Detection of impaired growth of the corpus callosum in premature infants

Disproportion of Corpus Callosum in Fetuses With Malformations of Cortical Development

OBJECTIVE

To evaluate corpus callosum (CC) size in fetuses with malformations of cortical development (MCD) and to explore the diagnostic value of three CC length (CCL) ratios in identifying cortical abnormalities.

METHODS

This is a single-center retrospective study in singleton fetuses at 20-37 weeks of gestation between April 2017 and August 2022. The midsagittal plane of the fetal brain was obtained and evaluated for the following variables: length, height, area of the corpus callosum, and relevant markers, including the ratios of corpus callosum length to internal cranial occipitofrontal dimension (CCL/ICOFD), corpus callosum length to femur length (CCL/FL), and corpus callosum length to cerebellar vermian diameter (CCL/VD). Intra-class correlation coefficient (ICC) was used to evaluate measurement consistency. The accuracy of biometric measurements in prediction of MCD was assessed using the area under the receiver-operating-characteristics curves (AUC).

RESULTS

Fetuses with MCD had a significantly decreased CCL, height (genu and splenium), and area as compared with those of normal fetuses (P < .05), but there was no significant difference in body height (P = .326). The CCL/ICOFD, CCL/FL, and CCL/VD ratios were significantly decreased in fetuses with MCD when compared with controls (P < .05). The CCL/ICOFD ratio offered the highest predictive accuracy for MCD, yielding an AUC of 0.856 (95% CI: 0.774-0.938, P < .001), followed by CCL/FL ratio (AUC, 0.780 (95% CI: 0.657-0.904), P < .001), CCL/VD ratio (AUC, 0.677 (95% CI: 0.559-0.795), P < .01).

CONCLUSION

The corpus callosum biometric parameters in fetuses with MCD are reduced. The CCL/ICOFD ratio derived from sonographic measurements is considered a promising tool for the prenatal detection of cortical malformations. External validation of these findings and prospective studies are warranted.

Brain Growth Evaluation Assessed with Transfontanellar (B-GREAT) Ultrasound. Old and New Bedside Markers to Estimate Cerebral Growth in Preterm Infants: a Pilot Study

OBJECTIVE

We aimed to investigate the feasibility of evaluating overall preterm brain growth using a gathered set of measurements of brain structures in standard cranial ultrasound planes. We called this method of assessment Brain Growth Evaluation Assessed with Transfontanellar ultrasound (B-GREAT).

STUDY DESIGN

In this prospective observational cohort study, cranial ultrasound was regularly performed (on day 1, 2, 3, and 7 of life, and then weekly until discharge, and at term) in preterm infants born with gestational age (GA) less than 32 weeks. We evaluated corpus callosum length, corpus callosum-fastigium length, anterior horn width, frontal white matter height, total brain surface, deep grey matter height, hemisphere height, transverse cerebellar diameter in the axial view, and transverse cerebellar diameter coronal view. Measurements obtained were used to develop growth charts for B-GREAT markers as a function of postmenstrual age. Reproducibility of B-GREAT markers was studied.

RESULTS

A total of 528 cranial ultrasounds were performed in 80 neonates (median birth GA: 28+5 weeks and interquartile range: 27+3-30+5). The intraclass correlation coefficients for intra-observer and inter-observer analyses showed substantial agreement for all B-GREAT markers. Growth curves for B-GREAT markers were developed.

CONCLUSION

B-GREAT is a feasible and reproducible method for bedside monitoring of the growth of the main brain structures in preterm neonates.

KEY POINTS

· Overall neonatal brain growth is not routinely monitored using ultrasound.. · Old and new markers were used to build a standardized and non-invasive tool to monitor brain growth.. · All B-GREAT measurements had a good intra-observer and inter-observer agreement..

Relationships between early postnatal cranial ultrasonography linear measures and neurodevelopment at 2 years in infants born at <30 weeks' gestational age without major brain injury

OBJECTIVE

To explore relationships of early postnatal cranial ultrasonography (cUS) linear measures of brain size and brain growth with neurodevelopment at 2 years in infants born <30 weeks' gestational age (GA) and free of major brain injury.

DESIGN

Prospective observational cohort study.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

139 infants born <30 weeks' GA, free of major brain injury on neonatal cUS and without congenital or chromosomal anomalies known to affect neurodevelopment.

INTERVENTION

Linear measures of brain tissue and fluid spaces made from cUS at 1-week, 1-month and 2-months' postnatal age.

MAIN OUTCOME MEASURES

Cognitive, language and motor scores on the Bayley Scales of Infant and Toddler Development, third edition at 2 years' corrected age.

RESULTS

313 scans were evaluated from the 131 children who were assessed at 2 years. Larger measures of the corpus callosum at 1 week, 1 month and 2 months, cerebellum and vermis at 2 months and faster positive growth of the cerebellum and vermis between 1 month and 2 months, were related to higher cognitive and language scores at 2 years. No relation between tissue measures and motor scores was found. Larger measures, and faster rate of increase, of fluid spaces within the first weeks after birth were related to better cognitive, language and motor outcomes at 2 years.

CONCLUSIONS

Early postnatal cUS linear measures of brain tissue were related to cognitive and language development at 2 years in infants born <30 weeks' GA without major brain injury. Relationships between cUS linear measures of fluid spaces in the early postnatal period and later neurodevelopment warrant further exploration.

Changes in structural brain development after selective fetal growth restriction in monochorionic twins

OBJECTIVES

Fetal growth restriction (FGR) may alter brain development permanently, resulting in lifelong structural and functional changes. However, in studies addressing this research question, FGR singletons have been compared primarily to matched appropriately grown singletons, a design which is inherently biased by differences in genetic and maternal factors. To overcome these limitations, we conducted a within-pair comparison of neonatal structural cerebral ultrasound measurements in monochorionic twin pairs with selective FGR (sFGR).

METHODS

Structural cerebral measurements on neonatal cerebral ultrasound were compared between the smaller and larger twins of monochorionic twin pairs with sFGR, defined as a birth-weight discordance (BWD) ≥ 20%, born in our center between 2010 and 2020. Measurements from each twin pair were also compared with those of an appropriately grown singleton, matched according to sex and gestational age at birth.

RESULTS

Included were 58 twin pairs with sFGR, with a median gestational age at birth of 31.7 (interquartile range, 29.9-33.8) weeks and a median birth weight of 1155 g for the smaller twin and 1725 g for the larger twin (median BWD, 32%). Compared with both the larger twin and the singleton, the smaller twin had significantly smaller cerebral structures (corpus callosum, vermis, cerebellum), less white/deep gray matter and smaller intracranial surface area and volume. Intracranial-volume discordance and BWD correlated significantly (R²  = 0.228, P < 0.0001). The median intracranial-volume discordance was smaller than the median BWD (19% vs 32%, P < 0.0001). After correction for intracranial volume, only one of the observed differences (biparietal diameter) remained significant for the smaller twin vs both the larger twin and the singleton.

CONCLUSIONS

In monochorionic twins with sFGR, neonatal cerebral ultrasound reveals an overall, proportional restriction in brain growth, with smaller cerebral structures, less white/deep gray matter and smaller overall brain-size parameters in the smaller twin. There was a positive linear relationship between BWD and intracranial-volume discordance, with intracranial-volume discordance being smaller than BWD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Language lateralization in very preterm children: associating dichotic listening to interhemispheric connectivity and language performance

BACKGROUND

Language difficulties of very preterm (VPT) children might be related to weaker cerebral hemispheric lateralization of language. Language lateralization refers to the development of an expert region for language processing in the left hemisphere during the first years of life. Children born VPT might not develop such a dominant left hemisphere for language processing. A dichotic listening task may be a functional task to show the dominance of the left hemisphere during language processing. During this task, different acoustic events are simultaneously presented to both ears. Due to crossing fibers in the brain, right ear stimuli are transferred directly to the left hemisphere, and left ear stimuli are transferred first to the right hemisphere and then, through the corpus callosum (CC), to the left hemisphere. Dichotic listening typically shows a right ear advantage, assuming to reflect left hemispherical language dominance. The CC, in particular the splenium, is associated with auditory processing and is considered important for language lateralization. The objective of this work was to explore whether dichotic listening performance in school-aged VPT children are associated with language performance and interhemispheric connectivity.

METHODS

This is a cross-sectional study of 58 VPT children and 30 full term controls at age 10 years. Language performance and dichotic digit test (DDT) were assessed. In 44 VPT children, additionally diffusion weighted imaging (DWI) was performed using a 3 T MRI scanner. Fractional anisotropy (FA) and mean diffusivity (MD) values of the splenium of the CC were extracted.

RESULTS

Poorer right ear DDT scores were associated with poorer language performance in VPT children only (p = 0.015). Association between right ear DDT scores and MD of the splenium approached the level of significance (p = 0.051).

CONCLUSIONS

These results support the hypothesis that poor language performance in VPT children may be a consequence of weaker lateralized language organization, due to a poorly developed splenium of the CC. Dichotic listening may reflect the level of language lateralization in VPT children.

IMPACT

Poor language performance in VPT children may be a consequence of weaker lateralized language organization, due to a poorly developed splenium of the CC. Dichotic listening performance may reflect the level of language lateralization in VPT children and right ear scores of a dichotic listening task are associated with both the splenium of the corpus callosum and language performance. If our results could be validated in future research, it suggests that poor CC development may indicate VPT children at risk for long-term language problems.

Early Ultrasonic Monitoring of Brain Growth and Later Neurodevelopmental Outcome in Very Preterm Infants

BACKGROUND AND PURPOSE

In infants born very preterm, monitoring of early brain growth could contribute to prediction of later neurodevelopment. Therefore, our aim was to investigate associations between 2 early cranial ultrasound markers (corpus callosum-fastigium and corpus callosum length) and neurodevelopmental outcome and the added value of both markers in the prediction of neurodevelopmental outcome based on neonatal risk factors and head circumference in very preterm infants.

MATERIALS AND METHODS

This prospective observational study included 225 infants born at <30 weeks' gestational age, of whom 153 were without any brain injury on cranial ultrasound. Corpus callosum-fastigium and corpus callosum length and head circumference were measured at birth, 29 weeks' gestational age, transfer from the neonatal intensive care unit to a level II hospital, and 2 months' corrected age. We analyzed associations of brain markers and their growth with cognitive, motor, language, and behavioral outcome at 2 years' corrected age.

RESULTS

In infants without brain injury, greater corpus callosum-fastigium length at 2 months was associated with better cognitive outcome. Corpus callosum length at 2 months was positively associated with cognitive, motor, and language outcome. Faster growth of the corpus callosum length between birth and 2 months was associated with better cognitive and motor function. Prediction of neurodevelopmental outcome based on neonatal risk factors with or without head circumference was significantly improved by adding corpus callosum length.

CONCLUSIONS

Both corpus callosum-fastigium and corpus callosum length on cranial ultrasound are associated with neurodevelopmental outcome of very preterm infants without brain injury at 2 years, but only corpus callosum length shows the added clinical utility in predicting neurodevelopmental outcome.

Corpus callosum size by neurosonography in fetuses with congenital heart defect and relationship with expected pattern of brain oxygen supply

OBJECTIVE

To evaluate corpus callosum (CC) size by neurosonography (NSG) in fetuses with an isolated major congenital heart defect (CHD) and explore the association of CC size with the expected pattern of in-utero oxygen supply to the brain.

METHODS

A total of 56 fetuses with postnatally confirmed isolated major CHD and 56 gestational-age-matched controls were included. Fetuses with CHD were stratified into two categories according to the main expected pattern of cerebral arterial oxygen supply: Class A, moderately to severely reduced oxygen supply (left outflow tract obstruction and transposition of the great arteries) and Class B, near normal or mildly impaired oxygenated blood supply to the brain (other CHD). Transvaginal NSG was performed at 32-36 weeks in all fetuses to evaluate CC length, CC total area and areas of CC subdivisions in the midsagittal plane.

RESULTS

CHD fetuses had a significantly smaller CC area as compared to controls (7.91 ± 1.30 vs 9.01 ± 1.44 mm² ; P < 0.001), which was more pronounced in the most posterior part of the CC. There was a significant linear trend for reduced CC total area across the three clinical groups, with CHD Class-A cases showing more prominent changes (controls, 9.01 ± 1.44 vs CHD Class B, 8.18 ± 1.21 vs CHD Class A, 7.53 ± 1.33 mm² ; P < 0.05).

CONCLUSIONS

Fetuses with major CHD had a smaller CC compared with controls, and the difference was more marked in the CHD subgroup with expected poorer brain oxygenation. Sonographic CC size could be a clinically feasible marker of abnormal white matter development in CHD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Relationships between early postnatal cranial ultrasonography linear measures and neurobehaviour at term-equivalent age in infants born <30 weeks' gestational age

BACKGROUND

The relationship between early postnatal brain development and neurobehaviour at term-equivalent age (TEA) remains uncertain.

AIM

We aimed to explore relationships between early postnatal cranial ultrasonography (cUS) linear measures of brain size and brain growth with neurobehaviour at TEA in infants born <30 weeks' gestational age (GA).

STUDY DESIGN

Prospective observational cohort study.

SUBJECTS

137 infants born <30 weeks' GA without major brain injury on neonatal cUS.

OUTCOME MEASURES

Neurobehaviour at TEA assessed using the General Movements Assessment (GMA) and Hammersmith Neonatal Neurological Examination (HNNE).

RESULTS

The GMA was administered in 115/137 (84%) infants; 80 (70%) presented with abnormal general movements (GMs) (79 poor repertoire, 1 cramped synchronised). The HNNE was assessed in 106/137 (77%) infants; 52 (49%) had a suboptimal total score. With respect to brain size, larger measures of the corpus callosum length (CCL) and right anterior horn width (AHW) at 1-month were related to lower risk of abnormal GMs, and larger measures of the biparietal diameter at 1-week and 2-months were related to lower risk of a suboptimal HNNE. As for brain growth, increases of the CCL and transcerebellar diameter between birth and 1-month, and left and right AHWs between 1- and 2-months, were related to lower risk of abnormal GMs.

CONCLUSION

Early postnatal brain size and brain growth were related to neurobehaviour at TEA in infants born <30 weeks' GA. This study provides preliminary evidence for the prognostic utility of early postnatal cUS linear measures as potential markers of neurodevelopment in later childhood.

An Exploratory Study Into a New Head Ultrasound Marker for Predicting Neurodevelopmental Outcomes in Preterm Infants

ABSTRACT

Preterm infants are at risk of neurological impairments and long-term developmental delay. Head ultrasound (HUS) is a promising tool for early detection of preterm brain injury and prediction of neurodevelopmental outcomes. We performed a retrospective analysis of data of 42 preterm infants with neurodevelopmental follow-up at 12 to 24 months corrected age. Corpus callosum length (CC length) and corpus callosum-fastigium length (CCF length) were measured on the HUS scans. Motor function and communication skills were assessed using evaluation scales. Corpus callosum length and CCF length were correlated with neurodevelopmental outcomes using Spearman correlation analysis. Neither CC length nor CCF length correlated with motor developmental outcomes. On early HUS, the CCF length was negatively correlated with symbolic composite percentile ranks (Spearman ρ = -0.49, P = 0.033) and total percentile ranks (Spearman ρ = -0.545, P = 0.016). On follow-up HUS scans, the CCF length was also found to be negatively correlated with social composite raw scores and percentile ranks (Spearman ρ = -0.615, P = 0.005; and Spearman ρ = -0.64, P = 0.003, respectively), symbolic composite raw scores and percentile ranks (Spearman ρ = -0.609, P = 0.006; and Spearman ρ = -0.657, P = 0.002, respectively) and total raw scores and percentile ranks (Spearman ρ = -0.472, P = 0.041; and Spearman ρ = -0.504, P = 0.028, respectively). Corpus callosum-fastigium length measurement on serial HUS is useful in predicting cognitive and behavioral outcomes at corrected age 12 to 24 months.

Corpus Callosum Growth and Neurodevelopmental Outcome Are Negatively Influenced by Systemic Infection in Very Low-Birth-Weight Infants

Systemic infection may negatively modulate the development of cerebral white matter and long-term outcome of neonates. We analyzed the growth of corpus callosum (using cranial ultrasonography) and neurodevelopment (Bayley Scales of Infant Development, Third Edition) in 101 very low-birth-weight newborns. We observed significantly reduced corpus callosum length at 3 months of corrected age (44.5 mm vs 47.7 mm, P = .004) and diminished corpus callosum growth (0.07 mm/d vs 0.08 mm/d, P = .028) in infants who experienced systemic infection. The subgroup exhibited inferior neurodevelopmental outcomes with predominant motor impairment. The results suggest that length and growth of corpus callosum might be affected by systemic inflammatory response in preterm newborns. The changes in corpus callosum can contribute to adverse neurodevelopment at 2 years of corrected age. Serial ultrasonographic measurements of the corpus callosum may be suitable to identify preterm infants with increased risk of neurodevelopmental impairment.

Prenatal Ultrasound Diagnosis of Biometric changes in the Brain of Growth Restricted Fetuses. A Systematic Review of Literature

Fetal growth restriction (FGR) occurs when the fetus does not reach its intrauterine potential for growth and development as a result of compromise in placental function. It is a condition that affects 5 to 10% of pregnancies and is the second most common cause of perinatal morbidity and mortality. Children born with FGR are at risk of impaired neurological and cognitive development and cardiovascular or endocrine diseases in adulthood. The purpose of the present revision is to perform a literature search for evidence on the detection and assessment by ultrasound of brain injury linked to FGR during fetal life. Using a systematic approach and quantitative evaluation as study methodology, we reviewed ultrasound studies of the fetal brain structure of growth-restricted fetuses with objective quality measures. A total of eight studies were identified. High quality studies were identified for measurement of brain volumes; corpus callosum; brain fissure depth measurements, and cavum septi pellucidi width measurement. A low-quality study was available for transverse cerebellar diameter measurement in FGR. Further prospective randomized studies are needed to understand the changes that occur in the brain of fetuses with restricted growth, as well as their correlation with the changes in cognitive development observed.

Linear growth of corpus callosum and cerebellar vermis in very-low-birth-weight preterm infants

BACKGROUND/PURPOSE

Impaired growth of the corpus callosum (CC) and cerebellar vermis (CV) is associated with poorer neurodevelopmental outcomes in preterm infants. However, references on the postnatal growth rate of the CC and CV by sonography are limited. The aim of this study is to assess the normal linear growth of CC and CV using a serial cranial ultrasound.

METHODS

We prospectively enrolled preterm infants with very low birth weight from September 2008 to December 2009 after excluding those with congenital anomalies or diseases affecting the brain parenchyma. Serial sonographic measurements of the CC and CV were performed according to the standard protocol. Scheduled comprehensive neurodevelopmental evaluations were performed till the corrected age of 2 years. We excluded those with significant brain damages or poor neurodevelopmental outcomes in the final analysis. The growth rate was estimated using the loess smoothing curve and linear regression analysis.

RESULTS

Among the 86 enrolled neonates, 14 with significant brain damage and 8 with poor neurodevelopmental outcomes were excluded from the final analysis. The growth rate of the CC length was 1.72 (95% confidence interval [CI]: 1.24-2.20) and 0.57 (95% CI: 0.33-0.80) mm per week before and after the postmenstrual age of 30.5 weeks, respectively. The growth rate of the CV length was 0.78 (95% CI: 0.68-0.89) mm per week.

CONCLUSION

We proposed reference values of the normal linear growth rate of the CC and CV lengths in very-low-birth-weight preterm infants using the serial cranial ultrasound.

Infant Corpus Callosum Size After Surgery and Critical Care for Long-Gap Esophageal Atresia: Qualitative and Quantitative MRI

Previous studies in preterm infants report white matter abnormalities of the corpus callosum (CC) as an important predictor of neurodevelopmental outcomes. Our cross-sectional study aimed to describe qualitative and quantitative CC size in critically ill infants following surgical and critical care for long-gap esophageal atresia (LGEA) - in comparison to healthy infants - using MRI. Non-sedated brain MRI was acquired for full-term (n = 13) and premature (n = 13) patients following treatment for LGEA, and controls (n = 20) <1 year corrected age. A neuroradiologist performed qualitative evaluation of T1-weighted images. ITK-SNAP was used for linear, 2-D and 3-D manual CC measures and segmentations as part of CC size quantification. Qualitative MRI analysis indicated underdeveloped CC in both patient groups in comparison to controls. We show no group differences in mid-sagittal CC length. Although 2-D results were inconclusive, volumetric analysis showed smaller absolute (F(2,42) = 20.40, p < 0.001) and normalized (F(2,42) = 16.61, p < 0.001) CC volumes following complex perioperative treatment for LGEA in both full-term and premature patients, suggesting delayed or diminished CC growth in comparison to controls, with no difference between patient groups. Future research should look into etiology of described differences, neurodevelopmental outcomes, and role of the CC as an early marker of neurodevelopment in this unique infant population.

Differences in White Matter Microstructure Among Children With Developmental Coordination Disorder

IMPORTANCE

Developmental coordination disorder (DCD) is a motor impairment that significantly interferes with activities of daily living. Little is known about the cause of DCD and how it develops, making it difficult to understand why children with DCD struggle in learning motor skills and to determine the best intervention to optimize function.

OBJECTIVE

To characterize white matter differences using diffusion tensor imaging in children with and without DCD.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study collected diffusion tensor imaging data at BC Children's Hospital Research Institute in Vancouver, British Columbia, Canada, from September 2014 to January 2017. Using a sample of convenience, children with DCD and children without DCD aged 8 to 12 years underwent magnetic resonance imaging. Data analysis was conducted from January 2017 to January 2020.

MAIN OUTCOMES AND MEASURES

The main outcome measures were diffusion parameters, including fractional anisotropy and mean, axial, and radial diffusivity, which are thought to provide an indirect measure of white matter microstructure. Tract-based spatial statistics, a voxelwise statistical analysis of diffusion parameters, were conducted using a 2-group comparison design matrix with age and attention as covariates.

RESULTS

Thirty children without DCD (mean [SD] age, 9.9 [1.4] years; 21 [70%] boys) and 31 children with DCD (mean [SD] age, 10.1 [1.2] years; 26 [84%] boys) were included in the study. Compared with children without DCD, children with DCD were characterized by significantly lower fractional anisotropy and axial diffusivity in regions of white matter pathways associated with motor and sensorimotor processing, including the corticospinal tract (fractional anisotropy: mean [SD], 0.54 [0.03] vs 0.51 [0.03]; P < .001; axial diffusivity: mean [SD], 0.13 [0.98] vs 0.12 [0.46]; P = .01), posterior thalamic radiation at the retrolenticular part of the internal capsule (axial diffusivity: mean [SD], 0.14 [0.57] vs 0.14 [0.44]; P = .01), and cerebellar pathways (eg, superior cerebellar peduncle, fractional anisotropy: mean [SD], 0.49 [0.05] vs 0.46 [0.03]; P = .03; axial diffusivity: mean [SD], 0.14 [0.66] vs 0.14 [0.63]; P = .009). There were no significant differences in mean diffusivity and radial diffusivity between children with and without DCD.

CONCLUSIONS AND RELEVANCE

These findings suggest that children with DCD show significant brain differences in motor and sensorimotor white matter pathways compared with children without DCD. The pattern of diffusion parameters in children with DCD suggests that axonal development may be disrupted in this neurodevelopmental disorder.

Neurologic Injury and Brain Growth in the Setting of Long-Gap Esophageal Atresia Perioperative Critical Care: A Pilot Study

We previously showed that infants born with long-gap esophageal atresia (LGEA) demonstrate clinically significant brain MRI findings following repair with the Foker process. The current pilot study sought to identify any pre-existing (PRE-Foker process) signs of brain injury and to characterize brain and corpus callosum (CC) growth. Preterm and full-term infants (n = 3/group) underwent non-sedated brain MRI twice: before (PRE-Foker scan) and after (POST-Foker scan) completion of perioperative care. A neuroradiologist reported on qualitative brain findings. The research team quantified intracranial space, brain, cerebrospinal fluid (CSF), and CC volumes. We report novel qualitative brain findings in preterm and full-term infants born with LGEA before undergoing Foker process. Patients had a unique hospital course, as assessed by secondary clinical end-point measures. Despite increased total body weight and absolute intracranial and brain volumes (cm3) between scans, normalized brain volume was decreased in 5/6 patients, implying delayed brain growth. This was accompanied by both an absolute and relative CSF volume increase. In addition to qualitative findings of CC abnormalities in 3/6 infants, normative CC size (% brain volume) was consistently smaller in all infants, suggesting delayed or abnormal CC maturation. A future larger study group is warranted to determine the impact on the neurodevelopmental outcomes of infants born with LGEA.

Prediction of Gait Impairment in Toddlers Born Preterm From Near-Term Brain Microstructure Assessed With DTI, Using Exhaustive Feature Selection and Cross-Validation

AIM

To predict gait impairment in toddlers born preterm with very-low-birth-weight (VLBW), from near-term white-matter microstructure assessed with diffusion tensor imaging (DTI), using exhaustive feature selection, and cross-validation.

METHODS

Near-term MRI and DTI of 48 bilateral and corpus callosum regions were assessed in 66 VLBW preterm infants; at 18-22 months adjusted-age, 52/66 participants completed follow-up gait assessment of velocity, step length, step width, single-limb support and the Toddle Temporal-spatial Deviation Index (TDI). Multiple linear models with exhaustive feature selection and leave-one-out cross-validation were employed in this prospective cohort study: linear and logistic regression identified three brain regions most correlated with gait outcome.

RESULTS

Logistic regression of near-term DTI correctly classified infants high-risk for impaired gait velocity (93% sensitivity, 79% specificity), right and left step length (91% and 93% sensitivity, 85% and 76% specificity), single-limb support (100% and 100% sensitivity, 100% and 100% specificity), step width (85% sensitivity, 80% specificity), and Toddle TDI (85% sensitivity, 75% specificity). Linear regression of near-term brain DTI and toddler gait explained 32%-49% variance in gait temporal-spatial parameters. Traditional MRI methods did not predict gait in toddlers.

INTERPRETATION

Near-term brain microstructure assessed with DTI and statistical learning methods predicted gait impairment, explaining substantial variance in toddler gait. Results indicate that at near term age, analysis of a set of brain regions using statistical learning methods may offer more accurate prediction of outcome at toddler age. Infants high risk for single-limb support impairment were most accurately predicted. As a fundamental element of biped gait, single-limb support may be a sensitive marker of gait impairment, influenced by early neural correlates that are evolutionarily and developmentally conserved. For infants born preterm, early prediction of gait impairment can help guide early, more effective intervention to improve quality of life.

WHAT THIS PAPER ADDS

• Accurate prediction of toddler gait from near-term brain microstructure on DTI.• Use of machine learning analysis of neonatal neuroimaging to predict gait.• Early prediction of gait impairment to guide early treatment for children born preterm.

Corpus callosum and cerebellar vermis size in very preterm infants: Relationship to long-term neurodevelopmental outcome

BACKGROUND

The neonatal changes of corpus callosum or cerebellar volume in preterm infants have been shown to link with abnormal mentality and motor disability in early childhood. This study aims to predict the long-term neurological outcomes by measuring these changes on neonatal brain ultrasound in preterm infants.

METHODS

Our cohort consisted of infants aged below 32 weeks' gestation with very low birth body weights who completed neuro-assessments at 5 years of age. Corpus callosum or cerebellar vermis were measured at 28-30 weeks and at 37-40 weeks gestational age in premature infants with cerebral palsy (CP), mental retardation (MR) and normal control premature infants.

RESULTS

There are 12 patients in MR group, 12 in CP group and 27 patients as controls for final analysis. There was no significant difference in other factors between study groups except lower gestational age (P = 0.043) in CP group. Respiratory distress syndrome was more common in MR group (P = 0.037) and cystic periventricular leukomalacia was more common in CP group (P < 0.001) than controls. After adjusting for sex and birth body weight, the MR group had smaller cerebellar vermis area at 37-40 gestational weeks (P = 0.002) than controls. They also reduced the growth of corpus callosum area (difference = -0.12 ± 0.16, P = 0.029) and cerebellar vermis area (difference = 1.10 ± 0.44, P = 0.020) from 28 to 30 gestational weeks to 37-40 gestational weeks compared with controls (difference = 0.03 ± 0.15, 1.92 ± 0.70, respectively). In contrast, the CP group had reduced the growth of corpus callosum body (difference = -0.02 ± 0.18, P = 0.034) compared with controls (difference = 0.03 ± 0.04). They subsequently had smaller body thickness of corpus callosum (0.10 ± 0.02, P = 0.015) at 37-40 gestational weeks than controls (0.14 ± 0.04).

CONCLUSIONS

Serial monitoring corpus callosum and cerebellar vermis size in early life of very preterm babies may predict the motor or mentality neurological outcome at 5 years of age.

Postnatal Brain Growth Assessed by Sequential Cranial Ultrasonography in Infants Born <30 Weeks' Gestational Age

BACKGROUND AND PURPOSE

Brain growth in the early postnatal period following preterm birth has not been well described. This study of infants born at <30 weeks' gestational age and without major brain injury aimed to accomplish the following: 1) assess the reproducibility of linear measures made from cranial ultrasonography, 2) evaluate brain growth using sequential cranial ultrasonography linear measures from birth to term-equivalent age, and 3) explore perinatal predictors of postnatal brain growth.

MATERIALS AND METHODS

Participants comprised 144 infants born at <30 weeks' gestational age at a single center between January 2011 and December 2013. Infants with major brain injury seen on cranial ultrasonography or congenital or chromosomal abnormalities were excluded. Brain tissue and fluid spaces were measured from cranial ultrasonography performed as part of routine clinical care. Brain growth was assessed in 3 time intervals: <7, 7-27, and >27 days' postnatal age. Data were analyzed using intraclass correlation coefficients and mixed-effects regression.

RESULTS

A total of 429 scans were assessed for 144 infants. Several linear measures showed excellent reproducibility. All measures of brain tissue increased with postnatal age, except for the biparietal diameter, which decreased within the first postnatal week and increased thereafter. Gestational age of ≥28 weeks at birth was associated with slower growth of the biparietal diameter and ventricular width compared with gestational age of <28 weeks. Postnatal corticosteroid administration was associated with slower growth of the corpus callosum length, transcerebellar diameter, and vermis height. Sepsis and necrotizing enterocolitis were associated with slower growth of the transcerebellar diameter.

CONCLUSIONS

Postnatal brain growth in infants born at <30 weeks' gestational age can be evaluated using sequential linear measures made from routine cranial ultrasonography and is associated with perinatal predictors of long-term development.

Postnatal Microstructural Developmental Trajectory of Corpus Callosum Subregions and Relationship to Clinical Factors in Very Preterm Infants

Our objectives were to define the microstructural developmental trajectory of six corpus callosum subregions and identify perinatal clinical factors that influence early development of these subregions in very preterm infants. We performed a longitudinal cohort study of very preterm infants (32 weeks gestational age or younger) (N = 36) who underwent structural MRI and diffusion tensor imaging serially at four time points - before 32, 32, 38, and 52 weeks postmenstrual age. We divided the corpus callosum into six subregions, performed probabilistic tractography, and used linear mixed effects models to evaluate the influence of antecedent clinical factors on its microstructural growth trajectory. The genu and splenium demonstrated the most rapid developmental maturation, exhibited by a steep increase in fractional anisotropy. We identified several factors that favored greater corpus callosum microstructural development, including advancing postmenstrual age, higher birth weight, and college level or higher maternal education. Bronchopulmonary dysplasia, low 5-minute Apgar scores, caffeine therapy/apnea of prematurity and male sex were associated with reduced corpus callosum microstructural integrity/development over the first six months after very preterm birth. We identified a unique postnatal microstructural growth trajectory and associated clinical factor profile for each of the six corpus callosum subregions that is consistent with the heterogeneous functional role of these white matter subregions.

Biometry of the corpus callosum assessed by 3D ultrasound and its correlation to neurodevelopmental outcome in very low birth weight infants

OBJECTIVE

Several studies have shown a relation between the size of corpus callosum (CC) and outcome in preterm infants. Three-dimensional ultrasound (3D-US) offers new perspectives in cerebral imaging. To establish reference values for biometry of the CC in very low birth weight infants and to correlate these measurements to neurodevelopmental outcome at 5 years of age.

STUDY DESIGN

Forty-three preterm infants with a gestational age <32 weeks were included. Transfontanellar 3D-US measurements were obtained at nine different timepoints.

RESULTS

3D-US-based reference values for size, length, circumference and surface area of the CC could be established. Measurements at term-equivalent age showed a correlation to neurodevelopment outcome.

CONCLUSION

Reliable biometric data of the CC can be established in preterm infants by 3D-US and correlate with neurodevelopmental outcome.

Association between corpus callosum development on magnetic resonance imaging and diffusion tensor imaging, and neurodevelopmental outcome in neonates born very preterm

AIM

To characterize corpus callosum development in neonates born very preterm from early in life to term-equivalent age and its relationship with neurodevelopmental outcome at 18 months corrected age.

METHOD

In a prospective cohort of 193 neonates born preterm, 24 to 32 weeks' gestation, we used magnetic resonance imaging and diffusion tensor imaging acquired early in life (n=193) and at term-equivalent age (n=159) to measure corpus callosum development: mid-sagittal area (including corpus callosum subdivisions) and length, and fractional anisotropy from the genu and splenium. We examined the association of (1) intraventricular haemorrhage (IVH) and white matter injury (WMI) severity, and (2) neurodevelopmental outcome at 18 months corrected age with corpus callosum development.

RESULTS

Severe WMI and severe IVH were strongly associated with reduced corpus callosum area (both p<0.001) and WMI with lower fractional anisotropy (p=0.002). Mild WMI predicted smaller corpus callosum area only posteriorly; mild IVH predicted smaller area throughout. Adverse motor outcome was associated with smaller corpus callosum size in the posterior subdivision (p=0.003). Abnormal cognitive outcomes were associated with lower corpus callosum fractional anisotropy (p=0.008).

INTERPRETATION

In newborn infants born very preterm, brain injury is associated with changes in simple metrics of corpus callosum development. In this population, the development of the corpus callosum, as reflected by size and microstructure, is associated with neurodevelopmental outcomes at 18 months corrected age.

‘State-of-the-Art’ Neonatal Cranial Ultrasound

Cranial ultrasound (cUS) provides bedside imaging access to the neonatal brain. Modern scanners and the use of various acoustic windows give detail not only of the well known pathologies met in the preterm infant, but also allow assessment of more subtle aspects of normal and abnormal brain growth and development. cUS is also very helpful in the early diagnosis of the many aetiologies of neonatal encephalopathy and seizures in the term infant and the subsequent monitoring of progress of hypoxic-ischaemic brain injury. Training issues in cUS need to be addressed.

Rodent Hypoxia-Ischemia Models for Cerebral Palsy Research: A Systematic Review

Cerebral palsy (CP) is a complex multifactorial disorder, affecting approximately 2.5-3/1000 live term births, and up to 22/1000 prematurely born babies. CP results from injury to the developing brain incurred before, during, or after birth. The most common form of this condition, spastic CP, is primarily associated with injury to the cerebral cortex and subcortical white matter as well as the deep gray matter. The major etiological factors of spastic CP are hypoxia/ischemia (HI), occurring during the last third of pregnancy and around birth age. In addition, inflammation has been found to be an important factor contributing to brain injury, especially in term infants. Other factors, including genetics, are gaining importance. The classic Rice-Vannucci HI model (in which 7-day-old rat pups undergo unilateral ligation of the common carotid artery followed by exposure to 8% oxygen hypoxic air) is a model of neonatal stroke that has greatly contributed to CP research. In this model, brain damage resembles that observed in severe CP cases. This model, and its numerous adaptations, allows one to finely tune the injury parameters to mimic, and therefore study, many of the pathophysiological processes and conditions observed in human patients. Investigators can recreate the HI and inflammation, which cause brain damage and subsequent motor and cognitive deficits. This model further enables the examination of potential approaches to achieve neural repair and regeneration. In the present review, we compare and discuss the advantages, limitations, and the translational value for CP research of HI models of perinatal brain injury.

Neurodevelopmental outcome after extreme prematurity: a review of the literature

BACKGROUND

Advances in obstetric and neonatal medical care and assisted reproductive technology have increased the rates of preterm birth, decreased preterm mortality rates, and lowered the limit of viability. However, morbidity in survivors, including neurodevelopmental disabilities, has increased, especially in extremely preterm infants born at ≤25 weeks' gestation. A better understanding of the prevalence and patterns of adverse neurodevelopmental outcomes in extremely preterm infants is important for patient care, counseling of families, and research.

METHODS

The PubMed and Ovid Medline databases were searched for full text articles published between 1999 and 2013 in English that reported neurodevelopmental outcomes after extreme prematurity, and a review of identified relevant cohort studies was performed.

RESULTS

Extreme prematurity of 22 to 25 weeks' gestation is associated with an overall high mortality of ≥50%. High rates (17% to 59%) of severe neurodevelopmental disabilities occur among survivors on short-term follow-up. The rates of surviving unimpaired or minimally impaired are 6% to 20% for live-born infants at ≤25 weeks' gestation and <5% for infants born at 22 and 23 weeks' gestation. Long-term adverse outcomes after extreme prematurity include intellectual disability (5% to 36%), cerebral palsy (9% to 18%), blindness (0.7% to 9%), and deafness (2% to 4%). Milder degrees of disability involving cognition, behavior, and learning are increasingly recognized among older preterm children, teens, and young adults.

CONCLUSIONS

Infants who are born at ≤25 weeks' gestation, especially those born at 22 and 23 weeks' gestation, have a very low likelihood of surviving little or no impairment. Nearly half of surviving extremely premature infants have significant neurodevelopmental disabilities on short- and long-term follow-up. Instituting early intervention programs, providing family support, and establishing special educational school programs can pay high dividends and lead to brighter futures and, hence, help improve neurodevelopmental outcome of preterm infants.

Ultrasound measurement of the corpus callosum and neural development of premature infants

Length and thickness of 152 corpus callosa were measured in neonates within 24 hours of birth. Using ultrasonic diagnostic equipment with a neonatal brain-specific probe, corpus callosum length and thickness of the genu, body, and splenium were measured on the standard mid-sagittal plane, and the anteroposterior diameter of the genu was measured in the coronal plane. Results showed that corpus callosum length as well as thickness of the genu and splenium increased with tional age and birth weight, while other measures did not. These three factors on the standard mid-sagittal plane are therefore likely to be suitable for real-time evaluation of corpus callosum velopment in premature infants using cranial ultrasound. Further analysis revealed that thickness of the body and splenium and the anteroposterior diameter of the genu were greater in male infants than in female infants, suggesting that there are sex differences in corpus callosum size during the neonatal period. A second set of measurements were taken from 40 premature infants whose gestational age was 34 weeks or less. Corpus callosum measurements were corrected to a gestational age of 40 weeks, and infants were grouped for analysis depending on the outcome of a neonatal behavioral neurological assessment. Compared with infants with a normal neurological assessment, corpus callosum length and genu and splenium thicknesses were less in those with abnormalities, indicating that corpus callosum growth in premature infants is associated with neurobehavioral development during the early extrauterine stage.

Serial diffusion tensor images during infancy and their relationship to neuromotor outcomes in preterm infants

BACKGROUND

Even preterm infants with normal magnetic resonance imaging (MRI) results are at greater risk for neuromotor dysfunction.

OBJECTIVES

Our aim was to compare serial diffusion tensor imaging (DTI) data from preterm infants without apparent brain abnormalities on magnetic resonance imaging with those from term controls and to investigate the white matter (WM) region associated with neuromotor outcomes.

METHODS

We obtained serial DTIs from 21 preterm infants at term-equivalent age (TEA) and 1 year of corrected age. As controls, 15 term neonates and 20 newly recruited term infants aged 1 year underwent DTI. Preterm and term infants at 1 year of age were assessed with the Bayley Scales of Infant Development, second edition. Tract-based spatial statistics and regions of interest were used for analysis.

RESULTS

At TEA, the entire WM development was delayed in the preterm infants compared with the term controls, but at 1 year of age, the WM development, except for that of the corpus callosum (CC), had reached the development level of the term controls. The psychomotor developmental index was positively correlated with the fractional anisotropy (FA) in the CC (particularly in the body and splenium) at 1 year of age after correcting for gestational age, chronic lung disease, and postnatal infection.

CONCLUSIONS

The CC of the preterm infants was consistently underdeveloped compared with that of the term controls. The FA in the CC, particularly in the body and splenium at 1 year of age, well reflected the degree of motor function in infants without apparent brain abnormalities.

Persistent periventricular echogenicities in preterms are not related to smaller brains at term-equivalent age

BACKGROUND

Periventricular white matter (PWM) is particularly vulnerable in very preterm infants. Non-cystic white matter injury, known as non-cystic periventricular leukomalacia (ncPVL), is the commonest 'lesion' affecting the preterm brain. There is no consensus about whether ncPVL can be reliably identified from cerebral ultrasound (cUS) or whether there is any reliable correlate of ncPVL on cUS at term-equivalent age (TEA).

OBJECTIVE

To compare brain volumes and linear measures at TEA in infants with and without a diagnosis of ncPVL.

METHODS

Preterm infants of ≤32 weeks' gestation without major lesions were serially assessed using cUS. ncPVL was defined as PWM echogenicity comparable to the choroid plexus on two scans at least 2 weeks apart after the first postnatal week. At TEA, infants were scanned for the estimation of brain volume and ventricular and tissue dimensions. Head circumference was measured. The data were compared between those with/without ncPVL. Observer agreement was assessed using kappa statistic.

RESULTS

Of 63 eligible infants 29% had ncPVL. Significant differences were found between those with/without ncPVL for 5 min Apgar score, CRIB score, invasive ventilation rates and chronic lung disease but not for other relevant clinical data. No significant differences were found for estimated brain volume, ventricular size, corpus callosum length/thickness or central grey matter width. Intra-observer reliability was moderate (kappa = 0.51-0.56); inter-observer reliability was poor (kappa = 0.20-0.32).

CONCLUSIONS

This study indicates that an ultrasound diagnosis of ncPVL should not be used as a sole predictor of lower brain growth detectable at TEA.

Imaging of an inflammatory injury in the newborn rat brain with photoacoustic tomography

Background

The precise assessment of cerebral saturation changes during an inflammatory injury in the developing brain, such as seen in periventricular leukomalacia, is not well defined. This study investigated the impact of inflammation on locoregional cerebral oxygen saturation in a newborn rodent model using photoacoustic imaging.

Methods

1 mg/kg of lipopolysaccharide(LPS) diluted in saline or saline alone was injected under ultrasound guidance directly in the corpus callosum of P3 rat pups. Coronal photoacoustic images were carried out 24 h after LPS exposure. Locoregional oxygen saturation (SO₂) and resting state connectivity were assessed in the cortex and the corpus callosum. Microvasculature was then evaluated on cryosection slices by lectin histochemistry.

Results

Significant reduction of SO₂ was found in the corpus callosum; reduced SO₂ was also found in the cortex ipsilateral to the injection site. Seed-based functional connectivity analysis showed that bilateral connectivity was not affected by LPS exposure. Changes in locoregional oxygen saturation were accompanied by a significant reduction in the average length of microvessels in the left cortex but no differences were observed in the corpus callosum.

Conclusion

Inflammation in the developing brain induces marked reduction of locoregional oxygen saturation, predominantly in the white matter not explained by microvascular degeneration. The ability to examine regional saturation offers a new way to monitor injury and understand physiological disturbance non-invasively.

Differential vulnerability of gray matter and white matter to intrauterine growth restriction in preterm infants at 12 months corrected age

Intrauterine growth restriction (IUGR) is associated with a high risk of abnormal neurodevelopment. Underlying neuroanatomical substrates are partially documented. We hypothesized that at 12 months preterm infants would evidence specific white-matter microstructure alterations and gray-matter differences induced by severe IUGR. Twenty preterm infants with IUGR (26-34 weeks of gestation) were compared with 20 term-born infants and 20 appropriate for gestational age preterm infants of similar gestational age. Preterm groups showed no evidence of brain abnormalities. At 12 months, infants were scanned sleeping naturally. Gray-matter volumes were studied with voxel-based morphometry. White-matter microstructure was examined using tract-based spatial statistics. The relationship between diffusivity indices in white matter, gray matter volumes, and perinatal data was also investigated. Gray-matter decrements attributable to IUGR comprised amygdala, basal ganglia, thalamus and insula bilaterally, left occipital and parietal lobes, and right perirolandic area. Gray-matter volumes positively correlated with birth weight exclusively. Preterm infants had reduced FA in the corpus callosum, and increased FA in the anterior corona radiata. Additionally, IUGR infants had increased FA in the forceps minor, internal and external capsules, uncinate and fronto-occipital white matter tracts. Increased axial diffusivity was observed in several white matter tracts. Fractional anisotropy positively correlated with birth weight and gestational age at birth. These data suggest that IUGR differentially affects gray and white matter development preferentially affecting gray matter. At 12 months IUGR is associated with a specific set of structural gray-matter decrements. White matter follows an unusual developmental pattern, and is apparently affected by IUGR and prematurity combined.

A systematic review of tests to predict cerebral palsy in young children

AIM

This systematic review evaluates the accuracy of predictive assessments and investigations used to assist in the diagnosis of cerebral palsy (CP) in preschool-age children (<5 y).

METHOD

Six databases were searched for studies that included a diagnosis of CP validated after 2 years of age. The validity of the studies meeting the criteria was evaluated using the Standards for Reporting Diagnostic Accuracy criteria. Where possible, results were pooled and a meta-analysis was undertaken.

RESULTS

Nineteen out of 351 studies met the full inclusion criteria, including studies of general movements assessment (GMA), cranial ultrasound, brain magnetic resonance imaging (MRI), and neurological examination. All studies assessed high-risk populations including preterm (gestational range 23-41 wks) and low-birthweight infants (range 500-4350 g). Summary estimates of sensitivity and specificity of GMA were 98% (95% confidence interval [CI] 74-100%) and 91% (95% CI 83-93%) respectively; of cranial ultrasound 74% (95% CI 63-83%) and 92% (95% CI 81-96%) respectively; and of neurological examination 88% (95% CI 55-97%) and 87% (95% CI 57-97%) respectively. MRI performed at term corrected age (in preterm infants) appeared to be a strong predictor of CP, with sensitivity ranging in individual studies from 86 to 100% and specificity ranging from 89 to 97% There was inadequate evidence for the use of other predictive tools.

SUMMARY

This review found that the assessment with the best evidence and strength for predictive accuracy is the GMA. MRI has a good predictive value when performed at term-corrected age. Cranial ultrasound is as specific as MRI and has the advantage of being readily available at the bedside. Studies to date have focused on high-risk infants. The accuracy of these tests in low-risk infants remains unclear and requires further research.

Clinical utility of corpus callosum measurements in head sonograms of preterm infants: a cohort study

OBJECTIVE

To assess the clinical usefulness of measurement of corpus callosum (CC) size in head ultrasound (HUS) to predict short-term neurodevelopmental (ND) outcomes in preterm infants. We hypothesised that including CC measurements in routine HUS will be an additional tool for early identification of infants at risk of adverse short-term ND outcome, over and above the predictive power of perinatal morbidities.

DESIGN

Retrospective cohort study.

SETTING

Level III neonatal intensive care unit (NICU) and outpatient NICU follow-up clinic of an academic medical centre in New York City.

PARTICIPANTS

929 HUS of 502 infants with gestational age of 23-36 weeks in African-American infants were initially studied. Exclusion criteria included those who died, had gross abnormalities in HUS, infants with race other than African-American, infants with suboptimal quality of HUS, late preterm infants and infants who did not participate in ND follow-up. A total of 173 infants completed the study.

INTERVENTIONS

CC size (length and thickness) was measured in a subset of 87 infants who had routine HUS between 23 and 29 weeks (0-6 postnatal weeks). Relevant clinical variables were collected from chart reviews. ND assessments were completed in outpatient follow-up clinics. A statistical model was developed to assess the clinical utility and possible predictive value of CC measurements for adverse short-term ND outcome, while adjusting for perinatal morbidities.

PRIMARY AND SECONDARY OUTCOME MEASURES

CC size and ND status.

RESULTS

Measurements of CC size did not add substantial predictive power to predict short-term ND outcome beyond the information provided by the presence of morbidities related to prematurity.

CONCLUSIONS

No association was found between morbidities related to prematurity and short-term ND outcome and CC size in preterm infants. CC measurements in HUS early in life did not have an additional value in predicting short-term ND outcome, therefore did not seem to provide further clinical utility.

Radiologic differences in white matter maturation between preterm and full-term infants: TBSS study

BACKGROUND

Widespread white matter (WM) pathology in preterm children has been proposed.

OBJECTIVE

The purpose of this study was to investigate maturational differences of WM between preterm infants with thinning of the corpus callosum and full-term infants.

MATERIALS AND METHODS

A total of 18 preterm children and 18 full-term children were divided into three subgroups according to the corrected age at the time of diffusion tensor imaging scanning. Tract-based spatial statistics was used for assessing differences in fractional anisotropy (FA) between preterm and full-term children, and between each age-related subgroup in preterm and in full-term children.

RESULTS

In the preterm group, FA values of overall WM showed an increase with age. This trend indicates that WM maturation is a gradual occurrence during a child's first 2 years. In the full-term group, most WM structures had reached maturation at around 1 year of age; however, centrum semiovale level showed sustained maturation during the first 2 years.

CONCLUSION

Results of our study demonstrate radiologic maturational differences of WM and provide evidence of the need for therapeutic intervention within 2 years of birth to prevent specific functional impairment and to improve clinical outcome in preterm children.

Infant brain structures, executive function, and attention deficit/hyperactivity problems at preschool age. A prospective study

BACKGROUND

Neuroimaging findings have provided evidence for a relation between variations in brain structures and attention deficit/hyperactivity disorder (ADHD). However, longitudinal neuroimaging studies are typically confined to children who have already been diagnosed with ADHD. In a population-based study, we aimed to characterize the prospective association between brain structures measured during infancy and executive function and attention deficit/hyperactivity problems assessed at preschool age.

METHODS

In the Generation R Study, the corpus callosum length, the gangliothalamic ovoid diameter (encompassing the basal ganglia and thalamus), and the ventricular volume were measured in 784 6-week-old children using cranial postnatal ultrasounds. Parents rated executive functioning at 4 years using the behavior rating inventory of executive function-preschool version in five dimensions: inhibition, shifting, emotional control, working memory, and planning/organizing. Attention deficit/hyperactivity problems were assessed at ages 3 and 5 years using the child behavior checklist.

RESULTS

A smaller corpus callosum length during infancy was associated with greater deficits in executive functioning at 4 years. This was accounted for by higher problem scores on inhibition and emotional control. The corpus callosum length during infancy did not predict attention deficit/hyperactivity problem at 3 and 5 years, when controlling for the confounders. We did not find any relation between gangliothalamic ovoid diameter and executive function or Attention deficit/hyperactivity problem.

CONCLUSIONS

Variations in brain structures detectible in infants predicted subtle impairments in inhibition and emotional control. However, in this population-based study, we could not demonstrate that early structural brain variations precede symptoms of ADHD.

Cerebral motor function in very premature-at-birth adolescents: a brain stimulation exploration of kangaroo mother care effects

AIM

  Given that prematurity has deleterious effects on brain networking development beyond childhood, the study explored whether an early intervention such as Kangaroo Mother Care (KMC) in very preterm preemies could have influenced brain motor function up to adolescence.

METHODS

  Transcranial magnetic stimulation (TMS) was applied over the primary motor cortex (M1) of 39 adolescents born very prematurely (<33 weeks' gestational age, 21 having received KMC after birth, 18 Controls with no KMC) and nine adolescents born at term (>37 weeks' gestational age, >2500 g) to assess the functional integrity of motor circuits in each hemisphere (motor planning) and between hemispheres (callosal function).

RESULTS

  All TMS outcomes were similar between KMC and term adolescents, with typical values as in healthy adults, and better than in Controls. KMC adolescents presented faster conduction times revealing more efficient M1 cell synchronization (p < 0.05) and interhemispheric transfer time (p < 0.0001), more frequent inhibitory processes with a better control between hemispheres (p < 0.0001).

CONCLUSION

  The enhanced synchronization, conduction times and connectivity of cerebral motor pathways in the KMC group suggests that the Kangaroo Mother Care positively influenced the premature brain networks and synaptic efficacy up to adolescence.

High-field diffusion tensor imaging characterization of cerebral white matter injury in lipopolysaccharide-exposed fetal sheep

BACKGROUND

In gyrencephalic species such as sheep, precise anatomical and microstructural characterization of the consequences of fetal inflammation remains scarce. The goal of this study was to characterize changes in white matter (WM) structure using advanced magnetic resonance imaging (MRI) following lipopolysaccharide (LPS) exposure in the preterm-equivalent fetal sheep.

METHODS

Preterm (0.7 gestation) fetal sheep received vehicle (Sham group) or LPS (LPS group), and fetal brains were collected 10 d later for subsequent ex vivo MRI. T1-weighted (T(1)W), T2-weighted (T(2)W), and diffusion tensor imaging (DTI) data were collected.

RESULTS

Fetuses exposed to LPS exhibited reductions in WM volume and corpus callosum thickness at 10 d recovery. Characteristic patterns of diffuse and focal WM lesions (necrosis or cysts) could be identified by various T1, T2, and DTI signal changes.

CONCLUSION

Fetal LPS exposure induces a pattern of injury characterized by diffuse and focal WM injury that closely reproduces that observed clinically in preterm infants. This work provides anatomical and microstructural MRI assessment, as well as histopathological correlates, of the consequences of LPS exposure in an animal model with a WM structure similar to that of the human brain. This work will help to further our understanding of MRI changes in preterm infants.

Preterm birth and developmental problems in the preschool age. Part I: minor motor problems

Nearly half of very preterm (VP) and extremely preterm (EP) infants suffers from minor disabilities. The paper overviews the literature dealing with motor problems other than cerebral palsy (CP) during infancy and preschool age. The term "minor motor problems" indicates a wide spectrum of motor disorders other than CP; "minor" does not mean "minimal", as a relevant proportion of the preterm infants will develop academic and behavioural problems at school age. Early onset disorders consist of abnormal general movements (GMs), transient dystonia and postural instability; these conditions usually fade during the first months. They were underestimated in the past; recently, qualitative assessment of GMs using Prechtl's method has become a major item of the neurological examination. Late onset disorders include developmental coordination disorder (DCD) and/or minor neurological dysfunction (MND): both terms cover partly overlapping problems. Simple MND (MND-1) and complex MND (MND-2) can be identified and MND-2 gives a higher risk for learning and behavioural disorders. A relationship between the quality of GMs and MND in childhood has been recently described. The Touwen infant neurological examination (TINE) can reliably detect neurological signs of MND even in infancy. However, the prognostic value of these disorders requires further investigations.

A comparison of microstructural maturational changes of the corpus callosum in preterm and full-term children: a diffusion tensor imaging study

INTRODUCTION

Preterm children with thinning of the corpus callosum (CC) frequently achieve poor neurodevelopmental outcomes despite the absence of a definite brain lesion. Here, the authors compared the microstructural characteristics of the CC in preterm and full-term children using diffusion tensor imaging (DTI).

METHODS

Twenty-two preterm children with no definite focal lesion but with thinning of the CC by conventional magnetic resonance imaging and 23 age-matched full-term children were investigated by DTI. CCs were subdivided into genu, rostral body, body, isthmus, and splenium, and voxel counts (VC), fractional anisotropies (FA), and apparent diffusion coefficients (ADC) were measured in each subdivision. Eleven preterm and 11 age-matched full-term subjects underwent follow-up scanning and interval changes in these parameters for each subdivision were compared.

RESULTS

VC and FA were significantly lower in the preterm group than in the full-term group, particularly in the isthmus. Furthermore, incremental changes in VC and FA were significantly smaller in the preterm group. Differences in maturation between the two groups were more pronounced with age in all subdivisions except the splenium. At all ages, noticeable FA differences between the two groups were observed in the isthmus. For white matter tracts, the preterm group displayed lower FA and fiber number, higher ADC values than the term group.

CONCLUSIONS

The present study shows that thinning of the CC is correlated with lower FA value and that it is more pronounced in preterm children. In addition, the isthmus was found to be the most vulnerable subdivision in preterm children.

Neuroimaging biomarkers of preterm brain injury: toward developing the preterm connectome

For typically developing infants, the last trimester of fetal development extending into the first post-natal months is a period of rapid brain development. Infants who are born premature face significant risk of brain injury (e.g., intraventricular or germinal matrix hemorrhage and periventricular leukomalacia) from complications in the perinatal period and also potential long-term neurodevelopmental disabilities because these early injuries can interrupt normal brain maturation. Neuroimaging has played an important role in the diagnosis and management of the preterm infant. Both cranial US and conventional MRI techniques are useful in diagnostic and prognostic evaluation of preterm brain development and injury. Cranial US is highly sensitive for intraventricular hemorrhage (IVH) and provides prognostic information regarding cerebral palsy. Data are limited regarding the utility of MRI as a routine screening instrument for brain injury for all preterm infants. However, MRI might provide diagnostic or prognostic information regarding PVL and other types of preterm brain injury in the setting of specific clinical indications and risk factors. Further development of advanced MR techniques like volumetric MR imaging, diffusion tensor imaging, metabolic imaging (MR spectroscopy) and functional connectivity are necessary to provide additional insight into the molecular, cellular and systems processes that underlie brain development and outcome in the preterm infant. The adult concept of the "connectome" is also relevant in understanding brain networks that underlie the preterm brain. Knowledge of the preterm connectome will provide a framework for understanding preterm brain function and dysfunction, and potentially even a roadmap for brain plasticity. By combining conventional imaging techniques with more advanced techniques, neuroimaging findings will likely be used not only as diagnostic and prognostic tools, but also as biomarkers for long-term neurodevelopmental outcomes, instruments to assess the efficacy of neuroprotective agents and maneuvers in the NICU, and as screening instruments to appropriately select infants for longitudinal developmental interventions.

Corpus callosum alterations in very preterm infants: perinatal correlates and 2 year neurodevelopmental outcomes

The aim of this study was to relate altered corpus callosum (CC) integrity in 106 very preterm (VPT) infants (<30 weeks' gestational age or <1250 g birth weight) at term equivalent to perinatal predictors and neurodevelopmental outcomes at two years. T1 and diffusion magnetic resonance images were obtained. The CC was traced, and divided into six sub-regions for cross-sectional area and shape analyses. Fractional anisotropy, mean, axial and radial diffusivity were sampled within the CC, and probabilistic tractography was performed. Perinatal predictors were explored. The Bayley Scales of Infant Development (BSID-II) was administered at two years. Intraventricular hemorrhage was associated with a smaller genu and altered diffusion values within the anterior and posterior CC of VPT infants. White matter injury was associated with widespread alterations to callosal diffusion values, especially posteriorly, and radial diffusivity was particularly elevated, indicating altered myelination. Reduced CC tract volume related to lower gestational age, particularly posteriorly. Reduced posterior callosal skew was associated with postnatal corticosteroid exposure. This more circular CC was associated with delayed cognitive development. Higher diffusivity, particularly in splenium tracts, was associated with impaired motor development. This study elucidates perinatal predictors and adverse neurodevelopmental outcomes associated with altered callosal integrity in VPT infants.

Impacto do nascimento pré-termo e com baixo peso na cognição, comportamento e aprendizagem de escolares

OBJETIVO: Avaliar o impacto do nascimento pré-termo e com baixo peso no neurodesenvolvimento, na cognição e, consequentemente, na aprendizagem de crianças e adolescentes em idade escolar. MÉTODOS: Estudo transversal caso-controle de 120 escolares com idades entre seis e 15 anos, regularmente matriculados no Ensino Fundamental e pareados socioeconomicamente. Todos foram submetidos ao protocolo de avaliação neuropsicológica, neurológica e escolar. O Grupo Propósito (GP) foi formado por 60 escolares nascidos com idade gestacional <37 semanas e peso <2500g. O Grupo Controle (GC) foi composto de 24 escolares irmãos dos sujeitos GP e 36 escolares vizinhos colegas dos sujeitos GP. Entre os instrumentos utilizados estão: WISC III, Teste Guestáltico Bender, Trail Making Test, Figura Complexa de Rey, Teste Neuropsicológico Luria Nebraska-C, Escala Comportamental A2 de Rutter, Lista de Verificação Comportamental para Crianças e Adolescentes e Teste de Desempenho Escolar. A comparação entre os grupos foi feita por teste de Fisher, Mann-Whitney e ANOVA. RESULTADOS: O GP mostrou resultados desfavoráveis em coordenação viso-motora (87% do GP), desenvolvimento psicomotor geral (75%), habilidade viso-construtiva (73%), raciocínio matemático (66%), habilidade tátil-cinestésica (65%) e memória visual (60%), todos com p=0,001. O QI dos sujeitos do GP mostrou-se, na média, 10 pontos abaixo do GC. CONCLUSÕES: Os escolares nascidos pré-termo e com baixo peso apresentaram alterações funcionais cerebrais específicas, associadas aos transtornos cognitivo-comportamentais e de aprendizagem.

Intrauterine growth restriction affects the maturation of myelin

Intrauterine growth-restriction (IUGR) can lead to adverse neurodevelopmental sequelae in postnatal life. Our objective was to determine whether IUGR, induced by chronic placental insufficiency (CPI) in the guinea pig results in long-term deficits in brain myelination and could therefore contribute to altered neural function. CPI was induced by unilateral ligation of the uterine artery at mid-gestation (term~67 days of gestation; dg), producing growth-restricted (GR) foetuses (60 dg), neonates (1 week) and young adults (8 week); controls were from the unligated horn or sham-operated animals. In GR foetuses (n=8) and neonates (n=7), white matter (WM) volume was reduced (p<0.05); this reduction did not persist in young adults (n=11) however the corpus callosum width was reduced (p<0.05). Immunoreactivity (IR) for myelin basic protein (MBP), myelin-associated glycoprotein (MAG) and myelin proteolipid protein (PLP), all markers of myelinating oligodendrocytes (OL), was reduced in GR foetuses compared to controls. MBP was the most markedly affected with an abnormal retention of protein in the OL soma and a reduction of its incorporation into the myelin sheath. MAG-IR OL density was reduced (p<0.05), while the density of OLs immunoreactive for Olig-2, a transcription factor expressed throughout the entire OL lineage, was increased (p<0.05). MBP-, MAG- and PLP-IR recovered to control levels postnatally. These results suggest that IUGR transiently delays OL maturation and myelination in utero but that myelination and WM volume are restored to control levels postnatally. Long-term deficits in myelination are therefore unlikely to be the major factor underlying the altered neurological function which can be associated with IUGR.

Developmental malformation of the corpus callosum: a review of typical callosal development and examples of developmental disorders with callosal involvement

This review provides an overview of the involvement of the corpus callosum (CC) in a variety of developmental disorders that are currently defined exclusively by genetics, developmental insult, and/or behavior. I begin with a general review of CC development, connectivity, and function, followed by discussion of the research methods typically utilized to study the callosum. The bulk of the review concentrates on specific developmental disorders, beginning with agenesis of the corpus callosum (AgCC)-the only condition diagnosed exclusively by callosal anatomy. This is followed by a review of several genetic disorders that commonly result in social impairments and/or psychopathology similar to AgCC (neurofibromatosis-1, Turner syndrome, 22q11.2 deletion syndrome, Williams yndrome, and fragile X) and two forms of prenatal injury (premature birth, fetal alcohol syndrome) known to impact callosal development. Finally, I examine callosal involvement in several common developmental disorders defined exclusively by behavioral patterns (developmental language delay, dyslexia, attention-deficit hyperactive disorder, autism spectrum disorders, and Tourette syndrome).

Neuroimaging of cortical development and brain connectivity in human newborns and animal models

Significant human brain growth occurs during the third trimester, with a doubling of whole brain volume and a fourfold increase of cortical gray matter volume. This is also the time period during which cortical folding and gyrification take place. Conditions such as intrauterine growth restriction, prematurity and cerebral white matter injury have been shown to affect brain growth including specific structures such as the hippocampus, with subsequent potentially permanent functional consequences. The use of 3D magnetic resonance imaging (MRI) and dedicated postprocessing tools to measure brain tissue volumes (cerebral cortical gray matter, white matter), surface and sulcation index can elucidate phenotypes associated with early behavior development. The use of diffusion tensor imaging can further help in assessing microstructural changes within the cerebral white matter and the establishment of brain connectivity. Finally, the use of functional MRI and resting-state functional MRI connectivity allows exploration of the impact of adverse conditions on functional brain connectivity in vivo. Results from studies using these methods have for the first time illustrated the structural impact of antenatal conditions and neonatal intensive care on the functional brain deficits observed after premature birth. In order to study the pathophysiology of these adverse conditions, MRI has also been used in conjunction with histology in animal models of injury in the immature brain. Understanding the histological substrate of brain injury seen on MRI provides new insights into the immature brain, mechanisms of injury and their imaging phenotype.

Effects of preterm birth on cortical thickness measured in adolescence

Despite the extensive research into brain development after preterm birth, few studies have investigated its long-term effects on cortical thickness. The Stockholm Neonatal Project included infants between 1988 and 1993 with birth weight (BW) ≤ 1500 g. Using a previously published method, cortical thickness was estimated on T(1)-weighted 3D anatomical images acquired from 74 ex-preterm and 69 term-born adolescents (mean age 14.92 years). The cortex was significantly thinner in ex-preterm individuals in focal regions of the temporal and parietal cortices as indicated by voxel-wise t-tests. In addition, large regions around the central sulcus and temporal lobe as well as parts of the frontal and occipital lobes tended also to be thinner in the ex-preterm group. Although these results were not significant on voxel-wise tests, the spatially coherent arrangement of the thinning in ex-preterm individuals made it notable. When the group of ex-preterm individuals was divided by gestational age or BW, the thinning tended to be more pronounced in the anterior and posterior poles in those born nearer term or with a BW closer to 1500 g. These results support the notion that preterm birth is a risk factor for long-term development of cortical thickness.

Anisotropy of transcallosal motor fibres indicates functional impairment in children with periventricular leukomalacia

AIM

In children with bilateral spastic cerebral palsy (CP), periventricular leukomalacia (PVL) is commonly identified on magnetic resonance imaging. We characterized this white matter condition by examining callosal microstructure, interhemispheric inhibitory competence (IIC), and mirror movements.

METHOD

We examined seven children (age range 11y 9mo-17y 9mo, median age 15y 10mo, four females, three males) with bilateral spastic CP/PVL (Gross Motor Function Classification System level I or II, Manual Ability Classification System level I) and 12 age-matched controls (age range 11y 7mo-17y 1mo, median age 15y 6mo, seven females, five males). Fractional anisotropy of the transcallosal motor fibres (TCMF) and the corticospinal tract (CST) of both sides were calculated. The parameters of IIC (transcranial magnetic stimulation) and mirror movements were measured using a standardized clinical examination and a computer-based hand motor test.

RESULTS

Fractional anisotropy was lower in children with bilateral spastic CP/PVL regarding the TCMF, but not the left or right CST. Resting motor threshold was elevated in children with bilateral spastic CP/PVL whereas measures of IIC tended to be lower. Mirror movements were markedly elevated in bilateral spastic CP/PVL.

INTERPRETATION

This study provides new information on different aspects of motor function in children with bilateral spastic CP/PVL. Decreased fractional anisotropy of TCMF is consistent with impairment of hand motor function in children with bilateral spastic CP/PVL. The previously overlooked microstructure of the TCMF may serve as a potential indicator for hand motor function in patients with bilateral spastic CP/PVL.