Effect of chorioamnionitis on brain development and injury in premature newborns

Associations of Bronchopulmonary Dysplasia and Infection with School-Age Brain Development in Children Born Preterm

OBJECTIVE

To determine the association of bronchopulmonary dysplasia (BPD) and culture-positive infection with neurodevelopment and white matter maturation at 8 years of age in children born preterm.

STUDY DESIGN

Prospective cohort study of 164 children born at 24-32 weeks of gestation followed to 8 years of age (89 male, median [IQR] age: 8.24 [8.07-8.58] years). At age 8, IQ (Weschler Abbreviated Scale of Intelligence, second Ed), working memory (Wechsler Intelligence Scale for Children, fifth Ed), visual-motor (Beery-Buktenica Developmental Test of Visual-Motor Integration sixth Ed), and motor outcomes (Movement Assessment Battery for Children-2) were assessed. Diffusion tensor imaging and tract-based spatial statistics were used to assess fractional anisotropy (FA).

RESULTS

Fifty of 164 children had BPD and 72/164 had culture-positive infection. At 8 years, BPD was associated with a 9.8-point decrease in motor (CI -17.9 to -1.8, P = .02) and 6.0-point decrease in visual-motor scores (CI -10.5 to -1.5, P = .009), whereas infection was associated with a 6.3-point decrease in IQ (CI -12.3 to -0.3, P = .04), after adjusting for gestational age and white matter injury volume. BPD was associated with left hemisphere-dominant FA reductions, which were associated with worse motor (P = .000006) and visual-motor (P = .00005) outcomes, whereas infection was associated with bilateral FA reductions, which were associated with lower IQ scores (P = .03) and poorer working memory (P = .01) at 8 years.

CONCLUSIONS

This cohort study of children born very preterm suggests that BPD and culture-positive infection are distinctly associated with impaired white-matter development and poor neurodevelopmental outcomes. These findings imply neonatal illnesses impact the brain nonuniformly, suggesting opportunities for targeted intervention.

The association between maternal immune activation and brain structure and function in human offspring: a systematic review

Maternal immune activation (MIA) during pregnancy, as a result of infectious or inflammatory stimuli, has gained increasing attention for its potential role in adverse child neurodevelopment, with studies focusing on associations in children born preterm. This systematic review summarizes research on the link between several types of prenatal MIA and subsequent child structural and/or functional brain development outcomes. We identified 111 neuroimaging studies in five MIA areas: inflammatory biomarkers (n = 13), chorioamnionitis (n = 18), other types of infections (n = 18), human immunodeficiency virus (HIV) (n = 42), and Zika virus (n = 20). Overall, there was large heterogeneity in the type of MIA exposure examined and in study methodology. Most studies had a prospective single cohort design and mainly focused on potential effects on the brain up to one year after birth. The median sample size was 53 participants. Severe infections, i.e., HIV and Zika virus, were associated with various types of cerebral lesions (e.g., microcephaly, atrophy, or periventricular leukomalacia) that were consistently identified across studies. For less severe infections and chronic inflammation, findings were generally inconsistent and mostly included deviations in white matter structure/function. Current findings have been mainly observed in the infants' brain, presenting an opportunity for future studies to investigate whether these associations persist throughout development. Additionally, the inconsistent findings, encompassing both regions of interest and null results, call into question whether prenatal exposure to less severe infections and chronic inflammation exerts a small effect or no effect on child brain development.

Preterm Sex Differences in Neurodevelopment and Brain Development from Early Life to 8 Years of Age

OBJECTIVE

To examine sex differences in neurodevelopmental outcomes and brain development from early life to 8 years in males and females born preterm.

STUDY DESIGN

This was a prospective cohort study of infants born very preterm (24-32 weeks of gestation) and followed to 8 years with standardized measures of neurodevelopment. Brain magnetic resonance imaging scans were performed soon after birth, term-equivalent age, and 8 years. The relationship between sex, severe brain injury, early pain exposure, fractional anisotropy, and neurodevelopmental outcomes were assessed using multivariable generalized estimating equations.

RESULTS

Males (n = 78) and females (n = 66) were similar in clinical risk factors. Male sex was associated with lower cognitive scores (β = -3.8, P = .02) and greater motor impairment (OR, 1.8; P = .04) across time. Male sex was associated with lower superior white matter fractional anisotropy across time (β = -0.01; P = .04). Sex moderated the association between severe brain injury, early pain, and neurodevelopmental outcomes. With severe brain injury, males had lower cognitive scores at 3 years of age (P < .001). With increasing pain, females had lower cognitive scores at 8 years of age (P = .008), and males had greater motor impairment at 4.5 years of age (P = .001) and 8 years of age (P = .05).

CONCLUSIONS

Males born preterm had lower cognitive scores and greater motor impairment compared with females, which may relate to differences in white matter maturation. The association between severe brain injury, early pain exposure, and neurodevelopmental outcomes was moderated by sex, indicating a differential response to early-life adversity in males and females born preterm.

Chronic Inflammation Offers Hints About Viable Therapeutic Targets for Preeclampsia and Potentially Related Offspring Sequelae

The combination of hypertension with systemic inflammation during pregnancy is a hallmark of preeclampsia, but both processes also convey dynamic information about its antecedents and correlates (e.g., fetal growth restriction) and potentially related offspring sequelae. Causal inferences are further complicated by the increasingly frequent overlap of preeclampsia, fetal growth restriction, and multiple indicators of acute and chronic inflammation, with decreased gestational length and its correlates (e.g., social vulnerability). This complexity prompted our group to summarize information from mechanistic studies, integrated with key clinical evidence, to discuss the possibility that sustained or intermittent systemic inflammation-related phenomena offer hints about viable therapeutic targets, not only for the prevention of preeclampsia, but also the neurobehavioral and other developmental deficits that appear to be overrepresented in surviving offspring. Importantly, we feel that carefully designed hypothesis-driven observational studies are necessary if we are to translate the mechanistic evidence into child health benefits, namely because multiple pregnancy disorders might contribute to heightened risks of neuroinflammation, arrested brain development, or dysconnectivity in survivors who exhibit developmental problems later in life.

Change in Volumes and Location of Preterm White Matter Injury over a Period of 15 Years

OBJECTIVE

To evaluate whether white matter injury (WMI) volumes and spatial distribution, which are important predictors of neurodevelopmental outcomes in preterm infants, have changed over a period of 15 years.

STUDY DESIGN

Five hundred and twenty-eight infants born <32 weeks' gestational age from 2 sequential prospective cohorts (cohort 1: 2006 through 2012; cohort 2: 2014 through 2019) underwent early-life (median 32.7 weeks postmenstrual age) and/or term-equivalent-age MRI (median 40.7 weeks postmenstrual age). WMI were manually segmented for quantification of volumes. There were 152 infants with WMI with 74 infants in cohort 1 and 78 in cohort 2. Multivariable linear regression models examined change in WMI volume across cohorts while adjusting for clinical confounders. Lesion maps assessed change in WMI location across cohorts.

RESULTS

There was a decrease in WMI volume in cohort 2 compared with cohort 1 (β = -0.6, 95% CI [-0.8, -0.3], P < .001) with a shift from more central to posterior location of WMI. There was a decrease in clinical illness severity of infants across cohorts.

CONCLUSIONS

We found a decrease in WMI volume and shift to more posterior location in very preterm infants over a period of 15 years. This may potentially reflect more advanced maturation of white matter at the time of injury which may be related to changes in clinical practice over time.

Histological chorioamnionitis and pathological stages on very preterm infant outcomes

AIMS

Histological chorioamnionitis (HCA) is a condition linked to preterm birth and neonatal infection and its relationship with various pathological stages in extremely preterm neonates, and with their associated short- and long-term consequences, remains a subject of research. This study investigated the connection between different pathological stages of HCA and both short-term complications and long-term outcomes in preterm infants born at or before 32 weeks of gestational age.

METHODS

Preterm infants born at ≤ 32 weeks of gestation who underwent placental pathology evaluation and were followed-up at 18-24 months of corrected age were included. Neonates were classified based on their exposure to HCA and were further subdivided into different groups according to maternal inflammatory responses (MIR) and fetal inflammatory responses (FIR) stages. We compared short-term complications during their hospital stay between the HCA-exposed and -unexposed groups and examined the influence of HCA stages on long-term outcomes.

RESULTS

The HCA group exhibited distinct characteristics such as higher rates of premature rupture of membranes > 18 h, reduced amniotic fluid, early-onset sepsis, bronchopulmonary dysplasia and intraventricular haemorrhage (IVH) grades III-IV (P < 0.05). The moderate-severe HCA group displayed lower gestational age, lower birth weight and higher incidence of IVH (grades III-IV) and preterm sepsis compared with the mild HCA group (P < 0.05). After adjusting for confounders, the MIR stages 2-3 group showed associations with cognitive impairment and cerebral palsy (P < 0.05), and the FIR stages 2-3 group also showed poor long-term outcomes and cognitive impairment (P < 0.05).

CONCLUSIONS

Moderate-severe HCA was associated with increased early-onset sepsis, severe IVH and poor long-term outcomes, including cognitive impairment and cerebral palsy. Vigilant prevention strategies are warranted for severe HCA cases in order to mitigate poorer clinical outcomes.

Intrauterine exposure to chorioamnionitis and neuroanatomical alterations at term-equivalent age in preterm infants

PURPOSE

Infants born to mothers with chorioamnionitis (CAM) are at increased risk of developing adverse neurodevelopmental disorders in later life. However, clinical magnetic resonance imaging (MRI) studies examining brain injuries and neuroanatomical alterations attributed to CAM have yielded inconsistent results. We aimed to determine whether exposure to histological CAM in utero leads to brain injuries and alterations in the neuroanatomy of preterm infants using 3.0- Tesla MRI at term-equivalent age.

METHODS

A total of 58 preterm infants born before 34 weeks of gestation at Nagoya University Hospital between 2010 and 2018 were eligible for this study (CAM group, n = 21; non-CAM group, n = 37). Brain injuries and abnormalities were assessed using the Kidokoro Global Brain Abnormality Scoring system. Gray matter, white matter, and subcortical gray matter (thalamus, caudate nucleus, putamen, pallidum, hippocampus, amygdala, and nucleus accumbens) volumes were evaluated using segmentation tools (SPM12 and Infant FreeSurfer).

RESULTS

The Kidokoro scores for each category and severity in the CAM group were comparable to those observed in the non-CAM group. White matter volume was significantly smaller in the CAM group after adjusting for covariates (postmenstrual age at MRI, infant sex, and gestational age) (p = 0.007), whereas gray matter volume was not significantly different. Multiple linear regression analyses revealed significantly smaller volumes in the bilateral pallidums (right, p = 0.045; left, p = 0.038) and nucleus accumbens (right, p = 0.030; left, p = 0.004) after adjusting for covariates.

CONCLUSIONS

Preterm infants born to mothers with histological CAM showed smaller volumes in white matter, pallidum, and nucleus accumbens at term-equivalent age.

Preterm Neurodevelopmental Trajectories from 18 Months to 4.5 Years

OBJECTIVE

To assess the longitudinal trajectory of cognitive, language, and motor outcomes from 18 months to 4.5 years of age in children born very preterm.

STUDY DESIGN

This was a prospective cohort study of 163 infants born very preterm (born 24-32 weeks of gestation) followed longitudinally and assessed with neurodevelopmental scales and magnetic resonance imaging of the brain. Outcomes at 18 months and 3 years were assessed with the Bayley Scales of Infant and Toddler Development, 3rd Edition, and at 4.5 years with the Wechsler Preschool and Primary Scale of Intelligence-III and the Movement Assessment Battery for Children. Cognitive, language, and motor outcomes were categorized as below-average, average, and above-average, and compared across time. Clinical data were analyzed using ANOVA, χ2 tests, and linear regression.

RESULTS

Cognitive and language trajectories were stable from 18 months to 4.5 years for all outcome groups. Motor impairment increased over time, with a greater proportion of children having motor deficits at 4.5 years. Children with below-average cognitive and language outcomes at 4.5 years had more clinical risk factors, greater white matter injury, and lower maternal education. Children with severe motor impairment at 4.5 years were born earlier, had more clinical risk factors, and demonstrated greater white matter injury.

CONCLUSIONS

Children born preterm have stable cognitive and language trajectories, while motor impairment increased at 4.5 years. These results highlight the importance of continued developmental surveillance for children born preterm into preschool age.

A comparison of altered white matter microstructure in youth born with congenital heart disease or born preterm

Introduction

Alterations to white matter microstructure as detected by diffusion tensor imaging have been documented in both individuals born with congenital heart disease (CHD) and individuals born preterm. However, it remains unclear if these disturbances are the consequence of similar underlying microstructural disruptions. This study used multicomponent driven equilibrium single pulse observation of T₁ and T₂ (mcDESPOT) and neurite orientation dispersion and density imaging (NODDI) to characterize and compare alterations to three specific microstructural elements of white matter - myelination, axon density, and axon orientation - in youth born with CHD or born preterm.

Methods

Participants aged 16 to 26 years with operated CHD or born ≤33 weeks gestational age and a group of healthy peers of the same age underwent a brain MRI including mcDESPOT and high angular resolution diffusion imaging acquisitions. Using tractometry, average values of myelin water fraction (MWF), neurite density index (NDI), and orientation dispersion index (ODI) were first calculated and compared between groups for 30 white matter bundles. Afterwards, bundle profiling was performed to further characterize the topology of the detected microstructural alterations.

Results

The CHD and preterm groups both presented with widespread bundles and bundle segments with lower MWF, accompanied by some occurrences of lower NDI, relative to controls. While there were no differences in ODI between the CHD and control groups, the preterm group presented with both higher and lower ODI compared to the control group and lower ODI compared to the CHD group.

Discussion

While youth born with CHD or born preterm both presented with apparent deficits in white matter myelination and axon density, youth born preterm presented with a unique profile of altered axonal organization. Future longitudinal studies should aim to better understand the emergence of these common and distinct microstructural alterations, which could orient the development of novel therapeutic approaches.

Comparison of the Clinical Characteristics of Infants with Punctate White Matter Lesions and/or Cystic Lesions

BACKGROUND

We aimed to investigate the differences in the clinical characteristics of preterm infants with punctate white matter lesions (PWMLs) and those with cystic periventricular leukomalacia (cPVL) using term-equivalent age magnetic resonance imaging.

METHODS

We conducted a retrospective case-control study to explore the clinical characteristics of infants (< 35 weeks gestation, born between 2007 and 2017 in a single Level III perinatal center) with PWML, cPVL or with PWML plus cPVL and compared them with those of gestational-age-matched controls.

RESULTS

Among 602 infants, 29, 5, and 4 were assigned to the PWML group, cPVL group, and PWML plus cPVL group (PWML-cPVL group), respectively. Compared to the control group (n = 87), the PWML group had higher birth weights (p = 0.04), rates of histological chorioamnionitis (p = 0.04), vaginal delivery (p = 0.008), and early heart contraction failure (within 72 hours after birth) (p = 0.003). The cPVL group had lower umbilical blood gas base excess (p = 0.01), higher rate of late-onset circulatory collapse (p = 0.008), and higher hydrocortisone requirements (p = 0.03) than the control group (n = 15). The PWML-cPVL group had a higher rate of intraventricular hemorrhage (p = 0.03) than the control group (n = 12). In the multivariate logistic regression analysis, vaginal delivery (odds ratio [OR] = 3.5; 95% confidence interval [CI] = 1.37-9.40; p = 0.009), higher birth weight (per 1 g) (OR = 1.001; 95% CI = 1.0001-1.002; p = 0.03), and early heart contraction failure (OR = 5.4; 95% CI = 1.84-16.8; p = 0.002), were independent risk factors for PWML.

CONCLUSION

Clinical characteristics of infants with PWML compared with gestational-age-matched controls differed from those with cPVL or PWML plus cPVL, as PWML were not related to severe disruption of hemodynamics.

1H-magnetic resonance spectroscopy and its role in predicting neurodevelopmental impairment in preterm neonates: A systematic review

To assess the diagnostic utility of proton (1H) magnetic resonance spectroscopy in early diagnosis of neurodevelopmental impairment in preterm newborns. Systematic review performed in compliance with the PRISMA statements. Eligible articles were searched in MEDLINE, Scopus, and ISI Web of Science databases using the following medical subject headings and terms: "magnetic resonance spectroscopy," "infant," and "newborn." Studies of any design published until 20 December 2021 and fulfilling the following criteria were selected: (1) studies including newborns with gestational age at birth <37 weeks which underwent at least one 1H-MRS scan within 52 weeks' postmenstrual age and neurodevelopmental assessment within 4 years of age; (2) studies in which preterm newborns with congenital infections, genetic disorders, and brain congenital anomalies were clearly excluded. Data regarding the relationship between metabolite ratios in basal ganglia, thalamus, and white matter, and neurodevelopment were analysed. The quality assessment of included studies was performed according to the criteria from the QUADAS-2. N-acetylaspartate (NAA)/choline (Cho) was the most studied metabolite ratio. Lower NAA/Cho ratio in basal ganglia and thalamus was associated with adverse motor, cognitive, and language outcomes, and worse global neurodevelopment. Lower NAA/Cho ratio in white matter was associated with cognitive impairment. However, some associations came from single studies or were discordant among studies. The quality of included studies was low. 1H-MRS could be a promising tool for early diagnosis of neurodevelopmental impairment. However, further studies of good quality are needed to define the relationship between metabolite ratios and neurodevelopment.

Acute histologic chorioamnionitis independently and directly increases the risk for brain abnormalities seen on magnetic resonance imaging in very preterm infants

BACKGROUND

The independent risk for neurodevelopmental impairments attributed to chorioamnionitis in premature infants remains controversial. Delayed brain maturation or injury identified on magnetic resonance imaging at term-equivalent age can be used as a surrogate measure of neurodevelopmental impairments that is less confounded by postdelivery neonatal intensive care unit environmental factors to investigate this relationship more clearly.

OBJECTIVE

This study aimed to determine whether preterm infants born with moderate to severe acute histologic chorioamnionitis would have a higher magnetic resonance imaging-determined global brain abnormality score, independent of early premature birth, when compared with preterm infants with no or mild chorioamnionitis.

STUDY DESIGN

This was a prospective, multicenter cohort study involving infants born very prematurely ≤32 weeks' gestational age with acute moderate to severe histologic chorioamnionitis, graded using standard histologic criteria. Brain abnormalities were diagnosed and scored using a well-characterized, standardized scoring system captured using a high-resolution 3 Tesla magnetic resonance imaging research magnet. In secondary analyses, total brain volume and 4 magnetic resonance imaging metrics of cortical maturation (cortical surface area, sulcal depth, gyral index, and inner cortical curvature) were calculated using an automated algorithm and correlated with chorioamnionitis. The association of funisitis (any grade) with brain abnormalities was also explored. We investigated if premature birth mediated the relationship between histologic chorioamnionitis and brain abnormality score using mediation analysis.

RESULTS

Of 353 very preterm infants, 297 infants had mild or no chorioamnionitis (controls), and 56 were diagnosed with moderate to severe acute histologic chorioamnionitis. The primary outcome brain abnormality score was significantly higher in histologic chorioamnionitis-exposed infants than in the controls (median, 4 vs 7; P<.001). Infants with acute histologic chorioamnionitis had significantly lower brain tissue volume (P=.03) and sulcal depth (P=.04), whereas other morphometric indices did not differ statistically. In the multiple regression analysis, we observed persistent significant relationships between moderate to severe acute histologic chorioamnionitis and brain abnormality scores (β=2.84; 1.51-4.16; P<.001), total brain volume (P=.03), and sulcal depth (P=.02). Funisitis was also significantly associated with brain abnormality score after adjustment for clinical confounders (P=.005). Mediation analyses demonstrated that 50% of brain abnormalities was an indirect consequence of premature birth, and the remaining 50% was a direct effect of moderate to severe acute histologic chorioamnionitis when compared with preterm infants with no or mild chorioamnionitis exposure. Examining gestational age as a mediator, funisitis did not exert a significant direct effect on brain abnormalities after the significant indirect effects of preterm birth were accounted for.

CONCLUSION

Acute histologic chorioamnionitis increases the risk for brain injury and delayed maturation, both directly and indirectly, by inducing premature birth.

Ventricular Volume in Infants Born Very Preterm: Relationship with Brain Maturation and Neurodevelopment at Age 4.5 Years

OBJECTIVE

To evaluate the relationship of quantitative ventricular volume with brain maturation and neurodevelopmental outcomes at age 4.5 years in children born very preterm.

STUDY DESIGN

T1-weighted imaging, diffusion tensor imaging, and magnetic resonance spectroscopy were performed shortly after birth (n = 212) and at term-equivalent age (TEA) (n = 194). Intraventricular hemorrhage (IVH) grade and white matter injury (WMI) volume were measured on early T1-weighted magnetic resonance imaging (MRI) scans. Total cerebral volume and ventricular volume were quantified using the Multiple Automatically Generated Templates-Brain pipeline. At age 4.5 years, 178 children (84%) underwent cognitive and motor assessments. Multivariable linear regression was used to examine the relationships between ventricular volume and neurodevelopmental outcomes. Generalized estimating equations were used to account for repeated measures when analyzing neonatal MRI data. All models accounted for sex, postmenstrual age at scan, WMI volume, IVH grade, and total cerebral volume and were corrected for multiple comparisons.

RESULTS

On early MRI, 97 infants had IVH (grade 1, n = 22; grade 2, n = 66; grade 3, n = 9), and 68 had WMI (median, 44 mm³; IQR, 21-296 mm³). IQ at 4.5 years was associated with MRI ventricular volume at the early (β = -0.64; P < .001) and TEA (β = -0.44, P < .001) time points. Motor outcomes were associated with ventricular volume at TEA (β = -0.84, P = .01). Greater ventricular volume independently predicted lower fractional anisotropy in corpus callosum (genu: β = -0.0008, P = .002; splenium: β = -0.003, P < .001) and optic radiations (β = -0.001, P = .004); ventricular volume did not predict the N-acetylaspartate/choline ratio.

CONCLUSIONS

In children born very preterm, neonatal ventricular size was associated with 4.5-year neurodevelopmental outcomes. Our findings suggest that white matter maturation may be abnormal in the setting of enlarged ventricular size beyond that expected from concurrent brain injuries.

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.

The dimensions of white matter injury in preterm neonates

White matter injury (WMI) represents a frequent form of parenchymal brain injury in preterm neonates. Several dimensions of WMI are recognized, with distinct neuropathologic features involving a combination of destructive and maturational anomalies. Hypoxia-ischemia is the main mechanism leading to WMI and adverse white matter development, which result from injury to the oligodendrocyte precursor cells. Inflammation might act as a potentiator for WMI. A combination of hypoxia-ischemia and inflammation is frequent in several neonatal comorbidities such as postnatal infections, NEC and bronchopulmonary dysplasia, all known contributors to WMI. White matter injury is an important predictor of adverse neurodevelopmental outcomes. When WMI is detected on neonatal brain imaging, a detailed characterization of the injury (pattern of injury, severity and location) may enhance the ability to predict outcomes. This clinically-oriented review will provide an overview of the pathophysiology and imaging diagnosis of the multiple dimensions of WMI, will explore the association between postnatal complications and WMI, and will provide guidance on the signification of white matter anomalies for motor and cognitive development.

Risk Factors for Periventricular Leukomalacia in Preterm Infants: A Systematic Review, Meta-analysis, and GRADE-Based Assessment of Certainty of Evidence

BACKGROUND

We analyzed the certainty of evidence (CoE) for risk factors of periventricular leukomalacia (PVL) in preterm neonates, a common morbidity of prematurity.

METHODS

Medline, CENTRAL, Embase, and CINAHL were searched. Cohort and case-control studies and randomised randomized controlled trials were included. Data extraction was performed in duplicate. A random random-effects meta-analysis was utilizedused. CoE was evaluated as per Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines.

RESULTS

One hundred eighty-six studies evaluating 95 risk factors for PVL were included. Of the 2,509,507 neonates assessed, 16,569 were diagnosed with PVL. Intraventricular hemorrhage [adjusted odds ratio: 3.22 (2.52-4.12)] had moderate CoE for its association with PVL. Other factors such as hypocarbia, chorioamnionitis, PPROM >48 hour, multifetal pregnancy reduction, antenatal indomethacin, lack of antenatal steroids, perinatal asphyxia, ventilation, shock/hypotension, patent ductus arteriosus requiring surgical ligation, late-onset circulatory collapse, sepsis, necrotizing enterocolitis, and neonatal surgery showed significant association with PVL after adjustment for confounders (CoE: very low to low). Amongst the risk factors associated with mother placental fetal (MPF) triad, there was paucity of literature related to genetic predisposition and defective placentation. Sensitivity analysis revealed that the strength of association between invasive ventilation and PVL decreased over time (P < 0.01), suggesting progress in ventilation strategies. Limited studies had evaluated diffuse PVL.

CONCLUSION

Despite decades of research, our findings indicate that the CoE is low to very low for most of the commonly attributed risk factors of PVL. Future studies should evaluate genetic predisposition and defective placentation in the MPF triad contributing to PVL. Studies evaluating exclusively diffuse PVL are warranted.

Maternal Immune Activation Hypotheses for Human Neurodevelopment: Some Outstanding Questions

The Maternal Immune Activation (MIA) hypothesis is a leading model for understanding prenatal influences on individual differences in, and clinical syndromes of, neurodevelopment. Experimental animal and human research has proliferated in recent years, and there is now a sizable research base. Several meta-analyses demonstrate general support for an association between prenatal immune activation and neurodevelopment in human research. However, questions remain about the nature of the immune activation, the network of underlying mechanisms involved, and the breadth of impact across behavioral phenotypes. Complementing recent reviews of results, the current review places particular emphasis on how advances in understanding mechanisms may be improved with greater attention to addressing the methodological variation and limitations of existing studies, and identifies areas for further clinical research.

Hyperglycemia associated with acute brain injury in neonatal encephalopathy

OBJECTIVE

To identify how alterations in glucose levels are associated with regional brain injury in neonatal encephalopathy.

METHODS

This was a prospective cohort study of 102 newborns with neonatal encephalopathy, with continuous glucose monitoring for 72 h. 97 (95%) completed 72 h of therapeutic hypothermia. Brain imaging around day 5 of life included diffusion tensor imaging and MR spectroscopy. Regions of interest were placed for both DTI and MR spectroscopy, and tractography of the optic radiation and corticospinal tract were evaluated. Linear regression models related each MR metric with minimum and maximum glucose values during each day of life, adjusting for 5-minute Apgar scores and umbilical artery pH.

RESULTS

Higher maximum glucose levels on the first day of life were associated with widespread changes in mean diffusivity in the anterior and posterior white matter, splenium of the corpus callosum, lentiform nucleus, pulvinar nucleus of the thalamus, posterior limb of the internal capsule, and optic radiations, thus including regions traditionally associated with hypoxia-ischemia or hypoglycemia. No associations were found between lower minimum glucose levels and DTI changes in any regions tested, or between glucose levels and MR spectroscopy.

CONCLUSIONS

In this cohort of neonatal encephalopathy with therapeutic hypothermia, higher maximal glucose on the first day of life was associated with widespread microstructural changes, but lower minimum glucose levels were not associated with changes in any of the regions tested. Long-term follow-up will determine if imaging findings translate to long-term outcomes.

Longitudinal neurodevelopmental outcomes in preterm twins

BACKGROUND

Several factors contribute to neurodevelopmental outcomes in preterm infants. The aim of this study was to examine the genetic and environmental influences on long-term outcomes in preterm twins.

METHODS

From a prospective cohort of 225 preterm neonates studied with MRI, 24 monozygotic and 52 dizygotic twins were included. Neurodevelopmental outcomes at 1.5 and 3 years were assessed with the Bayley-III and at 4.5 years with The Movement Assessment Battery for Children and The Wechsler Preschool and Primary Scale of Intelligence-III.

RESULTS

Preterm monozygotic and dizygotic twin pairs (N = 76 neonates) had similar neurodevelopmental outcomes at all time points. Monozygotic twins (N = 24) did not show greater agreement for outcomes relative to dizygotic twins (N = 52). Twin pairs who were discordant in development (N = 12) were born at a lower gestational age and had a higher incidence of bronchopulmonary dysplasia and retinopathy of prematurity. Discordant twins become more similar in cognitive and language outcomes over time.

CONCLUSIONS

Neurodevelopmental outcomes in preterm twins may relate more strongly to environmental factors than genetics. Discordant twins were born earlier and had more perinatal morbidities. Despite the initial discordance, these twin pairs become similar in outcomes over time, which may reflect the positive impact of home environment or early intervention programs.

IMPACT

Neurodevelopmental outcomes in preterm twins relate more strongly to environmental factors than genetics. Monozygotic twins did not show greater agreement in outcomes relative to dizygotic twins suggesting a stronger environmental, rather than genetic, influence on development. Twin pairs who were discordant in development were born at a lower gestational age and had a higher incidence of perinatal morbidities. Despite the initial discordance, these twin pairs become more similar in cognitive and language outcomes over time, which may reflect the positive impact of early intervention programs or home environment. Neurodevelopmental outcomes in preterm twins are influenced by exposure to early-life insults or environmental stressors. The initial variability in outcomes among preterm infants is not fixed, and efforts made post-discharge from the neonatal intensive care unit can have a substantial impact on long-term outcomes.

Interaction between Preterm White Matter Injury and Childhood Thalamic Growth

OBJECTIVE

The purpose of this study was to determine how preterm white matter injury (WMI) and long-term thalamic growth interact to predict 8-year neurodevelopmental outcomes.

METHODS

A prospective cohort of 114 children born at 24 to 32 weeks' gestational age (GA) underwent structural and diffusion tensor magnetic resonance imaging early in life (median 32 weeks), at term-equivalent age and at 8 years. Manual segmentation of neonatal WMI was performed on T1-weighted images and thalamic volumes were obtained using the MAGeT brain segmentation pipeline. Cognitive, motor, and visual-motor outcomes were evaluated at 8 years of age. Multivariable regression was used to examine the relationship among neonatal WMI volume, school-age thalamic volume, and neurodevelopmental outcomes.

RESULTS

School-age thalamic volumes were predicted by neonatal thalamic growth rate, GA, sex, and neonatal WMI volume (p < 0.0001). After accounting for total cerebral volume, WMI volume remained associated with school-age thalamic volume (β = -0.31, p = 0.005). In thalamocortical tracts, fractional anisotropy (FA) at term-equivalent age interacted with early WMI volume to predict school-age thalamic volumes (all p < 0.02). School-age thalamic volumes and neonatal WMI interacted to predict full-scale IQ (p = 0.002) and adverse motor scores among those with significant WMI (p = 0.01). Visual-motor scores were predicted by thalamic volumes (p = 0.04).

INTERPRETATION

In very preterm-born children, neonatal thalamic growth and WMI volume predict school-age thalamic volumes. The emergence at term of an interaction between FA and WMI to impact school-age thalamic volume indicates dysmaturation as a mechanism of thalamic growth failure. Cognition is predicted by the interaction of WMI and thalamic growth, highlighting the need to consider multiple dimensions of brain injury in these children. ANN NEUROL 2021;90:584-594.

Recurrent neonatal sepsis and progressive white matter injury in a premature newborn culture-positive for group B Streptococcus: A case report

RATIONALE

Group B Streptococcus (GBS) remains a principal pathogen causing neonatal sepsis and meningitis, particularly in premature infants with relatively insufficient immunity. Recurrence may occur uncommonly, largely associated with subclinical mucosal persistence or repetitive exposure to exogenous sources. White matter injury (WMI) including cystic periventricular leukomalacia (PVL) has been associated with intrauterine infection/inflammation, and neonatal infection as a more significant predictor including postnatal sepsis and recurrent infection, even without microbial neuroinvasion. Furthermore, clinical and experimental evidence of WMI by some bacteria other than GBS without central nervous system invasion has been reported. However, there is little evidence of WMI associated with neonatal GBS sepsis in the absence of meningitis in the literature.

PATIENT CONCERNS

A newborn at 30+4 weeks' gestation with low birthweight presented with 2 episodes (with a 13-day interval with no antibiotic therapy) of neonatal sepsis culture-proven for GBS with early-onset presentation after clinical chorioamnionitis via vertical GBS transmission and the associated conditions including prematurity-related neonatal immunodeficiency and persistent mucosal GBS carriage after the first antibiotic treatment. The perinatal GBS infection was complicated by progressive WMI presenting with ventriculomegaly and cystic PVL without a definite evidence of meningitis, intraventricular hemorrhage, and documented cerebral hypoxia or hypoperfusion conditions including septic shock.

DIAGNOSES

Recurrent group B streptococcal sepsis and cystic PVL with ventriculomegaly.

INTERVENTIONS

Two episodes of GBS sepsis were treated with 15-day parenteral antibiotic therapy, respectively.

OUTCOMES

Resolution of the recurrent GBS sepsis without further relapses, however, complicated by WMI and subsequent about 6 months delay in motor development at 12 months' corrected age.

LESSONS

This case suggests WMI associated with GBS bacteremia without central nervous system entry by viable GBS and also shows that in premature infants, intrauterine GBS infection with no interventions may lead to extensive and persistent GBS colonization, early-onset and recurrent GBS disease, and WMI. Postnatal as well as intrauterine infection/inflammation controls with maternal prophylaxis may be pivotal for prevention and limiting the magnitude of neurologic injury.

Anti-Inflammatory Therapies for Treatment of Inflammation-Related Preterm Brain Injury

Despite the prevalence of preterm brain injury, there are no established neuroprotective strategies to prevent or alleviate mild-to-moderate inflammation-related brain injury. Perinatal infection and inflammation have been shown to trigger acute neuroinflammation, including proinflammatory cytokine release and gliosis, which are associated with acute and chronic disturbances in brain cell survival and maturation. These findings suggest the hypothesis that the inhibition of peripheral immune responses following infection or nonspecific inflammation may be a therapeutic strategy to reduce the associated brain injury and neurobehavioral deficits. This review provides an overview of the neonatal immunity, neuroinflammation, and mechanisms of inflammation-related brain injury in preterm infants and explores the safety and efficacy of anti-inflammatory agents as potentially neurotherapeutics.

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

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

Association of early skin breaks and neonatal thalamic maturation: A modifiable risk?

OBJECTIVE

To test the hypothesis that a strategy of prolonged arterial line (AL) and central venous line (CVL) use is associated with reduced neonatal invasive procedures and improved growth of the thalamus in extremely preterm neonates (<28 weeks' gestation).

METHODS

Two international cohorts of very preterm neonates (n = 143) with prolonged (≥14 days) or restricted (<14 days) use of AL/CVL were scanned serially with MRI. General linear models were used to determine the association between skin breaks and thalamic volumes, accounting for clinical confounders and site differences. Children were assessed at preschool age on standardized tests of motor and cognitive function. Outcome scores were assessed in relation to neonatal thalamic growth.

RESULTS

Prolonged AL/CVL use in neonates (n = 86) was associated with fewer skin breaks (median 34) during the hospital stay compared to restricted AL/CVL use (n = 57, median 91, 95% confidence interval [CI] 60.35-84.89). Neonates with prolonged AL/CVL use with fewer skin breaks had significantly larger thalamic volumes early in life compared to neonates with restricted line use (B = 121.8, p = 0.001, 95% CI 48.48-195.11). Neonatal thalamic growth predicted preschool-age cognitive (B = 0.001, 95% CI 0.0003-0.001, p = 0.002) and motor scores (B = 0.01, 95% CI 0.001-0.10, p = 0.02). Prolonged AL/CVL use was not associated with greater incidence of sepsis or multiple infections.

CONCLUSIONS

Prolonged AL/CVL use in preterm neonates may provide an unprecedented opportunity to reduce invasive procedures in preterm neonates. Pain reduction in very preterm neonates is associated with optimal thalamic growth and neurodevelopment.

Mechanical Ventilation Duration, Brainstem Development, and Neurodevelopment in Children Born Preterm: A Prospective Cohort Study

OBJECTIVES

To determine, in children born preterm, the association of mechanical ventilation duration with brainstem development, white matter maturation, and neurodevelopmental outcomes at preschool age.

STUDY DESIGN

This prospective cohort study included 144 neonates born at <30 weeks of gestation (75 male, mean gestational age 27.1 weeks, SD 1.6) with regional brainstem volumes automatically segmented on magnetic resonance imaging at term-equivalent age (TEA). The white matter maturation was assessed by diffusion tensor imaging and tract-based spatial statistics. Neurodevelopmental outcomes were assessed at 4.5 years of age using the Movement Assessment Battery for Children, 2nd Edition, and the Wechsler Primary and Preschool Scale of Intelligence, 4th Edition, full-scale IQ. The association between the duration of mechanical ventilation and brainstem development was validated in an independent cohort of children born very preterm.

RESULTS

Each additional day of mechanical ventilation predicted lower motor scores (0.5-point decrease in the Movement Assessment Battery for Children, 2nd Edition, score by day of mechanical ventilation, 95% CI -0.6 to -0.3, P < .0001). Prolonged exposure to mechanical ventilation was associated with smaller pons and medulla volumes at TEA in 2 independent cohorts, along with widespread abnormalities in white matter maturation. Pons and medulla volumes at TEA predicted motor outcomes at 4.5 years of age.

CONCLUSIONS

In neonates born very preterm, prolonged mechanical ventilation is associated with impaired brainstem development, abnormal white matter maturation, and lower motor scores at preschool age. Further research is needed to better understand the neural pathological mechanisms involved.

Age-related changes in cerebral congenital toxoplasmosis: Histopathological and immunohistochemical evaluation

Congenital toxoplasmosis is a widespread worldwide disease producing varying degrees of damage to the fetus including ocular and neurological impairment. However, the underlying mechanisms are not yet clear. Therefore, the current study aimed to investigate the progress of congenital cerebral toxoplasmosis in experimentally infected offspring animal model at different age groups till become adults. To fulfill this aim, the offspring of Me49 T. gondii infected pregnant mice were divided into groups; embryo, infant, young and adult phases. Blood and brain samples were collected for further hormonal and histopathological studies and immunohistochemical staining of glial fibrillary acidic protein (GFAP) and synaptophysin (SYN). Our results showed several encephalitic changes in the infected groups ranging from gliosis to reduced cortical cell number and fibrinoid degeneration of the brain. We showed increased expression of GFAP and SYN indicating activation of astrocytes and modification of the synaptic function, respectively. These changes started intrauterine following congenital infection and increased progressively afterward. Moreover, infected mice had elevated corticosterone levels. In conclusion, the current study provided new evidences for the cellular changes especially in the infected embryo and highlighted the role of GFAP and SYN that may be used as indicators for T. gondii-related neuropathy.

Neuroprotection Care Bundle Implementation to Decrease Acute Brain Injury in Preterm Infants

BACKGROUND

We assessed the impact of an evidence-based neuroprotection care bundle on the risk of brain injury in extremely preterm infants.

METHODS

We implemented a neuroprotection care bundle consisting of a combination of neuroprotection interventions such as minimal handling, midline head position, deferred cord clamping, and protocolization of hemodynamic and respiratory managements. These interventions targeted risk factors for acute brain injury in extremely preterm infants (born at gestational age less than 29 weeks) during the first three days of birth. Implementation occurred in a stepwise manner, including care bundle development by a multidisciplinary care team based on previous evidence and experience, standardization of outcome assessment tools, and education. We compared the incidence of the composite outcome of acute preterm brain injury or death preimplementation and postimplementation.

RESULTS

Neuroprotection care bundle implementation associated with a significant reduction in acute brain injury risk factors such as the use of inotropes (24% before, 7% after, P value < 0.001) and fluid boluses (37% before, 19% after, P value < 0.001), pneumothorax (5% before, 2% after, P value = 0.002), and opioid use (19% before, 7% after, P value < 0.001). Adjusting for confounding factors, the neuroprotection care bundle significantly reduced death or severe brain injury (adjusted odds ratio, 0.34; 95% confidence interval, 0.20 to 0.59; P value < 0.001) and severe brain injury (adjusted odds ratio, 0.31; 95% confidence interval, 0.17 to 0.58; P < 0.001).

CONCLUSIONS

Implementation of neuroprotection care bundle targeting predefined risk factors is feasible and effective in reducing acute brain injury in extremely preterm infants.

Socioeconomic status and brain injury in children born preterm: modifying neurodevelopmental outcome

Improved intensive care therapies have increased the survival of children born preterm. Yet, many preterm children experience long-term neurodevelopmental sequelae. Indeed, preterm birth remains a leading cause of lifelong neurodevelopmental disability globally, posing significant challenges to the child, family, and society. Neurodevelopmental disability in children born preterm is traditionally linked to acquired brain injuries such as white matter injury and to impaired brain maturation resulting from neonatal illness such as chronic lung disease. Socioeconomic status (SES) has long been recognized to contribute to variation in outcome in children born preterm. Recent brain imaging data in normative term-born cohorts suggest that lower SES itself predicts alterations in brain development, including the growth of the cerebral cortex and subcortical structures. Recent evidence in children born preterm suggests that the response to early-life brain injuries is modified by the socioeconomic circumstances of children and families. Exciting new data points to the potential of more favorable SES circumstances to mitigate the impact of neonatal brain injury. This review addresses emerging evidence suggesting that SES modifies the relationship between early-life exposures, brain injury, and neurodevelopmental outcomes in children born preterm. Better understanding these relationships opens new avenues for research with the ultimate goal of promoting optimal outcomes for those children born preterm at highest risk of neurodevelopmental consequence.

Predicting developmental outcomes in preterm infants: A simple white matter injury imaging rule

OBJECTIVE

To develop a simple imaging rule to predict neurodevelopmental outcomes at 4.5 years in a cohort of preterm neonates with white matter injury (WMI) based on lesion location and examine whether clinical variables enhance prediction.

METHODS

Sixty-eight preterm neonates born 24-32 weeks' gestation (median 27.7 weeks) were diagnosed with WMI on early brain MRI scans (median 32.3 weeks). 3D T1-weighted images of 60 neonates with 4.5-year outcomes were reformatted and aligned to the posterior commissure-eye plane and WMI was classified by location: anterior or posterior-only to the midventricle line on the reformatted axial plane. Adverse outcomes at 4.5 years were defined as Wechsler Preschool and Primary Scale of Intelligence full-scale IQ <85, cerebral palsy, or Movement Assessment Battery for Children, second edition percentile <5. The prediction of adverse outcome by WMI location, intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), and retinopathy of prematurity (ROP) was assessed using multivariable logistic regression.

RESULTS

Six children had adverse cognitive outcomes and 17 had adverse motor outcomes. WMI location predicted cognitive outcomes in 90% (area under receiver operating characteristic curve [AUC] 0.80) and motor outcomes in 85% (AUC 0.75). Adding IVH, BPD, and ROP to the model enhances the predictive strength for cognitive and motor outcomes (AUC 0.83 and 0.88, respectively). Rule performance was confirmed in an independent cohort of children with WMI.

CONCLUSIONS

WMI on early MRI can be classified by location to predict preschool age outcomes in children born preterm. The predictive value of this WMI classification is enhanced by considering clinical factors apparent by term-equivalent age.

Neuroprotection from acute brain injury in preterm infants

Infants born at ≤32+6 weeks gestation are at higher risk for intracranial ischemic and hemorrhagic injuries, which often occur in the first 72 hours postbirth. Antenatal strategies to reduce the incidence of acute brain injuries include administering maternal corticosteroids and prompt antibiotic treatment for chorioamnionitis. Perinatal strategies include delivery within a tertiary centre, delayed cord clamping, and preventing hypothermia. Postnatal strategies include empiric treatment with antibiotics when chorioamnionitis is suspected, the cautious use of inotropes, the avoidance of blood PCO2 fluctuation, and neutral head positioning. Clinicians should be aware of the policies and procedures that, especially when combined, can provide neuroprotection for preterm infants.

Association of Socioeconomic Status and Brain Injury With Neurodevelopmental Outcomes of Very Preterm Children

IMPORTANCE

Studies of socioeconomic status and neurodevelopmental outcome in very preterm neonates have not sensitively accounted for brain injury.

OBJECTIVE

To determine the association of brain injury and maternal education with motor and cognitive outcomes at age 4.5 years in very preterm neonates.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of preterm neonates (24-32 weeks' gestation) recruited August 16, 2006, to September 9, 2013, at British Columbia Women's Hospital in Vancouver, Canada. Analysis of 4.5-year outcome was performed in 2018.

MAIN OUTCOMES AND MEASURES

At age 4.5 years, full-scale IQ assessed using the Wechsler Primary and Preschool Scale of Intelligence, Fourth Edition, and motor outcome by the percentile score on the Movement Assessment Battery for Children, Second Edition.

RESULTS

Of 226 survivors, neurodevelopmental outcome was assessed in 170 (80 [47.1%] female). Based on the best model to assess full-scale IQ accounting for gestational age, standardized β coefficients demonstrated the effect size of maternal education (standardized β = 0.21) was similar to that of white matter injury volume (standardized β = 0.23) and intraventricular hemorrhage (standardized β = 0.23). The observed and predicted cognitive scores in preterm children born to mothers with postgraduate education did not differ in those with and without brain injury. The best-performing model to assess for motor outcome accounting for gestational age included being small for gestational age, severe intraventricular hemorrhage, white matter injury volume, and chronic lung disease.

CONCLUSIONS AND RELEVANCE

At preschool age, cognitive outcome was comparably associated with maternal education and neonatal brain injury. The association of brain injury with poorer cognition was attenuated in children born to mothers of higher education level, suggesting opportunities to promote optimal outcomes.

The optimal choices of animal models of white matter injury

White matter injury, the most common neurological injury in preterm infants, is a major cause of chronic neurological morbidity, including cerebral palsy. Although there has been great progress in the study of the mechanism of white matter injury in newborn infants, its pathogenesis is not entirely clear, and further treatment approaches are required. Animal models are the basis of study in pathogenesis, treatment, and prognosis of white matter injury in preterm infants. Various species have been used to establish white matter injury models, including rodents, rabbits, sheep, and non-human primates. Small animal models allow cost-effective investigation of molecular and cellular mechanisms, while large animal models are particularly attractive for pathophysiological and clinical-translational studies. This review focuses on the features of commonly used white matter injury animal models, including their modelling methods, advantages, and limitations, and addresses some clinically relevant animal models that allow reproduction of the insults associated with clinical conditions that contribute to white matter injury in human infants.

Fixel-based analysis of the preterm brain: Disentangling bundle-specific white matter microstructural and macrostructural changes in relation to clinical risk factors

Diffusion MRI (dMRI) studies using the tensor model have identified abnormal white matter development associated with perinatal risk factors in preterm infants studied at term equivalent age (TEA). However, this model is an oversimplification of the underlying neuroanatomy. Fixel-based analysis (FBA) is a novel quantitative framework, which identifies microstructural and macrostructural changes in individual fibre populations within voxels containing crossing fibres. The aim of this study was to apply FBA to investigate the relationship between fixel-based measures of apparent fibre density (FD), fibre bundle cross-section (FC), and fibre density and cross-section (FDC) and perinatal risk factors in preterm infants at TEA. We studied 50 infants (28 male) born at 24.0-32.9 (median 30.4) weeks gestational age (GA) and imaged at 38.6-47.1 (median 42.1) weeks postmenstrual age (PMA). dMRI data were acquired in non-collinear directions with b-value 2500 s/mm2 on a 3 Tesla system sited on the neonatal intensive care unit. FBA was performed to assess the relationship between FD, FC, FDC and PMA at scan, GA at birth, days on mechanical ventilation, days on total parenteral nutrition (TPN), birthweight z-score, and sex. FBA reveals fibre population-specific alterations in FD, FC and FDC associated with clinical risk factors. FD was positively correlated with GA at birth and was negatively correlated with number of days requiring ventilation. FC was positively correlated with GA at birth, birthweight z-scores and was higher in males. FC was negatively correlated with number of days on ventilation and days on TPN. FDC was positively correlated with GA at birth and birthweight z-scores, negatively correlated with days on ventilation and days on TPN and higher in males. We demonstrate that these relationships are fibre-specific even within regions of crossing fibres. These results show that aberrant white matter development involves both microstructural changes and macrostructural alterations.

A population-based study of cystic white matter injury on ultrasound in very preterm infants born over two decades in Nova Scotia, Canada

OBJECTIVE

To identify the temporal trends, risk factors and outcomes of cystic white matter injury (WMI) detected by ultrasound in a population-based cohort of very preterm infants (VPI) with a minimal risk of selection bias.

STUDY DESIGN

All live-born VPIs between 22 and < 31 weeks gestational age born in Nova Scotia, Canada from 1993 to 2013.

RESULTS

Cystic WMI was identified in 87 (7%) out of 1184 eligible infants. The gestational age and mortality adjusted prevalence of cystic WMI decreased over time (p = 0.04). In multivariable analysis, chorioamnionitis, antenatal steroids, admission hypothermia, ventilator support, inotropes, and non-Coagulase-negative Staphylococcal and fungal infections were independently associated with cystic WMI. Cerebral palsy was the most common disability in the survivors, however, half of the survivors had none or mild disability.

CONCLUSIONS

This cohort study demonstrated a decreasing trend in the incidence of cystic WMI and reported population-based neurological outcomes with cystic WMI, which is important for health-care planning and parental counseling.

Preterm brain Injury: White matter injury

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

White matter injury predicts disrupted functional connectivity and microstructure in very preterm born neonates

Objective

To determine whether the spatial extent and location of early-identified punctate white matter injury (WMI) is associated with regionally-specific disruptions in thalamocortical-connectivity in very-preterm born neonates.

Methods

37 very-preterm born neonates (median gestational age: 28.1 weeks; interquartile range [IQR]: 27–30) underwent early MRI (median age 32.9 weeks; IQR: 32–35), and WMI was identified in 13 (35%) neonates. Structural T1-weighted, resting-state functional Magnetic Resonance Imaging (rs-fMRI, n = 34) and Diffusion Tensor Imaging (DTI, n = 31) sequences were acquired using 3 T-MRI. A probabilistic map of WMI was developed for the 13 neonates demonstrating brain injury. A neonatal atlas was applied to the WMI maps, rs-fMRI and DTI analyses to extract volumetric, functional and microstructural data from regionally-specific brain areas. Associations of thalamocortical-network strength and alterations in fractional anisotropy (FA, a measure of white-matter microstructure) with WMI volume were assessed in general linear models, adjusting for age at scan and cerebral volumes.

Results

WMI volume in the superior (β = −0.007; p = .02) and posterior corona radiata (β = −0.01; p = .01), posterior thalamic radiations (β = −0.01; p = .005) and superior longitudinal fasciculus (β = −0.02; p = .001) was associated with reduced connectivity strength between thalamus and parietal resting-state networks. WMI volume in the left (β = −0.02; p = .02) and right superior corona radiata (β = −0.03; p = .008), left posterior corona radiata (β = −0.03; p = .01), corpus callosum (β = −0.11; p < .0001) and right superior longitudinal fasciculus (β = −0.02; p = .02) was associated with functional connectivity strength between thalamic and sensorimotor networks. Increased WMI volume was also associated with decreased FA values in the corpus callosum (β = −0.004, p = .015).

Conclusions

Regionally-specific alterations in early functional and structural network complexity resulting from WMI may underlie impaired outcomes.

•

Lesions in white matter pathways predicted altered functional connectivity.

•

White matter lesions predicted alterations in white matter microstructure.

•

Findings of lesion location and size were regionally-specific.

•

White matter lesion size and location may underlie later delays in development.

A fast segmentation-free fully automated approach to white matter injury detection in preterm infants

White matter injury (WMI) is the most prevalent brain injury in the preterm neonate leading to developmental deficits. However, detecting WMI in magnetic resonance (MR) images of preterm neonate brains using traditional WM segmentation-based methods is difficult mainly due to lack of reliable preterm neonate brain atlases to guide segmentation. Hence, we propose a segmentation-free, fast, unsupervised, atlas-free WMI detection method. We detect the ventricles as blobs using a fast linear maximally stable extremal regions algorithm. A reference contour equidistant from the blobs and the brain-background boundary is used to identify tissue adjacent to the blobs. Assuming normal distribution of the gray-value intensity of this tissue, the outlier intensities in the entire brain region are identified as potential WMI candidates. Thereafter, false positives are discriminated using appropriate heuristics. Experiments using an expert-annotated dataset show that the proposed method runs 20 times faster than our earlier work which relied on time-consuming segmentation of the WM region, without compromising WMI detection accuracy. Graphical Abstract Key Steps of Segmentation-free WMI Detection.

Recent advances in preclinical and clinical multimodal MR in the newborn brain

Aside from injury identification, MRI of the newborn brain has given us insight into cortical and white matter development, identified windows of vulnerabilities, enabled the introduction of therapeutic hypothermia which has become the standard of care in neonatal asphyxia, and is fostering leapfrogging discoveries in the field of neuro-genetics. This article reviews the main advances in recent years in newborn brain imaging both in preclinical and clinical research.

Association of Histologic Chorioamnionitis With Perinatal Brain Injury and Early Childhood Neurodevelopmental Outcomes Among Preterm Neonates

IMPORTANCE

Understanding the role of chorioamnionitis, a major factor leading to preterm birth, in the pathogenesis of neonatal brain injury and adverse neurodevelopmental outcomes may help in identifying potentially modifiable perinatal variables affecting brain health and outcomes among children born preterm.

OBJECTIVE

To evaluate whether histologic chorioamnionitis among neonates born very preterm is associated with intraventricular hemorrhage (IVH) and punctate white matter injury (WMI) or with adverse neurodevelopmental outcomes during early childhood.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study conducted across 3 academic centers (from April 2006 to September 2013 in Canada, from March 2007 to March 2013 in the Netherlands, and from January 2004 to August 2011 in the United States). Children who were born preterm (24-32 weeks' gestation) and who had undergone a placental pathologic evaluation, magnetic resonance imaging as soon as clinically stable, and Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) assessments between 18 and 24 months' corrected age (CA) were included. Magnetic resonance imaging scans were assessed for grade of IVH and volume of punctate WMI. Data analysis occurred between December 2016 and January 2018. Final multivariable analyses examining the association of chorioamnionitis with motor and cognitive outcomes accounted for academic center and perinatal and postnatal factors.

MAIN OUTCOMES AND MEASURES

Punctate WMI volume and IVH detected on neonatal magnetic resonance imaging scans; motor and cognitive outcomes defined using Bayley-III assessments conducted among these children between 18 and 24 months' CA.

RESULTS

Of 350 neonates (182 male) in the final cohort, 145 (41.4%) had histologic chorioamnionitis. Gestational age was significantly lower among those with chorioamnionitis (median, 26.4 weeks; interquartile range [IQR], 25.6-27.7 weeks) than among those without chorioamnionitis (median, 28.0 weeks; IQR, 27.0-29.7 weeks). Chorioamnionitis was not associated with IVH or WMI, nor was it associated with worse motor outcomes in univariable or multivariable analyses (adjusted Bayley-III motor score, -2.2; 95% CI, -5.6 to 1.3). Cognitive scores were marginally yet statistically significantly lower among children with chorioamnionitis (median, 105; IQR, 95-110) than among those without chorioamnionitis (median, 105; IQR, 100-115) in the univariable model. This difference was attenuated in the multivariable model (adjusted Bayley-III cognitive score, -3.0; 95% CI, -6.4 to 0.4).

CONCLUSIONS AND RELEVANCE

Histologic chorioamnionitis was not associated with IVH or WMI near birth or with worse cognitive or motor outcomes from 18 to 24 months' CA after accounting for perinatal factors. Postnatal factors attenuated the association between chorioamnionitis and neurodevelopmental outcomes, highlighting the importance of preventing postnatal illness, such as infection, to promote optimal outcomes among children born preterm.

Multiple Postnatal Infections in Newborns Born Preterm Predict Delayed Maturation of Motor Pathways at Term-Equivalent Age with Poorer Motor Outcomes at 3 Years

OBJECTIVES

To evaluate whether the number of postnatal infections is associated with abnormal white matter maturation and poorer motor neurodevelopmental outcomes at 36 months of corrected age.

STUDY DESIGN

A prospective longitudinal cohort study was undertaken of 219 newborns born preterm at 24-32 weeks of gestational age recruited between 2006 and 2013 with magnetic resonance imaging of the brain both early in life and at term-equivalent age. Postnatal infection was defined as any clinical infection or positive culture ≥72 hours after birth. White matter maturation was assessed by magnetic resonance spectroscopic imaging, magnetic resonance diffusion tensor imaging, and tract-based spatial statistics. Neurodevelopmental outcomes were assessed in 175 (82% of survivors) infants with Bayley Scales of Infant and Toddler Development-III composite scores and Peabody Developmental Motor Scales at 35 months of corrected age (IQR 34-37 months). Infection groups were compared via the Fisher exact test, Kruskal-Wallis test, and generalized estimating equations.

RESULTS

Of 219 neonates born preterm (median gestational age 27.9 weeks), 109 (50%) had no postnatal infection, 83 (38%) had 1 or 2 infections, and 27 (12%) had ≥3 infections. Infants with postnatal infections had more cerebellar hemorrhage. Infants with ≥3 infections had lower N-acetylaspartate/choline in the white matter and basal ganglia regions, lower fractional anisotropy in the posterior limb of the internal capsule, and poorer maturation of the corpus callosum, optic radiations, and posterior limb of the internal capsule on tract-based spatial statistics analysis as well as poorer Bayley Scales of Infant and Toddler Development-III (P = .02) and Peabody Developmental Motor Scales, Second Edition, motor scores (P < .01).

CONCLUSIONS

In newborns born preterm, ≥3 postnatal infections predict impaired development of the motor pathways and poorer motor outcomes in early childhood.

Histologic chorioamnionitis in preterm infants: correlation with brain magnetic resonance imaging at term equivalent age

BACKGROUND

To explore the associations between histologic chorioamnionitis with brain injury, maturation and size on magnetic resonance imaging (MRI) of preterm infants at term equivalent age.

METHODS

Preterm infants (23-36 weeks' gestational age) were recruited into two longitudinal cohort studies. Presence or absence of chorioamnionitis was obtained from placental histology and clinical data were recorded. MRI at term-equivalent age was assessed for brain injury (intraventricular haemorrhage, cysts, signal abnormalities), maturation (degree of myelination, gyral maturation) and size of cerebral structures (metrics and brain segmentation). Histologic chorioamnionitis was assessed as a predictor of MRI variables using linear and logistic regression, with adjustment for confounding perinatal variables.

RESULTS

Two hundred and twelve infants were included in this study, 47 (22%) of whom had histologic chorioamnionitis. Histologic chorioamnionitis was associated with higher odds of intraventricular haemorrhage (odds ratio [OR] (95% confidence interval [CI]) = 7.4 (2.4, 23.1)), less mature gyral maturation (OR (95% CI) = 2.0 (1.0, 3.8)) and larger brain volume (mean difference in cubic centimeter (95% CI) of 14.1 (1.9, 26.2)); but all relationships disappeared following adjustment for perinatal variables.

CONCLUSION

Histologic chorioamnionitis was not independently associated with IVH, less mature gyral maturation or brain volume at term-equivalent age in preterm infants.

Timing of sepsis is an important risk factor for white matter abnormality in extremely premature infants with sepsis

BACKGROUND

Systemic infection is a major upstream mechanism for white matter abnormality (WMA). Our aim was to evaluate the risk factors for moderate-to-severe WMA in extremely premature infants (gestational age < 28 weeks) with neonatal sepsis.

METHODS

Extremely premature infants with culture-proven sepsis between 2006 and 2015 in a tertiary neonatal intensive care unit were classified as having none-to-mild or moderate-to-severe WMA based on WM scores of brain magnetic resonance imaging at the term-equivalent age. Various risk factors for WMA were analyzed.

RESULTS

Sixty-three infants (87.5%) had none-to-mild WMA, and nine infants (12.5%) had moderate-to-severe WMA. Multivariate logistic regression analysis revealed that postmenstrual age (PMA) at sepsis diagnosis (OR: 0.640, 95% CI: 0.435-0.941, p = 0.023) and PMA at sepsis diagnosis <28 weeks (OR: 9.232, 95% CI: 1.020-83.590, p = 0.048) were independently associated with moderate-to-severe WMA. PMA at sepsis diagnosis had a significant negative correlation with WM scores (r = -0.243, p = 0.039).

CONCLUSION

PMA at sepsis diagnosis might be an important risk factor for moderate-to-severe WMA in extremely premature infants with postnatal sepsis, especially before PMA 28 weeks. Infants who suffer from sepsis before PMA 28 weeks might need additional therapy for neuroprotection.

Chorioamnionitis, IL-17A, and fetal origins of neurologic disease

The Centers for Disease Control and Prevention estimate that 1 in 323 infants have cerebral palsy. Highly correlated to intrauterine infection and inflammation, the incidence of cerebral palsy has remained constant over the last few decades despite significant advances in neonatal intensive care including improved ventilator techniques, surfactant therapy, maternal steroid administration, and use of intrapartum empiric antimicrobials. Recent advances in our understanding of immune responses to infection and inflammation have identified the cytokine IL-17A as a crucial component of early proinflammatory mediators that cause brain injury associated with neurologic impairment. Remarkably, maternal inflammatory responses to in utero inflammation and infection can also lead to potentially debilitating neurologic conditions in the offspring, which often become clinically apparent during childhood and/or early adulthood. This review details the role of IL-17A in fetal and maternal proinflammatory responses that lead to fetal brain injury and neurologic sequelae, including cerebral palsy. Recent findings regarding the role of maternal inflammatory responses in the development of childhood and adult neurologic conditions, such as autism, schizophrenia, and multiple sclerosis, will also be highlighted.

Early Procedural Pain Is Associated with Regionally-Specific Alterations in Thalamic Development in Preterm Neonates

Very preterm human neonates are exposed to numerous invasive procedures as part of life-saving care. Evidence suggests that repetitive neonatal procedural pain precedes long-term alterations in brain development. However, to date the link between pain and brain development has limited temporal and anatomic specificity. We hypothesized that early exposure to painful stimuli during a period of rapid brain development, before pain modulatory systems reach maturity, will predict pronounced changes in thalamic development, and thereby cognitive and motor function. In a prospective cohort study, 155 very preterm neonates (82 males, 73 females) born 24-32 weeks' gestation underwent two MRIs at median postmenstrual ages 32 and 40 weeks that included structural, metabolic, and diffusion imaging. Detailed day-by-day clinical data were collected. Cognitive and motor abilities were assessed at 3 years, corrected age. The association of early (skin breaks, birth-Scan 1) and late pain (skin breaks, Scans 1-2) with thalamic volumes and N-acetylaspartate (NAA)/choline (Cho), and fractional anisotropy of white-matter pathways was assessed. Early pain was associated with slower thalamic macrostructural growth, most pronounced in extremely premature neonates. Deformation-based morphometry analyses confirmed early pain-related volume losses were localized to somatosensory regions. In extremely preterm neonates early pain was associated with decreased thalamic NAA/Cho and microstructural alterations in thalamocortical pathways. Thalamic growth was in turn related to cognitive and motor outcomes. We observed regionally-specific alterations in the lateral thalamus and thalamocortical pathways in extremely preterm neonates exposed to more procedural pain. Findings suggest a sensitive period leading to lasting alterations in somatosensory-system development.SIGNIFICANCE STATEMENT Early exposure to repetitive procedural pain in very preterm neonates may disrupt the development of regions involved in somatosensory processing, leading to poor functional outcomes. We demonstrate that early pain is associated with thalamic volume loss in the territory of the somatosensory thalamus and is accompanied by disruptions thalamic metabolic growth and thalamocortical pathway maturation, particularly in extremely preterm neonates. Thalamic growth was associated with cognitive and motor outcome at 3 years corrected age. Findings provide evidence for a developmentally sensitive period whereby subcortical structures in young neonates may be most vulnerable to procedural pain. Furthermore, results suggest that the thalamus may play a key role underlying the association between neonatal pain and poor neurodevelopmental outcomes in these high-risk neonates.

Exploring the multiple-hit hypothesis of preterm white matter damage using diffusion MRI

Background

Preterm infants are at high risk of diffuse white matter injury and adverse neurodevelopmental outcome. The multiple hit hypothesis suggests that the risk of white matter injury increases with cumulative exposure to multiple perinatal risk factors. Our aim was to test this hypothesis in a large cohort of preterm infants using diffusion weighted magnetic resonance imaging (dMRI).

Methods

We studied 491 infants (52% male) without focal destructive brain lesions born at < 34 weeks, who underwent structural and dMRI at a specialist Neonatal Imaging Centre. The median (range) gestational age (GA) at birth was 30^+ 1 (23^+ 2–33^+ 5) weeks and median postmenstrual age at scan was 42^+ 1 (38–45) weeks. dMRI data were analyzed using tract based spatial statistics and the relationship between dMRI measures in white matter and individual perinatal risk factors was assessed. We tested the hypothesis that increased exposure to perinatal risk factors was associated with lower fractional anisotropy (FA), and higher radial, axial and mean diffusivity (RD, AD, MD) in white matter. Neurodevelopmental performance was investigated using the Bayley Scales of Infant and Toddler Development, Third Edition (BSITD-III) in a subset of 381 infants at 20 months corrected age. We tested the hypothesis that lower FA and higher RD, AD and MD in white matter were associated with poorer neurodevelopmental performance.

Results

Identified risk factors for diffuse white matter injury were lower GA at birth, fetal growth restriction, increased number of days requiring ventilation and parenteral nutrition, necrotizing enterocolitis and male sex. Clinical chorioamnionitis and patent ductus arteriosus were not associated with white matter injury. Multivariate analysis demonstrated that fetal growth restriction, increased number of days requiring ventilation and parenteral nutrition were independently associated with lower FA values. Exposure to cumulative risk factors was associated with reduced white matter FA and FA values at term equivalent age were associated with subsequent neurodevelopmental performance.

Conclusion

This study suggests multiple perinatal risk factors have an independent association with diffuse white matter injury at term equivalent age and exposure to multiple perinatal risk factors exacerbates dMRI defined, clinically significant white matter injury. Our findings support the multiple hit hypothesis for preterm white matter injury.

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White matter injury was assessed in 491 preterm infants at term equivalent age.

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Aberrant white matter development was associated with several perinatal factors.

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Our findings support the multiple hit hypothesis for preterm brain injury.

Origin and dynamics of oligodendrocytes in the developing brain: Implications for perinatal white matter injury

Infants born prematurely are at high risk to develop white matter injury (WMI), due to exposure to hypoxic and/or inflammatory insults. Such perinatal insults negatively impact the maturation of oligodendrocytes (OLs), thereby causing deficits in myelination. To elucidate the precise pathophysiology underlying perinatal WMI, it is essential to fully understand the cellular mechanisms contributing to healthy/normal white matter development. OLs are responsible for myelination of axons. During brain development, OLs are generally derived from neuroepithelial zones, where neural stem cells committed to the OL lineage differentiate into OL precursor cells (OPCs). OPCs, in turn, develop into premyelinating OLs and finally mature into myelinating OLs. Recent studies revealed that OPCs develop in multiple waves and form potentially heterogeneous populations. Furthermore, it has been shown that myelination is a dynamic and plastic process with an excess of OPCs being generated and then abolished if not integrated into neural circuits. Myelination patterns between rodents and humans show high spatial and temporal similarity. Therefore, experimental studies on OL biology may provide novel insights into the pathophysiology of WMI in the preterm infant and offers new perspectives on potential treatments for these patients.

Severe retinopathy of prematurity predicts delayed white matter maturation and poorer neurodevelopment

OBJECTIVE

To determine whether severe retinopathy of prematurity (ROP) is associated with (1) abnormal white matter maturation and (2) neurodevelopmental outcomes at 18 months' corrected age (CA) compared with neonates without severe ROP.

DESIGN

We conducted a prospective longitudinal cohort of extremely preterm neonates born 24-28 weeks' gestational age recruited between 2006 and 2013 with brain MRIs obtained both early in life and at term-equivalent age. Severe ROP was defined as ROP treated with retinal laser photocoagulation. Using diffusion tensor imaging and tract-based spatial statistics (TBSS), white matter maturation was assessed by mean fractional anisotropy (FA) in seven predefined regions of interest. Neurodevelopmental outcomes were assessed with Bayley Scales of Infant and Toddler Development-III (Bayley-III) composite scores at 18 months' CA. Subjects were compared using Fisher's exact, Kruskal-Wallis and generalised estimating equations.

SETTING

Families were recruited from the neonatal intensive care unit at BC Women's Hospital.

PATIENTS

Of 98 extremely preterm neonates (median: 26.0 weeks) assessed locally for ROP, 19 (19%) had severe ROP and 83 (85%) were assessed at 18 months' CA.

RESULTS

Severe ROP was associated with lower FA in the posterior white matter, and with decreased measures of brain maturation in the optic radiations, posterior limb of the internal capsule (PLIC) and external capsule on TBSS. Bayley-III cognitive and motor scores were lower in infants with severe ROP.

CONCLUSIONS

Severe ROP is associated with maturational delay in the optic radiations, PLIC, external capsule and posterior white matter, housing the primary visual and motor pathways, and is associated with poorer cognitive and motor outcomes at 18 months' CA.

Early postnatal illness severity scores predict neurodevelopmental impairments at 10 years of age in children born extremely preterm

OBJECTIVE

A neonatal illness severity score, The Score for Neonatal Acute Physiology-II (SNAP-II), predicts neurodevelopmental impairments at two years of age among children born extremely preterm. We sought to evaluate to what extent SNAP-II is predictive of cognitive and other neurodevelopmental impairments at 10 years of age.

STUDY DESIGN

In a cohort of 874 children born before 28 weeks of gestation, we prospectively collected clinical, physiologic and laboratory data to calculate SNAP-II for each infant. When the children were 10 years old, examiners who were unaware of the child's medical history assessed neurodevelopmental outcomes, including neurocognitive, gross motor, social and communication functions, diagnosis and treatment of seizures or attention deficit hyperactivity disorder (ADHD), academic achievement, and quality of life. We used logistic regression to adjust for potential confounders.

RESULTS

An undesirably high SNAP-II (⩾30), present in 23% of participants, was associated with an increased risk of cognitive impairment (IQ, executive function, language ability), adverse neurological outcomes (epilepsy, impaired gross motor function), behavioral abnormalities (attention deficit disorder and hyperactivity), social dysfunction (autistic spectrum disorder) and education-related adversities (school achievement and need for educational supports. In analyses that adjusted for potential confounders, Z-scores ⩽-1 on 11 of 18 cognitive outcomes were associated with SNAP-II in the highest category, and 6 of 18 were associated with SNAP-II in the intermediate category. Odds ratios and 95% confidence intervals ranged from 1.4 (1.01, 2.1) to 2.1 (1.4, 3.1). Similarly, 2 of the 8 social dysfunctions were associated with SNAP-II in the highest category, and 3 of 8 were associated with SNAP-II in the intermediate category. Odds ratios and 95% confidence intervals were slightly higher for these assessments, ranging from 1.6 (1.1, 2.4) to 2.3 (1.2, 4.6).

CONCLUSION

Among very preterm newborns, physiologic derangements present in the first 12 postnatal hours are associated with dysfunctions in several neurodevelopmental domains at 10 years of age. We are unable to make inferences about causality.