Magnetic resonance imaging of preterm brain injury

Incidence of brain injuries in a large cohort of very preterm and extremely preterm infants at term-equivalent age: results of a single tertiary neonatal care center over 10 years

OBJECTIVES

Cerebral magnetic resonance imaging (cMRI) at term-equivalent age (TEA) can detect brain injury (BI) associated with adverse neurological outcomes in preterm infants. This study aimed to assess BI incidences in a large, consecutive cohort of preterm infants born < 32 weeks of gestation, the comparison between very (VPT, ≥ 28 + 0 to < 32 + 0 weeks of gestation) and extremely preterm infants (EPT, < 28 + 0 weeks of gestation) and across weeks of gestation.

METHODS

We retrospectively analyzed cMRIs at TEA of VPT and EPT infants born at a large tertiary center (2009-2018). We recorded and compared the incidences of BI, severe BI, intraventricular hemorrhage (IVH), periventricular hemorrhagic infarction (PVHI), cerebellar hemorrhage (CBH), cystic periventricular leukomalacia (cPVL), and punctate white matter lesions (PWML) between VPTs, EPTs, and across weeks of gestation.

RESULTS

We included 507 preterm infants (VPT, 335/507 (66.1%); EPT, 172/507 (33.9%); mean gestational age (GA), 28 + 2 weeks (SD 2 + 2 weeks); male, 52.1%). BIs were found in 48.3% of the preterm infants (severe BI, 12.0%) and increased with decreasing GA. IVH, PVHI, CBH, cPVL, and PWML were seen in 16.8%, 0.8%, 10.5%, 3.4%, and 18.1%, respectively. EPT vs. VPT infants suffered more frequently from BI (59.3% vs. 42.7%, p < 0.001), severe BI (18.6% vs. 8.7%, p = 0.001), IVH (31.9% vs. 9.0%, p < 0.001), and CBH (18.0% vs. 6.6%, p < 0.001).

CONCLUSION

Brain injuries are common cMRI findings among preterm infants with a higher incidence of EPT compared to VPT infants. These results may serve as reference values for clinical management and research.

CLINICAL RELEVANCE STATEMENT

Our results with regard to gestational age might provide valuable clinical insights, serving as a key reference for parental advice, structured follow-up planning, and enhancing research and management within the Neonatal Intensive Care Unit.

KEY POINTS

• Brain injury is a common cMRI finding in preterm infants seen in 48.3% individuals. • Extremely preterm compared to very preterm infants have higher brain injury incidences driven by brain injuries such as intraventricular and cerebellar hemorrhage. • Reference incidence values are crucial for parental advice and structured follow-up planning.

Divergent neurodevelopmental profiles of very-low-birth-weight infants

BACKGROUND

Advanced perinatal medicine has decreased the mortality rate of preterm infants. Long-term neurodevelopmental outcomes of very-low-birth-weight infants (VLBWIs) remain to be investigated.

METHODS

Participants were 124 VLBWIs who had in-hospital birth from 2007 to 2015. Perinatal information, developmental or intelligence quotient (DQ/IQ), and neurological comorbidities at ages 3 and 6 years were analyzed.

RESULTS

Fifty-eight (47%) VLBWIs received neurodevelopmental assessments at ages 3 and 6 years. Among them, 15 (26%) showed DQ/IQ <75 at age 6 years. From age 3 to 6 years, 21 (36%) patients showed a decrease (≤-10), while 5 (9%) showed an increase (≥+10) in DQ/IQ scores. Eight (17%) with autism spectrum disorder or attention-deficit hyperactivity disorder (ASD/ADHD) showed split courses of DQ/IQ, including two with ≤-10 and one with +31 to their scores. On the other hand, all 7 VLBWIs with cerebral palsy showed DQ ≤35 at these ages. Magnetic resonance imaging detected severe brain lesions in 7 (47%) of those with DQ <75 and 1 (18%) with ASD/ADHD.

CONCLUSIONS

VLBWIs show a broad spectrum of neurodevelopmental outcomes after 6 years. These divergent profiles also indicate that different risks contribute to the development of ASD/ADHD from those of cerebral palsy and epilepsy in VLBWIs.

IMPACT

Very-low-birth-weight infants (VLBWIs) show divergent neurodevelopmental outcomes from age 3 to 6 years. A deep longitudinal study depicts the dynamic change in neurodevelopmental profiles of VLBWIs from age 3 to 6 years. Perinatal brain injury is associated with developmental delay, cerebral palsy and epilepsy, but not with ASD or ADHD at age 6 years.

Early brain morphometrics from neonatal MRI predict motor and cognitive outcomes at 2-years corrected age in very preterm infants

Infants born very preterm face a range of neurodevelopmental challenges in cognitive, language, behavioural and/or motor domains. Early accurate identification of those at risk of adverse neurodevelopmental outcomes, through clinical assessment and Magnetic Resonance Imaging (MRI), enables prognostication of outcomes and the initiation of targeted early interventions. This study utilises a prospective cohort of 181 infants born <31 weeks gestation, who had 3T MRIs acquired at 29-35 weeks postmenstrual age and a comprehensive neurodevelopmental evaluation at 2 years corrected age (CA). Cognitive, language and motor outcomes were assessed using the Bayley Scales of Infant and Toddler Development - Third Edition and functional motor outcomes using the Neuro-sensory Motor Developmental Assessment. By leveraging advanced structural MRI pre-processing steps to standardise the data, and the state-of-the-art developing Human Connectome Pipeline, early MRI biomarkers of neurodevelopmental outcomes were identified. Using Least Absolute Shrinkage and Selection Operator (LASSO) regression, significant associations between brain structure on early MRIs with 2-year outcomes were obtained (r = 0.51 and 0.48 for motor and cognitive outcomes respectively) on an independent 25% of the data. Additionally, important brain biomarkers from early MRIs were identified, including cortical grey matter volumes, as well as cortical thickness and sulcal depth across the entire cortex. Adverse outcome on the Bayley-III motor and cognitive composite scores were accurately predicted, with an Area Under the Curve of 0.86 for both scores. These associations between 2-year outcomes and patient prognosis and early neonatal MRI measures demonstrate the utility of imaging prior to term equivalent age for providing earlier commencement of targeted interventions for infants born preterm.

Detection of Global Brain Injury Using Point-of-Care Neonatal MRI Scanner

BACKGROUND

 Conventional magnetic resonance imaging (MRI) neuroimaging of infants is complicated by the need to transport infants outside the neonatal intensive care unit (NICU), often to distant areas of the hospital.

PRIMARY OBJECTIVE

 The main aim of this study was to evaluate and compare scoring of images from a novel 1T MRI, which enables neuroimaging within the NICU, with those from a conventional MRI.

SECONDARY OBJECTIVE

 The second aim of this study was to document improved expediency, and thereby greater patient safety, as reflected by decreased transport time.

MATERIALS AND METHODS

 Thirty premature infants (mean gestational age: 28.8 ± 2.1 weeks) were scanned consecutively on the novel 1T and 1.5T conventional scanners at term-equivalent age. Orthogonal T1- and T2-weighted images were acquired and reviewed. A global brain abnormality score (Kidokoro) was assigned independently to all images by two radiologists. Interrater agreement was evaluated using the kappa statistic and interscanner agreement was evaluated by Bland-Altman analysis. Transport time to and from both scanners was monitored and compared.

RESULTS

 Weighted kappas were 0.77 (standard error of measurement [SEM] 0.08; confidence interval [CI]: 0.62-0.92) and 0.86 (SEM: 0.07; CI: 0.73-1), for the 1T and 1.5T scanners, respectively, reflecting substantial interrater agreement. Bland-Altman analysis showed excellent agreement between the two scanners.Transport time was 8 ± 6 minutes for the 1T MRI versus 46 ± 21 minutes for the conventional MRI (p < 0.00001). No adverse events were recorded during transport. Standard transport times will vary from institution to institution.

CONCLUSIONS

 Kidokoro scores are similar when comparing images obtained from a 1T MRI with those of a conventional 1.5T MRI, reflecting comparable image quality. Transport time was significantly decreased using the 1T neonatal MRI.

Speech sound production, speech intelligibility, and oral-motor outcomes of preterm children: Are they different from full term children?

We studied the speech sound abilities of preterm (PT) children. Thirty-one PT and twenty-nine full term (FT) children were recruited. Speech abilities were assessed in single word, story retelling, oral-motor, and intelligibility. PT group had poorer outcomes (Mean = 25.77, SD = 17.19) than FT ones (Mean = 5.9, SD = 4.97) for single word (p < 0.001). They obtained poorer results (Mean = 9.65, SD = 7.85) than FT peers (Mean = 2.95, SD = 3.34) in story retelling (p = 0.002) and intelligibility (Man-Whitney U = 89.50, p = 0.02). They obtained lower values for diadochokesis/patuku/(p < 0.001), isolated (p = 0.001), and sequenced movements (p = 0.02) but not for diadochokesis/patukejk/(p = 0.12). Significant values of correlation were found among single word scores with birth weight (r = -.54, p < .001) and gestational age (r = -0.67, p < .001) and story retelling scores with birth weight (r = -0.40, p = .013) and gestational age (r = -0.64, p < .001). The associations of single word score and maternal (r = -0.02, p = .85) and paternal education (r = -0.10, p = .41) were not significant. No significant relationships were obtained between story retelling score and maternal (r = 0.16, p = .34) and paternal education (r = 0.09, p = .59). The significant values were obtained for associations of intelligibility with isolated (r = 0.54, p = .001), sequenced movements (r = 0.59, p < .001), and diadochokesis/patukejk/(r = 0.39, p = .016) but not significant for intelligibility and diadochokesis/patuku/(r = 0.25, p = .13). Findings implied that speech abilities are weaker in PT children.

Orchestrating human neocortex development across the scales; from micro to macro

How our brains have developed to perform the many complex functions that make us human has long remained a question of great interest. Over the last few decades, many scientists from a wide range of fields have tried to answer this question by aiming to uncover the mechanisms that regulate the development of the human neocortex. They have approached this on different scales, focusing microscopically on individual cells all the way up to macroscopically imaging entire brains within living patients. In this review we will summarise these key findings and how they fit together.

General movements assessment and Alberta Infant Motor Scale in neurodevelopmental outcome of preterm infants

AIM

We aimed to compare the General Movement Assessment (GMA) and the Alberta Infant Motor Scale (AIMS) in preterm infants for the prediction of cerebral palsy (CP) and neurodevelopmental delay (NDD). Additionally, we aimed to evaluate the diagnostic compatibility of the General Movement Optimality Score (GMOS), the Motor Optimality Score (MOS), and AIMS for detecting CP and NDD.

METHOD

Seventy-five preterm infants with gestational age (GA) 24-37 weeks were enrolled. Group 1 was composed of infants with 24-28 GA (n = 22); groups 2 and 3 consisted of infants with 29-32 GA weeks (n = 23) and 33-37 GA (n = 30) weeks, respectively. The infants were assessed during the writhing period, the fidgety period, and at 6-12 months of corrected age with GMOS, MOS, and AIMS, respectively.

RESULTS

In the writhing period, a cramped-synchronized pattern was observed in 17 (22%) infants, whereas a poor repertoire pattern was observed in 34 (45%) infants. In the fidgety period of the 63 infants, 29 (46%) presented with fidgety movements absent. The MOS and AIMS scores of the infants in group 1 were significantly lower than the other groups, which were statistically significant (p = 0.004, p˂0.001). High and positive compatibility (Kappa coefficient: 0.709; p = 0.001) was found between AIMS and GMOS scores and between AIMS and MOS scores (Kappa coefficient: 0.804; p < 0.001). In all groups, a statistically significant association was found between total GMOS scores (p = 0.003) and the presence of fidgety movements (p = 0.003). GMOS, MOS, and AIMS were found to be associated with CP and NDD (p < 0.001).

CONCLUSION

GMA is an important tool for the prediction of CP and NDD. The combined use of GMOS, MOS, and AIMS may guide the clinical practice for the valid and reliable diagnosis of CP and NDD.

MRI based radiomics enhances prediction of neurodevelopmental outcome in very preterm neonates

To predict adverse neurodevelopmental outcome of very preterm neonates. A total of 166 preterm neonates born between 24–32 weeks’ gestation underwent brain MRI early in life. Radiomics features were extracted from T1- and T2- weighted images. Motor, cognitive, and language outcomes were assessed at a corrected age of 18 and 33 months and 4.5 years. Elastic Net was implemented to select the clinical and radiomic features that best predicted outcome. The area under the receiver operating characteristic (AUROC) curve was used to determine the predictive ability of each feature set. Clinical variables predicted cognitive outcome at 18 months with AUROC 0.76 and motor outcome at 4.5 years with AUROC 0.78. T1-radiomics features showed better prediction than T2-radiomics on the total motor outcome at 18 months and gross motor outcome at 33 months (AUROC: 0.81 vs 0.66 and 0.77 vs 0.7). T2-radiomics features were superior in two 4.5-year motor outcomes (AUROC: 0.78 vs 0.64 and 0.8 vs 0.57). Combining clinical parameters and radiomics features improved model performance in motor outcome at 4.5 years (AUROC: 0.84 vs 0.8). Radiomic features outperformed clinical variables for the prediction of adverse motor outcomes. Adding clinical variables to the radiomics model enhanced predictive performance.

Altered Cerebral Curvature in Preterm Infants Is Associated with the Common Genetic Variation Related to Autism Spectrum Disorder and Lipid Metabolism

Preterm births are often associated with neurodevelopmental impairment. In the critical developmental period of the fetal brain, preterm birth disrupts cortical maturation. Notably, preterm birth leads to alterations in the fronto-striatal and temporal lobes and the limbic region. Recent advances in MRI acquisition and analysis methods have revealed an integrated approach to the genetic influence on brain structure. Based on imaging studies, we hypothesized that the altered cortical structure observed after preterm birth is associated with common genetic variations. We found that the presence of the minor allele at rs1042778 in OXTR was associated with reduced curvature in the right medial orbitofrontal gyrus (p < 0.001). The presence of the minor allele at rs174576 in FADS2 (p < 0.001) or rs740603 in COMT (p < 0.001) was related to reduced curvature in the left posterior cingulate gyrus. This study provides biological insight into altered cortical curvature at term-equivalent age, suggesting that the common genetic variations related to autism spectrum disorder (ASD) and lipid metabolism may mediate vulnerability to early cortical dysmaturation in preterm infants.

Characterization of germinal matrix hemorrhage in extremely premature infants: recognition of posterior location and diagnostic pitfalls

BACKGROUND

Traditionally, descriptions of germinal matrix hemorrhage (GMH), derived from observations in preterm and very preterm infants, indicate its location at the caudothalamic grooves. However, before the germinal matrix begins to recede at approximately 28 weeks' gestational age (GA), it extends along the floor of the lateral ventricles far posterior to the caudothalamic grooves. Germinal matrix-intraventricular hemorrhage (GMH-IVH) can occur along any site from which the germinal matrix has not yet involuted. Therefore, as current advances in neonatology have allowed the routine survival of extremely preterm infants as young as 23 weeks' GA, postnatal GMH-IVH can occur in previously undescribed locations. Hemorrhage in the more posterior GMH on head ultrasound, if unrecognized, may lead to errors in diagnosis and mislocalization of this injury to the periventricular white matter or lateral walls of the lateral ventricles instead of to the subependyma, where it is in fact located.

OBJECTIVE

Our aim is to describe posterior GMH in extremely premature infants, including its characteristic imaging appearance and potential pitfalls in diagnosis.

MATERIALS AND METHODS

Over a 5-year period, all consecutive extremely preterm infants of 27 weeks' GA or less who developed GMH-IVH of any grade were included. A consecutive group of 100 very preterm infants of 31 weeks' GA with a GMH-IVH of any grade served as controls.

RESULTS

In 106 extremely preterm neonates (mean GA: 25 weeks, range: 23.1-26.6 weeks) with 212 potential lateral ventricular germinal matrix bleeding sites, 159 sites had bleeds. In 70/159 (44%), the GMH-IVH was located posterior to the caudothalamic grooves and the foramina of Monro, 52 (32.7%) were both anterior and posterior and 21 (13.2%) were exclusively anterior. In 16 ventricles with intraventricular hemorrhage, an origin site in the germinal matrix could not be determined. In the control population of very preterm infants, all hemorrhages were at the anterior caudothalamic grooves and 95% were grade I.

CONCLUSION

Unlike the older very preterm and moderately preterm infants that form the basis of our GMH-IVH description and classification, the extremely preterm infants now routinely surviving have a more fetal pattern of germinal matrix distribution, which is reflected in a different distribution and size of germinal matrix injury. We report the postnatal occurrence of subependymal GMH-IVH in extremely preterm infants in these more primitive, posterior locations, its potential imaging pitfalls and sonographic findings.

Clinical experience with an in-NICU magnetic resonance imaging system

OBJECTIVE

To evaluate the utility of the 1 Tesla (1 T) Embrace (Aspect Imaging) neonatal magnetic resonance imaging (MRI) scanner in a level III NICU.

STUDY DESIGN

Embrace brain MRI findings for 207 infants were reviewed, including 32 scans directly compared within 5 days with imaging on a 3 T Siemens Trio. Clinical MRI scan abnormalities were also compared to cranial ultrasound findings.

RESULT

Of the 207 Embrace brain MRIs, 146 (70.5%) were obtained for clinical indications and 61 (29.5%) were research cases. Abnormal findings were found in 80 scans, most commonly hemorrhage and white matter injury. Notable findings included a stroke, medullary brainstem tumor, and polymicrogyria. In the 1 T versus 3 T comparison cohort, results were discordant in only one infant with punctate foci of susceptibility noted only on the 3 T scan.

CONCLUSION

The Embrace MRI scans detected clinically relevant brain abnormalities and in a subset were clinically comparable to 3 T scans.

Structural Changes in the Cortico-Ponto-Cerebellar Axis at Birth are Associated with Abnormal Neurological Outcomes in Childhood

White matter lesions in hypoxic-ischemic encephalopathy (HIE) are considered to be the important substrate of frequent neurological consequences in preterm infants. The aim of the study was to analyze volumes and tractographic parameters of the cortico-ponto-cerebellar axis to assess alterations in the periventricular fiber system and crossroads, corticopontine and corticospinal pathways and prospective transsynaptic changes of the cerebellum.Term infants (control), premature infants without (normotypic) and with perinatal HIE (HIE) underwent brain magnetic resonance imaging at term-equivalent age (TEA) and at 2 years. Cerebrum, cerebellum, brainstem divisions and ventrodorsal compartments volumetric analysis were performed, as well as fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of corticopontine, corticospinal pathways and middle cerebellar peduncles. Amiel-Tison scale at TEA and the Hempel test at 2 years were assessed.Cerebellum, brainstem and its compartments volumes were decreased in normotypic and HIE groups at TEA, while at 2 years volumes were significantly reduced in the HIE group, accompanied by decreased volume and FA and increased ADC of corticopontine and corticospinal pathways. Negative association of the brainstem, cerebellum, mesencephalon, pons, corticopontine volumes and corticospinal pathway FA at TEA with the neurological score at 2 years. Cerebellum and pons volumes presented as potential prognostic indicators of neurological outcomes.Our findings agree that these pathways, as a part of the periventricular fiber system and crossroads, exhibit lesion-induced reaction and vulnerability in HIE. Structural differences between normotypic and HIE group at the 2 years suggest a different developmental structural plasticity.

Relationship Between Early Functional and Structural Brain Developments and Brain Injury in Preterm Infants

Background

Recent studies explored the relationship between early brain function and brain morphology, based on the hypothesis that increased brain activity can positively affect structural brain development and that excitatory neuronal activity stimulates myelination.

Objective

To investigate the relationship between maturational features from early and serial aEEGs after premature birth and MRI metrics characterizing structural brain development and injury, measured around 30weeks postmenstrual age (PMA) and at term. Moreover, we aimed to verify whether previously developed maturational EEG features are related with PMA.

Design/Methods

One hundred six extremely preterm infants received bedside aEEGs during the first 72h and weekly until week 5. 3T-MRIs were performed at 30weeks PMA and at term. Specific features were extracted to assess EEG maturation: (1) the spectral content, (2) the continuity [percentage of spontaneous activity transients (SAT%) and the interburst interval (IBI)], and (3) the complexity. Automatic MRI segmentation to assess volumes and MRI score was performed. The relationship between the maturational EEG features and MRI measures was investigated.

Results

Both SAT% and EEG complexity were correlated with PMA. IBI was inversely associated with PMA. Complexity features had a positive correlation with the cerebellar size at 30weeks, while event-based measures were related to the cerebellar size at term. Cerebellar width, cortical grey matter, and total brain volume at term were inversely correlated with the relative power in the higher frequency bands.

Conclusions

The continuity and complexity of the EEG steadily increase with increasing postnatal age. Increasing complexity and event-based features are associated with cerebellar size, a structure with enormous development during preterm life. Brain activity is important for later structural brain development.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12311-021-01232-z.

Synthetic MRI demonstrates prolonged regional relaxation times in the brain of preterm born neonates with severe postnatal morbidity

BACKGROUND

To identify preterm infants at risk for neurodevelopment impairment that might benefit from early neurorehabilitation, early prognostic biomarkers of future outcomes are needed.

OBJECTIVE

To determine whether synthetic MRI is sensitive to age-related changes in regional tissue relaxation times in the brain of preterm born neonates when scanned at term equivalent age (TEA, 37-42 weeks), and to investigate whether severe postnatal morbidity results in prolonged regional tissue relaxation times.

MATERIALS AND METHODS

This retrospective study included 70 very preterm born infants scanned with conventional and synthetic MRI between January 2017 and June 2019 at TEA. Infants with severe postnatal morbidity were allocated to a high-risk group (n = 22). All other neonates were allocated to a low-risk group (n = 48). Linear regression analysis was performed to determine the relationship between relaxation times and postmenstrual age (PMA) at scan. Analysis of covariance was used to evaluate the impact of severe postnatal morbidity in the high-risk group on T1 and T2 relaxation times. Receiver operating characteristic (ROC) curves were plotted and analysed with area under the ROC curve (AUC) to evaluate the accuracy of classifying high-risk patients based on regional relaxation times.

RESULTS

A linear age-related decrease of T1 and T2 relaxation times correlating with PMA at scan (between 37 and 42 weeks) was found in the deep gray matter, the cerebellum, the cortex, and the posterior limb of the internal capsule (PLIC) (p < .005 each), but not in the global, frontal, parietal, or central white matter. Analysis of covariance for both risk groups, adjusted for PMA, revealed significantly prolonged regional tissue relaxation times in neonates with severe postnatal morbidity, which was best illustrated in the central white matter of the centrum semiovale (T1 Δ = 11.5%, T2 Δ = 13.4%, p < .001) and in the PLIC (T1 Δ = 9.2%, T2 Δ = 6.9%, p < .001). The relaxation times in the PLIC and the central white matter predicted high-risk status with excellent accuracy (AUC range 0.82-0.86).

CONCLUSION

Synthetic MRI-based relaxometry in the brain of preterm born neonates is sensitive to age-related maturational changes close to TEA. Severe postnatal morbidity correlated with a significant delay in tissue relaxation. Synthetic MRI may provide early prognostic biomarkers for neurodevelopment impairment.

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.

Respiratory Support of the Preterm Neonate: Lessons About Ventilation-Induced Brain Injury From Large Animal Models

Many preterm neonates require mechanical ventilation which increases the risk of cerebral inflammation and white matter injury in the immature brain. In this review, we discuss the links between ventilation and brain injury with a focus on the immediate period after birth, incorporating respiratory support in the delivery room and subsequent mechanical ventilation in the neonatal intensive care unit. This review collates insight from large animal models in which acute injurious ventilation and prolonged periods of ventilation have been used to create clinically relevant brain injury patterns. These models are valuable resources in investigating the pathophysiology of ventilation-induced brain injury and have important translational implications. We discuss the challenges of reconciling lung and brain maturation in commonly used large animal models. A comprehensive understanding of ventilation-induced brain injury is necessary to guide the way we care for preterm neonates, with the goal to improve their neurodevelopmental outcomes.

Low-Grade Intraventricular Hemorrhage and Neurodevelopmental Outcomes at 24-42 Months of Age

Infants with high-grade (III-IV) intraventricular hemorrhage have been reported to have worse neurodevelopmental outcomes than those without, but outcomes of infants with low-grade (I-II) intraventricular hemorrhage are mixed. We sought to compare neurodevelopmental outcomes of infants with low-grade intraventricular hemorrhage to those with no intraventricular hemorrhage. This is a retrospective cohort study of very preterm (≤32 weeks' gestation) infants evaluated between 24 and 42 months chronologic age using the Bayley Scales of Infant Development, 3rd edition, to determine neurodevelopmental outcomes. Linear regression was used to control for potential confounders. There was no difference in outcome scores between groups when controlling for confounding variables. Infants with low-grade intraventricular hemorrhage, however, had higher rates of enrollment in early intervention services (64% vs 49%, P = .023). Low-grade intraventricular hemorrhage itself may not significantly increase the risk of neurodevelopmental impairment through the first 3 years of life considering other conditions of prematurity.

Effect of preterm birth on morphosyntactic development

Background: Preterm children are at risk of deficits in language, including grammatical skills. The main purpose of this survey was to investigate whether Persian-speaking children born preterm differ in their morphosyntax ability compared to full-term children.

Methods: Morphosyntactic performance was assessed in 86 Persian-speaking children (43 healthy preterm and 43 full-term children) aged 4 and 5 years using the Persian Developing Sentence Scoring (PDSS). Participants were matched for age, gender, and gestational age.

Results: The healthy preterm children who participated in this study were significantly outperformed by the full-term children in the morphosyntactic evaluation (p<0.05). Furthermore, their grammatical skills, based on PDSS, were not as developed as 4 to 5-year-old full-term children. Gender, in general, and gestational age had no effect on the PDSS scores of preterm children (p>0.05).

Conclusion: Preterm children, regardless of gestational age, are at risk of morphosyntax impairments, which may not be recovered during the normal development. Therefore, grammatical evaluation and treatment seem to be necessary for these children.

Reduced Neurosteroid Exposure Following Preterm Birth and Its' Contribution to Neurological Impairment: A Novel Avenue for Preventative Therapies

Children born preterm are at an increased risk of developing cognitive problems and neuro-behavioral disorders such as attention deficit hyperactivity disorder (ADHD) and anxiety. Whilst neonates born at all gestational ages, even at term, can experience poor cognitive outcomes due to birth-complications such as birth asphyxia, it is becoming widely known that children born preterm in particular are at significant risk for learning difficulties with an increased utilization of special education resources, when compared to their healthy term-born peers. Additionally, those born preterm have evidence of altered cerebral myelination with reductions in white matter volumes of the frontal cortex, hippocampus and cerebellum evident on magnetic resonance imaging (MRI). This disruption to myelination may underlie some of the pathophysiology of preterm-associated brain injury. Compared to a fetus of the same post-conceptional age, the preterm newborn loses access to in utero factors that support and promote healthy brain development. Furthermore, the preterm ex utero environment is hostile to the developing brain with a myriad of environmental, biochemical and excitotoxic stressors. Allopregnanolone is a key neuroprotective fetal neurosteroid which has promyelinating effects in the developing brain. Preterm birth leads to an abrupt loss of the protective effects of allopregnanolone, with a dramatic drop in allopregnanolone concentrations in the preterm neonatal brain compared to the fetal brain. This occurs in conjunction with reduced myelination of the hippocampus, subcortical white matter and cerebellum; thus, damage to neurons, astrocytes and especially oligodendrocytes of the developing nervous system can occur in the vulnerable developmental window prior to term as a consequence reduced allopregnanolone. In an effort to prevent preterm-associated brain injury a number of therapies have been considered, but to date, other than antenatal magnesium sulfate and corticosteroid therapy, none have become part of standard clinical care for vulnerable infants. Therefore, there remains an urgent need for improved therapeutic options to prevent brain injury in preterm neonates. The actions of the placentally derived neurosteroid allopregnanolone on GABAA receptor signaling has a major role in late gestation neurodevelopment. The early loss of this intrauterine neurotrophic support following preterm birth may be pivotal to development of neurodevelopmental morbidity. Thus, restoring the in utero neurosteroid environment for preterm neonates may represent a new and clinically feasible treatment option for promoting better trajectories of myelination and brain development, and therefore reducing neurodevelopmental disorders in children born preterm.

Language Network Function in Young Children Born Very Preterm

Language deficits are reported in preterm born children across development. Recent neuroimaging studies have found functional alterations in large-scale brain networks underlying these language deficits, but the early childhood development of the language network has not been investigated. Here, we compared intrinsic language network connectivity in 4-year-old children born VPT and term-born controls, using defined language regions (Broca's area, Wernicke's areas, and their homologues in the right hemisphere). Resting-state functional magnetic resonance imaging (fMRI) was obtained, and the group differences in whole-brain connectivity were examined from each seed as well as correlations with language outcomes. We found significantly decreased functional connectivity in almost all language regions in children born VPT compared to their term controls. Notably, Broca's area homologue in the right hemisphere emerged as a functional hub of decreased connectivity in VPT group, specifically to bilateral inferior frontal and supramarginal gyri; connectivity strength between Broca's area homologue with the right supramarginal and the left inferior frontal gyri was associated with better language outcomes at 4 years of age. Wernicke's area and its homologue also showed decreased inter-hemispheric connections to bilateral supramarginal gyri in the VPT group. Decreased intra- and inter-hemispheric connectivity among primary language regions suggests immature and altered function in the language network in children born VPT.

Hemodynamic and Metabolic Assessment of Neonates With Punctate White Matter Lesions Using Phase-Contrast MRI and T2-Relaxation-Under-Spin-Tagging (TRUST) MRI

The brain's hemodynamic and metabolism of punctate white matter lesions (PWML) is poorly understood due to a scarcity of non-invasive imaging techniques. The aim of this study was to apply new MRI techniques to quantify cerebral metabolic rate of oxygen (CMRO₂), global cerebral blood flow (CBF), oxygen saturation fractions in venous blood (Yv) and oxygen extraction fraction (OEF) in neonates with PWML, for better understanding of the pathophysiology of PWML. Fifty-one newborns were recruited continuously, including 23 neonatal patients with PWML and 28 normal control neonates. Phase-contrast (PC) MRI and T2-Relaxation-Under-Spin-Tagging (TRUST) MRI were performed for the measurement of CBF and Yv. OEF and CMRO₂ were calculated from the CBF and Yv values. The total maturation score (TMS) was assessed for each neonate on standard T1, 2-weighted images to evaluate cerebral maturation. The CMRO₂, CBF, Yv, and OEF values were compared between groups, and their associations with age and TMS were evaluated. Significant differences between PWML group and control group were found in CMRO₂ (P = 0.020), CBF (P = 0.027), Yv (P = 0.012), OEF (P = 0.018). After age/maturation is accounted for, Yv and OEF showed significant dependence on the groups (P < 0.05). Newborns with PWML had lower OEF and higher Yv. CMRO₂, CBF and brain volume were correlated with age (P < 0.001) and TMS (P < 0.05). It is feasible to use non-invasive MRI methods to measure cerebral oxygen supply and consumption in neonates with PWML. Newborns with PWML have lower oxygen consumption. Yv and OEF may be helpful for the diagnosis of PWML. The positive correlation between CBF and TMS, and between CMRO₂ and TMS suggested that as myelination progresses, the blood supply and oxygen metabolism in the brain increase to meet the escalating energy demand.

Protective effect of miconazole on rat myelin sheaths following premature infant cerebral white matter injury

The aim of the present study was to investigate the protective effects of miconazole on myelin sheaths following cerebral white matter damage (WMD) in premature infant rats. Sprague Dawley rats (3-days-old) were randomly divided into four groups (n=30 each) as follows: Sham surgery group, WMD model group, 10 mg/kg/day treatment group and 40 mg/kg/day treatment group. A cerebral white matter lesion model was created by ligating the right common carotid artery for 80 min. Treatment groups were administered with 10 or 40 mg/kg miconazole at 4–8 days following birth (early treatment group) or 5–11 days following birth (late treatment group). Rats in the model group received the same concentration of dimethylsulfoxide. Myelin basic protein (MBP) immunohistochemical staining and western blotting were used to detect the expression of cerebral white matter-specific MBP, and changes in myelin structure were observed using transmission electron microscopy. No swelling or necrosis was observed in the corpus callosum of the sham group rats, whereas rats in the model group demonstrated edema, loose structure, fiber disorder, inflammatory gliocytes and selective white matter lesions. Following treatment with miconazole, MBP expression in the corpus callosum was significantly higher compared with the model group. Furthermore, in the model group, myelin sheaths in the corpus callosum were loose with small vacuoles, there was a marked decrease in thickness and structural damage was observed. Conversely, a marked improvement in myelination was observed in the treatment group. The results of the present study suggest that miconazole is able to promote formation of the myelin sheath to ameliorate premature cerebral white matter lesions caused by ischemia or hypoxia in rats.

Cortical morphometry and cognition in very preterm and term-born children at early school age

Very preterm birth influences brain development and may result in alterations of cortical morphometry. These structural alterations may interact with cognitive development. The aim of the present study was to investigate the structure-function relationship in school-aged very preterm and term-born control children. A comprehensive neuropsychological test battery was administered to 41 very preterm (<32 weeks of gestation) and 30 term-born control children aged seven to twelve years. The automated method FreeSurfer was used to obtain cortical thickness and cortical surface area measures from T1-weighted MRI images. Regional cortical thickness differed between groups but differences disappeared when controlling for age. Global cortical thickness differed between groups in the right hemisphere (very preterm children>controls). No group differences occurred for cortical surface area. The relationship between cortical morphometry and cognition differed between very preterm and control children. In very preterm children, some cognitive domains correlated positively and others negatively with regional cortical thickness and cortical surface area. Our findings contribute to the understanding of the structure-function relationship in very preterm children and their term-born peers. They add to the notion that this relationship varies depending on the brain region and the cognitive function in question and suggest developmental differences between very preterm and term-born children.

Disruptions to the cerebellar GABAergic system in juvenile guinea pigs following preterm birth

BACKGROUND

Children that are born preterm are at an increased risk of developing cognitive problems and behavioural disorders, such as attention deficit hyperactivity disorder (ADHD). There is increasing interest in the role of the cerebellum in these processes and the potential involvement of GABAergic pathways in neurodevelopmental disorders. We propose that preterm birth, and the associated loss of the trophic intrauterine environment, alters the development of the cerebellum, contributing to ongoing neurobehavioral disorders.

METHODS

Guinea pigs were delivered preterm (GA62) or spontaneously at term (GA69), and tissues collected at corrected postnatal day (PND) 28. Neurodevelopmental and GABAergic markers myelin basic protein (MBP), neuronal nuclei (NeuN), calbindin (Purkinje cells), and GAD67 (GABA synthesis enzyme) were analysed in cerebellar lobules IX and X by immunohistochemistry. Protein expression of GAD67 and GAT1 (GABA transporter enzyme) were quantified by western blot, whilst neurosteroid-sensitive GABA_A receptor subunits were measured by RT-PCR.

RESULTS

MBP immunostaining was increased in lobule IX of preterm males, and reduced in lobule X of preterm females when compared to their term counterparts. GAD67 staining was decreased in lobule IX and X of the preterm males, but only in lobule X of the preterm females compared to term cohorts for each sex. Internal granule cell layer width of lobule X was decreased in preterm cohorts of both sexes compared to terms. There were no differences between gestational age groups for NeuN staining, GAD67 and GAT1 protein expression as measured by western blotting, or GABA_A receptor subunits as measured by RT-PCR between preterm and term for either sex.

CONCLUSIONS

The present findings suggest that components of the cerebellar GABAergic system of the ex-preterm cerebellum are disrupted. The higher expression of myelin in the preterm males may be due to a deficit in axonal pruning, whereas females have a deficit in myelination at 28 corrected days of age. Together these ongoing alterations may contribute to the neurodevelopmental and behavioural disorders observed in those born preterm.

A new neonatal cortical and subcortical brain atlas: the Melbourne Children's Regional Infant Brain (M-CRIB) atlas

Investigating neonatal brain structure and function can offer valuable insights into behaviour and cognition in healthy and clinical populations; both at term age, and longitudinally in comparison with later time points. Parcellated brain atlases for adult populations are readily available, however warping infant data to adult template space is not ideal due to morphological and tissue differences between these groups. Several parcellated neonatal atlases have been developed, although there remains strong demand for manually parcellated ground truth data with detailed cortical definition. Additionally, compatibility with existing adult atlases is favourable for use in longitudinal investigations. We aimed to address these needs by replicating the widely-used Desikan-Killiany (2006) adult cortical atlas in neonates. We also aimed to extend brain coverage by complementing this cortical scheme with basal ganglia, thalamus, cerebellum and other subcortical segmentations. Thus, we have manually parcellated these areas volumetrically using high-resolution neonatal T₂-weighted MRI scans, and initial automated and manually edited tissue classification, providing 100 regions in all. Linear and nonlinear T₂-weighted structural templates were also generated. In this paper we provide manual parcellation protocols, and present the parcellated probability maps and structural templates together as the Melbourne Children's Regional Infant Brain (M-CRIB) atlas.

Basal ganglia perfusion in the preterm infant during transition

BACKGROUND

The preterm brain is susceptible to changes in blood flow. Using power Doppler images, digital imaging techniques have been developed to measure the total amount of blood flow in a defined area, giving the index: fractional moving blood volume (FMBV). The aim of this study was to investigate temporal changes in basal ganglia perfusion during the transitional period after birth.

METHODS

Twenty-four preterm infants were examined with serial cranial ultrasounds at four time points during the first 48 h of life. FMBV was calculated using power Doppler images at each time point.

RESULTS

All infants had analyzable data and FMBV was successfully calculated at all time points. Twenty-three of the 24 infants had an increasing trend in FMBV over time. The median FMBV increased from 17% at 6 h to 25% at 48 h. One-way repeated measures ANOVA showed a significant increase in values at P < 0.001 at each of the four time points.

CONCLUSION

We have demonstrated changes in basal ganglia blood flow as the cerebral circulation adapts to extrauterine life. With further investigation, this technique may be useful in the assessment of preterm circulatory adaptation, either alone or in conjunction with other modes of evaluating cerebral blood flow.

Long-term effects of preterm birth on behavior and neurosteroid sensitivity in the guinea pig

BACKGROUND

Ex-preterm children and adolescents are at risk of developing late-onset neurodevelopmental and behavioral disorders. The mechanisms by which this happens are poorly understood and relevant animal models are required.

METHODS

Ex-preterm (delivered at 62 d gestation) and term (spontaneously delivered) juvenile guinea pigs underwent behavioral testing at 25 d corrected postnatal age, with tissues collected at 28 d. Neurodevelopmental markers (myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP)) were analyzed in the hippocampus and subcortical white matter by immunohistochemistry. Gamma-aminobutyric acid A (GABAA) receptor subunit mRNA levels were quantified by reverse transcription polymerase chain reaction (RT-PCR), and salivary cortisol measured by enzyme-linked immunosorbent assay.

RESULTS

Preterm males travelled greater distances, were mobile for longer, spent more time investigating objects, and approached or interacted with familiar animals more than controls. Myelination and reactive astrocyte coverage was lower in the hippocampus and the subcortical white matter in preterm males. Hippocampal levels of the α5 subunit were also lower in the preterm male brain. Baseline salivary cortisol was higher for preterm males compared to controls.

CONCLUSION

We conclude that juvenile ex-preterm male guinea pigs exhibit a hyperactive phenotype and feature impaired neurodevelopment, making this a suitable model for future therapeutic studies.

Clinical Outcomes after Selective Fetal Reduction of Complicated Monochorionic Twins with Radiofrequency Ablation and Bipolar Cord Coagulation

AIMS

To review pregnancy outcomes, complication rates and neonatal neural development of selective termination procedures for complicated monochorionic (MC) twins.

METHODS

This was a retrospective review of the pregnancies that underwent selective reduction with radiofrequency ablation (RFA) and bipolar cord coagulation (BCC) in our institution.

RESULTS

Forty-eight cases underwent selective reduction with BCC and the remaining 45 with RFA. Overall survival was not statistically different between the RFA and BCC groups (71.1 and 62.5%, p = 0.379). With regard to the indications, the survival rates were not significantly different for twin to twin transfusion syndrome, twin reversed arterial perfusion, discordant anomalies and selective intrauterine growth restriction. Preterm premature rupture of membrane was not statistically different between the BCC and RFA groups (47.9 and 33.3%, p = 0.153). Five foetuses presented with abnormal middle cerebral artery-peak systolic velocity in the BCC group and 4 in the RFA group (p = 0.829). In the BCC group, neurological injury was detected in 2 neonates, presenting with cerebral dysplasia on MR scanning. In the RFA group, intracranial haemorrhage Grade III was detected in one neonate with cranial ultrasound (p = 0.607).

CONCLUSIONS

Overall survival and complication rates following selective reduction in complicated MC twin pregnancies is similar irrespective of whether the reduction was performed using RFA or BCC. Key Message: It seems that selective reduction in MC pregnancies with RFA does not carry a significant decrease in the overall survival and complication rates than the cases with BCC. According to our data, neurodevelopmental impairment of the co-twins is relatively seldom after selective reduction.

Differential short-term regional effects of early high dose erythropoietin on white matter in preterm lambs after mechanical ventilation

Inadvertently injurious ventilation of preterm neonates in the delivery room can cause cerebral white matter (WM) inflammation and injury. We investigated the impact of an early high dose of recombinant human erythropoietin (EPO) on ventilation-induced WM changes in preterm lambs. Injurious ventilation, targeting a V(T) of 15 ml kg(-1) with no positive end-expiratory pressure, was initiated for 15 min in preterm lambs (0.85 gestation). Conventional ventilation was continued for a further 105 min. Lambs received either 5000 IU kg(-1) of EPO (EPREX®; Vent+EPO; n = 6) or vehicle (Vent; n = 8) via an umbilical vein at 4 ± 2 min. Markers of WM injury and inflammation were assessed using quantitative real-time PCR (qPCR) and immunohistochemistry and compared to a group of unventilated controls (UVC; n = 4). In Vent+EPO lambs compared to Vent lambs: (i) interleukin (IL)-1β and IL-6 mRNA levels in the periventricular WM and IL-8 mRNA levels in the subcortical WM were higher (P < 0.05 for all); (ii) the density of microglia within the aggregations was not different in the periventricular WM and was lower in the subcortical WM (P = 0.001); (iii) the density of astrocytes was lower in the subcortical WM (P = 0.002); (iv) occludin and claudin-1 mRNA levels were higher in the periventricular WM (P < 0.02 for all) and (vi) the number of blood vessels with protein extravasation was lower (P < 0.05). Recombinant human EPO had variable regional effects within the WM when administered during injurious ventilation. The adverse short-term outcomes discourage the use of early high dose EPO administration in preterm ventilated babies.

Predicting developmental outcomes in premature infants by term equivalent MRI: systematic review and meta-analysis

BACKGROUND

This study aims to determine the prognostic accuracy of term MRI in very preterm born (≤32 weeks) or low-birth-weight (≤1500 g) infants for long-term (>18 months) developmental outcomes.

METHODS

We performed a systematic review searching Central, Medline, Embase, and PsycInfo. Two independent reviewers performed study selection, data extraction, and quality assessment. We documented sensitivity and specificity for three different MRI findings (white matter abnormalities (WMA), brain abnormality (BA), and diffuse excessive high signal intensity (DEHSI)), related to developmental outcomes including cerebral palsy (CP), visual and/or hearing problems, motor, neurocognitive, and behavioral function. Using bivariate meta-analysis, we estimated pooled sensitivity and specificity and plotted summary receiver operating characteristic (sROC) curves for different cut-offs of MRI.

RESULTS

We included 20 papers published between 2000 and 2013. Quality of included studies varied. Pooled sensitivity and specificity values (95 % confidence interval (CI)) for prediction of CP combining the three different MRI findings (using normal/mild vs. moderate/severe cut-off) were 77 % (53 to 91 %) and 79 % (51 to 93 %), respectively. For prediction of motor function, the values were 72 % (52 to 86 %) and 62 % (29 to 87 %), respectively. Prognostic accuracy for visual and/or hearing problems, neurocognitive, and/or behavioral function was poor. sROC curves of the individual MRI findings showed that presence of WMA provided the best prognostic accuracy whereas DEHSI did not show any potential prognostic accuracy.

CONCLUSIONS

This study shows that presence of moderate/severe WMA on MRI around term equivalent age can predict CP and motor function in very preterm or low-birth-weight infants with moderate sensitivity and specificity. Its ability to predict other long-term outcomes such as neurocognitive and behavioral impairments is limited. Also, other white matter related tests as BA and DEHSI demonstrated limited prognostic value.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42013006362.

MRI evaluation and safety in the developing brain

Magnetic resonance imaging (MRI) evaluation of the developing brain has dramatically increased over the last decade. Faster acquisitions and the development of advanced MRI sequences, such as magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), perfusion imaging, functional MR imaging (fMRI), and susceptibility-weighted imaging (SWI), as well as the use of higher magnetic field strengths has made MRI an invaluable tool for detailed evaluation of the developing brain. This article will provide an overview of the use and challenges associated with 1.5-T and 3-T static magnetic fields for evaluation of the developing brain. This review will also summarize the advantages, clinical challenges, and safety concerns specifically related to MRI in the fetus and newborn, including the implications of increased magnetic field strength, logistics related to transporting and monitoring of neonates during scanning, and sedation considerations, and a discussion of current technologies such as MRI conditional neonatal incubators and dedicated small-foot print neonatal intensive care unit (NICU) scanners.

Human Amnion Epithelial Cells Modulate Ventilation-Induced White Matter Pathology in Preterm Lambs

BACKGROUND

Preterm infants can be inadvertently exposed to high tidal volumes (VT) during resuscitation in the delivery room due to limitations of available equipment. High VT ventilation of preterm lambs produces cerebral white matter (WM) pathology similar to that observed in preterm infants who develop cerebral palsy. We hypothesized that human amnion epithelial cells (hAECs), which have anti-inflammatory and regenerative properties, would reduce ventilation-induced WM pathology in neonatal late preterm lamb brains.

METHODS

Two groups of lambs (0.85 gestation) were used, as follows: (1) ventilated lambs (Vent; n = 8) were ventilated using a protocol that induces injury (VT targeting 15 ml/kg for 15 min, with no positive end-expiratory pressure) and were then maintained for another 105 min, and (2) ventilated + hAECs lambs (Vent+hAECs; n = 7) were similarly ventilated but received intravenous and intratracheal administration of 9 × 10(7) hAECs (18 × 10(7) hAECs total) at birth. Oxygenation and ventilation parameters were monitored in real time; cerebral oxygenation was measured using near-infrared spectroscopy. qPCR (quantitative real-time PCR) and immunohistochemistry were used to assess inflammation, vascular leakage and astrogliosis in both the periventricular and subcortical WM of the frontal and parietal lobes. An unventilated control group (UVC; n = 5) was also used for qPCR analysis of gene expression. Two-way repeated measures ANOVA was used to compare physiological data. Student's t test and one-way ANOVA were used for immunohistological and qPCR data comparisons, respectively.

RESULTS

Respiratory parameters were not different between groups. Interleukin (IL)-6 mRNA levels in subcortical WM were lower in the Vent+hAECs group than the Vent group (p = 0.028). IL-1β and IL-6 mRNA levels in periventricular WM were higher in the Vent+hAECs group than the Vent group (p = 0.007 and p = 0.001, respectively). The density of Iba-1-positive microglia was lower in the subcortical WM of the parietal lobes (p = 0.010) in the Vent+hAECs group but not in the periventricular WM. The number of vessels in the WM of the parietal lobe exhibiting protein extravasation was lower (p = 0.046) in the Vent+hAECs group. Claudin-1 mRNA levels were higher in the periventricular WM (p = 0.005). The density of GFAP-positive astrocytes was not different between groups.

CONCLUSIONS

Administration of hAECs at the time of birth alters the effects of injurious ventilation on the preterm neonatal brain. Further studies are required to understand the regional differences in the effects of hAECs on ventilation-induced WM pathology and their net effect on the developing brain.

Microglia toxicity in preterm brain injury

•

Microglia responses in the preterm human brain in association with injury.

•

Microglia responses in animal models of preterm brain injury.

•

Mechanisms of microglia toxicity from in vitro primary microglia cell culture experiments.

Microglia are the resident phagocytic cells of the central nervous system. During brain development they are also imperative for apoptosis of excessive neurons, synaptic pruning, phagocytosis of debris and maintaining brain homeostasis. Brain damage results in a fast and dynamic microglia reaction, which can influence the extent and distribution of subsequent neuronal dysfunction. As a consequence, microglia responses can promote tissue protection and repair following brain injury, or become detrimental for the tissue integrity and functionality. In this review, we will describe microglia responses in the human developing brain in association with injury, with particular focus on the preterm infant. We also explore microglia responses and mechanisms of microglia toxicity in animal models of preterm white matter injury and in vitro primary microglia cell culture experiments.

Prognostic value of gradient echo T2* sequences for brain MR imaging in preterm infants

BACKGROUND

Gradient echo T2*-W sequences are more sensitive than T2-W spin-echo sequences for detecting hemorrhages in the brain.

OBJECTIVE

The aim of this study is to correlate presence of hemosiderin deposits in the brain of very preterm infants (gestational age <32 weeks) detected by T2*-W gradient echo MRI to white matter injury and neurodevelopmental outcome at 2 years.

MATERIALS AND METHODS

In 101 preterm infants, presence and location of hemosiderin were assessed on T2*-W gradient echo MRI performed around term-equivalent age (range: 40-60 weeks). White matter injury was defined as the presence of >6 non-hemorrhagic punctate white matter lesions (PWML), cysts and/or ventricular dilatation. Six infants with post-hemorrhagic ventricular dilatation detected by US in the neonatal period were excluded. Infants were seen for follow-up at 2 years. Univariate and regression analysis assessed the relation between presence and location of hemosiderin, white matter injury and neurodevelopmental outcome.

RESULTS

In 38/95 (40%) of the infants, hemosiderin was detected. Twenty percent (19/95) of the infants were lost to follow-up. There was a correlation between hemosiderin in the ventricular wall with >6 PWML (P < 0.001) and cysts (P < 0.001) at term-equivalent age, and with a lower psychomotor development index (PDI) (P=0.02) at 2 years. After correcting for known confounders (gestational age, gender, intrauterine growth retardation and white matter injury), the correlation with PDI was no longer significant.

CONCLUSION

The clinical importance of detecting small hemosiderin deposits is limited as there is no independent association with neurodevelopmental outcome.

The role of neuroimaging in predicting neurodevelopmental outcomes of preterm neonates

Magnetic resonance imaging (MRI) is a safe and high-resolution neuroimaging modality that is increasingly used in the neonatal population to assess brain injury and its consequences on brain development. It is superior to cranial ultrasound for the definition of patterns of both white and gray matter maturation and injury and therefore has the potential to provide prognostic information on the neurodevelopmental outcomes of the preterm population. Furthermore, the development of sophisticated MRI strategies, including diffusion tensor imaging, resting state functional connectivity, and magnetic resonance spectroscopy, may increase the prognostic value, helping to guide parental counseling and allocate early intervention services.

Relation of neural structure to persistently low academic achievement: a longitudinal study of children with differing birth weights

OBJECTIVE

This study examined the relation of cerebral tissue reductions associated with VLBW to patterns of growth in core academic domains.

METHOD

Children born <750 g, 750 to 1,499 g, or >2,500 g completed measures of calculation, mathematical problem solving, and word decoding at time points spanning middle childhood and adolescence. K. A. Espy, H. Fang, D. Charak, N. M. Minich, and H. G. Taylor (2009, Growth mixture modeling of academic achievement in children of varying birth weight risk, Neuropsychology, Vol. 23, pp. 460-474) used growth mixture modeling to identify two growth trajectories (clusters) for each academic domain: an average achievement trajectory and a persistently low trajectory. In this study, 97 of the same participants underwent magnetic resonance imaging (MRI) in late adolescence, and cerebral tissue volumes were used to predict the probability of low growth cluster membership for each domain.

RESULTS

Adjusting for whole brain volume (wbv), each 1-cm(3) reduction in caudate volume was associated with a 1.7- to 2.1-fold increase in the odds of low cluster membership for each domain. Each 1-mm(2) decrease in corpus callosum surface area increased these odds approximately 1.02-fold. Reduced cerebellar white matter volume was associated specifically with low calculation and decoding growth, and reduced cerebral white matter volume was associated with low calculation growth. Findings were similar when analyses were confined to the VLBW groups.

CONCLUSIONS

Reduced volume of structures involved in connectivity, executive attention, and motor control may contribute to heterogeneous academic trajectories among children with VLBW.

Cerebral magnetic resonance imaging findings in children born extremely preterm, very preterm, and at term

BACKGROUND

The aim of this study was to compare findings on cerebral MRI scans of infants born extremely preterm (i.e., gestation < 28 weeks, very preterm; gestation 28-31 weeks) and at term.

METHODS

MRI scans obtained in a cohort of 29 extremely preterm children at 11 years, 51 very preterm young adults at 19 years, and respective term-born controls were scored according to presence and degree of MRI pathology.

RESULTS

MRI pathology was found in 76% of the extremely preterm children vs 31% of their controls (odds ratio 4.3; 95% confidence interval, 1.5-137.5) and in 55% of the very preterm group vs 19% of their controls (odds ratio 5.2; 95% confidence interval, 2.5-10.9). The distribution of moderate and severe pathology did not differ among the groups.

CONCLUSIONS

The extremely preterm, very preterm, and term subjects shared the same morphological pathology, revealing no specific preterm MRI pattern, but both premature cohorts had higher frequencies. Differences were mainly limited to mild pathology. Whether MRI lesions were more common in the extremely preterm than in the very preterm group is uncertain as the difference in frequency was similar in the two control groups, suggesting a lack of objective criteria for differentiating mild pathology from normality or that MRI scans normally differ at 11 and 19 years of age.

Optimal timing of cerebral MRI in preterm infants to predict long-term neurodevelopmental outcome: a systematic review

SUMMARY

Advances in neonatal neuroimaging have improved detection of preterm brain injury responsible for abnormal neuromotor and cognitive development. Increasingly sophisticated MR imaging setups allow scanning during early preterm life. In this review, we investigated how brain MR imaging in preterm infants should be timed to best predict long-term outcome. Given the strong evidence that structural brain abnormalities are related to long-term neurodevelopment, MR imaging should preferably be performed at term-equivalent age. Early MR imaging is promising because it can guide early intervention studies and is indispensable in research on preterm brain injury.

Tractography of white-matter tracts in very preterm infants: a 2-year follow-up study

AIM

The aim of this study was to determine whether tractography of white-matter tracts can independently predict neurodevelopmental outcome in very preterm infants.

METHOD

Out of 84 very preterm infants admitted to a neonatal intensive care unit, 64 (41 males, 23 females; median gestational age 29.1 weeks [range 25.6-31.9]; birthweight 1163 g [range 585-1960]) underwent follow-up at 2 years. Diffusion tensor imaging (DTI) values obtained around term were associated with a neurological examination and mental and psychomotor developmental index scores at 2 years based on the Bayley Scales of Infant Development (version 3). Univariate and logistic regression analyses tested for associations between DTI values and follow-up parameters. Cut-off values predicting motor delay and cerebral palsy (CP) were determined for fractional anisotropy, apparent diffusion coefficient (ADC), and fibre lengths.

RESULTS

Infants with psychomotor delay and CP had significantly lower fractional anisotropy values (p=0.002, p=0.04 respectively) and shorter fibre lengths (p=0.02, p=0.02 respectively) of the posterior limb of the internal capsule. Infants with psychomotor delay also had significantly higher ADC values (p=0.03) and shorter fibre lengths (p=0.002) of the callosal splenium. Fractional anisotropy values of the posterior limb of the internal capsule independently predicted motor delay and CP, with sensitivity between 80 and 100% and specificity between 66 and 69%. ADC values of the splenium independently predicted motor delay with sensitivity of 100% and specificity of 65%.

INTERPRETATION

Diffusion tensor imaging tractography at term-equivalent age independently predicts psychomotor delay at 2 years of age in preterm infants.

Incidental sonographic diagnosis of neonatal carotid occlusion

Cranial ultrasonography including colour Doppler can detect neonatal carotid flow problems at an early stage, even before symptoms occur. Different pathogeneses can be identified. The condition is more frequent than previously reported. If the circle of Willis is fully developed, this can prevent brain injury even in case of total carotid flow obstruction

CONCLUSION

Screening of the carotid artery in critically ill neonates may detect complications of treatment at an early stage.

Acquisition guidelines and quality assessment tools for analyzing neonatal diffusion tensor MRI data

Diffusion tensor imaging is a valuable measure in clinical settings to assess diagnosis and prognosis of neonatal brain development. However, obtaining reliable images is not straightforward because of the tissue characteristics of the neonatal brain and the high likelihood of motion artifacts. In this review, we present guidelines on how to acquire DTI data of the neonatal brain and recommend high-quality data acquisition and processing as an essential means to obtain accurate and robust parametric maps. Sudden head movements are problematic for DTI in neonates, and these may lead to incorrect values. We describe strategies to minimize the corrupting effects both in terms of acquisition (eg, more gradient directions) and postprocessing (eg, tensor estimation methods). In addition, tools are described that can help assess whether a dataset is of sufficient quality for further assessment.

Cerebral white matter and neurodevelopment of preterm infants after coagulase-negative staphylococcal sepsis

OBJECTIVE

Coagulase-negative staphylococci are the most common pathogens causing late-onset sepsis in the neonatal intensive care unit. Neonatal sepsis can be associated with cerebral white matter damage in preterm infants. Neurodevelopment has been shown to be correlated with apparent diffusion coefficients, fractional anisotropy, and axial and radial diffusivities of the white matter.

DESIGN

Prospective cohort study.

SETTING

Twenty-eight-bed neonatal intensive care unit at a tertiary care children's hospital.

PATIENTS

Seventy preterm infants (gestational age <32 wks), 28 with coagulase-negative staphylococcal sepsis (group 1) and 42 without sepsis (group 2).

INTERVENTION

The values of apparent diffusion coefficients, fractional anisotropy, and axial and radial diffusivity of three white matter regions (parietal, frontal, and occipital), estimated with diffusion-tensor magnetic resonance imaging with a 3.0-T magnetic resonance imaging system, were obtained at term-equivalent age. Neurodevelopmental outcome assessments were performed at 15 months (Griffiths Mental Developmental Scales) and 24 months (Bayley Scales of Infant and Toddler Development, Third Edition) corrected age.

MEASUREMENTS AND MAIN RESULTS

Values of apparent diffusion coefficients, fractional anisotropy, and axial and radial diffusivity of the left and right white matter regions were equal in all patients. There was no significant difference in apparent diffusion coefficient values (mean of total: 1.593 ± 0.090 × 10mm(-3)/sec(2) and 1.601 ± 0.117 × 10mm(-3)/sec(2), respectively, p = .684), fractional anisotropy values (mean of total: 0.19 ± 0.04 and 0.19 ± 0.03, respectively, p = .350), radial diffusivity (mean of total: 1.420 ± 0.09 × 10mm(-3)/sec(2)and 1.425 ± 0.12 × 10mm(-3)/sec(2), respectively, p = .719), and axial diffusivity (mean of total: 1.940 ± 0.12 × 10mm(-3)/sec(2) and 1.954 ± 0.13 × 10mm(-3)/sec(2), respectively, p = .590) in the three combined regions between the two groups. No significant differences were found in neurodevelopmental outcome at 24 months.

CONCLUSIONS

No association was found between coagulase-negative staphylococcal sepsis in preterm infants and cerebral white matter damage as determined by values of apparent diffusion coefficients, fractional anisotropy, and radial and axial diffusivity at term-equivalent age, and no adverse effect was seen on early neurodevelopmental outcome.