MR angiography findings in infants with neonatal arterial ischemic stroke in the middle cerebral artery territory: A prospective study using circle of Willis MR angiography

Arterial Ischemic Stroke in Children

Arterial ischemic stroke (AIS) in children has a high mortality and life-long disability rate in surviving patients. Diagnostic delays are longer and risk factors are different compared with AIS in the adult population. Congenital heart disease, cervical arterial dissection, and intracranial arteriopathies are the main causes of AIS in children. New revascularization time windows in children require the definition of diagnostic protocols for stroke in each referral center. In this article, we discuss the neuroimaging techniques and protocols, describe the main underlying causes, and review the current treatment options for pediatric and perinatal AIS.

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.

Early predictors of neurodevelopment after perinatal arterial ischemic stroke: a systematic review and meta-analysis

BACKGROUND AND AIMS

Perinatal arterial ischemic stroke (PAIS) often has lifelong neurodevelopmental consequences. We aimed to review early predictors (<4 months of age) of long-term outcome.

METHODS

We carried out a systematic literature search (PubMed and Embase), and included articles describing term-born infants with PAIS that underwent a diagnostic procedure within four months of age, and had any reported outcome parameter ≥12 months of age. Two independent reviewers included studies and performed risk of bias analysis.

RESULTS

We included 41 articles reporting on 1395 infants, whereof 1255 (90%) infants underwent follow-up at a median of 4 years. A meta-analysis was performed for the development of cerebral palsy (n = 23 studies); the best predictor was the qualitative or quantitative assessment of the corticospinal tracts on MRI, followed by standardized motor assessments. For long-term cognitive functioning, bedside techniques including (a)EEG and NIRS might be valuable. Injury to the optic radiation on DTI correctly predicted visual field defects. No predictors could be identified for behavior, language, and post-neonatal epilepsy.

CONCLUSION

Corticospinal tract assessment on MRI and standardized motor assessments are best to predict cerebral palsy after PAIS. Future research should be focused on improving outcome prediction for non-motor outcomes.

IMPACT

We present a systematic review of early predictors for various long-term outcome categories after perinatal arterial ischemic stroke (PAIS), including a meta-analysis for the outcome unilateral spastic cerebral palsy. Corticospinal tract assessment on MRI and standardized motor assessments are best to predict cerebral palsy after PAIS, while bedside techniques such as (a)EEG and NIRS might improve cognitive outcome prediction. Future research should be focused on improving outcome prediction for non-motor outcomes.

Neonatal Arterial Ischaemic Stroke: Advances in Pathologic Neural Death, Diagnosis, Treatment, and Prognosis

Neonatal arterial ischaemic stroke (NAIS) is caused by focal arterial occlusion and often leads to severe neurological sequelae. Neural deaths after NAIS mainly include necrosis, apoptosis, necroptosis, autophagy, ferroptosis, and pyroptosis. These neural deaths are mainly caused by upstream stimulations, including excitotoxicity, oxidative stress, inflammation, and death receptor pathways. The current clinical approaches to managing NAIS mainly focus on supportive treatments, including seizure control and anticoagulation. In recent years, research on the pathology, early diagnosis, and potential therapeutic targets of NAIS has progressed. In this review, we summarise the latest progress of research on the pathology, diagnosis, treatment, and prognosis of NAIS and highlight newly potential diagnostic and treatment approaches.

Perinatal Ischemic Stroke: Etiology and Imaging

Perinatal ischemic stroke is a common cause of lifelong disability.

Structural brain connectivity in children after neonatal stroke: A whole-brain fixel-based analysis

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Neonatal arterial ischemic stroke affects white matter distant from the lesion.

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Alterations are located ipsilesionally and in interhemispheric connections.

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Manual dexterity correlates with these structural impairments.

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The disseminated effects are therefore functionally relevant.

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Neonatal arterial ischemic stroke is a developmental network injury.

Introduction

Neonatal arterial ischemic stroke (NAIS) has been shown to affect white matter (WM) microstructure beyond the lesion. Here, we employed fixel-based analysis, a technique which allows to model and interpret WM alterations in complex arrangements such as crossing fibers, to further characterize the long-term effects of NAIS on the entire WM outside the primary infarct area.

Materials and methods

32 children (mean age 7.3 years (SD 0.4), 19 male) with middle cerebral artery NAIS (18 left hemisphere, 14 right hemisphere) and 31 healthy controls (mean age 7.7 years (SD 0.6), 16 male) underwent diffusion MRI scans and clinical examination for manual dexterity. Microstructural and macrostructural properties of the WM were investigated in a fixel-based whole-brain analysis, which allows to detect fiber-specific effects. Additionally, tract-averaged fixel metrics in interhemispheric tracts, and their correlation with manual dexterity, were examined.

Results

Significantly reduced microstructural properties were identified, located within the parietal and temporal WM of the affected hemisphere, as well as within their interhemispheric connecting tracts. Tract-averaged fixel metrics showed moderate, significant correlation with manual dexterity of the affected hand. No increased fixel metrics or contralesional alterations were observed.

Discussion

Our results show that NAIS leads to long-term alterations in WM microstructure distant from the lesion site, both within the parietal and temporal lobes as well as in their interhemispheric connections. The functional significance of these findings is demonstrated by the correlations with manual dexterity. The localization of alterations in structures highly connected to the lesioned areas shift our perception of NAIS from a focal towards a developmental network injury.

Expert consensus on the clinical practice of neonatal brain magnetic resonance imaging

In recent years, magnetic resonance imaging (MRI) has been widely used in evaluating neonatal brain development, diagnosing neonatal brain injury, and predicting neurodevelopmental prognosis. Based on current research evidence and clinical experience in China and overseas, the Neonatologist Society of Chinese Medical Doctor Association has developed a consensus on the indications and standardized clinical process of neonatal brain MRI. The consensus has the following main points. (1) Brain MRI should be performed for neonates suspected of hypoxic-ischemic encephalopathy, intracranial infection, stroke and unexplained convulsions; brain MRI is not considered a routine in the management of preterm infants, but it should be performed for further evaluation when cranial ultrasound finds evidence of brain injury; as for extremely preterm or extremely low birth weight infants without abnormal ultrasound findings, it is recommended that they should undergo MRI examination at term equivalent age once. (2) Neonates should undergo MRI examination in a non-sedated state if possible. (3) During MRI examination, vital signs should be closely monitored to ensure safety; the necessity of MRI examination should be strictly evaluated for critically ill neonates, and magnetic resonance compatible incubator and ventilator can be used. (4) At present, 1.5 T or 3.0 T equipment can be used for neonatal brain MRI examination, and the special coil for the neonatal head should be used to improve signal-to-noise ratio; routine neonatal brain MRI sequences should at least include axial T1 weighted image (T1WI), axial T2 weighted imaging (T2WI), diffusion-weighted imaging, and sagittal T1WI or T2WI. (5) It is recommended to use a structured and graded reporting system, and reports by at least two reviewers and multi-center collaboration are recommended to increase the reliability of the report.

MR Imaging Differences in the Circle of Willis between Healthy Children and Adults

BACKGROUND AND PURPOSE

Asymmetries in the circle of Willis have been associated with several conditions, including migraines and stroke, but they may also be age-dependent. This study examined the impact of age and age-dependent changes in cerebral perfusion on circle of Willis anatomy in healthy children and adults.

MATERIALS AND METHODS

We performed an observational, cross-sectional study of bright and black-blood imaging of the proximal cerebral vasculature using TOF-MRA and T2 sampling perfection with application-optimized contrasts by using different flip angle evolution (T2-SPACE) imaging at the level of the circle of Willis in 23 healthy children and 43 healthy adults (4-74 years of age). We compared arterial diameters measured manually and cerebral perfusion via pseudocontinuous arterial spin-labeling between children and adults.

RESULTS

We found that the summed cross-sectional area of the circle of Willis is larger in children than in adults, though the effect size was smaller with T2-SPACE-based measurements than with TOF-MRA. The circle of Willis is also more symmetric in children, and nonvisualized segments occur more frequently in adults than in children. Moreover, the size and symmetry of the circle of Willis correlate with cerebral perfusion.

CONCLUSIONS

Our results demonstrate that the circle of Willis is different in size and symmetry in healthy children compared with adults, likely associated with developmental changes in cerebral perfusion. Further work is needed to understand why asymmetric vasculature develops in some but not all adults.

How Does the Cause of Infantile Hemiparesis Influence Other Conditioning Factors? A Preliminary Study in a Spanish Population

Infantile hemiparesis may be associated with significant morbidity and may have a profound impact on a child’s physical and social development. Infantile hemiparesis is associated with motor dysfunction as well as additional neurologic impairments, including sensory loss, mental retardation, epilepsy, and vision, hearing, or speech impairments. The objective of this study was to analyze the association between the cause of infantile hemiparesis and birth (gestational age), age of diagnosis, and associated disorders present in children with infantile hemiparesis aged 0 to 3 years. An observational and cross-sectional study was performed. A simple and anonymous questionnaire was created ad hoc for parents of children diagnosed with infantile hemiparesis aged between 0 and 3 years about the situation regarding the diagnosis of hemiparesis, birth, cause of hemiparesis, and presence of other associated disorders. Perinatal stroke (60.1%) was the most common cause of hemiparesis, and the most typical associated disorder was epilepsy (34.2%), with the second largest percentage in this dimension corresponding to an absence of associated disorders (20.7%). The most frequent birth was “no premature” (74.1%). The mean age of diagnosis of infantile hemiparesis was registered at 8 months (IQR: 0–36). Knowing the possible association between different conditioning factors and the cause of infantile hemiparesis facilitates the prevention of severe sequelae in children and family, implementing an early comprehensive therapeutic approach in children with infantile hemiparesis.

Neuroimaging Perspectives of Perinatal Arterial Ischemic Stroke

Perinatal stroke ranks second only to that of adult stroke in the overall stroke incidence. It is a major contributor to long-term neurological morbidity, which includes cognitive dysfunction, cerebral palsy and seizures. Risk factors for stroke in the perinatal period differ from those in children and tend to be multifactorial. Differences in territorial predilection, response to injury, and stroke evolution exist when compared with childhood and adult stroke, and also among differing gestation age groups in the perinatal period (i.e., extreme preterm versus preterm versus term). The role of imaging is to diagnose stroke, exclude stroke mimics, establish the nature of stroke (arterial versus venous), and aid in prognostication. Magnetic resonance imaging is the mainstay of neuroimaging in perinatal stroke. Advanced imaging techniques such as diffusion tensor imaging and perfusion-weighted imaging are emerging as useful supplements to conventional imaging sequences. Here we describe the neuroimaging of perinatal arterial ischemic stroke with emphasis on imaging techniques, imaging phenotypes, stroke evolution, role of advanced imaging, and differences between stroke in preterm and term neonates. We also briefly describe the emerging role of fetal magnetic resonance imaging in the diagnosis of in utero stroke.

Perinatal Arterial Ischemic Stroke in Fetal Vascular Malperfusion: A Case Series and Literature Review

Fetal vascular malperfusion includes a continuum of placental histologic abnormalities increasingly associated with perinatal brain injury, namely arterial ischemic stroke. Here, we describe the clinical-neuroimaging features of 5 neonates with arterial ischemic stroke and histologically proved fetal vascular malperfusion. All infarcts involved the anterior territories and were multiple in 2 patients. In 2 neonates, there were additional signs of marked dural sinus congestion, thrombosis, or both. A mixed pattern of chronic hypoxic-ischemic encephalopathy and acute infarcts was noted in 1 patient at birth. Systemic cardiac or thrombotic complications were present in 2 patients. These peculiar clinical-radiologic patterns may suggest fetal vascular malperfusion and should raise the suspicion of this rare, underdiagnosed condition carrying important implications in patient management, medicolegal actions, and future pregnancy counseling.

Benefits of hypothermia in neonatal arterial ischemic strokes: A preclinical study

BACKGROUND

There is currently no targeted treatment available for neonatal arterial ischemic strokes (NAIS). Epidemiological studies demonstrated that perinatal infection/inflammation, peripartum hypoxia, and occlusion of the internal carotid tree are the main determinants of NAIS. The well-established benefit of therapeutic hypothermia (HT) in neonatal encephalopathy due to diffuse hypoxia-ischemia provides a rationale for the potential use of HT as a neuroprotective strategy in NAIS.

METHODS

We used a rat model to reproduce the most prevalent human physiopathological scenario of NAIS. The neuroprotective effect of HT was measured by morphometric magnetic resonance imaging, [¹⁸ F] fluorodeoxyglucose (FDG) metabolic activity by positron emission tomography/computed tomography, and behavioral tests.

RESULTS

HT (a) prevented the occurrence of 44% of NAIS, (b) reduced the volume of strokes by 37%, (c) enhanced [¹⁸ F] FDG metabolic activity within the territory of the occluded carotid artery, and (d) improved motor behavior. Both morphometric and metabolic techniques showed consistently that HT provided a neuroprotective effect located in the motor cortex, hippocampus, and caudate-putamen.

CONCLUSION

Through combining anatomical, metabolic imaging, and behavioral studies, our study provides evidence of neuroprotective effects of HT in NAIS. These results are potentially translational to human NAIS.

Perinatal Stroke

Perinatal strokes are a diverse but specific group of focal cerebrovascular injuries that occur early in brain development and affect an estimated 5 million people worldwide. The objective of this review is to describe the epidemiology, clinical presentations, pathophysiology, outcomes, and management for the 6 subtypes of perinatal stroke. Some perinatal strokes are symptomatic in the first days of life, typically with seizures, including neonatal arterial ischemic stroke, neonatal hemorrhagic stroke, and cerebral sinovenous thrombosis. The remaining subtypes present in the first year of life or later, usually with motor asymmetry and include arterial presumed perinatal ischemic stroke, presumed perinatal hemorrhagic stroke, and in utero periventricular venous infarction. The consequences of these injuries include cerebral palsy, epilepsy, and cognitive and behavioral challenges, in addition to the psychosocial impact on families. While there have been significant advances in understanding mechanisms of both injury and recovery, there is still a great deal to learn regarding causation and the optimization of outcomes.

Perinatal stroke syndromes: Similarities and diversities in aetiology, outcome and management

With a birth-prevalence of 37-67/100,000 (mostly term-born), perinatal stroke encompasses distinct disease-states with diverse causality, mechanism, time of onset, mode of presentation and outcome. Neonatal primary haemorrhagic stroke and ischemic events (also divided into neonatal arterial ischemic stroke and neonatal cerebral sinus venous thrombosis) that manifest soon after birth are distinguished from presumed perinatal - ischemic or haemorrhagic - stroke. Signs of the latter become apparent only beyond the neonatal period, most often with motor asymmetry or milestones delay, and occasionally with seizures. Acute or remote MRI defines the type of stroke and is useful for prognosis. Acute care relies on homeostatic maintenance. Seizures are often self-limited and anticonvulsant agents might be discontinued before discharge. Prolonged anticoagulation for a few weeks is an option in some cases of sinovenous thrombosis. Although the risk of severe impairment is low, many children develop mild to moderate multimodal developmental issues that require a multidisciplinary approach.

Perinatal arterial ischemic stroke

Perinatal arterial ischemic stroke is a relatively common and serious neurologic disorder that can affect the fetus, the preterm, and the term-born infant. It carries significant long-term disabilities. Herein we describe the current understanding of its etiology, pathophysiology and classification, different presentations, and optimal early management. We discuss the role of different brain imaging modalities in defining the extent of lesions and the impact this has on the prediction of outcomes. In recent years there has been progress in treatments, making early diagnosis and the understanding of likely morbidities imperative. An overview is given of the range of possible outcomes and optimal approaches to follow-up and support for the child and their family in the light of present knowledge.

A Model of Perinatal Ischemic Stroke in the Rat: 20 Years Already and What Lessons?

Neonatal hypoxia-ischemia (HI) and ischemia are a common cause of neonatal brain injury resulting in cerebral palsy with subsequent learning disabilities and epilepsy. Recent data suggest a higher incidence of focal ischemia-reperfusion located in the middle cerebral artery (MCA) territory in near-term and newborn babies. Pre-clinical studies in the field of cerebral palsy research used, and still today, the classical HI model in the P7 rat originally described by Rice et al. (1). At the end of the 90s, we designed a new model of focal ischemia in the P7 rat to explore the short and long-term pathophysiology of neonatal arterial ischemic stroke, particularly the phenomenon of reperfusion injury and its sequelae (reported in 1998). Cerebral blood-flow and cell death/damage correlates have been fully characterized. Pharmacologic manipulations have been applied to the model to test therapeutic targets. The model has proven useful for the study of seizure occurrence, a clinical hallmark for neonatal ischemia in babies. Main pre-clinical findings obtained within these 20 last years are discussed associated to clinical pattern of neonatal brain damage.

Perinatal stroke: mechanisms, management, and outcomes of early cerebrovascular brain injury

Perinatal stroke encompasses a heterogeneous group of focal neurological injuries early in brain development that probably affects more than 5 million people worldwide. Many such injuries are symptomatic in the first days of life, including neonatal arterial ischaemic stroke, cerebral sinovenous thrombosis, and neonatal haemorrhagic stroke. The remaining focal neurological injuries usually present later in the first year with motor asymmetry, such as arterial presumed perinatal ischaemic stroke, periventricular venous infarction, and presumed perinatal haemorrhagic stroke. The numerous sequelae of these injuries include hemiparesis (cerebral palsy), epilepsy, and cognitive, language, and behavioural challenges. In this Review we summarise each perinatal stroke disease, examining the epidemiology, pathophysiology, acute management, and outcomes, including the effect on parents and families, and emerging therapies to mitigate these lifelong morbidities.

Cytokine production pattern of T lymphocytes in neonatal arterial ischemic stroke during the first month of life-a case study

Background

The perinatal period carries the highest risk for stroke in childhood; however, the pathophysiology is poorly understood and preventive, prognostic, and therapeutic strategies are not available. A new pathophysiological model describes the development of neonatal arterial ischemic stroke (NAIS) as the combined result of prenatal inflammation and hypoxic–ischemic insult. Neuroinflammation and a systemic inflammatory response are also important features of NAIS. Identifying key players of the inflammatory system is in the limelight of current research.

Case presentation

We present four NAIS cases, in whom detailed analysis of intracellular and plasma cytokine levels are available from the first month of life. All neonates were admitted with the initial diagnosis of hypoxic ischemic encephalopathy (HIE); however, early MRI examination revealed NAIS. Blood samples were collected between 3 and 6 h of life, at 24 h, 72 h, 1 week, and 1 month of life. Peripheral blood mononuclear cells were assessed with flow cytometry and plasma cytokine levels were measured. Pooled data from the cohort of four NAIS patients were compared to infants with HIE.

At 6 and 72 h of age, the prevalence of IL10+ CD8+ lymphocytes remained lower in NAIS. At 6 h, CD8+ lymphocytes in NAIS produced more IL-17. At 72 h, CD8+ cells produced more IL-6 in severe HIE than in NAIS, but IL-6 production remained elevated in CD8 cells at 1 month in NAIS, while it decreased in HIE. At 1 week, the prevalence of TGF-β + lymphocytes prone to enter the CNS was elevated in NAIS. On the other hand, by 1 month of age, the prevalence of TGF-β + CD4+ lymphocytes decreased in NAIS compared to HIE. At 72 h, we found elevated plasma levels of IL-5, MCP-1, and IL-17 in NAIS. By 1 month, plasma levels of IL-4, IL-12, and IL-17 decreased in NAIS but remained elevated in HIE.

Conclusions

Differences in the cytokine network are present between NAIS and HIE. CD8 lymphocytes appear to shift towards the pro-inflammatory direction in NAIS. The inflammatory response appears to be more pronounced at 72 h in NAIS but decreases faster, reaching lower plasma levels of inflammatory markers at 1 month.

Predictors of short-term outcome in patients with acute middle cerebral artery occlusion: unsuitability of fluid-attenuated inversion recovery vascular hyperintensity scores

Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensity (FVH) is used to assess leptomeningeal collateral circulation, but clinical outcomes of patients with FVH can be very different. The aim of the present study was to assess a FVH score and explore its relationship with clinical outcomes. Patients with acute ischemic stroke due to middle cerebral artery M1 occlusion underwent magnetic resonance imaging and were followed up at 10 days (National Institutes of Health Stroke Scale) and 90 days (modified Rankin Scale) to determine short-term clinical outcomes. Effective collateral circulation indirectly improved recovery of neurological function and short-term clinical outcome by extending the size of the pial penumbra and reducing infarct lesions. FVH score showed no correlation with 90-day functional clinical outcome and was not sufficient as an independent predictor of short-term clinical outcome.

Role of Perinatal Inflammation in Neonatal Arterial Ischemic Stroke

Based on the review of the literature, perinatal inflammation often induced by infection is the only consistent independent risk factor of neonatal arterial ischemic stroke (NAIS). Preclinical studies show that acute inflammatory processes take place in placenta, cerebral arterial wall of NAIS-susceptible arteries and neonatal brain. A top research priority in NAIS is to further characterize the nature and spatiotemporal features of the inflammatory processes involved in multiple levels of the pathophysiology of NAIS, to adequately design randomized control trials using targeted anti-inflammatory vasculo- and neuroprotective agents.

Perinatal Arterial Ischemic Stroke Is Associated to Materno-Fetal Immune Activation and Intracranial Arteritis

The medium-size intra-cranial arteries arising from the carotid bifurcation are prone to perinatal arterial ischemic strokes (PAIS). PAIS’ physiopathology needs to be better understood to develop preventive and therapeutic interventions that are currently missing. We hypothesized that materno-fetal inflammation leads to a vasculitis affecting selectively the carotidian tree and promoting a focal thrombosis and subsequent stroke. Dams were injected with saline or lipopolysaccharide (LPS) from Escherichia coli. A prothrombotic stress was applied on LPS-exposed vs. saline (S)-exposed middle cerebral arteries (MCA). Immunolabeling detected the inflammatory markers of interest. In S-exposed newborn pups, a constitutive higher density of macrophages combined to higher expressions of tumor necrosis factor-α (TNF-α), and interleukin 1β (IL-1β) was observed within the wall of intra- vs. extra-cranial cervicocephalic arteries. LPS-induced maternal and placental inflammatory responses mediated by IL-1β, TNF-α and monocyte chemotactic protein 1 (MCP-1) were associated with: (i) increased density of pro-inflammatory macrophages (M1 phenotype); and (ii) pro-inflammatory orientation of the IL-1 system (IL-1β/IL-1 receptor antagonist (IL-1Ra) ratio) within the wall of LPS-, vs. S-exposed, intra-cranial arteries susceptible to PAIS. LPS plus photothrombosis, but not sole photothrombosis, triggered ischemic strokes and subsequent motor impairments. Based on these preclinical results, the combination of pro-thrombotic stress and selective intra-cranial arteritis arising from end gestational maternal immune activation seem to play a role in the pathophysiology of human PAIS.