The Sensitivity of Limited-Sequence MRI in Identifying Pediatric Cervical Spine Injury: A Western Pediatric Surgery Research Consortium Multicenter Retrospective Cohort Study

INTRODUCTION

Clinical clearance of a child's cervical spine after trauma is often challenging due to impaired mental status or an unreliable neurologic examination. Magnetic resonance imaging (MRI) is the gold standard for excluding ligamentous injury in children but is constrained by long image acquisition times and frequent need for anesthesia. Limited-sequence MRI (LSMRI) is used in evaluating the evolution of traumatic brain injury and may also be useful for cervical spine clearance while potentially avoiding the need for anesthesia. The purpose of this study was to assess the sensitivity and negative predictive value of LSMRI as compared to gold standard full-sequence MRI as a screening tool to rule out clinically significant ligamentous cervical spine injury.

METHODS

We conducted a ten-center, five-year retrospective cohort study (2017-2021) of all children (0-18y) with a cervical spine MRI after blunt trauma. MRI images were re-reviewed by a study pediatric radiologist at each site to determine if the presence of an injury could be identified on limited sequences alone. Unstable cervical spine injury was determined by study neurosurgeon review at each site.

RESULTS

We identified 2,663 children less than 18 years of age who underwent an MRI of the cervical spine with 1,008 injuries detected on full-sequence studies. The sensitivity and negative predictive value of LSMRI were both >99% for detecting any injury and 100% for detecting any unstable injury. Young children (age < 5 years) were more likely to be electively intubated or sedated for cervical spine MRI.

CONCLUSION

LSMRI is reliably detects clinically significant ligamentous injury in children after blunt trauma. To decrease anesthesia use and minimize MRI time, trauma centers should develop LSMRI screening protocols for children without a reliable neurologic exam.

LEVEL OF EVIDENCE

2 (Diagnostic Tests or Criteria).

Urine biomarkers of acute kidney injury and association with brain MRI abnormalities in neonatal hypoxic-ischemic encephalopathy

OBJECTIVE

Determine whether urine biomarkers NGAL (neutrophil gelatinase-associated lipocalin), KIM-1 (kidney injury molecule 1) and IL-18 (interleukin-18) are associated with abnormal MRI findings in neonates with hypoxic-ischemic encephalopathy (HIE) who underwent therapeutic hypothermia (TH).

STUDY DESIGN

Secondary analysis of a multicenter, prospective study of neonates with HIE requiring TH. Urine biomarkers were obtained at 12 and 24 h of life (HOL). Brain MRI was scored per NICHD criteria. Association between biomarkers and MRI stage was determined.

RESULTS

In 57 neonates with HIE, only IL-18 at 24 HOL was significantly increased in neonates with MRI Stage 2B or greater, compared to Stage 2A or less (mean 398.7 vs. 182.9 pg/mL, p = 0.024.) A multivariate model including IL-18 at 24 HOL and 5-min Apgar performed best, with an AUC of 0.84 (SE = 0.07, p = 0.02).

CONCLUSIONS

Elevated urine IL-18 at 24 HOL was associated with more severe brain MRI abnormalities among neonates with HIE.

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.

Dots and spots: A retrospective review of T2-hyperintense white matter lesions in pediatric patients with and without headache

OBJECTIVE

We aimed to determine if T2-weighted hyperintense white matter lesions (WMLs) on brain magnetic resonance imaging (MRI) occur more frequently in pediatric patients with migraine and other primary headache disorders compared to the general pediatric population.

BACKGROUND

Small foci of T2 hyperintensity in the white matter are frequently identified on brain MRI during the workup of pediatric headache. Such lesions have been reported to be more common among adults with migraine versus adults without migraine; however, this association has not been well established in the pediatric population.

METHODS

We performed a retrospective cross-sectional single-center study of electronic medical records and radiologic studies, examining pediatric patients from 3 to 18 years old who underwent brain MRI between 2016 and 2021. Patients with existing intracranial disease or abnormalities were excluded. Patients with reports of headache were categorized. Imaging was reviewed to determine the number and location of WMLs. Headache-associated disability scores (Pediatric Migraine Disability Assessment) were noted, when available.

RESULTS

Brain MRI of 248 patients with a diagnosis of headache (144 with migraine, 42 with non-migraine primary headache, and 62 with headache that could not be further classified) and 490 controls were reviewed. WMLs were encountered commonly among all study participants, with a prevalence of 40.5% (17/42) to 54.1% (265/490). There was no statistically significant difference comparing the number of lesions between each of the headache groups and the control group: migraine group versus control group median [interquartile range (IQR)], 0 [0-3] versus 1 [0-4], incidence rate ratio [95% confidence interval (CI)], 0.99 [0.69-1.44], p = 0.989, non-migraine headache group versus control group median [IQR], 0 [0-3] versus 1 [0-4], 0.71 [0.46-1.31], p = 0.156, headache not otherwise specified group versus control group median [IQR], 0 [0-4] versus 1 [0-4], 0.77 [0.45-1.31], p = 0.291. There was no significant correlation between headache-associated disability and the number of WMLs (0.07 [-0.30 to 0.17], rho [95% CI]).

CONCLUSION

T2 hyperintense WMLs are common within the pediatric population and are not encountered more frequently in pediatric patients with migraine or other primary headache disorders. Thus, such lesions are presumably incidental and unlikely related to headache history.

Defining Soft Tissue: Bitmap Printing of Soft Tissue for Surgical Planning

Nearly all applications of 3D printing for surgical planning have been limited to bony structures and simple morphological descriptions of complex organs due to the fundamental limitations in accuracy, quality, and efficiency of the current modeling paradigms and technologies. Current approaches have largely ignored the constitution of soft tissue critical to most surgical specialties where multiple high-resolution variations transition gradually across the interior of the volume. Differences in the scales of organization related to unique organs require special attention to capture fine features critical to surgical procedures. We present a six-material bitmap printing technique for creating 3D models directly from medical images, which are superior in spatial and contrast resolution to current 3D modeling methods, and contain previously unachievable spatial fidelity for soft tissue differentiation. A retrospective exempt IRB was obtained for all data through the Colorado Multiple Institution Review Board #21-3128.

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.

Age-related changes in the completeness of the circle of Willis in children

PURPOSE

The circle of Willis is a circulatory anastomosis that supplies blood to the brain. If any of the bridging segments are hypoplastic or absent, the capacity for collateral flow in the setting of large vessel occlusion may be decreased. Outside of the neonatal period, the prevalence of a complete circle of Willis (CoW) in the pediatric population has not been well described. Our objectives include determining the prevalence of a complete CoW in children and identifying if there is an age-related "loss" of arterial segments.

METHODS

Following IRB approval, angiograms of the CoW performed on a 3-T MR platform from 2016 to 2020 on patients 21 years or younger were retrospectively reviewed. Any patient with underlying arterial pathology that may affect the CoW was excluded. Patient age and gender at the time of imaging were obtained.

RESULTS

In total, 592 pediatric CoW were assessed. Frequencies of completeness were calculated in two different fashions: scenario 1 where a CoW was characterized as complete even if it contained hypoplastic vessels (88.8%), and scenario 2 where it was characterized as complete after excluding hypoplastic vessels (44.0%). In both scenarios, our data showed that older age was more associated with an incomplete CoW (p < 0.0001). In addition, we found a higher percentage of males with an incomplete CoW compared with females (p < 0.0001).

CONCLUSIONS

The presence of a complete CoW is greater in our pediatric population than what has been reported in adults. The prevalence of an incomplete circle of Willis also increases significantly with age.

Kinetically Stabilizing Mutations in Beta Tubulins Create Isotype-Specific Brain Malformations

Mutations in the family of genes encoding the tubulin subunits of microtubules are associated with a spectrum of human brain malformations known as tubulinopathies. How these mutations impact tubulin activity to give rise to distinct developmental consequences is poorly understood. Here we report two patients exhibiting brain malformations characteristic of tubulinopathies and heterozygous T178M missense mutations in different β-tubulin genes, TUBB2A or TUBB3. RNAseq analysis indicates that both TUBB2A and TUBB3 are expressed in the brain during development, but only TUBB2A maintains high expression in neurons into adulthood. The T178 residue is highly conserved in β-tubulins and located in the exchangeable GTP-binding pocket of β-tubulin. To determine the impact of T178M on β-tubulin function we created an analogous mutation in the β-tubulin of budding yeast and show that the substitution acts dominantly to produce kinetically stabilized microtubules that assemble and disassemble slowly, with fewer transitions between these states. In vitro experiments with purified mutant tubulin demonstrate that T178M decreases the intrinsic assembly activity of β-tubulin and forms microtubules that rarely transition to disassembly. We provide evidence that the T178M substitution disrupts GTPase-dependent conformational changes in tubulin, providing a mechanistic explanation for kinetic stabilization. Our findings demonstrate the importance of tubulin’s GTPase activity during brain development, and indicate that tubulin isotypes play different, important roles during brain development.

Intracranial Traumatic Hematoma Detection in Children Using a Portable Near-infrared Spectroscopy Device

Introduction

We sought to validate a handheld, near-infrared spectroscopy (NIRS) device for detecting intracranial hematomas in children with head injury.

Methods

Eligible patients were those <18 years old who were admitted to the emergency department at three academic children’s hospitals with head trauma and who received a clinically indicated head computed tomography (HCT). Measurements were obtained by a blinded operator in bilateral frontal, temporal, parietal, and occipital regions. Qualifying hematomas were a priori determined to be within the brain scanner’s detection limits of >3.5 milliliters in volume and <2.5 centimeters from the surface of the brain. The device’s measurements were positive if the difference in optical density between hemispheres was >0.2 on three successive scans. We calculated diagnostic performance measures with corresponding exact two-sided 95% Clopper-Pearson confidence intervals (CI). Hypothesis test evaluated whether predictive performance exceeded chance agreement (predictive Youden’s index > 0).

Results

A total of 464 patients were enrolled and 344 met inclusion for primary data analysis: 10.5% (36/344) had evidence of a hematoma on HCT, and 4.7% (16/344) had qualifying hematomas. The handheld brain scanner demonstrated a sensitivity of 58.3% (21/36) and specificity of 67.9% (209/308) for hematomas of any size. For qualifying hematomas the scanner was designed to detect, sensitivity was 81% (13/16) and specificity was 67.4% (221/328). Predictive performance exceeded chance agreement with a predictive Youden’s index of 0.11 (95% CI, 0.10 – 0.15; P < 0.001) for all hematomas, and 0.09 (95% CI, 0.08 – 0.12; P < 0.001) for qualifying hematomas.

Conclusion

The handheld brain scanner can non-invasively detect a subset of intracranial hematomas in children and may serve an adjunctive role to head-injury neuroimaging decision rules that predict the risk of clinically significant intracranial pathology after head trauma.

Robust deep learning classification of adamantinomatous craniopharyngioma from limited preoperative radiographic images

Deep learning (DL) is a widely applied mathematical modeling technique. Classically, DL models utilize large volumes of training data, which are not available in many healthcare contexts. For patients with brain tumors, non-invasive diagnosis would represent a substantial clinical advance, potentially sparing patients from the risks associated with surgical intervention on the brain. Such an approach will depend upon highly accurate models built using the limited datasets that are available. Herein, we present a novel genetic algorithm (GA) that identifies optimal architecture parameters using feature embeddings from state-of-the-art image classification networks to identify the pediatric brain tumor, adamantinomatous craniopharyngioma (ACP). We optimized classification models for preoperative Computed Tomography (CT), Magnetic Resonance Imaging (MRI), and combined CT and MRI datasets with demonstrated test accuracies of 85.3%, 83.3%, and 87.8%, respectively. Notably, our GA improved baseline model performance by up to 38%. This work advances DL and its applications within healthcare by identifying optimized networks in small-scale data contexts. The proposed system is easily implementable and scalable for non-invasive computer-aided diagnosis, even for uncommon diseases.

Unusual Neuroimaging in a Case of Rapidly Progressive Juvenile-Onset Krabbe Disease

Krabbe disease is a progressive neurologic disorder caused by deficiency of the lysosomal enzyme galactocerebrosidase. The disease commonly has an early-infantile onset, but can have late-infantile, juvenile, or adult-onset phenotypes. Classic computed tomography (CT) and magnetic resonance imaging (MRI) findings in Krabbe have been well described. We report a patient, ultimately diagnosed with juvenile-onset Krabbe, who presented with atypical CT imaging and rapid disease progression. Our patient was a previously healthy and developmentally appropriate female who presented at 3 years 4 months of age with ataxia and motor regression that had progressed over the course of 6 weeks without an identifiable catalyst. CT, performed in the emergency setting, demonstrated extensive white matter hyperdensity. Subsequent MRI showed T2 hyperintensity of the white matter corresponding to the areas of hyperdensity on the CT, as well as enhancement of multiple cranial nerves bilaterally, suggestive of Krabbe disease. Enzymatic testing demonstrated low galactocerebrosidase activity and molecular testing of GALC revealed compound heterozygosity for 2 known pathogenic mutations, consistent with a diagnosis of Krabbe Disease. This included the common 30-kb deletion and a known pathogenic mutation associated with juvenile/adult-onset disease. Our patient's diffuse hyperdensity on CT offers a new radiographic finding to include in the repertoire of Krabbe imaging, and thus aide in the diagnostic evaluation. The rapidity of progression our patient demonstrated is additionally unique and should be considered in the identification of juvenile Krabbe as well as the complicated decision-making process regarding potential treatments.

In Utero Exposure to Maternal Overweight or Obesity is Associated with Altered Offspring Brain Function in Middle Childhood

OBJECTIVE

The impact of in utero exposure to maternal overweight and obesity on offspring metabolic health is well documented. Neurodevelopmental outcomes among these children are, however, less well studied. To address this gap, the current study investigated brain function among 4- to 6-year-old children exposed to maternal overweight or obesity during gestation compared with that of children born to mothers with healthy BMI in pregnancy.

METHODS

Resting-state functional magnetic resonance imaging was used to study neuronal activity and connectivity during a passive viewing task (movie) among 101 typically developing children enrolled in the Healthy Start study, a longitudinal prebirth cohort in Colorado.

RESULTS

Forty-nine children (48%) were exposed to maternal overweight or obesity in utero (mean age = 5 years, SD = 0.9). Children born to mothers with overweight or obesity demonstrated hyperactivity in the left posterior cingulate cortex and hypoactivity in the dorsal anterior cingulate and the supplementary motor area (P < 0.05 for all). Children born to mothers with overweight or obesity also showed ubiquitously weaker brain connectivity (P < 0.05 for all).

CONCLUSIONS

These novel results suggest altered brain function among children exposed to maternal overweight and obesity in utero.

Lateral semi-circular canal asymmetry in females with idiopathic scoliosis

Purpose

Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal structural deformity that occurs in otherwise normal individuals. Although curve progression and severity vary amongst individuals, AIS can lead to significant cosmetic and functional deformity. AIS etiology has been determined to be genetic, however, exact genetic and biological processes underlying this disorder remain unknown. Vestibular structure and function have potentially been related to the etiopathogenesis of AIS. Here, we aimed to characterize the anatomy of the semicircular canals (SCC) within the vestibular system through a novel approach utilizing T2-weighted magnetic resonance images (MRI).

Methods

Three dimensional, MRI-based models of the SCCs were generated from AIS subjects (n = 20) and healthy control subjects (n = 19). Linear mixed models were used to compare SCC morphological measurements in the two groups. We compared side-to-side differences in the SCC measurements between groups (group*side interaction).

Results

Side-to-side differences in the lateral SCC were different between the two groups [false discovery rate adjusted p-value: 0.0107]. Orientation of right versus left lateral SCC was significantly different in the AIS group compared to the control group [mean side-to-side difference: -4.1°, 95% CI: -6.4° to -1.7°]. Overall, among subjects in the AIS group, the left lateral SCC tended to be oriented in a more horizontal position than subjects in the control group.

Significance

Asymmetry within the SCCs of the vestibular system of individuals with AIS potentially results in abnormal efferent activity to postural muscles. Consequences of this muscular activity during periods of rapid growth, which often coincides with AIS onset and progression, warrant consideration.

Serial Magnetic Resonance Imaging (MRI) in Pyruvate Dehydrogenase Complex Deficiency

OBJECTIVES

To report 2 additional cases of pyruvate dehydrogenase complex deficiency with reversible deep gray matter lesions following initiation of ketogenic diet and to perform a literature review of serial imaging in patients with pyruvate dehydrogenase complex.

METHODS

Clinical data on 3 previously unpublished cases of patients with pyruvate dehydrogenase complex deficiency and with serial magnetic resonance imagings (MRIs) before and after institution of ketogenic diet were reported. A systematic literature review was performed to search for published cases of patients with confirmed pyruvate dehydrogenase complex deficiency who underwent serial MRIs.

RESULTS

The 3 subjects in this series demonstrated clinical improvement on ketogenic diet. Two subjects showed reversal of some brain lesions on repeat MRI following initiation of ketogenic diet. Of the 21 published cases with serial MRIs, 13 patients underwent some form of treatment, and of this smaller subset 4 patients had repeat MRIs that showed definitive improvement. In both our described cases and those published in the literature, improvement occurred in lesions in the basal ganglia.

CONCLUSIONS

In patients with pyruvate dehydrogenase complex deficiency, basal ganglia lesions on MRI are reversible with treatment in some cases and could serve as a biomarker for measuring response to treatment.

Cost and Utility of Routine Contrast-Enhanced Neck MRA in a Pediatric MRI Stroke Evaluation Protocol

BACKGROUND AND PURPOSE

Cervical arterial dissection is one of the frequent causes of pediatric arterial ischemic stroke. Out of concern for missing cervical arterial dissection in patients in whom pediatric stroke is suspected, our tertiary children's hospital added contrast-enhanced 3D neck MR angiography to every pediatric stoke work-up. This research investigated whether the routine use of contrast-enhanced neck MRA in our MR imaging stroke protocol ever detected a cervical arterial abnormality when the DWI, SWI/gradient recalled-echo, or circle of Willis MRA findings from the brain MR imaging were reported as normal.

MATERIALS AND METHODS

The institutional PACS data base was searched for stroke protocol MRIs that included DWI, gradient recalled-echo or SWI, circle of Willis MRA, and 3D contrast-enhanced neck MRA in patients younger than 18 years of age with examinations performed between September 2010 and June 2017.

RESULTS

In only a single case (0.15%) were the DWI, SWI/gradient recalled-echo, or circle of Willis MRA findings all separately reported as normal and the contrast-enhanced neck MRA findings reported as abnormal. To reach these findings, we screened 681 patients, which would have resulted in an estimated >$200,000 in Medicare charges and $80,000 in of out-of-pocket cost to patients.

CONCLUSIONS

In our large series, the addition of a routine contrast-enhanced neck MRA to our pediatric stroke MR imaging protocol was of extremely low yield. We believe the use of neck MRA should reasonably be limited to cases in which abnormalities are initially detected on standard brain sequences or to patients with atypical presentation or recurrent pathology.

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

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

Diagnostic accuracy of neuroimaging in pediatric optic chiasm/sellar/suprasellar tumors

Preoperative diagnosis for tumors arising in the optic chiasm/sellar/suprasellar region in children is helpful to determine surgical necessity and approach, given the high operative risk in this area. We evaluated the ability to differentiate tumor type by preoperative neuroimaging. Thirty-eight of 53 tumors were correctly diagnosed by neuroimaging based on final pathologic diagnosis (prediction accuracy 72%). Prediction accuracies were 87% (20/23) for craniopharyngioma, 79% (11/14) for optic pathway glioma, 64% (7/11) for germ cell tumor, and 0% (0/5) for Langerhans cell histiocytosis. Diagnosis of optic chiasm/sellar/suprasellar tumors in children by imaging alone should be considered when biopsy is considered high risk.

Abstract WMP116: Acute Infarct Volume in Childhood Stroke Can Be Accurately Estimated by Modelling Contraction of Chronic Infarction

Introduction: Arterial ischemic stroke (AIS) occurs in 1-2 children/100,000/year. Most children have neurologic deficits post-AIS, but the influence of infarct volume on neurologic outcome is understudied. While acute infarct volume {best measured as a percentage of total brain volume infarcted (%aTBVi) in the growing brain} likely predicts outcome, acute scans are not always available in children. Chronic infarct volumes are underestimated by direct measurement due to contraction. A method for estimating acute infarct volumes from chronic scans is needed. We developed and compared the reliability of three methods for estimating the %aTBVi from values measured on chronic images.

Methods: A retrospective IRB-approved study studying children (age 1 month-17 years) with AIS enrolled 158 patients. Those with acute (<3 days) and chronic (>90 days) MRIs were manually segmented by a pediatric neuroradiologist. Method 1 (direct method, used as control) estimated %aTBVi by measuring chronic infarct volume (cVI) and dividing by total brain volume. Method 2 (OFC method) estimated %aTBVi by subtracting the total non-infarcted brain volume from an extrapolated total brain volume based on orbitofrontal circumference (OFC). Method 3 (contraction method, Figure 1) used a regression model to apply a correction factor to the direct measurement of cVI that was then divided by total brain volume to estimate %aTBVi. Intraclass correlation compared estimated %aTBVi of the three methods to the gold standard %aTBVi calculated from manual segmentation of acute scans.

Results: Inclusion criteria were met by 86 patients. The control direct method had excellent reliability (ICC 0.79), although it was exceeded by the contraction method (Figure 1, ICC=0.86), while the OFC method reliability was poor (ICC=0.42).

Conclusion: %aTBVi is reliably estimated in children with AIS with only chronic imaging via the contraction method.

Abstract TP505: Activity After Stroke in Children

Introduction: Childhood stroke is a devastating disease with lifelong morbidity that can last decades. Post-stroke exercise habits may be particularly important for long-term health and secondary stroke prevention in adulthood. We hypothesized that children with stroke have decreased activity as compared to age and gender matched healthy controls.

Methods: We enrolled 15 children from our IRB approved institutional stroke database and 15 controls to participate in a two-week study of daily activity (mean age=13 years, 80% female). Participants were asked to wear bilateral wireless ankle accelerometers with Bluetooth transmission to a smartphone around each ankle 8 hours or more a day for 14 days. Demographic data, activity patterns (i.e., total walking time, time spent sedentary, average walking speed), and compliance were recorded. Stroke size was measured by neuroradiologists as a percentage of total brain volume. We then compared the percentage of time sedentary between cases and controls via two-tailed t-test, as well as performed a regression analysis to determine the impact of stroke size upon activity levels.

Results: Children with stroke wore monitors an average of 10 of the 14 requested days for an average of 9.6 hours each day, as compared to controls who averaged 9 of the 14 requested days for an average of 10.6 hours each day. As expected, children with stroke show a slightly slower walking speed of 1.17 meters per second as compared to controls at 1.2 meters per second. While children with stroke walked a similar number of hours per day as the control group (1.42 for cases vs 1.48 for controls), both groups were sedentary a great percentage of time (85% vs 86% respectively, P=0.38). Patients with larger strokes did not record less activity than peers with smaller strokes (P=0.823).

Conclusion: Activity levels in children after stroke are comparable to their age and gender-matched peers, although less than ideal in both groups. In addition, stroke size did not have an impact upon activity levels in children with stroke. These findings suggest activity studies are feasible in this population, and will need to be confirmed in larger prospective studies. Low overall levels of activity may still represent an opportunity for intervention in this population.

The conus medullaris ratio: A new way to identify tethered cord on MRI

PURPOSE

Approximately 25% of patients with anorectal malformation have tethered cord. The traditional way of determining conus medullaris level on magnetic resonance imaging (MRI) relies on counting vertebrae, which may be challenging due to vertebral numeric variation, segmentation anomalies, as well as transitional vertebral body anatomy. The purpose of this study was to utilize more reliable anatomic landmarks (foramen magnum, conus termination, and the upper limit of the iliac crest) to establish a consistent ratio that may differentiate patients with normal and low-lying conus.

METHODS

A single institution database search identified two groups of patients: 255 with normal and 85 with abnormal spinal MRI, who underwent tethered cord release. The conus medullaris ratio was calculated in both groups. The ratio was obtained by dividing the distance between the conus level and the iliac crest by the distance between the foramen magnum and the conus level (IRB # 16-2330).

RESULTS

The mean ratio was significantly higher in the non-tethered group compared to the tethered patients (0.184 [sd 0.03] versus 0.118 [sd 0.09]; P < .0001). The ratio proved to be a good discriminator between normal and abnormal patients, with area under the curve (AUC) equal to 0.749, meaning that at random, there is a 75% chance that the tethered cord patient will have a lower ratio than the non-tethered cord patient.

CONCLUSION

"The Conus Medullaris Ratio" is a good predictor of low-lying conus level on MRI and offers an easy alternative to counting vertebral body levels, particularly in patients with variant or abnormal vertebral body anatomy.

LEVEL OF EVIDENCE

II, Study of Diagnostic Test.

Occult head injury is common in children with concern for physical abuse

BACKGROUND

Studies evaluating small patient cohorts have found a high, but variable, rate of occult head injury in children <2 years old with concern for physical abuse. The American College of Radiology (ACR) recommends clinicians have a low threshold to obtain neuroimaging in these patients.

OBJECTIVES

Our aim was to determine the prevalence of occult head injury in a large patient cohort with suspected physical abuse using similar selection criteria from previous studies. Additionally, we evaluated proposed risk factors for associations with occult head injury.

MATERIALS AND METHODS

This was a retrospective, secondary analysis of data collected by an observational study of 20 U.S. child abuse teams that evaluated children who underwent subspecialty evaluation for concern of abuse. We evaluated children <2 years old and excluded those with abnormal mental status, bulging fontanelle, seizure, respiratory arrest, underlying neurological condition, focal neurological deficit or scalp injury.

RESULTS

One thousand one hundred forty-three subjects met inclusion criteria and 62.5% (714) underwent neuroimaging with either head computed tomography or magnetic resonance imaging. We found an occult head injury prevalence of 19.7% (141). Subjects with emesis (odds ratio [OR] 3.5, 95% confidence interval [CI] 1.8-6.8), macrocephaly (OR 8.5, 95% CI 3.7-20.2), and loss of consciousness (OR 5.1, 95% CI 1.2-22.9) had higher odds of occult head injury.

CONCLUSION

Our results show a high prevalence of occult head injury in patients <2 years old with suspected physical abuse. Our data support the ACR recommendation that clinicians should have a low threshold to perform neuroimaging in patients <2 years of age.

Significance of FDG-PET Hypermetabolism in Children with Intractable Focal Epilepsy

BACKGROUND

Interictal 18F-fluorodeoxyglucose-positron emission topography (FDG-PET) hypometabolism is routinely used in the presurgical workup of children with medically intractable epilepsy (MIE). FDG-PET hypermetabolism, however, is rarely seen, and the significance of this finding in the epilepsy workup is not well established.

METHODS

We performed a retrospective study of patients who underwent FDG-PET during the presurgical workup of MIE over a 4-year period, between 1 January 2010 and 31 December 2013, at the Children's Hospital Colorado, CO, USA.

RESULTS

Focal FDG-PET hypermetabolism was identified in 7 (2.2%) of 317 patients. The median age was 124 months, all cases with catastrophic epilepsy. Surface electroencephalography (EEG) performed concomitantly with FDG injections revealed ictal EEG discharges in 2 patients, frequent interictal epileptiform discharges (IEDs) in 3, occasional IEDs in 1, and no IEDs in 1. All 7 patients underwent functional hemispherectomies. Histopathology revealed type 1 focal cortical dysplasia in all patients. Six (86%) were completely seizure-free (Engel class I) and 1 had extremely infrequent seizures (Engel class II) (mean follow-up, 47.4 months).

CONCLUSION

While a rare finding, interictal PET hypermetabolism does occur, may help identify epileptogenic zones, and assessment to reveal it should be made by concomitant use of surface EEG during PET scans.

Abstract WMP104: Pediatric Cortical Vein Thrombosis: Frequency and Association With Venous Infarction

Introduction: Cortical vein thrombosis (CVT) is an uncommon site of involvement in cerebral sinovenous thrombosis (CSVT). Few reports have described pediatric CVT, and none have described its unique features. The aim of our study was to evaluate the clinical and radiographic features of a cohort of children with CSVT, comparing those with CVT to those without CVT.

Hypothesis: Children with CVT are more likely to experience acute restricted diffusion and chronic venous infarction, as compared to those without CVT.

Methods: Children diagnosed with CSVT from 2006 to 2014 were enrolled in a prospective cohort study at a single tertiary care center. Inclusion criteria comprised confirmation of CSVT on acute imaging with MRI/MRV or CTV, and availability of follow-up imaging at subacute and chronic time periods. Patients were separated into two groups: those with CVT (CVT group) and those without (non-CVT group). Patient demographics, clinical presentation, and imaging findings were collected and analyzed using a two-tailed Fisher's exact test. Scans were reviewed for clot location and parenchymal abnormalities.

Results: Fifty patients met inclusion criteria, including 12 with CVT. In both groups, children frequently presented with headache and focal neurological deficits. However, the CVT group was more likely to present with seizure (P = 0.0271), altered mental status (P = 0.0271), and a family history of clotting disorder (P = 0.0477). Acute imaging of the CVT group more commonly demonstrated concurrent superior sagittal sinus thrombosis (P = 0.0024) and restricted diffusion (P < 0.0001); and follow-up imaging in the CVT group more commonly showed venous infarction (P = 0.0007).

Conclusions: The presence of CVT in our pediatric CSVT cohort was significantly associated with seizures at presentation, venous-territory restricted diffusion on acute imaging, and venous infarction at follow up. While further work is needed to confirm our results, involvement of cortical veins in CSVT appears to be associated with an increased risk of infarction in children.

Cerebral radiation necrosis in pediatric patients

Radiation necrosis is a well-described toxicity following radiation therapy in the brain. There is little data regarding the incidence of radiation necrosis in pediatric patients. We retrospectively reviewed our experience with 101 children with solid brain tumors. Radiation necrosis was diagnosed by examination of magnetic resonance imaging. Median follow-up for all patients was 13 months (range 3-51). Radiation necrosis occurred in 5% (5/101) of cases with a median time to onset of 1.2 months. In three of these children, the child was symptomatic, requiring management with steroids and bevacizumab. Radiation necrosis did not correlate with the administration of chemotherapy, age at treatment, or planning treatment volume. Our experience with pediatric patients treated with radiotherapy for solid brain tumor suggests that children may have an increased likelihood to develop radiation necrosis compared to adults.

Radiation-induced gliomas in 2 pediatric patients with neurofibromatosis type 1: case study and summary of the literature

Neurofibromatosis type 1 (NF1) is a genetic disorder that predisposes patients to the formation of sporadic tumors and also increases the risk of radiation-induced malignancies. The most commonly described radiation-induced tumor in NF1 patients is a malignant peripheral nerve sheath tumor. We present 2 children with NF1 who received radiation therapy and subsequently developed high-grade gliomas. We then review the current literature on radiation-induced tumors in NF1 patients. Although radiation may be the most appropriate therapy in specific situations for children with NF1, the secondary tumor risk should be carefully considered.

Continuous octreotide infusion for sulfonylurea-induced hypoglycemia in a toddler

BACKGROUND

Ingestion of a sulfonylurea by toddlers can cause profound hypoglycemia and neurologic sequelae. Although mild cases can be managed with dextrose and boluses of octreotide, optimal management of patients with severe hypoglycemia and cerebral injury has not been well established.

OBJECTIVE

Our objective was to report the use of continuous infusion octreotide for tight glucose control after accidental sulfonylurea ingestion with severe neurologic dysfunction.

CASE REPORT

A 17-month-old child presented to the emergency department with marked hypoglycemia, cerebral edema, and persistent seizures after ingestion of an unknown amount of glipizide. Hypoglycemia was refractory to i.v. dextrose bolus/infusion and subcutaneous octreotide. Continuous i.v. octreotide was utilized in conjunction with low-volume/high-concentration dextrose infusion as treatment, allowing for tight glucose and fluid management in the setting of cerebral edema.

CONCLUSIONS

Continuous infusion of octreotide resulted in rapid stabilization of blood glucose levels while maintaining fluid-restriction goals. Our patient demonstrated reversibility of diffuse cerebral edema in this setting with near complete recovery of neurologic function. Octreotide administration by continuous infusion may be preferable to subcutaneous bolus administration for the treatment of severe sulfonylurea-induced hypoglycemia with associated neurologic injury.

Late cytotoxic edema in 2 children with hemiplegia: hemiplegic migraine or stroke?

Hemiplegic migraine (HM) is a rare variant of migraine with aura, characterized by migrainous headache and fully reversible motor deficit within 24 hours. Both sporadic and familial forms of HMs are genetically heterogenous with little information on neuroimaging during and after acute attacks. We report 2 cases of children with presumed HM and late cytotoxic edema.

Dynamics of microglial activation: a confocal time-lapse analysis in hippocampal slices

The dynamics of microglial cell activation was studied in freshly prepared rat brain tissue slices. Microglia became activated in the tissue slices, as evidenced by their conversion from a ramified to amoeboid form within several hours in vitro. To define better the cytoarchitectural dynamics underlying microglial activation, we performed direct three-dimensional time-lapse confocal imaging of microglial cells in live brain slices. Microglia in tissue slices were stained with a fluorescent lectin conjugate, FITC-IB(4), and stacks of confocal optical sections through the tissue were collected repeatedly at intervals of 2-5 min for several hours at a time. Morphometric analysis of cells from time-lapse sequences revealed that ramified microglia progress to amoeboid macrophages through a stereotypical sequence of steps. First, in the withdrawal stage, the existing ramified branches of activating microglia do not actively extend or engulf other cells, but instead retract back (mean rate, 0.5-1.5 microm/min) and are completely resorbed into the cell body. Second, in the motility stage, a new set of dynamic protrusions, which can exhibit cycles of rapid extension and retraction (both up to 4 microm/min), abruptly emerges. Sometimes new processes begin to emerge even before the old branches are completely withdrawn. Third, in the locomotory stage, microglia begin translocating within the tissue (up to 118 microm/h) only after the new protrusions emerge. We conclude that the rapid conversion of resting ramified microglia to active amoeboid macrophages is accomplished not by converting quiescent branches to dynamic ones, but rather by replacing existing branches with an entirely new set of highly motile protrusions. This suggests that the ramified branches of resting microglia are normally incapable of rapid morphological dynamics necessary for activated microglial function. More generally, our time-lapse observations identify changes in the dynamic behavior of activating microglia and thereby help define distinct temporal and functional stages of activation for further investigation.

Comprehensive approach to Chiari malformation in pediatric patients

Chiari malformation is a developmental disorder that is often associated with other abnormalities of the cerebrospinal axis. Despite widespread recognition of this association, there is relatively little information on the treatment of these coexisting disorders in the setting of cerebellar tonsillar ectopia. In an effort to improve the care provided to pediatric patients with Chiari malformations the authors reviewed their management practices over the last 20 years. Specifically, they recorded presenting symptoms, radiological studies, comorbidities, and management (surgical and nonsurgical) of 112 patients (all < 20 years of age) with Chiari malformation without myelodysplasia.

They found an associated syrinx in 29% of patients, basilar invagination in 17%, and scoliosis in 14%. The basal angle varied from 120 to 190° and Boogard's angle varied from 120 to 220°; both angles were larger than those measured in normal controls. The vertical height of the posterior fossa was shortened and the volume decreased as compared with normal controls.

The surgical management of this group of patients included posterior decompressive (44%), combined transoral and posterior decompressive (31%), combined posterior decompressive and posterior fusion (8%), and multiple posterior decompressive procedures in the same patient (5%).

The authors conclude that pediatric patients with a Chiari malformation should be specifically examined for evidence of additional craniovertebral malformations so that procedures are directed at correcting both the comorbidities and the herniation of the cerebellar tonsils through the foramen magnum.