Brain injury patterns in hypoxic ischemic encephalopathy of term neonates

Temporal dynamics of neonatal hypoxic-ischemic encephalopathy injuries on magnetic resonance imaging

Moderate to severe perinatal hypoxic-ischemic encephalopathy occurs in ~ 1 to 3/1000 live births in high-income countries and is associated with a significant risk of death or neurodevelopmental disability. Detailed assessment is important to help identify high-risk infants, to help families, and to support appropriate interventions. A wide range of monitoring tools is available to assess changes over time, including urine and blood biomarkers, neurological examination, and electroencephalography. At present, magnetic resonance imaging is unique as although it is expensive and not suited to monitoring the early evolution of hypoxic-ischemic encephalopathy by a week of life it can provide direct insight into the anatomical changes in the brain after hypoxic-ischemic encephalopathy and so offers strong prognostic information on the long-term outcome after hypoxic-ischemic encephalopathy. This review investigated the temporal dynamics of neonatal hypoxic-ischemic encephalopathy injuries, with a particular emphasis on exploring the correlation between the prognostic implications of magnetic resonance imaging scans in the first week of life and their relationship to long-term outcome prediction, particularly for infants treated with therapeutic hypothermia. A comprehensive literature search, from 2016 to 2024, identified 20 pertinent articles. This review highlights that while the optimal timing of magnetic resonance imaging scans is not clear, overall, it suggests that magnetic resonance imaging within the first week of life provides strong prognostic accuracy. Many challenges limit the timing consistency, particularly the need for intensive care and clinical monitoring. Conversely, although most reports examined the prognostic value of scans taken between 4 and 10 days after birth, there is evidence from small numbers of cases that, at times, brain injury may continue to evolve for weeks after birth. This suggests that in the future it will be important to explore a wider range of times after hypoxic-ischemic encephalopathy to fully understand the optimal timing for predicting long-term outcomes.

Proteomic analysis of hippocampus reveals metabolic reprogramming in a piglet model of mild hypoxic ischemic encephalopathy

Neonatal hypoxic-ischemic encephalopathy (HIE) remains a leading cause of long-term neurologic morbidity. Fifty percent of HIE cases are mild and do not have clearly defined therapeutic interventions. Emergent evidence now demonstrates that up to 25% of children with mild HIE suffer motor and developmental delay by 18 months and 35% have cognitive impairments by age 5 years. Interestingly, the hippocampus, which is responsible for learning and memory, does not show overt injury but does demonstrate volume changes on imaging that correlate with cognitive and behavioral outcomes. Although there is extensive data regarding pathophysiological changes following moderate and severe HIE, there is a paucity of understanding regarding the extent, duration, and compensatory adaptations in the mild neonatal HIE brain. We performed hippocampal proteomic analysis using a swine model of mild neonatal hypoxia-asphyxia. Hippocampi were collected at 24 or 72 hours after injury, and proteomics was performed by liquid chromatography tandem mass spectrometry (LC-MS/MS). Pathway analysis demonstrated that several metabolic pathways are temporally regulated after mild HIE. Specifically, amino acid, carbohydrate, and one-carbon metabolism increased at 24 hours while fat metabolism and oxidative phosphorylation decreased at 24 hours. Downregulation of oxidative phosphorylation was more pronounced at 72 hours. Our data demonstrate that metabolic reprogramming occurs after mild HIE, and these changes persist up to 72 hours after injury. These results provide new evidence that mild HIE disrupts brain metabolism, emphasizing the need for a better understanding of the underlying pathophysiology of mild HIE and development of targeted therapeutic interventions for this population.

Can miRNAs in MSCs-EVs Offer a Potential Treatment for Hypoxic-ischemic Encephalopathy?

Neonatal hypoxic-ischemic encephalopathy (HIE) is a critical condition resulting from impaired oxygen and blood flow to the brain during birth, leading to neuroinflammation, neuronal apoptosis, and long-term neurological deficits. Despite the use of therapeutic hypothermia, current treatments remain inadequate in fully preventing brain damage. Recent advances in mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) offer a novel, cell-free therapeutic approach, as these EVs can cross the blood-brain barrier (BBB) and deliver functional microRNAs (miRNAs) to modulate key pathways involved in inflammation and neuroprotection. This review examines how specific miRNAs encapsulated in MSC-EVs-including miR-21, miR-124, miR-146, and the miR-17-92 cluster-target the complex inflammatory responses that drive HIE pathology. By modulating pathways such as NF-κB, STAT3, and PI3K/Akt, these miRNAs influence neuroinflammatory processes, reduce neuronal apoptosis, and promote tissue repair. The aim is to assess the therapeutic potential of miRNA-loaded MSC-EVs in mitigating inflammation and neuronal damage, thus addressing the limitations of current therapies like therapeutic hypothermia.

The Importance of Including Maternal Immune Activation in Animal Models of Hypoxic-Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a perinatal brain injury that is the leading cause of cerebral palsy, developmental delay, and poor cognitive outcomes in children born at term, occurring in about 1.5 out of 1000 births. The only proven therapy for HIE is therapeutic hypothermia. However, despite this treatment, many children ultimately suffer disability, brain injury, and even death. Barriers to implementation including late diagnosis and lack of resources also lead to poorer outcomes. This demonstrates a critical need for additional treatments for HIE, and to facilitate this, we need translational models that accurately reflect risk factors and interactions present in HIE. Maternal or amniotic infection is a significant risk factor and possible cause of HIE in humans. Maternal immune activation (MIA) is a well-established model of maternal infection and inflammation that has significant developmental consequences largely characterized within the context of neurodevelopmental disorders such as autism spectrum disorder and schizophrenia. MIA can also lead to long-lasting changes within the neuroimmune system, which lead to compounding negative outcomes following a second insult. This supports the importance of understanding the interaction of maternal inflammation and hypoxic-ischemic outcomes. Animal models have been invaluable to understanding the pathophysiology of this injury and to the development of therapeutic hypothermia. However, each model system has its own limitations. Large animal models such as pigs may more accurately represent the brain and organ development and complexity in humans, while rodent models are more cost-effective and offer more possible molecular techniques. Recent studies have utilized MIA or direct inflammation prior to HIE insult. Investigators should thoughtfully consider the risk factors they wish to include in their HIE animal models. In the incorporation of MIA, investigators should consider the type, timing, and dose of the inflammatory stimulus, as well as the timing, severity, and type of hypoxic insult. Using a variety of animal models that incorporate the maternal-placental-fetal system of inflammation will most likely lead to a more robust understanding of the mechanisms of this injury that can guide future clinical decisions and therapies.

Advances in Neuroimaging Biomarkers and Scoring

MRI of the brain is a critical tool in the diagnosis, evaluation, and management of neonatal encephalopathy (NE). More than simply a diagnostic and prognostic tool, MRI informs the biology, nature, and timing of the disease process resulting in NE, of which the largest single etiology is hypoxic-ischemic encephalopathy (HIE). Historically, 2 major patterns of injury were seen in HIE: a basal ganglia/thalamus predominant pattern and a watershed pattern of injury. The advent of therapeutic hypothermia for NE/HIE, alongside improvements in the application of imaging technology in newborn infants, has resulted in progressively more advanced MRI scoring systems.

Ultrasonic vocalization emission is altered following neonatal hypoxic-ischemic brain injury in mice

Neonatal hypoxic-ischemic (HI) brain injury leads to cognitive impairments including social communication disabilities. Current treatments do not sufficiently target these impairments, therefore new tools are needed to examine social communication in models for neonatal brain injury. Ultrasonic vocalizations (USVs) during early life show potential as a measurement for social development and reflect landmark developmental stages in neonatal mice. However, changes in USV emission early after HI injury have not been found yet. Our current study examines USV patterns and classes in the first 3 days after HI injury. C57Bl/6 mice were subjected to HI on postnatal day (P)9 and USVs were recorded between P10 and P12. Audio files were analyzed using the VocalMat automated tool. HI-injured mice emitted less USVs, for shorter durations, and at a higher frequency compared to control (sham-operated) littermates. The HI-induced alterations in USVs were most distinct at P10 and in the frequency range of 50-75 kHz. At P10 HI-injured mouse pups also produced different ratios of USV class types compared to control littermates. Moreover, alterations in the duration and frequency were specific to certain USV classes in HI animals compared to controls. Injury in the striatum and hippocampus contributed most to alterations in USV communication after HI. Overall, neonatal HI injury leads to USV alterations in newborn mice which could be used as a tool to study early HI-related social communication deficits.

Prognostic value of quantitative EEG in early hours of life for neonatal encephalopathy and neurodevelopmental outcomes

BACKGROUND

The ability to determine severity of encephalopathy is crucial for early neuroprotective therapies and for predicting neurodevelopmental outcome. The objective of this study was to assess a novel brain state of newborn (BSN) trend to distinguish newborns with presence of hypoxic ischemic encephalopathy (HIE) within hours after birth and predict neurodevelopmental outcomes at 2 years of age.

METHOD

This is a prospective cohort study of newborns at 36 weeks' gestation or later with and without HIE at birth. The Total Sanart Score (TSS) was calculated based on a modified Sarnat exam within 6 h of life. BSN was calculated from electroencephalogram (EEG) measurements initiated after birth. The primary outcome at 2 year of age was a diagnosis of death or disability using the Bayley Scales of Infant Development III.

RESULTS

BSN differentiated between normal and abnormal neurodevelopmental outcomes throughout the entire recording period from 6 h of life. Additionally, infants with lower BSN values had higher odds of neurodevelopmental impairment and HIE. BSN distinguished between normal (n = 86) and HIE (n = 46) and showed a significant correlation with the concomitant TSS.

CONCLUSION

BSN is a sensitive real-time marker for monitoring dynamic progression of encephalopathy and predicting neurodevelopmental impairment.

IMPACT

This is a prospective cohort study to investigate the ability of brain state of newborn (BSN) trend to predict neurodevelopmental outcome within the first day of life and identify severity of encephalopathy. BSN predicts neurodevelopmental outcomes at 2 years of age and the severity of encephalopathy severity. It also correlates with the Total Sarnat Score from the modified Sarnat exam. BSN could serve as a promising bedside trend aiding in accurate assessment and identification of newborns who may benefit from additional neuroprotection therapies.

Enhancing Early Detection of Sepsis in Neonates through Multimodal Biosignal Integration: A Study of Pulse Oximetry, Near-Infrared Spectroscopy (NIRS), and Skin Temperature Monitoring

Sepsis continues to be challenging to diagnose due to its non-specific clinical signs and symptoms, emphasizing the importance of early detection. Our study aimed to enhance the accuracy of sepsis diagnosis by integrating multimodal monitoring technologies with conventional diagnostic methods. The research included a total of 121 newborns, with 39 cases of late-onset sepsis, 35 cases of early-onset sepsis, and 47 control subjects. Continuous monitoring of biosignals, including pulse oximetry (PO), near-infrared spectroscopy (NIRS), and skin temperature (ST), was conducted. An algorithm was then developed in Python to identify early signs of sepsis. The model demonstrated the capability to detect sepsis 6 to 48 h in advance with an accuracy rate of 87.67 ± 7.42%. Sensitivity and specificity were recorded at 76% and 90%, respectively, with NIRS and ST having the most significant impact on predictive accuracy. Despite the promising results, limitations such as sample size, data variability, and potential biases were noted. These findings highlight the critical role of non-invasive biosensing methods in conjunction with conventional biomarkers and cultures, offering a strong foundation for early sepsis detection and improved neonatal care. Further research should be conducted to validate these results across different clinical settings.

EEG Spectral Power and Neurovascular Coupling as Early Predictors of Neurodevelopmental Outcome in Neonatal Hypoxic-Ischemic Encephalopathy

Hypoxic ischemic encephalopathy (HIE) remains one of the leading causes of morbidity and mortality in newborns. There is a strong need to predict their neurodevelopmental impairment (NDI) within early hours of life, tailoring treatment strategies accordingly. This study aims to explore the discriminatory capabilities of electroencephalogram (EEG) delta power (DP) and total power (TP), along with neurovascular coupling (NVC) to predict NDI. The study evaluates the relationships of single biomarkers (DP, TP, and NVC) with NDI using univariate logistic regression models. The predictive accuracy of single (DP, TP, and NVC) and combination of biomarkers (DP+NVC, TP+NVC) on NDI is further assessed through the receiver operating characteristic (ROC) curve, with the area under the ROC curve (AUC). Utilizing EEG and near infrared spectroscopy (NIRS) data from 35 newborns with mild and moderate HIE, we found that a one-unit increase in DP or TP significantly lowered the odds of NDI. The combination of DP or TP and NVC is most effective in distinguishing newborns who may develop NDI. These findings suggest that continuous multimodal real-time neuromonitoring could offer valuable insights into HIE severity, aiding in predicting brain injury and NDI.

Neuroprotective strategies for neonatal hypoxic-ischemic brain damage: Current status and challenges

Neonatal hypoxic-ischemic brain damage (HIBD) is a prominent contributor to both immediate mortality and long-term impairment in newborns. The elusive nature of the underlying mechanisms responsible for neonatal HIBD presents a significant obstacle in the effective clinical application of numerous pharmaceutical interventions. This comprehensive review aims to concentrate on the potential neuroprotective agents that have demonstrated efficacy in addressing various pathogenic factors associated with neonatal HIBD, encompassing oxidative stress, calcium overload, mitochondrial dysfunction, endoplasmic reticulum stress, inflammatory response, and apoptosis. In this review, we conducted an analysis of the precise molecular pathways by which these drugs elicit neuroprotective effects in animal models of neonatal hypoxic-ischemic brain injury (HIBD). Our objective was to provide a comprehensive overview of potential neuroprotective agents for the treatment of neonatal HIBD in animal experiments, with the ultimate goal of enhancing the feasibility of clinical translation and establishing a solid theoretical foundation for the clinical management of neonatal HIBD.

Clinical characteristics and long-term neurodevelopmental outcomes of leukomalacia in preterm infants and term infants: a cohort study

BACKGROUND

Leukomalacia is a serious form of neonatal brain injury that often leads to neurodevelopmental impairment, and studies on neonatal leukomalacia and its long-term outcomes are lacking. The aim of this study was to analyze the clinical manifestations, imaging features, and long-term neurodevelopmental outcomes in preterm infants and term infants with leukomalacia.

METHODS

Newborns diagnosed with leukomalacia by head magnetic resonance imaging (MRI) and who were admitted to intensive care units from January 2015 to June 2020 were enrolled. All infants were followed up to June 2022 (2-7 years old), and their neurodevelopmental outcomes were evaluated. The clinical data and long- term outcomes of preterm infants and term infants was analyzed by Chi-square tests.

RESULTS

A total of 218 surviving infants with leukomalacia including 114 preterm infants and 104 term infants completed the follow-up. The major typesof leukomalacia on MRI were periventricular leukomalacia in the preterm group and subcortical cystic leukomalacia in the term group, respectively (χ2 = 55.166; p < 0.001). When followed up to 2-7 years old, the incidence of neurodevelopmental impairment in the preterm group and term group was not significantly different (χ2 = 0.917; p = 0.338). However, the incidence of cerebral palsy (CP) in the preterm group was significantly higher (χ2 = 4.896; p = 0.027), while the incidence of intellectual disability (ID) (χ2 = 9.445; p = 0.002), epilepsy (EP) (χ2 = 23.049; p < 0.001), and CP combined with ID andEP (χ2 = 4.122; p = 0.042) was significantly lower than that in the term group.

CONCLUSIONS

Periventricular leukomalacia mainly occurred in preterm infants while subcortical cystic leukomalacia was commonly seen in term infants. Although the long-term neurodevelopmental outcomes of leukomalacia were both poor, preterm infants were more prone to CP, while term infants were more prone to ID, EP, and the combination of CP with ID and EP.

Selectively compromised inner retina function following hypoxic-ischemic encephalopathy in mice: A noninvasive measure of severity of the injury

The intricate system of connections between the eye and the brain implies that there are common pathways for the eye and brain that get activated following injury. Hypoxia-ischemia (HI) related encephalopathy is a consequence of brain injury caused by oxygen and blood flow deprivation that may result in visual disturbances and neurodevelopmental disorders in surviving neonates. We have previously shown that the tyrosine receptor kinase B (TrkB) agonist/modulator improves neuronal survival and long-term neuroprotection in a sexually differential way. In this study, we tested the hypotheses that; 1) TrkB agonist therapy improves the visual function in a sexually differential way; 2) Visual function detected by electroretinogram (ERG) correlates with severity of brain injury detected by magnetic resonance (MRI) imaging following neonatal HI in mice. To test our hypotheses, we used C57/BL6 mice at postnatal day (P) 9 and subjected them to either Vannucci's rodent model of neonatal HI or sham surgery. ERG was performed at P 30, 60, and 90. MRI was performed following the completion of the ERG. ERG in these mice showed that the a-wave is normal, but the b-wave amplitude is severely abnormal, reducing the b/a wave amplitude ratio. Inner retina function was found to be perturbed as we detected severely attenuated oscillatory potential after HI. No sex differences were detected in the injury and severity pattern to the retina as well as in response to 7,8-DHF therapy. Strong correlations were detected between the percent change in b/a ratio and percent hemispheric/hippocampal tissue loss obtained by MRI, suggesting that ERG is a valuable noninvasive tool that can predict the long-term severity of brain injury.