The journal of pain : official journal of the American Pain Society
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Though perioperative pain neuroscience education (PPNE) positively influences patients' surgical outcomes, little is known about the mechanisms behind this treatment's success. Therefore, this study aims to evaluate the potential mediating role of pain cognitions and pain sensitivity in the treatment effect of PPNE on postoperative quality of life in people undergoing surgery for lumbar radiculopathy. This secondary analysis uses data from 120 participants of a randomized controlled trial who were randomized to receive either PPNE or perioperative biomedical education before undergoing surgery for lumbar radiculopathy. ⋯ PERSPECTIVE: This secondary analysis identified pain catastrophizing as a mediator for PPNE in people undergoing surgery for lumbar radiculopathy. More so, its findings indicate that this educational intervention can enhance the postoperative physical health-related quality of life of these patients by addressing their catastrophizing thoughts. TRIAL REGISTRATION: Clinicaltrials.gov (NCT02630732).
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Conditioning and expectation are known to be the main mechanisms of placebo analgesia. They may operate together, so that expectations may be enhanced by a conditioning procedure. Although most of the studies have tried to potentiate expectations through conditioning in order to generate good placebo responders, a few studies have tried to mismatch conditioning and expectations in order to investigate the subsequent administration of a placebo. ⋯ They also stress the importance of expectations in the therapeutic outcome, with important implications for clinical trials. PERSPECTIVE: By using mismatch conditioning, in which study participants did not get what they expected, we reduced expectations of analgesia, and this reduction abolished placebo analgesia. This effect extended to other parts of the body and other types of pain, which indicates that placebo nonresponders can be created in the laboratory.
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Review Meta Analysis
The impact of sleep disturbances on endogenous pain modulation: a systematic review and meta-analysis.
The bidirectional relationship between sleep and pain problems has been extensively demonstrated but despite all the accumulating evidence, their shared mechanisms are currently not fully understood. This review examined the association between sleep disturbances, defined as a broad array of sleep-related outcomes (eg, poor quality, short duration, insomnia), and endogenous pain modulation (EPM) in healthy and clinical populations. Our search yielded 6,151 references, and 37 studies met the eligibility criteria. ⋯ Qualitatively, we found a frequent association between reduced sleep quality and impaired pain inhibition. However, quantitatively such an association was not corroborated. Sex-specific effects were observed, with females presenting sleep-related impaired pain inhibition but not males.
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Randomized Controlled Trial
Exploring HD-tDCS effect on μ-opioid receptor and pain sensitivity in temporomandibular disorder: A pilot randomized clinical trial study.
This study explored the association between experimentally-induced pain sensitivity and µ-opioid receptor (μOR) availability in patients with temporomandibular disorder (TMD) and further investigated any changes in the pain and μOR availability following high-definition transcranial direct current stimulation (HD-tDCS) over the primary motor cortex (M1) with pilot randomized clinical trials. Seven patients with TMD completed either active (n = 3) or sham treatment (n = 4) for 10 daily sessions and underwent positron emission tomography (PET) scans with [11C]carfentanil, a selective μOR agonist, a week before and after treatment. PET imaging consisted of an early resting and late phase with the sustained masseteric pain challenge by computer-controlled injection of 5% hypertonic saline. ⋯ TRIAL REGISTRATION: ClinicalTrial.gov (NCT03724032) PERSPECTIVE: This study links pain sensitivity and µ-opioid receptors in patients with TMD. HD-tDCS over M1 improved µOR availability, which was associated with reduced pain sensitivity. Implications for TMD pain management are promising, but larger clinical trials are essential for validation.
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The neurobiological underpinnings of gender differences in pain perception, and how these differences may be modified by age, are incompletely understood, placing patients at risk of suboptimal pain management. Using functional magnetic resonance imaging, we examined brain responses in the descending pain modulatory system (DPMS, specifically, dorsolateral prefrontal cortex, anterior cingulate cortex, insula, hypothalamus, amygdala, and periaqueductal gray, during an evoked pain task. We investigated the interaction of age and gender in our sample of healthy adults (27 females, 32 males, 30-86 years) on DPMS response. ⋯ Our results indicate that differences in DPMS responses may explain some gender differences in pain perception and that this effect may change across the adult lifespan. PERSPECTIVE: Gender differences in pain have been well-documented but the brain mechanisms for these differences are still unclear. This article describes potential differences in brain functioning during different levels of pain that could explain differences in pain responses between men and women across the adult lifespan.