Stroke and the child's brain: an overview of epidemiology, syndromes and risk factors

Cerebral blood flow and cognitive outcome after pediatric stroke in the middle cerebral artery

Adaptive recovery of cerebral perfusion after pediatric arterial ischemic stroke (AIS) is sought to be crucial for sustainable rehabilitation of cognitive functions. We therefore examined cerebral blood flow (CBF) in the chronic stage after stroke and its association with cognitive outcome in patients after pediatric AIS. This cross-sectional study investigated CBF and cognitive functions in 14 patients (age 13.5 ± 4.4 years) after pediatric AIS in the middle cerebral artery (time since AIS was at least 2 years prior to assessment) when compared with 36 healthy controls (aged 13.8 ± 4.3 years). Cognitive functions were assessed with neuropsychological tests, CBF was measured with arterial spin labeled imaging in the anterior, middle, and posterior cerebral artery (ACA, MCA, PCA). Patients had significantly lower IQ scores and poorer cognitive functions compared to healthy controls (p < 0.026) but mean performance was within the normal range in all cognitive domains. Arterial spin labeled imaging revealed significantly lower CBF in the ipsilesional MCA and PCA in patients compared to healthy controls. Further, we found significantly higher interhemispheric perfusion imbalance in the MCA in patients compared to controls. Higher interhemispheric perfusion imbalance in the MCA was significantly associated with lower working memory performance. Our findings revealed that even years after a pediatric stroke in the MCA, reduced ipsilesional cerebral blood flow occurs in the MCA and PCA and that interhemispheric imbalance is associated with cognitive performance. Thus, our data suggest that cerebral hypoperfusion might underlie some of the variability observed in long-term outcome after pediatric stroke.

Hypoxic-ischemic injury causes functional and structural neurovascular degeneration in the juvenile mouse retina

Ischemic stroke is a major cause of long-term disabilities, including vision loss. Neuronal and blood vessel maturation can affect the susceptibility of and outcome after ischemic stroke. Although we recently reported that exposure of neonatal mice to hypoxia–ischemia (HI) severely compromises the integrity of the retinal neurovasculature, it is not known whether juvenile mice are similarly impacted. Here we examined the effect of HI injury in juvenile mice on retinal structure and function, in particular the susceptibility of retinal neurons and blood vessels to HI damage. Our studies demonstrated that the retina suffered from functional and structural injuries, including reduced b-wave, thinning of the inner retinal layers, macroglial remodeling, and deterioration of the vasculature. The degeneration of the retinal vasculature associated with HI resulted in a significant decrease in the numbers of pericytes and endothelial cells as well as an increase in capillary loss. Taken together, these findings suggest a need for juveniles suffering from ischemic stroke to be monitored for changes in retinal functional and structural integrity. Thus, there is an emergent need for developing therapeutic approaches to prevent and reverse retinal neurovascular dysfunction with exposure to ischemic stroke.

Pediatric Stroke: A Single-Center Experience

The aim of this study was to evaluate the clinical characteristics, risk factors, treatment, and outcomes of pediatric stroke cases. A total of 118 patients diagnosed with arterial ischemic stroke (AIS), hemorrhagic stroke, and sinovenous thrombosis (SVT) between January 2000 and December 2011 were included. Neonatal cases were excluded. Demographic and clinical findings were retrospectively examined from medical records. We identified 118 patients with stroke. The age of the patients ranged from 1 to 215 months (17.92 y), with a mean age of 5.19±5.25 years. AIS accounted for the majority of cases (n=69, 58.5%), and the major etiology was cardiac disease (17%). Hemorrhagic stroke accounted for 19.5% (n=23) of the cases, and late hemorrhagic disease of the newborn was the major etiology (43%, n=10). SVT accounted for 22% (n=26) of the cases, and the major etiology was otitis media-mastoiditis (27%, n=7). Hemiplegia and headache were the most frequent symptoms for AIS and SVT, respectively. Stroke is rare in children compared with adults; however, it is detected more frequently with better imaging techniques and increased awareness. We found that children with AIS presented more commonly with hemiplegia and children with SVT with headache and strabismus. We did not find an association between thrombophilia and stroke.

Rodent Models of Developmental Ischemic Stroke for Translational Research: Strengths and Weaknesses

Cerebral ischemia can occur at any stage in life, but clinical consequences greatly differ depending on the developmental stage of the affected brain structures. Timing of the lesion occurrence seems to be critical, as it strongly interferes with neuronal circuit development and determines the way spontaneous plasticity takes place. Translational stroke research requires the use of animal models as they represent a reliable tool to understand the pathogenic mechanisms underlying the generation, progression, and pathological consequences of a stroke. Moreover, in vivo experiments are instrumental to investigate new therapeutic strategies and the best temporal window of intervention. Differently from adults, very few models of the human developmental stroke have been characterized, and most of them have been established in rodents. The models currently used provide a better understanding of the molecular factors involved in the effects of ischemia; however, they still hold many limitations due to matching developmental stages across different species and the complexity of the human disorder that hardly can be described by segregated variables. In this review, we summarize the key factors contributing to neonatal brain vulnerability to ischemic strokes and we provide an overview of the advantages and limitations of the currently available models to recapitulate different aspects of the human developmental stroke.

[Childhood stroke : What are the special features of childhood stroke?]

Childhood arterial ischemic stroke differs in essential aspects from adult stroke. It is rare, often relatively unknown among laypersons and physicians and the wide variety of age-specific differential diagnoses (stroke mimics) as well as less established care structures often lead to a considerable delay in the diagnosis of stroke. The possible treatment options in childhood are mostly off-label. Experiences in well-established acute treatment modalities in adult stroke, such as thrombolysis and mechanical thrombectomy are therefore limited in children and only based on case reports and case series. The etiological clarification is time-consuming due to the multitude of risk factors which must be considered. Identifying each child's individual risk profile is mandatory for acute treatment and secondary prevention strategies and has an influence on the individual outcome. In addition to the clinical neurological outcome the residual neurological effects of stroke on cognition and behavior are decisive for the integration of the child into its educational, later professional and social environment.

Risk factors in childhood arterial ischaemic stroke: Findings from a population-based study in Germany

OBJECTIVE

Acute treatment of childhood arterial ischaemic stroke and prevention strategies for recurrent stroke episodes depend strongly on each child's individual risk profile. The aim of this study is to characterize risk factors for childhood stroke, their occurrence in isolation or combination, and to identify possible common risk factor patterns.

METHODS

This population-based study was conducted via ESPED, a surveillance unit for rare paediatric diseases in Germany. Children aged >28days and <18 years with an acute arterial ischaemic stroke occurring between January 2015 and December 2016 were included.

RESULTS

Among 99 reported children with arterial ischaemic stroke, 56 children were male. Male predominance was significant in adolescents from 12 years old onward. Arterial ischaemic stroke was more common in very young children <2 years of age and in adolescence. No risk factor was identified in 27 children. Hypercoagulable states (29%), cardiac disorders (24%), and arteriopathies (21%) were the most common risk factors. Some risk factor categories were more likely to be identified in isolation (i.e. cardiac disorders, prothrombotic abnormalities and chronic head and neck disorders) than others. The number of risk factors (n = 0-4) per patient and risk factor categories did not differ by age.

CONCLUSION

Although we could not identify common patterns of risk factor combinations, several risk factors occurred more likely in isolation than others. Further research should focus on the impact of isolated presumed childhood stroke risk factors like certain prothrombotic abnormalities, migraine or a patent foramen ovale. With regard to different age groups, stroke mechanisms in male adolescents require particular attention.

Is the 1298A>C polymorphism in the MTHFR gene a risk factor for arterial ischaemic stroke in children? The results of meta-analysis

An elevated level of homocysteine is a risk factor for vascular diseases, brain atrophy and several other disorders. The 1298A>C polymorphism (rs1801131) leads to mildly decreased MTHFR activity. Previously, it was observed that the MTHFR 1298A>C polymorphism in combined analysis with the MTHFR 677C>T polymorphism increases homocysteine levels. However, conflicting results on its relation to ischaemic stroke in children can be found. We conducted a meta-analysis to analyse possible connections between the MTHFR 1298A>C polymorphism and ischaemic stroke in paediatric patients. We identified available data published before December 2016 using appropriate keywords and searching PubMed as well as the references cited in the found articles. Eight case-control studies were included in the meta-analysis (426 children with stroke and 778 controls). Statistical analyses were made using R and Comprehensive Meta-Analysis softwares to investigate the impact of polymorphism in four models: dominant, recessive, additive and allelic. No publication bias was observed in the meta-analysis. We demonstrated no relationship between the 1298A>C polymorphism and ischaemic stroke in children in the case of recessive, additive and allelic models. However, the results of the dominant model analysis should be treated with caution due to the sensitivity analysis results. After omitting one of the included study, we observed a significant association between the carriers of the MTHFR C allele (cases with AC + CC genotypes) and ischaemic stroke in children (OR 1.35 95% CI 1.02-1.79, p = 0.035 in a fixed effects model). In conclusion, the 1298A>C polymorphism in the MTHFR gene is not a risk factor for ischaemic stroke in paediatric patients.

Transient ischemic attack requiring hospitalization of children in the United States: kids' inpatient database 2003 to 2009

BACKGROUND AND PURPOSE

Transient ischemic attacks (TIA) are not well described in children. We assessed the prevalence of risk factors for TIA requiring hospitalization in children in a large national database.

METHODS

Using the Healthcare Cost and Utilization Project Kids' Inpatient Database, children aged 1 to 18 years admitted for TIA in 2003, 2006, and 2009 were identified by International Classification of Diseases, Ninth Revision, Clinical Modification code 435. Descriptive analyses identified patient characteristics. Trend analysis determined the change in annual average hospitalization days from 2003 to 2009.

RESULTS

TIA was the primary diagnosis for 531 children. Important secondary diagnoses included sickle cell disease (20%), congenital heart disease (11%), migraine (12%), moyamoya disease (10%), and stroke (4%). Mean length of stay decreased from 3.0 days (95% confidence interval, 2.4-3.6) in 2003 to 2.3 days (95% confidence interval, 2.0-2.7) in 2009 (P=0.04). During the same period, 2590 children were admitted with ischemic stroke; 4.8 children with stroke were admitted for every child with TIA.

CONCLUSIONS

Recognized risk factors for TIA, including sickle cell disease, congenital heart disease, moyamoya, recent stroke, and migraine, were present in <60% of children. Pediatric admissions for ischemic stroke were ≈5-fold more common than for TIA. Further study is required to understand the risk of stroke after TIA in children to guide appropriate evaluation and treatment.

Multiple presence of prothrombotic risk factors in Croatian children with arterial ischemic stroke and transient ischemic attack

Aim

To determine the frequency of inherited and acquired prothrombotic risk factors in children with arterial ischemic stroke (AIS) and transient ischemic attacks (TIA) in Croatia.

Methods

We investigated 14 prothrombotic risk factors using blood samples from 124 children with AIS or TIA and 42 healthy children. Prothrombotic risk factors were classified into five groups: natural coagulation inhibitors (antithrombin, protein C, protein S), blood coagulation factors (FV Leiden and FII 20210), homocysteine, lipid and lipoprotein profile (lipoprotein (a), triglycerides, total, high- and low-density lipoprotein), and antiphospholipid antibodies (lupus anticoagulant, anticardiolipin, and antiphosphatidylserine antibodies).

Results

The most common prothrombotic risk factor was elevated lipoprotein (a), which was identified in about 31% of patients and in 24% of controls. Natural coagulation inhibitors were decreased in about 19% of patients, but not in controls. Pathological values of homocysteine, blood coagulation factor polymorphisms, and antiphospholipid antibodies were found in similar frequencies in all groups. Fourteen children with AIS and TIA (11.3%) and no children from the control group had three or more investigated risk factors.

Conclusion

The presence of multiple prothrombotic risk factors in children with cerebrovascular disorder suggests that a combination of risk factors rather than individual risk factors could contribute to cerebrovascular disorders in children.

Interhemispheric functional connectivity following prenatal or perinatal brain injury predicts receptive language outcome

Early brain injury alters both structural and functional connectivity between the cerebral hemispheres. Despite increasing knowledge on the individual hemispheric contributions to recovery from such injury, we know very little about how their interactions affect this process. In the present study, we related interhemispheric structural and functional connectivity to receptive language outcome following early left hemisphere stroke. We used functional magnetic resonance imaging to study 14 people with neonatal brain injury, and 25 age-matched controls during passive story comprehension. With respect to structural connectivity, we found that increased volume of the corpus callosum predicted good receptive language outcome, but that this is not specific to people with injury. In contrast, we found that increased posterior superior temporal gyrus interhemispheric functional connectivity during story comprehension predicted better receptive language performance in people with early brain injury, but worse performance in typical controls. This suggests that interhemispheric functional connectivity is one potential compensatory mechanism following early injury. Further, this pattern of results suggests refinement of the prevailing notion that better language outcome following early left hemisphere injury relies on the contribution of the contralesional hemisphere (i.e., the "right-hemisphere-take-over" theory). This pattern of results was also regionally specific; connectivity of the angular gyrus predicted poorer performance in both groups, independent of brain injury. These results present a complex picture of recovery, and in some cases, such recovery relies on increased cooperation between the injured hemisphere and homologous regions in the contralesional hemisphere, but in other cases, the opposite appears to hold.

The epidemiology of intermittent and chronic ataxia in children in Manitoba, Canada

AIM

To determine the epidemiology of chronic ataxia in children in Manitoba, Canada.

METHOD

A retrospective study using multiple sources and disease codes identified children (age 0-16y) with chronic ataxia (>2mo duration or recurrent episodes of ataxia) seen at Winnipeg Children's Hospital from 1991 to 2008. Patients with isolated peripheral nerve diseases, vestibular disorders, or brain tumors were excluded.

RESULTS

We identified 184 patients (males=females; mean age 15y, SD 7y 8mo) with chronic ataxia. Median age at the presenting symptom onset was 1 year 3 months and at ataxia onset 3 years 1 month. Median duration of follow-up was 6 years 5 months. During the study period, the crude incidence rate was 5.77 in 10,000; the crude prevalence rate was 6.59 in 10,000; and the crude mortality rate 0.446 in 10,000. The most common presenting symptoms were developmental delay, ataxia, or seizures. The most common diagnoses (known in 129) were Angelman syndrome (n=16), ataxia telangiectasia (n=13), mitochondrial disease (n=9), Friedreich ataxia (n=7), stroke (n=7), and familial/genetic episodic ataxia (n=7).

INTERPRETATION

Chronic ataxia is a relatively common early-presenting symptom in childhood. A specific diagnosis is possible in 70% of patients after extensive investigations. The mortality rate is relatively low and the disease burden is high with significant comorbidities including developmental delay and epilepsy.

Perfusion CT in childhood stroke--initial observations and review of the literature

INTRODUCTION

To report the preliminary results of contrast-enhanced perfusion multi-detector CT for diagnoses of perfusion disturbances in children with clinical suspicion of stroke.

PATIENTS AND METHODS

Within the last two years emergency perfusion CT was performed in ten children (age: 8-17 years, male:female=3:7) for assessment of suspected childhood stroke. These intracranial perfusion CT, intracranial CT-digital subtraction angiography (CT-DSA) and extracranial CT-angiography (CTA) studies were retrospectively reviewed and compared with MRI, follow-up CT, catheter angiography and final clinical diagnosis. The total dose length product (DLP) for the entire examination was recorded. The image quality of perfusion CT-maps, CT-DSA and CTA were evaluated with a subjective three-point scale ranging from very good to non-diagnostic image quality rating perfusion disturbance, intracranial peripheral vessel depiction, and motion- or streak artifacts.

RESULTS

In nine of ten children perfusion CT showed no false positive or false negative results. In one of ten children suffering from migraine focal hypo-perfusion was read as perfusion impairment potentially indicating early stroke, but MRI and MRA follow-up were negative. Overall, perfusion-CT with CT-DSA was rated very good in 80% of cases for the detection of perfusion disturbances and vessel anatomy.

CONCLUSIONS

In comparison to standard CT, contrast-enhanced perfusion CT improves CTs' diagnostic capability in the emergency examination of children with a strong suspicion of ischemic cerebral infarction.

Ischemic stroke in infants and children: practical management in emergency

Stroke is a rare disease in children, with an estimated incidence 13/100000 and a significant impact on morbidity and mortality. Clinical presentation and risk factors, present in almost half of pediatric patients, are not the same as in adults. The diagnosis of stroke in children is often delayed because signs and symptoms can be subtle and nonspecific. History and clinical examination should exclude underlying diseases or predisposing factors. Neuroimaging is crucial in defining diagnosis. Other tests might be necessary, according to the clinical picture. We present here the most recent practical directions on how to diagnose and manage arterial stroke in children, according to different international guidelines on the subject.

Fatal ischemic stroke due to dissecting aneurysm of the intracranial arteries presenting as sudden unexpected death in childhood

Sudden unexpected death is any nontraumatic death in healthy individuals with normal activities for age until acute demise. Whereas not uncommon in adults and infants, it is considered a rarity in children, with most cases due to infection or occult cardiovascular abnormalities. Pathologic intracranial findings are rarely found in sudden unexpected death in childhood, with most cases due to occult intracranial neoplasms. Cerebral arterial dissection is an uncommon cause of arterial ischemic stroke in childhood. Outcome is poor, with more than 20% of patients dying. We report 4 cases of sudden unexpected death due to arterial ischemic stroke after cerebral arterial dissection in childhood and present a review of the literature.

Non-invasive imaging of intracranial pediatric vascular lesions

OBJECTIVES

The goal of this review is to discuss the different non-invasive imaging techniques as well as the age-specific pediatric vascular pathologies and their imaging features.

MATERIAL AND METHODS

Ultrasound, computed tomography, and magnetic resonance imaging features of pediatric ischemic stroke, intracranial hemorrhage, aneurysms, cavernomas, developmental venous anomalies, and arteriovenous malformations are presented. In addition, multiple non-invasive angiographic techniques (CT and MR angiography) and functional MRI sequences (diffusion, perfusion, and susceptibility-weighted imaging) are discussed.

CONCLUSION

Neurovascular imaging plays a central role in the early, sensitive, and specific diagnosis of pediatric intracranial vascular disorders. A detailed knowledge of the quality and exact angioarchitecture of pediatric vascular pathologies as well as their impact on the cerebral hemo-dynamics is essential to guide and monitor treatment options and to predict functional outcome.

Crossing the blood-brain barrier: clinical interactions between neurologists and hematologists in pediatrics - advances in childhood arterial ischemic stroke and cerebral venous thrombosis

PURPOSE OF REVIEW

The past year has marked a period of growing awareness of the need for improved diagnosis and treatment in children with arterial ischemic stroke (AIS) and cerebral sinus venous thrombosis (CSVT). Here we review these conditions, highlighting the importance of the intersection between hematologic abnormalities and pediatric stroke as they impact clinical management.

RECENT FINDINGS

Recent multicenter cohort studies are beginning to clarify the incidence, risk factors, clinical course and outcomes of AIS and CSVT in children. Key findings include: diagnosis rests on adequate neuroimaging and is often delayed more than 24 h after symptom onset; multiple risk factors and inciting events are often involved; one or more prothrombotic risk factors are common; recurrence is common; and selected groups of patients benefit from anticoagulation, and less frequently, thrombolytic therapies.

SUMMARY

Progress in caring for children with AIS and CSVT requires greatly improved awareness of cerebrovascular disease among primary providers, who are most often the first point of contact, more rapid and specific diagnosis using appropriate advanced neuroimaging technologies, comprehensive hematologic evaluation for inherited and acquired thrombophilias, and multidisciplinary approaches to treatment. Additional large cohort studies and clinical trials are greatly needed to further clarify these issues.

Childhood stroke in Eastern Province, KSA: pattern, risk factors, diagnosis and outcome

BACKGROUND AND PURPOSE

Stroke has been increasingly recognized in children in recent years, but diagnosis and management can be difficult because of the diversity of underlying risk factors, atypical presentation and the absence of a uniform treatment approach. The aim of this study was to examine risk factors, clinical presentation, imaging findings and outcomes of paediatric stroke in Eastern Province, Kingdom of Saudi Arabia (KSA).

SUBJECTS AND METHODS

We evaluated 25 patients (11 boys and 14 girls) using computerized tomography scan of the brain, magnetic resonance (MR) imaging and MR angiography. Cardiac assessment, haematological tests, immunological tests, infection and metabolic screening were also performed in the patients. After discharge, the patients were monitored regularly in the neurology clinic to detect their outcomes.

RESULTS

A total of 76% of the patients presented with ischaemic stroke, while the remaining 24% had haemorrhagic stroke. Sickle cell disease (SCD) was the commonest risk factor for stroke (36%) followed by non determinate causes (20%). Seizure was the commonest clinical presentation (54%) followed by haemiplegia (31%) and decreased level of consciousness (30%). Recurrence occurred in SCD patients (80%) and patients with moyamoya disease (20%). Regarding the outcome, long-term deficit was the commonest (44%), while short-term deficit and death were equal (28% each).

CONCLUSION

Our study in Eastern Province, KSA, showed agreement with other studies regarding risk factors, clinical presentation, imaging features and outcomes of stroke in children, yet with some points of differences, which are as follows: (1) SCD is the commonest risk factor in our study population, while in Chinese study it was not, (2) The percentage of cardiac disorders as a risk factor in this study was less than that in the European and American studies, and (3) there was relative discrepancy regarding predictors of outcome.

Varicella vaccination and ischemic stroke in children: is there an association?

BACKGROUND

Ischemic stroke is a known complication of varicella disease. Although there have been case reports of ischemic stroke after varicella vaccination, the existence and magnitude of any vaccine-associated risk has not been determined. OBJECTIVE. The purpose of this work was to determine whether varicella vaccination is associated with an increased risk of ischemic stroke and encephalitis in children within 12 months after vaccination.

PATIENTS AND METHODS

We conducted a retrospective cohort study based on computerized data from children 11 months through 17 years old enrolled for > or =12 months in the Vaccine Safety DataLink from 1991 through 2004. International Classification of Disease codes identified cases of ischemic stroke (433-436, 437.1, 437.4, 437.6, 437.8-437.9) and encephalitis (052.0, 323.5, 323.8-9). Cox regression was used to model the risk in the 12 months after vaccination relative to all other person-time. Covariates included calendar time, gender, and stroke risk factors (eg, sickle cell disease).

RESULTS

Varicella vaccine was administered to 35.3% of the 3.2 million children in the cohort. There were 203 new inpatient ischemic stroke diagnoses, including 8 that occurred within 12 months after vaccination; there was no temporal clustering. The adjusted stroke hazard ratio was not elevated during any of the time periods in the 12 months after vaccination. Stroke was strongly associated with known risk factors such as sickle cell disease and cardiac disease. None of the 243 encephalitis cases occurred during the first 30 days after vaccination, and there was no association between encephalitis and varicella vaccination at any time in the 12 months after vaccination.

CONCLUSION

Our retrospective cohort study of >3 million children found no association between varicella vaccine and ischemic stroke.

Impact of age and strain on ischemic brain injury and seizures after carotid ligation in immature mice

Stroke is an important cause of neurologic injury in the neonatal period and frequently results in lifelong neurologic impairments. We reported previously that unilateral carotid ligation on postnatal day (P)12 in CD1 mice causes acute behavioral seizures and unilateral brain injury and provides a model for neonatal stroke in human infants. In the present study we confirmed that behavioral seizures observed after ligation on P12 in the CD1 strain are associated with rhythmic ictal discharges that show temporal progression on electrocorticograms. We also examined the effects of carotid ligation performed at different ages in CD1 mice or performed in the C57Bl/6 strain. The right common carotid was ligated at P7, P10, P12 or P21 in CD1 mice or at P12 in C57Bl/6 mice. Littermate controls received sham surgery. Seizures were rated for 4h after surgery; brain injury was scored one week later. In a separate group of P12 CD1 mice, electrocorticographic activity was recorded continuously for 4h after carotid ligation or sham surgery. Brain injury and cumulative seizure score varied significantly with age (p<0.001) and strain (p<0.001). In CD1 mice, injury was greatest after ligation on P10 to P12 and seizure score was maximal at P12. Seizure scores were significantly correlated with injury after ligation on P10 or P12. C57Bl/6 mice, like C3Heb/FeJ mice examined previously, were much less vulnerable to seizures and injury than CD1 mice after ligation on P12. This study demonstrates that carotid ligation in the CD1 mouse on P12 causes acute electrographic rhythmic discharges that correlate with behavioral seizures. We also found that the age at which ligation is performed and genetic strain have a strong influence on the severity of injury.

Arterial ischemic stroke in children--recent advances

Childhood stroke syndromes are an important cause of mortality and morbidity. This paper focuses on the recent advances in arterial ischaemic stroke beyond the neonatal period. Vascular risk factors are identified in the majority of children and guide both acute and longer term treatments, as well as determining prognosis. Contrary to popular belief many children have residual impairments encompassing a wide range of domains. National and international collaborations are facilitating an increase in the understanding of childhood stroke and have the eventual aim of conducting trials of potential therapeutic interventions.

Arterial ischemic stroke in children

Stroke in children is relatively rare. Advances in the clinical recognition and radiographic diagnosis of ischemic stroke have increased the frequency of the diagnosis in infants and children and have raised the need for immediate therapy. A vast amount of data has recently become available through basic research and neuroimaging techniques shedding new light on the chain of events that occur in ischemic stroke in animal models and in the adult population. Whether this new information can also be applied to the pediatric population remains to be seen, but it is likely that the active management of children with acute ischemic stroke in the near future will include brain protection, brain reperfusion, and prevention measures.

Enriched environment and the effect of age on ischemic brain damage

Stroke affects all age groups from the newborn to the elderly. Previous work from our laboratory has shown that despite a greater susceptibility to brain damage, the immature brain recovers more rapidly and to a greater extent than does the more mature nervous system. In the current study, we examined the influence of environmental enrichment on the effects of age on the brain damaging effects of stroke. Rats aged 10, 63, and 180 days received ischemic insults following stereotactic intra-cerebral injection of endothelin-1, and resulting in injury to the right middle cerebral artery territory. Rats were then housed in either environmentally enriched cages, or standard cages for 60 days, after which they were sacrificed, and brain volumes determined for the extent of neurologic injury. Rats receiving the insult at 10 days of age showed a reduction of pathologic injury when housed in the enriched cages compared to standard. Conversely, rats receiving the insult at 180 days and housed environmentally enriched cages actually showed an increased volume of brain damage compared to controls. Our findings clearly indicate the dramatic influence of age on the extent of stroke and the influence of rehabilitative therapies. Behavioral correlation to morphologic alterations is required. Attempts at therapeutic interventions clearly need to be age-specific.

Arterial brain infarction in complicated acute otitis media

We report a rare case of acute otitis media (AOM) complicated by arterial brain infarction, meningitis and orbital cellulitis. Computed tomography (CT) initially showed suspected epidural abscess, coalescent mastoiditis, and orbital cellulitis. Further clinical deterioration occurred following mastoidectomy and evacuation of the abscess. Magnetic resonance imaging (MRI) revealed subacute brain infarction and an extra-axial brainstem abscess. Revision of the initial CT revealed subtle signs suggestive of arterial brain infarction. Although CT with contrast is the standard of care for suspected AOM complications, MRI should be considered as an adjunct when CT is not definitive and neurological signs are present.

Therapeutic approaches and advances in pediatric stroke

Evidence-based therapeutic interventions for pediatric ischemic cerebrovascular disease are beginning to emerge. The primary therapeutic target is usually the pathological prothrombotic disturbance that underlies the majority of pediatric stroke. A battle between anticoagulation and anti-platelet therapies continues to provide controversy and is the inspiration for upcoming randomized trials. Supportive care and neuroprotective strategies are an important consideration in children with stroke. Attempts to determine the safety of acute thrombolytic interventions are also underway. Finally, unique medical and surgical treatments for specific diseases leading to stroke in children continue to evolve. After briefly summarizing the epidemiology, pathophysiology, diagnosis, and outcomes of ischemic strokes in children, treatment approaches and alternatives will be reviewed in detail with emphasis placed on current areas of controversy and future directions for clinical research.

Pediatric stroke: the child is not merely a small adult

Arterial ischemic stroke and sinovenous thrombosis are a significant yet under-recognized causes of mortality and morbidity in the pediatric population. With increasingly complex etiologies yet urgency for rapid diagnosis and treatment, pediatric stroke teams likely will become the standard of care. A common terminology must be developed to avoid confusing types of acute cerebral insults--such as focal arterial ischemic stroke and global hypoxia and ischemia--that have different causes and pathophysiologic mechanisms of injury. Increased awareness of unique pediatric stroke subtypes, their clinical presentation, and their imaging findings will facilitate early identification and development of optimal treatment strategies.

Minocycline confers early but transient protection in the immature brain following focal cerebral ischemia-reperfusion

The incidence of neonatal stroke is high and currently there are no strategies to protect the neonatal brain from stroke or reduce the sequelae. Agents capable of modifying inflammatory processes hold promise. We set out to determine whether delayed administration of one such agent, minocycline, protects the immature brain in a model of transient middle cerebral artery (MCA) occlusion in 7-day-old rat pups. Injury volume in minocycline (45 mg/kg/dose, beginning at 2 h after MCA occlusion) and vehicle-treated pups was determined 24 h and 7 days after onset of reperfusion. Accumulation of activated microglia/macrophages, phosphorylation of mitogen-activated protein kinase (MAPK) p38 in the brain, and concentrations of inflammatory mediators in plasma and brain were determined at 24 h. Minocycline significantly reduced the volume of injury at 24 h but not 7 days after transient MCA occlusion. The beneficial effect of minocycline acutely after reperfusion was not associated with changed ED1 phenotype, nor was the pattern of MAPK p38 phosphorylation altered. Minocycline reduced accumulation of IL-1beta and CINC-1 in the systemic circulation but failed to affect the increased levels of IL-1beta, IL-18, MCP-1 or CINC-1 in the injured brain tissue. Therefore, minocycline provides early but transient protection, which is largely independent of microglial activation or activation of the MAPK p38 pathway.

A New Model for Determining the Influence of Age and Sex on Functional Recovery following Hypoxic-Ischemic Brain Damage

Stroke is a disorder affecting the lives of all age groups, and particularly those at the opposite ends of the age spectrum. It is generally believed that the immature brain is more resistant to damage resulting from a hypoxic/ischemic injury, and that it is also more 'plastic' in terms of its ability to recover. Evidence from our laboratory, and a host of others, has indicated, however, that the developing brain may in fact be more sensitive to injury resulting from hypoxia-ischemia. The question remains, however, whether the immature brain has a greater capacity for recovery. In order to determine the relative capability for functional recovery between age groups, a stroke model of comparable injury is required. This paper describes a new rodent model of ischemic injury allowing for comparisons of behavioral recovery spanning the spectrum of ages between newborn and the elderly. Endothelin-1, a potent vasoconstrictor, was stereotactically injected into the brains of 10-, 63-, and 180-day-old Wistar rats, immediately adjacent to the middle cerebral artery. Regionally, the cortex, caudate, and thalamus were most significantly affected, with sparing of the hippocampus. Pathologic assessment indicated a similar degree of injury across age groups affecting the territorial distribution of the middle cerebral artery, with a predominance of damage in the anterior sections of the cortex and caudate (p < 0.05), compared to the posterior sections including the cortex and thalamus. There were no regional differences in the extent of damage between age groups. Interestingly, however, there were significant differences between males and females regarding the overall extent of brain damage (p < 0.05), with males showing greater damage than females. In addition, there were significant regional differences in the extent of damage between males and females, particularly regarding cortical damage (p < 0.05), both anteriorly and posteriorly, and the caudate anteriorly (p < 0.05). Our findings provide an important new model for comparison of brain damage among the entire spectrum of ages affected by stroke. Importantly, this will allow for further investigations regarding both functional recovery and gender difference comparisons. This may have important ramifications for the development of therapeutic interventions that are age and gender specific.

Magnetic resonance image correlates of hemiparesis after neonatal and childhood middle cerebral artery stroke

OBJECTIVE

Motor impairment after neonatal and childhood-onset ischemic stroke (IS) is common, although the prevalence and type of hemiparesis differs between the 2 age groups. Lesion topography is an important predictor of hemiparesis after neonatal IS, but it is not known if the same topographic predictors of adverse motor outcome apply to childhood-onset IS. We used a consistent approach to define lesion topography and evaluate motor outcome in both age groups to (1) investigate whether early topographic predictors of hemiparesis after unilateral middle cerebral artery-territory stroke are the same in neonates and older children and (2) compare the prevalence of dystonia and loss of independent finger movements between the 2 age groups.

DESIGN

Twenty-eight patients with neonatal-onset IS (Hammersmith Hospital, London, United Kingdom) were studied together with 43 patients with childhood-onset IS (Great Ormond Street Hospital, London, United Kingdom). All patients had exclusive unilateral middle cerebral artery-territory IS. Lesion topography was studied by using the first magnetic resonance image acquired after the onset of symptoms and was coded for involvement of cerebral cortex (CC), posterior limb of the internal capsule (PLIC), basal ganglia (BG), and white matter. The primary outcome was hemiparesis, and secondary outcomes were dystonia and loss of age-appropriate independent finger movements.

RESULTS

Hemiparesis was more common after childhood-onset IS (56%) than neonatal-onset IS (24%). In neonatal-onset IS, concomitant involvement of BG, CC, and PLIC predicts the development of hemiparesis (odds ratio: 99; 95% confidence interval: 5.2-1883.8), and no child with 1 or 2 of these structures involved developed hemiparesis. In contrast, in childhood-onset IS, concomitant BG, CC, and PLIC lesions tended to be associated with hemiparesis (9 of 11), but this adverse outcome was seen also among patients with 1- or 2-site involvement. However, hemiparesis was less likely if the infarction involved BG only (odds ratio: 0.162; 95% confidence interval: 0.036-0.729). Dystonia was present in 15 of 24 in the childhood-onset group with hemiparesis but was not seen after neonatal-onset IS. In both age groups upper-limb impairment was more severe than lower-limb impairment, with frequent loss of independent hand function among hemiparetic patients.

CONCLUSIONS

In neonatal and childhood-onset IS, early magnetic resonance imaging provides useful prognostic information about subsequent motor outcome. There are differences in the functional response of the neuromotor system to injury between the 2 age groups that cannot be attributed to methodological differences alone.

Pediatric stroke among Hong Kong Chinese subjects

BACKGROUND

The incidence of pediatric stroke was estimated to be 2.5 to 2.7 cases per 100,000 children per year in North America and 13 cases per 100,000 children per year in France. Stroke is among the top 10 causes of death among children in the United States, with the highest incidence in the first 1 year of life. The annual mortality rate was 0.34 deaths per 100,000 person-years, with an average of 244 deaths per year. Interethnic differences have been demonstrated to be important in pediatric stroke. However, most population-based studies on pediatric stroke were from Europe or North America, and there was a lack of data on the incidence of stroke among Chinese or Asian children. Whether the etiologic patterns and risk factors for death and morbidity among Chinese children with stroke were similar to those described for other ethnic groups was unknown.

OBJECTIVES

To calculate the incidence of stroke among Chinese children in Hong Kong and to examine the clinical spectrum, causes, patterns, risk factors, and outcomes of pediatric stroke among Chinese subjects.

METHODS

The population of Hong Kong was 6.7 million in 2001, and >98% of our population is Chinese in origin. In Hong Kong, public hospitals under the Hospital Authority provide >95% of the hospital service for the region. We identified children (>1 month to <15 years of age) who were admitted and given a discharge diagnosis of stroke from the Clinical Data Analysis and Reporting System, which is a centralized computerized database for all public hospitals. The discharge coding of stroke used codes from the International Classification of Diseases, 9th Revision, Clinical Modification. Only first admissions during the study period were included. We excluded any subsequent admissions by using multiple demographic characteristics of the patients. The incidence of pediatric stroke was estimated as the number of first hospitalizations divided by the person-years at risk. Since 1991, we had been collecting a database on pediatric stroke (ages of 1 month to 16 years) from a single center (the university-affiliated pediatric unit). The clinical presentation, causes, risk factors, and outcomes for those in the Hong Kong Children's Stroke Registry with follow-up data for > or =2 years were analyzed. Data on outcomes, in terms of survival and neurologic deficits, were studied. For survivors, neurologic deficits were defined as short-term if they resolved within 3 months and long-term if they persisted for >3 months. The severity of deficits was defined as mild when function was minimally affected and the patient remained independent in activities of daily living, moderate when the patient required supervision or partial assistance in activities of daily living or when the deficit caused delay in developmental milestones, and severe when the patient required total or near-total care in activities of daily living. Potential risk factors for death and poor neurologic outcomes, including gender, age at the time of stroke, clinical presentation, causes, and neuroimaging findings, were analyzed.

RESULTS

Using projections from census data in 2001, the number of children <15 years of age in Hong Kong from 1998 to 2001 was estimated to be 1,104100 to 1,158800, resulting in 4,545300 person-years. During the same period, 94 children with discharge coding of stroke were identified. Therefore, the estimated incidence of pediatric stroke between 1998 and 2001 was 2.1 cases per 100,000 children-years. The average number of new cases treated annually was 4.5 (0-15 cases/year). Fifty children (28 boys and 22 girls; male/female ratio: 1.27:1) were identified in the 11-year period. The mean age at presentation was 5.6 +/- 4.9 years. Thirty-six strokes (72%) were ischemic and 14 (28%) were hemorrhagic. Despite evaluation for possible underlying causes, 12% (6 cases) remained idiopathic. Eighteen patients with ischemic strokes had cerebral thrombosis, whereas 15 had cerebral embolism. We did not observe any case of sinovenous thrombosis. The 36 cases of ischemic stroke were subtyped according to vascular territories. Eleven cases had infarction involving the middle cerebral artery territory; 2 were limited to the cortical region, 3 were limited to subcortical structures such as the basal ganglia or internal capsule or both, and 6 had complete middle cerebral artery involvement, with cortical and subcortical stroke. Involvement of the anterior cerebral artery occurred in 2 cases, with involvement of cerebellar/basilar artery territories in another 2 cases. The remaining 15 cases had multiple sites of infarction. Three patients experienced secondary hemorrhagic transformation after the initial thrombotic event. Of the 14 patients with hemorrhagic strokes, only 1 had subarachnoid hemorrhage. All others had intracerebral bleeding, at single (N = 9) or multiple (N = 4) loci. Important causes included complications related to congenital heart diseases (N = 15, 30%), vascular diseases (N = 13, 26%), and hematologic diseases (N = 14, 28%). Six cases had no determined causes. One case involved mitochondrial encephalopathy with lactic acidosis and stroke-like episodes and constituted the only case with a metabolic cause. For the 7 patients for whom prothrombotic screening was performed, findings were negative. Seizures (52%) and hemiplegia (34%) were the most common presenting features. Other presenting clinical features included headaches (22%), decreased consciousness (30%), visual field defects (12%), dysphasia (10%), and lethargy (8%). Only 1 patient, with moyamoya disease, had a family history of stroke. The median follow-up time was 8.7 years (range: 2-12.4 years). Nine patients (18%) died, 5 with ischemic stroke and 4 with hemorrhagic stroke. Among the 5 cases of death with ischemic stroke, 3 involved hemorrhagic transformation before death. Seven patients (77%) died within 31 days (range: 2-31 days), whereas the other 2 died 6 months and 2.5 years after the episode. Recurrence occurred in 5 cases (10%). Long-term neurologic deficits occurred among 41% of survivors, including mental retardation (N = 11), epilepsy (N = 7), and hemiplegia (N = 10). The functional deficits were classified as severe in 7 cases, moderate in 3 cases, and mild in 7 cases, for patients with long-term neurologic deficits. Decreased levels of consciousness, hematologic causes, and hemorrhagic transformation (applicable only in ischemic stroke) were significant risk factors associated with high mortality rates. For the 41 patients who survived, the only significant risk factor for long-term neurologic deficits was seizures at the initial presentation. Other factors, such as gender, age, other clinical features, stroke type, vascular territory, other causes, and recurrence of stroke, were all insignificant for both death and long-term deficits. The 3 risk factors identified for death were analyzed in multivariate logistic regression analyses, with adjustment for the confounding variables, and only decreased levels of consciousness remained significant (odds ratio = 15.6).

CONCLUSIONS

The incidence of stroke among Chinese children was slightly lower than that in Europe or North America. The etiologic pattern was different in our cohort, and there was no sickle cell anemia, thrombophilia, or sinovenous thrombosis. Despite these differences, however, mortality and long-term neurologic deficit rates were similar.

Misplaced peripherally inserted central catheter: an unusual cause of stroke

Stroke in pediatric patients occurs with a frequency of 3 to 8 per 100,000. The postevent evaluation attempts to identify the etiology of ischemia whether anatomic, hematologic, or embolic, with the intention of preventing future events. We present the case of a previously healthy male who developed unilateral facial and extremity weakness 2 weeks after receiving an appendectomy. Once the usual etiologies of stroke in pediatric patients were excluded, an evaluation of the peripheral venous catheter (placed for postoperative antibiotic delivery) demonstrated arterial misplacement. This article presents the first reported case of such an occurrence in the literature and exhibits the need to pursue all avenues of evaluation if the etiology of a pediatric stroke is not initially identified.

Fetal stroke

Fetal stroke, or that which occurs between 14 weeks of gestation and the onset of labor resulting in delivery, has been associated with postnatal epilepsy, mental retardation, and cerebral palsy. The entity is caused by antenatal ischemic, thrombotic, or hemorrhagic injury. We present seven new cases of fetal stroke diagnosed in utero and review the 47 cases reported in the literature. Although risk factors could not be assigned to 50% of the fetuses with stroke, the most common maternal conditions associated with fetal stroke were alloimmune thrombocytopenia and trauma. Magnetic resonance imaging was optimal for identifying fetal stroke, and prenatal imaging revealed hemorrhagic lesions in over 90% of studies; porencephalies were identified in just 13%. Seventy-eight percent of cases with reported outcome resulted in either death or adverse neurodevelopmental outcome at ages 3 months to 6 years. Fetal stroke appears to have different risk factors, clinical characteristics, and outcomes than other perinatal or childhood stroke syndromes. A better understanding of those risk factors predisposing a fetus to cerebral infarction may provide a basis for future therapeutic intervention trials. Ozduman K, Pober BR, Barnes P, Copel JA, Ogle EA, Duncan CC, Ment LR. Fetal stroke.

Central nervous system vasculitis in children

PURPOSE OF THE REVIEW

To summarize the current literature on central nervous system vasculitis in childhood because this condition remains a diagnostic and therapeutic challenge.

RECENT FINDINGS

Central nervous system vasculitis in childhood may be primary or secondary to a variety of conditions including infections, collagen vascular diseases, systemic vasculitides, and malignancies. Conditions that result in vasospasm or are associated with noninflammatory vasculopathies may mimic the features of central nervous system vasculitis. Recent studies have described the clinical spectrum of CNS vasculitis in childhood. The most common presenting features are headaches and focal neurologic deficits. The diagnosis of central nervous system vasculitis remains particularly difficult because the available investigative modalities have limited sensitivities and specificities. The most helpful diagnostic tests include cerebrospinal fluid analysis, MRI of the brain, and angiography. However, brain biopsy may be required to diagnose small vessel vasculitis.

SUMMARY

This review summarizes recent data on primary central nervous system vasculitis and some of the secondary CNS vasculitides in children. Awareness of the presenting clinical features of CNS vasculitis should lead to consideration of the diagnosis. Awareness of the sensitivity and specificity of the various diagnostic tests should lead to the more prudent use of invasive diagnostic tests including angiography and brain biopsy.