Inflammatory Biomarkers in Childhood Arterial Ischemic Stroke: Correlates of Stroke Cause and Recurrence

Steno-occlusive Intracranial Large Vessel Arteriopathies in Childhood: A Pattern Oriented Approach to Neuroimaging Diagnosis

Intracranial steno-occlusive large vessel arteriopathies refer to abnormalities of the arterial wall that typically express luminal stenosis. Notably, some entities that can find themselves within this category may also express luminal dilation, and/or aneurysm formation as an alternative phenotype. Intracranial steno-occlusive large vessel arteriopathies are a leading cause of arterial ischemic stroke (AIS) in children, often progress, and can predispose to recurrent brain infarction. Intracranial arterial dissections account for a subset of cases expressing the focal cerebral arteriopathy (FCA) phenotype because the affected arterial segment, clinical presentation, and AIS patterns are very similar to the inflammatory subtype of FCA.

Mechanical Thrombectomy for Pediatric Stroke: Focal Cerebral Arteriopathy Versus Cardioembolic Etiologies-Pooled Analysis of the Save ChildS and KidClot Cohort

BACKGROUND

The study aimed to compare outcomes of mechanical thrombectomy (MT) in pediatric patients with acute ischemic stroke (AIS) caused by focal cerebral arteriopathy (FCA) versus cardioembolism (CE).

METHODS

Data from the Save ChildS and KidClot cohorts were merged. Children with AIS because of FCA or CE that underwent MT were included. The study used the Childhood Arterial Ischemic Stroke Standardized Classification and Diagnostic Evaluation (CASCADE) for stroke cause assessment. Descriptive statistics and multivariable regression models were used to analyze final modified thrombolysis in cerebral infarction (mTICI) scores, periprocedural complications, and functional outcomes assessed by the modified Rankin scale (mRS) at 6 to 12 months.

RESULTS

The analysis included 60 children with 14 FCA and 46 CE cases. CE etiology was associated with better revascularization (good to excellent thrombolysis in cerebral infarction scores) and shift toward better outcomes (common adjusted odds ratio of mRs for CE vs FCA: 0.27, 95% CI: [0.06-0.97], p = 0.039), with no difference in favorable outcome rates. FCA was associated with significantly lower rates of excellent revascularization (21% vs 65%, p < 0.001). No difference in complications' rates was observed between the groups (7.2% in FCA vs 5.5%, p = 0.69).

INTERPRETATION

We found that pediatric AIS because of CE etiology has more favorable procedural outcomes compared to FCA following MT. This translated to mixed functional outcomes that may be more favorable in the CE group. These findings highlight the need for further research to refine treatment protocols for pediatric stroke, particularly in understanding and managing FCA in children. ANN NEUROL 2024.

IL-6 and stroke recurrence in ischemic stroke

Objective: This study aimed to evaluate the predictive value of IL-6 for stroke recurrence in acute ischemic stroke.Methods: Patients who were admitted within 48 h of onset were included. At 3-month, stroke recurrence was assessed. IL-6 levels were measured in serum samples taken upon admission.Results: Out of the 305 patients, 47 (15.4%) experienced a stroke recurrence. The risk of stroke recurrence increased by 8% (OR: 1.08; 95% CI: 1.04-1.11; p < 0.001) for every 1 pg/ml increase in IL-6 serum level, both in unadjusted and adjusted analyses (6%; OR: 1.06; 95% CI: 1.02-1.10; p = 0.001).Conclusion: The study supports the usefulness of IL-6 as a predictive biomarker for stroke recurrence after acute ischemic stroke.

Stroke recurrence and osteoporotic conditions in postmenopausal patients with atherosclerotic ischemic stroke

Recurrence after stroke is common, and associated with a high mortality rate. Degradation of the elastic tissue in the arterial wall has been shown to aggravate atherosclerosis in blood vessels. Considering that type 1 collagen is present in both bone and vascular smooth muscle cells, we explored whether osteoporotic conditions affect the likelihood of stroke recurrence in postmenopausal women following atherosclerotic ischemic stroke. To determine actual bone mineral density (BMD), the Hounsfield unit values in the frontal skull were evaluated using brain computed tomography (CT) scans taken at admission. A multivariate Cox regression analysis was also performed to examine if osteoporosis could independently predict stroke recurrence in postmenopausal patients with large artery atherosclerosis (LAA) or small vessel occlusion (SVO) stroke. This study included 2130 consecutive patients (both males and females aged 50 and older) with acute LAA or SVO strokes. After adjusting for all covariates, hypothetical osteoporosis was identified as an independent predictor of stroke recurrence in female patients ≥50 years with acute LAA or SVO stroke (hazard ratio, 1.84; 95 % confidence interval, 1.05 to 3.24; p = 0.034). Our findings showed that osteoporosis could potentially affect the recurrence of ischemic stroke in postmenopausal patients with LAA or SVO stroke.

Serum amyloid A-dependent inflammasome activation and acute injury in a mouse model of experimental stroke

Serum amyloid A (SAA) proteins increase dramatically in the blood following inflammation. Recently, SAAs are increased in humans following stroke and in ischemic animal models. However, the impact of SAAs on whether this signal is critical in the ischemic brain remains unknown. Therefore, we investigated the role of SAA and SAA signaling in the ischemic brain. Wildtype and SAA deficient mice were exposed to middle cerebral artery occlusion and reperfusion, examined for the impact of infarct volumes, behavioral changes, inflammatory markers, TUNEL staining, and BBB changes. The underlying mechanisms were investigated using SAA deficient mice, transgenic mice and viral vectors. SAA levels were significantly increase following MCAo and mice deficient in SAAs showed reduced infarct volumes and improved behavioral outcomes. SAA deficient mice showed a reduction in TUNEL staining, inflammation and decreased glial activation. Mice lacking acute phase SAAs demonstrated a reduction in expression of the NLRP3 inflammasome and SAA/NLRP3 KO mice showed improvement. Restoration of SAA expression via SAA tg mice or adenoviral expression reestablished the detrimental effects of SAA. A reduction in BBB permeability was seen in the SAA KO mice and anti-SAA antibody treatment reduced the effects on ischemic injury. SAA signaling plays a critical role in regulating NLRP3-induced inflammation and glial activation in the ischemic brain. Blocking this signal will be a promising approach for treating ischemic stroke.

Thrombotic complications in children with Coronavirus disease 2019 and Multisystem Inflammatory Syndrome of Childhood

Coronavirus disease 2019 (COVID-19) associated coagulopathy is multifactorial and involves inflammation driven hypercoagulability, endothelial dysfunction, platelet activation, and impaired fibrinolysis. Hospitalized adults with COVID-19 are at an increased risk of both venous thromboembolism and ischemic stroke, resulting in adverse outcomes, including increased mortality. Although COVID-19 in children follows a less severe course, both arterial and venous thromboses have been reported in hospitalized children with COVID-19. Additionally, some children develop a postinfectious, hyperinflammatory illness termed multisystem inflammatory syndrome of childhood (MIS-C), which is also associated with hypercoagulability and thrombosis. Several randomized trials have evaluated the safety and efficacy of antithrombotic therapy in adults with COVID-19, although similar pediatric data are lacking. In this narrative review, we discuss the postulated pathophysiology of COVID-19 coagulopathy and summarize principal findings of the recently completed adult trials of antithrombotic therapy. We provide an up-to-date summary of pediatric studies investigating the rate of venous thromboembolism and ischemic stroke in COVID-19 and multisystem inflammatory syndrome of childhood in addition to reviewing the findings of the single, nonrandomized pediatric trial investigating the safety of prophylactic anticoagulation. Lastly, we outline adult and pediatric consensus guidelines on the use of antithrombotic therapy in this cohort. A detailed discussion of the practical implementation and current limitations of published data will hopefully address the knowledge deficits surrounding the use of antithrombotic therapy in children with COVID-19 and generate hypotheses for future research.

Pediatric Ischemic Stroke

OBJECTIVE

Pediatric cerebrovascular disease is one of the leading causes of death and disability in children. Survivors of childhood stroke and their families are often left to cope with long-lasting sequelae, such as barriers to school reentry and long-term challenges in attaining independence as adults. Because childhood stroke is rare and providers may not be familiar with the disorder, this article reviews the risk factors, acute management, and sequelae of ischemic stroke in children.

LATEST DEVELOPMENTS

High-quality evidence has resulted in an organized approach to emergent treatment of ischemic stroke in adults, but most front-line providers are less prepared for emergent stroke management in children. The level of evidence for reperfusion therapies in children remains low but is growing. Thrombolysis and thrombectomy are sometimes considered for hyperacute treatment of stroke in children. Readiness for pediatric stroke at regional centers should include an organized approach to pediatric stroke triage and management based on extrapolation from adult stroke trials, expert consensus, and emerging pediatric studies.

ESSENTIAL POINTS

This review provides up-to-date information about ischemic stroke risk factors and management in children. Preparation for rapid stroke diagnosis and management in children may improve outcomes.

Pediatric Stroke-Are We Asking the Right Questions? The 2022 Sidney Carter Award Lecture

Over the past few decades, robust clinical and research collaborations among pediatric stroke researchers have informed and improved the care of children with stroke. Risk factors and presentation of childhood stroke have been described, and the acute and chronic burden of childhood stroke has been better delineated. Nevertheless, high-quality data for the treatment of children with stroke is dwarfed by that available for adult stroke, and it is therefore tempting to extend research questions and treatment trials from adults to children. A trial designed to answer a question about stroke in adults may yield useful information about stroke in childhood, but a trial that incorporates the unique neurodevelopmental and etiologic aspects of childhood stroke is more likely to truly advance care. Research questions and study design in childhood stroke must capture the complexity of stroke mechanisms and medical comorbidities in children who suffer stroke, the impact on the developing nervous system, and the role of normal and aberrant neurodevelopment in recovery.

Association between myeloperoxidase and the risks of ischemic stroke, heart failure, and atrial fibrillation: A Mendelian randomization study

BACKGROUND AND AIMS

The causality between myeloperoxidase (MPO) and cardiovascular disease still remains unclear. We performed a two-sample Mendelian randomization (MR) study to estimate the potential causal effect of MPO on the risks of ischemic stroke, ischemic stroke subtypes, heart failure (HF), and atrial fibrillation (AF).

METHODS AND RESULTS

Seventeen independent single-nucleotide polymorphisms associated with MPO levels were identified as instrumental variables from a European-descent genome-wide association study. Summary-level data on ischemic stroke originated from the Multiancestry Genome-wide Association Study of Stroke Consortium with 440 328 European individuals. We used the inverse-variance weighted method to assess the potential causality of plasma MPO with ischemic stroke and its subtypes in the main analysis. Genetically determined higher plasma MPO concentration was significantly associated with increased risks of ischemic stroke (odds ratio [OR] per standard deviation [SD] increase, 1.05; 95% confidence interval [CI], 1.02-1.09; P = 0.002) and cardioembolic stroke (CES) (OR per SD increase, 1.10; 95% CI, 1.03-1.18; P = 0.005), but was not associated with risks of large artery stroke or small vessel stroke. In the secondary analysis, MPO was associated with a high risk of HF (OR per SD increase, 1.05; 95% CI, 1.02-1.07; P = 0.001) and AF (OR per SD increase, 1.04; 95% CI, 1.01-1.07; P = 0.004). MR-Egger regression showed no directional pleiotropy for all associations, and the sensitivity analyses further confirmed these findings.

CONCLUSION

High plasma MPO levels were potentially associated with increased risks of ischemic stroke, CES, HF, and AF, suggesting that MPO plays an important role in the development of cardiovascular disease.

Cerebral Arteriopathies of Childhood - Current Approaches

Up to more than half of previously healthy children presenting with their first arterial ischemic stroke have a cerebral arteriopathy. Cerebral arteriopathies during childhood can be congenital, reflecting abnormal vessel development, or acquired when caused by disruption of vascular homeostasis. Distinguishing different types of cerebral arteriopathies in children can be challenging but of great clinical value as they may dictate different disease and treatment courses, and clinical and radiologic outcomes. Furthermore, children with stroke due to a specific arteriopathy exhibit distinctive features when compared to those with stroke due to other causes or a different type of arteriopathy. These features become crucial in the management of pediatric stroke by choosing appropriate diagnostic and treatment strategies. The objective of this article is to provide the reader with a comprehensive up-to-date review of the classification, symptoms, diagnosis, treatment, and outcome of cerebral arteriopathies in children.

Viral mimetic triggers cerebral arteriopathy in juvenile brain via neutrophil elastase and NETosis

Stroke is among the top ten causes of death in children but has received disproportionally little attention. Cerebral arteriopathies account for up to 80% of childhood arterial ischemic stroke (CAIS) cases and are strongly predictive of CAIS recurrence and poorer outcomes. The underlying mechanisms of sensitization of neurovasculature by viral infection are undefined. In the first age-appropriate model for childhood arteriopathy-by administration of viral mimetic TLR3-agonist Polyinosinic:polycytidylic acid (Poly-IC) in juvenile mice-we identified a key role of the TLR3-neutrophil axis in disrupting the structural-functional integrity of the blood-brain barrier (BBB) and distorting the developing neurovascular architecture and vascular networks. First, using an array of in-vivo/post-vivo vascular imaging, genetic, enzymatic and pharmacological approaches, we report marked Poly-IC-mediated extravascular leakage of albumin (66kDa) and of a small molecule DiI (∼934Da) and disrupted tight junctions. Poly-IC also enhanced the neuroinflammatory milieu, promoted neutrophil recruitment, profoundly upregulated neutrophil elastase (NE), and induced neutrophil extracellular trap formation (NETosis). Finally, we show that functional BBB disturbances, NETosis and neuroinflammation are markedly attenuated by pharmacological inhibition of NE (Sivelestat). Altogether, these data reveal NE/NETosis as a novel therapeutic target for viral-induced cerebral arteriopathies in children.

Microglia-leucocyte axis in cerebral ischaemia and inflammation in the developing brain

Development of the Central Nervous System (CNS) is reliant on the proper function of numerous intricately orchestrated mechanisms that mature independently, including constant communication between the CNS and the peripheral immune system. This review summarizes experimental knowledge of how cerebral ischaemia in infants and children alters physiological communication between leucocytes, brain immune cells, microglia and the neurovascular unit (NVU)-the "microglia-leucocyte axis"-and contributes to acute and long-term brain injury. We outline physiological development of CNS barriers in relation to microglial and leucocyte maturation and the plethora of mechanisms by which microglia and peripheral leucocytes communicate during postnatal period, including receptor-mediated and intracellular inflammatory signalling, lipids, soluble factors and extracellular vesicles. We focus on the "microglia-leucocyte axis" in rodent models of most common ischaemic brain diseases in the at-term infants, hypoxic-ischaemic encephalopathy (HIE) and focal arterial stroke and discuss commonalities and distinctions of immune-neurovascular mechanisms in neonatal and childhood stroke compared to stroke in adults. Given that hypoxic and ischaemic brain damage involve Toll-like receptor (TLR) activation, we discuss the modulatory role of viral and bacterial TLR2/3/4-mediated infection in HIE, perinatal and childhood stroke. Furthermore, we provide perspective of the dynamics and contribution of the axis in cerebral ischaemia depending on the CNS maturational stage at the time of insult, and modulation independently and in consort by individual axis components and in a sex dependent ways. Improved understanding on how to modify crosstalk between microglia and leucocytes will aid in developing age-appropriate therapies for infants and children who suffered cerebral ischaemia.

The Role of Biomarkers in Atherothrombotic Stroke-A Systematic Review

Stroke represents the primary debilitating disease in adults and is the second-highest cause of death worldwide. Atherosclerosis, the most prevalent etiology for vascular conditions, is a continuous process that gradually creates and develops endothelial lesions known as atherosclerotic plaques. These lesions lead to the appearance of atherothrombotic stroke. In the last decades, the role of biological biomarkers has emerged as either diagnostic, prognostic, or therapeutic targets. This article aims to create a list of potential biomarkers related to atherothrombotic stroke by reviewing the currently available literature. We identified 23 biomarkers and assessed their roles as risk factors, detection markers, prognostic predictors, and therapeutic targets. The central aspect of these biomarkers is related to risk stratification, especially for patients who have not yet suffered a stroke. Other valuable data are focused on the predictive capabilities for stroke patients regarding short-term and long-term prognosis, including their influence over the acute phase treatment, such as rt-PA thrombolysis. Although the role of biomarkers is anticipated to be of extreme value in the future, they cannot yet compete with traditional stroke neuroimaging markers but could be used as additional tools for etiological diagnosis.

Focal Cerebral Arteriopathy of Childhood: Clinical and Imaging Correlates

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Pediatric Ischemic Stroke: An Infrequent Complication of SARS-CoV-2

OBJECTIVE

Severe complications of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) include arterial ischemic stroke (AIS) in adults and multisystem inflammatory syndrome in children. Whether stroke is a frequent complication of pediatric SARS-CoV-2 is unknown. This study aimed to determine the proportion of pediatric SARS-CoV-2 cases with ischemic stroke and the proportion of incident pediatric strokes with SARS-CoV-2 in the first 3 months of the pandemic in an international cohort.

METHODS

We surveyed 61 international sites with pediatric stroke expertise. Survey questions included: numbers of hospitalized pediatric (≤ 18 years) patients with SARS-CoV-2; numbers of incident neonatal and childhood ischemic strokes; frequency of SARS-CoV-2 testing for pediatric patients with stroke; and numbers of stroke cases positive for SARS-CoV-2 from March 1 to May 31, 2020.

RESULTS

Of 42 centers with SARS-CoV-2 hospitalization numbers, 8 of 971 (0.82%) pediatric patients with SARS-CoV-2 had ischemic strokes. Proportions of stroke cases positive for SARS-CoV-2 from March to May 2020 were: 1 of 108 with neonatal AIS (0.9%), 0 of 33 with neonatal cerebral sinovenous thrombosis (CSVT; 0%), 6 of 166 with childhood AIS (3.6%), and 1 of 54 with childhood CSVT (1.9%). However, only 30.5% of neonates and 60% of children with strokes were tested for SARS-CoV-2. Therefore, these proportions represent 2.9, 0, 6.1, and 3.0% of stroke cases tested for SARS-CoV-2. Seven of 8 patients with SARS-CoV-2 had additional established stroke risk factors.

INTERPRETATION

As in adults, pediatric stroke is an infrequent complication of SARS-CoV-2, and SARS-CoV-2 was detected in only 4.6% of pediatric patients with ischemic stroke tested for the virus. However, < 50% of strokes were tested. To understand the role of SARS-CoV-2 in pediatric stroke better, SARS-CoV-2 testing should be considered in pediatric patients with stroke as the pandemic continues. ANN NEUROL 2021;89:657-665.

Validation of the focal cerebral arteriopathy severity score (FCASS) in a Swiss cohort: Correlation with infarct volume and outcome

BACKGROUND

Focal cerebral arteriopathy (FCA), a major cause of childhood arterial ischemic stroke (AIS), can progress and lead to increased infarct size and/or recurrent stroke. Evaluating treatment options depends on the ability to quantify reliably the degree of stenosis in FCA.

AIMS

We validated the recently introduced FCA severity score (FCASS) in an independent cohort from the Swiss Neuro-Paediatric Stroke Registry (SNPSR).

MATERIALS AND METHODS

We included children with FCA who had MR or CT angiography and a Pediatric Stroke Outcome Measure (PSOM) at 6-months and 2-years post-stroke. A paediatric neuroradiologist applied the FCASS and the modified pediatric Alberta Stroke Program Early Computed Tomography Score (ASPECTS), a measure of infarct volume, to all available imaging. Two senior paediatric stroke neurologists and a neuroradiology fellow independently assigned FCASS scores to test interrater reliability. Pairwise correlations between FCASS, pedASPECTS, and PSOM were examined.

RESULTS

Thirty-two children [median (IQR) age = 5.9 (1.8, 9.6), 19 males] were included. The median maximum FCASS score at any time was 9 (IQR 6, 12; range 3, 16). Larger infarct volume scores correlated with both higher maximum FCASS scores and worse post-stroke outcomes, although we found no direct correlation between FCASS and outcomes. Stroke neurologists tended to assign lower FCASS scores than the neuroradiologist, but interrater reliability was predominantly good.

CONCLUSIONS

In this independent validation cohort, higher maximum FCASS correlated with greater infarct volume scores that also correlated with worse neurological outcomes. Scoring by non-imaging specialists seems to be valuable, although differences are present.

Cerebrovascular Complications of Pediatric Blunt Trauma

Ischemic and hemorrhagic stroke can occur in the setting of pediatric trauma, particularly those with head or neck injuries. The risk of stroke appears highest within the first two weeks after trauma. Stroke diagnosis may be challenging due to lack of awareness or concurrent injuries limiting detailed neurological assessment. Other injuries may also complicate stroke management, with competing priorities for blood pressure, ventilator management, or antithrombotic timing. Here we review epidemiology, clinical presentation, and diagnostic approach to blunt arterial injuries including dissection, cerebral sinovenous thrombosis, mineralizing angiopathy, stroke from abusive head trauma, and traumatic hemorrhagic stroke. Owing to the complexities and heterogeneity of concomitant injuries in stroke related to trauma, a single pathway for stroke management is impractical. Therefore providers must understand the goals and possible costs or consequences of stroke management decisions to individualize patient care. We discuss the physiological principles of cerebral perfusion and oxygen delivery, considerations for ventilator strategy when stroke and lung injury are present, and current available evidence of the risks and benefits of anticoagulation to provide a framework for multidisciplinary discussions of cerebrovascular injury management in pediatric patients with trauma.

Risk Factors for Recurrent Arterial Ischemic Stroke in Children and Young Adults

Arterial ischemic stroke (AIS) experienced at a young age is undoubtedly a serious medical problem. AIS very rarely occurs at a developmental age, whereas in young adults, it occurs with a higher frequency. The etiologic mechanisms of AIS occurring in childhood and adulthood differ. However, for both age populations, neurological consequences of AIS, including post-stroke seizures, motor disability, and recurrence of the disease, are connected to many years of care, rehabilitation, and treatment. Recurrent stroke was observed to increase the risk of patients' mortality. One of the confirmed risk factors for recurrent stroke in children is the presence of vasculopathies, especially Moyamoya disease and syndrome, and focal cerebral arteriopathy of childhood (FCA). FCA causes a 5-fold increase in the risk of recurrent stroke in comparison with idiopathic AIS. In turn, young adults with recurrent stroke were found to more often suffer from hypertension, diabetes mellitus, or peripheral artery disease than young patients with first-ever stroke. Some reports also indicate relationships between specific genetic polymorphisms and AIS recurrence in both age groups. The aim of the present literature review was to discuss available data regarding the risk factors for recurrent AIS in children and young adults.

Chitinase-3-Like Protein 1, Serum Amyloid A1, C-Reactive Protein, and Procalcitonin Are Promising Biomarkers for Intracranial Severity Assessment of Traumatic Brain Injury: Relationship with Glasgow Coma Scale and Computed Tomography Volumetry

OBJECTIVE

The volume and location of intracranial hematomas are well-known prognostic factors for traumatic brain injury. The aim of this study was to determine the relationship of serum biomarkers S100β, glial fibrillary acidic protein, neuron-specific enolase, total tau, phosphorylated neurofilament heavy chain, serum amyloid A1 (SAA1), C-reactive protein, procalcitonin (PCT), and chitinase-3-like protein 1 (YKL-40) with traumatic brain injury severity and the amount and location of hemorrhagic traumatic lesions.

METHODS

A prospective observational cohort of 115 patients with a Glasgow Coma Scale (GCS) score of 3-15 were evaluated. Intracranial lesion volume was measured from the semiautomatic segmentation of hematoma on computed tomography using Analyze software. The establishment of possible biomarker cutoff points for intracranial lesion detection was estimated using the Youden Index (J) obtained from the area under the receiver operating characteristic curve.

RESULTS

SAA1, YKL-40, PCT, and S100β showed the most robust association with level of consciousness, both with total GCS and motor score. Biomarkers significantly correlated with volumetric measurements of subdural hematoma, traumatic subarachnoid hemorrhage, intraparenchymal hemorrhage, intraventricular hemorrhage, and total amount of bleeding. The type of intracranial hemorrhage was associated with various release patterns of neurobiochemical markers.

CONCLUSIONS

YKL-40, SAA1, C-reactive protein, and PCT combined with S100β were the most promising biomarkers to determine the presence, location, and extent of traumatic intracranial lesions. Combination of biomarkers further increased the discriminatory capacity for the detection of intracranial bleeding.

CX3CR1-CCR2-dependent monocyte-microglial signaling modulates neurovascular leakage and acute injury in a mouse model of childhood stroke

Stroke is among the top 10 causes of death in children. The developmental stage of the brain is central to stroke pathophysiology. The incidence of childhood arterial ischemic stroke (CAIS) is lower than of perinatal arterial ischemic stroke but the rate of recurrence is strikingly high. Vascular inflammation is seen as major contributor to CAIS but the mechanisms that govern structural-functional basis of vascular abnormalities remain poorly understood. To identify the contribution of immune-neurovascular interactions to CAIS, we established stroke model in postnatal day 21 (P21) mice. We demonstrate acute functional deficits and histological injury and chronic MRI-identifiable injury, brain atrophy and marked derangements in the vascular network. In contrast to negligible albumin leakage and neutrophil infiltration following acute perinatal stroke, CAIS leads to significantly increased albumin leakage and neutrophil infiltration in injured regions of wild type mice and mice with functional CX3CR1-CCR2 receptors. In mice with dysfunctional CX3CR1-CCR2 signaling, extravascular albumin leakage is significantly attenuated, infiltration of injurious Ccr2⁺-monocytes essentially aborted, accumulation of Ly6G+ neutrophils reduced and acute injury attenuated. Unique identifiers of microglia and monocytes revealed phenotypic changes in each cell subtype of the monocyte lineage after CAIS. Taken together, CX3CR1-CCR2-dependent microglia-monocyte signaling contributes to cerebrovascular leakage, inflammation and CAIS injury.

Focal Cerebral Arteriopathy of Childhood: Novel Severity Score and Natural History

Background and Purpose- Focal cerebral arteriopathy (FCA)-a common cause of arterial ischemic stroke in previously healthy children-often progresses over days to weeks, increasing the risk of recurrent stroke. We developed a novel severity scoring system designed to quantify FCA progression and correlate with clinical outcomes. Methods- The VIPS study (Vascular Effects of Infection in Pediatric Stroke) prospectively enrolled 355 children with arterial ischemic stroke (2010-2014), including 41 with centrally confirmed FCA. Two neuroradiologists independently reviewed FCA cerebrovascular imaging, assigning a graded severity score of zero (no involvement) to 4 (occlusion) to individual arterial segments. The FCA severity score (FCASS) was the unweighted sum. In an iterative process, we modeled scores derived from different combinations of arterial segments to identify the model that optimized correlation with clinical outcome, simplicity, and reliability. Results- The optimal FCASS summed scores from 5 arterial segments: supraclinoid internal carotid artery, A1, A2, M1, and M2. The median (interquartile range) baseline FCASS was 4 (2-6). Of 33 children with follow-up imaging, the maximum FCASS (at any time point) was 7 (5-9). Twenty-four (73%) had FCA progression on follow-up with their maximum FCASS at a median of 8 (5-35.5) days poststroke; their median FCASS increase was 4 (2.5-6). FCASS did not correlate with recurrent arterial ischemic stroke. Maximum (but not baseline) FCASS correlated with 1-year pediatric stroke outcome measures ( P=0.037). Conclusions- Our novel scoring system for FCA severity correlates with neurological outcomes in the VIPS cohort and provides a tool for FCA treatment trials under development.

Serum Proteome Alterations in Human Cystathionine β-Synthase Deficiency and Ischemic Stroke Subtypes

Ischemic stroke induces brain injury via thrombotic or embolic mechanisms involving large or small vessels. Cystathionine β-synthase deficiency (CBS), an inborn error of metabolism, is associated with vascular thromboembolism, the major cause of morbidity and mortality in affected patients. Because thromboembolism involves the brain vasculature in these patients, we hypothesize that CBS deficiency and ischemic stroke have similar molecular phenotypes. We used label-free mass spectrometry for quantification of changes in serum proteomes in CBS-deficient patients (n = 10) and gender/age-matched unaffected controls (n = 14), as well as in patients with cardioembolic (n = 17), large-vessel (n = 26), or lacunar (n = 25) ischemic stroke subtype. In CBS-deficient patients, 40 differentially expressed serum proteins were identified, of which 18 were associated with elevated homocysteine (Hcy) and 22 were Hcy-independent. We also identified Hcy-independent differentially expressed serum proteins in ischemic stroke patients, some of which were unique to a specific subtype: 10 of 32 for cardioembolic vs. large-vessel, six of 33 for cardioembolic vs. lacunar, and six of 23 for large-vessel vs. lacunar. There were significant overlaps between proteins affected by CBS deficiency and ischemic stroke, particularly the cardioembolic subtype, similar to protein overlaps between ischemic stroke subtypes. Top molecular pathways affected by CBS deficiency and ischemic stroke subtypes included acute phase response signaling and coagulation system. Similar molecular networks centering on NFκB were affected by CBS deficiency and stroke subtypes. These findings suggest common mechanisms involved in the pathologies of CBS deficiency and ischemic stroke subtypes.

Recurrent stroke: the role of thrombophilia in a large international pediatric stroke population

Risk factors for arterial ischemic stroke in children include vasculopathy and prothrombotic risk factors but their relative importance to recurrent stroke is uncertain. Data on recurrent stroke from databases held in Canada (Toronto), Germany (Kiel-Lübeck/Münster), and the UK (London/Southampton) were pooled. Data were available from 894 patients aged 1 month to 18 years at first stroke (median age, 6 years) with a median follow-up of 35 months. Among these 894 patients, 160 (17.9%) had a recurrence between 1 day and 136 months after the first stroke (median, 3.1 months). Among 288 children with vasculopathy, recurrence was significantly more common [hazard ratio (HR) 2.5, 95% confidence interval (95% CI) 1.92-3.5] compared to the rate in children without vasculopathy. Adjusting for vasculopathy, isolated antithrombin deficiency (HR 3.9; 95% CI: 1.4-10.9), isolated elevated lipoprotein (a) (HR 2.3; 95% CI: 1.3-4.1), and the presence of more than one prothrombotic risk factor (HR 1.9; 95% CI: 1.12-3.2) were independently associated with an increased risk of recurrence. Recurrence rates calculated per 100 person-years were 10 (95% CI: 3-24) for antithrombin deficiency, 6 (95% CI: 4-9) for elevated lipoprotein (a), and 13 (95% CI: 7-20) for the presence of more than one prothrombotic risk factor. Identifying children at increased risk of a second stroke is important in order to intensify measures aimed at preventing such recurrences.

Recent developments and new frontiers in childhood arterial ischemic stroke

This review will discuss important developments in childhood arterial ischemic stroke over the past decade, focusing on improved understanding of the causes, consequences, and targets for intervention. Risk factors for childhood arterial ischemic stroke are different to adults. Infections, particularly herpes group viruses, are important precipitants for stroke. Non-atherosclerotic arteriopathies are the most common cause of childhood arterial ischemic stroke and an important predictor of recurrent events. Recent advances include the identification of serum biomarkers for inflammation and endothelial injury, and imaging biomarkers to monitor for vascular progression. Multicenter trials of immunotherapies in focal cerebral arteriopathies are currently in development. Recognition of clinical and radiological phenotypic patterns has facilitated the discovery of multisystem disorders associated with arterial ischemic stroke including ACTA2 arteriopathy and adenosine deaminase 2 deficiency. Identification of these Mendelian disorders provide insights into genetic mechanisms of disease and have implications for medical and surgical management. In contrast to adults, there are long diagnostic delays in childhood arterial ischemic stroke. Refinement of pediatric Code Stroke protocols and clinical decision support tools are essential to improve diagnostic certainty and improve access to reperfusion therapies. Children do not recover better than adults following arterial ischemic stroke, with more than half of survivors having long-term impairments. The physical, cognitive, and behavioral consequences of childhood arterial ischemic stroke are increasingly reported but further research is required to understand their impact on participation, quality of life, psychosocial, and family functioning. Longitudinal studies and the use of advanced imaging techniques, to understand neurobiological correlates of functional reorganization, are essential to developing targeted intervention strategies to facilitate recovery.

Dyslipidemia in Children With Arterial Ischemic Stroke: Prevalence and Risk Factors

BACKGROUND

Risk factors for pediatric stroke are poorly understood and require study to improve prevention. Total cholesterol and triglyceride values peak to near-adult levels before puberty, a period of increased stroke incidence. The role of lipids in childhood arterial ischemic stroke has been minimally investigated.

METHODS

We performed a cross-sectional analysis of lipid and Lp(a) concentrations in children with arterial ischemic stroke in the International Pediatric Stroke Study to compare the prevalence of dyslipidemia and high- or low-ranking lipid values in our dataset with reported population values. We analyzed sex, body mass index, race, ethnicity, family history, and stroke risk factors for associations with dyslipidemia, high non-high-density lipoprotein cholesterol, and hypertriglyceridemia.

RESULTS

Compared with the National Health and Nutrition Examination Survey, a higher proportion of children ≥5 years with arterial ischemic stroke had dyslipidemia (38.4% versus 21%), high total cholesterol (10.6% versus 7.4%), high non-high-density lipoprotein cholesterol (23.1% versus 8.4%), and low high-density lipoprotein cholesterol (39.8% versus 13.4%). The lipid values that corresponded to one standard deviation above the mean (84th percentile) in multiple published national studies generally corresponded to a lower ranking percentile in children aged five years or older with arterial ischemic stroke. Dyslipidemia was more likely associated with an underweight, overweight, or obese body mass index compared with a healthy weight. Ethnic background and an acute systemic illness were also associated with abnormal lipids.

CONCLUSIONS

Dyslipidemia and hypertriglyceridemia may be more prevalent in children with arterial ischemic stroke compared with stroke-free children.

Neuroinflammation in Ischemic Pediatric Stroke

Over the last decades, the importance of inflammatory processes in pediatric stroke have become increasingly evident. Ischemia launches a cascade of events: activation and inhibition of inflammation by a large network of cytokines, adhesion and small molecules, protease, and chemokines. There are major differences in the neonatal brain compared to adult brain, but developmental trajectories of the process during childhood are not yet well known. In neonatal stroke ischemia is the leading pathophysiology, but infectious and inflammatory processes have a significant input into the course and degree of tissue damage. In childhood, beside inflammation lanced by ischemia itself, the event of ischemia might be provoked by an underlying inflammatory pathophysiology: transient focal arteriopathy, dissection, sickle cell anemia, Moyamoya and more generalized in meningitides, generalized vasculitis or genetic arteriopathies (as in ADA2). Focal inflammatory reactions tend to be located in the distal part of the carotid artery or the proximal medial arteries, but generalized processes rather tend to affect the small arteries.

Pediatric arterial ischemic stroke: Epidemiology, risk factors, and management

Pediatric arterial ischemic stroke (AIS) is an uncommon but important cause of neurologic morbidity in neonates and children, with consequences including hemiparesis, intellectual disabilities, and epilepsy. The causes of pediatric AIS are unique to those typically associated with stroke in adults. Familiarity with the risk factors for AIS in children will help with efficient diagnosis, which is unfortunately frequently delayed. Here we review the epidemiology and risk factors for AIS in neonates and children. We also outline consensus-based practices in the evaluation and management of pediatric AIS. Finally we discuss the outcomes observed in this population. While much has been learned in recent decades, many uncertainties sill persist in regard to pediatric AIS. The ongoing development of specialized centers and investigators dedicated to pediatric stroke will continue to answer such questions and improve our ability to effectively care for these patients.

Biomarkers of Inflammation in Pediatric Arterial Ischemic Stroke

Investigators from Switzerland studied inflammatory markers in children and neonates with acute arterial ischemic stroke (AIS).

Perspectives in neonatal and childhood arterial ischemic stroke

INTRODUCTION

Over the last decade considerable advances have been made in the identification, understanding and management of pediatric arterial ischemic stroke. Such increasing knowledge has also brought new perspectives and interrogations in the current acute and rehabilitative care of these patients. Areas covered: In developed countries, focal cerebral arteriopathy is one of the most common causes of arterial ischemic stroke in childhood and imaging features are well characterized. However, there are ongoing debates regarding its underlying mechanisms, natural evolution and proper management. The implementation of thrombolytic therapy in acute pediatric stroke has been shown to be efficient in anecdotal cases but is still limited by a number of caveats, even in large tertiary centers. Finally, neonatal stroke represents a unique circumstance of possible early intervention before the onset of any neurological disability but this appears meaningful only in a selective group of neonates. Expert commentary: While perinatal stroke, a leading cause of cerebral palsy, appears to be multifactorial, a large number of childhood ischemic stroke are probably essentially triggered by infectious factors leading to vessel wall damage. Current research is aiming at better identifying risk factors in both conditions, and to define optimal acute and preventive therapeutic strategies in order to reduce significant long-term morbidity.