White matter injury in term newborns with neonatal encephalopathy

Slow rewarming after hypothermia does not ameliorate white matter injury after hypoxia-ischemia in near-term fetal sheep

BACKGROUND

The optimal rate to rewarm infants after therapeutic hypothermia is unclear. In this study we examined whether slow rewarming after 72 h of hypothermia would attenuate white matter injury.

METHODS

Near-term fetal sheep received sham occlusion (n = 8) or cerebral ischemia for 30 min, followed by normothermia (n = 7) or hypothermia from 3-72 h, with either spontaneous fast rewarming (n = 8) within 1 h, or slow rewarming at ~0.5 °C/h (n = 8) over 10 h. Fetuses were euthanized 7 days later.

RESULTS

Ischemia was associated with loss of total and mature oligodendrocytes, reduced expression of myelin proteins and induction of microglia and astrocytes, compared with sham controls (P < 0.05). Both hypothermia protocols were associated with a significant increase in numbers of total and mature oligodendrocytes, area fraction of myelin proteins and reduced numbers of microglia and astrocytes, compared with ischemia-normothermia (P < 0.05). There was no difference in the number of oligodendrocytes, microglia or astrocytes or expression of myelin proteins between fast and slow rewarming after hypothermia.

CONCLUSION

The rate of rewarming after a clinically relevant duration of hypothermia had no apparent effect on white matter protection by hypothermia after cerebral ischemia in near-term fetal sheep.

IMPACT

Persistent white matter injury is a major contributor to long-term disability after neonatal encephalopathy despite treatment with therapeutic hypothermia. The optimal rate to rewarm infants after therapeutic hypothermia is unclear; current protocols were developed on a precautionary basis. We now show that slow rewarming at 0.5 °C/h did not improve histological white matter injury compared with rapid spontaneous rewarming after a clinically established duration of hypothermia in near-term fetal sheep.

Neonatal well-being and timing of brain injury in persons with cerebral palsy born at term or late preterm

AIM

To describe the distribution of neuroimaging patterns in a term/late preterm population-based cohort with cerebral palsy (CP), ascertain associations between neuroimaging patterns and neonatal well-being, estimate the proportion with antenatal or perinatal timing of neuropathology, and apply this information to the understanding of common mechanisms of brain injury and causal pathways.

METHOD

The cohort for this observational study comprised 1348 persons born between 1999 and 2017 in Victoria, Australia. Using algorithms designed for the study, neonatal well-being and timing of brain injury were tabulated for the whole cohort and across neuroimaging patterns and birth epochs.

RESULTS

Clinical and demographic profiles, neonatal well-being, and timing of brain injury differed across neuroimaging patterns. An estimated 57% of the cohort had a complicated neonatal period. Timing of brain injury was antenatal in 57% and perinatal in 41%. A decrease in the relative proportions of perinatal timing of brain injury was observed over a period when the rates of CP in live births at term decreased.

INTERPRETATION

This study begins to bridge the knowledge gap about causation in CP, moving towards better description of the main mechanisms of brain injury and their contribution within CP cohorts, and facilitating the ability to monitor changes over time and the success of preventive measures.

WHAT THIS PAPER ADDS

In a population-based, term/late preterm cohort with cerebral palsy, 57% had a complicated neonatal period. In the same cohort, 57% had presumed antenatal timing of brain injury. The relative proportion with perinatal injury decreased over time.

Amplitude-Integrated Electroencephalography Evolution and Magnetic Resonance Imaging Injury in Mild and Moderate to Severe Neonatal Encephalopathy

OBJECTIVE

This study aimed to describe the evolution of amplitude-integrated electroencephalography (aEEG) in neonatal encephalopathy (NE) during therapeutic hypothermia (TH) and evaluate the association between aEEG parameters and magnetic resonance imaging (MRI) injury.

STUDY DESIGN

aEEG data of infants who underwent TH were reviewed for background, sleep wake cycling (SWC), and seizures. Conventional electroencephalography (cEEG) background was assessed from the reports. Discordance of background on aEEG and cEEG was defined if there was a difference in the severity of the background. MRI injury (total score ≥ 5) was assessed by using the Weeke scoring system.

RESULTS

A total of 46 infants were included; 23 (50%) with mild NE and 23 (50%) with moderate to severe NE. Comparing mild NE with moderate to severe NE, the initial aEEG background differed with more mild being continuous (70 vs. 52%), with fewer being discontinuous (0 vs. 22%) and flat tracing (0 vs. 4%), whereas burst suppression (4 vs. 4%) and low voltage (26 vs. 18%) did not differ. There was a notably common discordance between the background assessment on cEEG with aEEG in 82% with continuous and 40% low voltage aEEG background. MRI abnormalities were identified in four infants with mild NE and seven infants with moderate to severe NE. MRI injury was associated with aEEG seizures in infants with moderate to severe NE.

CONCLUSION

aEEG seizures are useful to predict MRI injury in moderate to severe NE infants. There is a large discrepancy between aEEG, cEEG, and MRI in neonates treated by TH.

KEY POINTS

· MRI injury was identified in 29% of moderate NE infants and in 50% of severe NE infants.. · aEEG seizures were associated with MRI injury in the moderate to severe NE infants.. · MRI injury was identified in 16% infants with mild NE.. · Mild NE infants with normal aEEG were unlikely to have MRI injury.. · There was a large discrepancy between aEEG, cEEG, and MRI in infants treated by TH..

A role for immunohistochemical stains in perinatal brain autopsies

Identification of central nervous system injury is a critical part of perinatal autopsies; however, injury is not always easily identifiable due to autolysis and immaturity of the developing brain. Here, the role of immunohistochemical stains in the identification of perinatal brain injury was investigated. Blinded semiquantitative scoring of injury was performed on sections of frontal lobe from 76 cases (51 liveborn and 25 stillborn) using H&E, GFAP, Iba-1, and β-APP stains. Digital image analysis was used to quantify GFAP and Iba-1 staining. Commonly observed pathologies included diffuse white matter gliosis (DWMG) and white matter necrosis (WMN). DWMG scores were very similar on H&E and GFAP stains for liveborn subjects. For stillborn subjects, DWMG scores were significantly higher on GFAP stain than H&E. β-APP was needed for identification of WMN in 71.4% of stillborn subjects compared to 15.4% of liveborn subjects. Diffuse staining for Iba-1 within cortex and white matter was positively correlated with subject age. Staining quantification on digital image analysis was highly correlated to semiquantitative scoring. Overall, GFAP and β-APP stains were most helpful in identifying white matter injury not seen on H&E in stillborn subjects. Immunostains may therefore be warranted as an integral part of stillborn brain autopsies.

Effect of gestational age on cerebral lesions in neonatal encephalopathy

OBJECTIVE

To determine the risk on brain lesions according to gestational age (GA) in neonates with neonatal encephalopathy.

DESIGN

Secondary analysis of the prospective national French population-based cohort, Long-Term Outcome of NeonataL EncePhALopathy.

SETTING

French neonatal intensive care units.

PATIENTS

Neonates with moderate or severe neonatal encephalopathy (NE) born at ≥34 weeks' GA (wGA) between September 2015 and March 2017.

MAIN OUTCOME MEASURES

The results of MRI performed within the first 12 days were classified in seven injured brain regions: basal ganglia and thalami, white matter (WM), cortex, posterior limb internal capsule, corpus callosum, brainstem and cerebellum. A given infant could have several brain structures affected. Risk of brain lesion according to GA was estimated by crude and adjusted ORs (aOR).

RESULTS

MRI was available for 626 (78.8%) of the 794 included infants with NE. WM lesions predominated in preterm compared with term infants. Compared with 39-40 wGA neonates, those born at 34-35 wGA and 37-38 wGA had greater risk of WM lesions after adjusting for perinatal factors (aOR 4.0, 95% CI (1.5 to 10.7) and ORa 2.0, 95% CI (1.1 to 3.5), respectively).

CONCLUSION

WM is the main brain structure affected in late-preterm and early-term infants with NE, with fewer WM lesions as GA increases. This finding could help clinicians to estimate prognosis and improve the understanding of the pathophysiology of NE.

TRIAL REGISTRATION NUMBER

NCT02676063, ClinicalTrials.gov.

Association between continuous glucose profile during therapeutic hypothermia and unfavorable outcome in neonates with hypoxic-ischemic encephalopathy209 23-32

BACKGROUND

The detection and management of blood glucose abnormalities in high-risk neonates are crucial for clinical care. The objective of the study was to investigate the continuous glucose profile of hypoxic-ischemic encephalopathy (HIE) patients in the whole-process of therapeutic hypothermia (TH) and its association with clinical and neurological outcomes.

METHOD

In this single-center retrospective study, HIE patients who received both TH and continuous glucose monitoring (CGM) were recruited from March 2016 to September 2021.

RESULTS

Of 47 neonates recruited, 24 had unfavorable outcome. Dysglycemia was most prevalent in the first 24 h of TH, among which hyperglycemia occurred more frequently. CGM showed that the duration, episodes and area under curve (AUC) of hypoglycemia were statistically different in neonates with different outcomes. The occurrence, longer duration, greater AUC of hypoglycemia and an early high coefficient of variation (CV%, CV = SD/mean) were associated with unfavorable outcomes (aOR 26.55 [2.02-348.5], aOR 2.11 [1.08-4.14], aOR 1.80 [1.11-2.91] and aOR respectively), while hyperglycemia was not.

CONCLUSION

During the whole process of TH, hypoglycemia and early unstable glycemic variability were strongly associated with unfavorable outcomes. CGM can instantly detect dysglycemia and facilitate precise glucose management in HIE neonates.

Unequal Cerebral Magnetic Resonance Imaging Changes in Perinatal Hypoxic Ischemic Injury of Term Neonates

BACKGROUND

Perinatal hypoxic ischemic injury (HII) has a higher prevalence in the developing world. One of the primary concepts for suggesting that an imaging pattern reflects a global insult to the brain is when the injury is noted to be bilateral and symmetric in distribution. In the context of HII in term neonates, this is either bilateral symmetric ( a ) peripheral/watershed (WS) injury or ( b ) bilateral symmetric basal-ganglia-thalamus (BGT) pattern, often with the peri-Rolandic and hippocampal injury. Unilateral, asymmetric, or unequal distribution of injury may therefore be misdiagnosed as perinatal arterial ischemic stroke.

OBJECTIVES

We aimed to determine the prevalence of unequal cerebral injury in HII, identify patterns, and determine their relationship with existing classification of HII.

MATERIALS AND METHODS

Review of brain magnetic resonance imaging from a database of children with HII. Reports with any unequal pattern of injury were included and further classified as a unilateral, bilateral asymmetric, or symmetric but unequal degree pattern of HII.

RESULTS

A total of 1213 MRI scans in patients with a diagnosis of HII revealed 156 (13%) with unequal involvement of the hemispheres: unilateral in 2 of 1213 (0.2%) (involvement only in the WS), asymmetric in 48 of 1213 (4%) (WS in 6 [0.5%], BGT in 4 [0.3%], and combined BGT and WS in 38 [3.1%]), and bilateral symmetric but unequal degree in 106 of 1213 (8.7%) (WS in 20 [1.6%], BGT in 17 [1.4%], and combined BGT and WS in 69 [5.7%]).

CONCLUSIONS

The majority of children with cerebral palsy due to HII demonstrate a characteristic bilateral symmetric pattern of injury. In our study, 13% demonstrated an unequal pattern. Differentiation from perinatal arterial ischemic stroke, which is mostly unilateral and distributed typically in the middle cerebral artery territory, should be possible and recognition of the typical BGT or WS magnetic resonance imaging patterns should add confidence to the diagnosis, in such scenarios.

Practical Stepwise Approach to Performing Neonatal Brain MR Imaging in the Research Setting

Magnetic resonance imaging (MRI) is a non-invasive imaging technique that is commonly used for the visualization of newborn infant brains, both for clinical and research purposes. One of the main challenges with scanning newborn infants, particularly when scanning without sedation in a research setting, is movement. Infant movement can affect MR image quality and therewith reliable image assessment and advanced image analysis. Applying a systematic, stepwise approach to MR scanning during the neonatal period, including the use of the feed-and-bundle technique, is effective in reducing infant motion and ensuring high-quality images. We provide recommendations for one such systematic approach, including the step-by-step preparation and infant immobilization, and highlight safety precautions to minimize any potential risks. The recommendations are primarily focused on scanning newborn infants for research purposes but may be used successfully for clinical purposes as well, granted the infant is medically stable. Using the stepwise approach in our local research setting, our success rate of acquiring high-quality, analyzable infant brain MR images during the neonatal period is as high as 91%.

Safety and efficacy of therapeutic hypothermia in neonates with mild hypoxic-ischemic encephalopathy

BACKGROUND

Though there has been an increase in the number of neonates with hypoxic-ischemic encephalopathy (HIE) treated by therapeutic hypothermia (TH) in recent years, the effect of therapeutic hypothermia on mild HIE neonates is still uncertain.

OBJECTIVES

This study aims to explore the safety and efficacy of therapeutic hypothermia in neonates with mild HIE.

METHODS

Retrospectively collected between January 2010 to December 2022 at Children's Hospital of Fudan University, neonates with mild HIE were divided into TH and non-TH groups. Clinical data of the mild HIE neonates and their mothers' general information during pregnancy were collected. SPSS 23.0 was used to compare the general condition, the incidence of adverse events, and efficacy in the two groups.

RESULTS

A total of 71 neonates with mild HIE were included, including 31 in the TH group and 40 in the non-TH group. Compared with the non-TH group, the TH group had significantly lower 5-minute Apgar scores [6 (5-7) points vs. 7 (5-8) points, p = 0.033 ], but a higher rate of tracheal intubation at birth (68%, 21/31 vs. 40%, 16/40, p = 0.02), a higher rate of chest compressions > 30 s (39%, 12/31 vs. 15%, 6/40, p = 0.023), the later initiation enteral feeding [4 (3-4) days vs. 1 (1-2) days, p < 0.001], a higher usage rate of analgesic and sedative drugs (45%, 14/31 vs. 18%, 7/40, p = 0.011) and the longer hospital stay [12.5 (11-14) days vs. 9 (7-13.9) days, p = 0.003]. There was no death in 71 mild HIE neonates. TH group had lower incidence of brain injury (16%, 5/31 vs. 43%, 17/40, p = 0.017) and encephalopathy progression (10%, 3/31 vs. 45%, 18/40, p = 0.001) than the non-TH group. There was no statistical significance in the incidence of adverse events between the two groups.

CONCLUSION

Therapeutic hypothermia can reduce the incidence of brain injury in neonates with mild HIE.

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.

Periventricular Microglia Polarization and Morphological Changes Accompany NLRP3 Inflammasome-Mediated Neuroinflammation after Hypoxic-Ischemic White Matter Damage in Premature Rats

White matter damage (WMD) is a primary cause of cerebral palsy and cognitive impairment in preterm infants, and no effective treatments are available. Microglia are a major component of the innate immune system. When activated, they form typical pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes and regulate myelin development and synapse formation. Therefore, they may play a pivotal role in hypoxic-ischemic (HI) WMD. Herein, we investigated neural inflammation and long-term microglia phenotypic polarization in a neonatal rat model of hypoxia-ischemia-induced WMD and elucidated the underlying pathophysiological processes. We exposed 3-day-old (P3) Sprague-Dawley rats to hypoxia (8% oxygen) for 2.5 hr after unilateral common carotid artery ligation. The activation of NLRP3 inflammatory bodies, microglia M1/M2 polarization, myelination, and synaptic development in our model were monitored 7, 14, and 21 days after birth. In addition, the Morris water maze test was performed on postnatal Day 28. We confirmed myelination disturbance in the periventricular white matter, abnormal synaptic development, and behavioral changes in the periventricular area during the development of HI WMD. In addition, we found an association between the occurrence and development of HI WMD and activation of the NLRP3 inflammasome, microglial M1/M2 polarization, and the release of inflammatory factors. NLRP3 inhibition can play an anti-inflammatory role by inhibiting the differentiation of microglia into the M1 phenotype, thereby improving myelination and synapse formation. In conclusion, microglia are key mediators of the inflammatory response and exhibit continuous phenotypic polarization 7-21 days after HI-induced WMD. This finding can potentially lead to a new treatment regimen targeting the phenotypic polarization of microglia early after HI-induced brain injury.

Foetal Intrapartum Compromise at Term: Could COVID-19 Infection Be Involved? A Case Report

The impact of the SARS-CoV-2 infection on pregnancy has been studied and many reports have been published, mainly focussing on complications and in utero transmission with neonatal consequences. Although the effects of other viruses on foetuses are well known, the impact of maternal COVID-19 during pregnancy is not completely understood. We report a case of acute foetal intrapartum hypoxia without other risk factors than maternal COVID-19 disease 2 weeks previous to birth at term. Placental histological changes suggested that the viral infection could have been the culprit for the unfavourable outcome during labour. The neonate was promptly delivered by Caesarean section. Neonatal intensive care was started, including therapeutic hypothermia. The procedure was successful, the evolution of the neonate was favourable, and she was discharged after 10 days. Follow-up at 2 months of life indicated a normal neurological development but a drop in head growth. The case raises the idea that pregnancies with even mild COVID-19 symptoms may represent the cause of neonate compromise in a low-risk pregnancy. An important follow-up in the neonatal period and infancy is required to identify and treat any subsequent conditions. Further long-term studies are necessary to identify a cause–effect relationship between COVID-19 pregnancies and the whole spectrum of neonatal and infant consequences.

Magnetic Resonance Imaging in (Near-)Term Infants with Hypoxic-Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a major cause of neurological sequelae in (near-)term newborns. Despite the use of therapeutic hypothermia, a significant number of newborns still experience impaired neurodevelopment. Neuroimaging is the standard of care in infants with HIE to determine the timing and nature of the injury, guide further treatment decisions, and predict neurodevelopmental outcomes. Cranial ultrasonography is a helpful noninvasive tool to assess the brain before initiation of hypothermia to look for abnormalities suggestive of HIE mimics or antenatal onset of injury. Magnetic resonance imaging (MRI) which includes diffusion-weighted imaging has, however, become the gold standard to assess brain injury in infants with HIE, and has an excellent prognostic utility. Magnetic resonance spectroscopy provides complementary metabolic information and has also been shown to be a reliable prognostic biomarker. Advanced imaging modalities, including diffusion tensor imaging and arterial spin labeling, are increasingly being used to gain further information about the etiology and prognosis of brain injury. Over the past decades, tremendous progress has been made in the field of neonatal neuroimaging. In this review, the main brain injury patterns of infants with HIE, the application of conventional and advanced MRI techniques in these newborns, and HIE mimics, will be described.

The Effects of In Utero Fetal Hypoxia and Creatine Treatment on Mitochondrial Function in the Late Gestation Fetal Sheep Brain

Near-term acute hypoxia in utero can result in significant fetal brain injury, with some brain regions more vulnerable than others. As mitochondrial dysfunction is an underlying feature of the injury cascade following hypoxia, this study is aimed at characterizing mitochondrial function at a region-specific level in the near-term fetal brain after a period of acute hypoxia. We hypothesized that regional differences in mitochondrial function would be evident, and that prophylactic creatine treatment would mitigate mitochondrial dysfunction following hypoxia; thereby reducing fetal brain injury. Pregnant Border-Leicester/Merino ewes with singleton fetuses were surgically instrumented at 118 days of gestation (dGa; term is ~145 dGA). A continuous infusion of either creatine (n = 15; 6 mg/kg/h) or isovolumetric saline (n = 16; 1.5 ml/kg/h) was administered to the fetuses from 121 dGa. After 10 days of infusion, a subset of fetuses (8 saline-, 7 creatine-treated) were subjected to 10 minutes of umbilical cord occlusion (UCO) to induce a mild global fetal hypoxia. At 72 hours after UCO, the fetal brain was collected for high-resolution mitochondrial respirometry and molecular and histological analyses. The results show that the transient UCO-induced acute hypoxia impaired mitochondrial function in the hippocampus and the periventricular white matter and increased the incidence of cell death in the hippocampus. Creatine treatment did not rectify the changes in mitochondrial respiration associated with hypoxia, but there was a negative relationship between cell death and creatine content following treatment. Irrespective of UCO, creatine increased the proportion of cytochrome c bound to the inner mitochondrial membrane, upregulated the mRNA expression of the antiapoptotic gene Bcl2, and of PCG1-α, a driver of mitogenesis, in the hippocampus. We conclude that creatine treatment prior to brief, acute hypoxia does not fundamentally modify mitochondrial respiratory function, but may improve mitochondrial structural integrity and potentially increase mitogenesis and activity of antiapoptotic pathways.

Brain Magnetic Resonance Imaging Reveals Different Courses of Disease in Pediatric and Adult Cerebral Malaria

BACKGROUND

Cerebral malaria is a common presentation of severe Plasmodium falciparum infection and remains an important cause of death in the tropics. Key aspects of its pathogenesis are still incompletely understood, but severe brain swelling identified by magnetic resonance imaging (MRI) was associated with a fatal outcome in African children. In contrast, neuroimaging investigations failed to identify cerebral features associated with fatality in Asian adults.

METHODS

Quantitative MRI with brain volume assessment and apparent diffusion coefficient (ADC) histogram analyses were performed for the first time in 65 patients with cerebral malaria to compare disease signatures between children and adults from the same cohort, as well as between fatal and nonfatal cases.

RESULTS

We found an age-dependent decrease in brain swelling during acute cerebral malaria, and brain volumes did not differ between fatal and nonfatal cases across both age groups. In nonfatal disease, reversible, hypoxia-induced cytotoxic edema occurred predominantly in the white matter in children, and in the basal ganglia in adults. In fatal cases, quantitative ADC histogram analyses also demonstrated different end-stage patterns between adults and children: Severe hypoxia, evidenced by global ADC decrease and elevated plasma levels of lipocalin-2 and microRNA-150, was associated with a fatal outcome in adults. In fatal pediatric disease, our results corroborate an increase in brain volume, leading to augmented cerebral pressure, brainstem herniation, and death.

CONCLUSIONS

Our findings suggest distinct pathogenic patterns in pediatric and adult cerebral malaria with a stronger cytotoxic component in adults, supporting the development of age-specific adjunct therapies.

Neuroimaging in the term newborn with neonatal encephalopathy

Neuroimaging is widely used to aid in the diagnosis and clinical management of neonates with neonatal encephalopathy (NE). Yet, despite widespread use clinically, there are few published guidelines on neuroimaging for neonates with NE. This review outlines the primary patterns of brain injury associated with hypoxic-ischemic injury in neonates with NE and their frequency, associated neuropathological features, and risk factors. In addition, it provides an overview of neuroimaging methods, including the most widely used scoring systems used to characterize brain injury in these neonates and their utility as predictive biomarkers. Last, recommendations for neuroimaging in neonates with NE are presented.

Evaluating Neuroprotective Effects of Uridine, Erythropoietin, and Therapeutic Hypothermia in a Ferret Model of Inflammation-Sensitized Hypoxic-Ischemic Encephalopathy

Perinatal hypoxic-ischemic (HI) brain injury, often in conjunction with an inflammatory insult, is the most common cause of death or disability in neonates. Therapeutic hypothermia (TH) is the standard of care for HI encephalopathy in term and near-term infants. However, TH may not always be available or efficacious, creating a need for novel or adjunctive neurotherapeutics. Using a near-term model of inflammation-sensitized HI brain injury in postnatal day (P) 17 ferrets, animals were randomized to either the control group (n = 43) or the HI-exposed groups: saline vehicle (Veh; n = 42), Ur (uridine monophosphate, n = 23), Epo (erythropoietin, n = 26), or TH (n = 24) to test their respective therapeutic effects. Motor development was assessed from P21 to P42 followed by analysis of cortical anatomy, ex vivo MRI, and neuropathology. HI animals took longer to complete the motor assessments compared to controls, which was exacerbated in the Ur group. Injury resulted in thinned white matter tracts and narrowed cortical sulci and gyri, which was mitigated in Epo-treated animals in addition to normalization of cortical neuropathology scores to control levels. TH and Epo treatment also resulted in region-specific improvements in diffusion parameters on ex vivo MRI; however, TH was not robustly neuroprotective in any behavioral or neuropathological outcome measures. Overall, Ur and TH did not provide meaningful neuroprotection after inflammation-sensitized HI brain injury in the ferret, and Ur appeared to worsen outcomes. By comparison, Epo appears to provide significant, though not complete, neuroprotection in this model.

Interleukin-1 blockade attenuates white matter inflammation and oligodendrocyte loss after progressive systemic lipopolysaccharide exposure in near-term fetal sheep

Background

Increased systemic and tissue levels of interleukin (IL)-1β are associated with greater risk of impaired neurodevelopment after birth. In this study, we tested the hypothesis that systemic IL-1 receptor antagonist (Ra) administration would attenuate brain inflammation and injury in near-term fetal sheep exposed to lipopolysaccharide (LPS).

Methods

Chronically instrumented near-term fetal sheep at 0.85 of gestation were randomly assigned to saline infusion (control, n = 9), repeated LPS infusions (0 h = 300 ng, 24 h = 600 ng, 48 h = 1200 ng, n = 8) or repeated LPS plus IL-1Ra infusions (13 mg/kg infused over 4 h) started 1 h after each LPS infusion (n = 9). Sheep were euthanized 4 days after starting infusions for histology.

Results

LPS infusions increased circulating cytokines and were associated with electroencephalogram (EEG) suppression with transiently reduced mean arterial blood pressure, and increased carotid artery perfusion and fetal heart rate (P < 0.05 vs. control for all). In the periventricular and intragyral white matter, LPS-exposure increased IL-1β immunoreactivity, numbers of caspase 3+ cells and microglia, reduced astrocyte and olig-2+ oligodendrocyte survival but did not change numbers of mature CC1+ oligodendrocytes, myelin expression or numbers of neurons in the cortex and subcortical regions. IL-1Ra infusions reduced circulating cytokines and improved recovery of EEG activity and carotid artery perfusion. Histologically, IL-1Ra reduced microgliosis, IL-1β expression and caspase-3+ cells, and improved olig-2+ oligodendrocyte survival.

Conclusion

IL-1Ra improved EEG activity and markedly attenuated systemic inflammation, microgliosis and oligodendrocyte loss following LPS exposure in near-term fetal sheep. Further studies examining the long-term effects on brain maturation are now needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02238-4.

Early Psychomotor Advantage in Moderately Preterm Twins Born between 32 and 33 Weeks

Twin birth may represent a challenging event often associated with prematurity. We previously reported on developmental trajectories in preterm children categorized by gestational age. Based on the same study population, in this study we investigated the influence of gemellarity on the neurodevelopment of 73 twins (26.4%) and 207 singletons (73.6%), categorized into three groups according to their gestational age. The age of the achievement of developmental milestones between the three groups and the influence of preperinatal events on neurodevelopment were analyzed. An early neurodevelopmental advantage was detected in preterm twins born between 32 and 33 weeks. Environmental and nurturing factors may explain these findings.

Positive fluid balance is associated with death and severity of brain injury in neonates with hypoxic-ischemic encephalopathy

OBJECTIVE

To investigate the association between fluid balance during therapeutic hypothermia (TH) and severity of brain injury on magnetic resonance imaging (MRI) in neonates with hypoxic-ischemic encephalopathy (HIE).

STUDY DESIGN

This is a secondary analysis of data from a prospective observational study in neonates with HIE. Daily net positive fluid balance during TH was investigated for association with the adverse primary outcome of death or moderate-to-severe brain injury on MRI using multivariable logistic regression.

RESULTS

Of the 150 neonates included, 50 suffered adverse outcome and had significantly higher net positive fluid balance (53 vs. 19 ml/kg/day, p < 0.01) during first 24 hours of TH. Neonates with a net positive fluid balance (>25 ml/kg/day) at 24 hours of TH had 3.4 (95% CI 1.3-9) times higher odds of adverse outcome.

CONCLUSIONS

Positive fluid balance during TH in neonates with HIE is independently associated with death or moderate-to-severe brain injury on MRI.

A Decision-Tree Approach to Assist in Forecasting the Outcomes of the Neonatal Brain Injury

Neonatal brain injury or neonatal encephalopathy (NE) is a significant morbidity and mortality factor in preterm and full-term newborns. NE has an incidence in the range of 2.5 to 3.5 per 1000 live births carrying a considerable burden for neurological outcomes such as epilepsy, cerebral palsy, cognitive impairments, and hydrocephaly. Many scoring systems based on different risk factor combinations in regression models have been proposed to predict abnormal outcomes. Birthweight, gestational age, Apgar scores, pH, ultrasound and MRI biomarkers, seizures onset, EEG pattern, and seizure duration were the most referred predictors in the literature. Our study proposes a decision-tree approach based on clinical risk factors for abnormal outcomes in newborns with the neurological syndrome to assist in neonatal encephalopathy prognosis as a complementary tool to the acknowledged scoring systems. We retrospectively studied 188 newborns with associated encephalopathy and seizures in the perinatal period. Etiology and abnormal outcomes were assessed through correlations with the risk factors. We computed mean, median, odds ratios values for birth weight, gestational age, 1-min Apgar Score, 5-min Apgar score, seizures onset, and seizures duration monitoring, applying standard statistical methods first. Subsequently, CART (classification and regression trees) and cluster analysis were employed, further adjusting the medians. Out of 188 cases, 84 were associated to abnormal outcomes. The hierarchy on etiology frequencies was dominated by cerebrovascular impairments, metabolic anomalies, and infections. Both preterms and full-terms at risk were bundled in specific categories defined as high-risk 75-100%, intermediate risk 52.9%, and low risk 0-25% after CART algorithm implementation. Cluster analysis illustrated the median values, profiling at a glance the preterm model in high-risk groups and a full-term model in the inter-mediate-risk category. Our study illustrates that, in addition to standard statistics methodologies, decision-tree approaches could provide a first-step tool for the prognosis of the abnormal outcome in newborns with encephalopathy.

White matter injury in the neonatal hypoxic-ischemic brain and potential therapies targeting microglia

Neonatal hypoxic-ischemic (H-I) injury, which mainly causes neuronal damage and white matter injury (WMI), is among the predominant causes of infant morbidity (cerebral palsy, cognitive and persistent motor disabilities) and mortality. Disruptions to the oxygen and blood supply in the perinatal brain affect the cerebral microenvironment and may affect microglial activation, excitotoxicity, and oxidative stress. Microglia are significantly associated with axonal damage and myelinating oligodendrocytes, which are major pathological components of WMI. However, the effects of H-I injury on microglial functions and underlying transformation mechanisms remain poorly understood. The historical perception that these cells are major risk factors for ischemic stroke has been questioned due to our improved understanding of the diversity of microglial phenotypes and their alterable functions, which exacerbate or attenuate injuries in different regions in response to environmental instability. Unfortunately, although therapeutic hypothermia is an efficient treatment, death and disability remain the prognosis for a large proportion of neonates with H-I injury. Hence, novel neuroprotective therapies to treat WMI following H-I injury are urgently needed. Here, we review microglial mechanisms that might occur in the developing brain due to neonatal H-I injury and discuss whether microglia function as a double-edged sword in WMI. Then, we emphasize microglial heterogeneity, notably at the single-cell level, and sex-specific effects on the etiology of neurological diseases. Finally, we discuss current knowledge of strategies aiming to improve microglia modulation and remyelination following neonatal H-I injury. Overall, microglia-targeted therapy might provide novel and valuable insights into the treatment of neonatal H-I insult.

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.

Therapeutic hypothermia initiated within 6 hours of birth is associated with reduced brain injury on MR biomarkers in mild hypoxic-ischaemic encephalopathy: a non-randomised cohort study

OBJECTIVE

To examine the effect of therapeutic hypothermia on MR biomarkers and neurodevelopmental outcomes in babies with mild hypoxic-ischaemic encephalopathy (HIE).

DESIGN

Non-randomised cohort study.

SETTING

Eight tertiary neonatal units in the UK and the USA.

PATIENTS

47 babies with mild HIE on NICHD neurological examination performed within 6 hours after birth.

INTERVENTIONS

Whole-body cooling for 72 hours (n=32) or usual care (n=15; of these 5 were cooled for <12 hours).

MAIN OUTCOME MEASURES

MRI and MR spectroscopy (MRS) within 2 weeks after birth, and a neurodevelopmental outcome assessment at 2 years.

RESULTS

The baseline characteristics in both groups were similar except for lower 10 min Apgar scores (p=0.02) in the cooled babies. Despite this, the mean (SD) thalamic NAA/Cr (1.4 (0.1) vs 1.6 (0.2); p<0.001) and NAA/Cho (0.67 (0.08) vs 0.89 (0.11); p<0.001) ratios from MRS were significantly higher in the cooled group. Cooled babies had lower white matter injury scores than non-cooled babies (p=0.02). Four (27%) non-cooled babies with mild HIE developed seizures after 6 hours of age, while none of the cooled babies developed seizures (p=0.008). Neurodevelopmental outcomes at 2 years were available in 40 (85%) of the babies. Adverse outcomes were seen in 2 (14.3%) non-cooled babies, and none of the cooled babies (p=0.09).

CONCLUSIONS

Therapeutic hypothermia may have a neuroprotective effect in babies with mild HIE, as demonstrated by improved MRS biomarkers and reduced white matter injury on MRI. This may warrant further evaluation in adequately powered randomised controlled trials.

Punctate white-matter lesions in the full-term newborn: Underlying aetiology and outcome

BACKGROUND

Punctate white matter lesions (PWMLs) are small focal patches of increased signal intensity (SI) on T1- and decreased SI on T2-weighted magnetic resonance imaging (MRI). To date, there have been few reports of PWMLs in term born infants.

OBJECTIVE

To identify associated diagnoses and factors predictive of clinical outcome in (near) term infants with PWMLs.

METHODS

MRI studies and clinical records of (near) term infants, with PWMLs on MRI scans performed in two institutions in the first 28 postnatal days were reviewed. The PWMLs were classified according to their number, pattern and distribution. The medical records were examined to assess the associated diagnoses and determine the neurodevelopmental outcome at >12 months of age. Infants with congenital heart defect(s), those who had neonatal surgery, or those with perinatal arterial ischemic stroke were not eligible for the study.

RESULTS

Forty-two (near) term infants with PWMLs were included. The major clinical association was perinatal asphyxia, present in 19/42 (45%). Ten (24%) had a history of seizures unrelated to asphyxia or a genetic diagnosis. Eleven (26%) had pathological genetic mutations. Other diagnoses, without seizures were identified in 2 (5%). The lesion load of PWMLs was high (>6) in 30/42 (71%). Evidence of irreversible white matter injury was present in 5 infants who had follow-up MRI performed between 18 and 24 months of age, because of clinical concerns. Five infants died and 37 had follow-up at a median age of 24 months. Neurodevelopmental outcome was poorest amongst 6 infants (16%) whose PWMLs occurred in the setting of a genetic disorder.

CONCLUSION

PWMLs in (near) term infants represent white matter injury that may evolve into gliosis and/or white matter loss. Infants with PWMLs in the setting of a genetic disorder appeared at most risk of a poor outcome.

White matter injury in term neonates with congenital heart diseases: Topology & comparison with preterm newborns

BACKGROUND

Neonates with congenital heart disease (CHD) are at high risk of punctate white matter injury (WMI) and impaired brain development. We hypothesized that WMI in CHD neonates occurs in a characteristic distribution that shares topology with preterm WMI and that lower birth gestational age (GA) is associated with larger WMI volume.

OBJECTIVE

(1) To quantitatively assess the volume and location of WMI in CHD neonates across three centres. (2) To compare the volume and spatial distribution of WMI between term CHD neonates and preterm neonates using lesion mapping.

METHODS

In 216 term born CHD neonates from three prospective cohorts (mean birth GA: 39 weeks), WMI was identified in 86 neonates (UBC: 29; UCSF: 43; UCZ: 14) on pre- and/or post-operative T1 weighted MRI. WMI was manually segmented and volumes were calculated. A standard brain template was generated. Probabilistic WMI maps (total, pre- and post-operative) were developed in this common space. Using these maps, WMI in the term CHD neonates was compared with that in preterm neonates: 58 at early-in-life (mean postmenstrual age at scan 32.2 weeks); 41 at term-equivalent age (mean postmenstrual age at scan 40.1 weeks).

RESULTS

The total WMI volumes of CHD neonates across centres did not differ (p = 0.068): UBC (median = 84.6 mm3, IQR = 26-174.7 mm3); UCSF (median = 104 mm3, IQR = 44-243 mm3); UCZ (median = 121 mm3, IQR = 68-200.8 mm3). The spatial distribution of WMI in CHD neonates showed strong concordance across centres with predilection for anterior and posterior rather than central lesions. Predominance of anterior lesions was apparent on the post-operative WMI map relative to the pre-operative map. Lower GA at birth predicted an increasing volume of WMI across the full cohort (41.1 mm3 increase of WMI per week decrease in gestational age; 95% CI 11.5-70.8; p = 0.007), when accounting for centre and heart lesion. While WMI in term CHD and preterm neonates occurs most commonly in the intermediate zone/outer subventricular zone there is a paucity of central lesions in the CHD neonates relative to preterms.

CONCLUSIONS

WMI in term neonates with CHD occurs in a characteristic topology. The spatial distribution of WMI in term neonates with CHD reflects the expected maturation of pre-oligodendrocytes such that the central regions are less vulnerable than in the preterm neonates.

Preterm brain Injury: White matter injury

Despite the advances in neonatal intensive care, the preterm brain remains vulnerable to white matter injury (WMI) and disruption of normal brain development (i.e., dysmaturation). Compared to severe cystic WMI encountered in the past decades, contemporary cohorts of preterm neonates experience milder WMIs. More than destructive lesions, disruption of the normal developmental trajectory of cellular elements of the white and the gray matter occurs. In the acute phase, in response to hypoxia-ischemia and/or infection and inflammation, multifocal areas of necrosis within the periventricular white matter involve all cellular elements. Later, chronic WMI is characterized by diffuse WMI with aberrant regeneration of oligodendrocytes, which fail to mature to myelinating oligodendrocytes, leading to myelination disturbances. Complete neuronal degeneration classically accompanies necrotic white matter lesions, while altered neurogenesis, represented by a reduction of the dendritic arbor and synapse formation, is observed in response to diffuse WMI. Neuroimaging studies now provide more insight in assessing both injury and dysmaturation of both gray and white matter. Preterm brain injury remains an important cause of neurodevelopmental disabilities, which are still observed in up to 50% of the preterm survivors and take the form of a complex combination of motor, cognitive, and behavioral concerns.

Early Glycemic Profile Is Associated with Brain Injury Patterns on Magnetic Resonance Imaging in Hypoxic Ischemic Encephalopathy

OBJECTIVE

To investigate whether the early glycemic profile in infants with hypoxic ischemic encephalopathy is associated with distinct patterns of brain injury on magnetic resonance imaging (MRI).

STUDY DESIGN

We performed a secondary analysis of 178 prospectively enrolled infants who received therapeutic hypothermia for hypoxic ischemic encephalopathy. Glycemic profiles were identified by glucose concentrations within 24 hours after birth: normoglycemia (all glucose concentrations of >47 to ≤150 mg/dL; n = 62); hypoglycemia (≥1 concentration ≤47 mg/dL; n = 17); hyperglycemia (≥1 concentration >150 mg/dL; n = 76); and labile glucose (both hypoglycemia and hyperglycemia; n = 23). Patterns of brain injury were identified for 151 infants based on Barkovich scores from the postrewarming brain MRIs at a median age of 9 days.

RESULTS

A normal brain MRI was reported in 37 of 62 infants (60%) with normal blood glucose values compared with 37 of 116 infants (32%) with an abnormal glucose profile (adjusted for Sarnat stage of encephalopathy and Apgar score at 5 minutes; P = .02). The distribution of MRI patterns of brain injury differed among the glycemic groups (P = .03). The odds of predominant watershed or focal-multifocal injury was higher in infants with hypoglycemia (aOR, 6; 95% CI, 1.5-24.2) and labile glucose (6.6; 95% CI, 1.6-27) compared with infants with normoglycemia. Infants with labile glucose had higher odds (5.6; 95% CI, 1.1-29.3) of predominant basal ganglia or global injury compared with infants with normal blood glucose values.

CONCLUSIONS

The early glycemic profile in infants with hypoxic ischemic encephalopathy is associated with specific patterns of brain injury on MRI. Further investigation is needed to explore its prognostic significance and role as a phenotype biomarker.

Conventional MRI scan and DTI imaging show more severe brain injury in neonates with hypoxic-ischemic encephalopathy and seizures

BACKGROUND

Neonates with hypoxic-ischemic encephalopathy (HIE) and seizures have poorer outcome for undetermined reasons.

AIMS

Our aim was to determine if brain imaging was more abnormal in neonates with HIE and electrographically confirmed seizures and whether this was impacted by seizure burden.

STUDY DESIGN

Single center retrospective review.

SUBJECTS

Forty-eight term neonates with HIE (with and without seizures) underwent MRI brain scans before age 14 days between the years 2008 and 2013.

OUTCOME MEASURES

Images were rated using a MRI injury score and fractional anisotropy (FA) values were extracted from diffusion tensor imaging (DTI).

RESULTS

The seizure group (n = 25) had significantly more injury within white matter, basal ganglia, posterior limb of internal capsule, and watershed areas compared to the group without seizures (n = 23). The severity of injury in all measured areas increased with increasing seizure severity. The seizure group also had lower FA values in posterior limb of the internal capsule and the splenium of corpus callosum.

CONCLUSIONS

Neonates with HIE and seizures had more brain injury that occurred in areas typically affected by HIE and was greater with higher seizure burden. Seizures may be a marker of more severe brain injury or seizures themselves may amplify brain damage from HIE.

MRI as a biomarker for mild neonatal encephalopathy

Historically, there has been limited neuro-imaging data acquired on infants with mild neonatal encephalopathy (NE). This likely reflects the traditional assumption that these infants had a universally good prognosis. As new evidence has emerged challenging this assumption, there has been a renewed interest in the neuro-imaging findings of these infants. To date, magnetic resonance imaging (MRI) studies in infants with mild NE have demonstrated abnormalities in 20-40% of cases suggestive that the injury occurs during the peripartum period with a predominant watershed pattern of injury. The severity of the injury on MRI in infants with mild NE varies, but includes patterns of injury that have been associated with long-term neuro-developmental impairment.

A Comparison of Spastic Diplegia in Term and Preterm-Born Children

This study compared the risk factors and clinical and radiologic profile of children with spastic diplegic cerebral palsy born at term (≥37 weeks) with those born preterm. Children (2-14 years) with cerebral palsy meeting the study criteria for spastic diplegia were enrolled. Antecedent risk factors, clinical profile, and magnetic resonance imaging (MRI) findings were recorded. Spasticity, functional ability, intellectual ability, and social quotient were assessed using standard scales. Ninety-three children met the study inclusion criteria (45 term, 48 preterm). Moderate to severe intellectual disability (53% vs 21%, P = .001) and epilepsy (51% vs 33%) were significantly more common in term-born children, whereas periventricular white matter injury was less common in term-born children (64%vs 89.4%, P = .004). Term spastic diplegia was associated with cortical/subcortical involvement in (11/42 (26%) vs 3/47(6.4%); P = .01). We conclude that term-spastic-diplegia is clinicopathologically different from preterm-spastic-diplegia. Their neuroradiologic pattern also differs with more frequent involvement of cortical/subcortical areas.

Clinical Findings and Neurologic Outcome in Neonatal Encephalopathy With White Matter Injury Accompanied by Rotavirus

Our objective was to elucidate the clinical characteristics and neurodevelopmental outcomes in neonatal encephalopathy with characteristic white matter injury as compared with other injury patterns on magnetic resonance diffusion-weighted imaging. We conducted a retrospective study comparing clinical and laboratory findings, and neurologic outcomes between 17 newborns with diffuse lesions in the periventricular white matter and white matter tract (group I) and 22 newborns with other patterns (group II). Stool samples indicated that 16 neonates (94.1%) in group I were rotavirus-positive, whereas none in group II had rotavirus infection. Significantly lower calcium levels were found in group I than in group II ( P < .001). Moreover, a more favorable neurodevelopmental outcome was observed in group I than in group II. This study suggests that characteristic white matter injury in neonatal encephalopathy may be related to decreased calcium levels induced by rotavirus, and may have a better neurodevelopmental prognosis than other causes.

[Patterns of brain injury in neonatal hypoxic-ischemic encephalopathy on magnetic resonance imaging: recommendations on classification]

Although there are unified criteria for the clinical diagnosis and grading of neonatal hypoxic-ischemic encephalopathy (HIE), clinical features and neuropathological patterns vary considerably among the neonates with HIE due to birth asphyxia in the same classification. The patterns and progression of brain injury in HIE, which is closely associated with long-term neurodevelopment outcomes, can be well shown on magnetic resonance imaging (MRI), but different sequences may lead to different MRI findings at the same time. It is suggested that diffusion-weighted imaging sequence be selected at 2-4 days after birth, and the conventional MRI sequence at 4-8 days. The major patterns of brain injury in HIE on MRI are as follows: injury of the thalamus and basal ganglia and posterior limbs of the internal capsules; watershed injury involving the cortical and subcortical white matter; focal or multifocal minimal white matter injury; extensive whole brain injury. Severe acute birth asphyxia often leads to deep grey matter injury (thalamus and basal ganglia), and the brain stem may also be involved; the pyramidal tract is the most susceptible white matter fiber tract; repetitive or intermittent hypoxic-ischemic insults, with inflammation or hypoglycemia, usually cause injuries in the watershed area and deep white matter. It is worth noting that sometimes the pattern of brain injury among those described above cannot be determined exactly, but rather a predominant one is identified; not all cases of HIE have characteristic MRI findings.

White matter injury in the preterm infant: pathology and mechanisms

The human preterm brain is particularly susceptible to cerebral white matter injury (WMI) that disrupts the normal progression of developmental myelination. Advances in the care of preterm infants have resulted in a sustained reduction in the severity of WMI that has shifted from more severe focal necrotic lesions to milder diffuse WMI. Nevertheless, WMI remains a global health problem and the most common cause of chronic neurological morbidity from cerebral palsy and diverse neurobehavioral disabilities. Diffuse WMI involves maturation-dependent vulnerability of the oligodendrocyte (OL) lineage with selective degeneration of late oligodendrocyte progenitors (preOLs) triggered by oxidative stress and other insults. The magnitude and distribution of diffuse WMI are related to both the timing of appearance and regional distribution of susceptible preOLs. Diffuse WMI disrupts the normal progression of OL lineage maturation and myelination through aberrant mechanisms of regeneration and repair. PreOL degeneration is accompanied by early robust proliferation of OL progenitors that regenerate and augment the preOL pool available to generate myelinating OLs. However, newly generated preOLs fail to differentiate and initiate myelination along their normal developmental trajectory despite the presence of numerous intact-appearing axons. Disrupted preOL maturation is accompanied by diffuse gliosis and disturbances in the composition of the extracellular matrix and is mediated in part by inhibitory factors derived from reactive astrocytes. Signaling pathways implicated in disrupted myelination include those mediated by Notch, WNT-beta catenin, and hyaluronan. Hence, there exists a potentially broad but still poorly defined developmental window for interventions to promote white matter repair and myelination and potentially reverses the widespread disturbances in cerebral gray matter growth that accompanies WMI.

Children born at 32 to 35 weeks with birth asphyxia and later cerebral palsy are different from those born after 35 weeks

OBJECTIVE

The objectives of this study were to (1) establish the proportion of cerebral palsy (CP) that occurs with a history suggestive of birth asphyxia in children born at 32 to 35 weeks and (2) evaluate their characteristics in comparison with children with CP born at ⩾36 weeks with such a history.

STUDY DESIGN

Using the Canadian CP Registry, children born at 32 to 35 weeks of gestation with CP with a history suggestive of birth asphyxia were compared with corresponding ⩾36 weeks of gestation children.

RESULTS

Of the 163 children with CP born at 32 to 35 weeks and 738 born at ⩾36 weeks, 26 (16%) and 105 (14%) had a history suggestive of birth asphyxia, respectively. The children born at 32 to 35 weeks had more frequent abruptio placenta (35% vs 12%; odds ratio (OR) 4.1, 95% confidence interval (CI) 1.5 to 11.2), less frequent neonatal seizures (35% vs 72%; OR 0.20, 95% CI 0.08 to 0.52), more frequent white matter injury (47% vs 17%; OR 4.3, 95% CI 1.3 to 14.0), more frequent intraventricular hemorrhage (IVH) (40% vs 6%; OR 11.2, 95% CI 3.4 to 37.4) and more frequent spastic diplegia (24% vs 8%; OR 1.8, 95% CI 1.2 to 12.2) than the corresponding ⩾36 weeks of gestation children.

CONCLUSIONS

Approximately 1 in 7 children with CP born at 32 to 35 weeks had a history suggestive of birth asphyxia. They had different magnetic resonance imaging patterns of injury from those born at ⩾36 weeks and a higher frequency of IVH. Importantly, when considering hypothermia in preterm neonates with suspected birth asphyxia, prospective surveillance for IVH will be essential.

Neonatal Hypoxia Ischaemia: Mechanisms, Models, and Therapeutic Challenges

Neonatal hypoxia-ischaemia (HI) is the most common cause of death and disability in human neonates, and is often associated with persistent motor, sensory, and cognitive impairment. Improved intensive care technology has increased survival without preventing neurological disorder, increasing morbidity throughout the adult population. Early preventative or neuroprotective interventions have the potential to rescue brain development in neonates, yet only one therapeutic intervention is currently licensed for use in developed countries. Recent investigations of the transient cortical layer known as subplate, especially regarding subplate's secretory role, opens up a novel set of potential molecular modulators of neonatal HI injury. This review examines the biological mechanisms of human neonatal HI, discusses evidence for the relevance of subplate-secreted molecules to this condition, and evaluates available animal models. Neuroserpin, a neuronally released neuroprotective factor, is discussed as a case study for developing new potential pharmacological interventions for use post-ischaemic injury.

Punctate white matter lesions in full-term infants with neonatal seizures associated with SLC13A5 mutations

INTRODUCTION

Early-onset epileptic encephalopathy caused by biallelic SLC13A5 mutations is characterized by seizure onset in the first days of life, refractory epilepsy and developmental delay. Little detailed information about the brain MRI features is available in these patients.

METHODS

Observational study describing the neuro-imaging findings in eight patients (five families) with mutations in the SLC13A5 gene. Seven infants had an MRI in the neonatal period, two had a follow-up MRI at the age of 6 and 18 months and one only at 13 months. One patient had follow-up MRIs at 11 and 16 months and 3 and 6 years of age, but no neonatal MRI.

RESULTS

All patients presented with refractory neonatal seizures on the first day of life after an uncomplicated pregnancy and term delivery. Six out of seven infants with a neonatal MRI had a characteristic MRI pattern, with punctate white matter lesions (PWML), which were no longer visible at the age of 6 months, but led to gliotic scarring visible on MRI at the age of 18 months. The same pattern of gliotic scarring was seen on the MRIs of the infant without a neonatal scan. One infant had signal abnormalities in the white matter suspected of PWML on T2WI, but these could not be confirmed on other sequences.

CONCLUSION

In infants presenting with therapy resistant seizures in the first days after birth, without a clear history of hypoxic-ischemic encephalopathy, but with PWML on their neonatal MRI, a diagnosis of SCL13A5 related epileptic encephalopathy should be considered.

The Vulnerable Newborn Brain: Imaging Patterns of Acquired Perinatal Injury

BACKGROUND

Over the past two decades, imaging techniques have allowed for better visualization of the newborn brain. This has enabled us to detect patterns, understand mechanisms and guide diagnosis and treatment.

OBJECTIVES

The purpose of this review is to discuss imaging characteristics of acquired perinatal brain injury.

METHODS

Through literature review and the author's research, this review assesses published data on the distinct imaging patterns that occur in the neonatal period due to acquired brain insults.

RESULTS

In the term brain, susceptibility to hypoxia-ischemia, hypoglycemia and hyperbilirubinemia results in unique patterns of injury. Stroke commonly occurs in the newborn period. Infections, especially viral, have distinct patterns of white matter injury. In the preterm brain, white matter injury occurs commonly and is affected by postnatal growth, stress and infection. The cerebellum is uniquely vulnerable during this period, with resultant hemorrhages in almost half of preterm infants. Cerebellar growth is affected by intraventricular hemorrhage, drugs and placental pathology. Periventricular hemorrhagic infarction is the most serious consequence of the spectrum of intraventricular hemorrhage and results in profound disabilities.

CONCLUSIONS

Taken together, the acquired perinatal brain injuries can have lifelong devastating consequences, so the search for therapies must continue.

Brain magnetic resonance imaging and outcome after hypoxic ischaemic encephalopathy

OBJECTIVE

To correlate pattern of injury on neonatal brain magnetic resonance imaging (MRI) with outcome in infants ≥36 + 0 weeks gestation with hypoxic ischaemic encephalopathy.

METHODS

Prospective cohort study. Images were blindly reviewed. Children were assessed using a variety of standardised assessments.

RESULTS

MRI brain was performed on 88 infants. Follow up was available in 73(83%) infants. Eight of 25(32%) children with normal imaging had below normal assessment scores. Eight infants (12%) had isolated punctate white matter lesions and five of these had abnormal assessment scores. Death and cerebral palsy were seen only in children with imaging scores ≥3 on basal ganglia/thalami (BGT) score or ≥4 on watershed score. No developmental concerns were raised in 3/7(43%) infants with isolated watershed injury. Ten of 13(77%) infants with isolated BGT injury died or developed cerebral palsy. All 23 children with posterior limb of the internal capsule (PLIC) injury displayed developmental difficulties.

CONCLUSIONS

Almost one-third of infants with a normal MRI brain may be at risk of developmental problems. Punctate foci of white matter injury are common and not always benign. PLIC involvement is usually associated with neurological sequelae including isolated cognitive deficits. Worst outcomes are associated with basal ganglia injury.

The aetiology of neonatal seizures and the diagnostic contribution of neonatal cerebral magnetic resonance imaging

AIM

The aim of this study was to delineate aetiologies and explore the diagnostic value of cerebral magnetic resonance imaging (MRI) in addition to cranial ultrasonography (cUS) in infants presenting with neonatal seizures.

METHOD

This retrospective cohort study comprised infants (gestational age 35.0-42.6wks) with seizures, confirmed by either continuous amplitude-integrated electroencephalography (aEEG) or standard EEG and admitted during a 14-year period to a level three neonatal intensive care unit (n=378; 216 males, 162 females; mean [SD] birthweight 3334g [594]). All infants underwent cUS and MRI (MRI on median of 5 days after birth, range 0-58d) within the first admission period.

RESULTS

An underlying aetiology was identified in 354 infants (93.7%). The most common aetiologies identified were hypoxic-ischaemic encephalopathy (46%), intracranial haemorrhage (12.2%), and perinatal arterial ischaemic stroke (10.6%). When comparing MRI with cUS in these 354 infants MRI showed new findings which did not become apparent on cUS, contributing to a diagnosis in 42 (11.9%) infants and providing additional information to cUS, contributing to a diagnosis in 141 (39.8%). cUS alone would have allowed a diagnosis in only 37.9% of infants (134/354).

INTERPRETATION

Cerebral MRI contributed to making a diagnosis in the majority of infants. In 11.9% of infants the diagnosis would have been missed if only cUS were used and cerebral MRI added significantly to the information obtained in 39.8% of infants. These data suggest that cerebral MRI should be performed in all newborn infants presenting with EEG- or aEEG-confirmed seizures.

MRI for neurodevelopmental prognostication in the high-risk term infant

MRI performed in the neonatal period has become a tool widely used by clinicians and researchers to evaluate the developing brain. MRI can provide detailed anatomical resolution, enabling identification of brain injuries due to various perinatal insults. This review will focus on the link between neonatal MRI findings and later neurodevelopmental outcomes in high-risk term infants. In particular, the role of conventional and advanced MR imaging in prognosticating outcomes in neonates with hypoxic-ischemic encephalopathy, ischemic perinatal stroke, need for extracorporeal membrane oxygenation life support, congenital heart disease, and other neonatal neurological conditions will be discussed.

[Treatment of encephalopathy by hypothermia in the term newborn]

Criteria defining the involvement of severe perinatal anoxia in neonatal encephalopathy in at-term newborns at birth are stringent and are rarely all present. The simultaneous action of pre- and intrapartum factors preceding neonatal hypoxic-ischemic encephalopathy are often observed. Cooling is recommended as there is evidence that it reduces mortality without increasing major disability in survivors. It must be conducted following strict clinical and electroencephalographic criteria. Other strategies for brain protection remain difficult to establish. Follow-up must be long enough to detect cognitive deficiencies, which are frequent, even if cerebral palsy is not observed.

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

BACKGROUND

Magnetic resonance imaging is a surrogate biomarker for major neurodevelopmental disabilities in survivors of perinatal hypoxic-ischemic encephalopathy because injury to the basal ganglia/thalami is highly predictive of major neuromotor and cognitive problems. Major disabilities and the appearance of neonatal magnetic resonance imaging are improved with therapeutic hypothermia. We evaluated neurodevelopmental outcomes when conventional magnetic resonance imaging showed minimal or no brain injury.

METHODS

Institutional review board-approved series of 62 infants (≥36 weeks; ≥1800 g; 34 boys/28 girls) cooled for hypoxic-ischemic encephalopathy between 2005 and 2011 who underwent neonatal magnetic resonance imaging and Bayley Scales of Infant and Toddler Development-III at 22 ± 7 months of age. Magnetic resonance imaging at 5-14 (mean 8) days was scored as normal (score = 0), showing focal gray or white matter injury only (score = 1), or basal ganglia/thalamic and/or watershed lesions with or without more extensive hemispheric injury (score = 2). Sensitivity, specificity, and positive and negative predictive values for magnetic resonance scores 0 and 1 and statistical interaction between magnetic resonance imaging score and age at magnetic resonance imaging were determined.

RESULTS

Magnetic resonance score = 0 was seen in 35/62 patients; 26/35 (74%) were typically developing, seven (20%) had moderate and two (6%) had severe delay. Magnetic resonance score = 1 was seen in 17/62 (27%) patients; 5/17 (29%) were normal, 11/17 (65%) had moderate delay, and 1/17 (6%) had severe neurodevelopmental delay. Of the 52 patients with magnetic resonance scores of 0 and 1, 40% were abnormal. The negative predictive value of a normal magnetic resonance imaging was 74%. For score 1, sensitivity was 95% (confidence interval 63%-83%), specificity 84% (confidence interval 70%-90%), positive predictive value 84% (confidence interval 71%-93%), and negative predictive value 74% (confidence interval 62%-82%).

CONCLUSIONS

Caution is warranted when prognosticating about neurodevelopmental status in early childhood after hypoxic ischemic encephalopathy with cooling, and longer follow-up studies are needed to determine the prognostic significance of a neonatal magnetic resonance imaging showing no or minor degrees of brain injury.