episodes [MPEs]). This study determined whether recent changes to California's PMP influenced: 1) the extent that practitioners issue prescriptions for a variety of Schedule II opioids; and 2) the incidence of MPEs involving these opioids. Intervention time series of California's PMP data was used to determine the effect of requiring practitioners to transition from using triplicate prescription forms for Schedule II medications to security forms for all controlled substances. Outcome measures included changes in number of prescriptions issued for Schedule II long-acting or short-acting (SA) opioids and the MPEs involving these medications. Requiring a security form was associated with a sustained prescribing increase for SA hydromorphone, meperidine, and SA oxycodone; no prescribing changes were found for SA fentanyl, methadone, and SA morphine, or for any long-acting opioids. The same policy change, however, increased MPEs involving all opioids. Further effort is required to determine how California's PMP can continue to ensure availability of prescription opioids for medical use while better mitigating their diversion. ⋯ Statistical model-building was used to evaluate the influence of changes to California's prescription monitoring program. The extent that practitioners prescribe Schedule II opioids and the incidence of people receiving prescriptions from multiple providers were measured. Such research illustrates the viability of evaluating drug control program impact on prescribing practice and potential diversion behaviors.
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Physical functioning is often impaired in adolescents with chronic pain, which has largely been demonstrated through subjective self-report measures. Actigraphy uses motion monitoring as an objective means for assessing one dimension of physical functioning; physical activity level. This study used subjective and objective measures to assess multiple dimensions of physical functioning in a clinical sample of adolescents with chronic pain (n = 78) and a comparison group of healthy adolescents (n = 59). Individual and pain characteristics were also examined as predictors of actigraphy variables within the chronic pain sample. Results indicated that adolescents with chronic pain demonstrate significant impairment in subjective measures of physical functioning and evidence lower levels of physical activity. Actigraphic measures of physical activity were moderately correlated with self-report measures of physical functioning. Individual characteristics, including adolescent age, sex, and Body Mass Index percentile, were associated with physical activity levels among adolescents with chronic pain. Physical activity represents a distinct dimension of physical functioning. Assessing physical activity may provide additional description of physical functioning among adolescents with chronic pain, and may help identify targets for intervention in this population. ⋯ This study demonstrates that adolescents with chronic pain have lower physical activity levels, as measured objectively via actigraphy, as well as poorer subjective reports of physical functioning, compared to healthy adolescents. Actigraphic measurement of physical activity provides objective source data about one dimension of physical functioning.
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To assess the economic cost of chronic pain in Ireland, information was gathered from 140 people with chronic pain. Direct and indirect costs attributable to chronic pain and medical conditions of which chronic pain was a feature were recorded retrospectively for 12 months. Mean cost per chronic pain patient was estimated at €5,665 per year across all grades of pain, with mean costs increasing according to the severity of pain. A small proportion of patients account for the bulk of costs-the top 5% most expensive patients accounted for 26.4% of costs, with a mean cost per patient of €29,936, and the 10% most expensive patients were responsible for 42.8% of all costs. Total cost for individuals aged 20 and above was estimated at €5.34 billion per year, or 2.86% of Irish GDP in 2008. Those with clinically elevated depression scores had costs that were twice as high as people who scored below the depression cut-off score. Chronic pain services in Ireland are generally underresourced. Improved coordination and better management of patients via interdisciplinary pain rehabilitation program is essential and may offer a means of reducing the sizeable economic burden of chronic pain. ⋯ The cost of chronic pain per patient was €5,665 per year extrapolated to €5.34 billion or 2.86% of GDP per year. Those with clinically significant depression had costs twice as high as those without depression. The significant burden of chronic pain highlights the need for cost effective interventions to reduce long-term disability.
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Both race and socioeconomic status (SES) contribute to disparities. We assessed the relative roles of neighborhood socioeconomic status (nSES) and race in the chronic pain experience for young adults (<50 years old). Data from a tertiary care pain center was matched to 2000 US Census data to examine the role of race and nSES on chronic pain and its sequelae in 3,730 adults (9.7% black, 61% female) 18 to 49 years old (37 ± 8 years). Blacks had significantly more pain and disability and lived in lower SES neighborhoods. Living in a lower SES neighborhood was associated with increased sensory, affective, and "other" pain, pain-related disability, and mood disorders. Race was independently associated with affective and "other" pain on the McGill Pain Questionnaire scales, and both disability factors. Racial disparities in sensory pain and mood disorders were mediated by nSES. In every case, race and neighborhood SES played important roles in the outcomes for chronic pain. Age was related to both disability outcomes. Gender was associated with voluntary disability and mood disorders, with men displaying worse outcomes. ⋯ Important racial- and SES-related variability in pain related outcomes in young adults with chronic pain were defined. Black race was associated with neighborhood SES, and black race plays an important role in pain outcomes beyond neighborhood SES.