Cerebral processing of pain in school-aged children with neonatal nociceptive input: An exploratory fMRI study

Leptin and Leptin Receptor Polymorphisms in Infants and Their Parents: Correlation with Preterm Birth

It has been proven that single-nucleotide polymorphisms (SNPs) in LEP and LEPR genes could predispose individuals to an increased risk of pregnancy adverse outcomes (PAOs) such as recurrent pregnancy loss (RPL) and pre-eclampsia. Preterm birth (PTB) is the leading cause of infant mortality. We decided to investigate the correlation between PTB and LEP and LEPR SNPs. The study cohort included families who underwent spontaneous PTB and control samples of families who had at-term-born (≥37 weeks of gestational age) children. Swabs were performed by rubbing the sticky end for about 30 s on the gum and on the inside of the cheek, allowing us to collect the flaking cells of the oral mucosa. Genotyping of the three SNPs-LEPRA668G, LEPG2548A and A19G-was carried out via an ARMS-MAMA real-time PCR procedure, as previously described. Regarding LEPG2548A, we found that the most expressed genotype in infants both in the preterm and the at-term group was AG; however, we did not discover any statistically significant difference (p = 0.97). Considering LEPA19G, none among the infants and parents were found to carry the AA genotype. No statistically significant differences were found between children, mothers and fathers belonging to preterm and at-term groups. We did not find a statistically significant association in newborns and their mother, but our results show a statistical correlation with the LEPRA668G genotype GG of the father. This fact can contribute to defining genetic risk factors for PTB. Further studies are certainly needed to better clarify the role of genetics in influencing preterm delivery.

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.

Intervención educativa para mejorar el diagnóstico y manejo del dolor en unidades de recién nacidos en Colombia

Objetivo: Evaluar el impacto en profesionales y pacientes de desarrollar e implementar una estrategia educativa en tres unidades neonatales en Bogotá (Colombia) para el reconocimiento y manejo del dolor. Metodología: Estudio de antes y después para evaluar el cambio en los conocimientos y aptitudes de los profesionales mediante encuestas consecutivas, y el cambio en el registro y manejo del dolor, evaluando la información consignada en las historias clínicas en ambos periodos. Resultados: Se encuestaron 70 profesionales de la salud antes y después de la implementación de la estrategia. Se encontró un cambio en sus aptitudes con respecto al uso de escalas de dolor (p = 0,03), el conocimiento de medidas no farmacológicas (p = 0,009) y el uso de medidas farmacológicas (p = 0,009). Adicionalmente, se analizaron las historias clínicas de 75 neonatos antes y 75 después de la implementación de la estrategia, lo que evidenció un incremento en el uso de escalas para evaluar el dolor asociado con procedimientos diagnósticos (1,3% vs. 20%; p < 0,01), y terapéuticos (0% vs. 56,7%; p < 0,01) y en la proporción de pacientes que recibieron manejo farmacológico (17,3% vs. 53,7%; p < 0,01). Conclusión: Los resultados sugieren que la implementación de una estrategia educativa mejora los conocimientos y aptitudes de los profesionales, así como el compromiso con las medidas dirigidas a diagnosticar y tratar adecuadamente el dolor en las unidades neonatales.

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.

Usefulness of two types of pain monitors in newborns treated in NICU, in the opinion of experts: Results of the survey

Pain experienced in the neonatal period has been shown to have serious short- and long-term consequences. It is also known that painkillers have side effects and should not be abused. The basis of proper pain management is assessment of pain, which in newborns is very difficult due to the lack of verbal communication. In these patients, behavioural scales are used to assess pain, but they have numerous shortcomings. For this reason, many newborns treated in the ICU are at risk of pain, so instrumental methods of detecting and assessing the severity of pain are being sought. During three months, seven Polish NICUs conducted research with the use of NIPE and SCA monitors. After this time, the heads of these departments filled in questionnaires regarding their individual opinions on the usefulness of these devices. All respondents found pain monitors useful in the NICU. The NIPE monitor was rated slightly higher, as its usefulness in assessing the effectiveness of analgosedation and in the management of patients in the postoperative period was better rated. The high acceptance of both devices by legal guardians of newborns is noteworthy. It should be stated that in newborns, any way to improve pain monitoring is valuable. In the opinion of Polish experts, pain monitors are useful in NICU. The NIPE monitor was assessed a little higher and was considered useful in the assessment of analgosedation and in postoperative treatment. Pain monitors can provide valuable support for pain assessment in newborns treated in the NICU.

Pain management for necrotizing enterocolitis: getting the balance right

BACKGROUND

Adequate pain management for preterm born neonates suffering from the extremely painful disease necrotizing enterocolitis (NEC) is essential, since neonatal exposure to pain is related to negative short-term and long-term consequences. The aim of this study was to describe the current pain management and its effectiveness in NEC patients.

METHODS

In this single-center, retrospective study, neonates (gestational age < 32 weeks and/or birth weight < 1500 g) with NEC Bell's stage II or III were included. Information on pain (based on COMFORTneo and NRS scores) and analgesic therapy was collected and analyzed for the acute disease period.

RESULTS

Of 79 patients included, 74 (94%) received intravenous analgesic therapy: most commonly morphine, fentanyl, and acetaminophen. The median COMFORTneo score was 11 (IQR 10-11), however, 49 patients had at least one COMFORTneo score ≥ 14 indicating pain. Nineteen patients had persistent high pain scores ≥ 14 with a median duration of 7.2 h (IQR 2.8-14.0).

CONCLUSIONS

This study showed that despite analgesic therapy, most NEC patients showed signs of pain, and in some, pain persisted for several hours. It suggests that current analgesic therapy frequently failed to prevent pain and existing pain was often insufficiently treated. This supports the urgent need for individualized pain management guidelines for NEC patients.

IMPACT

This study is unique in reporting on pain management in neonates suffering from necrotizing enterocolitis (NEC) during the full acute disease period. Despite analgesic therapy, the majority of NEC patients experience pain, and in some patients, pain persists for several hours. These findings highlight the need for improvement of neonatal pain management in NEC patients, including better pain monitoring and guidelines for individualized analgesic therapy. Improved pain management guidelines may help to prevent short-term and long-term consequences of neonatal exposure to pain, as well as excessive exposure to opioids.

Neonatal Pain, Opioid, and Anesthetic Exposure; What Remains in the Human Brain After the Wheels of Time?

OBJECTIVE

To evaluate possible negative long-term effects of neonatal exposure to pain, opioids and anesthetics in children and adolescents.

STUDY DESIGN

We studied five unique groups of children recruited from well-documented neonatal cohorts with a history of neonatal exposure to pain, opioids or anesthetics at different points along the continuum from no pain to intense pain and from no opioid exposure to very high opioid exposure in the presence or absence of anesthetics. We evaluated children who underwent major surgery (group 1 and 2), extracorporeal membrane oxygenation (group 3), preterm birth (group 4) and prenatal opioid exposure (group 5) in comparison to healthy controls. Neuropsychological functioning, thermal detection and pain thresholds and high-resolution structural and task-based functional magnetic resonance imaging during pain were assessed. In total 94 cases were included and compared to their own control groups.

RESULTS

Children and adolescents in groups 3 and 5 showed worse neuropsychological functioning after high opioid exposure. A thicker cortex was found in group 1 (pain, opioid and anesthetic exposure) in only the left rostral-middle-frontal-cortex compared to controls. We found no differences in other brain volumes, pain thresholds or brain activity during pain in pain related brain regions between the other groups and their controls.

CONCLUSIONS

No major effects of neonatal pain, opioid or anesthetic exposure were observed in humans 8-19 years after exposure in early life, apart from neuropsychological effects in the groups with the highest opioid exposure that warrants further investigation. Studies with larger sample sizes are needed to confirm our findings and test for less pronounced differences between exposed and unexposed children.

Available Instruments to Assess Pain in Infants

Pain assessment in newborns and infants is challenging for clinicians. Although behavioral and behavioral-physiological scales are validated pain assessment instruments, their use in this age group has significant limitations. In this review, we summarize the methods currently available for assessing pain in neonates and infants. It is possible that these pain detection methods are also useful for assessing the quality of anesthesia and analgosedation in these populations. Further research should be aimed at confirming the usefulness of these tools in infants and identifying additional pain assessment options for clinical practice.

Evaluation of pain and physiological stress during targeted neonatal echocardiography

BACKGROUND

Targeted neonatal echocardiography (Tn-Echo) is a non-invasive examination which may cause pain/discomfort and physiological instability in neonates, but there is little evidence for the same. We conducted this study to evaluate whether targeted neonatal echocardiography causes pain or physiological stress to newborn infants.

METHODS

This cross-sectional study was conducted in a tertiary level NICU. Neonates undergoing targeted neonatal echocardiography were enrolled in this study. Pain was assessed using Premature Infant Pain Profile-Revised (PIPP-R) score before, during and after targeted neonatal echocardiography examination. Heart rate, oxygen saturation, perfusion index and blood pressure were also recorded at the same time points.

RESULTS

A total of 88 neonates were enrolled. Mean (SD) PIPP-R score during Tn-Echo was 8.18 (2.6) versus 3.60 (1.8) and 4.24 (2.0) before and after respectively (p value <  0.001). Heart rate and respiratory rate were significantly higher during targeted neonatal echocardiography; oxygen saturation and perfusion index were significantly lower during targeted neonatal echocardiography. Preterm infants had higher PIPP-R score compared to term neonates before, during and after the Tn-Echo [8.76 (2.4) versus 6.81 (2.4); p value <  0.001].

CONCLUSION

Targeted neonatal echocardiography causes significant pain/discomfort and physiological instability in neonates.

A Systematic Review of Clinical Practice Guidelines for Acute Procedural Pain on Neonates

OBJECTIVES

During hospitalization in neonatal intensive care units, neonates are exposed to many painful procedures within a stressful environment. To date, many evidence-based guidelines are available. However, the quality of these guidelines and their clinical application remain unclear. This systematic review aimed to determinie the quality of existing guidelines on the management of procedural pain in neonates and to summarize the recommendations provided by these guidelines.

MATERIALS AND METHODS

A structured search was conducted in Embase, PubMed, CINAHL, JBI database, and gray literature resources in November 2018 to identify relevant guidelines published from 2007 onward. Published guidelines and guidelines from complementary searches were included in the treating assessment or management of procedural pain in neonates. The methodological quality was analyzed using the Appraisal of Guidelines for Research and Evaluation (AGREE) II Instrument.

RESULTS

A total of 1154 records were identified. After screening for eligibility, 17 guidelines were included in this review. Among these, 11 were identified to be high-quality guidelines. Besides the usual recommendations for pharmacological and nonpharmacological treatments, the inclusion of parents, improving interprofessional collaboration, and considering the setting were identified as important elements.

DISCUSSION

The results of this review show that there is a need to improve the methodological quality of guidelines for procedural pain in newborns. The set of recommendations for procedural pain prevention needs to involve not only pharmacological and nonpharmacological pain treatment but also parents and interprofessional collaboration. It is also essential to take into account facilitators, barriers, and the context to improve pain management.

Does Repeated Painful Stimuli Change Cerebral Near-Infrared Spectroscopy Response in Healthy, Term, Large for Gestational Age Newborns?

OBJECTIVE

The objective of this study was to evaluate the effect of repeated painful stimuli on short-term pain response in healthy, term, large for gestational age newborns by measuring the regional cerebral oxygen saturation (rScO2), and behavioral and physiological responses.

METHODS

We compared term large for gestational age infants who received repeated painful stimuli (study group) with term, appropriate for gestational age infants (control group). A pulse oximeter and a near-infrared spectroscopy probe were connected to babies during the study period, and the responses of the babies were recorded by video, from which the crying time and the Neonatal Infant Pain Scale were obtained. The heart rate, peripheral oxygen saturation (SpO2), and rScO2 data were sampled every 1 second and exported to a personal computer via digital output during the study period. The maximum heart rate, the minimum SpO2, and peak, baseline, and mean rScO2 measurements following skin puncture were recorded. Data were compared within 1 group and between the 2 groups.

RESULTS

After the heel prick, crying time (P<0.001) and Neonatal Infant Pain Scale scores (P=0.024) increased, and SpO2 levels decreased significantly (P=0.012) in the study group versus the control group. Although mean rScO2 increased significantly within 1 group (P<0.001), it was not significant between the 2 groups. The percent change in rScO2 was greater in the study group (5.2 [2.5 to 9.3]) compared with the control group (2.8 [1.1 to 8.2], P=0.037).

CONCLUSION

We showed that rScO2 values changed significantly within the first few days of life in babies who received more painful stimuli compared with the control group, similar to behavioral and physiological responses.

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.

Single-nucleus characterization of adult mouse spinal dynorphin-lineage cells and identification of persistent transcriptional effects of neonatal hindpaw incision

Neonatal tissue damage can have long-lasting effects on nociceptive processing in the central nervous system, which may reflect persistent injury-evoked alterations to the normal balance between synaptic inhibition and excitation in the spinal dorsal horn. Spinal dynorphin-lineage (pDyn) neurons are part of an inhibitory circuit which limits the flow of nociceptive input to the brain and is disrupted by neonatal tissue damage. To identify the potential molecular underpinnings of this disruption, an unbiased single-nucleus RNAseq analysis of adult mouse spinal pDyn cells characterized this population in depth and then identified changes in gene expression evoked by neonatal hindpaw incision. The analysis revealed 11 transcriptionally distinct subpopulations (ie, clusters) of dynorphin-lineage cells, including both inhibitory and excitatory neurons. Investigation of injury-evoked differential gene expression identified 15 genes that were significantly upregulated or downregulated in adult pDyn neurons from neonatally incised mice compared with naive littermate controls, with both cluster-specific and pan-neuronal transcriptional changes observed. Several of the identified genes, such as Oxr1 and Fth1 (encoding ferritin), were related to the cellular stress response. However, the relatively low number of injury-evoked differentially expressed genes also suggests that posttranscriptional regulation within pDyn neurons may play a key role in the priming of developing nociceptive circuits by early-life injury. Overall, the findings reveal novel insights into the molecular heterogeneity of a key population of dorsal horn interneurons that has previously been implicated in the suppression of mechanical pain and itch.

Neonatal male circumcision is associated with altered adult socio-affective processing

BACKGROUND

Neonatal male circumcision is a painful skin-breaking procedure that may affect infant physiological and behavioral stress responses as well as mother-infant interaction. Due to the plasticity of the developing nociceptive system, neonatal pain might carry long-term consequences on adult behavior. In this study, we examined whether infant male circumcision is associated with long-term psychological effects on adult socio-affective processing.

METHODS

We recruited 408 men circumcised within the first month of life and 211 non-circumcised men and measured socio-affective behaviors and stress via a battery of validated psychometric scales.

RESULTS

Early-circumcised men reported lower attachment security and lower emotional stability while no differences in empathy or trust were found. Early circumcision was also associated with stronger sexual drive and less restricted socio-sexuality along with higher perceived stress and sensation seeking.

LIMITATIONS

This is a cross-sectional study relying on self-reported measures from a US population.

CONCLUSIONS

Our findings resonate with the existing literature suggesting links between altered emotional processing in circumcised men and neonatal stress. Consistent with longitudinal studies on infant attachment, early circumcision might have an impact on adult socio-affective traits or behavior.

Atypical neuromagnetic resting activity associated with thalamic volume and cognitive outcome in very preterm children

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Preterm birth is associated with higher risk of negative neurocognitive outcomes.

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At school age, preterm children have atypical frequency-specific power at rest.

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Thalamic volume reduction is associated with atypical power in preterm birth.

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Thalamic matter intensity is associated with negative neurocognitive outcomes.

Children born very preterm, even in the absence of overt brain injury or major impairment, are at increased risk of cognitive difficulties. This risk is associated with developmental disruptions of the thalamocortical system during critical periods while in the neonatal intensive care unit. The thalamus is an important structure that not only relays sensory information but acts as a hub for integration of cortical activity which regulates cortical power across a range of frequencies. In this study, we investigate the association between atypical power at rest in children born very preterm at school age using magnetoencephalography (MEG), neurocognitive function and structural alterations related to the thalamus using MRI. Our results indicate that children born extremely preterm have higher power at slow frequencies (delta and theta) and lower power at faster frequencies (alpha and beta), compared to controls born full-term. A similar pattern of spectral power was found to be associated with poorer neurocognitive outcomes, as well as with normalized T1 intensity and the volume of the thalamus. Overall, this study provides evidence regarding relations between structural alterations related to very preterm birth, atypical oscillatory power at rest and neurocognitive difficulties at school-age children born very preterm.

Managing childhood cancer pain into survivorship: recognition and emerging principles

PURPOSE OF REVIEW

Continual refinement and further stratification of childhood cancer treatment has led to increased survivorship with recognized improvements in many long-term health outcomes. Despite this progress, persisting pain prevalence in childhood cancer survivors is increasing and emerging as a significant long-term health concern.

RECENT FINDINGS

Currently, there is no guidance on how to approach and manage persisting pain in survivors of childhood cancer.

SUMMARY

Clinicians should work with children and young people to optimize the management of pain and other symptoms on treatment. Focusing on an early post treatment screening for pain and other symptoms (including sleep and fatigue), and the role of on-going analgesic use. Follow-up should offer a multidisciplinary approach, aimed at lessening reliance on pharmacological approaches to pain management, addressing psychological concerns and promoting increased physical activity. The onus is on clinicians to mitigate the long-term risk of pharmacological reliance, particularly opioid dependency, in patients leaving their care and heading into adulthood. In this article, we highlight the emerging evidence of persisting pain in survivors of childhood cancer as a significant long-term health outcome and consider some initial principles of management.

Neonatal Injury Evokes Persistent Deficits in Dynorphin Inhibitory Circuits within the Adult Mouse Superficial Dorsal Horn

Neonatal tissue damage induces long-term deficits in inhibitory synaptic transmission within the spinal superficial dorsal horn (SDH) that include a reduction in primary afferent-evoked, feedforward inhibition onto adult projection neurons. However, the subpopulations of mature GABAergic interneurons which are compromised by early-life injury have yet to be identified. The present research illuminates the persistent effects of neonatal surgical injury on the function of inhibitory SDH interneurons derived from the prodynorphin (DYN) lineage, a population that synapses directly onto lamina I spinoparabrachial neurons and is known to suppress mechanical pain and itch in adults. The results demonstrate that hindpaw incision at postnatal day 3 (P3) significantly decreased the strength of primary afferent-evoked glutamatergic drive onto DYN neurons within the adult mouse SDH while increasing the appearance of afferent-evoked inhibition onto the same population. Neonatal injury also dampened the intrinsic membrane excitability of mature DYN neurons, and reduced their action potential discharge in response to sensory input, compared with naive littermate controls. Furthermore, P3 incision decreased the efficacy of inhibitory DYN synapses onto adult spinoparabrachial neurons, which reflected a prolonged reduction in the probability of GABA release. Collectively, the data suggest that early-life tissue damage may persistently constrain the ability of spinal DYN interneurons to limit ascending nociceptive transmission to the adult brain. This is predicted to contribute to the loss of feedforward inhibition onto mature projection neurons, and the "priming" of nociceptive circuits in the developing spinal cord, following injuries during the neonatal period.SIGNIFICANCE STATEMENT Neonatal injury has lasting effects on pain processing in the adult CNS, including a reduction in feedforward inhibition onto ascending projection neurons in the spinal dorsal horn. While it is clear that spinal GABAergic interneurons are comprised of multiple subpopulations that play distinct roles in somatosensation, the identity of those interneurons which are compromised by tissue damage during early life remains unknown. Here we document persistent deficits in spinal inhibitory circuits involving dynorphin-lineage interneurons previously implicated in gating mechanical pain and itch. Notably, neonatal injury reduced the strength of dynorphin-lineage inhibitory synapses onto mature lamina I spinoparabrachial neurons, a major output of the spinal nociceptive network, which could contribute to the priming of pain pathways by early tissue damage.

Early life vincristine fails to prime developing pain pathways

Early life administration of vincristine (VNC), commonly used to treat pediatric leukemia, evokes peripheral neuropathy and mechanical pain hypersensitivity in rats that lasts into adolescence. However, the degree to which VNC-evoked neuropathic pain persists throughout adulthood has yet to be examined. It also remains unclear if pediatric VNC exposure can 'prime' developing nociceptive pathways and thereby exacerbate chronic pain following subsequent trauma later in life. To address these issues, rats received five total doses of VNC (60 μg/kg; or vehicle) on postnatal days (P) 11, 13, 17, 19 and 21 followed by a hindpaw surgical incision during adulthood. In addition, in order to model the clinical scenario where cancer relapse necessitates another round of chemotherapy, separate groups of rats that had been treated with VNC (or vehicle) as neonates were subsequently administered VNC as adults (five injections at 100 μg/kg). Intraepidermal nerve fiber density and baseline mechanical pain sensitivity were similar between the neonatal VNC and vehicle-treated littermate controls at 13-15 weeks of age, suggesting that the peripheral neuropathy, and resulting chronic pain, had resolved by adulthood. Importantly, there was no significant overall effect of early life VNC on the severity of post-operative pain following adult incision. Similarly, prior VNC exposure did not significantly influence the degree of mechanical pain hypersensitivity produced by adult VNC treatment. Collectively, these findings suggest that early life VNC administration does not increase the susceptibility to develop chronic pain as adults.

Exercise alters cerebellar and cortical activity related to working memory in phenotypes of Gulf War Illness

Gulf War Illness affects 25–32% of veterans from the 1990–91 Persian Gulf War. Post-exertional malaise with cognitive dysfunction, pain and fatigue following physical and/or mental effort is a defining feature of Gulf War Illness. We modelled post-exertional malaise by assessing changes in functional magnetic resonance imaging at 3T during an N-Back working memory task performed prior to a submaximal bicycle stress test and after an identical stress test 24 h later. Serial trends in postural changes in heart rate between supine and standing defined three subgroups of veterans with Gulf War Illness: Postural Orthostatic Tachycardia Syndrome (GWI-POTS, 15%, n = 11), Stress Test Associated Reversible Tachycardia (GWI-START, 31%, n = 23) and Stress Test Originated Phantom Perception (GWI-STOPP, no postural tachycardia, 54%, n = 46). Before exercise, there were no differences in blood oxygenation level-dependent activity during the N-Back task between control (n = 31), GWI-START, GWI-STOPP and GWI-POTS subgroups. Exercise had no effects on blood oxygenation level-dependent activation in controls. GWI-START had post-exertional deactivation of cerebellar dentate nucleus and vermis regions associated with working memory. GWI-STOPP had significant activation of the anterior supplementary motor area that may be a component of the anterior salience network. There was a trend for deactivation of the vermis in GWI-POTS after exercise. These patterns of cognitive dysfunction were apparent in Gulf War Illness only after the exercise stressor. Mechanisms linking the autonomic dysfunction of Stress Test Associated Reversible Tachycardia and Postural Orthostatic Tachycardia Syndrome to cerebellar activation, and Stress Test Originated Phantom Perception to cortical sensorimotor alterations, remain unclear but may open new opportunities for understanding, diagnosing and treating Gulf War Illness.

Nonopioid analgesics for perioperative and cardiac surgery pain in children: Current evidence and knowledge gaps

Objective:

The purpose of this review is to present the available literature on the use of nonopioid analgesics such as nonsteroidal anti-inflammatory drugs in postcardiac surgery pediatric patients, mainly to focus on patients <1 year of age, and to provide the foundation for future research.

Materials and Methods:

Published studies that address the use on nonopioid medications for postoperative sedation and analgesia in infants and children undergoing cardiac surgery were identified from online sources. Studies were reviewed by two authors independently to assess the quality of the data as well as the evidence. Due to limited availability of such studies, the review was then expanded to include use in noncardiac procedures as well as to expanded age groups. All studies that met the primary objective were included.

Results/Data Synthesis:

Majority of the studies in the population of interest were related to use of ketorolac. Five studies specifically addressed ketorolac use in cardiac patients. In addition, studies were reviewed for nonopioid analgesia in noncardiac patients and included as a part of the available evidence as in the case of acetaminophen use. Newer agents as well as agents with very limited information were also acknowledged.

Conclusion:

Nonopioid medications appear to show promise for analgesia in infants undergoing cardiac surgery, with ketorolac being the most potent agent as a potential substitute for opioids. These agents demonstrate a reasonable safety profile even in the very young. There continue to be significant gaps in knowledge before their adoption becomes routine. However, gives the awareness regarding short-term and long-term impact of opioid use in this vulnerable population, and studies of such agents are an urgent need.

Preterm infants with peri/intraventricular hemorrhage have poorer habituation responses to external stimuli

OBJECTIVE

To evaluate the association between intra-ventricular hemorrhage and habituation responses to external stimuli in preterm infants at 36-38 weeks post-conceptual age.

METHODS

Cross-sectional study of infants with gestational age <32 weeks. Intra-ventricular hemorrhage was identified by cranial ultrasonography and classified according to Papile et al. (1978). The luminous (flashlight), sound (rattle, bell), and tactile stimuli were presented, and the responses were scored according to Lester and Tronik (2004). Habituation response scores were compared between groups by Student's t-test. The association between IVH and habituation scores was evaluated by linear regression adjusted for GA, clinical severity score, post-conceptual age at habituation assessment, sepsis, and bronchopulmonary dysplasia.

RESULTS

Sixty-five infants were studied, 20 with intra-ventricular hemorrhage (16 grades I/II; four grades III/IV) and 45 without intra-ventricular hemorrhage. Infants with intra-ventricular hemorrhage had lower gestational age (28.2±2.2 vs. 29.7±1.7 weeks) and birth weight (990±305 vs. 1275±360g). Infants with intra-ventricular hemorrhage at 36-38 weeks post-conceptual age had lower habituation scores to light (4.21±2.23 vs. 6.09±2.44), rattle (3.84±2.12 vs. 6.18±2.27), and bell (3.58±1.74 vs. 5.20±2.47) after controlling for confounders. No differences were found for tactile stimulus.

CONCLUSION

Infants with gestational age <32 weeks and intra-ventricular hemorrhage had poorer habituation responses to external stimuli than those without intra-ventricular hemorrhage at 36-38 weeks post-conceptual age.

Newer nerve blocks in pediatric surgery

PURPOSE OF THE REVIEW

The purpose of this manuscript is to provide a brief discussion of the current direction in pediatric regional anesthesia, highlighting both newer nerve blocks and techniques and traditional nerve blocks.

RECENT FINDINGS

The number of nerve blocks performed in pediatric patients continues to increase. This growth is likely related in part to the recent focus on perioperative multimodal analgesia, in addition to growing data demonstrating safety and efficacy in this patient population. Multiple studies by the Pediatric Regional Anesthesia Network (PRAN) and the French-Language Society of Pediatric Anesthesiologists (ADARPEF) have demonstrated lack of major complications and general overall safety with pediatric nerve blocks. The growing prevalence of ultrasound-guided regional anesthesia has not only improved the safety profile, but also increased the efficacy of both peripheral nerve blocks and perineural catheters.

SUMMARY

As the push for multimodal analgesia increases and the breadth of pediatric regional anesthesia continues to expand, further large prospective studies will be needed to demonstrate continued efficacy and overall safety.

Postoperative pain in small-for-gestational age infants after hernia repair, orchidopexy and urethral reconstruction surgery: A pilot study

BACKGROUND

Small-for-gestational-age (SGA) birth bears an enhanced risk of developing hypertension, obesity, insulin resistance and mental health disorders in later life as a consequence of adaptive processes in utero. Only a small number of studies on pain perception in SGA infants exist. These are indicative of a blunted stress response to pain in SGA newborns.

AIM

We initiated a pilot study investigating differences in postoperative pain perception between SGA and appropriate-for-gestational-age (AGA) infants.

METHODS

Pain and alertness levels of 10 formerly SGA and 14 AGA infants at the age 0.5-2 years were evaluated by the FLACC scale, Steward and Aldrete Scores following hernia repair, reconstructive surgery of hypospadia and orchidopexy. In addition, the postoperative consumption of non-steroidal anti-inflammatory drugs was compared between SGA and AGA.

RESULTS

Postoperative pain and alertness levels were not significantly different in SGA and AGA children. We did not observe significant group differences regarding the consumption of non-steroidal anti-inflammatory drugs.

CONCLUSION

While previous studies were suggestive of a suppressed stress response to pain in SGA newborns, these findings did not fully translate into an altered response to pain beyond the newborn age. Further studies in a larger cohort seem necessary to verify this finding.

The development of pain circuits and unique effects of neonatal injury

Pain is a necessary sensation that prevents further tissue damage, but can be debilitating and detrimental in daily life under chronic conditions. Neuronal activity strongly regulates the maturation of the somatosensory system, and aberrant sensory input caused by injury or inflammation during critical periods of early postnatal development can have prolonged, detrimental effects on pain processing. This review will outline the maturation of neuronal circuits responsible for the transmission of nociceptive signals and the generation of pain sensation-involving peripheral sensory neurons, the spinal cord dorsal horn, and brain-in addition to the influences of the neuroimmune system on somatosensation. This summary will also highlight the unique effects of neonatal tissue injury on the maturation of these systems and subsequent consequences for adult somatosensation. Ultimately, this review emphasizes the need to account for age as an independent variable in basic and clinical pain research, and importantly, to consider the distinct qualities of the pediatric population when designing novel strategies for pain management.

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.

Developmental neurobiology as a guide for pharmacological management of pain in neonates

Pain in newborn children should be prevented due to negative short- and long-term consequences. A good understanding of the development of the nociceptive system in newborns is necessary to enable optimal pain assessment, and most importantly to treat and prevent pain adequately in neonates. So far, preclinical juvenile animal studies have led to a tremendous amount of information regarding the development of the nociceptive system. In addition, they have made clear that the developmental stage of the nociceptive system may influence the mechanism of action of different classes of analgesics. Age specific analgesic therapy, based on post-menstrual age, should therefore be considered by incorporating information on the developmental stages of the nociceptive system in combination with knowledge from pharmacokinetic and -dynamic studies in neonates.

Nociception and the neonatal brain

Measuring brain activity in infants provides an objective surrogate approach with which to infer pain perception following noxious events. Here we discuss different approaches which can be used to measure noxious-evoked brain activity, and discuss how these measures can be used to assess the analgesic efficacy of pharmacological and non-pharmacological interventions. We review factors that can modulate noxious-evoked brain activity, which may impact infant pain experience, including gestational age, sex, prior pain, stress, and illness.

The use of ultrasound guidance for perioperative neuraxial and peripheral nerve blocks in children

BACKGROUND

The use of ultrasound guidance for regional anaesthesia has become popular over the past two decades. However, it is not recognized by all experts as an essential tool, perhaps because it is unclear whether ultrasound reduces the risk of severe neurological complications, and the cost of an ultrasound machine (USD 22,000) is substantially higher than the cost of other tools. This review was published in 2016 and updated in 2019.

OBJECTIVES

To determine whether ultrasound guidance offers any clinical advantage when neuraxial and peripheral nerve blocks are performed in children in terms of decreasing failure rate or the rate of complications.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and two trial registers up to March 2018 together with reference checking to identify additional studies and contacted study authors to obtain additional trial information.

SELECTION CRITERIA

We included all parallel randomized controlled trials that evaluated the effects of ultrasound guidance used when a regional blockade technique was performed in children. We included studies performed in children (≤ 18 years of age) undergoing any type of surgical procedure (open or laparoscopic), for which a neuraxial (spinal, epidural, caudal, or combined spinal and epidural) or peripheral nerve block (any peripheral nerve block including fascial (fascia iliaca, transversus abdominis plane, rectus sheath blocks) or perivascular blocks), for surgical anaesthesia (alone or in combination with general anaesthesia) or for postoperative analgesia, was performed with ultrasound guidance. We excluded studies in which regional blockade was used to treat chronic pain.We included studies in which ultrasound guidance was used to perform the technique in real time (in-plane or out-of-plane), as pre-scanning before the procedure or to evaluate the spread of the local anaesthetic so the position of the needle could be adjusted or the block complemented. For control groups, any other technique used to perform the block including landmarks, loss of resistance (air or fluid), click, paraesthesia, nerve stimulator, transarterial, or infiltration was accepted.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by Cochrane. Our primary outcomes were failed blocks, pain scores at one hour after surgery, and block duration. Secondary outcomes included time to perform the block, number of needle passes, and minor and major complications. We used GRADE to assess the quality of evidence for each outcome.

MAIN RESULTS

We included 33 trials with a total of 2293 participants from 0.9 to 12 (mean or median) years of age. Most trials were at low risk of selection, detection, attrition, and reporting bias, however the lack of blinding of participants and personnel caring for participants resulted in 25 trials being judged as at high or unclear risk of bias. We identified five ongoing trials.Ultrasound guidance probably reduces the risk of failed block (risk difference (RD) -0.16, 95% confidence interval (CI) -0.25 to -0.07; 22 trials; 1789 participants; moderate-quality evidence). When ultrasound guidance was used, there was a small to moderate reduction in pain one hour after surgery, equivalent to a reduction of 1.3 points on the revised Bieri FACES pain scale (scale; 0 = no pain, 10 = maximal pain) (standardized mean difference (SMD) -0.41, 95% CI -0.74 to -0.07 (medium effect size); 15 trials; 982 participants; moderate-quality evidence). Ultrasound guidance increases block duration by the equivalent of 42 minutes (SMD 1.24, 95% CI 0.72 to 1.75; 10 trials; 460 participants; high-quality evidence).There is probably little or no difference in the time taken to perform the block (SMD -0.46, 95% CI -1.06 to 0.13; 9 trials; 680 participants; moderate-quality evidence). It is uncertain whether the number of needle passes required is reduced with the use of ultrasound guidance (SMD -0.63, 95% CI -1.08 to -0.18; 3 trials; 256 participants; very low-quality evidence).There were no occurrences of major complications in either the intervention or control arms of the trials (cardiac arrest from local anaesthetic toxicity (22 trials; 1576 participants; moderate-quality evidence); lasting neurological injury (19 trials; 1250 participants; low-quality evidence)).There may be little of no difference in the risk of bloody puncture (RD -0.02, 95% CI -0.05 to 0.00; 13 trials; 896 participants; low-quality evidence) or transient neurological injury (RD -0.00, 95% CI -0.01 to 0.01; 18 trials; 1230 participants; low-quality evidence). There were no occurrences of seizure from local anaesthetic toxicity (22 trials; 1576 participants; moderate-quality evidence) or block infections without neurological injury (18 trials; 1238 participants; low-quality evidence).

AUTHORS' CONCLUSIONS

Ultrasound guidance for regional blockade in children probably decreases the risk of failed block. It increases the duration of the block and probably decreases pain scores at one hour after surgery. There may be little or no difference in the risks of some minor complications. The five ongoing studies may alter the conclusions of the review once published and assessed.

Neonatal painful stimuli: skin conductance algesimeter index to measure efficacy 24% of sucrose oral solution

Pain management is one of the main challenges in addressing the improved care of hospitalized newborns. The administration of oral sucrose with and without non-nutritive suction has been proposed as a nonpharmacological intervention to relieve procedural pain in newborns. The effects have not yet been well characterized. The aim of this study is to investigate, using skin conductance algesimeter (SCA) pain monitor index, the effects of 24% sucrose solution on pain perception during capillary and arterial blood sampling. It is a prospective, randomized controlled study: sucrose versus placebo. Sucrose was given orally to infants who were submitted to arterial or capillary sampling. The SCA was measured during, and for 3 min before and after the intervention. Fifty-six infants were enrolled: 31 in the sucrose group and 25 in the placebo group. SCA showed that the measurement of peaks per second of pain during and 3 min after the procedures was lower in the sucrose group than the placebo group and that this difference was statistically significant (p < .05). In conclusion, 24% sucrose administered orally is effective in reducing pain during and after capillary and arterial sampling in newborns and can be used for the prevention and treatment of pain in the Neonatal Intensive Care Unit.Brief rationaleTo treat neonatal pain, a tiered approach with nonpharmacological and pharmacological method can be used.Among nonpharmacological therapies, sucrose administration is safe and effective in reducing single episodes of minor procedural pain. This study aimed to investigate, the effects of 24% sucrose solution on pain perception during capillary and arterial blood withdrawn by using an objective method: skin conductance algesimeter (SCA) pain monitor index.This randomized controlled trial in which term and/or preterm neonates (postnatal age maximum of 28 days corrected for postmenstrual age) received sucrose for procedural pain. Oral sucrose was administered directly by a disposable plastic vial. SCA was measured by means of a specific device.We demonstrated, using SCA pain monitor index, the efficacy of 24% sucrose solution on pain perception during capillary and arterial blood withdrawn. The results of this study provide an objective evidence of sucrose efficacy for the prevention and treatment of neonatal painful procedures.

Paediatric Pain Medicine: Pain Differences, Recognition and Coping Acute Procedural Pain in Paediatric Emergency Room

Paediatric pain and its assessment and management are challenging for medical professionals, especially in an urgent care environment. Patients in a paediatric emergency room (PER) often undergo painful procedures which are an additional source of distress, anxiety, and pain. Paediatric procedural pain is often underestimated and neglected because of various myths, beliefs, and difficulties in its evaluation and treatment. However, it is very different from other origins of pain as it can be preventable. It is known that neonates and children can feel pain and that it has long-term effects that last through childhood into adulthood. There are a variety of pain assessment tools for children and they should be chosen according to the patient’s age, developmental stage, communication skills, and medical condition. Psychological factors such as PER environment, preprocedural preparation, and parental involvement should also be considered. There are proven methods to reduce a patient’s pain and anxiety during different procedures in PER. Distraction techniques such as music, videogames, virtual reality, or simple talk about movies, friends, or hobbies as well as cutaneous stimulation, vibration, cooling sprays, or devices are effective to alleviate procedural pain and anxiety. A choice of distraction technique should be individualized, selecting children who could benefit from nonpharmacological pain treatment methods or tools. Nonpharmacological pain management may reduce dosage of pain medication or exclude pharmacological pain management. Most nonpharmacological treatment methods are cheap, easily accessible, and safe to use on every child, so it should always be a first choice when planning a patient’s care. The aim of this review is to provide a summary of paediatric pain features, along with their physiology, assessment, management, and to highlight the importance and efficacy of nonpharmacological pain management in an urgent paediatric care setting.

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.

Procedural Pain during Insertion of a Continuous Glucose Monitoring Device in Preterm Infants

Procedural pain was compared between the insertion of a continuous glucose monitoring sensor and heel stick using the Premature Infant Pain Profile in a single-blinded controlled trial in preterm infants (≤32 weeks of gestation or birth weight ≤1500 g) (ClinicalTrials.govNCT02583776). Continuous glucose monitoring insertion was associated with lower pain scores compared with the heel stick.

Enhanced Postsynaptic GABAB Receptor Signaling in Adult Spinal Projection Neurons after Neonatal Injury

Clinical and basic science research have revealed persistent effects of early-life injury on nociceptive processing and resulting pain sensitivity. While recent work has identified clear deficits in fast GABAA- and glycine receptor-mediated inhibition in the adult spinal dorsal horn after neonatal tissue damage, the effects of early injury on slow, metabotropic inhibition within spinal pain circuits are poorly understood. Here we provide evidence that neonatal surgical incision significantly enhances postsynaptic GABAB receptor signaling within the mature superficial dorsal horn (SDH) in a cell type-dependent manner. In vitro patch-clamp recordings were obtained from identified lamina I projection neurons and GABAergic interneurons in the SDH of adult female mice following hindpaw incision at postnatal day (P)3. Early tissue damage increased the density of the outward current evoked by baclofen, a selective GABAB receptor agonist, in projection neurons but not inhibitory interneurons. This could reflect enhanced postsynaptic expression of downstream G protein-coupled inward-rectifying potassium channels (GIRKs), as the response to the GIRK agonist ML297 was greater in projection neurons from neonatally incised mice compared to naive littermate controls. Meanwhile, presynaptic GABAB receptor-mediated reduction of spontaneous neurotransmitter release onto both neuronal populations was unaffected by early-life injury. Collectively, our findings suggest that ascending nociceptive transmission to the adult brain is under stronger control by spinal metabotropic inhibition in the aftermath of neonatal tissue damage.

Conditioned pain modulation identifies altered sensitivity in extremely preterm young adult males and females

BACKGROUND

Conditioned pain modulation is a potential biomarker for risk of persistent pain. As early-life experience can alter subsequent somatosensory processing and pain response, we evaluated conditioned pain modulation after extremely preterm birth.

METHODS

This observational study recruited extremely preterm (<26 weeks gestation; n=98) and term-born control (n=48) young adults (19-20 yr) from the longitudinal EPICure cohort. Pressure pain threshold (PPT; variable test stimulus lower leg) was measured before, during, and after a conditioning stimulus (contralateral hand immersion; 5°C water; 30 s). Questionnaires assessed current pain, medication use, anxiety, and pain catastrophising.

RESULTS

For participants tolerating conditioning, there were significant main effects of extremely preterm status, sex, and time on PPT during and after hand immersion. Inhibitory modulation was evoked in 64/98 extremely preterm (3, no change) and 38/48 term-born control (3, facilitation) subjects. The conditioned pain modulation effect (percentage change in PPT) did not differ between the extremely preterm and term-born control groups {53% [95% confidence interval (CI): 41-65] vs 57% [95% CI: 42-71]}. Reduced cold tolerance (<20 s) hampered conditioned pain modulation quantification in a higher proportion of extremely preterm participants [extremely preterm vs term-born control: 31/98 (32%) vs 7/48 (15%); P=0.03]. One-third of extremely preterm females withdrew the hand before parallel PPT (<15 s), and had lower baseline PPT than term-born control females [4.9 (95% CI: 4.8-5.1) vs 5.3 (95% CI: 5.1-5.5) ln kPa; P=0.02]. Higher anxiety, pain catastrophising, and medication use correlated with pain intensity, but not conditioned pain modulation effect.

CONCLUSIONS

Cold conditioning evoked inhibitory modulation in the majority of young adults and identified a subgroup of extremely preterm females with increased baseline sensitivity. Early-life experience and sex/gender should be considered when evaluating persistent pain risk with conditioned pain modulation.

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.

Early life vincristine exposure evokes mechanical pain hypersensitivity in the developing rat

Vincristine (VNC) is commonly used to treat pediatric cancers, including the most prevalent childhood malignancy, acute lymphoblastic leukemia. Although clinical evidence suggests that VNC causes peripheral neuropathy in children, the degree to which pediatric chemotherapeutic regimens influence pain sensitivity throughout life remains unclear, in part because of the lack of an established animal model of chemotherapy-induced neuropathic pain during early life. Therefore, this study investigated the effects of VNC exposure between postnatal days (P) 11 and 21 on mechanical and thermal pain sensitivity in the developing rat. Low doses of VNC (15 or 30 μg/kg) failed to alter nociceptive withdrawal reflexes at any age examined compared with vehicle-injected littermate controls. Meanwhile, high dose VNC (60 μg/kg) evoked mechanical hypersensitivity in both sexes beginning at P26 that persisted until adulthood and included both static and dynamic mechanical allodynia. Hind paw withdrawal latencies to noxious heat and cold were unaffected by high doses of VNC, suggesting a selective effect of neonatal VNC on mechanical pain sensitivity. Gross and fine motor function appeared normal after VNC treatment, although a small decrease in weight gain was observed. The VNC regimen also produced a significant decrease in intraepidermal nerve fiber density in the hind paw skin by P33. Overall, the present results demonstrate that high-dose administration of VNC during the early postnatal period selectively evokes a mechanical hypersensitivity that is slow to emerge during adolescence, providing further evidence that aberrant sensory input during early life can have prolonged consequences for pain processing.

Small-fiber neuropathy and pain sensitization in survivors of pediatric acute lymphoblastic leukemia

BACKGROUND

Chemotherapy-induced Peripheral Neuropathy (CIPN) of large-fibers affects up to 20% of survivors of pediatric acute lymphoblastic leukemia (ALL). We aimed to describe small-fiber toxicity and pain sensitization in this group.

METHODS

In a cross-sectional, bicentric study we assessed 46 survivors of pediatric ALL (Mean age: 5.7 ± 3.5 years at diagnosis, median 2.5 years after therapy; males: 28).

INCLUSION CRITERIA

≥6 years of age, ≥3 months after last administration of Vincristine, and cumulative dose of Vincristine 12 mg/m². We used a reduced version of the Pediatric-modified Total Neuropathy Score (Ped-mTNS) as bedside test and Quantitative Sensory Testing (QST) for assessment of small- and large-fiber neuropathy as well as pain sensitization. We employed Nerve Conduction Studies (NCS) as the most accurate tool for detecting large-fiber neuropathy.

RESULTS

Fifteen survivors (33%) had abnormal rPed-mTNS values (≥4 points) and 5 survivors (11%) reported pain. In QST, the survivor group showed significant (p < 0.001) inferior large-fiber function and pain sensitization when compared to healthy matched peers. We identified deficits of vibration in 33 (72%) and tactile hypoesthesia in 29 (63%), hyperalgesia to blunt pressure in 19 (41%), increased mechanical pain sensitivity in 12 (26%) and allodynia in 16 (35%) of 46 survivors. Only 7 survivors (15%) had pathologic NCS.

CONCLUSION

QST is a sensitive tool that revealed signs of large-fiber neuropathy in two thirds, small-fiber neuropathy and pain sensitization in one third of survivors. Prospective studies using QST in pediatric oncology may help to elucidate the pathophysiology of small-fiber neuropathy and pain sensitization as well as their relevance for quality of survival.

The manual orienting response habituation to repeated tactile stimuli in preterm neonates: Discrimination of stimulus locations and interstimulus intervals

Preterm infants frequently develop atypical sensory profiles, the tactile modality being particularly affected. However, there is a lack of recent investigation of neonatal tactile perception in a passive context, especially in preterms who are particularly exposed to this tactile stimuli. Our aims were to provide evidence of orienting responses (behavioral modifications directing subject's attention towards stimuli) and habituation to passive tactile stimuli in preterm neonates, to explore their ability to perceive spatial and temporal aspects of the stimulus, and to evaluate the effect of clinical factors on these abilities. We included 61 preterm neonates, born between 32 and 34 weeks of gestational age. At 35 weeks of corrected gestational age, we measured orienting responses (forearm, hand, and fingers movements) during vibrotactile stimulation of their hand and forearm; during a habituation and dishabituation paradigm, the dishabituation being either a location change or a pause in the stimulation sequence. Preterm newborns displayed a manual orienting response to vibrotactile stimuli which significantly decreased when the stimulus was repeated, regardless of the stimulated location on the limb. Habituation was delayed in subjects born at a younger gestational age, smaller birth weight, and having experienced more painful care procedures. Preterm neonates perceived changes in stimulus location and interstimulus time interval. Our findings provide insights on several aspects of the perception of repeated tactile stimuli by preterm neonates, and the first evidence of the early development of temporal processing abilities in the tactile modality. Future work will investigate the links between this ability and neurodevelopmental disorders.

Epigenetic Modifications Following Noxious Stimuli in Infants

Purpose:

To recruit healthy full- and preterm infants into genetic research and determine the effectiveness of a noninvasive DNA sampling technique for comparing epigenetic modifications.

Background:

Noxious stimuli during a vulnerable period of infant neuronal plasticity may trigger long-term epigenetic changes affecting neurodevelopment, pain modulation, and reactivity. Recognizing epigenetic pain findings is problematic because parents are reluctant to enroll newborns into genetic research.

Methods:

Design: Within-subject change over time candidate-gene DNA methylation association study. Setting/ sample: Urban teaching hospital’s neonatal intensive care unit and newborn nursery. Convenience sample of healthy full- (>37 weeks, n = 6) and preterm (<37 weeks, n = 6) infants. Procedure: Parents participated in a genetic presentation prior to informed consent. Infant buccal saliva was collected after admission to the unit and prior to discharge. Analysis: The methylation pattern at the 5′ end of µ-opioid receptor gene ( OPRM1) was examined. DNA was treated with bisulfite to convert all cytosines to uracil residues, leaving methylated cytosines unchanged. Sequencing of untreated and bisulfite-converted DNA was carried out. The sequences of unconverted and bisulfite-converted DNA were aligned with ClustalW, fidelity of the polymerase chain reaction and the sequencing reaction evaluated, and the methylation pattern identified.

Results:

Recruitment and assessment of a noninvasive DNA sampling technique for comparing epigenetic modifications were successful; however, infant stress did not produce a change in OPRM1 methylation expression.

Relevance:

This study established the feasibility of recruiting healthy full-term infants into genetic research and the effectiveness of noninvasive DNA sampling for comparing epigenetic modification in infants.

Self-reported Chronic Pain in Young Adults With a Low Birth Weight

OBJECTIVE

To investigate self-reported pain in young adults with a low birth weight.

MATERIALS AND METHODS

This study was a part of a long-term follow-up study of preterm very low birth weight (VLBW; birth weight ≤1500 g), term small for gestational age (SGA; birth weight <10th percentile adjusted for sex and parity), and control young adults born during 1986 to 1988. Of the 300 individuals invited, 216 (62 VLBW, 67 term SGA, and 87 controls) completed a pain questionnaire. Of these, 151 (70%) had answered a pain severity question at 19 years. Chronic pain was defined as pain lasting for >6 months and being moderate, severe, or very severe during the past 4 weeks.

RESULTS

The prevalence of chronic pain at 26 years was 16% in the VLBW group, 21% in the term SGA group, and 7% in the control group. The VLBW and the term SGA groups had higher odds ratios for chronic pain (crude OR, 2.6; 95% CI, 0.9-7.6 for the VLBW group and crude OR, 3.6; 95% CI, 1.3-9.9 for the term SGA group vs. controls). The main results remained after adjusting for potential confounding factors. Some attenuation was observed when adjusting for anxiety and depressive problems. Moderate to very severe pain increased from 16% to 41% in the term SGA group from 19 to 26 years, whereas less changes were seen in the VLBW and the control groups.

DISCUSSION

Results of our study imply that pain should be in focus when conducting long-term follow-up programs of individuals with a low birth weight.

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.

Counseling parents at risk of delivery of an extremely premature infant: Differing strategies

BACKGROUND

It is not known how neonatologists address the affective and cognitive loads on parents deciding whether to resuscitate infants born extremely preterm. This study explores expert neonatologists' views on these decision-making processes and their own roles in counseling parents.

METHODS

Semistructured interviews asked internationally recognized experts to share their perspectives on perinatal consultations. Their responses were subjected to thematic analysis.

RESULTS

Eighteen of 22 invited experts participated. Approximately equal numbers reported employing a physician-driven approach, a parent-driven approach, and a combined approach during these consultations. Those who followed a physician-driven approach typically focused on conveying standard information about adverse outcomes. Those who followed a parent-driven approach typically focused on addressing parents' information requests, guiding their decision making, and providing affective support. Nearly all experts, in each group, endorsed addressing the child's quality of life, in terms of functionality, when discussing long-term outcomes. Although many believed that families adjusted to life with a disabled child, few discussed the topic during prenatal consultations. Most, in each group, reported trying to alleviate future "decisional regret" for parents whose premature infants subsequently became disabled. None spoke to parents about possible decisional regret after deciding to forgo resuscitation.

CONCLUSIONS

Expert neonatologists are deeply concerned that parents understand the decision facing them. However, they differ on what information they offer and how they balance parents' need for cognitive and affective support. They expressed more concern about parents' decisional regret should their child survive resuscitation, but have severe disability, than about decisional regret after foregoing resuscitation.