General anesthetic neurotoxicity in the young: Mechanism and prevention

Perioperative impact of ultrasound-guided ilioinguinal and iliohypogastric nerve blocks in patients undergoing pelvic fracture surgery

Pelvic fractures present a severe and complex clinical challenge. This study aimed to compare ultrasound-guided ilioinguinal (IIN) and iliohypogastric nerve (IHN) blocks with conventional general anesthesia (GA) in patients undergoing internal fixation surgery for pelvic fractures. A retrospective analysis was conducted on 100 patients equally divided into ultrasound-guided and control groups. The study monitored hemodynamics, intraoperative anesthesia drug usage, postoperative pain levels, and the incidence of adverse reactions between the 2 groups. The ultrasound-guided group underwent ultrasound-guided IHN and IIN blocks combined with GA. The ultrasound-guided group exhibited significant advantages for hemodynamic measurements at specific time points, lower consumption of Propofol and Remifentanil, and reduced pain intensity across all evaluated time intervals (P < .05). The incidence rate of adverse reactions was significantly lower in the ultrasound group (P = .016). Ultrasound-guided anesthesia is a superior alternative to conventional GA for managing pelvic fractures through internal fixation surgery. It offers advantages in terms of hemodynamic stability, drug consumption, postoperative pain management, and adverse reaction reduction.

Impact of Repeated Infantile Exposure to Surgery and Anesthesia on Gut Microbiota and Anxiety Behaviors at Age 6-9

(1) Background: Preclinical as well as population studies have connected general anesthesia and surgery with a higher risk of abnormal cognitive development, including emotional development. Gut microbiota dysbiosis in neonatal rodents during the perioperative period has been reported, however, the relevance of this to human children who undergo multiple anesthesia for surgeries is unknown. Given the emerging role of altered gut microbes in propagating anxiety and depression, we sought to study whether repeated infantile exposures to surgery and anesthesia affect gut microbiota and anxiety behaviors later in life. (2) Methods: This is a retrospectively matched cohort study comparing 22 pediatric patients of less than 3 years of age with multiple exposures (≥3) to anesthesia for surgeries and 22 healthy controls with no history of exposure to anesthesia. The parent report version of the Spence Children's Anxiety Scale (SCAS-P) was applied to evaluate anxiety in children aged between 6 and 9 years old. Additionally, the gut microbiota profiles of the two groups were compared using 16S rRNA gene sequencing. (3) Results: In behavioral tests, the p-SCAS score of obsessive compulsive disorder and social phobia were significantly higher in children with repeated anesthesia exposure relative to the controls. There were no significant differences between the two groups with respect to panic attacks and agoraphobia, separation anxiety disorder, physical injury fears, generalized anxiety disorder, and the total SCAS-P scores. In the control group, 3 children out of 22 were found to have moderately elevated scores, but none of them had abnormally elevated scores. In the multiple-exposure group, 5 children out of 22 obtained moderately elevated scores, while 2 scored as abnormally elevated. However, no statistically significant differences were detected in the number of children with elevated and abnormally elevated scores. The data show that repeated anesthesia and surgical exposures in children led to long-lasting severe gut microbiota dysbiosis. (4) Conclusions: In this preliminary study, our findings demonstrated that early repeated exposures to anesthesia and surgical predisposes children to anxiety as well as long-term gut microbiota dysbiosis. We should confirm these findings in a larger data population size and with detailed analysis. However, the authors cannot confirm an association between the dysbiosis and anxiety.

Repeated neonatal isoflurane exposure facilitated stress-related fear extinction impairment in male mice and was associated with ΔFosB accumulation in the basolateral amygdala and the hippocampal dentate gyrus

Volatile anesthetics elicit neurodevelopmental toxicity in rodents and primates and lead to more exaggerated anxiety-like behavior in response to future stress. Anxiety and fear are closely correlated and maladaptive fear-associated learning is regarded as the core mechanism underlying anxiety-related disorders. However, little is known about the interaction between early-life anesthetic exposure and future stress and the accompanying effect on fear-associated learning. In the present study, we evaluated the alterations in fear-associated learning (fear acquisition and extinction) occurring in mice receiving repeated neonatal isoflurane exposure and chronic variable stress (CVS) successively through a series of fear conditioning, fear reinforcing, and fear extinction paradigms. The corticosterone (CORT) response during CVS and the immunohistochemical levels of ΔFosB and c-Fos expression in the basolateral amygdala (BLA) and the hippocampal dentate gyrus (DG) after the extinction retrieval test were also investigated. The results showed that neonatal isoflurane exposure could increase CORT levels following the first diurnal CVS procedure, but not after completion of the whole CVS paradigm. Neonatal isoflurane exposure exerted a repressive effect on fear acquisition, in contrast to that seen with CVS. Neonatal isoflurane exposure and CVS both exerted suppressive effects on fear extinction and there was a significant synergy between them. Furthermore, neonatal isoflurane exposure facilitated CVS-mediated ΔFosB accumulation in the BLA and the hippocampal DG, which may have been responsible for c-Fos expression deficits and fear extinction impairment. Collectively, these findings contribute to the understanding of the interaction between early-life anesthetic exposure and future stress, as well as the accompanying behavioral alterations.

Quantity and duration of exposure to general anesthesia for pediatric patients with retinoblastoma

PURPOSE

To quantify the duration of anesthesia required for optimal management of retinoblastoma (Rb), stratified by clinical factors.

METHODS

The medical records of Rb patients treated at Phoenix Children's Hospital between January 2011 and January 2022 were reviewed retrospectively. Demographic, tumor, and treatment data were collected. Anesthesia time was recorded for procedures requiring general anesthesia, including intra-arterial chemotherapy (IAC), enucleation, brainstem auditory evoked response testing (BAER), port placement, magnetic resonance imaging (MRI), and examination under anesthesia (EUA). Descriptive statistics were used to summarize patient and clinical characteristics.

RESULTS

Total anesthesia time was 48,991 minutes for 610 procedures in 43 patients. The median follow-up time was 36 months (range, 12-114 months). Average anesthetic durations per exposure were 274, 152, 81.8, 62.5, 60.7, and 45 minutes for IAC, enucleation, BAER, port placement, MRI, and EUA, respectively. Patients with bilateral Rb underwent a median of 1,659 minutes of total anesthesia, compared with 397 minutes for those with unilateral disease. In patients with unilateral Rb, median total anesthesia time was 2,651, 1681, 312, 397 minutes for International Classification of Retinoblastoma grades B, C, D, and E tumors, respectively. Patients who received IAC as their primary treatment had the highest median anesthesia duration (2,100 minutes), followed by systemic chemo (654 minutes) and enucleation (289 minutes).

CONCLUSIONS

Treatment of Rb requires prolonged and repeated exposure to general anesthesia. Future studies are required to determine the potential effects of these childhood anesthetic exposures.

Histone Deacetylase 2-Mediated Epigenetic Regulation is Involved in the Early Isoflurane Exposure-Related Increase in Susceptibility to Anxiety-Like Behaviour Evoked by Chronic Variable Stress in Mice

Increasing studies report that prolonged or multiple anaesthetic exposures early in life are associated with detrimental effects on brain function. Although studies have evaluated the detrimental effects on neurocognitive function, few have focused on long-term neuropsychiatric effects. In the present study, C57BL/6 mice received either three neonatal isoflurane exposures or control exposure. Starting on postnatal day 45, the mice were either exposed or not to a chronic variable stress (CVS) paradigm, and CVS-related neuropsychiatric performance was evaluated using a series of behavioural tests. The expression levels of histone 3 lysine 9 acetylation (acetyl-H3K9), brain-derived neurotrophic factor (BDNF), cAMP response element-binding protein-binding protein, and histone deacetylases 1-4 in the amygdala were measured by immunoblotting or immunohistochemistry analysis. In mice with neonatal isoflurane exposure, the effects of sodium butyrate (NaB), a commonly used HDAC inhibitor, were examined on CVS-related behavioural and molecular alterations. The results showed that repeated neonatal isoflurane exposure did not affect innate depression-like and anxiety-like behaviours under non-stress conditions but facilitated the CVS-induced anxiety-like behavioural phenotype. Increased HDAC2 expression in the amygdala was associated with an increase in the CVS-induced repression of acetyl-H3K9 and BDNF expression and an enhanced CVS-evoked anxiety-like behavioural phenotype in mice neonatal isoflurane exposure. NaB significantly decreased the CVS-induced anxiety level by elevating acetyl-H3K9 and BDNF expression. These results suggested that early anaesthesia exposure facilitated chronic stress-induced neuropsychiatric outcomes, and the HDAC2-related epigenetic dysregulation of BDNF gene expression is involved in the underlying mechanism.

Repeated Neonatal Isoflurane Exposure is Associated with Higher Susceptibility to Chronic Variable Stress-induced Behavioural and Neuro-inflammatory Alterations

Numerous studies have reported that prolonged or multiple exposures to anaesthetics in early life lead to detrimental effects on brain function, most having focused on neurocognitive function, and relatively few on long term neuropsychiatric performance. The present study investigated the impact of repeated neonatal isoflurane exposure on chronic variable stress (CVS)-induced psychiatric and behavioural outcomes together with CVS-related neuronal activity and neuro-inflammatory reactivity in relevant brain circuits. In the present study, C57BL/6J mice received either three exposures to isoflurane at postnatal days 7, 8, and 9 or a control exposure. From postnatal day 45, mice were exposed to a mild, 3-week, CVS paradigm or none and the CVS-related neuropsychiatric performance was evaluated using a series of behavioural tests. The neuronal activity in relevant brain regions was measured by ΔFosB immunopositivity and CVS-related neuroinflammation was assessed by analysing levels of pro-inflammatory cytokines IL-1α, IL-1β, IL-6, and TNF-α. In mice experiencing serial neonatal isoflurane exposure, we detected a significant enhancement in anxiety levels following CVS procedures, together with enhanced neuronal activity, and exacerbated neuroinflammation in the basolateral amygdaloid nuclei (BLA) and hippocampal dentate gyrus (DG) regions. No such change was found in control mice. These results indicate an association between early multiple isoflurane exposures in infant mice and susceptibility to a CVS-evoked anxious phenotype accompanied by enhanced neuronal activity in BLA and DG regions and high inflammatory reactivity in response to CVS.

Prenatal sevoflurane exposure causes neuronal excitatory/inhibitory imbalance in the prefrontal cortex and neurofunctional abnormality in rats

The balance of excitatory and inhibitory neurons in the central nervous system is critical for maintaining brain function and sevoflurane, a general anesthetic and an GABA receptor modulator, may change the balance of excitatory and inhibitory neurons in the cortex during early brain development. Herein, we investigated whether prenatal sevoflurane exposure (PSE) disturbs cortical neuronal development and brain function. Pregnant rats at the gestational day 14.5 were subjected to sevoflurane exposure at 3.0% for 3 h and their offspring were studied thereafter. We found a significant increase of parvalbumin-positive neurons, vesicular GABA transporter (VGAT) and GAD67 expression, and GABA neurotransmitter, and a significant decrease of vesicular glutamate transporter 1 (VGLUT1) expression and glutamate in the medial prefrontal cortex (mPFC) of offspring. Pyramidal neurons showed atrophy with shorter dendrites, less branches and lower spine density visualized by Golgi stain and a decrease of excitability with the increased miniature inhibitory postsynaptic current (mIPSC) frequency and amplitude, the decreased miniature excitatory postsynaptic current (mEPSC) frequency and excitation/inhibition (E/I) ratio using whole-cell recording in offspring. There was a significant increase of inhibitory synapse in the mPFC detected by electron microscopy. Furthermore, PSE animals showed hypo-excitatory phenotype including depression-like behaviors and learning deficits. Thus, our studies provide novel evidence that PSE causes the persisted imbalance of excitatory and inhibitory neurons in the mPFC, and this is very likely the mechanisms of the sevoflurane-induced brain functional abnormalities.

Research progress and treatment strategies for anesthetic neurotoxicity

Every year, a large number of infants and young children worldwide are administered general anesthesia. Whether general anesthesia adversely affects the intellectual development and cognitive function of children at a later date remains controversial. Many animal experiments have shown that general anesthetics can cause nerve damage during development, affect synaptic plasticity, and induce apoptosis, and finally affect learning and memory function in adulthood. The neurotoxicity of pediatric anesthetics (PAN) has received extensive attention in the field of anesthesia, which has been listed as a potential problem affecting public health by NFDA of the United States. Previous studies on rodents and non-human primates indicate that inhalation of anesthetics early after birth can induce long-term and sustained impairment of learning and memory function, as well as changes in brain function. Many anti-oxidant drugs, dexmedetomidine, as well as a rich living environment and exercise have been proven to reduce the neurotoxicity of anesthetics. In this paper, we summarize the research progress, molecular mechanisms and current intervention measures of anesthetic neurotoxicity.

Genistein attenuates cognitive deficits and neuroapoptosis in hippocampus induced by ketamine exposure in neonatal rats

Ketamine is a frequently used anesthetic in pediatric patients that can cause cognitive impairment. Genistein, a bioactive component of soy products, has been shown to suppress neuronal death through regulating the expression of apoptosis related genes. In this study, we hypothesized that genistein could alleviate ketamine-induced cognitive impairment by ameliorating hippocampal neuronal loss and tested this hypothesis in rats. Neonatal rats were treated with ketamine and genistein. Hippocampal tissue was harvested for histological and biochemical analysis to determine neuronal apoptosis and proteins involved in the apoptotic pathways. Behavioral assays including contextual fear conditioning test and Morris water maze test were performed to assess cognitive functions, including learning and memory. We found that in fear conditioning test, genistein restored freezing time in ketamine treated rats in a dose dependent manner. Similarly, genistein attenuated impaired learning and memory in Morris water maze test in rats treated with ketamine. Additionally, ketamine-induced neuronal apoptosis in rat hippocampus was attenuated by genistein treatment. Finally, we found that genistein partially restored proteins associated with apoptosis, including Bax, Bcl-2, cleaved caspase 3, and phosphorylated GSK-3ß and Akt. Genistein suppresses hippocampal neuronal loss and cognitive disruption induced by ketamine in rats.