Ventriculomegaly, delayed myelination, white matter hypoplasia, and "periventricular" leukomalacia: how are they related?

Acute Diffusion-Weighted Imaging Signaling Severe Periventricular Leukomalacia in Preterm Infants: Case Report and Review of Literature

Introduction: Periventricular leukomalacia occurs in up to 25% of very preterm infants resulting in adverse neurodevelopmental outcomes. In its acute phase, periventricular leukomalacia is clinically silent. Although ultrasonography is widely available, its sensitivity in the early detection of periventricular leukomalacia is low. Case Report and Published Literature: We identified a preterm infant with early diffusion-weighted imaging changes that later evolved to periventricular leukomalacia. Thirty-two cases of abnormal diffusion-weighted imaging reliably heralding severe periventricular leukomalacia in the preterm infant have been published in the literature. Notable features include the following: (1) infants were more mature preterm infants (29-36 weeks' gestation); (2) findings were often serendipitous with benign clinical courses; (3) diffusion-weighted imaging changes only were evident in the first weeks of life with later evolution to more classical abnormalities on conventional magnetic resonance imaging (MRI) or ultrasonography. Conclusion: Diffusion-weighted imaging in the first week of life may be a reliable early marker of severe periventricular leukomalacia injury in more mature preterm infants.

Prenatal exposure to air pollution is associated with structural changes in the neonatal brain

BACKGROUND

Prenatal exposure to air pollution is associated with adverse neurologic consequences in childhood. However, the relationship between in utero exposure to air pollution and neonatal brain development is unclear.

METHODS

We modelled maternal exposure to nitrogen dioxide (NO2) and particulate matter (PM2.5 and PM10) at postcode level between date of conception to date of birth and studied the effect of prenatal air pollution exposure on neonatal brain morphology in 469 (207 male) healthy neonates, with gestational age of ≥36 weeks. Infants underwent MR neuroimaging at 3 Tesla at 41.29 (36.71-45.14) weeks post-menstrual age (PMA) as part of the developing human connectome project (dHCP). Single pollutant linear regression and canonical correlation analysis (CCA) were performed to assess the relationship between air pollution and brain morphology, adjusting for confounders and correcting for false discovery rate.

RESULTS

Higher exposure to PM10 and lower exposure to NO2 was strongly canonically correlated to a larger relative ventricular volume, and moderately associated with larger relative size of the cerebellum. Modest associations were detected with higher exposure to PM10 and lower exposure to NO2 and smaller relative cortical grey matter and amygdala and hippocampus, and larger relaive brainstem and extracerebral CSF volume. No associations were found with white matter or deep grey nuclei volume.

CONCLUSIONS

Our findings show that prenatal exposure to air pollution is associated with altered brain morphometry in the neonatal period, albeit with opposing results for NO2 and PM10. This finding provides further evidence that reducing levels of maternal exposure to particulate matter during pregnancy should be a public health priority and highlights the importance of understanding the impacts of air pollution on this critical development window.

Fetal hypoxia results in sex- and cell type-specific alterations in neonatal transcription in rat oligodendrocyte precursor cells, microglia, neurons, and oligodendrocytes

BACKGROUND

Fetal hypoxia causes vital, systemic, developmental malformations in the fetus, particularly in the brain, and increases the risk of diseases in later life. We previously demonstrated that fetal hypoxia exposure increases the susceptibility of the neonatal brain to hypoxic-ischemic insult. Herein, we investigate the effect of fetal hypoxia on programming of cell-specific transcriptomes in the brain of neonatal rats.

RESULTS

We obtained RNA sequencing (RNA-seq) data from neurons, microglia, oligodendrocytes, A2B5⁺ oligodendrocyte precursor cells, and astrocytes from male and female neonatal rats subjected either to fetal hypoxia or control conditions. Substantial transcriptomic responses to fetal hypoxia occurred in neurons, microglia, oligodendrocytes, and A2B5⁺ cells. Not only were the transcriptomic responses unique to each cell type, but they also occurred with a great deal of sexual dimorphism. We validated differential expression of several genes related to inflammation and cell death by Real-time Quantitative Polymerase Chain Reaction (qRT-PCR). Pathway and transcription factor motif analyses suggested that the NF-kappa B (NFκB) signaling pathway was enriched in the neonatal male brain due to fetal hypoxia, and we verified this result by transcription factor assay of NFκB-p65 in whole brain.

CONCLUSIONS

Our study reveals a significant impact of fetal hypoxia on the transcriptomes of neonatal brains in a cell-specific and sex-dependent manner, and provides mechanistic insights that may help explain the development of hypoxic-ischemic sensitive phenotypes in the neonatal brain.

Brain Damage in the Preterm Infant: Clinical Aspects and Recent Progress in the Prevention and Treatment

Although the prevalence of brain injury and related neurodevelopmental disabilities resulting from preterm birth are major public health concerns, there are no definite neuroprotective strategies to prevent or reduce brain injury. The pattern of brain injury seen in preterm infants has evolved into more subtle lesions that are still essential to diagnose regarding neurodevelopmental outcomes. There is no specific effective method for the treatment of premature infant brain injury, and the focus of clinical treatment is still on prevention. Prevention of this injury requires insight into the pathogenesis, but many gaps exist in our understanding of how neonatal treatment procedures and medications impact cerebral hemodynamics and preterm brain injury. Many studies provide evidence about the prevention of premature infant brain injury, which is related to some drugs (such as erythropoietin, melatonin, mesenchymal stem cells, etc.). However, there are still some controversies about the quality of research and the effectiveness of therapy. This review aims to recapitulate the results of preclinical studies and provide an update on the latest developments around etiological pathways, prevention, and treatment.

Neonatal Cranial Ultrasound Findings among Infants Born Extremely Preterm: Associations with Neurodevelopmental Outcomes at 10 Years of Age

OBJECTIVE

To examine the association between neonatal cranial ultrasound (CUS) abnormalities among infants born extremely preterm and neurodevelopmental outcomes at 10 years of age.

STUDY DESIGN

In a multicenter birth cohort of infants born at <28 weeks of gestation, 889 of 1198 survivors were evaluated for neurologic, cognitive, and behavioral outcomes at 10 years of age. Sonographic markers of white matter damage (WMD) included echolucencies in the brain parenchyma and moderate to severe ventricular enlargement. Neonatal CUS findings were classified as intraventricular hemorrhage (IVH) without WMD, IVH with WMD, WMD without IVH, and neither IVH nor WMD.

RESULTS

WMD without IVH was associated with an increased risk of cognitive impairment (OR 3.5, 95% CI 1.7, 7.4), cerebral palsy (OR 14.3, 95% CI 6.5, 31.5), and epilepsy (OR 6.9; 95% CI 2.9, 16.8). Similar associations were found for WMD accompanied by IVH. Isolated IVH was not significantly associated these outcomes.

CONCLUSIONS

Among children born extremely preterm, CUS abnormalities, particularly those indicative of WMD, are predictive of neurodevelopmental impairments at 10 years of age. The strongest associations were found with cerebral palsy.

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.

Automatic segmentation and location learning of neonatal cerebral ventricles in 3D ultrasound data combining CNN and CPPN

Preterm neonates are highly likely to suffer from ventriculomegaly, a dilation of the Cerebral Ventricular System (CVS). This condition can develop into life-threatening hydrocephalus and is correlated with future neuro-developmental impairments. Consequently, it must be detected and monitored by physicians. In clinical routing, manual 2D measurements are performed on 2D ultrasound (US) images to estimate the CVS volume but this practice is imprecise due to the unavailability of 3D information. A way to tackle this problem would be to develop automatic CVS segmentation algorithms for 3D US data. In this paper, we investigate the potential of 2D and 3D Convolutional Neural Networks (CNN) to solve this complex task and propose to use Compositional Pattern Producing Network (CPPN) to enable Fully Convolutional Networks (FCN) to learn CVS location. Our database was composed of 25 3D US volumes collected on 21 preterm nenonates at the age of 35.8±1.6 gestational weeks. We found that the CPPN enables to encode CVS location, which increases the accuracy of the CNNs when they have few layers. Accuracy of the 2D and 3D FCNs reached intraobserver variability (IOV) in the case of dilated ventricles with Dice of 0.893±0.008 and 0.886±0.004 respectively (IOV = 0.898±0.008) and with volume errors of 0.45±0.42 cm³ and 0.36±0.24 cm³ respectively (IOV = 0.41±0.05 cm³). 3D FCNs were more accurate than 2D FCNs in the case of normal ventricles with Dice of 0.797±0.041 against 0.776±0.038 (IOV = 0.816±0.009) and volume errors of 0.35±0.29 cm³ against 0.35±0.24 cm³ (IOV = 0.2±0.11 cm³). The best segmentation time of volumes of size 320×320×320 was obtained by a 2D FCN in 3.5±0.2 s.

Fetal brain tissue characterization at 1.5 T using STrategically Acquired Gradient Echo (STAGE) imaging

OBJECTIVES

To estimate human fetal brain MRI tissue properties including apparent T₁ (T_1app) and apparent proton density (PD_app) by using a rapid multi-contrast acquisition protocol called STrategically Acquired Gradient Echo (STAGE) imaging.

METHODS

STAGE data were collected using two flip angles (15° and 60°, with a TR = 600 ms) for 30 pregnant women at 1.5 T (15 healthy controls: gestational age (GA) range 19 + 1/7 weeks to 34 + 5/7 weeks; 11 abnormal subjects with ventriculomegaly: GA range 21 + 5/7 weeks to 31 + 5/7 weeks; 4 subjects with other abnormalities). Both T_1app and PD_app maps of the fetal brain were calculated from the STAGE data. A region-of-interest-based approach was used to measure T_1app and PD_app in the subplate/intermediate zone (SP/IZ), cortical plate (CP), and cerebrospinal fluid (CSF) in the fetal brain.

RESULTS

The ratios of T_1appSP/IZ/T_1appCP and PD_appSP/IZ/PD_appCP were larger than unity while T_1appSP/IZ/T_1appCSF and PD_appSP/IZ/PD_appCSF were both less than unity.

CONCLUSIONS

STAGE imaging provides a potential practical approach to estimate multi-parametric properties of the human fetal brain.

KEY POINTS

• STAGE is feasible in measuring fetal brain tissue properties. • Water content in cortical plate and subplate/intermediate zone approaches that of cerebrospinal fluid in early gestational ages.

Limited developmental neurotoxicity from neonatal inhalation exposure to diesel exhaust particles in C57BL/6 mice

Background

Recent epidemiological studies indicate early-life exposure to pollution particulate is associated with adverse neurodevelopmental outcomes. The need is arising to evaluate the risks conferred by individual components and sources of air pollution to provide a framework for the regulation of the most relevant components for public health protection. Previous studies in rodent models have shown diesel particulate matter has neurotoxic potential and could be a health concern for neurodevelopment. The present study shows an evaluation of pathological and protracted behavioral alterations following neonatal exposure to aerosolized diesel exhaust particles (NIST SRM 1650b). The particular behavioral focus was on temporal control learning, a broad and fundamental cognitive domain in which reward delivery is contingent on a fixed interval schedule. For this purpose, C57BL/6 J mice were exposed to aerosolized NIST SRM 1650b, a well-characterized diesel particulate material, from postnatal days 4–7 and 10–13, for four hours per day. Pathological features, including glial fibrillary-acidic protein, myelin basic protein expression in the corpus callosum, and ventriculomegaly, as well as learning alterations were measured to determine the extent to which NIST SRM 1650b would induce developmental neurotoxicity.

Results

Twenty-four hours following exposure significant increases in glial-fibrillary acidic protein (GFAP) in the corpus callosum and cortex of exposed male mice were present. Additionally, the body weights of juvenile and early adult diesel particle exposed males were lower than controls, although the difference was not statistically significant. No treatment-related differences in males or females on overall locomotor activity or temporal learning during adulthood were observed in response to diesel particulate exposure.

Conclusion

While some sex and regional-specific pathological alterations in GFAP immunoreactivity suggestive of an inflammatory reaction to SRM 1650b were observed, the lack of protracted behavioral and pathological deficits suggests further clarity is needed on the developmental effects of diesel emissions prior to enacting regulatory guidelines.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0287-8) contains supplementary material, which is available to authorized users.

Three-dimensional ultrasound cranial imaging and early neurodevelopment in preterm growth-restricted infants

AIM

Fetal growth restriction (FGR) is associated with increased perinatal morbidity, mortality and long-term neurodevelopmental sequelae. The objective of this study was to examine whether information about early neurodevelopmental deficits was evident using three-dimensional head ultrasound and developmental assessments in preterm infants with FGR, compared with appropriate for gestational age (AGA) infants in the early post-natal period.

METHODS

Twenty preterm FGR infants weighing <10th centile and born between 28 and 32 weeks were compared with age-matched AGA infants. In the second post-natal week after birth, we used three-dimensional ultrasound to assess cerebral ventricular volumes. Prechtl General Movement Assessments were performed at 4-6 weeks after birth. Test of Infant Motor Performance (TIMP) to measure functional motor behaviour was performed at 4-6 and 12-14 weeks corrected age.

RESULTS

There was no statistically significant difference in the combined cerebral ventricular volume between the two groups (FGR, 0.81 ± 0.42 vs. AGA 0.72 ± 0.38 cm³ , P = 0.4). The TIMP assessment at 12-14 week term corrected demonstrated lower scores (worse performance) in FGR infants compared with the AGA cohort (regression coefficient: -7.74 (95% CI -16.06, 0.57); P = 0.07). We observed a significant correlation between greater ventricular volume and lower TIMP scores in the cohorts separately and also overall (FGR, r = -0.5, P = 0.06 vs. AGA, r = -0.62, P = 0.007 and overall, r = -0.53, P = 0.001).

CONCLUSION

Ultrasound in the early weeks may be useful to detect the neuropathology which could then mediate functional consequences.

Cranial Sonography in Preterm Infants with Short Review of Literature

Background:

Premature newborn infants are exposed to a wide spectrum of brain lesions which are clinically silent supporting a possible role of cerebral ultrasound screening. Aim of the study is to describe the pattern of cranial ultrasound abnormalities in preterm infants defining the short term and long term neurologic outcomes.

Material and Methods:

A hospital-based bedside cranial ultrasound was carried out at day 1, 3, 7 and follow-up scan at 3-6 months in the Department of Radio-diagnosis.

Results:

One hundred infants were included. The different abnormalities detected in cranial ultrasound of premature newborn infants include hydrocephalus in 12%, intracranial hemorrhage in 6%, brain edema in 6%, periventricular leukomalacia in 2%, choroid plexus cyst in 1%, intraventricular septa in 1% and colocephaly in 1%.

Conclusion:

Gestational age, newborn birth weight and neurologic symptoms were the most important risk factors for detecting brain lesions. The main purpose of cranial ultrasound was the demonstration or exclusion of an intracranial hemorrhage in a preterm neonate.

Clinical Risk Factors for Punctate White Matter Lesions on Early Magnetic Resonance Imaging in Preterm Newborns

OBJECTIVE

To identify clinical risk factors for punctate white matter lesions (PWML) on early magnetic resonance imaging (MRI) in 2 cohorts of newborns born extremely preterm in different neonatal centers.

STUDY DESIGN

A total of 250 newborns born preterm at less than 28 weeks of gestation (mean 26.4 ± 1.1 weeks) with an early MRI were identified from 2 neonatal centers, in Vancouver, Canada (cohort A, n = 100) and Utrecht, the Netherlands (cohort B, n = 150). Cohort A was imaged as part of a prospective research study and cohort B was imaged as part of routine clinical care. PWML were defined as cluster type foci of hyperintensity on T1-weighted imaging and were identified at a mean postmenstrual age of 31.1 (±1.9) weeks. Multivariable analysis was used to identify clinical factors predictive of PWML.

RESULTS

Cluster type PWML were found in 47 newborns born extremely preterm (18.8%) and were more common in cohort A (32%) than in cohort B (10%). Newborns in cohort A generally were sicker than those in cohort B. Multivariable analyses revealed that greater birth weight (B = 0.002; P < .02), grade II-III intraventricular hemorrhage (B = 0.83; P < .02), and cohort A (B = 1.34; P < .0001) were independent predictors of PWML.

CONCLUSION

Several risk factors for PWML on early MRI were identified. The interaction among birth weight, intraventricular hemorrhage, and other aspects of postnatal illness as risk factors for PWML warrants further investigation in newborns born extremely preterm and may help to identify modifiable risk factors for PWML.

Ventriculomegaly in very-low-birthweight infants with Down syndrome

AIM

The prevalence of Down syndrome in infants with fetal ventriculomegaly is 5% to 10%; however, the converse, the prevalence of cerebral ventriculomegaly in live-born infants with Down syndrome, is not well established. Because cranial ultrasounds are performed on most very-low-birthweight (VLBW) infants (birthweight <1500g), our aim was to examine ultrasound abnormalities of VLBW infants to determine prevalence of ventriculomegaly and intraventricular hemorrhage (IVH) in VLBW infants with Down syndrome, and whether VLBW infants with Down syndrome are at higher risk for cranial ultrasound abnormalities, compared with the already elevated risk in other VLBW infants.

METHOD

This study comprised retrospective analysis of data from Pediatrix BabySteps Clinical Data Warehouse. The study population consisted of 121 736 VLBW infants (61 869 males, 59 867 females), born between 1996 and 2013, of whom 441 had Down syndrome (233 males, 208 females; mean gestational age 30wks, standard deviation [SD] 2.8wks). Logistic regression was used to calculate odds of ventriculomegaly and IVH for Down syndrome.

RESULTS

Prevalence of ventriculomegaly in Down syndrome was 5.2% compared with 0.8% in other VLBW infants. Multivariate analysis indicated 5.8× odds (95% confidence interval [CI] 3.4-9.7) of ventriculomegaly in Down syndrome and 0.9× odds (95% CI 0.7-1.1) of IVH for Down syndrome.

INTERPRETATION

Very preterm infants with Down syndrome are at increased risk for ventriculomegaly (but not for IVH) compared with other infants born very preterm.

Quantitative analysis of cranial ultrasonographic periventricular echogenicity in relation to early neuromotor development in preterm infants

BACKGROUND

Periventricular white matter (WM) hyperechoic flares that do not evolve into cystic lesion(s) are frequently encountered on cranial ultrasonography (CUS) of preterm infants. Subjective interpretation of its presence, however, is challenging and its association with maturation and neurodevelopment remains undefined.

OBJECTIVES

To determine the relationship between quantitative WM echogenicity and postnatal and postmenstrual ages and the relationship between quantitative WM echogenicity and neuromotor development at term equivalent.

METHODS

We measured the mean pixel brightness intensity at the frontoparietal and parieto-occipital WM, choroid plexus and calvarium bone on sequential neonatal CUS scans of preterm infants born at <34 weeks gestation. The relative echogenicity (RE) was derived by dividing the mean WM echogenicity to that of the choroid plexus (RE(CP)) or bone (RE(BN)). The Lacey Assessment of the Preterm Infant was administered before discharge.

RESULTS

58 preterm infants (the mean gestational age 30.6±2.3 weeks and the mean birth weight 1211.9±224.7 g) were included. The RE(CP) of the frontoparietal WM decreased significantly with advancing postnatal and postmenstrual ages (r=-0.4, p<0.0001). The RE(BN) values of the frontoparietal and parieto-occipital WM during intermediate and late predischarge CUS studies, respectively, were significantly associated with neuromotor status at term (p<0.05). The RE(CP) and RE(BN) measured during the first week of life were not associated with neuromotor status at term.

CONCLUSIONS

Quantitative measurements of the periventricular WM echogenicity are feasible in neonatal CUSs of premature infants and may reflect microstructural developmental changes. An optimal echogenicity quantification technique and its correlation with long-term outcome remain to be determined.

Developmental neurotoxicity of inhaled ambient ultrafine particle air pollution: Parallels with neuropathological and behavioral features of autism and other neurodevelopmental disorders

Accumulating evidence from both human and animal studies show that brain is a target of air pollution. Multiple epidemiological studies have now linked components of air pollution to diagnosis of autism spectrum disorder (ASD), a linkage with plausibility based on the shared mechanisms of inflammation. Additional plausibility appears to be provided by findings from our studies in mice of exposures from postnatal day (PND) 4-7 and 10-13 (human 3rd trimester equivalent), to concentrated ambient ultrafine (UFP) particles, considered the most reactive component of air pollution, at levels consistent with high traffic areas of major U.S. cities and thus highly relevant to human exposures. These exposures, occurring during a period of marked neuro- and gliogenesis, unexpectedly produced a pattern of developmental neurotoxicity notably similar to multiple hypothesized mechanistic underpinnings of ASD, including its greater impact in males. UFP exposures induced inflammation/microglial activation, reductions in size of the corpus callosum (CC) and associated hypomyelination, aberrant white matter development and/or structural integrity with ventriculomegaly (VM), elevated glutamate and excitatory/inhibitory imbalance, increased amygdala astrocytic activation, and repetitive and impulsive behaviors. Collectively, these findings suggest the human 3rd trimester equivalent as a period of potential vulnerability to neurodevelopmental toxicity to UFP, particularly in males, and point to the possibility that UFP air pollution exposure during periods of rapid neuro- and gliogenesis may be a risk factor not only for ASD, but also for other neurodevelopmental disorders that share features with ASD, such as schizophrenia, attention deficit disorder, and periventricular leukomalacia.

Cognitive impairment in a young marmoset reveals lateral ventriculomegaly and a mild hippocampal atrophy: a case report

The number of studies that use the common marmoset (Callithrix jacchus) in various fields of neurosciences is increasing dramatically. In general, animals enter the study when their health status is considered satisfactory on the basis of classical clinical investigations. In behavioral studies, variations of score between individuals are frequently observed, some of them being considered as poor performers or outliers. Experimenters rarely consider the fact that it could be related to some brain anomaly. This raises the important issue of the reliability of such classical behavioral approaches without using complementary imaging, especially in animals lacking striking external clinical signs. Here we report the case of a young marmoset which presented a set of cognitive impairments in two different tasks compared to other age-matched animals. Brain imaging revealed a patent right lateral ventricular enlargement with a mild hippocampal atrophy. This abnormality could explain the cognitive impairments of this animal. Such a case points to the importance of complementing behavioral studies by imaging explorations to avoid experimental bias.

Treatment of posthemorrhagic ventricular dilation in preterm infants: a systematic review and meta-analysis of outcomes and complications

OBJECT The optimal clinical management of intraventricular hemorrhage (IVH) and posthemorrhagic ventricular dilation (PHVD)/posthemorrhagic hydrocephalus (PHH) in premature infants remains unclear. A common approach involves temporary treatment of hydrocephalus in these patients with a ventriculosubgaleal shunt (VSGS), ventricular access device (VAD), or external ventricular drain (EVD) until it becomes evident that the patient needs and can tolerate permanent CSF diversion (i.e., ventriculoperitoneal shunt). The present systematic review and meta-analysis aimed to provide a robust and comprehensive summary of the published literature regarding the clinical outcomes and complications of these 3 techniques as temporizing measures in the management of prematurity-related PHVD/PHH. METHODS The authors searched MEDLINE, EMBASE, CINAHL, Google Scholar, and the Cochrane Library for studies published through December 2013 on the use of VSGSs, VADs, and/or EVDs as temporizing devices for the treatment of hydrocephalus following IVH in the premature neonate. Data pertaining to patient demographic data, study methods, interventions, and outcomes were extracted from eligible articles. For each of the 3 types of temporizing device, the authors performed meta-analyses examining 6 outcomes of interest, which were rates of 1) obstruction; 2) infection; 3) arrest of hydrocephalus (i.e., permanent shunt independence); 4) mortality; 5) good neurodevelopmental outcome; and 6) revision. RESULTS Thirty-nine studies, representing 1502 patients, met eligibility criteria. All of the included articles were observational studies; 36 were retrospective and 3 were prospective designs. Nine studies (n = 295) examined VSGSs, 24 (n = 962) VADs, and 9 (n = 245) EVDs. Pooled rates of outcome for VSGS, VAD, and EVD, respectively, were 9.6%, 7.3%, and 6.8% for obstruction; 9.2%, 9.5%, and 6.7% for infection; 12.2%, 10.8%, and 47.3% for revision; 13.9%, 17.5%, and 31.8% for arrest of hydrocephalus; 12.1%, 15.3%, and 19.1% for death; and 58.7%, 50.1%, and 56.1% for good neurodevelopmental outcome. CONCLUSIONS This study provides robust estimates of outcomes for the most common temporizing treatments for IVH in premature infants. With few exceptions, the range of outcomes was similar for VSGS, VAD, and EVD.

Antecedents and correlates of visual field deficits in children born extremely preterm

AIM

We sought to identify the antecedents and correlates of visual field deficits (VFDs) at age 2 years among infants born before the 28th week of gestation.

METHODS

The visual fields of 1023 infants were assessed by confrontation at age 2 years. We compared the ante-and postnatal characteristics and exposures of the 65 infants with a VFD to their peers who did not have a VFD. We used time-oriented logistic regression risk models to assess the associations of potential antecedents and correlates with a VFD.

RESULTS

In the final regression model, VFD was associated with maternal consumption of aspirin during the current pregnancy, recurring/persistent acidemia during the first 3 postnatal days, cerebral ventriculomegaly seen on neonatal ultrasound, prethreshold retinopathy of prematurity (ROP), and supplemental oxygen and ventilator dependence at 36 weeks post-menstrual age. Birth before the 27th week was also associated with increased risk, but its significance was diminished by the addition of postnatal variables.

CONCLUSION

In this sample of extremely preterm born infants, antenatal as well as early and late postnatal characteristics and exposures are associated with an increased risk of having a VFD. Our study adds to our knowledge about the complex etiology of visual deficits of prematurity, and supports a multifactorial cause of these deficits.

Correlation of quantitative texture analysis of cranial ultrasound with later neurobehavior in preterm infants

The purpose of the study was to evaluate the association between a quantitative texture analysis of early neonatal brain ultrasound images and later neurobehavior in preterm infants. A prospective cohort study including 120 preterm (<33 wk of gestational age) infants was performed. Cranial ultrasound images taken early after birth were analyzed in six regions of interest using software based on texture analysis. The resulting texture scores were correlated with the Neonatal Behavioural Assessment Scale (NBAS) at term-equivalent age. The ability of texture scores, in combination with clinical data and standard ultrasound findings, to predict the NBAS results was evaluated. Texture scores were significantly associated with all but one NBAS domain and better predicted NBAS results than clinical data and standard ultrasound findings. The best predictive value was obtained by combining texture scores with clinical information and ultrasound standard findings (area under the curve = 0.94). We conclude that texture analysis of neonatal cranial ultrasound-extracted quantitative features that correlate with later neurobehavior has a higher predictive value than the combination of clinical data with abnormalities in conventional cranial ultrasound.

The potential for cell-based therapy in perinatal brain injuries

Perinatal brain injuries are a leading cause of cerebral palsy worldwide. The potential of stem cell therapy to prevent or reduce these impairments has been widely discussed within the medical and scientific communities and an increasing amount of research is being conducted in this field. Animal studies support the idea that a number of stem cells types, including cord blood and mesenchymal stem cells have a neuroprotective effect in neonatal hypoxia-ischemia. Both these cell types are readily available in a clinical setting. The mechanisms of action appear to be diverse, including immunomodulation, activation of endogenous stem cells, release of growth factors, and anti-apoptotic effects. Here, we review the different types of stem cells and progenitor cells that are potential candidates for therapeutic strategies in perinatal brain injuries, and summarize recent preclinical and clinical studies.

Demyelination initiated by oligodendrocyte apoptosis through enhancing endoplasmic reticulum-mitochondria interactions and Id2 expression after compressed spinal cord injury in rats

BACKGROUND

Demyelination is one of the most important pathological factors of spinal cord injury. Oligodendrocyte apoptosis is involved in triggering demyelination. However, fewer reports on pathological changes and mechanism of demyelination have been presented from compressed spinal cord injury (CSCI). The relative effect of oligodendrocyte apoptosis on CSCI-induced demyelination and the mechanism of apoptosis remain unclear.

AIMS

In this study, a custom-designed model of CSCI was used to determine whether or not demyelination and oligodendrocyte apoptosis occur after CSCI. The pathological changes in axonal myelinated fibers were investigated by osmic acid staining and transmission electron microscopy. Myelin basic protein (MBP), which is used in myelin formation in the central nervous system, was detected by immunofluorescence and Western blot assays. Oligodendrocyte apoptosis was revealed by in situ terminal-deoxytransferase-mediated dUTP nick-end labeling. To analyze the mechanism of oligodendrocyte apoptosis, we detected caspase-12 [a representative of endoplasmic reticulum (ER) stress], cytochrome c (an apoptotic factor and hallmark of mitochondria), and inhibitor of DNA binding 2 (Id2, an oligodendrocyte lineage gene) by immunofluorescence and Western blot assays.

RESULTS

The custom-designed model of CSCI was successfully established. The rats were spastic, paralyzed, and incontinent. The Basso, Beattie, and Bresnahan (BBB) locomotor rating scale scores were decreased as time passed. The compressed spinal cord slices were ischemic. Myelin sheaths became swollen and degenerative; these sheaths were broken down as time passed after CSCI. MBP expression was downregulated after CSCI and consistent with the degree of demyelination. Oligodendrocyte apoptosis occurred at 1 day after CSCI and increased as caspase-12 expression was enhanced and cytochrome c was released. Id2 was distributed widely in the white matter. Id2 expression increased with time after CSCI.

CONCLUSION

Demyelination occurred after CSCI and might be partly caused by oligodendrocyte apoptosis, which was positively correlated with ER-mitochondria interactions and enhanced Id2 expression after CSCI in rats.

Autism spectrum disorder is associated with ventricular enlargement in a low birth weight population

OBJECTIVE

To determine the relation of neonatal cranial ultrasound abnormalities to autism spectrum disorders (ASD) in low birth weight (LBW) adult survivors, a population at increased ASD risk.

STUDY DESIGN

This is a secondary analysis of a prospectively-followed regional birth cohort of 1105 LBW infants systematically screened for perinatal brain injury with cranial ultrasound in the first week of life and later assessed for ASD using a two-stage process [screening at age 16 years (n = 623) followed by diagnostic assessment at age 21 years of a systematically selected subgroup of those screened (n = 189)]; 14 cases of ASD were identified. For this analysis, cranial ultrasound abnormalities were defined as ventricular enlargement (indicative of diffuse white matter injury), parenchymal lesions (indicative of focal white matter injury), and isolated germinal matrix/intraventricular hemorrhage.

RESULTS

Compared with no cranial ultrasound abnormalities, any type of white matter injury (ventricular enlargement and/or parenchymal lesion) tripled the risk for screening positively for ASD [3.0 (2.2, 4.1)]. However, the risk of being diagnosed with ASD depended on type of white matter injury. With ventricular enlargement, the risk of ASD diagnosis was almost seven-fold that of no cranial ultrasound abnormality [6.7 (2.3, 19.7)], and no elevated risk was found for parenchymal lesion without ventricular enlargement [1.8 (0.2, 13.6)]. Isolated germinal matrix/intraventricular hemorrhage did not increase risk for a positive ASD screen or diagnosis.

CONCLUSION

In LBW neonates, cranial ultrasound evidence of ventricular enlargement is a strong and significant risk factor for subsequent development of rigorously-diagnosed ASD.

Ethyl pyruvate protects against lipopolysaccharide-induced white matter injury in the developing rat brain

The neuroprotective effects of ethyl pyruvate (EP) have been proved in several brain injury models, yet very little is known about its action on neonatal white matter injury. To investigate the effect of EP on white matte damage, a stereotactic intracerebral injection of lipopolysaccharide (LPS, 1mg/kg) was performed on postnatal day 5 Sprague-Dawley rat pups, and EP was administrated intraperitoneally at a dose of 40mg/kg immediately, 1h and 12h after LPS exposure. Significantly, treatment with EP reduced LPS-induced ventricle dilation, loss of O4+ and O1+ oligodendrocytes, apoptosis of oligodendrocytes, and hypomyelination. The protective effect of EP was associated with suppressed inflammatory responses, indicated by the inhibition of activation of microglia and astrocytes, as well as the decreased expression of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) in rat brains. Also, EP prevented the elevation of cleaved caspase-3 in periventricular white matter tissue after LPS insult. Taken together, these results suggest that EP confers potent protection against LPS-induced white matter injury via its anti-inflammatory and anti-apoptotic properties.

Increased number of cerebellar granule cells and astrocytes in the internal granule layer in sheep following prenatal intra-amniotic injection of lipopolysaccharide

Chorioamnionitis is an important problem in perinatology today, leading to brain injury and neurological handicaps. However, there are almost no data available regarding chorioamnionitis and a specific damage of the cerebellum. Therefore, this study aimed at determining if chorioamnionitis causes cerebellar morphological alterations. Chorioamnionitis was induced in sheep by the intra-amniotic injection of lipopolysaccharide (LPS) at a gestational age (GA) of 110 days. At a GA of 140 days, we assessed the mean total and layer-specific volume and the mean total granule cell (GCs) and Purkinje cell (PC) number in the cerebelli of LPS-exposed and control animals using high-precision design-based stereology. Astrogliosis was assessed in the gray and white matter (WM) using a glial fibrillary acidic protein staining combined with gray value image analysis. The present study showed an unchanged volume of the total cerebellum as well as the molecular layer, outer and inner granular cell layers (OGL and IGL, respectively), and WM. Interestingly, compared with controls, the LPS-exposed brains showed a statistically significant increase (+20.4%) in the mean total number of GCs, whereas the number of PCs did not show any difference between the two groups. In addition, LPS-exposed animals showed signs of astrogliosis specifically affecting the IGL. Intra-amniotic injection of LPS causes morphological changes in the cerebellum of fetal sheep still detectable at full-term birth. In this study, changes were restricted to the inner granule layer. These cerebellar changes might correspond to some of the motor or non-motor deficits seen in neonates from compromised pregnancies.

The association between proinflammatory cytokine polymorphisms and cerebral palsy in very preterm infants

Cerebral palsy (CP) is a nonprogressive motor disorder caused by white matter damage in the developing brain and is often accompanied with cognitive and sensory disabilities. The risk of CP is higher among infants born preterm than in more mature infants. Intrauterine infection/inflammation, activation of the cytokine network and elevated levels of proinflammatory cytokines in neonatal blood or in amniotic fluid to which the preterm infant is exposed, has been identified as the most common cause of preterm delivery, periventricular leukomalacia (PVL) and CP. The aim of our study was to evaluate the possible association of four TNFα promoter single nucleotide polymorphisms (SNPs) (-1031 T/C, -857 C/T, -308 G/A and -238 G/A), two IL1β SNPs (-511 C/T and +3954 C/T) and one IL6 (-174 C/G) polymorphism with susceptibility to CP in very preterm infants. Statistically significant association between TNFα -1031 T/C high expression genotypes (TC and CC) (OR, 2.339; p=0.016) as well as between TNFα -1031 C high expression allele (OR, 2.065; p=0.013) and risk of CP was observed. In addition, statistically significant association was found between TNFα TC, CC, GG, GG -1031/-857/-308/-238 genotypes combination (OR, 3.286; p=0.034) and risk of CP. Statistically significant association between IL1β TT, CC -511/+3954 genotypes combination and risk of CP (OR, 4.000; p=0.027) was also found. In CP patients with cystic PVL (cPVL) statistically significant association was found between TNFα -1031 T/C high expression genotypes (TC and CC) (OR, 2.361; p=0.038), IL1β -511 C/T high expression genotype TT (OR, 3.215; p=0.030) as well as IL1β -511 T high expression allele (OR, 1.956; p=0.019) and risk of CP. Statistically significant association was also found in patients with cPVL between TNFα TC, CC, GG, GG -1031/-857/-308/-238 genotypes combination (OR, 4.107; p=0.024), as well as IL1β TT, CC -511/+3954 genotypes combination (OR, 7.333; p=0.005) and risk of CP. Our results suggest the role of TNFα and IL1β polymorphisms which have previously been associated with higher circulating levels of these cytokines in genetic susceptibility to white matter damage and consequently CP in very preterm infants.

Neuron-oligodendrocyte myelination co-culture derived from embryonic rat spinal cord and cerebral cortex

An in vitro myelination model derived from rat central nervous system (CNS) remains to be established. Here, we describe a simple and reproducible myelination culture method using dissociated neuron-oligodendrocyte (OL) co-cultures from either the embryonic day 16 (E16) rat spinal cord or cerebral cortex. The dissociated cells are plated directly on poly-L-lysine-coated cover slips and maintained in a modified myelination medium that supports both OL and neuron differentiation. The spinal cord derived OL progenitor cells develop quickly into myelin basic protein (MBP)+ mature OLs and start to myelinate axons around 17 days in vitro (DIV17). Myelination reaches its peak around six weeks (DIV40) and the typical nodes of Ranvier are revealed by paranodal proteins Caspr and juxaparanodal protein Kv1.2 immunoreactivity. Electron microscopy (EM) shows typical myelination cytoarchitecture and synaptic organization. In contrast, the cortical-derived co-culture requires triiodothyronine (T3) in the culture medium for myelination. Finally, either hypomyelination and/or demyelination can be induced by exposing proinflammatory cytokines or demyelinating agents to the co-culture, suggesting the feasibility of this modified in vitro myelination model for myelin-deficit investigation.

Animal models of periventricular leukomalacia

Periventricular leukomalacia, specifically characterized as white matter injury, in neonates is strongly associated with the damage of pre-myelinating oligodendrocytes. Clinical data suggest that hypoxia-ischemia during delivery and intrauterine or neonatal infection-inflammation are important factors in the etiology of periventricular leukomalacia including cerebral palsy, a serious case exhibiting neurobehavioral deficits of periventricular leukomalacia. In order to explore the pathophysiological mechanisms of white matter injury and to better understand how infectious agents may affect the vulnerability of the immature brain to injury, novel animal models have been developed using hypoperfusion, microbes or bacterial products (lipopolysaccharide) and excitotoxins. Such efforts have developed rat models that produce predominantly white matter lesions by adopting combined hypoxia-ischemia technique on postnatal days 1-7, in which unilateral or bilateral carotid arteries of animals are occluded (ischemia) followed by 1-2 hour exposure to 6-8% oxygen environment (hypoxia). Furthermore, low doses of lipopolysaccharide that by themselves have no adverse-effects in 7-day-old rats, dramatically increase brain injury to hypoxic-ischemic challenge, implying that inflammation sensitizes the immature central nervous system. Therefore, among numerous models of periventricular leukomalacia, combination of hypoxia-ischemia-lipopolysaccharide might be one of the most-acceptable rodent models to induce extensive white matter injury and ensuing neurobehavioral deficits for the evaluation of candidate therapeutics.

The relationship between early concentrations of 25 blood proteins and cerebral white matter injury in preterm newborns: the ELGAN study

OBJECTIVE

To evaluate whether concentrations of inflammation-related proteins are elevated in the blood of preterm newborns who develop cerebral white matter damage.

STUDY DESIGN

We measured 25 proteins in blood collected on days 1, 7, and 14 from 939 infants born before the 28th week of gestation. Brain ultrasound scans were read by at least two sonologists, who agreed on the presence or absence of lesions. A protein concentration was considered elevated if it was in the highest quartile for gestational age and the day on which the specimen was collected.

RESULTS

In time-oriented models, elevated concentrations of vascular endothelial growth factor receptor 1, serum amyloid A, and macrophage inflammatory protein 1β on day 1 and interleukin-8 on day 7 were associated with increased risk of ventriculomegaly. Elevated concentrations of macrophage inflammatory protein 1β on day 1 and intercellular adhesion molecule 1 on day 7 were associated with increased risk of an echolucent lesion. Infants with elevated concentrations of inflammation-related proteins on two separate days were at significantly increased risk for ventriculomegaly, but at only modestly increased risk for an echolucent lesion.

CONCLUSIONS

Concentrations of inflammation-related proteins in the circulation in the first days after preterm birth provide information about the risk of sonographic white matter damage. The inflammatory process might begin in utero.

Total brain white matter is a major determinant of IQ in adolescents born preterm

OBJECTIVE

In preterm infants, white matter (WM) abnormalities detected on magnetic resonance imaging (MRI) at term-age are associated with early developmental delay. We set out to study this association in adolescents born pre-term, by examining intellectual outcome in relation to markers of brain injury, focusing on the effects of WM reduction.

METHODS

Seventy-nine participants were recruited and assessed at a mean age of 16 years: 49 adolescents born preterm (<32 weeks' gestation) with a wide spectrum of brain injuries (including 22 with no identifiable brain injury at birth) and 30 term-born controls. Data collected included: brain MRI scans, full-scale intelligence quotient (IQ) scores, educational attainments, and behavioral scores. Measures of WM reduction included total volume, cross-sectional area of the corpus callosum (CC), and ventricular dilatation. Cerebellar volumes and neuroradiological ratings were also included.

RESULTS

WM volume and IQ were reduced in the preterm groups (both with and without brain injury). Total WM volume and CC area jointly explained 70% of IQ variance in the adolescents born preterm, irrespective of the presence or severity of brain abnormalities detected at birth or on follow-up MRI. This relationship was not seen in controls. Importantly, correlations were also found with real-world measures of academic achievement and behavioral difficulties.

INTERPRETATION

Preterm birth has a long-term effect on cognition, behavior, and future academic success primarily as a consequence of global brain WM reduction. This emphasizes the need for early therapeutic efforts to prevent WM injury and promote or optimize its development in preterm neonates.

Early cranial ultrasound lesions predict microcephaly at age 2 years in preterm infants

To assess how well early ultrasound lesions in preterm newborns predict reduced head circumference at 2 years, the investigators followed 923 children born before the 28th week of gestation who were not microcephalic at birth. Six percent of children who had a normal ultrasound scan were microcephalic compared with 15% to 20% who had intraventricular hemorrhage, an echolucent lesion, or ventriculomegaly. The odds ratios (95% confidence intervals) for microcephaly associated with different ultrasound images were intraventricular hemorrhage, 1.5 (0.8-3.0); ventriculomegaly, 3.3 (1.8-6.0); an echodense lesion, 1.6 (0.7-3.5); and an echolucent lesion, 3.1 (1.5-6.2). Ventriculomegaly and an echolucent lesion had very similar low positive predictive values (24% and 27%, respectively) and high negative predictive values (91% and 90%, respectively) for microcephaly. Ventriculomegaly had a higher sensitivity for microcephaly than did an echolucent lesion (24% vs 16%, respectively). Focal white-matter lesion (echolucent lesion) and diffuse white-matter damage (ventriculomegaly) predict an increased risk of microcephaly.

Ventricular dilatation in relation to outcome at 2 years of age in very preterm infants: a prospective Finnish cohort study

AIM

The aim of this study was to analyse the relation between ventricular dilatation at term and neurodevelopmental outcome at 2 years corrected age in infants of very low birthweight (VLBW) or very low gestational age (VLGA).

METHOD

A total of 225 VLBW or VLGA infants (121 males, 104 female; mean birthweight 1133 g, SD 333 g; mean gestational age 29 wks, SD 2 wks 5d) born in Turku University Hospital were included. Ventricular-brain ratio and the widths of each lateral ventricular horn were determined using ultrasonography, and the volume of the ventricles was measured by magnetic resonance imaging at term. The 2-year outcome measures included scores for the Hammersmith Infant Neurological Examination, the presence of cerebral palsy (CP), the Mental Developmental Index (MDI) of the Bayley Scales of Infant Development (2nd edition), and the presence of severe hearing or vision impairments or any neurodevelopmental impairment (NDI).

RESULTS

CP was diagnosed in 15 participants (6.7%) and severe hearing deficit in 12 participants (5.3%). No severe vision impairment was found. Mild and severe cognitive delay was found in 24 (10.7%) and 8 (3.6%) of the VLBW or VLGA infants respectively. Isolated ventricular dilatation did not increase the risk for developmental impairments. However, ventricular dilatation with additional brain pathology was significantly associated with CP, MDI score below 70, and NDI. A ventricular-brain ratio above 0.35 was a sensitive measure of developmental impairment.

INTERPRETATION

Ventricular dilatation at term increases the risk of poor developmental outcome only when associated with other brain pathology. The ventricular-brain ratio is a useful clinical tool for determining the prognosis in VLBW and VLGA infants.

Familial recurrence of cerebral palsy with multiple risk factors

The recurrence of cerebral palsy in the same family is uncommon. We, however, report on two families with two or more affected siblings. In both families, numerous potential risk factors were identified including environmental, obstetric, and possible maternal effects. We hypothesize that multiple risk factors may lead to the increased risk of recurrence of cerebral palsy in families. Intrinsic and maternal risk factors should be investigated in all cases of cerebral palsy to properly counsel families on the risk of recurrence. Recent studies of genetic polymorphisms associated with cerebral palsy are considered with reference to our observations in these two families.

Reader variability in the use of diagnostic terms to describe white matter lesions seen on cranial scans of severely premature infants: the ELGAN study

PURPOSE

To evaluate reader variability of white matter lesions seen on cranial sonographic scans of extreme low gestational age neonates (ELGANs).

METHODS

In 1,452 ELGANs, cranial sonographic scans were obtained in the first and second postnatal weeks, and between the third postnatal week and term. All sets of scans were read independently by two sonologists. We reviewed the use of four diagnostic labels: early periventricular leucomalacia, cystic periventricular leucomalacia, periventricular hemorrhagic infarction (PVHI), and other white matter diagnosis, by 16 sonologists at 14 institutions. We evaluated the association of these labels with location and laterality of hyperechoic and hypoechoic lesions, location of intraventricular hemorrhage, and characteristics of ventricular enlargement.

RESULTS

Experienced sonologists differed substantially in their application of the diagnostic labels. Three readers applied early periventricular leucomalacia to more than one fourth of all the scans they read, whereas eight applied this label to ≤5% of scans. Five applied PVHI to ≥10% of scans, while three applied this label to ≤5% of scans. More than one third of scans labeled cystic periventricular leucomalacia had unilateral hypoechoic lesions. White matter abnormalities in PVHI were more extensive than in periventricular leucomalacia and were more anteriorly located. Hypoechoic lesions on late scans tended to be in the same locations, regardless of the diagnostic label applied.

CONCLUSIONS

Experienced sonologists differ considerably in their tendency to apply diagnostic labels for white matter lesions. This is due to lack of universally agreed-upon definitions. We recommend reducing this variability to improve the validity of large multicenter studies.

Periventricular leucomalacia (PVL)-like lesions in two neonatal cynomolgus monkeys (Macaca fascicularis)

Periventricular leucomalacia (PVL) is a lesion of immature cerebral white matter that occurs in the perinatal period. In man, PVL is the predominant form of brain injury and a cause of cerebral palsy and cognitive deficits in premature infants. PVL affects fetuses and newborns, particularly those who have undergone oxygen deprivation as may occur in premature birth. Many clinical and pathological studies of PVL have been performed in man, but there is no clear definition of PVL in animals. A few spontaneous PVL-like cases in puppies or experimental cases in other animal species have been reported. The present study reports the histopathological and immunohistochemical features of PVL-like lesions in two neonatal cynomolgus monkeys. In both cases, there was cerebral white matter necrosis with marked infiltration of lipid-laden phagocytes and a reduction of neurons in the cerebral cortex. In case 1 there was extensive cavitation of the cerebral white matter. In case 2 there was reactive astrocytosis associated with a decrease in oligodendroglial cells and a decrease in cerebral white matter myelin. To our knowledge, this is the first report of PVL-like leucoencephalomalacia in non-human primates.

Lipopolysaccharide-activated microglia induce death of oligodendrocyte progenitor cells and impede their development

Damage to oligodendrocyte (OL) progenitor cells (OPCs) and hypomyelination are two hallmark features of periventricular leukomalacia (PVL), the most common form of brain damage in premature infants. Clinical and animal studies have linked the incidence of PVL to maternal infection/inflammation, and activated microglia have been proposed to play a central role. However, the precise mechanism of how activated microglia adversely affects the survival and development of OPCs is still not clear. Here we demonstrate that lipopolysaccharide (LPS)-activated microglia are deleterious to OPCs, that is, impeding OL lineage progression, reducing the production of myelin basic protein (MBP), and mediating OPC death. We further demonstrate that LPS-activated microglia mediate OPC death by two distinct mechanisms in a time-dependent manner. The early phase of cell damage occurs within 24 h after LPS treatment, which is mediated by nitric oxide (NO)-dependent oxidative damage and is prevented by N(G)-nitro-l-arginine methyl ester (l-NAME), a general inhibitor of nitric oxide synthase. The delayed cell death is evident at 48 h after LPS treatment, is mediated by cytokines, and is prevented by blocking the activity of tumor necrosis factor-alpha (TNF-alpha) and pro-nerve growth factor (proNGF), but not by l-NAME. Furthermore, microglia-derived insulin-like growth factor-1 (IGF-1) and ciliary neurotrophic factor (CNTF) were significantly suppressed by LPS, and exogenous IGF-1 and CNTF synergistically protected OLs from death induced by LPS-treated microglia conditioned medium, indicating that a deficiency in trophic support may also be involved in OL death. Our finding that LPS-activated microglia not only induce two waves of cell death but also greatly impair OL development may shed some light on the mechanisms underlying selective white matter damage and hypomyelination in PVL.

Heart rate characteristics and neurodevelopmental outcome in very low birth weight infants

BACKGROUND

Sepsis in very low birth weight (VLBW) infants has been associated with an increased risk of adverse developmental outcome. We have identified abnormal heart rate characteristics (HRCs) that are predictive of impending sepsis, and we have developed a summary measure of an infant's abnormal HRCs during the neonatal hospitalization that we refer to as the cumulative HRC score (cHRC).

OBJECTIVE

In this study, we tested the hypothesis that increasing cHRC is associated with an increasing risk of adverse neurodevelopmental outcome in VLBW infants.

METHOD

Data were collected on 65 VLBW infants whose HRCs were monitored while in the neonatal intensive care unit and who were examined at 12 to 18 months adjusted age. Using the Bayley Scale of Infant Development-II, we identified delays in early cognitive function (i.e., Mental Developmental Index <70) and psychomotor development (i.e., Psychomotor Developmental Index <70). Cerebral palsy (CP) was diagnosed using a standard neurological examination.

RESULT

Increasing cHRC score was associated with an increased risk of CP (odds ratio per 1 standard deviation increase in cHRC: 2.6, 95% confidence limits: 1.42, 5.1) and delayed early cognitive development [odds ratio: 2.3 (1.3; 4.3)]. These associations remain statistically significant when adjusted for major cranial ultrasound abnormality. There was an association of increasing cHRC and delayed psychomotor development, which did not reach statistical significance [odds ratio: 1.7 (1.0, 3.0)].

CONCLUSION

Among VLBW infants, the cumulative frequency of abnormal HRCs, which can be assessed non-invasively in the neonatal intensive care unit, is associated with an increased risk of adverse neurodevelopmental outcome.

Neuroprotective effect of oligodendrocyte precursor cell transplantation in a long-term model of periventricular leukomalacia

Perinatal white matter injury, or periventricular leukomalacia (PVL), is the most common cause of brain injury in premature infants and is the leading cause of cerebral palsy. Despite increasing numbers of surviving extreme premature infants and associated long-term neurological morbidity, our understanding and treatment of PVL remains incomplete. Inflammation- or ischemia/hypoxia-based rodent models, although immensely valuable, are largely restricted to reproducing short-term features of up to 3 weeks after injury. Given the long-term sequelae of PVL, there is a need for subchronic models that will enable testing of putative neuroprotective therapies. Here, we report long term characterization of a neonatal inflammation-induced rat model of PVL. We show bilateral ventriculomegaly, inflammation, reactive astrogliosis, injury to pre-oligodendrocytes, and neuronal loss 8 weeks after injury. We demonstrate neuroprotective effects of oligodendrocyte precursor cell transplantation. Our findings present a subchronic model of PVL and highlight the tissue protective effects of oligodendrocyte precursor cell transplants that demonstrate the potential of cell-based therapy for PVL.

Molecular mechanisms involved in injury to the preterm brain

Injury to the premature brain is a major contributor to infant mortality and morbidity, often leading to mental retardation and sensory-motor impairment. The disease process is believed to be caused, sustained, and aggravated by multiple perinatal factors that team up in a multi-hit fashion. Clinical, epidemiological, and experimental studies have revealed that key factors such as inflammation, excitotoxicity, and oxidative stress contribute considerably to white- and gray-matter injury in premature infants, whose brains are particularly susceptible to damage. Depending on the timing, lesions of the immature brain may influence developmental events in their natural sequence and redirect subsequent development. We review current concepts on molecular mechanisms underlying injury to the premature brain.

''Intraventricular'' hemorrhage and cystic periventricular leukomalacia in preterm infants: how are they related?

Intraventricular hemorrhage and cystic periventricular leukomalacia are often co-occurring characteristics of brain damage in preterm infants. Using data from 1016 infants born before 30 completed weeks' gestational age, we sought to clarify the relationship between severe intraventricular hemorrhage and cystic periventricular leukomalacia, with special emphasis on common antecedents and potential confounding. After comparing risk factors for intraventricular hemorrhage grades 1 through 4 and cystic periventricular leukomalacia, it appears the risk patterns for intraventricular hemorrhage grade 3, intraventricular hemorrhage grade 4, and cystic periventricular leukomalacia differ. The association between intraventricular hemorrhage grade 3 and cystic periventricular leukomalacia differs appreciably from the association between intraventricular hemorrhage grade 4 and cystic periventricular leukomalacia, supporting the notion that intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 are different entities. The presence of intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 increases the risk of cystic periventricular leukomalacia, even after adjusting for potential confounders. This raises the possibility that intraventricular hemorrhage grade 3 and intraventricular hemorrhage grade 4 cause cystic periventricular leukomalacia.

Brain and ventricles in very low birth weight infants at term: a comparison among head circumference, ultrasound, and magnetic resonance imaging

OBJECTIVES

The aim of this study was to assess the relationship among the size of the lateral ventricles, head-circumference measure, and brain volumes. In addition, the association between ventricular dilatation and various brain lesions was defined.

PATIENTS AND METHODS

A total of 257 preterm very low birth weight (< or =1500 g) infants who met the inclusion criteria were born in Turku University Central Hospital between 2001 and 2006. A total of 209 (84.8%) of 218 survivors participated in the study. The measurements at term included the ventricular brain ratio, the widths of the frontal and occipital horns of the lateral ventricles by ultrasound, total and regional brain volumes by MRI, and head circumference. Brain lesions were defined by ultrasound at 3 to 5, 7 to 10, and 30 days of age monthly until discharge and by MRI and ultrasound at term.

RESULTS

An abnormal ventricular brain ratio (>0.35), an increasing number of dilated ventricular horns, and smaller head circumference were significantly associated with smaller total brain tissue volume. The abnormal ventricular brain ratio and the increasing number of dilated ventricular horns in ultrasound associated with larger ventricular volumes in MRI, and a smaller head circumference was associated significantly with reduced regional brain tissue volumes. Brain lesions were more common in infants with ventriculomegaly.

CONCLUSIONS

The ventricular brain ratio, widths of the lateral ventricular horns, and head circumference are appropriate measures for the estimation of both total and regional brain tissue volumes. Ventriculomegaly is strongly associated with brain lesions.

Cranial ultrasound lesions in the NICU predict cerebral palsy at age 2 years in children born at extremely low gestational age

Our prospective cohort study of extremely low gestational age newborns evaluated the association of neonatal head ultrasound abnormalities with cerebral palsy at age 2 years. Cranial ultrasounds in 1053 infants were read with respect to intraventricular hemorrhage, ventriculomegaly, and echolucency, by multiple sonologists. Standardized neurological examinations classified cerebral palsy, and functional impairment was assessed. Forty-four percent with ventriculomegaly and 52% with echolucency developed cerebral palsy. Compared with no ultrasound abnormalities, children with echolucency were 24 times more likely to have quadriparesis and 29 times more likely to have hemiparesis. Children with ventriculomegaly were 17 times more likely to have quadriparesis or hemiparesis. Forty-three percent of children with cerebral palsy had normal head ultrasound. Focal white matter damage (echolucency) and diffuse damage (late ventriculomegaly) are associated with a high probability of cerebral palsy, especially quadriparesis. Nearly half the cerebral palsy identified at 2 years is not preceded by a neonatal brain ultrasound abnormality.

Antioxidant therapy and neuroprotection in the newborn

Injury to the perinatal brain is a leading cause of childhood mortality and lifelong disability. Despite recent improvements in neonatal care, no effective treatment for perinatal brain lesions is available. The newborn, especially if preterm, is highly prone to oxidative stress (OS) and to the toxic effect of free radicals (FRs). At birth, the newborn is exposed to a relatively hyperoxic environment caused by an increased oxygen bioavailability with greatly enhanced generation of FRs. Additional sources (e.g., inflammation, hypoxia, ischemia, glutamate and free iron release) occur, magnifying OS. In the preterm baby, the perinatal transition is accompanied by the immaturity of the antioxidant systems and the reduced ability to induce efficient homeostatic mechanisms designed to control overproduction of cell-damaging FRs. Improved understanding of the pathophysiological mechanism involved in perinatal brain lesions helps to identify potential targets for neuroprotective interventions, and the knowledge of these mechanisms has enabled scientists to develop new therapeutic strategies that have confirmed their neuroprotective effects in animal studies. Considering the growing role of OS in preterm newborn morbidity in respect to the higher risk of FR damage in these babies, erythropoietin, allopurinol, melatonin and hypothermia demonstrate great promise as potential neuroprotectans. This article provides an overview of the pathogenesis of FR-mediated diseases of the newborn and the antioxidant strategies now tested in order to reduce OS and its damaging effects.

Neonatal cranial ultrasound lesions and developmental delays at 2 years of age among extremely low gestational age children

BACKGROUND

Studies of the relationship between ultrasound images from preterm newborns and developmental delay most often are based on small samples defined by birth weight and exclude infants not testable with standardized assessments.

METHODS

We evaluated associations between ultrasound-defined lesions of the brain and developmental delays at 24 months' corrected age in 1017 children born before the 28th postmenstrual week. Brain ultrasound scans were read for concordance on 4 lesions: intraventricular hemorrhage, moderate/severe ventriculomegaly, white matter echodense/hyperechoic lesions, and white matter echodense/hypoechoic lesions and 2 diagnoses-periventricular leukomalacia and periventricular hemorrhagic infarction. Certified examiners, who were not aware of the infants' ultrasound findings, administered the Bayley Scales of Infant Development-Second Edition. Children with an impairment (eg., blindness) that precluded testing with the Bayley Scales and those for whom >2 test items were omitted were classified using the Vineland Adaptive Behavior Scales Motor Skills Domain instead of the Psychomotor Development Index and the Adaptive Behavior Composite instead of the Mental Development Index.

RESULTS

Fully 26% of all of the children had delayed mental development (ie, Mental Development Index < 70), and 31% had delayed psychomotor development (ie, Psychomotor Development Index < 70). Ultrasound abnormalities were more strongly associated with low Psychomotor Development Index than with low Mental Development Index. Children without cranial ultrasound abnormality had the lowest probability (23% and 26%) of delayed mental or psychomotor development. Moderate/severe ventriculomegaly was associated with a more than fourfold increase in the risk of psychomotor delay and an almost threefold increase in the risk of mental delay. Echolucency was the next best predictor of delayed mental and psychomotor development. The probability of low scores varied with the number of zones involved and with the location of echolucency. At particularly high risk were infants with bilateral cerebellar hemorrhage, co-occurring ventriculomegaly and echolucency bilateral echolucency, or echolucency located posteriorly.

CONCLUSIONS

Focal white matter damage, as characterized by echolucent/hypoechoic lesion, and diffuse damage, as suggested by late ventriculomegaly, are associated with delayed mental and psychomotor development.

Studies on the value of diffusion-weighted MR imaging in the early prediction of periventricular leukomalacia

OBJECTIVE

Periventricular leukomalacia (PVL) is the most common cerebral injury in premature infants. While cranial ultrasonography and conventional magnetic resonance imaging (MRI) offer little for its early diagnosis, still they are much favored at present. Based on the pathologic mechanism of ischemic cerebral injury in PVL, we attempt to elucidate the effects of diffusion-weighted MR imaging (DWI) for the early diagnosis of PVL.

METHODS

Twelve cases of PVL in premature infants confirmed by MRI examinations were included in the current study. All cases underwent DWI in addition to conventional MR imaging (T1-weighted [T1W] and T2-weighted [T2W]) 7 days, 2 weeks, and 4 approximately 8 weeks after birth, respectively.

RESULTS

Initial DWI examination (carried out at an average of 4.5 days after birth) revealed symmetrical and diffuse high signal in bilateral periventricular areas in all cases, while conventional MRI demonstrated normal signal. DWI examination of 2 weeks later showed irregular inhomogeneous signals in cerebral white matter, while conventional MRI revealed hyperintensity on T1WI and slight hypointensity on T2WI in corresponding areas. Four weeks later, DWI revealed various intensities of cystic low signals beside lateral ventricles, while conventional MRI showed hypointensity on T1WI and hyperintensity on T2WI in corresponding lesion, ie, change in cystic PVL. Four months later, conventional MRI evidenced gradual shrink and disappearance of cystic cavity, reduction in cerebral white matter, and ventricle enlargement.

CONCLUSIONS

Symmetrical, diffuse hyperintensity in both lateral periventricular white matter on DWI was the earliest sign of PVL in premature infants. Imaging abnormalities provided by DWI had a close correlation with the results obtained by conventional MRI performed at the advanced stage of PVL, which suggests that DWI may be an important sequence for the early evaluation of cerebral white matter injury as well as for the prediction of PVL occurrence in premature infants.

Pathogenesis of cerebral white matter injury of prematurity

Cerebral white matter injury, characterised by loss of premyelinating oligodendrocytes (pre-OLs), is the most common form of injury to the preterm brain and is associated with a high risk of neurodevelopmental impairment. The unique cerebrovascular anatomy and physiology of the premature baby underlies the exquisite sensitivity of white matter to the abnormal milieu of preterm extrauterine life, in particular ischaemia and inflammation. These two upstream mechanisms can coexist and amplify their effects, leading to activation of two principal downstream mechanisms: excitotoxicity and free radical attack. Upstream mechanisms trigger generation of reactive oxygen and nitrogen species. The pre-OL is intrinsically vulnerable to free radical attack due to immaturity of antioxidant enzyme systems and iron accumulation. Ischaemia and inflammation trigger glutamate receptor-mediated injury leading to maturation-dependent cell death and loss of cellular processes. This review looks at recent evidence for pathogenetic mechanisms in white matter injury with emphasis on targets for prevention and treatment of injury.