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

Development of the corpus callosum and cognition after neonatal encephalopathy

OBJECTIVE

Neonatal imaging studies report corpus callosum abnormalities after neonatal hypoxic-ischaemic encephalopathy (HIE), but corpus callosum development and relation to cognition in childhood are unknown. Using magnetic resonance imaging (MRI), we examined the relationship between corpus callosum size, microstructure and cognitive and motor outcomes at early school-age children cooled for HIE (cases) without cerebral palsy compared to healthy, matched controls. A secondary aim was to examine the impact of HIE-related neonatal brain injury on corpus callosum size, microstructure and growth.

METHODS

Participants aged 6-8 years underwent MRI, the Movement Assessment Battery for Children Second Edition and Wechsler Intelligence Scale for Children Fourth Edition. Cross-sectional area, volume, fractional anisotropy and radial diffusivity of the corpus callosum and five subdivisions were measured. Multivariable regression was used to assess associations between total motor score, full-scale IQ (FSIQ) and imaging metrics.

RESULTS

Adjusting for age, sex and intracranial volume, cases (N = 40) compared to controls (N = 39) demonstrated reduced whole corpus callosum area (β = -26.9, 95% confidence interval [CI] = -53.17, -0.58), volume (β = -138.5, 95% CI = -267.54, -9.56), fractional anisotropy and increased radial diffusivity (P < 0.05) within segments II-V. In cases, segment V area (β = 0.18, 95% CI = 0.004, 0.35), volume (β = 0.04, 95% CI = 0.001, 0.079), whole corpus callosum fractional anisotropy (β = 13.8 95% CI = 0.6, 27.1) and radial diffusivity (β = -11.3, 95% CI = -22.22, -0.42) were associated with FSIQ. Growth of the corpus callosum was restricted in cases with a FSIQ ≤85, and volume was reduced in cases with mild neonatal multifocal injury compared to white matter injury alone.

INTERPRETATION

Following neonatal HIE, morphological and microstructural changes in the corpus callosum are associated with reduced cognitive function at early school age.

Motor function and white matter connectivity in children cooled for neonatal encephalopathy

Therapeutic hypothermia reduces the incidence of severe motor disability, such as cerebral palsy, following neonatal hypoxic-ischaemic encephalopathy. However, cooled children without cerebral palsy at school-age demonstrate motor deficits and altered white matter connectivity. In this study, we used diffusion-weighted imaging to investigate the relationship between white matter connectivity and motor performance, measured using the Movement Assessment Battery for Children-2, in children aged 6-8 years treated with therapeutic hypothermia for neonatal hypoxic-ischaemic encephalopathy at birth, who did not develop cerebral palsy (cases), and matched typically developing controls. Correlations between total motor scores and diffusion properties in major white matter tracts were assessed in 33 cases and 36 controls. In cases, significant correlations (FDR-corrected P < 0.05) were found in the anterior thalamic radiation bilaterally (left: r = 0.513; right: r = 0.488), the cingulate gyrus part of the left cingulum (r = 0.588), the hippocampal part of the left cingulum (r = 0.541), and the inferior fronto-occipital fasciculus bilaterally (left: r = 0.445; right: r = 0.494). No significant correlations were found in controls. We then constructed structural connectivity networks, for 22 cases and 32 controls, in which nodes represent brain regions and edges were determined by probabilistic tractography and weighted by fractional anisotropy. Analysis of whole-brain network metrics revealed correlations (FDR-corrected P < 0.05), in cases, between total motor scores and average node strength (r = 0.571), local efficiency (r = 0.664), global efficiency (r = 0.677), clustering coefficient (r = 0.608), and characteristic path length (r = -0.652). No significant correlations were found in controls. We then investigated edge-level association with motor function using the network-based statistic. This revealed subnetworks which exhibited group differences in the association between motor outcome and edge weights, for total motor scores (P = 0.0109) as well as for balance (P = 0.0245) and manual dexterity (P = 0.0233) domain scores. All three of these subnetworks comprised numerous frontal lobe regions known to be associated with motor function, including the superior frontal gyrus and middle frontal gyrus. The subnetwork associated with total motor scores was highly left-lateralised. These findings demonstrate an association between impaired motor function and brain organisation in school-age children treated with therapeutic hypothermia for neonatal hypoxic-ischaemic encephalopathy.

Cooling in mild encephalopathy: Costs and perils of therapeutic creep

Increasing confidence in therapeutic hypothermia and ambiguity of cooling guidelines has led to many clinicians extending its use to untested populations like mild encephalopathy, or even no encephalopathy. Poor quality clinical neurological examination for encephalopathy staging coupled with a fear of litigation if a baby with mild encephalopathy progress to moderate or severe encephalopathy appears to be the primary driver for this therapeutic creep. Recent data suggesting increased apoptosis with cooling uninjured brains, and lack of hypothermic neuroprotection in partial prolonged hypoxia, implies that such therapeutic creeps may cause more harm than benefit. Currently available preclinical and clinical data do not support the clinical use of therapeutic hypothermia for mild encephalopathy, although phase II clinical trials are ongoing. We recommend that until further evidence from adequately powered randomised controlled trials are available, cooling in mild encephalopathy need to be considered experimental and parental consent should be obtained before providing this therapy.

Diffusion Tensor Imaging in Very Preterm, Moderate-Late Preterm and Term-Born Neonates: A Systematic Review

OBJECTIVE

To examine white matter abnormalities, measured by diffusion tensor imaging, in very preterm (<32 weeks) and moderate-late preterm neonates (32-37 weeks) at term-equivalent age, compared with healthy full-term controls (≥37 weeks).

STUDY DESIGN

A search of Medline (PubMed) was conducted to identify studies with diffusion data collected on very preterm, moderate-late preterm and full-term neonates, using the guidelines from the Meta-analysis of Observational Studies in Epidemiology and PRISMA statements.

RESULTS

Eleven studies were included with diffusion tensor imaging data from 554 very preterm, 575 moderate-late preterm, and 318 full-term neonates. Widespread statistically significant diffusion measures were found in all preterm subgroups at term-equivalent age compared with full-term neonates, and this difference was more marked for the very preterm group. These abnormalities are suggestive of changes in the white matter microstructure in the preterm groups. The corpus callosum was a region of interest in both early and moderate-late preterm groups, which showed statistically significant diffusion measures in all 11 studies.

CONCLUSIONS

Microstructural white matter changes may underpin the increased risk of neurodevelopmental disability seen in preterm infants in later life. diffusion tensor imaging may therefore be a useful prognostic tool for neuro-disability in preterm neonates.

Disrupted brain connectivity in children treated with therapeutic hypothermia for neonatal encephalopathy

Therapeutic hypothermia following neonatal encephalopathy due to birth asphyxia reduces death and cerebral palsy. However, school-age children without cerebral palsy treated with therapeutic hypothermia for neonatal encephalopathy still have reduced performance on cognitive and motor tests, attention difficulties, slower reaction times and reduced visuo-spatial processing abilities compared to typically developing controls. We acquired diffusion-weighted imaging data from school-age children without cerebral palsy treated with therapeutic hypothermia for neonatal encephalopathy at birth, and a matched control group. Voxelwise analysis (33 cases, 36 controls) confirmed reduced fractional anisotropy in widespread areas of white matter in cases, particularly in the fornix, corpus callosum, anterior and posterior limbs of the internal capsule bilaterally and cingulum bilaterally. In structural brain networks constructed using probabilistic tractography (22 cases, 32 controls), graph-theoretic measures of strength, local and global efficiency, clustering coefficient and characteristic path length were found to correlate with IQ in cases but not controls. Network-based statistic analysis implicated brain regions involved in visuo-spatial processing and attention, aligning with previous behavioural findings. These included the precuneus, thalamus, left superior parietal gyrus and left inferior temporal gyrus. Our findings demonstrate that, despite the manifest successes of therapeutic hypothermia, brain development is impaired in these children.

Diffusion tensor imaging in neonatal encephalopathy: a systematic review

BACKGROUND AND OBJECTIVE

Diffusion tensor imaging (DTI) during the first few days of life can be used to assess brain injury in neonates with neonatal encephalopathy (NE) for outcome prediction. The goal of this review was to identify specific white matter tracts of interest that can be quantified by DTI as being altered in neonates with this condition, and to investigate its potential prognostic ability.

METHODS

Searches of Medline and the Cochrane Database of Systematic Reviews were conducted to identify studies with diffusion data collected in term-born neonates with NE.

RESULTS

19 studies were included which described restricted diffusion in encephalopathic neonates as compared with healthy controls, with the posterior limb of the internal capsule and the genu and splenium of the corpus callosum identified as particular regions of interest. Restricted diffusion was related to adverse outcomes in the studies that conducted a follow-up of these infants.

CONCLUSIONS

Obtaining diffusion measures in these key white matter tracts early in life before pseudonormalisation can occur can not only identify the extent of the damage but also can be used to examine the effectiveness of treatment and to predict neurodevelopmental outcome.

Motor performance and cognitive correlates in children cooled for neonatal encephalopathy without cerebral palsy at school age

AIM

To investigate whether motor performance in school-age children without cerebral palsy (CP), cooled for neonatal encephalopathy, is associated with perinatal factors and 18-month developmental scores and to explore relationships between school-age motor and cognitive performance.

METHODS

Motor and cognitive performance was assessed in 29 previously cooled children at six to eight years using the Movement Assessment Battery for Children-2 (MABC-2) and the Wechsler Intelligence Scale for Children (WISC-IV). Associations between MABC-2 scores less than/equal (≤) 15th centile and perinatal factors, social/family background, 18-month Bayley-III scores and WISC-IV scores were explored.

RESULTS

Eleven of the 29 (38%) children had MABC-2 scores ≤15th centile including 7 (24%) ≤5th centile. No significant perinatal or socio-economic risk factors were identified. Motor scores <85 at 18 months failed to identify children with MABC-2 scores ≤15th centile. MABC-2 scores ≤15th centile were associated with lower Full Scale IQ (p = 0.045), Working Memory (p = 0.03) and Perceptual Reasoning (p = 0.005) scores at six to eight years and receiving greater support in school (p = 0.01).

CONCLUSION

A third of cooled children without CP had MABC-2 scores indicating motor impairment at school age that was not identified at 18 months by Bayley-III. Most children with low MABC scores needed support at school. Sub-optimal MABC-2 scores indicate need for detailed school-age cognitive evaluation.

Comparison of MRI and neurosonogram 1- and 2-dimensional morphological measurements of the newborn corpus callosum

BACKGROUND

Developmental abnormalities of the corpus callosum (CC) are linked to multiple neuro-developmental disorders, for which neonatal neuroimaging may allow earlier diagnosis and intervention. MRI is often considered the most sensitive imaging modality to white matter changes, while neurosonogram (NS) remains the clinical staple. This study assesses the correlation between MRI and US measurements of the neonatal CC using a protocol derived from established methodologies.

METHODS

MR and NS images from an existing cohort of term infants (≥37 weeks gestational age) were studied. Length and area measurements of the CC made with linear (LUS) and phased array US (PUS) data were compared to those from MRI. Intra-observer reliabilities were estimated.

RESULTS

Moderate-to-strong correlation strengths were observed for length measurements and the total area of the CC. Sectional area measurements showed poorer correlations. Bland-Altman plots support improved correspondence of length and total area measurements. LUS data appeared to correspond closer to MRI. All three modalities showed comparable repeatability.

CONCLUSION

NS correlates well with some MRI measurements of the CC and shows similar levels of repeatability, making them possibly interchangeable. Use of LUS, a technique rarely used for NS, may be preferable to the standard approach for morphological studies.

Severe Perinatal Hypoxic-Ischemic Brain Injury Induces Long-Term Sensorimotor Deficits, Anxiety-Like Behaviors and Cognitive Impairment in a Sex-, Age- and Task-Selective Manner in C57BL/6 Mice but Can Be Modulated by Neonatal Handling

Perinatal brain injury (PBI) leads to neurological disabilities throughout life, from motor deficits, cognitive limitations to severe cerebral palsy. Yet, perinatal brain damage has limited therapeutic outcomes. Besides, the immature brain of premature children is at increased risk of hypoxic/ischemic (HI) injury, with males being more susceptible to it and less responsive to protective/therapeutical interventions. Here, we model in male and female C57BL/6 mice, the impact of neonatal HI and the protective effects of neonatal handling (NH), an early life tactile and proprioceptive sensory stimulation. From postnatal day 1 (PND1, modeling pre-term) to PND21 randomized litters received either NH or left undisturbed. HI brain damage occurred by permanent left carotid occlusion followed by hypoxia at PND7 (modeling full-term) in half of the animals. The behavioral and functional screening of the pups at weaning (PND23) and their long-term outcomes (adulthood, PND70) were evaluated in a longitudinal study, as follows: somatic development (weight), sensorimotor functions (reflexes, rods and hanger tests), exploration [activity (ACT) and open-field (OF) test], emotional and anxiety-like behaviors [corner, open-field and dark-light box (DLB) tests], learning and memory [T-maze (TM) and Morris Water-Maze (MWM)]. HI induced similar brain damage in both sexes but affected motor development, sensorimotor functions, induced hyperactivity at weaning, and anxiety-like behaviors and cognitive deficits at adulthood, in a sex- and age-dependent manner. Thus, during ontogeny, HI affected equilibrium especially in females and prehensility in males, but only reflexes at adulthood. Hyperactivity of HI males was normalized at adulthood. HI increased neophobia and other anxiety-like behaviors in males but emotionality in females. Both sexes showed worse short/long-term learning, but memory was more affected in males. Striking neuroprotective effects of NH were found, with significantly lower injury scores, mostly in HI males. At the functional level, NH reversed the impaired reflex responses and improved memory performances in hippocampal-dependent spatial-learning tasks, especially in males. Finally, neuropathological correlates referred to atrophy, neuronal densities and cellularity in the affected areas [hippocampal-CA, caudate/putamen, thalamus, neocortex and corpus callosum (CC)] point out distinct neuronal substrates underlying the sex- and age- functional impacts of these risk/protection interventions on sensorimotor, behavioral and cognitive outcomes from ontogeny to adulthood.

The long-term effect of perinatal asphyxia on hippocampal volumes

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) in term-born infants can lead to memory problems. The hippocampus is important for long-term episodic memory. The primary aim was to investigate the effect of HIE on hippocampal volumes in 9- to 10-year-old children. The secondary aim was to investigate the association between hippocampal volumes and previously found impaired memory and cognitive functions in the current cohort.

METHODS

In total 26 children with mild HIE, 26 with moderate HIE, and 37 controls were included. The intelligence quotient (IQ) and memory were tested. A 3D-volumetric MRI was obtained. Brain segmentation was performed for hippocampal volumes and intracranial volume. The differences in hippocampal volumes, memory, and IQ between the groups were determined. Multivariable linear regression analyses were performed, including hippocampal volume as a percentage of intracranial volume as a dependent variable.

RESULTS

Smaller hippocampal volumes were found in moderate HIE (p < 0.001), with a trend toward smaller volumes in mild HIE, compared to controls. In multivariable linear regression analysis, hippocampal volume as a percentage of intracranial volume was significantly associated with long-term visuospatial memory.

CONCLUSION

Children with moderate HIE had smaller hippocampal volumes than controls, with a trend toward smaller volumes following mild HIE. Reduced hippocampal volumes were associated with poorer long-term visuospatial memory.

Neurodevelopmental outcome in survivors of hypoxic ischemic encephalopathy without cerebral palsy

To access outcome following hypoxic ischemic encephalopathy (HIE), survivors without cerebral palsy were invited for formal developmental assessment. Children aged ≥ 42 months were assessed using the NEPSY-2, Movement Assessment Battery for Children 2 (Movement ABC-2), Behavior Rating Inventory of Executive Function, and the Child Behavior Checklist. Children aged < 42 months were assessed using the Bayley Scales of Infant and Toddler Development, Third Edition (BSITD-3). One hundred forty-six children attended for assessments [Grade 1 (112), Grade 2 (33), and Grade 3 (1)]. BSITD-3 did not identify significant rates of impairment on cognitive, motor, or language subtests. A significant proportion of children scored < 3rd percentile on the adaptive behavior scale. In older age groups, difficulties were seen in 16/24 NEPSY-2 subtests and on timed assessments using Movement ABC-2. Difficulties arose especially in the "control" aspects of cognition and behavior. Behavioral difficulties were common with internalizing problems predominating. There was a graded effect with grade 2 cases differing significantly from grade 1 cases.

CONCLUSION

Following HIE, children may experience attention, memory, and behavior difficulties which are not always evident at a young age. The adaptive behavior questionnaire may be a useful tool to select children requiring developmental surveillance beyond 2 years of age. What is known: • Diversity of outcome across grades of HIE is reported and few studies have looked at the milder consequences of HIE at school age. What is new: • Following HIE children may experience attention, memory, and behavior difficulties which are not always evident at a young age. • The adaptive behavior questionnaire may be a useful tool to select children requiring developmental surveillance beyond 2 years of age.

Association of transcallosal motor fibres with function of both hands after unilateral neonatal arterial ischemic stroke

AIM

The objective of this study was to investigate the involvement of the motor fibres of the corpus callosum after unilateral neonatal arterial ischemic stroke (NAIS) of the middle cerebral artery territory and the relationship to both ipsilesional and contralesional hand function.

METHOD

Using high-resolution structural magnetic resonance imaging (MRI), functional MRI, and magnetic resonance diffusion-tractography, we compared the midsagittal area of the motor part of the corpus callosum (defined by the fibres connecting the precentral gyri) between 33 7-year-old children after unilateral NAIS and 31 typically developing 7-year-old children. Hand motor performance was assessed by the box and blocks test.

RESULTS

Children after NAIS showed on average significantly smaller motor corpus callosum area compared to typically developing children (p<0.001, without differences of the non-motor corpus callosum area). In addition, there was a significant positive association between the motor part of the corpus callosum and both contralesional (Pr(>|t|)=0.034) and ipsilesional hand motor performance (Pr(>|t|)=0.006) after controlling for lesion volume and sex. In a post-hoc analysis the additional contribution of corticospinal tract damage was evaluated.

INTERPRETATION

Compared to typically developing children, children after NAIS exhibited a smaller motor part of their corpus callosum associated with reduced contralesional but also ipsilesional manual dexterity. These results indicate that the affection of transcallosal motor fibres in unilateral NAIS might be of functional relevance and an important part of the involved structural network that should be elucidated in further studies.

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

OBJECTIVE

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

STUDY DESIGN

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

RESULTS

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

CONCLUSION

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

Structural brain differences in school-age children with and without single-suture craniosynostosis

OBJECTIVE Single-suture craniosynostosis (SSC), the premature fusion of a cranial suture, is characterized by dysmorphology of the craniofacial skeleton. Evidence to suggest that children with SSC are at an elevated risk of mild to moderate developmental delays and neurocognitive deficits is mounting, but the associations among premature suture fusion, neuroanatomy, and neurocognition are unexplained. The goals of this study were to determine 1) whether differences in the brain are present in young children with the 2 most common forms of SSC (sagittal and metopic) several years following surgical correction, and 2) whether the pattern of differences varies by affected suture (sagittal or metopic). Examination of differences in the brains of children with SSC several years after surgery may illuminate the growth trajectory of the brain after the potential constraint of the dysmorphic cranium has been relieved. METHODS The authors compared quantitative measures of the brain acquired from MR images obtained from children with sagittal or metopic craniosynostosis (n = 36) at 7 years of age to those obtained from a group of unaffected controls (n = 27) at the same age. The authors measured the volumes of the whole brain, cerebral cortex, cerebral white matter, cerebral cortex by lobe, and ventricles. Additionally, they measured the midsagittal area of the corpus callosum and its segments and of the cerebellar vermis and its component lobules. Measurements obtained from children with SSC and controls were compared using linear regression models. RESULTS No volume measures of the cerebrum or of the whole brain differed significantly between patients with SSC and controls (p > 0.05). However, ventricle volume was significantly increased in patients with SSC (p = 0.001), particularly in those with sagittal craniosynostosis (p < 0.001). In contrast, the area of the corpus callosum was significantly reduced in patients with metopic synostosis (p = 0.04), particularly in the posterior segments (p = 0.004). Similarly, the area of lobules VI-VII of the cerebellar vermis was reduced in patients with SSC (p = 0.03), with those with metopic craniosynostosis showing the greatest reduction (p = 0.01). CONCLUSIONS The lack of differences in overall brain size or regional differences in the size of the lobes of the cerebrum in children with metopic and sagittal synostosis suggests that the elevated risk of neurodevelopmental deficits is not likely to be associated with differences in the cerebral cortex. Instead, this study showed localized differences between sagittal and metopic craniosynostosis cases as compared with controls in the ventricles and in the midsagittal structures of the corpus callosum and the cerebellum. It remains to be tested whether these structural differences are associated with the increased risk for developmental delay and neurocognitive deficits in children with SSC.

Limitations in the Activity of Mobility at Age 6 Years After Difficult Birth at Term: Prospective Cohort Study

BACKGROUND

A difficult birth at term (DBAT) may manifest as fetal acidosis and low Apgar scores and is often referred to as "perinatal asphyxia," especially when infants show signs of neonatal encephalopathy (NE). In contrast to DBAT resulting in moderate-to-severe NE, which is associated with neurodevelopmental disorders, little is known about the prognosis of less severe forms of DBAT, with or without NE.

OBJECTIVE

The purpose of this study was to evaluate the International Classification of Functioning, Disability and Health, Children & Youth Version activity "mobility" and other neurodevelopmental sequelae in infants with DBAT at age 6 years.

METHODS

The index cohort (n=62; 35 boys, 27 girls) consisted of consecutive term infants with DBAT based on clinical criteria in a Dutch nonacademic hospital from 1999 to 2005. Neonatal encephalopathy was assessed according to the Sarnat grading system and excluded infants with severe NE. The matched reference cohort (n=81; 49 boys, 32 girls) consisted of healthy term infants. The primary outcome at 6 years was limited mobility (Movement Assessment Battery for Children score ≤15th percentile). Secondary outcomes included learning and behavioral problems and the presence of minor neurological dysfunction.

RESULTS

Three children developed cerebral palsy and were excluded from analyses. Children with DBAT more often had limited mobility than children without DBAT (risk ratio [RR]=2.44; 95% confidence interval [95% CI]=1.16, 5.14). The risk of limited mobility rose with increasing severity of NE (mild NE: RR=3.38; 95% CI=1.40, 8.16; moderate NE: RR=4.00; 95% CI=1.54, 10.40), and manual abilities especially were affected (RR=4.12; 95% CI=1.40, 12.14). Learning problems, need for physical therapy, and complex minor neurological dysfunction were more common in children with DBAT than in children without DBAT.

CONCLUSIONS

Term infants who develop mild or moderate NE following DBAT are at increased risk for limited mobility at age 6 years. Routine monitoring of neuromotor development in these children is warranted.

Neonatal Magnetic Resonance Imaging Pattern of Brain Injury as a Biomarker of Childhood Outcomes following a Trial of Hypothermia for Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVE

To examine the ability of magnetic resonance imaging (MRI) patterns of neonatal brain injury defined by the National Institute of Child Health and Human Development Neonatal Research Network to predict death or IQ at 6-7 years of age following hypothermia for neonatal encephalopathy.

STUDY DESIGN

Out of 208 participants, 124 had MRI and primary outcome (death or IQ <70) data. The relationship between injury pattern and outcome was assessed.

RESULTS

Death or IQ <70 occurred in 4 of 50 (8%) of children with pattern 0 (normal MRI), 1 of 6 (17%) with 1A (minimal cerebral lesions), 1 of 4 (25%) with 1B (extensive cerebral lesions), 3 of 8 (38%) with 2A (basal ganglia thalamic, anterior or posterior limb of internal capsule, or watershed infarction), 32 of 49 (65%) with 2B (2A with cerebral lesions), and 7 of 7 (100%) with pattern 3 (hemispheric devastation), P < .001; this association was also seen within hypothermia and control subgroups. IQ was 90 ± 13 among the 46 children with a normal MRI and 69 ± 25 among the 50 children with an abnormal MRI. In childhood, for a normal outcome, a normal neonatal MRI had a sensitivity of 61%, specificity of 92%, a positive predictive value of 92%, and a negative predictive value of 59%; for death or IQ <70, the 2B and 3 pattern combined had a sensitivity of 81%, specificity of 78%, positive predictive value of 70%, and a negative predictive value of 87%.

CONCLUSIONS

The Neonatal Research Network MRI pattern of neonatal brain injury is a biomarker of neurodevelopmental outcome at 6-7 years of age.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00005772.

Therapeutic hypothermia modifies perinatal asphyxia-induced changes of the corpus callosum and outcome in neonates

What Is Known about this Subject?

Diffusion-weighted MRI has demonstrated changes in the corpus callosum of term neonates with perinatal asphyxia. The severity of cerebral changes demonstrated using diffusion-weighted MRI is difficult to assess without measuring values of the Apparent Diffusion Coefficient (ADC).

What Is New?

ADC values of the anterior part of the corpus callosum are slightly higher than of the posterior part in full term infants with perinatal asphyxia. Low ADC values of the corpus callosum were associated with an adverse outcome in infants with perinatal asphyxia. In infants treated with hypothermia lower ADC values than with normothermia were associated with a poor outcome, supporting neuroprotective effects of hypothermia

Background

Using MRI, changes can be detected in the corpus callosum (CC) following perinatal asphyxia which are associated with later neurodevelopmental outcome.

Aim

To study the association between the apparent diffusion coefficient of water (ADC) in the CC on MRI in neonates with perinatal asphyxia and neurodevelopmental outcome at 18 months of age.

Subjects, Methods

Of 121 infants 32 (26%) died and 13 (11%) survived with an adverse neurological outcome. Sixty-five (54%) received therapeutic hypothermia. MRI was performed within 7 days after birth using a 1.5 T or 3.0 T system, and ADC values were measured in the anterior and posterior CC. The association between ADC and composite outcome (death or abnormal neurodevelopment) was analyzed for both normothermia and hypothermia cases using receiver operating characteristics.

Results

ADC values of the posterior CC were lower than of the anterior part (mean difference 0.050 x 10^-3 mm²/s, p<0.001). Field strength did not affect ADC values. ADC values of the posterior part of the CC were significantly lower in infants with basal ganglia/thalamus or near total brain injury (p<0.001). Lower ADC values were associated with an adverse outcome, but cut-off levels were lower after hypothermia (1.024 x 10^-3 mm²/s vs 0.969 x 10^-3 mm²/s)

Conclusion

Low ADC values of the posterior part of the corpus callosum are associated with an adverse outcome in term or near term neonates with perinatal asphyxia. Therapeutic hypothermia slightly modifies this association, showing that lower values were needed for an adverse outcome.

Development of cerebral gray and white matter injury and cerebral inflammation over time after inflammatory perinatal asphyxia

Antenatal inflammation is associated with increased severity of hypoxic-ischemic (HI) encephalopathy and adverse outcome in human neonates and experimental rodents. We investigated the effect of lipopolysaccharide (LPS) on the timing of HI-induced cerebral tissue loss and gray matter injury, white matter injury and integrity, and the cerebral inflammatory response. On postnatal day 9, mice underwent HI by unilateral carotid artery occlusion followed by systemic hypoxia which resulted in early neuronal damage (MAP2 loss) at 3 h that did not increase up to day 15. LPS injection 14 h before HI (LPS+HI) significantly and gradually aggravated MAP2 loss from 3 h up to day 15, resulting in an acellular cystic lesion. LPS+HI increased white matter damage, reduced myelination in the corpus callosum and increased white matter fiber coherency in the cingulum. The number of oligodendrocytes throughout the lineage (Olig2-positive) was increased whereas more mature myelinating (CNPase-positive) oligodendrocytes were strongly decreased after LPS+HI. LPS+HI induced an increased and prolonged expression of cerebral cytokines/chemokines compared to HI. Additionally, LPS+HI increased macrophage/microglia activation and influx of neutrophils in the brain compared to HI. This study demonstrates the sensitizing effect of LPS on neonatal HI brain injury for an extended time-frame up to 15 days postinsult. LPS before HI induced a gradual increase in gray and white matter deficits, including reduced numbers of more mature myelinating oligodendrocytes and a decrease in white matter integrity. Moreover, LPS+HI prolonged and intensified the cerebral inflammatory response, including cellular infiltration. In conclusion, as the timing of damage and/or involved pathways are changed when HI is preceded by inflammation, experimental therapies might require modifications in the time window, dosage or combinations of therapies for efficacious neuroprotection.

Functional connectivity in preterm infants derived from EEG coherence analysis

OBJECTIVE

To quantify the neuronal connectivity in preterm infants between homologous channels of both hemispheres.

METHODS

EEG coherence analysis was performed on serial EEG recordings collected from preterm infants with normal neurological follow-up. The coherence spectrum was divided in frequency bands: δnewborn(0-2 Hz), θnewborn(2-6 Hz), αnewborn(6-13 Hz), βnewborn(13-30 Hz). Coherence values were evaluated as a function of gestational age (GA) and postnatal maturation.

RESULTS

All spectra show two clear peaks in the δnewborn and θnewborn-band, corresponding to the delta and theta EEG waves observed in preterm infants. In the δnewborn-band the peak magnitude coherence decreases with GA and postnatal maturation for all channels. In the θnewborn-band, the peak magnitude coherence decreases with GA for all channels, but increases with postnatal maturation for the frontal polar channels. In the βnewborn-band a modest magnitude coherence peak was observed in the occipital channels, which decreases with GA.

CONCLUSIONS

Interhemispherical connectivity develops analogously with electrocortical maturation: signal intensities at low frequencies decrease with GA and postnatal maturation, but increase at high frequencies with postnatal maturation. In addition, peak magnitude coherence is a clear trend indicator for brain maturation.

SIGNIFICANCE

Coherence analysis can aid in the clinical assessment of the functional connectivity of the infant brain with maturation.

Early neurophysiology and MRI in predicting neurological outcome at 9-10 years after birth asphyxia

OBJECTIVE

To assess whether early somatosensory evoked potentials (SEP) predict long-term neurodevelopmental outcome in normothermic, full-term infants with mild to moderate neonatal encephalopathy (NE), and to compare their predictive value to already available amplitude integrated EEG (aEEG) and magnetic resonance imaging (MRI).

METHODS

Fifty-six infants with post-asphyxia NE were prospectively recruited, and their SEP, aEEG and MRI data were acquired during the first five days. Follow-up continued to 9-10 years for assessment of neuromotor and neurocognitive development. We analysed SEP latency (N1 component), normality of aEEG background pattern, as well as patterns of injury on the neonatal MRI. Neurological outcome measures at 9-10 years included conventional MRI, Movement-ABC and the WISC-III NL.

RESULTS

A SEP latency <50 ms during the first five days was associated with a normal neuromotor outcome (p < 0.03), and a prolonged day 3 latency was associated with lower childhood IQ (p = 0.02). The presence of multiple seizures in aEEG, as well as a moderate or severe injury on the neonatal MRI was associated with a poor neuromotor score (p = 0.03 and p < 0.01, respectively). Combination of multiple techniques improved prediction of long-term outcome compared to single modality.

CONCLUSION

Early SEPs provide information that is comparable to the already available aEEG and MRI paradigms in the prediction of long-term outcome of full-term infants with mild to moderate neonatal encephalopathy.

SIGNIFICANCE

The present results call for further studies using early SEP to aid early assessment of infants treated with hypothermia.

Fine motor skills and interhemispheric transfer in treatment-naive male children with Tourette syndrome

AIM

This study addressed whether Tourette syndrome is associated with an impairment of fine motor skills or altered interhemispheric transfer. We additionally investigated the association between interhemispheric transfer and size of the corpus callosum.

METHOD

The sample, a subsample of our larger neuroimaging sample, included 27 treatment-naive males with 'pure' Tourette syndrome (age range 10y 2mo-14y 4mo; mean age 11y 10mo, SD 1y 2mo) and 26 matched healthy comparison children (age range 10y 2mo-14y 4mo; mean age 11y 10mo, SD 1y 1mo). A finger tapping task and the Purdue Pegboard were used to assess fine motor skills. Interhemispheric transfer time (ITT) was measured with the Poffenberger paradigm. The neuroanatomical data were derived from our previous neuroimaging study.

RESULTS

ITT was negatively correlated with the size of callosal subregion 3 (r=-0.366, p=0.028), indicating that a shorter ITT was associated with a larger corpus callosum.

INTERPRETATION

Our findings support the assumption that previously reported impairment of motor skills in Tourette syndrome does not directly result from tics but from other factors such as medication or comorbidities. Following the assumption that callosal subregion 3 in Tourette syndrome grows as a consequence of tic performance over years, our preliminary results suggest that this growth might accelerate interhemispheric transfer in Tourette syndrome.

Increased putamen and callosal motor subregion in treatment-naïve boys with Tourette syndrome indicates changes in the bihemispheric motor network

BACKGROUND

Despite an increasing number of studies, findings of structural brain alterations in patients with Tourette syndrome are still inconsistent. Several confounders (comorbid conditions, medication, gender, age, IQ) might explain these discrepancies. In the present study, these confounders were excluded to identify differences in basal ganglia and corpus callosum size that can be ascribed more probably to Tourette syndrome per se.

METHODS

High-resolution T1-weighted structural magnetic resonance images of 49 boys with Tourette syndrome were compared with those of 42 healthy boys. The groups were matched for IQ and age (9 to 15 years). Boys with comorbid conditions and previous treatment were excluded. Volumes of gray and white matter, cerebrospinal fluid as well as the size of the basal ganglia, the thalamus, the corpus callosum and its subregions were estimated.

RESULTS

The left and right putamen and subregion 3 of the corpus callosum were larger in boys with Tourette syndrome than in healthy controls. No differences were found in volumes of caudate nucleus, globus pallidus or thalamus of each hemisphere or in total callosal size and its other subregions.

CONCLUSIONS

Bilateral enlargement of the putamen may reflect dopaminergic dysfunction or neuroimmunologic alterations (PANDAS) underlying Tourette syndrome. The larger callosal motor subregion 3 might be a consequence of daily tic activity. Previous divergent volumetric findings might be ascribed to confounding variables like comorbid conditions or medication, or to different imaging methods.

Hypoxic-ischemic encephalopathy: challenges in outcome and prediction

The outcomes of hypoxic-ischemic encephalopathy vary between death and intact survival. The spectrum of long-term morbidity in survivors ranges from mild motor and cognitive deficits to cerebral palsy and severe cognitive deficits. Our literature review reinforces the notion that the spectrum of hypoxic-ischemic encephalopathy outcomes represents a continuum, which has important implications for the prediction of outcome and the indications for intervention. We summarize predictive criteria at 3 time points: the first 6 hours of life, 6-72 hours of life, and at hospital discharge. In this era of neuroprotection, predictive models that aid therapeutic decision making, including the withdrawal of support, need to be revised.

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.

Age-related regional variations of the corpus callosum identified by diffusion tensor tractography

The corpus callosum is the largest white matter connection in the human brain, and an understanding of its evolution with age in healthy individuals is one crucial aspect for determining its role in cognition and disease. Diffusion tensor imaging (DTI) allows for investigation of age-related callosal changes since tractography can both virtually reconstruct the segments of the corpus callosum in vivo based on unique target cortical regions, and provide quantitative diffusion parameters reflecting tissue microstructure. DTI tractography was used to subdivide the corpus callosum into seven distinct sections based on unique target areas (i.e., orbital frontal, anterior frontal, superior frontal, superior parietal, posterior parietal, temporal, and occipital) in a very large number of healthy volunteers (n=315) across a wide age range (5-59 years). Both fractional anisotropy (FA) and mean diffusivity (MD) changes with respect to age were fit with Poisson curves, showing increasing FA and decreasing MD during childhood and adolescence and slightly slower decreases of FA and increases of MD at older ages. Age at peak FA values and minimum MD values varied from 21 to 44 years, and an overall "outer-to-inner" trend was observed in which the anterior and posterior regions peaked earlier than central areas. In addition to these maturational trends of diffusion parameters reflecting the microstructural changes in the healthy corpus callosum over a large age range spanning childhood to older adulthood, these results can provide a baseline for identifying the presence and timing of callosal abnormalities in various brain disorders.

Evolving understanding of hypoxic-ischemic encephalopathy in the term infant

Our aim was to document changes in the evaluation and prognosis of term-born infants with neonatal encephalopathy of hypoxic-ischemic origin, with particular reference to our own experiences and influences, and to summarize the debate on causation and the relative importance of antenatal and perinatal factors. High quality neonatal cranial ultrasound and magnetic resonance imaging and spectroscopy have enabled the accurate early visualization of different patterns of hypoxic-ischemic brain injury and prediction of their associated outcomes. Long-term follow-up shows that cognitive and memory difficulties may follow even in children without motor deficits. The very early use of electrophysiologic methods has allowed broad prognostic categorization of infants when this is not possible from clinical assessment or imaging, providing a rationale for entry into intervention trials, such as therapeutic hypothermia. This work has also shown that most of these infants have evidence of acute hypoxic-ischemic brain injury that explains their symptoms and outcomes.