Mammillary body atrophy and other MRI correlates of school-age outcome following neonatal hypoxic-ischemic encephalopathy

Consensus Approach for Standardization of the Timing of Brain Magnetic Resonance Imaging and Classification of Brain Injury in Neonates With Neonatal Encephalopathy/Hypoxic-Ischemic Encephalopathy: A Canadian Perspective

BACKGROUND

Neonatal encephalopathy (NE) and hypoxic-ischemic encephalopathy (HIE) are linked to significant neurodevelopmental impairments. Magnetic resonance imaging (MRI) is the preferred modality for classifying brain injury severity in HIE, yet considerable variability exists among institutions in terms of MRI timing, protocols, injury classification, and scoring systems for predicting long-term outcomes.

METHODS

A Canadian taskforce comprising radiologists and neonatologists was established to develop a consensus on the optimal timing of brain MRI, appropriate MRI protocols, and a unified approach to the classification and scoring of brain injury in infants with NE secondary to hypoxic-ischemic insult. The taskforce proposed a radiological classification and scoring system that is both simplified and modified from previously validated systems.

RESULTS

The consensus resulted in a standardized MRI protocol and a streamlined classification system designed to reduce interinstitutional variability. This proposed system offers a uniform framework for assessing the severity of brain injury and serves as a potential tool for predicting long-term neurodevelopmental outcomes.

CONCLUSION

Once validated, the proposed radiological classification and scoring system can be applied across centers to facilitate consistent outcome comparisons, improve prognostication for neonates with NE/HIE, and enhance the quality of family counseling regarding long-term neurodevelopmental prospects.

Neonatal encephalopathy and hypoxic-ischemic encephalopathy: the state of the art

Neonatal Encephalopathy (NE) remains a major cause of death and long-term severe disabilities, including epilepsy and cerebral palsy in term and near-term infants. The single most common cause is hypoxic-ischemic encephalopathy (HIE). However, there are many other potential causes, including infection, intracranial hemorrhage, stroke, brain malformations, metabolic disorders, and genetic causes. The appropriate management depends on both the specific cause and the stage of evolution of injury. Key tools to expand our understanding of the timing and causes of NE include aEEG, or even better, video EEG monitoring, neuro-imaging including cranial ultrasound and MRI, placental investigations, metabolic, biomarker, and genetic studies. This information is critical to better understand the underlying causes of NE. Therapeutic hypothermia improves outcomes after HIE, but there is still considerable potential to do better. Careful clinical and pre-clinical studies are needed to develop novel therapeutics and to help provide the right treatment at the right time for this high-risk population. IMPACT: Neonatal encephalopathy is complex and multifactorial. This review seeks to expand understanding of the causes, timing, and evolution of encephalopathy in newborns. We highlight key unanswered questions about neonatal encephalopathy.

Co-occurring impairments in several domains of memory following neonatal hypoxic-ischaemic encephalopathy have real-life implications

BACKGROUND

Neonatal Hypoxic-Ischaemic Encephalopathy (HIE) increases the risk for neurodevelopmental impairment. Information on school-age memory function is limited in children who received hypothermia treatment (TH) for neonatal HIE.

OBJECTIVES

To evaluate memory function in school-aged children who had neonatal HIE and TH and survived without major neuromotor impairment.

METHOD

Fifty-one children with neonatal HIE and 41 typically developing (TD) peers participated. At age 6-8 years general cognitive abilities (FSIQ) were assessed with Wechsler Intelligence Scale for Children (WISC-V), immediate and delayed visual and verbal memory with Children's Memory Scale (CMS), everyday memory with Rivermead Behavioural Memory Test for Children (RBMT-C), and working memory with WISC-V. Real-life implications were assessed with Behavior Rating Inventory for Executive Function (BRIEF; Parent and Teacher). Group differences were examined and correlations calculated to assess associations between memory measures. Relationship maps illustrate co-occurring impairments.

RESULTS

FSIQ was in the normal range for both groups but significantly lower in the HIE group. Children with HIE had significantly more deficits in working memory (20.4 % vs 0 %), verbal immediate (20.0 % vs 2.5 %), verbal delayed (17.8 % vs 2.5 %), visual immediate (28.9 % vs 7.5 %), and everyday memory (38.8 % vs 5.6 %). Relationship maps identified more co-occurring clinical/borderline impairments in children with HIE (45.1 % vs 4.9 %) and more frequent clinical impairments in real-world memory measures.

CONCLUSION

Despite hypothermia treatment, and with general cognitive abilities in the normal range, children with neonatal HIE are at risk of memory impairments in multiple domains, affecting everyday functioning at home and school. Timely identification is important for individually targeted support.

Individualized Neuroprognostication in Neonates With Hypoxic-Ischemic Encephalopathy Treated With Hypothermia

Background and Objectives

To determine whether post-rewarming brain MRI enables individualized domain-specific prediction of neurodevelopmental outcomes at 2 years of age in infants treated with hypothermia for hypoxic-ischemic brain injury.

Methods

We conducted a retrospective multicenter study of infants with moderate-to-severe hypoxic-ischemic encephalopathy (HIE) treated with hypothermia. Brain MRI abnormalities and the prediction of domain-specific 2-year neurodevelopmental outcomes were scored independently by 2 investigators after which consensus was reached for both imaging findings and outcome prediction. Neuroimaging patterns were categorized as normal, white matter (WM)/watershed-predominant, deep gray matter (DGM)-predominant, and near-total injury. Outcomes were predicted separately for mortality, cerebral palsy (CP) type and severity, cognitive delay, epilepsy, cerebral visual impairment (CVI), and feeding difficulties; these outcomes were predicted as highly unlikely, possible, probable, or highly likely.

Results

Of the 152 study infants, 27 (18%) died. The neurodevelopmental outcome at 2 years was available in all 125 survivors. CP was seen in 21 of 125 surviving infants (17%). No infants in the highly unlikely category developed CP while 90% in the highly likely category did. When CP was predicted as possible, 40% developed CP; all were mild and ambulatory. When CP was predicted as probable, 67% developed CP of whom 40% were severe and nonambulatory. Cognitive scores were available in 104 of 125 infants (83%). Cognitive delay was seen in 23 of 104 infants (22%) (15% mild and 7% severe). When cognitive delay was predicted as highly unlikely, 92% did not develop cognitive delay and the delay was mild in those who did. When cognitive delay was considered highly likely, this developed in 100%. When epilepsy, CVI, and feeding problems were predicted as highly unlikely, 98% did not develop epilepsy; for CVI and feeding problems, this was 100% and 97%, respectively. In 27 of 152 infants (18%), the investigators reached consensus that the overall injury was severe enough to consider redirection of care; 21 of 27 infants (78%) died. Of the survivors, 5 infants developed severe CP and 1 had a mild dyskinetic CP with swallowing problems and CVI.

Discussion

Individualized domain-specific categorical neuroprognostication mainly based on brain MRI is feasible, reliable, and highly accurate in infants with HIE.

Oligodendrocyte progenitor cells' fate after neonatal asphyxia-Puzzling implications for the development of hypoxic-ischemic encephalopathy

Premature birth or complications during labor can cause temporary disruption of cerebral blood flow, often followed by long-term disturbances in brain development called hypoxic-ischemic (HI) encephalopathy. Diffuse damage to the white matter is the most frequently detected pathology in this condition. We hypothesized that oligodendrocyte progenitor cell (OPC) differentiation disturbed by mild neonatal asphyxia may affect the viability, maturation, and physiological functioning of oligodendrocytes. To address this issue, we studied the effect of temporal HI in the in vivo model in P7 rats with magnetic resonance imaging (MRI), microscopy techniques and biochemical analyses. Moreover, we recreated the injury in vitro performing the procedure of oxygen-glucose deprivation on rat neonatal OPCs to determine its effect on cell viability, proliferation, and differentiation. In the in vivo model, MRI evaluation revealed changes in the volume of different brain regions, as well as changes in the directional diffusivity of water in brain tissue that may suggest pathological changes to myelinated neuronal fibers. Hypomyelination was observed in the cortex, striatum, and CA3 region of the hippocampus. Severe changes to myelin ultrastructure were observed, including delamination of myelin sheets. Interestingly, shortly after the injury, an increase in oligodendrocyte proliferation was observed, followed by an overproduction of myelin proteins 4 weeks after HI. Results verified with the in vitro model indicate, that in the first days after damage, OPCs do not show reduced viability, intensively proliferate, and overexpress myelin proteins and oligodendrocyte-specific transcription factors. In conclusion, despite the increase in oligodendrocyte proliferation and myelin protein expression after HI, the production of functional myelin sheaths in brain tissue is impaired. Presented study provides a detailed description of oligodendrocyte pathophysiology developed in an effect of HI injury, resulting in an altered CNS myelination. The described models may serve as useful tools for searching and testing effective of effective myelination-supporting therapies for HI injuries.

Enhancing daily life for children with cognitive developmental delay through insights into brain development

Cognitive developmental delay, including severe intellectual disability (IQ below 70) and borderline intellectual functioning (IQ 70-85), poses significant challenges, including high costs and emotional burden. Early diagnosis and interventions might improve adaptive behavior and daily life functioning. High-risk groups include children with neonatal complications, congenital anomalies, genetic disorders, or metabolic errors, yet over 50% of cases have unknown causes. To provide timely diagnosis and intervention for children with cognitive developmental delay, it is important to increase our understanding and ability to prognosticate their level of functioning. The pivotal role of brain development in the first few years of life presents a window of opportunity for these goals. By detailed investigation of common patterns in structural brain development and connectivity by MRI in relation to cognitive and executive functioning, this review aims to identify potential factors that might improve understanding and prognostication of children with cognitive developmental delay. Exploring similarities among diverse patient groups with childhood cognitive developmental delay, this review intends to provide a nuanced perspective. IMPACT: This review identified several MRI brain developmental markers, especially in the white matter, that might hold potential to be a prognostic marker for intellectual and executive functioning in children with cognitive developmental delay. Bringing together information on aberrant brain developmental trajectories and connectivity across different patient childhood populations with cognitive developmental delay might improve our understanding and prognostication.

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.

Perinatal compromise affects development, form, and function of the hippocampus part one; clinical studies

The hippocampus is a neuron-rich specialised brain structure that plays a central role in the regulation of emotions, learning and memory, cognition, spatial navigation, and motivational processes. In human fetal development, hippocampal neurogenesis is principally complete by mid-gestation, with subsequent maturation comprising dendritogenesis and synaptogenesis in the third trimester of pregnancy and infancy. Dendritogenesis and synaptogenesis underpin connectivity. Hippocampal development is exquisitely sensitive to perturbations during pregnancy and at birth. Clinical investigations demonstrate that preterm birth, fetal growth restriction (FGR), and acute hypoxic-ischaemic encephalopathy (HIE) are common perinatal complications that alter hippocampal development. In turn, deficits in hippocampal development and structure mediate a range of neurodevelopmental disorders, including cognitive and learning problems, autism, and Attention-Deficit/Hyperactivity Disorder (ADHD). In this review, we summarise the developmental profile of the hippocampus during fetal and neonatal life and examine the hippocampal deficits observed following common human pregnancy complications. IMPACT: The review provides a comprehensive summary of the developmental profile of the hippocampus in normal fetal and neonatal life. We address a significant knowledge gap in paediatric research by providing a comprehensive summary of the relationship between pregnancy complications and subsequent hippocampal damage, shedding new light on this critical aspect of early neurodevelopment.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Cranial MRI beyond the Neonatal Period and Neurodevelopmental Outcomes in Neonatal Encephalopathy Due to Perinatal Asphyxia: A Systematic Review

BACKGROUND

Magnetic resonance imaging (MRI) including diffusion-weighted imaging within seven days after birth is widely used to obtain prognostic information in neonatal encephalopathy (NE) following perinatal asphyxia. Later MRI could be useful for infants without a neonatal MRI or in the case of clinical concerns during follow-up. Therefore, this review evaluates the association between cranial MRI beyond the neonatal period and neurodevelopmental outcomes following NE.

METHODS

A systematic literature search was performed using PubMed and Embase on cranial MRI between 2 and 24 months after birth and neurodevelopmental outcomes following NE due to perinatal asphyxia. Two independent researchers performed the study selection and risk of bias analysis. Results were separately described for MRI before and after 18 months.

RESULTS

Twelve studies were included (high-quality n = 2, moderate-quality n = 6, low-quality n = 4). All reported on MRI at 2-18 months: seven studies demonstrated a significant association between the pattern and/or severity of injury and overall neurodevelopmental outcomes and three showed a significant association with motor outcome. There were insufficient data on non-motor outcomes and the association between MRI at 18-24 months and neurodevelopmental outcomes.

CONCLUSIONS

Cranial MRI performed between 2 and 18 months after birth is associated with neurodevelopmental outcomes in NE following perinatal asphyxia. However, more data on the association with non-motor outcomes are needed.

Cerebellar growth, volume and diffusivity in children cooled for neonatal encephalopathy without cerebral palsy

Children cooled for HIE and who did not develop cerebral palsy (CP) still underperform at early school age in motor and cognitive domains and have altered supra-tentorial brain volumes and white matter connectivity. We obtained T1-weighted and diffusion-weighted MRI, motor (MABC-2) and cognitive (WISC-IV) scores from children aged 6-8 years who were cooled for HIE secondary to perinatal asphyxia without CP (cases), and controls matched for age, sex, and socioeconomic status. In 35 case children, we measured cerebellar growth from infancy (age 4-15 days after birth) to childhood. In childhood, cerebellar volumes were measured in 26 cases and 23 controls. Diffusion properties (mean diffusivity, MD and fractional anisotropy, FA) were calculated in 24 cases and 19 controls, in 9 cerebellar regions. Cases with FSIQ ≤ 85 had reduced growth of cerebellar width compared to those with FSIQ > 85 (p = 0.0005). Regional cerebellar volumes were smaller in cases compared to controls (p < 0.05); these differences were not significant when normalised to total brain volume. There were no case-control differences in MD or FA. Interposed nucleus volume was more strongly associated with IQ in cases than in controls (p = 0.0196). Other associations with developmental outcome did not differ between cases and controls.

Reduced mammillary body volume in individuals with a schizophrenia diagnosis: an analysis of the COBRE data set

While the frontal cortices and medial temporal lobe are well associated with schizophrenia, the involvement of wider limbic areas is less clear. The mammillary bodies are important for both complex memory formation and anxiety and are implicated in several neurological disorders that present with memory impairments. However, little is known about their role in schizophrenia. Post-mortem studies have reported a loss of neurons in the mammillary bodies but there are also reports of increased mammillary body volume. The findings from in vivo MRI studies have also been mixed, but studies have typically only involved small sample sizes. To address this, we acquired mammillary body volumes from the open-source COBRE dataset, where we were able to manually measure the mammillary bodies in 72 individuals with a schizophrenia diagnosis and 74 controls. Participant age ranged from 18 to 65. We found the mammillary bodies to be smaller in the patient group, across both hemispheres, after accounting for the effects of total brain volume and gender. Hippocampal volumes, but not subiculum or total grey matter volumes, were also significantly lower in patients. Given the importance of the mammillary bodies for both memory and anxiety, this atrophy could contribute to the symptomology in schizophrenia.

Additional Value of 3-Month Cranial Magnetic Resonance Imaging in Infants with Neonatal Encephalopathy following Perinatal Asphyxia

OBJECTIVE

To assess the evolution of neonatal brain injury noted on magnetic resonance imaging (MRI), develop a score to assess brain injury on 3-month MRI, and determine the association of 3-month MRI with neurodevelopmental outcome in neonatal encephalopathy (NE) following perinatal asphyxia.

METHODS

This was a retrospective, single-center study including 63 infants with perinatal asphyxia and NE (n = 28 cooled) with cranial MRI <2 weeks and 2-4 months after birth. Both scans were assessed using biometrics, a validated injury score for neonatal MRI, and a new score for 3-month MRI, with a white matter (WM), deep gray matter (DGM), and cerebellum subscore. The evolution of brain lesions was assessed, and both scans were related to 18- to 24-month composite outcome. Adverse outcome included cerebral palsy, neurodevelopmental delay, hearing/visual impairment, and epilepsy.

RESULTS

Neonatal DGM injury generally evolved into DGM atrophy and focal signal abnormalities, and WM/watershed injury evolved into WM and/or cortical atrophy. Although the neonatal total and DGM scores were associated with composite adverse outcomes, the 3-month DGM score (OR 1.5, 95% CI 1.2-2.0) and WM score (OR 1.1, 95% CI 1.0-1.3) also were associated with composite adverse outcomes (occurring in n = 23). The 3-month multivariable model (including the DGM and WM subscores) had higher positive (0.88 vs 0.83) but lower negative predictive value (0.83 vs 0.84) than neonatal MRI. Inter-rater agreement for the total, WM, and DGM 3-month score was 0.93, 0.86, and 0.59.

CONCLUSIONS

In particular, DGM abnormalities on 3-month MRI, preceded by DGM abnormalities on the neonatal MRI, were associated with 18- to 24-month outcome, indicating the utility of 3-month MRI for treatment evaluation in neuroprotective trials. However, the clinical usefulness of 3-month MRI seems limited compared with neonatal MRI.

Reduced Hippocampal Volumes in Children with History of Hypoxic Ischemic Encephalopathy after Therapeutic Hypothermia

Hypoxic ischemic encephalopathy (HIE) remains a significant cause of disability despite treatment with therapeutic hypothermia (TH). Many survive with more subtle deficits that affect daily functioning and school performance. We have previously shown an early indication of hippocampal changes in infants with HIE despite TH. The aim of this study was to evaluate the hippocampal volume via MRI and memory function at 5 years of age. A cohort of children followed from birth returned for a 5-year follow-up (n = 10 HIE treated with TH, n = 8 healthy controls). The children underwent brain MRI and neurodevelopmental testing to assess their brain volume, general development, and memory function. Children with HIE had smaller hippocampal volumes than the controls despite no differences in the total brain volume (p = 0.02). Children with HIE generally scored within the average range on developmental testing. Though there was no difference in the memory scores between these groups, there was a positive within-group correlation between the hippocampal volume and memory scores in children with HIE (sentence recall r = 0.66, p = 0.038). There was no relationship between newborn memory function and 5-year hippocampal size. Children with HIE treated with TH experienced significant and lasting changes to the hippocampus despite improvements in survival and severe disability. Future studies should target diminishing injury to the hippocampus to improve overall outcomes.

Mammillary body abnormalities and cognitive outcomes in children cooled for neonatal encephalopathy

AIM

To evaluate mammillary body abnormalities in school-age children without cerebral palsy treated with therapeutic hypothermia for neonatal hypoxic-ischaemic encephalopathy (cases) and matched controls, and associations with cognitive outcome, hippocampal volume, and diffusivity in the mammillothalamic tract (MTT) and fornix.

METHOD

Mammillary body abnormalities were scored from T1-weighted magnetic resonance imaging (MRI) in 32 cases and 35 controls (median age [interquartile range] 7 years [6 years 7 months-7 years 7 months] and 7 years 4 months [6 years 7 months-7 years 7 months] respectively). Cognition was assessed using the Wechsler Intelligence Scale for Children, Fourth Edition. Hippocampal volume (normalized by total brain volume) was measured from T1-weighted MRI. Radial diffusivity and fractional anisotropy were measured in the MTT and fornix, from diffusion-weighted MRI using deterministic tractography.

RESULTS

More cases than controls had mammillary body abnormalities (34% vs 0%; p < 0.001). Cases with abnormal mammillary bodies had lower processing speed (p = 0.016) and full-scale IQ (p = 0.028) than cases without abnormal mammillary bodies, and lower scores than controls in all cognitive domains (p < 0.05). Cases with abnormal mammillary bodies had smaller hippocampi (left p = 0.016; right p = 0.004) and increased radial diffusivity in the right MTT (p = 0.004) compared with cases without mammillary body abnormalities.

INTERPRETATION

Cooled children with mammillary body abnormalities at school-age have reduced cognitive scores, smaller hippocampi, and altered MTT microstructure compared with those without mammillary body abnormalities, and matched controls.

WHAT THIS PAPER ADDS

Cooled children are at higher risk of mammillary body abnormalities than controls. Abnormal mammillary bodies are associated with reduced cognitive scores and smaller hippocampi. Abnormal mammillary bodies are associated with altered mammillothalamic tract diffusivity.

Normative mammillary body volumes: From the neonatal period to young adult

The mammillary bodies may be small, but they have an important role in encoding complex memories. Mammillary body pathology often occurs following thiamine deficiency but there is increasing evidence that the mammillary bodies are also compromised in other neurological conditions and in younger ages groups. For example, the mammillary bodies are frequently affected in neonates with hypoxic-ischemic encephalopathy. At present, there is no normative data for the mammillary bodies in younger groups making it difficult to identify abnormalities in neurological disorders. To address this, the present study set out to develop a normative dataset for neonates and for children to young adult. A further aim was to determine whether there were laterality or sex differences in mammillary body volumes. Mammillary body volumes were obtained from MRI scans from 506 participants across two datasets. Measures for neonates were acquired from the Developing Human Connectome Project database (156 male; 100 female); volumes for individuals aged 6-24 were acquired from the NICHE database (166 males; 84 females). Volume measurements were acquired using a semi-automated multi-atlas segmentation approach. Mammillary body volumes increased up to approximately 15 years-of-age. The left mammillary body was marginally, but significantly, larger than the right in the neonates with a similar pattern in older children/young adults. In neonates, the mammillary bodies in males were slightly bigger than females but no sex differences were present in older children/young adults. Given the increasing presentation of mammillary body pathology in neonates and children, these normative data will enable better assessment of the mammillary bodies in healthy and at-risk populations.

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.

The Mammillary Bodies: A Review of Causes of Injury in Infants and Children

Despite their small size, the mammillary bodies play an important role in supporting recollective memory. However, they have typically been overlooked when assessing neurologic conditions that present with memory impairment. While there is increasing evidence of mammillary body involvement in a wide range of neurologic disorders in adults, very little attention has been given to infants and children. Literature searches of PubMed and EMBASE were performed to identify articles that describe mammillary body pathology on brain MR imaging in children. Mammillary body pathology is present in the pediatric population in several conditions, indicated by signal change and/or atrophy on MR imaging. The main causes of mammillary body pathology are thiamine deficiency, hypoxia-ischemia, direct damage due to masses or hydrocephalus, or deafferentation resulting from pathology within the wider Papez circuit. Optimizing scanning protocols and assessing mammillary body status as a standard procedure are critical, given their role in memory processes.

Hypoglycemia in Infants with Hypoxic-Ischemic Encephalopathy Is Associated with Additional Brain Injury and Worse Neurodevelopmental Outcome

OBJECTIVE

To determine the incidence of hypoglycemia among infants with hypoxic-ischemic encephalopathy (HIE) who received therapeutic hypothermia, and to assess whether infants with hypoglycemia had more brain injury on magnetic resonance imaging (MRI) or differences in neurodevelopmental outcome.

STUDY DESIGN

Single-center, retrospective cohort study including infants cooled for HIE. Hypoglycemia (blood glucose <36.0 mg/dL <2 hours and <46.8 mg/dL ≥2 hours after birth) was analyzed in the period before brain MRI. Brain injury was graded using a validated score. Motor and neurocognitive outcomes were assessed at 2 years for all survivors, and 5.5 years for a subset who had reached this age.

RESULTS

Of 223 infants analyzed, 79 (35.4%) had hypoglycemia. MRI was performed in 187 infants. Infants with hypoglycemia (n = 65) had higher brain injury scores (P = .018). After adjustment for HIE severity, hypoglycemia remained associated with higher injury scores (3.6 points higher; 95% CI, 0.8-6.4). Hyperglycemia did not affect MRI scores. In survivors at 2 years (n = 154) and 5.5 years (n = 102), a univariable analysis showed lower 2-year motor scores and lower motor and cognitive scores at preschool age in infants with hypoglycemia. After adjustment for HIE severity, infants with hypoglycemia had 9 points lower IQs (P = .023) and higher odds of adverse outcomes at preschool age (3.6; 95% CI, 1.4-9.0).

CONCLUSIONS

More than one-third of infants cooled for HIE had hypoglycemia. These infants had a higher degree of brain injury on MRI and lower cognitive function at preschool age. Strategies to avoid hypoglycemia should be optimized in this setting.

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.

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.

Neurological and developmental outcomes following neonatal encephalopathy treated with therapeutic hypothermia

In randomized trials, therapeutic hypothermia (TH) is associated with reduced prevalence of the composite outcome mortality or neurodevelopmental morbidity in infants with neonatal encephalopathy (NE). Following systematic review, the reduction in prevalence of both mortality and infant neuromorbidity is clear. Among three trials reporting school age outcomes, the effects of NE and TH suggest that such benefit persists into middle childhood, but none of the major trials were powered to detect differences in these outcomes. Cognitive, educational and behavioural outcomes are all adversely affected by NE in children without moderate or severe neuromorbidity. High-quality longitudinal studies of neurocognitive and educational outcomes following NE in the era of TH, including studies incorporating multimodal neuroimaging assessments, are required to characterise deficits more precisely so that robust interventional targets may be developed, and resource planning can occur. Understanding the impact of NE on families and important educational, social, and behavioural outcomes in childhood is critical to attempts to optimise outcomes through interventions.

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.