Altered neonatal white and gray matter microstructure is associated with neurodevelopmental impairments in very preterm infants with high-grade brain injury

BACKGROUND

This study examines relationships between neonatal white and gray matter microstructure and neurodevelopment in very preterm (VPT) infants (≤30 weeks gestation) with high-grade brain injury (BI).

METHODS

Term-equivalent diffusion tensor magnetic resonance imaging data were obtained in 32 VPT infants with high-grade BI spanning grade III/IV intraventricular hemorrhage, post-hemorrhagic hydrocephalus (PHH), and cystic periventricular leukomalacia (BI group); 69 VPT infants without high-grade injury (VPT group); and 55 term-born infants. The Bayley-III assessed neurodevelopmental outcomes at age 2 years.

RESULTS

BI infants had lower fractional anisotropy (FA) in the posterior limb of the internal capsule (PLIC), cingulum, and corpus callosum, and higher mean diffusivity (MD) in the optic radiations and cingulum than VPT infants. PHH was associated with higher MD in the optic radiations and left PLIC, and higher FA in the right caudate. For BI infants, higher MD in the right optic radiation and lower FA in the right cingulum, PLIC, and corpus callosum were related to motor impairments.

CONCLUSIONS

BI infants demonstrated altered white and gray matter microstructure in regions affected by injury in a manner dependent upon injury type. PHH infants demonstrated the greatest impairments. Aberrant white matter microstructure was related to motor impairment in BI infants.

Development of postural control in infancy in cerebral palsy and cystic periventricular leukomalacia

BACKGROUND

Development of postural problems in Cerebral Palsy (CP) is largely unknown. Postural muscle activity is organized into two levels: 1) direction-specificity; 2) fine-tuning of direction-specific activity.

AIM

To study development of postural control until 21 months corrected age in subgroups of infants at very high-risk (VHR) of CP: a) with and without CP at 21 months; b) with and without cystic periventricular leukomalacia (cPVL), the brain lesion with highest risk of CP.

METHODS AND PROCEDURES

Longitudinal electromyography recordings of postural muscles during reaching were made in 38 VHR-infants (severe brain lesion or clear neurological signs) between 4.7 and 22.6 months (18 CP, of which 8 with cPVL). Developmental trajectories were calculated using linear mixed effect models.

OUTCOMES AND RESULTS

VHR-infants with and without CP showed virtually similar postural development throughout infancy. The subgroup of VHR-infants with cPVL improved performance in direction-specificity with increasing age, while they performed throughout infancy worse in fine-tuning of postural adjustments than infants without cPVL.

CONCLUSIONS AND IMPLICATIONS

VHR-infants with and without CP have a similar postural development that differs from published trajectories of typically developing infants. Infants with cPVL present from early age onwards dysfunctions in fine-tuning of postural adjustments; they focus on direction-specificity.

Supramodal agnosia for oblique mirror orientation in patients with periventricular leukomalacia

Periventricular leukomalacia (PVL) is characterized by focal necrosis at the level of the periventricular white matter, often observed in preterm infants. PVL is frequently associated with motor impairment and with visual deficits affecting primary stages of visual processes as well as higher visual cognitive abilities. Here we describe six PVL subjects, with normal verbal IQ, showing orientation perception deficits in both the haptic and visual domains. Subjects were asked to compare the orientation of two stimuli presented simultaneously or sequentially, using both a two alternative forced choice (2AFC) orientation-discrimination and a matching procedure. Visual stimuli were oriented gratings or bars or collinear short lines embedded within a random pattern. Haptic stimuli comprised two rotatable wooden sticks. PVL patients performed at chance in discriminating the oblique orientation, both for visual and haptic stimuli. Moreover when asked to reproduce the oblique orientation, they often oriented the stimulus along the symmetric mirror orientation. The deficit generalized to stimuli varying in many low level features, was invariant for spatiotopic object orientation, and also occurred for sequential presentations. The deficit was specific to oblique orientations, and not for horizontal or vertical stimuli. These findings show that PVL can affect a specific network involved with the supramodal perception of mirror symmetry orientation.

Spastic diplegia in preterm-born children: Executive function impairment and neuroanatomical correlates

BACKGROUND

The neuropsychological literature on preterm-born children with spastic diplegia due to periventricular leukomalacia is convergent in reporting deficits in non-verbal intelligence and in visuo-spatial abilities. Nevertheless, other cognitive functions have found to be impaired, but data are scant and not correlated with neuroimaging findings.

AIMS

This study analyzes the neuropsychological strengths and weaknesses in preterm-born children with spastic diplegia (pSD) and their relationships with neuroanatomical findings, investigated by a novel scale for MRI classification.

METHODS AND PROCEDURES

Nineteen children with pSD, mild to moderate upper limb impairment and Verbal IQ>80, and 38 normal controls were evaluated with a comprehensive neuropsychological battery (NEPSY-II), assessing Attention/Executive Functioning, Language, Memory, Sensorimotor, Social Perception and Visuospatial Processing domains. The MRIs were quantitatively scored for lesion severity.

OUTCOMES AND RESULTS

The results showed that, beyond core visuo-spatial and sensory-motor deficits, impairments in attention and executive functions were present in more than half of the sample, particularly in children with damage to the anterior corpus callosum.

CONCLUSIONS AND IMPLICATIONS

The findings are discussed in terms of clinical and rehabilitative implications tailored for pSD subgroups diversified for neuropsychological and neuroanatomical characteristics.

Relationship between brain lesion characteristics and communication in preschool children with cerebral palsy

BACKGROUND

MRI shows promise as a prognostic tool for clinical findings such as gross motor function in children with cerebral palsy(CP), however the relationship with communication skills requires exploration.

AIMS

To examine the relationship between the type and severity of brain lesion on MRI and communication skills in children with CP.

METHODS AND PROCEDURES

131 children with CP (73 males(56%)), mean corrected age(SD) 28(5) months, Gross Motor Functional Classification System distribution: I=57(44%), II=14(11%), III=19(14%), IV=17(13%), V=24(18%). Children were assessed on the Communication and Symbolic Behavioral Scales Developmental Profile (CSBS-DP) Infant-Toddler Checklist. Structural MRI was analysed with reference to type and semi-quantitative assessment of the severity of brain lesion. Children were classified for motor type, distribution and GMFCS. The relationships between type/severity of brain lesion and communication ability were analysed using multivariable tobit regression.

OUTCOMES AND RESULTS

Children with periventricular white matter lesions had better speech than children with cortical/deep grey matter lesions (β=-2.6, 95%CI=-5.0, -0.2, p=0.04). Brain lesion severity on the semi-quantitative scale was related to overall communication skills (β=-0.9, 95%CI=-1.4, -0.5, p<0.001). Motor impairment better accounted for impairment in overall communication skills than brain lesion severity.

IMPLICATIONS

Structural MRI has potential prognostic value for communication impairment in children with CP. WHAT THIS PAPER ADDS?: This is the first paper to explore important aspects of communication in relation to the type and severity of brain lesion on MRI in a representative cohort of preschool-aged children with CP. We found a relationship between the type of brain lesion and communication skills, children who had cortical and deep grey matter lesions had overall communication skills>1 SD below children with periventricular white matter lesions. Children with more severe brain lesions on MRI had poorer overall communication skills. Children with CP born at term had poorer communication than those born prematurely and were more likely to have cortical and deep grey matter lesions. Gross motor function better accounted for overall communication skills than the type of brain lesion or brain lesion severity.

Extent of altered white matter in unilateral and bilateral periventricular white matter lesions in children with unilateral cerebral palsy

AIMS

To investigate the extent of white matter damage in children with unilateral cerebral palsy (UCP) caused by periventricular white matter lesions comparing between unilateral and bilateral lesions; and to investigate a relationship between white matter microstructure and hand function.

METHODS AND PROCEDURES

Diffusion MRI images from 46 children with UCP and 18 children with typical development (CTD) were included. Subjects were grouped by side of hemiparesis and unilateral or bilateral lesions. A voxel-wise white matter analysis was performed to identify regions where fractional anisotropy (FA) was significantly different between UCP groups and CTD; and where FA correlated with either dominant or impaired hand function (using Jebsen Taylor Hand Function Test).

OUTCOMES AND RESULTS

Children with unilateral lesions had reduced FA in the corticospinal tract of the affected hemisphere. Children with bilateral lesions had widespread reduced FA extending into all lobes. In children with left hemiparesis, impaired hand function correlated with FA in the contralateral corticospinal tract. Dominant hand function correlated with FA in the posterior thalamic radiations as well as multiple other regions in both left and right hemiparesis groups.

CONCLUSIONS AND IMPLICATIONS

Periventricular white matter lesions consist of focal and diffuse components. Focal lesions may cause direct motor fibre insult resulting in motor impairment. Diffuse white matter injury is heterogeneous, and may contribute to more global dysfunction.

Relationship between characteristics on magnetic resonance imaging and motor outcomes in children with cerebral palsy and white matter injury

In a population cohort of children with white matter injury (WMI) and cerebral palsy (CP), we aimed to describe the magnetic resonance imaging (MRI) characteristics, identify key structure-function relationships, and classify the severity of WMI in a clinically relevant way. Stratified on MRI laterality/symmetry, variables indicating the extent and location of cerebral abnormalities for 272 children with CP and WMI on chronic-phase MRI were related to gross motor function and motor topography using univariable and multivariable approaches. We found that symmetrical involvement, severe WM loss in the hemispheres and corpus callosum, and cerebellar involvement were the strongest predictors of poor gross motor function, but the final model explained only a small proportion of the variability. Bilateral, extensive WM loss was more likely to result in quadriplegia, whereas volume loss in the posterior-mid WM more frequently resulted in diplegia. The extent and location of MRI abnormalities differed according to laterality/symmetry; asymmetry was associated with less extensive hemispheric involvement than symmetrical WMI, and unilateral lesions were more focal and located more anteriorly. In summary, laterality/symmetry of WMI, possibly reflecting different pathogenic mechanisms, together with extent of WM loss and cerebellar abnormality predicted gross motor function in CP, but to a limited extent.

Discovering hidden relationships in physiological signals for prediction of Periventricular Leukomalacia

This paper is concerned with predicting the occurrence of Periventricular Leukomalacia (PVL) using vital data which are collected over a period of twelve hours after neonatal cardiac surgery. The vital data contain heart rate (HR), mean arterial pressure (MAP), right atrium pressure (RAP), and oxygen saturation (SpO2). Various features are extracted from the data and are then ranked so that an optimal subset of features that have the highest discriminative capabilities can be selected. A decision tree (DT) is then developed for the vital data in order to identify the most important vital measurements. The DT result shows that high amplitude 20 minutes variations and low sample entropy in the data is an important factor for prediction of PVL. Low sample entropy represents lack of variability in hemodynamic measurement, and constant blood pressure with small fluctuations is an important indicator of PVL occurrence. Finally, using the different time frames of the collected data, we show that the first six hours of data contain sufficient information for PVL occurrence prediction.

Vessel maturation schedule determines vulnerability to neuronal injuries of prematurity

Premature birth is a major risk factor for multiple brain pathologies, notably periventricular leukomalacia (PVL), which is distinguished by bilateral necrosis of neural tissue around the ventricles and a sequela of neurological disturbances. The 2 hallmarks of brain pathologies of prematurity are a restricted gestational window of vulnerability and confinement of injury to a specific cerebral region. Here, we examined the proposition that both of these features are determined by the state of blood vessel immaturity. We developed a murine genetic model that allows for inducible and reversible VEGF blockade during brain development. Using this system, we determined that cerebral vessels mature in a centrifugal, wave-like fashion that results in sequential acquisition of a functional blood-brain barrier and exit from a VEGF-dependent phase, with periventricular vessels being the last to mature. This developmental program permitted selective ablation of periventricular vessels via episodic VEGF blockade within a specific, vulnerable gestational window. Enforced collapse of ganglionic eminence vessels and resultant periventricular neural apoptosis resulted in a PVL-like phenotype that recapitulates the primary periventricular lesion, ventricular enlargement, and the secondary cortical deficit in out-migrating GABAergic inhibitory interneurons. These findings provide an animal model that reproduces the temporal and spatial specificities of PVL and indicate that damage to VEGF-dependent, immature periventricular vessels contributes to PVL development.

The effects of hemorrhagic parenchymal infarction on the establishment of sensori-motor structural and functional connectivity in early infancy

INTRODUCTION

The objective of the study was to characterize alterations of structural and functional connectivity within the developing sensori-motor system in infants with focal perinatal brain injury and at high risk of cerebral palsy.

METHODS

Functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) data were used to study the developing functional and structural connectivity framework in six infants born prematurely at term equivalent age. This was first characterised in three infants without focal pathology, which was then compared to that derived from three infants with unilateral haemorrhagic parenchymal infarction and a subsequent focal periventricular white matter lesion who developed later haemiparesis.

RESULTS

Functional responses to passive hand movement were in the contralateral perirolandic cortex, regardless of focal pathology. In infants with unilateral periventricular injury, afferent thalamo-cortical tracts appeared to have developed compensatory trajectories which circumvented areas of damage. In contrast, efferent corticospinal tracts showed marked asymmetry at term equivalent age following focal brain injury. Sensori-motor network analysis suggested that inter-hemispheric functional connectivity is largely preserved despite pathology and that impairment may be associated with adverse neurodevelopmental outcome.

CONCLUSION

Following focal perinatal brain injury, altered structural and functional connectivity is already present and can be characterized with MRI at term equivalent age. The results of this small case series suggest that these techniques may provide valuable new information about prognosis and the pathophysiology underlying cerebral palsy.

[Visuospatial functions and prematurity]

Visuospatial functions are very important in learning process and development of abstract thought during childhood. Several studies show that preterm and low birth weight infants obtain lower scores in test that assess cognitive functions, specially in the first year of life. These differences are attenuated over time, but a developmental delay that affects working memory and visuospatial process still persists. It is unclear what factors are involved in development of these functions, and pre- or perinatal factors may interfere with the proper conduct of the same, but have been described anatomical and physiological differences between the preterm and term brain that could explain somewhere in these alterations. The different selective vulnerability to hypoxia between immature brain in which preoligodendrocytes and subplate neurons predominate, and mature brain, determine differences in the pattern of injury from hypoxia with greater involvement of the periventricular white matter in preterm children. This lesional pattern leaves to a dysfunction in attentional and visuospatial process, due to the increased vulnerability of the regions involved in the dorsal pathway of visual processing.

Treatment with UDP-glucose, GDNF, and memantine promotes SVZ and white matter self-repair by endogenous glial progenitor cells in neonatal rats with ischemic PVL

Periventricular leukomalacia (PVL) is one of the foremost neurological conditions leading to long-term abnormalities in premature infants. Since it is difficult to prevent initiation of this damage in utero, promoting the innate regenerative potential of the brain after birth may provide a more feasible, prospective therapy for PVL. Treatment with UDP-glucose (UDPG), an endogenous agonist of G protein-coupled receptor 17 (GPR17) that may enhance endogenous self-repair potentiality, glial cell line-derived neurotrophic factor (GDNF), a neurotrophic factor associated with the growth and survival of nerve cells, and memantine, a noncompetitive antagonist of N-methyl-d-aspartate (NMDA) receptors that block ischemia-induced glutamate signal transduction, has been reported to achieve functional, neurological improvement in neonatal rats with PVL. The aim of the present study was to further explore whether UDPG, GDNF and/or memantine could promote corresponding self-repair of the subventricular zone (SVZ) and white matter (WM) in neonatal rats with ischemia-induced PVL. SVZ or WM tissue samples and cultured glial progenitor cells derived from a 5 day-old neonatal rat model of PVL were utilized for studying response to UDPG, GDNF and memantine in vivo and in vitro, respectively. Labeling with 5'-bromo-2'-deoxyuridine and immunofluorescent cell lineage markers after hypoxia-ischemia or oxygen-glucose deprivation (OGD) revealed that UDPG, GDNF and memantine each significantly increased glial progenitor cells and preoligodendrocytes (preOLs), as well as more differentiated immature and mature oligodendrocyte (OL), in both the SVZ and WM in vivo or in vitro. SVZ and WM glial cell apoptosis was also significantly reduced by UDPG, GDNF or memantine, both in vivo and in vitro. These results indicated that UDPG, GDNF or memantine may promote endogenous self-repair by stimulating proliferation of glial progenitor cells derived from both the SVZ and WM, activating their differentiation into more mature OLs, and raising the survival rate of these newly generated glial cells in neonatal rats with ischemic PVL.

Chorioamnionitis in the pathogenesis of brain injury in preterm infants

Chorioamnionitis (or placental infection) is suspected to be a risk factor for brain injury in premature infants. The suggested association between chorioamnionitis and cystic periventricular leukomalacia and cerebral palsy is uncertain because of the variability of study designs and definitions of chorioamnionitis. Improvements in neonatal intensive care may have attenuated the impact of chorioamnionitis on brain health outcomes. Large multicenter studies using rigorous definitions of chorioamnionitis on placental pathologies and quantitative magnetic resonance techniques may offer the optimal way to clarify the complex role of chorioamnionitis in modifying brain health and long-term outcomes.

Neurodevelopmental outcomes of children with periventricular leukomalacia

OBJECTIVES

To examine the neurodevelopmental outcomes of children with periventricular leukomalacia (PVL).

MATERIALS AND METHODS

Twenty-five children diagnosed with grade 1, 2 or 3 PVL on the basis of magnetic resonance imaging (MRI) findings between January 2002 and December 2011 were enrolled and followed from 15 months to 10 years of age.

RESULTS

Of the 25 children, one was a term and 24 were preterm-births. Nine (36%) had spastic diplegia and 12 (48%) had quadriplegia. Ten of the 25 (40%) were able to walk independently at 36 months utilizing short leg braces, whereas 13 children (52%) were unable to walk independently. MRI findings revealed grade 1 PVL in nine (36%), grade 2 in 12 (48%), and grade 3 in four (16%) of the 25 children. Eleven of the 16 children (69%) with grade 2 or 3 PVL had Papile III or IV intraventricular hemorrhage (IVH), and many of these children had severe neurologic motor abnormalities, severe psychomotor delay, and seizures. Five of the nine children (56%) with grade 1 PVL had normal psychomotor development. There were statistically significant differences in the motor impairment and walking ability between the children with grade 1 and those with grade 2 PVL (p = 0.008 and 0.005, respectively).

CONCLUSION

Most children with grade 2 or 3 PVL had severe neurodevelopmental delays, but attention should also be paid to the 56% of children with grade 1 PVL who presented with normal psychomotor development. Further studies of larger populations, including long-term follow-up, are necessary to evaluate the outcomes of children with PVL.

Children with cerebral palsy and periventricular white matter injury: does gestational age affect functional outcome?

This study aimed to determine differences in functional profiles and movement disorder patterns in children aged 4-12 years with cerebral palsy (CP) and periventricular white matter injury (PWMI) born >34 weeks gestation compared with those born earlier. Eligible children born between 1999 and 2006 were recruited through the Victorian CP register. Functional profiles were determined using the Gross Motor Function Classification System (GMFCS), Manual Abilities Classification System (MACS), Communication Function Classification System (CFCS), Functional Mobility Scale (FMS) and Bimanual Fine Motor Function (BFMF). Movement disorder and topography were classified using the Surveillance of Cerebral Palsy in Europe (SCPE) classification. 49 children born >34 weeks (65% males, mean age 8 y 9 mo [standard deviation (SD) 2 y 2 mo]) and 60 children born ≤ 34 weeks (62% males, mean age 8 y 2 mo [SD 2 y 2 mo]) were recruited. There was evidence of differences between the groups for the GMFCS (p=0.003), FMS 5, 50 and 500 (p=0.003, 0.002 and 0.012), MACS (p=0.04) and CFCS (p=0.035), with a greater number of children born ≤ 34 weeks more severely impaired compared with children born later. Children with CP and PWMI born >34 weeks gestation had milder limitations in gross motor function, mobility, manual ability and communication compared with those born earlier.

[Pathomorphology of periventricular leukomalacia and other white matter lesions in infants]

The paper describes white matter lesions that differ from periventricular leukomalacia (PVL), such as diffuse leukomalacia (DL) and telencephalic gliosis (TG). There are three types of cerebral leukomalacias: PVL, DL, and subcortical leukomalacia. The morphological differences between PVL and DL are considered. The diffuse form of PVL is described. It is pointed out that colliquation PVL foci frequently occur in infants with birth weight less than 1500 g. There are data on the morphology of TG in which generalized and occasionally large-focal astrogliosis develops in the cerebral hemispheric white matter. It is suggested that it is inexpedient to identify the focal and diffuse components of PVL. The immunihistochemical findings led to the conclusion that PVL, DL, and TG did not result from the direct effects of pathogens of inherited infections on brain tissue.

Visuospatial working memory in toddlers with a history of periventricular Leukomalacia: an EEG narrow-band power analysis

BACKGROUND

Periventricular Leukomalacia (PVL) affects white matter, but grey matter injuries have also been reported, particularly in the dorsomedial nucleus and the cortex. Both structures have been related to working memory (WM) processes. The aim of this study was to compare behavioral performances and EEG power spectra during a visuospatial working memory task (VSWMT) of toddlers with a history of PVL and healthy toddlers.

METHODOLOGY/PRINCIPAL FINDINGS

A prospective, comparative study of WM was conducted in toddlers with a history of PVL and healthy toddlers. The task responses and the EEG narrow-band power spectra during a VSWMT were compared in both groups. The EEG absolute power was analyzed during the following three conditions: baseline, attention and WM retention. The number of correct responses was higher in the healthy group (20.5 ± 5.0) compared to the PVL group (16.1 ± 3.9) (p = 0.04). The healthy group had absolute power EEG increases (p ≤ 0.05) during WM compared to the attention condition in the bilateral frontal and right temporal, parietal and occipital regions in frequencies ranging from 1.17 to 2.34 Hz and in the right temporal, parietal and occipital regions in frequencies ranging from 14.06 to 15.23 Hz. In contrast, the PVL group had absolute power increases (p ≤ 0.05) in the bilateral fronto-parietal, left central and occipital regions in frequencies that ranged from 1.17 to 3.52 Hz and in the bilateral frontal and right temporal regions in frequencies ranging from 9.37 to 19.14 Hz.

CONCLUSIONS/SIGNIFICANCE

This study provides evidence that PVL toddlers have visuospatial WM deficits and a very different pattern of absolute power increases compared to a healthy group of toddlers, with greater absolute power in the low frequency range and widespread neuronal networks in the WM retention phase.

[Relationship between degree of white matter damage and EEG changes in premature infants early after birth]

OBJECTIVE

To study the relationship between the degree of white matter damage and changes in brain function in premature infants early after birth according to amplitude-integrated electroencephalogram (aEEG) and raw EEG (with burst-suppression patterns).

METHODS

Thirty-eight premature infants of less than 32 weeks' gestational age and with white matter damage, including 20 cases of mild white matter damage and 18 cases of severe white matter damage, were included in the study. Forty-two premature infants without white matter damage were selected as a control group. After birth, they were examined using aEEG and brain ultrasound once a week until four weeks after birth or a corrected gestational age of 32 weeks. The white matter damage and control groups were compared in terms of aEEG patterns and amplitudes and burst suppression ratio (BSR) on EEG.

RESULTS

The white matter damage and control groups had highly discontinuous patterns and had no complete sleep cycles. The lower amplitude was significantly smaller in the severe white matter damage subgroup than in the mild white matter damage subgroup and control group. There was alternating burst-suppression activity on the raw EEG in the white matter damage and control groups; and the severe white matter damage subgroup had a significantly longer suppression time and a significantly higher BSR on EEG compared with the mild white matter damage subgroup and control group.

CONCLUSIONS

Brain function monitoring should be performed in premature infants with white matter damage early after birth so as to detect cases of severe white matter damage in time.

[Features of epileptiform activity on EEG in children with periventricular leukomalacya and cerebral palsy without epilepsy]

We have analyzed morphologic and chronologic characteristics of epileptiform activity, with account for repeated EEG-study during the follow-up, in patients with periventricular leukomalacia and children cerebral palsy without epilepsy. The high frequency of "benign epileptiform patterns of childhood" (BEPC) was noted. The epileptiform activity recorded by chronologic criteria corresponded to BEPC in 67% of children. The high probability of epileptiform activity of symptomatic character was identified in 33% of children. The results obtained in this study of the parameters of epileptiform activity could be of great importance for predicting the risk for the development of epilepsy and tactics of rehabilitation of motor disorders.

Electrophysiological auditory responses and language development in infants with periventricular leukomalacia

This study presents evidence suggesting that electrophysiological responses to language-related auditory stimuli recorded at 46weeks postconceptional age (PCA) are associated with language development, particularly in infants with periventricular leukomalacia (PVL). In order to investigate this hypothesis, electrophysiological responses to a set of auditory stimuli consisting of series of syllables and tones were recorded from a population of infants with PVL at 46weeks PCA. A communicative development inventory (i.e., parent report) was applied to this population during a follow-up study performed at 14months of age. The results of this later test were analyzed with a statistical clustering procedure, which resulted in two well-defined groups identified as the high-score (HS) and low-score (LS) groups. The event-induced power of the EEG data recorded at 46weeks PCA was analyzed using a dimensionality reduction approach, resulting in a new set of descriptive variables. The LS and HS groups formed well-separated clusters in the space spanned by these descriptive variables, which can therefore be used to predict whether a new subject will belong to either of these groups. A predictive classification rate of 80% was obtained by using a linear classifier that was trained with a leave-one-out cross-validation technique.

Neural plasticity after pre-linguistic injury to the arcuate and superior longitudinal fasciculi

We describe the case of girl who was born prematurely and diagnosed periventricular leukomalacia, a condition characterized by severe injury to the white matter tracts primarily surrounding the ventricles. At 12 years of age, we obtained diffusion tensor imaging (DTI) data on this child as part of a research protocol. Multiple analyses of DTI data, including tractography, showed that the left and right arcuate and superior longitudinal fasciculi were missing in the child though all other major white matter tracts were present. Standardized psychometric tests at age 12 years revealed that despite early language delays, she had average scores on expressive language, sentence repetition, and reading, functions that have been hypothesized to depend on signals carried by the arcuate fasciculus. We identified intact ventral connections between the temporal and frontal lobes through the extreme capsule fiber system and uncinate fasciculus. Preserved language and reading function after serious injury to the arcuate fasciculus highlights the plasticity of the developing brain after severe white matter injury early in life.

Potential neuronal repair in cerebral white matter injury in the human neonate

Periventricular leukomalacia (PVL) in the premature infant represents the major substrate underlying cognitive deficits and cerebral palsy and is characterized as focal periventricular necrosis and diffuse gliosis in the immature cerebral white matter. We have recently shown a significant decrease in the density of neurons in PVL relative to controls throughout the white matter, including the subventricular, periventricular, and subcortical regions. These neurons are likely to be remnants of the subplate and/or GABAergic neurons in late migration to the cerebral cortex, both of which are important for proper cortical circuitry in development and throughout adulthood. Here, we tested the hypothesis that intrinsic repair occurs in PVL to attempt to compensate for the deficits in white matter neurons. By using doublecortin (DCX) immunopositivity as a marker of postmitotic migrating neurons, we found significantly increased densities (p < 0.05) of DCX-immunopositive cells in PVL cases (n = 9) compared with controls (n = 7) in the subventricular zone (their presumed site of origin), necrotic foci, and subcortical white matter in the perinatal time-window, i.e. 35-42 postconceptional weeks. These data provide the first evidence suggestive of an attempt at neuronal repair or regeneration in human neonatal white matter injury.

Cognitive abilities and language comprehension in preschool children with perinatal brain lesion

Perinatal brain lesion is a risk factor for development, making parents of such children particularly worried about consequences it may have on the child's cognitive and language development. Although literature findings on the outcome of perinatal brain lesion are inconsistent, most of the studies have found a positive general outcome, but also subtle deficits that affect the child's academic success. Since language comprehension and cognitive abilities influence learning abilities at school, we wanted to know how six-year olds who were selected based on pathological ultrasonographical findings (ischemic or hemorrhagic brain lesion) would perform on subtests of Wechsler battery (WISC) and language comprehension measures (Reynell Developmental Language Scale and Peabody Picture Vocabulary Test), compared with controls. The second issue we investigated was whether in children who suffered a perinatal brain lesion cognitive abilities predicted the level of language comprehension in the same way as in children without perinatal brain lesion. The relation between cognitive and linguistic abilities is still a controversial one, and a different relation would mean that these two groups of children have different structure of abilities probably due to perinatal brain lesion. Forty children who suffered a perinatal brain lesion and forty age-matched children without perinatal risk factors were examined. Our results showed that the groups differed more in linguistic than in cognitive variables. Also, the two groups showed different relation patterns between cognitive abilities and language comprehension. Cognitive abilities were statistically significantly associated with language comprehension in children who suffered a perinatal brain lesion, while this association was not statistically significant within the control group. Since a number of participants with perinatal brain lesion had language difficulties, it is presumed that they rely on cognitive abilities in order to overcome and compensate for language shortcomings.

Twelve-month neurodevelopmental outcome in preterm infants with and without intrauterine growth restriction

AIM

To evaluate the neurodevelopmental outcome at 12 months' corrected age in preterm infants with and without severe intrauterine growth restriction.

METHODS

This prospective follow-up study included 37 infants with severe intrauterine growth restriction and 36 appropriate-for-gestational-age infants born between 26 and 34 weeks. Neonatal and infant data were prospectively recorded. Infants were assessed at 12 ± 2 months' corrected age with the Hammersmith Infant Neurological Examination and the Bayley Scale for Infant Development version-II.

RESULTS

Both groups were similar in demographic characteristics and perinatal status. No significant differences in neurodevelopmental performance were found. The mental development index was 98.8 (SD 9.0) vs 98.4 (SD 13.1) (p = 0.9) and the psychomotor development index was 91.7 (SD 9.9) vs 95.5 (SD 13.4) (p = 0.2) for the study and reference groups respectively. Neurological assessment showed no significant differences between the two groups.

CONCLUSION

Although the study group showed a non-significant trend towards a lower score in the psychomotor development index than the reference group, significant differences at 12 months could not be demonstrated. IUGR infants continued to have significantly lower weight, length and head circumference at 1 year.

Cerebral white matter blood flow and arterial blood pressure in preterm infants

It is generally assumed that one reason why white matter injury is common in preterm infants is the relatively poor vascular supply.

IGF-1 can either protect against or increase LPS-induced damage in the developing rat brain

Periventricular leukomalacia (PVL) is a major form of brain damage in premature infants. This study was to test whether IGF-1 can prevent PVL-like brain damage induced by lipopolysaccharide (LPS) in the neonatal rat. Intraventricular delivery of LPS resulted in an acute brain inflammatory response, i.e., rapid recruitment of polymorphonuclear leukocytes (PMNs), activation of microglia and astrocytes, and induction of IL-1beta (IL1beta) expression. Brain inflammation was associated with the loss of O4+ preoligodendrocytes (preOLs), a decrease of myelin basic protein (MBP) in the white matter and an increase of pyknotic cells in the cortex. IGF-1 at a low dose significantly prevented LPS-induced deleterious effects without alteration of IL-1beta expression and microglia/astrocytes activation. On the other hand, the low dose of IGF-1 enhanced LPS-induced PMNs recruitment and blood-brain barrier (BBB) permeability, and caused intracerebral hemorrhage. At higher doses, co-application of IGF-1 with LPS resulted in a high mortality rate. Brains from the surviving rats showed massive PMN infiltration and intracerebral hemorrhage. However, these adverse effects were not found in rats treated with IGF-1 alone. This study provides the alarming evidence that in an acute inflammatory condition, IGF-1 may have severe, harmful effects on the developing brain.

Insults to the developing brain and impact on neurodevelopmental outcome

Premature infants have a disproportionately increased risk for brain injury based on several mechanisms including intraventricular hemorrhage, ischemia and the vulnerability of developing neuronal progenitor cells. Injury to the developing brain often results in neurologic abnormalities that can be correlated with a structural lesion; however more subtle injury may result in disruption of critical neural pathways. There also appears to be an important relationship between brain injury in the cortex and the growth and developing cerebellum. Although the survival rate for premature has improved over the past decade, researchers remain concerned about the risk for adverse neurocognitive functioning in these early childhood, including an increased risk for cerebral palsy, cognitive impairment, speech and language delay and sensory dysfunction.

LEARNING OUTCOMES

After this activity, the learner will be able to (1) identify potential causes of brain injury in the premature infant, (2) understand that the maturational process for the human brain continues throughout gestation, (3) identify risk factors for adverse neurocognitive functioning in premature infants, and (4) identify abnormalities on central nervous system neuroimaging studies that correlate with an increased risk for adverse neurodevelopmental outcome in premature infants.

[Multicenter follow-up report of 147 premature infants with brain injuries from 6 hospitals in China]

OBJECTIVE

Sponsored by the Subspecialty Group of Neonatology of Pediatric Society, China Medical Association, more than 10 large-scale hospitals participated in the near two-year multicenter investigation for Brain Injuries in Premature Infants in China. The present study presents the follow-up results of 147 premature infants with brain injuries from 6 Third Class A Level hospitals.

METHODS

All premature infants with intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL) diagnosed in the early neonatal period in the 6 hospitals were followed-up between January 2005 and August 2006. Based on the synthetic results of physical development, examination of nervous system, intelligence tests and cranial ultrasound, the premature infants with brain injuries were classified as normal development, marginal development and retarded development.

RESULTS

One hundred and forty-seven premature infants with brain injuries from the 6 hospitals consisted of 141 cases of IVH and 36 cases of PVL (30 cases having IVH and PVL). Based on the synthetic follow-up results, 51.4% of premature infants with brain injuries were generally assessed as normal development, 38.4% as marginal development and 10.7% as retarded development. Among them, delayed growth in head circumference, height and weight was 13.4%; the occurrence frequency of cerebral paralysis (CP) was 7.1% in PVL grade I, 28.6% in PVL grade II and 100% in PVL grade III; 12.7% showed retarded development of intelligence; and 30% presented post-injurious changes on cranial sonography.

CONCLUSIONS

The data of the multicenter follow-up can basically reflect the short-term prognosis of premature infants with brain injuries in major big cities of China. About 10% of them have retarded physical, motor-and mental developments. The long-term regular follow-up study is expected for more premature infants with brain injuries, and behavioral sequelae of brain injuries which may occur in peri-school age and adolescence should be paid particularly close attention.

Prediction of periventricular leukomalacia. Part I: Selection of hemodynamic features using logistic regression and decision tree algorithms

OBJECTIVE

Periventricular leukomalacia (PVL) is part of a spectrum of cerebral white matter injury which is associated with adverse neurodevelopmental outcome in preterm infants. While PVL is common in neonates with cardiac disease, both before and after surgery, it is less common in older infants with cardiac disease. Pre-, intra-, and postoperative risk factors for the occurrence of PVL are poorly understood. The main objective of the present work is to identify potential hemodynamic risk factors for PVL occurrence in neonates with complex heart disease using logistic regression analysis and decision tree algorithms.

METHODS

The postoperative hemodynamic and arterial blood gas data (monitoring variables) collected in the cardiac intensive care unit of Children's Hospital of Philadelphia were used for predicting the occurrence of PVL. Three categories of datasets for 103 infants and neonates were used-(1) original data without any preprocessing, (2) partial data keeping the admission, the maximum and the minimum values of the monitoring variables, and (3) extracted dataset of statistical features. The datasets were used as inputs for forward stepwise logistic regression to select the most significant variables as predictors. The selected features were then used as inputs to the decision tree induction algorithm for generating easily interpretable rules for prediction of PVL.

RESULTS

Three sets of data were analyzed in SPSS for identifying statistically significant predictors (p<0.05) of PVL through stepwise logistic regression and their correlations. The classification success of the Case 3 dataset of extracted statistical features was best with sensitivity (SN), specificity (SP) and accuracy (AC) of 87, 88 and 87%, respectively. The identified features, when used with decision tree algorithms, gave SN, SP and AC of 90, 97 and 94% in training and 73, 58 and 65% in test. The identified variables in Case 3 dataset mainly included blood pressure, both systolic and diastolic, partial pressures pO(2) and pCO(2), and their statistical features like average, variance, skewness (a measure of asymmetry) and kurtosis (a measure of abrupt changes). Rules for prediction of PVL were generated automatically through the decision tree algorithms.

CONCLUSIONS

The proposed approach combines the advantages of statistical approach (regression analysis) and data mining techniques (decision tree) for generation of easily interpretable rules for PVL prediction. The present work extends an earlier research [Galli KK, Zimmerman RA, Jarvik GP, Wernovsky G, Kuijpers M, Clancy RR, et al. Periventricular leukomalacia is common after cardiac surgery. J Thorac Cardiovasc Surg 2004;127:692-704] in the form of expanding the feature set, identifying additional prognostic factors (namely pCO(2)) emphasizing the temporal variations in addition to upper or lower values, and generating decision rules. The Case 3 dataset was further investigated in Part II for feature selection through computational intelligence.

Periventricular leukomalacia in premature infants in mainland China

Periventricular leukomalacia (PVL) in premature infants is a major cause of mortality and disability. However, while China is the largest developing country, there is an absence of data concerning PVL. This study was carried out in order to explore the incidence rate and analyze the high-risk factors of PVL in premature infants, and to suggest a working protocol for the prevention of PVL in newborns at risk. The cohort prospective study included 921 premature infants < 37 weeks' gestation from January 2004 to July 2007. The study group was comprised of 271 premature infants with an ultrasound diagnosis of PVL and the control group was comprised of 650 premature infants who were submitted to the same evaluation protocol but did not show any echographic signs of PVL. The results showed that the incidence rate of PVL was 29.4% in China. High-degree PVL accounted for < 12% and > 88% of PVL was low-degree. The incidence rate was much higher when premature infants were accompanied by the following complications: low gestational age, low birth weight, prolonged rupture of membranes, chorionitis, mechanical ventilation, periventricular-ventricular hemorrhage, hypocapnia, and hyperlactacidemia. Severe complications that occur in premature infants also significantly increase the incidence of PVL. Antenatal corticosteroids can significantly decrease the incidence rate of PVL. This investigation provided a theoretical reference for the prevention of premature PVL.

Infection and fetal neurologic injury

PURPOSE OF REVIEW

Antepartum fetal exposure to infection/inflammation is a more important risk factor for brain injury than intrapartum hypoxia in both the term and preterm neonate. Such preexisting infection/inflammation might also provide the platform for subsequent intrapartum hypoxic-ischaemic damage. This review will discuss the complex interaction between fetal inflammatory response and neurotoxicity, and focus on the clinical implications of the synergistic interaction between infection/inflammation and hypoxia-ischaemia.

RECENT FINDINGS

Current evidence indicates that inflammatory mediators are directly neurotoxic, and also sensitize the fetal brain tissue to a greater magnitude of damage by subsequent hypoxia-ischaemia by lowering the threshold at which hypoxia initiates neuronal cell apoptosis/cell death.

SUMMARY

Further studies are urgently needed to characterize the fetuses at risk of damage, the duration of exposure required to cause injury, the influence of gestational age and whether Caesarean section may be protective. Until then clinicians should maintain a high level of surveillance in labours complicated by infection and avoid additional exposure to hypoxic-ischaemic insults.

[Periventricular leukomalacia in premature infants: from pathogenesis to treatment]

Prematurity is a major cause of cerebral palsy (CP). CP in preterm infants usually results from damage to the periventricular white matter, known as periventricular leukomalacia (PVL). The pathogenesis of PVL is controversial, with leading models suggesting either ischemic etiology or infection and inflammation as the root cause for the disease. Advances in understanding the biology of PVL may result in clinical interventions that reduce the burden of CP.

Gray matter injury associated with periventricular leukomalacia in the premature infant

Neuroimaging studies indicate reduced volumes of certain gray matter regions in survivors of prematurity with periventricular leukomalacia (PVL). We hypothesized that subacute and/or chronic gray matter lesions are increased in incidence and severity in PVL cases compared to non-PVL cases at autopsy. Forty-one cases of premature infants were divided based on cerebral white matter histology: PVL (n = 17) with cerebral white matter gliosis and focal periventricular necrosis; diffuse white matter gliosis (DWMG) (n = 17) without necrosis; and “

Negative” group (n = 7) with no abnormalities. Neuronal loss was found almost exclusively in PVL, with significantly increased incidence and severity in the thalamus (38%), globus pallidus (33%), and cerebellar dentate nucleus (29%) compared to DWMG cases. The incidence of gliosis was significantly increased in PVL compared to DWMG cases in the deep gray nuclei (thalamus/basal ganglia; 50–60% of PVL cases), and basis pontis (100% of PVL cases). Thalamic and basal ganglionic lesions occur almost exclusively in infants with PVL. Gray matter lesions occur in a third or more of PVL cases suggesting that white matter injury generally does not occur in isolation, and that the term “perinatal panencephalopathy” may better describe the scope of the neuropathology.

Serial diffusion tensor imaging detects white matter changes that correlate with motor outcome in premature infants

The objective of the study was to assess predictive value of serial diffusion tensor MRI (DTI) for the white matter injury and neurodevelopmental outcome in a cohort of premature infants. Twenty-four infants less than 32 weeks' gestation were stratified to a control group (n = 11), mild brain injury with grades 1-2 of intraventricular hemorrhage (n = 6) and severe brain injury with grades 3-4 intraventricular hemorrhage (n = 4). Serial DTI studies were performed at around 30 and 36 weeks' gestation. Fractional anisotropy (FA) and apparent diffusion coefficient were calculated. Twelve infants were followed up for developmental outcome. Developmental testing was performed with the Bayley Scales of Infant Development to obtain psychomotor index (Performance Developmental Index). Apparent diffusion coefficient was higher in the severe injury group at the second MRI in the central and occipital white matter, and corona radiata; FA was lower in optic radiation compared to controls. Performance Developmental Index score correlated with FA on the scan taken at the 30th week and inversely with the change of FA between scans in internal capsule and occipital white matter. A low value of FA at 30 weeks and a higher change of FA predicted less favorable motor outcome at 2 years and suggests that early subtle white matter injury can be detected in premature infants even without obvious signs of injury.

Perinatal brain damage causation

The search for causes of perinatal brain damage needs a solid theoretical foundation. Current theory apparently does not offer a unanimously accepted view of what constitutes a cause, and how it can be identified. We discuss nine potential theoretical misconceptions: (1) too narrow a view of what is a cause (causal production vs. facilitation), (2) extrapolating from possibility to fact (potential vs. factual causation), (3) if X, then invariably Y (determinism vs. probabilism), (4) co-occurrence in individuals vs. association in populations, (5) one cause is all that is needed (single cause attribution vs. multicausal constellations), (6) drawing causal inferences from very small numbers of observations (the tendency to generalize), (7) unstated causal inferences, (8) ignoring heterogeneity, and (9) failing to consider alternative explanations for what is observed. We hope that our critical discussion will contribute to fruitful research and help reduce the burden of perinatal brain damage.

Activated protein C reduces endotoxin-induced white matter injury in the developing rat brain

Periventricular leukomalacia (PVL), the dominant form of brain injury in premature infants, is characterized by white matter injury (WMI) and is associated with cerebral palsy. The pathogenesis of PVL is complex and likely involves ischemia/reperfusion, free radical formation, excitotoxicity, impaired regulation of cerebral blood flow, a procoagulant state, and inflammatory mechanisms associated with maternal and/or fetal infection. Using an established animal model of human PVL, we investigated whether activated protein C (APC), an anti-coagulant factor with anti-inflammatory, anti-apoptotic, anti-oxidant, and cytoprotective activities, could reduce endotoxin-induced WMI in the developing rat brain. Intraperitoneal injections of lipopolysaccharide (LPS) (0.5 mg/kg body weight) were given at embryonic days 18 (E18) and 19 (E19) to pregnant Sprague-Dawley rats; control rats were injected with sterile saline. A single intravenous injection of recombinant human (rh) APC (0.2 mg /kg body weight) was given to pregnant rats following the second LPS dose on embryonic day 19 (E19). Reduced cell death in white matter and hypomyelination were shown on TUNEL and myelin basic protein (MBP) staining, respectively, on late postnatal days (P7) in APC-treated groups. There were significantly fewer TUNEL+nuclei in the periventricular WM in the APC+LPS group than in the untreated LPS group. Compared to the APC+LPS and control group, MBP expression was weak in the LPS group on P7, indicating endotoxin-induced hypomyelination in the developing rat brain. APC attenuated the LPS-induced protein expression of inflammatory cytokines, tumor necrosis factor-alpha, and interleukin-6, as evaluated by ELISA in neonatal rat brains. A single intraperitoneal injection of rhAPC (0.2 mg/kg body weight) to neonatal rats on P1 also had similar protective and anti-inflammatory effects against maternally administered LPS. Collectively, these data support the hypothesis that APC may provide protection against an endotoxin-evoked inflammatory response and WMI in the developing rat brain. Moreover, our results suggest that the possible use of APC in treatment of preterm infants and pregnant women with maternal or placental infection may minimize the risk of PVL and cerebral palsy.

Epilepsy development in infancy with epileptic discharges

As a part of the study to prevent West syndrome (WS) by early treatment, we assessed what kind of epilepsy developed in infants who showed epileptic discharges in early infancy. EEG examinations were performed on 116 infants born from 1997 to September 2004, both before and after 3 months of corrected age (CA). We divided 45 infants who showed epileptic discharges in early infancy into two groups according to the existence of periventricular leukomalacia (PVL) and retrospectively performed the course observation at the survey point on April 1 in 2005. Out of 45 infants showing epileptic discharges in early infancy, 26 developed WS. Compared with infants without PVL, infants with PVL were more likely to develop WS than infants without PVL. Furthermore, infants with PVL were more likely to develop WS than other types of epilepsy. Namely, 11 out of 17 infants with PVL developed WS at the survey point. All infants with WS showed initial epileptic discharges before 5 months of corrected age (CA), and most of them (except for five) had initial epileptic discharges before 3 months of CA. There were two infants who once developed hypsarrhythmia on EEG; however, after starting VPA therapy, they did not develop WS with the improvement of EEG findings, and one was presented here in detail. We proposed that preterm infants with PVL who showed epileptic discharges before 3 months of CA should be treated by antiepileptic drugs to prevent the onset of WS syndrome.

Oscillatory MEG response to human locomotion is modulated by periventricular lesions

Veridical processing of biological movement is of immense value for adaptive behavior and social communication. Here we ask whether and, if so, how oscillatory cortical magnetoencephalographic (MEG) response to biological motion is modulated by early damage to periventricular regions that might affect the pathways interconnecting subcortical structures with cortex and cortico-cortical connectivity. The visual sensitivity to biological motion was lower in adolescents with periventricular leukomalacia (PVL). In controls, the evoked oscillatory MEG response (26.5 Hz) to biological motion peaked at a latency of 170 ms over the right temporo-parietal cortex. This increase was absent in PVL patients. By contrast, peaks in the oscillatory response to biological motion of lower frequency (23.5 Hz) were found in PVL patients later, at a latency of 290 ms over the left temporal region. The findings provide the first evidence for modulation of oscillatory cortical activity by periventricular lesions. The data suggest that PVL affects the brain connectivity with the right temporo-parietal cortex leading to disintegration of the neural network engaged in biological motion processing.

Fetal heart rate accelerations and the risk of cerebral lesions and poor neurodevelopmental outcome in very low birthweight neonates

The risk of intraventricular hemorrhage and periventricular leukomalacia correlates with fetal brain immaturity. Given that the appearance of fetal heart rate (FHR) accelerations is associated with brain maturation, we tested the hypothesis that neonatal cerebral lesions and developmental delay in very low birthweight newborns are associated with absent reactivity of the FHR tracing prior to delivery. We analyzed the FHR tracing of 97 fetuses with birthweight < 1200 g who underwent head ultrasound at day 3 and Bayley Scales of Infant Development testing at age 1 year. We used multivariate analysis to adjust for confounding variables. We found that the absence of two FHR accelerations of 10 beats per minute (bpm) for 10 seconds twice in a 20-minute window 1 hour before delivery was associated with intraventricular hemorrhage and/or periventricular leukomalacia ( P < 0.01) and a significant risk for mental and psychomotor delays by Bayley testing ( P < 0.001). The absence of accelerations of 15 bpm for 15 seconds was not associated with these abnormalities. The absence of FHR accelerations before delivery suggests a greater risk for cerebral injury and developmental delay in the very premature neonate.

Analysis of the correlation between three methods used in the assessment of children with cerebral palsy

The primary aim of this study was to assess the correlations between gait analysis, magnetic resonance imaging (MRI), and Gross Motor Function Measure (GMFM) scores in children with cerebral palsy (CP). These common diagnostic tools were used to evaluate 21 children affected by CP (mean age: 6 years, range: 5-13 years; 8 females and 13 males; 5 left hemiplegics, 4 right hemiplegics, 12 diplegics). In particular, in order to compare gait analysis data with other diagnostic evaluations, the Normalcy Index (NI) was used. The results showed a good correlation between the NI and the results of MRI, and between NI and the GMFM score (r=-0.76). Therefore, this investigation demonstrated that there exists a strong relationship between gait analysis and other clinical evaluation tools.

Neurodevelopmental outcome of the late preterm infant

There is very limited information about the developmental outcome of the late preterm infant. The developing brain is vulnerable to injury during this very active and important stage of fetal brain development; therefore, it is important to carefully monitor the neurologic outcome of these infants. This article discusses gestational brain development and complications of late preterm birth that contribute to the overall risk of brain injury.

Protective effects of caffeine on chronic hypoxia-induced perinatal white matter injury

OBJECTIVE

Periventricular white matter injury (PWMI) is the major cause of cerebral palsy and cognitive impairment in prematurely born infants. PWMI is characterized by reductions in cerebral myelination and cerebrocortical volumes and is associated with secondary ventriculomegaly. In neonatal rodents, these features of PWMI can be induced by rearing in chronic hypoxia or by activation of A1 adenosine receptors. We determined: (1) whether altered maturation or development of one or more oligodendrocyte (OL) lineage stages plays a role in the pathogenesis of the myelination disturbances associated with exposure to chronic hypoxia, and (2) whether blockade of A1 adenosine receptor action with the adenosine antagonist caffeine can prevent hypoxia-induced white matter injury.

METHODS

Ventriculomegaly and reduced cerebral myelination were generated in mice reared in hypoxia (10% oxygen) from postnatal days 3 (P3) through 12.

RESULTS

Hypomyelination was related to abnormal OL lineage progression and a reduction in the OL progenitor pool. Myelination was enhanced and ventriculomegaly reduced in hypoxia-exposed neonatal pups treated with caffeine from P3 to P12.

INTERPRETATION

These observations support that hypoxia inhibits OL maturation and that caffeine administration during early postnatal development may have utility in the prevention of PWMI.

Erythropoietin is neuroprotective against NMDA-receptor-mediated excitotoxic brain injury in newborn mice

Using an established mouse model of human periventricular leukomalacia, we investigated whether EPO could reduce excitotoxic damage. When administered 1 h following intracerebral injection of 10 microg ibotenic acid at day 5 of life, both a single injection of EPO (5000 IU/kg bw) and repetitive administrations of EPO reduced white and gray matter lesion size. The therapeutic window for protection was small as the protective effect of EPO was lost when EPO administration was delayed to 4 h post-insult. EPO-mediated upregulation of EPO-R, but not EPO, mRNA was observed within 4 h of the excitotoxic insult. The EPO effect was gender independent. Minor hematopoetic effects were observed following EPO treatment. We conclude that a single dose of EPO is sufficient to reduce excitotoxic brain injury and may therefore possess therapeutic relevance in the clinical setting.

Abnormal brushes in preterm infants with periventricular leukomalacia

OBJECTIVE

The aim of this study is to describe a new objective method of detecting white matter injury by use of refiltering function of digital EEG.

STUDY DESIGN

The neonatal EEGs of 9 patients with PVL were analyzed retrospectively, and compared with EEGs of 18 normal infants without PVL. Abnormal brushes were counted on the refiltered EEG where low cut filter were set at 10 Hz so that slow waves were eliminated. Abnormal brushes were defined as spindle-like fast wave bursts with maximal amplitudes higher than 40 mV and frequencies between 13 Hz and 20 Hz, which were easily distinguishable from a flat background.

RESULTS

The incidence of abnormal brushes in infants with PVL was 0.25/min, 0.45/min, 2.08/min, and 0.62/min on the frontal, central, occipital, and temporal region, respectively. The incidence in infants without PVL was 0.14/min, 0.08/min, 0.24/min, and 0.19/min, respectively. Abnormal brushes were observed more often in infants with PVL on the central, occipital, and temporal region than in infants without PVL. Localization of abnormal brushes was also correlated with the lesion of white matter injury on MR images and clinical outcome.

CONCLUSION

Our results indicated that abnormal brushes on refiltered EEGs were strongly associated with white matter injury.

Neurological examination at 6 to 9 months in infants with cystic periventricular leukomalacia

The Hammersmith Infant Neurological Examination was performed in 24 infants with cystic periventricular leukomalacia whose gestational age ranged between 26-38 weeks. The infants were examined between 6 and 9.5 months corrected age. The aim of the study was to establish the different patterns of neurological abnormality as well as the optimality scores that predict the severity of motor sequelae at 2 years. Increased neck and trunk extensor tone, and a posture of flexed arms and extended legs between 6 and 9 months were always associated with the inability to sit unsupported at 2 years, whilst truncal hypotonia and extended arms and legs were associated with unsupported sitting but not walking. Optimality scores between 41 and 60 were generally associated with sitting but not walking at 2 years whilst scores below 40 were always associated with the inability to sit independently at 2 years. All infants who did not develop cerebral palsy at 2 years had scores > 60. Our results suggest that the pattern of findings on neurological examination performed between 6 and 9 months as well as the calculated optimality score helps to predict motor impairment in infants with PVL.

Minocycline attenuates hypoxia-ischemia-induced neurological dysfunction and brain injury in the juvenile rat

To investigate whether minocycline provides long-lasting protection against neonatal hypoxia-ischemia-induced brain injury and neurobehavioral deficits, minocycline was administered intraperitoneally in postnatal day 4 Sprague-Dawley rats subjected to bilateral carotid artery occlusion followed by exposure to hypoxia (8% oxygen for 15 min). Brain injury and myelination were examined on postnatal day 21 (P21) and tests for neurobehavioral toxicity were performed from P3 to P21. Hypoxic-ischemic insults resulted in severe white matter injury, enlarged ventricles, deficits in the hippocampus, reduction in numbers of mature oligodendrocytes and tyrosine hydroxylase-positive neurons, damage to axons and dendrites, and impaired myelination, as indicated by the decrease in myelin basic protein immunostaining in the P21 rat brain. Hypoxic-ischemic insult also significantly affected physical development (body weight gain and eye opening) and neurobehavioral performance, including sensorimotor and locomotor function, anxiety and cognitive ability in the P21 rat. Treatments with minocycline significantly attenuated the hypoxia-ischemia-induced brain injury and improved neurobehavioral performance. The protection of minocycline was associated with its ability to reduce microglial activation. The present results show that minocycline has long-lasting protective effects in the neonatal rat brain in terms of both hypoxia-ischemia-induced brain injury and the associated neurological dysfunction.

Role of instrumented fetal sheep preparations in defining the pathogenesis of human periventricular white-matter injury

Periventricular white-matter injury is the major form of brain injury associated with prematurity and the leading cause of cerebral palsy in survivors of premature birth. Progress in understanding the pathogenesis of periventricular white-matter injury requires the development of animal models that are relevant to the unique physiology of the preterm human brain and that replicate the major neuropathologic features of human injury. The sheep is the most extensively studied true fetal preparation. The neurodevelopment of the preterm sheep fetus (0.65 gestation) is comparable to that of the preterm human between approximately 24 and 28 weeks. The size of the fetal sheep permits chronic instrumentation so that well-defined insults can be studied with reliable measurements of blood flow and metabolism in cerebral white-matter. We review here recent developments in the understanding of the role of cerebral hypoxia-ischemia and vulnerable oligodendrocyte progenitors in the pathogenesis of periventricular white-matter injury in the immature sheep fetus. We focus on recent developments in high-resolution spatially defined cerebral blood flow measurements in utero. We determined ovine white-matter maturation between 90 and 120 days' gestation, as defined by immunohistochemical localization of oligodendrocyte lineage-specific antibodies. There was considerable spatial and temporal heterogeneity in oligodendrocyte maturation in the immature periventricular white-matter. Oligodendrocyte maturation in the 90- to 105-day fetal sheep closely coincided with that of the preterm human during the high-risk period for white-matter injury. Hence, the immature state of the 90- to 105-day fetal periventricular white-matter is an optimal and dynamic developmental window to study the role of cellular-maturational factors in the pathogenesis of white-matter injury. We conclude with a review of the significant advantages of the instrumented fetal sheep to accelerate progress in the translation of preventive therapies for periventricular white-matter injury and cerebral palsy.