Neurodegeneration and humoral response proteins in cerebrospinal fluid associate with pediatric-onset multiple sclerosis and not monophasic demyelinating syndromes in childhood.

BACKGROUND: Pediatric-onset multiple sclerosis (POMS) represents the earliest stage of disease pathogenesis. Investigating the cerebrospinal fluid (CSF) proteome in POMS may provide novel insights into early MS processes. OBJECTIVE: To analyze CSF obtained from children at time of initial central nervous system (CNS) acquired demyelinating syndrome (ADS), to compare CSF proteome of those subsequently ascertained as having POMS versus monophasic acquired demyelinating syndrome (mADS). METHODS: Patients were selected from two prospective pediatric ADS studies. Liquid chromatography-mass spectrometry (LC-MS) was performed in a Dutch discovery cohort (POMS n = 28; mADS n = 39). Parallel reaction monitoring-mass spectrometry (PRM-MS) was performed on selected proteins more abundant in POMS in a combined Dutch and Canadian validation cohort (POMS n = 48; mADS n = 106). RESULTS: Discovery identified 5580 peptides belonging to 576 proteins; 58 proteins were differentially abundant with ⩾2 peptides between POMS and mADS, of which 28 more abundant in POMS. Fourteen had increased abundance in POMS with ⩾8 unique peptides. Five selected proteins were all confirmed within validation. Adjusted for age, 2 out of 5 proteins remained more abundant in POMS, that is, Carboxypeptidase E (CPE) and Semaphorin-7A (SEMA7A). CONCLUSION: This exploratory study identified several CSF proteins associated with POMS and not mADS, potentially reflecting neurodegeneration, compensatory neuroprotection, and humoral response in POMS. The proteins associated with POMS highly correlated with age at CSF sampling.

Comparison of acute flaccid myelitis and transverse myelitis in children and evaluation of diagnostic criteria.

BACKGROUND AND PURPOSE: Acute flaccid myelitis (AFM) and transverse myelitis (TM) are serious conditions that may be difficult to differentiate, especially at onset of disease. In this study, we compared clinical features of pediatric AFM and TM and evaluated current diagnostic criteria, aiming to improve early and accurate diagnosis. METHODS: Two cohorts of children with enterovirus D68-associated AFM and clinically diagnosed TM were compared regarding presenting clinical features, additional investigations, and outcome. Current diagnostic criteria for AFM and TM were applied to evaluate their specificity. RESULTS: Children with AFM (n = 21) compared to those with TM (n = 36) were younger (median 3 vs. 10 years), more often had a prodromal illness (100% vs. 39%), predominant proximal weakness (69% vs. 17%), and hyporeflexia (100% vs. 44%), and less often had sensory deficits (0% vs. 81%), bowel and/or bladder dysfunction (12% vs. 69%), and hyperreflexia (0% vs. 44%). On magnetic resonance imaging, brainstem involvement was more common in AFM (74% vs. 21%), whereas supratentorial abnormalities were only seen in TM (0% vs. 40%). When omitting the criterion of a sensory level, 11 of 15 (73%) children with AFM fulfilled the diagnostic criteria for TM. Of children with TM, four of 33 (12%) fulfilled the diagnostic criteria for probable/definite AFM. CONCLUSIONS: Although there is considerable overlap between AFM and TM in children, we found important early differentiating clinical and diagnostic features. Meeting diagnostic criteria for AFM in children with TM and vice versa underlines the importance of thorough clinical examination and early and accurate diagnostic studies.

Gut microbiota analysis in pediatric-onset multiple sclerosis compared to pediatric monophasic demyelinating syndromes and pediatric controls.

BACKGROUND AND PURPOSE: Gut microbiota dysbiosis may lead to proinflammatory conditions contributing to multiple sclerosis (MS) etiology. Pediatric-onset MS patients are close to biological disease onset and less exposed to confounders. Therefore, this study investigated gut microbiota composition and functional pathways in pediatric-onset MS, compared to monophasic acquired demyelinating syndromes (mADS) and healthy controls (HCs). METHODS: Pediatric participants were selected from the Dutch national prospective cohort study including ADS patients and HCs <18 years old. Amplicon sequence variants (ASVs) were generated from sequencing the V3/4 regions of the 16S rRNA gene. Functional MetaCyc microbial pathways were predicted based on Enzyme Commission numbers. Gut microbiota composition (alpha/beta diversity and individual microbe abundance at ASV to phylum level) and predicted functional pathways were tested using nonparametric tests, permutational multivariate analysis of variance, and linear regression. RESULTS: Twenty-six pediatric-onset MS (24 with disease-modifying therapy [DMT]), 25 mADS, and 24 HC subjects were included. Alpha/beta diversity, abundance of individual resident microbes, and microbial functional features were not different between these participant groups. Body mass index (BMI) showed significant differences, with obese children having a lower alpha diversity (Chao1 Index p = 0.015, Shannon/Simpson Diversity Index p = 0.014/p = 0.023), divergent beta diversity (R2  = 3.7%, p = 0.013), and higher abundance of numerous individual resident microbes and functional microbial pathways. CONCLUSIONS: Previous results of gut microbiota composition and predicted functional features could not be validated in this Dutch pediatric-onset MS cohort using a more sensitive 16S pipeline, although it was limited by sample size and DMT use. Notably, several other host-related factors were found to associate with gut microbiota variation, especially BMI.

Multiple sclerosis risk variants influence the peripheral B-cell compartment early in life in the general population.

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) is associated with abnormal B-cell function, and MS genetic risk alleles affect multiple genes that are expressed in B cells. However, how these genetic variants impact the B-cell compartment in early childhood is unclear. In the current study, we aim to assess whether polygenic risk scores (PRSs) for MS are associated with changes in the blood B-cell compartment in children from the general population. METHODS: Six-year-old children from the population-based Generation R Study were included. Genotype data were used to calculate MS-PRSs and B-cell subset-enriched MS-PRSs, established by designating risk loci based on expression and function. Analyses of variance were performed to examine the effect of MS-PRSs on total B-cell numbers (n = 1261) as well as naive and memory subsets (n = 675). RESULTS: After correction for multiple testing, no significant associations were observed between MS-PRSs and total B-cell numbers and frequencies of subsets therein. A naive B-cell-MS-PRS (n = 26 variants) was significantly associated with lower relative, but not absolute, naive B-cell numbers (p = 1.03 × 10-4 and p = 0.82, respectively), and higher frequencies and absolute numbers of CD27+ memory B cells (p = 8.83 × 10-4 and p = 4.89 × 10-3 , respectively). These associations remained significant after adjustment for Epstein-Barr virus seropositivity and the HLA-DRB1*15:01 genotype. CONCLUSIONS: The composition of the blood B-cell compartment is associated with specific naive B-cell-associated MS risk variants during childhood, possibly contributing to MS pathophysiology later in life. Cell subset-specific PRSs may offer a more sensitive tool to define the impact of genetic risk on the immune system in diseases such as MS.

White matter microstructural differences in children and genetic risk for multiple sclerosis: A population-based study.

BACKGROUND: MS patients show abnormalities in white matter (WM) on brain imaging, with heterogeneity in the location of WM lesions. The "pothole" method can be applied to diffusion-weighted images to identify spatially distinct clusters of divergent brain WM microstructure. OBJECTIVE: To investigate the association between genetic risk for MS and spatially independent clusters of decreased or increased fractional anisotropy (FA) in the brain. In addition, we studied sex- and age-related differences. METHODS: 3 Tesla diffusion tensor imaging (DTI) data were collected in 8- to 12-year-old children from a population-based study. Global and tract-based potholes (lower FA clusters) and molehills (higher FA clusters) were quantified in 3047 participants with usable DTI data. A polygenic risk score (PRS) for MS was calculated in genotyped individuals (n = 1087) and linear regression analyses assessed the relationship between the PRS and the number of potholes and molehills, correcting for multiple testing using the False Discovery Rate. RESULTS: The number of molehills increased with age, potholes decreased with age, and fewer potholes were observed in girls during typical development. The MS-PRS was positively associated with the number of molehills (ß = 0.9, SE = 0.29, p = 0.002). Molehills were found more often in the corpus callosum (ß = 0.3, SE = 0.09, p = 0.0003). CONCLUSION: Genetic risk for MS is associated with spatially distinct clusters of increased FA during childhood brain development.

Epidemiology of acute flaccid myelitis in children in the Netherlands, 2014 to 2019.

BackgroundAcute flaccid myelitis (AFM) is a polio-like condition affecting mainly children and involving the central nervous system (CNS). AFM has been associated with different non-polio-enteroviruses (EVs), in particular EV-D68 and EV-A71. Reliable incidence rates in European countries are not available.AimTo report AFM incidence in children in the Netherlands and its occurrence relative to EV-D68 and EV-A71 detections.MethodsIn 10 Dutch hospitals, we reviewed electronic health records of patients diagnosed with a clinical syndrome including limb weakness and/or CNS infection and who were < 18 years old when symptoms started. After excluding those with a clear alternative diagnosis to AFM, those without weakness, and removing duplicate records, only patients diagnosed in January 2014-December 2019 were retained and further classified according to current diagnostic criteria. Incidence rates were based on definite and probable AFM cases. Cases' occurrences during the study period were co-examined with laboratory-surveillance detections of EV-D68 and EV-A71.ResultsAmong 143 patients included, eight were classified as definite and three as probable AFM. AFM mean incidence rate was 0.06/100,000 children/year (95% CI: -0.03 to 0.14). All patient samples were negative for EV-A71. Of respiratory samples in seven patients, five were EV-D68 positive. AFM cases clustered in periods with increased EV-D68 and EV-A71 detections.ConclusionsAFM is rare in children in the Netherlands. The temporal coincidence of EV-D68 circulation and AFM and the detection of this virus in several cases' samples support its association with AFM. Increased AFM awareness among clinicians, adequate diagnostics and case registration matter to monitor the incidence.

Polygenic Multiple Sclerosis Risk and Population-Based Childhood Brain Imaging.

OBJECTIVE: Multiple sclerosis (MS) is a neurological disease with a substantial genetic component and immune-mediated neurodegeneration. Patients with MS show structural brain differences relative to individuals without MS, including smaller regional volumes and alterations in white matter (WM) microstructure. Whether genetic risk for MS is associated with brain structure during early neurodevelopment remains unclear. In this study, we explore the association between MS polygenic risk scores (PRS) and brain imaging outcomes from a large, population-based pediatric sample to gain insight into the underlying neurobiology of MS. METHODS: We included 8- to 12-year-old genotyped participants from the Generation R Study in whom T1-weighted volumetric (n = 1,136) and/or diffusion tensor imaging (n = 1,088) had been collected. PRS for MS were calculated based on a large genome-wide association study of MS (n = 41,505) and were regressed on regional volumes, global and tract-specific fractional anisotropy (FA), and global mean diffusivity using linear regression. RESULTS: No associations were observed for the regional volumes. We observed a positive association between the MS PRS and global FA (ß = 0.098, standard error [SE] = 0.030, p = 1.08 × 10-3 ). Tract-specific analyses showed higher FA and lower radial diffusivity in several tracts. We replicated our findings in an independent sample of children (n = 186) who were scanned in an earlier phase (global FA; ß = 0.189, SE = 0.072, p = 9.40 × 10-3 ). INTERPRETATION: This is the first study to show that greater genetic predisposition for MS is associated with higher global brain WM FA at an early age in the general population. Our results suggest a preadolescent time window within neurodevelopment in which MS risk variants act upon the brain. ANN NEUROL 2020;87:774-787.

T cell composition and polygenic multiple sclerosis risk: A population-based study in children.

BACKGROUND AND PURPOSE: Patients with multiple sclerosis (MS) have altered T cell function and composition. Common genetic risk variants for MS affect proteins that function in the immune system. It is currently unclear to what extent T cell composition is affected by genetic risk factors for MS, and how this may precede a possible disease onset. Here, we aim to assess whether an MS polygenic risk score (PRS) is associated with an altered T cell composition in a large cohort of children from the general population. METHODS: We included genotyped participants from the population-based Generation R study in whom immunophenotyping of blood T cells was performed at the age of 6 years. Analyses of variance were used to determine the impact of MS-PRSs on total T cell numbers (n = 1261), CD4+ and CD8+ lineages, and subsets therein (n= 675). In addition, T-cell-specific PRSs were constructed based on functional pathway data. RESULTS: The MS-PRS negatively correlated with CD8+ T cell frequencies (p = 2.92 × 10-3 ), which resulted in a positive association with CD4+ /CD8+ T cell ratios (p = 8.27 × 10-9 ). These associations were mainly driven by two of 195 genome-wide significant MS risk variants: the main genetic risk variant for MS, HLA-DRB1*15:01 and an HLA-B risk variant. We observed no significant associations for the T-cell-specific PRSs. CONCLUSIONS: Our results suggest that MS-associated genetic variants affect T cell composition during childhood in the general population.

Atypical neuroimaging characteristics of hemophagocytic lymphohistiocytosis in infants: a case series of hemorrhagic brain lesions in the deep grey matter.

Hemophagocytic lymphohistiocytosis (HLH) is a rare multisystem condition associated with uncontrolled overproduction and infiltration of lymphocytes and histiocytes predominantly in liver, lymph nodes, spleen, and central nervous system. Neuroimaging findings on MRI are fairly nonspecific and classically include periventricular white matter signal abnormalities and diffuse atrophy. Focal parenchymal lesions may demonstrate post contrast ring or nodular enhancement and calcification. However, the MR imaging characteristics can be highly variable. Here, we present two cases of HLH in infants with multiple hemorrhagic lesions mostly depicted in both thalami and basal ganglia regions. Thalamic, basal ganglia, and brain stem involvement with hemorrhagic changes in HLH are rarely described in literature. Early diagnosis of HLH may be lifesaving. Awareness of the disease is necessary to investigate its characteristic findings and avoiding a delay in diagnosis.

High neurofilament levels are associated with clinically definite multiple sclerosis in children and adults with clinically isolated syndrome.

BACKGROUND: A promising biomarker for axonal damage early in the disease course of multiple sclerosis (MS) is neurofilament light chain (NfL). It is unknown whether NfL has the same predictive value for MS diagnosis in children as in adults. OBJECTIVE: To explore the predictive value of NfL levels in cerebrospinal fluid (CSF) for MS diagnosis in paediatric and adult clinically isolated syndrome (CIS) patients. METHODS: A total of 88 adult and 65 paediatric patients with a first attack of demyelination were included and followed (mean follow up-time in adults: 62.8 months (standard deviation (SD) ±38.7 months) and 43.8 months (SD ±27.1 months) in children). Thirty control patients were also included. Lumbar puncture was done within 6 months after onset of symptoms. NfL was determined in CSF using enzyme-linked immunosorbent assay (ELISA). COX regression analyses were used to calculate hazard ratios (HR) for clinically definite multiple sclerosis (CDMS) diagnosis. RESULTS: After adjustments for age, oligoclonal bands (OCB), and asymptomatic T2 lesions on baseline magnetic resonance imaging (MRI), increased NfL levels in both paediatric and adult CIS patients were associated with a shorter time to CDMS diagnosis (children HR = 3.7; p = 0.007, adults HR = 2.1; p = 0.032). For CIS patients with a future CDMS diagnosis, children showed higher NfL levels than adults (geometric mean 4888 vs 2156 pg/mL; p = 0.007). CONCLUSION: CSF NfL levels are associated with CDMS diagnosis in children and adults with CIS. This makes NfL a promising predictive marker for disease course with potential value in clinical practice.

A framework for measurement and harmonization of pediatric multiple sclerosis etiologic research studies: The Pediatric MS Tool-Kit.

BACKGROUND: While studying the etiology of multiple sclerosis (MS) in children has several methodological advantages over studying etiology in adults, studies are limited by small sample sizes. OBJECTIVE: Using a rigorous methodological process, we developed the Pediatric MS Tool-Kit, a measurement framework that includes a minimal set of core variables to assess etiological risk factors. METHODS: We solicited input from the International Pediatric MS Study Group to select three risk factors: environmental tobacco smoke (ETS) exposure, sun exposure, and vitamin D intake. To develop the Tool-Kit, we used a Delphi study involving a working group of epidemiologists, neurologists, and content experts from North America and Europe. RESULTS: The Tool-Kit includes six core variables to measure ETS, six to measure sun exposure, and six to measure vitamin D intake. The Tool-Kit can be accessed online ( www.maelstrom-research.org/mica/network/tool-kit ). CONCLUSION: The goals of the Tool-Kit are to enhance exposure measurement in newly designed pediatric MS studies and comparability of results across studies, and in the longer term to facilitate harmonization of studies, a methodological approach that can be used to circumvent issues of small sample sizes. We believe the Tool-Kit will prove to be a valuable resource to guide pediatric MS researchers in developing study-specific questionnaire.

Ketogenic diet treatment in recurrent diffuse intrinsic pontine glioma in children: A safety and feasibility study.

BACKGROUND: The mean overall survival rate of children with diffuse intrinsic pontine glioma (DIPG) is 9-11 months, with current standard treatment with fractionated radiotherapy and adjuvant chemotherapy. So far, novel therapeutic strategies have not yet resulted in significantly better survival. The main source of energy for glioblastoma cells is glucose. Therefore, metabolic alterations induced by the use of the extremely carbohydrate-restricted ketogenic diet (KD) as adjuvant therapy are subject of interest in cancer research. PROCEDURE: This study explores the safety and feasibility of the KD in children with recurrent DIPG and no remaining treatment options. Safety was defined as the number of adverse effects. Feasibility was defined as the number of patients who were able to use the KD for three months. Coping of patients and parents was measured with questionnaires. RESULTS: Three of 14 children referred to our hospital between 2010 and 2015 were included. Two patients completed the study, and one died before the end of the study. Hospitalizations were needed for placing a nasogastric tube (n = 1) and epileptic seizures (n = 1). Adverse effects related to the diet were mild and transient. Parents were highly motivated during the study. CONCLUSION: Use of KD is safe and feasible, but the effect on survival has to be proven in a larger cohort of children who start the KD earlier after diagnosis, preferably as adjuvant therapy to fractionated radiotherapy.

Acute flaccid myelitis and enterovirus D68: lessons from the past and present.

Acute flaccid myelitis is characterized by the combination of acute flaccid paralysis and a spinal cord lesion largely restricted to the gray matter on magnetic resonance imaging. The term acute flaccid myelitis was introduced in 2014 after the upsurge of pediatric cases in the USA with enterovirus D68 infection. Since then, an increasing number of cases have been reported worldwide. Whereas the terminology is new, the clinical syndrome has been recognized in the past in association with several other neurotropic viruses such as poliovirus.Conclusion: This review presents the current knowledge on acute flaccid myelitis with respect to the clinical presentation and its differential diagnosis with Guillain-Barré syndrome and acute transverse myelitis. We also discuss the association with enterovirus D68 and the presumed pathophysiological mechanism of this infection causing anterior horn cell damage. Sharing clinical knowledge and insights from basic research is needed to make progress in diagnosis, treatment, and prevention of this new polio-like disease. What is Known: • Acute flaccid myelitis (AFM) is a polio-like condition characterized by rapid progressive asymmetric weakness, together with specific findings on MRI • AFM has been related to different viral agents, but recent outbreaks are predominantly associated with enterovirus D68. What is New: • Improving knowledge on AFM must increase early recognition and adequate diagnostic procedures by clinicians. • The increasing incidence of AFM urges cooperation between pediatricians, neurologists, and microbiologists for the development of treatment and preventive options.

Fatigue and physical functioning in children with multiple sclerosis and acute disseminated encephalomyelitis.

BACKGROUND AND OBJECTIVE: Fatigue and physical impairments are a major concern in children with multiple sclerosis (MS) and after acute disseminated encephalomyelitis (post-ADEM). We here aimed to evaluate the interaction between fatigue, exercise capacity, motor performance, neurological status, and quality of life (HRQoL). METHODS: In this cross-sectional study, data of 38 children (MS n = 22, post-ADEM n = 16), aged 4-17 years attending our national pediatric MS center, were studied. Fatigue was measured with the Pediatric Quality of Life Multidimensional Fatigue Scale, exercise capacity with the Bruce Protocol, motor performance with the Movement Assessment Battery for Children second edition, HRQoL with the Pediatric Quality of Life Questionnaire, and extent of disability with the Expanded Disability Status Scale (EDSS). RESULTS: Children with MS and post-ADEM experienced more fatigue ( p < 0.001), reduced exercise capacity ( p < 0.001), and impaired motor performance ( p < 0.001), despite low scores on the EDSS. Fatigue, but not the other parameters, was significantly correlated with HRQoL. Fatigue was not correlated with exercise capacity. CONCLUSION: We confirm the major impact of fatigue on quality of life in children with MS and post-ADEM. Fatigue was not explained by reduced exercise capacity or impaired motor performance. An important finding for clinical practice is that the low EDSS score did not reflect the poor physical functioning.

T-cell activation marker sCD27 is associated with clinically definite multiple sclerosis in childhood-acquired demyelinating syndromes.

BACKGROUND: Cerebrospinal fluid (CSF) levels of T-cell activation marker soluble CD27 (sCD27) are associated with subsequent disease activity after a first attack of suspected MS in adults. The predictive value for disease course in children with acquired demyelinating syndromes (ADS) is unknown. OBJECTIVES: To assess the predictive value of sCD27 levels for clinically definite multiple sclerosis (CDMS) diagnosis in childhood ADS. METHODS: Children <18 years with a first demyelinating event were prospectively included and followed. Soluble CD27 was determined in CSF using an enzyme-linked immunosorbent assay (ELISA). Cox regression analyses were used to calculate hazard ratios (HRs) for CDMS. RESULTS: A total of 94 ADS children were included (ADS with encephalopathy (ADS+) n = 33 and ADS without encephalopathy (ADS-) n = 61). Of the 61 ADS- children, 21 (48%) were diagnosed with CDMS during follow-up. At baseline, sCD27 levels were higher in patients with a future CDMS diagnosis ( n = 29) than in monophasic ADS+ ( n = 30), monophasic ADS- ( n = 28) and relapsing non-MS patients ( n = 7; p < 0.001). In ADS- patients, sCD27 was associated with CDMS (HR = 1.8 per 100 U/mL increase in sCD27 levels, p = 0.031), after adjustments for age, oligoclonal bands and the presence of dissemination in space on baseline magnetic resonance imaging (MRI). CONCLUSION: CSF sCD27 levels at first attack of demyelination were associated with CDMS diagnosis in children. This makes sCD27 a potential clinically relevant quantitative marker when performing routine CSF diagnostics.

Neurogenic lower urinary tract dysfunction in the early disease phase of paediatric multiple sclerosis.

Neurogenic lower urinary tract dysfunction (LUTD) in multiple sclerosis (MS) is highly prevalent in adults, but has not previously been described in paediatric MS. A total of 24 consecutive children with newly diagnosed MS were prospectively assessed for bladder and bowel problems early after diagnosis. Five of 24 children (21%) showed LUTD during assessment. One of these patients did not report voiding complaints. This high prevalence of LUTD indicates that all recently diagnosed patients with paediatric MS should be evaluated early in their disease and treated for urinary problems in order to prevent potential damage to the upper urinary tract.

Neuronal antibodies in pediatric epilepsy: Clinical features and long-term outcomes of a historical cohort not treated with immunotherapy.

OBJECTIVE: In autoimmune encephalitis the etiologic role of neuronal cell-surface antibodies is clear; patients diagnosed and treated early have better outcomes. Neuronal antibodies have also been described in patients with pediatric epilepsy without encephalitis. The aim was to assess whether antibody presence had any effect on long-term outcomes in these patients. METHODS: Patients (n = 178) were recruited between 1988 and 1992 as part of the prospective Dutch Study of Epilepsy in Childhood; none received immunotherapy. Healthy age-matched bone-marrow donors served as controls (n = 112). All sera were tested for serum N-methyl-d-aspartate receptor (NMDAR), alpha amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor, leucine rich glioma inactivated 1, contactin associated protein like 2 (CASPR2), contactin-2, glutamic acid decarboxylase, and voltage gated potassium channel (VGKC)-complex antibodies by standard techniques. No cerebrospinal fluid (CSF) samples were available. Results were correlated with clinical data collected over 15 years. RESULTS: Seventeen patients (9.5%) were positive for VGKC complex (n = 3), NMDAR (n = 7), CASPR2 (n = 4), and contactin-2 (n = 3), compared to three (3/112; 2.6%) healthy controls (VGKC complex [n = 1], NMDAR [n = 2]; p = 0.03; Fisher's exact test). Titers were relatively low (≤1:100 for cell-surface antibodies), but 8 (47%) of the 17 positive samples bound to the surface of live hippocampal neurons consistent with a potential pathogenic antibody. Preexisting cognitive impairment was more frequent in antibody-positive patients (9/17 vs. 33/161; p = 0.01). Fourteen antibody-positive patients were treated with standard antiepileptic drugs (AEDs); three (17%) became intractable but this was not different from the 16 (10%) of 161 antibody-negative patients. In 96 patients with available follow-up samples at 6 and/or 12 months, 6 of 7 positive antibodies had disappeared and, conversely, antibodies had appeared for the first time in a further 7 patients. SIGNIFICANCE: Neuronal antibodies were found at low levels in 9.5% of patients with new-onset pediatric epilepsy but did not necessarily persist over time, and the development of antibodies de novo in later samples suggests they could be due to a secondary response to neuronal damage or inflammation. Moreover, as the response to standard AEDs and the long-term outcome did not differ from those of antibody-negative pediatric patients, these findings suggest that routine neuronal antibody testing is unlikely to be helpful in pediatric epilepsy. However, the higher incidence of preexisting cognitive problems in the antibody-positive group, the CASPR2 and contactin-2 antibodies in 7 of 17 patients, and the binding of 8 of 17 of serum samples to live hippocampal neurons suggest that neuronal antibodies, even if secondary, could contribute to the comorbidities of pediatric epilepsy.