Does neonatal surgery lead to increased pain sensitivity in later childhood?

Predicting postoperative pain in children: an observational study using the pain threshold Index

Objective

While the pain threshold index (PTI) holds potential as a tool for monitoring analgesia-pain equilibrium, its precision in forecasting postoperative pain in children remains unconfirmed. This study's primary aim was to assess the PTI's predictive precision for postoperative pain.

Methods

Children (aged 2-16 years) undergoing general surgery under general anesthesia were included. Within 5 min prior to the patient's emergence from surgery, data including PTI, wavelet index (WLI), heart rates (HR) and mean arterial pressure (MAP) were collected. Subsequently, a 15-min pain assessment was conducted following the patient's awakening. The accuracy of these indicators in discerning between mild and moderate to severe postoperative pain was evaluated through receiver operating characteristic (ROC) analysis.

Results

The analysis encompassed data from 90 children. ROC analysis showed that PTI was slightly better than HR, MAP and WLI in predicting postoperative pain, but its predictive value was limited. The area under the curve (AUC) was 0.659 [0.537∼0.780] and the optimal threshold was 65[64-67]. Sensitivity and specificity were determined at 0.90 and 0.50, respectively. In a multivariable logistic regression model, a higher predictive accuracy was found for a multivariable predictor combining PTI values with gender, BMI, HR and MAP (AUC, 0.768; 95%CI, 0.669-0.866). Upon further scrutinizing the age groups, PTI's AUC was 0.796 for children aged 9-16, 0.656 for those aged 4-8, and 0.601 for younger individuals.

Conclusions

PTI, when used alone, lacks acceptable accuracy in predicting postoperative pain in children aged 2 to 16 years. However, when combined with other factors, it shows improved predictive accuracy. Notably, PTI appears to be more accurate in older children.

Dexmedetomidine as a Short-Use Analgesia for the Immature Nervous System

Pain management in neonates continues to be a challenge. Diverse therapies are available that cause loss of pain sensitivity. However, because of side effects, the search for better options remains open. Dexmedetomidine is a promising drug; it has shown high efficacy with a good safety profile in sedation and analgesia in the immature nervous system. Though dexmedetomidine is already in use for pain control in neonates (including premature neonates) and infants as an adjunct to other anesthetics, the question remains whether it affects the neuronal activity patterning that is critical for development of the immature nervous system. In this study, using the neonatal rat as a model, the pharmacodynamic effects of dexmedetomidine on the nervous and cardiorespiratory systems were studied. Our results showed that dexmedetomidine has pronounced analgesic effects in the neonatal rat pups, and also weakly modified both the immature network patterns of cortical and hippocampal activity and the physiology of sleep cycles. Though the respiration and heart rates were slightly reduced after dexmedetomidine administration, it might be considered as the preferential independent short-term therapy for pain management in the immature and developing brain.

Macrophage memories of early-life injury drive neonatal nociceptive priming

The developing peripheral nervous and immune systems are functionally distinct from those of adults. These systems are vulnerable to early-life injury, which influences outcomes related to nociception following subsequent injury later in life (i.e., "neonatal nociceptive priming"). The underpinnings of this phenomenon are unclear, although previous work indicates that macrophages are trained by inflammation and injury. Our findings show that macrophages are both necessary and partially sufficient to drive neonatal nociceptive priming, possibly due to a long-lasting remodeling in chromatin structure. The p75 neurotrophic factor receptor is an important effector in regulating neonatal nociceptive priming through modulation of the inflammatory profile of rodent and human macrophages. This "pain memory" is long lasting in females and can be transferred to a naive host to alter sex-specific pain-related behaviors. This study reveals a mechanism by which acute, neonatal post-surgical pain drives a peripheral immune-related predisposition to persistent pain following a subsequent injury.

Macrophage epigenetic memories of early life injury drive neonatal nociceptive priming

The developing peripheral nervous and immune systems are functionally distinct from adults. These systems are vulnerable to early life injury, which influences outcomes related to nociception following subsequent injury later in life (neonatal nociceptive priming). The underpinnings of this phenomenon are largely unknown, although previous work indicates that macrophages are epigenetically trained by inflammation and injury. We found that macrophages are both necessary and partially sufficient to drive neonatal nociceptive priming possibly due to a long-lasting epigenetic remodeling. The p75 neurotrophic factor receptor (NTR) was an important effector in regulating neonatal nociceptive priming through modulation of the inflammatory profile of rodent and human macrophages. This pain memory was long lasting in females and could be transferred to a naive host to alter sex-specific pain-related behaviors. This study reveals a novel mechanism by which acute, neonatal post-surgical pain drives a peripheral immune-related predisposition to persistent pain following a subsequent injury.

Regular use of low-dose of opioids after gastrointestinal surgery may lead to postoperative gastrointestinal tract dysfunction in children: a Chinese national regional health center experience sharing

BACKGROUND

The need for pain management is increasing in pediatrics, but the side effects of overuse or abuse of analgesics can be harmful to children's health and even life-threatening in severe cases.

METHODS

Patients who underwent resection of Meckel's diverticulum at the Children's Hospital of Chongqing Medical University from July 1, 2019, to July 1, 2022, were included in this study. Opioids were administered through patient-controlled analgesia (PCA). Based on the preoperative choices made by the legal guardians, patients were stratified into two groups: PCA Group (PCAG) and Non-PCA Group (NPCAG). Data pertaining to the clinical characteristics and prognoses of these patients were subsequently collected and analyzed to assess the impact of opioid administration.

RESULTS

In the study, a total of 126 patients were enrolled, with 72 allocated to the Patient-Controlled Analgesia Group (PCAG) and 54 to the Non-Patient-Controlled Analgesia Group (NPCAG). When compared to the NPCAG, the PCAG exhibited a longer duration of postoperative fasting (median 72 vs. 62 h, p = 0.044) and increased utilization of laxatives (12[16.7%] vs. 2[3.7%], p = 0.022). However, the PCAG also experienced higher incidences of intestinal stasis and abnormal intestinal dilation (13[18.1%] vs. 3[5.6%], p = 0.037). No statistically significant differences were observed in pain assessments at the conclusion of the surgical procedure (0 vs. 1[1.9%], p = 0.429) or within the first 24 h postoperatively (16[22.2%] vs. 18[33.3%], p = 0.164). Additionally, NPCAG patients did not necessitate increased administration of rescue analgesics (2[2.8%] vs. 4[7.4%], p = 0.432).

CONCLUSIONS

The administration of opioids did not demonstrably ameliorate postoperative pain but was associated with a heightened incidence of postoperative gastrointestinal tract dysfunction. The retrospective nature of the current research should be considered and should be clarified further.

Prevalence of opioid and benzodiazepine use in adult patients with the exstrophy-epispadias complex

INTRODUCTION

Bladder exstrophy (BE), cloacal exstrophy (CE), and epispadias (E) are variants of the exstrophy-epispadias complex (EEC). These children require opioids and benzodiazepines to achieve pain management and immobilization for a lifetime of surgeries. It is hypothesized that these children would be sensitized to opiates and benzodiazepines as adults. The objective was to identify incidence of opiate and benzodiazepine use in adult EEC patients.

METHODS

A US Health network, TriNetX Diamond was queried from 2009 to 2022. Incidence of prescriptions for benzodiazepines and opioids were calculated for adults aged 18-60 years with a diagnosis of BE, CE, or E.

RESULTS

A total of 2627 patients were identified: 337 with CE, 1854 patients with BE, and 436 with E. Of these, 55.5% of CE, 56.4% of BE, and 41.1% of E had received any opioid prescription. Non-EEC controls had lower rates of opioids at 0.3%. E had a lower likelihood than BE or CE of receiving opioids (p < 0.0001, p < 0.0001). Benzodiazepines were prescribed in 30.3% of CE, 24.4% of BE, 18.3% of E, and 0.1% of controls. CE had a higher likelihood of benzodiazepines than both BE and E (p = 0.022, p < 0.001, respectively). E group had the lowest likelihood of benzodiazepine prescription (p = 0.007 when compared to BE) and all groups were significantly higher than controls (p < 0.0001 for all comparisons). For BE, females were more likely to be prescribed opioids (p = 0.039) and benzodiazepines (p = 0.027) than males. Sub-analyses revealed BE females had higher rates of surgical procedures (general, cardiac, gastrointestinal, and maternity) and chronic diagnoses (generalized anxiety disorder, major depressive disorder, chronic pain) compared to males with BE. Older age was associated with higher likelihood of opioid or benzodiazepine prescriptions in BE (p < 0.001), CE (p = 0.004), and E (p = 0.002).

DISCUSSION

Across the EEC, adult patients with the most severe anomalies of CE were more likely to have received opioids and benzodiazepines. Females with BE were prescribed more opioid and benzodiazepines than males with BE. Mirroring the US population, female sex and increasing age were associated with higher rates of prescriptions, chronic diagnoses, and surgical procedures. Limitations include the lack of granular data and ability to correlate results with childhood surgeries.

CONCLUSION

Adult EEC patients have higher rates of opioid and benzodiazepine prescriptions, with a high percentage of co-prescribing when compared to healthy controls. Across the spectrum, those with more severe anomalies, female sex, and increasing age were more likely to have received prescriptions.

Current Evidence for Biological Biomarkers and Mechanisms Underlying Acute to Chronic Pain Transition across the Pediatric Age Spectrum

Chronic pain is highly prevalent in the pediatric population. Many factors are involved in the transition from acute to chronic pain. Currently, there are conceptual models proposed, but they lack a mechanistically sound integrated theory considering the stages of child development. Objective biomarkers are critically needed for the diagnosis, risk stratification, and prognosis of the pathological stages of pain chronification. In this article, we summarize the current evidence on mechanisms and biomarkers of acute to chronic pain transitions in infants and children through the developmental lens. The goal is to identify gaps and outline future directions for basic and clinical research toward a developmentally informed theory of pain chronification in the pediatric population. At the outset, the importance of objective biomarkers for chronification of pain in children is outlined, followed by a summary of the current evidence on the mechanisms of acute to chronic pain transition in adults, in order to contrast with the developmental mechanisms of pain chronification in the pediatric population. Evidence is presented to show that chronic pain may have its origin from insults early in life, which prime the child for the development of chronic pain in later life. Furthermore, available genetic, epigenetic, psychophysical, electrophysiological, neuroimaging, neuroimmune, and sex mechanisms are described in infants and older children. In conclusion, future directions are discussed with a focus on research gaps, translational and clinical implications. Utilization of developmental mechanisms framework to inform clinical decision-making and strategies for prevention and management of acute to chronic pain transitions in children, is highlighted.

Early-Life Iron Deficiency Persistently Alters Nociception in Developing Mice

Clinical association studies have identified early-life iron deficiency (ID) as a risk factor for the development of chronic pain. While preclinical studies have shown that early-life ID persistently alters neuronal function in the central nervous system, a causal relationship between early-life ID and chronic pain has yet to be established. We sought to address this gap in knowledge by characterizing pain sensitivity in developing male and female C57Bl/6 mice that were exposed to dietary ID during early life. Dietary iron was reduced by ∼90% in dams between gestational day 14 and postnatal day (P)10, with dams fed an ingredient-matched, iron-sufficient diet serving as controls. While cutaneous mechanical and thermal withdrawal thresholds were not altered during the acute ID state at P10 and P21, ID mice were more sensitive to mechanical pressure at P21 independent of sex. During adulthood, when signs of ID had resolved, mechanical and thermal thresholds were similar between early-life ID and control groups, although male and female ID mice displayed increased thermal tolerance at an aversive (45 °C) temperature. Interestingly, while adult ID mice showed decreased formalin-induced nocifensive behaviors, they showed exacerbated mechanical hypersensitivity and increased paw guarding in response to hindpaw incision in both sexes. Collectively, these results suggest that early-life ID elicits persistent changes in nociceptive processing and appears capable of priming developing pain pathways. PERSPECTIVE: This study provides novel evidence that early-life ID evokes sex-independent effects on nociception in developing mice, including an exacerbation of postsurgical pain during adulthood. These findings represent a critical first step towards the long-term goal of improving health outcomes for pain patients with a prior history of ID.

Microglial phagocytosis mediates long-term restructuring of spinal GABAergic circuits following early life injury

Peripheral injury during the early postnatal period alters the somatosensory system, leading to behavioural hyperalgesia upon re-injury in adulthood. Spinal microglia have been implicated as the cellular mediators of this phenomenon, but the mechanism is unclear. We hypothesised that neonatal injury (1) alters microglial phagocytosis of synapses in the dorsal horn leading to long-term structural changes in neurons, and/or (2) trains microglia, leading to a stronger microglial response after re-injury in adulthood. Using hindpaw surgical incision as a model we showed that microglial density and phagocytosis increased in the dorsal horn region innervated by the hindpaw. Dorsal horn microglia increased engulfment of synapses following injury, with a preference for those expressing the vesicular GABA transporter VGAT and primary afferent A-fibre terminals in neonates. This led to a long-term reduction of VGAT density in the dorsal horn and reduced microglial phagocytosis of VGLUT2 terminals. We also saw an increase in apoptosis following neonatal injury, which was not limited to the dorsal horn suggesting that larger circuit wide changes are happening. In adults, hindpaw incision increased microglial engulfment of predominantly VGAT synapses but did not alter the engulfment of A-fibres. This engulfment was not affected by prior neonatal injury, suggesting that microglial phagocytosis was not trained. These results highlight microglial phagocytosis in the dorsal horn as an important physiological response towards peripheral injury with potential long-term consequences and reveals differences in microglial responses between neonates and adults.

Analgesic efficacy of ultrasound-guided bilateral transversus abdominis plane block in children: retrospective analysis of 97 cases

BACKGROUND

Transversus abdominis plane (TAP) block is a method for postoperative pain management. Studies on children are gradually increasing. The aim of this retrospective study was to evaluate effectiveness of TAP block on pain control, its side effects, and parental satisfaction levels in children.

METHODS

Study included patients operated between January 2019 and December 2020 in Gazi University Faculty of Medicine. Total of 97 patients (35 girls, 62 boys) between 5 and 18 years who had an ultrasound guided TAP block for lower abdominal or inguinal surgery were examined retrospectively. TAP block application time, hemodynamic variables, postoperative pain scores, postoperative analgesic requirement, sex, surgical history and satisfaction levels were evaluated.

RESULTS

: The average application time of TAP block was 9.48 ± 3.4 and the time between TAP block and surgical incision was 12.06 ± 6.1 min. Pain scores in postanesthesia care unit (PACU) and at the postoperative first hour decreased as the time between TAP block and surgical incision increased (p < 0.05). Girls have higher pain scores at PACU than boys (p < 0.05). Previous surgical history increased postoperative 1st hour pain scores (OR: 13.8; 95% CI 1.7-113.3; p = 0.01). There was a significant negative correlation between pain scores at PACU, postoperative 1st, 2nd, 4th, 6th, 12th and satisfaction levels (r = -0.45, r = -0.56, r = -0.60, r = -0.54, r = -0.52, r = -0,43, respectively, p < 0.05).

DISCUSSION

Ultrasound-guided TAP blocks can be performed safely in children in lower abdominal surgeries. However, the efficacy of TAP block on late term postoperative pain scores is limited. Time interval between the TAP block and the incision, sex, and pain memory, as well as other factors that may improve the quality of TAP block should be considered.

PRG-1 prevents neonatal stimuli-induced persistent hyperalgesia and memory dysfunction via NSF/Glu/GluR2 signaling

Neonatal repetitive noxious stimuli (RNS) has been shown to cause long-term harmful effects on nociceptive processing, learning, and memory which persist until adulthood. Plasticity-related gene 1 (PRG-1) regulates synaptic plasticity and functional reorganization in the brain during neuronal development. In this study, neonatal RNS rats were established by repetitive needle pricks to neonatal rats on all four feet to model repetitive pain exposure in infants. Neonatal RNS caused thermal hyperalgesia, mechanical allodynia, learning, and memory impairments which manifested in young rats and persisted until adulthood. Hippocampal PRG-1/N-ethylmaleimide sensitive fusion protein (NSF) interaction was determined to be responsible for the RNS-induced impairment via enhanced extracellular glutamate release and AMPAR GluR2 trafficking deficiency in a cell-autonomous manner. These pathways likely act synergistically to cause changes in dendritic spine density. Our findings suggest that PRG-1 prevents the RNS-induced hyperalgesia, learning, and memory impairment by regulating synaptic plasticity via NSF/Glu/GluR2 signaling.

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Neonatal RNS induced hyperalgesia, learning, and memory impairment until adulthood.

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PRG-1 attenuated RNS-induced impairments by dendritic spine regulation.

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PRG-1 prevents RNS-induced impairments via NSF/Glu/GluR2 signaling.

Evolving approaches in neonatal postoperative pain management

Neonates experience significant moderate and severe postoperative pain. Effective postoperative pain management in neonates is required to minimize acute and long-term effects of neonatal pain. Protecting the developing nervous system from persistent sensitization of pain pathways and developing primary hyperalgesia is essential. Opioids and acetaminophen are commonly analgesics used for pain control. Regional anesthesia provides adequate intraoperative and postoperative analgesia in neonates. It decreases exposure to opioids, reduces adverse drug effects, and facilitates early extubation. It suppresses the stress response and can prevent long-term behavioral responses to pain. The most common blocks performed in neonates are neuraxial blocks. Using ultrasound increased the number of peripheral nerve blocks performed in neonates. Recently, various peripheral nerve blocks (paravertebral, transverse abdominis plane, rectus sheath, quadratus lumborum, erector spinae plane blocks) were safely used. Many studies support analgesic efficacy but highlight neonates' unpredictability and variability of fascial blocks.

Genetic and epigenetic mechanisms influencing acute to chronic postsurgical pain transitions in pediatrics: Preclinical to clinical evidence

Background

Chronic postsurgical pain (CPSP) in children remains an important problem with no effective preventive or therapeutic strategies. Recently, genomic underpinnings explaining additional interindividual risk beyond psychological factors have been proposed.

Aims

We present a comprehensive review of current preclinical and clinical evidence for genetic and epigenetic mechanisms relevant to pediatric CPSP.

Methods

Narrative review.

Results

Animal models are relevant to translational research for unraveling genomic mechanisms. For example, Cacng2, p2rx7, and bdnf mutant mice show altered mechanical hypersensitivity to injury, and variants of the same genes have been associated with CPSP susceptibility in humans; similarly, differential DNA methylation (H1SP) and miRNAs (miR-96/7a) have shown translational implications. Animal studies also suggest that crosstalk between neurons and immune cells may be involved in nociceptive priming observed in neonates. In children, differential DNA methylation in regulatory genomic regions enriching GABAergic, dopaminergic, and immune pathways, as well as polygenic risk scores for enhanced prediction of CPSP, have been described. Genome-wide studies in pediatric CPSP are scarce, but pathways identified by adult gene association studies point to potential common mechanisms.

Conclusions

Bench-to-bedside genomics research in pediatric CPSP is currently limited. Reverse translational approaches, use of other -omics, and inclusion of pediatric/CPSP endophenotypes in large-scale biobanks may be potential solutions. Time of developmental vulnerability and longitudinal genomic changes after surgery warrant further investigation. Emergence of promising precision pain management strategies based on gene editing and epigenetic programing emphasize need for further research in pediatric CPSP-related genomics.

Assessing Neonatal Pain with NIPS and COMFORT-B: Evaluation of NICU’s Staff Competences

Background

Pain is considered “the 5th vital sign” that should be regularly assessed in the neonatal intensive care setting. Although over 40 pain assessment tools have been developed for neonates, their implementation in everyday practice is challenging. Epidemiological studies demonstrate that pain is still underassessed and undertreated in European NICUs.

Purpose

To evaluate the interrater and intrarater reliability of the NIPS and COMFORT-B scales among the tertiary NICU's staff members 4 years after their implementation in local pain guidelines with no prior dedicated training.

Methods

Physicians and nurses were invited to evaluate 5 video recordings of infants hospitalized in the intensive care settings, using the NIPS and COMFORT-B scales. The assessment took part twice at a 3-month interval. Interrater reliability was calculated for both scales using Kendall's W coefficient of concordance and Krippendorff's alpha coefficient. Cohen's kappa was used to assess intrarater reliability.

Results

17 physicians and 19 nurses took part in the study. Interrater agreement for the COMFORT-B scale was above 0.8 for Kendall's W coefficient (p < .01) and above 0.667 for Krippendorff's alpha coefficient. Kendall's W coefficient for the NIPS scores ranged between 0.7 and 0.8 (p < .01). Krippendorff's alpha was above 0.667. Intrarater agreement for both the COMFORT-B and NIPS scales was 0.693 and 0.724, respectively.

Conclusions

Overall, the agreement between our staff members was moderately good for both scales. This is not enough to avoid inadequate pain assessment. More training is needed to improve NICU's staff competences in using pain scales.

Is there an association between necrotizing enterocolitis in premature neonates and functional gastrointestinal disorders later in childhood?

BACKGROUND

Stressful events during infancy may predispose to the development of functional gastrointestinal disorders (FGIDs) in childhood.

AIMS

To evaluate the association of necrotizing enterocolitis (NEC) with childhood FGIDs.

METHODS

We conducted a study, comparing 29 children of eight to ten years with a history of NEC with 58 children with no history of NEC. Subjects were assessed for FGIDs, based on Rome-III criteria.

RESULTS

Among 29 subjects with NEC, 17 had surgical and 12 conservative NEC. Subjects with surgically, or conservatively managed NEC developed FGIDs at a significantly higher proportion, as compared to children with no history of NEC, later in childhood (41%, 33%, and 13% respectively, p = 0.033). Functional constipation was the most frequently identified disorder (35%, 33%, and 7% respectively). A significant association was detected between FGIDs and the history of perinatal stress (p = 0.049), NEC (p = 0.011), and the surgical management of NEC (p = 0.015).

CONCLUSIONS

Our study suggests that there is a potential association between NEC and FGIDs later in childhood with functional constipation being the most frequently identified disorder.

Developmental Mechanisms of CPSP: Clinical Observations and Translational Laboratory Evaluations

Understanding mechanisms that underly the transition from acute to chronic pain and identifying potential targets for preventing or minimizing this progression have specific relevance for chronic postsurgical pain (CPSP). Though it is clear that multiple psychosocial, family, and environmental factors may influence CPSP, this review will focus on parallels between clinical observations and translational laboratory studies investigating the acute and long-term effects of surgical injury on nociceptive pathways. This includes data related to alterations in sensitivity at different points along nociceptive pathways from the periphery to the brain; age- and sex-dependent mechanisms underlying the transition from acute to persistent pain; potential targets for preventive interventions; and the impact of prior surgical injury. Ongoing preclinical studies evaluating age- and sex-dependent mechanisms will also inform comparative efficacy and preclinical safety assessments of potential preventive pharmacological interventions aimed at reducing the risk of CPSP. In future clinical studies, more detailed and longitudinal peri-operative phenotyping with patient- and parent-reported chronic pain core outcomes, alongside more specialized evaluations of somatosensory function, modulation, and circuitry, may enhance understanding of individual variability in postsurgical pain trajectories and improve recognition and management of CPSP.

Neonatal procedural pain affects state, but not trait anxiety behavior in adult rats

The influence of neonatal experiences upon later-life affective behavior is increasingly recognized, but the reported effects on anxiety are often contradictory. The observed effect may depend upon the type of anxiety (state or trait) affected. The current study aims to investigate whether neonatal repetitive needle pricking alters anxiety behavior in adulthood, by assessing both state and trait anxiety in rats. Sprague-Dawley rat pups received four unilateral needle pricks per day, while controls received four tactile stimuli or were left completely undisturbed during the first postnatal week. Mechanical sensitivity was assessed in the neonatal phase and throughout the development. State anxiety was assessed in the open field test and trait anxiety in the elevated zero maze. The results show that repetitive needle pricking leads to acute mechanical hypersensitivity, but does not affect baseline mechanical sensitivity throughout development. In adulthood, animals previously exposed to neonatal procedural pain (including repetitive handling and removal from litter) showed lower state anxiety but did not differ in trait anxiety, as compared with the undisturbed controls. These findings indicate that early-life procedural pain decreases state but not trait anxiety behavior in later life in a rodent model of repetitive needle pricking.

Phenotyping peripheral neuropathic pain in male and female adolescents: pain descriptors, somatosensory profiles, conditioned pain modulation, and child-parent reported disability

ABSTRACT

Neuropathic pain (NeuP) can be difficult to diagnose and manage in children. Data regarding prevalence and sex-dependent differences are limited, and more detailed phenotyping is needed. This observational cohort study recruited adolescents (10-17 years) with NeuP or complex regional pain syndrome (CRPS). After pain history and NeuP questionnaires, quantitative sensory testing was performed. Individual z-score plots were calculated with body-region control measures and matched to mechanism-related sensory profiles (sensory loss, thermal hyperalgesia, and mechanical hyperalgesia). Conditioned pain modulation was assessed with pressure pain threshold and a contralateral cold conditioning stimulus, and meaningful conditioned pain modulation defined as twice the standard error of measurement. Patients and parents completed validated questionnaires for child quality of life (QoL), pain catastrophizing, and self-reported anxiety/depression. Males (n = 23) and females (n = 43) with NeuP (n = 52) or CRPS (n = 14) reported moderate-severe pain with neuropathic sensory descriptors. Mixed patterns of sensory gain/loss at pain sites were not sex-dependent. Thermal hyperalgesia was common in both NeuP and CRPS, whereas sensory loss occurred only with NeuP and in a smaller proportion than adult cohorts. Conditioned pain modulation was inhibitory in 54%, facilitatory in 14%, and nonresponders had variable cold conditioning sensitivity. Males and females reported marked impairment of QoL, increased emotional distress, and pain catastrophising. Child-parent QoL scores correlated, but catastrophizing scores were discordant when parents or adolescents reported higher anxiety/depression. NeuP in adolescents is associated with significant pain, physical impairment, and psychosocial impairment. Quantifying alterations in somatosensory profiles, descending modulation, child and parent psychological function will inform individualized therapy and stratification for future clinical trials.

A Painful Beginning: Early Life Surgery Produces Long-Term Behavioral Disruption in the Rat

Early life surgery produces peripheral nociceptive activation, inflammation, and stress. Early life nociceptive input and inflammation have been shown to produce long-term processing changes that are not restricted to the dermatome of injury. Additionally stress has shown long-term effects on anxiety, depression, learning, and maladaptive behaviors including substance abuse disorder and we hypothesized that early life surgery would have long-term effects on theses complex behaviors in later life. In this study surgery in the rat hindpaw was performed to determine if there are long-term effects on anxiety, depression, audiovisual attention, and opioid reward behaviors. Male animals received paw incision surgery and anesthesia or anesthesia alone (sham) at postnatal day 6. At 10 weeks after surgery, open field center zone entries were decreased, a measure of anxiety (n = 20) (P = 0.03) (effect size, Cohen's d = 0.80). No difference was found in the tail suspension test as a measure of depression. At 16-20 weeks, attentional performance in an operant task was similar between groups at baseline and decreased with audiovisual distraction in both groups (P < 0.001) (effect size, η² = 0.25), but distraction revealed a persistent impairment in performance in the surgery group (n = 8) (P = 0.04) (effect size, η² = 0.13). Opioid reward was measured using heroin self-administration at 16-24 weeks. Heroin intake increased over time in both groups during 24-h free access (P < 0.001), but was greater in the surgery group (P = 0.045), with a significant interaction between time and treatment (P < 0.001) (effect size, Cohen f ² = 0.36). These results demonstrate long-term disruptions in complex behaviors from surgical incision under anesthesia. Future studies to explore sex differences in early life surgery and the attendant peripheral neuronal input, stress, and inflammation will be valuable to understand emerging learning deficits, anxiety, attentional dysfunction, and opioid reward and their mechanisms. This will be valuable to develop optimal approaches to mitigate the long-term effects of surgery in early life.

Vorteile, Sicherheit und Nebenwirkungen der Tumeszenz‐Lokalanästhesie bei dermatologischen Operationen an Säuglingen

Die Tumeszenz-Lokalanästhesie (TLA) spielt bei dermatochirurgischen Eingriffen eine wichtige Rolle. Die TLA bietet etliche Vorteile, wie lang anhaltende Betäubung, reduzierte Blutung während der Operation und Vermeidung möglicher Komplikationen einer Vollnarkose. Einfache Durchführung, günstiges Risikoprofil und breites Indikationsspektrum sind weitere Gründe dafür, dass TLA zunehmend auch bei Säuglingen eingesetzt wird. Es gibt nicht nur viele Indikationen für chirurgische Exzisionen im Säuglingsalter, wie angeborene Naevi, sondern es hat auch erhebliche Vorteile, wenn diese Exzisionen in einem frühen Alter durchgeführt werden. Dazu zählen die geringere Größe der Läsionen sowie die unproblematische Wundheilung und Geweberegeneration im Säuglingsalter. Dennoch müssen hinsichtlich der Anwendung der TLA bei Säuglingen einige Aspekte berücksichtigt werden, darunter die Dosierung, eine veränderte Plasmaproteinbindung und die Notwendigkeit einer adäquaten und lang anhaltenden Schmerzkontrolle.

The burden of early life stress on the nociceptive system development and pain responses

For a long time, the capacity of the newborn infant to feel pain was denied. Today it is clear that the nociceptive system, even if still immature, is functional enough in the newborn infant to elicit pain responses. Unfortunately, pain is often present in the neonatal period, in particular in the case of premature infants which are subjected to a high number of painful procedures during care. These are accompanied by a variety of environmental stressors, which could impact the maturation of the nociceptive system. Therefore, the question of the long-term consequences of early life stress is a critical question. Early stressful experience, both painful and non-painful, can imprint the nociceptive system and induce long-term alteration in brain function and nociceptive behavior, often leading to an increase sensitivity and higher susceptibility to chronic pain. Different animal models have been developed to understand the mechanisms underlying the long-term effects of different early life stressful procedures, including pain and maternal separation. This review will focus on the clinical and preclinical data about early life stress and its consequence on the nociceptive system.

Benefits, safety and side effects of tumescent local anesthesia in dermatologic surgery in infants

Tumescent local anesthesia (TLA) plays an important role in dermatosurgical procedures. TLA has several benefits such as long-lasting anesthesia, reduced bleeding during surgery and the avoidance of general anesthesia-associated complications. Convenience and a favorable risk profile along with a broad spectrum of indications are further reasons why TLA is increasingly applied in infants as well. There are not only a variety of indications for surgical excisions in infancy, such as congenital nevi, but also substantial benefits when performing these excisions at an early age. These include the smaller size of the lesions as well as the unproblematic wound healing and tissue regeneration in infancy. Nevertheless, several aspects need to be considered when applying TLA in infants including dosing, altered plasma protein binding and the need for adequate and long-lasting pain control.

Early Life Health in Women with Provoked Vestibulodynia and/or Vaginismus

Background: The lifetime prevalence of prolonged vulvar pain ranges from 3% to 28% among premenopausal women. Provoked vestibulodynia (PVD), often accompanied with various degrees of vaginismus, is the predominant cause. We explored the association between birth-related events and the risk of developing PVD/vaginismus during adulthood. Materials and Methods: We identified all women born in Sweden between 1973 and 2001 and categorized those with and without a diagnosis of PVD/vaginismus between 2001 and 2016 (during ages 15-43 years). Nationwide registry data were used to estimate the association between health during infancy (preterm birth, low birth weight, small for gestational age [SGA], Appearance, Pulse, Grimace, Activity and Respiration [APGAR] scores <7, and pain exposure during infancy) and the onset of PVD/vaginismus later in life using an event probability model. Results: Of the 1,359,315 women born in Sweden during 1973-2001, 9,247 were diagnosed with PVD (n = 6,648), vaginismus (n = 3,567), or both (n = 969). Preterm delivery <37 weeks (adjusted odds ratios [aOR]: 1.15, 95% confidence interval [CI]: 1.05-1.26), low birth weight <2,500 g (aOR: 1.24, 95% CI: 1.12-1.36), extremely low birth weight <1,500 g (aOR 1.41, 95% CI: 1.10-1.82), and SGA (aOR 1.20, 95% CI: 1.08-1.34) were factors associated with developing PVD/vaginismus. APGAR scores <7 or pain exposure during birth or infancy was not associated with PVD/vaginismus. Advanced maternal age, higher educational attainment, and being born in Sweden were associated with having a female offspring diagnosed with PVD/vaginismus. Conclusions: In a population of Swedish women 15-43 years of age, adverse health at birth was associated with developing PVD/vaginismus later on in life.

Effects of Pain-Reporting Education Program on Children's Pain Reports-Results From a Randomized Controlled Post-operative Pediatric Pain Trial

Objective: Accurate assessment of patients' pain is an essential part of adequate analgesic treatment. Although reporting pain is a complex task, limited-to-no instructions are provided to pediatric patients regarding this process. Our goal in this randomized parallel-group clinical trial (Clinicaltrial.gov study protocol number NCT04306679) was to evaluate if a training program designed to improve children's ability to understand and use pain scales in a post-surgical setting would affect their pain scores. Methods: Eligible children (aged 8-17), hospitalized for elective surgery and their parents were randomized into two groups. Pre-surgery the intervention group underwent a multi-media program aimed to teach and train how to report pain. The control group received standard pre-surgical instructions. Post-surgery, the children reported their pain on 4 pain scales. The primary outcome was the concordance between children's pain intensity scores reported on four pain scales, both in terms of within-child standard deviation and absolute difference. Results: Ninety-six children met inclusion criteria and completed the study. The trained subjects' pain reports had significantly (p = 0.002) lower within-subject standard deviation (0.41 ± 0.31) than the control group (0.67 ± 0.46). In line, regarding absolute difference, the concordance of children's pain reports was twice better in the trained group (mean difference of 0.43 ± 0.40) than in the control group (0.88 ± 0.70) (p < 0.001). Discussion: Our results suggests that children's ability to report pain is a skill that can be improved. Future studies should test the potential clinical impacts of educational interventions aimed to improve pain assessment in children and adults.

The effect of early burn injury on sensitivity to future painful stimuli in dairy heifers

Animals that experience painful procedures as neonates are more sensitive to pain later in life. We evaluated whether disbudding with a heated iron at 3 (n = 12), 35 (n = 9), or 56 (n = 20) d of age affected heifers’ pain responses to vaccine injections at 11 mo of age. Heifers responded to the injection procedure with struggling and changes in eye temperature and heart rate variability compared to a sham procedure the day before, and still had a heightened response 6 d later, regardless of disbudding age. However, some heart rate variability indices suggested increased sympathetic dominance in heifers disbudded at 35 d, compared to the other 2 age groups, independent of the injection procedure. We also found that heifers disbudded at 3 or 35 d had a higher mean heart rate after the injection procedure compared to those disbudded at 56 d. We conclude that: (1) heifers find injections aversive; and (2) there is some evidence that disbudding age influences autonomic nervous system activity later in life.

Early Neonatal Pain-A Review of Clinical and Experimental Implications on Painful Conditions Later in Life

Modern health care has brought our society innumerable benefits but has also introduced the experience of pain very early in life. For example, it is now routine care for newborns to receive various injections or have blood drawn within 24 h of life. For infants who are sick or premature, the pain experiences inherent in the required medical care are frequent and often severe, with neonates requiring intensive care admission encountering approximately fourteen painful procedures daily in the hospital. Given that much of the world has seen a steady increase in preterm births for the last several decades, an ever-growing number of babies experience multiple painful events before even leaving the hospital. These noxious events occur during a critical period of neurodevelopment when the nervous system is very vulnerable due to immaturity and neuroplasticity. Here, we provide a narrative review of the literature pertaining to the idea that early life pain has significant long-term effects on neurosensory, cognition, behavior, pain processing, and health outcomes that persist into childhood and even adulthood. We refer to clinical and pre-clinical studies investigating how early life pain impacts acute pain later in life, focusing on animal model correlates that have been used to better understand this relationship. Current knowledge around the proposed underlying mechanisms responsible for the long-lasting consequences of neonatal pain, its neurobiological and behavioral effects, and its influence on later pain states are discussed. We conclude by highlighting that another important consequence of early life pain may be the impact it has on later chronic pain states-an area of research that has received little attention.

Repetitive noxious stimuli during early development affect acute and long-term mechanical sensitivity in rats

BACKGROUND

Prematurely born infants are frequently exposed to painful procedures in the neonatal intensive care unit, causing changes to the development of the nervous system lasting into adulthood. The current study aims to study acute and long-term consequences of neonatal repetitive noxious stimulation.

METHODS

Rat pups received either 4 or 10 unilateral needle pricks per day, while control littermates received 4 or 10 tactile stimuli in the first postnatal week. Behavioural sensitivity was assessed in the neonatal phase, in adulthood, and after re-injury of the same dermatome in adulthood.

RESULTS

An increase in the number of repetitive painful stimuli, from 4 to 10 needle pricks per day, resulted in increased mechanical hypersensitivity during the neonatal period. In adulthood, repetitive painful stimuli resulted in hyposensitivity to mechanical stimuli, while thermal sensitivity was unaffected. After re-injury of the same dermatome in adulthood, the number of repetitive noxious stimuli did not affect mechanical hypersensitivity. Both needle prick groups showed an increased duration of postoperative hypersensitivity compared to control.

CONCLUSION

This study shows that repetitive noxious stimulation during the early postnatal period affects acute and long-term mechanical sensitivity. Therefore, the amount of nociceptive stimuli should be minimized or adequately treated in a clinical setting.

Postoperative pain management for circumcision; Comparison of frequently used methods

Objective

To determine the ideal method for postoperative pain management after circumcision by comparing the most frequently used different methods like; dorsal penile block, caudal epidural block, subcutaneous ring block, intravenous paracetamol and intravenous tramadol HCl.

Methods

Between May 1^st 2015 to May 1^st 2016, 500 children between 2-10 year old were circumcised at the department of pediatric surgery of Istanbul Medipol University Health Care Practice & Research Center Sefakoy Hospital. Five groups were formed according to postoperative analgesia methods which were planned to be compared; Group-I. penile block, Group-II. Caudal epidural block, Group-III. subcutaneous ring block, Group-IV as intravenous paracetamol and Group-V as intravenous tramadol HCl. In order to evaluate the postoperative pain levels of children, Children's Hospital Eastern Ontario Pain Scale (CHEOPS) was filled at 30, 60, 120, 180 minutes after circumcision by a researcher who does not know which method was applied.

Results

No significant difference is found between the groups (p>0.05). In the statistical analysis, no significant difference was found in the effect of analgesia methods on CHEOPS scores between 30, 60, 120 and 180 minutes (p>0.05). In parallel with this result, no significant difference was found in the effect of heart beat rates and respiration rate averages between 30, 60, 120 and 180 minutes (p>0.05).

Conclusion

It has been shown that none of the five method has any superiority in reducing pain after circumcision and that all five methods can be used. However, we think that side effects of regional anesthesia and systemic analgesic applications should not be ignored.

Current state of science in machine learning methods for automatic infant pain evaluation using facial expression information: study protocol of a systematic review and meta-analysis

INTRODUCTION

Infants can experience pain similar to adults, and improperly controlled pain stimuli could have a long-term adverse impact on their cognitive and neurological function development. The biggest challenge of achieving good infant pain control is obtaining objective pain assessment when direct communication is lacking. For years, computer scientists have developed many different facial expression-centred machine learning (ML) methods for automatic infant pain assessment. Many of these ML algorithms showed rather satisfactory performance and have demonstrated good potential to be further enhanced for implementation in real-world clinical settings. To date, there is no prior research that has systematically summarised and compared the performance of these ML algorithms. Our proposed meta-analysis will provide the first comprehensive evidence on this topic to guide further ML algorithm development and clinical implementation.

METHODS AND ANALYSIS

We will search four major public electronic medical and computer science databases including Web of Science, PubMed, Embase and IEEE Xplore Digital Library from January 2008 to present. All the articles will be imported into the Covidence platform for study eligibility screening and inclusion. Study-level extracted data will be stored in the Systematic Review Data Repository online platform. The primary outcome will be the prediction accuracy of the ML model. The secondary outcomes will be model utility measures including generalisability, interpretability and computational efficiency. All extracted outcome data will be imported into RevMan V.5.2.1 software and R V3.3.2 for analysis. Risk of bias will be summarised using the latest Prediction Model Study Risk of Bias Assessment Tool.

ETHICS AND DISSEMINATION

This systematic review and meta-analysis will only use study-level data from public databases, thus formal ethical approval is not required. The results will be disseminated in the form of an official publication in a peer-reviewed journal and/or presentation at relevant conferences.

PROSPERO REGISTRATION NUMBER

CRD42019118784.

A Review of Regional Anesthesia in Infants

Regional anesthesia provides effective anesthesia and pain relief in infants with age-specific data attesting to safety and efficacy. Regional anesthesia decreases exposure to opioids and general anesthetic agents and associated adverse drug effects, suppresses the stress response, and provides better hemodynamic stability compared to general anesthesia. Regional anesthesia can prevent long-term behavioral responses to pain. As a result, the overall number and variety of nerve blocks being used in infants is increasing. While neuraxial blocks are the most common blocks performed in infants, the introduction of ultrasound imaging and a better safety profile has advanced the use of peripheral nerve blocks. Infant-specific pharmacokinetic and pharmacodynamic data of local anesthetic medications are reviewed including risk factors for the accumulation of high serum levels of unbound, pharmacologically active drug. Bupivacaine accumulates with continuous infusion and 2-chloroprocaine can be used as an alternative. Local anesthetic systemic toxicity has the highest incidence in infants less than 6 months of age and is associated with bolus dosing and penile nerve blocks. Local anesthetic toxicity is treated by securing the airway, suppression of seizure activity and implementation of cardiopulmonary resuscitation. Administration of intralipid (intravenous lipid emulsion) is initiated at the first sign of toxicity. A high level of expertise in regional anesthesia is needed when treating infants due to their unique development.

Epidural and Spinal Anesthesia for Newborn Surgery

Neuraxial (spinal and epidural) anesthesia has become commonplace in the care of neonates undergoing surgical procedures. These techniques afford many benefits, and, when properly performed, are extremely safe. This article reviews the benefits, risks, and applications of neuraxial anesthesia in neonates.

Long-term effects of neonatal pain

Pain experienced during neonatal intensive care management can influence neurodevelopmental outcome and the somatosensory and/or emotional components of pain response in later life. Alterations in biological factors (e.g. peripheral and central somatosensory function and modulation, brain structure and connectivity) and psychosocial factors (e.g. gender, coping style, mood, parental response) that influence pain have been identified in children and young adults born very preterm or extremely preterm. Earlier gestational age at birth and cumulative pain exposure from tissue-breaking procedures and/or neonatal surgery influence the degree of change. In neonatal rodents, repeated needle insertion or hindpaw incision identify developmentally-regulated and activity-dependent long term alterations in nociceptive processing, and the efficacy of novel or current analgesic interventions can be compared. As prior neonatal experience and sex may influence current pain experience or the risk of persistent pain, these factors should be considered within the biopsychosocial assessment and formulation of pain in later life.

Pre- and perinatal stress and irritable bowel syndrome in young adults - A nationwide register-based cohort study

BACKGROUND

The etiology of irritable bowel syndrome (IBS) is poorly understood. Animal and human data suggest that early life stress may induce long-term changes in the nociceptive circuitry, but conclusive studies are lacking.

METHODS

We identified all Swedish children born between 1973 and 1992 in the Swedish Medical Birth Register. We had access to all diagnostic codes for specialized (nonprimary care) outpatient visits 2001-2009 (the National Patient Register) and identified individuals who were diagnosed with IBS (ICD-10 code: K58) after 18 years of age. We compared incidence of IBS in individuals with and without pre- and perinatal stress using multivariable logistic regression.

KEY RESULTS

2 056 430 children were included in the study. After turning 18 years, 14 382 of them were diagnosed with IBS in specialized outpatient care. Neither high, nor low birth weight was a risk factor for IBS in young adults. Preterm birth was associated with lower occurrence of IBS (adjusted OR 0.82 [0.75-0.90]) and vaginal instrumental delivery and Cesarean delivery were associated with slightly increased odds of IBS (adjusted OR 1.14 [1.06-1.24] and 1.09 [1.03-1.16] respectively). Neonatal distress and respiratory distress were not associated with future IBS. Female gender was by far the strongest risk factor for IBS in young adults (adjusted OR 3.48 [3.34-3.63]).

CONCLUSIONS & INFERENCES

In this large population-based study, we found that mode of delivery was associated with an increased risk for IBS in young adulthood, while other proxies for pre- and perinatal stress were not. Female gender remains the most important risk factor for IBS.

Dorsal penile nerve block versus eutectic mixture of local anesthetics cream for pain relief in infants during circumcision: A meta-analysis

OBJECTIVE

To compare dorsal penile nerve block (DPNB) and eutectic mixture of local anesthetics (EMLA) cream for pain relief in infants during circumcision.

METHODS

We systematically searched Medline via PubMed, Embase, CNKI and the Cochrane Library Center Register to identify randomized controlled trials up to March 2018. Effect estimates were performed in random effect models. Mean neonate infant pain scale (NIPS) scores, incidence of hematoma, edema and erythema, mean heart rate were conducted to assessed the effect of analgesia. We found that the EMLA had significantly higher pain scores compared to DPNB (SMD = 3.72, 95% CI 1.27-6.17, P = 0.003). In DPNB group, the incidence of hematoma was significantly higher than EMLA group, OR = 0.03, 95% CI 0.00-0.24, P = 0.001. The analysis did not show any significant differences in mean heart rate and the risk of edema and erythema between EMLA and DPNB group (SMD = 21.71, 95% CI = -0.88-44.30, P = 0.06 & OR = 0.40, 95% CI 0.15-1.07, P = 0.07 & OR = 7.33, 95% CI 0.84-64.07, P = 0.07).

CONCLUSION

Based on the pooled results from the included studies, we found that DPNB was significantly more effective in pain relief as indicated by mean NIPS score than EMLA in infants during circumcision. However, use of DPNB significantly increased the risk of hematoma.

Somatosensory function and pain in extremely preterm young adults from the UK EPICure cohort: sex-dependent differences and impact of neonatal surgery

BACKGROUND

Surgery or multiple procedural interventions in extremely preterm neonates influence neurodevelopmental outcome and may be associated with long-term changes in somatosensory function or pain response.

METHODS

This observational study recruited extremely preterm (EP, <26 weeks' gestation; n=102, 60% female) and term-born controls (TC; n=48) aged 18-20 yr from the UK EPICure cohort. Thirty EP but no TC participants had neonatal surgery. Evaluation included: quantitative sensory testing (thenar eminence, chest wall); clinical pain history; questionnaires (intelligence quotient; pain catastrophising; anxiety); and structural brain imaging.

RESULTS

Reduced thermal threshold sensitivity in EP vs TC participants persisted at age 18-20 yr. Sex-dependent effects varied with stimulus intensity and were enhanced by neonatal surgery, with reduced threshold sensitivity in EP surgery males but increased sensitivity to prolonged noxious cold in EP surgery females (P<0.01). Sex-dependent differences in thermal sensitivity correlated with smaller amygdala volume (P<0.05) but not current intelligence quotient. While generalised decreased sensitivity encompassed mechanical and thermal modalities in EP surgery males, a mixed pattern of sensory loss and sensory gain persisted adjacent to neonatal scars in males and females. More EP participants reported moderate-severe recurrent pain (22/101 vs 4/48; χ2=0.04) and increased pain intensity correlated with higher anxiety and pain catastrophising.

CONCLUSIONS

After preterm birth and neonatal surgery, different patterns of generalised and local scar-related alterations in somatosensory function persist into early adulthood. Sex-dependent changes in generalised sensitivity may reflect central modulation by affective circuits. Early life experience and sex/gender should be considered when evaluating somatosensory function, pain experience, or future chronic pain risk.

Factors Associated With Infant Pain Severity Undergoing Immunization Injections

PURPOSE

Factors influencing infants' behavioral and vocal (cry) response to painful stimuli are explored to improve pain management plans for infants undergoing immunizations.

DESIGN AND METHODS

An observational study design was used. Pain responses of 60 to 75 days-old infants (44% male vs 56% female) undergoing two-month immunization injections were videotaped and coded using the Modified Behavioral Pain Scale (MBPS), and duration of total crying time during injection was recorded. The influences of five factors (gender, caregiver attendance, previous experience of nociception (circumcision), mode of delivery), and weight (birth and current) were examined at baseline, during and post-immunization.

RESULTS

Higher birth weight was the most significant factor that reduced pain responses during (p = 0.001) and post-immunization (p = 0.03). A higher birth weight reduced full lung crying (p = 0.04), which reflects crying during injection as compared to total crying time. Vaginal delivery had a significant effect on behavioral pain responses of infants only post-immunization (p = 0.006). Parent's presence in the immunization room significantly reduced total crying time (p = 0.03). Uncircumcised male infants had a significant reduction in behavioral pain responses during immunization (p = 0.01) compared to circumcised infants.

CONCLUSIONS

The literature well supports the acknowledgement of early pain experience and its psychological consequences. Knowing and controlling for each of mentioned factors early in life during every painful procedure could improve coping mechanisms of infants for any painful procedures later in life.

PRACTICE IMPLICATIONS

Control of certain factors during early life experiences can modify pain of immunization.

Spinal SHP2 Contributes to Exaggerated Incisional Pain in Adult Rats Subjected to Neonatal and Adult Incisions via PI3K

Neonatal injury-induced exaggeration of pain hypersensitivity after adult trauma is a significant clinical challenge. However, the underlying mechanisms remain poorly understood. Growing evidence shows that spinal Src homology-2 domain-containing protein tyrosine phosphatase-2 (SHP2) contributes to chronic pain in adult rodents. Here we demonstrated that the phosphorylation and expression of SHP2 in synaptosomal fraction of the spinal dorsal horn are elevated in adult rats subjected to neonatal and adult incisions (nIN-IN), and the upregulation of SHP2 is highly correlated with pain hypersensitivity. Intrathecal blockade of SHP2 phosphorylation using a SHP2 protein tyrosine phosphatase inhibitor NSC-87877, or knockdown of SHP2 by intrathecal delivery of small interfering RNA (siRNA), ameliorates mechanical allodynia and heat hyperalgesia in nIN-IN rats. Moreover, the expression of phosphatidylinositol 3-kinase (PI3K) in the spinal dorsal horn is significantly increased in nIN-IN rats. Intrathecal application of PI3K inhibitor, LY294002 or wortmannin, alleviates pain hypersensitivity in nIN-IN rats. Additionally, intrathecal administration of NSC-87877 or SHP2 siRNA attenuates the upregulation of PI3K. Finally, no alternation of SHP2 phosphorylation in the dorsal root ganglion and dorsal root of nIN-IN rats as well as PI3K expression in the dorsal root of nIN-IN rats intrathecally treated with NSC-87877 or SHP2 siRNA is observed. These results suggest that the phosphorylation and expression of SHP2 in the spinal dorsal horn play vital roles in neonatal incision-induced exaggeration of adult incisional pain via PI3K. Thus, SHP2 and PI3K may serve as potential therapeutic targets for exaggerated incisional pain induced by neonatal and adult injuries.

Randomized Clinical Trial of Lidocaine Analgesia for Transurethral Bladder Catheterization Delivered via Blunt Tipped Applicator in Young Children

OBJECTIVE

Transurethral bladder catheterization (TUBC) is a painful, frequently performed procedure for collecting sterile urine. We sought to determine if administration of intraurethral lidocaine before TUBC using a blunt tipped syringe decreases procedural pain in young children in the pediatric emergency department.

METHODS

Randomized clinical trial of children 0 to 36 months old requiring TUBC for collection of urine in a pediatric emergency department was performed. Patients received intraurethral 2% lidocaine jelly or usual care (no analgesia). Randomization was stratified by sex. Intraurethral lidocaine jelly was administered via Uro-Jet, 5 minutes before TUBC. Baseline child state, lidocaine application, TUBC, and child state 1 minute post-TUBC were videotaped. Neither providers nor parents were blinded to study arm. Videos were scored by a trained, independent, blinded reviewer using the Faces, Legs, Arms, Cry, and Consolability (FLACC) and Modified Behavioral Pain Score scales. Pain scores were compared using the Wilcoxon rank sum test. Our primary outcome was difference in FLACC scores between groups.

RESULTS

Eighty children were enrolled in the study, and 73 had analyzable data. No differences were detected in pain by mean FLACC score between intervention (8; 95% confidence interval, 7-9) and control (9; 95% confidence interval, 8-10) groups. There were no differences between groups in mean FLACC score when stratified by age or sex or in mean Modified Behavioral Pain Score.

CONCLUSIONS

Intraurethral lidocaine for TUBC for urine collection using a blunt tipped applicator did not improve procedural pain scores. Pain scores were high across groups. Further study should be performed to improve analgesia for this highly painful procedure.

Opioid analgesia and the somatosensory memory of neonatal surgical injury in the adult rat

Background

Nociceptive input during early development can produce somatosensory memory that influences future pain response. Hind-paw incision during the 1st postnatal week in the rat enhances re-incision hyperalgesia in adulthood. We now evaluate its modulation by neonatal analgesia.

Methods

Neonatal rats [Postnatal Day 3 (P3)] received saline, intrathecal morphine 0.1 mg kg−1 (IT), subcutaneous morphine 1 mg kg⁻¹ (SC), or sciatic levobupivacaine block (LA) before and after plantar hind-paw incision (three×2 hourly injections). Six weeks later, behavioural thresholds and electromyography (EMG) measures of re-incision hyperalgesia were compared with an age-matched adult-only incision (IN) group. Morphine effects on spontaneous (conditioned place preference) and evoked (EMG sensitivity) pain after adult incision were compared with prior neonatal incision and saline or morphine groups. The acute neonatal effects of incision and analgesia on behavioural hyperalgesia at P3 were also evaluated.

Results

Adult re-incision hyperalgesia was not prevented by neonatal peri-incision morphine (saline, IT, and SC groups > IN; P<0.05–0.01). Neonatal sciatic block, but not morphine, prevented the enhanced re-incision reflex sensitivity in adulthood (LA < saline and morphine groups, P<0.01; LA vs IN, not significant). Morphine efficacy in adulthood was altered after morphine alone in the neonatal period, but not when administered with neonatal incision. Morphine prevented the acute incision-induced hyperalgesia in neonatal rats, but only sciatic block had a preventive analgesic effect at 24 h.

Conclusions

Long-term effects after neonatal injury highlight the need for preventive strategies. Despite effective analgesia at the time of neonatal incision, morphine as a sole analgesic did not alter the somatosensory memory of early-life surgical injury.

Fear of Injections and Needle Phobia Among Children and Adolescents: An Overview of Psychological, Behavioral, and Contextual Factors

The purpose of this clinical update is to provide an overview of the fear of needles and needle phobia in children and adolescents including characteristics and diagnosis, prevalence and epidemiology, etiological factors, and treatment options. Needle-related fear and needle phobia present as significant needle-related distress and avoidance behavior. The etiology is biopsychosocial. These challenging conditions are more common in children and adolescents than in adults. The nurse-patient relationship enables the provision of suitable preparation before injection procedures. Nurses can use exposure-based interventions and incorporate coping strategies and teaching of parents and children. Nurses play a pivotal role in noticing the need for further treatment. Procedural needle-related distress is a complex phenomenon representing a continuum ranging from needle fear to more severe needle phobia. For patients with needle fear management and training methods used by nurses can possibly prevent a progression of the condition into needle phobia. In cases of needle phobia, a correct diagnosis made by a psychiatrist is necessary and enables referral to a psychotherapist with experience in treating children and adolescents with needle phobia.

Microglia in health and pain: impact of noxious early life events

NEW FINDINGS

What is the topic of this review? This review discusses the origins and development of microglia, and how stress, pain or inflammation in early life disturbs microglial function during critical developmental periods, leading to altered pain sensitivity and/or increased risk of chronic pain in later life. What advances does it highlight? We highlight recent advances in understanding how disrupted microglial function impacts the developing nervous system and the consequences for pain processing and susceptibility for development of chronic pain in later life. The discovery of microglia is accredited to Pío del Río-Hortega, who recognized this 'third element' of CNS cells as being morphologically distinct from neurons and astrocytes. For decades after this finding, microglia were altogether ignored or relegated as simply being support cells. Emerging from virtual obscurity, microglia have now gained notoriety as immune cells that assume a leading role in the development, maintenance and protection of a healthy CNS. Pioneering studies have recently shed light on the origins of microglia, their role in the developing nervous system and the complex roles they play beyond the immune response. These studies reveal that altered microglial function can have a profoundly negative impact on the developing brain and may be a determinant in a range of neurodevelopmental disorders and neurodegenerative diseases. The realization that aberrant microglial function also critically underlies chronic pain, a debilitating disorder that afflicts over 1.5 billion people worldwide, was a major conceptual leap forward in the pain field. Adding to this advance is emerging evidence that early life noxious experiences can have a long-lasting impact on central pain processing and adult pain sensitivity. With microglia now coming of age, in this review we examine the association between adverse early life events, such as stress, injury or inflammation, and the influence of sex differences, on the role of microglia in pain physiology in adulthood.

Peripheral Mechanisms of Ischemic Myalgia

Musculoskeletal pain due to ischemia is present in a variety of clinical conditions including peripheral vascular disease (PVD), sickle cell disease (SCD), complex regional pain syndrome (CRPS), and even fibromyalgia (FM). The clinical features associated with deep tissue ischemia are unique because although the subjective description of pain is common to other forms of myalgia, patients with ischemic muscle pain often respond poorly to conventional analgesic therapies. Moreover, these patients also display increased cardiovascular responses to muscle contraction, which often leads to exercise intolerance or exacerbation of underlying cardiovascular conditions. This suggests that the mechanisms of myalgia development and the role of altered cardiovascular function under conditions of ischemia may be distinct compared to other injuries/diseases of the muscles. It is widely accepted that group III and IV muscle afferents play an important role in the development of pain due to ischemia. These same muscle afferents also form the sensory component of the exercise pressor reflex (EPR), which is the increase in heart rate and blood pressure (BP) experienced after muscle contraction. Studies suggest that afferent sensitization after ischemia depends on interactions between purinergic (P2X and P2Y) receptors, transient receptor potential (TRP) channels, and acid sensing ion channels (ASICs) in individual populations of peripheral sensory neurons. Specific alterations in primary afferent function through these receptor mechanisms correlate with increased pain related behaviors and altered EPRs. Recent evidence suggests that factors within the muscles during ischemic conditions including upregulation of growth factors and cytokines, and microvascular changes may be linked to the overexpression of these different receptor molecules in the dorsal root ganglia (DRG) that in turn modulate pain and sympathetic reflexes. In this review article, we will discuss the peripheral mechanisms involved in the development of ischemic myalgia and the role that primary sensory neurons play in EPR modulation.

Neonatal Invasive Procedures Predict Pain Intensity at School Age in Children Born Very Preterm

INTRODUCTION

Children born very preterm display altered pain thresholds. Little is known about the neonatal clinical and psychosocial factors associated with their later pain perception.

OBJECTIVE

We aimed to examine whether the number of neonatal invasive procedures, adjusted for other clinical and psychosocial factors, was associated with self-ratings of pain during a blood collection procedure at school age in children born very preterm.

MATERIALS AND METHODS

56 children born very preterm (24 to 32 weeks gestational age), followed longitudinally from birth, and free of major neurodevelopmental impairments underwent a blood collection by venipuncture at age 7.5 years. The children's pain was self-reported using the Coloured Analog Scale and the Facial Affective Scale. Parents completed the Child Behavior Checklist and the State-Trait Anxiety Inventory. Pain exposure (the number of invasive procedures) and clinical factors from birth to term-equivalent age were obtained prospectively. Multiple linear regression was used to predict children's pain self-ratings from neonatal pain exposure after adjusting for neonatal clinical and concurrent psychosocial factors.

RESULTS

A greater number of neonatal invasive procedures and higher parent trait-anxiety were associated with higher pain intensity ratings during venipuncture at age 7.5 years. Fewer surgeries and lower concurrent child externalizing behaviors were associated with a higher pain intensity.

CONCLUSIONS

In very preterm children, exposure to neonatal pain was related to altered pain self-ratings at school age, independent of other neonatal factors. Neonatal surgeries and concurrent psychosocial factors were also associated with pain ratings.

What dilemmas do healthcare workers face looking after children with acute pain?

There have been significant advances in the treatment of acute pain in children alongside increased academic interest in the field. This has led to improvements in both efficacy and safety alongside the development of multidisciplinary pain services. Despite this, however, there are still high rates of acute pain reported in children in both inpatient and outpatient settings. In this article, we discuss some of the challenges faced by healthcare workers in designing effective multidisciplinary treatment regimens, understanding the implications for long-term pain and pain processing of acute pain and analgesic interventions as well as ongoing issues around research, education and resource.

Age-Dependent Sexual Dimorphism in Susceptibility to Develop Chronic Pain in the Rat

Neonatal pain has been suggested to contribute to the development and/or persistence of adult pain. Observations from animal models have shown that neonatal inflammation produces long-term changes in sensory neuron function, which can affect the susceptibility of adults to develop persistent pain. We used a preclinical model of transition to chronic pain, hyperalgesic priming, in which a previous inflammatory stimulus triggers a long-lasting increase in responsiveness to pro-algesic mediators, prototypically prostaglandin E₂ (PGE₂), to investigate if post-natal age influences susceptibility of adult rats to develop chronic pain. Priming was induced by tumor necrosis factor alpha (TNFα), in male and female rats, 1, 2, 3, 4, 5 or 7weeks after birth. When adults (8weeks after birth), to evaluate for the presence of priming, PGE₂ was injected at the same site as TNFα. In males that had received TNFα at post-natal weeks 1, 2 or 3, priming was attenuated compared to the 4-, 5- and 7-week-old treated groups, in which robust priming developed. In contrast, in females treated with TNFα at post-natal week 1, 2, 3, or 4, but not at 5 or 7, priming was present. This age and sex difference in the susceptibility to priming was estrogen-dependent, since injection of TNFα in 3-week-old males and 5-week-old females, in the presence of the estrogen receptor antagonist ICI 182,780, did produce priming. These results suggest that estrogen levels, which vary differently in males and females over the post-natal period, until they stabilize after puberty, impact pain as an adult.