Long-term cognitive and behavioral consequences of neonatal encephalopathy following perinatal asphyxia: a review

Pathophysiology of perinatal asphyxia: can we predict and improve individual outcomes?

Perinatal asphyxia occurs still with great incidence whenever delivery is prolonged, despite improvements in perinatal care. After asphyxia, infants can suffer from short- to long-term neurological sequelae, their severity depend upon the extent of the insult, the metabolic imbalance during the re-oxygenation period and the developmental state of the affected regions. Significant progresses in understanding of perinatal asphyxia pathophysiology have achieved. However, predictive diagnostics and personalised therapeutic interventions are still under initial development. Now the emphasis is on early non-invasive diagnosis approach, as well as, in identifying new therapeutic targets to improve individual outcomes. In this review we discuss (i) specific biomarkers for early prediction of perinatal asphyxia outcome; (ii) short and long term sequelae; (iii) neurocircuitries involved; (iv) molecular pathways; (v) neuroinflammation systems; (vi) endogenous brain rescue systems, including activation of sentinel proteins and neurogenesis; and (vii) therapeutic targets for preventing or mitigating the effects produced by asphyxia.

Early testosterone modulated sex differences in behavioral outcome following neonatal hypoxia ischemia in rats

Hypoxia ischemia (HI; reduced blood oxygenation and/or flow to the brain) represents one of the most common injuries for both term and preterm/very low birth weight (VLBW) infants. These children experience elevated incidence of cognitive and/or sensory processing disabilities, including language based learning disabilities. Clinical data also indicate more substantial long-term deficits for HI injured male babies as compared to HI injured females. Previously, we reported significant deficits in rapid auditory processing and spatial learning in male rats with postnatal day 1 (P1), P7, or P10 HI injury. We also showed sex differences in HI injured animals, with more severe deficits in males as compared to females. Given these findings, combined with extant clinical data, the current study sought to assess a putative role for perinatal testosterone in modulating behavioral outcome following early hypoxic-ischemic injury in rats. Male, female, and testosterone-propionate (TP) treated females were subjected to P7 HI or sham surgery, and subsequently (P30+) underwent a battery of auditory testing and water maze assessment. Results confirm previous reports of sex differences following HI, and add new findings of significantly worse performance in TP-treated HI females compared to vehicle treated HI females. Post mortem anatomic analyses showed consistent effects, with significant brain weight decreases seen in HI male and TP-treated HI females but not female HI or sham groups. Further neuromorphometric analysis of brain structures showed that HI male animals exhibited increased pathology relative to HI females as reflected in ventricular enlargement. Findings suggest that neonatal testosterone may act to enhance the deleterious consequences of early HI brain injury, as measured by both neuropathology and behavior.

Preterm birth and attention-deficit/hyperactivity disorder in schoolchildren

OBJECTIVE

Previous studies have demonstrated an increased risk for attention-deficit/hyperactivity disorder (ADHD) in follow-up studies of preterm survivors from NICUs. In this study we analyzed the effect of moderate as well as extreme preterm birth on the risk for ADHD in school age, taking into account genetic, perinatal, and socioeconomic confounders.

METHODS

Register study in a Swedish national cohort of 1 180 616 children born between 1987 and 2000, followed up for ADHD medication in 2006 at the age of 6 to 19 years. Logistic regression was used to test hypotheses. A within-mother-between-pregnancy design was used to estimate the importance of genetic confounding in a subpopulation of offspring (N = 34 334) of mothers who had given birth to preterm (≤34 weeks) as well as term infants.

RESULTS

There was a stepwise increase in odds ratios for ADHD medication with increasing degree of immaturity at birth; from 2.1 (1.4-2.7) for 23 to 28 weeks' gestation, to 1.6 (1.4-1.7) for 29 to 32 weeks', 1.4 (1.2-1.7) for 33 to 34 weeks', 1.3 (1.1-1.4) for 35 to 36 weeks', and 1.1 (1.1-1.2) for 37 to 38 weeks' gestation compared with infants born at 39 to 41 weeks' gestation in the fully adjusted model. The odds ratios for the within-mother-between-pregnancy analysis were very similar. Low maternal education increased the effect of moderate, but not extreme, preterm birth on the risk for ADHD.

CONCLUSION

Preterm and early term birth increases the risk of ADHD by degree of immaturity. This main effect is not explained by genetic, perinatal, or socioeconomic confounding, but socioeconomic context modifies the risk of ADHD in moderately preterm births.

Hypothermia after perinatal asphyxia: selection for treatment and cooling protocol

Three large randomized controlled trials have demonstrated benefits from 3 days of cooling to 33-34°C after perinatal asphyxia. No serious adverse effects were documented. The trials excluded many infants for hypothermia (HT) therapy, including those of age >6 hours and those with prematurity of <36 weeks gestation, abnormal coagulation, persistent pulmonary hypertension, and congenital abnormalities. This article considers whether the foregoing trial exclusion criteria are feasible given current knowledge and evidence. HT affects the validity of some outcome predictors (eg, clinical examination, amplitude-integrated electroencephalography), but not of magnetic resonance imaging. HT is a time-critical emergency treatment after perinatal asphyxia that requires optimal collaboration among local hospitals, transport teams, and cooling centers.

Autism spectrum disorders and fetal hypoxia in a population-based cohort: accounting for missing exposures via Estimation-Maximization algorithm

BACKGROUND

Autism spectrum disorders (ASD) are associated with complications of pregnancy that implicate fetal hypoxia (FH); the excess of ASD in male gender is poorly understood. We tested the hypothesis that risk of ASD is related to fetal hypoxia and investigated whether this effect is greater among males.

METHODS

Provincial delivery records (PDR) identified the cohort of all 218,890 singleton live births in the province of Alberta, Canada, between 01-01-98 and 12-31-04. These were followed-up for ASD via ICD-9 diagnostic codes assigned by physician billing until 03-31-08. Maternal and obstetric risk factors, including FH determined from blood tests of acidity (pH), were extracted from PDR. The binary FH status was missing in approximately half of subjects. Assuming that characteristics of mothers and pregnancies would be correlated with FH, we used an Estimation-Maximization algorithm to estimate HF-ASD association, allowing for both missing-at-random (MAR) and specific not-missing-at-random (NMAR) mechanisms.

RESULTS

Data indicated that there was excess risk of ASD among males who were hypoxic at birth, not materially affected by adjustment for potential confounding due to birth year and socio-economic status: OR 1.13, 95%CI: 0.96, 1.33 (MAR assumption). Limiting analysis to full-term males, the adjusted OR under specific NMAR assumptions spanned 95%CI of 1.0 to 1.6.

CONCLUSION

Our results are consistent with a weak effect of fetal hypoxia on risk of ASD among males. E-M algorithm is an efficient and flexible tool for modeling missing data in the studied setting.

Perinatal asphyxia affects rat auditory processing: implications for auditory perceptual impairments in neurodevelopmental disorders

Perinatal asphyxia, a naturally and commonly occurring risk factor in birthing, represents one of the major causes of neonatal encephalopathy with long term consequences for infants. Here, degraded spectral and temporal responses to sounds were recorded from neurons in the primary auditory cortex (A1) of adult rats exposed to asphyxia at birth. Response onset latencies and durations were increased. Response amplitudes were reduced. Tuning curves were broader. Degraded successive-stimulus masking inhibitory mechanisms were associated with a reduced capability of neurons to follow higher-rate repetitive stimuli. The architecture of peripheral inner ear sensory epithelium was preserved, suggesting that recorded abnormalities can be of central origin. Some implications of these findings for the genesis of language perception deficits or for impaired language expression recorded in developmental disorders, such as autism spectrum disorders, contributed to by perinatal asphyxia, are discussed.

The autism risk genes MET and PLAUR differentially impact cortical development

Candidate risk genes for autism spectrum disorder (ASD) have been identified, but the challenge of determining their contribution to pathogenesis remains. We previously identified two ASD risk genes encoding the receptor tyrosine kinase MET and the urokinase plasminogen activator receptor (PLAUR), which is thought to modulate availability of the MET ligand. We also reported a role for Met signaling in cortical interneuron development in vitro and a reduction of these neurons in uPAR (mouse ortholog of PLAUR) null mice, suggesting that disruption of either gene impacts cortical development similarly. Here, we modify this conclusion, reporting that interneuron numbers are unchanged in the neocortex of Met(fx/fx) / Dlx5/6(cre) mice, in which Met is ablated from cells arising from the ventral telencephalon (VTel). Consistent with this, Met transcript is not detected in the VTel during interneuron genesis and migration; furthermore, during the postnatal period of interneuron maturation, Met is co-expressed in glutamatergic projection neurons, but not interneurons. Low levels of Met protein are expressed in the VTel at E12.5 and E14.5, likely reflecting the arrival of Met containing corticofugal axons. Met expression, however, is induced in E12.5 VTel cells after 2 days in vitro, perhaps underlying discrepancies between observations in vitro and in Met(fx/fx) / Dlx5/6(cre) mice. We suggest that, in vivo, Met impacts the development of cortical projection neurons, whereas uPAR influences interneuron maturation. An altered balance between excitation and inhibition has been postulated as a biological mechanism for ASD; this imbalance could arise from different risk genes differentially affecting either or both elements.

Therapeutic hypothermia for newborn infants with hypoxic-ischaemic encephalopathy

Peripartum asphyxia complicated by moderate or severe hypoxic-ischaemic encephalopathy is a devastating global health issue. A therapeutic 'window of opportunity' exists after resuscitation of the asphyxiated newborn and before the delayed phase of neuronal loss. Animal studies demonstrated that neuronal injury following hypoxia-ischaemia can be prevented or reduced by a mild reduction in brain temperature. Human infant pilot studies confirmed feasibility, without major adverse effects. Randomised trials and systematic reviews comprising term infants with moderate or severe encephalopathy and peripartum asphyxia have established the neuroprotective benefit of therapeutic hypothermia. Hypothermia reduces mortality or major disability to 18 months of age, as well as cerebral palsy, and neuromotor and cognitive delay. Importantly, mortality is reduced without any increase in major neurodevelopmental disability in survivors, and with only minor adverse effects. The evidence supports therapeutic hypothermia when used within strict protocols in tertiary centres to improve the outcome for term and near-term newborns with moderate or severe hypoxic-ischaemic encephalopathy. Equally strict protocols in non-tertiary nurseries will enable earlier initiation of hypothermia under guidance of the regional neonatal intensive care unit and transport team.

Effects of perinatal HIV infection and early institutional rearing on physical and cognitive development of children in Ukraine

To study the effects of perinatal HIV-1 infection and early institutional rearing on the physical and cognitive development of children, 64 Ukrainian uninfected and HIV-infected institutionalized and family-reared children were examined (mean age = 50.9 months). Both HIV infection and institutional care were related to delays in physical and cognitive development, with a larger effect of the rearing environment. Family care, even of compromised quality, was found to be more favorable for children's physical and cognitive development than institutional care. The impact of the quality of child care on physical and cognitive development is discussed in light of future interventions.

Serial MRI and neurodevelopmental outcome in 9- to 10-year-old children with neonatal encephalopathy

OBJECTIVE

To assess the relation between patterns of brain injury on neonatal and childhood magnetic resonance imaging (MRI) and long-term neurodevelopmental outcome.

STUDY DESIGN

Neonatal (n = 34) and childhood MRIs (n = 77) were analyzed for 80 children with neonatal encephalopathy and for 51 control subjects during childhood. MRIs were graded as normal, mildly abnormal (white matter lesions), or moderately/severely abnormal (watershed injury, lesions in basal ganglia/thalamus or focal infarction). Severity of brain injury was related to different aspects of neurologic outcome: Total impairment score of the Movement Assessment Battery for Children, intelligence quotient score, cerebral palsy, postneonatal epilepsy, and need for special education. Seven children with neonatal encephalopathy required extracorporeal membrane oxygenation treatment.

RESULTS

Neonatal and childhood MRI were comparable in 25/33 children (75.8%, P < .001). Children with moderate/severe lesions on neonatal or childhood MRI more often had a total impairment score <or= 15th percentile, an intelligence quotient <or= 85, and cerebral palsy, and attended special education.

CONCLUSION

Different patterns of injury seen on neonatal MRI after neonatal encephalopathy can still be recognized on childhood MRI. Children with moderate to severe brain lesions on neonatal or childhood MRI significantly more often have impaired motor and cognitive outcomes.

Mild neonatal hypoxia-ischemia induces long-term motor- and cognitive impairments in mice

To understand and potentially treat the lifelong cognitive and motor deficits in humans resulting from perinatal mild cerebral hypoxic-ischemic (HI) events, valid animal models are of high importance. Nowadays the murine model of neonatal cerebral HI-injury (unilateral carotid artery occlusion followed by hypoxia) is applied more frequently. In the present study we investigated motor, behavioral and cognitive functioning in mice with mild cerebral HI-injury (45 min of hypoxia; HI-45) in comparison to mice exposed to severe HI (HI-75) and sham-control mice. Lateralizing motor disturbances as measured using the cylinder rearing test developed in both HI-45 and HI-75 mice and was significantly more severe in HI-75 animals. To assess behavior and cognitive functions, we used the modified hole board (mHB) test in two stages. First, the ability of the animals to find the three food rewards in cued holes over time was determined. The results revealed an overall learning impairment in HI-75 mice, while HI-45 mice were not different from sham controls. In the second stage, a reversal test was performed with rewarded cylinders being non-cued and non-rewarded cylinders being cued. This reversal-task revealed impairments in cognitive flexibility in HI-45 mice as compared to sham-control animals. Our data indicate that both the cylinder rearing task and the two stages of the mHB are suitable behavioral approaches to differentiate consequences of neonatal mild and severe brain damage on executive functioning.

Epidemiology of neurodevelopmental disorders in 2 years old Georgian children. Pilot study - population based prospective study in a randomly chosen sample

Three hundred-forty-eight out of a regional population of 1272 newborn infants were randomly chosen and followed neurologically until age of two years to study the epidemiology of neurodevelopmental disorders, and to reveal the main factors influencing outcome. The most frequent neonatal pathologies were low Apgar scores - 45 (3.5%), neonatal sepsis - 28 (2.2%), neonatal seizures - 26 (2.0%), neonatal sepsis complicated with bacterial meningitis - 13 (1.0%), traumatic injury of peripheral nerves - 7 (0.6%), intracranial hemorrhages - 4 (0.3%) and CNS malformations - 3 (0.2%). At the age of 24 months abnormal development was identified in 29 cases (8.5%) of children, comprising global developmental delay in five (1.5%), unclassified motor problems (hypotonia without ataxia) in four (1.2%), cerebral palsy in three (0.9%), behavioral/sleep disorders in 12 (3.5%) and epilepsy in five (1.5%). The most significant single risk factors for abnormal neurodevelopmental outcome were maternal age, chorioamnionitis, gestational age <37 weeks, pathological delivery, and a low (<5) Apgar score at 5min after birth. Coexistence of several risk factors increased the probability of an adverse outcome.

Antenatal allopurinol for reduction of birth asphyxia induced brain damage (ALLO-Trial); a randomized double blind placebo controlled multicenter study

BACKGROUND

Hypoxic-ischaemic encephalopathy is associated with development of cerebral palsy and cognitive disability later in life and is therefore one of the fundamental problems in perinatal medicine. The xanthine-oxidase inhibitor allopurinol reduces the formation of free radicals, thereby limiting the amount of hypoxia-reperfusion damage. In case of suspected intra-uterine hypoxia, both animal and human studies suggest that maternal administration of allopurinol immediately prior to delivery reduces hypoxic-ischaemic encephalopathy.

METHODS/DESIGN

The proposed trial is a randomized double blind placebo controlled multicenter study in pregnant women at term in whom the foetus is suspected of intra-uterine hypoxia.Allopurinol 500 mg IV or placebo will be administered antenatally to the pregnant woman when foetal hypoxia is suspected. Foetal distress is being diagnosed by the clinician as an abnormal or non-reassuring foetal heart rate trace, preferably accompanied by either significant ST-wave abnormalities (as detected by the STAN-monitor) or an abnormal foetal blood scalp sampling (pH < 7.20).Primary outcome measures are the amount of S100B (a marker for brain tissue damage) and the severity of oxidative stress (measured by isoprostane, neuroprostane, non protein bound iron and hypoxanthine), both measured in umbilical cord blood. Secondary outcome measures are neonatal mortality, serious composite neonatal morbidity and long-term neurological outcome. Furthermore pharmacokinetics and pharmacodynamics will be investigated.We expect an inclusion of 220 patients (110 per group) to be feasible in an inclusion period of two years. Given a suspected mean value of S100B of 1.05 ug/L (SD 0.37 ug/L) in the placebo group this trial has a power of 90% (alpha 0.05) to detect a mean value of S100B of 0.89 ug/L (SD 0.37 ug/L) in the 'allopurinol-treated' group (z-test2-sided). Analysis will be by intention to treat and it allows for one interim analysis.

DISCUSSION

In this trial we aim to answer the question whether antenatal allopurinol administration reduces hypoxic-ischaemic encephalopathy in neonates exposed to foetal hypoxia.

TRIAL REGISTRATION NUMBER

Clinical Trials, protocol registration system: NCT00189007.

NF-kappaB inhibition after neonatal cerebral hypoxia-ischemia improves long-term motor and cognitive outcome in rats

We recently demonstrated that inhibition of the NF-kappaB-pathway by the specific peptide inhibitor TAT-NBD markedly reduced cerebral injury in a rat model of perinatal hypoxic-ischemic (HI) brain damage. The aim of the current study was to assess whether neuroprotection by TAT-NBD is associated with long-term functional improvements after neonatal HI. Postnatal-day 7 rats subjected to HI showed motor deficits in the cylinder rearing test and adhesive removal task. HI-treated animals also showed cognitive impairments in a visuo-spatial learning task (modified hole board) as defined by an increased latency to complete this task and increased numbers of short- and long-term memory errors. HI animals treated with TAT-NBD [20mg/kg i.p.] at 0 and 3h post-HI did not show impairments in the cylinder rearing test, adhesive removal task and modified hole board. In conclusion, the almost complete reduction in lesion size observed after TAT-NBD treatment was associated with long-lasting normalization of sensorimotor and cognitive functions.

Bilateral loss of cortical somatosensory evoked potential at birth predicts cerebral palsy in term and near-term newborns

Bilateral loss of cortical somatosensory evoked potential (SEP) is considered the single best indicator of adverse outcome in acute encephalopathy of adult patients and older children. This study determines whether the presence or absence of the neonatal cortical SEP can predict cerebral palsy at two years in survivors of neonatal encephalopathy scored according to Sarnat criteria. We also compare SEPs with visual evoked potentials (VEPs), the EEG and neonatal neurological status. Fifty-nine neonates admitted to the neonatal intensive care unit had SEP, VEP and EEG recordings analysed according to the presence (n=37, 63%) or absence (n=22, 37%) of neonatal encephalopathy (score >or=1). Cortical SEP was always present in the perinatal period in those surviving without major neurological disability, while it was bilaterally absent in all but one patient with a subsequent diagnosis of cerebral palsy. Multivariate analysis using the logistic regression model showed that bilateral loss of cortical SEP and Sarnat Score correctly classified the neurological outcome in all patients. Bilateral absence of cortical SEP indicates early identification of neonates at risk of cerebral palsy indicating that EPs have a clinical role in the workup of neonatal encephalopathy.

Regulation of Kv2.1 phosphorylation in an animal model of anoxia

Conditions such as hypoxia and anoxia inflict serious damage to the brain and continue to be major medical problems. However, the molecular mechanisms that give rise to such damage are not well understood. To elucidate these mechanisms, we established a clinically relevant rodent model of anoxia/recovery by monitoring blood gas levels after oxygen deprivation. Using this animal model, we examined the regulation of Kv2.1, a voltage-gated potassium channel that plays pivotal roles in the homeostasis and survival of neurons. We found that exposure to anoxia induces rapid dephosphorylation of Kv2.1 in the brain, which can be blocked by pre-administration of a NMDA-type glutamate receptor antagonist, memantine. Furthermore, this change is rapidly reversed as the animal recovers from anoxic stress. These results suggest that Kv2.1 is tightly regulated in a clinically relevant animal model of anoxia and further implicate its role in the homeostasis of neurons during anoxic stress.

Poststroke subgranular and rostral subventricular zone proliferation in a mouse model of neonatal stroke

Stroke in the neonatal brain is an understudied cause of neurologic morbidity. Recently we have characterized a new immature mouse model of stroke utilizing unilateral carotid ligation alone to produce infarcts and acute seizures in postnatal day 12 (P12) CD-1 mice. In this study, the amount of poststroke neural progenitor proliferation was examined in the subgranular (SGZ) of the dentate gyrus and the subventricular zone (SVZ) 7, 14, and 21days after ischemia (DAI). A single IP injection (50 mg/kg) of bromodeoxyuridine (BrdU) given 2 hr before perfusion fixation labeled newborn cells. Early cell phenotypes were quantified by colabeling with GFAP, nestin, and DCX. Control mice revealed an age-dependent decrease in neural proliferation, with an approximately 50% drop in BrdU-labeled cell counts at P33 compared with P19 both in the SGZ and in the SVZ. Significant reduction in the amount of neural proliferation in the ipsilateral injured SGZ of ligated mice correlated with both the severity of the stroke-injury and the acute seizure scores. Similar correlations were not detected contralaterally. Contralateral SGZ neural proliferation was initially lowered at 7 DAI but normalized by 21 DAI. In both injured and control brains, approximately 90% of newborn SGZ cells colabeled with nestin, approximately 30% colabeled with GFAP, and a few colabeled with DCX. In contrast, poststroke SVZ cell proliferation was enhanced ipsi- more than contralaterally at 7 DAI. In the SVZ, the enhanced neural proliferation normalized to control levels by P33. In conclusion, the neural cell proliferation was differentially altered in the SGZ vs. SVZ after neonatal stroke.

The spectrum of abnormal neurologic outcomes subsequent to term intrapartum asphyxia

The purpose of this study was to describe the spectrum of possible abnormal neurologic outcomes in term infants with intrapartum asphyxia and to identify those clinical factors associated with the later occurrence of cerebral palsy. All children with term intrapartum asphyxia encountered in a single pediatric neurologic practice with at least 2 years of follow-up and an abnormal neurologic outcome were identified. Abnormal outcomes were grouped into those with or without cerebral palsy. A total of 40 children (28 male, 12 female) met study criteria. Of these, 23 developed cerebral palsy; the remaining 17 children developed an abnormal neurologic outcome that did not include cerebral palsy. A more severe grade of neonatal encephalopathy, a higher number of neonatal seizures, the neonatal use of phenytoin, diffuse abnormalities on imaging, and abnormal findings on neurologic examination at neonatal discharge were all significantly (P<0.05) associated with an abnormal outcome that included cerebral palsy. Abnormal neurologic outcomes other than cerebral palsy subsequent to term intrapartum asphyxia may occur. It appears that a more severe grade of apparent initial clinical injury is more likely to result in an outcome featuring cerebral palsy.

From selective vulnerability to connectivity: insights from newborn brain imaging

The ability to image the newborn brain during development has provided new information regarding the effects of injury on brain development at different vulnerable time periods. Studies in animal models of brain injury correlate beautifully with what is now observed in the human newborn. We now know that injury at term primarily results in grey matter injury while injury in the premature brain predominantly results in a pattern of white matter injury, though recent evidence suggests a blurring of this distinction . These injuries affect how the brain matures subsequently and again, imaging has led to new insights that allow us to match function and structure. This review will focus on these patterns of injury that are so crucially determined by age at insult. In addition, this review will highlight how the brain responds to these insults with changes in connectivity that have profound functional consequences.

A review of developmental outcomes of term infants with post-asphyxia neonatal encephalopathy

BACKGROUND/AIMS

Post-asphyxia neonatal encephalopathy (NE) is one of the main causes of disabilities in term-born infants. This review attempted to investigate the developmental outcomes of term-born infants with post-asphyxia NE.

METHOD

An electronic search on various databases identified 13 empirical studies against the selection criteria modified from the consensus statement from the International Cerebral Palsy Task Force.

RESULTS

The overall quality of methodology of these studies was average. The random effect meta-estimate of the proportion of infants having adverse developmental outcomes such as death, cognitive impairment, sensory-motor impairments was 47% (95% CI 36-57%). Significant heterogeneity (I(2)=87.7%, p<0.00001) between studies indicated variations in number of subjects in studies and their characteristics. For those studies using the Sarnat grading of NE, the proportion of infants with adverse outcomes was nil in stage 1 (mild) NE, 32% in stage 2 (moderate) and almost 100% in stage 3 (severe) NE.

CONCLUSIONS

At present, researchers are using very loose diagnostic criteria of perinatal asphyxia and post-asphyxia NE, making the study samples heterogeneous. Clinicians and researchers are urged to make use of the recent consensus statement regarding diagnostic criteria for intrapartum asphyxia and to identify these high-risk infants for early intervention.

Neonatal watershed brain injury on magnetic resonance imaging correlates with verbal IQ at 4 years

OBJECTIVE

We have previously described patterns of neonatal brain injury that correlate with global cognitive and motor outcomes. We now examine, in survivors of neonatal encephalopathy (presumed secondary to hypoxia-ischemia) without functional motor deficits, whether the severity and neuroanatomical involvement on neonatal MRI are associated with domain-specific cognitive outcomes, verbal and performance IQ, at 4 years of age.

METHODS

In this prospective study, neonatal MRIs of 81 term infants with neonatal encephalopathy were scored for degree of injury in 2 common patterns: watershed distribution and basal ganglia distribution. Follow-up evaluation at 4 years of age by examiners blinded to clinical history and MRIs included a 5-point neuromotor score and the Wechsler Preschool and Primary Scale of Intelligence-Revised. In 64 subjects with no functional motor impairment, test of trend was used to examine the association of ordered watershed-distribution and basal ganglia-distribution MRI scores with mean verbal and performance IQ.

RESULTS

Lower verbal and performance IQs were seen with increasing degree of injury on both watershed-distribution and basal ganglia-distribution scales in univariate analyses. When each MRI pattern score was adjusted for the other, only the association of decreasing verbal IQ with increasing watershed-distribution injury remained significant. A suggestion of decreasing verbal IQ with increasing basal ganglia-distribution injury was also seen in the multivariate model, whereas no association was seen between performance IQ and severity of injury in either MRI pattern.

CONCLUSIONS

In survivors of neonatal encephalopathy without functional motor deficits at 4 years of age, an increasing severity of watershed-distribution injury is associated with more impaired language-related abilities.

Aufmerksamkeitsstörungen nach Schlaganfällen im Kindesalter

Zusammenfassung: Fragestellung: Es wird geklärt, ob es nach Schlaganfällen im Kindes- und Jugendalter zu Aufmerksamkeitsstörungen kommt und welche Einflussfaktoren vorliegen. Methodik: Es wurden die Aufmerksamkeitsleistungen von 78 schlaganfallerkrankten Kindern in Untertests der Testbatterie zur Aufmerksamkeitsprüfung (TAP) sowie der Testbatterie zur Aufmerksamkeitsprüfung für Kinder (KITAP) ausgewertet. Darüber hinaus wurden der Elternfragebogen der CBCL/4-18 sowie eine während der Untersuchung dokumentierte und standardisierte Verhaltensbeobachtung eingesetzt. Die Ergebnisse werden u.a. nach Alter zum Zeitpunkt des Schlaganfalls, betroffener Hemisphäre und Lokalisation des Schlaganfalls miteinander verglichen. Ergebnisse: Nach Schlaganfällen im Kindes- und Jugendalter kommt es vermehrt zu Störungen der Aufmerksamkeitsleistungen. Das Geschlecht, das Alter zum Zeitpunkt des Schlaganfalls und die Lokalisation der Hirnschädigung (kortikal vs. subkortikal) zeigen keinen signifikanten Einfluss. Tendenziell treten Aufmerksamkeitsstörungen häufiger nach rechtshemisphärischen Schlaganfällen auf. Schlussfolgerungen: Es besteht die Notwendigkeit einer frühen Diagnosestellung und wirksamen Behandlung, um der Entstehung komorbider Störungen und Schulschwierigkeiten vorzubeugen.

Long-term functional and protective actions of preconditioning with hypoxia, cobalt chloride, and desferrioxamine against hypoxic-ischemic injury in neonatal rats

Preconditioning with hypoxia and hypoxia-mimetic compounds cobalt chloride (CoCl2) and desferrioxamine (DFX) protects against hypoxic-ischemic (HI) injury in neonatal rat brain. We examined long-term functional and protective actions of preconditioning induced by hypoxia, CoCl(2) and DFX in a neonatal rat model of HI. Postnatal day six rat pups were exposed to preconditioning with hypoxia (8% oxygen) or injections of CoCl(2), DFX or saline vehicle and 24 h later rats underwent HI or sham surgery. Behavioral tests were performed and at the conclusion of experiments, brains removed for morphologic analyses. HI resulted in a large unilateral lesion in the ipsilateral hemisphere compared with sham control rats. All preconditioning treatments significantly reduced the total lesion volume. Behavioral deficits were observed in HI rats compared with sham controls. The reduction in forelimb grasping strength in HI rats was attenuated by preconditioning with hypoxia, CoCl(2) and DFX. HI increased the number of foot faults in a grid-walking test and resulted in forelimb asymmetry in the cylinder test. Only preconditioning with hypoxia reversed all three functional deficits after HI. These findings indicate that preconditioning, especially when induced by hypoxia, has the potential to minimize the morphologic and functional effects of neonatal HI injury.

Corpus callosum size in relation to motor performance in 9- to 10-year-old children with neonatal encephalopathy

Magnetic resonance imaging studies have contributed to recognize the patterns of cerebral injury related to neonatal encephalopathy (NE). We assessed whether a smaller corpus callosum (CC) explained the difference in motor performance between school-age children with NE and controls. Frontal, middle, and posterior areas of the CC were measured in 61 9-10-y-old children with NE and in 47 controls. Motor performance was determined using the Movement Assessment Battery for Children (M-ABC). Linear regression was used to assess whether differences in M-ABC between NE children and controls could be explained by CC size. The CC of 11/30 children with NE type I according to Sarnat (NE I) and 19/36 children with NE type II according to Sarnat (NE II) showed generalized or focal thinning, compared with 8/49 controls. Children with NE II had significantly smaller middle and posterior parts and total areas of the CC. Children with NE scored significantly worse on the M-ABC than controls. The reduction in size of the posterior part of the CC partly explained the mean differences on the M-ABC. Children with NE have poorer motor skills than controls, which is partly explained by a smaller size of the CC.