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Diabetic sensorimotor peripheral neuropathy (DSPN) is a serious complication of diabetes mellitus and is associated with increased mortality, lower-limb amputations and distressing painful neuropathic symptoms (painful DSPN). Our understanding of the pathophysiology of the disease has largely been derived from animal models, which have identified key potential mechanisms. However, effective therapies in preclinical models have not translated into clinical trials and we have no universally accepted disease-modifying treatments. Moreover, the condition is generally diagnosed late when irreversible nerve damage has already taken place. Innovative point-of-care devices have great potential to enable the early diagnosis of DSPN when the condition might be more amenable to treatment. The management of painful DSPN remains less than optimal; however, studies suggest that a mechanism-based approach might offer an enhanced benefit in certain pain phenotypes. The management of patients with DSPN involves the control of individualized cardiometabolic targets, a multidisciplinary approach aimed at the prevention and management of foot complications, and the timely diagnosis and management of neuropathic pain. Here, we discuss the latest advances in the mechanisms of DSPN and painful DSPN, originating both from the periphery and the central nervous system, as well as the emerging diagnostics and treatments.
Learn More >Trials of Cognitive Therapy (CT), Mindfulness-Based Stress Reduction (MBSR), and Behavior Therapy (BT) suggest that all three treatments produce reductions in pain and improvements in physical function, mood and sleep disturbance in people with chronic pain conditions. Fewer studies have compared the relative efficacies of these treatments. In this randomized controlled study, we compared CT, MBSR, BT and treatment as usual (TAU) in a sample of people with chronic low back pain (N = 521). Eight individual sessions were administered with weekly assessments of outcomes. Consistent with prior work, we found that CT, MBSR, and BT produced similar pre- to post-treatment effects on all outcomes and revealed similar levels of maintenance of treatment gains at 6-month follow-up. All three active treatments produced greater improvements than TAU. Weekly assessments allowed us to assess rates of change; i.e., how quickly a given treatment produced significant differences, compared to TAU, on a given outcome. The three treatments differed significantly from TAU on average by session 6, and this rate of treatment effect was consistent across all treatments. Results suggest the possibility that the specific techniques included in CT, MBSR, and BT may be less important for producing benefits than people participating in any techniques rooted in these evidence-based psychosocial treatments for chronic pain.
Learn More >Pain can be considered as a signal of "bodily error": Errors put organisms at danger and activate behavioral defensive systems. If the error is of physical nature, pain is the warning signal that motivates protective action such as avoidance behavior to safeguard our body's integrity. Interestingly, an important component of neural error processing, the error-related negativity (ERN), has been found to be related to avoidance in anxiety disorders. The present study is the first to extend these findings to pain and investigate the relationship between ERN and pain-related avoidance behavior. It was hypothesized that individuals with larger ERN amplitudes would show more pain-related avoidance behavior and would be more persistent in their avoidance despite changes in the environment. Fifty-three healthy individuals performed the Eriksen Flanker task during which their brain activity upon correct and erroneous motor responses was recorded by means of high-density electroencephalography. Avoidance behavior was assessed with an arm-reaching task using the HapticMaster robot arm. Results showed that, in contrast to our hypothesis, avoidance was not related to ERN amplitudes. Surprisingly, persons with elevated ERN amplitudes showed low levels of avoidance specifically during early acquisition trials. In contrast to earlier findings in anxiety disorders, individuals with elevated ERN amplitudes did not engage in more pain-related avoidance behavior. In fact, the opposite pattern was found at the start of acquisition: individuals with higher compared to lower ERN amplitudes were slower in learning to avoid pain. Replications and future studies on the relationship between ERN and avoidance behavior are needed.
Learn More >Nociplastic pain is the semantic term suggested by the international community of pain researchers to describe a third category of pain that is mechanistically distinct from nociceptive pain, which is caused by ongoing inflammation and damage of tissues, and neuropathic pain, which is caused by nerve damage. The mechanisms that underlie this type of pain are not entirely understood, but it is thought that augmented CNS pain and sensory processing and altered pain modulation play prominent roles. The symptoms observed in nociplastic pain include multifocal pain that is more widespread or intense, or both, than would be expected given the amount of identifiable tissue or nerve damage, as well as other CNS-derived symptoms, such as fatigue, sleep, memory, and mood problems. This type of pain can occur in isolation, as often occurs in conditions such as fibromyalgia or tension-type headache, or as part of a mixed-pain state in combination with ongoing nociceptive or neuropathic pain, as might occur in chronic low back pain. It is important to recognise this type of pain, since it will respond to different therapies than nociceptive pain, with a decreased responsiveness to peripherally directed therapies such as anti-inflammatory drugs and opioids, surgery, or injections.
Learn More >Neuromodulation is an expanding area of pain medicine that incorporates an array of non-invasive, minimally invasive, and surgical electrical therapies. In this Series paper, we focus on spinal cord stimulation (SCS) therapies discussed within the framework of other invasive, minimally invasive, and non-invasive neuromodulation therapies. These therapies include deep brain and motor cortex stimulation, peripheral nerve stimulation, and the non-invasive treatments of repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and transcutaneous electrical nerve stimulation. SCS methods with electrical variables that differ from traditional SCS have been approved. Although methods devoid of paraesthesias (eg, high frequency) should theoretically allow for placebo-controlled trials, few have been done. There is low-to-moderate quality evidence that SCS is superior to reoperation or conventional medical management for failed back surgery syndrome, and conflicting evidence as to the superiority of traditional SCS over sham stimulation or between different SCS modalities. Peripheral nerve stimulation technologies have also undergone rapid development and become less invasive, including many that are placed percutaneously. There is low-to-moderate quality evidence that peripheral nerve stimulation is effective for neuropathic pain in an extremity, low quality evidence that it is effective for back pain with or without leg pain, and conflicting evidence that it can prevent migraines. In the USA and many areas in Europe, deep brain and motor cortex stimulation are not approved for chronic pain, but are used off-label for refractory cases. Overall, there is mixed evidence supporting brain stimulation, with most sham-controlled trials yielding negative findings. Regarding non-invasive modalities, there is moderate quality evidence that repetitive transcranial magnetic stimulation does not provide meaningful benefit for chronic pain in general, but conflicting evidence regarding pain relief for neuropathic pain and headaches. For transcranial direct current stimulation, there is low-quality evidence supporting its benefit for chronic pain, but conflicting evidence regarding a small treatment effect for neuropathic pain and headaches. For transcutaneous electrical nerve stimulation, there is low-quality evidence that it is superior to sham or no treatment for neuropathic pain, but conflicting evidence for non-neuropathic pain. Future research should focus on better evaluating the short-term and long-term effectiveness of all neuromodulation modalities and whether they decrease health-care use, and on refining selection criteria and treatment variables.
Learn More >Chronic pain exerts an enormous personal and economic burden, affecting more than 30% of people worldwide according to some studies. Unlike acute pain, which carries survival value, chronic pain might be best considered to be a disease, with treatment (eg, to be active despite the pain) and psychological (eg, pain acceptance and optimism as goals) implications. Pain can be categorised as nociceptive (from tissue injury), neuropathic (from nerve injury), or nociplastic (from a sensitised nervous system), all of which affect work-up and treatment decisions at every level; however, in practice there is considerable overlap in the different types of pain mechanisms within and between patients, so many experts consider pain classification as a continuum. The biopsychosocial model of pain presents physical symptoms as the denouement of a dynamic interaction between biological, psychological, and social factors. Although it is widely known that pain can cause psychological distress and sleep problems, many medical practitioners do not realise that these associations are bidirectional. While predisposing factors and consequences of chronic pain are well known, the flipside is that factors promoting resilience, such as emotional support systems and good health, can promote healing and reduce pain chronification. Quality of life indicators and neuroplastic changes might also be reversible with adequate pain management. Clinical trials and guidelines typically recommend a personalised multimodal, interdisciplinary treatment approach, which might include pharmacotherapy, psychotherapy, integrative treatments, and invasive procedures.
Learn More >The novel coronavirus disease (COVID-19) has caused prolonged disruptions in daily life for many communities. Little is known about the impact of the COVID-19 pandemic on the health and well-being of youth with chronic pain and their families. We conducted a longitudinal, mixed-methods study to characterize early adaptation to the COVID-19 pandemic among 250 families of youth (ages 12-21 years) diagnosed with chronic headache (64%) or other chronic pain conditions (36%) and to determine whether direct exposures to COVID-19 and secondary economic stress modified symptom trajectories. Youth and parents reported on pain interference, anxiety, depression, and insomnia symptoms at 4 waves of data collection from April 2020 to July 2020. We also collected qualitative data on the impact of the pandemic on the youth's pain problem. Nearly half of our sample (49.6%) experienced direct exposures to COVID-19. Secondary economic stress was also common, affecting 44.4% of families. Symptom trajectories for pain, insomnia, depression, and anxiety remained stable or improved for most participants, indicating adaptive adjustment. However, overall symptom burden was high with persistent and clinically elevated depression, anxiety, and insomnia symptoms common among youth and parents. Direct exposures to COVID-19 did not modify symptom trajectories. However, youth pain interference and parent insomnia worsened in families who experienced secondary economic stress. Qualitative data revealed perceived benefits and harms from school closures on the youth's pain problem. Our findings of high symptom burden suggest that pediatric pain clinicians should offer distance assessment and treatment (eg, through telemedicine) to avoid pandemic-related disruptions in pain care.
Learn More >Poor access to pediatric chronic pain care is a longstanding concern. The COVID-19 pandemic has necessitated virtual care delivery at an unprecedented pace and scale. We conducted a scoping review to create an interactive Evidence and Gap Map (EGM) of virtual care solutions across a stepped care continuum (i.e., from self-directed to specialist care) for youth with chronic pain and their families. Review methodology was co-designed with 8 youth with chronic pain and 7 parents/caregivers. Data sources included peer-reviewed scientific literature, grey literature (app stores, websites), and a call for innovations. Records were independently coded and assessed for quality. Overall, 185 records were included (105 scientific records, 56 apps, 16 websites, and 8 innovations). Most virtual care solutions were applicable across pediatric chronic pain diagnoses, with the greatest proportion at lower levels of stepped care (i.e., >100 self-guided apps and websites). Virtual delivery of psychological strategies was common. Evidence gaps were noted at higher levels of stepped care (i.e., requiring more resource and health professional involvement), integration with health records, communication with health professionals, web accessibility, and content addressing social/family support, medications, school, substance use, sleep, diet, and acute pain flares or crises. EGMs are a novel visual knowledge synthesis tool that enable rapid evidence-informed decision-making by patients and families, health professionals, and policymakers. This EGM identified high quality virtual care solutions for immediate scale and spread, and areas with no evidence in need of prioritization. Virtual care should address priorities identified by youth with chronic pain and their families.
Learn More >Migraine involves brain hypersensitivity with episodic dysfunction triggered by behavioral or physiological stressors. During an acute migraine attack the trigeminal nerve is activated (peripheral sensitization). This leads to central sensitization with activation of the central pathways including the trigeminal nucleus caudalis, the trigemino-thalamic tract, and the thalamus. In episodic migraine the sensitization process ends with the individual act, but with chronic migraine central sensitization may continue interictally. Increased allostatic load, the consequence of chronic, repeated exposure to stressors, leads to central sensitization, lowering the threshold for future neuronal activation (hypervigilance). Ostensibly innocuous stressors are then sufficient to trigger an attack. Medications that reduce sensitization may help patients who are hypervigilant and help to balance allostatic load. Acute treatments and drugs for migraine prevention have traditionally been used to reduce attack duration and frequency. However, since many patients do not fully respond, an unmet treatment need remains. Calcitonin gene-related peptide (CGRP) is a vasoactive neuropeptide involved in nociception and in the sensitization of peripheral and central neurons of the trigeminovascular system, which is implicated in migraine pathophysiology. Elevated CGRP levels are associated with dysregulated signaling in the trigeminovascular system, leading to maladaptive responses to behavioral or physiological stressors. CGRP may, therefore, play a key role in the underlying pathophysiology of migraine. Increased understanding of the role of CGRP in migraine led to the development of small-molecule antagonists (gepants) and monoclonal antibodies (mAbs) that target either CGRP or the receptor (CGRP-R) to restore homeostasis, reducing the frequency, duration, and severity of attacks. In clinical trials, US Food and Drug Administration-approved anti-CGRP-R/CGRP mAbs were well tolerated and effective as preventive migraine treatments. Here, we explore the role of CGRP in migraine pathophysiology and the use of gepants or mAbs to suppress CGRP-R signaling via inhibition of the CGRP ligand or receptor.
Learn More >Opioids are potent analgesics, but their pain-relieving effects diminish with repeated use. The reduction in analgesic potency is a hallmark of opioid analgesic tolerance, which hampers opioid pain therapy. In the central nervous system, opioid analgesia is critically modulated by adenosine, a purine nucleoside implicated in the beneficial and detrimental actions of opioid medications. Here, we focus on the A adenosine receptor (A AR) in opioid analgesic tolerance. Intrathecal administration of the A AR agonist MRS5698 with daily systemic morphine in male rats attenuated the reduction in morphine antinociception over 7 days. In rats with established morphine tolerance, intrathecal MRS5698 partially restored the antinociceptive effects of morphine. However, when MRS5698 was discontinued, these animals displayed a reduced antinociceptive response to morphine. Our results suggest that MRS5698 acutely and transiently potentiates morphine antinociception in tolerant rats. By contrast, in morphine-naïve rats MRS5698 treatment did not impact thermal nociceptive threshold or affect antinociceptive response to a single injection of morphine. Furthermore, we found that morphine-induced adenosine release in cerebrospinal fluid was blunted in tolerant animals, but total spinal A AR expression was not affected. Collectively, our findings indicate that spinal A AR activation acutely potentiates morphine antinociception in the opioid tolerant state.
Learn More >Despite the biopsychosocial underpinnings of chronic noncancer pain, relatively little is known about the contribution of psychosocial factors to chronic cancer pain. The authors aimed to characterize associations between biopsychosocial factors and pain and opioid use among individuals with chronic pain and cancer.
Learn More >Mechanical hyperalgesia and allodynia incidence varies considerably among neuropathic pain patients. This study explored whether sensory or psychological factors associate with mechanical hyperalgesia and brush allodynia in a human experimental model.
Learn More >Chronic pain affects 50 million Americans and is often treated with non-pharmacologic approaches like physical therapy. Developing a no-show prediction model for individuals seeking physical therapy care for musculoskeletal conditions has several benefits including enhancement of workforce efficiency without growing the existing provider pool, delivering guideline adherent care, and identifying those that may benefit from telehealth. The objective of this paper was to quantify the national prevalence of no-shows for patients seeking physical therapy care and to identify individual and organizational factors predicting whether a patient will be a no-show when seeking physical therapy care.
Learn More >To evaluate whether the 15-day threshold of headache days per month adequately reflects substantial differences in disability across the full spectrum of migraine.
Learn More >To investigate whether illness perceptions, measured with the Brief Illness Perception Questionnaire, are an independent predictor of chronic low back pain and pain-related disability at 12 weeks.
Learn More >This study is the first comprehensive characterisation of the pain phenotype after fracture using both evoked and naturalistic behaviours in adult male and ovariectomised female mice. It also shows that an anti-nerve growth factor (NGF) therapy could be considered to reduce pain after fracture surgery.
Learn More >In our previous studies, we developed a series of mixed MOR/DOR agonists that are enkephalin-like tetrapeptide analogs with an N-phenyl-N-piperidin-4-ylpropionamide (Ppp) moiety at the C-terminus. Further SAR study on the analogs, initiated by the findings from off-target screening, resulted in the discovery of (, Dmt-DNle-Gly-Phe(-Cl)-Ppp), a multifunctional ligand with MOR/DOR agonist and KOR antagonist activity (GTPγS assay: IC = 52 nM, I = 122% cf. IC = 59 nM, I = 100% for naloxone) with nanomolar range of binding affinity ( = 1.3 nM cf. = 2.4 nM for salvinorin A). Based on its unique biological profile, is considered to possess high therapeutic potential for the treatment of chronic pain by modulating pathological KOR activation while retaining analgesic efficacy attributed to its MOR/DOR agonist activity.
Learn More >Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors that exist in three isoforms: PPARα, PPARβ/δ and PPARγ. Studies suggest that the PPAR signalling system may modulate pain, anxiety and cognition. The aim of the present study was to investigate whether endogenous signalling via PPARs differentially modulates innate anxiety responses and mnemonic function in the presence and absence of inflammatory pain. We examined the effects of intraperitoneal administration of GW6471 (PPARα antagonist), GSK0660 (PPARβ/δ antagonist), GW9662 (PPARγ antagonist), and -palmitoylethanolamide (PEA) on rat behaviour in the elevated plus maze (EPM), open field (OF), light-dark box (LDB), and novel object recognition (NOR) tests in the presence or absence of chronic inflammatory pain. Complete Freund's Adjuvant (CFA)-injected rats exhibited impaired recognition and spatial mnemonic performance in the NOR test and pharmacological blockade of PPARα further impaired spatial memory in CFA-treated rats. -oleoylethanolamide (OEA) levels were higher in the dorsal hippocampus in CFA-injected animals compared to their counterparts. The results suggest a modulatory effect of CFA-induced chronic inflammatory pain on cognitive processing, but not on innate anxiety-related responses. Increased OEA-PPARα signalling may act as a compensatory mechanism to preserve spatial memory function following CFA injection.
Learn More >Complex regional pain syndrome (CRPS) is a chronic pain condition characterized by inflammation and debilitating pain. CRPS patients with pain refractory to more conventional analgesics can be treated with subanesthetic doses of ketamine. Our previous studies found that poor responders to ketamine had a 22-fold downregulation of the miRNA hsa-miR-605 in blood prior to ketamine treatment. Hence, we sought to investigate the functional significance of miR-605 downregulation and its impact on target gene expression, as investigating target mRNAs of differentially expressed miRNAs can provide important insights on aberrant gene expression that may contribute to disease etiology. Using a bioinformatics prediction, we identified that miR-605 can target the proinflammatory chemokine CXCL5, which plays a role in leukocyte recruitment and activation. We hypothesized that downregulation of miR-605 in poor responders to ketamine could increase CXCL5 expression and thereby contribute to inflammation in these patients. We confirmed that miR-605 regulates CXCL5 by using a miRNA mimic and inhibitor in human primary endothelial cells. Inhibition of miR-605 increased CXCL5 secretion and migration of human monocytic cells, thereby demonstrating a functional impact of miR-605 on chemotaxis. Additionally, CXCL5 mRNA was upregulated in whole blood from poor responders to ketamine, and CXCL5 protein was increased in plasma from CRPS patients. Thus, our studies suggest that miR-605 regulation of CXCL5 can regulate inflammation.
Learn More >The cold pressor test (CPT) is widely implemented and offers a simple, experimental acute pain model utilizing cold pain. Previous trials have frequently paired the CPT with opioids in order to investigate the mechanisms underlying pharmacological analgesia, due to their known analgesic efficacy. However, opioid side effects may lead to unblinding and raise concerns about the safety of the experimental setting. Despite the established clinical efficacy of dipyrone (metamizole), its efficacy, tolerability, and safety in cold pressor pain has not been systematically addressed to date. This pooled analysis included data of 260 healthy volunteers from three randomized, placebo-controlled, double-blind substudies using the CPT following a pre-test-post-test-design. These substudies allow for comparing a single dose of 800 mg dipyrone with two different doses of the opioid tilidine/naloxone (50/4 mg and 100/8 mg, respectively). Outcomes included pain intensity ratings, pain tolerance, medication-attributed side effects, as well as changes of blood pressure and heart rate. We demonstrate that both opioid doses and dipyrone had a comparable, significant analgesic effect on cold pressor pain. However, dipyrone was associated with significantly less self-reported adverse effects and these were not significantly different from those under placebo. These results indicate that the combination of dipyrone and the CPT provides a safe, tolerable, and effective experimental model for the study of pharmacological analgesia. In combination with a CPT, dipyrone may be useful as a positive control, or baseline medication for the study of analgesic modulation.
Learn More >The gut-brain axis (GBA) is broadly accepted to describe the bidirectional circuit that links the gastrointestinal tract with the central nervous system (CNS). Interest in the GBA has grown dramatically over past two decades along with advances in our understanding of the importance of the axis in the pathophysiology of numerous common clinical disorders including mood disorders, neurodegenerative disease, diabetes mellitus, non-alcohol fatty liver disease (NAFLD) and enhanced abdominal pain (visceral hyperalgesia). Paralleling the growing interest in the GBA, there have been seminal developments in our understanding of how environmental factors such as psychological stress and other extrinsic factors alter gene expression, primarily via epigenomic regulatory mechanisms. This process has been driven by advances in next-generation multi-omics methods and bioinformatics. Recent reviews address various components of GBA, but the role of epigenomic regulatory pathways in chronic stress-associated visceral hyperalgesia in relevant regions of the GBA including the amygdala, spinal cord, primary afferent (nociceptive) neurons, and the intestinal barrier has not been addressed. Rapidly developing evidence suggests that intestinal epithelial barrier dysfunction and microbial dysbiosis play a potentially significant role in chronic stress-associated visceral hyperalgesia in nociceptive neurons innervating the lower intestine via downregulation in intestinal epithelial cell tight junction protein expression and increase in paracellular permeability. These observations support an important role for the regulatory epigenome in the development of future diagnostics and therapeutic interventions in clinical disorders affecting the GBA.
Learn More >Acceptance and commitment therapy (ACT), based in the psychological flexibility model, may benefit people with chronic abdominal pain. The current study preliminarily investigates associations between psychological flexibility processes and daily general, social and emotional functioning in chronic abdominal pain.
Learn More >Psychological variables contribute to pain- and injury-related outcomes. We examined the hypothesis that anatomical spread and intensity of persistent pain relate to anxiety-related variables: generalised anxiety, fear of pain and pain catastrophising.
Learn More >Little is known about the consequences of the opioid epidemic on people living with chronic non-cancer pain (CNCP). This study examined this issue in people who lived in the most impacted province by opioid overdoses in Canada (British Columbia (BC)) or one of the least impacted (Quebec (QC)), and examined the factors associated with opioid use.
Learn More >The current treatments of primary musculoskeletal low back pain (LBP) have a low to moderate efficacy, which might be improved by looking at the contribution of placebo effects. However, the size of true placebo effects in LBP is unknown. Therefore, a systematic review and meta-analysis were executed of randomized controlled trials investigating placebo effects in LBP.
Learn More >Both spinal tumor necrosis factor (TNF) and interleukin-6 (IL-6) contribute to the development of "mechanical" spinal hyperexcitability in inflammatory pain states. Recently we found that spinal sensitization by TNF was significantly reduced by blockade of spinal IL-6 signaling suggesting that IL-6 signaling is involved in spinal TNF effects. Here we explored whether spinal interleukin-1β (IL-1β), also implicated in inflammatory pain, induces "mechanical" spinal hyperexcitability, and whether spinal IL-1β effects are related to TNF and IL-6 effects. We recorded the responses of spinal cord neurons to mechanical stimulation of the knee joint in vivo and used cellular approaches on microglial and astroglial cell lines to identify interactions of IL-1β, TNF, and IL-6. Spinal application of IL-1β in anaesthetized rats modestly enhanced responses of spinal cord neurons to innocuous and noxious mechanical joint stimulation. This effect was blocked by minocycline indicating microglia involvement, and significantly attenuated by interfering with IL-6 signaling. In the BV2 microglial cell line, IL-1β, like TNF, enhanced the release of soluble IL-6 receptor, necessary for spinal IL-6 actions. Different to TNF, IL-1β caused SNB-19 astrocytes to release interleukin-11. The generation of "mechanical" spinal hyperexcitability by IL-1β was more pronounced upon spinal TNF neutralization with etanercept, suggesting that concomitant TNF limits IL-1β effects. In BV2 cells, TNF stimulated the release of IL-1Ra, an endogenous IL-1β antagonist. Thus spinal IL-1β has the potential to induce spinal hyperexcitability sharing with TNF dependency on IL-6 signaling, but TNF also limited IL-1β effects explaining the modest effect of IL-1β.
Learn More >A 2019 review concluded that spinal manipulative therapy (SMT) results in similar benefit compared to other interventions for chronic low back pain (LBP). Compared to traditional aggregate analyses individual participant data (IPD) meta-analyses allows for a more precise estimate of the treatment effect.
Learn More >Altered attentional processing of pain-associated stimuli-which might take the form of either avoidance or enhanced vigilance-is thought to be implicated in the development and maintenance of chronic pain. In contrast to reaction time tasks like the dot probe, eye tracking allows for tracking the time course of visual attention and thus differentiating early and late attentional processes. Our study aimed at investigating visual attention to emotional faces in patients with chronic musculoskeletal pain (N = 20) and matched pain-free controls (N = 20). Emotional faces (pain, angry, happy) were presented in pairs with a neutral face for 2000 ms each. Three parameters were determined: First fixation probabilities, fixation durations (overall and divided in four 500 ms intervals) and a fixation bias score as the relative fixation duration of emotional faces compared to neutral faces. There were no group differences in any of the parameters. First fixation probabilities were lower for pain faces than for angry faces. Overall, we found longer fixation duration on emotional compared to neutral faces ('emotionality bias'), which is in accord with previous research. However, significant longer fixation duration compared to the neutral face was detected only for happy and angry but not for pain faces. In addition, fixation durations as well as bias scores yielded evidence for vigilant-avoidant processing of pain faces in both groups. These results suggest that attentional bias towards pain-associated stimuli might not generally differentiate between healthy individuals and chronic pain patients. Exaggerated attentional bias in patients might occur only under specific circumstances, e.g., towards stimulus material specifically relating to the specific pain of the patients under study or under high emotional distress.
Learn More >Chronic pain is a major healthcare issue that often requires an interdisciplinary treatment approach. Defining relevant treatment goals is one of the crucial steps in creating successful rehabilitation schemes. Therefore, the first aim is to explore goals that patients suffering from chronic pain aim to achieve. The second aim is to translate those goals into measurable functional outcome variables which can be used to measure treatment success.
Learn More >Pain catastrophizing underpins several psychosocial theories of pain, but there is limited evidence to support the proposal that changes in pain catastrophizing cause changes in pain. Results from mediation analyses have conflicting results, and one reason for these might be the timing of the assessment of pain catastrophizing. This study aimed to test the effect of the timing of pain catastrophizing on pain intensity.
Learn More >Atopic dermatitis (AD) often presents more severely in African Americans (AAs) and with greater involvement of extensor areas. To investigate immune signatures of AD in AAs with moderate to severe pruritus, lesional and non-lesional punch biopsies were taken from AA patients along with age-, race-, and sex-matched controls. Histology of lesional skin showed psoriasiform dermatitis and spongiotic dermatitis, suggesting both Th2 and Th17 activity. Gene Set Variation Analysis showed upregulation of Th2 and Th17 pathways in both lesional versus non-lesional and lesional versus control (p < 0.01), while Th1 and Th22 upregulation were observed in lesional versus control (p < 0.05). Evidence for a broad immune signature also was supported by upregulated Th1 and Th22 pathways, and clinically may represent greater severity of AD in AA. Furthermore, population-level analysis of data from TriNetX, a global federated health research network, revealed that AA AD patients had higher values for CRP, ferritin, and blood eosinophils compared to age-, sex-, and race-matched controls as well as white AD patients, suggesting broad systemic inflammation. Therefore, AA AD patients may feature broader immune activation than previously thought and may derive benefit from systemic immunomodulating therapies that modulate key drivers of multiple immune pathways.
Learn More >Functional abdominal pain disorders (FAPDs) are common in childhood, impacting quality of life and school attendance. There are several compounds available for the treatment of pediatric FAPDs, but their efficacy and safety are unclear because of a lack of head-to-head randomized controlled trials (RCTs).
Learn More >A national clinical registry was established in the Netherlands containing data directly sampled from electronic health record systems of physical therapists (PTs). This registry aims to evaluate the potential of patient reported outcome measures (PROMs) to develop quality indicators (QIs) in physical therapy care.
Learn More >Social deprivation is associated with a higher prevalence of chronic pain in children and an under-representation in specialist paediatric chronic pain programs. Our primary objective was to determine if there was a relationship between social deprivation and paediatric chronic pain referrals in Ireland. Secondary objectives included analysing for differences between deprivation groups in pain characteristics and function that are recorded at first clinic visit.
Learn More >Social relationships are important for pain management among individuals with HIV, but the impact of daily social contact on pain responses in real-time, real-world settings has never been specifically examined.
Learn More >New daily persistent headache (NDPH) is a primary headache disorder characterized by an intractable, daily, and unremitting headache lasting for at least 3 months. Currently, there are limited studies in the pediatric population describing the characteristics of NDPH.
Learn More >The development of several drugs that target the calcitonin gene-related peptide (CGRP) system has been a major breakthrough in the pharmacological management of migraine. These are divided into two major classes: antibodies which bind to the CGRP peptide, preventing it from activating CGRP receptors and receptor antagonists. Within the receptor antagonist class, there are two mechanisms of action: small molecule receptor antagonists and an antibody antagonist. This mini-review considers the pharmacology of these receptor targeted antagonist drugs at the CGRP receptor and closely-related AMY receptor, at which CGRP may also act. The antagonists are most potent at the CGRP receptor but can also show antagonism of the AMY receptor. However, important data are missing and selectivity parameters cannot be provided for all antagonists. The clinical implications of AMY receptor antagonism are unknown but we urge consideration of this receptor as a potential contributing factor to CGRP and antagonist drug actions.
Learn More >Growth differentiation factor 15 (GDF-15) is a member of the transforming growth factor-β superfamily. It is widely distributed in the central and peripheral nervous systems. Whether and how GDF-15 modulates nociceptive signaling remains unclear. Behaviorally, we found that peripheral GDF-15 significantly elevated nociceptive response thresholds to mechanical and thermal stimuli in naïve and arthritic rats. Electrophysiologically, we demonstrated that GDF-15 decreased the excitability of small-diameter dorsal root ganglia (DRG) neurons. Furthermore, GDF-15 concentration-dependently suppressed tetrodotoxin-resistant sodium channel Nav1.8 currents, and shifted the steady-state inactivation curves of Nav1.8 in a hyperpolarizing direction. GDF-15 also reduced window currents and slowed down the recovery rate of Nav1.8 channels, suggesting that GDF-15 accelerated inactivation and slowed recovery of the channel. Immunohistochemistry results showed that activin receptor-like kinase-2 (ALK2) was widely expressed in DRG medium- and small-diameter neurons, and some of them were Nav1.8-positive. Blockade of ALK2 prevented the GDF-15-induced inhibition of Nav1.8 currents and nociceptive behaviors. Inhibition of PKA and ERK, but not PKC, blocked the inhibitory effect of GDF-15 on Nav1.8 currents. These results suggest a functional link between GDF-15 and Nav1.8 in DRG neurons via ALK2 receptors and PKA associated with MEK/ERK, which mediate the peripheral analgesia of GDF-15.
Learn More >Chronic pain affects mental and physical health and alters brain structure and function. Interventions that reduce chronic pain are also associated with changes in the brain. A number of non-invasive strategies can promote improved learning and memory and increase neuroplasticity in older adults. Intermittent fasting and glucose administration represent two such strategies with the potential to optimize the neurobiological environment to increase responsiveness to recognized pain treatments. The purpose of the pilot study was to test the feasibility and acceptability of intermittent fasting and glucose administration paired with a recognized pain treatment activity, relaxation and guided imagery. A total of 32 adults (44% W, 56% M), 50 to 85 years of age, with chronic knee pain for three months or greater participated in the study. Four sessions were completed over an approximate two-week period. Findings indicate the ability to recruit, randomize, and retain participants in the protocol. The procedures and measures were reasonable and completed without incident. Participant adherence was high and exit interview feedback positive. In summary, the pilot study was feasible and acceptable, providing the evidence necessary to move forward with a larger clinical trial.
Learn More >Motor variability is an important feature when performing repetitive movement, and in asymptomatic people functional tasks are typically performed with variable motor patterns. However, in the presence of chronic non-specific low back pain (LBP), people often present with different motor control strategies than those without pain. Movement variability has been assessed using a wide range of variables, including kinetic and kinematic components of motion. This has resulted in a wide range of findings reported in the literature and some contradicting results. Therefore, the aim of this systematic review is to investigate whether the amount and structure of motor variability are altered in people with chronic non-specific LBP, during both repetitive non-functional and functional tasks.
Learn More >While against recommendations, long-term opioid therapy (LTOT) for chronic pain is common. This study aimed to describe the prevalence of opioid prescriptions and to study the association of patient characteristics (demographics, pain characteristics, anxiety, depressive symptoms and pain coping) with future LTOT. The sample included = 1334 chronic musculoskeletal pain patients, aged 18-65, who were assessed for Interdisciplinary Multimodal Pain Rehabilitation (IMMR) in Swedish specialist rehabilitation. Prescriptions were tracked across a two-year target period after assessment. In total, 9100 opioid prescriptions were prescribed to 55% of the sample (M = 6, IQR = 14). Prediction of LTOT was analyzed separately for those who did (24%) and did not (76%) receive IMMR. The odds of receiving opioids was similar for these subsamples, after controlling for differences in baseline characteristics. In both samples, there were significant associations between patient characteristics and future opioid prescriptions. Dysfunctional pain coping was a unique predictor of LTOT in those who received IMMR while pain intensity and depressive symptoms were unique predictors in those who did not receive IMMR. The results underscore that opioid treatment is common among patients in chronic pain rehabilitation and relates to pain and psychological factors. Understanding in detail why these factors relate to opioid prescription patterns is an important future study area as it is a prerequisite for better management and fundamental for preventing overuse.
Learn More >Pediatric chronic pain is a challenging problem for children and their families, although it is still under-recognized and under-treated. The aim of this study was to investigate whether a pain neuroscience education program for children (PNE4Kids) delivered to healthy children aged 8 to 12 years old and attended by their parents would result in improved parental knowledge about pain neurophysiology, decreased parental pain catastrophizing about their own pain and their children's, decreased parental pain vigilance and awareness, and decreased fear of pain in children. Twenty-seven healthy child-parent dyads received a 45 min PNE4Kids session. Demographic data were collected, and the Neurophysiology of Pain Questionnaire (NPQ), Fear of Pain Questionnaire-Parent Proxy Report (FOPQ-P), Pain Catastrophizing Scale (PCS), Pain Catastrophizing Scale for Parents (PCS-P), and the Pain Vigilance and Awareness Questionnaire (PVAQ) were completed by the parents before and after the PNE4Kids session. Twenty-six dyads completed study participation. In response to the PNE4Kids session, significant short-term (1 week) improvements were shown in the NPQ ( < 0.001) and the FOPQ-P ( = 0.002). Parents' level of pain knowledge and children's fear of pain, reported by their parents, improved after a 45 min PNE4Kids session. Thus, PNE4Kids should likewise be further investigated in healthy child-parent dyads as it might be useful to target parental and children's pain cognitions at a young age.
Learn More >Chronic pruritus (itch lasting ≥6 weeks) is a bothersome chief complaint that may present in a broad variety of diseases. Most itch-causing diagnoses fit into 1 of 5 categories (inflammatory, secondary to systemic disease, neuropathic, chronic pruritus of undetermined origin, and psychogenic itch) and this broad differential can be narrowed using key findings in the history and physical. In this article, we discuss which key findings are most pertinent for narrowing this differential and guiding further workup and treatment, as well as how to treat many itchy conditions.
Learn More >Low back pain (LBP) is the leading cause of disability and a global public health concern. Studies indicate that pain self-efficacy is associated with the development of disability in chronic LBP (CLBP) patients. The Pain Self-Efficacy Questionnaire (PSEQ) is a commonly used questionnaire to assess pain self-efficacy in patients with CLBP. It is essential to examine the psychometric properties of the PSEQ in the population in which it is to be used. Thus, the aim of this study is to evaluate the reliability and smallest detectable change of the Danish version of the Pain Self-Efficacy Questionnaire (PSEQ-DK) in patients with CLBP before implementing it as an outcome measure in an inpatient rehabilitation context.
Learn More >The aim of this pilot study was to assess: (1) the feasibility and acceptability of a Mindfulness-Based Virtual Reality (MBVR) intervention among children and young adults with Inflammatory Bowel Disease (IBD), and (2) the preliminary efficacy of MBVR on key psychological (anxiety) and physical (pain) outcomes. Participants were 62 children to young adults with IBD (M = 15.6 years; 69.4% Crohn's disease; 58% male) recruited from an outpatient pediatric IBD clinic. Participants completed a baseline assessment, underwent the 6-min MBVR intervention, completed a post-intervention assessment and study satisfaction survey, and provided qualitative feedback. Results suggest strong feasibility and acceptability. Participants reported high levels of satisfaction with MBVR including high levels of enjoyment (M = 4.38; range 1-5) and relaxation (M = 4.35; range 1-5). Qualitative data revealed several key themes including participants interest in using MBVR in IBD medical settings (e.g., hospitalizations, IBD procedures, IBD treatments), as well as in their daily lives to support stress and symptom management. Preliminary analyses demonstrated improvements in anxiety ( = 4.79, = 0.001) and pain ( = 3.72, < 0.001) following MBVR. These findings provide initial support for the feasibility and acceptability of MBVR among children and young adults with IBD. Results also suggest MBVR may improve key IBD outcomes (e.g., anxiety, pain) and highlight the importance of conducting a randomized controlled trial and more rigorous research to determine intervention efficacy.
Learn More >Although microglia activation plays an important role in the development of nerve injury-induced neuropathic pain, the molecular mechanisms of spinal cord microglia activation in nerve injury are not completely understood. Recently, two injured sensory neuron-derived molecules, colony stimulating factor-1 (CSF-1) and GT1b, were proposed to trigger spinal cord microglia activation, yet their relationship and relative contribution to microglia activation have not been addressed. In the present study, the role of GT1b and CSF-1 in microglia activation and proliferation was characterized. GT1b stimulation upregulated proinflammatory mediators such as IL-1β, TNF-α, and NADPH oxidase 2 (Nox2), without microglia proliferation. Conversely, CSF-1 stimulation induced microglia proliferation with minimal proinflammatory gene induction. Notably, neither GT1b nor CSF-1 induced mechanical hypersensitivity in female mice; however, they induced similar microglial proliferation in both male and female mice. Taken together, our data indicate that injured sensory neuron-derived GT1b and CSF-1 activate spinal cord microglia in concert through distinct activation pathways.
Learn More >The main symptoms of fibromyalgia comprise diffuse pain, disability, depressive symptoms, catastrophizing, sleep disruption and fatigue, associated with dysfunction of the descending pain-modulating system (DPMS).
Learn More >The hallmark of sickle cell disease (SCD) is acute and chronic pain, and the pain dominates the clinical characteristics of SCD patients. Although pharmacological treatments of SCD targeting the disease mechanisms have been improved, many SCD patients suffer from pain. To overcome the pain of the disease, there have been renewed requirements to understand the novel molecular mechanisms of the pain in SCD.
Learn More >People with chronic pain often seek support from friends and family for everyday tasks. These individuals are termed informal caregivers. There remains uncertainty regarding the lived experiences of these people who care for individuals with chronic musculoskeletal pain. The aim of this article is to synthase the evidence on the lived experiences of informal caregivers providing care to people with chronic musculoskeletal pain.
Learn More >This article describes the development and initial evaluation of introducing a psychologist role within an adult inpatient pain service (IPS) in a large North West of England National Health Service (NHS) trust.
Learn More >Chronic pain has been widely recognized as a major public health problem that impacts multiple aspects of patient quality of life. Unfortunately, chronic pain is often resistant to conventional analgesics, which are further limited by their various side effects. New therapeutic strategies and targets are needed to better serve the millions of people suffering from this devastating disease. To this end, recent clinical and preclinical studies have implicated the epidermal growth factor receptor signaling pathway in chronic pain states. EGFR is one of four members of the ErbB family of receptor tyrosine kinases that have key roles in development and the progression of many cancers. EGFR functions by activating many intracellular signaling pathways following binding of various ligands to the receptor. Several of these signaling pathways, such as phosphatidylinositol 3-kinase, are known mediators of pain. EGFR inhibitors are known for their use as cancer therapeutics but given recent evidence in pilot clinical and preclinical investigations, may have clinical use for treating chronic pain. Here, we review the clinical and preclinical evidence implicating EGFR in pathological pain states and provide an overview of EGFR signaling highlighting how EGFR and its ligands drive pain hypersensitivity and interact with important pain pathways such as the opioid system.
Learn More >Disrupted cognition and chronic musculoskeletal pain (CMP) are prevalent experiences among Gulf War Veterans (GWV). A negative association between CMP and cognition (i.e., chronic pain-related cognitive interference) has been observed in some chronic pain populations but has not been evaluated in GWV. Additional research suggests that disrupted cognition in GWV with CMP may be exacerbated by stressing the nociceptive system. Therefore, we compared cognitive performance and related neural activity between CMP and healthy control (CO) GWV in the absence and presence of experimental pain.
Learn More >Patients with episodic migraine (EM) with a higher-frequency of migraine headache days (HFEM: 8-14 migraine headache days/month) have a greater disease burden and a higher risk of progressing to chronic migraine (CM) with associated acute treatment overuse versus those with low-frequency EM (LFEM: 4-7 migraine headache days/month). In this post hoc analysis, we assessed the proportions of patients who shifted from HFEM to LFEM and to very low-frequency EM (VLFEM: 0-3 migraine headache days/month) status following treatment with galcanezumab versus placebo.
Learn More >Endometriosis is a common condition associated with infertility that causes chronic pain in many, but not all, women. It is defined by the presence of endometrial-like tissue outside the uterus. Although the cause and natural history of the disorder remain uncertain, hormonal, neurological, and immunological factors are all implicated in the mechanisms contributing to development of symptoms. Because definitive diagnosis requires surgery, there is often a long diagnostic delay after onset of symptoms. Current interventions for endometriosis have limited efficacy and unacceptable side effects/risks and are associated with high rates of symptom recurrence. Here, we review recent advances in our understanding of the etiology of endometriosis, discuss current diagnostic and treatment strategies, highlight current clinical trials, and consider how recent results offer new avenues for the identification of endometriosis biomarkers and the development of effective non-surgical therapies that are fertility-sparing.
Learn More >Neonatal pain such as that experienced by infants in the neonatal intensive care unit is known to produce later-life dysfunction including heightened pain sensitivity and anxiety, although the mechanisms remain unclear. Both chronic pain and stress in adult organisms are known to influence the corticotropin-releasing factor (CRF) system in the Central Nucleus of the Amygdala, making this system a likely candidate for changes following neonatal trauma. To examine this, neonatal rats were subjected to daily pain, non-painful handling or left undisturbed for the first week of life. Beginning on postnatal day, 24 male and female rats were subjected to a 4-day fear conditioning and sensory testing protocol. Some subjects received intra-amygdalar administration of either Vehicle, the CRF receptor 1 (CRF) receptor antagonist Antalarmin, or the CRF receptor 2 (CRF) receptor antagonist Astressin 2B prior to fear conditioning and somatosensory testing, while others had tissue collected following fear conditioning and CRF expression in the CeA and BLA was assessed using fluorescent hybridization. CRF antagonism attenuated fear-induced hypersensitivity in neonatal pain and handled rats, while CRF antagonism produced a general antinociception. In addition, neonatal pain and handling produced a lateralized sex-dependent decrease in CRF expression, with males showing a diminished number of CRF-expressing cells in the right CeA and females showing a similar reduction in the number of CRF-expressing cells in the left BLA compared to undisturbed controls. These data show that the amygdalar CRF system is a likely target for alleviating dysfunction produced by early life trauma and that this system continues to play a major role in the lasting effects of such trauma into the juvenile stage of development.
Learn More >Chronic migraine (CM) is associated with substantial economic burden. Real-world data suggests that onabotulinumtoxinA treatment for CM reduces healthcare resource utilisation (HRU) and related costs.
Learn More >Abdominal pain adversely impacts children with functional gastrointestinal disorders (FGIDs) or organic gastrointestinal disorders (OGIDs); findings are inconsistent regarding diagnosis and health-related quality of life (HRQoL). This study utilizes a positive psychology framework to understand the experience of youth with abdominal pain (i.e., do positive psychological factors, such as optimism and pain self-efficacy, relate to higher HRQoL?). Consistent with a protective factor model of resilience, in which personal assets may serve as buffers between risk factors and negative outcomes, optimism and pain self-efficacy were examined as they relate to HRQoL in youth with abdominal pain. Specifically, exploratory moderational analyses examined a) if optimism and pain self-efficacy moderate the relation between pain and HRQoL, and b) whether diagnostic status moderated the relation between optimism/pain self-efficacy and HRQoL.
Learn More >Chronic pain is conceptualized as a biopsychosocial phenomenon that involves both physical and emotional processes. The vast majority of research regarding these facets of chronic pain characterizes differences between individuals. In this review, we describe problems with assuming that differences between persons accurately characterize within-person processes. We also provide a systematic review of studies that have examined within-person relationships between pain and affect among individuals with chronic pain.
Learn More >To better characterize the ways that migraine affects multiple domains of life.
Learn More >Chronic pain is a common symptom experienced among patients with sickle cell disease (SCD). Our aims were to assess the feasibility and acceptability of performing acupuncture for the treatment of chronic pain in adults with SCD.
Learn More >There is currently insufficient clinical and epidemiological data concerning small fibre neuropathy (SFN). This research analyzes data from medical records to determine epidemiology, demographics, clinical characteristics and etiology of SFN.
Learn More >The Global burden of disease study ranked migraine as the sixth most common disorder worldwide in 2016, with significant social and economic sequelae. In this study, we assessed the efficacy of different Calcitonin gene-related peptide (CGRP) receptor blockers as potential pharmacological approaches and compare them to placebo using the systematic review (SR) and network meta-analysis (NMA) approach. We performed a computerized search of SCOPUS, PubMed, Cochrane central, and Embase databases through January 2019 and included randomized controlled trials (RCTs), which were performed on episodic and chronic migraine patients who used Erenumab, Eptinezumab, Fremanezumab, or Galcanezumab. The combined analysis revealed that after six, eight, and twelve weeks of intervention, the medications with the most potent effects in comparison to placebo were Fremanezumab 900 mg, (SMD = -0.55, 95% CI [-0.97, -0.12]); Erenumab 140 mg, (SMD = -0.51, 95% CI [-0.61, 0.41]); and Erenumab 140 mg, (SMD = -0.48, 95% CI [-0.571, 0.39]), respectively. For chronic migraine patients, Fremanezumab 900 mg, Erenumab 140 mg, in addition to Erenumab 70 mg, were associated with the highest efficacy after 6, 8, and 12 weeks, correspondingly. The analysis of combined groups data (Chronic and Episodic) showed that Fremanezumab was the most effective drug after six weeks, where Erenumab was the most effective after 8 and 12 weeks. The current evidence retrieved from this NMA suggests that Fremanezumab was the most effective anti-migraine medication in decreasing MHDs per month after six weeks in both chronic and episodic patients.
Learn More >To date, clinical trials of deep brain stimulation (DBS) for refractory chronic pain have yielded unsatisfying results. Recent evidence suggests that the posterior insula may represent a promising DBS target for this indication.
Learn More >Background Opioid analgesics are frequently initiated for chronic and acute pain despite weak evidence of benefit, although prescribing rates of some analgesics decreased in the context of the epidemic. In some populations, up to a quarter of opioid naïve persons prescribed opioids for non-cancer pain develop prescription opioid use disorder (OUD). Audit and feedback interventions rely on constructive use of routinely collected data to align professional behaviours and clinical practice with best evidence. These interventions have been shown to help reduce inappropriate initiation. However, effectiveness and acceptability of individualized "portraits" of physicians' prescribing patterns, to reduce inappropriate initiation of opioid analgesics to opioid naïve persons, have not been evaluated. Methods REDONNA is a mixed-methods randomized study testing the effectiveness of individualized prescribing Portraits to reduce inappropriate initiation of opioid analgesics. This intervention to improve safety of opioid prescribing in primary care in British Columbia (BC), Canada involves mailing individual prescribing portraits to an 'early group' of 2604 family physicians, followed in 6 months by a mailing to 2553 family physicians in the 'delayed group'. Primary outcome is number of new opioid prescriptions initiated in opioid naïve people, measured using administrative data from a centralized medication monitoring database covering all prescription opioids dispensed from BC community pharmacies. Secondary endpoints will compare prescribing impact between the two groups. A qualitative sub-study will examine feasibility among a purposive sample of physicians and patients. Discussion This trial provides important evidence on the intervention's potential to steer policy and practice on inappropriate opioid analgesics initiation. Trial registration: The study was registered prospectively on 30 March 2020 at the ISRCTN Register (https://www.isrctn.com/ISRCTN34246811).
Learn More >The most common cause of chronic musculoskeletal pain is chronic myofascial pain syndrome (MPS). MPS often presents with increased muscle stiffness, and the myofascial trigger point (MTrP). Imaging modalities have been used to identify the MTrP, but their role in the detection and diagnosis of MPS remains unclear. The purpose of this review was to identify evidence in literature for the use of imaging in the role of classifying and explaining the physiology of MTrPs. Since few imaging techniques have been performed on MTrPs, we explored the imaging techniques that can effectively image complex skeletal muscle microstructure, and how they could be used. As part of a scoping review, we conducted a systematic search from three medical databases (CINAHL, EMBASE and MEDLINE) from year to year to analyze past MTrP imaging, as well as analyzing imaging techniques performed on the microstructure of muscle. Previously, ultrasound has been used to differentiate active, latent MTrPs, but these studies do not adequately address their underlying anatomical structure. MRI remains the standard method of imaging skeletal muscle. The existing MRI literature suggests that the DTI technique can quantify muscle injury, strain, and structure. However, theoretically, HARDI and DKI techniques seem to provide more information for complex structural areas, although these modalities have a disadvantage of longer scan times and have not been widely used on skeletal muscle. Our review suggests that DTI is the most effective imaging modality that has been used to define the microstructure of muscle and hence, could be optimal to image the MTrP. HARDI and DKI are techniques with theoretical potential for analysis of muscle, which may provide more detailed information representative of finer muscle structural features. Future research utilizing MRI techniques to image muscle are necessary to provide a more robust means of imaging skeletal muscle and the MTrP.
Learn More >Serotonin (5-HT) is highly associated with pain modulation. The human 5-HT transporter (5-HTT) gene (SLC6A4) features several polymorphisms in its promoter region (5-HTTLPR) that affect the 5-HTT expression. The S allele of 5-HTTLPR induces low 5-HT tone, and it may influence the modulation of chronic pain. Meanwhile, pain occurs in 40-50% of patients after thoracic surgery, and its mechanism remains under investigation. This study assessed the role of 5-HTTLPR polymorphisms in postthoracotomy pain severity.
Learn More >Headache disorders are highly prevalent worldwide, but not well investigated in adolescents. Few studies have included representative nationwide samples. This study aimed to present the prevalence and burden of recurrent headache in Australian adolescents.
Learn More >This systematic review aims to identify what rehabilitation care networks, within primary care or between primary and other health care settings, have been described for patients with chronic musculoskeletal pain, and what their impact is on the Quadruple Aim outcomes (health; health care costs; quality of care experienced by patients; work satisfaction for health care professionals). Studies published between 1 January 1994 and 11 April 2019 were identified in PubMed, CINAHL, Web of Science, and PsycInfo. Forty-nine articles represented 34 interventions: 21 within primary care; 6 between primary and secondary/tertiary care; 1 in primary care and between primary and secondary/tertiary care; 2 between primary and social care; 2 between primary, secondary/tertiary, and social care; and 2 between primary and community care. Results on impact were presented in 19 randomized trials, 12 non-randomized studies, and seven qualitative studies. In conclusion, there is a wide variety of content, collaboration, and evaluation methods of interventions. It seems that patient-centered interdisciplinary interventions are more effective than usual care. Further initiatives should be performed for interdisciplinary interventions within and across health care settings and evaluated with mixed methods on all Quadruple Aim outcomes.
Learn More >Dysregulation of the protease-antiprotease balance in the gastrointestinal tract has been suggested as a mechanism underlying visceral hypersensitivity in conditions such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). We aimed to study the potential therapeutic role of an intracolonically administered serine protease inhibitor for the treatment of abdominal pain in a post-inflammatory rat model for IBS. An enema containing 2,4,6-trinitrobenzene sulfonic acid (TNBS) was used to induce colitis in male Sprague-Dawley rats, whereas controls received a saline solution. Colonoscopies were performed to confirm colitis and follow-up mucosal healing. In the post-inflammatory phase, the serine protease inhibitor UAMC-00050 (0.1-5 mg/kg) or its vehicle alone (5% DMSO in HO) was administered in the colon. Thirty minutes later, visceral mechanosensitivity to colorectal distensions was quantified by visceromotor responses (VMRs) and local effects on colonic compliance and inflammatory parameters were assessed. Specific proteolytic activities in fecal and colonic samples were measured using fluorogenic substrates. Pharmacokinetic parameters were evaluated using bioanalytical measurements with liquid chromatography-tandem mass spectrometry. Post-inflammatory rats had increased trypsin-like activity in colonic tissue and elevated elastase-like activity in fecal samples compared to controls. Treatment with UAMC-00050 decreased trypsin-like activity in colonic tissue of post-colitis animals. Pharmacokinetic experiments revealed that UAMC-00050 acted locally, being taken up in the bloodstream only minimally after administration. Local administration of UAMC-00050 normalized visceral hypersensitivity. These results support the role of serine proteases in the pathophysiology of visceral pain and the potential of locally administered serine protease inhibitors as clinically relevant therapeutics for the treatment of IBS patients with abdominal pain.
Learn More >Individuals suffering from chronic low-back pain and obesity face severe physical and functional limitations. According to the fear-avoidance model, kinesiophobia might play a crucial role in the relationship between pain intensity and disability. Thus, the purpose of this study was to verify the role of kinesiophobia as a mediator in the association between pain intensity and disability in individuals with both chronic low-back pain and obesity. A total of 213 individuals with chronic low-back pain and obesity were included in the study. The level of kinesiophobia, pain intensity and disability were all assessed using self-reported questionnaires. We verified through a simple mediation analysis that kinesiophobia partially mediated the association between pain intensity and disability in our sample. According to our findings, we emphasize the crucial role of kinesiophobia as a psychological factor that should be addressed in chronic low-back pain rehabilitative protocols to reduce disability in individuals with obesity.
Learn More >(1) Background: In many surgical procedures, regional analgesia (RA) techniques are associated with improved postoperative analgesia compared to systemic pain treatment. As continuous RA requires time and experienced staff, it would be helpful to identify settings in which continuous RA has the largest benefit. (2) Methods: On the basis of 23,911 data sets from 179 German and Austrian hospitals, we analyzed the association of perioperative RA with patient-reported pain intensity, functional impairment of movement, nausea and opioid use for different surgeries. Regression analyses adjusted for age, sex and preoperative pain were performed for each surgery and the following groups: patients receiving continuous RA (surgery and ward; RA++), RA for surgery only (RA+-) and patients receiving no RA (RA–). (3) Results: Lower pain scores in the RA++ compared to the RA– group were observed in 13 out of 22 surgeries. There was no surgery where pain scores for RA++ were higher than for RA–. If maximal pain, function and side effects were combined, the largest benefit of continuous RA (RA++) was observed in laparoscopic colon and sigmoid surgery, ankle joint arthrodesis, revision (but not primary) surgery of hip replacement, open nephrectomy and shoulder surgery. The benefit of RA+- was lower than that of RA++. (4) Discussion: The additional benefit of RA for the mentioned surgeries is larger than in many other surgeries in clinical routine. The decision to use RA in a given surgery should be based on the expected pain intensity without RA and its additional benefits.
Learn More >Mirogabalin besylate has been approved in several countries to treat peripheral neuropathic pain. This pooled analysis, using data from the two pivotal Phase III studies in Asian patients with diabetic peripheral neuropathic pain and post-herpetic neuralgia, aimed to provide clinicians with more detailed and precise information relating to mirogabalin's safety and efficacy.
Learn More >The transient receptor potential vanilloid-superfamily member 3 (TRPV3) channel is implicated in a variety of physiological processes, including temperature sensing, nociception and itch, maintenance of the skin barrier, wound healing, hair growth, and embryonic development. TRPV3 is also associated with various skin diseases, including Olmsted syndrome, atopic dermatitis, and rosacea. Studies of TRPV3 are of fundamental importance for structural pharmacology aimed at the design of drugs targeting this channel and for understanding the molecular basis of temperature sensing. Here we describe a detailed protocol for expression and purification of chemically pure and stable TRPV3 protein that is suitable for structural and functional characterization of this channel, in particular for cryo-EM sample preparation and high-resolution 3D reconstruction.
Learn More >The Short-Term Kinetics of sICAM-1 after Induction of Acute Experimental Pain in Healthy Volunteers.
Intercellular adhesion molecule-1 (ICAM-1) mediates extravasation of leukocytes, releasing proinflammatory cytokines or endogenous opioids in the inflamed tissue. Thus, ICAM-1 is a crucial component of peripheral antinociception. Previously, we demonstrated a significant correlation between the soluble form of ICAM (sICAM-1) in serum and pain intensity reported by chronic pain patients. The present study examines the role and kinetics of sICAM-1 in experimentally induced acute pain. Three groups of 10 subjects were exposed to 10 min of high (capsaicin-enhanced) or low-intensity heat pain or cold pain, respectively. Thermal stimuli were induced using a device for quantitative sensory testing. Topical capsaicin significantly increased heat pain intensity without the risk of thermal tissue damage. Pain intensity was recorded every minute during testing. sICAM-1 concentrations in serum were determined by ELISA before, immediately after, and 60 min after test termination. Among all experimental groups, sICAM-1 significantly decreased immediately after pain induction. After 60 min, sICAM-1 concentrations returned towards initial values. Interestingly, a linear correlation was found between the extent of sICAM-1 changes and the initial concentrations. Whereas high initial values led to a distinct decrease of sICAM-1, low concentrations tended to increase. There was no statistically significant correlation between levels or alterations of serum sICAM-1 and pain intensity reported by the test subjects. In contrast to our previous findings in chronic pain patients, the present results show that sICAM-1 values do not correlate with the intensity of acute experimental pain. However, we were able to detect short-term changes of sICAM-1 after induction of nociceptive thermal stimuli, suggesting that this marker is part of a demand-oriented homeostatically controlled system.
Learn More >Migraine is a highly prevalent and disabling primary headache disorder, however its pathophysiology remains unclear, hindering successful treatment. A number of key secondary headache disorders have headaches that mimic migraine. Evidence has suggested a role of mitochondrial dysfunction and an imbalance between energetic supply and demand that may contribute towards migraine susceptibility. Targeting these deficits with nutraceutical supplementation may provide an additional adjunctive therapy. Neuroimaging techniques have demonstrated a metabolic phenotype in migraine similar to mitochondrial cytopathies, featuring reduced free energy availability and increased metabolic rate. This is reciprocated in vivo when modelling a fundamental mechanism of migraine aura, cortical spreading depression. Trials assessing nutraceuticals successful in the treatment of mitochondrial cytopathies including magnesium, coenzyme q10 and riboflavin have also been conducted in migraine. Although promising results have emerged from nutraceutical trials in patients with levels of minerals or vitamins below a critical threshold, they are confounded by lacking control groups or cohorts that are not large enough to be representative. Energetic imbalance in migraine may be relevant in driving the tissue towards maximum metabolic capacity, leaving the brain lacking in free energy. Personalised medicine considering an individual's deficiencies may provide an approach to ameliorate migraine.
Learn More >The pleiotropic cytokine interleukin-6 (IL-6) is emerging as a molecule with both beneficial and destructive potentials. It can exert opposing actions triggering either neuron survival after injury or causing neurodegeneration and cell death in neurodegenerative or neuropathic disorders. Importantly, neurons respond differently to IL-6 and this critically depends on their environment and whether they are located in the peripheral or the central nervous system. In addition to its hub regulator role in inflammation, IL-6 is recently emerging as an important regulator of neuron function in health and disease, offering exciting possibilities for more mechanistic insight into the pathogenesis of mental, neurodegenerative and pain disorders and for developing novel therapies for diseases with neuroimmune and neurogenic pathogenic components.
Learn More >To characterize the relationship between persistent post-traumatic headache (pPTH) and traumatic cerebrovascular injury (TCVI) in chronic traumatic brain injury (TBI). Cerebrovascular reactivity (CVR), a measure of the cerebral microvasculature and endothelial cell function, is altered both in individuals with chronic TBI and migraine headache disorder (Amyot et al., 2017; Lee et al., 2019b). The pathophysiologies of pPTH and migraine are believed to be associated with chronic microvascular dysfunction. We therefore hypothesize that TCVI may contribute to the underlying migraine-like mechanism(s) of pPTH.
Learn More >The hypothalamus is one of the key structures involved in the pathophysiology of cluster headaches. This study aimed to analyze the volume of hypothalamic subunits and structural covariance networks in the hypothalamus of patients with cluster headache.
Learn More >Low back pain is the most common pain condition seen in primary care, with the most common treatment being analgesic medications, including opioids. A dramatic increase in opioid prescriptions for low back pain over the past few decades has led to increased non-medical use and opioid overdose deaths. Cognitive behavioral therapy (CBT) for chronic pain is an evidence-based non-pharmacological treatment for pain with demonstrated efficacy when delivered using collaborative care models. No previous studies have tested CBT compared to analgesic optimization that includes opioid management in primary care. This paper describes the study design and methods of the CAre Management for the Effective use of Opioids (CAMEO) trial, a 2-arm, randomized comparative effectiveness trial in seven primary care clinics. CAMEO enrolled 261 primary care veterans with chronic (6 months or longer) low back pain of at least moderate severity who were receiving long-term opioid therapy and randomized them to either nurse care management focused on analgesic treatment and optimization (MED) or cognitive behavioral therapy (CBT). All subjects undergo comprehensive outcome assessments at baseline, 3, 6, 9, and 12 months by interviewers blinded to treatment assignment. The primary outcome is pain severity and interference, measured by the Brief Pain Inventory (BPI) total score. Secondary outcomes include health-related quality of life, fatigue, sleep, functional improvement, pain disability, pain beliefs, alcohol and opioid problems, depression, anxiety, and stress.
Learn More >