Pain
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Randomized Controlled Trial
Brain networks predicting placebo analgesia in a clinical trial for chronic back pain.
A fundamental question for placebo research is whether such responses are a predisposition, quantifiable by brain characteristics. We examine this issue in chronic back pain (CBP) patients who participated in a double-blind brain imaging (functional magnetic resonance imaging) clinical trial. We recently reported that when the 30 CBP participants were treated, for 2 weeks, with topical analgesic or no drug patches, pain and brain activity decreased independently of treatment type and thus were attributed to placebo responses. ⋯ Additionally, by means of frequency domain contrasts, we observe that at baseline, left dorsolateral prefrontal cortex high-frequency oscillations also predicted treatment outcomes and identified an additional set of functional connections distinguishing treatment outcomes. Combining medial and lateral prefrontal functional connections, we observe a statistically higher accuracy (0.9) for predicting posttreatment groups. These findings indicate that placebo response can be identified a priori at least in CBP, and that neuronal population interactions between prefrontal cognitive and pain processing regions predetermine the probability of placebo response in the clinical setting.
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Psychological factors are thought to play a part in the aetiology of chronic widespread pain. We investigated the relationship between intelligence in childhood and risk of chronic widespread pain in adulthood in 6902 men and women from the National Child Development Survey (1958 British Birth Cohort). Participants took a test of general cognitive ability at age 11 years; and chronic widespread pain, defined according to the American College of Rheumatology criteria, was assessed at age 45 years. ⋯ In multivariate backwards stepwise regression, lower childhood intelligence remained as an independent predictor of chronic widespread pain (RR 1.10; 95% CI 1.01-1.19), along with social class, educational attainment, body mass index, smoking status, and psychological distress. Part of the effect of lower childhood intelligence on risk of chronic widespread pain in midlife was significantly mediated through greater body mass index and more disadvantaged socioeconomic position. Men and women with higher intelligence in childhood are less likely as adults to report chronic widespread pain.
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Randomized Controlled Trial
Associations between daily chronic pain intensity, daily anger expression, and trait anger expressiveness: an ecological momentary assessment study.
Links between elevated trait anger expressiveness (anger-out) and greater chronic pain intensity are well documented, but pain-related effects of expressive behaviors actually used to regulate anger when it is experienced have been little explored. This study used ecological momentary assessment methods to explore prospective associations between daily behavioral anger expression and daily chronic pain intensity. Forty-eight chronic low back pain (LBP) patients and 36 healthy controls completed electronic diary ratings of momentary pain and behavioral anger expression in response to random prompts 4 times daily for 7 days. ⋯ Overlap with trait and state negative affect did not account for study findings. This study for the first time documents lagged within-day influences of behavioral anger expression on subsequent chronic pain intensity. Trait anger regulation style may moderate associations between behavioral anger expression and chronic pain intensity.
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Case Reports
A case of pain, motor impairment, and swelling of the arm after acute herpes zoster infection.
Complex regional pain syndrome (CRPS) and postherpetic neuralgia (PHN) represent neuropathic pain syndromes that may appear with similar clinical signs and symptoms. Medical history and clinical distribution of symptoms and signs (PHN typically at the thorax; CRPS typically at the limbs) is obvious in most cases, helping to discriminate between both disorders. Here, we present a patient suffering from CRPS II following PHN of one upper extremity. This case demonstrates that both etiology and part of the body affected by a neuropathy influence the pain phenotype.
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Distraction is a strategy that is commonly used to cope with pain. Results concerning the efficacy of distraction from both experimental and clinical studies are variable, however, and indicate that its efficacy may depend on particular circumstances. Several models propose that distraction may be less effective for people who display a large attentional bias towards pain-related information. ⋯ Results indicated that people who display a large attentional bias towards predictive cues of pain or who initially experience the pain as more painful benefit less from distraction on a subsequent test. No effects were found between attentional bias towards pain words, state-trait anxiety, catastrophic thinking, and the efficacy of distraction. Current findings suggest that distraction should not be used as a 'one size fits all' method to control pain, but only under more specific conditions.