Predictive value of neonatal MRI showing no or minor degrees of brain injury after hypothermia

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.

Relationship between EEG spectral power and dysglycemia with neurodevelopmental outcomes after neonatal encephalopathy

OBJECTIVE

We investigated how electroencephalography (EEG) quantitative measures and dysglycemia relate to neurodevelopmental outcomes following neonatal encephalopathy (NE).

METHODS

This retrospective study included 90 neonates with encephalopathy who received therapeutic hypothermia. EEG absolute spectral power was calculated during post-rewarming and 2-month follow-up. Measures of dysglycemia (hypoglycemia, hyperglycemia, and glycemic lability) and glucose variability were computed for the first 48 h of life. We evaluated the ability of EEG and glucose measures to predict neurodevelopmental outcomes at ≥ 18 months, using logistic regressions (with area under the receiver operating characteristic [AUROC] curves).

RESULTS

The post-rewarming global delta power (average all electrodes), hyperglycemia and glycemic lability predicted moderate/severe neurodevelopmental outcome separately (AUROC = 0.8, 95%CI [0.7,0.9], p < .001) and even more so when combined (AUROC = 0.9, 95%CI [0.8,0.9], p < .001). After adjusting for NE severity and magnetic resonance imaging (MRI) brain injury, only global delta power remained significantly associated with moderate/severe neurodevelopmental outcome (odds ratio [OR] = 0.9, 95%CI [0.8,1.0], p = .04), gross motor delay (OR = 0.9, 95%CI [0.8,1.0], p = .04), global developmental delay (OR = 0.9, 95%CI [0.8,1.0], p = .04), and auditory deficits (OR = 0.9, 95%CI [0.8,1.0], p = .03).

CONCLUSIONS

In NE, global delta power post-rewarming was predictive of outcomes at ≥ 18 months.

SIGNIFICANCE

EEG markers post-rewarming can aid prediction of neurodevelopmental outcomes following NE.

Insights from serial magnetic resonance imaging in neonatal encephalopathy in term infants

BACKGROUND

Limited serial neuroimaging studies use magnetic resonance imaging (MRI) to define the evolution of hypoxic-ischemic insults to the brain of term infants and encompass both the primary injury and its secondary impact on cerebral development. The optimal timing of MRI to fully evaluate the impact of hypoxic-ischemic encephalopathy on brain development and associated neurodevelopmental sequelae remains unknown.

METHODS

Goals: (a) review literature related to serial neuroimaging in term infants with HIE; (b) describe pilot data in two infants with HIE treated with therapeutic hypothermia who had a brain injury at day 3-5 and underwent four additional MRIs over the next 12 weeks of life and developmental evaluation at 24 months of age.

RESULTS

Early MRI defines primary injury on diffusion-weighted imaging, yet the full impact may not be fully apparent until after 1 month of life.

CONCLUSION

The full impact of an ischemic injury on the neonatal brain may not be fully visible until several weeks after the initial insult. This suggests the benefit of obtaining later time points for MRI to fully define the extent of injury and its neurodevelopmental impact.

IMPACT

Few studies inform the nature of the evolution of brain injury with hypothermia in HIE, limiting understanding of potential neuroprotection. MRI is the standard of care for prognosis in infants with HIE, however timing for optimal prognostic prediction remains unclear. Insights from MRI after the first week of life may assist in defining the full extent of brain injury and prognostic significance. A pilot study using five MRI timepoints up to 3 months of age, is presented. More data is required with a systematic evaluation of the impact of early brain injury on brain development in term infants with HIE following TH.

How well does neonatal neuroimaging correlate with neurodevelopmental outcomes in infants with hypoxic-ischemic encephalopathy?

BACKGROUND

In newborns with hypoxic-ischemic encephalopathy (HIE), the correlation between neonatal neuroimaging and the degree of neurodevelopmental impairment (NDI) is unclear.

METHODS

Infants with HIE enrolled in a randomized controlled trial underwent neonatal MRI/MR spectroscopy (MRS) using a harmonized protocol at 4-6 days of age. The severity of brain injury was measured with a validated scoring system. Using proportional odds regression, we calculated adjusted odds ratios (aOR) for the associations between MRI/MRS measures of injury and primary ordinal outcome (i.e., normal, mild NDI, moderate NDI, severe NDI, or death) at age 2 years.

RESULTS

Of 451 infants with MRI/MRS at a median age of 5 days (IQR 4.5-5.8), outcomes were normal (51%); mild (12%), moderate (14%), severe NDI (13%); or death (9%). MRI injury score (aOR 1.06, 95% CI 1.05, 1.07), severe brain injury (aOR 39.6, 95% CI 16.4, 95.6), and MRS lactate/n-acetylaspartate (NAA) ratio (aOR 1.6, 95% CI 1.4,1.8) were associated with worse primary outcomes. Infants with mild/moderate MRI brain injury had similar BSID-III cognitive, language, and motor scores as infants with no injury.

CONCLUSION

In the absence of severe injury, brain MRI/MRS does not accurately discriminate the degree of NDI. Given diagnostic uncertainty, families need to be counseled regarding a range of possible neurodevelopmental outcomes.

IMPACT

Half of all infants with hypoxic-ischemic encephalopathy (HIE) enrolled in a large clinical trial either died or had neurodevelopmental impairment at age 2 years despite receiving therapeutic hypothermia. Severe brain injury and a global pattern of brain injury on MRI were both strongly associated with death or neurodevelopmental impairment. Infants with mild or moderate brain injury had similar mean BSID-III cognitive, language, and motor scores as infants with no brain injury on MRI. Given the prognostic uncertainty of brain MRI among infants with less severe degrees of brain injury, families should be counseled regarding a range of possible neurodevelopmental outcomes.

The Use of Contrast-Enhanced Ultrasound (CEUS) in the Evaluation of the Neonatal Brain

In recent years, advancements in technology have allowed the use of contrast-enhanced ultrasounds (CEUS) with high-frequency transducers, which in turn, led to new possibilities in diagnosing a variety of diseases and conditions in the field of radiology, including neonatal brain imaging. CEUSs overcome some of the limitations of conventional ultrasounds (US) and Doppler USs. It allows the visualization of dynamic perfusion even in the smallest vessels in the whole brain and allows the quantitative analysis of perfusion parameters. An increasing number of articles are published on the topic of the use of CEUSs on children each year. In the area of brain imaging, the CEUS has already proven to be useful in cases with clinical indications, such as hypoxic-ischemic injuries, stroke, intracranial hemorrhages, vascular anomalies, brain tumors, and infections. We present and discuss the basic principles of the CEUS and its safety considerations, the examination protocol for imaging the neonatal brain, and current and emerging clinical applications.

Development of a composite diffusion tensor imaging score correlating with short-term neurological status in neonatal hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is the most common cause of neonatal acquired brain injury. Although conventional MRI may predict neurodevelopmental outcomes, accurate prognostication remains difficult. As diffusion tensor imaging (DTI) may provide an additional diagnostic and prognostic value over conventional MRI, we aimed to develop a composite DTI (cDTI) score to relate to short-term neurological function. Sixty prospective neonates treated with therapeutic hypothermia (TH) for HIE were evaluated with DTI, with a voxel size of 1 × 1 × 2 mm. Fractional anisotropy (FA) and mean diffusivity (MD) from 100 neuroanatomical regions (FA/MD *100 = 200 DTI parameters in total) were quantified using an atlas-based image parcellation technique. A least absolute shrinkage and selection operator (LASSO) regression was applied to the DTI parameters to generate the cDTI score. Time to full oral nutrition [short-term oral feeding (STO) score] was used as a measure of short-term neurological function and was correlated with extracted DTI features. Seventeen DTI parameters were selected with LASSO and built into the final unbiased regression model. The selected factors included FA or MD values of the limbic structures, the corticospinal tract, and the frontotemporal cortices. While the cDTI score strongly correlated with the STO score (rho = 0.83, p = 2.8 × 10-16), it only weakly correlated with the Sarnat score (rho = 0.27, p = 0.035) and moderately with the NICHD-NRN neuroimaging score (rho = 0.43, p = 6.6 × 10-04). In contrast to the cDTI score, the NICHD-NRN score only moderately correlated with the STO score (rho = 0.37, p = 0.0037). Using a mixed-model analysis, interleukin-10 at admission to the NICU (p = 1.5 × 10-13) and tau protein at the end of TH/rewarming (p = 0.036) and after rewarming (p = 0.0015) were significantly associated with higher cDTI scores, suggesting that high cDTI scores were related to the intensity of the early inflammatory response and the severity of neuronal impairment after TH. In conclusion, a data-driven unbiased approach was applied to identify anatomical structures associated with some aspects of neurological function of HIE neonates after cooling and to build a cDTI score, which was correlated with the severity of short-term neurological functions.

Increase of Parkin and ATG5 plasmatic levels following perinatal hypoxic-ischemic encephalopathy

Brain injury at birth is an important cause of neurological and behavioral disorders. Hypoxic-ischemic encephalopathy (HIE) is a critical cerebral event occurring acutely or chronically at birth with high mortality and morbidity in newborns. Therapeutic strategies for the prevention of brain damage are still unknown, and the only medical intervention for newborns with moderate-to-severe HIE is therapeutic hypothermia (TH). Although the neurological outcome depends on the severity of the initial insult, emerging evidence suggests that infants with mild HIE who are not treated with TH have an increased risk for neurodevelopmental impairment; in the current clinical setting, there are no specific or validated biomarkers that can be used to both correlate the severity of the hypoxic insult at birth and monitor the trend in the insult over time. The aim of this work was to examine the presence of autophagic and mitophagic proteins in bodily fluids, to increase knowledge of what, early at birth, can inform therapeutic strategies in the first hours of life. This is a prospective multicentric study carried out from April 2019 to April 2020 in eight third-level neonatal intensive care units. All participants have been subjected to the plasma levels quantification of both Parkin (a protein involved in mitophagy) and ATG5 (involved in autophagy). These findings show that Parkin and ATG5 levels are related to hypoxic-ischemic insult and are reliable also at birth. These observations suggest a great potential diagnostic value for Parkin evaluation in the first 6 h of life.

Outcome Prediction and Inter-Rater Comparison of Four Brain Magnetic Resonance Imaging Scoring Systems of Infants with Perinatal Asphyxia and Therapeutic Hypothermia

INTRODUCTION

The brain magnetic resonance imaging (MRI) result is a major predictor for the outcome of term infants with perinatal asphyxia who underwent therapeutic hypothermia. In daily practice, no uniform method is used to assess these images.

PURPOSE

The aim of this study was to determine which MRI-score best predicts adverse outcome at 24 months of age and has the highest inter-rater reliability.

METHODS

Four MRI scoring systems for term infants with perinatal asphyxia were selected: Rutherford score, Trivedi score, Weeke score, and NICHD NRN score. Experienced blinded raters retrospectively evaluated the brain MR Images of 161 infants using all four scoring systems. Long-term outcome (the composite outcome death or adverse outcome, and its separate components) were routinely assessed by standardized testing at the age of 24 months. The predictive accuracy was assessed by logistic regression analyses and expressed as area under the ROC curve (AUC). The inter-rater reliability of the scores was calculated by the weighted Kappa or intraclass correlation. A sensitivity analysis using only high-quality MRI scans was performed.

RESULTS

All four MRI scoring systems demonstrated an AUC of >0.66 for the prediction of adverse outcome and ≥0.80 for the prediction of death. The inter-rater reliability analyses demonstrated the highest reliability for the Weeke and Trivedi scores. When only assessing the high-quality scans, the AUC increased further.

CONCLUSION

All four MRI brain scores proved reliable predictors for an adverse outcome at 24 months of age. The Weeke and Trivedi score demonstrated the highest inter-rater reliability. The use of high-quality MRI further improved prediction.

Alterations in motor functional connectivity in Neonatal Hypoxic Ischemic Encephalopathy

BACKGROUND

Neonatal hypoxic-ischemic encephalopathy (HIE) is the result of global hypoxic-ischemic brain injury in neonates due to asphyxia during birth and is one of the most common causes of severe, long-term neurologic deficits in children. Methods: Resting state fMRI (rs-fMRI) was used to assess potential functional disruptions in the primary and association motor areas in HIE neonates (n = 16) compared to healthy controls (n = 11).

RESULTS

Results demonstrate reduced intra-hemispheric resting state functional connectivity (rs-FC) between primary motor regions (upper extremity and facial motor regions) as well as reduced inter-hemispheric rs-FC in the HIE group. In addition, HIE neonates demonstrated increased rs-FC between motor regions and frontal, temporal and parietal cortices but decreased rs-FC with the cerebellum.

DISCUSSION

These preliminary results provide initial evidence for the disruption of functional communication with the motor network in neonates with HIE. Further studies are necessary to both validate these findings in a larger dataset as well as to determine if rs-fMRI measurements collected at birth may have the potential to serve as a prognostic marker in addition to the traditional combination of clinical measurements and conventional MRI.

Comparison of numerical and standard sarnat grading using the NICHD and SIBEN methods

OBJECTIVE

The NICHD and SIBEN assessments are adapted from the Sarnat grade, and used to determine severity of neonatal encephalopathy (NE). We compare NICHD and SIBEN methods, and their ability to define a minimum threshold associated with significant cerebral injury.

STUDY DESIGN

Between 2016 and 2019, 145 infants with NE (77-mild; 65-moderate; 3-severe) were included. NICHD and SIBEN grade and numerical scores were assigned. Kappa scores described agreement between methods, and ROC curves their ability to predict MR injury.

RESULTS

Good agreement existed between grading systems (K = 0.86). SIBEN defined more infants as moderate, and less as mild, than NICHD (p < 0.001). Both numerical scores were superior to standard grades in predicting MR injury.

CONCLUSION

Despite good agreement between methods, SIBEN defines more infants as moderate NE. Both numerical scores were superior to standard grade, and comparable to each other, in defining a minimum threshold for cerebral injury. Further assessment contrasting their predictive ability for long-term outcome is required.

Relationship Between MRI Scoring Systems and Neurodevelopmental Outcome at Two Years in Infants With Neonatal Encephalopathy

BACKGROUND

Magnetic resonance imaging (MRI) scoring systems are used in the neonatal period to predict outcome in infants with neonatal encephalopathy. Our aim was to assess the relationship between three MRI scores and neurodevelopmental outcome assessed using Bayley Scales of Infant and Toddler Development, third edition (Bayley-III), at two years in infants with neonatal encephalopathy.

METHODS

Term-born neonates with evidence of perinatal asphyxia born between 2011 and 2015 were retrospectively reviewed. MRI scanning was performed within the first two weeks of life and scored using Barkovich, National Institute of Child Health and Human Development (NICHD) Neonatal Research Network (NRN), and Weeke systems by a single assessor blinded to the infants clinical course. Neurodevelopmental outcome was assessed using composite scores on the Bayley-III at two years. Multiple linear regression analyses were used to assess the association between MRI scores and Bayley-III composite scores, with postmenstrual age at scan and sex included as covariates.

RESULTS

Of the 135 recruited infants, 90 infants underwent MRI, and of these, 66 returned for follow-up. MRI abnormalities were detected with the highest frequency using the Weeke score (Barkovich 40%, NICHD NRN 50%, Weeke 77%). The inter-rater agreement was good for the Barkovich score and excellent for NICHD NRN and Weeke scores. There was a significant association between Barkovich, NICHD NRN, and Weeke scores and Bayley-III cognitive and motor scores. Only the Weeke score was associated with Bayley-III language scores.

CONCLUSIONS

Our findings confirm the predictive value of existing MRI scoring systems for cognitive and motor outcome and suggest that more detailed scoring systems have predictive value for language outcome.

Wavelet-based neurovascular coupling can predict brain abnormalities in neonatal encephalopathy

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is a leading cause of morbidity and mortality in neonates, but quantitative methods to predict outcomes early in their course of illness remain elusive. Real-time physiologic biomarkers of neurologic injury are needed in order to predict which neonates will benefit from therapies. Neurovascular coupling (NVC) describes the correlation of neural activity with cerebral blood flow, and the degree of impairment could predict those at risk for poor outcomes.

OBJECTIVE

To determine if neurovascular coupling (NVC) calculated in the first 24-hours of life based on wavelet transform coherence analysis (WTC) of near-infrared spectroscopy (NIRS) and amplitude-integrated electroencephalography (aEEG) can predict abnormal brain MRI in neonatal HIE.

METHODS

WTC analysis was performed between dynamic oscillations of simultaneously recorded aEEG and cerebral tissue oxygen saturation (SctO2) signals for the first 24 h after birth. The squared cross-wavelet coherence, R2, of the time-frequency domain described by the WTC, is a localized correlation coefficient (ranging between 0 and 1) between these two signals in the time-frequency domain. Statistical analysis was based on Monte Carlo simulation with a 95% confidence interval to identify the time-frequency areas from the WTC scalograms. Brain MRI was performed on all neonates and classified as normal or abnormal based on an accepted classification system for HIE. Wavelet metrics of % significant SctO2-aEEG coherence was compared between the normal and abnormal MRI groups.

RESULT

This prospective study recruited a total of 36 neonates with HIE. A total of 10 had an abnormal brain MRI while 26 had normal MRI. The analysis showed that the SctO2-aEEG coherence between the group with normal and abnormal MRI were significantly different (p = 0.0007) in a very low-frequency (VLF) range of 0.06-0.2 mHz. Using receiver operating characteristic (ROC) curves, the use of WTC-analysis of NVC had an area under the curve (AUC) of 0.808, and with a cutoff of 10% NVC. Sensitivity was 69%, specificity was 90%, positive predictive value (PPV) was 94%, and negative predictive value (NPV) was 52% for predicting brain injury on MRI. This was superior to the clinical Total Sarnat score (TSS) where AUC was 0.442 with sensitivity 61.5%, specificity 30%, PPV 75%, and NPV 31%.

CONCLUSION

NVC is a promising neurophysiological biomarker in neonates with HIE, and in our prospective cohort was superior to the clinical Total Sarnat score for prediction of abnormal brain MRI.

Blood Plasma Metabolic Profile of Newborns with Hypoxic-Ischaemic Encephalopathy by GC-MS

Background

Early diagnosis of hypoxic-ischaemic encephalopathy (HIE) is crucial in preventing neurodevelopmental disabilities and reducing morbidity and mortality. The study was to investigate the plasma metabolic signatures in the peripheral blood of HIE newborns and explore the potential diagnostic biomarkers.

Method

In the present study, 24 newborns with HIE and 24 healthy controls were recruited. The plasma metabolites were measured by gas chromatography-mass spectrometry (GC-MS), and the raw data was standardized by the EigenMS method. Significantly differential metabolites were identified by multivariate statistics. Pathway enrichment was performed by bioinformatics analysis. Meanwhile, the diagnostic value of candidate biomarkers was evaluated.

Result

The multivariate statistical models showed a robust capacity to distinguish the HIE cases from the controls. 52 metabolites were completely annotated. 331 significantly changed pathways were enriched based on seven databases, including 33 overlapped pathways. Most of them were related to amino acid metabolism, energy metabolism, neurotransmitter biosynthesis, pyrimidine metabolism, the regulation of HIF by oxygen, and GPCR downstream signaling. 14 candidate metabolites showed great diagnostic potential on HIE. Among them, alpha-ketoglutaric acid has the potential to assess the severity of HIE in particular.

Conclusion

The blood plasma metabolic profile could comprehensively reflect the metabolic disorders of the whole body under hypoxia-ischaemic injury. Several candidate metabolites may serve as promising biomarkers for the early diagnosis of HIE. Further validation based on large clinical samples and the establishment of guidelines for the clinical application of mass spectrometry data standardization methods are imperative in the future.

Early Versus Late Brain Magnetic Resonance Imaging after Neonatal Hypoxic Ischemic Encephalopathy Treated with Therapeutic Hypothermia

OBJECTIVE

To evaluate the agreement in brain injury findings between early and late magnetic resonance imaging (MRI) in newborn infants with hypoxic-ischemic encephalopathy treated with therapeutic hypothermia and to compare the ability of early vs late MRI to predict early neurodevelopmental outcomes.

STUDY DESIGN

This was a prospective longitudinal study of 49 patients with hypoxic-ischemic encephalopathy who underwent therapeutic hypothermia and had MRI performed at both <7 and ≥7 days of age. MRIs were reviewed by an experienced neuroradiologist and assigned brain injury severity scores according to established systems. Scores for early and late MRIs were assessed for agreement using the kappa statistic. The ability of early and late MRI scores to predict death or developmental delay at 15-30 months of age was assessed by logistic regression analyses.

RESULTS

Agreement between the early and late MRI was substantial to near perfect (k > 0.75, P < .001) across MRI scoring systems. In cases of discrepant scoring, early MRI was more likely to identify severe injury when compared with late MRI. Early MRI scores were more consistently predictive of adverse outcomes compared with late MRI.

CONCLUSIONS

The results of this study suggest that a single MRI performed in the first week after birth is adequate to assess brain injury and offer prognostic information in this high-risk population.

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.

Limitations of Conventional Magnetic Resonance Imaging as a Predictor of Death or Disability Following Neonatal Hypoxic-Ischemic Encephalopathy in the Late Hypothermia Trial

OBJECTIVE

To investigate if magnetic resonance imaging (MRI) is an accurate predictor for death or moderate-severe disability at 18-22 months of age among infants with neonatal encephalopathy in a trial of cooling initiated at 6-24 hours.

STUDY DESIGN

Subgroup analysis of infants ≥36 weeks of gestation with moderate-severe neonatal encephalopathy randomized at 6-24 postnatal hours to hypothermia or usual care in a multicenter trial of late hypothermia. MRI scans were performed per each center's practice and interpreted by 2 central readers using the Eunice Kennedy Shriver National Institute of Child Health and Human Development injury score (6 levels, normal to hemispheric devastation). Neurodevelopmental outcomes were assessed at 18-22 months of age.

RESULTS

Of 168 enrollees, 128 had an interpretable MRI and were seen in follow-up (n = 119) or died (n = 9). MRI findings were predominantly acute injury and did not differ by cooling treatment. At 18-22 months, death or severe disability occurred in 20.3%. No infant had moderate disability. Agreement between central readers was moderate (weighted kappa 0.56, 95% CI 0.45-0.67). The adjusted odds of death or severe disability increased 3.7-fold (95% CI 1.8-7.9) for each increment of injury score. The area under the curve for severe MRI patterns to predict death or severe disability was 0.77 and the positive and negative predictive values were 36% and 100%, respectively.

CONCLUSIONS

MRI injury scores were associated with neurodevelopmental outcome at 18-22 months among infants in the Late Hypothermia Trial. However, the results suggest caution when using qualitative interpretations of MRI images to provide prognostic information to families following perinatal hypoxia-ischemia.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT00614744.

Regional heterogeneity of cerebral hemodynamics in mild neonatal encephalopathy measured with multichannel near-infrared spectroscopy

BACKGROUND

Neuromonitoring at the bedside is the key to understand the pathophysiological mechanisms of brain injury associated with neonatal encephalopathy. The current practice is to monitor the forehead using a noninvasive cerebral oximetry-it remains unknown to what extent cerebral hemodynamics in other brain regions is different to the frontal region.

METHOD

A multichannel near-infrared spectroscopy (NIRS) system was used to monitor neonates (n = 14) with fetal acidosis and mild neonatal encephalopathy at four brain regions (the frontal, posterior, left temporal, and right temporal lobes). The data were compared to delineate the regional difference in (1) cerebral hemodynamics and (2) pressure autoregulation. For both analyses, wavelet transform coherence was applied.

RESULTS

We observed frontal-posterior heterogeneity as indicated by significantly lower coherence between these two regions (p = 0.02). Furthermore, areas with regional magnetic resonance imaging (MRI)-detected lesions showed greater hemodynamic variations compared to non-affected areas (p = 0.03), while cerebral autoregulation was not affected and showed no difference.

CONCLUSION

Cerebral hemodynamics in mild neonatal encephalopathy is heterogeneous across different brain regions, while cerebral autoregulation remains intact. These findings indicate the robustness of the wavelet measure of cerebral autoregulation in this population, but need to be further investigated in the presence of severe injury.

IMPACT

This proof-of-concept study is the first to investigate the regional difference of cerebral hemodynamics and autoregulation in mild neonatal encephalopathy. Study findings confirm that brain functions are complex in the developing neonatal brain and that cerebral hemodynamics are region specific in newborns with frontal-posterior heterogeneity among brain regions probed by multichannel NIRS. Regional MRI lesions were associated with differences across NIRS regional channels among the affected side. Cerebral autoregulation with multichannel NIRS is not affected by regional MRI abnormalities.

Brain Contrast-Enhanced Ultrasound Evaluation of a Pediatric Swine Model

ABSTRACT

Brain injury remains a leading cause of morbidity and mortality in children. We evaluated the feasibility of using a pediatric swine model to develop contrast-enhanced ultrasound (CEUS)-based measures of brain perfusion for clinical application in various types of brain injury monitoring. Six-week-old, 10-kg swine (N = 10) were anesthetized, and an acoustic window was created in the right frontal cranium to provide visualization of an oblique coronal plane and bilateral thalami. Ultrasound contrast agent was administered via a femoral venous catheter as a weight-based (0.03 mL/kg) bolus. After localization of the imaging plane, CEUS cine clips were acquired for 90 seconds. Bolus injection of contrast agent provided global visualization of cerebral perfusion and highlighted microvasculature in the brain. Preliminary evaluation of bolus kinetics in piglets showed a central gray nuclei-to-cortex ratio similar to human infants with a steep wash-in that crossed and remained above the 1.0 threshold for most of the enhancement period. We demonstrated the similarity in brain perfusion between piglets and human infants, specifically central gray nuclei-to-cortex ratio, showing preliminary feasibility of its use as a pediatric model of brain perfusion. Contrast-enhanced ultrasound can be performed at the bedside as a minimally invasive procedure, and quantitative CEUS may provide critical information regarding changes in brain perfusion as a result of injury or as a response to therapy.

The prognosis of brain magnetic resonance imaging injury pattern for outcomes of hypothermia-treated infants

Magnetic resonance imaging (MRI) can be a tool that allows the observation of structural injury patterns after cooling. The aim of this study was to determine the early pattern of brain injury in the MRIs of infants with hypoxic ischemic encephalopathy (HIE) after cooling and to search for any clinical factors related to abnormal MRI findings.The study retrospectively recruited 118 infants who were treated with therapeutic hypothermia (TH) between 2013 and 2016.Forty-three patients had normal brain MRI, and 75 had abnormal brain MRI findings. The TH-treated infants with abnormal brain MRI readings showed significantly more clinical seizures and the use of additional antiepileptic drugs (AEDs) than the normal MRI group. As a long-term outcome, more lesions in the basal ganglia and thalamus, posterior limb of internal capsule, or severe white matter lesions were associated with abnormal neurodevelopmental outcomes at 18 to 24 months of age.A higher frequency of clinical seizures and AED use were related to abnormal brain injury on MRI. A significant risk for poor long-term outcomes was found in the abnormal brain MRI group.

DTI parameters in neonates with hypoxic-ischemic encephalopathy after total body hypothermia

BACKGROUND AND PURPOSE

MR imaging provides means for discriminating different patterns of Hypoxic-ischemic encephalopathy (HIE) and may distinguish most severe cases from less severe but is unable to predict long-term outcome. Diffusion tensor imaging (DTI) offers information for a more complete characterization of HIE. The purpose of this study is to compare the modifications of DTI parameters in newborns one week and six months following total-body cooling to healthy controls.

METHODS

Forty-seven cooled newborns were studied with MRI, 20 underwent follow-up at 6 months. 12 healthy newborns and nine children at 6 months were enrolled as control groups (HC). Inferior Longitudinal Fasciculus (ILF), Corpus Callosum Fasciculus (CCF), Corticospinal Tract (CST), Optical Tract (OT), Optic Radiation (OR) were generated in all subjects. DTI parameters were evaluated in basal ganglia (BG), thalamus (TH) and tracks. Statistical analysis was performed with MANOVA.

RESULTS

In newborns HIE versus HC, there were significantly lower fractional anisotropy (FA) on OR and CST and higher axial diffusivity (AD), apparent diffusion coefficient (ADC) and radial diffusivity (RD) values on CST, BG and TH in HIE-N. At 6 months there were no significant grouping effects. The analysis showed a significant increase of FA, decrease of ADC, AD, RD after 6 months for HIE and HC.

CONCLUSIONS

We observed modifications of parameter values in HIE newborns vs HC; however normalization of values at 6 months suggests that changes of parameters cannot be considered early biomarkers for evaluation of therapeutic hypothermia in newborns with moderate HIE and normal conventional MRI.

Abnormalities in evoked potentials associated with abnormal glycemia and brain injury in neonatal hypoxic-ischemic encephalopathy

OBJECTIVE

To investigate how functional integrity of ascending sensory pathways measured by visual and somatosensory evoked potentials (VEP & SEP) is associated with abnormal glycemia and brain injury in newborns treated with hypothermia for hypoxic-ischemic encephalopathy (HIE).

METHODS

Fifty-four neonates ≥ 36 weeks gestational age with HIE underwent glucose testing, VEPs, SEPs, and magnetic resonance imaging (MRI) the first week of life. Minimum and maximum glucose values recorded prior to evoked potential (EP) testing were compared with VEP and SEP measures using generalized estimating equations. Relationships between VEP and SEP measures and brain injury on MRI were assessed.

RESULTS

Maximum glucose is associated with decreased P200 amplitude, and increased odds that N300 peak will be delayed/absent. Minimum glucose is associated with decreased P22 amplitude. Presence of P200 and N300 peaks is associated with decreased odds of brain injury in the visual processing pathway, with delayed/absent N300 peak associated with increased odds of brain injury in posterior white matter.

CONCLUSIONS

Deviations from normoglycemia are associated with abnormal EPs, and abnormal VEPs are associated with brain injury on MRI in cooled neonates with HIE.

SIGNIFICANCE

Glucose is a modifiable risk factor associated with atypical brain function in neonates with HIE despite hypothermia treatment.

In clinical practice, cerebral MRI in newborns is highly predictive of neurodevelopmental outcome after therapeutic hypothermia

OBJECTIVE

In the trials, a substantial proportion of newborns who underwent therapeutic hypothermia (TH) had an adverse outcome after hypoxic-ischaemic encephalopathy (HIE). Cooled babies were noted to have fewer cerebral lesions on MRI but when present lesions were predictive of adverse outcome. We investigate the predictive value of cerebral MRI in babies who undergo cooling in the clinical setting outside of the clinical trials in a prospective UK cohort.

RESULTS

Of 75 babies recruited from four centres, neurodevelopment was available for 69 (92%) with 29% (20/69) being abnormal. The unfavourable MRI group (n = 22) had significantly lower motor (p < 0.001), language (p < 0.001) and cognition (p < 0.001) scores on Bayley-III assessment, compared to the favourable MRI group (n = 47). On multiple regression there was a significant relationship between basal ganglia and thalami abnormality and motor (p = 0.002), cognition (p = 0.011) and language (p = 0.013) outcomes. Half of the babies who had an MRI predictive of adverse outcome (11/22) had highest grade cerebral palsy. Cerebral MRI had 95% sensitivity, 94% specificity, 91% PPV and 98% NPV in predicting neurodevelopment.

CONCLUSIONS

In this clinical cohort, fewer children had adverse neurodevelopment after TH compared to the TH trials. However, half the children who had an MRI predictive of adverse ND outcome had the most severe form of cerebral palsy. In this cohort, cerebral MRI was found to be highly predictive of neurodevelopmental outcome.

Prognostic role of acute kidney injury on long-term outcome in infants with hypoxic-ischemic encephalopathy

BACKGROUND

The objective of this study was to evaluate the prognostic role of postnatal acute kidney injury (AKI) on neurodevelopmental outcome in infants with hypoxic-ischemic encephalopathy (HIE) receiving therapeutic hypothermia (TH).

METHODS

This is a prospective observational study including all neonates with HIE receiving TH between 2009 and 2016 at a single center. AKI was classified according to the Kidney Disease: Improving Global Outcomes definition modified for neonatal age. Child development was assessed using the Griffiths Mental Development Scales (GMDS). Study outcome was defined as unfavorable outcome (including death or disability according to GMDS) or favorable otherwise, at 12 and 24 months.

RESULTS

One-hundred and one neonates (median gestational age 39 weeks) were included. AKI was diagnosed in 10 neonates (10%). Seven patients died within the first year, 35 patients had disability at 12 months, and 45 patients at 24 months. AKI was associated with increased likelihood of unfavorable outcome at 24 months (100% vs. 59% in neonates without AKI; p = 0.01). AKI showed good positive predictive value (1.00, 95% CI 0.71-1.00) and specificity (1.00, 95% CI 0.88-1.00), but poor negative predictive value (0.41, 95% CI 0.30-0.52) and sensitivity (0.19, 95% CI 0.11-0.32) at 24 months.

CONCLUSIONS

AKI might be a reliable indicator of death or long-term disability in infants with HIE receiving TH, but the absence of AKI does not guarantee a favorable long-term outcome.

Cerebral Pulsed Arterial Spin Labeling Perfusion Weighted Imaging Predicts Language and Motor Outcomes in Neonatal Hypoxic-Ischemic Encephalopathy

Rationale and Objectives: To compare cerebral pulsed arterial spin labeling (PASL) perfusion among controls, hypoxic ischemic encephalopathy (HIE) neonates with normal conventional MRI(HIE/MRI⊕), and HIE neonates with abnormal conventional MRI(HIE/MRI⊖). To create a predictive machine learning model of neurodevelopmental outcomes using cerebral PASL perfusion. Materials and Methods: A total of 73 full-term neonates were evaluated. The cerebral perfusion values were compared by permutation test to identify brain regions with significant perfusion changes among 18 controls, 40 HIE/MRI⊖ patients, and 15 HIE/MRI⊕ patients. A machine learning model was developed to predict neurodevelopmental outcomes using the averaged perfusion in those identified brain regions. Results: Significantly decreased PASL perfusion in HIE/MRI⊖ group, when compared with controls, were found in the anterior corona radiata, caudate, superior frontal gyrus, precentral gyrus. Both significantly increased and decreased cerebral perfusion changes were detected in HIE/MRI⊕ group, when compared with HIE/MRI⊖ group. There were no significant perfusion differences in the cerebellum, brainstem and deep structures of thalamus, putamen, and globus pallidus among the three groups. The machine learning model demonstrated significant correlation (p < 0.05) in predicting language(r = 0.48) and motor(r = 0.57) outcomes in HIE/MRI⊖ patients, and predicting language(r = 0.76), and motor(r = 0.53) outcomes in an additional group combining HIE/MRI⊖ and HIE/MRI⊕. Conclusion: Perfusion MRI can play an essential role in detecting HIE regardless of findings on conventional MRI and predicting language and motor outcomes in HIE survivors. The perfusion changes may also reveal important insights into the reperfusion response and intrinsic autoregulatory mechanisms. Our results suggest that perfusion imaging may be a useful adjunct to conventional MRI in the evaluation of HIE in clinical practice.

Early Post-cooling Brain Magnetic Resonance for the Prediction of Neurodevelopmental Outcome in Newborns with Hypoxic-Ischemic Encephalopathy

Aim and Objectives:

This study aimed to evaluate the predictive role of early post-cooling brain magnetic resonance for developmental outcome in newborns with hypoxic–ischemic encephalopathy.

Materials and Methods:

A retrospective cohort study was performed on 29 consecutive patients through magnetic resonance evaluation (visual analysis of the images and scoring of the detected lesions; mean diffusivity of semioval centre and lenticular nuclei; and area under the curve of basal ganglia N-acetylaspartate at proton magnetic resonance spectroscopic imaging) and Griffiths Mental Development Scales–third edition at 12 and 24 months.

Results:

Brain magnetic resonance was performed at a mean age of 5.7 ± 3.7 days. Newborns with no/minor magnetic resonance abnormalities had a better developmental outcome than patients with moderate or severe lesions. Structural and spectroscopic abnormalities in basal ganglia resulted in the most significant predictors for an unfavorable outcome.

Conclusion:

Normal magnetic resonance in early post-cooling phases is strongly associated with a favorable developmental outcome.

Ultrasound Predicts White Matter Integrity after Hypothermia Therapy in Neonatal Hypoxic-Ischemic Injury

BACKGROUND

Hypoxic-ischemic injury (HII) is a major cause of neonatal death and neurodevelopmental disability. Head ultrasounds (HUS) in neonates with HII often show enhanced gray/white matter differentiation. We assessed the significance of this finding in predicting white matter structural integrity measured by diffusion tensor imaging (DTI) in neonates with HII.

METHODS

We performed a quantitative region of interest-based analysis of white and gray matter echogenicity within the cingulate gyrus on pre- and posthypothermia HUS. We also completed a quantitative analysis of fractional anisotropy (FA) and mean (MD), axial (AD), and radial (RD) diffusivity within the bilateral anterior and posterior centrum semiovale (CSO) on posthypothermia brain magnetic resonance imaging. For HUS studies, we calculated a white-to-gray matter echogenicity ratio (WGR) and subsequently correlated it to DTI measurements.

RESULTS

Forty-two term neonates with HII who underwent hypothermia therapy were included. Significant correlation was found between prehypothermia WGR and MD, AD, and RD values in the left anterior CSO (r = .38-.40, P = .02). Prehypothermia WGR also correlated with the following: MD and RD in the right anterior CSO (r = .35-.36, P = .04), MD and AD in the right posterior CSO (r = .32-.45, P = .008-.03), and AD in the left posterior CSO (r = .47, P = .005). No significant correlation was found either between prehypothermia WGR and FA values in the bilateral anterior and posterior CSO or between posthypothermia WGR and all DTI scalars in the bilateral anterior and posterior CSO.

CONCLUSIONS

Prehypothermia HUS WGR may predict posthypothermia white matter structural integrity and is potentially an early and easily obtainable biomarker of severity in neonatal HII.

WITHDRAWN: In clinical practice, cerebral MRI in newborns is highly predictive of neurodevelopmental outcome after therapeutic hypothermia

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Early proton magnetic resonance spectroscopy during and after therapeutic hypothermia in perinatal hypoxic-ischemic encephalopathy

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) remains a significant cause of mortality and neurodevelopmental impairment despite treatment with therapeutic hypothermia. Magnetic resonance H¹-spectroscopy measures concentrations of cerebral metabolites to detect derangements in aerobic metabolism.

OBJECTIVE

We assessed MR spectroscopy in neonates with HIE within 18-24 h of initiating therapeutic hypothermia and at 5-6 days post therapeutic hypothermia.

MATERIALS AND METHODS

Eleven neonates with HIE underwent MR spectroscopy of the basal ganglia and white matter. We compared metabolite concentrations during therapeutic hypothermia and post-therapeutic hypothermia and between moderate and severe HIE.

RESULTS

During therapeutic hypothermia, neonates with severe HIE had decreased basal ganglia N-acetylaspartate (NAA; 0.62±0.08 vs. 0.72±0.05; P=0.02), NAA + N-acetylaspartylglutamate (NAAG; 0.66±0.11 vs. 0.77±0.06; P=0.05), glycerophosphorylcholine + phosphatidylcholine (GPC+PCh; 0.28±0.05 vs. 0.38±0.06; P=0.02) and decreased white matter GPC+PCh (0.35±0.13 vs. 0.48±0.04; P=0.02) compared to neonates with moderate HIE. For all subjects, basal ganglia NAA decreased (-0.08±0.07; P=0.01), whereas white matter GPC+PCh increased (0.03±0.04; P=0.04) from therapeutic hypothermia MRI to post-therapeutic-hypothermia MRI. All metabolite values are expressed in mmol/L.

CONCLUSION

Decreased NAA and GPC+PCh were associated with greater HIE severity and could distinguish neonates who might benefit most from targeted additional neuroprotective therapies.

Circulating blood cellular glucose transporters - Surrogate biomarkers for neonatal hypoxic-ischemic encephalopathy assessed by novel scoring systems

OBJECTIVE

We examined Red Blood Cell (RBC) Glucose Transporter isoform 1 (GLUT1) and White Blood Cell (WBC) Glucose Transporter isoform 3 (GLUT3) protein concentrations to assess their potential as surrogate biomarkers for the presence of hypoxic-ischemic encephalopathy (HIE) and response to therapeutic hypothermia (TH), with respect to the neurodevelopmental prognosis.

STUDY DESIGN

A prospective feasibility study of 10 infants with HIE and 8 age-matched control subjects was undertaken. Following parental consent, blood samples were obtained at baseline before institution of TH (<6 h of life), during TH, at rewarming and post-TH in the HIE group with a baseline sample from the control group. GLUT1 and GLUT3 were measured by Enzyme-linked immunosorbent assay (ELISA) with brain biomarkers, Neuron-Specific Enolase (NSE) and Glial Fibrillary Acidic Protein (GFAP). Novel "HIE-high risk" and "Neurological" scores were developed to help identify HIE and to assess severity and prognosis, respectively.

RESULTS

RBC GLUT1 concentrations were increased at the baseline pre-TH time point in HIE versus control subjects (p = .006), normalizing after TH (p = .05). An association between GLUT1 and NSE concentrations (which was reflective of the HIE-high risk and the Neuro-scores) in controls and HIE pre-TH was seen (R² = 0.36, p = .008), with GLUT1 demonstrating 90% sensitivity and 88% specificity for presence of HIE identified by Sarnat Staging. WBC GLUT3 concentrations were low and no different in HIE versus control, and GFAP concentrations trended higher during re-warming (p = .11) and post-TH (p = .16). We demonstrated a significant difference between HIE and controls for both the "HIE-high risk" and the "Neurological" Scores. The latter score revealing the severity of clinical neurological illness correlated with the corresponding RBC GLUT1 (R² value = 0.39; p = .006).

CONCLUSION

Circulating RBC GLUT1 concentrations with NSE demonstrate a significant potential in reflecting the severity of HIE pre-TH and gauging effectiveness of TH. In contrast, the low neonatal WBC GLUT3 concentrations make discerning differences between degrees of HIE as well as assessing effectiveness of TH difficult. The HIE-high risk and Neurological scores may extend the "Sarnat staging" towards assessing severity and neuro-developmental prognosis of HIE.

Neonatal Encephalopathy: Current Management and Future Trends

It is well-documented in the literature that infants who suffer from hypoxic ischemic encephalopathy are at high risk for neurologic sequelae or even death. With the addition of therapeutic hypothermia into the treatment regimen for neonatal hypoxic ischemic encephalopathy, newborns afflicted with hypoxic ischemic encephalopathy were given the opportunity for a better outcome. Questions linger as to the most optimal treatment strategy of therapeutic hypothermia for these newborns. The goal of this article is to discuss current management strategies, as well as future trends, for infants with hypoxic ischemic encephalopathy.

Electroencephalography and brain magnetic resonance imaging in asphyxia comparing cooled and non-cooled infants

OBJECTIVE

The aim was to establish any differences in the predictive value of EEG and MRI for outcome in infants treated and not-treated with therapeutic hypothermia (HT) for perinatal asphyxia. We hypothesize that they are equally predictive and that combining both has the highest predictive value.

STUDY DESIGN

We retrospectively compared data of infants with hypoxic-ischemic encephalopathy (HIE) who received HT (n = 45) between September 2009 and December 2013 with those of infants with HIE born between January 2004 and August 2009, before HT was available (NT, n = 37). All received conventional and/or amplitude-integrated EEG during the first days and early MRI (day 4-5). Associations of EEG, MRI and severe neurodevelopmental outcome (death or Bayley's -2SD below mean), were tested with a multivariable logistic regression analysis, corrected for HT.

RESULTS

Forty-eight hours' EEG background pattern had a PPV of 92% and a NPV of 81% in HT, versus 100% and 58% in NT. MRI had a PPV of 71% and a NPV of 93% in HT, versus 82% and 75% in NT. The adjusted OR for adverse outcome was 0.013 (95% CI 0.002-0.154, p < 0.001) for EEG background normalization within 48 h and 32.19 (95% CI 4.84-214.25, p < 0.001) for abnormal MRI.

CONCLUSION

The predictive value of EEG and MRI is equal in cooled and non-cooled infants with HIE. Our data show a higher predictive value (death and severe outcome) for EEG compared to MRI. In HIE, persistent abnormal EEG background pattern until 48 h, combined with abnormal early MRI is strongly predictive for poor neurodevelopment.

The Role of Diffusion Tensor Imaging in Detecting Hippocampal Injury Following Neonatal Hypoxic-Ischemic Encephalopathy

BACKGROUND AND PURPOSE

Neonatal hypoxic-ischemic injury of the brain and resultant encephalopathy (HIE) leads to major developmental impairments by school age. Conventional/anatomical MRI often fails to detect hippocampal injury in mild cases. We hypothesize that diffusion tensor imaging (DTI) has greater sensitivity for identifying subtle hippocampal injury.

METHODS

We retrospectively analyzed DTI data collected from a cohort of neonates with HIE and controls. Conventional MRI sequences were classified qualitatively according to severity using a modified Barkovich scale. Using multivariate linear regression, we compared hippocampal DTI scalars of HIE patients and controls. Spearman correlation was used to test the association of DTI scalars in the hippocampal and thalamic regions. A multiple regression analysis tested the association of the DTI scalars with short-term outcomes.

RESULTS

Fifty-five neonates with HIE (42% males) and 13 controls (54% males) were included. Hippocampal DTI scalars were similar between HIE and control groups, even when restricting the HIE group to those with moderate-to-severe injury (8 subjects). DTI scalars of the thalamus were significantly lower in the moderate-to-severely affected patients compared to controls (right fractional anisotropy [FA] .148 vs. .182, P = .01; left FA .147 vs. .181, P = .03). Hippocampal and thalamic DTI scalars were correlated (P < .001). Hippocampal DTI scalars were not associated with short-term outcomes.

CONCLUSIONS

Quantitative DTI analysis of the hippocampus in neonates following HIE is a feasible technique to examine neuronal injury. Although DTI scalars were useful in identifying thalamic injury in our cohort, hippocampal DTI analysis did not provide additional information regarding hippocampal injury following HIE.

Body Temperature, Heart Rate, and Short-Term Outcome of Cooled Infants

Therapeutic hypothermia following neonatal encephalopathy is neuroprotective. However, approximately one in two cooled infants still die or develop permanent neurological impairments. Further understanding of variables associated with the effectiveness of cooling is important to improve the therapeutic regimen. To identify clinical factors associated with short-term outcomes of cooled infants, clinical data of 509 cooled infants registered to the Baby Cooling Registry of Japan between 2012 and 2014 were evaluated. Independent variables of death during the initial hospitalization and survival discharge from the cooling hospital at ≤28 days of life were assessed. Death was associated with higher Thompson scores at admission (p < 0.001); higher heart rates after 3-72 hours of cooling (p < 0.001); and higher body temperature after 24 hours of cooling (p = 0.002). Survival discharge was associated with higher 10 minutes Apgar scores (p < 0.001); higher blood pH and base excess (both p < 0.001); lower Thompson scores (at admission and after 24 hours of cooling; both p < 0.001); lower heart rates at initiating cooling (p = 0.003) and after 24 hours of cooling (p < 0.001) and lower average values after 3-72 hours of cooling (p < 0.001); higher body temperature at admission (p < 0.001); and lower body temperature after 24 hours and lower mean values after 3-72 hours of cooling (both p < 0.001). Survival discharge was best explained by higher blood pH (p < 0.05), higher body temperature at admission (p < 0.01), and lower body temperature and heart rate after 24 hours of cooling (p < 0.01 and <0.001, respectively). Lower heart rate, higher body temperature at admission, and lower body temperature during cooling were associated with favorable short-term outcomes.

Evoked potentials predict psychomotor development in neonates with normal MRI after hypothermia for hypoxic-ischemic encephalopathy

OBJECTIVES

To assess the prognostic role of evoked potentials (EP) in neonates with normal magnetic resonance imaging (MRI) after therapeutic hypothermia (TH) for hypoxic-ischemic encephalopathy (HIE).

METHODS

Thirty-five neonates recruited for TH because of HIE, having normal neonatal MRI, performed neonatal somatosensory (SEP), visual (VEP) evoked potentials and electroencephalogram (EEG). The effect of SEP, VEP or EEG abnormalities on Griffith's developmental scales at 12 and 24 months was measured; positive (PPV) and negative (NPV) predictive value, sensitivity, specificity and accuracy were calculated.

RESULTS

At 24 months, 28% had global psychomotor impairment and 57% had isolated impairments. VEP abnormality was associated with impaired hearing-language score (p = 0.002) and performance score (p < 0.0001). VEP achieved best PPV (0.91, 95% C.I. 0.62-0.99) and specificity (0.93, 95% C.I. 0.70-0.99). The combination of neurophysiological tests achieved the best NPV (0.85, 95% C.I. 0.58-0.96), sensitivity (0.90, 95% C.I. 0.70-0.97), overall accuracy (0.83, 95% C.I. 0.67-0.92).

CONCLUSIONS

Psychomotor sequelae may occur in survivors of neonatal HIE with normal MRI. VEP is the single best neurophysiological prognostic marker but the combination of neurophysiological tests has a better value.

SIGNIFICANCE

When facing the challenge of neurodevelopmental prognosis in infants with normal MRI after TH, EPs are useful prognostic tools, complementary to EEG.

Evaluating a Targeted Bedside Measure of Cerebral Perfusion in a Nonhuman Primate Model of Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVES

To compare ultrasound-derived resistive indices (RIs) obtained at the level of the thalamus via fast Doppler ultrasound with traditional anterior cerebral artery measures in a model of neonatal hypoxic-ischemic encephalopathy and to correlate each with clinical outcomes.

METHODS

Nine nonhuman primate neonates underwent no umbilical cord occlusion (n = 3), umbilical cord occlusion without hypothermia (n = 3), or umbilical cord occlusion with hypothermia (n = 3). The RI was measured in the anterior cerebral artery and thalamus on days 0, 1, and 4 of life. Magnetic resonance imaging with spectroscopy was performed on day 4.

RESULTS

Mean thalamus and anterior cerebral artery RI values in the first 36 hours of life were statistically different in neonates who died (+0.13; P = .019) or developed cerebral palsy (-0.08; P = .003). Thalamic RI values showed stronger associations with serum and spectroscopic lactate values than those in the anterior cerebral artery. The umbilical cord occlusion-with-hypothermia group showed a significant increase in the RI in the thalamus but not the anterior cerebral artery.

CONCLUSIONS

Resistive index measurements in the thalamus may eventually supplement other bedside measures for predicting outcomes in the HIE population, but further studies need to differentiate the effect of hypothermia from illness severity on thalamic perfusion.

Prospective research on infants with mild encephalopathy: the PRIME study

OBJECTIVE

To determine short-term outcomes of infants with evidence of hypoxia-ischemia at birth and classified as mild neonatal encephalopathy (NE) at <6 h of age.

STUDY DESIGN

Prospective multicenter study. Mild NE was defined as ⩾1 abnormal category in modified Sarnat score. Primary outcome was any abnormality on early amplitude integrated electroencephalogram (aEEG) or seizures, abnormal brain magnetic resonance imaging (MRI) or neurological exam at discharge.

RESULTS

A total of 54/63 (86%) of enrolled infants had data on components of the primary outcome, which was abnormal in 28/54 (52%): discontinuous aEEG (n=4), MRI (n=9) and discharge exam (n=22). Abnormal tone and/or incomplete Moro were the most common findings. MRI abnormalities were confined to cerebral cortex but two infants had basal ganglia and/or thalamus involvement. The 18 to 24 months follow-up is ongoing.

CONCLUSIONS

A larger than expected proportion of mild NE infants with abnormal outcomes was observed. Future research should evaluate safety and efficacy of neuroprotection for mild NE.

Therapeutic hypothermia for neonates with hypoxic ischemic encephalopathy

Therapeutic hypothermia (TH) is a recommended regimen for newborn infants who are at or near term with evolving moderate-to-severe hypoxic ischemic encephalopathy (HIE). The Task Force of the Taiwan Child Neurology Society and the Taiwan Society of Neonatology held a joint meeting in 2015 to establish recommendations for using TH on newborn patients with HIE. Based on current evidence and experts' experiences, this review article summarizes the key points and recommendations regarding TH for newborns with HIE, including: (1) selection criteria for TH; (2) choices of method and equipment for TH; (3) TH prior to and during transport; (4) methods for temperature maintenance, monitoring, and rewarming; (5) systemic care of patients during TH, including the care of respiratory and cardiovascular systems, management of fluids, electrolytes, and nutrition, as well as sedation and drug metabolism; (6) monitoring and management of seizures; (7) neuroimaging, prognostic factors, and outcomes; and (8) adjuvant therapy for TH.

Management and investigation of neonatal encephalopathy: 2017 update

This review discusses an approach to determining the cause of neonatal encephalopathy, as well as current evidence on resuscitation and subsequent management of hypoxic-ischaemic encephalopathy (HIE). Encephalopathy in neonates can be due to varied aetiologies in addition to hypoxic-ischaemia. A combination of careful history, examination and the judicious use of investigations can help determine the cause. Over the last 7 years, infants with moderate to severe HIE have benefited from the introduction of routine therapeutic hypothermia; the number needed to treat for an additional beneficial outcome is 7 (95% CI 5 to 10). More recent research has focused on optimal resuscitation practices for babies with cardiorespiratory depression, such as delayed cord clamping after establishment of ventilation and resuscitation in air. Around a quarter of infants with asystole at 10 min after birth who are subsequently cooled have normal outcomes, suggesting that individualised decision making on stopping resuscitation is needed, based on access to intensive treatment unit and early cooling. The full benefit of cooling appears to have been exploited in our current treatment protocols of 72 hours at 33.5°C; deeper and longer cooling showed adverse outcome. The challenge over the next 5-10 years will be to assess which adjunct therapies are safe and optimise hypothermic brain protection in phase I and phase II trials. Optimal care may require tailoring treatments according to gender, genetic risk, injury severity and inflammatory status.

Neurologic Injury in Acidemic Term Infants

Objective To determine whether arterial umbilical cord gas (aUCG) pH, in anatomically normal-term infants, could select infants at risk for brain injury identified on magnetic resonance imaging (MRI). Study Design We performed a nested case-control within a prospective cohort of 8,580 women. Cases, with an aUCG pH < 7.10, were temporally, age, and sex matched to controls with an aUCG pH ≥ 7.20. Bi- and multivariable analyses compared the presence and severity of brain injury. Secondary analyses estimated whether elevated arterial base excess or lactate were associated with brain injury. Results Fifty-five cases were matched to 165 controls. There was no statistical difference in brain injury between the groups (adjusted odds ratio [aOR]: 1.8, 95% confidence interval [CI]: 0.7-4.4]). Base excess ≥ -8 mEq/L was not significantly associated with brain injury (p = 0.12). There was no increase in risk of injury based on elevation of arterial lactate ≥ 4 mmol ⁄L (p = 1.00). Cases were significantly more likely to have an abnormal score in several domains of the Dubowitz neurologic examination. Conclusion The aUCG acid-base parameters alone are not sufficient clinical markers to identify term infants that might benefit from MRI of the brain to identify injury.

Diffusion Tensor Imaging Detects Occult Cerebellar Injury in Severe Neonatal Hypoxic-Ischemic Encephalopathy

BACKGROUND

Despite the benefits of whole-body hypothermia therapy, many infants with hypoxic-ischemic encephalopathy (HIE) die or have significant long-term neurodevelopmental impairment. Prospectively identifying neonates at risk of poor outcome is essential but not straightforward. The cerebellum is not classically considered to be a brain region vulnerable to hypoxic-ischemic insults; recent literature suggests, however, that the cerebellum may be involved in neonatal HIE. In this study, we aimed to assess the microstructural integrity of cerebellar and linked supratentorial structures in neonates with HIE compared to neurologically healthy neonatal controls.

METHODS

In this prospective cohort study, we performed a quantitative diffusion tensor imaging (DTI) analysis of the structural pathways of connectivity, which may be affected in neonatal cerebellar injury by measuring fractional anisotropy (FA) and mean diffusivity (MD) within the superior, middle, and inferior cerebellar peduncles, dentate nuclei, and thalami. All magnetic resonance imaging (MRI) studies were grouped into 4 categories of severity based on a qualitative evaluation of conventional and advanced MRI sequences. Multivariable linear regression analysis of cerebellar scalars of patients and controls was performed, controlling for gestational age, age at the time of MRI, and HIE severity. Spearman rank correlation was performed to correlate DTI scalars of the cerebellum and thalami.

RESULTS

Fifty-seven (23 females, 40%) neonates with HIE and 12 (6 females, 50%) neonatal controls were included. There were 8 patients (14%) in HIE severity groups 3 and 4 (injury of the basal ganglia/thalamus and/or cortex). Based on a qualitative analysis of conventional and DTI images, no patients had evidence of cerebellar injury. No significant differences between patients and controls were found in the FA and MD scalars. However, FA values of the middle cerebellar peduncles (0.294 vs. 0.380, p < 0.001) and MD values of the superior cerebellar peduncles (0.920 vs. 1.007 × 10-3 mm/s2, p = 0.001) were significantly lower in patients with evidence of moderate or severe injury on MRI (categories 3 and 4) than in controls. In patients, cerebellar DTI scalars correlated positively with DTI scalars within the thalami.

CONCLUSION

Our results suggest that infants with moderate-to-severe HIE may have occult injury of cerebellar white-matter tracts, which is not detectable by the qualitative analysis of neuroimaging data alone. Cerebellar DTI scalars correlate with thalamic measures, highlighting that cerebellar injury is unlikely to occur in isolation and may reflect the severity of HIE. The impact of concomitant cerebellar injury in HIE on long-term neurodevelopmental outcome warrants further study.

MR spectroscopy in children: protocols and pitfalls in non-tumorous brain pathology

Proton nuclear magnetic resonance spectroscopy (MRS) delivers information about cell content and metabolism in a noninvasive manner. The diagnostic strength of MRS lies in its evaluation of pathologies in combination with conventional magnetic resonance imaging (MRI). MRS in children has been most widely used to evaluate brain conditions like tumors, infections, metabolic diseases or learning disabilities and especially in neonates with hypoxic-ischemic encephalopathy. This article reviews some basic theoretical considerations, routine procedures, protocols and pitfalls and will illustrate the range of spectrum alterations occurring in some non-tumorous pediatric brain pathologies.

Wavelet coherence analysis of dynamic cerebral autoregulation in neonatal hypoxic-ischemic encephalopathy

Cerebral autoregulation represents the physiological mechanisms that keep brain perfusion relatively constant in the face of changes in blood pressure and thus plays an essential role in normal brain function. This study assessed cerebral autoregulation in nine newborns with moderate-to-severe hypoxic–ischemic encephalopathy (HIE). These neonates received hypothermic therapy during the first 72 h of life while mean arterial pressure (MAP) and cerebral tissue oxygenation saturation (S_ctO₂) were continuously recorded. Wavelet coherence analysis, which is a time-frequency domain approach, was used to characterize the dynamic relationship between spontaneous oscillations in MAP and S_ctO₂. Wavelet-based metrics of phase, coherence and gain were derived for quantitative evaluation of cerebral autoregulation. We found cerebral autoregulation in neonates with HIE was time-scale-dependent in nature. Specifically, the spontaneous changes in MAP and S_ctO₂ had in-phase coherence at time scales of less than 80 min (< 0.0002 Hz in frequency), whereas they showed anti-phase coherence at time scales of around 2.5 h (~ 0.0001 Hz in frequency). Both the in-phase and anti-phase coherence appeared to be related to worse clinical outcomes. These findings suggest the potential clinical use of wavelet coherence analysis to assess dynamic cerebral autoregulation in neonatal HIE during hypothermia.

•

Cerebral hemodynamics in HIE neonates were continuously recorded in hypothermia.

•

Wavelet coherence can be used to assess dynamic autoregulation in HIE neonates.

•

Wavelet-derived metrics have about 88.9% accuracy in predicting clinical outcomes.

•

Wavelet phase, coherence, and gain are validated against transfer function analysis.

•

Cerebral autoregulation in HIE neonates is time-scale-dependent in a wide range.

Comparison of early and late MRI in neonatal hypoxic-ischemic encephalopathy using three assessment methods

BACKGROUND

There is no consensus on the optimum timing of MRI in neonates with hypoxic-ischemic encephalopathy treated with hypothermia. Reliable early imaging assessment might help managing treatment.

OBJECTIVE

To assess non-random differences between early and late MRI that might influence intensive-care decisions.

MATERIALS AND METHODS

This single-center retrospective study included all asphyxiated term neonates eligible for hypothermia treatment November 2009-July 2012. MRI scans were systematically performed at day 4 (early MRI) and day 11 of life as part of routine protocol. Two experienced pediatric radiologists reviewed both scans according to three assessment methods: a pattern classification, a scoring system and a simplified classification. Agreement between early and late imaging findings was assessed using Cohen's kappa coefficients.

RESULTS

Thirty-three neonates were included. Interobserver agreement was excellent. Early MRI detected all severe injuries. Agreement between early and late MRI was excellent for the simplified classification (κ = 0.82), good for the pattern classification (κ = 0.64), and good to excellent for 3 scores out of 4 in the scoring system (κ = 0.70-0.89).

CONCLUSION

Early MRI may provide valuable information about brain injury to help parents and neonatologists in intensive-care decisions at the end of hypothermia treatment.