Assessment of MR blood-oxygen-level-dependent (BOLD) cerebrovascular reactivity under general anesthesia in children with moyamoya

BACKGROUND

Moyamoya is a progressive, non-atherosclerotic cerebral arteriopathy that may present in childhood and currently has no cure. Early diagnosis is critical to prevent a lifelong risk of neurological morbidity. Blood-oxygen-level-dependent (BOLD) MRI cerebrovascular reactivity (CVR) imaging provides a non-invasive, in vivo measure of autoregulatory capacity and cerebrovascular reserve. However, non-compliant or younger children require general anesthesia to achieve BOLD-CVR imaging.

OBJECTIVE

To determine the same-day repeatability of BOLD-CVR imaging under general anesthesia in children with moyamoya.

MATERIALS AND METHODS

Twenty-eight examination pairs were included (mean patient age = 7.3 ± 4.0 years). Positive and negatively reacting voxels were averaged over signals and counted over brain tissue and vascular territory. The intraclass correlation coefficient (ICC), Wilcoxon signed-rank test, and Bland-Altman plots were used to assess the variability between the scans.

RESULTS

There was excellent-to-good (≥ 0.59) within-day repeatability in 18 out of 28 paired studies (64.3%). Wilcoxon signed-rank tests demonstrated no significant difference in the grey and white matter CVR estimates, between repeat scans (all p-values > 0.05). Bland-Altman plots of differences in mean magnitude of positive and negative and fractional positive and negative CVR estimates illustrated a reasonable degree of agreement between repeat scans and no systematic bias.

CONCLUSION

BOLD-CVR imaging provides repeatable assessment of cerebrovascular reserve in children with moyamoya imaged under general anesthesia.

Health Inequity and Time From Pediatric Stroke Onset to Arrival

BACKGROUND

Time from stroke onset to hospital arrival determines treatment and impacts outcome. Structural, socioeconomic, and environmental factors are associated with health inequity and onset-to-arrival in adult stroke. We aimed to assess the association between health inequity and onset-to-arrival in a pediatric comprehensive stroke center.

METHODS

A retrospective observational study was conducted on a consecutive cohort of children (>28 days-18 years) diagnosed with acute arterial ischemic stroke (AIS) between 2004 and 2019. Neighborhood-level material deprivation was derived from residential postal codes and used as a proxy measure for health inequity. Patients were stratified by level of neighborhood-level material deprivation, and onset-to-arrival was categorized into 3 groups: <6, 6 to 24, and >24 hours. Association between neighborhood-level material deprivation and onset-to-arrival was assessed in multivariable ordinal logistic regression analyses adjusting for sociodemographic and clinical factors.

RESULTS

Two hundred and twenty-nine children were included (61% male; median age [interquartile range] at stroke diagnosis 5.8-years [1.1-11.3]). Over the 16-year study period, there was an increase in proportion of children diagnosed with AIS living in the most deprived neighborhoods and arriving at the emergency room within 6 hours (P=0.01). Among Asian patients, a higher proportion lived in the most deprived neighborhoods (P=0.02) and level of material deprivation was associated with AIS risk factors (P=0.001).

CONCLUSIONS

Our study suggests an increase in pediatric stroke in deprived neighborhoods and certain communities, and earlier arrival times to the emergency room over time. However, whether these changes are due to an increase in incidence of childhood AIS or increased awareness and diagnosis is yet to be determined. The association between AIS risk factors and material deprivation highlights the intersectionality of clinical factors and social determinants of health. Finally, whether material deprivation impacts onset-to-arrival is likely complex and requires further examination.

Long-term clinical and radiological trajectories of craniocervical vasculopathy in children with PHACE syndrome

AIM

To describe the rates of stroke and craniocervical vasculopathy progression in children with posterior fossa malformations, hemangioma, arterial anomalies, coarctation of the aorta/cardiac defects, and eye abnormalities (PHACE) syndrome.

METHOD

A single-center, retrospective natural history study of children with PHACE syndrome. Clinical and sequential neuroimaging data were reviewed to study the characteristics and progression of vasculopathy and calculate the rates of arterial ischemic stroke (AIS) and transient ischemic stroke (TIA). Vasculopathy progression was defined as worsening or new vascular findings on follow-up magnetic resonance angiography.

RESULTS

Thirty-four children with cerebrovascular abnormalities at the PHACE syndrome diagnosis were studied (age range = 2 to 18 years, 85% females). Median age at the initial diagnosis was 5.5 months (interquartile range = 1-52 months); median age at the last follow-up was 8 years 6 months (range = 2-18 years). Overall, 10 (29%) patients had radiological progression of their vasculopathy, with a cumulative progression-free rate of 73% (95% confidence interval [CI] = 0.57-0.89), and a cumulative TIA-free and AIS-free rate of 87% (95% CI = 0.745-0.99). Vasculopathy was continuously progressive in six patients (18%) at the last follow-up. Three patients (9%) had TIA and all had progressive vasculopathy. One patient had presumed perinatal AIS at the initial PHACE diagnosis, while no other patient experienced an AIS during the follow-up.

INTERPRETATION

In children with PHACE syndrome, craniocervical vasculopathy is non-progressive and asymptomatic in the majority of cases. The risk of ischemic stroke in these children is very low. Larger and prospective studies are necessary to confirm these findings.

Network localization of pediatric lesion-induced dystonia

Objective

Dystonia is a movement disorder defined by involuntary muscle contractions leading to abnormal postures or twisting and repetitive movements. Classically dystonia has been thought of as a disorder of the basal ganglia, but newer results in idiopathic dystonia and lesion-induced dystonia in adults point to broader motor network dysfunction spanning the basal ganglia, cerebellum, premotor cortex, sensorimotor, and frontoparietal regions. It is unclear whether a similar network is shared between different etiologies of pediatric lesion-induced dystonia.

Methods

Three cohorts of pediatric patients with lesion-induced dystonia were identified. The lesion etiologies included hypoxia, kernicterus, and stroke versus comparison subjects with acquired lesions not associated with dystonia. Multivariate lesion-symptom mapping and lesion network mapping were used to evaluate the anatomy and networks associated with dystonia.

Results

Multivariate lesion-symptom mapping showed that lesions of the putamen (stroke: r = 0.50, p <0.01; hypoxia, r = 0.64, p <0.001) and globus pallidus (kernicterus, r = 0.61, p <0.01) were associated with dystonia. Lesion network mapping using normative connectome data from healthy children demonstrated that these regional findings occurred within a common brain-wide network that involves the basal ganglia, anterior and medial cerebellum, and cortical regions that overlap the cingulo-opercular and somato-cognitive-action networks.

Interpretation

We interpret these findings as novel evidence for a unified dystonia brain network that involves the somato-cognitive-action network, which is involved in higher order coordination of movement. Elucidation of this network gives insight into the functional origins of dystonia and provides novel targets to investigate for therapeutic intervention.

Social skill and social withdrawal outcomes in children following pediatric stroke

Pediatric stroke can result in long-term impairments across attention, functional communication and motor domains. The current paper utilized parent reports of the Behavioral Assessment System for Children 2nd Edition and the Pediatric Stroke Outcome Measure to examine children's social skills and withdrawal behavior within a pediatric stroke population. Using the Canadian Pediatric Stroke Registry at The Hospital for Sick Children, data were analyzed for 312 children with ischemic stroke. Children with ischemic stroke demonstrated elevated parent-reported social skills problems (observed = 20.51%, expected = 14.00%) and clinically elevated social withdrawal (observed = 11.21%, expected = 2.00%). Attentional problems significantly contributed to reduced social skills, F (3,164) = 30.68, p < 0.01, while attentional problems and neurological impairments accounted for increased withdrawal behavior, F (2, 164) = 7.47, p < 0.01. The presence of a motor impairment was associated with higher social withdrawal compared to individuals with no motor impairment diagnosis, t(307.73) = 2.25, p < .025, d = 0.25, 95% CI [0.42, 6.21]. The current study demonstrates that children with stroke who experience motor impairments, attentional problems, reduced functional communication skills, and neurological impairments can experience deficits in their social skills and withdrawal behavior.

Pediatric Moyamoya Revascularization Perioperative Care: A Modified Delphi Study

BACKGROUND

Surgical revascularization decreases the long-term risk of stroke in children with moyamoya arteriopathy but can be associated with an increased risk of stroke during the perioperative period. Evidence-based approaches to optimize perioperative management are limited and practice varies widely. Using a modified Delphi process, we sought to establish expert consensus on key components of the perioperative care of children with moyamoya undergoing indirect revascularization surgery and identify areas of equipoise to define future research priorities.

METHODS

Thirty neurologists, neurosurgeons, and intensivists practicing in North America with expertise in the management of pediatric moyamoya were invited to participate in a three-round, modified Delphi process consisting of a 138-item practice patterns survey, anonymous electronic evaluation of 88 consensus statements on a 5-point Likert scale, and a virtual group meeting during which statements were discussed, revised, and reassessed. Consensus was defined as ≥ 80% agreement or disagreement.

RESULTS

Thirty-nine statements regarding perioperative pediatric moyamoya care for indirect revascularization surgery reached consensus. Salient areas of consensus included the following: (1) children at a high risk for stroke and those with sickle cell disease should be preadmitted prior to indirect revascularization; (2) intravenous isotonic fluids should be administered in all patients for at least 4 h before and 24 h after surgery; (3) aspirin should not be discontinued in the immediate preoperative and postoperative periods; (4) arterial lines for blood pressure monitoring should be continued for at least 24 h after surgery and until active interventions to achieve blood pressure goals are not needed; (5) postoperative care should include hourly vital signs for at least 24 h, hourly neurologic assessments for at least 12 h, adequate pain control, maintaining normoxia and normothermia, and avoiding hypotension; and (6) intravenous fluid bolus administration should be considered the first-line intervention for new focal neurologic deficits following indirect revascularization surgery.

CONCLUSIONS

In the absence of data supporting specific care practices before and after indirect revascularization surgery in children with moyamoya, this Delphi process defined areas of consensus among neurosurgeons, neurologists, and intensivists with moyamoya expertise. Research priorities identified include determining the role of continuous electroencephalography in postoperative moyamoya care, optimal perioperative blood pressure and hemoglobin targets, and the role of supplemental oxygen for treatment of suspected postoperative ischemia.

Predictors of neurocognitive outcome in pediatric ischemic and hemorrhagic stroke

This clinical study examined the impact of eight predictors (age at stroke, stroke type, lesion size, lesion location, time since stroke, neurologic severity, seizures post-stroke, and socioeconomic status) on neurocognitive functioning following pediatric stroke. Youth with a history of pediatric ischemic or hemorrhagic stroke (n = 92, ages six to 25) underwent neuropsychological testing and caregivers completed parent-report questionnaires. Hospital records were accessed for medical history. Spline regressions, likelihood ratios, one-way analysis of variance, Welch's t-tests, and simple linear regressions examined associations between predictors and neuropsychological outcome measures. Large lesions and lower socioeconomic status were associated with worse neurocognitive outcomes across most neurocognitive domains. Ischemic stroke was associated with worse outcome in attention and executive functioning compared to hemorrhagic stroke. Participants with seizures had more severe executive functioning impairments than participants without seizures. Youth with cortical-subcortical lesions scored lower on a few measures than youth with cortical or subcortical lesions. Neurologic severity predicted scores on few measures. No differences were found based on time since stroke, lesion laterality, or supra- versus infratentorial lesion. In conclusion, lesion size and socioeconomic status predict neurocognitive outcome following pediatric stroke. An improved understanding of predictors is valuable to clinicians who have responsibilities related to neuropsychological assessment and treatments for this population. Findings should inform clinical practice through enhanced appraisals of prognosis and the use of a biopsychosocial approach when conceptualizing neurocognitive outcome and setting up support services aimed at fostering optimal development for youth with stroke.

Comprehensive whole-genome sequence analyses provide insights into the genomic architecture of cerebral palsy

We performed whole-genome sequencing (WGS) in 327 children with cerebral palsy (CP) and their biological parents. We classified 37 of 327 (11.3%) children as having pathogenic/likely pathogenic (P/LP) variants and 58 of 327 (17.7%) as having variants of uncertain significance. Multiple classes of P/LP variants included single-nucleotide variants (SNVs)/indels (6.7%), copy number variations (3.4%) and mitochondrial mutations (1.5%). The COL4A1 gene had the most P/LP SNVs. We also analyzed two pediatric control cohorts (n = 203 trios and n = 89 sib-pair families) to provide a baseline for de novo mutation rates and genetic burden analyses, the latter of which demonstrated associations between de novo deleterious variants and genes related to the nervous system. An enrichment analysis revealed previously undescribed plausible candidate CP genes (SMOC1, KDM5B, BCL11A and CYP51A1). A multifactorial CP risk profile and substantial presence of P/LP variants combine to support WGS in the diagnostic work-up across all CP and related phenotypes.

Predictors of externalizing behavior outcomes following pediatric stroke

Children who experience pediatric stroke are at higher risk for future behavioral problems in childhood. We examined the prevalence of parent reported externalizing behaviors and executive function problems in children following stroke and neurological predictors. This study included 210 children with pediatric ischemic stroke (mean age 9.18 years (SD = 3.95)). The parent form of the Behavioral Assessment System for Children-Second Edition (BASC-2) and Behavior Rating Inventory of Executive Function (BRIEF) were used to evaluate externalizing behavior and executive function. No externalizing behavior or executive function differences were found between perinatal (n = 94) or childhood (n = 116) stoke, except for the shift subscale which had higher T-scores among the perinatal group (M = 55.83) than childhood group (M = 50.40). When examined together, 10% of children had clinically elevated hyperactivity T-scores as opposed to the expected 2%. Parents endorsed higher ratings of concern on the behavior regulation and metacognition indices of the BRIEF. Externalizing behaviors were correlated moderately to strongly with executive functions (r = 0.42 to 0.74). When examining neurological and clinical predictors of externalizing behaviors, only female gender was predictive of increased hyperactivity (p = .004). However, there were no significant gender differences in diagnosis of attention deficit hyperactivity disorder (ADHD). In summary, in this cohort, children with perinatal and childhood stroke did not differ on parent reported externalizing behavior or executive function outcomes. However, compared to normative data, children with perinatal or childhood stroke are significantly more likely to experience clinically elevated levels of hyperactivity.

Executive functioning, ADHD symptoms and resting state functional connectivity in children with perinatal stroke

Perinatal stroke describes a group of focal, vascular brain injuries that occur early in development, often resulting in lifelong disability. Two types of perinatal stroke predominate, arterial ischemic stroke (AIS) and periventricular venous infarction (PVI). Though perinatal stroke is typically considered a motor disorder, other comorbidities commonly exist including attention-deficit hyperactivity disorder (ADHD) and deficits in executive function. Rates of ADHD symptoms are higher in children with perinatal stroke and deficits in executive function may also occur but underlying mechanisms are not known. We measured resting state functional connectivity in children with perinatal stroke using previously established dorsal attention, frontoparietal, and default mode network seeds. Associations with parental ratings of executive function and ADHD symptoms were examined. A total of 120 participants aged 6-19 years [AIS N = 31; PVI N = 30; Controls N = 59] were recruited. In comparison to typically developing peers, both the AIS and PVI groups showed lower intra- and inter-hemispheric functional connectivity values in the networks investigated. Group differences in between-network connectivity were also demonstrated, showing weaker anticorrelations between task-positive (frontoparietal and dorsal attention) and task-negative (default mode) networks in stroke groups compared to controls. Both within-network and between-network functional connectivity values were highly associated with parental reports of executive function and ADHD symptoms. These results suggest that differences in functional connectivity exist both within and between networks after perinatal stroke, the degree of which is associated with ADHD symptoms and executive function.

Adjusting to life after pediatric stroke: A qualitative study

AIM

To examine adjustment after stroke in adolescence from the perspective of affected young people.

METHOD

Fourteen participants (10 female) aged 13 to 25 years with a history of ischemic or hemorrhagic stroke in adolescence participated in one-on-one semi-structured interviews at the Hospital for Sick Children, Toronto, Canada. Interviews were audio-recorded and transcribed verbatim. Two independent coders conducted a reflexive thematic analysis.

RESULTS

Five themes were identified as representative of adjustment after stroke: (1) 'Processing the story'; (2) 'Loss and challenges'; (3) 'I've changed'; (4) 'Keys to recovery'; and (5) 'Adjustment and acceptance'.

INTERPRETATION

This qualitative study provides medical professionals with a personal, patient-driven lens through which to better understand the challenges of adjusting to life after pediatric stroke. Findings highlight the need to provide mental health support to patients to assist them in processing their stroke and adapting to long-lasting sequelae.

WHAT THIS PAPER ADDS

Processing the onset event is a key component of adjustment to stroke. Feelings of anxiety, sadness, frustration, and self-consciousness impede adjustment to stroke. Young people may feel overwhelmed academically owing to neurocognitive deficits. Sequelae may rid young people of hobbies and passions, and alter plans for the future. To adjust to stroke, survivors draw on resilience, patience, determination, and social support.

Association Between Thrombectomy and Functional Outcomes in Pediatric Patients With Acute Ischemic Stroke From Large Vessel Occlusion

Importance

Pediatric large vessel occlusion (LVO) stroke has a poor natural history. However, uptake of mechanical thrombectomy is hindered by a lack of clinical trial data in children. A randomized clinical trial is not feasible due to small sample sizes and absence of equipoise.

Objective

To evaluate whether pediatric patients with acute LVO stroke who undergo thrombectomy have better clinical outcomes than matched patients managed conservatively.

Design, Setting, and Participants

This matched case-control study used pooled stroke registry data from 5 tertiary referral hospitals in Australia and Canada from January 2011 to April 2022. Patients were aged 1 month to younger than 18 years with acute LVO stroke. Pooled data identified 31 thrombectomy patients and 46 control patients. Five patients undergoing thrombectomy with basilar artery occlusion were excluded due to insufficient controls. Using a hierarchal matching system (site of occlusion, age group, side of occlusion, and sex), deidentified consensus matching of patients and controls was undertaken while blinded to clinical outcome. Data were analyzed from July to November 2022.

Exposure

In the case cohort, mechanical thrombectomy was undertaken for management of acute LVO stroke. The control cohort received medical treatment only.

Main Outcomes and Measures

The primary outcome was the functional clinical status 3 months following stroke, measured by the pediatric modified Rankin Scale (mRS). Clinical outcomes were compared between groups using ordinal regression analysis.

Results

Of 52 included patients, 31 (60%) were male, and the mean (SD) age was 10.3 (4.4) years. Matching was achieved for 26 children undergoing thrombectomy with 26 controls. There was no significant difference between groups for site or side of occlusion, age, sex, etiology, thrombolysis status, baseline Alberta Stroke Programme Early CT Score, or time since last seen well to presentation. Patients undergoing thrombectomy had superior clinical outcomes than control patients at 3 months on the pediatric mRS (odds ratio, 3.76; 95% CI, 1.32-10.67; P = .01). These superior outcomes were maintained at final follow-up (odds ratio, 3.65; 95% CI, 1.25-10.68; P = .02).

Conclusions and Relevance

In the absence of a randomized clinical trial, this case-control study demonstrates better clinical outcomes with thrombectomy than medical management alone for pediatric patients aged 2 to 18 years with anterior circulation LVO stroke.

Alterations in cortical morphometry of the contralesional hemisphere in children, adolescents, and young adults with perinatal stroke

Perinatal stroke causes most hemiparetic cerebral palsy and cognitive dysfunction may co-occur. Compensatory developmental changes in the intact contralesional hemisphere may mediate residual function and represent targets for neuromodulation. We used morphometry to explore cortical thickness, grey matter volume, gyrification, and sulcal depth of the contralesional hemisphere in children, adolescents, and young adults after perinatal stroke and explored associations with motor, attention, and executive function. Participants aged 6-20 years (N = 109, 63% male) with unilateral perinatal stroke underwent T1-weighted imaging. Participants had arterial ischemic stroke (AIS; n = 36), periventricular venous infarction (PVI; n = 37) or were controls (n = 36). Morphometry was performed using the Computational Anatomy Toolbox (CAT12). Group differences and associations with motor and executive function (in a smaller subsample) were assessed. Group comparisons revealed areas of lower cortical thickness in contralesional hemispheres in both AIS and PVI and greater gyrification in AIS compared to controls. Areas of greater grey matter volume and sulcal depth were also seen for AIS. The PVI group showed lower grey matter volume in cingulate cortex and less volume in precuneus relative to controls. No associations were found between morphometry metrics, motor, attention, and executive function. Cortical structure of the intact contralesional hemisphere is altered after perinatal stroke. Alterations in contralesional cortical morphometry shown in perinatal stroke may be associated with different mechanisms of damage or timing of early injury. Further investigations with larger samples are required to more thoroughly explore associations with motor and cognitive function.

The development of the pediatric stroke neuroimaging platform (PEDSNIP)

Childhood stroke occurs from birth to 18 years of age, ranks among the top ten childhood causes of death, and leaves lifelong neurological impairments. Arterial ischemic stroke in infancy and childhood occurs due to arterial occlusion in the brain, resulting in a focal lesion. Our understanding of mechanisms of injury and repair associated with focal injury in the developing brain remains rudimentary. Neuroimaging can reveal important insights into these mechanisms. In adult stroke population, multi-center neuroimaging studies are common and have accelerated the translation process leading to improvements in treatment and outcome. These studies are centered on the growing evidence that neuroimaging measures and other biomarkers (e.g., from blood and cerebrospinal fluid) can enhance our understanding of mechanisms of risk and injury and be used as complementary outcome markers. These factors have yet to be studied in pediatric stroke because most neuroimaging studies in this population have been conducted in single-centred, small cohorts. By pooling neuroimaging data across multiple sites, larger cohorts of patients can significantly boost study feasibility and power in elucidating mechanisms of brain injury, repair and outcomes. These aims are particularly relevant in pediatric stroke because of the decreased incidence rates and the lack of mechanism-targeted trials. Toward these aims, we developed the Pediatric Stroke Neuroimaging Platform (PEDSNIP) in 2015, funded by The Brain Canada Platform Support Grant, to focus on three identified neuroimaging priorities. These were: developing and harmonizing multisite clinical protocols, creating the infrastructure and methods to import, store and organize the large clinical neuroimaging dataset from multiple sites through the International Pediatric Stroke Study (IPSS), and enabling central searchability. To do this, developed a two-pronged approach that included building 1) A Clinical-MRI Data Repository (standard of care imaging) linked to clinical data and longitudinal outcomes and 2) A Research-MRI neuroimaging data set acquired through our extensive collaborative, multi-center, multidisciplinary network. This dataset was collected prospectively in eight North American centers to test the feasibility and implementation of harmonized advanced Research-MRI, with the addition of clinical information, genetic and proteomic studies, in a cohort of children presenting with acute ischemic stroke. Here we describe the process that enabled the development of PEDSNIP built to provide the infrastructure to support neuroimaging research priorities in pediatric stroke. Having built this Platform, we are now able to utilize the largest neuroimaging and clinical data pool on pediatric stroke data worldwide to conduct hypothesis-driven research. We are actively working on a bioinformatics approach to develop predictive models of risk, injury and repair and accelerate breakthrough discoveries leading to mechanism-targeted treatments that improve outcomes and minimize the burden following childhood stroke. This unique transformational resource for scientists and researchers has the potential to result in a paradigm shift in the management, outcomes and quality of life in children with stroke and their families, with far-reaching benefits for other brain conditions of people across the lifespan.

Language and Cognitive Outcomes Following Ischemic Stroke in Children With Monolingual and Bilingual Exposure

Aim: Although many children who experience ischemic stroke come from bilingual backgrounds, it is unclear whether bilingual exposure affects poststroke development. Our research evaluates bilingual and monolingual exposure on linguistic/cognitive development poststroke across 3 stroke-onset groups. Method: An institutional stroke registry and medical charts were used to gather data on 237 children across 3 stroke-onset groups: neonatal, <28 days; first-year, 28 days to 12 months; and childhood, 13 months to 18 years. The Pediatric Stroke Outcome Measure (PSOM), administered several times poststroke, was used to evaluate cognition and linguistic development. Results: Similar cognitive outcomes were observed across language groups. However, an interaction effect with stroke-onset group was observed, with monolinguals in the first-year group having worse productive language outcomes as compared to bilinguals. Interpretation: Overall, no detrimental effects of bilingualism were found on children's poststroke cognition and linguistic development. Our study suggests that a bilingual environment may facilitate language development in children poststroke.

Bridging clinical care and research in Ontario, Canada: Maximizing diagnoses from reanalysis of clinical exome sequencing data

We examined the utility of clinical and research processes in the reanalysis of publicly-funded clinical exome sequencing data in Ontario, Canada. In partnership with eight sites, we recruited 287 families with suspected rare genetic diseases tested between 2014 and 2020. Data from seven laboratories was reanalyzed with the referring clinicians. Reanalysis of clinically relevant genes identified diagnoses in 4% (13/287); four were missed by clinical testing. Translational research methods, including analysis of novel candidate genes, identified candidates in 21% (61/287). Of these, 24 families have additional evidence through data sharing to support likely diagnoses (8% of cohort). This study indicates few diagnoses are missed by clinical laboratories, the incremental gain from reanalysis of clinically-relevant genes is modest, and the highest yield comes from validation of novel disease-gene associations. Future implementation of translational research methods, including continued reporting of compelling genes of uncertain significance by clinical laboratories, should be considered to maximize diagnoses.

Abstract TP159: Association Of Lesion Characteristics And Neurological Outcomes In Neonatal Arterial Ischemic Stroke Patients

Background: Neonatal arterial ischemic stroke (NAIS) occurs as a result of an acute focal cerebral arterial infarction between birth and 28 days of life in nearly 1:2500 live births. As there are few studies examining the relationship between NAIS lesion characteristics and clinical outcomes, this study aims to determine if lesion volume and lesion location are associated with abnormal neurological outcomes in NAIS.

Methods: Semi-automated lesion segmentation of co-registered multi-modal images was conducted using ITK-SNAP. Semi-automated lesion segmentations with manual corrections were performed using ITK-SNAP software. Lesion volumes were corrected for head size by dividing lesion volumes by total intracranial volume, and correlated (using Kendall's Tau-b [τ b ]) with neurological outcome that was assessed with the Pediatric Stroke Outcome Measure (PSOM).

Results: Participants included N=20 NAIS patients (mean [M] weeks gestation=39.5, +/-1.64; 55% male, 70% single infarct, 75% left-sided lesions). Outcome was assessed an average of 312, +/-7.6 days post-stroke. Neurological deficits were present in 50% (with seizures in 85%) at time of stroke, and infarct locations most commonly involved supratentorial cortical structures (75%), however none were correlated with outcome. Larger lesion volumes (M=5.35 mm 3 , +/-0.069) were correlated with poor outcome (τ b =.444, p=0.02).

Conclusion: We found larger lesion volume to be associated with atypical clinical outcomes following NAIS. Further analysis is in progress that include changes over time in lesion characteristics and outcome. These results demonstrate a need for better characterize the relationship between lesion characteristics and outcomes in NAIS.

Abstract 159: Impact Of Health Inequities On Outcomes Of Stroke In Children

Introduction: Recent studies have reported access to initial imaging and underlying chronic disorders to be associated with post-stroke outcome in children. However, the influence of sociodemographic factors is yet to be investigated within the Canadian context. Our study explored the role of health inequities while considering the influence of clinical and radiological factors on post-stroke outcomes.

Methods: A consecutive cohort of children &gt;28 days-18 years of age diagnosed with arterial ischemic stroke between 2004 and 2019 at a comprehensive stroke centre in Ontario were included. Patient residential postal codes were linked to the Ontario Marginalization Index including area-level data on income, education, single-parent families, and housing quality. Post-stroke outcomes were assessed using the validated Pediatric Stroke Outcome Measure - Severity Classification System (PSOM-SCS). Poor outcome was defined as moderate-to-severe deficit at discharge or at 18 months from the onset of stroke. Univariable and multivariable logistic regression models were developed to examine the influence of material deprivation on neurological outcomes while controlling for demographic, clinical, and radiological factors.

Results: Amongst 234 children, predictors of poor outcome at discharge included moderate-to-severe stroke at presentation (OR = 4.00, p &lt; 0.05) while the presence of a single infarct may protect the patient from poor outcome at discharge (OR = 0.32, p &lt; 0.05). Predictors of poor outcome at 18 months post-stroke included patients from moderately deprived neighborhoods (OR = 5.36, p &lt; 0.05), stroke onset between 2014 and 2019 (OR = 7.44, p &lt; 0.05), or presence of a left cerebral hemispheric infarction (OR = 8.20, p &lt; 0.05).

Conclusion: Our study demonstrated that stroke severity and the number of infarcts were important in determining outcome at discharge whereas neighbourhood-level material deprivation, year of onset, and infarct location predicted outcome at 18 months from the onset of stroke. Further research is needed to explore the role of broader social determinants of health in predicting stroke outcomes longitudinally over time.

Abstract TMP22: Exploring The Impact Of Material Deprivation, Clinical, And Radiological Features On Neurological Outcomes Of Neonatal Stroke

Introduction: Neonatal arterial ischemic stroke (AIS) is an important cause of neurologic disability in children. No research to date has examined the influence of determinants of health on outcomes in a neonatal AIS population. This study examined whether neighbourhood-level material deprivation was associated with long-term neurological outcomes in neonatal AIS patients, after accounting for the influence of clinical and radiological factors.

Methods: Patients with neonatal AIS between 2004 and 2019 at a comprehensive stroke centre were included. The Ontario Marginalization Index (ON-Marg) was used to assess neighbourhood-level material deprivation. Participant postal codes were linked to census data and ON-Marg scores were reported. Neurological outcomes were assessed using the Pediatric Stroke Outcome Measure Severity Classification Scale (PSOM-SCS) at latest follow up (median = 49 months, range = 12 to 187 months). A poor outcome was defined as any neurologic deficit (i.e., mild, moderate, or severe). Univariable and multivariable logistic regression models were developed.

Results: Amongst 154 participants, the majority of scores (66.23%) were within the normal range. Remaining participants demonstrated neurological deficits, including 25.97% mild and 7.79% moderate-to-severe. Predictors of poor outcome in the multivariable model included hemiparesis at stroke presentation (OR = 12.81, p &lt; 0.05) and basal ganglia involvement (OR = 3.68, p &lt; 0.05). Neighbourhood-level material deprivation was not significantly associated with poor outcome.

Conclusions: Hemiparesis and basal ganglia involvement are important in determining long-term outcomes. Although material deprivation was not associated with poor outcomes in our study, it may be associated with neurological outcomes at later ages. Further research is needed to understand the role of socioeconomic factors in a neonatal stroke population, including the measurement of individual-level indicators and outcomes at later ages post-stroke. While outcomes after neonatal stroke are generally favourable, identifying predictors of poor outcomes may assist clinicians in developing a more precise risk evaluation regarding recovery after stroke.

Neuroimaging in Pediatric Stroke

Pediatric stroke is unfortunately not a rare condition. It is associated with severe disability and mortality because of the complexity of potential clinical manifestations, and the resulting delay in seeking care and in diagnosis. Neuroimaging plays an important role in the multidisciplinary response for pediatric stroke patients. The rapid development of adult endovascular thrombectomy has created a new momentum in health professionals caring for pediatric stroke patients. Neuroimaging is critical to make decisions of identifying appropriate candidates for thrombectomy. This review article will review current neuroimaging techniques, imaging work-up strategies and special considerations in pediatric stroke. For resources limited areas, recommendation of substitute imaging approaches will be provided. Finally, promising new techniques and hypothesis-driven research protocols will be discussed.

Pediatric Moyamoya Biomarkers: Narrowing the Knowledge Gap

Moyamoya is a progressive cerebrovascular disorder that leads to stenosis of the arteries in the distal internal carotid, proximal middle cerebral and proximal anterior cerebral arteries of the circle of Willis. Typically a network of collaterals form to bypass the stenosis and maintain cerebral blood flow. As moyamoya progresses it affects the anterior circulation more commonly than posterior circulation, and cerebral blood flow becomes increasingly reliant on external carotid supply. Children with moyamoya are at increased risk for ischemic symptoms including stroke and transient ischemic attacks (TIA). In addition, cognitive decline may occur over time, even in the absence of clinical stroke. Standard of care for stroke prevention in children with symptomatic moyamoya is revascularization surgery. Treatment of children with asymptomatic moyamoya with revascularization surgery however remains more controversial. Therefore, biomarkers are needed to assist with not only diagnosis but also with determining ischemic risk and identifying best surgical candidates. In this review we will discuss the current knowledge as well as gaps in research in relation to pediatric moyamoya biomarkers including neurologic presentation, cognitive, neuroimaging, genetic and biologic biomarkers of disease severity and ischemic risk.

Closing the Gap in Pediatric Hemorrhagic Stroke: A Systematic Review

Pediatric hemorrhagic stroke (HS) accounts for a large proportion of childhood strokes, 1 of the top 10 causes of pediatric deaths. Morbidity and mortality lead to significant socio-economic and psychosocial burdens. To understand published data on recognizing and managing children with HS, we conducted a systematic review of the literature presented here. We searched PubMed, Embase, CINAHL and the Cochrane Library databases limited to English language and included 174 studies, most conducted in the USA (52%). Terminology used interchangeably for HS included intraparenchymal/intracranial hemorrhage, spontaneous ICH, and cerebrovascular accident (CVA). Key assessments informing prognosis and management included clinical scoring (Glasgow coma scale), and neuroimaging. HS etiologies reported were systemic coagulopathy (genetic, acquired pathologic, or iatrogenic), or focal cerebrovascular lesions (brain arteriovenous malformations, cavernous malformations, aneurysms, or tumor vascularity). Several scales were used to measure outcome: Glasgow outcome score (GOS), Kings outcome score for head injury (KOSCHI), modified Rankin scale (mRS) and pediatric stroke outcome measure (PSOM). Most studies described treatments of at-risk lesions. Few studies described neurocritical care management including raised ICP, seizures, vasospasm, or blood pressure. Predictors of poor outcome included ethnicity, comorbidity, location of bleed, and hematoma &gt;2% of total brain volume. Motor and cognitive outcomes followed independent patterns. Few studies reported on cognitive outcomes, rehabilitation, and transition of care models. Interdisciplinary approach to managing HS is urgently needed, informed by larger cohort studies targeting key clinical question (eg development of a field-guide for the clinician managing patients with HS that is reproducible internationally).

Fronto-Parietal and White Matter Haemodynamics Predict Cognitive Outcome in Children with Moyamoya Independent of Stroke

Moyamoya disease is a major arteriopathy characterised by progressive steno-occlusion of the arteries of the circle of Willis. Studies in adults with moyamoya suggest an association between abnormal fronto-parietal and white matter regional haemodynamics and cognitive impairments, even in the absence of focal infarction. However, these associations have not been investigated in children with moyamoya. We examined the relationship between regional haemodynamics and ratings of intellectual ability and executive function, using hypercapnic challenge blood oxygen level-dependent magnetic resonance imaging of cerebrovascular reactivity in a consecutive cohort of children with confirmed moyamoya. Thirty children were included in the final analysis (mean age: 12.55 ± 3.03 years, 17 females, 15 idiopathic moyamoya and 15 syndromic moyamoya). Frontal haemodynamics were abnormal in all regardless of stroke history and comorbidity, but occipital lobe haemodynamics were also abnormal in children with syndromic moyamoya. Executive function deficits were noted in both idiopathic and syndromic moyamoya, whereas intellectual ability was impaired in syndromic moyamoya, even in the absence of stroke. Analysis of the relative effect of regional abnormal haemodynamics on cognitive outcomes demonstrated that executive dysfunction was predominantly explained by right parietal and white matter haemodynamics independent of stroke and comorbidity, while posterior circulation haemodynamics predicted intellectual ability. These results suggest that parietal and posterior haemodynamics play a compensatory role in overcoming frontal vulnerability and cognitive impairment.

Cerebral Venous Sinus Thrombosis in Preterm Infants

BACKGROUND:

Neonatal cerebral venous sinus thrombosis (CVST) can lead to brain injury and neurodevelopmental impairments. Previous studies of neonatal CVST have focused on term infants, and studies of preterm infants are lacking. In this study, we examined the clinical and radiological features, treatment and outcome of CVST in preterm infants.

METHODS:

This was a retrospective, consecutive cohort study of preterm infants (gestational age <37 weeks) with radiologically confirmed CVST. All magnetic resonance imaging/MRV and CT/CTV scans were re-reviewed to study thrombus characteristics and pattern of brain injury. Outcome was assessed by the validated pediatric stroke outcome measure at the most recent clinic visit.

RESULTS:

Twenty-six preterm infants with CVST were studied. Of these, 65% were moderate-late preterm (32–37 weeks), 27% very preterm (28–32 weeks), and 8% extreme preterm (<28 weeks). Most (73%) were symptomatic at presentation with seizures or abnormal exam. Transverse (85%) and superior sagittal (42%) sinuses were common sites of thrombosis. Parenchymal brain injury was predominantly periventricular (35%) and deep white matter (31%) in location. Intraventricular hemorrhage occurred in 46%. Most infants (69%) were treated with anticoagulation. No treated infant (including eleven with pretreatment hemorrhage) had new or worsening post-treatment hemorrhage. Outcomes ranged from no deficits (50%), mild-moderate (25%), and severe (25%) impairment.

CONCLUSIONS:

In our sample of preterm infants with CVST, more than one-quarter were asymptomatic. White matter brain lesions predominated and one-half had neurological deficits at follow-up. Anticoagulation of preterm CVST in this small cohort appeared to be safe. Larger studies of preterm CVST are needed.

International Prevalence and Mechanisms of SARS-CoV-2 in Childhood Arterial Ischemic Stroke During the COVID-19 Pandemic

Background:

Data from the early pandemic revealed that 0.62% of children hospitalized with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had an acute arterial ischemic stroke (AIS). In a larger cohort from June 2020 to December 2020, we sought to determine whether our initial point estimate was stable as the pandemic continued and to understand radiographic and laboratory data that may clarify mechanisms of pediatric AIS in the setting of SARS-CoV-2.

Methods:

We surveyed international sites with pediatric stroke expertise to determine numbers of hospitalized SARS-CoV-2 patients <18 years, numbers of incident AIS cases among children (29 days to <18 years), frequency of SARS-CoV-2 testing for children with AIS, and numbers of childhood AIS cases positive for SARS-CoV-2 June 1 to December 31, 2020. Two stroke neurologists with 1 neuroradiologist determined whether SARS-CoV-2 was the main stroke risk factor, contributory, or incidental.

Results:

Sixty-one centers from 21 countries provided AIS data. Forty-eight centers (78.7%) provided SARS-CoV-2 hospitalization data. SARS-CoV-2 testing was performed in 335/373 acute AIS cases (89.8%) compared with 99/166 (59.6%) in March to May 2020, P<0.0001. Twenty-three of 335 AIS cases tested (6.9%) were positive for SARS-CoV-2 compared with 6/99 tested (6.1%) in March to May 2020, P=0.78. Of the 22 of 23 AIS cases with SARS-CoV-2 in whom we could collect additional data, SARS-CoV-2 was the main stroke risk factor in 6 (3 with arteritis/vasculitis, 3 with focal cerebral arteriopathy), a contributory factor in 13, and incidental in 3. Elevated inflammatory markers were common, occurring in 17 (77.3%). From centers with SARS-CoV-2 hospitalization data, of 7231 pediatric patients hospitalized with SARS-CoV-2, 23 had AIS (0.32%) compared with 6/971 (0.62%) from March to May 2020, P=0.14.

Conclusions:

The risk of AIS among children hospitalized with SARS-CoV-2 appeared stable compared with our earlier estimate. Among children in whom SARS-CoV-2 was considered the main stroke risk factor, inflammatory arteriopathies were the stroke mechanism.

Abstract TMP96: Maladaptive Plasticity In Dystonia Following Pediatric Basal Ganglia Stroke: Associations Between Structural Connectivity And Cognitive Functioning

Background: Dystonia is one of the most common movement disorders after pediatric basal ganglia stroke, causing significant disability. It presents several months post stroke suggesting a role of maladaptive neuroplasticity in its manifestation. Children with dystonia show additional difficulties in intelligence (IQ), academics, and cognitive inhibition, beyond those associated with stroke.

Objective: To examine structural connectivity in children with post-stroke dystonia and its relationship with cognitive outcomes.

Method: A prospective study of children with unilateral basal ganglia stroke and dystonia and healthy controls. Diffusion tensor imaging was used to assess white matter integrity in the cingulum and superior longitudinal fasciculus (SLF) using fractional anisotropy (FA) and mean diffusivity (MD). Participants completed measures of IQ and cognitive inhibition and flexibility.

Results: Six children with basal ganglia stroke and dystonia (6 female; Median age= 15.98, IQR= 4.32) and 6 neurotypical controls (3 male; Median age= 18.01, IQR= 5.13) were included. Participants were age-matched within 1-3 years. Hemispheres were matched by dominance such that if the stroke was in the dominant hemisphere the control’s dominant hemisphere was matched to the ipsilateral side and vice versa. Mann Whitney-U tests showed children with dystonia had poorer performance on measures of IQ (U= 0, p=. 002, η 2 = .69) and inhibition (U= 4.5, p= .026, η 2 = .39). FA was lower in the ipsilateral cingulum (U= 5, p= .041, η 2 = .36) and MD was higher in the ipsilateral SLF (U= 32, p= .026, η 2 = .42) in the dystonia participants. Significant associations (p< .05) were found between ipsilateral cingulum FA and IQ (r= .56), inhibition (r= .76), and flexibility (r= .60); contralateral cingulum FA and inhibition (p= .59); ipsilateral SLF FA and inhibition (r= .51) and flexibility (r= .58); and ipsilateral SLF MD and inhibition (r= -.54) and flexibility (r= -.55). Associations between the contralateral cingulum FA and IQ (r= .47, p= .060) and flexibility (r= .50, p= .051) trended to significance.

Conclusion: Findings support the hypothesis that post-stroke dystonia reflects maladaptive reorganization after injury that is associated with motor and cognitive outcome.

Abstract TP97: White Matter And Deep Grey Matter Structural Variations In Childhood Moyamoya Disease

Background: Moyamoya disease is a progressive steno-occlusive arteriopathy that increases stroke risk. Clinically, cognitive decline is known to occur over time, even in the absence of stroke. MRI measures of cerebrovascular reactivity (CVR) provide an in vivo assessment of cerebrovascular reserve and stroke risk. Typically, in normal-appearing white matter (WM) lower (quantified as negative) CVR is associated with increased apparent diffusion coefficient (ADC). However, the association between negative CVR and ADC in children is not well understood.

Objectives: To determine (i) whether negative CVR is associated with changes in ADC in normal-appearing WM of children with Moyamoya, ii) whether there is an association between CVR and ADC with structural damage to the brain (by measuring the volume of subcortical structures).

Methods: Retrospective analysis of a consecutive cohort of nine children with Moyamoya (male = 4, median age = 12.1) with no history of stroke, and seven age and sex-matched controls. ADC values and fractional negativity (fneg), calculated from CVR parametric maps as the fraction of negative CVR voxels within a region of interest (ROI), were extracted from WM and subcortical GM ROIs. Volumes from the subcortical GM regions were extracted and normalized for head size. Analyses of differences was calculated per hemisphere (n=18, bilateral disease n = 4, unilateral n=5) and categorized as affected and unaffected and compared to controls.

Results: Mean (m) ADC in WM of affected hemispheres (m=807.05, p<0.01) and unaffected (m=814.68, p<0.05) hemispheres were significantly larger compared to controls (m=761.04). A positive relationship was found between fneg and ADC in affected (r=0.37, p=0.24) and unaffected (r=0.26, p=0.62) hemispheres, but with no statistical significance. Increased ADC in the caudate was associated with smaller volume in the affected hemisphere of patients (r =-0.83, p=0.02).

Conclusions: ADC in normal appearing WM in children with Moyamoya is elevated, and is associated with volume of the caudate in this cohort demonstrating the association between abnormal CVR, perfusion and structural damage in children with Moyamoya and no stroke.

Abstract WP176: Compared To Catheter Angiogram MRA Is A Moderate Predictor Of Suzuki Grade In Children With Moyamoya

Introduction: Moyamoya is a progressive cerebral arteriopathy affecting the arteries in the circle of Willis. Suzuki grade for moyamoya using catheter angiogram has been gold standard for the evaluation of moyamoya both in children and adults. Suzuki grade evaluates the amount of stenosis and collateral formation in the cerebral arteries. Magnetic resonance angiography (MRA) non-luminal imaging can overestimate stenosis and underestimate collaterals. With greater use of MRA for diagnosis and follow-up, it is important to understand MRA staging is truly comparable to catheter angiogram.

Methods: Study neurologist and interventional radiologist reviewed both catheter angiograms and MRAs without clinical information. The modified Suzuki stage was used to evaluate the MRA. Median time from MRA to catheter angiogram was calculated. Cohen’s Kappa was used to compare modalities of Suzuki grade based on catheter angiogram to modified Suzuki grade by MRA on the same patients.

Results: A total of 29 patients with moyamoya were reviewed. Median time between MRA and catheter angiogram was 2.4 months with interquartile range from 0.6-5.3 months. Unweighted Cohen’s Kappa was 0.34 (p<0.0001) which is considered fair correlation. When we calculated a weighted Cohen’s Kappa it improved but only to 0.49 (p<0.0001) which is moderate correlation.

Conclusion: Using Cohen’s kappa to compare two methods of evaluating cerebral artery stenosis in children with moyamoya, we demonstrated that there is only moderate correlation between catheter angiogram Suzuki staging compared to modified Suzuki staging with MRA. In conclusion, we suggest caution in the reliance of MRA for diagnosis and follow-up of children with moyamoya. We recommend consideration catheter angiograms at time of diagnosis and with surgical planning.

Abstract TMP95: Cerebral Sinovenous Thrombosis In Preterm Infants

Introduction: Neonatal cerebral sinovenous thrombosis (CSVT) can lead to brain injury and long-term neurodevelopmental impairments. Previous studies of neonatal CSVT have primarily focused on term infants, and studies of preterm infants are lacking. In this study, we examined the clinical and radiological features, treatment and outcome of CSVT in preterm infants.

Methods: This was a retrospective, consecutive cohort study of preterm infants (gestational age <37 weeks) with radiologically confirmed CSVT. All MRI/MRV and CT/CTV scans were re-reviewed to study thrombus characteristics and the pattern of brain injury. Clinical and radiological data were analysed using descriptive statistics, ANOVA and chi-square tests. Outcome was assessed by the validated Pediatric Stroke Outcome Measure (PSOM).

Results: A total of 26 preterm infants with CSVT were included. Of these, 65% were late preterm, 27% very preterm and 8% extreme preterm. Most (73%) were symptomatic at presentation with seizures or abnormal exam. Transverse (85%) and superior sagittal (42%) sinus were most common sites of thrombosis. Parenchymal brain injury was predominantly periventricular (35%) and deep white matter (31%) in location. Intraventricular hemorrhage occurred in 46%. Most infants (69%) were treated with anticoagulation. None of the treated infants had hemorrhagic complications. Outcome at follow-up ranged from no impairment (39%), mild impairment (19%) and severe impairment (19%).

Conclusions: Preterm infants with CSVT are often symptomatic and have white matter brain lesions at presentation. Anticoagulation treatment of preterm CSVT in this small cohort appeared to be safe. Further larger studies and treatment.

Abstract TP168: Quantitative Cerebrovascular Reactivity Atlas In Children

Introduction: Cerebrovascular reactivity (CVR) can be measured by inducing carbon dioxide (CO 2 ) changes in the circulation and measuring subsequent changes in blood flow with functional MRI blood oxygen level dependent sequences (BOLD). In clinical practice, abnormalities in CVR imaging can serve as a biomarker of ischemic risk. To characterize pathological aberrations in CVR, it is essential to have quantitative reference data as to what constitutes normal CVR across brain regions at various stages of development.

Methods: Prospective enrollment of healthy children ages 6 to 18. Target N of 40. Two datasets are being generated within the atlas using two different methods of administering the vasoactive stimulus (CO 2 ): a breath-hold CVR dataset (endogenous stimulus) and a RespirAct TM CVR dataset (exogenous). A test of normality is performed on CVR values for each voxel across subjects, with mean and standard deviation calculations. This will allow for generation of a Z-score for each CVR value per voxel in any clinical CVR study. Voxel-wide validation of breath-hold CVR values against the gold standard RespirAct TM CVR values will be performed using within subject t-test and between group comparisons. Subgroup analysis based on gender and age will also be performed.

Results: Preliminary CVR data for 8 healthy right-handed children is presented (4 female, median age 13, range 9 -14 years). All participants tolerated CVR studies well and no side effects were reported. Group datasets acquired to date passed tests of normality with no significant differences in CVR values between the two methods found.

Conclusions: This study will generate the first atlas of quantitative CVR-fMRI data in healthy children. Normative physiological data on CVR changes throughout childhood, and associations between CVR, blood pressure, age, and gender will be obtained. CVR imaging is performed clinically in patients with a risk of recurrent arterial ischemic stroke such as those with intracranial arteriopathies, sickle cell disease and other genetic and metabolic disorders. Our atlas can provide clinicians with objective measures regarding extent and distribution of CVR abnormalities, allow for stroke risk stratification, and aid in determining the optimal time for intervention.

Abstract TP172: Clinical And Neuroimaging Predictors Of Dyskinetic Cerebral Palsy

Background: Dyskinetic cerebral palsy (DCP) is a non-progressive disorder that results from lesions to the developing fetal brain. Neuroimaging patterns and risk factors for DCP in pre-term infants are poorly understood. Furthermore, neuroimaging differences between preterm and term infants with DCP and its relationship to clinical outcomes are not well established.

Objectives: 1) To describe neuroimaging differences between term and preterm infants with DCP. 2) To investigate relationships between neuroimaging patterns and clinical motor outcome of infants with DCP.

Methods: Patients with DCP were identified through The Cerebral Palsy Network where clinical details and magnetic resonance images (MRI) were collected on children with DCP. To determine lesion volume and location, manual segmentation was performed using ITK-SNAP software by study neuroradiologist. Lesion severity was graded using a semi-quantitative scale for structural MRIs(Laporta-Hoyos et al. 2018) based on the number of lobes and subcortical structures involved. Motor outcomes was assessed with the Gross Motor Function Classification System.

Results: Twenty-nine patients with DCP were identified. Preterm infants (n=12, [male= 8, female=4]), and term infants (n=16 term, [male= 6, female=10]) differed in mean gestational age (30.5 versus 39.1 weeks respectively, p=.02). The frequency of periventricular leukomalacia in preterm (89%) and term-born (58%) infants differed (p = 0.02). Lesion severity was associated with: the ventral posterior lateral (VPL) thalamus (r=0.574,p =.01), the posterior limb of the internal capsule (PLIC) (r=0.437p = .04) in term infants, and the right (r = 0.504, p = .01) and left putamen r = 0.629, p = .002) in term infants. Significant negative correlations were found between lesion severity and gross motor function in the VPL thalamus (r= -0.624, p = .001), PLIC (r= -0.735, p < .001), right (r= -0.50, p= .016) and left putamen (r= -0.54 p = .008).

Conclusion: Our results suggest the timing of lesions in term-born and preterm infants with DCP are associated with neuroimaging lesion patterns. Involvement of subcortical structures and lesion severity scores were associated with gross motor function in this cohort of patients with DCP.

Abstract TMP94: Health Inequity And Time From Stroke Onset To Arrival Trends: A Single-centre Experience

Introduction: Clinical outcomes post childhood stroke have been shown to largely depend on age at the time of stroke, and the size and location of the infarct. However, the impact of health inequities on time to hospital arrival and outcomes remain inadequately addressed. This study examined trends in material deprivation and its impact on time from stroke onset to arrival in the ER for children with arterial ischemic stroke.

Methods: A consecutive cohort of children >28 days-18 years of age diagnosed with arterial ischemic stroke between 2004 and 2019 at a comprehensive stroke centre were included. The Ontario Marginalization Index data for each child was derived from their residential postal code using validated mapping techniques. Within the index, material deprivation measures the income, education, single-parent families, and housing quality in a region. Patients were stratified into 3 cohorts by year of presentation; Cohort 1: 2004-2008, Cohort 2: 2009-2013, and Cohort 3: 2014-2019, while their postal codes were dichotomized into low or highly deprived neighbourhoods. The time from stroke onset to arrival was stratified into < 6 hours, 6 to 24 hours, and > 24 hours.

Results: Amongst 285 children, more lived in a highly deprived neighbourhood in the later cohort (Cohort 3: 2014-2019) than the earlier cohort (Cohort 1: 2004-2008) (47.5% vs. 40.3%). Compared to Cohort 1, more patients in Cohort 3 arrived in the ER within 6 hours of stroke onset (28.3% vs 52.5%) while a similar trend was found in patients arriving 6 to 24 hours post onset of stroke (10.1% vs. 23.2%). From Cohorts 1 to 3, a significant increase in the proportion of patients arriving in the ER within 6 hours of stroke onset was found (χ 2 = 10.9, p = 0.027).

Conclusion: Our study demonstrated an increasing trend toward more patients with stroke coming from highly deprived neighbourhoods. This is a cause for concern. However, whether this has an impact on stroke severity and outcomes is yet to be determined. Over the same period, more patients within the later cohort arrived in the ER within 6 hours of stroke onset. These findings may be attributed to sustained community-based education and primary-care initiatives that have led to increased awareness of childhood stroke symptoms over the past 15 years.

Surgical treatment of post-infectious hydrocephalus in infants

The management of post-infective hydrocephalus in infants remains a challenging task for the pediatric neurosurgeon. The decision-making curve is often complex in that appropriate temporizing measures need to be implemented to properly clear any infection within the CSF before any decision can be made regarding a permanent solution. The etiology differs at varying stages of neonatal development, and the weight of the child, skin fragility, and relevant surgical treatment options are often important limiting factors. Deciding on the optimal treatment option involves assessing the etiology, age, and clinical and radiological features of the individual case and selecting the most appropriate surgical option.

Hemorrhagic transformation and stroke recurrence in children with cardiac disease receiving antithrombotic therapy for secondary stroke prevention

BACKGROUND

Antithrombotic therapy is currently recommended for stroke prevention in pediatric cardioembolic stroke where the recurrence risk is high; however, safety concerns remain. The primary objective of this study was to evaluate clinical and radiographic predictors of hemorrhagic transformation and stroke recurrence in children with cardiac disease to ascertain the safety and failure rates for secondary stroke prevention.

METHODS

This was a single-center, retrospective analysis of a prospectively enrolled cohort of children with radiologically confirmed cardioembolic stroke from January 2003 to December 2017 treated with institutional guidelines.

RESULTS

Eighty-two children met inclusion criteria (male 44 [54%]; neonates 23 [28%]; median age 0.43 years [0.08-4.23]). Hemorrhagic transformation occurred in 20 (24%) with the majority (75% of 20) being petechial and asymptomatic. One death (1%) was reported from hemorrhagic transformation. Four children (5%) had major extracranial hemorrhage. Most (95%) received antithrombic therapy, with anticoagulation being favored (82%). Greater stroke volume was associated with hemorrhagic transformation using the pediatric Alberta Stroke Program Early CT Score (6.1 ± 3.3 vs. 3.5 ± 2.3; p = .006). Stroke recurred in 11 (13%) children at a median 32 days (5.5-93) from the index event and the majority (90%) were on treatment at the time of recurrence. Children with univentricular physiology were less likely to have hemorrhagic transformation (RR 0.31; 95% CI 0.09-0.96, p = .04); however, they had higher rates of recurrent stroke before final palliative repair.

CONCLUSIONS

In spite of the 24% hemorrhagic transformation rate, antithrombotic therapy has a positive risk-balance in certain cardioembolic stroke subgroups, particularly in those with single-ventricle physiology, when accounting for stroke volume.

Sterilization of gowns: making the most of a scarce commodity during the COVID-19 pandemic

Baylor Clinic in Mbabane, Eswatini, convened a crisis meeting to tackle critical shortages of long-sleeved disposable gowns that resulted from COVID-19 pandemic constraints on available personal protective equipment (PPE). A strategy deemed safe, affordable and sustainable was adopted to autoclave and re-use gowns based on a risk-stratified approach. Key objectives were to ensure essential infection control and prevention (ICP) for medical doctors, nurses, and laboratory teams. Administrative, environmental and personal protective measures for ICP were enhanced through regular staff training. This strategy for gown re-use has been invaluable in motivating responsible stewardship and maximization of available gowns during the COVID-19 pandemic.

Childhood arterial ischemic stroke due to mineralizing angiopathy: an 18-year single-center experience

Mineralizing angiopathy is a unique, age-specific stroke syndrome characterized by basal ganglia infarction and lenticulostriate calcification after minor head injury in early childhood. There is limited understanding of the pathophysiology, course, and clinical outcome of this syndrome. We describe the clinical and radiographical phenotype of a single-center, consecutively enrolled cohort of children with mineralizing angiopathy from January 2002 to January 2020 and provide a comparative analysis to previously published literature. Fourteen children were identified. Previously unreported findings include: stroke onset in eight children older than 18 months; presence of basal ganglia hemorrhage in four; multifocal basal ganglia infarcts in three; presence of additional non-basal ganglia calcifications in three; and presence of thrombophilia in one. Seven children had moderate-to-severe neurological deficits. There was no symptomatic stroke recurrence (mean follow-up 3y 7mo, SD 1y 7mo). Our expanded phenotype highlights distinct characteristics of mineralizing angiopathy in children and has the potential to inform future research. What this paper adds Children with mineralizing angiopathy are often misdiagnosed as having a limb fracture despite normal x-rays. A magnetic resonance imaging-only approach may miss this entity. Non-contrast computed tomography, in addition to MRI is recommended to identify calcifications in idiopathic arterial ischemic stroke. Most children have moderate-to-severe neurological sequela.

Distinct Clinical and Radiographic Phenotypes in Pediatric Patients With Moyamoya

BACKGROUND

Given the expanding evidence of clinico-radiological differences between moyamoya disease (MMD) and moyamoya syndrome (MMS), we compared the clinical and radiographic features of childhood MMD and MMS to identify predictors of ischemic event recurrence.

METHODS

We reviewed a pediatric moyamoya cohort followed between 2003 and 2019. Clinical and radiographic characteristics at diagnosis and follow-up were abstracted. Comparisons between MMD and MMS as well as between MMD and two MMS subgroups (neurofibromatosis [MMS-NF1] and sickle cell disease [MMS-SCD]) were performed.

RESULTS

A total of 111 patients were identified. Patients with MMD presented commonly with transient ischemic attacks (TIAs) (35 % MMD versus 13% MMS-NF1 versus 9.5% MMS-SCD; P = 0.047). Symptomatic stroke presentation (MMD 37% versus MMS-NF1 4% versus 33%; P = 0.0147) and bilateral disease at diagnosis (MMD 73% versus MMS-NF1 22 % versus MMS-SCD 67%; P = 0.0002) were uncommon in MMS-NF1. TIA recurrence was common in MMD (hazard ratio 2.86; P = 0.001). The ivy sign was absent on neuroimaging in a majority of patients with MMS-SCD (MMD 67% versus MMS-NF1 52% versus MMS-SCD 9.5%; P = 0.0002). Predictors of poor motor outcome included early age at diagnosis (odds ratio [OR] 8.45; P = 0.0014), symptomatic stroke presentation (OR 6.6; P = 0.019), and advanced Suzuki stage (OR 3.59; P = 0.019).

CONCLUSIONS

Moyamoya exhibits different phenotypes based on underlying etiologies. Frequent TIAs is a common phenotype of MMD and symptomatic stroke presentation a common feature of MMD and MMS-SCD, whereas unilateral disease and low infarct burden are common in MMS-NF1. In addition, absence of ivy sign is a common phenotype in MMS-SCD.

Abstract P584: Sleep in Pediatric Stroke Study (SleePSS): Neuroimaging and Neurocognitive Correlates of Sleep Health in Pediatric Stroke

Introduction: Pediatric arterial ischemic stroke (AIS) is a serious cause of lifelong neurological and cognitive disabilities. Although they are at increased risk of obstructive sleep apnea (OSA), children with AIS may have abnormal sleep indices even in the absence of OSA diagnosis. This can adversely affect their blood vessels health (impaired cerebrovascular reactivity, CVR) and can lead to neurocognitive impairments. Therefore, we aimed to investigate the association of cerebral blood vessels health with polysomnographic measures and cognitive function in children with AIS.

Hypothesis: Quantitative measure of negative CVR, i.e. fractional negativity (fneg) and negative CVR correlate significantly with abnormal overnight oxygen and carbon dioxide levels in children with AIS, even in the absence of OSA.

Methods: We conducted a single-centre cross-sectional study in children with AIS aged between 8 and 18 years old and who were not at risk of OSA (i.e., pediatric sleep questionnaire score<0.33). All children were evaluated using:

(1) Non-invasive Blood Oxygen Level Dependent magnetic resonance imaging to study CVR.

(2) An overnight polysomnography

(3) Comprehensive evaluation of intellectual abilities, attention and executive function.

Results: Ten children with AIS (40% males; median age: 14.3 years) were included after a median of 8.8 years following stroke onset. None of the children was diagnosed with OSA. We found significant correlations between fneg and minimum oxygen saturation during REM sleep (r=0.81, r=0.68 and r=0.76 in grey matter, white matter and whole brain, respectively; p<0.05). The whole brain mean negative CVR correlated significantly with the visual spatial, fluid reasoning, and emotion regulation indices (r=-0.82, -0.8, and 0.75, respectively, p<0.05). Mean negative CVR in white matter correlated significantly with the indices of executive function (emotion regulation, cognitive regulation and global executive composite scores, r=0.72-0.76, p<0.05).

Conclusion: Impaired CVR in children with AIS correlates with abnormal sleep indices even in the absence of OSA diagnosis. This can potentially result in cognitive difficulties, the majority of which remain not fully explained by stroke-related factors.

Swallowing, Oral Motor, Motor Speech, and Language Impairments Following Acute Pediatric Ischemic Stroke

BACKGROUND AND PURPOSE

Following adult stroke, dysphagia, dysarthria, and aphasia are common sequelae. Little is known about these impairments in pediatric stroke. We assessed frequencies, co-occurrence and associations of dysphagia, oral motor, motor speech, language impairment, and caregiver burden in pediatric stroke.

METHODS

Consecutive acute patients from term birth-18 years, hospitalized for arterial ischemic stroke (AIS), and cerebral sinovenous thrombosis, from January 2013 to November 2018 were included. Two raters reviewed patient charts to detect documentation of in-hospital dysphagia, oral motor dysfunction, motor speech and language impairment, and caregiver burden, using a priori operational definitions for notation and assessment findings. Other variables abstracted included demographics, preexisting conditions, stroke characteristics, and discharge disposition. Impairment frequencies were obtained by univariate and bivariate analysis and associations by simple logistic regression.

RESULTS

A total of 173 patients were stratified into neonates (N=67, mean age 2.9 days, 54 AIS, 15 cerebral sinovenous thrombosis) and children (N=106, mean age 6.5 years, 73 AIS, 35 cerebral sinovenous thrombosis). Derived frequencies of impairments included dysphagia (39% neonates, 41% children); oral motor (6% neonates, 41% children); motor speech (37% children); and language (31% children). Common overlapping impairments included oral motor and motor speech (24%) and dysphagia and motor speech (23%) in children. Associations were found only in children between stroke type (AIS over cerebral sinovenous thrombosis) and AIS severity (more severe deficit at presentation) for all impairments except feeding impairment alone. Caregiver burden was present in 58% patients.

CONCLUSIONS

For the first time, we systematically report the frequencies and associations of dysphagia, oral motor, motor speech, and language impairment during acute presentation of pediatric stroke, ranging from 30% to 40% for each impairment. Further research is needed to determine long-term effects of these impairments and to design standardized age-specific assessment protocols for early recognition following stroke.

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.

Imaging Predictors of Neurologic Outcome After Pediatric Arterial Ischemic Stroke

BACKGROUND AND PURPOSE

To assess whether initial imaging characteristics independently predict 1-year neurological outcomes in childhood arterial ischemic stroke patients.

METHODS

We used prospectively collected demographic and clinical data, imaging data, and 1-year outcomes from the VIPS study (Vascular Effects of Infection in Pediatric Stroke). In 288 patients with first-time stroke, we measured infarct volume and location on the acute magnetic resonance imaging studies and hemorrhagic transformation on brain imaging studies during the acute presentation. Neurological outcome was assessed with the Pediatric Stroke Outcome Measure. We used univariate and multivariable ordinal logistic regression models to test the association between imaging characteristics and outcome.

RESULTS

Univariate analysis demonstrated that infarcts involving uncinate fasciculus, angular gyrus, insular cortex, or that extended from cortex to the subcortical nuclei were significantly associated with poorer outcomes with odds ratios ranging from 1.95 to 3.95. All locations except the insular cortex remained significant predictors of poor outcome on multivariable analysis. When infarct volume was added to the model, the locations did not remain significant. Larger infarct volumes and younger age at stroke onset were significantly associated with poorer outcome, but the strength of the relationships was weak. Hemorrhagic transformation did not predict outcome.

CONCLUSIONS

In the largest pediatric arterial ischemic stroke cohort collected to date, we showed that larger infarct volume and younger age at stroke were associated with poorer outcomes. We made the novel observation that the strength of these associations was modest and limits the ability to use these characteristics to predict outcome in children. Infarcts affecting specific locations were significantly associated with poorer outcomes in univariate and multivariable analyses but lost significance when adjusted for infarct volume. Our findings suggest that infarcts that disrupt critical networks have a disproportionate impact upon outcome after childhood arterial ischemic stroke.

Long-term cognitive outcomes after cerebral sinovenous thrombosis in childhood

AIM

To assess long-term cognitive function in children after cerebral sinovenous thrombosis (CSVT).

METHOD

Children with CSVT, who had neuropsychological testing for intellectual ability, executive function, attention, language, or behavior, were included in a prospective observational study. Outcomes were compared with normative means using one-sample t-tests. Predictors of abnormal function were examined using logistic regression.

RESULTS

Fifty children with CSVT were included (median age at diagnosis 2y 10mo, interquartile range 7d-6y 10mo; 35 males, 15 females). The median follow-up time was 4 years 2 months (interquartile range 2y 8mo-6y 4mo). Compared with normative means, children with CSVT had lower mean (± standard deviation) full-scale IQ, working memory, and processing speed scores (93.3±16, p=0.01; 93.6±16, p=0.04; 93.7±15.3, p=0.02 respectively). They also had lower scores in executive function, attention, and language domains. Refractory seizure at presentation was associated with a trend in behavioral problems (odds ratio [OR] 6.3, 95% confidence interval [CI] 0.9-46, p=0.07). Females were less likely to experience processing speed difficulties (OR 0.22, 95% CI 0.04-1.3, p=0.09). Incomplete recanalization was associated with a greater risk of abnormal verbal comprehension (OR 5.3, 95% CI 0.93-30.5, p=0.059).

INTERPRETATION

Children with CSVT as a group performed below age expectations on standardized neuropsychological tests, although there was variability across individuals and cognitive domains. Larger studies are needed to evaluate predictors of cognitive deficits in children with CSVT.