Prospectively assessed neurodevelopmental outcomes in studies of anaesthetic neurotoxicity in children: a systematic review and meta-analysis

The lateral septum partakes the regulation of propofol-induced anxiety-like behavior

Repeated exposure to propofol during early brain development is associated with anxiety disorders in adulthood, yet the mechanisms underlying propofol-induced susceptibility to anxiety disorders remain elusive. The lateral septum (LS), primarily composed of γ-aminobutyric acidergic (GABAergic) neurons, serves as a key brain region in the regulation of anxiety. However, it remains unclear whether LS GABAergic neurons are implicated in propofol-induced anxiety. Therefore, we conducted c-Fos immunostaining of whole-brain slices from mice exposed to propofol during early life. Our findings indicate that propofol exposure activates GABAergic neurons in the LS. Selective activation of LS GABAergic neurons resulted in increased anxiety-like behavior, while selective inhibition of these neurons reduced such behaviors. These results suggest that the LS is a critical brain region involved in propofol-induced anxiety. Furthermore, we investigated the molecular mechanism of propofol-induced anxiety in the LS. Microglia activation underlies the development of anxiety. Immunofluorescence staining and Western blot analysis of LS revealed activated microglia and significantly elevated levels of phospho-NF-κB p65 protein. Additionally, a decrease in the number of neuronal spines was observed. Our study highlights the crucial role of the LS in the development of anxiety-like behavior in adulthood following childhood propofol exposure, accompanied by the activation of inflammatory pathways.

Effects of general anaesthesia in early childhood on local and global visual processing: a post hoc analysis of the APEX cohort study

BACKGROUND

Preclinical studies suggest that early exposure to anaesthesia alters the visual system in mice and non-human primates. We investigated whether exposure to general anaesthesia leads to visual attention processing changes in children, which could potentially impact essential life skills, including learning.

METHODS

This was a post hoc analysis of data from the APprentissages EXécutifs et cerveau chez les enfants d'âge scolaire (APEX) cohort study. A total of 24 healthy 9-10-yr-old children who were or were not exposed to general anaesthesia (for surgery) by a mean age of 3.8 (2.6) yr performed a visual attention task to evaluate ability to process either local details or general global visual information. Whether children were distracted by visual interference during global and local information processing was also assessed.

RESULTS

Participants included in the analyses (n=12 participants exposed to general anaesthesia and n=12 controls) successfully completed (>90% of correct answers) the trial tasks. Children from both groups were equally distracted by visual interference. However, children who had been exposed to general anaesthesia were more attracted to global visual information than were control children (P=0.03).

CONCLUSIONS

These findings suggest lasting effects of early-life exposure to general anaesthesia on visuospatial abilities. Further investigations of the mechanisms by which general anaesthesia could have delayed effects on how children perceive their visual environment are needed.

Identification of differential m6A RNA methylomes and ALKBH5 as a potential prevention target in the developmental neurotoxicity induced by multiple sevoflurane exposures

Sevoflurane, as a commonly used inhaled anesthetic for pediatric patients, has been reported that multiple sevoflurane exposures are associated with a greater risk of developing neurocognitive disorder. N6-Methyladenosine (m6A), as the most common mRNA modification in eukaryotes, has emerged as a crucial regulator of brain function in processes involving synaptic plasticity, learning and memory, and neurodevelopment. Nevertheless, the relevance of m6A RNA methylation in the multiple sevoflurane exposure-induced developmental neurotoxicity remains mostly elusive. Herein, we evaluated the genome-wide m6A RNA modification and gene expression in hippocampus of mice that received with multiple sevoflurane exposures using m6A-sequencing (m6A-seq) and RNA-sequencing (RNA-seq). We discovered 19 genes with differences in the m6A methylated modification and differential expression in the hippocampus. Among these genes, we determined that a total of nine differential expressed genes may be closely associated with the occurrence of developmental neurotoxicity induced by multiple sevoflurane exposures. We further found that the alkB homolog 5 (ALKBH5), but not methyltransferase-like 3 (METTL3) and Wilms tumor 1-associated protein (WTAP), were increased in the hippocampus of mice that received with multiple sevoflurane exposures. And the IOX1, as an inhibitor of ALKBH5, significantly improved the learning and memory defects and reduced neuronal damage in the hippocampus of mice induced by multiple sevoflurane exposures. The current study revealed the role of m6A methylated modification and m6A-related regulators in sevoflurane-induced cognitive impairment, which might provide a novel insight into identifying biomarkers and therapeutic strategies for inhaled anesthetic-induced developmental neurotoxicity.

ADAR1 prevents ZBP1-dependent PANoptosis via A-to-I RNA editing in developmental sevoflurane neurotoxicity

It is well established that sevoflurane exposure leads to widespread neuronal cell death in the developing brain. Adenosine deaminase acting on RNA-1 (ADAR1) dependent adenosine-to-inosine (A-to-I) RNA editing is dynamically regulated throughout brain development. The current investigation is designed to interrogate the contributed role of ADAR1 in developmental sevoflurane neurotoxicity. Herein, we provide evidence to show that developmental sevoflurane priming triggers neuronal pyroptosis, apoptosis and necroptosis (PANoptosis), and elicits the release of inflammatory factors including IL-1β, IL-18, TNF-α and IFN-γ. Additionally, ADAR1-P150, but not ADAR1-P110, depresses cellular PANoptosis and inflammatory response by competing with Z-DNA/RNA binding protein 1 (ZBP1) for binding to Z-RNA in the presence of sevoflurane. Further investigation demonstrates that ADAR1-dependent A-to-I RNA editing mitigates developmental sevoflurane-induced neuronal PANoptosis. To restore RNA editing, we utilize adeno-associated virus (AAV) to deliver engineered circular ADAR-recruiting guide RNAs (cadRNAs) into cells, which is capable of recruiting endogenous adenosine deaminases to promote cellular A-to-I RNA editing. As anticipated, AAV-cadRNAs diminishes sevoflurane-induced cellular Z-RNA production and PANoptosis, which could be abolished by ADAR1-P150 shRNA transfection. Moreover, AAV-cadRNAs delivery ameliorates developmental sevoflurane-induced spatial and emotional cognitive deficits without influence on locomotor activity. Taken together, these results illustrate that ADAR1-P150 exhibits a prominent role in preventing ZBP1-dependent PANoptosis through A-to-I RNA editing in developmental sevoflurane neurotoxicity. Application of engineered cadRNAs to rectify the compromised ADAR1-dependent A-to-I RNA editing provides an inspiring direction for possible clinical preventions and therapeutics.

Zona incerta mediates early life isoflurane-induced fear memory deficits

The potential long-term effects of anesthesia on cognitive development, especially in neonates and infants, have raised concerns. However, our understanding of its underlying mechanisms and effective treatments is still limited. In this study, we found that early exposure to isoflurane (ISO) impaired fear memory retrieval, which was reversed by dexmedetomidine (DEX) pre-treatment. Measurement of c-fos expression revealed that ISO exposure significantly increased neuronal activation in the zona incerta (ZI). Fiber photometry recording showed that ZI neurons from ISO mice displayed enhanced calcium activity during retrieval of fear memory compared to the control group, while DEX treatment reduced this enhanced calcium activity. Chemogenetic inhibition of ZI neurons effectively rescued the impairments caused by ISO exposure. These findings suggest that the ZI may play a pivotal role in mediating the cognitive effects of anesthetics, offering a potential therapeutic target for preventing anesthesia-related cognitive impairments.

Integrated ribosome and proteome analyses reveal insights into sevoflurane-induced long-term social behavior and cognitive dysfunctions through ADNP inhibition in neonatal mice

A growing number of studies have demonstrated that repeated exposure to sevoflurane during development results in persistent social abnormalities and cognitive impairment. Davunetide, an active fragment of the activity-dependent neuroprotective protein (ADNP), has been implicated in social and cognitive protection. However, the potential of davunetide to attenuate social deficits following sevoflurane exposure and the underlying developmental mechanisms remain poorly understood. In this study, ribosome and proteome profiles were analyzed to investigate the molecular basis of sevoflurane-induced social deficits in neonatal mice. The neuropathological basis was also explored using Golgi staining, morphological analysis, western blotting, electrophysiological analysis, and behavioral analysis. Results indicated that ADNP was significantly down-regulated following developmental exposure to sevoflurane. In adulthood, anterior cingulate cortex (ACC) neurons exposed to sevoflurane exhibited a decrease in dendrite number, total dendrite length, and spine density. Furthermore, the expression levels of Homer, PSD95, synaptophysin, and vglut2 were significantly reduced in the sevoflurane group. Patch-clamp recordings indicated reductions in both the frequency and amplitude of miniature excitatory postsynaptic currents (mEPSCs). Notably, davunetide significantly ameliorated the synaptic defects, social behavior deficits, and cognitive impairments induced by sevoflurane. Mechanistic analysis revealed that loss of ADNP led to dysregulation of Ca 2+ activity via the Wnt/β-catenin signaling, resulting in decreased expression of synaptic proteins. Suppression of Wnt signaling was restored in the davunetide-treated group. Thus, ADNP was identified as a promising therapeutic target for the prevention and treatment of neurodevelopmental toxicity caused by general anesthetics. This study provides important insights into the mechanisms underlying social and cognitive disturbances caused by sevoflurane exposure in neonatal mice and elucidates the regulatory pathways involved.

Pediatric Anesthesia Exposure: Decoding Its Neurodevelopmental Implications and Navigating the Nuances

General anesthesia is fundamental in pediatric medical interventions, but its potential neurodevelopmental impact on children has raised concerns, necessitating a thorough investigation. This systematic review aimed to assess the association between pediatric anesthesia exposure and neurodevelopmental outcomes, focusing on dosage effects and identifying high-risk groups. The study involved an extensive literature search across PubMed, Medline, and Google Scholar, selecting 40 relevant studies from an initial pool of 2,000, based on inclusion criteria that focused on children under 18 years exposed to anesthesia, excluding those with major comorbidities or perioperative physiological insults. It was observed that while a single exposure to anesthesia had minimal impact on general neurodevelopment, repeated or prolonged exposures posed greater concerns. Despite these findings, the study identified gaps in certain areas like adaptive behavior and sensory cognition due to limited data. The conclusion drawn is that although the evidence on anesthesia-induced neurotoxicity in children remains inconclusive, the implications of pediatric anesthesia exposure are significant enough to warrant careful consideration by healthcare professionals, who should balance the procedural benefits against the risks. This study also calls for future research to standardize methodologies and employ consistent, validated neurodevelopmental measurement tools.

Risk of attention deficit hyperactivity disorder diagnosis following multiple exposures to general anesthesia in the paediatric population: A systematic review and meta-analysis

Objectives

The risk of attention deficit hyperactivity disorder (ADHD) following multiple exposures to anesthesia has been debated. Our objective was to systematically review the literature to examine the association between multiple exposures to general anesthesia before age 5 and subsequent diagnosis of ADHD.

Methods

A systematic search of EMBASE, PubMed, and SCOPUS was performed using key search terms in February 2022. We included studies that: were published after 1980, included only otherwise healthy children who experienced two or more exposures to general anesthetic before age 5, diagnosed ADHD by a medical professional before age 19 years after exposure to general anesthetic, were cross-sectional, case-control, or cohort study, and were published in English. The results (expressed as hazard ratios [HR] and associated 95% confidence intervals [CI]) were pooled using meta-analytic techniques. Studies which did not present their results as HR and 95% CI were analyzed separately. GRADE was used to determine the certainty of the findings. PRISMA guidelines were followed at each stage of the review.

Results

Eight studies (196,749 children) were included. Five reported HR and 95% CI and were subsequently pooled for meta-analysis. Multiple exposures to anesthesia were associated with diagnosis of ADHD before the 19th year of life (HR: 1.71; 95% CI: 1.59, 1.84). Two of the three studies not used in the meta-analysis also found an increased risk of ADHD diagnosis following multiple anesthetic exposures.

Conclusions

There was an association between multiple early exposures to general anesthesia and later diagnosis of ADHD.

Early-in-life isoflurane exposure alters resting-state functional connectivity in juvenile non-human primates

BACKGROUND

Clinical studies suggest that anaesthesia exposure early in life affects neurobehavioural development. We designed a non-human primate (NHP) study to evaluate cognitive, behavioural, and brain functional and structural alterations after isoflurane exposure during infancy. These NHPs displayed decreased close social behaviour and increased astrogliosis in specific brain regions, most notably in the amygdala. Here we hypothesise that resting-state functional connectivity MRI can detect alterations in connectivity of brain areas that relate to these social behaviours and astrogliosis.

METHODS

Imaging was performed in 2-yr-old NHPs under light anaesthesia, after early-in-life (postnatal days 6-12) exposure to 5 h of isoflurane either one or three times, or to room air. Brain images were segmented into 82 regions of interest; the amygdala and the posterior cingulate cortex were chosen for a seed-based resting-state functional connectivity MRI analysis.

RESULTS

We found differences between groups in resting-state functional connectivity of the amygdala and the auditory cortices, medial premotor cortex, and posterior cingulate cortex. There were also alterations in resting-state functional connectivity between the posterior cingulate cortex and secondary auditory, polar prefrontal, and temporal cortices, and the anterior insula. Relationships were identified between resting-state functional connectivity alterations and the decrease in close social behaviour and increased astrogliosis.

CONCLUSIONS

Early-in-life anaesthesia exposure in NHPs is associated with resting-state functional connectivity alterations of the amygdala and the posterior cingulate cortex with other brain regions, evident at the juvenile age of 2 yr. These changes in resting-state functional connectivity correlate with the decrease in close social behaviour and increased astrogliosis. Using resting-state functional connectivity MRI to study the neuronal underpinnings of early-in-life anaesthesia-induced behavioural alterations could facilitate development of a biomarker for anaesthesia-induced developmental neurotoxicity.

Needle in a haystack: localising the long-term neuronal changes from early-life exposure to general anaesthesia

Narrowing down the histopathological changes in the brain after early-life exposure to general anaesthesia has presented a consistent challenge for preclinical models of anaesthetic neurotoxicity. Using resting-state functional magnetic resonance imaging, in this issue of the journal Neudecker and colleagues demonstrated in vivo connectivity changes in the brain following a seed-based analysis that was derived from previously reported histopathology in the same animals. The combination of neurohistology and neuroimaging should help focus future preclinical studies investigating the developmental consequences of early exposure to general anaesthesia.

Unanswered questions of anesthesia neurotoxicity in the developing brain

PURPOSE OF REVIEW

This article reviews recent advances and controversies of developmental anesthesia neurotoxicity research with a special focus on the unanswered questions in the field both from clinical and preclinical perspectives.

RECENT FINDINGS

Observational cohort studies of prenatal and early childhood exposure to anesthesia have reported mixed evidence of an association with impaired neurodevelopment. Meta-analyses of currently available studies of early childhood exposure to anesthesia suggest that, while limited to no change in general intelligence can be detected, more subtle deficits in specific neurodevelopmental domains including behavior and executive function may be seen. Several studies have evaluated intraoperative blood pressure values and neurocognitive outcomes and have not found an association. Although many animal studies have been performed, taking into consideration other peri-operative exposures such as pain and inflammation may help with translation of results from animal models to humans.

SUMMARY

Advances have been made in the field of developmental anesthetic neurotoxicity over the past few years, including the recognition that anesthetic exposure is associated with deficits in certain cognitive domains but not others. Although the most important question of whether anesthetic agents actually cause long-term neurodevelopmental effects in children has still not been answered, results from recent studies will guide further studies necessary to inform clinical decision-making in children.

Perioperative management of infant inguinal hernia surgery; a review of the recent literature

Inguinal hernia surgery is one of the most common electively performed surgeries in infants. The common nature of inguinal hernia combined with the high-risk population involving a predominance of preterm infants makes this a particular area of interest for those concerned with their perioperative care. Despite a large volume of literature in the area of infant inguinal hernia surgery, there remains much debate amongst anesthetists, surgeons and neonatologists regarding the optimal perioperative management of these patients. The questions asked by clinicians include; when should the surgery occur, how should the surgery be performed (open or laparoscopic), how should the anesthesia be conducted, including regional versus general anesthesia and airway devices used, and what impact does anesthesia choice have on the developing brain? There is a paucity of evidence in the literature on the concerns, priorities or goals of the parents or caregivers but clearly their opinions do and should matter. In this article we review the current clinical surgical and anesthesia practice and evidence for infants undergoing inguinal hernia surgery to help clinicians answer these questions.

Early Neurodevelopmental Outcomes Following Exposure to General Anesthesia in Infancy: EGAIN, a Prospective Cohort Study

BACKGROUND

General anesthesia (GA) is known to worsen neural outcomes in animals, but human research assessing early-life GA exposure and neurodevelopment show inconsistent findings. We investigated the effects of a single GA exposure for minor surgery on the neurodevelopment of healthy children at multiple time-points, using clinical assessments along with behavioral and neurophysiological measures rarely used in human research.

METHODS

GA-exposed children were a prospective cohort of 250 full-term, healthy infants who underwent GA for minor surgery before 15 months. Nonexposed children were from a separate cohort of similar age, sex, ethnicity, and maternal education. In both cohorts, clinical measures (Bayley Scales of Infant and Toddler Development-III [BSID-III] and Child Behavior Checklist [CBCL1½-5]) were assessed at 24 months, and experimental tests (memory and attentional) and neurophysiology (event-related potentials) at 6 and 18 months.

RESULTS

At 24 months, there were no differences between GA-exposed and nonexposed children in the cognitive, language, motor, and socioemotional domains of the BSDI-III; however, GA-exposed children had poorer parental-reported scores in BSID-III general adaptability (94.2 vs. 99.0 [mean difference, 4.77; 97.3% confidence interval, -9.29, -0.24]; P =0.020) and poorer internalizing behavior scores on CBCL1½-5 (52.8 vs. 49.4 [mean difference, 3.35; 97.3% confidence interval, 0.15-6.55]; P =0.021). For experimental measures, GA-exposed children showed differences in 4 tests at 6 and 18 months.

CONCLUSIONS

GA-exposed children did not differ from unexposed children in cognitive, language or motor outcomes at 24 months, but exhibited poorer parent-reported behavior scores. Differences in infant behavior and neurophysiology were detected at 6 and 18 months. Neurophysiological assessments may complement clinically relevant assessments to provide greater insights into neurodevelopment following early GA exposure.

Anesthesia and Sedation Exposure and Neurodevelopmental Outcomes in Infants Undergoing Congenital Cardiac Surgery: A Retrospective Cohort Study

BACKGROUND

Children undergoing complex cardiac surgery are exposed to substantial cumulative doses of sedative medications and volatile anesthetics and are more frequently anesthetized with ketamine, compared with healthy children. This study hypothesized that greater exposure to sedation and anesthesia in this population is associated with lower neurodevelopmental scores at 18 months of age.

METHODS

A secondary analysis was conducted of infants with congenital heart disease who participated in a prospective observational study of environmental exposures and neurodevelopmental outcomes to assess the impact of cumulative volatile anesthetic agents and sedative medications. Cumulative minimum alveolar concentration hours of exposure to volatile anesthetic agents and all operating room and intensive care unit exposures to sedative and anesthesia medications were collected before administration of Bayley Scales of Infant and Toddler Development, 3rd edition (Bayley III), at 18 months of age.

RESULTS

The study cohort included 41 (37%) single-ventricle and 69 (63%) two-ventricle patients. Exposures to volatile anesthetic agents, opioids, benzodiazepines, and dexmedetomidine were not associated with abnormal Bayley III scores. At 18-month follow-up, after adjusting for confounders, each mg/kg increase in ketamine exposure was associated with a 0.34 (95% CI, -0.64 to -0.05) point decrease in Bayley III motor scores (P = 0.024).

CONCLUSIONS

Total cumulative exposures to volatile anesthetic agents were not associated with neurodevelopmental impairment in infants with congenital heart disease undergoing various imaging studies and procedures, whereas higher ketamine doses were associated with poorer motor performance.

EDITOR’S PERSPECTIVE

Behavioral and Cognitive Outcomes of Rhesus Macaques Following Neonatal Exposure to Antiseizure Medications

OBJECTIVE

Exposure of neonatal macaques to the antiseizure medications phenobarbital and midazolam (PbM) causes widespread apoptotic death of neurons and oligodendrocytes. We studied behavior and neurocognitive performance in 12 to 24 month-old macaques treated as neonates with PbM.

METHODS

A total of 14 monkeys received phenobarbital and midazolam over 24 hours under normothermia (n = 8) or mild hypothermia (n = 6). Controls (n = 8) received no treatment. Animals underwent testing in the human intruder paradigm at ages 12 and 18 months, and a 3-step stimulus discrimination task at ages 12, 18, and 24 months.

RESULTS

Animals treated with PbM displayed lower scores for environmental exploration, and higher scores for locomotion and vocalizations compared with controls. Combined PbM and hypothermia resulted in lower scores for aggression and vigilance at 12 months compared with controls and normothermic PbM animals. A mixed-effects generalized linear model was used to test for differences in neurocognitive performance between the control and PbM groups in the first step of the stimulus discrimination task battery (shape center baited to shape center non-baited). The odds of passing this step differed by group (p = 0.044). At any given age, the odds of passing for a control animal were 9.53-fold (95% CI 1.06-85) the odds for a PbM animal. There was also evidence suggesting a higher learning rate in the shape center non-baited for the control relative to the PbM group (Cox model HR 2.13, 95% CI 1.02-4.43; p = 0.044).

INTERPRETATION

These findings demonstrate that a 24-hour-long neonatal treatment with a clinically relevant combination of antiseizure medications can have long-lasting effects on behavior and cognition in nonhuman primates. ANN NEUROL 2023.

First anesthesia exposure effects on short-term neurocognitive function among 1- to 36-month-old children: a case-control pilot study

Background

Multiple human studies have shown no significant long-term results of anesthesia exposure during early childhood compared to the general population; however, reports on short-term neurodevelopmental assessment before and after anesthesia exposure are limited. This study aimed to evaluate the short-term characteristics of neurocognitive function post-anesthesia in noncardiac surgery compared with baseline.

Methods

This prospective case-control pilot study recruited healthy participants in the control group and hospitalized children in the anesthesia group. Children aged 1-36 months without previous anesthesia were included. Neurocognitive function was assessed at baseline and seven days after anesthesia administration using a cognitive scale of the Bayley Scales of Infant and Toddler Development, third edition. The control group received only a baseline assessment. The cognitive composite score had a mean of 100 and a standard deviation (SD) of 15, with a difference of score >1/3 SD (5 points) defined as clinically significant.

Results

Twenty and 39 participants in the control and anesthesia groups, respectively, were included in the final analysis. The baseline cognitive scale score of the anesthesia group was statistically and clinically lower than that of the control group. The mean (SD) cognitive composite scores in the control and anesthesia group were 111.50 (11.71) and 97.13 (9.88), P<0.001. The mean difference [95% confidence interval (CI)] was -14.37 (-8.28 to -20.47). In the anesthesia group, the post-anesthesia cognitive composite score was statistically higher than that at baseline, but without clinical significance. The mean (SD) of baseline and post-anesthesia cognitive composite scores were 97.05 (9.85) and 101.28 (10.87), P=0.039, respectively. The mean difference (95% CI) was 4.23 (0.23-8.23). However, 7 (17.9%) participants had decreased cognitive composite scores after anesthesia exposure.

Conclusions

Children in the anesthesia group had lower baseline cognitive composite scores than those in the control group. The post-anesthesia cognitive score did not decrease compared with the baseline assessment. Anesthetic exposure resulted in a decline in the cognitive composite score in 17.9% of the participants.

The effects of general anesthetics on mitochondrial structure and function in the developing brain

The use of general anesthetics in modern clinical practice is commonly regarded as safe for healthy individuals, but exposures at the extreme ends of the age spectrum have been linked to chronic cognitive impairments and persistent functional and structural alterations to the nervous system. The accumulation of evidence at both the epidemiological and experimental level prompted the addition of a warning label to inhaled anesthetics by the Food and Drug Administration cautioning their use in children under 3  years of age. Though the mechanism by which anesthetics may induce these detrimental changes remains to be fully elucidated, increasing evidence implicates mitochondria as a potential primary target of anesthetic damage, meditating many of the associated neurotoxic effects. Along with their commonly cited role in energy production via oxidative phosphorylation, mitochondria also play a central role in other critical cellular processes including calcium buffering, cell death pathways, and metabolite synthesis. In addition to meeting their immense energy demands, neurons are particularly dependent on the proper function and spatial organization of mitochondria to mediate specialized functions including neurotransmitter trafficking and release. Mitochondrial dependence is further highlighted in the developing brain, requiring spatiotemporally complex and metabolically expensive processes such as neurogenesis, synaptogenesis, and synaptic pruning, making the consequence of functional alterations potentially impactful. To this end, we explore and summarize the current mechanistic understanding of the effects of anesthetic exposure on mitochondria in the developing nervous system. We will specifically focus on the impact of anesthetic agents on mitochondrial dynamics, apoptosis, bioenergetics, stress pathways, and redox homeostasis. In addition, we will highlight critical knowledge gaps, pertinent challenges, and potential therapeutic targets warranting future exploration to guide mechanistic and outcomes research.

Anesthesia, the developing brain, and dexmedetomidine for neuroprotection

Anesthesia-induced neurotoxicity is a set of unfavorable adverse effects on central or peripheral nervous systems associated with administration of anesthesia. Several animal model studies from the early 2000's, from rodents to non-human primates, have shown that general anesthetics cause neuroapoptosis and impairment in neurodevelopment. It has been difficult to translate this evidence to clinical practice. However, some studies suggest lasting behavioral effects in humans due to early anesthesia exposure. Dexmedetomidine is a sedative and analgesic with agonist activities on the alpha-2 (ɑ₂) adrenoceptors as well as imidazoline type 2 (I2) receptors, allowing it to affect intracellular signaling and modulate cellular processes. In addition to being easily delivered, distributed, and eliminated from the body, dexmedetomidine stands out for its ability to offer neuroprotection against apoptosis, ischemia, and inflammation while preserving neuroplasticity, as demonstrated through many animal studies. This property puts dexmedetomidine in the unique position as an anesthetic that may circumvent the neurotoxicity potentially associated with anesthesia.

Early-life propofol exposure does not affect later-life GABAergic inhibition, seizure induction, or social behavior

The early developing brain is especially vulnerable to anesthesia, which can result in long lasting functional changes. We examined the effects of early-life propofol on adult excitatory-inhibitory balance and behavior. Postnatal day 7 male mice were exposed to propofol (250 mg/kg i.p.) and anesthesia was maintained for 2 h; control mice were given the same volume of isotonic saline and treated identically. The behavior and electrophysiology experiments were conducted when the mice were adults. We found that a 2-h neonatal propofol exposure did not significantly reduce paired pulse inhibition, alter the effect of muscimol (3 µM) to inhibit field excitatory postsynaptic potentials or alter the effect of bicuculline (100 µM) to increase the population spike in the CA1 region of hippocampal slices from adult mice. Neonatal propofol did not alter the evoked seizure response to pentylenetetrazol in adult mice. Neonatal propofol did not affect anxiety, as measured in the open field apparatus, depression-like behavior, as measured by the forced swim test, or social interactions with novel mice, in either the three-chamber or reciprocal social tests. These results were different from those with neonatal sevoflurane which demonstrated reduced adult GABAergic inhibition, increased seizure susceptibility and reduced social interaction. Even though sevoflurane and propofol both prominently enhance GABA inhibition, they have unique properties that alter the long-term effects of early-life exposure. These results indicate that clinical studies grouping several general anesthetic agents in a single group should be interpreted with great caution when examining long-term effects.

Multiple General Anesthesia in Children: A Systematic Review of Its Effect on Neurodevelopment

The effect of multiple general anesthesia (mGA) procedures administered in early life is a critical theme and has led the Food and Drug Administration (FDA) to issue an alert. This systematic review seeks to explore the potential effects on neurodevelopment of mGA on patients under 4 years. The Medline, Embase and Web of Science databases were searched for publications up to 31 March 2021. The databases were searched for publications regarding "children multiple general anesthesia OR pediatric multiple general anesthesia". Case reports, animal studies and expert opinions were excluded. Systematic reviews were not included, but they were screened to identify any possible additional information. A total of 3156 studies were identified. After removing the duplicates, screening the remaining records and analyzing the systematic reviews' bibliography, 10 studies were considered suitable for inclusion. Comprehensively, a total cohort of 264.759 unexposed children and 11.027 exposed children were assessed for neurodevelopmental outcomes. Only one paper did not find any statistically significant difference between exposed and unexposed children in terms of neurodevelopmental alterations. Controlled studies on mGA administered before 4 years of age support that there might be a greater risk of neurodevelopmental delay in children receiving mGA, warranting the need for careful risk/benefit considerations.

Electroencephalographic delta and alpha oscillations reveal phase-amplitude coupling in paediatric patients undergoing sevoflurane-based general anaesthesia

BACKGROUND

Sevoflurane-induced anaesthesia generates frontal alpha oscillations as early as 6 months of age, whereas strong delta oscillations are present at birth. In adults, delta oscillations and alpha oscillations are coupled: the phase of delta waves modulates the amplitude of alpha oscillations in a phenomenon known as phase-amplitude coupling. We hypothesise that delta-alpha phase-amplitude coupling exists in young children and is a feature of sevoflurane-based general anaesthesia distinct from emergence after anaesthesia.

METHODS

Electroencephalographic data from 31 paediatric patients aged 10 months to 3 yr undergoing elective surgery with sevoflurane-based anaesthesia were analysed retrospectively. Delta-alpha phase-amplitude coupling was evaluated during maintenance of anaesthesia and during emergence.

RESULTS

Delta-alpha phase-amplitude coupling was observed in the study population. Strength of phase-amplitude coupling, represented by the delta-alpha mean amplitude vector, was greater during general anaesthesia than during emergence (Wilcoxon paired signed-rank test, Z=3.107, P=0.002). Frontal alpha amplitude during anaesthesia was not uniformly distributed across all delta phases. During general anaesthesia, alpha power was restricted to the positive phase of the delta wave (omnibus circular uniformity, general anaesthesia: P<0.001, mean phase: 114º; 99% confidence interval: 90º-139º; emergence: P=0.35, mean phase 181º, 99% confidence interval: 110º-253º).

CONCLUSIONS

Sevoflurane-based anaesthesia is associated with delta-alpha phase-amplitude coupling in paediatric patients. These findings improve our understanding of cortical dynamics in children undergoing general anaesthesia, which might improve paediatric intraoperative depth of anaesthesia monitoring techniques.

Transphyseal distal humeral separation in neonates: A case series

INTRODUCTION

Birth trauma is a rare condition. Typically, injury in neonates occurs as a result of obstetrical manipulation to allow delivery or from trauma sustained during a difficult passage through the birth canal. Transphyseal separation of the humerus is particularly rare. Diagnosis is not always straightforward and is prone to mistakes. There is a general consensus that the outcome is usually favorable. It is generally agreed that the fracture needs to be realigned, while the suggested methods in contention vary from a simple plaster cast to closed and even open reduction and percutaneous Kirschner wire fixation. The purpose of this study was to review our experience in treating transphyseal distal humeral separation in neonates to better define the diagnostic and therapeutic pathway.

METHODS

Ten consecutive cases of transphyseal distal humeral separation in neonates were treated at our institution between September 2008 and June 2021. All cases were reviewed and clinical data collected on birth injury risk factors, diagnostic workup, age at diagnosis and treatment, and type of treatment. Results of treatment and outcome were analyzed for time to fracture union, complications and clinical alignment, range of motion and residual pain at the latest follow-up.

RESULTS

Mean age at diagnosis was 4.2 days (range 0 to 9 days) and time between diagnosis and treatment varied from three to 26 h (average 15 h). Risk factors for birth injury were present in six patients. Four patients were initially treated with closed reduction and cast immobilization, all the other cases were treated with closed reduction and percutaneous pinning. Arthrography was performed at the time of treatment in six cases. Average follow-up was 37 months (range 12 to 120 months). At the latest follow-up, all fractures had healed with full range of motion. No clinical or radiographic deformity requiring repeated surgery or physeal damage was observed.

CONCLUSIONS

This rare lesion may occur both in the presence and in the absence of risk factors. Due to the rarity of the injury, misdiagnosis and delayed diagnosis are not uncommon. Treatment with closed reduction and percutaneous pin fixation is advisable and safe.

Analgesia and sedation in critically ill pediatric patients: an update from the recent guidelines and point of view

In the last decades, the advancement of knowledge in analgesia and sedation for critically ill pediatric patients has been conspicuous and relevant. Many recommendations have changed to ensure patients' comfort during their intensive care unit (ICU) stay and prevent and treat sedation-related complications, as well as improve functional recovery and clinical outcomes. The key aspects of the analgosedation management in pediatrics have been recently reviewed in two consensus-based documents. However, there remains a lot to be researched and understood. With this narrative review and authors' point of view, we aimed to summarize the new insights presented in these two documents to facilitate their interpretation and application in clinical practice, as well as to outline research priorities in the field.    Conclusion: With this narrative review and authors' point of view, we aimed to summarize the new insights presented in these two documents to facilitate their interpretation and application in clinical practice, as well as to outline research priorities in the field. What is Known: • Critically ill pediatric patients receiving intensive care required analgesia and sedation to attenuate painful and stressful stimuli. •Optimal management of analgosedation is a challenge often burdened with complications such as tolerance, iatrogenic withdrawal syndrome, delirium, and possible adverse outcomes. What is New: •The new insights on the analgosedation treatment for critically ill pediatric patients delineated in the recent guidelines are summarized to identify strategies for changes in clinical practice. •Research gaps and potential for quality improvement projects are also highlighted.

Neurodevelopmental outcomes after prenatal exposure to anaesthesia for maternal surgery: a propensity-score weighted bidirectional cohort study

Up to 1% of pregnant women undergo anaesthesia for non-obstetric surgery. This study investigated neurodevelopmental outcomes after prenatal anaesthesia for maternal surgery. A bidirectional cohort study of children born between 2001 and 2018 was performed: neurodevelopmental outcomes of children who had received prenatal anaesthesia for maternal surgery were prospectively compared with unexposed children, with exposure status being assessed retrospectively. Children exposed to anaesthesia for obstetric and fetal surgery were excluded. The primary outcome was the global executive composite of the behaviour rating inventory of executive function score. Our secondary outcomes were: total problems; internalising problems and externalising problems derived from the child behaviour checklist; psychiatric diagnoses; and learning disorders. In 90% of exposed children, there was a single mean (SD) antenatal anaesthesia exposure lasting 91(94) min. There was a broad spectrum of indications, with abdominal surgery being most frequent. Parents of 129 exposed (response rate 68%) and 453 unexposed (response rate 63%) children participated. There were no arguments for non-response bias. After propensity weighting, there were no statistically significant differences in primary outcome, with a weighted mean difference (95%CI) of exposed minus unexposed children of 1.9 (-0.4-4.2), p = 0.10; or any of the secondary outcomes. Sensitivity analyses confirmed the robustness. Exploratory analyses, however, showed significant differences in certain subgroups for the primary outcome, (e.g. for intra-abdominal surgery, exposure duration > 1 h) and some cognitive subdomains (e.g. working memory and attention). This bidirectional cohort study, the largest investigation on the subject to date, has found no evidence in the general population for an association between prenatal exposure to anaesthesia and impaired neurodevelopmental outcomes.

Consequences of General Anesthesia in Infancy on Behavior and Brain Structure

BACKGROUND

One in 7 children will need general anesthesia (GA) before the age of 3. Brain toxicity of anesthetics is controversial. Our objective was to clarify whether exposure of GA to the developing brain could lead to lasting behavioral and structural brain changes.

METHODS

A first study was performed in mice. The behaviors (fear conditioning, Y-maze, and actimetry) and brain anatomy (high-resolution magnetic resonance imaging) of 6- to 8-week-old Swiss mice exposed or not exposed to GA from 4 to 10 days old were evaluated. A second study was a complementary analysis from the preexisting APprentissages EXécutifs et cerveau chez les enfants d'âge scolaire (APEX) cohort to assess the replicability of our data in humans. The behaviors (behavior rating inventory of executive function, emotional control, and working memory score, Backward Digit Span, and Raven 36) and brain anatomy (high-resolution magnetic resonance imaging) were compared in 102 children 9 to 10 years of age exposed or not exposed to a single GA (surgery) during infancy.

RESULTS

The animal study revealed chronic exacerbated fear behavior in the adult mice (95% confidence interval [CI], 4-80; P = .03) exposed to postnatal GA; this was associated with an 11% (95% CI, 7.5-14.5) reduction of the periaqueductal gray matter (P = .046). The study in humans suggested lower emotional control (95% CI, 0.33-9.10; P = .06) and a 6.1% (95% CI, 4.3-7.8) reduction in the posterior part of the right inferior frontal gyrus (P = .019) in the children who had been exposed to a single GA procedure.

CONCLUSIONS

The preclinical and clinical findings of these independent studies suggest lasting effects of early life exposure to anesthetics on later emotional control behaviors and brain structures.

Usefulness of serum neurofilament light in the assessment of neurologic outcome in the pediatric population: a systematic literature review

Children undergoing general anesthesia and surgery in the early years of life are exposed to the possible neurotoxicity of anesthetic agents. Prospective studies have shown deficits in behavior, executive function, social communication, and motor function in children undergoing anesthesia and surgery. Different biomarkers of neuronal injury have been evaluated neuronal injury in the pediatric population, among which neurofilaments represent a significant advantage as they are proteins exclusively expressed in neuronal tissue. Our aim was to evaluate the utility of serum neurofilament light (NfL) as a prognostic biomarker of neuronal injury in the pediatric population. A literature search was performed on PubMed, Embase, and Cochrane Databases in November 2022 for studies concerning serum NfL in the pediatric population in addition to a neurological assessment. Inclusion criteria were as follows: (1) prospective or retrospective studies, (2) studies including pediatric population until the age of 18 years, (3) serum NfL sampling, and (4) evaluation of neurological outcome. Data collection regarding study design, pediatric age, serum NfL levels, and results for neurological assessment were extracted from each study. Four manuscripts met the inclusion criteria and evaluated the prognostic utility of serum NfL in neonatal encephalopathy in correlation with the neurodevelopmental outcome that was assessed by the Bayley Scales of Infant Development until the age of 2 years. Children with neonatal encephalopathy showed significantly higher serum NfL vs. healthy controls and high serum NfL levels predicted an adverse neurological outcome. The decrease of serum NfL to a nadir point between 10 and 15 years old reflects the brain growth in healthy controls. No studies were available in the perioperative period.  Conclusions: Serum NfL is a valuable biomarker in evaluating neuronal injury in the pediatric population. Further studies with perioperative serial sampling of serum NfL combined with standardized neurodevelopmental tests should be conducted to evaluate the neurotoxicity of anesthetic agents and monitor the effectiveness of specific neuroprotective strategies in pediatric patients undergoing anesthesia and surgery. What is Known: • Preclinical animal data have shown neurotoxicity of the anesthetic agents in the developing brain. • Data regarding anesthetic neurotoxicity in humans show limitations and no objective tools are available. What is New: • This systematic review showed that serum NfL is a valuable biomarker of neuronal injury in the pediatric population. • Perioperative use of serum NfL may be considered in future trials evaluating anesthetic neurotoxicity in the pediatric population and in monitoring neuroprotective strategies.

Memory Problems in Children With Congenital Heart Disease: A Narrative Review

INTRODUCTION

Care for congenital heart diseases (CHD) has improved significantly over the past several decades, and children with CHD are now surviving into adulthood. Cognitive and behavioral problems affect children with CHD more than healthy peers. A review of performance on neuropsychological memory tasks has not been reported. We aimed to summarize the published literature on memory problems in people with CHD.

METHODS

We searched Pubmed, Medline, and PsycINFO from January 1, 1986 to March 22, 2022 to reflect modern care for people with CHD. Our inclusion criteria were randomized controlled trials or observational studies that included children with CHD older than age 3 years, which reported the results of at least 1 neuropsychological test of memory in the CHD group. Our exclusion criteria were studies that included heart transplant recipients and studies that included children who required extracorporeal membrane oxygenation.

RESULTS

Thirty-one studies that met our inclusion criteria and avoided exclusion criteria were included in this review. Several studies reported deficits in the subdomains of short-term and long-term memory and visual and verbal memory, though we found substantial heterogeneity across studies. The most likely subdomain to be affected in children with CHD appears to be short-term visual memory.

CONCLUSIONS

There is likely an increased risk of memory problems for children and adults with CHD. We were unable to quantify the risk of memory problems due to the heterogeneity of published studies. Future research should make efforts to account for confounding variables and standardize outcome measures.

Impact of Anesthetic Exposures on the Neurocognitive Profiles of Pediatric Brain Tumor Survivors: A New Direction for Research and Multidisciplinary Collaboration

Primary brain tumors are the most commonly diagnosed solid tumors in children, and pediatric brain tumor survivors experience lasting, pervasive deficits of neurocognitive functioning. Repeated exposure to anesthetic drugs is a necessary component not only of surgical resection but also of multimodal cancer care for the youngest patients with brain tumors. The potential for anesthetic neurotoxicity to worsen neurocognitive outcomes in this vulnerable group, therefore, warrants our attention and further study through multi-disciplinary collaboration. This review discusses neurocognitive functioning in pediatric brain tumor survivors, highlighting the findings of a recent study of children with tumors of the posterior fossa which identified treatment-related risk factors for neurocognitive difficulties, with those undergoing multimodal therapies (eg, chemotherapy and irradiation) experiencing the greatest deficits compared with healthy controls. The role of anesthetic neurotoxicity in long-term outcomes among pediatric brain tumor survivors is also reviewed.

Z-DNA/RNA Binding Protein 1 Senses Mitochondrial DNA to Induce Receptor-Interacting Protein Kinase-3/Mixed Lineage Kinase Domain-Like-Driven Necroptosis in Developmental Sevoflurane Neurotoxicity

Developmental sevoflurane exposure leads to widespread neuronal cell death known as sevoflurane-induced neurotoxicity (SIN). Receptor-interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like (MLKL)-driven necroptosis plays an important role in cell fate. Previous research has shown that inhibition of RIPK1 activity alone did not attenuate SIN. Since RIPK3/MLKL signaling could also be activated by Z-DNA/RNA binding protein 1 (ZBP1), the present study was designed to investigate whether ZBP1-mediated and RIPK3/MLKL-driven necroptosis is involved in SIN through in vitro and in vivo experiments. We found that sevoflurane priming triggers neuronal cell death and LDH release in a time-dependent manner. The expression levels of RIPK1, RIPK3, ZBP1 and membrane phosphorylated MLKL were also dramatically enhanced in SIN. Intriguingly, knockdown of RIPK3, but not RIPK1, abolished MLKL-mediated neuronal necroptosis in SIN. Additionally, inhibition of RIPK3-mediated necroptosis with GSK'872, rather than inhibition of apoptosis with zVAD, significantly ameliorated SIN. Further investigation showed that sevoflurane treatment causes mitochondrial DNA (mtDNA) release into the cytosol. Accordingly, ZBP1 senses cytosolic mtDNA and consequently activates RIPK3/MLKL signaling. This conclusion was reinforced by the evidence that knockdown of ZBP1 or depleting mtDNA with ethidium bromide remarkably improved SIN. Finally, the administration of the RIPK3 inhibitor GSK'872 relieved sevoflurane-induced spatial and emotional disorders without influence on locomotor activity. Altogether, these results illustrate that ZBP1 senses cytosolic mtDNA to induce RIPK3/MLKL-driven necroptosis in SIN. Elucidating the role of necroptosis in SIN will provide new insights into understanding the mechanism of anesthetic exposure in the developing brain.

Neonatal exposures to sevoflurane in rhesus monkeys alter synaptic ultrastructure in later life

Repeated or prolonged early life exposure to anesthesia is neurotoxic in animals and associated with neurocognitive impairment in later life in humans. We used electron microscopy with unbiased stereological sampling to assess synaptic ultrastructure in dorsolateral prefrontal cortex (dlPFC) and hippocampal CA1 of female and male rhesus monkeys, four years after three 4-h exposures to sevoflurane during the first five postnatal weeks. This allowed us to ascertain long-term consequences of anesthesia exposure without confounding effects of surgery or illness. Synapse areas were reduced in the largest synapses in CA1 and dlPFC, predominantly in perforated spinous synapses in CA1 and nonperforated spinous synapses in dlPFC. Mitochondrial morphology and localization changed subtly in both areas. Synapse areas in CA1 correlated with response to a mild social stressor. Thus, exposure to anesthesia in infancy can cause long-term ultrastructural changes in primates, which may be substrates for long-term alterations in synaptic transmission and behavioral deficits.

Did Age at Surgery Influence Outcome in Patients With Hirschsprung Disease? A Nationwide Cohort Study in the Netherlands

OBJECTIVES

Hirschsprung disease (HD) requires surgical resection of affected bowel, but the current evidence is inconclusive regarding the optimal age for resection. The aim of this study was to assess whether age at resection of the aganglionic segment is a determinant for surgical outcomes.

METHODS

A cross-sectional cohort study was done including all consecutive patients with HD between 1957 and 2015, aged 8 years or older (n = 830), who were treated in 1 of the 6 pediatric surgical centers in the Netherlands. Outcome measures were mortality, postoperative complications, stoma rate and redo surgery rate, retrieved from the medical records. Additionally, constipation and fecal incontinence rate in long term were assessed with the Defecation and Continence Questionnaire (DeFeC and P-DeFeC).

RESULTS

The medical records of 830 patients were reviewed, and 346 of the 619 eligible patients responded to the follow-up questionnaires (56%). There was a small increase in the risk of a permanent stoma [odds ratio (OR) 1.01 (95% confidence interval {CI}: 1.00-1.02); P = 0.019] and a temporary stoma [OR 1.01 (95% CI: 1.00-1.01); P = 0.022] with increasing age at surgery, regardless of the length of the aganglionic segment and operation technique. Both adjusted and unadjusted for operation technique, length of disease, and temporary stoma, age at surgery was not associated with the probability and the severity of constipation and fecal incontinence in long term.

CONCLUSIONS

In this study, we found no evidence that the age at surgery influences surgical outcomes, thus no optimal timing for surgery for HD could be determined.

General anesthesia in children and long-term neurodevelopmental deficits: A systematic review

Background

Millions of children experienced surgery procedures requiring general anesthesia (GA). Any potential neurodevelopmental risks of pediatric anesthesia can be a serious public health issue. Various animal studies have provided evidence that commonly used GA induced a variety of morphofunctional alterations in the developing brain of juvenile animals.

Methods

We conducted a systematic review to provide a brief overview of preclinical studies and summarize the existing clinical studies. Comprehensive literature searches of PubMed, EMBASE, CINAHL, OVID Medline, Web of Science, and the Cochrane Library were conducted using the relevant search terms “general anesthesia,” “neurocognitive outcome,” and “children.” We included studies investigating children who were exposed to single or multiple GA before 18, with long-term neurodevelopment outcomes evaluated after the exposure(s).

Results

Seventy-two clinical studies originating from 18 different countries published from 2000 to 2022 are included in this review, most of which are retrospective studies (n = 58). Two-thirds of studies (n = 48) provide evidence of negative neurocognitive effects after GA exposure in children. Neurodevelopmental outcomes are categorized into six domains: academics/achievement, cognition, development/behavior, diagnosis, brain studies, and others. Most studies focusing on children &lt;7 years detected adverse neurocognitive effects following GA exposure, but not all studies consistently supported the prevailing view that younger children were at greater risk than senior ones. More times and longer duration of exposures to GA, and major surgeries may indicate a higher risk of negative outcomes.

Conclusion

Based on current studies, it is necessary to endeavor to limit the duration and numbers of anesthesia and the dose of anesthetic agents. For future studies, we require cohort studies with rich sources of data and appropriate outcome measures, and carefully designed and adequately powered clinical trials testing plausible interventions in relevant patient populations.

PP2A-associated tau hyperphosphorylation was involved in sevoflurane induced neonatal neurotoxicity

BACKGROUND

The effects of sevoflurane anesthesia on childhood neurodevelopment and adult brain function have attracted increasing scientific attentions. However, the exact mechanisms underlying hyperphosphorylation of tau protein in sevoflurane induced abnormalities in central nervous system (CNS) development, particularly in the hippocampus, have not been fully determined.

METHODS

We utilized molecular biological and behavioral approaches to compare the changes in cognitive function in mice exposed to repeated sevoflurane during the neonatal stage, and to assess whether PP2A-associated tau hyperphosphorylation is involved in sevoflurane induced neonatal neurotoxicity.

RESULTS

We reported that mice anesthetized with repeated sevoflurane during the neonatal period caused cognitive dysfunction during the adulthood. More importantly, we found that hyperphosphorylation of tau protein and decreased level of protein phosphatase 2A (PP2A) were detected in the hippocampus of mice after neonatal exposure of sevoflurane. Meanwhile, GSK-3β activity was found to be increased with repeated sevoflurane exposure, but not for more than 2 weeks.

CONCLUSION

Our results suggest that PP2A-associated hyperphosphorylation of tau protein might contribute to sevoflurane induced developmental neurotoxicity. These findings could provide a theoretical basis for the safely usage of sevoflurane in pediatric surgeries, and offer a valuable reference and potential therapeutic targets for the development of neuroprotective drugs.

The impact of early exposure to general anesthesia on visual and neurocognitive development

Every year millions of children are exposed to general anesthesia while undergoing surgical and diagnostic procedures. In the field of ophthalmology, 44,000 children are exposed to general anesthesia annually for strabismus surgery alone. While it is clear that general anesthesia is necessary for sedation and pain minimization during surgical procedures, the possibility of neurotoxic impairments from its exposure is of concern. In animals there is strong evidence linking early anesthesia exposure to abnormal neural development. but in humans the effects of anesthesia are debated. In humans many aspects of vision develop within the first year of life, making the visual system vulnerable to early adverse experiences and potentially vulnerable to early exposure to general anesthesia. We attempt to address whether the visual system is affected by early postnatal exposure to general anesthesia. We first summarize key mechanisms that could account for the neurotoxic effects of general anesthesia on the developing brain and review existing literature on the effects of early anesthesia exposure on the visual system in both animals and humans and on neurocognitive development in humans. Finally, we conclude by proposing future directions for research that could address unanswered questions regarding the impact of general anesthesia on visual development.

Integrated Excitatory/Inhibitory Imbalance and Transcriptomic Analysis Reveals the Association between Dysregulated Synaptic Genes and Anesthetic-Induced Cognitive Dysfunction

Emerging evidence from human epidemiologic and animal studies has demonstrated that developmental anesthesia neurotoxicity could cause long-term cognitive deficits and behavioral problems. However, the underlying mechanisms remain largely unknown. We conducted an electrophysiological analysis of synapse activity and a transcriptomic assay of 24,881 mRNA expression on hippocampal tissues from postnatal day 60 (P60) mice receiving propofol exposure at postnatal day 7 (P7). We found that developmentally propofol-exposed P60 mouse hippocampal neurons displayed an E/I imbalance, compared with control mice as evidenced by the decreased excitation and increased inhibition. We found that propofol exposure at P7 led to the abnormal expression of 317 mRNAs in the hippocampus of P60 mice, including 23 synapse-related genes. Various bioinformatic analyses revealed that these abnormally expressed synaptic genes were associated with the function and development of synapse activity and plasticity, E/I balance, behavior, and cognitive impairment. Our findings suggest that the altered E/I balance may constitute a mechanism for propofol-induced long-term impaired learning and memory in mice. The transcriptomic and bioinformatic analysis of these dysregulated genes related to synaptic function paves the way for development of therapeutic strategies against anesthetic neurodegeneration through the restoration of E/I balance and the modification of synaptic gene expression.

Long-term cognitive and behavioral outcomes following early exposure to general anesthetics

PURPOSE OF REVIEW

Nearly 100 clinical studies have been published evaluating neurodevelopmental outcomes in children following surgery and anesthesia. These studies have reported mixed results, likely attributable at least in part to significant heterogeneity in their study designs, types and numbers of exposures, patient populations evaluated, and most importantly, the outcomes that were assessed. This review aims to summarize the results from clinical studies evaluating behavioral outcomes in children exposed to surgery and anesthesia.

RECENT FINDINGS

Children with early exposure to surgery and anesthesia were found to have limited to no differences in intelligence when compared with unexposed children. However, several studies have reported more behavioral problems in children exposed to general anesthesia. An increased incidence of attention-deficit hyperactivity disorder has also been reported in anesthetic exposed children, particularly after multiple exposures.

SUMMARY

Nearly all clinical studies of anesthetic neurotoxicity are observational in nature, so the associations between anesthetic exposure and behavioral deficits cannot yet be directly attributed to the anesthetic medication. However, the finding of deficits in some neurodevelopmental domains and not others will help guide the selection of appropriate outcomes in future studies of anesthetic neurotoxicity that can further evaluate whether anesthetic medications have an impact on neurodevelopment in children.

Repeated ketamine anesthesia during neurodevelopment upregulates hippocampal activity and enhances drug reward in male mice

Early exposures to anesthetics can cause long-lasting changes in excitatory/inhibitory synaptic transmission (E/I imbalance), an important mechanism for neurodevelopmental disorders. Since E/I imbalance is also involved with addiction, we further investigated possible changes in addiction-related behaviors after multiple ketamine anesthesia in late postnatal mice. Postnatal day (PND) 16 mice received multiple ketamine anesthesia (35 mg kg^-1, 5 days), and behavioral changes were evaluated at PND28 and PND56. Although mice exposed to early anesthesia displayed normal behavioral sensitization, we found significant increases in conditioned place preference to both low-dose ketamine (20 mg kg^-1) and nicotine (0.5 mg kg^-1). By performing transcriptome analysis and whole-cell recordings in the hippocampus, a brain region involved with CPP, we also discovered enhanced neuronal excitability and E/I imbalance in CA1 pyramidal neurons. Interestingly, these changes were not found in female mice. Our results suggest that repeated ketamine anesthesia during neurodevelopment may influence drug reward behavior later in life.

Safety of general anaesthetics on the developing brain: are we there yet?

Thirty years ago, neurotoxicity induced by general anaesthetics in the developing brain of rodents was observed. In both laboratory-based and clinical studies, many conflicting results have been published over the years, with initial data confirming both histopathological and neurodevelopmental deleterious effects after exposure to general anaesthetics. In more recent years, animal studies using non-human primates and new human cohorts have identified some specific deleterious effects on neurocognition. A clearer pattern of neurotoxicity seems connected to exposure to repeated general anaesthesia. The biochemistry involved in this neurotoxicity has been explored, showing differential effects of anaesthetic drugs between the developing and developed brains. In this narrative review, we start with a comprehensive description of the initial concerning results that led to recommend that any non-essential surgery should be postponed after the age of 3 yr and that research into this subject should be stepped up. We then focus on the neurophysiology of the developing brain under general anaesthesia, explore the biochemistry of the observed neurotoxicity, before summarising the main scientific and clinical reports investigating this issue. We finally discuss the GAS trial, the importance of its results, and some potential limitations that should not undermine their clinical relevance. We finally suggest some key points that could be shared with parents, and a potential research path to investigate the biochemical effects of general anaesthesia, opening up perspectives to understand the neurocognitive effects of repetitive exposures, especially in at-risk children.

Nonapoptotic caspases in neural development and in anesthesia-induced neurotoxicity

Apoptosis, classically initiated by caspase pathway activation, plays a prominent role during normal brain development as well as in neurodegeneration. The noncanonical, nonlethal arm of the caspase pathway is evolutionarily conserved and has also been implicated in both processes, yet is relatively understudied. Dysregulated pathway activation during critical periods of neurodevelopment due to environmental neurotoxins or exposure to compounds such as anesthetics can have detrimental consequences for brain maturation and long-term effects on behavior. In this review, we discuss key molecular characteristics and roles of the noncanonical caspase pathway and how its dysregulation may adversely affect brain development. We highlight both genetic and environmental factors that regulate apoptotic and sublethal caspase responses and discuss potential interventions that target the noncanonical caspase pathway for developmental brain injuries.

Anesthetic Exposure During Childhood and Neurodevelopmental Outcomes: A Systematic Review and Meta-analysis

IMPORTANCE

Clinical studies of neurodevelopmental outcomes after anesthetic exposure have evaluated a range of outcomes with mixed results.

OBJECTIVE

To examine via meta-analyses the associations between exposure to general anesthesia and domain-specific neurodevelopmental outcomes in children.

DATA SOURCES

PubMed/MEDLINE, Embase, CINAHL, Web of Science and the Cochrane Library were searched from inception to August 31, 2021.

STUDY SELECTION

Inclusion criteria were exposures to procedures requiring general anesthesia at younger than 18 years and evaluation of long-term neurodevelopmental function after exposure. Studies lacking unexposed controls or focused on children with major underlying comorbidities were excluded.

DATA EXTRACTION AND SYNTHESIS

Extracted variables included effect size; hazard, risk, or odds ratio; number of exposures; procedure type; major comorbidities; age of exposure and assessment; presence of unexposed controls; and study design. Studies were independently reviewed by 2 coders, and review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data were pooled using a random-effects model.

MAIN OUTCOMES AND MEASURES

The main outcomes were standardized mean differences (SMD) for scores in the neurodevelopmental domains of academics, behavioral problems, cognition, executive function, general development, language, motor function, nonverbal reasoning, social cognition, and hazard and risk of neurodevelopmental disorder diagnoses.

RESULTS

A total of 31 studies contributed data for meta-analysis. For each of the assessed neurodevelopmental domains, the numbers of children evaluated ranged from 571 to 63 315 exposed and 802 to 311 610 unexposed. Children with any exposure (single or multiple) had significantly worse behavioral problems scores, indicating more behavioral problems (SMD, -0.10; 95% CI, -0.18 to -0.02; P = .02), and worse scores in academics (SMD, -0.07; 95% CI -0.12 to -0.01; P = .02), cognition (SMD, -0.03; 95% CI, -0.05 to 0.00; P = .03), executive function (SMD, -0.20; 95% CI, -0.32 to -0.09; P < .001), general development (SMD, -0.08; 95% CI, -0.13 to -0.02; P = .01), language (SMD, -0.08; 95% CI, -0.14 to -0.02; P = .01), motor function (SMD, -0.11; 95% CI, -0.21 to -0.02; P = .02), and nonverbal reasoning (SMD, -0.15; 95% CI, -0.27 to -0.02; P = .02). Higher incidences of neurodevelopmental disorder diagnoses were also reported (hazard ratio, 1.19; 95% CI, 1.09 to 1.30; P < .001; risk ratio, 1.81; 95% CI, 1.25 to 2.61; P = .002).

CONCLUSIONS AND RELEVANCE

These findings support the hypothesis that associations between anesthetic exposure during childhood and subsequent neurodevelopmental deficits differ based on neurodevelopmental domain.