A review of the conundrum of mild hypoxic-ischemic encephalopathy: Current challenges and moving forward

Association between Early Basal Ganglia and Thalami Perfusion Assessed by Color Doppler Ultrasonography and Brain Injury in Infants with Hypoxic-Ischemic Encephalopathy: A Prospective Cohort Study

OBJECTIVE

To evaluate associations between neurologic outcomes and early measurements of basal ganglia (BG) and thalamic (Th) perfusion using color Doppler ultrasonography (CDUS) in infants with hypoxic-ischemic encephalopathy (HIE).

STUDY DESIGN

Prospective study of infants with mild (n = 18), moderate (n = 17), and severe HIE (n = 14) and controls (n = 17). Infants with moderate-severe HIE received therapeutic hypothermia (TH). CDUS was performed at 24-36 hours and brain magnetic resonance imaging (MRI) at a median of 10 days. Development was followed through 2.5-5 years. The primary outcome was the association between BG and Th perfusion and brain MRI injury. Secondary analyses focused on associations between perfusion measurements and admission neurologic examinations, MRI scores in infants treated with TH, and motor and sensory disability, or death. An exploratory analysis assessed the accuracy of BG and Th perfusion to predict brain MRI injury in infants treated with TH.

RESULTS

Increased BG and Th perfusion on CDUS was observed in infants with severe MRI scores and those with significant motor and neurosensory disability or death through 2.5-5 years (P < .05). Infants with severe HIE showed increased BG and Th perfusion (P < .005) compared with infants with moderate HIE. No differences were identified between the between the control and mild HIE groups. Th perfusion ≥0.237 cm/second (Area under the curve of 0.824) correctly classified 80% of infants with severe MRI scores.

CONCLUSIONS

Early dynamic CDUS of the BG and Th is a potential biomarker of severe brain injury in infants with HIE and may be a useful adjunct to currently used assessments.

Networks of cortical activity show graded responses to perinatal asphyxia

BACKGROUND

Perinatal asphyxia often leads to hypoxic-ischemic encephalopathy (HIE) with a high risk of neurodevelopmental consequences. While moderate and severe HIE link to high morbidity, less is known about brain effects of perinatal asphyxia with no or only mild HIE. Here, we test the hypothesis that cortical activity networks in the newborn infants show a dose-response to asphyxia.

METHODS

We performed EEG recordings for infants with perinatal asphyxia/HIE of varying severity (n = 52) and controls (n = 53) and examined well-established computational metrics of cortical network activity.

RESULTS

We found graded alterations in cortical activity networks according to severity of asphyxia/HIE. Furthermore, our findings correlated with early clinical recovery measured by the time to attain full oral feeding.

CONCLUSION

We show that both local and large-scale correlated cortical activity are affected by increasing severity of HIE after perinatal asphyxia, suggesting that HIE and perinatal asphyxia are better represented as a continuum rather than the currently used discreet categories. These findings imply that automated computational measures of cortical function may be useful in characterizing the dose effects of adversity in the neonatal brain; such metrics hold promise for benchmarking clinical trials via patient stratification or as early outcome measures.

IMPACT

Perinatal asphyxia causes every fourth neonatal death worldwide and provides a diagnostic and prognostic challenge for the clinician. We report that infants with perinatal asphyxia show specific graded responses in cortical networks according to severity of asphyxia and ensuing hypoxic-ischaemic encephalopathy. Early EEG recording and automated computational measures of brain function have potential to help in clinical evaluation of infants with perinatal asphyxia.

Neonatal Hypoxia-Ischemia alters Brain-Derived Contactin-2-Positive Extracellular Vesicles in the Mouse Plasma

Neonatal encephalopathy (NE) impairs white matter development and results in long-term neurodevelopmental deficits. Leveraging prior findings of altered neuronal proteins carried by brain-derived extracellular vesicles (EVs) that are marked by a neural-specific cell surface glycoprotein Contactin-2 (CNTN2) in NE infants, the present study aimed to determine the correlation between brain and circulating CNTN2+-EVs and whether NE alters circulating CNTN2+-EV levels in mice. Brain tissue and plasma were collected from postnatal day (P)7, 10, 11, 15 mice to determine the baseline CNTN2 correlation between these two compartments (n = 4-7/time point/sex). NE was induced in P10 pups. Brain and plasma samples were collected at 1, 3, 6, 24, and 120 h (n = 4-8/time point/sex). CNTN2 from brain tissue and plasma EVs were quantified using ELISA. ANOVA and linear regression analyses were used to evaluate changes and correlations between brain and plasma CNTN2+-EVs. In baseline experiments, CNTN2 in brain tissue and plasma EVs peaked at P10 with no sex-difference. Brain and plasma CNTN2+-EV showed a positive correlation across early postnatal ages. NE pups showed an elevated CNTN2 in brain tissue and EVs at 1 h and only in brain tissue at 24 h. NE also abolished the positive plasma-brain correlation. The findings establish a link for central CNTN2 and its release into circulation during early postnatal life. The immediate elevation and release of CNTN2 following NE highlight a potential molecular response shortly after a brain injurious event. Our findings further support the utility of circulating brain-derived EVs as a possible bioindicator of NE.

Maternal treatment with selective serotonin reuptake inhibitors during pregnancy and delayed neonatal adaptation: a population-based cohort study

OBJECTIVE

Selective serotonin reuptake inhibitor (SSRI) use is common in pregnancy. It is associated with delayed neonatal adaptation. Most previous studies have not adjusted for the severity of maternal mental health disorders or examined the impact of SSRI type and dosage. We examined whether treatment with SSRIs in late pregnancy (after 20 weeks) is associated with delayed neonatal adaptation independent of maternal depression and anxiety.

DESIGN, SETTING AND PATIENTS

Retrospective population-based birth cohort of 280 090 term infants born at 15 Kaiser Permanente Northern California hospitals, 2011-2019. Individual-level pharmacy, maternal, pregnancy and neonatal data were obtained from electronic medical records.

EXPOSURE

Dispensed maternal SSRI prescription after 20 weeks of pregnancy.

MAIN OUTCOME MEASURES

Delayed neonatal adaptation defined as a 5 min Apgar score ≤5, resuscitation at birth or admission to a neonatal intensive care unit for respiratory support. Secondary outcomes included each individual component of the primary outcome and more severe neonatal outcomes (pulmonary hypertension, hypoxic-ischaemic encephalopathy and seizures).

RESULTS

7573 (2.7%) infants were exposed to SSRIs in late pregnancy. Delayed neonatal adaptation occurred in 11.2% of exposed vs 4.4% of unexposed infants (relative risk 2.52 (95% CI 2.36 to 2.70)). After multivariable adjustment, there was an association between SSRI exposure and delayed neonatal adaptation (adjusted OR 2.14 (95% CI 1.96 to 2.32)). This association was dose dependent. Escitalopram and fluoxetine were associated with the highest risk of delayed neonatal adaptation.

CONCLUSIONS

Infants exposed to SSRIs have increased risks of delayed adaptation in a type and dose-dependent relationship, pointing toward a causal relationship.

Neonatal cortical activity organizes into transient network states that are affected by vigilance states and brain injury

Early neurodevelopment is critically dependent on the structure and dynamics of spontaneous neuronal activity; however, the natural organization of newborn cortical networks is poorly understood. Recent adult studies suggest that spontaneous cortical activity exhibits discrete network states with physiological correlates. Here, we studied newborn cortical activity during sleep using hidden Markov modeling to determine the presence of such discrete neonatal cortical states (NCS) in 107 newborn infants, with 47 of them presenting with a perinatal brain injury. Our results show that neonatal cortical activity organizes into four discrete NCSs that are present in both cardinal sleep states of a newborn infant, active and quiet sleep, respectively. These NCSs exhibit state-specific spectral and functional network characteristics. The sleep states exhibit different NCS dynamics, with quiet sleep presenting higher fronto-temporal activity and a stronger brain-wide neuronal coupling. Brain injury was associated with prolonged lifetimes of the transient NCSs, suggesting lowered dynamics, or flexibility, in the cortical networks. Taken together, the findings suggest that spontaneously occurring transient network states are already present at birth, with significant physiological and pathological correlates; this NCS analysis framework can be fully automatized, and it holds promise for offering an objective, global level measure of early brain function for benchmarking neurodevelopmental or clinical research.

Low Apgar score and need for resuscitation increased the probability of receiving therapeutic hypothermia more strongly than acidosis at birth

AIM

The aim of this study was to investigate how individual markers for birth asphyxia, so-called A criteria, were associated with the probability of receiving therapeutic hypothermia.

METHODS

This population-based cohort study included 1336 live-born singleton term infants with any A criterion in the Stockholm-Gotland Region, Sweden during 2008 to 2014. The Swedish Neonatal Quality Register and National Patient Register were used for data collection. Results were presented as adjusted odds ratios (aORs) with 95% confidence intervals (CIs).

RESULTS

There were 89 infants, 44 boys and 45 girls with mean gestational age 40.5 weeks, who received therapeutic hypothermia. Low Apgar score, aOR 12.44 (95% CI 5.99-25.86), and resuscitation, aOR 9.18 (95% CI 3.77-22.34), were strongly associated with therapeutic hypothermia. A pH <7.0 was less associated with the outcome, aOR 2.02 (95% CI 1.02-4.0). No infant who received therapeutic hypothermia fulfilled the criteria of base deficit ≥16 mmol/L only.

CONCLUSION

A low Apgar score of and/or a need for resuscitation is more relevant for identifying infants eligible for therapeutic hypothermia, compared to other A criteria. This knowledge could be used clinically to identify cases for review and avoid unnecessary monitoring of infants.

Hypoxic-Ischemic Encephalopathy: Changing Outcomes Across the Spectrum

Neonatal hypoxic-ischemic encephalopathy (HIE) is a leading cause of death and neurodevelopmental impairment in neonates. Therapeutic hypothermia (TH) is the only established effective therapy and randomized trials affirm that TH reduces death and disability in moderate-to-severe HIE. Traditionally, infants with mild HIE were excluded from these trials due to the perceived low risk for impairment. Recently, multiple studies suggest that infants with untreated mild HIE may be at significant risk of abnormal neurodevelopmental outcomes. This review will focus on the changing landscape of TH, the spectrum of HIE presentations and their neurodevelopmental outcomes.

Near-infrared spectroscopy measured cerebral oxygenation in full-term infants during transition: an observational study

Background

Brain is one of the most sensitive organs to hypoxia during resuscitation. NIRS-measured cerebral oxygenation is an evolving brain monitoring tool for neonatal resuscitation.

Methods

We undertook a prospective observational study for monitoring of cerebral oxygenation and peripheral preductal saturation at 1, 5, and 10 min after birth. Fractional tissue oxygen extraction was calculated as well. In addition to studying factors affecting cerebral oxygenation at those points in time. For the current cohort, cerebral oxygenation centile charts were provided at those time points. This work was registered in the cinicaltrial.gov NCT05158881.

Results

Sixty healthy term neonates were enrolled to define reference ranges and centile charts of cerebral oxygenation at 1, 5, and 10 min after birth. The strongest correlations between cerebral oxygenation metrics and peripheral preductal saturation were at 5 min after birth with r value = 0.628. Using logistic regression analysis to determine the most significant factors affecting NIRS-measured crSO2 in healthy full-term neonates, we found that the mode of delivery was the most significant factor with OR = 4.000 (1.367–11.703) at 5 min and 8.726 (2.517–30.25) at 10 min.

Conclusions

Normal values for NIRS may help to identify infants with cerebral oxygenation below a certain value indicating regional hypoxia at certain time points and can guide neonatal resuscitation interventions. Caesarean section is the most significant factor affecting cerebral oxygenation during the transition of healthy full-term neonates.

Placental pathology as a marker of brain injury in infants with hypoxic ischemic encephalopathy

BACKGROUND

Hypoxic Ischemic Encephalopathy (HIE) can lead to devastating consequences for the affected infant. Although therapeutic cooling benefits infants with moderate and severe HIE, differentiating mild from moderate-severe HIE may be challenging. The placenta reflects the fetal intrauterine environment and may reveal underlying processes that affect brain injury.

AIM

To describe placental histopathology using the Amsterdam Placental Workshop Group Criteria in different grades of HIE.

STUDY DESIGN

Retrospective cohort.

SUBJECTS

Infants admitted to a tertiary care neonatal intensive care unit with a diagnosis of HIE between 2011 and 2016.

OUTCOME MEASURE

Maternal and neonatal clinical variables and placental histopathology using the Amsterdam Placental Workshop Group Criteria were compared between mild and moderate-severe HIE. Mann-Whitney or t-test or ꭓ² were performed for bivariate associations as appropriate. To explain the relationship between placental pathology and severity of HIE odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated using logistic regression models.

RESULTS

Of the 73 infants in the study, 23 had mild and 50 moderate-sever HIE. There was no difference in maternal and neonatal characteristics except for sentinel events which were higher in the moderate- severe group. On placental histopathology, acute inflammation, including fetal inflammatory reaction (FIR) were significantly higher in the moderate-severe group. After adjusting for confounders, FIR remained significantly associated with moderate-severe HIE, ORs 6.29, 95 % CI 1.5-25.

CONCLUSION

Our study demonstrates FIR in the placenta is associated with severity of HIE.

Scutellarin protects cortical neurons against neonatal hypoxic-ischemic encephalopathy injury via upregulation of vascular endothelial growth factor

Neonatal hypoxic-ischemic encephalopathy (NHIE) causes devastating cerebral damage and neurological deficits that seldom have effective therapies. This study aimed to explore the mechanisms underlying the therapeutic efficacy of Scutellarin in NHIE. NHIE models were successfully established. Zea-longa score and triphenyte-trazoliumchloride (TTC) staining demonstrated that hypoxia and ischemia (HI) insult induced prominent neurological dysfunctions and brain infarction. Protein microarray was applied to detect the differentially expressed genes in the cortex, hippocampus, and lung tissues of HI rats, which revealed the downregulation of vascular endothelial growth factor (VEGF) in these tissues. Additionally, double immunostaining uncovered VEGF expression was localized in the neurons. Besides, VEGF was decreasingly expressed in oxygen-glucose deprivation (OGD) neurons, which was intriguingly reversed by Scutellarin treatment. Moreover, VEGF silencing increased OGD-induced neuronal apoptosis and attenuated neurite outgrowth, which was enhanced by Scutellarin administration. GeneMANIA predicted a close correlation of VEGF with caspase 3, caspase 7, and interleukin (IL)-1β, and qRT-PCR revealed that Scutellarin treatment depressed the expression levels of them elevated in OGD neurons, but the Scutellarin-depressed levels of these factors were prominently increased after VEGF silencing. Our findings suggested that Scutellarin exerted neuroprotective effects in NHIE potentially through mediating VEGF-targeted inactivation of caspase 3, caspase 7, and IL-1β.

Early Troponin I Levels in Newborns Undergoing Therapeutic Hypothermia for Hypoxic Ischemic Encephalopathy and Residual Encephalopathy at Discharge

OBJECTIVE

Elevation of serum troponin I has been reported in newborns with hypoxic ischemic encephalopathy (HIE), but it is diagnostic and prognostic utility for newborn under 6 hours is not clear. Study the predictive value of early serum troponin I levels in newborns with HIE undergoing therapeutic hypothermia (TH) for persistent residual encephalopathy (RE) at discharge.

STUDY DESIGN

Retrospective chart review of newborns admitted with diagnosis of HIE to neonatal intensive care unit (NICU) for TH over a period of 3 years. Troponin levels were drawn with the initial set of admission laboratories while initiating TH. Newborns were followed up during hospital course and stratified into three groups based on predischarge examination and their electrical encephalography and cranial MRI findings: Group 1: no RE, Group 2: mild-to-moderate RE, and Group 3: severe RE or needing assisted medical technology or death. Demographic and clinical characteristics including troponin I levels were compared in each group.

RESULTS

Out of 104 newborns who underwent TH, 65 infants were in Group 1, 26 infants in Group 2, and 13 newborns in Group 3. All groups were comparable in demographic characteristics. There was a significant elevation of serum troponin in group 2 (mild-to-moderate RE) and group 3 (severe RE) as compared with group 1 (no RE). Receiver operator curve analysis for any RE (groups 2 and 3) compared with group 1 (no RE as control) had 0.88 (0.81-0.95) area under curve, p < 0.001. A cut-off level of troponin I ≥0.12 µg/L had a sensitivity of 77% and specificity of 78% for diagnosis of any RE, positive predictive value of 68%, and a negative predictive value of 84%.

CONCLUSION

In newborns undergoing TH for HIE, the elevation of troponin within 6 hours of age predicts high risk of having RE at discharge.

KEY POINTS

· Troponin I elevation is a biomarker of myocardial ischemia in adults and children.. · Myocardial ischemia may be part of multi-organ injury in neonatal HIE.. · Early elevation of troponin I level may correlate with the severity of neonatal HIE and predict residual encephalopathy in newborn at discharge from initial hospitalization..

New Horizons in Mild Hypoxic-ischemic Encephalopathy: A Standardized Algorithm to Move past Conundrum of Care

Hypoxic-ischemic encephalopathy (HIE) presents clinically with a neonatal encephalopathy (NE) whereby the mild spectrum is difficult to classify immediately after birth. For decades trials have focused exclusively on infants with moderate-severe HIE s, as these infants were easier to identify after birth and had the highest risk of adverse outcomes. Twenty years after those trials, the PRIME study finally solved the first part of the conundrum by providing a definition of mild HIE in the first 6 hours. There is strong biological plausibility and preclinical evidence supporting the efficacy of therapeutic hypothermia (TH) but there is a lack of comparative clinical data to establish the risk-benefit in mild HIE. The fundamental question of how best to manage mild HIE remains unanswered. This review will summarize (1) the evidence that neonates with mild HIE are at significant risk for adverse outcomes, (2) the gaps/controversies in management, and (3) an algorithm of care is proposed to ensure standardized management of mild HIE and the direction of future trials.

Utilization of Therapeutic Hypothermia and Neurological Injury in Neonates with Mild Hypoxic-Ischemic Encephalopathy: A Report from Children's Hospital Neonatal Consortium

OBJECTIVE

This study was aimed to describe utilization of therapeutic hypothermia (TH) in neonates presenting with mild hypoxic-ischemic encephalopathy (HIE) and associated neurological injury on magnetic resonance imaging (MRI) scans in these infants.

STUDY DESIGN

Neonates ≥ 36 weeks' gestation with mild HIE and available MRI scans were identified. Mild HIE status was assigned to hyper alert infants with an exaggerated response to arousal and mild HIE as the highest grade of encephalopathy recorded. MRI scans were dichotomized as "injury" versus "no injury."

RESULTS

A total of 94.5% (257/272) neonates with mild HIE, referred for evaluation, received TH. MRI injury occurred in 38.2% (104/272) neonates and affected predominantly the white matter (49.0%, n = 51). Injury to the deep nuclear gray matter was identified in (10.1%) 20 infants, and to the cortex in 13.4% (n = 14 infants). In regression analyses (odds ratio [OR]; 95% confidence interval [CI]), history of fetal distress (OR = 0.52; 95% CI: 0.28-0.99) and delivery by caesarian section (OR = 0.54; 95% CI: 0.31-0.92) were associated with lower odds, whereas medical comorbidities during and after cooling were associated with higher odds of brain injury (OR = 2.31; 95% CI: 1.37-3.89).

CONCLUSION

Majority of neonates with mild HIE referred for evaluation are being treated with TH. Odds of neurological injury are over two-fold higher in those with comorbidities during and after cooling. Brain injury predominantly involved the white matter.

KEY POINTS

· Increasingly, neonates with mild HIE are being referred for consideration for hypothermia therapy.. · Drift in clinical practice shows growing number of neonates treated with hypothermia as having mild HIE.. · MRI data show that 38% of neonates with mild HIE have brain injury, predominantly in the white matter..

EEG phase-amplitude coupling to stratify encephalopathy severity in the developing brain

BACKGROUND

Neonatal hypoxic ischemic encephalopathy (HIE) is difficult to classify within the narrow therapeutic window of hypothermia. Neurophysiological biomarkers are needed for timely differentiation of encephalopathy severity within the short therapeutic window for initiation of hypothermia therapy.

METHODS

A novel analysis of mean Phase Amplitude Coupling index, PAC_m, of amplitudes high frequencies (12-30 Hz) coupled with phases of low (1,2 Hz) frequencies was calculated from the 6 h EEG recorded during the first day of life. PAC_m values were compared to identify differences between mild versus higher-grade HIE, respectively, for each of the EEG electrodes. A receiver operating characteristic curve was generated to examine the performance of PAC_m.

RESULTS

38 newborns with different HIE grades were enrolled in the first 6 h of life. Threshold PAC_m 0.001 at Fz, O1, O2, P3, and P4 had AUC >0.9 to differentiate HIE severity and predict the persistence of moderate to severe encephalopathy that requires treatment with hypothermia.

CONCLUSION

PAC is a promising biomarker to identify mild from higher severity of HIE after birth.

Profile of minor neurological findings after perinatal asphyxia

Aim

To characterise the spectrum of findings in sequential neurological examinations, general movements (GM) assessment and magnetic resonance imaging (MRI) of infants with perinatal asphyxia.

Methods

The prospective cohort study of term infants with perinatal asphyxia treated at Helsinki University Hospital's neonatal units in 2016–2020 used Hammersmith Neonatal Neurological Examination (HNNE) and brain MRI at 2 weeks and Hammersmith Infant Neurological Examination (HINE) and GM assessment at 3 months of age.

Results

Analysis included 50 infants: 33 displaying perinatal asphyxia without hypoxic‐ischaemic encephalopathy (HIE), seven with HIE1 and 10 with HIE2. Of the infants with atypical HNNE findings, 24/25 perinatal asphyxia without HIE cases, 5/6 HIE1 cases and all 10 HIE2 cases showed atypical findings in the HINE. The HINE identified atypical spontaneous movements significantly more often in infants with white matter T2 hyperintensity.

Conclusion

In this cohort, most infants with perinatal asphyxia, with or without HIE, presented atypical neurological findings in sequential examinations. The profile of neurological findings for children with perinatal asphyxia without HIE resembled that of children with HIE. White matter T2 hyperintensity was associated with atypical spontaneous movements in the HINE and was a frequent MRI finding also in perinatal asphyxia without HIE.

Early Use of Transcranial Doppler Ultrasonography to Stratify Neonatal Encephalopathy

BACKGROUND

The dynamic nature of neonatal hypoxic-ischemic encephalopathy (HIE) after birth necessitates reliable biomarkers to identify infants with evolving brain injury. This prospective cohort aims to use serial Doppler ultrasonography (US) to measure cerebral blood flow velocity and resistance index (RI) to help detect the time and evolution of the clinical encephalopathy.

METHODS

A total of 60 neonates were enrolled all ≥36 weeks' gestation with perinatal acidemia, defined as a blood gas pH ≤ 7.0 or base deficit ≥16 mmol/L and encephalopathy including a matched control group without encephalopathy. Each neonate received one to three serial Doppler recordings starting at six to 24 hours of life. Mean RI ≤ 0.55 was considered abnormal.

RESULTS

Mean RIs obtained shortly after birth were significantly lower with increasing severity of encephalopathy. On the first Doppler recordings, abnormal mean RIs were seen in 11 of 18 (61%) neonates with mild, 13 of 17 (76%) with moderate, and two of two (100%) with severe HIE. Of the neonates with mild HIE and abnormal mean RIs, congruity abnormal amplitude electroencephalography (45%), brain magnetic resonance imaging (45%), and abnormal head ultrasound (44%) are here reported.

CONCLUSIONS

Doppler measurements can provide bedside adjunct biomarkers indicating the time and severity of neonatal HIE.

Mild Hypoxic-Ischemic Encephalopathy: Can Neurophysiological Monitoring Predict Unfavorable Neurological Outcome? A Systematic Review and Meta-analysis

OBJECTIVE

 Hypoxic-ischemic encephalopathy (HIE) is the second cause of neonatal deaths and one of the main conditions responsible for long-term neurological disability. Contrary to past belief, children with mild HIE can also experience long-term neurological sequelae. The aim of this systematic review is to determine the predictive value of long-term neurological outcome of (electroencephalogram) EEG/amplitude-integrated electroencephalogram (aEEG) in children who complained mild HIE.

STUDY DESIGN

 From a first search on PubMed, Google Scholar, and clinicalTrials.gov databases, only five articles were considered suitable for this study review. A statistical meta-analysis with the evaluation of odds ratio was performed on three of these studies.

RESULTS

 No correlation was found between the characteristics of the electrical activity of the brain obtained through EEG/aEEG in infants with mild HIE and subsequent neurological involvement.

CONCLUSION

 EEG/aEEG monitoring in infants with mild HIE cannot be considered a useful tool in predicting their neurodevelopmental outcome, and its use for this purpose is reported as barely reliable.

KEY POINTS

· Hypoxic-Ischemic Encephalopathy is responsible for long-term neurological outcome, even in newborns with mild HIE.. · No correlation was found between EEG/aEEG trace in infants with mild HIE and neurological sequelae.. · Neurophysiological monitoring, in mild HIE, cannot predic neurodevelopmental outcome..

Acute and Chronic Placental Abnormalities in a Multicenter Cohort of Newborn Infants with Hypoxic-Ischemic Encephalopathy

OBJECTIVE

To examine the frequency of placental abnormalities in a multicenter cohort of newborn infants with hypoxic-ischemic encephalopathy (HIE) and to determine the association between acuity of placental abnormalities and clinical characteristics of HIE.

STUDY DESIGN

Infants born at ≥36 weeks of gestation (n = 500) with moderate or severe HIE were enrolled in the High-dose Erythropoietin for Asphyxia and Encephalopathy Trial. A placental pathologist blinded to clinical information reviewed clinical pathology reports to determine the presence of acute and chronic placental abnormalities using a standard classification system.

RESULTS

Complete placental pathologic examination was available for 321 of 500 (64%) trial participants. Placental abnormalities were identified in 273 of 321 (85%) and were more common in infants ≥40 weeks of gestation (93% vs 81%, P = .01). A combination of acute and chronic placental abnormalities (43%) was more common than either acute (20%) or chronic (21%) abnormalities alone. Acute abnormalities included meconium staining of the placenta (41%) and histologic chorioamnionitis (39%). Chronic abnormalities included maternal vascular malperfusion (25%), villitis of unknown etiology (8%), and fetal vascular malperfusion (6%). Infants with chronic placental abnormalities exhibited a greater mean base deficit at birth (-15.9 vs -14.3, P = .049) than those without such abnormalities. Patients with HIE and acute placental lesions had older mean gestational ages (39.1 vs 38.0, P < .001) and greater rates of clinically diagnosed chorioamnionitis (25% vs 2%, P < .001) than those without acute abnormalities.

CONCLUSIONS

Combined acute and chronic placental abnormalities were common in this cohort of infants with HIE, underscoring the complex causal pathways of HIE.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02811263.

Changing clinical characteristics of infants treated for hypoxic-ischaemic encephalopathy in England, Wales and Scotland: a population-based study using the National Neonatal Research Database

BACKGROUND

Therapeutic hypothermia is standard of care for babies with moderate/severe hypoxic-ischaemic encephalopathy and is increasingly used for mild encephalopathy.

OBJECTIVE

Describe temporal trends in the clinical condition of babies diagnosed with hypoxic-ischaemic encephalopathy who received therapeutic hypothermia.

DESIGN

Retrospective cohort study using data held in the National Neonatal Research Database.

SETTING

National Health Service neonatal units in England, Wales and Scotland.

PATIENTS

Infants born from 1 January 2010 to 31 December 2017 with a recorded diagnosis of hypoxic-ischaemic encephalopathy who received therapeutic hypothermia for at least 3 days or died in this period.

MAIN OUTCOMES

Primary outcomes: recorded clinical characteristics including umbilical cord pH; Apgar score; newborn resuscitation; seizures and treatment on day 1.

SECONDARY OUTCOMES

recorded hypoxic-ischaemic encephalopathy grade.

RESULTS

5201 babies with a diagnosis of hypoxic-ischaemic encephalopathy received therapeutic hypothermia or died; annual numbers increased over the study period. A decreasing proportion had clinical characteristics of severe hypoxia ischaemia or a diagnosis of moderate or severe hypoxic-ischaemic encephalopathy, trends were statistically significant and consistent across multiple clinical characteristics used as markers of severity.

CONCLUSIONS

Treatment with therapeutic hypothermia for hypoxic-ischaemic encephalopathy has increased in England, Scotland and Wales. An increasing proportion of treated infants have a diagnosis of mild hypoxic-ischaemic encephalopathy or have less severe clinical markers of hypoxia. This highlights the importance of determining the role of hypothermia in mild hypoxic-ischaemic encephalopathy. Receipt of therapeutic hypothermia is unlikely to be a useful marker for assessing changes in the incidence of brain injury over time.

EEG Spectral Power: A Proposed Physiological Biomarker to Classify the Hypoxic-Ischemic Encephalopathy Severity in Real Time

BACKGROUND

Mild hypoxic-ischemic encephalopathy (HIE) constitutes a large unstudied population with considerable debate on how to define and treat due to the dynamic evolution of the clinical signs of encephalopathy. We propose to address this gap with quantitative physiological biomarkers to aid in stratification of the disease severity. The objectives of this prospective cohort study were to measure the electroencephalographic (EEG) power as an objective biomarker of the evolution of the clinical encephalopathy in newborns with mild to severe HIE.

METHODS

EEG was collected in infants with HIE using four bipolar electrodes analyzed for the first three hours of the recording. Delta power (DP, 0.5 to 4 Hz) and total power (TP, 0.5 to 20 Hz) were compared between groups with different HIE severity using a univariate ordinal logistic regression model and receiver operating characteristic curves.

RESULTS

A total of 44 term-born infants with mild to severe HIE were identified within six hours of birth. The DP and TP values were significantly higher for the mild group than for the moderate group for all bipolar electrodes. A one-unit increase in DP was associated with significantly lower odds of encephalopathy. DP best distinguished mild from higher encephalopathy grades by area under the curve.

CONCLUSIONS

We conclude that DP and TP are sensitive real-time biomarkers for monitoring the dynamic evolution of the encephalopathy severity in the first day of life. The quantitative EEG power may lead to timely recognition of the worsening of the encephalopathy and guide future therapeutic interventions targeting mild HIE.

Short-term outcomes in infants with mild neonatal encephalopathy: a retrospective, observational study

BACKGROUND

Neonatal encephalopathy due to acute perinatal asphyxia is a major cause of perinatal brain damage. Moderate to severe neonatal encephalopathy is associated with high mortality and morbidity rates. However, the neurodevelopmental outcomes in neonates with mild neonatal encephalopathy are unclear. The primary aim of this single-center observational study was to assess the short-term outcomes in term neonates with mild neonatal encephalopathy due to perinatal asphyxia. A secondary aim was to identify predictors of poor prognosis by identifying the characteristics of these infants according to their short-term outcomes.

METHODS

We retrospectively investigated all infants with perinatal asphyxia at Tokyo Metropolitan Children's Medical Center from January 2014 to December 2019. An abnormal short-term outcome was defined as any one of the following: seizures or abnormal electroencephalography, abnormal brain magnetic resonance imaging obtained within the first 4 weeks of life, and abnormal neurological examination findings at discharge.

RESULTS

In total, 110 term infants with perinatal asphyxia during the study period were screened and 61 were diagnosed with mild neonatal encephalopathy. Eleven (18 %) of these infants had an abnormal short-term outcome. The median Thompson score at admission was significantly higher in infants with abnormal short-term outcomes than in those with normal short-term outcomes (5 [interquartile range, 4-5.5] vs. 2 [interquartile range, 1-3], p < 0.01). Receiver operating characteristic curve analysis showed that a cutoff value of 4 had high sensitivity and specificity (90.9 and 83.0 %, respectively) for prediction of an abnormal short-term outcome.

CONCLUSIONS

18 % of infants with mild encephalopathy had an abnormal short-term outcome, such as abnormal brain magnetic resonance imaging findings. The Thompson score at admission may be a useful predictor of an abnormal short-term outcome in infants with mild neonatal encephalopathy.

MRI Score Ability to Detect Abnormalities in Mild Hypoxic-Ischemic Encephalopathy

BACKGROUND

Magnetic resonance imaging (MRI) scores have been well validated in moderate/severe hypoxic-ischemic encephalopathy (HIE). Infants with mild HIE can have different patterns of injury, yet different scores have not been compared in this group of infants. Our objective was to compare the ability of three = MRI scores to detect abnormalities in infants with mild HIE, and infants with moderate/severe HIE were included for comparison.

METHODS

This is a single-center prospective cohort study of infants ≥36 weeks' gestation with HIE born at a level III neonatal intensive care unit from 2017 to 2019. All infants with HIE underwent an MRI, but only infants with moderate/severe HIE underwent therapeutic hypothermia. At least two experienced MRI readers who were unaware of all clinical variables independently assigned three scores (Barkovich, NICHD NRN, and Weeke).

RESULTS

A total of 42 newborns with varying HIE severity underwent MRI on day five of life. In the overall cohort, abnormalities were reported in three (7%) infants using the Barkovich, in 10 (24%) using the NICHD NRN, and in 24 (57%) using the Weeke score. Agreement was excellent for each score: Barkovich score (k = 1.0), NICHD NRN (k = 0.92), and Weeke score (k = 0.9).

CONCLUSIONS

Subtle injury due to mild HIE was detected with the highest frequency using the Weeke score, while inter-rater reliability was excellent for all three scores. These findings suggest that infants with mild HIE and subtle MRI abnormalities may benefit from detailed scoring systems, which is important for studies investigating the benefit of hypothermia in mild HIE.

Is there a role for therapeutic hypothermia administration in term infants with mild neonatal encephalopathy?

OBJECTIVE

Identifying term infants presenting with early mild neonatal encephalopathy (NE) as candidates for therapeutic hypothermia (TH) remains unclear. Study objectives were to characterize the neonatal clinical, magnetic resonance imaging (MRI), and longer-term outcome in infants with mild NE treated with TH.

STUDY DESIGN

Retrospective cohort study of infants admitted with mild or moderate NE treated with TH. Enrollment criteria included a sentinel event, severe acidosis, DR interventions, and low Apgar scores.

RESULTS

Infants with mild (n = 11) and moderate NE (n = 37) received TH. Mild NE findings included hyperalertness (64%), hypotonia (73%), high level sensory response (91%); 64% progressed to moderate NE. Infants with mild vs. moderate NE had less severe MRI changes (0 vs. 16%) and no cerebral palsy (CP) (0 vs. 13%).

CONCLUSIONS

Outcomes were favorable with mild NE whereas four infants with moderate NE developed CP. A potential role for TH in this population requires further study.

The development of neonatal neurointensive care

Brain injury remains one of the major unsolved problems in neonatal care, with survivors at high risk of lifelong neurodisability. It is unlikely that a single intervention can ameliorate neonatal brain injury, given the complex interaction between pathological processes, developmental trajectory, genetic susceptibility, and environmental influences. However, a coordinated, interdisciplinary approach to understand the root cause enables early detection, and diagnosis with enhanced clinical care offering the best chance of improving outcomes and facilitate new lines of neuroprotective treatments. Adult neurointensive care has existed as a speciality in its own right for over 20 years; however, it is only recently that large prospective studies have demonstrated the benefit of this model of care. The 'Neuro-intensive Care Nursery' model originated at the University of California San Francisco in 2008, and since then a growing number of units worldwide have adopted this approach. As well as providing consistent coordinated care for infants from a multidisciplinary team, it provides opportunities for specialist education and training in neonatal neurology, neuromonitoring, neuroimaging and nursing. This review outlines the origins of brain-oriented care of the neonate and the development of the Neuro-NICU (neonatal intensive care unit) and discusses some of the challenges and opportunities in expanding this model of care.

A Total Sarnat Score in Mild Hypoxic-ischemic Encephalopathy Can Detect Infants at Higher Risk of Disability

To define mild hypoxic-ischemic encephalopathy and distinguish infants at risk of disability in the first 6 hours, this study stratified risk of disability by using early neurologic examination findings of infants enrolled in the Prospective Research for Infants with Mild Encephalopathy cohort. A total Sarnat score of ≥5 when performed at <6 hours of age detected future disability. TRIAL REGISTRATION: Clinicaltrials.gov: NCT01747863.

Vitamin D as an Adjuvant Therapy in Neonatal Hypoxia: Is it Beneficial?

Background

Neonatal hypoxic ischemic encephalopathy (HIE) is a potentially devastating disorder associated with significant mortality and long-term morbidity.

Objective

The aim of this study was to study the role of vitamin D as an adjuvant therapy for management of neonatal HIE.

Patients and Methods

This study was carried out on 60 neonates with HIE grade II who were diagnosed according to modified Sarnat staging and were divided in to 2 groups: Group I: Included 30 neonates with Sarnat grade II HIE who received single daily oral dose of vitamin D3 (1000 IU) for 2 weeks in addition to daily subcutaneous (SC) human recombinant erythropoietin (2500 IU/kg) for 5 days and IM or IV magnesium sulphate 250 mg/kg within half an hour of birth, and subsequently 125 mg/kg at 24 and 48 hours of life. Group II: Included 30 neonates with HIE grade II who received erythropoietin and magnesium sulphate as group I but without vitamin D. Two blood samples were taken from all neonates included in both groups; the 1^st at diagnosis and the 2^nd after 2 weeks of therapy. This study included also 30 healthy neonates as a control group. All neonates included in this study were subjected to: complete clinical examination with assessment of Apgar score at 5 and 10 minutes, measurement of arterial blood gases and serum 25 (OH) vitamin D, calcium, phosphorus, S100-B and IL-17 levels.

Results

Before therapy, there were no significant differences between group I and II in PH, PO2 and PCO2 (p= 0.294, 0.462, 0.758 respectively), but after 2 weeks of therapy, there were significantly higher PH levels in group I compared with group II (p <0.001) while there were no significant differences between group I and II regarding PO2 and PCO2. Before therapy, there were no significant differences in serum 25(OH) vitamin D levels between group I and II while there were significantly lower serum 25(OH) vitamin D levels in group I and II compared with controls (P1; comparison between group I and II = 0.742, P2; comparison between group I and controls = 0.001 and P3; comparison between group II and controls = 0. 001). There were no significant differences between group I and II and between group I and II and control as regard serum calcium (P1= 0.943, P2= 0.875 and P3= 0.764) and phosphorus (P1= 0.862, P2= 0.921, P3= 0.786). There were no significant differences between group I and II regarding serum IL-17 levels while there were significantly lower serum IL-17 levels in group I and II compared with controls (P1 = 0.457, P2 = 0.043 and P3 = 0.023). Before therapy, there were no significant differences in serum S100-B levels between group I and II while there were significantly higher serum S100-B levels in group I and II compared with control (P1 = 0.381, P2 = 0.001 and P3= 0.001) but after therapy, there were significantly higher S100-B levels in group II compared with group I and significantly higher S100-B levels in group I and II compared with control (P1= 0.001, P2= 0.043, P3 = 0.001). There were significant negative correlations in group I between serum S100-B and PH and between S100-B and serum vitamin D before and after therapy.

Conclusion

Vitamin D was found to improve the cases of group I as demonstrated by the reduction of serum S100-B levels after vitamin D therapy.

Recommendations

Extensive multicenter studies are required on a large number of patients with Sarnat grade II HIE with longer duration of follow up to give valid recommendations about the use of vitamin D as an adjuvant therapy in Sarnat grade II HIE.

Current Practice of Therapeutic Hypothermia for Mild Hypoxic Ischemic Encephalopathy

CONTEXT

Therapeutic hypothermia is the recommended treatment for neonates with moderate or severe hypoxic ischemic encephalopathy (HIE). There is an increasing trend to use therapeutic hypothermia even in infants with mild hypoxic ischemic encephalopathy, even though there is little evidence to support/refute this.

OBJECTIVE

To estimate the incidences of mild hypoxic ischemic encephalopathy among infants who received therapeutic hypothermia, and its short- and long-term outcomes.

DATA SOURCES AND STUDY SELECTION

PubMed, Embase, CINAHL, and Cochrane library were searched to identify observational studies reporting on therapeutic hypothermia in term and near-term infants with mild hypoxic ischemic encephalopathy. The JBI (Joanna Briggs Institute) tools were used to assess the risk of bias in the included studies. Random effects meta-analysis was conducted to find out the percentage of cooled infants who had only mild hypoxic ischemic encephalopathy.

RESULTS

A total of 3590 citations were screened, of which 13 were included. Of the 2783 infants who received therapeutic hypothermia, 573 had mild hypoxic ischemic encephalopathy. Meta-analysis found that 22% of the infants who underwent therapeutic hypothermia had only mild hypoxic ischemic encephalopathy (95% confidence interval: 16%-27%; I² statistic = 90.5%). Five studies provided information on adverse effects of therapeutic hypothermia in mild hypoxic ischemic encephalopathy. The reported adverse effects were extreme hypothermia, bradycardia, hypoglycemia, sepsis, skin necrosis, pulmonary hypertension, and systemic hypotension. Limitation: The limitations included relatively small sample size and the lack of data for short- and long-term neurodevelopmental outcome.

CONCLUSIONS

A significant proportion of infants who received therapeutic hypothermia had mild hypoxic ischemic encephalopathy. Randomized trials are urgently needed to evaluate the efficacy and safety of therapeutic hypothermia in infants with mild hypoxic ischemic encephalopathy.

Should therapeutic hypothermia be offered to babies with mild neonatal encephalopathy in the first 6 h after birth?

Infants with moderate to severe neonatal encephalopathy (NE) benefit significantly from therapeutic hypothermia, with reduced risk of death or disability. However, the need for therapeutic hypothermia for infants with milder NE remains unclear. It has been suggested that these infants should not be offered therapeutic hypothermia as they may not be at risk for adverse neurodevelopmental outcome and that the balance of risk against potential benefit is unknown. Several key questions need to be answered including first, whether one can define NE in the first 6 h after birth so as to accurately distinguish infants with brain injury who may be at risk for adverse neurodevelopmental consequences. Second, will treatment of infants with mild NE with therapeutic hypothermia improve or even worsen neurological outcomes? Although alternate treatment protocols for mild NE may be feasible, the use of the current approach combined with rigorous avoidance of hyperthermia and initiation of hypothermia as early as possible after birth may promote optimal outcomes. Animal experimental data support the potential for greater benefit for mild HIE compared with moderate to severe HIE. This review will summarize current knowledge of mild NE and the challenges to a trial in this population.

Prospective research in infants with mild encephalopathy identified in the first six hours of life: neurodevelopmental outcomes at 18-22 months

BACKGROUND

Studies of early childhood outcomes of mild hypoxic-ischemic encephalopathy (HIE) identified in the first 6 h of life are lacking.

OBJECTIVE

To evaluate neurodevelopmental outcomes at 18-22 months of PRIME study.

STUDY DESIGN

Multicenter, prospective study of mild HIE defined as ≥1 abnormality using the modified Sarnat within 6 h of birth and not meeting cooling criteria. Primary outcome was disability with mild: Bayley III cognitive 70-84 or ≥85 and either Gross Motor Function Classification System (GMFCS) 1 or 2, seizures, or hearing deficit; moderate: cognitive 70-84 and either GMFCS 2, seizures, or hearing deficit; severe: cognitive <70, GMFCS 3-5.

RESULTS

Of the 63 infants enrolled, 51 (81%) were evaluated at 19 ± 2 months and 43 (68%) completed Bayley III. Of the 43 infants, 7 (16%) were diagnosed with disability, including 1 cerebral palsy and 2 autism. Bayley scores < 85 in either cognition, motor, or language were detected in 17 (40%): 14 (32%) language, 7 (16%) cognitive, and 6 (14%) motor domain. Infants with disability had more abnormalities on discharge examination and brain MRI, with longer hospital stay (p < 0.001).

CONCLUSIONS

In this contemporary untreated cohort of mild HIE, disability occurred in 16% of infants at 18-22 months.