Brain Growth Gains and Losses in Extremely Preterm Infants at Term.

Premature exposure to the extrauterine environment negatively affects the brains' developmental trajectory. Our aim was to determine whether extremely preterm (EPT) infants, with no evidence of focal brain lesions, show morphological brain differences when compared with term-born infants. Additionally, we investigated associations between perinatal factors and neuroanatomical alterations. Conventional magnetic resonance imaging was acquired at term-equivalent age (TEA) from 47 EPT infants born before 27 weeks of gestation, and 15 healthy, term-born controls. Automatic segmentation and voxel-based morphometry-Diffeomorphic Anatomical Registration through Exponentiated Lie algebra (DARTEL) were used. Compared with controls, EPT infants displayed global reductions in cortical and subcortical gray matter, brainstem, and an increased cerebrospinal fluid volume. Regionally, they showed decreased volumes of all brain tissues, in particular cortical gray matter. Increased volumes of cortical gray and white matter were observed in regions involved in visual processing. Increasing prematurity, intraventricular hemorrhage grade I-II, and patent ductus arteriosus ligation were associated with decreased volumes and had a particular effect on the cerebellum. Concluding, EPT infants without focal brain lesions had an altered brain growth at TEA that particularly affected the gray matter, and varied when it came to the presence of perinatal risk factors. Brain growth gains in EPT infants may be related to a longer extrauterine experience.

Review of Trackside Monitoring Solutions: From Strain Gages to Optical Fibre Sensors.

A review of recent research on structural monitoring in railway industry is proposed in this paper, with a special focus on stress-based solutions. After a brief analysis of the mechanical behaviour of ballasted railway tracks, an overview of the most common monitoring techniques is presented. A special attention is paid on strain gages and accelerometers for which the accurate mounting position on the track is requisite. These types of solution are then compared to another modern approach based on the use of optical fibres. Besides, an in-depth discussion is made on the evolution of numerical models that investigate the interaction between railway vehicles and tracks. These models are used to validate experimental devices and to predict the best location(s) of the sensors. It is hoped that this review article will stimulate further research activities in this continuously expanding field.

Sex differences in outcome and associations with neonatal brain morphology in extremely preterm children.

OBJECTIVE: To investigate sex differences in neurologic and developmental outcomes in extremely preterm (EPT) children and explore associations with neonatal brain morphology. STUDY DESIGN: A population-based cohort of infants born at <27 weeks gestation underwent magnetic resonance imaging (MRI) at term equivalent age (n = 107). Voxel-based morphometry (n = 27) and tract-based spatial statistics (n = 29) were performed in infants with normal MRI findings. Neurologic and developmental assessment (using the Bayley Scales of Infant and Toddler Development-Third Edition [BSITD-III]) was performed at 30 months corrected age (n = 91). RESULTS: EPT boys had lower mean cognitive composite scores (P = .03) and lower mean language composite scores (P = .04) compared with EPT girls. Rates of cerebral palsy were similar in the 2 sexes. No perinatal factor explained the variance in outcomes. Visual inspection of T1- and T2-weighted MRI images found that delayed myelination was found more frequently in boys, whereas cerebellar abnormalities were more common in girls. In the subgroup of children with normal MRI findings (n = 27), boys had poorer cognitive function (P = .015) and language function (P = .008), despite larger volumes of cerebellar tissue (P = .029). In boys, cerebellar volume was positively correlated with BSITD-III cognitive and motor scores (P = .04 for both). In girls, white matter volume (P = .02) and cortical gray matter volume (P = .03) were positively correlated with BSITD-III language score. At the regional level, significant correlations with outcomes were found only in girls. CONCLUSION: Cognitive and language outcomes at age 30 months were poorer in boys. Sex-related differences were observed on neonatal structural MRI, including differences in the patterns of correlations between brain volumes and developmental scores at both global and regional levels.

White matter microstructure is influenced by extremely preterm birth and neonatal respiratory factors.

AIM: The aim of this study was to investigate whether prematurity per se or perinatal risk factors explain altered brain structure after preterm birth, in extremely preterm (EPT) infants without focal brain lesions. METHODS: A population-based cohort of 58 EPT infants [gestational age (GA) <27 + 0 weeks] was examined with diffusion magnetic resonance imaging at term-equivalent age and compared with 14 term-born controls. Associations of diffusion measures with prematurity and neonatal risk factors were explored. Data were analysed with tract-based spatial statistics (TBSS) for whole-brain analysis and region-of-interest (ROI) analysis. RESULTS: Whole-brain analyses showed lower fractional anisotropy (FA) and higher mean diffusivity (MD) in several white matter (WM) tracts in the preterms, which was essentially confirmed by ROI analyses. Within the preterm GA range (23 + 0 to 26 + 6 weeks), GA at birth was not significantly associated with diffusion measures. Bronchopulmonary dysplasia predicted lower FA in the corpus callosum and right inferior longitudinal fasciculus; mechanical ventilation >2 days was predictive of higher MD in the right external capsule. CONCLUSION: White matter microstructure is influenced by preterm birth and by neonatal respiratory factors, whereas the degree of prematurity within the EPT range appears to be of less importance.

Early hyperglycemia is a risk factor for death and white matter reduction in preterm infants.

OBJECTIVE: The objective of this study was to determine whether hyperglycemia during the first week of life in extremely preterm (EPT) infants was associated with increased mortality rates and with cerebral injury, as assessed with MRI of the brain, at term-equivalent age. METHODS: All 143 EPT infants (gestational ages of <27 weeks) who were born at Karolinska University Hospital between January 2004 and December 2006 and were alive at 24 hours were eligible. Of the 118 surviving infants, 24 were excluded for various reasons. MRI was performed for the 94 included survivors at term age, with a 1.5-T system, and scans were scored for gray matter/white matter (WM) abnormalities. Of the 25 infants who died before term age, 6 were excluded because of missing glucose documentation and the remaining 19 were included. Hyperglycemia was defined as plasma glucose levels of >8.3 mmol/L. RESULTS: Hyperglycemia occurring on the first day of life was identified as an independent risk factor for death (adjusted odds ratio: 3.7 [95% confidence interval: 1.3-10.6]; P = .01). Hyperglycemia occurring on the first day of life also was a risk factor for WM reduction, as determined through MRI, at term-equivalent age (adjusted odds ratio: 3.1 [95% confidence interval: 1.0-9.2]; P = .04). CONCLUSION: In this population-based cohort of EPT infants, hyperglycemia on the first day of life was associated with increased mortality rates and brain damage, as reflected by WM reduction at term age.