The association between conditioned pain modulation and psychological factors in people with chronic spinal pain: A systematic review

Chronic spinal pain has negative effects on physical and mental well-being. Psychological factors can influence pain tolerance. However, whether these factors influence descending modulatory control mechanisms measured by conditioned pain modulation (CPM) in people with chronic spinal pain is unclear. This systematic review investigated the association between CPM response and psychological factors in people with chronic spinal pain. Published and unpublished literature databases were searched from inception to 23rd October 2023 included MEDLINE, EMBASE, CINAHL, and PubMed. Studies assessing the association between CPM response and psychological factors in people with chronic spinal pain were eligible. Data were pooled through meta-analysis. Methodological quality was assessed using the AXIS tool and the certainty of evidence measured through GRADE. From 2172 records, seven studies (n = 598) were eligible. Quality of included studies was moderate. There was very low certainty of evidence that depression (r = 0.01 [95% CI -0.10 to 0.12], I2 = 0%), and anxiety (r = -0.20 [95% CI -0.56 to 0.16], I2 = 84%), fear avoidance (r = -0.10 [95% CI -0.30 to 0.10], I2 = 70%) had no statistical associations with CPM responder status. Higher pain catastrophising was associated with CPM non-responder status (r = -0.19; 95% CI: -0.37 to -0.02; n = 545; I2: 76%) based on a very low certainty of evidence measured by GRADE. There is currently limited available evidence demonstrating an association between CPM response and psychological factors for people with chronic pain. Managing an individual's chronic pain symptoms irrespective of comorbid psychological distress, should continue until evidence offer insights that more targeted interventions are needed.

Attention and Interoception Alter Perceptual and Neural Pain Signatures-A Case Study

Introduction

Fluctuations of chronic pain levels are determined by a complex interplay of cognitive, emotional and perceptual variables. We introduce a pain tracking platform composed of wearable neurotechnology and a smartphone application to measure and predict chronic pain levels and its interplay with other dimensions of experience.

Methods

Our method measures, dynamically and at home, pain strength, phenomenal and neural time series collected with an online tool and low-density EEG. Here we used data from a single participant who performed an attention task at home for a period of 20 days to investigate the role of attention to different bodily systems in chronic pain.

Results

We show a relationship between emotions and pain strength while allocating attention to the heartbeat, the breathing, the affected or the unaffected limb. We found that pain was maximal when attending to the affected limb and decreased when the participant focused on his breathing or his heartbeat. These results provide interesting insights regarding the role of attention to interoceptive signals in chronic pain. We found power changes in the delta, theta, alpha and beta (but not in the gamma) band between the four attention conditions. However, there was no reliable association of these changes to pain intensity ratings. Theta power was higher when attention was directed to the unaffected limb compared to the others. Further, the pain ratings, when attending to unaffected limb, were associated with alpha and theta power band changes.

Conclusion

Overall, we demonstrate that our neurophysiology and experience tracking platform can capture how body attention allocation alters the dynamics of subjective measures and its neural correlates. This research approach is proof of concept for the development of personalized clinical assessment tools and a testbed for behavioural, subjective and biomarkers characterization.

Statistical learning shapes pain perception and prediction independently of external cues

The placebo and nocebo effects highlight the importance of expectations in modulating pain perception, but in everyday life we don't need an external source of information to form expectations about pain. The brain can learn to predict pain in a more fundamental way, simply by experiencing fluctuating, non-random streams of noxious inputs, and extracting their temporal regularities. This process is called statistical learning. Here, we address a key open question: does statistical learning modulate pain perception? We asked 27 participants to both rate and predict pain intensity levels in sequences of fluctuating heat pain. Using a computational approach, we show that probabilistic expectations and confidence were used to weigh pain perception and prediction. As such, this study goes beyond well-established conditioning paradigms associating non-pain cues with pain outcomes, and shows that statistical learning itself shapes pain experience. This finding opens a new path of research into the brain mechanisms of pain regulation, with relevance to chronic pain where it may be dysfunctional.

Could Relationship-Based Learnt Beliefs and Expectations Contribute to Physiological Vulnerability of Chronic Pain? Making a Case to Consider Attachment in Pain Research

Pain is an interpersonal and inherently social experience. Pain perception and administration of medical treatment all occur in a particular environmental and social context. Early environmental influences and early learning experiences and interactions condition the body's response to different threats (like pain), ultimately shaping the underlying neurophysiology. These early interactions and experiences also determine what situations are perceived as threatening, as well as our belief in our own ability to self-manage, and our belief in others to offer support, during perceived threats. These beliefs intrinsically drive the combination of behaviors that emerge in response to perceived threats, including pain. Such behaviors can be categorized into attachment styles. In this interdisciplinary review, we synthesize and summarize evidence from the neurobiological, psychobiological, psychosocial, and psychobehavioral fields, to describe how these beliefs are embedded in the brain's prediction models to generate a series of expectations/perceptions around the level of safety/threat in different contexts. As such, these beliefs may predict how one experiences and responds to pain, with potentially significant implications for the development and management of chronic pain. Little attention has been directed to the effect of adult attachment style on pain in research studies and in the clinical setting. Using interdisciplinary evidence, we argue why we think this interaction merits further consideration and research. PERSPECTIVE: This review explores the influence of attachment styles on pain perception, suggesting a link between social connections and chronic pain development. It aligns with recent calls to emphasize the social context in pain research and advocates for increased focus on adult attachment styles in research and clinical practice.

Reliability of task-based fMRI in the dorsal horn of the human spinal cord

The application of functional magnetic resonance imaging (fMRI) to the human spinal cord is still a relatively small field of research and faces many challenges. Here we aimed to probe the limitations of task-based spinal fMRI at 3T by investigating the reliability of spinal cord blood oxygen level dependent (BOLD) responses to repeated nociceptive stimulation across two consecutive days in 40 healthy volunteers. We assessed the test-retest reliability of subjective ratings, autonomic responses, and spinal cord BOLD responses to short heat pain stimuli (1s duration) using the intraclass correlation coefficient (ICC). At the group level, we observed robust autonomic responses as well as spatially specific spinal cord BOLD responses at the expected location, but no spatial overlap in BOLD response patterns across days. While autonomic indicators of pain processing showed good-to-excellent reliability, both β-estimates and z-scores of task-related BOLD responses showed poor reliability across days in the target region (gray matter of the ipsilateral dorsal horn). When taking into account the sensitivity of gradient-echo echo planar imaging (GE-EPI) to draining vein signals by including the venous plexus in the analysis, we observed BOLD responses with fair reliability across days. Taken together, these results demonstrate that heat pain stimuli as short as one second are able to evoke a robust and spatially specific BOLD response, which is however strongly variable within participants across time, resulting in low reliability in the dorsal horn gray matter. Further improvements in data acquisition and analysis techniques are thus necessary before event-related spinal cord fMRI as used here can be reliably employed in longitudinal designs or clinical settings.

Effects of mindfulness-based preoperative intervention for patients undergoing elective surgery: A meta-analysis

OBJECTIVE

Patients often experience pain and psychological distress when undergoing elective surgeries. Mindfulness-based interventions have been proposed as potential strategies to address these challenges. This meta-analysis aims to evaluate the efficacy of preoperative mindfulness-based interventions on several outcomes for patients undergoing elective surgery, including preoperative anxiety/depression, postoperative anxiety/depression, postoperative pain, and quality of life (QOL).

METHODS

This meta-analysis encompassed randomized controlled trials published in the database PubMed, Cochrane, and Embase to August 2023. Mindfulness-based interventions were compared to control groups, who received treatment as usual (TAU). The RevMan software was employed to assess each outcome by using standardized mean difference based on patient-reported data. Subgroup analyses were further performed according to different categories of surgical types.

RESULTS

Eight RCTs with a total of 685 patients were identified. This meta-analysis demonstrated significant difference in preoperative anxiety (SMD:-0.36, 95% CI: -0.62 to -0.11, p = .006) and postoperative pain immediately (SMD:-0.65,95% CI: -1.09 to -0.20, p = .004), 2-3 days (SMD:-0.40, 95% CI:-0.78 to -0.02, p = .04),at 14 days (SMD:-0.48,95% CI: -0.85 to -0.12, p = .009) and 28 days (SMD:-0.89,95% CI: -1.55 to -0.23, p = .008) postoperatively. However, there were no differences between postoperative anxiety, preoperative/postoperative depression, and QOL.

CONCLUSION

Our findings suggest preoperative mindfulness-based interventions can effectively manage preoperative anxiety and postoperative pain in patients scheduled for elective surgery. Further research is warranted to explore the different timing and types of mindfulness-based intervention.

Pain perception as hierarchical Bayesian inference: A test case for the theory of constructed emotion

An intriguing perspective about human emotion, the theory of constructed emotion considers emotions as generative models according to the Bayesian brain hypothesis. This theory brings fresh insight to existing findings, but its complexity renders it challenging to test experimentally. We argue that laboratory studies of pain could support the theory because although some may not consider pain to be a genuine emotion, the theory must at minimum be able to explain pain perception and its dysfunction in pathology. We review emerging evidence that bear on this question. We cover behavioral and neural laboratory findings, computational models, placebo hyperalgesia, and chronic pain. We conclude that there is substantial evidence for a predictive processing account of painful experience, paving the way for a better understanding of neuronal and computational mechanisms of other emotions.

Patient Expectations and Therapeutic Alliance Affect Pain Reduction Following Lidocaine Infusion in an Interdisciplinary Chronic Pain Clinic

Pain experience is affected by both ascending nociceptive signals and descending modulation. Expectations can affect pain experience and augment treatment-induced analgesia through descending inhibitory modulation of pain. This open-label, prospective cohort study examined the association between participant expectation ratings and pain reduction in adult participants with chronic pain receiving an intravenous lidocaine infusion. We aimed to explore whether: 1) participants' expectations of treatment efficacy were associated with pain reduction over 8 weeks after infusion; and 2) participants' therapeutic alliance was associated with expectations and/or pain reduction. We recruited 70 participants with chronic pain scheduled for lidocaine infusion. Study measures included pain intensity (pre-treatment, post-treatment, and daily for 8 weeks), treatment expectations (EXPECT), and therapeutic alliance (Trust in Physician and Working Alliance Inventory-Short Revised). Baseline treatment expectations were significantly correlated with pain reduction (r = .42, P < .01). Therapeutic alliance was significantly correlated with expectations (r = .27, P < .05) and pain reduction (r = .38, P < .01). This study quantifies the contribution of: 1) treatment expectations; and 2) therapeutic alliance to the magnitude of lidocaine-induced pain reduction. Results generate the hypothesis that focused efforts to augment treatment expectations and therapeutic alliance could serve to improve pain treatment outcomes. PERSPECTIVE: This study evaluates the relationship between pain reduction and ratings of: 1) treatment expectations; and 2) therapeutic alliance following an intravenous lidocaine infusion. Results generate the hypothesis that focused efforts to augment treatment expectations and therapeutic alliance could serve to improve pain treatment outcomes.

Localizing somatic symptoms associated with childhood maltreatment

Childhood maltreatment has been linked to adult somatic symptoms, although this has rarely been examined in daily life. Furthermore, the localization of somatization associated with childhood maltreatment and its subtypes is unknown. This large-scale experience sampling study used body maps to examine the relationships between childhood maltreatment, its subtypes, and the intensity and location of negative somatic sensations in daily life. Participants (N = 2,234; 33% female and 67% male) were part of MyBPLab 2.0, a study conducted using a bespoke mobile phone application. Four categories of childhood maltreatment (emotional abuse, emotional neglect, physical abuse, and physical neglect) were measured using the Childhood Trauma Questionnaire. Using gender-matched human silhouettes, participants indicated the location and intensity of feelings of negative activation in the body. Childhood maltreatment generally and its four measured subtypes were all positively associated with heightened negative activation on both the front and back body maps. For females, total childhood maltreatment was associated with negative activation in the abdomen and lower back, while for males, the association was localized to the lower back. Similarly, each of the four subscales had localized associations with negative activation in the abdomen and lower back in females and lower back in males, except for emotional abuse, which was also associated with negative activation in the abdomen in males. These associations likely reflect increased somatization in individuals exposed to childhood maltreatment, suggesting a role for psychotherapeutic interventions in alleviating associated distress.

Updating beliefs about pain following advice: Trustworthiness of social advice predicts pain expectations and experience

Prior expectations influence pain experience. These expectations, in turn, rely on prior pain experience, but they may also be socially influenced. Yet, most research has focused on self rather than social expectations about pain, and hardly any studies examined their combined effects on pain. Here, we adopted a Bayesian learning perspective to investigate how explicitly communicated social expectations ('advice about pain tolerance') affect own pain expectations, and ultimately pain tolerance, under varying conditions of social epistemic uncertainty (trustworthiness of the advice). N = 72 female participants took part in a coldpressor (cold water) task before (self-learning baseline) and after (socially-influenced learning) receiving advice about their likely pain tolerance from a confederate, the trustworthiness of whom was experimentally manipulated. We used path analysis to test the hypothesis that social advice from a highly trustworthy confederate would influence participants' expectations about pain more than advice from a less trustworthy source, and that the degree of this social influence would in turn predict pain tolerance. We further used a simplified, Bayesian learning, computational approach for explicit belief updating to examine the role of latent parameters of precision optimisation in how participants subsequently changed their future pain expectations (prospective posterior beliefs) based on the combined effect of the confederate's advice on their own pain expectations, and their own task experience. Results confirmed that participants adjusted their pain expectations towards the confederate's advice more in the high- vs. low-trustworthiness condition, and this advice taking predicted their pain tolerance. Furthermore, the confederate's trustworthiness influenced how participants weighted the confederate's advice in relation to their own expectations and task experience in forming prospective posterior beliefs. When participants received advice from a less trustworthy confederate, their own sensory experience was weighted more highly than their socially-influenced prior expectations. Thus, explicit social advice appears to impact pain by influencing one's own pain expectations, but low social trustworthiness leads to these expectations becoming more malleable to novel, sensory learning.

Racial Differences in Movement-Related Appraisals and Pain Behaviors Among Adults With Chronic Low Back Pain

Research documents racial disparities in chronic low back pain (CLBP). Few studies have examined racial disparities in movement-related appraisals and no studies have examined anticipatory appraisals prior to or pain behaviors during functional activities among individuals with CLBP. This cross-sectional study examined racial differences in anticipatory appraisals of pain, concerns about harm, and anxiety, appraisals of pain and anxiety during movement, and observed pain behaviors during 3 activities of daily living (supine-to-standing bed task, sitting-to-standing chair task, floor-to-waist lifting task) in a sample (N = 126) of non-Hispanic Black (31.0%), Hispanic (30.2%), and non-Hispanic White (38.9%) individuals with CLBP. Hispanic participants reported more expected pain, concerns about harm, and pre-movement anxiety prior to the bed and chair tasks compared to non-Hispanic White participants. Hispanic participants reported more pain during the bed task and more anxiety during the bed and chair tasks compared to non-Hispanic White participants. Non-Hispanic Black participants reported more expected pain, concerns about harm, and pre-movement anxiety prior to the bed task and more pre-movement anxiety prior to the chair task compared to non-Hispanic White participants. Non-Hispanic Black participants reported more anxiety during the bed and chair tasks compared to non-Hispanic White participants. Non-Hispanic Black participants were observed to have significantly more verbalizations of pain during the bed task compared to non-Hispanic White participants. Current findings identify racial disparities in important cognitive-behavioral and fear-avoidance mechanisms of pain. Results indicate a need to revisit traditional theoretical and treatment models in CLBP, ensuring racial disparities in pain cognitions are considered. PERSPECTIVE: This study examined racial disparities in anticipatory and movement-related appraisals, and pain behaviors during activities of daily living among Non-Hispanic Black, Non-Hispanic White, and Hispanic individuals with CLBP. Racial disparities identified in the current study have potentially important theoretical implications surrounding cognitive-behavioral and fear-avoidance mechanisms of pain.

Mimicking opioid analgesia in cortical pain circuits

The anterior cingulate cortex plays a pivotal role in the cognitive and affective aspects of pain perception. Both endogenous and exogenous opioid signaling within the cingulate mitigate cortical nociception, reducing pain unpleasantness. However, the specific functional and molecular identities of cells mediating opioid analgesia in the cingulate remain elusive. Given the complexity of pain as a sensory and emotional experience, and the richness of ethological pain-related behaviors, we developed a standardized, deep-learning platform for deconstructing the behavior dynamics associated with the affective component of pain in mice-LUPE (Light aUtomated Pain Evaluator). LUPE removes human bias in behavior quantification and accelerated analysis from weeks to hours, which we leveraged to discover that morphine altered attentional and motivational pain behaviors akin to affective analgesia in humans. Through activity-dependent genetics and single-nuclei RNA sequencing, we identified specific ensembles of nociceptive cingulate neuron-types expressing mu-opioid receptors. Tuning receptor expression in these cells bidirectionally modulated morphine analgesia. Moreover, we employed a synthetic opioid receptor promoter-driven approach for cell-type specific optical and chemical genetic viral therapies to mimic morphine's pain-relieving effects in the cingulate, without reinforcement. This approach offers a novel strategy for precision pain management by targeting a key nociceptive cortical circuit with on-demand, non-addictive, and effective analgesia.

[Does patient communication influence kinesiophobia? A systematic review]

The aim of the present systematic review was to determine the effect of communication in the health care setting on kinesiophobia. To this end, a literature search was conducted in seven databases between November 2022 and February 2023. The review was carried out following the PRISMA statement and for the analysis of methodological quality we used: PEDro Scale, Van Tulder criteria and risk of bias analysis of the Cochrane Collaboration. A total of 13 articles were included with a mean methodological quality of 7.1 out of 10. Significant results were obtained for at least one variable (kinesiophobia, disability or level of physical activity) in 12 articles. There is strong evidence that communication can influence a subject's kinesiophobia. This influence is most likely to be in a negative or disabling sense, but it can also act in a positive sense by decreasing it.

The role of histamine H1 receptor in the anterior cingulate cortex on nociception level following acute restraint stress in male rats

Considering the importance of pain and stress, we decided to investigate the intra-anterior cingulate cortex (ACC) microinjection of histamine and mepyramine alone and concurrently on acute pain induced by hot plate following restraint stress in male rats. 24-gauge, 10 mm stainless steel guide cannula was implanted over the ACC in the incised scalp of 4 groups. Restraint stress in healthy rats produced a significant increase (p < .05) in the pain threshold. The simultaneous microinjection of 4 μg/side histamine and 8 μg/side mepyramine as a histaminergic system inverse agonist in healthy nonrestraint animals did not affect the pain threshold. Although Histamine decreased the threshold of pain meaningfully, mepyramine elevated it in a significant manner (p < .05). In the restrained animals, intra-ACC microinjection of histamine produced no significant impact on the pain threshold. However, intra-ACC microinjection of mepyramine before histamine, significantly (p < .01) altered the result and enhanced the threshold of pain. The results of our study demonstrated that histaminergic neurons have an important role in the processing of pain in the ACC following restraint stress.

Electric massage chairs reduce labor pain in nulliparous patients: a randomized crossover trial

BACKGROUND

Labor pain varies significantly among pregnant women, ranging from mild to extremely distressing. Nonpharmacologic pain relief methods during vaginal birth are increasingly popular, either as a complement to pharmacologic agents or, at times, as the primary method of pain relief. Multiple trials have reported that manual or by-hand massage reduces labor pain. The effectiveness of full-body mechanical massage using electric massage chairs on labor pain remains unexplored.

OBJECTIVE

This study aimed to evaluate mechanical massage using an electric massage chair on labor pain in nulliparous women.

STUDY DESIGN

A randomized counterbalanced crossover trial was conducted in a university hospital in Malaysia from August 2022 to February 2023. Eligible nulliparas in labor with a minimum labor pain score of 5 (0-10 numerical rating scale) were enrolled. Participants were randomized to 30 minutes on the massage chair with mechanical massage followed by 30 minutes on the massage chair without mechanical massage or the other way around in the massage sequence. The primary outcome was a change in pain score comparing pain with and without mechanical massage as a paired comparison for the entire trial participants. The secondary outcomes were across arms analyses of maternal and neonatal outcomes. The paired t test, t test, Mann-Whitney U test, chi-square test, and Fisher exact test were used as appropriate for the data.

RESULTS

Overall, 208 women were randomized: 104 to each intervention. Data were available from 204 participants (103 randomized to massage first and 101 to no massage first). The primary outcomes of change in labor pain scores (0-10 numerical rating scale) after massage and no massage (all participants included after crossover, paired t test analysis) were 4.51±2.30 and 5.38±2.10, respectively (mean difference, -0.87; 95% confidence interval, -1.14 to -0.59; P<.001), a significant reduction in pain score after electric chair mechanical massage compared with no massage. On the across randomized arms secondary analyses, labor pain scores after their first massage chair session were 4.35±2.52 (randomized to massage first, received massage as initial intervention) and 5.66±1.73 (randomized to no massage first, received no massage as initial intervention) (mean difference, -1.31; 95% confidence interval, -1.91 to -0.748; P<.001), a significant reduction after mechanical massage. Other distal maternal outcomes (mode of delivery, labor analgesia, duration of labor, and maternal agreement that mechanical massage is effective for labor pain) and neonatal outcomes (Apgar scores at 1 and 5 minutes, cord artery blood pH and base excess, and neonatal admission) were not different across randomized arms.

CONCLUSION

Mechanical massage using an electric massage chair significantly reduced labor pain, offering a potential nonpharmacologic pain management option during labor.

Landau model for illustrating the learning and unlearning process of nociplastic pain

Recent advancements in understanding the consolidation of nociplastic pain point to a complex, non-conscious learned process of threat perception. Neurobiological pain education is emerging as a promising approach to unlearn nociplastic pain, supported by biopsychosocial tools such as exposure to movement, mindfulness, and group sharing formats. However, this approach is still not well-known among clinicians and the society at large, creating a communication problem that unfortunately perpetuates the suffering of patients. Herein, we propose a Landau model to describe the learning and unlearning process of nociplastic pain, aiming to clarify this complex situation and facilitate communication across different sectors of the society. Nociplastic pain corresponds to a first-order transition, with attention more likely in the alert-protection state than in the trust-explore state. Two appealing results of the model are that the perception of the critical context depends on personal history regarding the symptom and that biopsychosocial loops are formed when there is alarming learned historical information about the symptom, along with confused and contradictory expert information, as seen in nocebo messages. Learning and unlearning in the model correspond to a chang in control parametrs that can weigh more on the alert-protection state, trust-explore state, uncertain state or neutral state. This description clarifies why neurobiological education is the foundational therapy from which others must be built to embody the accessible, clear, and trustworthy information.

Brain Plasticity in Patients with Spinal Cord Injuries: A Systematic Review

A spinal cord injury (SCI) causes changes in brain structure and brain function due to the direct effects of nerve damage, secondary mechanisms, and long-term effects of the injury, such as paralysis and neuropathic pain (NP). Recovery takes place over weeks to months, which is a time frame well beyond the duration of spinal shock and is the phase in which the spinal cord remains unstimulated below the level of injury and is associated with adaptations occurring throughout the nervous system, often referred to as neuronal plasticity. Such changes occur at different anatomical sites and also at different physiological and molecular biological levels. This review aims to investigate brain plasticity in patients with SCIs and its influence on the rehabilitation process. Studies were identified from an online search of the PubMed, Web of Science, and Scopus databases. Studies published between 2013 and 2023 were selected. This review has been registered on OSF under (n) 9QP45. We found that neuroplasticity can affect the sensory-motor network, and different protocols or rehabilitation interventions can activate this process in different ways. Exercise rehabilitation training in humans with SCIs can elicit white matter plasticity in the form of increased myelin water content. This review has demonstrated that SCI patients may experience plastic changes either spontaneously or as a result of specific neurorehabilitation training, which may lead to positive outcomes in functional recovery. Clinical and experimental evidence convincingly displays that plasticity occurs in the adult CNS through a variety of events following traumatic or non-traumatic SCI. Furthermore, efficacy-based, pharmacological, and genetic approaches, alone or in combination, are increasingly effective in promoting plasticity.

The prevalence of chronic pain in adolescents in Central Switzerland: A cross- sectional school-based study protocol

BACKGROUND

Chronic pain is associated with substantial personal suffering and societal costs and is a growing healthcare concern worldwide. While chronic pain has been extensively studied in adults, limited data exists on its prevalence and impact in adolescents. Understanding the prevalence and impact of chronic pain and pain beliefs in adolescents is crucial for developing effective prevention and treatment strategies. This study aims to estimate the prevalence, characteristics, and impact of chronic pain, and explore adolescents' knowledge and beliefs about pain.

METHODS

This is an observational cohort study of school-going adolescents aged 11 to 17 years in Central Switzerland. The study will estimate the point prevalence, characteristics (location, intensity, frequency, duration) and impact (PROMIS Pediatric Short Form v2.0 -Pain Interference Scale, PPIS) of chronic pain in school-going adolescents. We will also measure and investigate pupils' beliefs about pain (Concept of Pain Inventory (COPI)). Data will be collected through manual and digital self-report questionnaires and from participants in primary, secondary, and high schools between September 2023 and January 2024.

ANALYSES

The primary analyses will utilise descriptive statistics to estimate the point prevalence, characteristics, and impact of chronic pain. Secondary analyses will analyse associations and correlations between chronic pain, impact of pain and beliefs about pain.

OUTCOMES

This study will provide an estimate of the prevalence, characteristics and impact of chronic pain in adolescents in Central Switzerland and a measure of adolescents' understanding and beliefs about pain. In doing so, this study will provide insights into the scale of chronic pain as a public health concern. By understanding adolescents' pain beliefs and their influence on pain experience, this study can contribute to the development of educational approaches to enhance adolescents' knowledge and understanding of pain in order to optimise the prevention and treatment of chronic pain in adolescents. The findings may be useful to healthcare professionals and funders, policymakers, and researchers involved in the prevention, assessment, and treatment of pain in adolescents.

Spatial summation of pain is associated with pain expectations: Results from a home-based paradigm

The purpose of this study was to reproduce the previously observed spatial summation of pain effect (SSp) using non-laboratory procedures and commercial equipment. An additional aim was to explore the association between expectations and SSp. The Cold Pressor Task (CPT) was used to induce SSp. Healthy participants (N = 68) immersed their non-dominant hands (divided into 5 segments) into cold water (CPT). Two conditions were used 1) gradual hand immersion (ascending condition) and 2) gradual hand withdrawal (descending condition). Pain intensity was measured on a Visual Analogue Scale (VAS). Psychological factors, such as the participants' expectations of pain intensity were also measured on a VAS. Results showed significant SSp (χ2(4) = 116.90, p < 0.001), reproduced with non-laboratory equipment in a home-based set-up. Furthermore, two novel findings were observed: i) there was a significant correlation between expectations and perceived pain, indicating a link between pain expectations and SSp, ii) spatial summation increased with the increase in duration exposure to the noxious stimulus (Wald χ2(8) = 80.80, p < 0.001). This study suggests that SSp is associated with pain expectations and can be formed by a mixture of excitatory and inhibitory mechanisms potentially driven by temporal characteristics of neural excitation. Moreover, this study proposes a new feasible way to induce SSp using a home-based set-up.

Systems genetics analysis reveals the common genetic basis for pain sensitivity and cognitive function

BACKGROUND

There is growing evidence of a strong correlation between pain sensitivity and cognitive function under both physiological and pathological conditions. However, the detailed mechanisms remain largely unknown. In the current study, we sought to explore candidate genes and common molecular mechanisms underlying pain sensitivity and cognitive function with a transcriptome-wide association study using recombinant inbred mice from the BXD family.

METHODS

The pain sensitivity determined by Hargreaves' paw withdrawal test and cognition-related phenotypes were systematically analyzed in 60 strains of BXD mice and correlated with hippocampus transcriptomes, followed by quantitative trait locus (QTL) mapping and systems genetics analysis.

RESULTS

The pain sensitivity showed significant variability across the BXD strains and co-varies with cognitive traits. Pain sensitivity correlated hippocampual genes showed a significant involvement in cognition-related pathways, including glutamatergic synapse, and PI3K-Akt signaling pathway. Moreover, QTL mapping identified a genomic region on chromosome 4, potentially regulating the variation of pain sensitivity. Integrative analysis of expression QTL mapping, correlation analysis, and Bayesian network modeling identified Ring finger protein 20 (Rnf20) as the best candidate. Further pathway analysis indicated that Rnf20 may regulate the expression of pain sensitivity and cognitive function through the PI3K-Akt signaling pathway, particularly through interactions with genes Ppp2r2b, Ppp2r5c, Col9a3, Met, Rps6, Tnc, and Kras.

CONCLUSIONS

Our study demonstrated that pain sensitivity is associated with genetic background and Rnf20-mediated PI3K-Akt signaling may involve in the regulation of pain sensitivity and cognitive functions.

Alcohol use and the pain system

The World Health Organization's epidemiological data from 2016 revealed that while 57% of the global population aged 15 years or older had abstained from drinking alcohol in the previous year, more than half of the population in the Americas, Europe, and Western Pacific consumed alcohol. The spectrum of alcohol use behavior is broad: low-risk use (sensible and in moderation), at-risk use (e.g., binge drinking), harmful use (misuse) and dependence (alcoholism; addiction; alcohol use disorder). The at-risk use and misuse of alcohol is associated with the transition to dependence, as well as many damaging health outcomes and preventable causes of premature death. Recent conceptualizations of alcohol dependence posit that the subjective experience of pain may be a significant contributing factor in the transition across the spectrum of alcohol use behavior. This narrative review summarizes the effects of alcohol at all levels of the pain system. The pain system includes nociceptors as sensory indicators of potentially dangerous stimuli and tissue damage (nociception), spinal circuits mediating defensive reflexes, and most importantly, the supraspinal circuits mediating nocifensive behaviors and the perception of pain. Although the functional importance of pain is to protect from injury and further or future damage, chronic pain may emerge despite the recovery from, and absence of, biological damage (i.e., in the absence of nociception). Like other biological perceptual systems, pain is a construction contingent on sensory information and a history of individual experiences (i.e., learning and memory). Neuroadaptations and brain plasticity underlying learning and memory and other basic physiological functions can also result in pathological conditions such as chronic pain and addiction. Moreover, the negative affective/emotional aspect of pain perception provides embodied and motivational components that may play a substantial role in the transition from alcohol use to dependence.

Neural correlates of word processing influenced by painful primes

The administration of painful primes has been shown to influence the perception of successively presented semantic stimuli. Painful primes lead to more negative valence ratings of pain-related, negative, and positive words than no prime. This effect was greater for pain-related than negative words. The identities of this effect's neural correlates remain unknown. In this EEG experiment, 48 healthy subjects received noxious electrical stimuli of moderate intensity. During this priming, they were presented with adjectives of variable valence (pain-related, negative, positive, and neutral). The triggered event-related potentials were analyzed during N1 (120-180 ms), P2 (170-260 ms), P3 (300-350 ms), N400 (370-550 ms), and two late positive complex components (LPC1 [650-750 ms] and LPC2 [750-1000 ms]). Larger event-related potentials were found for negative and pain-related words compared to positive words in later components (N400, LPC1, and LPC2), mainly in the frontal regions. Early components (N1, P2) were less affected by the word category but were by the prime condition (N1 amplitude was smaller with than without painful stimulation, P2 amplitude was larger with than without painful stimulation). Later components (LPC1, LPC2) were not affected by the prime condition. An interaction effect involving prime and word category was found on the behavioral level but not the electrophysiological level. This finding indicates that the interaction effect does not directly translate from the behavioral to the electrophysiological level. Possible reasons for this discrepancy are discussed.

SOMAScience: A Novel Platform for Multidimensional, Longitudinal Pain Assessment

Chronic pain is one of the most significant health issues in the United States, affecting more than 20% of the population. Despite its contribution to the increasing health crisis, reliable predictors of disease development, progression, or treatment outcomes are lacking. Self-report remains the most effective way to assess pain, but measures are often acquired in sparse settings over short time windows, limiting their predictive ability. In this paper, we present a new mobile health platform called SOMAScience. SOMAScience serves as an easy-to-use research tool for scientists and clinicians, enabling the collection of large-scale pain datasets in single- and multicenter studies by facilitating the acquisition, transfer, and analysis of longitudinal, multidimensional, self-report pain data. Data acquisition for SOMAScience is done through a user-friendly smartphone app, SOMA, that uses experience sampling methodology to capture momentary and daily assessments of pain intensity, unpleasantness, interference, location, mood, activities, and predictions about the next day that provide personal insights into daily pain dynamics. The visualization of data and its trends over time is meant to empower individual users' self-management of their pain. This paper outlines the scientific, clinical, technological, and user considerations involved in the development of SOMAScience and how it can be used in clinical studies or for pain self-management purposes. Our goal is for SOMAScience to provide a much-needed platform for individual users to gain insight into the multidimensional features of their pain while lowering the barrier for researchers and clinicians to obtain the type of pain data that will ultimately lead to improved prevention, diagnosis, and treatment of chronic pain.

Methodological advice for the young at heart investigator: Triangulation to build better foundations

In medicine and science, one is typically taught the main theories in a discipline or field along with standard models before receiving more instructions on how to apply certain methods. The aim of this work is not to address one method, but rather methodology, the study and evaluation of methods, by taking a philosophy of science detour. In this, a critique of biomedicine will be used as a starting point to address some positions regarding reductionism, specifying notions such as systems and mechanisms, as well as regarding the mind-body problem discussing psychosomatic medicine and psychoneuroimmunology. Some recommendations to make science more pluralistic, robust and translationally-relevant will then be made as a way to foster constructive debates on reductionism and the mind-body problem and, in turn, favor more interdisciplinary research.

Low-frequency electroacupuncture exerts antinociceptive effects through activation of POMC neural circuit induced endorphinergic input to the periaqueductal gray from the arcuate nucleus

It has been widely recognized that electroacupuncture (EA) inducing the release of β-endorphin represents a crucial mechanism of EA analgesia. The arcuate nucleus (ARC) in the hypothalamus is a vital component of the endogenous opioid peptide system. Serving as an integration center, the periaqueductal gray (PAG) receives neural fiber projections from the frontal cortex, insular cortex, and ARC. However, the specific mechanisms how EA facilitates the release of β-endorphin within the ARC, eliciting analgesic effects are yet to be elucidated. In this study, we conducted in vivo and in vitro experiments by transcriptomics, microdialysis, photogenetics, chemical genetics, and calcium imaging, combined with transgenic animals. Firstly, we detected 2 Hz EA at the Zusanli (ST36) increased the level of β-endorphin and transcriptional level of proopiomelanocortin (POMC). Our transcriptomics profiling demonstrated that 2 Hz EA at the ST36 modulates the expression of c-Fos and Jun B in ARC brain nuclear cluster, and the transcriptional regulation of 2 Hz EA mainly occur in POMC neurons by Immunofluorescence staining verification. Meaning while, 2 Hz EA specifically activated the cAMP-PKA-CREB signaling pathway in ARC which mediating the c-Fos and Jun B transcription, and 2 Hz EA analgesia is dependent on the activation of cAMP-PKA-CREB signaling pathway in ARC. In order to investigate how the β-endorphin produced in ARC transfer to integration center PAG, transneuronal tracing technology was used to observe the 2 Hz EA promoted the neural projection from ARC to PAG compared to 100 Hz EA and sham mice. Inhibited PAGGABA neurons, the transfer of β-endorphin from the ARC nucleus to the PAG nucleus through the ARCPOMC-PAGGABA neural circuit. Furthermore, by manipulating the excitability of POMC neurons from ARCPOMC to PAGGABA using inhibitory chemogenetics and optogenetics, we found that this inhibition significantly reduced transfer of β-endorphin from the ARC nucleus to the PAG nucleus and the effectiveness of 2 Hz EA analgesia in neurological POMC cyclization recombination enzyme (Cre) mice and C57BL/6J mice, which indicates that the transfer of β-endorphin depends on the activation of POMC neurons prefect from ARCPOMC to PAGGABA. These findings contribute to our understanding of the neural circuitry underlying the EA pain-relieving effects and maybe provide valuable insights for optimizing EA stimulation parameters in clinical pain treatment using the in vivo dynamic visual investigating the central analgesic mechanism.

The Roles of Endogenous Opioids in Placebo and Nocebo Effects: From Pain to Performance to Prozac

Placebo and nocebo effects have been well documented for nearly two centuries. However, research has only relatively recently begun to explicate the neurobiological underpinnings of these phenomena. Similarly, research on the broader social implications of placebo/nocebo effects, especially within healthcare delivery settings, is in a nascent stage. Biological and psychosocial outcomes of placebo/nocebo effects are of equal relevance. A common pathway for such outcomes is the endogenous opioid system. This chapter describes the history of placebo/nocebo in medicine; delineates the current state of the literature related to placebo/nocebo in relation to pain modulation; summarizes research findings related to human performance in sports and exercise; discusses the implications of placebo/nocebo effects among diverse patient populations; and describes placebo/nocebo influences in research related to psychopharmacology, including the relevance of endogenous opioids to new lines of research on antidepressant pharmacotherapies.

Not a general, symptom-unspecific, transdiagnostic marker for functional symptoms: sensorimotor processing of head control is intact in chronic pain

Introduction

Functional disorders are prevalent in all medical fields and pose a tremendous public health problem, with pain being one of the most common functional symptoms. Understanding the underlying, potentially unifying mechanism in functional (pain) disorders is instrumental in facilitating timely diagnosis, stigma reduction, and adequate treatment options. Neuroscientific models of perception suggest that functional symptoms arise due to dysregulated sensorimotor processing in the central nervous system, with brain-based predictions dominating the eventual percept. Experimental evidence for this transdiagnostic mechanism has been established in various functional symptoms. The goal of the current study was to investigate whether erroneous sensorimotor processing is an underlying transdiagnostic mechanism in chronic (functional) pain.

Method

A total of 13 patients with chronic (functional) pain [three patients with chronic (functional) pain disorder, F45.40, ICD-10; 10 patients with chronic pain disorder with somatic and psychological factors, F45.41, ICD-10]; and 15 healthy controls performed large combined eye-head gaze shifts toward visual targets, naturally and with increased head moment of inertia. We simultaneously measured participants' eye and head movements to assess head oscillations at the end of the gaze shift, which are an established indicator of (transdiagnostic) sensorimotor processing deficits of head control.

Results

Using a Bayesian analysis protocol, we found that patients with chronic (functional) pain and control participants stabilized their heads equally well (Bayes Factor 01 = 3.7, Bayes Factor exclusion = 5.23; corresponding to substantial evidence) during all sessions of the experiment.

Conclusion

Our results suggest that patients with chronic (functional) pain do not show measurable symptom-unspecific sensorimotor processing deficits. We discuss outcome parameter choice, organ system specificity, and selection of patient diagnoses as possible reasons for this result and recommend future avenues for research.

Similarities between explaining dizziness and explaining pain? Exploring common patient experiences, theoretical models, treatment approaches and potential therapeutic narratives for persistent dizziness or pain

Pain and dizziness are common experiences throughout the lifespan. However, nearly a quarter of those with acute pain or dizziness experience persistence, which is associated with disability, social isolation, psychological distress, decreased independence, and poorer quality of life. Thus, persistent pain or dizziness impacts peoples' lives in similarly negative ways. Conceptual models of pain and dizziness also have many similarities. Many of these models are more expansive than explaining mere symptoms; rather they describe pain or dizziness as holistic experiences that are influenced by biopsychosocial and contextual factors. These experiences also appear to be associated with multi-modal bodily responses related to evaluation of safety, threat detection and anticipation, as influenced by expectations, and predictions anticipation, not simply a reflection of tissue injury or pathology. Conceptual models also characterize the body as adaptable and therefore capable of recovery. These concepts may provide useful therapeutic narratives to facilitate understanding, dethreaten the experience, and provide hope for patients. In addition, therapeutic alliance, promoting an active movement-based approach, building self-efficacy, and condition-specific approaches can help optimize outcomes. In conclusion, there are significant overlaps in the patient experience, theoretical models and potential therapeutic narratives that guide care for people suffering with persistent pain or dizziness.

A systematic review of the added value of perioperative pain neuroscience education

OBJECTIVE

To identify and summarize evidence about the benefits of perioperative pain neuroscience education (PNE) on pain-related and psychosocial outcomes.

METHODS

Included were reports written in English that carried out PNE or its synonyms; perioperative period; aged ≥ 18 years; interventional studies and observational studies. Secondary studies, conference abstracts, and editorials were excluded. There was no time limitation.

INFORMATION SOURCES

PubMed, Virtual Health Library, Cochrane Library, and Science Direct. Search: June 20th 2023. The risk of bias was assessed using the Joanna Briggs Institute checklists, and synthesis followed the recommendations of the Synthesis Without Meta-analysis (SWiM) guideline. Register: Center for Open Science website (10.17605/OSF.IO/ZTNEJ).

RESULTS

The sample consisted of 18 reports. For pain outcomes, it was not possible to attribute PNE benefits because ten reports found improvements in both intervention and control groups. For psychosocial outcomes, fourteen reports found benefits for PNE groups. All the analyzed reports showed low risk of bias.

CONCLUSION

PNE had additional benefits beyond those obtained with conventional treatment for psychosocial outcomes.

PRACTICAL IMPLICATIONS

Due to the lack of evidence, it was not possible to indicate the clinical use of PNE. It is suggested that further studies are needed aimed at clarifying the possible benefits.

Pain and Reorganization after Amputation: Is Interoceptive Prediction a Key?

There is an ongoing discussion on the relevance of brain reorganization following amputation for phantom limb pain. Recent attempts to provide explanations for seemingly controversial findings-specifically, maladaptive plasticity versus persistent functional representation as a complementary process-acknowledged that reorganization in the primary somatosensory cortex is not sufficient to explain phantom limb pain satisfactorily. Here we provide theoretical considerations that might help integrate the data reviewed and suppose a possible additional driver of the development of phantom limb pain-namely, an error in interoceptive predictions to somatosensory sensations and movements of the missing limb. Finally, we derive empirically testable consequences based on our considerations to guide future research.

The heavy-tailed valence hypothesis: the human capacity for vast variation in pleasure/pain and how to test it

Introduction

Wellbeing policy analysis is often criticized for requiring a cardinal interpretation of measurement scales, such as ranking happiness on an integer scale from 0-10. The commonly-used scales also implicitly constrain the human capacity for experience, typically that our most intense experiences can only be at most ten times more intense than our mildest experiences. This paper presents the alternative "heavy-tailed valence" (HTV) hypothesis: the notion that the accessible human capacity for emotional experiences of pleasure and pain spans a minimum of two orders of magnitude.

Methods

We specify five testable predictions of the HTV hypothesis. A pilot survey of adults aged 21-64 (n = 97) then tested two predictions, asking respondents to comment on the most painful and most pleasurable experiences they can recall, alongside the second most painful and pleasurable experiences.

Results

The results find tentative support for the hypothesis. For instance, over half of respondents said their most intense experiences were at least twice as intense as the second most intense, implying a wide capacity overall. Simulations further demonstrate that survey responses are more consistent with underlying heavy-tailed distributions of experience than a "constrained valence" psychology.

Discussion

A synthesis of these results with prior findings suggests a "kinked" scale, such that a wide range of felt experience is compressed in reports at the high end of intensity scales, even if reports at lower intensities behave more cardinally. We present a discussion of three stylized facts that support HTV and six against, lessons for a future survey, practical guidelines for existing analyses, and implications for current policy. We argue for a dramatic increase in societal ambition. Even in high average income countries, the HTV hypothesis suggests we remain far further below our wellbeing potential than a surface reading of the data might suggest.

Familiarity From Facial Appearance Leads to Hypoalgesia

Social context has been shown to influence pain perception. This study aimed to broaden this literature by investigating whether relevant social stimuli, such as faces with different levels of intrinsic (based on physical resemblance to known individuals) and episodic (acquired through a previous experience) familiarity, may lead to hypoalgesia. We hypothesized that familiarity, whether intrinsic or acquired through experience, would increase pain threshold and decrease pain intensity. Sixty-seven participants underwent pain induction (the cold pressor test) viewing previously seen faces (Episodic Group) or new faces (Non-episodic Group) that differed in the level of intrinsic familiarity (high vs low). Pain threshold was measured in seconds, while pain intensity was measured on a rating scale of 0 to 10. The results did not show an effect of episodic familiarity. However, compared to low, high intrinsic familiar faces had an attenuating effect on pain intensity, even after controlling for pain expectation. These results suggest that physical features conveying a higher feeling of familiarity induce a top-down hypoalgesic modulation, in line with the idea that familiarity may signal safety and that the presence of familiar others reduce perceived threat-related distress. This study provides further evidence on the social modulation of pain and contributes to the literature on first impressions' influence on social behavior. PERSPECTIVE: Consistent with the idea that familiar others signal safety and reduce the sense of threat, facial features conveying familiarity induce a top-down hypoalgesic modulation. This knowledge may contribute to understanding differences in pain perception in experimental and clinical contexts.

Kidney Donor Perspectives on Acute Postoperative Pain Management

This study employed a qualitative descriptive approach to examine living kidney donor's experience of postoperative pain. Thirteen living kidney donors aged 46.5 (±14.4) years participated in this study. Semi-structured interviews were conducted and transcribed. Transcripts were inductively coded and reviewed for trends, patterns, and insights into donor's experience of postoperative pain. Donors experienced postoperative pain from a variety of sources that hindered recovery and created anxiety and fear in some. Donors managed pain with opioid and non-opioid medications, social support, and ambulation. Donor's past experiences with and expectations about pain, relationships with intended recipients, social support, as well as motivations for and meaning of donation informed their experience of postoperative pain. Prompt pharmacologic intervention for pain, as well as further coaching and education about pain management should be emphasized for nurses caring for living kidney donors. Further study of how donor's motivation might mediate their pain experience is needed.

How Do Expectations Modulate Pain? A Motivational Perspective

Expectations can profoundly modulate pain experience, during which the periaqueductal gray (PAG) plays a pivotal role. In this article, we focus on motivationally evoked neural activations in cortical and brainstem regions both before and during stimulus administration, as has been demonstrated by experimental studies on pain-modulatory effects of expectations, in the hope of unraveling how the PAG is involved in descending and ascending nociceptive processes. This motivational perspective on expectancy effects on the perception of noxious stimuli sheds new light on psychological and neuronal substrates of pain and its modulation, thus having important research and clinical implications.

Analgesia for the Bayesian Brain: How Predictive Coding Offers Insights Into the Subjectivity of Pain

PURPOSE OF REVIEW

In order to better treat pain, we must understand its architecture and pathways. Many modulatory approaches of pain management strategies are only poorly understood. This review aims to provide a theoretical framework of pain perception and modulation in order to assist in clinical understanding and research of analgesia and anesthesia.

RECENT FINDINGS

Limitations of traditional models for pain have driven the application of new data analysis models. The Bayesian principle of predictive coding has found increasing application in neuroscientific research, providing a promising theoretical background for the principles of consciousness and perception. It can be applied to the subjective perception of pain. Pain perception can be viewed as a continuous hierarchical process of bottom-up sensory inputs colliding with top-down modulations and prior experiences, involving multiple cortical and subcortical hubs of the pain matrix. Predictive coding provides a mathematical model for this interplay.

Characteristic oscillatory brain networks for predicting patients with chronic migraine

To determine specific resting-state network patterns underlying alterations in chronic migraine, we employed oscillatory connectivity and machine learning techniques to distinguish patients with chronic migraine from healthy controls and patients with other pain disorders. This cross-sectional study included 350 participants (70 healthy controls, 100 patients with chronic migraine, 40 patients with chronic migraine with comorbid fibromyalgia, 35 patients with fibromyalgia, 30 patients with chronic tension-type headache, and 75 patients with episodic migraine). We collected resting-state magnetoencephalographic data for analysis. Source-based oscillatory connectivity within each network, including the pain-related network, default mode network, sensorimotor network, visual network, and insula to default mode network, was examined to determine intrinsic connectivity across a frequency range of 1-40 Hz. Features were extracted to establish and validate classification models constructed using machine learning algorithms. The findings indicated that oscillatory connectivity revealed brain network abnormalities in patients with chronic migraine compared with healthy controls, and that oscillatory connectivity exhibited distinct patterns between various pain disorders. After the incorporation of network features, the best classification model demonstrated excellent performance in distinguishing patients with chronic migraine from healthy controls, achieving high accuracy on both training and testing datasets (accuracy > 92.6% and area under the curve > 0.93). Moreover, in validation tests, classification models exhibited high accuracy in discriminating patients with chronic migraine from all other groups of patients (accuracy > 75.7% and area under the curve > 0.8). In conclusion, oscillatory synchrony within the pain-related network and default mode network corresponded to altered neurophysiological processes in patients with chronic migraine. Thus, these networks can serve as pivotal signatures in the model for identifying patients with chronic migraine, providing reliable and generalisable results. This approach may facilitate the objective and individualised diagnosis of migraine.

The experience of pain and its ontological modelling from a philosophical point of view: Phenomenological description and ontological revision of the McGill Pain Questionnaire

The aim of the article is to identify, on the basis of the phenomenological and ontological analysis of the experience of pain and the ways in which this experience is expressed in natural language, an ontological modelling of the language of pain and, at the same time, a revision of the traditional version of the McGill questionnaire. The purpose is to provide a different characterisation and an adequate evaluation of the phenomenon of pain, and, consequently, an effective measure of the actual experience of the suffering subject.

Pain management in periodontal therapy using local anesthetics and other drugs: an integrative review

Background

Surgical and non-surgical periodontal procedures often lead to postoperative pain. Clinicians use pharmacological methods such as anesthetics, anti-inflammatory drugs, and analgesics for relief. However, the multitude of options makes it challenging to select the best approach for routine dental care.

Objective

This review aimed to describe previous studies regarding the pharmacological management used for pain control during periodontal procedures as well as factors that may interfere with patients' perception of pain.

Methods

We included studies (period of 2000-2023, whose approach corresponded to the pharmacological protocols used for preoperative, trans-operative, and postoperative pain control in adult patients undergoing surgical and non-surgical periodontal therapy.

Results

A total of 32 studies were included in the analysis, of which 17 (53%) were related to anesthetic methods and 15 (47%) were related to therapeutic protocols (anti-inflammatory/analgesic agents). These studies predominantly involved nonsurgical periodontal procedures. Studies have reported that factors related to age, type of procedure, and anxiety can influence pain perception; however, only seven of these studies evaluated anxiety.

Conclusions

Numerous methods for pain control can be applied in periodontal therapy, which are accomplished through anesthetic methods and/or therapeutic protocols. Factors such as anxiety, age, and type of procedure are related to pain perception in patients. Thus, it is the responsibility of dentists to evaluate each clinical situation and define the best protocol to follow based on the literature.

Lifeworlds in pain: a principled method for investigation and intervention

The experience of pain spans biological, psychological and sociocultural realms, both basic and complex, it is by turns necessary and devastating. Despite an extensive knowledge of the constituents of pain, the ability to translate this into effective intervention remains limited. It is suggested that current, multiscale, medical approaches, largely informed by the biopsychosocial (BPS) model, attempt to integrate knowledge but are undermined by an epistemological obligation, one that necessitates a prior isolation of the constituent parts. To overcome this impasse, we propose that an anthropological stance needs to be taken, underpinned by a Bayesian apparatus situated in computational psychiatry. Here, pain is presented within the context of lifeworlds, where attention is shifted away from the constituents of experience (e.g. nociception, reward processing and fear-avoidance), towards the dynamic affiliation that occurs between these processes over time. We argue that one can derive a principled method of investigation and intervention for pain from modelling approaches in computational psychiatry. We suggest that these modelling methods provide the necessary apparatus to navigate multiscale ontology and epistemology of pain. Finally, a unified approach to the experience of pain is presented, where the relational, inter-subjective phenomenology of pain is brought into contact with a principled method of translation; in so doing, revealing the conditions and possibilities of lifeworlds in pain.

Dysfunctional Activation of the Dorsolateral Prefrontal Cortex During Pain Anticipation Is Associated With Altered Subsequent Pain Experience in Fibromyalgia Patients

The ability to accurately predict pain is an adaptive feature in healthy individuals. However, in chronic pain, this mechanism may be selectively impaired and can lead to increased anxiety and excessive avoidance behavior. Recently, we reported the first data demonstrating brain activation in fibromyalgia (FM) patients during conditioned pain responses, in which FM patients revealed a tendency to form new pain-related associations rather than extinguishing irrelevant ones. The aim of the present study was to extend our previous analysis, to elucidate potential neural divergences between subjects with FM (n = 65) and healthy controls (HCs) (n = 33) during anticipatory information (ie, prior to painful stimulus onset). Using functional magnetic resonance imaging (fMRI), the current analyses include 1) a congruently cued paradigm of low and high pain predictive cues, followed by 2) an incongruently cued paradigm where low and high pain predictive cues were followed by an identical mid-intensity painful pressure. During incongruently cued high-pain associations, FM exhibited reduced left dorsolateral prefrontal cortex (dlPFC) activation compared to HCs, which was followed by an altered subsequent pain experience in FM, as patients continued to rate the following painful stimuli as high, even though the pressure had been lowered. During congruently cued low pain anticipation, FM exhibited decreased right dlPFC activation compared to HCs, as well as decreased brain connectivity between brain regions implicated in cognitive modulation of pain (dlPFC) and nociceptive processing (primary somatosensory cortex/postcentral gyrus [S1] and supplementary motor area [SMA]/midcingulate cortex [MCC]). These results may reflect an important feature of validating low pain expectations in HCs and help elucidate behavioral reports of impaired safety processing in FM patients. PERSPECTIVE: FM exhibited a stronger conditioned pain response for high-pain associations, which was associated with reduced dlPFC activation during the incongruent trial. During (congruent and incongruent) low pain associations, FM dlPFC brain activation remained indifferent. Imbalances in threat and safety pain perception may be an important target for psychotherapeutic interventions.

Doctors Speak: A Qualitative Study of Physicians' Prescribing of Antidepressants in Functional Bowel Disorders

Tricyclic antidepressants (TCAs) are frequently prescribed for chronic functional pain disorders. Although the mechanism of action targets pain perception, treating patients with TCAs for disorders conceptualized as "functional" can promote stigmatization in these patients because it hints at psychological dimensions of the disorder. The goal of this study was to understand how physicians prescribe TCAs in the face of this challenge. We interviewed eleven gastroenterologists in tertiary care clinics specializing in functional gastrointestinal disorders, such as irritable bowel syndrome. We found that the physicians interviewed (1) were aware of the stigma attached to taking antidepressants for a medical condition, (2) emphasized biological, as opposed to psychological, mechanisms of action, (3) while focusing on biological mechanisms, they nevertheless prescribed TCAs in a way that is highly attentive to the psychology of expectations, making specific efforts to adjust patients' expectations to be realistic and to reframe information that would be discouraging and (4) asked patients to persist in taking TCAs despite common and, at times, uncomfortable side effects. In this context of shared decision making, physicians described nuanced understanding and behaviours necessary for treating the complexity of functional disorders and emphasized the importance of a strong patient-provider relationship.

Human ventromedial prefrontal cortex lesions enhance the effect of expectations on pain perception

Pain is strongly modulated by expectations and beliefs. Across species, subregions of ventromedial prefrontal cortex (VMPFC) are implicated in a variety of functions germane to pain, predictions, and learning. Human fMRI studies show that VMPFC activity tracks expectations about pain and mediates expectancy effects on pain-related activity in other brain regions. Prior lesion studies suggest that VMPFC may instead play a more general role in generating affective responses to painful stimuli. To test whether VMPFC is required to generate affective responses to pain or is more specifically involved in expectancy-based pain modulation, we studied responses to heat stimuli in five adults with bilateral surgical lesions of VMPFC and twenty healthy adults without brain damage. All participants underwent a quantitative sensory testing procedure followed by a pain expectancy task in which cues predicting either low or high pain were followed by intermittent medium intensity heat stimuli. Compared to adults without brain damage, individuals with VMPFC lesions reported larger differences in expected pain based on predictive cues and failed to update expectations following the covert introduction of unexpected medium temperature stimuli. Consistent with observed expectancy differences, subjective pain unpleasantness ratings in the VMPFC lesion group were more strongly modulated by cue during thermal stimulation. We found no group differences in overall pain sensitivity, nor in relationships between pain and autonomic arousal, suggesting that VMPFC damage specifically enhances the effect of expectations on pain processing, likely driven by impaired integration of new sensory feedback to update expectations about pain. These results provide essential new data regarding the specific functional contribution of VMPFC to pain modulation.

I Feel! Therefore, I Am from Pain to Consciousness in DOC Patients

Pain assessment and management in patients with disorders of consciousness (DOC) is a challenging and important aspect of care, with implications for detecting consciousness and promoting recovery. This narrative review explores the role of pain in consciousness, the challenges of pain assessment, pharmacological treatment in DOC, and the implications of pain assessment when detecting changes in consciousness. The review discusses the Nociception Coma Scale and its revised version, which are behavioral scales used to assess pain in DOC patients, and the challenges and controversies surrounding the appropriate pharmacological treatment of pain in these patients. Moreover, we highlight recent evidence suggesting that an accurate pain assessment may predict changes in the level of consciousness in unresponsive wakefulness syndrome/vegetative state patients, underscoring the importance of ongoing pain management in these patients.

Effects of False Feedback on Pain Tolerability Among Young Healthy Adults: Predictive Roles of Intentional Effort Investment and Perceived Pain Intensity

Purpose

Expectations and modification gained through critical learning influence pain perception. We tested how pain tolerability was influenced by the effects of orally delivered false feedback and participant status immediately prior to performing tasks.

Patients and Methods

A total of 125 healthy college students (69 females and 56 males) were randomly assigned to 3 groups (positive, negative, and control) to participate in two formal cold pressor tests (CPTs). Participants completed the same series of task-related questionnaires (perceived importance, intended effort, current affect, and self-efficacy) before each CPT. False performance feedback was delivered after completion of the baseline level CPT. After completion of each CPT, both pain intensity and pain tolerability (duration in ice water) were recorded.

Results

The results of linear mixed models revealed significant condition × time interactions on pain tolerability and task self-efficacy after controlling for individual variance as a random effect. Participants who received negative feedback exhibited increased pain tolerability without decreasing their self-efficacy, whereas participants who received positive feedback showed increased self-efficacy with no change in pain tolerability. A longer pain tolerance duration was also predicted by a more intentional investment of effort and a lower intensity of experienced pain as well as the effect of false feedback.

Conclusion

The research highlights the effect of powerful situational influences on laboratory-induced pain tolerance.

Up-regulation of LCN2 in the anterior cingulate cortex contributes to neural injury-induced chronic pain

Chronic pain caused by disease or injury affects more than 30% of the general population. The molecular and cellular mechanisms underpinning the development of chronic pain remain unclear, resulting in scant effective treatments. Here, we combined electrophysiological recording, in vivo two-photon (2P) calcium imaging, fiber photometry, Western blotting, and chemogenetic methods to define a role for the secreted pro-inflammatory factor, Lipocalin-2 (LCN2), in chronic pain development in mice with spared nerve injury (SNI). We found that LCN2 expression was upregulated in the anterior cingulate cortex (ACC) at 14 days after SNI, resulting in hyperactivity of ACC glutamatergic neurons (ACC^Glu) and pain sensitization. By contrast, suppressing LCN2 protein levels in the ACC with viral constructs or exogenous application of neutralizing antibodies leads to significant attenuation of chronic pain by preventing ACC^Glu neuronal hyperactivity in SNI 2W mice. In addition, administering purified recombinant LCN2 protein in the ACC could induce pain sensitization by inducing ACC^Glu neuronal hyperactivity in naïve mice. This study provides a mechanism by which LCN2-mediated hyperactivity of ACC^Glu neurons contributes to pain sensitization, and reveals a new potential target for treating chronic pain.

Mindfulness-Based Interventions for the Reduction of Postoperative Pain in Hip and Knee Arthroplasty Patients: A Systematic Review and Meta-Analysis

PURPOSE

The aim of this systematic review and meta-analysis is to evaluate the effect of mindfulness-based interventions (MBIs) on post-surgical pain in patients undergoing a total hip replacement (THR) or total knee replacement (TKR).

METHODS

We performed a systematic review and meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. A search of multiple databases, including PubMed and EMBASE, was performed for studies from database inception through March 2nd, 2022. Data were extracted, and pooled estimates of standardized mean differences in pain scores were calculated using a random effects model and inverse probability weighting.

RESULTS

Two randomized control trials were eligible for inclusion (299 patients). The average ages of participants in each study were similar at 65.5 and 64.8 years, and both studies were predominantly female at 72.4% and 61.9%. The mindfulness intervention ranged from an eight-week program to a 20-minute session. Both individual studies reported statistically significant reductions in postoperative pain for MBI groups. The pooled standardized mean difference in pain scores for the MBI groups compared to the control groups was -1.94 (-3.39; -0.48).

CONCLUSIONS

There exists preliminary evidence for the beneficial effect of MBIs on reducing the postoperative pain experience in this patient population. Given the significant consequences of postoperative pain and the necessity for non-opioid forms of analgesia, this topic represents a promising area of research that warrants future randomized control trials to better understand the role of MBIs for postoperative analgesia.

Psychophysiologic Symptom Relief Therapy (PSRT) for Post-acute Sequelae of COVID-19

Objective

To determine if psychophysiologic symptom relief therapy (PSRT) will reduce symptom burden in patients suffering from post-acute sequelae of COVID-19 (PASC) who had mild/moderate acute COVID-19 disease without objective evidence of organ injury.

Patients and Methods

Twenty-three adults under the age of 60 with PASC for at least 12 weeks following COVID-19 infection were enrolled in an interventional cohort study conducted via virtual platform between May 18, 2021 and August 7, 2022. Participants received PSRT during a 13 week (approximately 44 hour) course. Participants were administered validated questionnaires at baseline and at 4, 8, and 13 weeks. The primary outcome was change in somatic symptoms from baseline, measured using the Somatic Symptom Scale-8 (SSS-8), at 13 weeks.

Results

The median duration of symptoms prior to joining the study was 267 days (IQR: 144, 460). The mean SSS-8 score of the cohort decreased from baseline by 8.5 (95% CI: 5.7-11.4), 9.4 (95% CI: 6.9-11.9), and 10.9 (95% CI: 8.3-13.5) at 4, 8, and 13 weeks respectively (all p<.001). Participants also experienced statistically significant improvements across other secondary outcomes including changes in dyspnea, fatigue, and pain (all p<.001).

Conclusion

PSRT may effectively decrease symptom burden in patients suffering from PASC without evidence of organ injury. The study was registered on clinicaltrials.gov (NCT04854772).

Cognitive exertion affects the appraisal of one's own and other people's pain

Correctly evaluating others' pain is a crucial prosocial ability. In both clinical and private settings, caregivers assess their other people's pain, sometimes under the effect of poor sleep and high workload and fatigue. However, the effect played by such cognitive strain in the appraisal of others' pain remains unclear. Fifty participants underwent one of two demanding tasks, involving either working memory (Experiment 1: N-Back task) or cognitive interference (Experiment 2: Stroop task). After each task, participants were exposed to painful laser stimulations at three intensity levels (low, medium, high), or video-clips of patients experiencing three intensity levels of pain (low, medium, high). Participants rated the intensity of each pain event on a visual analogue scale. We found that the two tasks influenced rating of both one's own and others' pain, by decreasing the sensitivity to medium and high events. This was observed either when comparing the demanding condition to a control (Stroop), or when modelling linearly the difficulty/performance of each depleting task (N-Back). We provide converging evidence that cognitive exertion affects the subsequent appraisal of one's own and likewise others' pain.