The journal of pain : official journal of the American Pain Society
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Substantial literature suggests that diverse biological, psychological, and sociocultural mechanisms account for differences by race and ethnicity in the experience, epidemiology, and management of pain. Many studies have examined differences between Whites and minority populations, but American Indians (AIs), Alaska Natives (ANs), and Aboriginal peoples of Canada have been neglected both in studies of pain and in efforts to understand its biopsychosocial and cultural determinants. This article reviews the epidemiology of pain and identifies factors that may affect clinical assessment and treatment in these populations. We searched for peer-reviewed articles focused on pain in these populations, using PubMed, CINAHL, Cochrane, and the University of New Mexico Native Health Database. We identified 28 articles published 1990 to 2009 in 3 topic areas: epidemiology of pain, pain assessment and treatment, and healthcare utilization. A key finding is that AI/ANs have a higher prevalence of pain symptoms and painful conditions than the U.S. general population. We also found evidence for problems in provider-patient interactions that affect clinical assessment of pain, as well as indications that AI/AN patients frequently use alternative modalities to manage pain. Future research should focus on pain and comorbid conditions and develop conceptual frameworks for understanding and treating pain in these populations. ⋯ We reviewed the literature on pain in AI/ANs and found a high prevalence of pain and painful conditions, along with evidence of poor patient-provider communication. We recommend further investigation of pain and comorbid conditions and development of conceptual frameworks for understanding and treating pain in this population.
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Non-adherence to opioid prescriptions can decrease the safety and efficacy of opioid therapy. Identifying factors associated with over- and under-use of opioids in patients presenting with pain may improve prescribing and pain management. Patients presenting with pain often also present with somatization, and somatization is associated with both excessive use of and non-adherence to medications. This study examines the relationship between somatization and non-adherence (over- and under-use) to opioid prescriptions in the Veteran sample. One hundred and ninety-one Veterans who received an opioid prescription at a Veterans Affairs Palo Alto Health Care System in the prior year participated by completing a 1.5 hour semistructured interview which included assessments of depressive symptoms, somatization, medication side effects, and opioid pain medication usage. The percentage of patients non-adherent to opioid prescriptions increased as a function of somatization: Compared to no somatization, all levels of somatization were associated with higher rates of underuse, while severe somatization was associated with increased rates of overuse. Consistent with previous studies of medication non-adherence, increased depression and medication side effects were associated with decreased adherence to opioid prescriptions. However, in exploratory analyses, somatization mediated the relationship between depressive symptoms and opioid-use patterns as well as medication side effects and opioid use patterns. ⋯ This article sought to explore the relationship between somatization and adherence to prescription opioid medications. Our findings suggest that pain management treatment plans may be optimized by addressing patient distress about physical symptoms when considering the use of prescription opioid medications.
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The electrical stimulation of the occipital (OC) or retrosplenial (RSC) cortex produces antinociception in the rat tail-flick test. These cortices send inputs to the anterior pretectal nucleus (APtN) which is implicated in antinociception and nociception. At least muscarinic cholinergic, opioid, and serotonergic mechanisms in the APtN are involved in stimulation-produced antinociception (SPA) from the nucleus. In this study, the injection of 2% lidocaine (.25 μL) or methysergide (40 and 80 ng/.25 μL) into the APtN reduced the duration but did not change the intensity of SPA from the OC, whereas both duration and intensity of SPA from the RSC were significantly reduced in rats treated with lidocaine or naloxone (10 and 50 ng/.25 μL), injected into the APtN. Naloxone or methysegide injected into the APtN was ineffective against SPA from the OC or RSC, respectively. Atropine (100 ng/.25 μL) injected into the APtN was ineffective against SPA from either the OC or RSC. We conclude that the APtN acts as an intermediary for separate descending pain inhibitory pathways activated from the OC and RSC, utilizing at least serotonin and endogenous opioid as mediators in the nucleus. ⋯ Stimulation-induced antinociception from the retrosplenial or occipital cortex in the rat tail-flick test depends on the activation of separate descending pain inhibitory pathways that utilize the APtN as a relay station.
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Randomized Controlled Trial
Transcranial DC stimulation in fibromyalgia: optimized cortical target supported by high-resolution computational models.
In this study we aimed to determine current distribution and short-term analgesic effects of transcranial direct current stimulation (tDCS) in fibromyalgia using different electrode montages. For each electrode montage, clinical effects were correlated with predictions of induced cortical current flow using magnetic resonance imaging-derived finite element method head model. Thirty patients were randomized into 5 groups (Cathodal-M1 [primary motor cortex], Cathodal-SO [supra-orbital area], Anodal-M1, Anodal-SO, and Sham) to receive tDCS application (2 mA, 20 minutes) using an extracephalic montage. Pain was measured using a visual numerical scale (VNS), pressure pain threshold (PPT), and a body diagram (BD) evaluating pain area. There was significant pain reduction in cathodal-SO and anodal-SO groups indexed by VNS. For PPT there was a trend for a similar effect in anodal-SO group. Computer simulation indicated that the M1-extracephalic montage produced dominantly temporo-parietal current flow, consistent with lack of clinical effects with this montage. Conversely, the SO-extracephalic montage produced current flow across anterior prefrontal structures, thus supporting the observed analgesic effects. Our clinical and modeling findings suggest that electrode montage, considering both electrodes, is critical for the clinical effects of M1-tDCS as electric current needs to be induced in areas associated with the pain matrix. These results should be taken into consideration for the design of pain tDCS studies. ⋯ Results in this article support that electrode montage is a critical factor to consider for the clinical application of tDCS for pain control, as there is an important correlation between the location of induced electrical current and tDCS-induced analgesic effects.
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Preliminary reports suggest that acceptance of pain is an important construct when assessing and treating adolescents with chronic pain. Although the Chronic Pain Acceptance Questionnaire, Adolescent version (CPAQ-A) appears to be a promising tool, it has been evaluated in only 1 study. The current results present a confirmatory analysis of the CPAQ-A and validity data collected independently from the developers of the scale. A sample of 109 adolescents with chronic pain completed the CPAQ-A, as well as measures of pain characteristics, functional impairment, depression, anxiety, and pain self-efficacy. Results of the confirmatory factor analysis indicate the previously reported 2-factor solution provides a good fit to the data, and has acceptable internal consistency. The CPAQ-A correlated strongly with disability, depression, anxiety, and self-efficacy. It correlated only moderately with pain intensity and was not correlated with pain frequency or duration of pain. When entered last into a hierarchical regression model predicting disability, acceptance accounted for more variance than pain intensity, depression, anxiety, and self-efficacy. Results supported the internal consistency and validity of the CPAQ-A as a measure of pain acceptance in this sample of adolescents with chronic pain. Use of the CPAQ-A may provide valuable insight into the manner in which adolescents adapt to chronic pain and can guide acceptance-based treatment. ⋯ This article strengthens the psychometric support for a measure of chronic pain acceptance in adolescents. Acceptance-based treatment has been shown to reduce disability in preliminary research targeting adolescents with chronic pain; the CPAQ-A may be useful for assessing the degree to which acceptance-based approaches may be indicated for a given patient.