Antenatal brain injury: aetiology and possibilities of prevention

Early changes in S100B maternal blood levels can predict fetal intrauterine growth restriction

OBJECTIVES

Intrauterine growth restriction (IUGR) represents one of the main causes of perinatal mortality and morbidity. Nowadays, IUGR early diagnosis is mandatory in order to limit the occurrence of multiorgan failure, especially the brain. Therefore, we investigated whether longitudinal S100B assessment in maternal blood could be a trustable predictor of IUGR.

METHODS

We conducted a prospective study in 480 pregnancies (IUGR: n=40; small for gestational age, SGA: n=40; controls: n=400) in whom S100B was measured at three predetermined monitoring time-points (T1: 8-18 GA; T2: 19-23 GA; T3: 24-28 GA).

RESULTS

Lower S100B in IUGR fetuses than SGA and controls (p<0.05, for all) at T1-T3. Receiver operating characteristic curve showed that S100B at T1 was the best predictor of IUGR (sensitivity: 100 %; specificity: 81.4 %) than T2, T3.

CONCLUSIONS

The early lower S100B concentration in pregnant women lately complicated by IUGR support the notion that non-invasive early IUGR diagnosis and monitoring is becoming feasible. Results open the way to further studies aimed at diagnosing and monitoring fetal/maternal diseases at earliest time.

The Ca2+-Binding S100B Protein: An Important Diagnostic and Prognostic Neurobiomarker in Pediatric Laboratory Medicine

In recent decades a significant scientific effort has focused on projects regarding the use of neurobiomarkers in perinatal medicine with a view to understanding the mechanisms that interfere with physiological patterns of brain development and lead to ominous effects in several human diseases. Numerous potential neurobiomarkers have been proposed for use in monitoring high-risk fetuses and newborns, including markers of oxidative stress, neuroproteins, and vasoactive agents. Nonetheless, the use of these markers in clinical practice remains a matter of debate. Recently, the calcium-binding S100B protein has been proposed as being an ideal neurobiomarker, thanks to its simple availability and easy reproducibility, to the possibility of detecting it noninvasively in biological fluids with good reproducibility, and to the possibility of a longitudinal evaluation in relation to reference curves. The present chapter contains an overview of the most significant studies on the assessment of S100B in different biological fluids as a trophic factor and/or marker of brain damage in high-risk fetuses and newborns.

Associations between neural injury markers of intrauterine growth-restricted infants and neurodevelopment at 2 years of age

Objectives: The aim of this study was to evaluate the relationships between brain injury biomarkers in intrauterine growth-restricted (IUGR) infants (S100B and neuron-specific enolase (NSE)) and neurodevelopment at 2 years of age. Methods: This prospective case-control study was a cooperative effort among Spanish Maternal and Child Health Network (Retic SAMID) hospitals. At inclusion, biometry for estimated fetal weight and feto-placental Doppler variables were measured for each infant. Maternal venous blood and fetal umbilical arterial blood samples were collected at the time of delivery and neural injury markers S100B and NSE concentrations were measured. Neurodevelopment was evaluated at 2 years of age using the Bayley Scales of Infant and Toddler Development, third edition (Bayley-III). Results: Fifty six pregnancies were included. Thirty-one infants were classified as IUGR and 25 as non-IUGR. Neurodevelopmental evaluation at 2 years of age indicated that there were no between-group differences for any of the tests. For all patients in both groups, we found statistically significant inverse relationships between the concentrations of NSE in the cord blood and the results of the cognitive test (r = -271, p = .042), fine motor subtest (r = -280, p = .036), and social-emotional test (r = -349, p = .015). We also found statistically significant differences between the concentrations of S100B in the cord blood and the results of the cognitive test (r = -306, p = .022) and expressive communication subtest (r = -304, p = .023). For the IUGR group, we found a significant inverse relationship between the concentrations of S100B in the maternal serum and the results of adaptive behavior test (p < .05). In the non-IUGR group, we found statistically significant inverse relationships between the concentration of NSE in the cord blood and the results of the fine motor subtest (r = -446, p = .025) and social-emotional test (r = -489, p = .021). The difference between the concentration of S100B in the cord blood and the language composite score was also statistically significant (p = .038). Conclusions: At 2 years of age, the concentrations of NSE and S100B were higher in the non-IUGR and IUGR groups with the worst scores for some areas of neurodevelopmental evaluation. The value of these biomarkers for prognostic neurodevelopmental use requires further investigation for both non-IUGR and IUGR infants.

S100B maternal blood levels are gestational age- and gender-dependent in healthy pregnancies

BACKGROUND

S100B is a well-established biomarker of central nervous system (CNS) development and damage in the perinatal period. Because the fetal CNS induces an overproduction of S100B measurable in the maternal bloodstream we evaluated S100B protein in healthy pregnancies in order to provide a reference curve of the protein in the second and third trimesters and to provide information on CNS development when standard monitoring procedures could be silent or unavailable.

METHODS

Between July 2012 and December 2014 we conducted a prospective study in 1213 healthy pregnancies delivering healthy newborns. Maternal blood samples were collected for standard monitoring procedures and S100B assessment. S100B correlations with selected outcomes (gestational age at sampling, gender of fetus, gestational age and weight at birth, delivery mode) were calculated using multiple forward stepwise regression analysis.

RESULTS

S100B concentrations in the second and third trimesters of pregnancy were found to be gestational age-, gender- and delivery mode-dependent (p<0.05, for all). Multiple forward stepwise regression analysis with S100B as the dependent variable and gestational age at sampling, gender, delivery mode, gestational age and weight at birth as independent variables, showed a significant correlation between S100B and gestational age at sampling (R=0.13; p<0.001).

CONCLUSIONS

The present findings offering a S100B protein reference curve in maternal blood suggest that non-invasive fetal CNS monitoring is becoming feasible and open the way to further research in neuro-biomarker assessment in the maternal bloodstream.

Neural injury markers in intrauterine growth restriction and their relation to perinatal outcomes

BACKGROUNDThe aims of this study were to (i) compare the concentrations of two neural injury markers, S100B protein and neuron-specific enolase (NSE), in intrauterine growth-restricted (IUGR) fetuses and in fetuses with appropriate growth-for-gestational-age (AGA), and (ii) investigate potential relationships between concentrations of these markers, Doppler abnormalities, and adverse perinatal or neonatal outcomes.METHODSThis was a case-controlled, cooperative, prospective study among Spanish Maternal and Child Health Network (Retic SAMID) hospitals. At inclusion, biometry for estimated fetal weight and feto-placental Doppler were measured. At the time of delivery, maternal venous blood and fetal umbilical arterial blood samples were collected. S100B and NSE concentrations were determined from these samples.RESULTSIn total, 254 pregnancies were included. Among these, 147 were classified as IUGR and 107 as AGA. There were no differences between the groups in S100B concentrations. However, levels of NSE in maternal and umbilical cord serum differed significantly between these groups (2.31 in AGA vs. 2.51 in IUGR in (P<0.05); and 2.89 in AGA vs. 3.25 in IUGR (P<0.05), respectively). No differences were observed in these neurological markers when stratified by perinatal or neonatal complications.CONCLUSIONAlthough some variations exist in these neurological markers, they did not correlate with perinatal or neonatal complications.

GSK3β inhibition protects the immature brain from hypoxic-ischaemic insult via reduced STAT3 signalling

Hypoxic-ischaemic (HI) injury is an important cause of neurological morbidity in neonates. HI leads to pathophysiological responses, including inflammation and oxidative stress that culminate in cell death. Activation of glycogen synthase kinase 3β (GSK3β) and the signal transducer and activator of transcription (STAT3) promotes brain inflammation. The purpose of this study was to test whether inhibition of GSK3β signalling protects against neonatal HI brain injury. Mice were subjected to HI at postnatal day (PND) 9 and treated with a selective GSK3β inhibitor, SB216763. Brain injury and caspase-3 activation, anti-oxidant and inflammatory mRNA responses and activation of STAT3 were analysed. Our results show that HI reduced phosphorylation of GSK3β, thus promoting its kinase activity. The GSK3β inhibitor reduced caspase-3 activation and neuronal cell death elicited by HI and reverted the effects of HI on gene expression of the anti-oxidant enzyme sod2 and mitochondrial factor pgc1α. The HI insult activated STAT3 in glial cells and GSK3β inhibition attenuated STAT3 phosphorylation and its nuclear translocation following HI. Further, GSK3β inhibition reduced HI-induced gene expression of pro-inflammatory cytokines tnfα and Il-6, while promoted the anti-inflammatory factor Il-10. In summary, data show that GSK3β inhibition is neuroprotective in neonatal HI brain injury likely via reduced pro-inflammatory responses by blocking STAT3 signalling. Our study suggests that pharmacological interventions built upon GSK3β silencing strategies could represent a novel therapy in neonatal brain injury.

Umbilical cord blood cell transplantation after brain ischemia--from recovery of function to cellular mechanisms

Cell transplantation has been proposed as a potential approach to the treatment of neurological disorders. One cell population of interest consists of human umbilical cord blood (hUCB) cells, which have previously been shown to be useful for reparative medicine in haematological diseases. However, hUCB cells are also capable of differentiating into various non-haematopoietic cells, including those of the neural lineage. Moreover, hUCB cells can secrete numerous neurotrophic factors and modulate immune function and inflammatory reaction. Several studies on animal models of ischemic brain injury have demonstrated the potential of hUCB cells to minimize damage and promote recovery after ischemic brain injury.This review focuses on the treatment of both stroke and perinatal hypoxic-ischemic brain injury using hUCB cells. We discuss the therapeutic effects demonstrated after hUCB cell transplantation and emphasize possible mechanisms counteracting pathophysiological events of ischemia, thus leading to the generation of a regenerative environment that allows neural plasticity and functional recovery. The therapeutic functional effects of hUCB cells observed in animal models make the transplantation of hUCB cells a promising experimental approach in the treatment of ischemic brain injury. Together with its availability, low risk of transplantation, immaturity of cells, and simple route of application, hUCB transplantation may stand a good chance of being translated into a clinical setting for the therapy of ischemic brain injury.

Fetal magnetic resonance imaging of acquired and developmental brain anomalies

During the last decade, increasing interest in magnetic resonance imaging has emerged for the evaluation of fetal abnormalities detected on ultrasound. The advent of single-shot rapid acquisition sequences has greatly facilitated our ability to obtain detailed imaging information of the fetal brain. To date, fetal magnetic resonance imaging has shown to have an important role in the investigation of cerebral abnormalities suspected by sonography, and in the detection of subtle brain anomalies associated with high-risk pregnancies. Magnetic resonance imaging has proved to be a useful adjunct to sonography during the prenatal period of development, especially for the detection of acquired disorders.

Timing of neonatal seizures and intrapartum obstetrical factors

One hundred ninety-three neonates with seizures were available on a neonatal seizure database, which included intrapartum and neonatal factors such as labor duration, fetal heart rate abnormalities, cord blood gas values, Apgar scores and clinical signs of encephalopathy. Regression analyses (analysis of variance) were performed on the entire cohort as well as specific subsets of neonates (eg, neonatal encephalopathy vs no encephalopathy) to assess the relationship between seizure timing and intrapartum/neonatal factors. Seizures were noted earlier for the encephalopathic group than for the nonencephalopathic group. No significant differences were noted for any intrapartum or neonatal factors. Timing of neonatal seizures, with or without an encephalopathy occurs within the first 2 days after birth and is independent of selected intrapartum and neonatal factors, underscoring recent task force recommendations concerning neonatal encephalopathy. Factors other than intrapartum events more likely contribute to the encephalopathic repertoire of the newborn, including seizures.

Genetic program of neuronal differentiation and growth induced by specific activation of NMDA receptors

Glutamate and its receptors are expressed very early during development and may play important roles in neurogenesis, synapse formation and brain wiring. The levels of glutamate and activity of its receptors can be influenced by exogenous factors, leading to neurodevelopmental disorders. To investigate the role of NMDA receptors on gene regulation in a neuronal model, we used primary neuronal cultures developed from embryonic rat cerebri in serum-free medium. Using Affymetrix Gene Arrays, we found that genes known to be involved in neuronal plasticity were differentially expressed 24 h after a brief activation of NMDA receptors. The upregulation of these genes was accompanied by a sustained induction of CREB phosphorylation, and an increase in synaptophysin immunoreactivity. We conclude that NMDA receptor activation elicits expression of genes whose downstream products are involved in the regulation of early phases of the process leading to synaptogenesis and its consolidation, at least in part through sustained CREB phosphorylation.

The Timing of Neonatal Brain Damage

Although neonatal morbidity and mortality are less than in the past, the risk of pre-natal and neonatal brain damage has not been eliminated. In order to optimize pre-natal, perinatal and neonatal care, it is necessary to detect factors responsible for brain damage and obtain information about their timing. Knowledge of the timing of asphyxia, infections and circulatory abnormalities would enable obstetricians and neonatologists to improve prevention in pre-term and full-term neonates. Cardiotocography has been criticized as being too indirect a sign of fetal condition and as having various technical pitfalls, though its reliability seems to be improved by association with pulse oximetry, fetal blood pH and electrocardiography. Neuroimaging is particularly useful to determine the timing of hypoxic-ischemic brain damage. Cranial ultrasound has been used to determine the type and evolution of brain damage. Magnetic resonance has also been used to detect antenatal, perinatal and neonatal abnormalities and timing on the basis of standardized assessment of brain maturation. Advances in the interpretation of neonatal electroencephalograms have also made this technique useful for determining the timing of brain lesions. Nucleated red blood cell count in cord blood has been recognized as an important indication of the timing of pre-natal hypoxia, and even abnormal lymphocyte and thrombocyte counts may be used to establish pre-natal asphyxia. Cord blood pH and base excess are well-known markers of fetal hypoxia, but are best combined with heart rate and blood pressure. Other markers of fetal and neonatal hypoxia useful for determining the timing of brain damage are assays of lactate and markers of oxidative stress in cord blood and neonatal blood. Cytokines in blood and amniotic fluid may indicate chorioamnionitis or post-natal infections. The determination of activin and protein S100 has also been proposed. Obstetricians and neonatologists can therefore now rely on various methods for monitoring the risk of brain damage in the antenatal and post-natal periods.

High Maternal Blood S100B Concentrations in Pregnancies Complicated by Intrauterine Growth Restriction and Intraventricular Hemorrhage

Background: Intrauterine growth restriction (IUGR) is associated with perinatal mortality and with neurologic damage from intraventricular hemorrhage (IVH). We investigated whether S100B, a neural protein found in high concentrations after cell injury in the nervous system, is increased in serum of women whose pregnancies are complicated by IUGR and whose newborns develop IVH. We also explored the prognostic accuracy of maternal serum S100B for IVH in the newborn.

Methods: We conducted a case–control study of 106 pregnancies complicated by IUGR, including a subgroup (n = 26) who developed IVH after birth, and 212 unaffected pregnancies matched for gestational age. Ultrasound examination, Doppler velocimetry patterns (in the utero-placental vessels and middle cerebral artery), and maternal blood collection were performed before birth; cerebral ultrasound and neurologic examinations were performed after birth.

Results: S100B was higher (P &lt;0.001) in IUGR pregnancies complicated by IVH than in those that were not and in controls. At a cutoff of 0.72 μg/L, sensitivity was 100% [95% confidence interval (95% CI), 87%–100%] and specificity was 99.3% (97.5%–99.9%) for prediction of IVH (area under the ROC curve, 0.999). The prevalence of IVH was 8.2% in the whole study population, 93% (95% CI, 83.6%–100%) in those with maternal S100B &gt;0.72 μg/L, and 0% (0%–2.5%) in those with maternal S100B &lt;0.72 μg/L.

Conclusion: For prediction of IVH, measurements of maternal S100B may be useful at times before clinical, laboratory, and ultrasound patterns can identify risk of IVH.

Electrocardiographic changes following umbilical cord occlusion in the midgestation fetal sheep

BACKGROUND

Clinical studies show that analysis of the fetal electrocardiographic (FECG) ST waveform at term gives important information on the myocardial response to intrapartum asphyxia. However, it is not known whether the preterm fetus responds in a similar fashion. The objective of the present study was to evaluate the FECGST response to umbilical cord occlusion in the preterm fetal sheep.

METHODS

Fetal sheep at midgestation were subjected to 25 min umbilical cord occlusion (n = 7) and compared to controls (n = 5). Changes in the FECGST waveform were recorded together with arterial blood pressure, heart rate, and acid base status during the occlusion and for 3 days afterward.

RESULTS

Umbilical cord occlusion resulted in immediate bradycardia (control: 187 +/- 7 bpm versus occlusion: 102 +/- 7 bpm), hypertension (control: 43.2 +/- 1.1 mmHg versus occlusion: 59.8 +/- 2.2 mmHg), and an initial increase in the T/QRS ratio (control: 0.10 +/- 0.02 versus occlusion: 0.60 +/- 0.10, P < 0.001), followed by hypotension (21.7 +/- 1.2 mmHg), normalization of the T/QRS ratio, and in some cases the development of negative T waves toward the end of the occlusion.

CONCLUSIONS

These studies show that the midgestation fetal sheep has the capacity to react to umbilical cord occlusion with a significant increase in the amplitude of the ST waveform together with an augmentation of blood pressure, which then subsides as the occlusion continues. The appearance of negative ST segment appears to signify significant cardiac dysfunction. The characteristic progression of ST-waveform changes in response to umbilical cord occlusion in midgestation fetal sheep, suggests that monitoring the ST waveform may contribute clinically important information also in the preterm individual.

Antenatal risk factors for cerebral palsy

Two of every 1000 live-born children develop cerebral palsy (CP). The aetiology of CP is often unclear and because CP is a symptom complex rather than a disease, clinically defined at 4-5 years of age, it is not surprising that there are considerable problems associated with epidemiological studies of its aetiology. The only reason for the CP concept is that it emanates from an insult to a growing, developing brain and a dynamic clinical picture from static pathology. Evidence suggests that 70-80% of CP cases are due to prenatal factors and that birth asphyxia plays a relatively minor role (<10%). Some antenatal risk factors are repeatedly observed to be related to CP: low gestational age, male gender, multiple gestation, intrauterine viral infections and maternal thyroid abnormalities. Recently, intrauterine infection/inflammation with a maternal response (consisting of chorioamnionitis) and a fetal inflammatory response (consisting of funicitis or elevated interleukin-6 in fetal plasma) has been found to be related to white matter injury and CP. Some risk factors are associated with CP at all gestational ages whereas others mostly affect term or preterm infants, e.g. intrauterine growth restriction seems to be a risk factor in term infants. There also seems to be an association between autoimmune and coagulation disorders and CP.

Screening for infectious diseases

INTRODUCTION

Fetal brain injury is an essential cause of lifelong morbidity. Infection appears as a cause of brain damage. Apart from chorioamnionitis, screening for infectious diseases must be considered in pregnancies with a risk of congenital infection or cases with abnormal cerebral ultrasound findings.

DISCUSSION

Congenital infections include most of the major components of the TORCH complex: toxoplasmosis, rubella, cytomegalovirus, herpes, and varicella. Seronegative mothers can develop primary infection, which carries a risk of vertical transmission. The timing of the infection is a critical point, because fetal damage often depends on the gestational age at which acute maternal infection took place and occurs more likely in the first half of pregnancy. Antenatal ultrasound can detect brain abnormalities, like hydrocephalus, periventricular leukomalacia, calcifications or hemorrhage. Maternal serologic tests must be performed to look for an infectious etiology; the most frequent agents are the components of the TORCH complex. But additional serology must include parvovirus B19, HIV, and coxsackieviruses.

Fetal and neonatal neurologic case histories: assessment of brain disorders in the context of fetal-maternal-placental disease. Part 2: Neonatal neurologic consultations in the context of adverse antepartum and intrapartum events

The more conventional role of the pediatric neurologist involves the evaluation of the child after birth. Although the pediatric neurologist rarely attends the delivery of the neonate, consultation by the neurologist should begin immediately following stabilization by the neonatal resuscitation team. Four interrelated aspects of the neurologist's clinical assessment will be discussed in the context of reaching a consultative opinion, which must incorporate knowledge of chronologic events before as well as during labor and delivery. This evaluation encompasses an assessment of levels of arousal, increased or decreased muscle tone, presence of seizures, and effects of systemic diseases on the central nervous system, which are the essential elements of a complete neurologic examination. Documentation of the neonate's neurologic condition, together with knowledge of maternal, fetal, and placental diseases, will help anticipate neuroresuscitative decisions, as well as subsequent neurologic deficits.

Environmental factors and disturbances of brain development

Foetal and neonatal brain is under the influence of environmental factors from maternal and extra-maternal origin. Based on the available data, these environmental factors can be classified into three arbitrary groups: (i) factors and maternal status with a demonstrated deleterious effect on the foetal brain (i.e. ethanol, cocaine, some drugs including anticonvulsants, some viral infections, maternal diabetes, untreated maternal phenylketonuria); (ii) factors highly suspected to interfere with foetal brain development (i.e. lead and other heavy metals, some drugs like benzodiazepines, nicotine); (iii) factors which have been shown to be safe for the developing brain in the available studies (i.e. low to moderate doses of caffeine, methadone). However, most of these studies do not address the potential risk of environmental factors on minimal to moderate cognitive and behavioural disturbances. Finally, the impact of the neonatal environment on brain development in very pre-term infants is probably underestimated.

Perinatal asphyxia: timing and mechanisms of injury in neonatal encephalopathy

This article summarizes the recent medical literature regarding perinatal asphyxia with respect to timing and mechanisms of injury for neonates who were clinically diagnosed with an encephalopathy in the newborn period. Multiple mechanisms of injury are reviewed, including genetic vulnerability, acquired inflammatory responses, and clotting defects that can lead to ischemic-induced brain damage. Before effective treatments for fetal and neonatal brain disorders can be developed, accurate and timely diagnoses of fetal or neonatal brain injury must be achieved. Specific subsets of children can then benefit from neuroprotective strategies that can target the specific developmental aspects of brain adaptation or plasticity relative to the specific etiology and timing of injury after asphyxia.