Hypoxic-Ischemic Encephalopathy: Changing Outcomes Across the Spectrum

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).