Hypoxic-Ischemic Encephalopathy: Changing Outcomes Across the Spectrum

Neuroprognostication in neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy

Over the last two decades, significant progress has been made in the management of neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy. One key area that requires improvement is timely and accurate neuroprognostication in this population to identify infants who may benefit from early interventions and harness the maximum neuroplastic capacity of the developing brain. Improved neuroprognostication also has the potential to foster more effective communication of findings to caregivers. In this review, we explore whether improved neuroprognostication is possible by assessing clinical, biochemical, electrographic, neurophysiological, and neuroimaging biomarkers and their role in neuroprognostication. IMPACT STATEMENT: Over the last two decades, significant progress has been made in the management of neonatal encephalopathy due to presumed hypoxic-ischemic encephalopathy. One key area that requires improvement is timely and accurate neuroprognostication in this population to identify infants who may benefit from early interventions and harness the maximum neuroplastic capacity of the developing brain. In this review article, we discuss general concepts and principles of neuroprognostication and the role of each prognostic marker.

Sevoflurane postconditioning mitigates neuronal hypoxic-ischemic injury via regulating reactive astrocytic STAT3 protein modification

Astrocyte activation plays a pivotal role in accelerating the cascade of neuroinflammation associated with the development of hypoxic-ischemic brain injury. This study aimed to investigate the mechanism by which sevoflurane postconditioning mitigates neuronal damage through astrocytes by regulating reactive astrocytic Signal Transducer and Activator of Transcription 3 (STAT3) modifications. A modified Rice‒Vannucci model in rats and a conditioned culture system established by subjecting primary astrocytes to oxygen glucose deprivation, followed by using the conditioned medium to culture the neuron cell line SH-SY5Y were used to simulate HI insult in vivo and in vitro, respectively. These models were followed by 30 min of 2.5 % sevoflurane treatment. Stattic was used to inhibit STAT3 phosphorylation, and (Z)-PUGNAc or OSMI-1 was added to regulate O-linked-β-N-acetylglucosamine modification (O-GlcNAcylation) in primary astrocytes in vitro. Neurobehavioral tests, Nissl staining, CCK8 assay, and flow cytometry for apoptosis were used to assess neuronal function. Immunofluorescence staining was used to detect astrocyte reactivity and the intracellular distribution of STAT3. Immunoprecipitation combined with Western blotting was used to evaluate the O-GlcNAcylation of STAT3. Protein expression and phosphorylation levels were detected by Western blotting. ELISA was conducted to detect the detrimental cytokines IL-6 and IL-1β in astrocyte-conditioned medium. Sevoflurane postconditioning enhanced the O-GlcNAcylation of astrocytic STAT3 following HI insult via the manner of OGT. Crosstalk between O-GlcNAcylation and phosphorylation of STAT3 showed that O-GlcNAcylation inhibited STAT3 phosphorylation. The inhibitory effect on astrocytes suppressed STAT3 nuclear translocation, reduced astrocyte reactivity, decreased the release of the inflammatory cytokines IL6 and IL-1β, attenuated neuronal apoptosis following HI insult, and improved neuron viability. Sevoflurane postconditioning increased astrocytic STAT3 O-GlcNAcylation level to competitively inhibit STAT3 phosphorylation. This deactivated downstream inflammation pathways and reduced astrocyte reactivity, thereby mitigating HI insult in neurons both in vivo and in vitro.

Project Initiate: A Clinical Feasibility Trial of Equitable Access to Early Neurodevelopmental Therapy

Background/Objectives: Despite evidence of the effectiveness of early intervention (EI) programs, eligible infants often experience delays in initiation of services or fail to receive services entirely. Disparities have been documented, including lower enrollment rates for infants with public insurance. The objective of this pilot study was to evaluate the feasibility of initiating home physical therapy (PT) services promptly after neonatal or cardiac intensive care unit (NICU/CICU) discharge for infants with public insurance and to assess early motor outcomes for children who received study therapy compared with a standard of care group. Methods: Infants were recruited if discharged from a study NICU/CICU, had public insurance, and were eligible for Illinois EI services. Infants living in Chicago (n = 46) received weekly home-based PT from a study therapist until 3-4 months corrected age (CA). Infants living outside Chicago received standard of care services and served as a control group (n = 14). At discharge, infants were referred to EI and underwent the Test of Infant Motor Performance (TIMP). Outcomes at 3-4 months CA included initiation rates for study PT and EI and follow-up TIMP testing. Results: By 3-4 months CA, 78% of the intervention group had received ≥1 PT session. In contrast, just 13% of the entire cohort had received any EI therapy. Infants who had 8-10 PT sessions in the first 3-4 months after discharge were more likely to have a change in the TIMP Z-score of >0.5 SD. Conclusions: Prompt transition to home therapy was feasible for infants with public insurance in an urban setting who may benefit most due to the potential for neuroplastic change. Addressing barriers identified in this study may assist in improving access to EI for young infants.

Role of pentoxifylline in neonatal hypoxic ischaemic encephalopathy: a systematic review of animal studies

We systematically reviewed the evidence from animal studies assessing the effects of pentoxifylline on neonatal hypoxic-ischemic encephalopathy (HIE). The PubMed, EMBASE, EMCARE, MEDLINE, Cochrane Library, and Google Scholar databases were searched for randomized and quasi randomized controlled trials (RCTs) in December 2023 to determine the effects of pentoxifylline in animal models of HIE. The quality of the included studies was assessed via the SYRCLE risk of bias (ROB) tool. The certainty of evidence was assessed via the GRADE methodology. All seven included studies (n = 248) involved a rat HIE model in which pentoxifylline (25-150 mg/kg) was administered intraperitoneally. The majority had unclear ROB. All the studies reported a protective effect of pentoxifylline on HIE-induced organ injury. Mortality was comparable at pentoxifylline doses between 25 and 75 mg/kg but higher at 150 mg/kg than in the control group. Three studies reported macroscopic changes in HIE-affected organs. There was a significant reduction in cerebral infarction (40 and 75 mg/kg), hippocampal atrophy, and visible gut injury (60 mg/kg). A significantly lower number of Caspase 3 immunoreactive cells and necrotic cells were observed at the 60 mg/kg dose, whereas the 100 mg/kg dose had a deleterious effect. Three other studies reported significantly reduced levels of proinflammatory markers including IL-6 and TNF-alpha. Current evidence (with low uncertainty) from a rat model suggests that pentoxifylline has the potential to improve mortality and attenuate organ injury following HIE. Adequately powered, well-designed human RCTs are needed to confirm our findings.

A New Horizon for Understanding the Comparative Effectiveness for Cooling Prospectively Infants with Mild Encephalopathy

The authors summarize the methodology for a new pragmatic comparative effectiveness research investigation, Cooling Prospectively Infants with Mild Encephalopathy (COOLPRIME), which uses sites' existing mild hypoxic-ischemic encephalopathy (HIE) treatment preference (hypothermia or normothermia) to assess hypothermia effectiveness and safety. COOLPRIME's primary aim is to determine the safety and effectiveness of hypothermia compared to normothermia in mild HIE. Engagement of Families and Community Affected by Hypoxic-Ischemic Encephalopathy strongly favored Effectiveness over Efficacy Trials leading to COOL PRIME design.

Advances in Electroencephalographic Biomarkers of Neonatal Hypoxic Ischemic Encephalopathy

Electroencephalography (EEG) is a key objective biomarker of newborn brain function, delivering critical, cotside insights to aid the management of encephalopathy. Access to continuous EEG is limited, forcing reliance on subjective clinical assessments. In hypoxia ischaemia, the primary cause of encephalopathy, alterations in EEG patterns correlate with. injury severity and evolution. As HIE evolves, causing secondary neuronal death, EEG can track injury progression, informing neuroprotective strategies, seizure management and prognosis. Despite its value, challenges with interpretation and lack of on site expertise has limited its broader adoption. Technological advances, particularly in digital EEG and machine learning, are enhancing real-time analysis. This will allow EEG to expand its role in HIE diagnosis, management and outcome prediction.

Pediatric Cranial Ultrasound Revisited: A Comprehensive Review

ABSTRACT

Cranial ultrasound (CUS) is an indispensable tool in the evaluation of intracranial pathology in premature and term neonates and older infants. Familiarity with standard cranial ultrasound techniques and parameters, normal anatomy, and commonly encountered abnormalities is crucial for providing appropriate care for these patients. This review provides a comprehensive overview of cranial ultrasound in clinical practice.

[Investigation of a French cohort of neonatal anoxo-ischemic encephalopathy in the era of therapeutic hypothermia: Questions and answers]

OBJECTIVE

To improve knowledge of neonatal hypoxic-ischemic encephalopathy, a prospective, nationwide, population-based cohort of affected children is being set up between September 2015 and March 2017.

METHODS

During this period, 794 cases are collected, with information on pregnancy, delivery, neonatal stay and outcome at the end of hospitalization. Clinical and parental questionnaire follow-up is planned until the child is 4 years old.

RESULTS

This article presents the clinical presentation of the newborns included, the analysis of factors associated with short-term outcome at hospital discharge and the organizational factors associated with treatment with therapeutic hypothermia.

CONCLUSION

These data illustrate the value of a prospective cohort to analyze the management of anoxo-ischemic encephalopathy in France.

Neonatal Hypoxic-Ischemic Encephalopathy Spectrum: Severity-Stratified Analysis of Neuroimaging Modalities and Association with Neurodevelopmental Outcomes

OBJECTIVE

To compare hypoxic-ischemic injury on early cranial ultrasonography (cUS) and post-rewarming brain magnetic resonance imaging (MRI) in newborn infants with hypoxic-ischemic encephalopathy (HIE) and to correlate that neuroimaging with neurodevelopmental outcomes.

STUDY DESIGN

This was a retrospective cohort study of infants with mild, moderate, and severe HIE treated with therapeutic hypothermia and evaluated with early cUS and postrewarming MRI. Validated scoring systems were used to compare the severity of brain injury on cUS and MRI. Neurodevelopmental outcomes were assessed at 18 months of age.

RESULTS

Among the 149 included infants, abnormal white matter (WM) and deep gray matter (DGM) hyperechogenicity on cUS in the first 48 hours after birth were more common in the severe HIE group than the mild HIE group (81% vs 39% and 50% vs 0%, respectively; P < .001). In infants with a normal cUS, 95% had normal or mildly abnormal brain MRIs. In infants with severely abnormal cUS, none had normal and 83% had severely abnormal brain MRIs. Total abnormality scores on cUS were higher in neonates with near-total brain injury on MRI than in neonates with normal MRI or WM-predominant injury pattern (adjusted P < .001 for both). In the multivariable model, a severely abnormal MRI was the only independent risk factor for adverse outcomes (OR: 19.9, 95% CI: 4.0-98.1; P < .001).

CONCLUSION

The present study shows the complementary utility of cUS in the first 48 hours after birth as a predictive tool for the presence of hypoxic-ischemic injury on brain MRI.

A Call for Early Detection of Cerebral Palsy

Cerebral palsy (CP) is the most common physical disability across the lifespan, but historically, CP has not been diagnosed before the age of 2 years. Barriers to early diagnosis ranged from lack of available biomarkers, absence of curative treatments, perceived stigma associated with a lifelong diagnosis, and a desire to rule out other diagnoses first. Most importantly, the fundamental question that remained was whether children would benefit from earlier detection and intervention given the paucity of research. However, evidence-based guidelines published in 2017 demonstrated that the General Movements Assessment, the Hammersmith Infant Neurological Examination, and neuroimaging can be combined with other elements such as a clinical history and standardized motor assessments to provide the highest predictive value for diagnosing CP as early as age 3 months in high-risk newborns. Implementation of these guidelines has been successful in decreasing the age at CP diagnosis, particularly in high-risk infant follow-up clinics with expertise in performing these assessments. Early detection of CP allows for clinical and research opportunities investigating earlier interventions during a critical period of neuroplasticity, with the goal of improving developmental trajectories for children and their families. New guidelines and research are now being developed with a focus on early, targeted interventions that continue to be studied, along with global detection initiatives.

Mononuclear cell therapy of neonatal hypoxic-ischemic encephalopathy in preclinical versus clinical studies: a systematic analysis of therapeutic efficacy and study design

Background

Hypoxic-ischemic encephalopathy (HIE) is a devastating condition affecting around 8.5 in 1000 newborns globally. Therapeutic hypothermia (TH) can reduce mortality and, to a limited extent, disability after HIE. Nevertheless, there is a need for new and effective treatment strategies. Cell based treatments using mononuclear cells (MNC), which can be sourced from umbilical cord blood, are currently being investigated. Despite promising preclinical results, there is currently no strong indicator for clinical efficacy of the approach. This analysis aimed to provide potential explanations for this discrepancy.

Methods

A systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines. Preclinical and clinical studies were retrieved from PubMed, Web of Science, Scopus, and clinicaltrials.gov using a predefined search strategy. A total of 17 preclinical and 7 clinical studies were included. We analyzed overall MNC efficacy in preclinical trials, the methodological quality of preclinical trials and relevant design features in preclinical versus clinical trials.

Results

There was evidence for MNC therapeutic efficacy in preclinical models of HIE. The methodological quality of preclinical studies was not optimal, and statistical design quality was particularly poor. However, methodological quality was above the standard in other fields. There were significant differences in preclinical versus clinical study design including the use of TH as a baseline treatment (only in clinical studies) and much higher MNC doses being applied in preclinical studies.

Conclusions

Based on the analyzed data, it is unlikely that therapeutic effect size is massively overestimated in preclinical studies. It is more plausible that the many design differences between preclinical and clinical trials are responsible for the so far lacking proof of efficacy of MNC treatments in HIE. Additional preclinical and clinical research is required to optimize the application of MNC for experimental HIE treatment.

Outcomes of Neonates with Hypoxic-Ischemic Encephalopathy Treated with Magnesium Sulfate: A Systematic Review with Meta-analysis

OBJECTIVE

To assess magnesium sulfate (MgSO4) as a neuroprotective agent in hypoxic-ischemic encephalopathy.

STUDY DESIGN

For this systematic review, PubMed, EMBASE, the Cochrane Library, EMCARE, and MedNar were searched in November 2022 for randomized controlled trials (RCTs). Meta-analysis was conducted using Stata 16.0 and RevMan 5.3.

RESULTS

Twenty RCTs with a total sample size of 1485 were included, of which 16 were from settings where therapeutic hypothermia (TH) was not offered. Regarding MgSO4 in settings where TH was not offered, only 1 study evaluated composite outcome of death or disability at ≥18 months and reported such poor outcome in 8 of 14 control infants and 4 of 8 in the MgSO4 group. MgSO4 was not associated with mortality (RR, 0.86; 95% CI, 0.72-1.03; 13 RCTs) or hypotension (RR, 1.02; 95% CI, 0.88-1.18; 5 RCTs). Thirteen studies reported that MgSO4 improved in-hospital outcomes, such as reduced seizure burden and improved neurological status at discharge. MgSO4 reduced the risk of poor suck feeds (RR, 0.52; 95% CI, 0.40-0.68; 6RCTs) and abnormal electroencephalogram (RR, 0.64; 95% CI, 0.45-0.93; 5 RCTs). Certainty of evidence was moderate for mortality and low or very low for other outcomes. For studies with MgSO4 as an adjunct to TH, none reported on death or neurodevelopmental disability at ≥18 months. MgSO4 was not associated with mortality (RR, 0.65; 95% CI, 0.34-1.27; 3 RCTs) or hypotension (RR, 1.0; 95% CI, 0.71-1.40; 3 RCTs).

CONCLUSIONS

Evidence around long-term outcomes of MgSO4 when used with or without TH was scant. MgSO4 therapy may improve in-hospital neurological outcomes without affecting mortality in settings where TH is not offered. Well-designed RCTs for neuroprotection are needed, especially in low-resource settings.

TRIAL REGISTRATION

"Open Science Forum" (https://doi.org/10.17605/OSF.IO/FRM4D).