Cerebral arteriopathies of childhood and stroke - A focus on systemic arteriopathies and pediatric fibromuscular dysplasia (FMD).

Systemic vascular involvement in children with cerebral arteriopathies is increasingly recognized and often highly morbid. Fibromuscular dysplasia (FMD) represents a cerebral arteriopathy with systemic involvement, commonly affecting the renal and carotid arteries. In adults, FMD diagnosis and classification typically relies on angiographic features, like the 'string-of-beads' appearance, following exclusion of other diseases. Pediatric FMD (pFMD) is considered equivalent to adult FMD although robust evidence for similarities is lacking. We conducted a comprehensive literature review on pFMD and revealed inherent differences between pediatric and adult-onset FMD across various domains including epidemiology, natural history, histopathophysiology, clinical, and radiological features. Although focal arterial lesions are often described in children with FMD, the radiological appearance of 'string-of-beads' is highly nonspecific in children. Furthermore, children predominantly exhibit intimal-type fibroplasia, common in other childhood monogenic arteriopathies. Our findings lend support to the notion that pFMD broadly reflects an undefined heterogenous group of monogenic systemic medium-or-large vessel steno-occlusive arteriopathies rather than a single entity. Recognizing the challenges in categorizing complex morphologies of cerebral arteriopathy using current classifications, we propose a novel term for describing children with cerebral and systemic vascular involvement: 'cerebral and systemic arteriopathy of childhood' (CSA-c). This term aims to streamline patient categorization and, when coupled with advanced vascular imaging and high-throughput genomics, will enhance our comprehension of etiology, and accelerate mechanism-targeted therapeutic developments. Lastly, in light of the high morbidity in children with cerebral and systemic arteriopathies, we suggest that investigating for systemic vascular involvement is important in children with cerebral arteriopathies.

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.

Anterior extension of the choroid plexus into the frontal horns of the fetal lateral cerebral ventricles: Prenatal findings and postnatal outcome.

OBJECTIVE: To evaluate the short- and long-term outcome of fetuses with evidence of extension of the choroid plexus into the frontal horns. METHODS: This is a retrospective cohort study of fetuses diagnosed with isolated choroid plexi extending into the frontal horns. Fetuses with major central nervous system anomalies were excluded. Ultrasound and fetal/postnatal magnetic resonance imaging (MRI) were evaluated. Postnatal outcomes, including developmental assessment, were obtained. RESULTS: Twenty nine fetuses were diagnosed with choroid plexus extension (22 unilateral and 7 bilateral). Gestational age at diagnosis was 19.3 weeks. Three cases (10.3%) presented with nonspecific extra-CNS findings. At presentation, 8/29 (28%) cases had single/multiple choroid plexus cysts (CPC). Twenty-six (89.6%) cases underwent antenatal MRI. On MRI, four cases had punctate susceptibility weighted imaging (SWI) foci suggesting trace hemosiderin and two cases had ventriculomegaly. Antenatal follow-up demonstrated resolution of the choroid plexus extension in 90% (18/20). Gestational age at delivery was 39.6 weeks. All had normal neurologic examinations within 24 h of life. Postnatal MRI studies were notable for deep venous differences in seven cases. Long-term clinical outcome was assessed in 14 cases with a median follow-up of 1.75 years, with normal neurodevelopment reported in 13/14 (92.8%). CONCLUSIONS: Most fetuses with an anterior extension of the choroid plexus as the sole sonographic finding had favorable outcomes.

Simple prenatal imaging predictors for postnatal cerebrospinal fluid diversion surgery in fetuses undergoing in utero surgery for spina bifida.

OBJECTIVES: To determine simple prenatal imaging parameters that can easily be acquired to predict the need for postnatal CSF diversion (PCD) surgery in fetuses undergoing open fetal surgery for open spina bifida (OSB). METHODS: All fetuses with OSB that underwent open fetal surgery between June 2017 and June 2021 with available follow-up outcomes were included. Imaging parameters including clivus-supraocciput angle (CSA) on magnetic resonance imaging, transcerebellar diameter (TCD) and lateral ventricle size (Vp) on ultrasound (US), were collected pre- and postoperatively. The requirement for PCD surgery was determined at 1 year of age. The predictive strength of each parameter was determined by Receiver Operating Characteristic curve analysis. RESULTS: Among 36 babies eligible for the analyses, 41.7% required PCD by one year of age. Pre-operative Vp (AUC 0.71; 95% confidence interval [CI] 0.54-0.88; p = 0.03), TCD (AUC 0.72; 95% CI 0.55-0.89; p = 0.02) and CSA (AUC 0.72; 95% CI 0.51-0.93; p = 0.04) were fair predictors for PCD surgery. After fetal surgery, TCD (AUC 0.93; 95% CI 0.83-1.00; p < 0.0001) and CSA (AUC 0.94; 95% CI 0.83-1.00; p = 0.0005) were outstanding predictors of PCD, whereas post-operative Vp was a fair predictor (AUC 0.71, 95% CI 0.54-0.88, p = 0.03). CONCLUSION: Post-operative CSA and TCD were outstanding predictors for the need for PCD surgery.

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.

Neurodevelopmental profiles of children with unilateral cerebral palsy associated with middle cerebral artery and periventricular venous infarctions.

AIM: To compare the neurodevelopment of children with unilateral cerebral palsy (CP) with middle cerebral artery (MCA) and periventricular venous infarctions (PVIs). METHOD: In this cross-sectional study, children with unilateral CP completed a neurological exam, unimanual Quality of Upper Extremity Skills Test, hand usage questionnaires, and IQ test. Neuroimaging was obtained from health records. RESULTS: Two hundred and forty-five participants with unilateral CP had neuroimaging (151 [61.9%] male, ages 2-18y, median=7y 6mo, interquartile range [IQR]=6y 7mo, with 93.6% in Gross Motor Function Classification System level I/II and 78.8% in Manual Ability Classification System level I/II). Ninety-seven (39.6%) had MCA injuries and 106 (43.3%) had periventricular white matter injuries, of which 48 (45.3%) were PVIs. Median Quality of Upper Extremity Skills Test for the MCA group was 49.2 (IQR=55.8), PVI 79.9 (IQR=23.6) (Mann-Whitney U=988.50, p<0.001). Bimanual hand usage (Children's Hand-use Experience Questionnaire) (Mann-Whitney U=425, p<0.001) and light touch (odds ratio=9.12, 95% confidence interval 1.28-400.76, Fisher's exact test p=0.017) were lower in the MCA compared to the PVI group. Full-scale IQ median centile score for the MCA group was 18.0 (IQR=35.5) and 50.0 (IQR=30.0) for the PVI group (Mann-Whitney U=382, p<0.001). INTERPRETATION: Children with unilateral CP and MCA injuries demonstrated lower hand function and usage, decreased light touch, and lower IQs compared to the PVI group. This study aids in defining rehabilitation needs informed by brain injury patterns.

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.

Homozygous mutation in PRUNE1 in an Oji-Cree male with a complex neurological phenotype.

The PRUNE1 gene encodes a member of the phosphoesterases (DHH) protein superfamily that is highly expressed in the human fetal brain and involved in the regulation of cell migration. Homozygous or compound heterozygous PRUNE1 mutations were recently identified in five individuals with brain malformations from four families. We present a case of a 2-year-old male with a complex neurological phenotype and abnormalities on brain MRI. Re-annotation of clinical whole-exome sequencing data revealed a homozygous likely pathogenic variant in PRUNE1 (c.521-2A>G). These results further delineate a new PRUNE1-related syndrome, and highlight the importance of periodic data re-annotation in individuals who remain without a diagnosis after undergoing genome-wide testing. © 2017 Wiley Periodicals, Inc.

Effects of orthodontic appliances on the diagnostic quality of magnetic resonance images of the head.

INTRODUCTION: The influence of 4 commonly used fixed orthodontic appliances on artifact formation and diagnostic quality of magnetic resonance (MR) images of the head produced by a 3-T MR scanner was studied. METHODS: Stainless steel brackets, ceramic brackets, combination of ceramic brackets and steel molar tubes, and multistranded steel mandibular lingual retainers were embedded into custom-made trays for each of 10 adult subjects. Head MR scans of 9 regions were acquired for each subject wearing these trays. Sagittal T1-weighted, axial T2-weighted, axial gradient-recalled, axial diffusion-weighted, noncontrast axial MR angiography, and axial fluid-attenuated inversion recovery MR sequences were included. Two neuroradiologists evaluated image distortions and diagnostic qualities of the 1314 acquired images (13860 image slices). RESULTS: The images were affected by appliance, head region, and MR sequence. Stainless steel brackets and molar tubes affected the images the most, and ceramic brackets caused minimal image distortion. CONCLUSIONS: Head MR images are differentially affected by orthodontic appliances. The appliance, region imaged, and MR sequence should be considered before imaging patients wearing fixed orthodontic appliances.

Imaging findings and MRI patterns in a cohort of 18q chromosomal abnormalities.

BACKGROUND AND PURPOSE: The abnormalities of long arm of chromosome 18 (18q) constitute a complex spectrum. We aimed to systematically analyze their MRI features. We hypothesized that there would be variable but recognizable white matter and structural patterns in this cohort. MATERIALS AND METHODS: In this retrospective cohort study, we included pediatric patients with a proven abnormality of 18q between 2000-2022. An age and sex matched control cohort was also constructed. RESULTS: Thirty-six cases, median MRI age 19.6 months (4.3 - 59.3), satisfied our inclusion criteria. Majority were females (25, 69%, F:M ratio 2.2:1). Fifty MR imaging studies were analyzed and 35 (70%) had delayed myelination. Two independent readers scored brain myelination with excellent interrater reliability. Three recognizable evolving MRI patterns with distinct age distributions and improving myelination scores were identified - PMD-like (9.9 months, 37), intermediate (22 months, 48) and washed-out pattern (113.6 months, 53). Etiologically, MRIs were analyzed across three subgroups - 18q- (34, 69%), trisomy 18 (10, 21%) and ring chromosome 18 (5, 10%). Ring chromosome 18 had the highest myelination lag (27, P value = 0.005) and multifocal white matter changes (P value = 0.001). Trisomy 18 had smaller pons and cerebellar dimensions (APD pons P value = 0.002, CC vermis P value <0.001 and TCD P value = 0.04). CONCLUSIONS: In this cohort of 18q chromosomal abnormalities, MRI revealed recognizable patterns correlating with improving brain myelination. Imaging findings appear to be on a continuum with more severe white matter abnormalities in ring chromosome 18 and greater prevalence of structural abnormalities of pons and cerebellum in trisomy 18. ABBREVIATIONS: 18q-: 18q deletion; CC: corpus callosum; CC-APD: CC anteroposterior diameter; FOD: fronto-occipital diameter; TCD: transverse cerebellar diameter; APD: anteroposterior diameter; CCD: craniocaudal diameter; MBP: myelin basic protein; PMD: Pelizaeus-Merzbacher Disease; GWMD: gray-white matter differentiation.

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.

Surgical outcomes in children with drug-resistant epilepsy and hippocampal sclerosis.

BACKGROUND: Hippocampal sclerosis (HS) is a common surgical substrate in adult epilepsy surgery cohorts but variably reported in various pediatric cohorts. OBJECTIVE: We aimed to study the epilepsy phenotype, radiological and pathological variability, seizure and neurocognitive outcomes in children with drug-resistant epilepsy and hippocampal sclerosis (HS) with or without additional subtle signal changes in anterior temporal lobe who underwent surgery. METHODS: This retrospective study enrolled children with drug-resistant focal epilepsy and hippocampal sclerosis with or without additional subtle T2-Fluid Attenuated Inversion Recovery (FLAR)/Proton Density (PD) signal changes in anterior temporal lobe who underwent anterior temporal lobectomy with amygdalohippocampectomy. Their clinical, EEG, neuropsychological, radiological and pathological data were reviewed and summarized. RESULTS: Thirty-six eligible patients were identified. The mean age at seizure onset was 3.7 years; 25% had daily seizures at time of surgery. Isolated HS was noted in 22 (61.1%) cases and additional subtle signal changes in ipsilateral temporal lobe in 14 (38.9%) cases. Compared to the normative population, the group mean performance in intellectual functioning and most auditory and visual memory tasks were significantly lower than the normative sample. The mean age at surgery was 12.3 years; 22 patients (61.1%) had left hemispheric surgeries. ILAE class 1 outcomes was seen in 28 (77.8%) patients after a mean follow up duration of 2.3 years. Hippocampal sclerosis was noted pathologically in 32 (88.9%) cases; type 2 (54.5%) was predominant subtype where further classification was possible. Additional pathological abnormalities were seen in 11 cases (30.6%); these had had similar rates of seizure freedom as compared to children with isolated hippocampal sclerosis/gliosis (63.6% vs 84%, p=0.21). Significant reliable changes were observed across auditory and visual memory tasks at an individual level post surgery. CONCLUSIONS: Favourable seizure outcomes were seen in most children with isolated radiological hippocampal sclerosis. Patients with additional pathological abnormalities had similar rates of seizure freedom as compared to children with isolated hippocampal sclerosis/gliosis.

Imaging of Abusive Head Trauma in Children.

In this article, we describe relevant anatomy, mechanisms of injury, and imaging findings of abusive head trauma (AHT). We also briefly address certain mimics of AHT, controversies, pearls, and pitfalls. Concepts of injury, its evolution, and complex nature of certain cases are highlighted with the help of case vignettes.

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.

Cerebral White Matter Tract Anatomy.

Advances in MR imaging techniques have allowed for detailed in vivo depiction of white matter tracts. The study of white matter structure and connectivity is of paramount importance in leukodystrophies, demyelinating disorders, neoplasms, and various cognitive, neuropsychiatric, and developmental disorders. The advent of advanced "function-preserving" surgical techniques also makes it imperative to understand white matter anatomy and connectivity, to provide accurate road maps for tumor and epilepsy surgery. In this review, we will describe cerebral white matter anatomy with the help of conventional MRI and diffusion tensor imaging.

Neuroradiological Mimics of Periventricular Leukomalacia.

AIM: Periventricular leukomalacia (PVL) is a term reserved to describe white matter injury in the premature brain. In this review article, the authors highlight the common and rare pathologies mimicking the chronic stage of PVL and propose practical clinico-radiological criteria that would aid in diagnosis and management. METHODS AND RESULTS: The authors first describe the typical brain MRI (magnetic resonance imaging) features of PVL. Based on their clinical presentation, pathologic entities and their neuroimaging findings were clustered into distinct categories. Three clinical subgroups were identified: healthy children, children with stable/nonprogressive neurological disorder, and those with progressive neurological disorder. The neuroradiological discriminators are described in each subgroup with relevant differential diagnoses. The mimics were broadly classified into normal variants, acquired, and inherited disorders. CONCLUSIONS: The term "PVL" should be used appropriately as it reflects its pathomechanism. The phrase "white matter injury of prematurity" or "brain injury of prematurity" is more specific. Discrepancies in imaging and clinical presentation must be tread with caution and warrant further investigations to exclude other possibilities.

Cerebral Sinovenous Thrombosis in Infants and Children: A Practical Approach to Management.

Cerebral sinovenous thrombosis (CSVT) is a rare, yet potentially devastating disorder, associated with acute complications and long-term neurologic sequelae. Consensus-based international pediatric CSVT treatment guidelines emphasize early clinical-radiologic recognition and prompt consideration for anticoagulation therapy. However, lack of clinical trials has precluded evidence-based patient selection, anticoagulant choice, optimal monitoring parameters and treatment duration. Consequently, uncertainties and controversies persist regarding anticoagulation practices in pediatric CSVT. This review focuses on commonly encountered issues that continue to pose questions and raise debates regarding anticoagulation therapy among pediatric neurologists and hematologists.

Hydrocephalus in Children: A Neuroradiological Perspective.

Concepts about the production, absorption, dynamics, and physiological roles of cerebrospinal fluid (CSF) have dramatically changed over the recent decades. This article will review these new concepts and detail how they must be used for a better assessment and a better understanding of the various aspects of hydrocephalus by using neuroradiological tools.

Neuroimaging Perspectives of Perinatal Arterial Ischemic Stroke.

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