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Papers: 1 Jan 2022 - 7 Jan 2022

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Glutamate in primary afferents is required for itch transmission.

Whether glutamate or itch-selective neurotransmitters are used to confer itch specificity is still under debate. We focused on an itch-selective population of primary afferents expressing MRGPRA3, which highly expresses Vglut2 and the neuropeptide neuromedin B (Nmb), to investigate this question. Optogenetic stimulation of MRGPRA3 afferents triggers scratching and other itch-related avoidance behaviors. Using a combination of optogenetics, spinal cord slice recordings, Vglut2 conditional knockout mice, and behavior assays, we showed that glutamate is essential for MRGPRA3 afferents to transmit itch. We further demonstrated that MRGPRA3 afferents form monosynaptic connections with both NMBR and NMBR neurons and that NMB and glutamate together can enhance the activity of NMBR spinal DH neurons. Moreover, Nmb in MRGPRA3 afferents and NMBR DH neurons are required for chloroquine-induced scratching. Together, our results establish a new model in which glutamate is an essential neurotransmitter in primary afferents for itch transmission, whereas NMB signaling enhances its activities.

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The longitudinal relationship between emotion regulation and pain-related outcomes: Results from a large, online prospective study.

People with chronic pain engage in various strategies, such as pain catastrophizing and pain acceptance, to regulate the difficult emotional aspects of living with pain. Engagement in these strategies is known to influence pain severity and pain interference. However, less research has examined the extent to which general emotion regulation, the ability to identify emotions and engage in strategies to alter emotions, relates to pain-related outcomes. The current study, a large (N = 1453) online prospective study of adults with chronic pain, employed theory-driven assessment of emotion regulation to determine the extent to which general difficulties with emotion regulation at baseline relate to pain severity and pain interference at three-month follow-up, above and beyond pain catastrophizing and pain acceptance. We conducted a series of path models, controlling for demographic covariates and baseline pain severity and pain interference. Pain catastrophizing and pain acceptance at baseline significantly predicted pain interference at three-month follow-up. However, when indices of general emotion regulation were entered into the model, the associations between pain catastrophizing and pain interference (B = .009, p = .153) were no longer statistically significant. Alexithymia emerged as a significant predictor of pain severity (B = .012, p = .032) and pain interference (B = .026, p < .001). These findings highlight the value of considering the role of general emotion regulation (particularly identifying and describing emotions), in addition to pain-specific experiences, in understanding risk for poor pain-related outcomes. PERSPECTIVE: : In addition to pain catastrophizing and pain acceptance, difficulties regulating emotions in general (particularly elevated alexithymia) relates to pain outcomes three months later. These findings shed light on risk for poor pain outcomes and point to general emotion regulation as a potentially important target of chronic pain intervention.

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Behavioural immune landscapes of inflammation.

Transcriptional and proteomic profiling of individual cells have revolutionized interpretation of biological phenomena by providing cellular landscapes of healthy and diseased tissues. These approaches, however, do not describe dynamic scenarios in which cells continuously change their biochemical properties and downstream 'behavioural' outputs. Here we used 4D live imaging to record tens to hundreds of morpho-kinetic parameters describing the dynamics of individual leukocytes at sites of active inflammation. By analysing more than 100,000 reconstructions of cell shapes and tracks over time, we obtained behavioural descriptors of individual cells and used these high-dimensional datasets to build behavioural landscapes. These landscapes recognized leukocyte identities in the inflamed skin and trachea, and uncovered a continuum of neutrophil states inside blood vessels, including a large, sessile state that was embraced by the underlying endothelium and associated with pathogenic inflammation. Behavioural screening in 24 mouse mutants identified the kinase Fgr as a driver of this pathogenic state, and interference with Fgr protected mice from inflammatory injury. Thus, behavioural landscapes report distinct properties of dynamic environments at high cellular resolution.

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Pharmacological treatments of neuropathic pain: real-life comparisons using propensity score matching.

Studies comparing different drug treatments for chronic neuropathic pain (NP) are very limited. We, therefore, examined 4 recommended treatments, namely, antidepressants (duloxetine, venlafaxine, and tricyclic antidepressants), antiepileptics (gabapentine and pregabalin), weak opioids, and strong opioids, among patients with NP evaluated before first visit in a tertiary pain treatment centre and 6 months later. Patients with both a clinical diagnosis of NP and a DN4 score >=3/7 were selected from patients enrolled in the Quebec Pain Registry. Each participant was assigned an inverse weighting of the probability of receiving any NP treatment, taking into account their age, sex, baseline pain intensity, pain duration, pain catastrophizing tendency, education level, employment, and comedications at 6-month follow-up (M6). Patients were considered as improved if they presented at least a 30% reduction on average pain intensity at M6 compared with baseline. A total of 944 patients completed both baseline and M6 evaluations. Overall, 23.0% of patients were significantly improved for pain intensity at M6. There was no significant difference in proportions patients taking or not antidepressants, gabapentinoids, or weak opioids. Among patients taking strong opioids (N = 288), 13.9% (N = 40/288) were improved vs 27.0% (177/656) of those who were not on opioids (P < 0.004). Inverse probability of treatment weighting confirmed that the proportion of patients who improved was significantly lower among those taking strong opioids compared with those who did not (P < 0.001). In conclusion, long-term use of strong opioids is a treatment suited for a limited proportion of patients with chronic NP.

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Family History of Alcohol Use Disorder as a Predictor of Endogenous Pain Modulation Among Moderate to Heavy Drinkers.

Family history of alcohol use disorder (AUD) is frequently endorsed by persons with chronic pain. Although individuals with a family history of AUD have demonstrated enhanced sensitivity to painful stimulation, previous research has not examined endogenous pain modulation in this population. The goal of this study was to test family history of AUD as a predictor of conditioned pain modulation, offset analgesia, and temporal summation among a sample of moderate and heavy drinkers. Adults with no current pain (N = 235; 58.3% male; M = 34.3; 91.9% non-Hispanic; 60% white) were evaluated for family history of AUD at baseline and pain modulatory outcomes were assessed via quantitative sensory testing. Participants with a family history of AUD (relative to those without) evinced a pro-nociceptive pain modulation profile in response to experimental pain. Specifically, family history of AUD was associated with deficits in pain-inhibitory processes. Approximately 4% of the variance in endogenous pain modulation was accounted for by family history, and exploratory analyses suggested these effects may be driven by paternal AUD.

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Microvascular barrier protection by microRNA-183 via FoxO1 repression: A pathway disturbed in neuropathy and complex regional pain syndrome.

Blood nerve barrier (BNB) disruption and edema are common in neuropathic pain as well as complex regional pain syndrome (CRPS). MicroRNAs (miRNA) are epigenetic multitarget switches controlling neuronal and non-neuronal cells in pain. The miR-183 complex attenuates hyperexcitability in nociceptors, but additional non-neuronal effects via transcription factors could contribute as well. This study explored exosomal miR-183 in CRPS and murine neuropathy, its effect on the microvascular barrier via transcription factor FoxO1 and tight junction protein claudin-5, and its antihyperalgesic potential. Sciatic miR-183 decreased after CCI. Substitution with perineural miR-183 mimic attenuated mechanical hypersensitivity and restored BNB function. In vitro, serum from CCI mice und CRPS patients weakened the microvascular barrier of murine cerebellar endothelial cells, increased active FoxO1 and reduced claudin-5, concomitant with a lack of exosomal miR-183 in CRPS patients. Cellular stress also compromised the microvascular barrier which was rescued either by miR-183 mimic via FoxO1 repression or by prior silencing of Foxo1. Perspective: Low miR-183 leading to barrier impairment via FoxO1 and subsequent claudin-5 suppression is a new aspect in the pathophysiology of CRPS and neuropathic pain. This pathway might help untangle the wide symptomatic range of CRPS and nurture further research into miRNA mimics or FoxO1 inhibitors.

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Effect of dexamethasone as an analgesic adjuvant to multimodal pain treatment after total knee arthroplasty: randomised clinical trial.

To investigate the effects of one and two doses of intravenous dexamethasone in patients after total knee arthroplasty.

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Patient-centred approaches for the management of unpleasant symptoms in kidney disease.

Patients with chronic kidney disease (CKD) frequently experience unpleasant symptoms. These can be gastrointestinal (constipation, nausea, vomiting and diarrhoea), psychological (anxiety and sadness), neurological (lightheadedness, headache and numbness), cardiopulmonary (shortness of breath and oedema), dermatological (pruritus and dry skin), painful (muscle cramps, chest pain and abdominal pain) or involve sexual dysfunction, sleep disorders and fatigue. These symptoms often occur in clusters, with one of them as the lead symptom and others as secondary symptoms. Uraemic toxins (also called uremic toxins) are often considered to be the main cause of CKD-associated symptom burden, but treatment of uraemia by dialysis often fails to resolve them and can engender additional symptoms. Indeed, symptoms can be exacerbated by comorbid conditions, pharmacotherapies, lifestyle and dietary regimens, kidney replacement therapy and ageing. Patients with kidney disease, including those who depend on dialysis or transplantation, should feel actively supported in their symptom management through the identification and targeting of unpleasant symptoms via a tailored palliative care approach. Such an approach may help minimize the burden and consequences of kidney disease, and lead to improved patient outcomes including health-related quality of life and better life participation.

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Small molecule targeting NaV1.7 via inhibition of the CRMP2-Ubc9 interaction reduces pain in chronic constriction injury (CCI) rats.

The voltage-gated sodium channel isoform NaV1.7 is a critical player in the transmission of nociceptive information. This channel has been heavily implicated in human genetic pain disorders and is a validated pain target. However, targeting this channel directly has failed, and an indirect approach – disruption of interactions with accessory protein partners – has emerged as a viable alternative strategy. We recently reported that a small-molecule inhibitor of CRMP2 SUMOylation, compound , selectively reduces NaV1.7 currents in DRG neurons across species from mouse to human. This compound also reversed mechanical allodynia in a spared nerve injury and chemotherapy-induced model of neuropathic pain. Here, we show that oral administration of reverses mechanical allodynia in a chronic constriction injury (CCI) model of neuropathic pain. Furthermore, we show that orally administered reverses the increased latency to cross an aversive barrier in a mechanical conflict-avoidance task following CCI. These two findings, in the context of our previous report, support the conclusion that is a robust inhibitor of NaV1.7 function with the ultimate effect of profoundly ameliorating mechanical allodynia associated with nerve injury. The fact that this was observed using both traditional, evoked measures of pain behavior as well as the more recently developed operator-independent mechanical conflict-avoidance assay increases confidence in the efficacy of -induced anti-nociception.

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Lidocaine relieves spinal cord ischemia-reperfusion injury via long non-coding RNA MIAT-mediated Notch1 downregulation.

Microglial activation and inflammatory response play a critical role in spinal cord ischemia-reperfusion injury (SCIRI). This study aimed to investigate whether lidocaine relieves SCIRI via modulating MIAT-mediated Notch1 downregulation. Mouse SCIRI was induced by the obstruction of the aortic arch. Lidocaine was injected after reperfusion. Microglial activation and inflammatory response were assessed by Iba1, interleukin 1 beta (IL-1β), and tumor necrosis factor alpha (TNF-α) levels. The interaction between MIAT and Notch1 was assessed by RNA pull-down and RNA immunoprecipitation assays. Lidocaine treatment relieved SCIRI by reducing Iba1 and serum TNF-α and IL-1β levels. After lidocaine treatment, MIAT expression was elevated in lipopolysaccharide- (LPS-) induced BV2 cells. The interference of MIAT and the overexpression of MIAT and Notch1 restored TNF-α and IL-1β levels in supernatants. Notch1 protein was existent in MIAT-pull-down compounds, and the expression of MIAT was markedly elevated in Notch1-immunoprecipitants. The overexpression of MIAT markedly promoted the degradation of Notch1 and increased the level of ubiquitin-bound Notch1 complex. The therapeutic effect of lidocaine on SCIRI mice could be reversed by adeno-associated virus-mediated MIAT knockdown. In conclusion, lidocaine treatment relieved SCIRI via inhibiting microglial activation and reducing the inflammatory response. The molecular mechanism was partly through MIAT-mediated Notch1 downregulation.

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The glial cell’s role in antinociceptive differential effects of oxytocin upon female and male rats.

Sex plays a crucial role in pain processing and response to analgesic drugs. Indeed, spinal glia seems to be significant in the sexual dimorphism observed in the above effects. Recently, studies have associated oxytocin with antinociceptive effects, but these have been mainly performed in male animals; consequently, the influence of sex has been poorly explored.

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Play the Pain: A Digital Strategy for Play-Oriented Research and Action.

The value of understanding patients' illness experience and social contexts for advancing medicine and clinical care is widely acknowledged. However, methodologies for rigorous and inclusive data gathering and integrative analysis of biomedical, cultural, and social factors are limited. In this paper, we propose a digital strategy for large-scale qualitative health research, using (as a state of being, a communication mode or context, and a set of imaginative, expressive, and game-like activities) as a research method for recursive learning and action planning. Our proposal builds on Gregory Bateson's cybernetic approach to knowledge production. Using chronic pain as an example, we show how pragmatic, structural and cultural constraints that define the relationship of patients to the healthcare system can give rise to conflicted messaging that impedes inclusive health research. We then review existing literature to illustrate how different types of play including games, chatbots, virtual worlds, and creative art making can contribute to research in chronic pain. Inspired by Frederick Steier's application of Bateson's theory to designing a science museum, we propose DiSPORA (Digital Strategy for Play-Oriented Research and Action), a virtual citizen science laboratory which provides a framework for delivering health information, tools for play-based experimentation, and data collection capacity, but is flexible in allowing participants to choose the mode and the extent of their interaction. Combined with other data management platforms used in epidemiological studies of neuropsychiatric illness, DiSPORA offers a tool for large-scale qualitative research, digital phenotyping, and advancing personalized medicine.

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Long-term intrathecal administration of morphine vs. baclofen: Differences in CSF glycoconjugate profiles using multiglycomics.

Opioid use for treatment of persistent pain has increased dramatically over the past two decades, but it has not resulted in improved pain management outcomes. To understand the molecular mechanisms of opioids, molecular signatures that arise from opioid exposure are often sought after, using various analytical methods. In this study, we performed proteomics, and multiglycomics via sequential analysis of polysialic acids, glycosaminoglycans, N-glycans and O-glycans, using the same cerebral spinal fluid (CSF) sample from patients that had long-term (>2 years), intrathecal morphine or baclofen administered via an indwelling pump. Proteomics and N-glycomics signatures between the two treatment groups were highly conserved, while significant differences were observed in polysialic acid, heparan sulfate glycosaminoglycan and O-glycan profiles between the two treatment groups. This represents the first study to investigate the potential relationships between diverse CSF conjugated glycans and long-term intrathecal drug exposure. The unique changes, observed by a sequential analytical workflow, reflect previously undescribed molecular effects of opioid administration and pain management.

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Arguments for and against a new diagnostic entity for patients with chronic pain on long-term opioid therapy for whom harms outweigh benefits.

The goal of this study was to understand perspectives on whether a new diagnostic entity, distinct from Diagnostic and Statistical Manual – 5 (DSM-5) opioid use disorder (OUD), is needed for patients with chronic pain on long-term opioid therapy (LTOT) for whom the harms of continued opioid therapy outweigh the benefits. Data were collected as part of a larger Delphi study. We used rapid and thematic qualitative methods to analyze data from 51 panelists with expertise in internal medicine, psychiatry, psychology, and related fields. Three-quarters of panelists supported a new diagnostic entity; common themes included recognizing distinct experiences of patients prescribed LTOT, addressing problems with DSM-5 OUD criteria, facilitating research and improved treatment, and reducing stigma. Thirteen panelists opposed the creation of a new diagnostic entity; common themes included similarities in biological underpinnings of patients prescribed LTOT and diagnosed with OUD, belief that the continuum of OUD captured patients' experiences, finding better ways to address problems with DSM-5 OUD criteria, and concerns about stigma. While this expert panel disagreed about the need for a new diagnostic entity, there was an overall acknowledgement that the current implementation of DSM-5's OUD diagnosis is not meeting the needs of LTOT providers or patients. Perspective: The DSM-5's OUD diagnosis may not adequately meet the needs of patients on LTOT for whom the harms of continued opioid therapy outweigh the benefits. Experts do not agree on how to address this problem; more work is needed to determine if a new diagnostic entity would be beneficial.

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Trajectories, risk factors, and impact of persistent pain after major musculoskeletal surgery in adolescents: a replication study.

Studies have identified high rates of chronic postsurgical pain in adolescents. Characterizing patterns of pain in the transition from acute to chronic following major surgery may pinpoint critical periods of recovery. This observational study modelled pain trajectories over 1-year following surgery to attempt replication of prior work and evaluate baseline psychosocial factors and 12-month health outcomes. Adolescents 10-18 years completed electronic daily pain reporting for 7 days and self-reported health outcomes, at 5 assessment timepoints. Group-based trajectory modelling identified two trajectories with similar starting points in-hospital but distinct recovery courses at home. Pain declined steadily in one group across the study period ("Declining Pain"; estimated probability,18.9%), but pain increased after hospital discharge and remained high through 12-months in the other group ("High and Persistent Pain"; estimated probability,81.1%). Pre-surgery pain (aOR=1.86,p=0.001) and sleep quality (aOR=0.49,p=0.029) were associated with the High and Persistent pain trajectory in multivariate regressions. This trajectory was associated with lower total quality of life (B=-9.79,p=0.002), physical health (B=-15.93,p<0.001), psychosocial health (B=-6.73,p=0.06), and greater fatigue (B=-13.61,p=0.001). This study replicated prior findings identifying two post-surgical pain trajectories with diverging pain in the first two weeks. Clinical detection of those with increasing pain and early intervention may interrupt persistence of pain. PERSPECTIVE: . This article replicates a prior study identifying distinct post-surgical pain trajectories, Declining Pain and High and Persistent Pain. The High and Persistent pain trajectory is associated with pre-surgery pain, pre-surgery sleep quality, and lower quality of life (total, physical, and psychosocial health as well as fatigue) at 12-month follow-up.

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Maintenance of Patient-Reported Outcomes in Baricitinib-Treated Patients with Moderate-to-Severe Active Rheumatoid Arthritis: Post Hoc Analyses from Two Phase 3 Trials.

Baricitinib has been shown to improve patient-reported outcomes (PROs) in patients with rheumatoid arthritis (RA) who are inadequate responders (IR) to conventional synthetic and biologic disease-modifying antirheumatic drugs (csDMARDs and bDMARDs, respectively). We assessed the ability of baricitinib 2-mg to maintain minimal clinically important differences (MCIDs) in PROs until week 24 among week 4 and 12 responders.

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Exchange proteins directly activated by cyclic adenosine monophosphate inhibitor reverses mechanical allodynia via the modification of astrocytes activity in the spinal cord.

Gliosis and inflammation are pivotal in the development of acute and chronic pain. Here, we demonstrated a previously unidentified molecular mechanism in which the activation of exchange proteins directly activated by cyclic adenosine monophosphate (Epac)1 accelerated the activation of astrocytes in the spinal cord, thereby promoting chronic postsurgical pain (CPSP).

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A systematic review and meta-analysis of efficacy of ultrasound-guided single-shot quadratus lumborum block for postoperative analgesia in adults following total hip arthroplasty.

To evaluate the efficacy of ultrasound-guided single-shot quadratus lumborum block (QLB) for postoperative analgesia in adults following total hip arthroplasty (THA).

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Central metabolism as a potential origin of sex differences in morphine antinociception but not in the induction of antinociceptive tolerance in mice.

In rodents, morphine antinociception is influenced by sex. However, conflicting results have been reported regarding the interaction between sex and morphine antinociceptive tolerance. Morphine is metabolised in the liver and brain into morphine-3-glucuronide (M3G). Sex differences in morphine metabolism and differential metabolic adaptations during tolerance development might contribute to behavioural discrepancies. This article investigates the differences in peripheral and central morphine metabolism after acute and chronic morphine treatment in male and female mice.

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Does Neuromodulation Reduce Chronic Pain Patient Emergency Department Utilization?

Chronic pain (CP) affects roughly 100 million adults in the United States. These subjects present disproportionately to the emergency department (ED). Neuromodulation (NM) has been shown to reduce ED visits longitudinally in subjects.

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Pinocembrin relieves hip fracture-induced pain by repressing spinal substance P signaling in aged rats.

Whether pinocembrin (PCN) could be utilized to alleviate hip fracture-induced pain is investigated in this research. Aged rats with hip fractures were treated with vehicle or 80 mg/kg/day PCN from week 3 to week 4. Then hind paw mechanical allodynia, unweighting, warmth, and thickness were measured. The microglia and astrocytes activation and proliferation markers in the spinal dorsal horn were detected with real-time PCR and immunofluorescence staining. The relative expression of substance P and its receptor, tachykinin receptor 1 (Tacr1), were detected with enzyme-linked immunosorbent assay (ELISA) and Western blots. The antinociceptive effect of Tacr1 inhibitor LY303870 was also testified. PCN alleviated hip fracture-induced hind paw nociceptive (allodynia and unweighting) and vascular changes (warmth and thickness) in aged rats with diminished microglia and astrocytes activation and proliferation in the spinal dorsal horn. Up-regulated substance P and Tacr1 were induced after hip fracture, which could be reversed by PCN treatment. Furthermore, LY303870 treatment partially reversed both spinal nociceptive sensitization and vascular changes after hip fracture. Substance P signaling contributes to the nociceptive and vascular changes observed in the hip fracture, which could be alleviated by PCN.

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Effect of High-Power Laser Therapy Versus Shock Wave Therapy on Pain and Function in Knee Osteoarthritis Patients: A Randomized Controlled Trial.

The aim of this study was to evaluate and compare the effects of extracorporeal shock wave therapy (ESWT) and high-intensity laser therapy (HILT), as outpatient physical therapy modalities, on knee osteoarthritis (KOA) patients. The treatment program was completed by 40 individuals with stage II KOA (according to Kellgren and Lawrence) who were randomly allocated to one of two groups. They have had more than grade 3 pain on the visual analog scale (VAS) during activities for the last 3 months, with body-mass index less than 30 and no history of knee operation, fracture, cancer, or other neuromuscular or musculoskeletal diseases that may affect study results. The ESWT group ( = 20, mean age = 40.12 ± 9.45 years) received ESWT, 0.05 mJ/mm, one session/week for 4 weeks, and the HILT group ( = 20, mean age = 46.62 ± 8.68 years) received HILT, 1500 mJ/cm in each session, three sessions/week for 4 weeks. Both groups received conservative physical therapy programs. Before and after 4 weeks of intervention, pain, physical function, and disability were assessed using a VAS, 6-min walking test, and the Western Ontario and McMaster Universities Osteoarthritis Index. When the pre- and post-treatment mean values of dependent variables of both groups were compared, there were statistically significant improvements in both groups. Significant differences in the measured variables were also discovered in favor of the HILT group compared with the ESWT group. HILT showed a superior effect compared with ESWT on pain, physical function, and disability in chronic KOA patients. Pan African Clinical Trials Registry number: PACTR202007638955907.

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Enhanced arthrocentesis of the effusive knee with pneumatic compression.

Complete arthrocentesis of the effusive knee ameliorates patient pain, reduces intra-articular and intraosseous pressure, removes inflammatory cytokines, and has been shown to substantially improve the therapeutic outcomes of intra-articular injections. However, conventional arthrocentesis incompletely decompresses the knee, leaving considerable residual synovial fluid in the intra-articular space. The present study determined whether external pneumatic circumferential compression of the effusive knee permitted more successful arthrocentesis and complete joint decompression.

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LncRNA MRAK159688 facilitates morphine tolerance by promoting REST-mediated inhibition of mu opioid receptor in rats.

Morphine tolerance (MT) caused by the long-term use of morphine is a major medical problem. The molecular mechanism of morphine tolerance remains elusive. Here, we established a morphine tolerance model in rats and verified whether the long noncoding RNA (lncRNA) MRAK159688 is involved in morphine tolerance and its specific molecular mechanism. We show the significant upregulation of MRAK159688 expression in the spinal cord of morphine-tolerant rats. Overexpression of MRAK159688 by a lentivirus reduces the analgesic efficacy of morphine and induces pain behavior. Downregulation of MRAK159688 using a small interfering RNA (siRNA) attenuates the formation of morphine tolerance, partially reverses the development of morphine tolerance and alleviates morphine-induced hyperalgesia. MRAK159688 is located in the nucleus and cytoplasm of neurons, and it colocalizes with repressor element-1 silencing transcription factor (REST) in the nucleus. MRAK159688 potentiates the expression and function of REST, thereby inhibiting the expression of mu opioid receptor (MOR) and subsequently inducing morphine tolerance. Moreover, REST overexpression blocks the effects of MRAK159688 siRNA on relieving morphine tolerance. In general, chronic morphine administration-mediated upregulation of MRAK159688 in the spinal cord contributes to morphine tolerance and hyperalgesia by promoting REST-mediated inhibition of MOR. MRAK159688 downregulation may represent a novel RNA-based therapy for morphine tolerance.

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Stress-induced antinociception to noxious heat requires α-adrenaline receptors of spinal inhibitory neurons in mice.

It is well known that acute exposure to physical stress produces a transient antinociceptive effect (called stress-induced analgesia [SIA]). One proposed mechanism for SIA involves noradrenaline (NA) in the central nervous system. NA has been reported to activate inhibitory neurons in the spinal dorsal horn (SDH), but its in vivo role in SIA remains unknown. In this study, we found that an antinociceptive effect on noxious heat after acute exposure to restraint stress was impaired in mice with a conditional knockout of α-adrenaline receptors (α-ARs) in inhibitory neurons (Vgat-Cre;Adra1a mice). A similar reduction was also observed in mice treated with N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine, a selective neurotoxin for NAergic neurons in the locus coeruleus (LC). Furthermore, whole-cell patch-clamp recordings using spinal cord slices revealed that NA-induced increase in the frequency of spontaneous inhibitory postsynaptic currents in the substantia gelatinosa neurons was suppressed by silodosin, an α-AR antagonist, and by conditional knockout of α-ARs in inhibitory neurons. Moreover, under unstressed conditions, the antinociceptive effects of intrathecal NA and phenylephrine on noxious heat were lost in Vgat-Cre;Adra1a mice. Our findings suggest that activation of α-ARs in SDH inhibitory neurons, presumably via LC-NAergic neurons, is necessary for SIA to noxious heat.

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Socioeconomic status and use of analgesic drugs before and after primary hip arthroplasty: a population-based cohort study of 103,209 patients during 1996-2018.

Background and purpose – Total hip arthroplasty (THA) is an effective and common procedure. However, persistent pain and analgesic requirement up to 2 years after THA surgery are common. We examined the trends in the utilization of analgesics before and after THA, overall, and in relation to socioeconomic status (SES) in a populationbased cohort. Patients and methods – We used the Danish Hip Arthroplasty Register to identify 103,209 patients who underwent THA between 1996 and 2018. Data on prescriptions and SES markers was obtained from Danish medical databases. Prevalence rates of redeemed prescriptions for analgesics with 95% confidence intervals were calculated for 4 quarters before and 4 quarters after THA for the entire THA population, and by 3 SES markers (education, cohabiting status, and wealth). Results – Overall, the prevalence of analgesic use prior to surgery was 42% at 9-12 months and 59% at 0-3 months before the THA. The prevalence of analgesics reached its highest at 64% 0-3 months after THA but declined to 27% at 9-12 months after THA. Low education, living alone, and having low wealth (low SES) were associated with higher prevalence of analgesics use both before and after THA. Interpretation – 59% of patients used analgesics 0-3 months before surgery, which could indicate that THA might not be considered the last option for treatment and that surgery criteria might depend more on factors such as patient preferences or hip function. Moreover, health professionals should prioritize the use of a detailed plan when phasing out analgesics after THA to counteract unnecessary use, especially when treating patients with low SES.

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IL-17 crosses the blood-brain barrier to trigger neuroinflammation: a novel mechanism in nitroglycerin-induced chronic migraine.

Chronic migraine places a disabling burden on patients, which is extensively modeled by the nitroglycerin (NTG)-treated animal model. Although the NF-κB pathway is involved in an increase in CGRP levels and activation of the trigeminal system in the NTG model, the relationship between NTG and neuroinflammation remains unclear. This study aimed to optimize a chronic NTG rat model with hyperalgesia and the ethological capacity for estimating migraine therapies and to further explore the underlying mechanism of NTG-induced migraine.

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A Novel Peripheral Action of PICK1 Inhibition in Inflammatory Pain.

Chronic pain is a major healthcare problem that impacts one in five adults across the globe. Current treatment is compromised by dose-limiting side effects including drowsiness, apathy, fatigue, loss of ability to function socially and professionally as well as a high abuse liability. Most of these side effects result from broad suppression of excitatory neurotransmission. Chronic pain states are associated with specific changes in the efficacy of synaptic transmission in the pain pathways leading to amplification of non-noxious stimuli and spontaneous pain. Consequently, a reversal of these specific changes may pave the way for the development of efficacious pain treatment with fewer side effects. We have recently described a high-affinity, bivalent peptide TAT-P-(C5), enabling efficient targeting of the neuronal scaffold protein, PICK1, a key protein in mediating chronic pain sensitization. In the present study, we demonstrate that in an inflammatory pain model, the peptide does not only relieve mechanical allodynia by targeting PICK1 involved in central sensitization, but also by peripheral actions in the inflamed paw. Further, we assess the effects of the peptide on novelty-induced locomotor activity, abuse liability, and memory performance without identifying significant side effects.

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Genome-Wide Association Study of 2,093 Cases With Idiopathic Polyneuropathy and 445,256 Controls Identifies First Susceptibility Loci.

About one third of patients with chronic polyneuropathy have no obvious underlying etiology and are classified as having idiopathic polyneuropathy. The lack of knowledge about pathomechanisms and predisposing factors limits the development of effective prevention and treatment for these patients. We report the first genome-wide association study (GWAS) of idiopathic polyneuropathy. Cases with idiopathic polyneuropathy and healthy controls were identified by linkage to hospital records. We performed genome-wide association studies using genetic data from two large population-based health studies, the Trøndelag Health Study (HUNT, 1,147 cases and 62,204 controls) and UK Biobank (UKB, 946 cases and 383,052 controls). In a two-stage analysis design, we first treated HUNT as a discovery cohort and UK Biobank as a replication cohort. Secondly, we combined the two studies in a meta-analysis. Downstream analyses included genetic correlation to other traits and diseases. We specifically examined previously reported risk loci, and genes known to cause hereditary polyneuropathy. No replicable risk loci were identified in the discovery-replication stage, in line with the limited predicted power of this approach. When combined in a meta-analysis, two independent loci reached statistical significance (rs7294354 in -value 4.51 × 10) and (rs147738081 near -value 4.75 × 10). Idiopathic polyneuropathy genetically correlated with several anthropometric measures, most pronounced for height, and with several pain-related traits. In this first GWAS of idiopathic polyneuropathy we identify two risk-loci that indicate possible pathogenetic mechanisms. Future collaborative efforts are needed to replicate and expand on these findings.

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Gender Differences in 3-Month Outcomes of Erenumab Treatment-Study on Efficacy and Safety of Treatment With Erenumab in Men.

We reported gender-specific data on the efficacy and safety of erenumab, a monoclonal antibody antagonizing the calcitonin gene-related peptide (CGRP) receptor. Our pooled patient-level analysis of real-world data included patients treated with erenumab and followed up for 12 weeks. We considered the following outcomes at weeks 9-12 of treatment compared with baseline: 0-29%, 30-49%, 50-75%, and ≥75% responder rates, according to the decrease in monthly headache days (MHDs), rate of treatment stopping, change in MHDs, monthly migraine days (MMDs), monthly days of acute medication and triptan use, and Headache Impact Test-6 (HIT-6) score from baseline to weeks 9-12. Outcomes were compared between men and women by the chi-squared test or -test, as appropriate. An analysis of covariance (ANCOVA) was performed to identify factors influencing the efficacy outcomes. We included 1,410 patients from 16 centers, of which 256 (18.2%) were men. Men were older than women and had a lower number of MHDs at baseline. At weeks 9-12, compared with baseline, 46 (18.0%) men had a ≥75% response, 75 (29.3%) had a 50-74% response, 35 (13.7%) had a 30-49% response, and 86 (33.6%) had a 0-29% response, while 14 (5.5%) stopped the treatment. The corresponding numbers for women were 220 (19.1%), 314 (27.2%), 139 (12.0%), 402 (34.8%), and 79 (6.8%). No gender difference was found in any of the outcomes. The ANCOVA showed that gender did not influence the efficacy of outcomes. We found that erenumab is equally safe and effective in men compared with women after 12 weeks.

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Does group-based cognitive therapy improve functional ability, pain, catastrophic thoughts and quality of life in patients with persistent low back pain and psychological risk factors? A randomised controlled trial in a secondary care setting.

To investigate the effects of a group-based cognitive behavioural intervention for patients with persistent low back pain (LBP) and psychological risk factors referred to secondary care.

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Selected Thiadiazine-Thione Derivatives Attenuate Neuroinflammation in Chronic Constriction Injury Induced Neuropathy.

Neuropathic pain refers to a lesion or disease of peripheral and/or central somatosensory neurons and is an important body response to actual or potential nerve damage. We investigated the therapeutic potential of two thiadiazine-thione [TDT] derivatives, 2-(5-propyl-6-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT1] and 2-(5-propyl-2-thioxo-1, 3, 5-thiadiazinan-3-yl) acetic acid [TDT2] against CCI (chronic constriction injury)-induced neuroinflammation and neuropathic pain. Mice were used for assessment of acute toxicity of TDT derivatives and no major toxic/bizarre responses were observed. Anti-inflammatory activity was assessed using the carrageenan test, and both TDT1 and TDT2 significantly reduced carrageenan-induced inflammation. We also used rats for the induction of CCI and performed allodynia and hyperalgesia-related behavioral tests followed by biochemical and morphological analysis using RT-qPCR, immunoblotting, immunohistochemistry and immunofluorescence. Our findings revealed that CCI induced clear-cut allodynia and hyperalgesia which was reversed by TDT1 and TDT2. To determine the function of TDT1 and TDT2 in glia-mediated neuroinflammation, Iba1 mRNA and protein levels were measured in spinal cord tissue sections from various experimental groups. Interestingly, TDT1 and TDT2 substantially reduced the mRNA expression and protein level of Iba1, implying that TDT1 and TDT2 may mitigate CCI-induced astrogliosis. molecular docking studies predicted that both compounds had an effective binding affinity for TNF-α and COX-2. The compounds interactions with the proteins were dominated by both hydrogen bonding and van der Waals interactions. Overall, these results suggest that TDT1 and TDT2 exert their neuroprotective and analgesic potentials by ameliorating CCI-induced allodynia, hyperalgesia, neuroinflammation and neuronal degeneration in a dose-dependent manner.

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The role of basolateral amygdala orexin 1 receptors on the modulation of pain and psychosocial deficits in nitroglycerin-induced migraine model in adult male rats.

Migraine headaches have been associated with sensory hyperactivity and anomalies in social/emotional responses. The main objective of this study was to evaluate the potential involvement of orexin 1 receptors (Orx1R) within the basolateral amygdala (BLA) in the modulation of pain and psychosocial dysfunction in a nitroglycerin (NTG)-induced rat model of migraine.

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Combination of waveforms in modern spinal cord stimulation.

After the surge of burst stimulation, different waveforms were developed to optimize results in spinal cord stimulation. Studies have shown higher responder rates for multiwave therapy, but since the launch of such multiwave systems, little is known about the patients' preference regarding waveforms in the long-term follow-up. No study connected particular waveforms to specific pain etiologies or required stimulation parameters so far.

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Investigating the Causal Relationship Between Physical Activity and Chronic Back Pain: A Bidirectional Two-Sample Mendelian Randomization Study.

Recent observational studies have reported a negative association between physical activity and chronic back pain (CBP), but the causality of the association remains unknown. We introduce bidirectional Mendelian randomization (MR) to assess potential causal inference between physical activity and CBP. This two-sample MR used independent genetic variants associated with physical activity and CBP as genetic instruments from large genome-wide association studies (GWASs). The effects of both directions (physical activity to CBP and CBP to physical activity) were examined. Inverse variance-weighted meta-analysis and alternate methods (weighted median and MR-Egger) were used to combine the MR estimates of the genetic instruments. Multiple sensitivity analyses were conducted to examine the robustness of the results. The MR set parallel GWAS cohorts, among which, those involved in the primary analysis were comprised of 337,234 participants for physical activity and 158,025 participants (29,531 cases) for CBP. No evidence of a causal relationship was found in the direction of physical activity to CBP [odds ratio (OR), 0.98; 95% CI, 0.85-1.13; = 0.81]. In contrast, a negative causal relationship in the direction of CBP to physical activity was detected ( = -0.07; 95% CI, -0.12 to -0.01; = 0.02), implying a reduction in moderate-vigorous physical activity (approximately 146 MET-minutes/week) for participants with CBP relative to controls. The negative relationship between physical activity and CBP is probably derived from the reduced physical activity of patients experiencing CBP rather than the protective effect of physical activity on CBP.

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Antinociceptive Effects of Aza-Bicyclic Isoxazoline-Acylhydrazone Derivatives in Different Models of Nociception in Mice.

In a study recently published by our research group, the compounds isoxazoline-acylhydrazone derivatives R-99 and R-123 presented promising antinociceptive activity. However, the mechanism of action of this compound is still unknown.

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What Is Migraine?

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Dupilumab Treatment for Cholestatic Pruritus.

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Mouse Models of Osteoarthritis: A Summary of Models and Outcomes Assessment.

Osteoarthritis (OA) is a multidimensional health problem and a common chronic disease. It has a substantial impact onpatient quality of life and is a common cause of pain and mobility issues in older adults. The functional limitations, lack of curative treatments, and cost to society all demonstrate the need for translational and clinical research. The use of OA models in mice is important for achieving a better understanding of the disease. Models with clinical relevance are needed to achieve 2 main goals: to assess the impact of the OA disease (pain and function) and to study the efficacy of potential treatments. However, few OA models include practical strategies for functional assessment of the mice. OA signs in mice incorporate complex interrelations between pain and dysfunction. The current review provides a comprehensive compilation of mousemodels of OA and animal evaluations that include static and dynamic clinical assessment of the mice, merging evaluationof pain and function by using automatic and noninvasive techniques. These new techniques allow simultaneous recordingof spontaneous activity from thousands of home cages and also monitor environment conditions. Technologies such as videographyand computational approaches can also be used to improve pain assessment in rodents but these new tools must first be validated experimentally. An example of a new tool is the digital ventilated cage, which is an automated home-cage monitor that records spontaneous activity in the cages.

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Prevalence of trigeminal neuralgia in multiple sclerosis: A systematic review and meta-analysis.

The prevalence of Trigeminal Neuralgia (TN) in patients diagnosed with multiple sclerosis (MS) is insufficiently understood and controversially reported. This study focused on providing a better understanding of the prevalence of TN in MS patients.

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[The care of people with chronic pain benefits greatly from the academization of physiotherapy-the facts speak for themselves].

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Headache, anosmia, ageusia and other neurological symptoms in COVID-19: a cross-sectional study.

Neurological symptoms are frequent among patients with COVID-19. Little is known regarding the repercussions of neurological symptoms for patients and how these symptoms are related to one another.

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Development and Validation of Pediatric Opioid Analgesia Self-Instruction System (PedOASIS): An Opioid Knowledge Tool for Pediatric Clinicians.

Acute pain is common in children and young adults with cancer and sickle cell disease. Current training curricula fail to adequately impart skills for pain management. We sought to develop and validate an education and assessment tool to address the safe effective use of opioids for pain management by pediatrics trainees.

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End-range Maitland mobilization decreasing pain sensitivity in knee osteoarthritis: randomised, controlled clinical trial.

Pressure pain threshold (PPT) is a widely applied method for measuring the magnitude of increased peripheral and central pain sensitivity causing hyperalgesia in knee osteoarthritis (OA). Although manual therapy techniques effects positively PPT, the effect of end-range Maitland mobilization has not been evaluated in knee OA.

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Foot and ankle pain and risk of incident knee osteoarthritis and knee pain: Data from the Multicentre Osteoarthritis Study.

To examine whether foot and/or ankle pain increases the risk of knee OA.

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Impact of transitioning from long-term to intermittent opioid therapy on the development of opioid-related adverse outcomes: A retrospective cohort study.

Increasing pressures exist to reduce or discontinue opioid use among patients currently on long-term opioid therapy (LTOT). It is essential to understand the potential effects of opioid reduction.

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Chronic Pain Clinical and Prescriptive Practices in the Cannabis Era.

To explore how health care providers in the United States are adapting clinical recommendations and prescriptive practices in response to patient use of medical cannabis (MC) for chronic pain symptoms.

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An experimental model of the epithelial to mesenchymal transition and pro-fibrogenesis in urothelial cells related to bladder pain syndrome/interstitial cystitis.

Suitable models are needed to investigate urothelial epithelial to mesenchymal transition (EMT) and pro-fibrogenesis phenotype in bladder pain syndrome/interstitial cystitis (BPS/IC). This study is to establish a novel experimental BPS/IC cell model and explore how different concentrations of tumor necrosis factor (TNF)-α influence the EMT and pro-fibrogenesis phenotype of urothelial cells.

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The Serum Oxidative Stress Biomarkers and Selenium Levels in a Group of Migraine Patients Compared with Healthy Controls: a Case-Control Study.

Migraine is one of the most common neurological disorders associated with recurrent attacks of moderate to severe headache. Oxidative stress may play an important role in migraine pathogenesis. This study aimed to measure and compare the serum levels of Selenium, total antioxidant capacity (TAC), and malondialdehyde) MDA (in migraine patients and healthy individuals. This case-control study was performed on 31 migraine patients and 30 age and gender-matched healthy controls. The severity of headache was assessed with a standard questionnaire, and the serum levels of Selenium (Se), MDA, and TAC were measured via biochemical methods. The odds of migraine were calculated across quartile of Se and oxidative stress biomarkers via binary logistic regression. Migraine patients had a significant lower Se levels (81.06 ± 8.66 vs. 88.94 ± 10.23 μg/L, P = 0.002) and a significant higher MDA levels (3.04 ± 1.74 vs. 2.06 ± 0.59 nmol/ml, P = 0.005) compared to healthy participants. Although serum TAC levels (1.34 ± 0.34 vs.1.37 ± 0.33 mmol/L, P = 0.755) were not significantly different between migraine patients rather than healthy subjects. Individuals in the lowest quartile of Se levels were about eleven times more likely to have migraine than those in the highest quartile (OR: 11.2; 95%CI: 1.57 to 80.2; P-trend: 0.016). Besides, being in the highest quartile of the serum MDA level, the odds of having migraine increases 15.4 times compared to the lowest quartile (OR = 15.4, 95%CI: 1.1 to 221, P = 0.044). No significant association was found between TAC and migraine. The lower Se and MDA levels in migraine patients gives rise to the probability which oxidant status may play an underlying role in migraine pathophysiology.

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Temporal Summation Predicts De Novo Contralateral Pain After Cordotomy in Patients With Refractory Cancer Pain.

Percutaneous cervical cordotomy (PCC), which selectively interrupts ascending nociceptive pathways in the spinal cord, can mitigate severe refractory cancer pain. It has an impressive success rate, with most patients emerging pain-free. Aside from the usual complications of neurosurgical procedures, the risks of PCC include development of contralateral pain, which is less understood.

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Asprosin, a novel therapeutic candidate for painful neuropathy: an experimental study in mice.

Recent studies indicate presence of a strong link between adipokines and neuropathic pain. However, the effects of asprosin, a novel adipokine, on neuropathic pain have not been studied in animal models.Mouse models were employed to investigate the antinociceptive effectiveness of asprosin in the treatment of three types of neuropathic pain, with metabolic (streptozocin/STZ), toxic (oxaliplatin/OXA), and traumatic (sciatic nerve ligation/CCI [chronic constriction nerve injury]) etiologies, respectively. Changes in nociceptive behaviors were assessed relative to controls using thermal (the hot plate and cold plate tests, at 50 °C and 4 °C respectively) and mechanical pain (von Frey test) tests after intraperitoneal (i.p.) administration of asprosin (10 µg/kg) and gabapentin (50 mg/kg) in several times intervals. Besides, possible effect of asprosin on the motor coordination of mice was assessed with a rotarod test. Serum level of asprosin was quantified by ELISA.In neuropathic pain models (STZ, OXA, and CCI), asprosin administration significantly reduced both mechanical and thermal hypersensitivity, indicating that it exhibits a clear-cut antihypersensitivity effect in the analyzed neuropathic pain models. The most effective time of asprosin on pain threshold was observed 60 min after its injection. Also, asprosin displayed no notable effect on the motor activity. Asprosin levels were significantly lower in neuropathic pain compared to healthy group (p < 0.05).The results yielded by the present study suggest that asprosin exhibits an analgesic effect in the neuropathic pain models and may have clinical utility in alleviating chronic pain associated with disease and injury originating from peripheral structures.

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Prolonged exposure for pain and comorbid PTSD: a single-case experimental study of a treatment supplement to multiprofessional pain rehabilitation.

It is unclear how to address PTSD in the context of chronic pain management. Here we examine the potential benefits of an addition of prolonged exposure (PE) therapy for PTSD for adults attending multidisciplinary CBT for chronic pain.

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Mesenchymal Stem Cell Therapy for Osteoarthritis: Practice and Possible Promises.

Osteoarthritis (OA) is a common progressively degenerative joint disease that affects more than 300 million people worldwide. OA is manifested by articular cartilage degradation, chronic pain, deformity, functional disability, and decreased quality of life. A real challenge in OA management is the lack of an effective cure because exiting therapeutics often provide symptom control rather than disease modification; therefore, they fail to prevent disease progression. The inadequate treatments for OA management have encouraged researchers to study mesenchymal stem cells (MSCs) as an investigational treatment for OA. MSCs are a promising tool for OA because of their availability; expand cultivation and multi-lineage differentiation capacity as well as well-documented paracrine function have made MSCs a promising tool in this field. Accordingly, MSCs application has been successfully utilized in a broad range of pre-clinical OA animal models as well as clinical studies with the aim of cartilage repair which had not previously been achieved using classical treatments. Here, the brief scientific review of MSC role in the control of OA as well as the proposed mechanisms are discussed. We provide an insight into the last 10 years' studies conducted on preclinical and clinical OA treatment as well as future opportunities in OA management strategies employing MSCs.

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Systematic Review of the Use of Intravenous Ketamine for Fibromyalgia.

Fibromyalgia, a complex disorder that affects 1% to 5% of the population, presents as widespread chronic musculoskeletal pain without physical or laboratory signs of any specific pathologic process. The mechanism, while still being explored, suggests central sensitization and disordered pain regulation at the spinal cord and supraspinal levels, with a resulting imbalance between excitation and inhibition that may alter central nervous system nociceptive processing. Nociceptive hypersensitivity results from activity of the N-methyl-D-aspartate receptor (NMDAR)-mediated glutamatergic synaptic transmission in the spinal cord and brain. Because ketamine, an NMDAR antagonist, may reduce induction of synaptic plasticity and maintenance of chronic pain states, the study of its use in intravenous form to treat fibromyalgia has increased. We conducted a literature search with the objectives of examining the effect of intravenous ketamine administration on pain relief, identifying side effects, and highlighting the need for clinical studies to evaluate ketamine infusion treatment protocols for patients with fibromyalgia. We used the keywords "fibromyalgia," "chronic pain," "ketamine," "intravenous," and "infusion" and found 7 publications that included 118 patients with fibromyalgia who met inclusion criteria. Clinical studies revealed a short-term reduction-only for a few hours after the infusions-in self-reported pain intensity with single, low-dose, intravenous ketamine infusions, likely attributable to nociception-dependent central sensitization in fibromyalgia via NMDAR blockade. Case studies suggest that increases in the total dose of ketamine and longer, more frequent infusions may be associated with more effective pain relief and longer-lasting analgesia. Another neurotransmitter release may be contributing to this outcome. This systematic review suggests a dose response, indicating potential efficacy of intravenous ketamine in the treatment of fibromyalgia.

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Opioid Use Disorder Treatment Initiation and Continuation: a Qualitative Study of Patients Who Received Addiction Consultation and Hospital-Based Providers.

Hospitalizations related to opioid use disorder (OUD) are rising. Addiction consultation services (ACS) increasingly provide OUD treatment to hospitalized patients, but barriers to initiating and continuing medications for OUD remain. We examined facilitators and barriers to hospital-based OUD treatment initiation and continuation from the perspective of patients and healthcare workers in the context of an ACS.

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Frequent or chronic migraine negatively impacts personal, social and professional life.

INTRODUCTION Migraine affects 16% of the population and is a leading cause of disability. We aimed to describe the treatment status and impact of migraine in a selected cohort of patients with ≥ 4 migraine days per month. METHODS The study was conducted as a large, cross-sectional, multi-country online survey of adults (≥ 18 years) with migraine. Data presented here stem from 306 Danish respondents. Pre-specified quotas were applied so that 90% of respondents had used preventive migraine treatment and 80% had one or more treatment failures. RESULTS The median number of headache days per months was 11.3 (8-17.8) and 89 (29%) of patients met the criteria for chronic migraine. Most patients (n = 213; 70%) had taken preventive treatment (PT) for their migraines and among these 170 (80%) had experienced at least one treatment failure. Ninety-four (44.1%) patients reported being dissatisfied or mostly dissatisfied with their PTs. A negative impact of migraine on either private, social or professional life was reported by 303 (99.0%) patients; and among these, 195 (64.4%) reported an impact in all three domains. CONCLUSIONS Frequent or chronic migraine is associated with a considerable negative impact on personal, social and professional life. Treatment failure is frequent in this patient group, highlighting the need for continuous research and awareness of new treatment possibilities. FUNDING Novartis Pharmaceutical Corporation. TRIAL REGISTRATION not relevant.

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Regional anaesthesia in patients on antithrombotic drugs: Joint ESAIC/ESRA guidelines.

Bleeding is a potential complication after neuraxial and peripheral nerve blocks. The risk is increased in patients on antiplatelet and anticoagulant drugs. This joint guideline from the European Society of Anaesthesiology and Intensive Care and the European Society of Regional Anaesthesia aims to provide an evidence-based set of recommendations and suggestions on how to reduce the risk of antithrombotic drug-induced haematoma formation related to the practice of regional anaesthesia and analgesia.

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Butyric acid modulates periodontal nociception in Porphyromonas gingivalis-induced periodontitis.

Periodontitis progresses with chronic inflammation, without periodontal pain. However, the underlying mechanisms are not well known. Here, the involvement of butyric acid (BA) in periodontal pain sensitivity in Porphyromonas gingivalis (P. gingivalis)-induced periodontitis was examined.

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The relationship between psychosocial factors and reported disability: the role of pain self-efficacy.

Chronic pain and the accompanying level of disability is a healthcare crisis that reaches epidemic proportions and is now considered a world level crisis. Chronic non-specific low back pain (CNLBP) contributes a significant proportion to the chronic pain population. CNLBP occurs with overlapping psychosocial factors. This study was design to investigate specific psychosocial factors and their influence on reported disability in a population with CNLBP.

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Clinical Outcomes after Spinal Cord Stimulation According to Pain Characteristics.

Spinal cord stimulation (SCS) is an effective treatment for chronic neuropathic pain. However, its clinical efficacy in regard to specific types of pain has not been well studied. The primary objective of this study was to retrospectively analyze the clinical outcomes of paddle-type SCS according to the type of neuropathic pain.

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α-Conotoxin RgIA and oligoarginine R8 in the mice model alleviate long-term oxaliplatin induced neuropathy.

Оligoarginines were recently discovered (Lebedev et al., 2019 Nov) [1] as a novel class of nicotinic acetylcholine receptors (nAChRs) inhibitors, octaoligoarginine R8 showing a relatively high affinity (40 nM) for the α9/α10 nAChR. Since the inhibition of α9/α10 nAChR by α-conotoxin RgIA and its analogs is a possible way to drugs against neuropathic pain, here in a mice model we compared R8 with α-conotoxin RgIA in the effects on the chemotherapy-induced peripheral neuropathy (CIPN), namely on the long-term oxaliplatin induced neuropathy. Tests of cold allodynia, hot plate, Von Frey and grip strength analysis revealed for R8 and α-conotoxin RgIA similar positive effects, expressed most prominently after two weeks of administration. Histological analysis of the dorsal root ganglia sections showed for R8 and RgIA a similar partial correction of changes in the nuclear morphology of neurons. Since α9/α10 nAChR might be not the only drug target for R8, we analyzed the R8 action on rat TRPV1 and TRPA1, well-known nociceptive receptors. Against rTRPV1 at 25 μM there was no inhibition, while for rTRPA1 IC was about 20 μM. Thus, involvement of rTRPA1 cannot be excluded, but in view of the R8 much higher affinity for α9/α10 nAChR the latter seems to be the main target and the easily synthesized R8 can be considered as a potential candidate for a drug design.

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Nicotine-induced C-shape movements in planarians are reduced by antinociceptive drugs: implications for pain in planarian paroxysm etiology?

C-shapes are stereotyped movements in planarians that are elicited by diverse stimuli (e.g. acidity, excitatory neurotransmitters, psychostimulants, and pro-convulsants). Muscle contraction and seizure contribute to the expression of C-shape movements, but a causative role for pain is understudied and unclear. Here, using nicotine-induced C-shapes as the endpoint, we tested the efficacy of three classes of antinociceptive compounds – an opioid, NSAID (non-steroidal anti-inflammatory drug), and transient receptor potential ankyrin 1 (TRPA1) channel antagonist. For comparison we also tested effects of a neuromuscular blocker. Nicotine (0.1-10 mM) concentration-dependently increased C-shapes. DAMGO (1-10 µM), a selective µ-opioid agonist, inhibited nicotine (5 mM)-induced C-shapes. Naloxone (0.1-10 µM), an opioid receptor antagonist, prevented the DAMGO (1 µM)-induced reduction of nicotine (5 mM)-evoked C-shapes, suggesting an opioid receptor mechanism. C-shapes induced by nicotine (5 mM) were also reduced by meloxicam (10-100 µM), a NSAID; HC 030031 (1-10 µM), a TRPA1 antagonist; and pancuronium (10-100 µM), a neuromuscular blocker. Evidence that nicotine-induced C-shapes are reduced by antinociceptive drugs from different classes, and require opioid receptor and TRPA1 channel activation, suggest C-shape etiology involves a pain component.

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Cannabis Use for Endometriosis: Clinical and Legal Challenges in Australia and New Zealand.

Endometriosis is a difficult to manage condition associated with a significant disease burden. High levels of illicit cannabis use for therapeutic purposes have been previously reported by endometriosis patients in Australia and New Zealand (NZ). Although access to legal medicinal cannabis (MC) is available through medical prescription via multiple federal schemes, significant barriers to patient access remain. An anonymous cross-sectional online survey was developed and distributed through social media via endometriosis advocacy groups worldwide. Respondents were asked about legal versus illicit cannabis usage, their understanding of access pathways and legal status, and their interactions with health care professionals. Of 237 respondents who reported cannabis use with a medical diagnosis of endometriosis, 186 (72.0%) of Australian and 51 (88.2%) NZ respondents reported self-administering cannabis illicitly. Only 23.1% of Australian and 5.9% of NZ respondents accessed cannabis through a doctor's prescription, with 4.8% of Australian and no NZ respondents reporting to legally self-administer cannabis. Substantial substitution effects (>50% reduction) were observed in users of nonopioid analgesia (63.1%), opioid analgesia (66.1%), hormonal therapies (27.5%), antineuropathics (61.7%), antidepressants (28.2%) and antianxiety medications (47.9%). Of Australian respondents, 18.8% and of NZ respondents, 23.5% reported not disclosing their cannabis use to their medical doctor, citing concern over legal repercussions, societal judgment, or their doctors' reaction and presumed unwillingness to prescribe legal MC. Respondents self-reported positive outcomes when using cannabis for management of endometriosis, demonstrating a therapeutic potential for MC. Despite this, many are using cannabis without medical supervision. While evidence for a substantial substitution effect by cannabis was demonstrated in these data, of particular concern are the clinical consequences of using cannabis without medical supervision, particularly with regard to drug interactions and the tapering or cessation of certain medications without that supervision. Improving doctor and patient communication about MC use may improve levels of medical oversight, the preference for legal MC adoption over acquisition via illicit supply and reducing cannabis-associated stigma.

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Buprenorphine Microdosing for the Pain and Palliative Care Clinician.

Buprenorphine (BUP) can be a safe and effective alternative to traditional opioids for many patients with chronic pain. For patients on higher doses of opioids, rotation to BUP is complicated by the requirement of an opioid-free interval or withdrawal during the transition. Microdosing inductions, in which BUP is gradually titrated, while full agonist opioids are continued, are a viable alternative to traditional inductions. The objective of this article is to review the current literature on BUP microdosing induction, with a focus on patients using opioids for pain. A literature review of the PubMed database was performed in the United States on articles published from inception to May 2021. A total of 34 publications were included. The most commonly utilized microdosing strategy involved administering divided doses of sublingual (SL) products marketed for opioid use disorder treatment, with 25 (73.5%) articles reporting use of partial SL tablets or films (ranging from 1/8 to 1/2 of a 2 mg product) at some point during the induction. Transdermal patches, low-dose SL BUP available in Europe, intravenous BUP, and buccal BUP have also been used. Beyond the products used, the speed of the microinduction, setting, final BUP dosing, and management of concomitant full agonists vary widely in the literature. Microdosing regimens should be individualized based on local guidelines and patient-specific factors. Further studies comparing the safety and efficacy of different protocols are warranted.

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Therapeutic interventions to urologic chronic pelvic pain syndrome and UPOINT system for clinical phenotyping: How far are we?

The assessment and management of urologic chronic pelvic pain syndrome (UCPPS), is controversial. It is classified by voiding symptoms, pelvic pain, and bladder pain, which is weekly treated, weekly understood, and bothersome. In the aspect of clinical efforts and research to help people with this syndrome have been hampered by the deficiency of a widely reliable, accepted, and a valuable tool to evaluate the patient symptoms and quality of life (QoL) impact. However, the etiology comes into sight is multifactorial, and available treatment options have been imprecise considerably in present years. We compiled the published literature on the assessment of the syndrome, a tentative role of pharmacological and non-pharmacological (conservative, alternative, and invasive therapy) interventions in eradicating the disease as well as improving symptoms. The previously published literature on animal models has established the association of immune systems in the etiology, pathogenesis, and progression of the disease. The UPOINT system for clinical phenotyping of UCPPS patients has six predefined domains that direct multimodal therapy, which would lead to significant symptom improvement in the medical field. The narrative review aims to scrutinize the fluctuating scientist's views on the evaluation of patient and multimodal treatment of the UPOINT system.

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The Physical, Psychological, and Social Day-to-Day Experience of Women Living With Endometriosis Compared to Healthy Age-Matched Controls-A Mixed-Methods Study.

Endometriosis is characterized by lesions of endometrial tissue outside the uterus. Chronic pain is considered as main symptom, but challenges can relate to various physical, mental, and social aspects of the women's lives. The aim of our study was to gain a holistic understanding of the everyday reality of women with endometriosis compared to healthy controls. The total sample comprised 12 hormone-free endometriosis patients (EP) and 11 age-matched healthy women (HC). A mixed-methods design was used comprising semi-structured interviews, standardized questionnaires and a comprehensive diary to assess pain ratings and various mental and physical symptoms over the course of a menstrual cycle. Interviews were recorded, transcribed, and evaluated according to phenomenological analysis using the MAXQDA software. Interviews showed that living with endometriosis was associated with an impairment in everyday life. Physical strains, especially pain, high levels of psychological distress, and social limitations have been reported. Living with endometriosis affected the patients' personality and they "no longer felt like themselves." Physical and psychological symptoms were reported to interfere with social interaction and participation. Evaluation of the standardized questionnaires revealed significant impairments in EP compared to HC in regard to anxiety and depression scores (both < 0.001; Hospital Anxiety and Depression Scale), mental and physical quality of life (both < 0.001; Short-Form Health Survey-12), stress ratings ( < 0.001; Patient Health Questionnaire-15) and functional well-being ( < 0.001; Functional Well-being-7). The highest levels of mean pelvic pain and dyschezia were observed in EP during menstruation, but mean pain ratings and dyschezia were increased in EPs compared to HP during the whole cycle. EP reported mental symptoms (e.g., depressed mood or anxiety) mainly during menstruation, while HC did not show any mental symptoms during the cycle. In addition, physical symptoms were elevated during the entire cycle in EPs (all < 0.01). The mixed-methods approach enabled to interpret the interviews, the standardized questionnaires, and the symptom diary in a broader context of everyday life. The symptoms do not appear to act independently, but rather influence each other. This leads to a complex interplay of physical, mental, and social impairments, with pain often being the starting point.

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Pain Management in Acute Pancreatitis: A Systematic Review and Meta-Analysis of Randomised Controlled Trials.

Pain management is an important priority in the treatment of acute pancreatitis (AP). Current evidence and guideline recommendations are inconsistent on the most effective analgesic protocol. This systematic review and meta-analysis of randomised controlled trials (RCTs) aimed to compare the safety and efficacy of analgesics for pain relief in AP. A literature search was performed to identify all RCTs assessing analgesics in patients with AP. The primary outcome was the number of participants who needed rescue analgesia. Study quality was assessed using Jadad score. Pooled odds ratios (ORs) or weighted mean differences (WMDs) with 95% confidence intervals (CI) were analysed using a random-effects model. Twelve studies comprising 699 patients with AP (83% mild AP) were analysed. The tested analgesics significantly decreased the need for rescue analgesia (3 studies, OR.36, 95% CI 0.21 to 0.60) vs. placebo or conventional treatment. The analgesics also improved the pain score [Visual Analogue Scale (Δ-VAS)] at 24 h (WMD 18.46, 0.84 to 36.07) and by the 3rd to 7th days (WMD 11.57, 0.87 to 22.28). Opioids vs. non-opioids were associated with a decrease in the need for rescue analgesia (6 studies, OR 0.25, 95% CI 0.07 to 0.86, = 0.03) but without significance in pain score. In subgroup analyses, opioids were similar to non-steroidal anti-inflammatory drugs (NSAIDs) regarding the primary outcome (4 studies, OR 0.56, 95% CI 0.24 to 1.32, = 0.18). There were no significant differences in other clinical outcomes and rate of adverse events. Other studies, comparing epidural anaesthesia vs. patient-controlled analgesia and opioid (buprenorphine) vs. opioid (pethidine) did not show significant difference in primary outcome. Study quality issues significantly contributed to overall study heterogeneity. NSAIDs and opioids are equally effective in decreasing the need for rescue analgesia in patients with mild AP. The relative paucity of trials and high-quality data in this setting is notable and the optimal analgesic strategy for patients with moderately severe and severe AP still requires to be determined.

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The Convergent Neuroscience of Affective Pain and Substance Use Disorder.

Opioids and alcohol are widely used to relieve pain, with their analgesic efficacy stemming from rapid actions on both spinal and supraspinal nociceptive centers. As an extension of these relationships, both substances can be misused in attempts to manage negative affective symptoms stemming from chronic pain. Moreover, excessive use of opioids or alcohol facilitates the development of substance use disorder (SUD) as well as hyperalgesia, or enhanced pain sensitivity. Shared neurobiological mechanisms that promote hyperalgesia development in the context of SUD represent viable candidates for therapeutic intervention, with the ideal strategy capable of reducing both excessive substance use as well as pain symptoms simultaneously. Neurocognitive symptoms associated with SUD, ranging from poor risk management to the affective dimension of pain, are likely mediated by altered activities of key anatomical elements that modulate executive and interoceptive functions, including contributions from key frontocortical regions. To aid future discoveries, novel and translationally valid animal models of chronic pain and SUD remain under intense development and continued refinement. With these tools, future research strategies targeting severe SUD should focus on the common neurobiology between negative reinforcement and affective elements of pain, possibly by reducing excessive stress hormone and neurotransmitter activity within shared circuitry.

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Innate Receptors Expression by Lung Nociceptors: Impact on COVID-19 and Aging.

The lungs are constantly exposed to non-sterile air which carries harmful threats, such as particles and pathogens. Nonetheless, this organ is equipped with fast and efficient mechanisms to eliminate these threats from the airways as well as prevent pathogen invasion. The respiratory tract is densely innervated by sensory neurons, also known as nociceptors, which are responsible for the detection of external stimuli and initiation of physiological and immunological responses. Furthermore, expression of functional innate receptors by nociceptors have been reported; however, the influence of these receptors to the lung function and local immune response is poorly described. The COVID-19 pandemic has shown the importance of coordinated and competent pulmonary immunity for the prevention of pathogen spread as well as prevention of excessive tissue injury. New findings suggest that lung nociceptors can be a target of SARS-CoV-2 infection; what remains unclear is whether innate receptor trigger sensory neuron activation during SARS-CoV-2 infection and what is the relevance for the outcomes. Moreover, elderly individuals often present with respiratory, neurological and immunological dysfunction. Whether aging in the context of sensory nerve function and innate receptors contributes to the disorders of these systems is currently unknown. Here we discuss the expression of innate receptors by nociceptors, particularly in the lungs, and the possible impact of their activation on pulmonary immunity. We then demonstrate recent evidence that suggests lung sensory neurons as reservoirs for SARS-CoV-2 and possible viral recognition innate receptors. Lastly, we explore the mechanisms by which lung nociceptors might contribute to disturbance in respiratory and immunological responses during the aging process.

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Neuropathic Pain in Multiple Sclerosis and Its Animal Models: Focus on Mechanisms, Knowledge Gaps and Future Directions.

Multiple sclerosis (MS) is a multifaceted, complex and chronic neurological disease that leads to motor, sensory and cognitive deficits. MS symptoms are unpredictable and exceedingly variable. Pain is a frequent symptom of MS and manifests as nociceptive or neuropathic pain, even at early disease stages. Neuropathic pain is one of the most debilitating symptoms that reduces quality of life and interferes with daily activities, particularly because conventional pharmacotherapies do not adequately alleviate neuropathic pain. Despite advances, the mechanisms underlying neuropathic pain in MS remain elusive. The majority of the studies investigating the pathophysiology of MS-associated neuropathic pain have been performed in animal models that replicate some of the clinical and neuropathological features of MS. Experimental autoimmune encephalomyelitis (EAE) is one of the best-characterized and most commonly used animal models of MS. As in the case of individuals with MS, rodents affected by EAE manifest increased sensitivity to pain which can be assessed by well-established assays. Investigations on EAE provided valuable insights into the pathophysiology of neuropathic pain. Nevertheless, additional investigations are warranted to better understand the events that lead to the onset and maintenance of neuropathic pain in order to identify targets that can facilitate the development of more effective therapeutic interventions. The goal of the present review is to provide an overview of several mechanisms implicated in neuropathic pain in EAE by summarizing published reports. We discuss current knowledge gaps and future research directions, especially based on information obtained by use of other animal models of neuropathic pain such as nerve injury.

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Practical Closed-Loop Strategies for Deep Brain Stimulation: Lessons From Chronic Pain.

Deep brain stimulation (DBS) is a plausible therapy for various neuropsychiatric disorders, though continuous tonic stimulation without regard to underlying physiology (open-loop) has had variable success. Recently available DBS devices can sense neural signals which, in turn, can be used to control stimulation in a closed-loop mode. Closed-loop DBS strategies may mitigate many drawbacks of open-loop stimulation and provide more personalized therapy. These devices contain many adjustable parameters that control how the closed-loop system operates, which need to be optimized using a combination of empirically and clinically informed decision making. We offer a practical guide for the implementation of a closed-loop DBS system, using examples from patients with chronic pain. Focusing on two research devices from Medtronic, the Activa PC+S and Summit RC+S, we provide pragmatic details on implementing closed- loop programming from a clinician's perspective. Specifically, by combining our understanding of chronic pain with data-driven heuristics, we describe how to tune key parameters to handle feature selection, state thresholding, and stimulation artifacts. Finally, we discuss logistical and practical considerations that clinicians must be aware of when programming closed-loop devices.

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Gait Adaptation to a Phase-Specific Nociceptive Electrical Stimulation Applied at the Ankle: A Model to Study Musculoskeletal-Like Pain.

Lower limb pain, whether induced experimentally or as a result of a musculoskeletal injury, can impair motor control, leading to gait adaptations such as increased muscle stiffness or modified load distribution around joints. These adaptations may initially reduce pain but can also lead to longer-term maladaptive plasticity and to the development of chronic pain. In humans, many current experimental musculoskeletal-like pain models are invasive, and most don't accurately reproduce the movement-related characteristics of musculoskeletal pain. The main objective of this study was to measure pain adaptation strategies during gait of a musculoskeletal-like experimental pain protocol induced by phase-specific, non-invasive electrical stimulation. Sixteen healthy participants walked on a treadmill at 4 km/h for three consecutive periods (BASELINE, PAIN, and POST-PAIN). Painful electrical stimulations were delivered at heel strike for the duration of heel contact (HC) using electrodes placed around the right lateral malleolus to mimic ankle sprains. Gait adaptations were quantified bilaterally using instrumented pressure-sensitive insoles. One-way ANOVAs and group time course analyses were performed to characterize the impact of electrical stimulation on heel and forefoot contact pressure and contact duration. During the first few painful strides, peak HC pressure decreased on the painful side (8.6 ± 1.0%, < 0.0001) and increased on the non-stimulated side (11.9 ± 0.9%, < 0.0001) while HC duration was significantly reduced bilaterally (painful: 12.1 ± 0.9%, < 0.0001; non-stimulated: 4.8 ± 0.8%, < 0.0001). No clinically meaningful modifications were observed for the forefoot. One minute after the onset of painful stimulation, perceived pain levels stabilized and peak HC pressure remained significantly decreased on the painful side, while the other gait adaptations returned to pre-stimulation values. These results demonstrate that a non-invasive, phase-specific pain can produce a stable painful gait pattern. Therefore, this protocol will be useful to study musculoskeletal pain locomotor adaptation strategies under controlled conditions.

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Remote Delivery of the Chronic Pain Self-management Program Using Self-directed Materials and Small-group Telephone Support: A Pilot Study.

A remote (telephone and tool kit) chronic pain program was studied using the RE-AIM (reach, effectiveness, adoption, implementation, and maintenance) framework. This 6-week pilot took place in underserved communities in Cleveland, Ohio. We determined reach by the diversity of the population, nearly 50% Black and mostly low income. Effectiveness over 7 weeks was shown with validated instruments (depression, pain, sleep, quality of life, self-rated health, and self-efficacy). Changes in pain, depression, and self-efficacy were significant. ( < .01). Remote implementation was accomplished by sending participants a box of materials (book, exercise and relaxation CDs, a self-test, and tip sheets). Participants also participated in peer-facilitated weekly scripted telephone calls. Maintenance was demonstrated as the study site has offered nine additional programs with more plan. In addition, 60 additional organizations are now offering the program. This proof-of-concept study offers an alternate to in-person chronic pain self-management program delivery.

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A Pilot Study Investigating the Role of Gender in the Intergenerational Relationships between Gene Expression, Chronic Pain, and Adverse Childhood Experiences in a Clinical Sample of Youth with Chronic Pain.

Chronic pain is a highly prevalent and costly issue that often emerges during childhood or adolescence and persists into adulthood. Adverse childhood experiences (ACEs) increase risk for several adverse health conditions, including chronic pain. Recent evidence suggests that parental trauma (ACEs, post-traumatic stress disorder (PTSD) symptoms) confers risk of poor health outcomes in their children. Intergenerational relationships between parental trauma and child chronic pain may be mediated by epigenetic mechanisms. A clinical sample of youth with chronic pain and their parents completed psychometrically sound questionnaires assessing ACEs, PTSD symptoms, and chronic pain, and provided a saliva sample. These were used to investigate the intergenerational relationships between four epigenetic biomarkers (COMT, DRD2, GR, and SERT), trauma, and chronic pain. The results indicated that the significant biomarkers were dependent upon the gender of the child, wherein parental ACEs significantly correlated with changes in DRD2 expression in female children and altered COMT expression in the parents of male children. Additionally, the nature of the ACE (maltreatment vs. household dysfunction) was associated with the specific epigenetic changes. There may be different pathways through which parental ACEs confer risk for poor outcomes for males and females, highlighting the importance of child gender in future investigations.

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Opioid use disorder with chronic pain increases disease burden and service use.

To address the ongoing opioid epidemic, there has been an increased focus on the treatment and evaluation of opioid use disorder (OUD). OUD and chronic pain (CP) frequently co-occur; however, little is known about the additional comorbidities that present when they occur together as compared to when either condition presents alone. Using data from Fiscal Year 2012 Veteran's Health Administration, all veterans diagnosed with both OUD + CP were compared to those diagnosed with OUD or CP alone on socioenvironmental characteristics, medical and mental health diagnoses, and Veterans Affairs (VA) clinical service use. Veterans with OUD + CP ( = 33,166), compared to those with OUD only (n = 12,517), had higher numbers of medical conditions. Compared to those with CP only ( = 2,015,368), veterans with OUD + CP had higher rates of homelessness and substance use diagnoses. Most mental health diagnoses, numbers of psychotropic medication fills, opioid prescriptions, and use of all other services were higher in the OUD + CP group than in either single disorder group. Multinomial regression analysis revealed stronger effects for medical disorders and medical-surgical outpatient service use in the comparison of OUD + CP with OUD only and stronger effects for substance use and mental health disorders and use of prescription opiates in the comparison with CP only. These findings suggest that concurrent OUD + CP imposes exceptional disease and clinical service burdens that likely require the development of simultaneous, integrated approaches to treatment. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

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