Impaired glymphatic system revealed by DTI-ALPS in cerebral palsy due to periventricular leukomalacia: relation with brain lesion burden and hand dysfunction

PURPOSE

Preterm children with cerebral palsy (CP) often have varying hand dysfunction, while the specific brain injury with periventricular leukomalacia (PVL) cannot quite explain its mechanism. We aimed to investigate glymphatic activity using diffusion tensor image analysis along the perivascular space (DTI-ALPS) method and evaluate its association with brain lesion burden and hand dysfunction in children with CP secondary to PVL.

METHODS

We retrospectively enrolled 18 children with bilateral spastic CP due to PVL and 29 age- and sex-matched typically developing controls. The Manual Ability Classification System (MACS) was used to assess severity of hand dysfunction in CP. A mediation model was performed to explore the relationship among the DTI-ALPS index, brain lesion burden, and the MACS level in children with CP.

RESULTS

There were significant differences in the DTI-ALPS index between children with CP and their typically developing peers. The DTI-ALPS index of the children with CP was lower than that of the controls (1.448 vs. 1.625, P = 0.003). The mediation analysis showed that the DTI-ALPS index fully mediated the relationship between brain lesion burden and the MACS level (c' = 0.061, P = 0.665), explaining 80% of the effect.

CONCLUSION

This study provides new insights into the neural basis of hand dysfunction in children with CP, demonstrating an important role of glymphatic impairment in such patients. These results suggest that PVL might affect hand function in children with CP by disrupting glymphatic drainage.

Placental fetal vascular malperfusion, neonatal neurologic morbidity, and infant neurodevelopmental outcomes: a systematic review and meta-analysis

OBJECTIVE

This study aimed to evaluate the association of placental fetal vascular malperfusion lesions with neonatal brain injury and adverse infant neurodevelopmental outcomes.

DATA SOURCES

PubMed and Medline, Scopus, and Cochrane databases were searched from inception to July 2022.

STUDY ELIGIBILITY CRITERIA

We included cohort and case-control studies reporting the associations of fetal vascular malperfusion lesions with neonatal encephalopathy, perinatal stroke, intracranial hemorrhage, periventricular leukomalacia, and infant neurodevelopmental and cognitive outcomes.

METHODS

Data were analyzed by including fetal vascular malperfusion lesions as an exposure variable and brain injuries or neurodevelopmental impairment as outcomes using random-effects models. The effect of moderators, such as gestational age or study type, was assessed by subgroup analysis. Study quality and risk of bias were assessed by applying the Observational Study Quality Evaluation method.

RESULTS

Out of the 1115 identified articles, 26 were selected for quantitative analysis. The rates of neonatal central nervous system injury (neonatal encephalopathy or perinatal stroke) in term or near-term infants were more common among fetal vascular malperfusion cases (n=145) than among controls (n=1623) (odds ratio, 4.00; 95% confidence interval, 2.72-5.90). In premature deliveries, fetal vascular malperfusion lesions did not influence the risk of intracranial hemorrhage or periventricular leukomalacia (odds ratio, 1.40; 95% confidence interval, 0.90-2.18). Fetal vascular malperfusion-associated risk of abnormal infant neurodevelopmental outcome (314 fetal vascular malperfusion cases and 1329 controls) was modulated by gestational age being higher in term infants (odds ratio, 5.02; 95% confidence interval, 1.59-15.91) than in preterm infants (odds ratio, 1.70; 95% confidence interval, 1.13-2.56). Abnormal infant cognitive development and mental development were more common among fetal vascular malperfusion cases (n=241) than among controls (n=2477) (odds ratio, 2.14; 95% confidence interval, 1.40-3.27). The type of study (cohort vs case-control) did not influence the association between fetal vascular malperfusion and subsequent infant brain injury or abnormal neurodevelopmental outcome.

CONCLUSION

The findings of cohort and case-control studies indicate a considerable association between fetal vascular malperfusion placental lesions and increased risk of brain injury in term neonates, and neurodevelopmental impairment in both term and preterm infants. A diagnosis of placental fetal vascular malperfusion should be taken into consideration by both pediatricians and neurologists during the follow-up of infants at risk of adverse neurodevelopmental outcomes.

Inhibition of Microglial Activation by Delayed Mild Hypothermia Reduced Preoligodendrocyte Injury in a Neonatal Rat Brain Slice Model

Periventricular leukomalacia (PVL), characterized by distinctive form of white matter injury, often arises after neonatal cardiac surgery. Proven therapies for PVL are absent. In this study, we designed to quest therapeutic effects of delayed mild hypothermia on PVL and its mechanism in a neonatal rat brain slice model. With the increase of delayed mild hypothermia-treating time, the reduced expression of myelin basic protein and loss of preoligodendrocytes were significantly attenuated after oxygen-glucose deprivation. In addition, the proportion of ionized calcium binding adapter molecule 1 (Iba-1)-positive cells and the expression of Iba-1 were apparently reduced with the increased duration of mild hypothermia treatment. Furthermore, the levels of tumor necrosis factor alpha and interleukin-6 reduced after the mild hypothermia treatment relative to the control. Inhibition of microglial activation with prolonged mild hypothermia may be a potential strategy for white matter protection during cardiopulmonary bypass and hypothermic circulatory arrest.

Use of Thalamus L-Sign to Differentiate Periventricular Leukomalacia From Neurometabolic Disorders

PURPOSE

To assess the diagnostic value of the thalamus L-sign on magnetic resonance imaging (MRI) in distinguishing between periventricular leukomalacia and neurometabolic disorders in pediatric patients.

METHODS

In this retrospective study, clinical and imaging information was collected from 50 children with periventricular leukomalacia and 52 children with neurometabolic disorders. MRI was used to evaluate the L-sign of the thalamus (ie, injury to the posterolateral thalamus) and the lobar distribution of signal intensity changes. Age, sex, gestational age, and level of Gross Motor Function Classification System (only for periventricular leukomalacia) constituted the clinical parameters. Statistical evaluation of group differences for imaging and clinical variables were conducted using univariable statistical methods. The intra- and inter-observer agreement was evaluated using Cohen's kappa. Univariable or multivariable logistic regression was employed for selection of variables, determining independent predictors, and modeling.

RESULTS

The thalamus L-sign was observed in 70% (35/50) of patients in the periventricular leukomalacia group, but in none of the patients with neurometabolic disorder (P < .001). The gestational age between groups varied significantly (P < .001). Involvement of frontal, parietal, and occipital lobes differed significantly between groups (P < .001). In the logistic regression, the best model included negative thalamus L-sign and gestational age, yielding an area under the curve, accuracy, sensitivity, specificity, and precision values of 0.995, 96.1%, 96%, 96.2%, and 96%, respectively. Both the lack of thalamus L-sign and gestational age were independent predictors (P < .001).

CONCLUSIONS

The thalamus L-sign and gestational age may be useful in distinguishing between periventricular leukomalacia and neurometabolic disorders.

Decreased Fetal Movements: A Sign of Placental SARS-CoV-2 Infection with Perinatal Brain Injury

Neonatal COVID-19 is rare and mainly results from postnatal transmission. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), however, can infect the placenta and compromise its function. We present two cases of decreased fetal movements and abnormal fetal heart rhythm 5 days after mild maternal COVID-19, requiring emergency caesarean section at 29 + 3 and 32 + 1 weeks of gestation, and leading to brain injury. Placental examination revealed extensive and multifocal chronic intervillositis, with intense cytoplasmic positivity for SARS-CoV-2 spike antibody and SARS-CoV-2 detection by RT-qPCR. Vertical transmission was confirmed in one case, and both neonates developed extensive cystic peri-ventricular leukomalacia.

Recurrent neonatal sepsis and progressive white matter injury in a premature newborn culture-positive for group B Streptococcus: A case report

RATIONALE

Group B Streptococcus (GBS) remains a principal pathogen causing neonatal sepsis and meningitis, particularly in premature infants with relatively insufficient immunity. Recurrence may occur uncommonly, largely associated with subclinical mucosal persistence or repetitive exposure to exogenous sources. White matter injury (WMI) including cystic periventricular leukomalacia (PVL) has been associated with intrauterine infection/inflammation, and neonatal infection as a more significant predictor including postnatal sepsis and recurrent infection, even without microbial neuroinvasion. Furthermore, clinical and experimental evidence of WMI by some bacteria other than GBS without central nervous system invasion has been reported. However, there is little evidence of WMI associated with neonatal GBS sepsis in the absence of meningitis in the literature.

PATIENT CONCERNS

A newborn at 30+4 weeks' gestation with low birthweight presented with 2 episodes (with a 13-day interval with no antibiotic therapy) of neonatal sepsis culture-proven for GBS with early-onset presentation after clinical chorioamnionitis via vertical GBS transmission and the associated conditions including prematurity-related neonatal immunodeficiency and persistent mucosal GBS carriage after the first antibiotic treatment. The perinatal GBS infection was complicated by progressive WMI presenting with ventriculomegaly and cystic PVL without a definite evidence of meningitis, intraventricular hemorrhage, and documented cerebral hypoxia or hypoperfusion conditions including septic shock.

DIAGNOSES

Recurrent group B streptococcal sepsis and cystic PVL with ventriculomegaly.

INTERVENTIONS

Two episodes of GBS sepsis were treated with 15-day parenteral antibiotic therapy, respectively.

OUTCOMES

Resolution of the recurrent GBS sepsis without further relapses, however, complicated by WMI and subsequent about 6 months delay in motor development at 12 months' corrected age.

LESSONS

This case suggests WMI associated with GBS bacteremia without central nervous system entry by viable GBS and also shows that in premature infants, intrauterine GBS infection with no interventions may lead to extensive and persistent GBS colonization, early-onset and recurrent GBS disease, and WMI. Postnatal as well as intrauterine infection/inflammation controls with maternal prophylaxis may be pivotal for prevention and limiting the magnitude of neurologic injury.

Successful use of an artificial placenta-based life support system to treat extremely preterm ovine fetuses compromised by intrauterine inflammation

BACKGROUND

Ex vivo uterine environment therapy is an experimental intensive care strategy for extremely preterm infants born between 21 and 24 weeks of gestation. Gas exchange is performed by membranous oxygenators connected by catheters to the umbilical vessels. The fetus is submerged in a bath of synthetic amniotic fluid. The lungs remain fluid filled, and pulmonary respiration does not occur. Intrauterine inflammation is strongly associated with extremely preterm birth and fetal injury. At present, there are no data that we are aware of to show that artificial placenta-based systems can be used to support extremely preterm fetuses compromised by exposure to intrauterine inflammation.

OBJECTIVE

To evaluate the ability of our ex vivo uterine environment therapy platform to support extremely preterm ovine fetuses (95-day gestational age; approximately equivalent to 24 weeks of human gestation) exposed to intrauterine inflammation for a period of 120 hours, the following primary endpoints were chosen: (1) maintenance of key physiological variables within normal ranges, (2) absence of infection and inflammation, (3) absence of brain injury, and (4) gross fetal growth and cardiovascular function matching that of age-matched in utero controls.

STUDY DESIGN

Ten ewes with singleton pregnancies were each given a single intraamniotic injection of 10-mg Escherichia coli lipopolysaccharides under ultrasound guidance 48 hours before undergoing surgical delivery for adaptation to ex vivo uterine environment therapy at 95-day gestation (term=150 days). Fetuses were adapted to ex vivo uterine environment therapy and maintained for 120 hours with constant monitoring of key vital parameters (ex vivo uterine environment group) before being killed at 100-day equivalent gestational age. Umbilical artery blood samples were regularly collected to assess blood gas data, differential counts, biochemical parameters, inflammatory markers, and microbial load to exclude infection. Ultrasound was conducted at 48 hours after intraamniotic lipopolysaccharides (before surgery) to confirm fetal viability and at the conclusion of the experiments (before euthanasia) to evaluate cardiac function. Brain injury was evaluated by gross anatomic and histopathologic investigations. Eight singleton pregnant control animals were similarly exposed to intraamniotic lipopolysaccharides at 93-day gestation and were killed at 100-day gestation to allow comparative postmortem analyses (control group). Biobanked samples from age-matched saline-treated animals served as an additional comparison group. Successful instillation of lipopolysaccharides into the amniotic fluid exposure was confirmed by amniotic fluid analysis at the time of administration and by analyzing cytokine levels in fetal plasma and amniotic fluid. Data were tested for mean differences using analysis of variance.

RESULTS

Six of 8 lipopolysaccharide control group (75%) and 8 of 10 ex vivo uterine environment group fetuses (80%) successfully completed their protocols. Six of 8 ex vivo uterine environment group fetuses required dexamethasone phosphate treatment to manage profound refractory hypotension. Weight and crown-rump length were reduced in ex vivo uterine environment group fetuses at euthanasia than those in lipopolysaccharide control group fetuses (P<.05). There were no biologically significant differences in cardiac ultrasound measurement, differential leukocyte counts (P>.05), plasma tumor necrosis factor α, monocyte chemoattractant protein-1 concentrations (P>.05), or liver function tests between groups. Daily blood cultures were negative for aerobic and anaerobic growth in all ex vivo uterine environment group animals. No cases of intraventricular hemorrhage were observed. White matter injury was identified in 3 of 6 lipopolysaccharide control group fetuses and 3 of 8 vivo uterine environment group fetuses.

CONCLUSION

We report the use of an artificial placenta-based system to support extremely preterm lambs compromised by exposure to intrauterine inflammation. Our data highlight key challenges (refractory hypotension, growth restriction, and white matter injury) to be overcome in the development and use of artificial placenta technology for extremely preterm infants. As such challenges seem largely absent from studies based on healthy pregnancies, additional experiments of this nature using clinically relevant model systems are essential for further development of this technology and its eventual clinical application.

[Prevention of brain injury in preterm born infants]

Intra- and periventricular haemorrhage, cystic and diffuse periventricular leucomalacia, post-haemorrhagic ventriculomegali, and cerebral atrophy are "visible" forms of brain injury and explain one third of neurodevelopmental impairment in preterm infants. We have not been successful in proving the benefits of specific preventive measures after birth. The risk of brain injury, however, has decreased over the years, possibly because understanding of the pathophysiology has led to more precisely adapted support of vital functions.

White matter injury in the preterm infant: pathology and mechanisms

The human preterm brain is particularly susceptible to cerebral white matter injury (WMI) that disrupts the normal progression of developmental myelination. Advances in the care of preterm infants have resulted in a sustained reduction in the severity of WMI that has shifted from more severe focal necrotic lesions to milder diffuse WMI. Nevertheless, WMI remains a global health problem and the most common cause of chronic neurological morbidity from cerebral palsy and diverse neurobehavioral disabilities. Diffuse WMI involves maturation-dependent vulnerability of the oligodendrocyte (OL) lineage with selective degeneration of late oligodendrocyte progenitors (preOLs) triggered by oxidative stress and other insults. The magnitude and distribution of diffuse WMI are related to both the timing of appearance and regional distribution of susceptible preOLs. Diffuse WMI disrupts the normal progression of OL lineage maturation and myelination through aberrant mechanisms of regeneration and repair. PreOL degeneration is accompanied by early robust proliferation of OL progenitors that regenerate and augment the preOL pool available to generate myelinating OLs. However, newly generated preOLs fail to differentiate and initiate myelination along their normal developmental trajectory despite the presence of numerous intact-appearing axons. Disrupted preOL maturation is accompanied by diffuse gliosis and disturbances in the composition of the extracellular matrix and is mediated in part by inhibitory factors derived from reactive astrocytes. Signaling pathways implicated in disrupted myelination include those mediated by Notch, WNT-beta catenin, and hyaluronan. Hence, there exists a potentially broad but still poorly defined developmental window for interventions to promote white matter repair and myelination and potentially reverses the widespread disturbances in cerebral gray matter growth that accompanies WMI.

Whole-Brain DTI Assessment of White Matter Damage in Children with Bilateral Cerebral Palsy: Evidence of Involvement beyond the Primary Target of the Anoxic Insult

BACKGROUND AND PURPOSE

Cerebral palsy is frequently associated with both motor and nonmotor symptoms. DTI can characterize the damage at the level of motor tracts but provides less consistent results in nonmotor areas. We used a standardized pipeline of analysis to describe and quantify the pattern of DTI white matter abnormalities of the whole brain in a group of children with chronic bilateral cerebral palsy and periventricular leukomalacia. We also explored potential correlations between DTI and clinical scale metrics.

MATERIALS AND METHODS

Twenty-five patients (mean age, 11.8 years) and 25 healthy children (mean age, 11.8 years) were studied at 3T with a 2-mm isotropic DTI sequence. Differences between patients and controls were assessed both voxelwise and in ROIs obtained from an existing DTI atlas. Clinical metrics included the Gross Motor Function Classification System, the Manual Ability Classification System, and intelligence quotient.

RESULTS

The voxel-level and ROI-level analyses demonstrated highly significant (P < .001) modifications of DTI measurements in patients at several levels: cerebellar peduncles, corticospinal tracts and posterior thalamic radiations, posterior corpus callosum, external capsule, anterior thalamic radiation, superior longitudinal fasciculi and corona radiata, optic nerves, and chiasm. The reduction of fractional anisotropy values in significant tracts was between 8% and 30%. Statistically significant correlations were found between motor impairment and fractional anisotropy in corticospinal tracts and commissural and associative tracts of the supratentorial brain.

CONCLUSIONS

We demonstrated the involvement of several motor and nonmotor areas in the chronic damage associated with periventricular leukomalacia and showed new correlations between motor skills and DTI metrics.

The vulnerability of thalamocortical circuitry to hypoxic-ischemic injury in a mouse model of periventricular leukomalacia

BACKGROUND

Periventricular leukomalacia (PVL) is the leading cause of neurological disabilities including motor and cognitive deficits in premature infants. Periventricular leukomalacia is characterized by damage to the white matter in the immature brain, but the mechanisms by which damage to immature white matter results in widespread deficits of cognitive and motor function are unclear. The thalamocortical system is crucial for human consciousness and cognitive functions, and impaired development of the cortico-thalamic projections in the neonatal period is implicated to contribute importantly to abnormalities of cognitive function in children with PVL.

RESULTS

In this study, using a mouse model of PVL, we sought to test the hypothesis that PVL-like injury affects the different components of the thalamocortical circuitry that can be defined by vesicular glutamate transporters 1 and 2 (vGluT1 and vGluT2), both of which are required for glutamatergic synaptic transmission in the central nervous system. We combined immunocytochemistry and immuno-electron microscopy to investigate changes in cortico-thalamic synapses which were specifically identified by vGluT1 immunolabeling. We found that a drastic reduction in the density of vGluT1 labeled profiles in the somatosensory thalamus, with a reduction of 72-74 % in ventroposterior (VP) nucleus and a reduction of 42-82 % in thalamic reticular nucleus (RTN) in the ipsilateral side of PVL mice. We further examined these terminals at the electron microscopic level and revealed onefold-twofold decrease in the sizes of vGluT1 labeled corticothalamic terminals in VP and RTN. The present study provides anatomical and ultrastructural evidence to elucidate the cellular mechanisms underlying alteration of thalamic circuitry in a mouse model of PVL, and reveals that PVL-like injury has a direct impact on the corticothalamic projection system.

CONCLUSIONS

Our findings provide the first set of evidence showing that the thalamocortical circuitry is affected and vulnerable in PVL mice, supporting a working model in which vGluT1 defined corticothalamic synapses are altered in PVL mice, and vGluT2 defined thalamocortical synapses are associated with such changes, leading to the compromised thalamocortical circuitry in the PVL mice. Our study demonstrates that the thalamocortical circuitry is highly vulnerable to hypoxia-ischemia in the PVL model, thus identifying a novel target site in PVL pathology.

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.

Regional vulnerability of longitudinal cortical association connectivity: Associated with structural network topology alterations in preterm children with cerebral palsy

Preterm born children with spastic diplegia type of cerebral palsy and white matter injury or periventricular leukomalacia (PVL), are known to have motor, visual and cognitive impairments. Most diffusion tensor imaging (DTI) studies performed in this group have demonstrated widespread abnormalities using averaged deterministic tractography and voxel-based DTI measurements. Little is known about structural network correlates of white matter topography and reorganization in preterm cerebral palsy, despite the availability of new therapies and the need for brain imaging biomarkers. Here, we combined novel post-processing methodology of probabilistic tractography data in this preterm cohort to improve spatial and regional delineation of longitudinal cortical association tract abnormalities using an along-tract approach, and compared these data to structural DTI cortical network topology analysis. DTI images were acquired on 16 preterm children with cerebral palsy (mean age 5.6 ± 4) and 75 healthy controls (mean age 5.7 ± 3.4). Despite mean tract analysis, Tract-Based Spatial Statistics (TBSS) and voxel-based morphometry (VBM) demonstrating diffusely reduced fractional anisotropy (FA) reduction in all white matter tracts, the along-tract analysis improved the detection of regional tract vulnerability. The along-tract map-structural network topology correlates revealed two associations: (1) reduced regional posterior-anterior gradient in FA of the longitudinal visual cortical association tracts (inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, optic radiation, posterior thalamic radiation) correlated with reduced posterior-anterior gradient of intra-regional (nodal efficiency) metrics with relative sparing of frontal and temporal regions; and (2) reduced regional FA within frontal-thalamic-striatal white matter pathways (anterior limb/anterior thalamic radiation, superior longitudinal fasciculus and cortical spinal tract) correlated with alteration in eigenvector centrality, clustering coefficient (inter-regional) and participation co-efficient (inter-modular) alterations of frontal-striatal and fronto-limbic nodes suggesting re-organization of these pathways. Both along tract and structural topology network measurements correlated strongly with motor and visual clinical outcome scores. This study shows the value of combining along-tract analysis and structural network topology in depicting not only selective parietal occipital regional vulnerability but also reorganization of frontal-striatal and frontal-limbic pathways in preterm children with cerebral palsy. These finding also support the concept that widespread, but selective posterior-anterior neural network connectivity alterations in preterm children with cerebral palsy likely contribute to the pathogenesis of neurosensory and cognitive impairment in this group.

Expression of ephrinB2 and EphB4 in a neonatal rat model of periventricular white matter damage

BACKGROUND

Periventricular white matter damage (PWMD), also termed periventricular leukomalacia, is the predominant neurologic lesion in preterm infants. It appears to relate in part to the development of the vascular supply to the cerebral white matter. We investigated whether, in case of severe hypoxia-ischemia, the vascular system would be subject to severe damage or remodeled.

AIMS

To evaluate microvessel density (MVD) and the use of ephrinB2 and its receptor EphB4 to mark arterioles and venules to establish the correct anatomic assignment of the remodeled vessels in a hypoxia-induced PWMD rat model.

METHODS

Postnatal day 3 rats underwent permanent ligation of the right common carotid artery followed by 6% O2 for 4 h (hypoxia-ischemia) or sham operation and normoxic exposure (sham). MVD and levels of ephrinB2 and EphB4, which are respectively regarded as relatively specific molecular markers of arteries and veins, were determined at postnatal day 7.

RESULTS

Compared with sham rats, MVD, ephrinB2 and EphB4 levels were higher in the brains of hypoxic-ischemic rats. Similar percentages of vessels expressed ephrinB2 and EphB4 in sham rats, but expression of ephrinB2 was greater in brains injured by hypoxia-ischemia.

CONCLUSIONS

Following hypoxic-ischemic injury to the rat brain, microvessels were remodeled and more arterioles than venules were acquired.

Validity of semi-quantitative scale for brain MRI in unilateral cerebral palsy due to periventricular white matter lesions: Relationship with hand sensorimotor function and structural connectivity

AIM

To provide first evidence of construct validity of a semi-quantitative scale for brain structural MRI (sqMRI scale) in children with unilateral cerebral palsy (UCP) secondary to periventricular white matter (PWM) lesions, by examining the relationship with hand sensorimotor function and whole brain structural connectivity.

METHODS

Cross-sectional study of 50 children with UCP due to PWM lesions using 3 T (MRI), diffusion MRI and assessment of hand sensorimotor function. We explored the relationship of lobar, hemispheric and global scores on the sqMRI scale, with fractional anisotropy (FA), as a measure of brain white matter microstructure, and with hand sensorimotor measures (Assisting Hand Assessment, AHA; Jebsen-Taylor Test for Hand Function, JTTHF; Melbourne Assessment of Unilateral Upper Limb Function, MUUL; stereognosis; 2-point discrimination).

RESULTS

Lobar and hemispheric scores on the sqMRI scale contralateral to the clinical side of hemiplegia correlated with sensorimotor paretic hand function measures and FA of a number of brain structural connections, including connections of brain areas involved in motor control (postcentral, precentral and paracentral gyri in the parietal lobe). More severe lesions correlated with lower sensorimotor performance, with the posterior limb of internal capsule score being the strongest contributor to impaired hand function.

CONCLUSION

The sqMRI scale demonstrates first evidence of construct validity against impaired motor and sensory function measures and brain structural connectivity in a cohort of children with UCP due to PWM lesions. More severe lesions correlated with poorer paretic hand sensorimotor function and impaired structural connectivity in the hemisphere contralateral to the clinical side of hemiplegia. The quantitative structural MRI scoring may be a useful clinical tool for studying brain structure-function relationships but requires further validation in other populations of CP.

Single fetal demise in monochorionic pregnancies: incidence and patterns of cerebral injury

OBJECTIVE

To evaluate the incidence, type and severity of cerebral injury in the surviving monochorionic (MC) cotwin after single fetal demise in twin pregnancies.

METHODS

All MC pregnancies with single fetal demise that were evaluated at the Leiden University Medical Center between 2002 and 2013 were included. Perinatal characteristics, neonatal outcome and the presence of cerebral injury, observed on neuroimaging, were recorded for all cotwin survivors.

RESULTS

A total of 49 MC pregnancies with single fetal demise, including one MC triplet, were included in the study (n = 50 cotwins). Median gestational age at occurrence of single fetal demise was 25 weeks and median interval between single fetal demise and live birth was 61 days, with a median gestational age at birth of 36 weeks. Severe cerebral injury was diagnosed in 13 (26%) of the 50 cotwins and was detected antenatally in 4/50 (8%) and postnatally in 9/50 (18%) cases. Cerebral injury was mostly due to hypoxic-ischemic injury resulting in cystic periventricular leukomalacia, middle cerebral artery infarction or injury to basal ganglia, thalamus and/or cortex. Risk factors associated with severe cerebral injury were advanced gestational age at the occurrence of single fetal demise (odds ratio (OR), 1.14 (95% CI, 1.01-1.29) for each week of gestation; P = 0.03), twin-twin transfusion syndrome developing prior to single fetal demise (OR, 5.0 (95% CI, 1.30-19.13); P = 0.02) and a lower gestational age at birth (OR, 0.83 (95% CI, 0.69-0.99) for each week of gestation; P = 0.04).

CONCLUSIONS

Single fetal demise in MC pregnancies is associated with severe cerebral injury occurring in 1 in 4 surviving cotwins. Routine antenatal and postnatal neuroimaging, followed by standardized long-term follow-up, is mandatory.

Brain abscess of unknown etiology in a 2-year-old child: a case report

We present a case of brain abscess necroptically discovered in a 2-year-old child hospitalized in the Pediatrics Clinic of the "Filantropia" Municipal Hospital, Craiova, Romania. The family, with a poor financial situation, reports previous episodes that may be interpreted as comitial crises. Clinically speaking, he presents a height-weight hypertrophia, vitamin D loss rickets, and psychomotor retardation. At the objective examination, we found a weight of 10 500 g (!), second and third degree mesocardiac systolic beat and cardiomegaly in the thorax-cardiac-pulmonary X-ray examination. Despite the intensive treatment, death occurs few hours after hospitalization. During the autopsy, there is observed a partial dehiscence of the cranial arch sutures, with a 6/5 cm ovalary cavity in the parietal lobe, containing approximately 200 mL of yellow-green serous liquid, with uneven walls, but with no hemorrhagic or puss infiltrates. The heart is enlarged (in comparison to the general somatic development) of 9/7/4 cm, without any cardiac malformations. The microscopic examination showed degenerative neuronal and ischemic lesions on the left-brain hemisphere. Comparing to the data from specialty literature, we consider it as a yellow brain softening (according to Rokitansky's classification), most probably of an embolic cause.

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.

[Expression of endogenous leukemia inhibitory factor in neonatal rats with periventricular leukomalacia]

OBJECTIVE

To study the changes of endogenous leukemia inhibitory factor (LIF) in neonatal rats with periventricular leukomalacia (PVL).

METHODS

A PVL model of 3-day-old Wistar rats was prepared by left carotid artery ligation followed by 6% oxygen for 4 hours. The rats were sacrificed at 1, 3, 7, 14 and 28 days of hypoxia ischemia (HI), and the brain tissues were sampled. Real-Time PCR and Western blot methods were applied to analyze the expression of LIF mRNA and protein. Double staining immunofluorescence was used to detect the co-expression of LIF and GFAP.

RESULTS

At 1, 3 and 7 days of HI, LIF protein level in the PVL group was higher than in the control group (P<0.01). In the PVL group, the LIF protein level on the third day after HI reached a peak and was higher than the other time points (P<0.01). The change of LIF mRNA expression showed the same tendency with LIF protein. The double staining immunofluorescence showed a co-expression of LIF and GFAP.

CONCLUSIONS

LIF mRNA and LIF protein expression in astrocytes show a trend of initial increase followed by steady decline in neonatal rats with PVL, suggesting that endogenous LIF may participate in the repair of PVL.

[Magnetic resonance imaging of premature infants with punctate white matter damage and short-term neurodevelopmental outcome]

OBJECTIVE

To investigate the early diagnosis with MRI changes, MRI types and short-term neurodevelopmental outcome of preterm infants with punctate white matter damage (PWMD).

METHOD

There were 44 preterm infants with PWMD (group A) from March 2009 to August 2010 at the neonatal ward of Shengjing Hospital of China Medical University, according to the number, shape and distribution of the lesions, group A was divided into dot injury group (A1), clusters group (A2) and linear group (A3), the first MRI and DWI scan of all cases were within 14 days after birth, and 17 subjects received re-examination with the MRI in the hospital. Twenty preterm infants with normal MRI (group B) received the follow-up, according to the age, 20 normal full-term infants were selected (group C) as the control group using paired design. Mental development index (MDI) and psychomotor development index (PDI) were determined using Bayley scales of infant development-II.

RESULT

First MRI scan:in 44 infants with PWMD, group A1, A2, A3 separately had, 10, and 9 infants. MRI follow up in 17 cases showed that in 4 cases of A1 group the dot lesions disappeared; in 3 of 4 cases in clusters group who received re-examination, the lesions disappeared, 1 case had periventricular leukomalacia (PVL); in 5 of the 9 cases who had re-examination in linear group the lesions disappeared, while in 4 cases the lesions evolved into PVL. MDI and PDI: Group A [MDI (102.9 ± 15.5) , PDI (107.7 ± 17.5) ] was lower than that of group B[MDI (114.0 ± 13.1) , PDI (120.8 ± 9.4) ], group C [MDI (114.2 ± 12.2) , PDI (119.5 ± 10.7) ] (P < 0.05) . There were no significant differences between group B and group C. Group A1 [MDI (112.2 ± 8.1) , PDI (116.4 ± 8.5) ] had no significant differences compared with group B and group C. Group A2 [MDI (100.8 ± 12.5) , PDI (105.0 ± 12.1) ] showed significantly reduced values compared with group B, Group C, Group A1 (P < 0.05) ,Group A3 [MDI (75.8 ± 11.6) , PDI (79.1 ± 16.2) ] had lower values than group B, Group C, Group A1, and Group A2 (P < 0.05) .

CONCLUSION

Premature infants with PWMD mainly showed dot-like and clustered injury that are easy to be absorbed and disappear, but the linear lesions are likely to evolve into PVL. In addition, the cluster-like and linear injury have an influence on short-term cognition and motion development, especially the outcome of linear injury was the worst.

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.

Neurological impairment in a surviving twin following intrauterine fetal demise of the co-twin: a case study

It has been established that twin pregnancies are at an increased risk for complications, including the risk of morbidity or mortality for one or both of the infants. Cerebral palsy and other associated neurological deficits also occur at higher rates in twin pregnancies. This report examines two cases of intrauterine demise of one twin with subsequent survival of the co-twin. In both cases, the surviving infant suffered significant neurological sequelae. Impairments observed in these two cases include multicystic encephalomalacia and periventricular leukomalacia as well as the subsequent development of cerebral palsy. This case study explores the predisposing factors, incidence, pathophysiology, consequences, and future research implications of these findings.

[The relationship between the severity of periventricular leukomalacia and the fractional anisotropy values of diffusion tensor imaging]

OBJECTIVE

We performed diffusion tensor imaging (DTI) in children with periventricular leukomalacia (PVL) to quantify the relationship between the fractional anisotropy (FA) values of DTI and the severity of PVL.

METHODS

In this study, we performed DTI in 16 children (seven males, nine females) with PVL. To evaluate the FA values, we used region-of-interest (ROI) measurements and tractography-based measurements. We classified the patients into two groups based on the severity of the magnetic resonance imaging (MRI) findings: the mild group had white matter injury limited to a triangular zone around the lateral ventricle (n = 9) and the severe group had it extended forward (n = 7). Then, we performed ROI measurements for these two groups to evaluate the FA values. We also divided the patients into two groups based on their motor ability :those that could (n = 10) and could not (n = 6) stand. We used tractography-based measurements to evaluate the FA values. To reduce the bias caused by age, we divided the patients into two groups: those younger than 3 years and those 3 years of age and older. All data were analyzed using the Mann-Whitney U-test, and p < 0.05 was considered statistically significant.

RESULTS

In the ROI measurements, regardless of age, the severe group showed a more significant FA reduction in the white matter of the parietal and occipital lobes, including the middle/posterior part of the centrum ovale, superior longitudinal fasciculus, arcuate fascicullus, and thalamic radiation. In the tractography-based measurements, regardless of age, the measured FA values were significantly lower in the group that could not stand.

CONCLUSIONS

This study suggested that the measured FA values could be used to evaluate the severity of PVL quantitatively, and that DTI provides much more information for understanding the pathophysiology of PVL, as compared with conventional MRI.

[Endogenous self-repair in immature white matter induced by ischemia in neonatal rats]

OBJECTIVE

To study in vivo the endogenous self-repair mechanism in immature white matter induced by ischemia in neonatal rats with periventricular leukomalacia (PVL).

METHODS

Five-day-old neonatal Sprague-Dawley (SD) rats were randomly divided into sham and PVL groups. Rat model of PVL was prepared by ligation of the right common carotid artery following 2 hours of exposure to 8% oxygen. Pathological changes and myelination in the white matter were assessed under light and electron microscopy at 7 and 21 days after PVL. O4-positive OL precursor cells in the white matter were determined with immunofluorescence staining. Activation, proliferation, migration and differentiation of glial progenitor cells in SVZ were observed using immunofluorescent double labeling of either NG2 (marker of progenitor cells) and 5-bromodeoxyuridine (BrdU), or O4 (marker of OL precursor cells) and BrdU.

RESULTS

All rats in the PVL group manifested either mild or severe white matter injury under light microscopy, and had higher pathological scores of white matter compared with the sham group at 7 and 21 days after PVL (P<0.05). Electron microscopy showed that the number and thickness of myelin sheath in the PVL group were significantly reduced compared with the sham group (P<0.01). O4-positive OL precursor cells in the white matter observed under fluorescence microscopy were significantly reduced in the PVL group compared with the sham group (P<0.05). BrdU/NG2-positive cells in the SVZ increased significantly in the PVL group 48 hours after PVL and migrated into the periventricular area, reaching a peak on day 7 after PVL. BrdU/O4-positive newborn cells began to appear in the periventricular area 72 hours after PVL, and the number of BrdU/O4-positive cells in the PVL group was statistically more than in the sham group on day 21 after PVL (P<0.05).

CONCLUSIONS

Ischemia may induce brain self-repair in neonatal rats, resulting in activation and proliferation of NG2 glial progenitor cells in the SVZ migration and differentiation into OL precursor cells in periventricular white matter.

[Diffusion tensor imaging at term-equivalent age in extremely-low-birth-weight infants with periventricular leukomalacia]

It is important to predict the neurological prognoses of preterm infants as part of their normal follow-up. Previous reports have shown that conventional magnetic resonance imaging (MRI) and electroencephalography are useful in predicting neurological prognoses. Diffusion tensor imaging (DTI) is a relatively new method of evaluating the central nervous system (CNS) that can detect abnormalities quantitatively. We compared DTI at term-equivalent age in two extremely-low-birth-weight infants diagnosed with periventricular leukomalacia (PVL) with conventional MRI and DTI in three control extremely-low-birth-weight infants. DTI was analyzed using the free software, "Volume-one" and "dTVII SR." We compared the fractional anisotropy (FA) values at the corpus callosum, posterior limbs of the internal capsule, cerebral peduncle, and corticospinal tract using manual region of interest (ROI) analysis, and at the commissural fibers and corticospinal tract using tract-specific analysis. The FA values were lower in patients with PVL than in control infants at all measurement points, except the commissural fibers on tract-specific analysis. These measurement points showed no abnormality using conventional MRI. This suggests that DTI can detect CNS abnormalities that cannot be detected with conventional MRI. However, our sample size was very small and we examined only cases in which PVL was detected with conventional MRI. Further study is necessary to examine the correlation of DTI findings and neurological prognoses in infants who have no abnormality on conventional MRI.

Diffuse periventricular leukomalacia in preterm children: assessment of grey matter changes by MRI

BACKGROUND

Preterm children may have cognitive deficits and behavioural disorders suggestive of grey matter (GM) injury. The prevalence is higher in preterm children with diffuse periventricular leukomalacia (dPVL).

OBJECTIVE

Evaluate changes in the volume of 116 GM areas in preterm children with dPVL.

METHODS AND MATERIALS

Eleven preterm children with dPVL, gestational age 32.8 ± 2.6 weeks, examined at corrected age 22.0 ± 18.2 months and 33 matched preterm controls with normal brain MRI were studied. Volumes of 116 individual GM areas, and white matter/cerebrospinal fluid (WM/CSF) ratio were calculated on T1-weighted high-resolution images after segmentation.

RESULTS

Relative to controls, children with dPVL had decreased GM volume of the hippocampus, amygdala, and frontal lobes and temporal middle gyrus (P < 0.05); increased GM volume of the putamen, thalamus, globus pallidum, superior temporal gyrus and of the parietal and occipital lobes (P < 0.05) and lower WM volume/higher CSF volume (P < 0.05). WM/CSF ratios also differed (P < 0.05).

CONCLUSIONS

Preterm children with dPVL have increased regional GM volume in some areas probably related with a process of brain plasticity-regeneration and reduced GM volume in areas associated with cognition and memory.

Hypoxic ischemic cerebral lesions of the newborn--ultrasound diagnosis. Pictorial essay

Transcranial ultrasonography is the most widely used neuroimaging technique in both premature and full term infants. The high susceptibility to hypoxia of the preterm brain explains the raised prevalence of intracranial haemorrhages at this group of patients. Ultrasound examination contributes to assessment of the neurologic status in children by diagnosing and staging of the intracranial bleeding, and brings informations about immediate and long term prognosis. The two major pictures of cerebral damage secondary to perinatal hypoxia are: peri and intraventricular haemorrhages and periventricular leucomalacia respectively. This paper present the major features for ultrasound diagnosis in both pathological situations.

Neuroprotective potential of erythropoietin and its derivative carbamylated erythropoietin in periventricular leukomalacia

Periventricular leukomalacia (PVL) is the predominant pathology in premature infants, characterized by prominent cerebral white matter injury, and commonly caused by hypoxia-ischemia and inflammation. Activated microglia trigger white matter damage and play a major role in the development of PVL. Erythropoietin (EPO) and its derivative carbamylated erythropoietin (CEPO) have been shown to be neuroprotective in several brain disease models. Here we investigated whether EPO and CEPO could provide protection in mouse models of PVL induced by hypoxia-ischemia or hypoxia-ischemia-inflammation. We administered EPO or CEPO to mice with PVL, and found that both EPO and CEPO treatments decreased microglia activation, oligodendrocyte damage and myelin depletion. We also noted improved performance in neurological function assays. Inhibited disease progression in PVL mice by EPO or CEPO treatment was associated with decreased poly-(ADP-ribose) polymerase-1 (PARP-1) activity. PARP-1 activity was increased dramatically in activated microglia in untreated mice with PVL. Furthermore, we demonstrated that the neuroprotective properties of EPO and CEPO were diminished after PARP-1 gene depletion. The therapeutic doses of EPO and CEPO used in this study did not interfere with normal oligodendrocyte maturation and myelination. Together, our data demonstrate that EPO and CEPO are neuroprotective in cerebral white matter injury via a novel microglial PARP-1 dependent mechanism, and hold promise as a future treatment for PVL and other hypoxic-ischemic/inflammatory white matter diseases.

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

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

[Mechanisms of genome instability in children with periventricular leucomalacia that resulted in cerebral palsy]

The activity of free-radical oxidation and the level of genome instability in children with periventricular leucomalacia that resulted in cerebral palsy have been studied. Genome destabilization, i.e., the elevation of erythrocyte micronuclei in the peripheral blood, has been reported. There was a correlation of a number of cells with cytogenetic rearrangements with the activity of antioxidant defense enzymes and the malonaldehyde level. It has been shown that genome instability occurs during the activation of endogenous mutagenesis and reduction of antiradical and antimutagenic defense. Having, along with the neurotrophic effect, antiradical and antimutagenic effects, cortexin is capable to inhibit the pronounced processes of free-radical oxidation and endogenous mutagenesis in patients with periventricular leucomalacia that resulted in spastic dyplegia exerting.

Cerebral cortical folding analysis with multivariate modeling and testing: Studies on gender differences and neonatal development

This paper presents a novel statistical framework for human cortical folding pattern analysis that relies on a rich multivariate descriptor of folding patterns in a region of interest (ROI). The ROI-based approach avoids problems faced by spatial normalization-based approaches stemming from the deficiency of homologous features between typical human cerebral cortices. Unlike typical ROI-based methods that summarize folding by a single number, the proposed descriptor unifies multiple characteristics of surface geometry in a high-dimensional space (hundreds/thousands of dimensions). In this way, the proposed framework couples the reliability of ROI-based analysis with the richness of the novel cortical folding pattern descriptor. This paper presents new mathematical insights into the relationship of cortical complexity with intra-cranial volume (ICV). It shows that conventional complexity descriptors implicitly handle ICV differences in different ways, thereby lending different meanings to "complexity". The paper proposes a new application of a nonparametric permutation-based approach for rigorous statistical hypothesis testing with multivariate cortical descriptors. The paper presents two cross-sectional studies applying the proposed framework to study folding differences between genders and in neonates with complex congenital heart disease. Both studies lead to novel interesting results.

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.

Nitrosative stress and inducible nitric oxide synthase expression in periventricular leukomalacia

Periventricular leukomalacia (PVL) is a lesion of the immature cerebral white matter in the perinatal period and associated predominantly with prematurity and cerebral ischemia/reperfusion as well as inflammation due to maternofetal infection. It consists of focal necrosis in the periventricular region and diffuse gliosis with microglial activation and premyelinating oligodendrocyte (pre-OL) injury in the surrounding white matter. We previously showed nitrotyrosine in pre-OLs in PVL, suggesting involvement of nitrosative stress in this disorder. Here we hypothesize that inducible nitric oxide synthase (iNOS) expression is increased in PVL relative to controls. Using immunocytochemistry in human archival tissue, the density of iNOS-expressing cells was determined in the cerebral white matter of 15 PVL cases [29-51 postconceptional (PC) weeks] and 16 control cases (20-144 PC weeks). Using a standardization score of 0-3, the density of iNOS-positive cells was significantly increased in the diffuse component of PVL (score of 1.8 +/- 0.3) cases compared to controls (score of 0.7 +/- 0.3) (P = 0.01). Intense iNOS expression occurred in reactive astrocytes in acute through chronic stages and in activated microglia primarily in the acute stage, suggesting an early role for microglial iNOS in PVL's pathogenesis. This study supports an important role for iNOS-induced nitrosative stress in the reactive/inflammatory component of PVL.

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.

Thalamic damage in periventricular leukomalacia: novel pathologic observations relevant to cognitive deficits in survivors of prematurity

Despite major advances in the long-term survival of premature infants, cognitive deficits occur in 30-50% of very preterm (<32 gestational weeks) survivors. Impaired working memory and attention despite average global intelligence are central to the academic difficulties of the survivors. Periventricular leukomalacia (PVL), characterized by periventricular necrosis and diffuse gliosis in the cerebral white matter, is the major brain pathology in preterm infants. We tested the novel hypothesis that pathology in thalamic nuclei critical for working memory and attention, i.e. mediodorsal nucleus and reticular nucleus, respectively, occurs in PVL. In 22 PVL cases (gestational age 32.5 +/- 4.8 wk) and 16 non-PVL controls (36.7 +/- 5.2 wk) who died within infancy, the incidence of thalamic pathology was significantly higher in PVL cases (59%; 13/22) compared with controls (19%; 3/16) (p = 0.01), with substantial involvement of the mediodorsal, and reticular nuclei in PVL. The prevention of thalamic damage may be required for the eradication of defects in survivors with PVL.

Diffuse axonal injury in periventricular leukomalacia as determined by apoptotic marker fractin

Periventricular leukomalacia (PVL), the major substrate of neurologic deficits in premature infants, is associated with reduced white matter volume. Using immunomarkers of axonal pathology [beta-amyloid precursor protein (beta-APP) and apoptotic marker fractin], we tested the hypothesis that widespread (diffuse) axonal injury occurs in the gliotic white matter beyond the foci of necrosis in PVL, thus contributing to the white matter volume reduction. In a cohort of 17 control cases and 13 PVL cases with lesions of different chronological ages, diffuse axonal damage in PVL was detected by fractin in white matter sites surrounding and distant from acute and organizing foci of necrosis. Using beta-APP, axonal spheroids were detected within necrotic foci in the acute and organizing (subacute) stages, a finding consistent with others. Interestingly, GAP-43 expression was also detected in spheroids in the necrotic foci, suggesting attempts at axonal regeneration. Thirty-one percent of the PVL cases had thalamic damage and 15% neuronal injury in the cerebral cortex overlying PVL. We conclude that diffuse axonal injury, as determined by apoptotic marker fractin, occurs in PVL and that its cause likely includes primary ischemia and trophic degeneration secondary to corticothalamic neuronal damage.

[Cerebral pathological evaluation following neural stem cells intraventricular transplantation in neonatal rats with periventricular leukomalacia]

OBJECTIVE

To evaluate the brain pathological changes following exdogenous neural stem cells (NSCs) intraventricular transplantation in neonatal rats with periventricular leukomalacia (PVL), and to explore the feasibility of NSCs transplantation for the treatment of PVL in premature infants.

METHODS

NSCs were prepared from E14 embryonic rat brain. Two-day-old neonatal rats were randomly divided into six groups: PVL, PVL+culture medium, PVL+NSCs, sham operation, sham operation+culture medium, and sham operation+NSCs (18-21 rats each group). Intraventricular transplantation of exdogenous NSCs was performed 72 hrs after PVL induction or sham operation. The cerebral pathological evaluation was undertaken by light microscopy 7, 14 and 21 days after transplantation.

RESULTS

The pathological changes in the cerebral white matter were gradually improved with the prolonged time after transplantation. After 21 days of transplantation, 50% of the cerebral white matter showed mild pathological changes and 50% of that showed severe pathological changes, with neuronal pathological scores of 1.28+/-0.86, in the untreated PVL group. In the PVL+NSCs group, 30% of normal white matter, 40% of mild and 30% of severe pathological changes in the white matter were observed, with neuronal pathological scores of 0.32+/-0.16, 21 days after transplantation. There were very significant differences in both of pathological changes in the cerebral white matter and neuronal pathological scores between the PVL and PVL+NSCs groups (x2=10.7, P<0.01; F=29.664, P<0.01).

CONCLUSIONS

Intraventricular transplantation of exdogenous NSCs can apparently improve cerebral white matter damage. It is suggested that intraventricular transplantation of NSCs is of a great potential feasibility for the treatment of PVL in premature infants.

[Values of diffusion-weighted magnetic resonance imaging in the early detection of periventricular leukomalacia in preterm infants]

OBJECTIVE

Periventricular leukomalacia (PVL), the principal form of brain injury in the premature infant, is characterized by overt focal necrotic lesions in periventricular white matter and diffuse cerebral white matter injury. The early detection of the disease is not consistently possible with cranial ultrasonography or conventional magnetic resonance imaging (MRI). Recently, diffusion-weighted imaging (DWI) has been shown to be highly sensitive in detecting acute ischemic cerebral injury. This study aimed to evaluate possible role of DWI in early diagnosis of PVL.

METHODS

Images and clinical data from 12 preterm infants with PVL diagnosed in our NICU from August, 2005 to April, 2007 were reviewed. MRI using conventional and diffusion-weighted imaging, as well as the assays of blood routine test, serum bilirubin, C-reactive protein (CRP), blood culture, blood gas analysis, blood sugar and serum ions were performed in these preterm infants. All examinations were performed on a 3.0-T MRI system (Philips Intera Acheva Magnetom Vision) with echo-planar imaging capability with the use of a standard protocol. The imaging protocol for all the patients contained diffuse weighted images (EPI-SE, TR = 2144 ms, TE = 56 ms), T1-weighted images (TR = 389 ms; TE = 15 ms; slice thickness = 4 mm) as well as T2-weighted images (TR = 3035 ms; TE = 100 ms; slice thickness = 4 mm). The first MR examinations were performed in all these twelve preterm infants (mean age 4.5 days, range 2 - 7 days). Conventional MRI and DWI sequences obtained in the acute phase were compared. All the neonates underwent another two MRI examinations up to 2 and 4 weeks after delivery; five subjects also underwent MRI follow-up for up to 4 - 8 months (in 3 for 4 months, in 1 for 7 months, and in another for 8 months). Qualitative evaluations were performed to assess the presence of DWI changes compatible with PVL.

RESULTS

The gestational ages of these twelve patients were from 31 to 35 weeks. None of them had intrauterine distress or birth asphyxia. None of the patients had localized neurological signs in the early course except for abnormal muscular tone of some extent, but seizure and apnea were their major symptoms. No other positive signs of nervous system was found in these preterm infants with PVL. First DWI detection (on the average of 4.5 days) in all these infants showed bilateral, symmetric, diffuse high signal intensity (including genu and plenum of corpus callosum), while conventional MRI showed normal images on both T1- and T2-weighted imaging; two weeks later, DWI showed irregularly high, low mixed signals while conventional MRI showed punctate high signal intensity on T1-weighted imaging and slightly lower signal on T2-weighted imaging. Four weeks later, DWI showed cystic low signal intensity where conventional MRI showed low signal intensity on T1-weighted imaging and high signal intensity on T2-weighted imaging (cystic PVL). Four months later, DWI showed that the cystic cava became diminished and disappeared, while conventional MRI showed reduced cerebral white matter and dilation of ventricle.

CONCLUSION

Bilateral, symmetric, diffuse high signal intensity on DWI seems to be the earliest evidence of PVL; diffusion-weighted imaging performed in the acute phase of the disease may have a higher correlation with later evidence of PVL than does conventional MR imaging. DWI is likely to be a considerable technique in the early assessment of white matter injury and later PVL in preterm infants.

Pontine hypoplasia in children with periventricular leukomalacia

BACKGROUND AND PURPOSE

The brain stem in patients with periventricular leukomalacia (PVL) appears smaller than normal on MR imaging, but few reports have described this feature, and the number of patients has been relatively small. The present study was conducted to examine the hypothesis that the pons in patients with PVL is smaller than normal.

MATERIALS AND METHODS

Using MR imaging, we examined 80 children (43 boys and 37 girls) with PVL and 80 age-matched control children (41 boys and 39 girls). The control children were diagnosed as neurologically and developmentally normal by pediatric neurologists and also showed normal MR imaging findings. MR imaging was performed at a corrected age range of 0-5 years in both groups. We measured the anteroposterior diameter of the whole pons, the tegmentum and the basis, and the corpus callosal length by using midline T1-weighted sagittal images and compared each parameter between the PVL groups and the control groups.

RESULTS

Pontine diameters in all of the regions were significantly smaller in the PVL group than in the control group (mean +/- SD, whole pontine diameters, 1.66 +/- 0.21 and 1.87 +/- 0.23 cm [P < .001]; basis diameters, 0.42 +/- 0.10 and 0.51 +/- 0.14 [P < .001]; tegmentum diameters, 1.23 +/- 0.20 and 1.36 +/- 0.19 [P < .001], respectively). The respective corpus callosal lengths were 5.02 +/- 0.90 and 5.51 +/- 0.76 (P < .001). There was no significant difference in the basis/tegmentum ratio between the PVL group and the control group. When the age-related pontine diameter differences were examined, there was already a significant difference at 0 years of age between the 2 groups. There was a significant correlation between whole pontine diameter and corpus callosal length in the PVL group (correlation coefficient, 0.52; P < .001) and the control group (correlation coefficient, 0.63; P < .001).

CONCLUSION

We have proven that pontine diameter in patients with PVL is significantly smaller than that in normal control subjects, including each diameter of basis and tegmentum.

Cerebral palsy

Cerebral palsy (CP) is a group of disorders of movement and posture resulting from nonprogressive disturbances of the fetal or neonatal brain. More than 80% of cases of CP in term infants originate in the prenatal period; in premature infants, both prenatal or postnatal causes contribute. The most prevalent pathological lesion seen in CP is periventricular white matter injury (PWMI) resulting from vulnerability of the immature oligodendrocytes (pre-OLs) before 32 wk of gestation. PWMI is responsible for the spastic diplegia form of CP and a spectrum of cognitive and behavioral disorders. Oxidative stress and excitotoxicity resulting from excessive stimulation of ionotropic glutamate receptors on preOLs are the most prominent molecular mechanisms for PWMI. Asphyxia around the time of birth in term infants accounts for less than 15% of CP in developed countries but the incidence is higher in underdeveloped areas. Asphyxia causes a different pattern of brain injury and CP than is seen after preterm injuries. This type of CP is associated with the clinical syndrome of hypoxic-ischemic encephalopathy shortly after the insult, and the cortex, basal ganglia, and brainstem are selectively vulnerable to injury. Experimental models indicate that neurons in the neonatal brain are more likely to die by delayed apoptosis extending over days to weeks than those in the adult brain. Neurons die by glutamate-mediated excitotoxicity involving downstream caspase-dependent and caspase-independent cell death pathways. Recent reports indicate that males and females preferentially utilize different pathways. Clinical trials indicate that mild hypothermia reduces death or disability in term infants following asphyxia and basic research suggests that this approach might be combined with pharmacological strategies in the future.

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.

Diffusion tensor imaging in children with periventricular leukomalacia: variability of injuries to white matter tracts

BACKGROUND AND PURPOSE

Conventional MR imaging shows evidence of brain injury and/or maldevelopment in 70%-90% of children with cerebral palsy (CP), though its capability to identify specific white matter tract injury is limited. The great variability of white matter lesions in CP already demonstrated by postmortem studies is thought to be one of the reasons why response to treatment is so variable. Our hypothesis is that diffusion tensor imaging (DTI) is a suitable technique to provide in vivo characterization of specific white matter tract lesions in children with CP associated with periventricular leukomalacia (PVL).

MATERIALS AND METHODS

In this study, 24 children with CP associated with PVL and 35 healthy controls were evaluated with DTI. Criteria for identification of 26 white matter tracts on the basis of 2D DTI color-coded maps were established, and a qualitative scoring system, based on visual inspection of the tracts in comparison with age-matched controls, was used to grade the severity of abnormalities. An ordinal grading system (0=normal, 1=abnormal, 2=severely abnormal or absent) was used to score each white matter tract.

RESULTS

There was marked variability in white matter injury pattern in patients with PVL, with the most frequent injury to the retrolenticular part of the internal capsule, posterior thalamic radiation, superior corona radiata, and commissural fibers.

CONCLUSION

DTI is a suitable technique for in vivo assessment of specific white matter lesions in patients with PVL and, thus, a potentially valuable diagnostic tool. The tract-specific evaluation revealed a family of tracts that are highly susceptible in PVL, important information that can potentially be used to tailor treatment options in the future.

Diffuse white matter injury and neurologic outcomes of infants born very preterm in the 1990s

Neurocognitive outcomes of infants born very preterm (less than 32 weeks gestation) remain a major concern in perinatal practice. Very preterm birth rates have increased, with enhanced survival since 1990. As focal brain lesions become less common, diffuse injury to both gray and white matter is now the primary focus for improving neurologic outcomes in survivors. Recent evidence supports preoligodendrocytes as the principal cellular target of diffuse white matter injury due to their susceptibility to hypoxic-ischemic and inflammatory insults. An understanding of their development and vulnerability can inform acute nursing care of very preterm infants.