Cerebral microhemorrhages in children with congenital heart disease: Prevalence, risk factors, and impact on neurodevelopmental outcomes.

Background: Infants with complex congenital heart disease (CHD) require life-saving corrective/palliative heart surgery in the first weeks of life. These infants are at risk for brain injury and poor neurodevelopmental outcomes. Cerebral microhemorrhages (CMH) are frequently seen after neonatal bypass heart surgery, but it remains unknown if CMH are a benign finding or constitute injury. Herein, we investigate the risk factors for developing CMH and their clinical significance. Methods: 192 infants with CHD undergoing corrective cardiac surgery with cardiopulmonary bypass (CPB) at a single institution were prospectively evaluated with pre-(n = 183) and/or postoperative (n = 162) brain magnetic resonance imaging (MRI). CMH severity was scored based on total number of microhemorrhages. Antenatal, perioperative, and postoperative candidate risk factors for CMH and neurodevelopmental (ND) outcomes were analyzed. Eighteen-month neurodevelopmental outcomes were assessed using the Bayley-III Scales of Infants and Toddler Development in a subset of patients (n = 82). Linear regression was used to analyze associations between risk factors or ND outcomes and presence/number of CMH. Results: The most common CHD subtypes were hypoplastic left heart syndrome (HLHS) (37%) and transposition of the great arteries (TGA) (33%). Forty-two infants (23%) had CMH present on MRI before surgery and 137 infants (85%) post-surgery. No parameters evaluated were significant risk factors for preoperative CMH. In multivariate analysis, cardiopulmonary bypass (CPB) duration (p < 0.0001), use of extracorporeal membrane oxygenation (ECMO) support (p < 0.0005), postoperative seizure(s) (p < 0.03), and lower birth weight (p < 0.03) were associated with new or worsened CMH postoperatively. Higher CMH number was associated with lower scores on motor (p < 0.03) testing at 18 months. Conclusion: CMH is a common imaging finding in infants with CHD with increased prevalence and severity after CPB and adverse impact on neurodevelopmental outcomes starting at a young age. Longer duration of CPB and need for postoperative ECMO were the most significant risk factors for developing CMH. However, presence of CMH on preoperative scans indicates non-surgical risk factors that are yet to be identified. Neuroprotective strategies to mitigate risk factors for CMH may improve neurodevelopmental outcomes in this vulnerable population.

Prevalence of Patent Foramen Ovale in a Cohort of Children With Cryptogenic Ischemic Stroke.

BACKGROUND AND OBJECTIVES: To determine the significance of patent foramen ovale (PFO) in childhood stroke, we compared PFO prevalence, PFO features, and stroke recurrence risk in 25 children with cryptogenic arterial ischemic stroke (AIS), 54 children with AIS from a known etiology, and 209 healthy controls. METHODS: We performed a case-control analysis of a 14-year prospectively enrolled single-center cohort of children with AIS who underwent transthoracic echocardiogram (TTE) and compared them to TTEs of otherwise healthy children evaluated for benign cardiac concerns. Stroke patients 29 days to 18 years of age at stroke ictus with confirmed acute AIS on imaging, availability of complete diagnostic studies of stroke risk factors, including TTE images available for central review, and at least 1 follow-up evaluation after index stroke were included. Presence of PFO and high-risk PFO features were assessed by 2 independent, blinded reviewers and compared between groups with the Fisher exact test. Stroke/TIA recurrence risk was determined from Cox proportional hazards models. RESULTS: Of 154 children with first-ever AIS, 79 were eligible; 25 had cryptogenic AIS, and 54 had a known cause. PFO prevalence was higher in the cryptogenic group (7, 28%) compared to both the known stroke etiology group (3, 5.6%, p = 0.009) and controls without stroke (24, 11.5%, p = 0.03). There were no significant differences in presence of right-to-left shunt and atrial septal aneurysm. Median follow-up time for entire stroke cohort was 20.9 months. Stroke-free recurrence at 2-years did not differ between children with and without PFO (HR 2.0, 95% CI 0.4-9.3, p = 0.39). DISCUSSION: PFO prevalence was higher in children with cryptogenic stroke compared to patients with AIS with known etiology and healthy controls. PFO was not associated with increased recurrence risk. Optimal secondary preventive treatment in children with cryptogenic stroke and PFO remains uncertain and requires further study. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that children with cryptogenic ischemic stroke have an increased frequency of PFO compared to children with ischemic stroke of known etiology and healthy controls.

Endovascular and thrombolytic treatment eligibility in childhood arterial ischemic stroke.

AIM: To describe factors affecting eligibility for, and rates of utilization of, hyperacute therapy in children with acute ischemic stroke (AIS) following establishment of our institutional acute stroke treatment pathway in 2005. METHODS: A retrospective analysis of a prospectively enrolled, single-center cohort was performed including children age 2 - <18 years with acute AIS from 2005 through 2017. Descriptive statistics were used to summarize clinical characteristics, presentation data, and Pediatric NIH Stroke Scale (PedNIHSS) scores that were abstracted from medical records. Assessment for eligibility and administration of hyperacute therapy was determined at the time of presentation according to the institutional stroke pathway. RESULTS: Of 90 children (median age at presentation 11.3 years, 36% female) with acute AIS, 5 (6%) received hyperacute therapy: 3 received intravenous tissue plasminogen activator (IV-tPA) alone, 1 received endovascular therapy (EVT) alone, and 1 received IV-tPA and EVT. Of 54 children (60%) who presented within 4.5 h of time last seen well, 6 had PedNIHSS scores 6-24, no medical contraindication to IV-tPA, and a partial or complete vessel occlusion. Of 7 children >3 years old who presented after EVT became available at our hospital and within 6 h of time last seen well with a PedNIHSS score 6-24, 3 (43%) had a large vessel occlusion (LVO). Two patients underwent EVT and the other patient was not transferred until >6 h from time last seen well. CONCLUSIONS: Delay to presentation and diagnosis of childhood acute AIS, mild neurologic deficits at presentation, medical contraindications to IV-tPA, and lack of vessel occlusion on acute neuroimaging contribute to low rates of hyperacute treatment in children with acute AIS.

Role of Astrocytic Mitochondria in Limiting Ischemic Brain Injury?

Until recently, astrocyte processes were thought to be too small to contain mitochondria. However, it is now clear that mitochondria are found throughout fine astrocyte processes and are mobile with neuronal activity resulting in positioning near synapses. In this review, we discuss evidence that astrocytic mitochondria confer selective resiliency to astrocytes during ischemic insults and the functional significance of these mitochondria for normal brain function.

The Spontaneous Ataxic Mouse Mutant Tippy is Characterized by a Novel Purkinje Cell Morphogenesis and Degeneration Phenotype.

This study represents the first detailed analysis of the spontaneous neurological mouse mutant, tippy, uncovering its unique cerebellar phenotype. Homozygous tippy mutant mice are small, ataxic, and die around weaning. Although the cerebellum shows grossly normal foliation, tippy mutants display a complex cerebellar Purkinje cell phenotype consisting of abnormal dendritic branching with immature spine features and patchy, non-apoptotic cell death that is associated with widespread dystrophy and degeneration of the Purkinje cell axons throughout the white matter, the cerebellar nuclei, and the vestibular nuclei. Moderate anatomical abnormalities of climbing fiber innervation of tippy mutant Purkinje cells were not associated with changes in climbing fiber-EPSC amplitudes. However, decreased ESPC amplitudes were observed in response to parallel fiber stimulation and correlated well with anatomical evidence for patchy dark cell degeneration of Purkinje cell dendrites in the molecular layer. The data suggest that the Purkinje neurons are a primary target of the tippy mutation. Furthermore, we hypothesize that the Purkinje cell axonal pathology together with disruptions in the balance of climbing fiber and parallel fiber-Purkinje cell input in the cerebellar cortex underlie the ataxic phenotype in these mice. The constellation of Purkinje cell dendritic malformation and degeneration phenotypes in tippy mutants is unique and has not been reported in any other neurologic mutant. Fine mapping of the tippy mutation to a 2.1 MB region of distal chromosome 9, which does not encompass any gene previously implicated in cerebellar development or neuronal degeneration, confirms that the tippy mutation identifies novel biology and gene function.