The effects of age on pain sensitivity: preclinical studies

Deep proteomics and network pharmacology reveal sex- and age-shared neuropathic pain signatures in mouse dorsal root ganglia

Our understanding of how sex and age influence chronic pain at the molecular level is still limited with wide-reaching consequences for adolescent patients. Here, we leveraged deep proteome profiling of mouse dorsal root ganglia (DRG) from adolescent (4-week-old) and adult (12-week-old) male and female mice to investigate the establishment of neuropathic pain in the spared nerve injury (SNI)-model in parallel. We quantified over 12,000 proteins, including notable ion channels involved in pain, highlighting the sensitivity of our approach. Differential expression revealed sex- and age-dependent proteome changes upon nerve injury. In contrast to most previous studies, our comprehensive dataset enabled us to determine differentially expressed proteins (DEPs), which were shared between male and female mice of both age groups. Among these, the vast majority (94 %) were also expressed and, in part, altered in human DRG of neuropathic pain patients, indicating evolutionary conservation. Proteome signatures represented numerous targets of FDA-approved drugs comprising both (i) known pain therapeutics (e.g. Pregabalin and opioids) and, importantly, (ii) compounds with high potential for future re-purposing, e.g. Ptprc-modulators and Epoetins. Protein network and multidimensional analysis uncovered distinct hubs of sex- and age-shared biological pathways impacted by neuropathic pain, such as neuronal activity and synaptic function, DNA-damage, and neuroimmune interactions. Taken together, our results capture the complexity of nerve injury-associated DRG alterations in mice at the network level, moving beyond single-candidate studies. Consequently, we provide an innovative resource of the molecular landscape of neuropathic pain, enabling novel opportunities for translational pain research and network-based drug discovery.

Inflammation is associated with pain and fatigue in older adults

Introduction

Increasing evidence suggests that inflammation may play a pivotal role in the development of chronic pain and fatigue in aging individuals. This study investigated the relationship between three inflammatory markers (IL-6, CRP, and TNFα) and pain and fatigue, both cross-sectionally and longitudinally, in a sample of older adults from the Saint Louis Personality and Aging (SPAN) study.

Methods

SPAN study participants provided blood samples at two in-person sessions approximately 2 years apart for the analysis of the inflammatory biomarkers IL-6, CRP, and TNFα. Pain and fatigue were assessed using the RAND-36 Health Status Inventory. Correlations (with false discovery rate correction for multiple testing) and follow-up linear regressions including potentially confounding demographic (e.g., annual household income) and health (e.g., BMI, medication use) covariates were used to estimate cross sectional and longitudinal associations. Analytic ns ranged from 533 to 815.

Results

Cross-sectional analyses revealed that higher IL-6 and CRP were associated with greater reported pain and fatigue, even after accounting for covariates (βs > .098, ps < .05). TNFα was associated with greater fatigue only (β = .100, p = .012). Longitudinally, CRP and IL-6 predicted future pain and fatigue, although only the relationship between CRP and future fatigue survived the inclusion of covariates (β = .104, p = .022). Both pain and fatigue predicted higher levels of IL-6 and CRP approximately 2 years later, although only the associations with IL-6 survived the inclusion of covariates (βs > .12, ps < .01).

Discussion

Our study adds to a growing body of literature showing that inflammation is associated with greater pain and fatigue in older adults. Our longitudinal data showing temporal bidirectional associations is consistent with evidence from non-human animal models that heightened inflammation causally contributes to fatigue and also suggests that the experience of pain and fatigue may contribute to inflammation. It will be important for future work to identify how lifestyle factors associated with pain and fatigue (e.g., physical activity) may contribute to these associations.

"I will try anything" the experience of working age stroke survivors living with chronic post-stroke pain: an interpretative phenomenological analysis

PURPOSE

To investigate the experience of working age adults living with chronic post-stroke pain in the United Kingdom (UK).

METHODS

Semi-structured interviews were conducted with eight working age (46-64 years) UK-based stroke survivors who experience chronic post-stroke pain (≥3 months). The interviews were analysed using interpretative phenomenological analysis.

RESULTS

The analysis led to three Group Experiential Themes: "The Solitude of the Pain Experience," "Unsatisfactory Healthcare and the Need for Self-Care" and "The Development of Pain Acceptance." Findings suggest that individuals see their post-stroke pain as an invisible disability, which is overlooked and misunderstood by others. Furthermore, in the absence of a differential post-stroke pain diagnosis, clear, accurate information and alternatives to pharmacological treatments, individuals with post-stroke pain invest their own resources in finding answers and a way to live with the pain.

CONCLUSIONS

The findings suggest the need for further education on post-stroke pain for healthcare professionals, the consideration of pain in post-stroke assessments, the need for clear differential pain diagnoses and the provision of accurate information to patients. Research is needed to establish non-pharmacological evidence-based treatment approaches, such as pain management programmes, peer support and psychological interventions.

Differential Impact of Adolescent or Adult Stress on Behavior and Cortical Parvalbumin Interneurons and Perineuronal Nets in Male and Female Mice

BACKGROUND

Stress has become a common public health concern, contributing to the rising prevalence of psychiatric disorders. Understanding the impact of stress considering critical variables, such as age, sex, and individual differences, is of the utmost importance for developing effective intervention strategies.

METHODS

Stress effects (daily footshocks for 10 days) during adolescence (postnatal day [PND] 31-40) and adulthood (PND 65-74) were investigated on behavioral outcomes and parvalbumin (PV)-expressing GABAergic interneurons and their associated perineuronal nets (PNNs) in the prefrontal cortex of male and female mice 5 weeks post stress.

RESULTS

In adulthood, adolescent stress induced behavioral alterations in male mice, including anxiety-like behaviors, social deficits, cognitive impairments, and altered dopamine system responsivity. Applying integrated behavioral z-score analysis, we identified sex-specific differences in response to adolescent stress, with males displaying greater vulnerability than females. Furthermore, adolescent-stressed male mice showed decreased PV+ and PNN+ cell numbers and PV+/PNN+ colocalization, while in females, adolescent stress reduced prefrontal PV+/PNN+ colocalization in the prefrontal cortex. Further analysis identified distinct behavioral clusters, with certain females demonstrating resilience to adolescent stress-induced deficits in sociability and PV+ cell number. Adult stress in male and female mice did not cause long-lasting changes in behavior and PV+ and PNN+ cell number.

CONCLUSION

Our findings indicate that the timing of stress, sex, and individual variabilities seem to be determinants for the development of behavioral changes associated with psychiatric disorders, particularly in male mice during adolescence.

Comparison of Post-Hemorrhoid Surgery Pain Profiles in Older and Younger Adults

INTRODUCTION

Older and younger adults are offered similar analgesic options after hemorrhoid surgery (HS), but the differences in pain between the two populations are unknown. This study aims to compare postoperative pain outcomes after HS in older and younger individuals.

METHODS

This is a retrospective analysis of electronic medical records of patients who underwent HS between 2018 and 2023. Patients were excluded if additional anorectal procedures were performed at the time of HS. Data related to pain-related outcomes were compiled: (1) need for narcotic prescription refills; (2) documentation of a pain-related phone call within 30 d; (3) urgent postoperative office visit before regular scheduled follow-up; and (4) pain-related postoperative emergency department visits. Associations between age and pain-related outcomes were tested using Fisher's exact test, chi-square test, and covariate adjusted logistic regression modeling.

RESULTS

There were a total of 249 patients, 60 older adults, and 189 younger adults. Compared to younger patients, older adults demonstrated a reduced frequency of pain-related phone calls (10.3 versus 32.1%, P < 0.01) and opioid refills (0 versus 14.4%, P < 0.01). After adjusting for confounders, older age remained inversely associated with pain-related postoperative phone calls (odds ratio = 0.25, 95% confidence interval = [0.1-0.6], P = 0.003).

CONCLUSIONS

Older adults had better pain outcomes after HS in comparison to younger patients. These findings suggest that the postoperative analgesic needs of older patients after HS are lower than those of younger patients. Decisions regarding opioid prescription in older adults recovering from HS should be tailored to avoid narcotic-related complications.

Enhancing end-of-life care quality and achieving a good death for the elderly in Japan

BACKGROUND

In the context of an aging populations, there is an escalating need for palliative care tailored to the needs of the elderly. This study aimed to assess differences in symptoms and good death among the elderly, along with the structures and processes involved in end-of life care, and to explore the impact of age on achieving a good death.

METHODS

We conducted a questionnaire survey for bereaved family members of patients with cancer, heart disease, stroke, pneumonia, and kidney failure in 2019 and 2020. The study population was categorized into the following age groups: ≤64, 65-74, 75-84, and ≥85. The outcomes included symptom intensity, achievement of a good death, and receipt of quality care.

RESULTS

In total, 62,576 bereaved family members agreed to participate in the survey (response rate; 54.0 %). The weighted percentages of 'severe' and 'very severe' symptoms decreased with age. These trends were observed across age groups, even among the elderly. The strongest effect of age on achieving a good death was found for 'feeling that life is complete' with reference to those aged ≤64 years: 65-74 years (odds ratio [OR]; 2.09, 95 % CI; 1.94 to 2.25), 75-84 years (OR; 4.86, 95 % CI; 4.52 to 5.22) and ≥85 years (OR; 12.8, 95 % CI; 11.9 to 13.8).

CONCLUSION

Age-specific differences were observed in quality of death, quality of care, and symptom intensity. It is important to provide individualized consideration for each age group rather than categorizing them broadly as the elderly when caring for them.

Predicting risk factors for acute pain after hepatobiliary and pancreatic surgery: an observational case control study

BACKGROUND

Inadequate postoperative analgesia is associated with increased risks of various postoperative complications, longer hospital stay, decreased quality of life and higher costs.

OBJECTIVES

This study aimed to investigate the risk factors for moderate-to-severe postoperative pain within the first 24 hours and 24-48 hours after major hepatobiliary pancreatic surgery.

METHODS

Data of patients who underwent surgery at the Department of Hepatobiliary Surgery in Henan Provincial People's Hospital were collected from January 2018 to August 2020. Univariate and multivariate logistic regression analyses were used to identify the risk factors of postoperative pain.

RESULTS

In total, 2180 patients were included in the final analysis. 183 patients (8.4%) suffered moderate-to-severe pain within 24 hours after operation. The independent risk factors associated with moderate-to-severe pain 24 hours after procedures were younger age (OR, 0.97; 95% CI 0.95 to 0.98, p<0.001), lower body mass index (BMI) (OR, 0.94; 95% CI 0.89 to 0.98, p=0.018), open surgery (OR, 0.34; 95% CI 0.22 to 0.52, p<0.001), and postoperative analgesia protocol with sufentanil (OR, 4.38; 95% CI 3.2 to 5.99, p<0.001). Postoperative hospital stay was longer in patients with inadequate analgesia (p<0.05).

CONCLUSION

Age, BMI, laparoscopic surgery, and different analgesic drugs were significant predictors of postoperative pain after major hepatobiliary and pancreatic surgery.

TRIAL REGISTRATION

ChiCTR2100049726.

Pressure algometry in the general adult population: Age and sex differences

Experimental pain studies have revealed inter-individual variations in pain perception that are influenced by age, sex, and country of origin. This study aimed to explore the age and sex differences in pressure pain thresholds within the Iranian general population. To assess the pressure pain thresholds, a handheld pressure algometer was applied bilaterally to the middle fingers of both hands. The participants also completed the short form of the McGill Pain Questionnaire to provide a clinical pain rating. This cross-sectional study included 1610 adult subjects (54.96% female, mean age 40.13 ± 10.18 years). The findings indicated that females generally exhibited lower pain thresholds than males when assessing pain detection and tolerance parameters (P < .001). Females also demonstrated a significant lower pressure thresholds and clinical pain ratings compared with men (P < .001). Additionally, significant differences were observed between age groups in terms of pain detection and tolerance thresholds (P = .02 and P = .03, respectively). However, the interaction between sex and age was not significant. No significant differences in pain detection thresholds were observed between the right and left hand (P = .11). This study underscores the potential utility of algometry as a valuable tool for objectifying pain in the Iranian population.

Unpacking the relationship between Big Five personality traits and experimental pain: A systematic review and meta-analysis

Pain is essential for survival, but individual responses to painful stimuli vary, representing a complex interplay between sensory, cognitive, and affective factors. Individual differences in personality traits and in pain perception covary but it is unclear which traits play the most significant role in understanding the pain experience and whether this depends on pain modality. A systematic search identified 1534 records (CINAHL, MEDLINE, PsycInfo, PubMed and Web of Science), of which 22 were retained and included in a systematic review. Only studies from the pressure pain domain (n=6) could be compared in a formal meta-analysis to evaluate the relationship between Big Five traits and experimental pain. Pressure pain tolerance correlated positively with Extraversion and negatively with Neuroticism with a trivial effect size (<0.1). While these findings suggest personality might be only weakly related to pain in healthy individuals, we emphasize the need to consider standardization, biases, and adequate sample sizes in future research, as well as additional factors that might affect experimental pain sensitivity.

The comparison of effectiveness of acupressure on Spleen 6 and Hugo points on the severity of postpartum pain: A randomized clinical trial

Background and aims

Postpartum pain poses a significant challenge for new mothers. Various nonpharmacological methods are employed to manage postpartum pain. This study aimed to compare the effectiveness of acupressure on Spleen 6 and Hugo points on the severity of postpartum pain.

Methods

In this parallel randomized trial study, 68 eligible primiparous women who had vaginal deliveries and experienced postpartum pain at Farabi Hospital in Malekan (a city in East Azarbaijan Province in Iran) were selected according to inclusion/exclusion criteria and then allocated to the Hugo (n = 34) and Spleen 6 (n = 34) acupressure groups using a randomized block design (six blocks). The data collection process took place from November 2022 to April 2023. The participants were blinded; however, the analysts and investigators were not blinded. Acupressure interventions were applied bilaterally for 20 min, consisting of 10 s of pressure followed by 2 s of rest. Pain intensity was assessed using a visual pain scale before, immediately after, and 1 h after the intervention. In total, 68 participants fulfilled the study. Data were analyzed using Statistical Package for the Social Sciences version 25 with chi-square, Mann-Whitney, and Friedman tests.

Results

Both groups exhibited a statistically significant reduction in postpartum pain intensity across all periods (p < 0.001). Although there was a significant difference in pain intensity between the groups before the intervention (p = 0.039), this distinction was not observed immediately and 1 h after the intervention (p ≥ 0.05). Both Hugo and Spleen's 6 acupressure interventions reduced postpartum pain intensity. No significant adverse events or side effects were observed.

Conclusion

Acupressure on Spleen 6 and Hugo points helped decrease the severity of postpartum pain in primiparous women who had vaginal deliveries. Healthcare providers are encouraged to consider acupressure for postpartum pain management.

Exploring the relationship between language, postoperative pain, and opioid use

BACKGROUND

Racial and ethnic disparities in pain management are well documented. Differences in pain assessment and management by language have not been studied in the postoperative setting in gynecologic surgery.

OBJECTIVE

This study aimed to investigate the association between language and immediate postoperative pain management by comparing pain assessments and perioperative opioid use in non-English speakers and English speakers.

STUDY DESIGN

This was a retrospective cohort study comparing perioperative outcomes between non-English-speaking patients and English-speaking patients who had undergone a gynecologic oncology open surgery between July 2012 and December 2020. The primary language was extracted from the electronic medical record. Opioid use is expressed in oral morphine equivalents. Proportions are compared using chi-square tests, and mean values are compared using 2-sample t tests. Although interpreter services are widely available in our institution, the use of interpreters for any given inpatient-provider interaction is not documented.

RESULTS

Between 2012 and 2020, 1203 gynecologic oncology patients underwent open surgery, of whom 181 (15.1%) were non-English speakers and 1018 (84.9%) were English speakers. There was no difference between the 2 cohorts concerning body mass index, surgical risk score, or preoperative opioid use. Compared with the English-speaking group, the non-English-speaking group was younger (57 vs 54 years old, respectively; P<.01) and had lower rates of depression (26% vs 14%, respectively; P<.01) and chronic pain (13% vs 6%, respectively; P<.01). Although non-English-speaking patients had higher rates of hysterectomy than English-speaking patients (80% vs 72%, respectively; P=.03), there was no difference in the rates of bowel resections, adnexal surgeries, lengths of surgery, intraoperative oral morphine equivalents administered, blood loss, use of opioid-sparing modalities, lengths of hospital stay, or intensive care unit admissions. In the postoperative period, compared with English-speaking patients, non-English-speaking patients received fewer oral morphine equivalents per day (31.7 vs 43.9 oral morphine equivalents, respectively; P<.01) and had their pain assessed less frequently (7.7 vs 8.8 checks per day, respectively; P<.01) postoperatively. English-speaking patients received a median of 19.5 more units of oral morphine equivalents daily in the hospital and 205.1 more units of oral morphine equivalents at the time of discharge (P=.02 and P=.04, respectively) than non-English-speaking patients. When controlling for differences between groups and several factors that may influence oral morphine equivalent use, English-speaking patients received a median of 15.9 more units of oral morphine equivalents daily in the hospital cohort and similar oral morphine equivalents at the time of discharge compared with non-English-speaking patients.

CONCLUSION

Patients who do not speak English may be at risk of undertreated pain in the immediate postoperative setting. Language barrier, frequency of pain assessments, and provider bias may perpetuate disparity in pain management. Based on this study's findings, we advocate for the use of regular verbal pain assessments with language-concordant staff or medical interpreters for all postoperative patients.

The influence of advanced age on long-term postsurgical analgesic use in patients receiving neuraxial anaesthesia for elective surgery

OBJECTIVE

To determine the relationship between age and long-term postsurgical analgesic use in patients who underwent elective surgery with neuraxial anaesthesia.

DESIGN

Retrospective observational study using data from the National Health Insurance Research Database of Taiwan from 2015 to 2019.

SETTING

National Health Insurance Research Database of Taiwan.

PATIENTS

A total of 12,810 patients (6405 younger and 6405 older) matched using propensity score matching.

INTERVENTIONS

Older (≥65 years).

MEASUREMENTS

The use of long-term (3 or 6 months) postoperative analgesics, including opioids, as a surrogate marker of chronic postsurgical pain (CPSP) was analysed using logistic regression.

MAIN RESULTS

After 3 months of surgery, older adults had higher use of all analgesics (odds ratio [OR] = 1.15; 95% CI = 1.03-1.28) and opioids (OR = 1.18; 95% CI = 1.09-1.28) compared to younger patients. Similar results were observed after 6 months of surgery (all analgesic use: OR = 1.11; 95% CI = 1.03-1.20; opioid use: OR = 1.33; 95% CI = 1.07-1.81).

CONCLUSION

The findings from this study suggest that older adults are more likely to experience CPSP and have increased use of long-term analgesics, including opioids, after undergoing elective surgery with neuraxial anaesthesia. The study highlights the need for improved pain management strategies for older adults after surgery.

SIGNIFICANCE

Older age is an independent risk factor for long-term analgesic use after surgery under neuraxial anaesthesiaanesthesia, indicating an increased risk for chronic postsurgical pain.

Mentha rotundifolia (L.) Huds. and Salvia officinalis L. hydrosols mitigate aging related comorbidities in rats

Introduction

Aging is often linked to oxidative stress, where the body experiences increased damage from free radicals. Plants are rich sources of antioxidants, playing a role in slowing down aging and supporting the proper functioning and longevity of cells. Our study focuses on exploring the impact of Mentha rotundifolia (MR) and Salvia officinalis (SO) hydrosols on aging-related comorbidities.

Methods

The chemical composition of MR and SO hydrosols was analyzed by gas chromatography coupled to mass spectrometry. 2,2-Diphenyl 1-picrylhydrazyl and 2,20-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid radicals scavenging assays were used to assess their in vitro antioxidant activity, and heat induced albumin denaturation test was used to evaluate their anti-inflammatory activity. Subsequently, we administered 5% of each plant hydrosol in the drinking water of 18-month-old rats for six months. We then conducted behavioral tests, including open field, dark/light box, rotarod, and Y-maze assessments, and measured biochemical parameters in plasma, liver and brain tissues.

Results and discussion

At two years old, animals treated with MR and SO hydrosols displayed fewer physical and behavioral impairments, along with well-preserved redox homeostasis in comparison with animals in the control group. These results highlighted the significance of MR and SO hydrosols in addressing various aspects of age-related comorbidities. The study suggests that these plant-derived hydrosols may have potential applications in promoting healthy aging and mitigating associated health challenges.

Pain: its prevalence and correlates among the oldest old

BACKGROUND

There is very limited knowledge regarding pain among the oldest old.

AIMS

To investigate the prevalence and correlates of pain among the oldest old.

METHODS

Data were taken from the "Survey on quality of life and subjective well-being of the very old in North Rhine-Westphalia (NRW80+)", including individuals living in North Rhine-Westphalia aged 80 years and over. Pain was categorized as no pain, moderate pain and severe pain. Its prevalence was stratified by sex, age groups, marital status, place of residence and education. A multinomial logistic regression analysis was conducted.

RESULTS

28.50% of the participants reported no pain, 45.06% moderate pain and 26.44% severe pain. Regressions showed that being 85 years or older and a better self-rated health status decreased the likelihood of moderate pain. Being 85-89 years old, being male, highly educated and a better self-rated health status decreased the likelihood of severe pain. The likelihood of moderate and severe pain increased with a higher number of chronic diseases.

DISCUSSION

Study findings showed a high prevalence of pain in the oldest old living in North Rhine-Westphalia, Germany. The likelihood of having moderate or severe pain was reduced among those who were older and presented with a better self-rated health but increased with a growing number of comorbidities. Severe pain was less likely among men and those with a higher education.

CONCLUSION

This cross-sectional representative study adds first evidence of prevalence and correlations of pain among the oldest old. Longitudinal studies are required to further explore the determinants of pain in this age group.

Pain and Itch Processing in Aged Mice

Most reports agree that aging negatively impacts pain processing and that the prevalence of chronic pain increases significantly with age. To improve current therapies, it is critical that aged animals be included in preclinical studies. Here we compared sensitivities to pain and itch-provoking stimuli in naïve and injured young and aged mice. Surprisingly, we found that in the absence of injury, aged male and female mice are significantly less responsive to mechanical stimuli and, in females, also to noxious thermal (heat) stimuli. In both older male and female mice, compared to younger (6-month-old mice), we also recorded reduced pruritogen-evoked scratching. On the other hand, after nerve injury, aged mice nevertheless developed significant mechanical hypersensitivity. Interestingly, however, and in contrast to young mice, aged mice developed both ipsilateral and contralateral postinjury mechanical allodynia. In a parallel immunohistochemical analysis of microglial and astrocyte markers, we found that the ipsilateral to the contralateral ratio of nerve injury-induced expression decreased with age. That observation is consistent with our finding of contralateral hypersensitivity after nerve injury in the aged but not the young mice. We conclude that aging has opposite effects on baseline versus postinjury pain and itch processing. PERSPECTIVE: Aged male and female mice (22-24 months) are less sensitive to mechanical, thermal (heat), and itch-provoking stimuli than are younger mice (6 months).

Novel marine natural products as effective TRPV1 channel blockers

Chronic pain management poses a formidable challenge to healthcare, exacerbated by current analgesic options' limitations and adverse effects. Transient receptor potential vanilloid 1 (TRPV1), a non-selective cation channel, has emerged as a promising target for novel analgesics. However, safety and tolerability concerns have constrained the development of TRPV1 modulators. In this study, we explored marine-derived natural products as a source of potential TRPV1 modulators using high-throughput dye-uptake assays. We identified chrexanthomycins, a family of hexacyclic xanthones, exhibited potent TRPV1 inhibitory effects, with compounds cC and cF demonstrating the most significant activity. High-resolution patch-clamp assays confirmed the direct action of these compounds on the TRPV1 channel. Furthermore, in vivo assays revealed that cC and cF effectively suppressed capsaicin-induced pain sensation in mice, comparable to the known TRPV1 inhibitor, capsazepine. Structural-activity relationship analysis highlighted the importance of specific functional groups in modulating TRPV1 activity. Our findings underscore the therapeutic potential of chrexanthomycins and pave the way for further investigations into marine-derived TRPV1 modulators for pain management.

Adverse Drug Reactions to Opioids: A Study in a National Pharmacovigilance Database

INTRODUCTION

Opioids are commonly used as analgesics; however, like any medicine, they can produce adverse drug reactions (ADRs), including nausea, constipation, dependence, and respiratory depression, that result in harmful and fatal events. Therefore, it is essential to monitor the safety of these drugs in clinical practice.

OBJECTIVE

This study aimed to characterize the safety profile of opioids by conducting a descriptive study based on a spontaneous reporting system (SRS) for ADRs in The Netherlands, focusing on abuse, misuse, medication errors, and differences between sexes.

METHODS

Reports submitted to the Netherlands Pharmacovigilance Centre Lareb from January 2003 to December 2021 with an opioid drug as the suspected/interacting medicine were analyzed. Reporting odds ratios (RORs) for drug-ADR combinations were calculated, analyzed, and corrected for sex and drug utilization (expenditure) for the Dutch population.

RESULTS

A total of 8769 reports were analyzed. Tramadol was the opioid with the most reports during the period (n = 2746), while oxycodone or tramadol had the highest number of reports per year in the study period. The most reported ADRs from opioid use were nausea, followed by dizziness and vomiting, independent of sex, and all of them were more often reported in women. Vomiting associated with tramadol (ROR females/males = 2.17) was significantly higher in women. Buprenorphine was responsible for most ADRs when corrected for expenditure, with high RORs observed with application site hypersensitivity, application site reaction, and application site rash. Fentanyl gave rise to most of the reports of ADRs concerning abuse, misuse, and medication errors.

CONCLUSION

Patients treated with opioids experienced ADRs, primarily nausea, dizziness, and vomiting. For those groups of drugs, no significant differences were found between the sexes, except for the vomiting associated with tramadol. In general, ADRs related to opioids presented higher RORs when uncorrected and corrected for sexes and expenditure than other drugs. There was more disproportionate reporting for ADRs concerning abuse, misuse, and medication errors for opioids than other drugs in the Dutch SRS.

Systematic manipulation of experimenters' non-verbal behaviors for the investigation of pain reports and placebo effects

Objective

Non-verbal behaviors (NBs) of caregivers affect pain reports and placebo effects. However, little experimental research has systematically examined the caregivers' NBs. This study protocol and preparatory study report a systematic manipulation of experimenters' NBs to investigate pain report and placebo effects.

Methods

We propose an experiment in which videotaped experimenters (VEs) conduct a pain stimulation and a placebo treatment study. The VEs express one positively enhanced NB and keep the other NBs neutral. Participants will be randomized to either the positive facial expressions (+FE), tone of voice (+TV), body movement (+BM), or neutral NBs (i.e., neutral condition; NC) of the VEs. As a preparatory study for proof of concept, two groups of NB coders from Norway and the USA separately rated the degree of NBs (eye contact, body postures and movements, and tone of voice), and impressions of dominance and being in charge, positivity, and expressivity from each NB video. The NB videos had construct validity and reliability. The +BM and +FE were rated as more dominant and in charge than the +TV and the NC. The +FE and +BM were rated as the most positive and expressive NBs, respectively.

Expected results

+FE will have the largest placebo effects on pain and stress levels. However, transmitting the NBs to patients by VEs is challenging. Moreover, controlling for the effects of research assistants present in the testing room is challenging.

Discussion

We propose that caregivers' NBs affect pain reports and placebo effects. Moreover, different NBs elicit different impressions, and a better understanding of the role of caregiver NBs requires more rigorous investigations. Lastly, aiming to investigate the caregiver NBs, the varying degrees of micro-NBs and their effects on the formation of impressions should be considered.

The impact of sleep disturbance on pain perception: A systematic review examining the moderating effect of sex and age

Females have increased pain sensitivity and are more vulnerable to chronic pain conditions. Sleep disturbances are comorbid with chronic pain and exacerbate pain symptoms. Different types of sleep disturbance affect pain perception distinctly, but it is not clear if these effects are equal in men and women. This systematic review investigated potential differences in how sleep disturbance affects pain in males and females. We searched EBSCO, MEDLINE, Psych INFO, Science Direct, and Web of Science from January 2001 to November 2022 and found 38 studies with 978 participants. Separate random-effects models were used to estimate the pooled effect sizes based on standardized mean differences (SMDs) of experimental sleep disturbance paradigms on various pain outcomes. Sex moderated the effect of sleep disturbance on pain facilitation (SMD = 0.13; 95%CI: 0.004 to 0.022; p=.009) and pain inhibition (SMD = 0.033; 95%CI: 0.011 to 0.054; p=.005), with increased facilitation and decreased inhibition in females, but the opposite effect in males. Further, age moderated the effects of total sleep deprivation (SMD = -0.194; 95%CI -0.328 to -0.060; p=.008) on pain sensitivity and fragmented sleep (SMD = -0.110; 95%CI: 0.148 to -0.072; p<.001) on pain threshold. While the moderating effect of sex and age on the sleep-pain relationship was small, these factors need to be considered in future sleep-pain research.

Aging exaggerates pulpal pain sensation by increasing the expression levels of nociceptive neuropeptides and inflammatory cytokines

BACKGROUND

Dental pain is a main clinical problem in the elderly population and its assessment and treatment make special challenges for health care services. However, the age-induced alteration in dental pain perception and the underlying molecular mechanism(s) has not yet been fully clarified.

METHODS

Here, the effect of aging on nociceptive behaviors following inflammatory dental pulp pain was evaluated. Since prostaglandins, nociceptive neuropeptides, and inflammatory cytokines have critical roles in the development of aging as well as pain signaling, the expression levels of COX-2, CGRP, IL-1β, IL-6, TNF-α and its converting enzyme TACE were assessed in the trigeminal ganglion of young and aged rats with dental pain. Dental pulp pain was induced by intradental application of capsaicin (100 μg). The immunofluorescence (COX-2 and CGRP) and western blot techniques were used.

RESULTS

The data showed that aged animals have different pattern of pain. So that, the mean of nociceptive scores was significantly greater in aged rats at 10 and 15 min after capsaicin injection. In aged rats, dental pain was persisting over 7 h, while it was disappeared at 300 min in young rats. Molecular data showed that dental pain significantly increased the expression of COX-2, CGRP, IL-1β, IL-6, TNF-α and TACE in the trigeminal ganglion of the young and aged rats. In addition, the amount of those parameters, except TACE, in capsaicin-treated aged animals were significantly (p < 0.05) greater than those in capsaicin-treated young rats.

CONCLUSION

It seems that the induction of pro-inflammatory cytokines in an acute inflammatory pulpal pain model may contribute, at least in part to the increased nociceptive behaviors and pain perception in aged rats.

Sexual Dimorphism in the Mechanism of Pain Central Sensitization

It has long been recognized that men and women have different degrees of susceptibility to chronic pain. Greater recognition of the sexual dimorphism in chronic pain has resulted in increasing numbers of both clinical and preclinical studies that have identified factors and mechanisms underlying sex differences in pain sensitization. Here, we review sexually dimorphic pain phenotypes in various research animal models and factors involved in the sex difference in pain phenotypes. We further discuss putative mechanisms for the sexual dimorphism in pain sensitization, which involves sex hormones, spinal cord microglia, and peripheral immune cells. Elucidating the sexually dimorphic mechanism of pain sensitization may provide important clinical implications and aid the development of sex-specific therapeutic strategies to treat chronic pain.

Exploring sensory sensitivity, cortical excitability, and habituation in episodic migraine, as a function of age and disease severity, using the pattern-reversal task

BACKGROUND

Migraine is a cyclic, neurosensory disorder characterized by recurrent headaches and altered sensory processing. The latter is manifested in hypersensitivity to visual stimuli, measured with questionnaires and sensory thresholds, as well as in abnormal cortical excitability and a lack of habituation, assessed with visual evoked potentials elicited by pattern-reversal stimulation. Here, the goal was to determine whether factors such as age and/or disease severity may exert a modulatory influence on sensory sensitivity, cortical excitability, and habituation.

METHODS

Two similar experiments were carried out, the first comparing 24 young, episodic migraine patients and 28 healthy age- and gender-matched controls and the second 36 middle-aged, episodic migraine patients and 30 healthy age- and gender-matched controls. A neurologist confirmed the diagnoses. Migraine phases were obtained using eDiaries. Sensory sensitivity was assessed with the Sensory Perception Quotient and group comparisons were carried out. We obtained pattern-reversal visual evoked potentials and calculated the N1-P1 Peak-to-Peak amplitude. Two linear mixed-effects models were fitted to these data. The first model had Block (first block, last block) and Group (patients, controls) as fixed factors, whereas the second model had Trial (all trials) and Group as fixed factors. Participant was included as a random factor in both. N1-P1 first block amplitude was used to assess cortical excitability and habituation was defined as a decrease of N1-P1 amplitude across Blocks/Trials. Both experiments were performed interictally.

RESULTS

The final samples consisted of 18 patients with episodic migraine and 27 headache-free controls (first experiment) and 19 patients and 29 controls (second experiment). In both experiments, patients reported increased visual hypersensitivity on the Sensory Perception Quotient as compared to controls. Regarding N1-P1 peak-to-peak data, there was no main effect of Group, indicating no differences in cortical excitability between groups. Finally, significant main effects of both Block and Trial were found indicating habituation in both groups, regardless of age and headache frequency.

CONCLUSIONS

The results of this study yielded evidence for significant hypersensitivity in patients but no significant differences in either habituation or cortical excitability, as compared to headache-free controls. Although the alterations in patients may be less pronounced than originally anticipated they demonstrate the need for the definition and standardization of optimal methodological parameters.

Age-dependent immune and lymphatic responses after spinal cord injury

Spinal cord injury (SCI) causes lifelong debilitating conditions. Previous works demonstrated the essential role of the immune system in recovery after SCI. Here, we explored the temporal changes of the response after SCI in young and aged mice in order to characterize multiple immune populations within the mammalian spinal cord. We revealed substantial infiltration of myeloid cells to the spinal cord in young animals, accompanied by changes in the activation state of microglia. In contrast, both processes were blunted in aged mice. Interestingly, we discovered the formation of meningeal lymphatic structures above the lesion site, and their role has not been examined after contusive injury. Our transcriptomic data predicted lymphangiogenic signaling between myeloid cells in the spinal cord and lymphatic endothelial cells (LECs) in the meninges after SCI. Together, our findings delineate how aging affects the immune response following SCI and highlight the participation of the spinal cord meninges in supporting vascular repair.

Chronic pain following elective surgery under general anesthesia in older adults

BACKGROUND

The purpose of this study was to investigate the association between age and chronic postsurgical pain (CPSP) in patients who underwent elective surgery under general anesthesia, with a focus on long-term postsurgical analgesic use. To our knowledge, no previous study has examined this relationship in detail between older and younger patients.

METHODS

We conducted a propensity score-matched (PSM) study to compare the rates of long-term (3 or 6 months) postoperative analgesic use between older adult (≥ 65 years) and younger (< 65 years) patients. Multivariate logistic regression was used to assess the use of analgesics as a surrogate indicator of CPSP.

RESULTS

The PSM analysis included 62,784 surgical patients (31,392 in each group). Three months after surgery, the rates of analgesic use were significantly higher in the older age group (adjusted odds ratio [aOR], 1.45; 95% confidence interval [CI], 1.41-1.49) as well as for opioid use specifically (aOR, 1.34; 95% CI, 1.29-1.39). Six months after surgery, the rates of analgesic use remained higher in the older age group (aOR, 1.52; 95% CI, 1.47-1.58), and similarly for opioid use specifically (aOR, 1.42; 95% CI, 1.36-1.48).

CONCLUSIONS

Our findings suggest that older adults have higher rates of long-term analgesic use for CPSP after elective surgery under general anesthesia. This study highlights the importance of addressing CPSP in older adult patients and considering age-related factors when managing postoperative pain.

The effects of high-definition transcranial direct current stimulation on pain modulation and stress-induced hyperalgesia

Background

The dorsolateral prefrontal cortex (DLPFC) has been implicated in the modulation of pain-related signals. Given this involvement, manipulation of the DLPFC through transcranial direct current stimulation (tDCS) may influence internal pain modulation and decrease pain sensitivity. Acute stress is also thought to affect pain, with increased pain sensitivity observed following the presentation of an acute stressor.

Methods

A total of 40 healthy adults (50% male), ranging in age from 19 to 28 years (M = 22.13, SD = 1.92), were randomly allocated to one of two stimulation conditions (active and sham). High-definition tDCS (HD-tDCS) was applied for 10 min at 2 mA, with the anode placed over the left DLPFC. Stress was induced after HD-tDCS administration using a modified version of the Trier Social Stress Test. Pain modulation and sensitivity were assessed through the conditioned pain modulation paradigm and pressure pain threshold measurements, respectively.

Results

Compared to sham stimulation, active stimulation produced a significant increase in pain modulation capacity. No significant change in pain sensitivity and stress-induced hyperalgesia was observed following active tDCS.

Conclusion

This research shows novel evidence that anodal HD-tDCS over the DLPFC significantly enhances pain modulation. However, HD-tDCS had no effect on pain sensitivity or stress-induced hyperalgesia. The observed effect on pain modulation after a single dose of HD-tDCS over the DLPFC is a novel finding that informs further research into the utility of HD-tDCS in the treatment of chronic pain by presenting the DLPFC as an alternative target site for tDCS-induced analgesia.

The association of wound factors and symptoms of fatigue and pain with wound healing in chronic venous leg ulcers

The purpose of this study was: (1) to characterise the association of wound area, wound exudate C-reactive protein (CRP), broad-spectrum matrix metalloprotease protein (MMPs), and symptoms of fatigue and pain in individuals with chronic venous leg ulcers (CVLUs) over time and (2) to identify factors associated with the wound healing trajectory in CVLUs. Seventy four participants with CVLU who received weekly sharp debridement were recruited from a wound care clinic during the 8-week study period. To examine associations among wound CRP, MMPs, pain, fatigue, and wound healing trajectory over time, we calculated Bayes factors (BF) based on a linear mixed model. The mean age of participants was 71.8 (SD = 9.8) and the mean wound area was 2278 mm² (SD = 7085 mm² ) at baseline. Higher fatigue was strongly associated with higher MMPs (BF = 9, 95% HDI: [-.05, .43]), lower CRP (BF = 11, 95% HDI: [-.02, .002]), and large areas of wound (BF = 20, 95% HDI: [-.001, .01]). Higher CRP and MMPs activity in wound exudate and higher fatigue were associated with a larger wound area. To facilitate wound healing, clinicians need to utilise the multifactorial approach, which includes wound treatment and management of symptoms such as pain and fatigue, because of the molecular and psycho-behavioural factors involved in wound healing.

Estimation of effects of extreme temperature on the risk of hospitalisation in Taiwan

BACKGROUND

Extreme temperatures are triggering and exacerbating hospital admissions and health burdens; however, it is still understudied. Therefore, we evaluated the effects of the average temperature on overall hospitalisation and the average length of hospital stay.

METHODS

Daily area-specific age-sex stratified hospitalisation records from 2006 to 2020 were collected from the National Health Research Institutes of Taiwan. The distributed lag non-linear model was used to estimate the area-specific relative risk (RR) and 95% CI associated with daily average temperature. Overall cumulative RR was pooled from area-specific RRs using random effects meta-analysis. Temperature effects of extreme high and low thresholds were also evaluated based on the 99th (32°C) and 5th (14°C) percentiles, respectively.

RESULTS

Our findings suggested that the elderly (age ≥65 years) are vulnerable to temperature effects, while differential gender effects are not explicit in Taiwan. A higher risk of in-patient visits was seen among the elderly during extreme low temperatures (RR 1.08; 95% CI 1.04 to 1.11) compared with extreme high temperatures (RR 1.07; 95% CI 1.05 to 1.10). Overall, high-temperature extremes increased the risk of hospitalisation with an RR of 1.05 (95% CI 1.03 to 1.07) among the all-age-sex population in Taiwan. Additionally, lag-specific analysis of the study revealed that high-temperature effects on in-patient visits are effective on the same day of exposure, while cold effects occurred after 0-2 days of exposure. The average length of hospital stays can also increase with high-temperature extremes among age group 41-64 years and the elderly.

CONCLUSION

Public health preparedness should consider the increased load on health facilities and health expenditures during extreme temperatures.

Median Effective Dose of Remifentanil for the Prevention of Pain Caused by the Injection of Rocuronium: An Age-Stratified Study

INTRODUCTION

Rocuronium intravenous pain is common in induction of general anesthesia. The aim of our study was to determine the median effective dose (ED₅₀) of prophylactic intravenous remifentanil for the prevention of rocuronium injection pain and to explore the effect of age on the ED₅₀.

METHODS

Eighty-nine adult patients undergoing elective general anesthesia, ASA I or II, regardless of gender or weight, were stratified according to age: group R1 18-44 years, group R2 45-59 years, and group R3 60-80 years. The initial dose of prophylactic remifentanil before rocuronium injection was set at 1 μg/kg lean body weight (LBW). The remifentanil doses were adjusted according to the degree of injection pain using the Dixon sequential method, with a ratio of 1.1 between adjacent doses. Injection pain was graded, and the occurrence of injection pain and adverse reactions were recorded. The ED₅₀ and 95% confidence intervals (CIs) of remifentanil were calculated using the Dixon-Massey formula. Patients were asked whether they recalled feeling any injection pain in the post-anesthesia care unit (PACU).

RESULTS

The ED₅₀ (95% CIs) of prophylactic remifentanil for the prevention of rocuronium injection pain were 1.266 μg/kg (1.186-1.351 μg/kg), 1.188 μg/kg (1.065-1.324 μg/kg), and 1.070 μg/kg (1.014-1.129 μg/kg) LBW in group R1, group R2, and group R3, respectively. No adverse reactions to remifentanil occurred in any group. In PACU, 84.6, 86.7, and 85.7% of patients who experienced injection pain had memories of the pain in group R1, group R2, and group R3, respectively.

CONCLUSIONS

Prophylactic intravenous remifentanil can prevent rocuronium injection pain, and its ED₅₀ decreases with age, with 1.266 μg/kg (18-44 years), 1.188 μg/kg (45-59 years), and 1.070 μg/kg LBW (60-80 years), respectively.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05217238 (registration date 18 Dec 2021).

Mimicking Pain-Perceptual Sensitization and Pattern Recognition Based on Capacitance- and Conductance-Regulated Neuroplasticity in Neural Network

Neuromorphic computing, inspired by the biological neuronal system, is a high potential approach to substantially alleviate the cost of computational latency and energy for massive data processing. Artificial synapses with regulable synaptic weights are the basis of neuromorphic computation, providing an efficient and low-power system to overcome the constraints of the von Neumann architecture. Here, we report an ITO/TaOx-based synaptic capacitor and transistor. With the drift motion of mobile-charged ions in the TaOx, the capacitance and channel conductance can be tuned to exhibit synaptic weight modulation. Robust stability in the cycle-to-cycle (C2C) variation is found in capacitance and conductance potentiation/depression weight updating of 0.9 and 1.8%, respectively. Simulation results show a higher classification accuracy of handwritten digit recognition (95%) in capacitance synapses than that in conductance synapses (84%). Besides, the synaptic capacitor consumes much less energy than the synaptic transistor. Moreover, the ITO/TaOx-based capacitor successfully emulates the pain-perceptual sensitization on top of the superior performance, indicating its promising potential in applying the capacitive neural network.

Age-dependent and modality-specific changes in the phenotypic markers Nav1.8, ASIC3, P2X3 and TRPM8 in male rat primary sensory neurons during healthy aging

The effects during healthy aging of the tetrodotoxin-resistant voltage-gated sodium channel 1.8 (Nav1.8), the acid-sensing ion channel-3 (ASIC3), the purinergic-receptor 2X3 (P2X3) and transient receptor potential of melastatin-8 (TRPM8) on responses to non-noxious stimuli are poorly understood. These effects will influence the transferability to geriatric subjects of findings obtained using young animals. To evaluate the involvement of these functional markers in mechanical and cold sensitivity to non-noxious stimuli and their underlying mechanisms, we used a combination of immunohistochemistry and quantitation of immunostaining in sub-populations of neurons of the dorsal root ganglia (DRG), behavioral tests, pharmacological interventions and Western-blot in healthy male Wistar rats from 3 to 24 months of age. We found significantly decreased sensitivity to mechanical and cold stimuli in geriatric rats. These behavioural alterations occurred simultaneously with differing changes in the expression of Nav1.8, ASIC3, P2X3 and TRPM8 in the DRG at different ages. Using pharmacological blockade in vivo we demonstrated the involvement of ASIC3 and P2X3 in normal mechanosensation and of Nav1.8 and ASIC3 in cold sensitivity. Geriatric rats also exhibited reductions in the number of A-like large neurons and in the proportion of peptidergic to non-peptidergic neurons. The changes in normal sensory physiology in geriatric rats we report here strongly support the inclusion of aged rodents as an important group in the design of pre-clinical studies evaluating pain treatments.

Nine-month-long Social Isolation Changes the Levels of Monoamines in the Brain Structures of Rats: A Comparative Study of Neurochemistry and Behavior

Social isolation (SI) is chronic psycho-emotional stress for humans and other socially living species. There are few comparative studies that have measured monoamine levels in brain structures in male and female rats subjected to SI. Existing data is highly controversial. In our recent study, we investigated behavioral effects of SI prolonged up to 9 months on a rather large sample of 69 male and female Wistar rats. In the present study, we measured the levels of monoamines-norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT), and DA and 5-HT metabolites-in the brain structures of 40 rats from the same sample. The single-housed rats of both sexes showed hyperactivity and reduced reactivity to novelty in the Open Field test, and impaired passive avoidance learning. Regardless of their sex, by the time of sacrifice, the single-housed rats weighed less and had lower pain sensitivity and decreased anxiety compared with group-housed animals. SI decreased NE levels in the hippocampus and increased them in the striatum. SI induced functional activation of the DA-ergic system in the frontal cortex and hypothalamus, with increased DA and 3-methoxytyramine levels. SI-related changes were found in the 5-HT-ergic system: 5-HT levels increased in the frontal cortex and striatum, while 5-hydroxyindoleacetic acid only increased in the frontal cortex. We believe that SI prolonged for multiple months could be a valuable model for comparative analysis of the behavioral alterations and the underlying molecular processes in dynamics of adaptation to chronic psychosocial stress in male and female rats in relation to age-dependent changes.

Factors associated with persistent postsurgical pain after total knee or hip joint replacement: a systematic review and meta-analysis

Studies have identified demographic, clinical, psychosocial, and perioperative variables associated with persistent pain after a variety of surgeries. This study aimed to perform a systematic review and meta-analysis of factors associated with persistent pain after total knee replacement (TKR) and total hip replacement (THR) surgeries. To meet the inclusion criteria, studies were required to assess variables before or at the time of surgery, include a persistent postsurgical pain (PPSP) outcome measure at least 2 months after a TKR or THR surgery, and include a statistical analysis of the effect of the risk factor(s) on the outcome measure. Outcomes from studies implementing univariate and multivariable statistical models were analyzed separately. Where possible, data from univariate analyses on the same factors were combined in a meta-analysis. Eighty-one studies involving 171,354 patients were included in the review. Because of the heterogeneity of assessment methods, only 44% of the studies allowed meaningful meta-analysis. In meta-analyses, state anxiety (but not trait anxiety) scores and higher depression scores on the Beck Depression Inventory were associated with an increased risk of PPSP after TKR. In the qualitative summary of multivariable analyses, higher preoperative pain scores were associated with PPSP after TKR or THR. This review systematically assessed factors associated with an increased risk of PPSP after TKR and THR and highlights current knowledge gaps that can be addressed by future research.

Subgrouping patients with zoster-associated pain according to sensory symptom profiles: A cluster analysis

Background and goal of study

Patients with zoster-associated pain exhibit a variety of sensory symptoms and forms of pain and complain of different pain patterns. The purpose of this study is to subgroup patients with zoster-associated pain who visited a hospital using painDETECT sensory symptom scores, analyze their respective characteristics and pain-related data, and compare similarities and differences among the groups.

Materials and methods

The characteristics of 1,050 patients complaining of zoster-associated pain and pain-related data were reviewed retrospectively. To identify subgroups of patients with zoster-associated pain according to sensory symptom profiles, a hierarchical cluster analysis was performed based on the responses to a painDETECT questionnaire. Demographics and pain-related data were compared among all subgroups.

Results and discussion

Patients with zoster-associated pain were classified into 5 subgroups according to the distribution of sensory profiles, with each subgroup exhibiting distinct differences in the expression of sensory symptoms. Patients in cluster 1 complained of burning sensations, allodynia, and thermal sensitivity, but felt numbness less strongly. Cluster 2 and 3 patients complained of burning sensations and electric shock-like pain, respectively. Cluster 4 patients complained of most sensory symptoms at similar intensities and reported relatively strong prickling pain. Cluster 5 patients suffered from both burning and shock-like pains. Patient ages and the prevalence of cardiovascular disease were significantly lower in cluster 1. Patients in clusters 1 and 4 reported longer pain duration compared with those in clusters 2 and 3. However, no significant differences were found with respect to sex, body mass index, diabetes mellitus, mental health problems, and sleep disturbance. Pain scores, distribution of dermatomes and gabapentinoid use were also similar among the groups.

Conclusions

Five different subgroups of patients with zoster-associated pain were identified on the basis of sensory symptoms. A subgroup of younger patients with longer pain duration showed specific and distinct symptoms, such as burning sensations and allodynia. Unlike patients with acute or subacute pain, patients with chronic pain were associated with diverse sensory symptom profiles.

Incidence and risk factors for acute shoulder pain after hepatectomy: a nested case-control study

BACKGROUND

Shoulder pain is commonly reported after hepatic surgery; however, the factors affecting post-hepatectomy shoulder pain remain unclear. This study aimed to determine the incidence and risk factors of shoulder pain after hepatectomy.

METHODS

This prospective cohort study recruited 218 patients who underwent hepatic resection at our hospital from June to September 2022. Data were obtained from electronic medical records and follow-up assessments on the second postoperative day. All patients denied chronic pain before surgery. In this cohort study, patients were grouped according to the appearance of shoulder pain. Demographic information and perioperative data were compared between the two groups. The relationship between shoulder pain and independent variables was assessed using univariate binary logistic regression analysis. The potential risk factors were analyzed using multivariable binary logistic regression.

RESULTS

Of the 218 patients enrolled in this cohort study, 91 (41.7%) reported shoulder pain. Patients in the case group were significantly younger than those in the control group (P = 0.001). Epidural anesthesia was used more frequently in the case group (P = 0.012). Patients over 60 years of age showed a lower incidence of shoulder pain than younger patients (P = 0.028). According to multivariable binary logistic regression analysis, advanced age and epidural anesthesia were associated with risk of shoulder pain (advanced age: odds ratio [OR] [95% confidence interval (CI)]: 0.96 [0.94, 0.99], P = 0.002; epidural anesthesia: OR [95% CI]: 2.08 [1.18, 3.69], P = 0.012).

CONCLUSIONS

The incidence of acute shoulder pain after hepatectomy is 41.7%. The application of epidural anesthesia is an independent risk factor for shoulder pain after hepatectomy, whereas advanced age is a protective factor.

Local translation in primary afferents and its contribution to pain

ABSTRACT

Chronic pain remains a significant problem due to its prevalence, impact, and limited therapeutic options. Progress in addressing chronic pain is dependent on a better understanding of underlying mechanisms. Although the available evidence suggests that changes within the central nervous system contribute to the initiation and maintenance of chronic pain, it also suggests that the primary afferent plays a critical role in all phases of the manifestation of chronic pain in most of those who suffer. Most notable among the changes in primary afferents is an increase in excitability or sensitization. A number of mechanisms have been identified that contribute to primary afferent sensitization with evidence for both increases in pronociceptive signaling molecules, such as voltage-gated sodium channels, and decreases in antinociceptive signaling molecules, such as voltage-dependent or calcium-dependent potassium channels. Furthermore, these changes in signaling molecules seem to reflect changes in gene expression as well as posttranslational processing. A mechanism of sensitization that has received far less attention, however, is the local or axonal translation of these signaling molecules. A growing body of evidence indicates that this process not only is dynamically regulated but also contributes to the initiation and maintenance of chronic pain. Here, we review the biology of local translation in primary afferents and its relevance to pain pathobiology.

Osteoarthritis Pain in Old Mice Aggravates Neuroinflammation and Frailty: The Positive Effect of Morphine Treatment

Knee osteoarthritis is a common cause of pain and disability in old subjects. Pain may predispose to the development of frailty. Studies on mechanisms underlying pain in osteoarthritis models during aging are lacking. In this work, we used the monosodium iodoacetate model of osteoarthritis in adult (11-week-old) and old (20-month-old) C57BL/6J mice to compare hypersensitivity, locomotion, neuroinflammation, and the effects of morphine treatment. After osteoarthritis induction in adult and old mice, weight-bearing asymmetry, mechanical allodynia, and thermal hyperalgesia similarly developed, while locomotion and frailty were more affected in old than in adult animals. When behavioral deficits were present, the animals were treated for 7 days with morphine. This opioid counteracts the behavioral alterations and the frailty index worsening both in adult and old mice. To address the mechanisms that underlie pain, we evaluated neuroinflammatory markers and proinflammatory cytokine expression in the sciatic nerve, DRGs, and spinal cord. Overexpression of cytokines and glia markers were present in osteoarthritis adult and old mice, but the activation was qualitatively and quantitatively more evident in aged mice. Morphine was able to counteract neuroinflammation in both age groups. We demonstrate that old mice are more vulnerable to pain's detrimental effects, but prompt treatment is successful at mitigating these effects.

What is the quality of life in patients with long COVID compared to a healthy control group?

Introduction

Many patients have prolonged symptoms after COVID-19 infection, which can affect patient quality of life (QOL). The aim of this study is to determine the quality of life in patients with long COVID, compared with healthy controls.

Material and methods

The study was a prospective cross-sectional study using an anonymous online survey. The SF-36 questionnaire was chosen for quality of life measurement. The survey was distributed through the Facebook social media platform targeting groups of patients with long COVID. The control group was made up of physiotherapy and physical education students.

Results

There was a significant difference in physical function, with a mean score of 94.9 (±9.4) among the students, compared to long COVID patients with a mean score of 66.2 (±25.4) (p < 0.001). A similar result was found in the physical role (p < 0.001). The overall quality of life score for college students was 578.0 (±111.9), and the overall score for patients with long COVID was 331.9 (±126.9).

Conclusions

Patients with long COVID had a lower quality of life compared to the healthy control group, and this was associated with the negative effect of long-COVID. Lower quality of life in patients with long COVID is an important therapeutic goal, which requires attention.

Establishment and validation of the survival prediction risk model for appendiceal cancer

OBJECTIVE

Establishing a risk model of the survival situation of appendix cancer for accurately identifying high-risk patients and developing individualized treatment plans.

METHODS

A total of 4,691 patients who were diagnosed with primary appendix cancer from 2010 to 2016 were extracted using Surveillance, Epidemiology, and End Results (SEER) * Stat software. The total sample size was divided into 3,283 cases in the modeling set and 1,408 cases in the validation set at a ratio of 7:3. A nomogram model based on independent risk factors that affect the prognosis of appendix cancer was established. Single-factor Cox risk regression, Lasso regression, and multifactor Cox risk regression were used for analyzing the risk factors that affect overall survival (OS) in appendectomy patients. A nomogram model was established based on the independent risk factors that affect appendix cancer prognosis, and the receiver operating characteristic curve (ROC) curve and calibration curve were used for evaluating the model. Survival differences between the high- and low-risk groups were analyzed through Kaplan-Meier survival analysis and the log-rank test. Single-factor Cox risk regression analysis found age, ethnicity, pathological type, pathological stage, surgery, radiotherapy, chemotherapy, number of lymph nodes removed, T stage, N stage, M stage, tumor size, and CEA all to be risk factors for appendiceal OS. At the same time, multifactor Cox risk regression analysis found age, tumor stage, surgery, lymph node removal, T stage, N stage, M stage, and CEA to be independent risk factors for appendiceal OS. A nomogram model was established for the multifactor statistically significant indicators. Further stratified with corresponding probability values based on multifactorial Cox risk regression, Kaplan-Meier survival analysis found the low-risk group of the modeling and validation sets to have a significantly better prognosis than the high-risk group (p < 0.001).

CONCLUSION

The established appendix cancer survival model can be used for the prediction of 1-, 3-, and 5-year OS and for the development of personalized treatment options through the identification of high-risk patients.

Challenges with Assessing and Treating Pain in Research Primates: A Focused Survey and Literature Review

Research primates may undergo surgical procedures making effective pain management essential to ensure good animal welfare and unbiased scientific data. Adequate pain mitigation is dependent on whether veterinarians, technicians, researchers, and caregivers can recognize and assess pain, as well as the availability of efficacious therapeutics. A survey was conducted to evaluate primate veterinary approaches to pain assessment and alleviation, as well as expressed challenges for adequately managing primate pain. The survey (n = 93 respondents) collected information regarding institutional policies and procedures for pain recognition, methods used for pain relief, and perceived levels of confidence in primate pain assessment. Results indicated that 71% (n = 60) of respondents worked at institutions that were without formal experimental pain assessment policies. Pain assessment methods were consistent across respondents with the majority evaluating pain based on changes in general activity levels (100%, n = 86) and food consumption (97%, n = 84). Self-reported confidence in recognizing and managing pain ranged from slightly confident to highly confident, and there was a commonly expressed concern about the lack of objective pain assessment tools and science-based evidence regarding therapeutic recommendations of analgesics for research primates. These opinions correspond with significant gaps in the primate pain management literature, including limited specific pharmacokinetic data and efficacy testing for commonly used analgesics in research primate species as well as limited research on objective and specific measures of pain in research primates. These results demonstrate that there are inconsistencies in institutional policies and procedures surrounding pain management in research primates and a lack of objective pain assessment methods. Demonstrating the gaps and challenges in primate pain management can inform guideline development and suggest areas for future research.

Design a protocol to investigate the effects of climate change in vivo

Climate change has a variety of effects on communities and the environment, most of which have been directly addressed, such as floods, droughts, and fires. To date, the impacts of climate change on health in in vivo conditions have not been assessed, and no protocol has been developed in this regard. Therefore, the purpose of the current study is to develop a protocol as well as design and build a pilot to deal with climate change in vivo to show the direct effects of climate change on health. For this purpose, twenty specialists, comprising ten experts active in field climate and 10 experts in field medicine and anatomy, have been consulted to design the proposed exposure protocol using the Delphi method. According to the prepared protocol, an exposure pilot was then designed and built, which provides the climatic conditions for animal exposure with a fully automatic HMI-PLC system. The results showed the average 12:12-h day/night temperature, humidity, and circadian cycle for three consecutive ten-year periods selected for exposure of 1-month-old male rats. The duration of the exposure period is four months, which is equivalent to a ten-year climatic period. This study is a framework and a starting point for examining the effects of climate change on in vivo conditions that have not yet been considered.

Effect of Virtual Reality Hypnosis on Pain Threshold and Neurophysiological and Autonomic Biomarkers in Healthy Volunteers: Prospective Randomized Crossover Study

Background

Virtual reality hypnosis (VRH) is a promising tool to reduce pain. However, the benefits of VRH on pain perception and on the physiological expression of pain require further investigation.

Objective

In this study, we characterized the effects of VRH on the heat pain threshold among adult healthy volunteers while monitoring several physiological and autonomic functions.

Methods

Sixty healthy volunteers were prospectively included to receive nociceptive stimulations. The first set of thermal stimuli consisted of 20 stimulations at 60°C (duration 500 milliseconds) to trigger contact heat evoked potentials (CHEPs). The second set of thermal stimuli consisted of ramps (1°C/second) to determine the heat pain threshold of the participants. Electrocardiogram, skin conductance responses, respiration rate, as well as the analgesia nociception index were also recorded throughout the experiment.

Results

Data from 58 participants were analyzed. There was a small but significant increase in pain threshold in VRH (50.19°C, SD 1.98°C) compared to that in the control condition (mean 49.45°C, SD 1.87; P<.001, Wilcoxon matched-pairs signed-rank test; Cohen d=0.38). No significant effect of VRH on CHEPs and heart rate variability parameters was observed (all P>0.5; n=22 and n=52, respectively). During VRH, participants exhibited a clear reduction in their autonomic sympathetic tone, as shown by the lower number of nonspecific skin conductance peak responses (P<.001, two-way analysis of variance; n=39) and by an increase in the analgesia nociception index (P<.001, paired t-test; n=40).

Conclusions

The results obtained in this study support the idea that VRH administration is effective at increasing heat pain thresholds and impacts autonomic functions among healthy volunteers. As a nonpharmacological intervention, VRH has beneficial action on acute experimental heat pain. This beneficial action will need to be evaluated for the treatment of other types of pain, including chronic pain.

Regulatory Emotional Self-Efficacy Buffers the Effect of Heart Rate Variability on Functional Capacity in Older Adults With Chronic Low Back Pain

Introduction

Chronic low back pain is one of the leading causes of disability globally among older adults. Prevailing research suggests that autonomic dysregulation places individuals at increased risk for chronic pain. This study examines the moderating role of emotional self-efficacy (ESE) on the relationship between heart rate variability (HRV) and pain related-outcomes, including movement-evoked pain (MEP) and physical functioning.

Methods

In a secondary analysis of the Adaptability and Resilience in Aging Adults (ARIAA) study, a total of 58 adults (aged 60 and older) with chronic low back pain (cLBP) completed the PROMIS self-efficacy for managing emotions questionnaire and the 6-minute walk test (6 MWT) to assess functional capacity and MEP. Heart rate variability, indexed by the frequency domain, was assessed for 5 min during rest.

Results

For pain-related outcomes, having a lower body mass index (p = 0.03) was associated with better functional capacity on the 6MWT, while higher education level (p = 0.01) and less pain duration (p = 0.00) were correlated with lower MEP. After controlling for sex, age, and body mass index, an increase in low-frequency HRV (LF-HRV) was associated with poorer physical functioning among individuals low in ESE (b = −0.12 p = 0.03). No significant moderation effects were observed for MEP.

Conclusion

Our results bring attention to the degree to which ESE influences the relationship between LF-HRV and physical functioning. Interventions that enhance adaptive psychological processes such as ESE may dampen ANS dysregulation and mitigate risk for adverse pain outcomes among older adults with cLBP.

Improved acquisition of contact heat evoked potentials with increased heating ramp

Contact heat evoked potentials (CHEPs) represent an objective and non-invasive measure to investigate the integrity of the nociceptive neuraxis. The clinical value of CHEPs is mostly reflected in improved diagnosis of peripheral neuropathies and spinal lesions. One of the limitations of conventional contact heat stimulation is the relatively slow heating ramp (70 °C/s). This is thought to create a problem of desynchronized evoked responses in the brain, particularly after stimulation in the feet. Recent technological advancements allow for an increased heating ramp of contact heat stimulation, however, to what extent these improve the acquisition of evoked potentials is still unknown. In the current study, 30 healthy subjects were stimulated with contact heat at the hand and foot with four different heating ramps (i.e., 150 °C/s, 200 °C/s, 250 °C/s, and 300 °C/s) to a peak temperature of 60 °C. We examined changes in amplitude, latency, and signal-to-noise ratio (SNR) of the vertex (N2-P2) waveforms. Faster heating ramps decreased CHEP latency for hand and foot stimulation (hand: F = 18.41, p < 0.001; foot: F = 4.19, p = 0.009). Following stimulation of the foot only, faster heating ramps increased SNR (F = 3.32, p = 0.024) and N2 amplitude (F = 4.38, p = 0.007). Our findings suggest that clinical applications of CHEPs should consider adopting faster heating ramps up to 250 °C/s. The improved acquisition of CHEPs might consequently reduce false negative results in clinical cohorts. From a physiological perspective, our results demonstrate the importance of peripherally synchronizing afferents recruitment to satisfactorily acquire CHEPs.

What Did We Learn About Fracture Pain from Animal Models?

Progress in bone fracture repair research has been made possible due to the development of reproducible models of fracture in rodents with more clinically relevant fracture fixation, where there is considerably better assessment of the factors that affect fracture healing and/or novel therapeutics. However, chronic or persistent pain is one of the worst, longest-lasting and most difficult symptoms to manage after fracture repair, and an ongoing challenge remains for animal welfare as limited information exists regarding pain scoring and management in these rodent fracture models. This failure of adequate pre-clinical pain assessment following osteotomy in the rodent population may not only subject the animal to severe pain states but may also affect the outcome of the bone healing study. Animal models to study pain were also mainly developed in rodents, and there is increasing validation of fracture and pain models to quantitatively evaluate fracture pain and to study the factors that generate and maintain fracture pain and develop new therapies for treating fracture pain. This review aims to discuss the different animal models for fracture pain research and characterize what can be learned from using animal models of fracture regarding behavioral pain states and new molecular targets for future management of these behaviors.

Prevalence and risk factors of musculoskeletal pain in patients with chronic obstructive pulmonary disease: A systematic review

OBJECTIVES

This systematic review aimed to discuss the prevalence and the risk factors of the musculoskeletal pain in chronic obstructive pulmonary disease (COPD).

DATA SOURCE AND STUDY SELECTION

Four databases were analysed (Scopus, PubMed, Cochrane and EMBASE). We excluded systematic reviews, meta-analyses, conference abstracts and case reports. Two authors independently checked for the eligibility of the relevant articles. The risk of bias was evaluated using the Newcastle Ottawa Quality Assessment Scale and the Joanna Briggs Institute critical appraisal checklist. The selection and evaluation of studies followed the PRISMA guidelines.

RESULTS

Twenty studies were retrieved, including from 21 to 7952 patients with COPD. The prevalence of pain was highly heterogeneous across studies: 7-89.7%. Pain was mostly reported in the lumbar (7-69%) and cervical spine (11-48.3%) and the chest (44-82.8%). The main risk factors for developing pain were old age, sex (female), level of physical activity (low) and comorbidities.

CONCLUSION

Pain is a very common symptom in patients with COPD. Despite this, few clinical trials have investigated the pain. It appears to be located primarily in the lumbar, cervical and thoracic regions and facilitated by being a female, a low level of physical activity, comorbidity(ies) and old age.

The relationship between pain severity and sleep quality: Posttube thoracostomy

BACKGROUND

The presence of a chest tube is a factor significantly associated with pain and pain posttube thoracostomy that negatively affects sleep quality (SQ).

AIM

To determine the relationship between the pain severity and SQ of patients who underwent the tube thoracostomy (TT).

METHODS

This was a descriptive and cross-sectional survey conducted from May 1, 2018, to December 30, 2018, in the thoracic surgery department of Sivas Cumhuriyet University Hospital in Central Anatolia/Turkey. Data were collected using a questionnaire form, a Numerical Rating Scale to determine pain severity, and the Richard-Campbell Sleep Questionnaire to assess SQ.

RESULTS

The study was carried out with 102 patients who underwent the TT. The mean age of the participants were 48.94 years. The mean scores for the scale items indicated that during the procedure and on the first day of post-TT, the pain severity of the patients was very high, their SQ was low. Pain level decreased gradually in the following days, and the SQ increased. There was a positive, strong correlation between the post-TT first day pain and first night SQ (r = 0.380, p = 0.000), second day pain and second night SQ (r = -0.537, p = 0.000), and third day pain and third night SQ (r = -0.507, p = 0.000).

CONCLUSION

The results of this study highlight that the pain severity of post-TT significantly affect the quality of the patients' night sleep.

Anterior Cingulate Cortex Activity During Rest Is Related to Alterations in Pain Perception in Aging

Alterations in the affective component of pain perception are related to the development of chronic pain and may contribute to the increased vulnerability to pain observed in aging. The present study analyzed age-related changes in resting-state brain activity and their possible relation to an increased pain perception in older adults. For this purpose, we compared EEG current source density and fMRI functional-connectivity at rest in older (n = 20, 66.21 ± 3.08 years) and younger adults (n = 21, 20.71 ± 2.30 years) and correlated those brain activity parameters with pain intensity and unpleasantness ratings elicited by painful stimulation. We found an age-related increase in beta2 and beta3 activity in temporal, frontal, and limbic areas, and a decrease in alpha activity in frontal areas. Moreover, older participants displayed increased functional connectivity in the anterior cingulate cortex (ACC) and the insula with precentral and postcentral gyrus. Finally, ACC beta3 activity was positively correlated with pain intensity and unpleasantness ratings in older, and ACC-precentral/postcentral gyrus connectivity was positively correlated with unpleasantness ratings in older and younger participants. These results reveal that ACC resting-state hyperactivity is a stable trait of brain aging and may underlie their characteristic altered pain perception.

Placebo Effects on Stress, but Not on Pain Reports. A Multi-Experiment Study

Background

Contextual factors, such as participant/experimenter sex may moderate the placebo effects. We tested whether the participant and experimenter sex modulated placebo effects on experimentally induced pain and associated stress.

Objective

To investigate if (i) participant sex and (ii) experimenter sex influence placebo analgesia and subjective and physiological stress in two experiments employing a within-subjects and a mixed design, respectively. Placebo effects were investigated in pain reports, stress, and blood pressure.

Methods

Participants received painful stimulations and a placebo cream. In Experiment One (N = 59) participants underwent a placebo condition (PC) and a natural history condition (NHC) in random order. A placebo cream was applied in the PC and then the heat stimulation temperature was surreptitiously lowered. Identical stimulations were administered in the NHC, but with no cream, no information, and no lowered temperature. In Experiment Two, participants (N = 93) were randomly assigned to three groups receiving either a placebo cream with surreptitiously lowered intensity of electric stimuli (Placebo, PG), a placebo cream (Cream-Control, CCG) without changing the stimuli, or lowered intensity, but with no cream (Pain-Control, PCG) in a mixed design. All participants in both experiments received the same stimuli in the post-test as in the pre-test. Four experimenters (two females) in Experiment One, and five experimenters (two females) in Experiment Two conducted the studies.

Results

No placebo effect was seen on pain. However, there were placebo effects on stress, moderated by participant and experimenter sex: in Experiment One males in the PC had lower diastolic blood pressure (DBP) compared to males in the NHC. Participants in the PC had lower DBP compared to the NHC when tested by a female. In Experiment Two, participants expected more cream effectiveness when a female experimenter administered it, and reported lower stress in the PG compared to the PCG when tested by females.

Conclusion

Our findings highlight a distinction between placebo effects on pain and on associated stress. Secondly, female experimenters recorded lower physiological and subjective stress, higher effectiveness expectations, and lower pain from both sexes compared to male experimenters. Possible reasons for the failure to find a pain placebo effect are discussed.