Brain Maturation as a Fundamental Factor in Immune-Neurovascular Interactions in Stroke

Injuries in the developing brain cause significant long-term neurological deficits. Emerging clinical and preclinical data have demonstrated that the pathophysiology of neonatal and childhood stroke share similar mechanisms that regulate brain damage, but also have distinct molecular signatures and cellular pathways. The focus of this review is on two different diseases-neonatal and childhood stroke-with emphasis on similarities and distinctions identified thus far in rodent models of these diseases. This includes the susceptibility of distinct cell types to brain injury with particular emphasis on the role of resident and peripheral immune populations in modulating stroke outcome. Furthermore, we discuss some of the most recent and relevant findings in relation to the immune-neurovascular crosstalk and how the influence of inflammatory mediators is dependent on specific brain maturation stages. Finally, we comment on the current state of treatments geared toward inducing neuroprotection and promoting brain repair after injury and highlight that future prophylactic and therapeutic strategies for stroke should be age-specific and consider gender differences in order to achieve optimal translational success.

Perinatal Stroke in a Chinese Neonatal Center: Clinical Characteristics, Long-Term Outcomes, and Prognostic Factors

BACKGROUND

Neonatal stroke manifests atypically and can potentially result in significant neurological sequelae in affected infants. Studies on long-term neurodevelopmental outcomes and prognostic factors are limited. We aimed to assess the clinical characteristics, long-term outcomes, and prognostic factors of perinatal stroke.

METHODS

Patients diagnosed with perinatal stroke were enrolled from 2009 to 2018. Clinical data including general information, clinical manifestations, and risk factors were collected and compared. Follow-up was performed for at least two years. Statistical analysis was performed using the chi-square test, t tests, and logistic regression analysis.

RESULTS

Sixty-nine cases were identified with an incidence of one of 2049 live births (51 boys and 18 girls). Twenty-seven patients (39%) experienced perinatal ischemic stroke (PIS) and 42 (61%) perinatal hemorrhagic stroke (PHS). In 48 cases (69%) onset involved acute symptomatic stroke (21 ischemic strokes and 27 hemorrhagic strokes). Seizures within 12 to 72 hours (20 cases, 29%) were the most common presentations. Most (57%) perinatal arterial ischemic strokes focused on the left middle cerebral artery. About 43% of PHS was diagnosed with temporal lobe hemorrhage, and 40% of patients exhibited multiple lesions of cerebral parenchymal hemorrhage. There was no association between adverse prognosis after perinatal stroke and different risk factors. During follow-up, six patients (10%) were dead and 22 patients (35%) experienced adverse neurodevelopmental outcomes.

CONCLUSIONS

More infants exhibited hemorrhagic stroke than ischemic stroke. Among infants with asymptomatic perinatal stroke, PHS was more common. The first symptom of perinatal stroke within 12 to 72 hours after birth is convulsions, with the left middle cerebral artery and the temporal lobe being the most common lesion sites for ischemic and hemorrhagic strokes, respectively. PIS was more likely to achieve adverse outcomes.

Role of advanced (magnetic resonance) neuroimaging and clinical outcomes in neonatal strokes: Experience from tertiary care center

Neonatal strokes constitute a major cause of pediatric mortality and morbidity. Neuroimaging helps in its diagnosis as well as prognostication. However, advanced imaging, including magnetic resonance imaging (MRI), carries multiple challenges. Limited data exists in the literature on imaging-based predictors of neurological outcomes in neonatal stroke in the Indian population. In this study, we reviewed our available data on neonatal stroke patients between 2015 and 2020 for clinico-radiological patterns. During this period, 17 neonatal strokes were admitted and the majority were term births with a slight male preponderance. Seizures and encephalopathy were the most common presentation. Multiple maternal risk factors such as gestational diabetes, meconium-stained liquor, APLA syndrome, fever, deranged coagulation profile, oligohydramnios, cord prolapse, and non-progressive labor were seen. Cardiac abnormalities were seen in only less than half of these patients with the most common finding being atrial septal defects (ASD). Transcranial ultrasound was performed in eight neonates and the pick-up rate of ultrasound was poor. MR imaging showed large infarcts in 11 patients. The MCA territory was most commonly involved. Interestingly, five neonates had venous thrombosis with three showing it in addition to arterial thrombosis. Associated ictal, as well as Wallerian changes, were noted in 10. Although large territorial infarcts were the most common pattern, non-contrast MR angiography did not show major vessel occlusion in these cases. Outcomes were fairly good and only three patients had a residual motor deficit at 1 year. No recurrence of stroke was seen in any of the neonates.

Maternal n-3 Polyunsaturated Fatty Acid Enriched Diet Commands Fatty Acid Composition in Postnatal Brain and Protects from Neonatal Arterial Focal Stroke

The fetus is strongly dependent on nutrients from the mother, including polyunsaturated fatty acids (PUFA). In adult animals, n-3 PUFA ameliorates stroke-mediated brain injury, but the modulatory effects of different PUFA content in maternal diet on focal arterial stroke in neonates are unknown. This study explored effects of maternal n-3 or n-6 enriched PUFA diets on neonatal stroke outcomes. Pregnant mice were assigned three isocaloric diets until offspring reached postnatal day (P) 10–13: standard, long-chain n-3 PUFA (n-3) or n-6 PUFA (n-6) enriched. Fatty acid profiles in plasma and brain of mothers and pups were determined by gas chromatography–mass spectrometry and cytokines/chemokines by multiplex protein analysis. Transient middle cerebral artery occlusion (tMCAO) was induced in P9-10 pups and cytokine and chemokine accumulation, caspase-3 and calpain-dependent spectrin cleavage and brain infarct volume were analyzed. The n-3 diet uniquely altered brain lipid profile in naïve pups. In contrast, cytokine and chemokine levels did not differ between n-3 and n-6 diet in naïve pups. tMCAO triggered accumulation of inflammatory cytokines and caspase-3-dependent and -independent cell death in ischemic-reperfused regions in pups regardless of diet, but magnitude of neuroinflammation and caspase-3 activation were attenuated in pups on n-3 diet, leading to protection against neonatal stroke. In conclusion, maternal/postnatal n-3 enriched diet markedly rearranges neonatal brain lipid composition and modulates the response to ischemia. While standard diet is sufficient to maintain low levels of inflammatory cytokines and chemokines under physiological conditions, n-3 PUFA enriched diet, but not standard diet, attenuates increases of inflammatory cytokines and chemokines in ischemic-reperfused regions and protects from neonatal stroke.

Pediatric Acute Ischemic Stroke by Age-Group: A Systematic Review and Meta-Analysis of Published Studies and Hospitalization Records

BACKGROUND

Although stroke is rare among the pediatric population, it is nevertheless associated with serious or life-threatening consequences. The etiologic factors of acute ischemic stroke (AIS) are likely to vary over the course of childhood development. The incidence rates of AIS, not previously systematically examined by pediatric age subgroup, could guide studies of its etiology.

OBJECTIVE

The aim of this study is to evaluate the incidence rate of AIS by age-group in the pediatric population (aged 0-17/18 years) and identify any common trends or sources of variability across different countries.

METHODS

Rates of pediatric AIS were collated from a systematic literature review of published studies globally (1983-2020) and hospitalization records from Europe and the USA (2015-2018). Records that were included in the analysis reported the code or description used for AIS diagnosis and age-specific data for children aged 0-17/18 years. AIS incidence rates were summarized by age-group, data source, country, and geographic region. A meta-analysis was conducted to assess the heterogeneity of AIS rates in neonates.

RESULTS

The pooled AIS incidence rate was 5.6 per 100,000 children across all records. When only records reporting the AIS incidence rates for children across the full age range (0-17/18 years) were analyzed, the pooled AIS incidence rate was 4.6 per 100,000 children and ranged from 7.0 per 100,000 (Germany) to 1.3 per 100,000 (Denmark). The highest pooled rates were observed in the 0-28-day age-group (24.6 per 100,000 live births), declining to the lowest rates in the 5-9-year age-group, and rising again in the 10-17/18-year age-group. AIS rates were the most heterogeneous in the 0-28-day age-group and across European countries. Significantly higher AIS rates in neonates were observed from hospital databases (35.9 per 100,000) than in the literature (19.4 per 100,000). AIS rates may be underestimated as pediatric AIS events are rare and challenging to diagnose, and limited age-specific data are available.

CONCLUSIONS

Incidence rates of pediatric AIS by age-groups followed a consistent overall pattern of a reverse J-shaped curve, with the highest rates in neonates, across predominantly European and North American countries. Further research is warranted to examine if this pattern is observed in other geographic regions and to identify AIS risk factors specific to different phases of childhood development.

Neonatal Subpial Hemorrhage: Clinical Factors, Neuroimaging, and Outcomes in a Quaternary Care Children's Center

BACKGROUND

Subpial hemorrhages are underrecognized, underreported, and poorly understood. The spectrum of their clinical manifestations and consequences in neonates has not been fully described. Here, we describe the demographic, clinical, and radiographic characteristics of neonates with subpial hemorrhages.

METHODS

We reviewed the medical records and neuroimaging studies of neonates with subpial hemorrhage who were admitted to our neonatal intensive care unit between September 2009 and December 2020.

RESULTS

Of 114 neonates with intracranial hemorrhage, 31 (27%) had subpial hemorrhage. The majority of neonates in our cohort were male (68%) and born at term (55%). The most common imaging indication was apneas and/or seizures in 58%. Common comorbid conditions included cardiorespiratory failure (42%), hypoxic-ischemic encephalopathy (26%), and coagulopathy (23%). Subpial hemorrhages were multifocal in 45% of neonates, located in the temporal lobe in 45% of neonates, and tended to be larger in neonates with coagulopathy, birth trauma, or hydrocephalus requiring neurosurgical intervention. Subpial hemorrhage was associated with another type of intracranial bleed in 77% of cases and with arterial ischemic stroke in 16% of cases. Of 17 patients with more than one year of follow-up data, 14 (82%) have developmental delay and four (24%) have epilepsy. Of 14 patients with follow-up imaging, 10 (71%) had encephalomalacia subjacent to the subpial hemorrhage.

CONCLUSIONS

This is the largest cohort of neonates with subpial hemorrhages to date. Outcome data are limited by duration of follow-up and may be confounded by comorbid conditions and other concurrent hemorrhages. Further study is needed to define the spectrum of risk factors and expected neurological outcomes.

Parent experiences and developmental outcomes following neonatal stroke

OBJECTIVE

Parents of children with neonatal stroke offer critical insight into potential avenues to direct neuropsychological care from the time of diagnosis through the early years. The aims of this study were to (1) describe what parents remember about early prognostic discussions with the medical team and (2) to examine the relationships between initial prognoses and the child's current neurodevelopmental status and parents' mental health. Method: Thirty parents of children with neonatal stroke completed the Depression Anxiety Stress Scales (DASS) and Parent Experiences Questionnaire (PEQ). The children of these parents were also seen for neurodevelopmental/neuropsychological assessments. Results: Parents recalled discussions with the medical team about motor, language, cognitive, and academic outcomes, with fewer discussions about the impact of neonatal stroke on their child's social skills, behavior, attention, mental health, and adaptive functioning. Many parents recalled poor initial prognoses following their child's diagnosis, with better than expected outcomes 3 years later. Parent self-reported depression, anxiety, and stress were associated with higher ratings of externalizing symptoms in their child. There were no significant correlations between parent mental health and their perception of their child's internalizing symptoms, neurodevelopmental functioning, or any of the child's medical/demographic factors. Conclusions: This study highlights the role of the neuropsychologist in the child's care in educating families and monitoring outcomes, emphasizes mental health support for parents of children with a history of neonatal stroke, and reiterates how environmental factors outside of the neonatal stroke itself can impact the child's functioning.

Differences in coordination and timing of pre-reaching upper extremity movements may be an indicator of cerebral palsy in infants with stroke: A preliminary investigation

BACKGROUND

Neonatal stroke is a leading cause of hemiplegic cerebral palsy that occurs around the time of birth. Infants are diagnosed with cerebral palsy when motor impairments become clinically apparent, months or years after the stroke. Tools/methods for identifying high risk or diagnosis of cerebral palsy in infancy are improving.

METHODS

We measured spatial and temporal kinematics of pre-reaching upper extremity movements in 2-3 month old infants with neonatal stroke and typical development. We aimed to evaluate the feasibility of applying kinematics in this population and collect preliminary data to explore (1) if asymmetries are present in the infants with neonatal stroke, particularly those with a later diagnosis of cerebral palsy, and (2) to compare differences in the timing and coordination of their movements to infants with typical development, and infants with stroke and no cerebral palsy. Participants were 21 full-term infants, 10 with stroke (4 who later received a cerebral palsy diagnosis) age 72.1 (SD 9.3) days, and 11 typically developing, age 74.3 (SD 9.3) days.

FINDINGS

Results showed that infants with stroke and cerebral palsy demonstrated significant asymmetry in the average movement length (p = 0.0089) and hand path length (p = 0.0275) between their involved and uninvolved sides and moved less frequently (p = 0.09) and slower (p = 0.041) than infants with stroke and no cerebral palsy.

INTERPRETATION

Results suggest that kinematic analysis might detect asymmetries and motor impairment indicative of hemiplegic cerebral palsy earlier than current assessments and that asymmetry in speed, length and frequency of arm movements may be early indicators. This study is preliminary, limiting interpretation of the results.

Diffusion Imaging of Cerebral Diaschisis in Neonatal Arterial Ischemic Stroke

BACKGROUND

Neonatal arterial ischemic stroke is a leading cause of cerebral palsy and lifelong disability. Diffusion-weighted imaging has revolutionized diagnosis and facilitated outcome prognostication in acute neonatal arterial ischemic stroke. Diaschisis refers to changes in brain areas functionally connected but structurally remote from primary injury. We hypothesized that acute diffusion-weighted imaging can quantify cerebral diaschisis and is associated with outcome from neonatal arterial ischemic stroke.

METHODS

Subjects were identified from a prospective, population-based research cohort (Alberta Perinatal Stroke Project). Inclusion criteria were unilateral middle cerebral artery neonatal arterial ischemic stroke, diffusion-weighted magnetic resonance imaging within 10 days of birth, and more than 12-months follow-up (pediatric stroke outcome measure). Diaschisis was characterized and quantified using a validated software method (ImageJ). Volumetric analysis assessed atrophy of affected structures. Diaschisis scores were corrected for infarct size and compared with outcomes (Mann-Whitney).

RESULTS

From 20 eligible neonatal arterial ischemic strokes, two were excluded for poor image quality. Of 18 remaining (61% male, median age 3.2 days), 16 (89%) demonstrated diaschisis. Thalamus (88%) was the most common location in addition to corpus callosum (50%). Age at imaging was not associated with diaschisis. Affected structures demonstrated atrophy on imaging. Long-term outcomes available in 81% (median age 7.5 years) were not associated with diaschisis scores.

CONCLUSIONS

Cerebral diaschisis occurs in neonatal arterial ischemic stroke and can be quantified with diffusion-weighted imaging. Occurrence is common and should not be mistaken for additional infarction. Determining clinical significance will require larger samples with well-characterized long-term outcomes.

Bedside neurophysiological tests can identify neonates with stroke leading to cerebral palsy

OBJECTIVE

The unspecific symptoms of neonatal stroke still challenge its bedside diagnosis. We studied the accuracy of routine electroencephalography (EEG) and simultaneously recorded somatosensory evoked potentials (EEG-SEP) for diagnosis and outcome prediction of neonatal stroke.

METHODS

We evaluated EEG and EEG-SEPs from a hospital cohort of 174 near-term neonates with suspected seizures or encephalopathy, 32 of whom were diagnosed with acute ischemic or hemorrhagic stroke in MRI. EEG was scored for background activity and seizures. SEPs were classified as present or absent. Developmental outcome of stroke survivors was evaluated from medical records at 8- to 18-months age.

RESULTS

The combination of continuous EEG and uni- or bilaterally absent SEP (n = 10) was exclusively seen in neonates with a middle cerebral artery (MCA) stroke (specificity 100%). Moreover, 80% of the neonates with this finding developed with cerebral palsy. Bilaterally present SEPs did not exclude stroke, but predicted favorable neuromotor outcome in stroke survivors (positive predictive value 95%).

CONCLUSIONS

Absent SEP combined with continuous EEG background in near-term neonates indicates an MCA stroke and a high risk for cerebral palsy.

SIGNIFICANCE

EEG-SEP offers a bedside method for diagnostic screening and a reliable prediction of neuromotor outcome in neonates suspected of having a stroke.

Epidemiology of neonatal stroke: A population-based study

Objective

The goal of this study was to obtain population-based data on the incidence, clinical presentation, management, imaging features, and long-term outcomes of patients with all types of neonatal stroke (NS).

Methods

Full-term neonates with NS born between January 2007 and December 2013 were identified through the Nova Scotia Provincial Perinatal Follow-up Program Database. Perinatal data and neonatal course were reviewed. Neurodevelopmental outcomes were assessed at 18 and 36 months of age using standardized testing.

Results

Twenty-nine neonates with NS were identified during the study period, giving an incidence of 47 per 100,000 live births in Nova Scotia. Arterial ischemic stroke was the most common stroke type (76%), followed by neonatal hemorrhagic stroke (17%), then cerebral sinovenous thrombosis (7%). The majority of neonates presented with seizures (86%) on the first day of life (76%). At 36 months of age, 23 (79%) of the children had a normal outcome, while 3 (10%) were diagnosed with cerebral palsy (2 with neonatal arterial stroke and one with neonatal hemorrhagic stroke) and 3 (10%) had recurrent seizures (1 patient from each stroke subtype group).

Conclusion

The incidence of NS in Nova Scotia is higher than what has been reported internationally in the literature. However, the neurodevelopmental outcomes at 3 years of age are better. Further studies are required to better understand the reasons for these findings.

Long-term neurodevelopmental outcome after perinatal arterial ischemic stroke and periventricular venous infarction

BACKGROUND

Long-term follow-up data after different vascular types of ischemic perinatal stroke is sparse. Our aim was to study neurodevelopmental outcomes following neonatal and presumed perinatal ischemic middle cerebral artery territory stroke (arterial ischemic stroke, AIS) and periventricular venous infarction (PVI).

METHODS

A prospective consecutive cohort of 40 term-born children with perinatal stroke (21 AIS, 19 PVI) was identified through the Estonian Paediatric Stroke Database. While 48% of the children with AIS were diagnosed during the neonatal period, all the children with PVI had presumed perinatal stroke. Outcomes based on the Paediatric Stroke Outcome Measure (PSOM) and Kaufman Assessment Battery for Children - Second Edition (K-ABC-II), in relation to extent and laterality of stroke, were defined.

RESULTS

At a median age of 7 years 6 months (range 3.6-13y), there was a trend towards worse neurodevelopmental outcome in participants with AIS when compared to PVI (mean total PSOM scores 3.1 and 2.2, respectively; p = 0.06). Combined deficits of motor, language and cognitive/behavioural functions were significantly more common among children with AIS (90%) when compared to children with PVI (53%, p = 0.007). General cognitive ability (by K-ABC-II) was significantly lower in the AIS subgroup (mean 79.6; 95% CI 72.3-87.0), but children with PVI (91.6; 95% CI 85.5-97.8) also had poorer performance than the age-equivalent normative mean. Large extent of stroke was associated with poorer neurodevelopmental outcome and lower cognitive performance in children following AIS but not in PVI.

CONCLUSION

In this national cohort, poor long-term neurodevelopmental outcome after perinatal ischemic stroke was seen irrespective of the vascular type or time of diagnosis of stroke. However, the spectrum of neurological deficits is different after perinatal AIS and PVI, with combined deficits more common among children following AIS.

Sex differences in the effects of PARP inhibition on microglial phenotypes following neonatal stroke

Neonatal acute ischemic stroke is a cause of neonatal brain injury that occurs more frequently in males, resulting in associated neurobehavioral disorders. The bases for these sex differences are poorly understood but might include the number, morphology and activation of microglia in the developing brain when subjected to stroke. Interestingly, poly (ADP-ribose) polymerase (PARP) inhibition preferentially protects males against neonatal ischemia. This study aims to examine the effects of PJ34, a PARP inhibitor, on microglial phenotypes at 3 and 8 days and on neurobehavioral disorders in adulthood for both male and female P9 mice subjected to permanent middle cerebral artery occlusion (pMCAo). PJ34 significantly reduced the lesion size by 78% and reduced the density of CX3CR1^gfp-labeled microglial cells by 46% when examined 3 days after pMCAo in male but not in female mice. Eight days after pMCAo, the number of Iba1⁺/Cox-2⁺ cells did not differ between male and female mice in the cortical peri-infarct region. In the amygdala, Iba1⁺/Cox-2⁺ (M1-like) cell numbers were significantly decreased in PJ34-treated males but not in females. Conversely, Iba1⁺/Arg-1⁺ (M2-like) and Arg-1⁺/Cox-2⁺ (Mtransitional) cell numbers were significantly increased in PJ34-treated females. Regarding neurobehavioral disorders during adulthood, pMCAo induced a motor coordination deficit and a spatial learning deficit in female mice only. PJ34 prevented MBP fibers, motor coordination and learning disorders during adulthood in female mice. Our data show significant sex differences in the effects of PARP inhibition on microglia phenotypes following neonatal ischemia, associated with improved behavior and myelination during adulthood in females only. Our findings suggest that modulating microglial phenotypes may play key roles in behavior disorders and white matter injury following neonatal stroke.

Neonatal stroke and haematuria: Questions

This is a report of an infant born near term with neonatal stroke and haematuria. Changes were noted on foetal magnetic resonance images, and these persisted postnatally. A routine renal ultrasound scan during follow-up detected haematuria with no associated proteinuria. A likely pathogenic genetic mutation was identified. This case highlights a relatively newly discovered cause for hereditary nephropathy affecting the basement membrane, initially affecting the glomerular but later the renal tubular basement membranes. The renal phenotype, pathogenic genotype and pathological findings on renal biopsy are discussed.

Epilepsy after perinatal stroke with different vascular subtypes

Objective

With an incidence up to 63 per 100,000 live births, perinatal stroke is an important cause of childhood epilepsy. The aim of the study was to find the prevalence of and predictive factors for epilepsy, and to describe the course of epilepsy in children with perinatal stroke with different vascular subtypes.

Methods

Patients were retrieved from the Estonian Paediatric Stroke Database with follow‐up time at least 24 months. Patients were divided into 5 perinatal stroke syndromes: neonatal arterial ischemic stroke (AIS), neonatal hemorrhagic stroke, neonatal cerebral sinovenous thrombosis, presumed AIS, and presumed periventricular venous infarction.

Results

The final study group included 73 children with perinatal stroke (39 boys). With a median follow‐up time of 8.6 years, epilepsy was diagnosed in 21/73 (29%) children, most of whom had AIS (17/21, 81%). The 18‐year cumulative poststroke epilepsy risk according to the Kaplan‐Meier estimator was 40.8% (95% confidence interval [CI] 20.7–55.9%). The median age at epilepsy diagnosis was 50 months (range 1 month to 18.4 years). Children with neonatal AIS had the highest risk of epilepsy, but children with presumed AIS more often had severe epilepsy syndromes. Cortical lesions (odds ratio [OR] 19.7, 95% CI 2.9–133), and involvement of thalamus (OR 9.8, 95% CI 1.8–53.5) and temporal lobe (OR 8.3, 95% CI 1.8–39.6) were independently associated with poststroke epilepsy.

Significance

The risk for poststroke epilepsy after perinatal stroke depends on the vascular subtype. Patients with perinatal AIS need close follow‐up to detect epilepsy and start with antiepileptic treatment on time.

Delayed erythropoietin therapy improves histological and behavioral outcomes after transient neonatal stroke

BACKGROUND AND PURPOSE

Stroke is a major cause of neonatal morbidity, often with delayed diagnosis and with no accepted therapeutic options. The purpose of this study is to investigate the efficacy of delayed initiation of multiple dose erythropoietin (EPO) therapy in improving histological and behavioral outcomes after early transient ischemic stroke.

METHODS

32 postnatal day 10 (P10) Sprague-Dawley rats underwent sham surgery or transient middle cerebral artery occlusion (tMCAO) for 3h, resulting in injury involving the striatum and parieto-temporal cortex. EPO (1000U/kg per dose×3 doses) or vehicle was administered intraperitoneally starting one week after tMCAO (at P17, P20, and P23). At four weeks after tMCAO, sensorimotor function was assessed in these four groups (6 vehicle-sham, 6 EPO-sham, 10 vehicle-tMCAO and 10 EPO-tMCAO) with forepaw preference in cylinder rearing trials. Brains were then harvested for hemispheric volume and Western blot analysis.

RESULTS

EPO-tMCAO animals had significant improvement in forepaw symmetry in cylinder rearing trials compared to vehicle-tMCAO animals, and did not differ from sham animals. There was also significant preservation of hemispheric brain volume in EPO-tMCAO compared to vehicle-tMCAO animals. No differences in ongoing cell death at P17 or P24 were noted by spectrin cleavage in either EPO-tMCAO or vehicle-tMCAO groups.

CONCLUSIONS

These results suggest that delayed EPO therapy improves both behavioral and histological outcomes at one month following transient neonatal stroke, and may provide a late treatment alternative for early brain injury.

Progesterone in the treatment of neonatal arterial ischemic stroke and acute seizures: Role of BDNF/TrkB signaling

Neonatal stroke is among the top ten causes of childhood death and permanent disability in survivors, but no safe and effective acute treatments exist. To advance understanding of its neuroprotective mechanisms, we examined the effects of progesterone (PROG) on local and systemic inflammation (IL-1β, IL-6, TNFα), brain derived neurotrophic factor/Tropomyosin receptor kinase B (BDNF/TrkB) signaling, vascular damage (vascular endothelial growth factor (VEGF), matrix metalloproteinase-9 (MMP-9)), acute behavioral seizures and brain infarction size following neonatal arterial ischemic stroke in mice. CD1 mouse pups (postnatal day 12, mixed gender) received permanent unilateral right common carotid ligation (pUCCL) or sham surgery. Pups showing seizure activity during the first hour post-pUCCL were randomly assigned to receive PROG (8 mg/kg) or vehicle injections. PROG treatment significantly (p < 0.05) reduced seizure occurrence by ∼44% compared to vehicle and attenuated the expression of pro-inflammatory cytokines in serum and brain at different time-points. PROG differentially regulated the expression of BDNF and TrkB and the activity of VEGF and MMP-9 over the 7d period. Permanent UCCL resulted in severe hemispheric damage measured at 7 days post-pUCCL but PROG treatment produced a significant (p < 0.05) reduction in infarct volume (∼70%) compared to vehicle. A gender-based comparison of data revealed significantly greater seizure activity in males compared to females. However, we did not observe significant sex differences on any other markers of the injury at this early stage of development. PROG treatment is neuroprotective through a number of signaling pathways and can be beneficial in treating neonatal arterial ischemic stroke in CD1 mice.

Prediction of visual field defects in newborn infants with perinatal arterial ischemic stroke using early MRI and DTI-based tractography of the optic radiation

PURPOSE

Visual field (VF) defects are common sequelae of perinatal arterial ischemic stroke (PAIS). The aim of this study was to investigate the predictive value of magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) for VF defects following PAIS.

METHODS

Nineteen infants with unilateral PAIS, who underwent conventional MRI (T1/T2) and DTI at three months of age and a VF examination later in life (median age 3.2 yrs) were included. Conventional T1-weighted MRI was used to assess asymmetry of the optic radiation (OR). DTI-based tractography of the bilateral OR was performed, and the average fractional anisotropy (FA), axial (λ1), radial (λ23) and mean diffusivity (MD) were extracted. Asymmetry of the OR on MRI and DTI was used as a predictor of VF defects using receiver operating characteristic (ROC) analysis.

RESULTS

Of the 19 infants, nine had a normal VF, eight had a VF defect (six hemianopia and two quadrantanopia), and two had an inconclusive VF test. The presence or absence of a VF defect could be correctly predicted using conventional MRI assessment in the majority of the infants, with an area under the curve (AUC) of 0.90 (95% CI 0.66-0.99). Prediction based on DTI parameter asymmetry indices showed an AUC of 0.96 (95% CI 0.74-1.00), 0.78 (95% CI 0.52-0.94), 0.93 (95% CI 0.70-1.00) and 0.90 (95% CI 0.66-0.99) for FA, λ1, λ23 and MD, respectively.

CONCLUSIONS

VF defects following PAIS can be reliably predicted by assessment of asymmetry of the OR at three months on conventional MRI and DTI-based tractography with comparable predictive values. Conventional T1-weighted MRI can be used in clinical practice.

Neuroprotective Effects of a PSD-95 Inhibitor in Neonatal Hypoxic-Ischemic Brain Injury

The postsynaptic density-95 inhibitor NA-1 uncouples NMDA glutamate receptors from downstream neurotoxic signaling pathways without affecting normal glutamate receptor function. NA-1 attenuates NMDA receptor-mediated neuronal cell death after stroke in multiple models and species. However, its efficacy in providing neuroprotection in models of neonatal hypoxic-ischemic brain injury has not yet been tested. In this study, a modified version of the Rice-Vannucci method for the induction of neonatal hypoxic-ischemic brain injury was performed on postnatal day 7 mouse pups. Animals received a single dose of NA-1 intraperitoneally either before or after right common carotid artery occlusion. All experiments were performed in a blinded manner. Infarct volumes were measured 1 and 7 days after the injury, while behavioral tests were conducted 1, 3, and 7 days after injury. Administration of NA-1 before right common carotid artery occlusion or immediately after ischemia significantly reduced infarct volume and improved neurobehavioral outcomes 1, 3, and 7 days post-injury. The neuroprotection and improvement in neurobehavioral outcomes conferred by NA-1 in this mouse neonatal hypoxic-ischemic injury model imply that NA-1 will be effective in reducing neonatal stroke damage and thus could potentially serve as a therapeutic drug for prevention or treatment of neonatal stroke.

Cannabinoid receptor 2 attenuates microglial accumulation and brain injury following germinal matrix hemorrhage via ERK dephosphorylation in vivo and in vitro

Microglia accumulation plays detrimental roles in the pathology of germinal matrix hemorrhage (GMH) in the immature preterm brain. However, the underlying mechanisms remain poorly defined. Here, we investigated the effects of a cannabinoid receptor 2 (CB2R) agonist on microglia proliferation and the possible involvement of the mitogen-activated protein kinase (MAPK) family pathway in a collagenase-induced GMH rat model and in thrombin-induced rat microglia cells. We demonstrated that activation of CB2R played a key role in attenuating brain edema, neuronal degeneration, microglial accumulation and the phosphorylated extracellular signal-regulated kinase (p-ERK) protein level 24 h following GMH. In vitro, Western blot analysis and immunostaining indicated that ERK and P38 phosphorylation levels in microglia stimulated by thrombin were decreased after JWH-133 (CB2R selective agonist) treatment in a concentration-dependent manner. Microglia proliferation (EDU + microglia) and inflammatory and oxidative stress responses were attenuated by UO126 (ERK pathway inhibitor) 24 h after thrombin stimulation, an activity that was prevented by AM630 (CB2R selective antagonist). Overall, these findings suggest that activation of the endocannabinoid system might attenuate inflammation-induced secondary brain injury after GMH in rats by reducing microglia accumulation through a mechanism involving ERK dephosphorylation. Enhancing CB2R activation is a potential treatment to slow down the course of GMH in preterm newborns.

BNIP3 interacting with LC3 triggers excessive mitophagy in delayed neuronal death in stroke

INTRODUCTION

A basal level of mitophagy is essential in mitochondrial quality control in physiological conditions, while excessive mitophagy contributes to cell death in a number of diseases including ischemic stroke. Signals regulating this process remain unknown. BNIP3, a pro-apoptotic BH3-only protein, has been implicated as a regulator of mitophagy.

AIMS

Both in vivo and in vitro models of stroke, as well as BNIP3 wild-type and knock out mice were used in this study.

RESULTS

We show that BNIP3 and its homologue BNIP3L (NIX) are highly expressed in a "delayed" manner and contribute to delayed neuronal loss following stroke. Deficiency in BNIP3 significantly decreases both neuronal mitophagy and apoptosis but increases nonselective autophagy following ischemic/hypoxic insults. The mitochondria-localized BNIP3 interacts with the autophagosome-localized LC3, suggesting that BNIP3, similar to NIX, functions as a LC3-binding receptor on mitochondria. Although NIX expression is upregulated when BNIP3 is silenced, up-regulation of NIX cannot functionally compensate for the loss of BNIP3 in activating excessive mitophagy.

CONCLUSIONS

NIX primarily regulates basal level of mitophagy in physiological conditions, whereas BNIP3 exclusively activates excessive mitophagy leading to cell death.

Delayed VEGF treatment enhances angiogenesis and recovery after neonatal focal rodent stroke

Neonatal stroke occurs in one in 4,000 live births and leads to significant morbidity and mortality. Approximately two thirds of the survivors have long-term sequelae including seizures and neurological deficits. However, the pathophysiological mechanisms of recovery after neonatal stroke are not clearly understood, and preventive measures and treatments are nonexistent in the clinical setting. In this study, we investigated the effect of vascular endothelial growth factor (VEGF) treatment on histological recovery and angiogenic response to the developing brain after an ischemic insult. Ten-day-old Sprague-Dawley rats underwent right middle cerebral arterial occlusion (MCAO) for 1.5 h. Diffusion-weighted MRI during occlusion confirmed focal ischemia that was then followed by reperfusion. On group of animals received 5-bromo-2-deoxyuridine and sacrificed at postnatal day (P)18 or P25. A second group of animals was treated with VEGF (1.5 µg/kg, icv) or phosphate-buffered saline (PBS) at P18 and perfusion fixed at P25. Based on Nissl and iron staining, a single VEGF injection reduced the injury score, compared to the animals that underwent MCAO and PBS injection. Furthermore, neurodegeneration represented by neuronal nuclei staining was markedly diminished. In addition, animals treated with VEGF revealed a positive trend in endothelial proliferation and a significant increase in total vessel volume in the peri-infarct region of the caudate. The number of Iba1-positive microglial cells was significantly reduced after a single VEGF injection, and myelin basic protein expression was enhanced in the caudate after ischemia without an effect of VEGF treatment. In conclusion, delayed treatment with VEGF ameliorates injury, promotes endothelial cell proliferation, and increases total vascular volume following neonatal stroke. These results suggest that VEGF has a neuroprotective effect, in part by enhancing endogenous angiogenesis. These data contribute to a better understanding of neonatal stroke.

Quality of life and functional outcome in early school-aged children after neonatal stroke: a prospective cohort study

BACKGROUND

Quality of life (QoL) is recognized internationally as an efficient tool for evaluating health interventions. To our knowledge, QoL has not been specifically assessed in children after neonatal arterial ischemic stroke (AIS).

AIM

To study the QoL of early school-aged children who suffered from neonatal AIS, and QoL correlation to functional outcome.

METHOD

We conducted a multicenter prospective cohort study as part of a larger study in full-term newborns with symptomatic AIS. Participating families were sent anonymous QoL questionnaires (QUALIN). Functional outcome was measured using the Wee-FIM scale. Healthy controls in the same age range were recruited in public schools. Their primary caregivers filled in the QUALIN questionnaires anonymously. We used Student's t-test and a rank test to compare patients and controls' QoL and functional outcomes.

RESULTS

84 children with neonatal AIS were included. The control group was composed of 74 children, of which ten were later excluded due to chronic conditions. Mean ages and QUALIN median scores did not differ between patients and controls. Median Wee-FIM scores were lower in hemiplegic children than in non-hemiplegic ones (p < 0.001). QoL scores did not seem correlated to functional outcome.

INTERPRETATION

Those results could support the presence of a "disability paradox" in young children following neonatal AIS.

Neonatal stroke: a review of the current evidence on epidemiology, pathogenesis, diagnostics and therapeutic options

Neonatal stroke, including perinatal arterial ischaemic stroke and cerebral sinovenous thrombosis, remains a serious problem in the neonate. This article reviews the current evidence on epidemiology, pathogenesis, diagnostics and therapeutic options.

CONCLUSION

Although our understanding of the underlying mechanisms and possible risk factors has improved, little progress has been made towards therapeutic options. Considering the high incidence of neurological sequelae, the need for therapeutic options is high and should be the focus of future research.