Brain tissue volumes in preterm infants: prematurity, perinatal risk factors and neurodevelopmental outcome: a systematic review

Intelligence quotient testing in children with hearing loss: A systematic review

OBJECTIVE

The objective of the current study is to perform a systematic review of the research literature to evaluate the impact of hearing loss on intelligence quotient (IQ) scores in pediatric patients.

DATA SOURCES

Ovid MEDLINE, EMBASE, CINAHL, and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched from their inception up to December 21st, 2021.

REVIEW METHODS

Studies evaluating neurocognitive testing and hearing loss in children aged 21 years old or younger who had not undergone auditory rehabilitation were included in the study. Two independent reviewers evaluated titles, abstracts, and full texts for all included studies.

RESULTS

The literature search yielded 3199 studies of which 431 studies underwent full-text screening. 21 studies were ultimately selected for inclusion and contained a total of 1716 pediatric patients assessed through 13 different validated tests of intelligence. Six studies included both hearing impaired (HI) and normal hearing (NH) patients, and IQ testing results.

CONCLUSION

The results of this large systematic review demonstrate that hearing impaired children may perform lower than their age-matched normal hearing peers on IQ testing across a battery of IQ testing modalities.

Cortical growth from infancy to adolescence in preterm and term-born children

Early life experiences can exert a significant influence on cortical and cognitive development. Very preterm birth exposes infants to several adverse environmental factors during hospital admission, which affect cortical architecture. However, the subsequent consequence of very preterm birth on cortical growth from infancy to adolescence has never been defined; despite knowledge of critical periods during childhood for establishment of cortical networks. Our aims were to: chart typical longitudinal cortical development and sex differences in cortical development from birth to adolescence in healthy term-born children; estimate differences in cortical development between children born at term and very preterm; and estimate differences in cortical development between children with normal and impaired cognition in adolescence. This longitudinal cohort study included children born at term (≥37 weeks' gestation) and very preterm (<30 weeks' gestation) with MRI scans at ages 0, 7 and 13 years (n = 66 term-born participants comprising 34 with one scan, 18 with two scans and 14 with three scans; n = 201 very preterm participants comprising 56 with one scan, 88 with two scans and 57 with three scans). Cognitive assessments were performed at age 13 years. Cortical surface reconstruction and parcellation were performed with state-of-the-art, equivalent MRI analysis pipelines for all time points, resulting in longitudinal cortical volume, surface area and thickness measurements for 62 cortical regions. Developmental trajectories for each region were modelled in term-born children, contrasted between children born at term and very preterm, and contrasted between all children with normal and impaired cognition. In typically developing term-born children, we documented anticipated patterns of rapidly increasing cortical volume, area and thickness in early childhood, followed by more subtle changes in later childhood, with smaller cortical size in females than males. In contrast, children born very preterm exhibited increasingly reduced cortical volumes, relative to term-born children, particularly during ages 0-7 years in temporal cortical regions. This reduction in cortical volume in children born very preterm was largely driven by increasingly reduced cortical thickness rather than area. This resulted in amplified cortical volume and thickness reductions by age 13 years in individuals born very preterm. Alterations in cortical thickness development were found in children with impaired language and memory. This study shows that the neurobiological impact of very preterm birth on cortical growth is amplified from infancy to adolescence. These data further inform the long-lasting impact on cortical development from very preterm birth, providing broader insights into neurodevelopmental consequences of early life experiences.

A Preliminary Study of Correlates of Premature Birth and Their Influence on Cortisol Levels in Young Children

OBJECTIVE

The HPA-axis is programmed during early infancy, but a lot is unknown about the programming of the HPA-axis in prematurely born or small for gestational age (SGA) children. Therefore, the aim of this preliminary study was to investigate the influence of prematurity and variables associated with birth on cortisol levels in young children.

METHODS

Cortisol was measured in a cross-sectional design in 38 premature born participants (<37 weeks of gestation), aged between 3 - 9 years old. Correlates of prematurity (degree of prematurity and birth delivery route) were investigated in relationship with cortisol levels with regression analysis.

RESULTS

Corrected for sex, delivery by C-section was associated with lower cortisol levels in the children (ß = -.42, p = .028), with an explained variance of 34%.

CONCLUSION

Birth delivery route by C-section is associated with lowered (or flattened) cortisol levels in children born prematurely. This is clinically relevant and might have important implications, because an HPA-axis disturbance might lead to developmental problems later on in life. However, future research is necessary to investigate the underlying indications for performing a C-section, which will help to understand factors that influence the HPA-axis development in children born prematurely.

Machine Learning-Derived Active Sleep as an Early Predictor of White Matter Development in Preterm Infants

White matter dysmaturation is commonly seen in preterm infants admitted to the neonatal intensive care unit (NICU). Animal research has shown that active sleep is essential for early brain plasticity. This study aimed to determine the potential of active sleep as an early predictor for subsequent white matter development in preterm infants. Using heart and respiratory rates routinely monitored in the NICU, we developed a machine learning-based automated sleep stage classifier in a cohort of 25 preterm infants (12 females). The automated classifier was subsequently applied to a study cohort of 58 preterm infants (31 females) to extract active sleep percentage over 5-7 consecutive days during 29-32 weeks of postmenstrual age. Each of the 58 infants underwent high-quality T2-weighted magnetic resonance brain imaging at term-equivalent age, which was used to measure the total white matter volume. The association between active sleep percentage and white matter volume was examined using a multiple linear regression model adjusted for potential confounders. Using the automated classifier with a superior sleep classification performance [mean area under the receiver operating characteristic curve (AUROC) = 0.87, 95% CI 0.83-0.92], we found that a higher active sleep percentage during the preterm period was significantly associated with an increased white matter volume at term-equivalent age [β = 0.31, 95% CI 0.09-0.53, false discovery rate (FDR)-adjusted p-value = 0.021]. Our results extend the positive association between active sleep and early brain development found in animal research to human preterm infants and emphasize the potential benefit of sleep preservation in the NICU setting.

Impact of Nutritional Status on Total Brain Tissue Volumes in Preterm Infants

Preterm infants bypass the crucial in utero period of brain development and are at increased risk of malnutrition. We aimed to determine if their nutritional status is associated with brain tissue volumes at term equivalent age (TEA), applying recently published malnutrition guidelines for preterm infants. We performed a single center retrospective chart review of 198 infants < 30 weeks' gestation between 2018 and 2021. We primarily analyzed the relationship between the manually obtained neonatal MR-based brain tissue volumes with the maximum weight and length z-score. Significant positive linear associations between brain tissue volumes at TEA and weight and length z-scores were found (p < 0.05). Recommended nutrient intake for preterm infants is not routinely achieved despite efforts to optimize nutrition. Neonatal MR-based brain tissue volumes of preterm infants could serve as objective, quantitative and reproducible surrogate parameters of early brain development. Nutrition is a modifiable factor affecting neurodevelopment and these results could perhaps be used as reference data for future timely nutritional interventions to promote optimal brain volume.

Preterm birth associated alterations in brain structure, cognitive functioning and behavior in children from the ABCD dataset

BACKGROUND

Preterm birth is a global health problem and associated with increased risk of long-term developmental impairments, but findings on the adverse outcomes of prematurity have been inconsistent.

METHODS

Data were obtained from the baseline session of the ongoing longitudinal Adolescent Brain and Cognitive Development (ABCD) Study. We identified 1706 preterm children and 1865 matched individuals as Control group and compared brain structure (MRI data), cognitive function and mental health symptoms.

RESULTS

Results showed that preterm children had higher psychopathological risk and lower cognitive function scores compared to controls. Structural MRI analysis indicated that preterm children had higher cortical thickness in the medial orbitofrontal cortex, parahippocampal gyrus, temporal and occipital gyrus; smaller volumes in the temporal and parietal gyrus, cerebellum, insula and thalamus; and smaller fiber tract volumes in the fornix and parahippocampal-cingulum bundle. Partial correlation analyses showed that gestational age and birth weight were associated with ADHD symptoms, picvocab, flanker, reading, fluid cognition composite, crystallized cognition composite and total cognition composite scores, and measures of brain structure in regions involved with emotional regulation, attention and cognition.

CONCLUSIONS

These findings suggest a complex interplay between psychopathological risk and cognitive deficits in preterm children that is associated with changes in regional brain volumes, cortical thickness, and structural connectivity among cortical and limbic brain regions critical for cognition and emotional well-being.

Interaction of hydrocortisone and illness severity on head growth in cohort of ELBW infants

BACKGROUND

Extremely low birth weight (ELBW) infants comprise a fragile population at risk for neurodevelopmental disabilities (NDD). Systemic steroids were previously associated with NDD, but more recent studies suggest hydrocortisone (HCT) may improve survival without increasing NDD. However, the effects of HCT on head growth adjusted for illness severity during NICU hospitalization are unknown. Thus, we hypothesize that HCT will protect head growth, accounting for illness severity using a modified neonatal Sequential Organ Failure Assessment (M-nSOFA) score.

METHODS

We conducted a retrospective study that included infants born at 23-29 weeks gestational age (GA) and < 1000 g. Our study included 73 infants, 41% of whom received HCT.

RESULTS

We found negative correlations between growth parameters and age, similar between HCT and control patients. HCT-exposed infants had lower GA but similar normalized birth weights; HCT-exposed infants also had higher illness severity and longer lengths of hospital stay. We found an interaction between HCT exposure and illness severity on head growth, such that infants exposed to HCT had better head growth compared to those not exposed to HCT when adjusted for illness severity.

CONCLUSION

These findings emphasize the importance of considering patient illness severity and suggest that HCT use may offer additional benefits not previously considered.

IMPACT

This is the first study to assess the relationship between head growth and illness severity in extremely preterm infants with extremely low birth weights during their initial NICU hospitalization. Infants exposed to hydrocortisone (HCT) were overall more ill than those not exposed, yet HCT exposed infants had better preserved head growth relative to illness severity. Better understanding of the effects of HCT exposure on this vulnerable population will help guide more informed decisions on the relative risks and benefits for HCT use.

The influence of very preterm birth on adolescent EEG connectivity, network organization and long-term outcome

OBJECTIVE

The aim of this study was to explore differences in functional connectivity and network organization between very preterm born adolescents and term born controls and to investigate if these differences might explain the relation between preterm birth and adverse long-term outcome.

METHODS

Forty-seven very preterm born adolescents (53% males) and 54 controls (54% males) with matching age, sex and parental educational levels underwent high-density electroencephalography (EEG) at 13 years of age. Long-term outcome was assessed by Intelligence Quotient (IQ), motor, attentional functioning and academic performance. Two minutes of EEG data were analysed within delta, theta, lower alpha, upper alpha and beta frequency bands. Within each frequency band, connectivity was assessed using the Phase Lag Index (PLI) and Amplitude Envelope Correlation, corrected for volume conduction (AEC-c). Brain networks were constructed using the minimum spanning tree method.

RESULTS

Very preterm born adolescents had stronger beta PLI connectivity and less differentiated network organization. Beta AEC-c and differentiation of AEC-c based networks were negatively associated with long-term outcomes. EEG measures did not mediate the relation between preterm birth and outcomes.

CONCLUSIONS

This study shows that very preterm born adolescents may have altered functional connectivity and brain network organization in the beta frequency band. Alterations in measures of functional connectivity and network topologies, especially its differentiating characteristics, were associated with neurodevelopmental functioning.

SIGNIFICANCE

The findings indicate that EEG connectivity and network analysis is a promising tool for investigating underlying mechanisms of impaired functioning.

The impact of cumulative obstetric complications and childhood trauma on brain volume in young people with psychotic experiences

Psychotic experiences (PEs) occur in 5-10% of the general population and are associated with exposure to childhood trauma and obstetric complications. However, the neurobiological mechanisms underlying these associations are unclear. Using the Avon Longitudinal Study of Parents and Children (ALSPAC), we studied 138 young people aged 20 with PEs (n = 49 suspected, n = 53 definite, n = 36 psychotic disorder) and 275 controls. Voxel-based morphometry assessed whether MRI measures of grey matter volume were associated with (i) PEs, (ii) cumulative childhood psychological trauma (weighted summary score of 6 trauma types), (iii) cumulative pre/peri-natal risk factors for psychosis (weighted summary score of 16 risk factors), and (iv) the interaction between PEs and cumulative trauma or pre/peri-natal risk. PEs were associated with smaller left posterior cingulate (pFWE < 0.001, Z = 4.19) and thalamus volumes (pFWE = 0.006, Z = 3.91). Cumulative pre/perinatal risk was associated with smaller left subgenual cingulate volume (pFWE < 0.001, Z = 4.54). A significant interaction between PEs and cumulative pre/perinatal risk found larger striatum (pFWE = 0.04, Z = 3.89) and smaller right insula volume extending into the supramarginal gyrus and superior temporal gyrus (pFWE = 0.002, Z = 4.79), specifically in those with definite PEs and psychotic disorder. Cumulative childhood trauma was associated with larger left dorsal striatum (pFWE = 0.002, Z = 3.65), right prefrontal cortex (pFWE < 0.001, Z = 4.63) and smaller left insula volume in all participants (pFWE = 0.03, Z = 3.60), and there was no interaction with PEs group. In summary, pre/peri-natal risk factors and childhood psychological trauma impact similar brain pathways, namely smaller insula and larger striatum volumes. The effect of pre/perinatal risk was greatest in those with more severe PEs, whereas effects of trauma were seen in all participants. In conclusion, environmental risk factors affect brain networks implicated in schizophrenia, which may increase an individual's propensity to develop later psychotic disorders.

Novel metrics to characterize temporal lobe of very preterm infants on term-equivalent brain MRI

BACKGROUND

Preterm birth adversely impacts brain development and contributes to neurodevelopmental impairment; the temporal lobe may be particularly vulnerable to the impact of very preterm (VP) birth. Yet, no prior magnetic resonance imaging (MRI) scoring system incorporated a method to quantify temporal lobe size in VP infants.

METHODS

We developed and applied three metrics (temporal lobe length, extra-axial space, and temporal horn width) to quantify temporal lobe structure on term-equivalent brain MRIs obtained from 74 VP and 16 term infants. We compared metrics between VP and term infants and explored associations of each metric with perinatal risk factors.

RESULTS

All metrics had excellent reliability (intra-class correlation coefficient 0.62-0.98). VP infants had lower mean temporal lobe length (76.8 mm versus 79.2 mm, p = 0.02); however, the difference attenuated after correction for postmenstrual age. VP infants had larger temporal horn widths compared with term infants (2.6 mm versus 1.8 mm, p < 0.001). Temporal lobe length was positively associated with gestational age, birth weight, and male sex, and negatively associated with the duration of parenteral nutrition.

CONCLUSIONS

The proposed metrics are reliable and sensitive in distinguishing differences in temporal lobe development between VP and full-term infants.

IMPACT

We developed a novel method for quantifying temporal lobe size among very preterm infants at term equivalent using simple metrics performed on brain MRI. Temporal lobe metrics were reliable, correlated with brain volume from volumetric analysis, and were sensitive in identifying differences in temporal lobe development among preterm compared with term infants, specifically larger temporal horn size in preterm infants. This temporal lobe metric system will enable future work to delineate the perinatal and postnatal factors that impact temporal lobe growth, and better understand the relationship between temporal lobe disturbance and neurodevelopment in very preterm infants.

Meta-Analysis of Hippocampal Volume and Episodic Memory in Preterm and Term Born Individuals

Preterm birth (< 37 weeks gestation) has been associated with memory deficits, which has prompted investigation of possible alterations in hippocampal volume in this population. However, existing literature reports varying effects of premature birth on hippocampal volume. Specifically, it is unclear whether smaller hippocampal volume in preterm-born individuals is merely reflective of smaller total brain volume. Further, it is not clear if hippocampal volume is associated with episodic memory functioning in preterm-born individuals. Meta-analysis was used to investigate the effects of premature birth on hippocampal volume and episodic memory from early development to young adulthood (birth to 26). PubMed, PsychINFO, and Web of Science were searched for English peer-reviewed articles that included hippocampal volume of preterm and term-born individuals. Thirty articles met the inclusion criteria. Separate meta-analyses were used to evaluate standardized mean differences between preterm and term-born individuals in uncorrected and corrected hippocampal volume, as well as verbal and visual episodic memory. Both uncorrected and corrected hippocampal volume were smaller in preterm-born compared to term-born individuals. Although preterm-born individuals had lower episodic memory performance than term-born individuals, the limited number of studies only permitted a qualitative review of the association between episodic memory performance and hippocampal volume. Tested moderators included mean age, pre/post-surfactant era, birth weight, gestational age, demarcation method, magnet strength, and slice thickness. With this meta-analysis, we provide novel evidence of the effects of premature birth on hippocampal volume.

Long-lasting effects of very preterm birth on brain structure in adulthood: A systematic review and meta-analysis

Early life experiences, such as very preterm (VP) birth, can affect brain and cognitive development. Several prior studies investigated brain structure in adults born VP; synthesising these studies may help to provide a clearer understanding of long-term effects of VP birth on the brain. We systematically searched Medline and Embase for articles that investigated brain structure using MRI in adulthood in individuals born VP (<32 weeks' gestation) or with very low birth weight (VLBW; <1500 g), and controls born at term or with normal birth weight. In total, 77 studies met the review inclusion criteria, of which 28 studies were eligible for meta-analyses, including data from up to 797 VP/VLBW participants and 518 controls, aged 18-33 years. VP/VLBW adults exhibited volumetric, morphologic and microstructural alterations in subcortical and temporal cortical regions compared with controls, with pooled standardised mean differences up to - 1.0 (95% confidence interval: -1.2, -0.8). This study suggests there is a persisting neurological impact of VP birth, which may provide developmental neurobiological insights for adult cognition in high-risk populations.

Brain Biometry Reveals Impaired Brain Growth in Preterm Neonates with Intraventricular Hemorrhage

INTRODUCTION

Preterm birth and cerebral hemorrhage have adverse effects on brain development. Alterations in regional brain size on magnetic resonance imaging (MRI) can be assessed using 2D biometrical analysis, an easily applicable technique showing good correlation with 3D brain volumes.

METHODS

This retrospective study included 74 preterm neonates with intraventricular hemorrhage (IVH) born <32+0 weeks of gestation between 2011 and 2019. Cerebral MRI was performed at term-equivalent age, and 2D measurement techniques were used for biometrical analysis and compared to normative data of two control groups. Finally, the correlation and association of brain parameters and patterns of impaired brain growth and outcome at 2 and 3 years of age were evaluated.

RESULTS

Interhemispheric distance (IHD), the 3rd ventricle, and lateral ventricles presented larger, in contrast, cerebral biparietal width (cBPW), fronto-occipital diameter (FOD), and the length of the corpus callosum were smaller in IVH patients compared to respective controls. The strongest correlations with outcome were observed for the parameters FOD, anteroposterior diameter of the vermis, transverse cerebellar diameter (tCD), corpus callosum, 3rd ventricle, and left ventricular index. Patients with the small FOD, small BPW, and increased IHD pattern reached overall lower outcome scores at follow-up.

DISCUSSION

Preterm neonates with IVH showed reduced total brain sizes and enlarged pericerebral spaces compared to neurologically healthy controls. Biometric analysis revealed that several 2D brain parameters as well as different patterns of impaired brain growth were associated with neurodevelopmental impairment in early childhood. These findings may support prediction of long-term outcome and parental counseling in patients with IVH.

Behavioral outcome of very preterm children at 5 years of age: Prognostic utility of brain tissue volumes at term-equivalent-age, perinatal, and environmental factors

OBJECTIVE

Prematurity is associated with a high risk of long-term behavioral problems. This study aimed to assess the prognostic utility of volumetric brain data at term-equivalent-age (TEA), clinical perinatal factors, and parental social economic risk in the prediction of the behavioral outcome at 5 years in a cohort of very preterm infants (VPT, <32 gestational weeks).

METHODS

T2-weighted magnetic resonance brain images of 80 VPT children were acquired at TEA and automatically segmented into cortical gray matter, deep subcortical gray matter, white matter (WM), cerebellum (CB), and cerebrospinal fluid. The gray matter structure of the amygdala was manually segmented. Children were examined at 5 years of age with a behavioral assessment, using the strengths and difficulties questionnaire (SDQ). The utility of brain volumes at TEA, perinatal factors, and social economic risk for the prediction of behavioral outcome was investigated using support vector machine classifiers and permutation feature importance.

RESULTS

The predictive modeling of the volumetric data showed that WM, amygdala, and CB volumes were the best predictors of the SDQ emotional symptoms score. Among the perinatal factors, sex, sepsis, and bronchopulmonary dysplasia were the best predictors of the hyperactivity/inattention score. When combining the social economic risk with volumetric and perinatal factors, we were able to accurately predict the emotional symptoms score. Finally, social economic risk was positively correlated with the scores of conduct problems and peer problems.

CONCLUSIONS

This study provides information on the relation between brain structure at TEA and clinical perinatal factors with behavioral outcome at age 5 years in VPT children. Nevertheless, the overall predictive power of our models is relatively modest, and further research is needed to identify factors associated with subsequent behavioral problems in this population.

Postnatal serum IGF-1 levels associate with brain volumes at term in extremely preterm infants

BACKGROUND

Growth factors important for normal brain development are low in preterm infants. This study investigated the link between growth factors and preterm brain volumes at term.

MATERIAL/METHODS

Infants born <28 weeks gestational age (GA) were included. Endogenous levels of insulin-like growth factor (IGF)-1, brain-derived growth factor, vascular endothelial growth factor, and platelet-derived growth factor (expressed as area under the curve [AUC] for serum samples from postnatal days 1, 7, 14, and 28) were utilized in a multivariable linear regression model. Brain volumes were determined by magnetic resonance imaging (MRI) at term equivalent age.

RESULTS

In total, 49 infants (median [range] GA 25.4 [22.9-27.9] weeks) were included following MRI segmentation quality assessment and AUC calculation. IGF-1 levels were independently positively associated with the total brain (p < 0.001, β = 0.90), white matter (p = 0.007, β = 0.33), cortical gray matter (p = 0.002, β = 0.43), deep gray matter (p = 0.008, β = 0.05), and cerebellar (p = 0.006, β = 0.08) volume adjusted for GA at birth and postmenstrual age at MRI. No associations were seen for other growth factors.

CONCLUSIONS

Endogenous exposure to IGF-1 during the first 4 weeks of life was associated with total and regional brain volumes at term. Optimizing levels of IGF-1 might improve brain growth in extremely preterm infants.

IMPACT

High serum levels of insulin-like growth factor (IGF)-1 during the first month of life were independently associated with increased total brain volume, white matter, gray matter, and cerebellar volume at term equivalent age in extremely preterm infants. IGF-1 is a critical regulator of neurodevelopment and postnatal levels are low in preterm infants. The effects of IGF-1 levels on brain development in extremely preterm infants are not fully understood. Optimizing levels of IGF-1 may benefit early brain growth in extremely preterm infants. The effects of systemically administered IGF-1/IGFBP3 in extremely preterm infants are now being investigated in a randomized controlled trial (Clinicaltrials.gov: NCT03253263).

Early structural connectivity within the sensorimotor network: Deviations related to prematurity and association to neurodevelopmental outcome

Consisting of distributed and interconnected structures that interact through cortico-cortical connections and cortico-subcortical loops, the sensorimotor (SM) network undergoes rapid maturation during the perinatal period and is thus particularly vulnerable to preterm birth. However, the impact of prematurity on the development and integrity of the emerging SM connections and their relationship to later motor and global impairments are still poorly understood. In this study we aimed to explore to which extent the early microstructural maturation of SM white matter (WM) connections at term-equivalent age (TEA) is modulated by prematurity and related with neurodevelopmental outcome at 18 months corrected age. We analyzed 118 diffusion MRI datasets from the developing Human Connectome Project (dHCP) database: 59 preterm (PT) low-risk infants scanned near TEA and a control group of full-term (FT) neonates paired for age at MRI and sex. We delineated WM connections between the primary SM cortices (S1, M1 and paracentral region) and subcortical structures using probabilistic tractography, and evaluated their microstructure with diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) models. To go beyond tract-specific univariate analyses, we computed a maturational distance related to prematurity based on the multi-parametric Mahalanobis distance of each PT infant relative to the FT group. Our results confirmed the presence of microstructural differences in SM tracts between PT and FT infants, with effects increasing with lower gestational age at birth. Maturational distance analyses highlighted that prematurity has a differential effect on SM tracts with higher distances and thus impact on (i) cortico-cortical than cortico-subcortical connections; (ii) projections involving S1 than M1 and paracentral region; and (iii) the most rostral cortico-subcortical tracts, involving the lenticular nucleus. These different alterations at TEA suggested that vulnerability follows a specific pattern coherent with the established WM caudo-rostral progression of maturation. Finally, we highlighted some relationships between NODDI-derived maturational distances of specific tracts and fine motor and cognitive outcomes at 18 months. As a whole, our results expand understanding of the significant impact of premature birth and early alterations on the emerging SM network even in low-risk infants, with possible relationship with neurodevelopmental outcomes. This encourages further exploration of these potential neuroimaging markers for prediction of neurodevelopmental disorders, with special interest for subtle neuromotor impairments frequently observed in preterm-born children.

Direct and indirect effects on child neurocognitive development when maternal cancer is diagnosed during pregnancy: What do we know so far?

Cancer during pregnancy threatens the lives of mother and foetus and its incidence is rising, making it an emerging medical challenge. Evidence on the direct impact of cancer therapies on neonatal outcomes resulted in general guidelines for maternal treatment that safeguards foetal development. Less focus has been placed on indirect factors, in pre- and postnatal periods, that may exert long-term impacts specifically on child neurocognition. Foetal development, in the context of maternal cancer during pregnancy, may be influenced directly by exposure to cancer diagnostics and (co-)treatment, or indirectly through maternal inflammation, malnutrition, hormonal fluctuations, prematurity, and psycho-biological stress. Maternal stress and insecure mother-infant bonding related to postpartum cancer treatment may further impact child cognitive-behavioural development. Understanding the independent and synergistic effects of the factors impacting neurocognitive development creates the opportunity to intervene during the oncological treatment to improve the child's long-term outcome, both by medical and psychosocial care and support.

Sensory-based interventions in the NICU: systematic review of effects on preterm brain development

BACKGROUND

Infants born preterm are known to be at risk for abnormal brain development and adverse neurobehavioral outcomes. To improve early neurodevelopment, several non-pharmacological interventions have been developed and implemented in the neonatal intensive care unit (NICU). Sensory-based interventions seem to improve short-term neurodevelopmental outcomes in the inherently stressful NICU environment. However, how this type of intervention affects brain development in the preterm population remains unclear.

METHODS

A systematic review of the literature was conducted for published studies in the past 20 years reporting the effects of early, non-pharmacological, sensory-based interventions on the neonatal brain after preterm birth.

RESULTS

Twelve randomized controlled trials (RCT) reporting short-term effects of auditory, tactile, and multisensory interventions were included after the screening of 1202 articles. Large heterogeneity was identified among studies in relation to both types of intervention and outcomes. Three areas of focus for sensory interventions were identified: auditory-based, tactile-based, and multisensory interventions.

CONCLUSIONS

Diversity in interventions and outcome measures challenges the possibility to perform an integrative synthesis of results and to translate these for evidence-based clinical practice. This review identifies gaps in the literature and methodological challenges for the implementation of RCTs of sensory interventions in the NICU.

IMPACT

This paper represents the first systematic review to investigate the effect of non-pharmacological, sensory-based interventions in the NICU on neonatal brain development. Although reviewed RCTs present evidence on the impact of such interventions on the neonatal brain following preterm birth, it is not yet possible to formulate clear guidelines for clinical practice. This review integrates existing literature on the effect of sensory-based interventions on the brain after preterm birth and identifies methodological challenges for the conduction of high-quality RCTs.

Brain tissue microstructural and free-water composition 13 years after very preterm birth

There have been many studies demonstrating children born very preterm exhibit brain white matter microstructural alterations, which have been related to neurodevelopmental difficulties. These prior studies have often been based on diffusion MRI modelling and analysis techniques, which commonly focussed on white matter microstructural properties in very preterm-born children. However, there have been relatively fewer studies investigating the free-water content of the white matter, and also the microstructure and free-water content of the cortical grey matter, in very preterm-born children. These biophysical properties of the brain change rapidly during fetal and neonatal brain development, and therefore such properties are likely also adversely affected by very preterm birth. In this study, we investigated the relationship of very preterm birth (<30 weeks' gestation) to both white matter and cortical grey matter microstructure and free-water content in childhood using advanced diffusion MRI analyses. A total of 130 very preterm participants and 45 full-term control participants underwent diffusion MRI at age 13 years. Diffusion tissue signal fractions derived by Single-Shell 3-Tissue Constrained Spherical Deconvolution were used to investigate brain tissue microstructural and free-water composition. The tissue microstructural and free-water composition metrics were analysed using a bespoke voxel-based analysis and cortical region-of-interest analysis approach. Very preterm 13-year-olds exhibited reduced white matter microstructural density and increased free-water content across widespread regions of the white matter compared with controls. Additionally, very preterm 13-year-olds exhibited reduced microstructural density and increased free-water content in specific temporal, sensorimotor, occipital and cingulate cortical regions. These brain tissue composition alterations were strongly associated with cerebral white matter abnormalities identified in the neonatal period, and concurrent adverse cognitive and motor outcomes in very preterm children. The findings demonstrate brain microstructural and free-water alterations up to thirteen years from neonatal brain abnormalities in very preterm children that relate to adverse neurodevelopmental outcomes.

Erythropoietin as a Neuroprotective Drug for Newborn Infants: Ten Years after the First Use

Protective strategies against perinatal brain injury represent a major challenge for modern neonatology. Erythropoietin (Epo) enhances endogenous mechanisms of repair and angiogenesis. In order to analyse the newest evidence on the role of Epo in prematurity, hypoxic ischemic encephalopathy (HIE) and perinatal stroke, a critical review using 2020 PRISMA statement guidelines was conducted. This review uncovered 26 clinical trials examining the use of Epo for prematurity and brain injury-related outcomes. The effects of Epo on prematurity were analysed in 16 clinical trials. Erythropoietin was provided until 32–35 weeks of corrected postnatal age with a dosage between 500–3000 UI/kg/dose. Eight trials reported the Epo effects on HIE term newborn infants: Erythropoietin was administered in the first weeks of life, at different multiple doses between 250–2500 UI/kg/dose, as either an adjuvant therapy with hypothermia or a substitute for hypothermia. Two trials investigated Epo effects in perinatal stroke. Erythropoietin was administered at a dose of 1000 IU/kg for three days. No beneficial effect in improving morbidity was observed after Epo administration in perinatal stroke. A positive effect on neurodevelopmental outcome seems to occur when Epo is used as an adjuvant therapy with hypothermia in the HIE newborns. Administration of Epo in preterm infants still presents inconsistencies with regard to neurodevelopmental outcome. Clinical trials show significant differences mainly in target population and intervention scheme. The identification of specific markers and their temporal expression at different time of recovery after hypoxia-ischemia in neonates might be implemented to optimize the therapeutic scheme after hypoxic-ischemic injury in the developing brain. Additional studies on tailored regimes, accounting for the risk stratification of brain damage in newborns, are required.

Head circumference, total cerebral volume and neurodevelopment in preterm neonates

OBJECTIVES

To assess the association of head circumference (HC) <10th percentile at birth and discharge from the neonatal intensive care unit (NICU) with neurodevelopment in very preterm (24-32 weeks' gestational age) neonates, and to compare the association of HC and total cerebral volume (TCV) with neurodevelopmental outcomes.

DESIGN

In a prospective cohort, semiautomatically segmented TCV and manually segmented white matter injury (WMI) volumes were obtained. Multivariable regressions were used to study the association of HC and TCV with neurodevelopmental outcomes, accounting for birth gestational age, WMI and postnatal illness.

SETTING

Participants born in 2006-2013 at British Columbia Women's Hospital were recruited.

PATIENTS

168 neonates had HC measurements at birth and discharge and MRI at term-equivalent age (TEA). 143 children were assessed at 4.5 years.

MAIN OUTCOME MEASURES

Motor, cognitive and language outcomes at 4.5 years were assessed using the Movement Assessment Battery for Children Second Edition (M-ABC) and Wechsler Preschool and Primary Scale of Intelligence Third Edition Full Scale IQ (FSIQ) and Verbal IQ (VIQ).

RESULTS

Small birth HC was associated with lower M-ABC and FSIQ scores. In children with small birth HC, small discharge HC was associated with lower M-ABC, FSIQ and VIQ scores, while normal HC at discharge was no longer associated with adverse outcomes. HC strongly correlated with TCV at TEA. TCV did not correlate with outcomes.

CONCLUSIONS

Small birth HC is associated with poorer neurodevelopment, independent of postnatal illness and WMI. Normalisation of HC during NICU care appears to moderate this risk.

Infants' prenatal exposure to opioids and the association with birth outcomes: A systematic review and meta-analysis

BACKGROUND

Prenatal exposure to opioids (PEO) is a worldwide public health issue. Opioids cross the placental barrier and may affect the developing foetus and the birth outcomes.

OBJECTIVES

This review aimed to explore newborns' weight, length and head circumference, preterm birth, and perinatal death as primary outcomes in relation to PEO. The secondary outcomes were gestational age at birth, Apgar scores and length of hospitalisation after delivery.

DATA SOURCES

PubMed, Embase, PsycInfo and the Web of Science.

STUDY SELECTION AND DATA EXTRACTION

Inclusion criteria were (i) cohort, case-control or cross-sectional peer-reviewed studies published in English through 1 March 2021; (ii) comparing outcomes between prenatal exposed and unexposed groups to opioids (prescribed or obtained illegally). Exclusion criteria were foetal alcohol syndrome and non-opioid primary exposure.

SYNTHESIS

Data were extracted by two authors. The Newcastle-Ottawa Quality Assessment Scale was used for study quality assessment. Due to heterogeneity across studies, we used random effects models to obtain pooled standardised mean difference (SMD), pooled risk ratio (RR) and 95% confidence interval (CI).

RESULTS

Data from 80 studies were extracted. In meta-analyses, opioid-exposed neonates had lower birthweight (SMD -0.77, 95% CI -0.90, -0.64, I²  = 82%), smaller head circumference (SMD -0.67, 95% CI -0.86, -0.48, I²  = 84%), shorter birth length (SMD -0.97, 95% CI -1.24, -0.70, I²  = 91%) and gestational age (SMD -0.45, 95% CI -0.60, -0.30, I²  = 80%) than unexposed neonates. Pooled risks of neonatal death and preterm birth were higher among opioid-exposed compared to unexposed neonates (RR 4.05, 95% CI 2.12, 7.72, I²  = 73%; and RR 1.92, 95% CI 1.57, 2.35, I²  = 99%).

CONCLUSIONS

We found increased risks of adverse birth outcomes in relation to PEO. Caution should be used in interpreting the findings, as many studies were rated as poor quality, and with substantial inter-study heterogeneity. Future studies should ensure comparability of opioid-exposed and -unexposed group to strengthen internal validity.

Evaluation of the correlation of the new Ballard scoring with the ultrasonographic optical nerve sheath diameter and brain volume of preterm infants

BACKGROUND

Optic nerve sheath diameter (ONSD) measurements with magnetic resonance imaging and ultrasonography in preterm infants are similar.

AIM

We measured ultrasonographic ONSD and calculated the brain volumes of preterm infants using two-dimensional cranial ultrasonography and explored the relationships thereof with gestational age, birth weight, head circumference, and new Ballard score.

METHOD

This prospective study included preterm infants admitted to the neonatal intensive care unit without intracranial pathology. Two images per eye were obtained from a linear array ultrasound transducer placed on the patient's superior eyelid. The ONSD was measured 3 mm behind the globe. The brain was considered an ellipsoid, and estimated absolute brain volumes were calculated by subtracting the volumes of the two lateral ventricles from the total brain volumes.

RESULTS

A total of 143 preterm infants (male 74, female 69) included in the study. The mean gestational age of the study population was 29.7 weeks (23-36), and the mean birth weight was 1390 g (500-2850). There was a significant difference in ONSD between the male and female gender. A significant, strong, and positive correlation was found between ONSD measurements and gestational age (r 0.901, p < 0.001), new Ballard score (r 0.946, p < 0.001), birth weight, head circumference, and brain volumes.

CONCLUSION

Our results suggested that ONSD measurements are highly correlated with anthropometry, and it could be a promising bedside, non-invasive objective tool for the determination of exact gestational age postnatally along with the new Ballard score.

Serum docosahexaenoic acid levels are associated with brain volumes in extremely preterm born infants

BACKGROUND

Docosahexaenoic acid (DHA) and arachidonic acid (AA) are important for fetal brain growth and development. Our aim was to evaluate the association between serum DHA and AA levels and brain volumes in extremely preterm infants.

METHODS

Infants born at <28 weeks gestational age in 2013-2015, a cohort derived from a randomized controlled trial comparing two types of parenteral lipid emulsions, were included (n = 90). Serum DHA and AA levels were measured at postnatal days 1, 7, 14, and 28, and the area under the curve was calculated. Magnetic resonance (MR) imaging was performed at term-equivalent age (n = 66), and volumes of six brain regions were automatically generated.

RESULTS

After MR image quality assessment and area under the curve calculation, 48 infants were included (gestational age mean [SD] 25.5 [1.4] weeks). DHA levels were positively associated with total brain (B = 7.966, p = 0.012), cortical gray matter (B = 3.653, p = 0.036), deep gray matter (B = 0.439, p = 0.014), cerebellar (B = 0.932, p = 0.003), and white matter volume (B = 3.373, p = 0.022). AA levels showed no association with brain volumes.

CONCLUSIONS

Serum DHA levels during the first 28 postnatal days were positively associated with volumes of several brain structures in extremely preterm infants at term-equivalent age.

IMPACT

Higher serum levels of DHA in the first 28 postnatal days are positively associated with brain volumes at term-equivalent age in extremely preterm born infants. Especially the most immature infants suffer from low DHA levels in the first 28 postnatal days, with little increase over time. Future research is needed to explore whether postnatal fatty acid supplementation can improve brain development and may serve as a nutritional preventive and therapeutic treatment option in extremely preterm infants.

Relationship between the Quantitative Indicators of Cranial MRI and the Early Neurodevelopment of Preterm Infants

Aim

To explore the relationship between the quantitative indicators (biparietal width, interhemispheric distance) of the cranial MRI for preterm infants at 37 weeks of postmenstrual age (PMA) and neurodevelopment at 6 months of corrected age.

Methods

A total of 113 preterm infants (gestational age < 37 weeks) delivered in the Obstetrics Department of the First People's Hospital of Lianyungang from September 2018 to February 2020 and directly transferred to the Neonatology Department for treatment were enrolled in this study. Based on their development quotient (DQ), the patients were divided into the normal (DQ ≥ 85, n = 76) group and the abnormal (DQ < 85, n = 37) group. Routine cranial MRI (cMRI) was performed at 37 weeks of PMA to measure the biparietal width (BPW) and interhemispheric distance (IHD). At the corrected age of 6 months, Development Screening Test (for children under six) was used to assess the participants' neurodevelopment.

Results

Univariate analysis showed statistically significant differences in BPW, IHD, and the incidence of bronchopulmonary dysplasia between the normal and the abnormal groups (P < 0.05), while no statistically significant differences were found in maternal complications and other clinical conditions between the two groups (P > 0.05). Binary logistic regression analysis demonstrated statistically significant differences in IHD and BPW between the normal and the abnormal groups (95% CI: 1.629-12.651 and 0.570-0.805, respectively; P = 0.004 and P < 0.001, respectively), while no significant differences were found in the incidence of bronchopulmonary dysplasia between the two groups (95% CI: 0.669-77.227, P = 0.104). Receiver operating characteristic curve revealed that the area under the curve of BPW, IHD, and the joint predictor (BPW + IHD) were 0.867, 0.805, and 0.881, respectively (95% CI: 0.800-0.933, 0.710-0.900, and 0.819-0.943, respectively; all P values < 0.001).

Conclusion

BPW and IHD, the two quantitative indicators acquired by cMRI, could predict the neurodevelopmental outcome of preterm infants at the corrected age of 6 months. The combination of the two indicators showed an even higher predictive value.

Association between brain structural network efficiency at term-equivalent age and early development of cerebral palsy in very preterm infants

Very preterm infants (born at less than 32 weeks gestational age) are at high risk for serious motor impairments, including cerebral palsy (CP). The brain network changes that antecede the early development of CP in infants are not well characterized, and a better understanding may suggest new strategies for risk-stratification at term, which could lead to earlier access to therapies. Graph theoretical methods applied to diffusion MRI-derived brain connectomes may help quantify the organization and information transfer capacity of the preterm brain with greater nuance than overt structural or regional microstructural changes. Our aim was to shed light on the pathophysiology of early CP development, before the occurrence of early intervention therapies and other environmental confounders, to help identify the best early biomarkers of CP risk in VPT infants. In a cohort of 395 very preterm infants, we extracted cortical morphometrics and brain volumes from structural MRI and also applied graph theoretical methods to diffusion MRI connectomes, both acquired at term-equivalent age. Metrics from graph network analysis, especially global efficiency, strength values of the major sensorimotor tracts, and local efficiency of the motor nodes and novel non-motor regions were strongly inversely related to early CP diagnosis. These measures remained significantly associated with CP after correction for common risk factors of motor development, suggesting that metrics of brain network efficiency at term may be sensitive biomarkers for early CP detection. We demonstrate for the first time that in VPT infants, early CP diagnosis is anteceded by decreased brain network segregation in numerous nodes, including motor regions commonly-associated with CP and also novel regions that may partially explain the high rate of cognitive impairments concomitant with CP diagnosis. These advanced MRI biomarkers may help identify the highest risk infants by term-equivalent age, facilitating earlier interventions that are informed by early pathophysiological changes.

The Role of Extracellular Vesicles in the Developing Brain: Current Perspective and Promising Source of Biomarkers and Therapy for Perinatal Brain Injury

This comprehensive review focuses on our current understanding of the proposed physiological and pathological functions of extracellular vesicles (EVs) in the developing brain. Furthermore, since EVs have attracted great interest as potential novel cell-free therapeutics, we discuss advances in the knowledge of stem cell- and astrocyte-derived EVs in relation to their potential for protection and repair following perinatal brain injury. This review identified 13 peer-reviewed studies evaluating the efficacy of EVs in animal models of perinatal brain injury; 12/13 utilized mesenchymal stem cell-derived EVs (MSC-EVs) and 1/13 utilized astrocyte-derived EVs. Animal model, method of EV isolation and size, route, timing, and dose administered varied between studies. Notwithstanding, EV treatment either improved and/or preserved perinatal brain structures both macroscopically and microscopically. Additionally, EV treatment modulated inflammatory responses and improved brain function. Collectively this suggests EVs can ameliorate, or repair damage associated with perinatal brain injury. These findings warrant further investigation to identify the optimal cell numbers, source, and dosage regimens of EVs, including long-term effects on functional outcomes.

Ultrasound measurements of brain structures differ between moderate-late preterm and full-term infants at term equivalent age

BACKGROUND

Brain growth in moderate preterm (MP; gestational age (GA) 32⁺⁰-33⁺⁶ weeks) and late preterm infants (LP; GA 34⁺⁰-36⁺⁶ weeks) may be impaired, even in the absence of brain injury.

AIMS

The aims of this study were to assess brain measurements of MP and LP infants, and to compare these with full-term infants (GA > 37 weeks) using linear cranial ultrasound (cUS) at term equivalent age (TEA).

STUDY DESIGN

cUS data from two prospective cohorts were combined. Two investigators performed offline measurements on standard cUS planes. Eleven brain structures were compared between MP, LP and full-term infants using uni- and multivariable linear regression. Results were adjusted for postmenstrual age at cUS and corrected for multiple testing.

RESULTS

Brain measurements of 44 MP, 54 LP and 52 full-term infants were determined on cUS scans at TEA. Biparietal diameter and basal ganglia-insula width were smaller in MP (-9.1 mm and - 1.7 mm, p < 0.001) and LP infants (-7.0 mm and - 1.7 mm, p < 0.001) compared to full-term infants. Corpus callosum - fastigium length was larger in MP (+2.2 mm, p < 0.001) than in full-term infants. No significant differences were found between MP and LP infants.

CONCLUSIONS

These findings suggest that brain growth in MP and LP infants differs from full-term infants. Whether these differences have clinical implications remains to be investigated.

Mild brain lesions do not affect brain volumes in moderate-late preterm infants

PURPOSE

It is unknown whether frequently occurring mild brain lesions affect brain volumes in moderate (MP²; 32⁺⁰-33⁺⁶ weeks' gestation) and late (LP³; 34⁺⁰-35⁺⁶ weeks' gestation) preterm infants. Therefore, we aimed to investigate the effect of mild brain lesions on brain volumes in moderate-late preterm (MLPT⁴) infants and to compare brain volumes between MP and LP infants.

METHODS

From August 2017 to November 2019, eligible MLPT infants born at Isala Women and Children's Hospital were enrolled in a prospective cohort study (Brain Imaging in Moderate-late Preterm infants 'BIMP-study'). MRI was performed around term equivalent age (TEA⁵). MRI scans were assessed for (mild) brain lesions. T2-weighted images were used for automatic segmentation of eight brain structures. Linear regression analysis was performed to compare absolute and relative brain volumes between infants with and without mild brain lesions and between MP and LP infants.

RESULTS

36 MP and 68 LP infants were included. In infants with mild brain lesions, intracranial volume (B = 27.4 cm³, p = 0.02), cerebrospinal fluid (B = 8.78 cm³, p = 0.01) and cerebellar volumes (B = 1.70 cm³, p = 0.03) were significantly larger compared to infants without mild brain lesions. After correction for weight and postmenstrual age at MRI, these volumes were no longer significantly different. LP infants had larger brain volumes than MP infants, but differences were not significant. Relative brain volumes showed no significant differences in both analyses.

CONCLUSION

Neither having mild brain lesions, nor being born moderate prematurely affected brain volumes at TEA in MLPT infants.

The Developing Human Connectome Project: typical and disrupted perinatal functional connectivity

The Developing Human Connectome Project is an Open Science project that provides the first large sample of neonatal functional MRI data with high temporal and spatial resolution. These data enable mapping of intrinsic functional connectivity between spatially distributed brain regions under normal and adverse perinatal circumstances, offering a framework to study the ontogeny of large-scale brain organization in humans. Here, we characterize in unprecedented detail the maturation and integrity of resting state networks (RSNs) at term-equivalent age in 337 infants (including 65 born preterm). First, we applied group independent component analysis to define 11 RSNs in term-born infants scanned at 43.5–44.5 weeks postmenstrual age (PMA). Adult-like topography was observed in RSNs encompassing primary sensorimotor, visual and auditory cortices. Among six higher-order, association RSNs, analogues of the adult networks for language and ocular control were identified, but a complete default mode network precursor was not. Next, we regressed the subject-level datasets from an independent cohort of infants scanned at 37–43.5 weeks PMA against the group-level RSNs to test for the effects of age, sex and preterm birth. Brain mapping in term-born infants revealed areas of positive association with age across four of six association RSNs, indicating active maturation in functional connectivity from 37 to 43.5 weeks PMA. Female infants showed increased connectivity in inferotemporal regions of the visual association network. Preterm birth was associated with striking impairments of functional connectivity across all RSNs in a dose-dependent manner; conversely, connectivity of the superior parietal lobules within the lateral motor network was abnormally increased in preterm infants, suggesting a possible mechanism for specific difficulties such as developmental coordination disorder, which occur frequently in preterm children. Overall, we found a robust, modular, symmetrical functional brain organization at normal term age. A complete set of adult-equivalent primary RSNs is already instated, alongside emerging connectivity in immature association RSNs, consistent with a primary-to-higher order ontogenetic sequence of brain development. The early developmental disruption imposed by preterm birth is associated with extensive alterations in functional connectivity.

Uncomplicated intraventricular hemorrhage is not associated with lower estimated cerebral volume at term age

BACKGROUND AND AIMS

Cerebral lesions detected using cerebral ultrasound (cUS) in very preterm infants are associated with increased risk for neurodevelopmental problems. However, uncomplicated intraventricular hemorrhage (IVH) has no consistent association with poor outcome. In this study we evaluate the effect of uncomplicated IVH on estimated brain volume at term-equivalent age (TEA), using a model based on measurements made from cUS.

METHODS

We studied 2 groups of preterm infants (<32 weeks' gestational age (GA)) up to and at TEA: (1) infants with uncomplicated grades 2 or 3 IVH, (2) infants with consistently normal scans. Estimated cerebral volumes at TEA were calculated using a previously described model based on linear measurements and compared between the 2 groups using independent groups t-test or the Mann-Whitney test; p-value <0.05 was considered significant.

RESULTS

We assessed 95 preterm infants (18 with uncomplicated IVH and 71 with normal scans). GA and birth weight were lower in infants with uncomplicated IVH (26.8/28.7weeks, p < 0.001, 944/1082g, p < 0.05, respectively); occipital-frontal circumference at TEA was smaller in the IVH infants (34.2 vs 35.3 cm, p < 0.05). However, no significant differences at TEA were found for estimated cranial volume (383/411cc³), estimated cerebral volume (337/341cc³), Levene ventricular index (13.5/12.2 mm) or thalamo-occipital distance (21.5/20.3 mm). Statistical adjustment for the lower GA in the IVH group confirmed the absence of a significant difference in the findings.

CONCLUSIONS

In summary, we found that estimated cerebral volume at TEA, based on measurements made at the bedside using cranial US, is not different between very preterm infants with consistently normal scans and those with uncomplicated grades 2 and 3 IVH.

Automatic Segmentation of Diffuse White Matter Abnormality on T2-weighted Brain MR Images Using Deep Learning in Very Preterm Infants

About 50%-80% of very preterm infants (VPIs) (≤ 32 weeks gestational age) exhibit diffuse white matter abnormality (DWMA) on their MR images at term-equivalent age. It remains unknown if DWMA is associated with developmental impairments, and further study is warranted. To aid in the assessment of DWMA, a deep learning model for DWMA quantification on T2-weighted MR images was developed. This secondary analysis of prospective data was performed with an internal cohort of 98 VPIs (data collected from December 2014 to April 2016) and an external cohort of 28 VPIs (data collected from January 2012 to August 2014) who had already undergone MRI at term-equivalent age. Ground truth DWMA regions were manually annotated by two human experts with the guidance of a prior published semiautomated algorithm. In a twofold cross-validation experiment using the internal cohort of 98 infants, the three-dimensional (3D) ResU-Net model accurately segmented DWMA with a Dice similarity coefficient of 0.907 ± 0.041 (standard deviation) and balanced accuracy of 96.0% ± 2.1, outperforming multiple peer deep learning models. The 3D ResU-Net model that was trained with the whole internal cohort (n = 98) was further tested on an independent external test cohort (n = 28) and achieved a Dice similarity coefficient of 0.877 ± 0.059 and balanced accuracy of 92.3% ± 3.9. The externally validated 3D ResU-Net deep learning model for accurately segmenting DWMA may facilitate the clinical diagnosis of DWMA in VPIs. Supplemental material is available for this article. Keywords: Brain/Brain Stem, Convolutional Neural Network (CNN), MR-Imaging, Pediatrics, Segmentation, Supervised learning © RSNA, 2021.

Brain Volumes of very Low Birth Weight Infants Measured by Two-dimensional Cranial Ultrasonography: A Prospective Cohort Study

BACKGROUND

Cranial ultrasonography is the main neuroimaging technique for very low birth weight infants. Low brain volume is associated with poor neurologic outcome. This study aimed to calculate brain volumes of preterm infants with two-dimensional measurements of cranial ultrasonography.

METHODS

Intracranial height, anteroposterior diameter, bi-parietal diamater, ventricular height, thalamo-occipital distance and ventricular index were measured with routine cranial ultrasonographic scanning. Brain considered a spheric, ellipsoid model and estimated brain volume (EBV) was calculated by subtracting two lateral ventricular volumes from the total brain volume.

RESULTS

One hundred and twenty-one preterm infants under a birth weight of 1500 g and 32 weeks of gestational age were included in this study. The mean gestational age of study population was 27.7 weeks, and mean birthweight was 1057 grams. Twenty-two of 121 infants had dilated ventricle, in this group, EBV was lower than normal group (202 ± 58 cm3 vs 250 ± 53 cm3, respectively, p<0.01). Advanced resuscitation, bronchopulmonary dysplasia and late-onset sepsis were found to be independent risk factors for low brain volume in our data.

CONCLUSION

Estimated brain volume can be calculated by two-dimensional measurements with cranial ultrasonography.

Preterm Brain Injury, Antenatal Triggers, and Therapeutics: Timing Is Key

With a worldwide incidence of 15 million cases, preterm birth is a major contributor to neonatal mortality and morbidity, and concomitant social and economic burden Preterm infants are predisposed to life-long neurological disorders due to the immaturity of the brain. The risks are inversely proportional to maturity at birth. In the majority of extremely preterm infants (<28 weeks' gestation), perinatal brain injury is associated with exposure to multiple inflammatory perinatal triggers that include antenatal infection (i.e., chorioamnionitis), hypoxia-ischemia, and various postnatal injurious triggers (i.e., oxidative stress, sepsis, mechanical ventilation, hemodynamic instability). These perinatal insults cause a self-perpetuating cascade of peripheral and cerebral inflammation that plays a critical role in the etiology of diffuse white and grey matter injuries that underlies a spectrum of connectivity deficits in survivors from extremely preterm birth. This review focuses on chorioamnionitis and hypoxia-ischemia, which are two important antenatal risk factors for preterm brain injury, and highlights the latest insights on its pathophysiology, potential treatment, and future perspectives to narrow the translational gap between preclinical research and clinical applications.

Brain tissue volumes at term-equivalent age are associated with early motor behavior in very preterm infants

Preterm birth is associated with a wide range of adverse developmental outcomes, including sensory, motor, cognitive and language impairments, and behavioral or attention problems. Subtle motor deficits that might emerge in premature infants with no evident or with mild brain injury encompass qualitative and quantitative aspects of motor behavior. This prospective cohort study provided an evaluation of the relationship between brain tissue volumes revealed by magnetic resonance imaging (MRI) at term-equivalent age and motor behavior in infancy in very preterm infants (total number = 40; mean gestational age = 28 weeks + 4 days; mean birth weight = 1190 g) without evident or with mild brain injury. Infants were recruited at birth and assessed at 12 months corrected age using the tool for qualitative and quantitative assessment of motor behavior, infant motor profile. The brain tissue was segmented first using advanced segmentation techniques and the volumes were measured by summing the volumes of all voxels belonging to a particular tissue class. The associations between volumetric brain MRI measures with motor behavior were explored using linear regression analyses. Results showed that larger total brain volumes were associated with higher motor score. Similar relationships were documented for parietal lobe, deep gray matter, and cerebellum volumes. Volumetric quantitative data of brain structures may serve as biomarkers for subtle motor deficits described in very preterm born infants without or with mild brain lesions apparent on MRI.

Brain 3D-echographic early predictors of neuro-behavioral disorders in infants: a prospective observational study

Background: Prematurity, low birth weight (LBW), very low birth weight (VLBW), and intrauterine growth restriction (IUGR) are risk factors of long-term poor neuro-development outcomes and associate with reduction of regional brain volumes.Objective: To evaluate the possible role of 3D ultrasound sonography (3DUS) regional brain volumes, measured at 30-40 days of postnatal period, as early predictors of long-term risk of neuro-behavioral disorders.Methods: A highly selected population, which included: full-term, preterm, IUGR, and preterm-IUGR born individuals, was followed longitudinally from 30 to 40 days of postnatal period to the second year of life. The population was mostly composed of bichorionic twins to ensure a, theoretically, major intracategory homogeneity. Preterm and IUGR subjects were characterized by a gestational age (GA) and birth weight (BW)>32 weeks and >1500 g, respectively, whereas the full-term neonates were of 37 weeks GA. At enrollment, the assessment of the volumetric measurements was performed using the 3DUS. The evaluation of neuro-development was performed at 2 years using the Griffiths Mental Development Scales.Results: The 3DUS measurements of whole brain, thalamus, frontal cortex, and cerebellum volumes, assessed at 30-40 days of postnatal period, were significantly reduced in infants characterized by negative outcome. In addition, the respective areas of the ROC curves, made by comparing values of normal and abnormal neuro-development groups, were indicative of a strong diagnostic accuracy.Conclusion: Data found suggest that the 3DUS regional brain volumes may assume a significant role as early indicators of neonates at major risk of neuro-behavioral disorders in later life. Further and larger studies in this direction are needed to validate this significant perspective.

Tracking regional brain growth up to age 13 in children born term and very preterm

Serial regional brain growth from the newborn period to adolescence has not been described. Here, we measured regional brain growth in 216 very preterm (VP) and 45 full-term (FT) children. Brain MRI was performed at term-equivalent age, 7 and 13 years in 82 regions. Brain volumes increased between term-equivalent and 7 years, with faster growth in the FT than VP group. Perinatal brain abnormality was associated with less increase in brain volume between term-equivalent and 7 years in the VP group. Between 7 and 13 years, volumes were relatively stable, with some subcortical and cortical regions increasing while others reduced. Notably, VP infants continued to lag, with overall brain size generally less than that of FT peers at 13 years. Parieto–frontal growth, mainly between 7 and 13 years in FT children, was associated with higher intelligence at 13 years. This study improves understanding of typical and atypical regional brain growth.

In this longitudinal study, the authors tracked the course of brain development from birth to adolescence (age 13 years) and examined the effects of very preterm birth. Very preterm children showed slower brain growth from age 0 (term equivalent) to age 7.

Neuroprotection Strategies in Preterm Encephalopathy

Advances in neonatology have led to unprecedented improvements in neonatal survival such that those born as early as 22 weeks of gestation now have some chance of survival, and over 70% of those born at 24 weeks of gestation survive. Up to 50% of infants born extremely preterm develop poor outcomes involving long-term neurodevelopmental impairments affecting cognition and learning, or motor problems such as cerebral palsy. Poor outcomes arise because the preterm brain is vulnerable both to direct injury (by events such as intracerebral hemorrhage, infection, and/or hypoxia), or indirect injury due to disruption of normal development. This neonatal brain injury and/or dysmaturation is called "encephalopathy of prematurity". Current and future strategies to improve outcomes in this population include prevention of preterm birth, and pre-, peri-, and postnatal approaches to protect the developing brain. This review will describe mechanisms of preterm brain injury, and current and upcoming therapies in the antepartum and postnatal period to improve preterm encephalopathy.

Low Cerebral Oxygenation in Preterm Infants Is Associated with Adverse Neurodevelopmental Outcome

OBJECTIVE

To assess whether high and low levels of cerebral oxygenation (regional cerebral oxygenation [rScO₂]) in infants born at <32 weeks of gestation were associated with adverse long-term outcome.

STUDY DESIGN

Observational cohort study including preterm infants born at <32 weeks of gestation at the Wilhelmina Children's Hospital, The Netherlands, between April 2006 and April 2013. The rScO₂ was continuously monitored for 72 hours after birth using near-infrared spectroscopy. Outcome was assessed at 15 and 24 months of corrected age by certified investigators. An unfavorable composite outcome was defined as an outcome score below -1 SD or death. Various rScO₂ thresholds were explored.

RESULTS

In total, 734 infants were eligible for analysis, 60 of whom died. Associations with an unfavorable cognitive outcome in multivariable analysis were comparable for time spent with a rScO₂ below 55% and -1.5 SD (according to published reference values), with an OR of 1.4 (CI 1.1-1.7) for 20% of time below either threshold. Results at 15 months were comparable with results at 24 months. Results were not statistically significant for thresholds defining high values of rScO₂. The composite motor outcome was not significantly related to either low or high values or rScO₂.

CONCLUSIONS

Low, but not high, rScO₂ was associated with an unfavorable cognitive outcome. This suggests the use of a threshold of rScO₂ <55% for future clinical studies when using adult near-infrared sensors (rScO₂ <65% for neonatal sensors, approximately).

Effects of an Early Postnatal Music Intervention on Cognitive and Emotional Development in Preterm Children at 12 and 24 Months: Preliminary Findings

Preterm birth is associated with a higher prevalence of neurodevelopmental deficits. Indeed, preterm children are at increased risk for cognitive, behavioral, and socio-emotional difficulties. There is currently an increasing interest in introducing music intervention in neonatal intensive care unit (NICU) care. Several studies have shown short-term beneficial effects. A recent study has shown that listening to a familiar music (heard daily during the NICU stay) enhanced preterm infants’ functional connectivity between auditory cortices and subcortical brain regions at term-equivalent age. However, the long-term effects of music listening in the NICUs have never been explored. The aim of this study was to evaluate at 12 and 24 months the effects of music listening in the NICU on cognitive and emotional development in preterm children by comparing them to a preterm control group with no previous music exposure and to a full-term group. Participants were 44 children (17 full-term and 27 preterm). Preterm children were randomized to either music intervention or control condition (without music). The preterm-music group regularly listened to music from 33 weeks postconceptional age until hospital discharge or term-equivalent age. At 12 months, children were evaluated on the Bayley Scales of Infant and Toddler Development, Third Edition, then with 4 episodes of the Laboratory Temperament Assessment Battery (assessing expressions of joy, anger, and fear, and sustained attention). At 24 months, the children were evaluated with the same tests, and with 3 additional episodes of the Effortful Control Battery (assessing inhibition). Results showed that the scores of preterm children, music and control, differed from those of full-term children for fear reactivity at 12 months of age and for anger reactivity at 24 months of age. Interestingly, these significant differences were less important between the preterm-music and the full-term groups than between the preterm-control and the full-term groups. The present study provides preliminary, but promising, scientific findings on the beneficial long-term effects of music listening in the NICU on neurodevelopmental outcomes in preterm children, and more specifically on emotion mechanisms at 12 and 24 months of age. Our findings bring new insights for supporting early music intervention in the NICU.

Bronchopulmonary Dysplasia Is Associated with Altered Brain Volumes and White Matter Microstructure in Preterm Infants

BACKGROUND

Bronchopulmonary dysplasia (BPD), an inflammatory disease involving disrupted lung development, is associated with neurodevelopmental outcome in preterm infants.

OBJECTIVE

This study examined the brain volume and white matter (WM) microstructure in preterm infants at term-equivalent age and explored the effects of BPD on brain development.

METHOD

We studied 56 preterm infants (33 with BPD and 23 without BPD) with no evidence of focal abnormalities on conventional magnetic resonance imaging (MRI) at term-equivalent age. Regional brain volumes and diffusion tensor images were examined using advanced segmentation techniques to acquire quantitative volume measurements, and the JHU neonatal template was used for the atlas-based analysis. We compared these infants with 22 healthy term infants of a similar postmenstrual age.

RESULTS

The preterm infants with BPD had smaller cerebral WM (p = 0.005) volumes than the preterm infants without BPD, independent of sex, gestational age, age at MRI scan, and total intracranial volume. Independent of sex, gestational age, and age at MRI scan, the preterm infants with BPD exhibited marked reductions in fractional anisotropy in the corpus callosum (p = 0.006), corticospinal tract (p = 0.003), and superior cerebellar peduncle (p = 0.002) compared with the infants with no BPD, with a significance level of p ≤ 0.008 as a Bonferroni correction for multiple comparisons.

CONCLUSION

Our study highlights the potential impairing influence of BPD on WM and cerebellar development in preterm infants compared with those without BPD at term-equivalent age, suggesting its clinical significance for neurodevelopment in BPD infants.

Characterisation of brain volume and microstructure at term-equivalent age in infants born across the gestational age spectrum

Background

Risk of morbidity differs between very preterm (VP; <32 weeks' gestational age (GA)), moderate preterm (MP; 32–33 weeks' GA), late preterm (LP; 34–36 weeks' GA), and full-term (FT; ≥37 weeks' GA) infants. However, brain structure at term-equivalent age (TEA; 38–44 weeks) remains to be characterised in all clinically important GA groups. We aimed to compare global and regional brain volumes, and regional white matter microstructure, between VP, MP, LP and FT groups at TEA, in order to establish the magnitude and anatomical locations of between-group differences.

Methods

Structural images from 328 infants (91 VP, 63 MP, 104 LP and 70 FT) were segmented into white matter, cortical grey matter, cerebrospinal fluid (CSF), subcortical grey matter, brainstem and cerebellum. Global tissue volumes were analysed, and additionally, cortical grey matter and white matter volumes were analysed at the regional level using voxel-based morphometry. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) images from 361 infants (92 VP, 69 MP, 120 LP and 80 FT) were analysed using Tract-Based Spatial Statistics. Statistical analyses involved examining the overall effect of GA group on global volumes (using linear regressions) and regional volumes and microstructure (using non-parametric permutation testing), as well performing post-hoc comparisons between the GA sub-groups.

Results

On global analysis, cerebrospinal fluid (CSF) volume was larger in all preterm sub-groups compared with the FT group. On regional analysis, volume was smaller in parts of the temporal cortical grey matter, and parts of the temporal white matter and corpus callosum, in all preterm sub-groups compared with the FT group. FA was lower, and RD and MD were higher in voxels located in much of the white matter in all preterm sub-groups compared with the FT group. The anatomical locations of group differences were similar for each preterm vs. FT comparison, but the magnitude and spatial extent of group differences was largest for the VP, followed by the MP, and then the LP comparison. Comparing within the preterm groups, the VP sub-group had smaller frontal and temporal grey and white matter volume, and lower FA and higher MD and RD within voxels in the approximate location of the corpus callosum compared with the MP sub-group. There were few volume and microstructural differences between the MP and LP sub-groups.

Conclusion

All preterm sub-groups had atypical brain volume and microstructure at TEA when compared with a FT group, particularly for the CSF, temporal grey and white matter, and corpus callosum. In general, the groups followed a gradient, where the differences were most pronounced for the VP group, less pronounced for the MP group, and least pronounced for the LP group. The VP sub-group was particularly vulnerable compared with the MP and LP sub-groups.

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The very, moderate, and late preterm brain differed from full-term at term.

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Differences were seen for CSF, temporal grey and white, and corpus callosum volumes.

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Differences were also found in the microstructure of many major white matter tracts.

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Differences were most pronounced for very and least for late preterm infants.

Brain Volumes and Developmental Outcome in Childhood Following Fetal Growth Restriction Leading to Very Preterm Birth

Background: Children born very preterm (PT) after fetal growth restriction (FGR) exhibit cognitive impairment at early school age. The relationship between neurodevelopmental impairment and attained regional brain volumes is unknown. Methods: We studied 23 preterm children with FGR (PT-FGR), 24 matched preterm children AGA (PT-AGA), and 27 matched term AGA children (T-AGA) by measuring brain volumes with magnetic resonance imaging at early school age. Cognitive and motor functions were assessed by the Wechsler Intelligence Scales for Children and the ABC-Movement score. Results: The mean (SD) full-scale IQ was 80 (17) in the PT-FGR group and 103 (12) in the PT-AGA group (p < 0.001). The PT-FGR group had lower mean total, gray matter, white matter, thalamic, cerebellar white matter, and hippocampal volumes as compared to the T-AGA group (p = 0.01, 0.04, 0.003, 0.002, 0.001, and 0.009, respectively). Brain volumes did not differ significantly between the PT groups. Reduction of hippocampal volume correlated with degree of growth restriction at birth (r = 0.46, p = 0.05). Neither the full-scale IQ nor the ABC movement score <5th percentile were related to brain volumes. Conclusion: Brain volumes as determined by MRI at early school age were primarily associated with degree of prematurity at birth and less with FGR. Regional brain volumes did not discriminate cognitive and motor function beyond that predicted by gestational age at birth.

Assessment of neonatal brain volume and growth at different postmenstrual ages by conventional MRI

Data regarding neonatal brain volumes represent a basis for monitoring early brain development, and large sample of neonatal brain volume data has not been well described. This study was focused on neonatal brain volumes at different postmenstrual ages (PMA) and postnatal age (PNA).A cohort of 415 neonates with PMA 30 to 43 weeks were recruited for the determination of brain volumes. Intracranial cavity (ICC), total brain tissue (TBT), and cerebrospinal fluid (CSF) were evaluated on the basis of T1-weighted sagittal plane magnetic resonance images. Brain magnetic resonance imaging was assessed using maturation scoring system and multiple linear regression analysis was conducted to forecast the effect factors of brain volumes.TBT volume reached a peak growth at 39 to 40 weeks, ICC volume presented peak growth later at around 43 to 44 weeks, and CSF had a cliff fallen at 37 to 38 weeks PMA at scan. The maturation score increased along with PMA, and the TBT and CSF volumes were significantly different between higher and lower gestational age (GA) groups. The ICC and TBT volumes in higher GA group were larger than lower GA group. Most infants in higher GA group had higher TMS than those in lower GA group. Gender, PMA, PNA, and birth weight were predictors of TBT and ICC volumes.Our results showed that premature volumes of ICC and TBT enlarged with the increasing PMA, while volumes of CSF decreased at 37 weeks. Premature earlier to leave the uterus can lead to brain mature retard although they had the same GA compared with those later birth neonates.