Improving newborn screening test performance for metachromatic leukodystrophy: Recommendation from a pre-pilot study that identified a late-infantile case for treatment.

Metachromatic leukodystrophy (MLD) is a devastating rare neurodegenerative disease. Typically, loss of motor and cognitive skills precedes early death. The disease is characterised by deficient lysosomal arylsulphatase A (ARSA) activity and an accumulation of undegraded sulphatide due to pathogenic variants in the ARSA gene. Atidarsagene autotemcel (arsa-cel), an ex vivo haematopoietic stem cell gene therapy was approved for use in the UK in 2021 to treat early-onset forms of pre- or early-symptomatic MLD. Optimal outcomes require early diagnosis, but in the absence of family history this is difficult to achieve without newborn screening (NBS). A pre-pilot MLD NBS study was conducted as a feasibility study in Manchester UK using a two-tiered screening test algorithm. Pre-established cutoff values (COV) for the first-tier C16:0 sulphatide (C16:0-S) and the second-tier ARSA tests were evaluated. Before the pre-pilot study, initial test validation using non­neonatal diagnostic bloodspots demonstrated ARSA pseudodeficiency status was associated with normal C16:0-S results for age (n = 43) and hence not expected to cause false positive results in this first-tier test. Instability of ARSA in bloodspot required transfer of NBS bloodspots from ambient temperature to -20°C storage within 7-8 days after heel prick, the earliest possible in this UK pre-pilot study. Eleven of 3687 de-identified NBS samples in the pre-pilot were positive for C16:0-S based on the pre-established COV of ≥170 nmol/l or ≥ 1.8 multiples of median (MoM). All 11 samples were subsequently tested negative determined by the ARSA COV of <20% mean of negative controls. However, two of 20 NBS samples from MLD patients would be missed by this C16:0-S COV. A further suspected false negative case that displayed 4% mean ARSA activity by single ARSA analysis for the initial test validation was confirmed by genotyping of this NBS bloodspot, a severe late infantile MLD phenotype was predicted. This led to urgent assessment of this child by authority approval and timely commencement of arsa-cel gene therapy at 11 months old. Secondary C16:0-S analysis of this NBS bloodspot was 150 nmol/l or 1.67 MoM. This was the lowest result reported thus far, a new COV of 1.65 MoM is recommended for future pilot studies. Furthermore, preliminary data of this study showed C16:1-OH sulphatide is more specific for MLD than C16:0-S. In conclusion, this pre-pilot study adds to the international evidence that recommends newborn screening for MLD, making it possible for patients to benefit fully from treatment through early diagnosis.

Newborn screening in metachromatic leukodystrophy - European consensus-based recommendations on clinical management.

INTRODUCTION: Metachromatic leukodystrophy (MLD) is a rare autosomal recessive lysosomal storage disorder resulting from arylsulfatase A enzyme deficiency, leading to toxic sulfatide accumulation. As a result affected individuals exhibit progressive neurodegeneration. Treatments such as hematopoietic stem cell transplantation (HSCT) and gene therapy are effective when administered pre-symptomatically. Newborn screening (NBS) for MLD has recently been shown to be technically feasible and is indicated because of available treatment options. However, there is a lack of guidance on how to monitor and manage identified cases. This study aims to establish consensus among international experts in MLD and patient advocates on clinical management for NBS-identified MLD cases. METHODS: A real-time Delphi procedure using eDELPHI software with 22 experts in MLD was performed. Questions, based on a literature review and workshops, were answered during a seven-week period. Three levels of consensus were defined: A) 100%, B) 75-99%, and C) 50-74% or >75% but >25% neutral votes. Recommendations were categorized by agreement level, from strongly recommended to suggested. Patient advocates participated in discussions and were involved in the final consensus. RESULTS: The study presents 57 statements guiding clinical management of NBS-identified MLD patients. Key recommendations include timely communication by MLD experts with identified families, treating early-onset MLD with gene therapy and late-onset MLD with HSCT, as well as pre-treatment monitoring schemes. Specific knowledge gaps were identified, urging prioritized research for future evidence-based guidelines. DISCUSSION: Consensus-based recommendations for NBS in MLD will enhance harmonized management and facilitate integration in national screening programs. Structured data collection and monitoring of screening programs are crucial for evidence generation and future guideline development. Involving patient representatives in the development of recommendations seems essential for NBS programs.

Inventory of current practices regarding hematopoietic stem cell transplantation in metachromatic leukodystrophy in Europe and neighboring countries.

BACKGROUND: For decades, early allogeneic stem cell transplantation (HSCT) has been used to slow neurological decline in metachromatic leukodystrophy (MLD). There is lack of consensus regarding who may benefit, and guidelines are lacking. Clinical practice relies on limited literature and expert opinions. The European Reference Network for Rare Neurological Diseases (ERN-RND) and the MLD initiative facilitate expert panels for treatment advice, but some countries are underrepresented. This study explores organizational and clinical HSCT practices for MLD in Europe and neighboring countries to enhance optimization and harmonization of cross-border MLD care. METHODS: A web-based EUSurvey was distributed through the ERN-RND and the European Society for Blood and Marrow Transplantation Inborn Errors Working Party. Personal invitations were sent to 89 physicians (43 countries) with neurological/metabolic/hematological expertise. The results were analyzed and visualized using Microsoft Excel and IBM SPSS statistics. RESULTS: Of the 30 countries represented by 42 respondents, 23 countries offer HSCT for MLD. The treatment is usually available in 1-3 centers per country (18/23, 78%). Most countries have no or very few MLD patients transplanted during the past 1-5 years. The eligibility criteria regarding MLD subtype, motor function, IQ, and MRI largely differ across countries. CONCLUSION: HSCT for MLD is available in most European countries, but uncertainties exist in Eastern and South-Eastern Europe. Applied eligibility criteria and management vary and may not align with the latest scientific insights, indicating physicians' struggle in providing evidence-based care. Interaction between local physicians and international experts is crucial for adequate treatment decision-making and cross-border care in the rapidly changing MLD field.

First in man study of intravitreal tripeptidyl peptidase 1 for CLN2 retinopathy.

BACKGROUND/OBJECTIVES: CLN2 Batten Disease is a fatal neurodegenerative condition of childhood associated with retinal dystrophy and blindness. Intracerebroventricular infusion of rhTPP1 greatly slows the rate of neurodegenerative decline but not retinopathy. Intravitreal rhTPP1 is known to slow retinal degeneration in a canine model of CLN2. We report a first-in-man controlled clinical trial of intravitreal rhTPP1 for CLN2 associated retinal dystrophy. SUBJECTS/METHODS: 8 children aged 5-9 with CLN2 Batten Disease were prospectively enroled. Severely affected patients were preferentially selected, provided that vision was better than no perception of light. Children underwent 8 weekly intravitreal injections of rhTPP1 (0.2 mg in 0.05 ml) into the right eye for 12-18 months. The left eye was untreated and acts as a paired control. The primary outcome was safety based on the clinical detection of complications. A secondary outcome was paracentral macular volume (PMV) measured by spectral domain OCT. Linear regression/paired t tests were used to compare rates of decline. RESULTS: No severe adverse reactions (uveitis, raised IOP, media opacity) occurred. The mean baseline PMV was 1.28 mm3(right), 1.27 mm3(left). 3 of the youngest patients exhibited bilateral progressive retinal thinning (p < 0.05), whereas retinal volume was stable in the remaining 5 patients. In the 3 patients undergoing retinal degeneration, the rate of PMV loss was slower in the treated vs. untreated eye (p = 0.000042, p = 0.0011, p = 0.00022). CONCLUSIONS: Intravitreal rhTPP1 appears to be a safe and effective treatment for CLN2 related retinopathy however commencement of treatment early in the course of disease is more likely to be efficacious.

Evolution of brain MRI lesions in paediatric myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and its relevance to disease course.

BACKGROUND: Lesion resolution is often observed in children with myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and asymptomatic lesions are less commonly reported in MOGAD than in multiple sclerosis (MS). OBJECTIVE: We aimed to evaluate brain MRI changes over time in paediatric MOGAD. METHODS: Retrospective study in eight UK paediatric neuroscience centres. Acute brain MRI and available follow-up MRIs were reviewed. Predictors for lesion dynamic were evaluated using multivariable regression and Kaplan-Meier survival analyses were used to predict risk of relapse, disability and MOG-Ab status. RESULTS: 200 children were included (MOGAD 97; MS 103). At first MRI post attack, new symptomatic and asymptomatic lesions were seen more often in MS versus MOGAD (52/103 vs 28/97; p=0.002 and 37/103 vs 11/97; p<0.001); 83% of patients with MOGAD showed at least one lesion's resolution at first follow-up scan, and 23% had normal MRI. Only 1 patient with MS had single lesion resolution; none had normal MRI. Disappearing lesions in MOGAD were seen in 40% after the second attack, 21% after third attack and none after the fourth attack.New lesions at first follow-up scan were associated with increased likelihood of relapse (p=0.02) and persistent MOG-Ab serostatus (p=0.0016) compared with those with no new lesions. Plasma exchange was associated with increased likelihood of lesion resolution (p=0.01). Longer time from symptom onset to steroids was associated with increased likelihood of new lesions; 50% increase at 20 days (p=0.01). CONCLUSIONS: These striking differences in lesion dynamics between MOGAD and MS suggest greater potential to repair. Early treatment with steroids and plasma exchange is associated with reduced likelihood of new lesions.

A retrospective cohort study of Libmeldy (atidarsagene autotemcel) for MLD: What we have accomplished and what opportunities lie ahead.

Metachromatic leukodystrophy (MLD) results from ARSA gene mutations. Affected individuals meet early milestones before neurological deterioration and early death. Atidarsagene autotemcel (arsa-cel), an autologous haematopoietic stem cell gene therapy (HSC-GT) product, has demonstrated sustained clinical benefits in MLD. Arsa-cel was approved for NHS treatment in February 2022 for asymptomatic late infantile or early juvenile disease, or early symptomatic early juvenile MLD. We evaluate the impact of this approval in the largest real-world dataset of MLD HSC-GT. Hospital records were reviewed for all patients referred for NHS treatment following arsa-cel approval. Information was gathered about disease phenotype, presentation, eligibility, and affected siblings. In the year following NHS approval, 17 UK MLD patients were referred for treatment. Four patients met eligibility criteria and have been treated, including 1 infant who weighed 5 kg at leukapheresis. Eleven patients failed screening: 10 symptomatic patients with late infantile disease and 1 with early juvenile disease and cognitive decline. Two further patients with later onset subtypes did not meet the approval criteria. Three out of four treated patients were diagnosed by screening after MLD was diagnosed in a symptomatic older sibling. The success of HSC-GT for MLD has heralded a new era of hope for families affected by this devastating disease, yet currently, most patients are ineligible for treatment at diagnosis. The feasibility of apheresis in infants and the availability of a licenced, effective HSC-GT product highlights the urgent need for newborn screening to ensure that patients can be diagnosed and treated before symptom onset.

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

BACKGROUND: Data from the early pandemic revealed that 0.62% of children hospitalized with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had an acute arterial ischemic stroke (AIS). In a larger cohort from June 2020 to December 2020, we sought to determine whether our initial point estimate was stable as the pandemic continued and to understand radiographic and laboratory data that may clarify mechanisms of pediatric AIS in the setting of SARS-CoV-2. METHODS: We surveyed international sites with pediatric stroke expertise to determine numbers of hospitalized SARS-CoV-2 patients <18 years, numbers of incident AIS cases among children (29 days to <18 years), frequency of SARS-CoV-2 testing for children with AIS, and numbers of childhood AIS cases positive for SARS-CoV-2 June 1 to December 31, 2020. Two stroke neurologists with 1 neuroradiologist determined whether SARS-CoV-2 was the main stroke risk factor, contributory, or incidental. RESULTS: Sixty-one centers from 21 countries provided AIS data. Forty-eight centers (78.7%) provided SARS-CoV-2 hospitalization data. SARS-CoV-2 testing was performed in 335/373 acute AIS cases (89.8%) compared with 99/166 (59.6%) in March to May 2020, P<0.0001. Twenty-three of 335 AIS cases tested (6.9%) were positive for SARS-CoV-2 compared with 6/99 tested (6.1%) in March to May 2020, P=0.78. Of the 22 of 23 AIS cases with SARS-CoV-2 in whom we could collect additional data, SARS-CoV-2 was the main stroke risk factor in 6 (3 with arteritis/vasculitis, 3 with focal cerebral arteriopathy), a contributory factor in 13, and incidental in 3. Elevated inflammatory markers were common, occurring in 17 (77.3%). From centers with SARS-CoV-2 hospitalization data, of 7231 pediatric patients hospitalized with SARS-CoV-2, 23 had AIS (0.32%) compared with 6/971 (0.62%) from March to May 2020, P=0.14. CONCLUSIONS: The risk of AIS among children hospitalized with SARS-CoV-2 appeared stable compared with our earlier estimate. Among children in whom SARS-CoV-2 was considered the main stroke risk factor, inflammatory arteriopathies were the stroke mechanism.

Isolated central nervous system familial hemophagocytic lymphohistiocytosis (fHLH) presenting as a mimic of demyelination in children.

Isolated central nervous system (CNS) presentations of haemophagocytic lymphohistiocytosis (HLH), traditionally a systemic inflammatory condition, have been reported in adults and children. We identified nine patients with a diagnosis of isolated CNS familial hemophagocytic lymphohistiocytosis (fHLH) with symptom onset <18 years of age, and one asymptomatic sibling. Children with atypical chronic/recurrent CNS inflammation should be considered for immunological and genetic panel testing for fHLH even in the absence of any systemic inflammatory features. Despite haematopoietic stem cell transplantation (HSCT) being a mainstay of treatment, treatment failure and high morbidity and mortality post-HSCT suggest that alternative immune therapies may be worth considering.

Expanding the phenotypic spectrum of pathogenic variants in the PRRT2 gene: bilateral papilledema and abducens nerve palsies secondary to pseudotumor cerebri syndrome.

An 8-year-old girl with known pathogenic variant in the PRRT2 gene causing paroxysmal kinesigenic dyskinesia with infantile convulsions presented with bilateral papilledema and abducens nerve palsy, which was subsequently confirmed to be pseudotumor cerebri syndrome (PTCS). She was treated with acetazolamide and recovered baseline vision, with some residual papilledema. PTCS is not confirmed to be associated with pathogenic variants in the PRRT2 gene; however, this case in conjunction with a previously reported case of PTCS and unilateral abducens nerve palsy in a patient with PRRT2 variants, raises the possibility that PTCS is part of the phenotypic spectrum rather than being a coincidental occurrence.

Neurological manifestations of SARS-CoV-2 infection in hospitalised children and adolescents in the UK: a prospective national cohort study.

BACKGROUND: The spectrum of neurological and psychiatric complications associated with paediatric SARS-CoV-2 infection is poorly understood. We aimed to analyse the range and prevalence of these complications in hospitalised children and adolescents. METHODS: We did a prospective national cohort study in the UK using an online network of secure rapid-response notification portals established by the CoroNerve study group. Paediatric neurologists were invited to notify any children and adolescents (age <18 years) admitted to hospital with neurological or psychiatric disorders in whom they considered SARS-CoV-2 infection to be relevant to the presentation. Patients were excluded if they did not have a neurological consultation or neurological investigations or both, or did not meet the definition for confirmed SARS-CoV-2 infection (a positive PCR of respiratory or spinal fluid samples, serology for anti-SARS-CoV-2 IgG, or both), or the Royal College of Paediatrics and Child Health criteria for paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS). Individuals were classified as having either a primary neurological disorder associated with COVID-19 (COVID-19 neurology group) or PIMS-TS with neurological features (PIMS-TS neurology group). The denominator of all hospitalised children and adolescents with COVID-19 was collated from National Health Service England data. FINDINGS: Between April 2, 2020, and Feb 1, 2021, 52 cases were identified; in England, there were 51 cases among 1334 children and adolescents hospitalised with COVID-19, giving an estimated prevalence of 3·8 (95% CI 2·9-5·0) cases per 100 paediatric patients. 22 (42%) patients were female and 30 (58%) were male; the median age was 9 years (range 1-17). 36 (69%) patients were Black or Asian, 16 (31%) were White. 27 (52%) of 52 patients were classified into the COVID-19 neurology group and 25 (48%) were classified into the PIMS-TS neurology group. In the COVID-19 neurology group, diagnoses included status epilepticus (n=7), encephalitis (n=5), Guillain-Barré syndrome (n=5), acute demyelinating syndrome (n=3), chorea (n=2), psychosis (n=2), isolated encephalopathy (n=2), and transient ischaemic attack (n=1). The PIMS-TS neurology group more often had multiple features, which included encephalopathy (n=22 [88%]), peripheral nervous system involvement (n=10 [40%]), behavioural change (n=9 [36%]), and hallucinations at presentation (n=6 [24%]). Recognised neuroimmune disorders were more common in the COVID-19 neurology group than in the PIMS-TS neurology group (13 [48%] of 27 patients vs 1 [<1%] of 25 patients, p=0·0003). Compared with the COVID-19 neurology group, more patients in the PIMS-TS neurology group were admitted to intensive care (20 [80%] of 25 patients vs six [22%] of 27 patients, p=0·0001) and received immunomodulatory treatment (22 [88%] patients vs 12 [44%] patients, p=0·045). 17 (33%) patients (10 [37%] in the COVID-19 neurology group and 7 [28%] in the PIMS-TS neurology group) were discharged with disability; one (2%) died (who had stroke, in the PIMS-TS neurology group). INTERPRETATION: This study identified key differences between those with a primary neurological disorder versus those with PIMS-TS. Compared with patients with a primary neurological disorder, more patients with PIMS-TS needed intensive care, but outcomes were similar overall. Further studies should investigate underlying mechanisms for neurological involvement in COVID-19 and the longer-term outcomes. FUNDING: UK Research and Innovation, Medical Research Council, Wellcome Trust, National Institute for Health Research.

Use of Disease-Modifying Therapies in Pediatric Relapsing-Remitting Multiple Sclerosis in the United Kingdom.

OBJECTIVES: To compare the real-world effectiveness of newer disease-modifying therapies (DMTs) vs injectables in children with relapsing-remitting multiple sclerosis (RRMS). METHODS: In this retrospective, multicenter study, from the UK Childhood Inflammatory Demyelination Network, we identified children with RRMS receiving DMTs from January 2012 to December 2018. Clinical and paraclinical data were retrieved from the medical records. Annualized relapse rates (ARRs) before and on treatment, time to relapse, time to new MRI lesions, and change in Expanded Disability Status Scale (EDSS) score were calculated. RESULTS: Of 103 children treated with DMTs, followed up for 3.8 years, relapses on treatment were recorded in 53/89 (59.5%) on injectables vs 8/54 (15%) on newer DMTs. The ARR was reduced from 1.9 to 1.1 on injectables (p < 0.001) vs 1.6 to 0.3 on newer DMTs (p = 0.002). New MRI lesions occurred in 77/89 (86.5%) of patients on injectables vs 26/54 (47%) on newer DMTs (p = 0.0001). Children on newer DMTs showed longer time to relapse, time to switch treatment, and time to new radiologic activity than patients on injectables (log-rank p < 0.01). After adjustment for potential confounders, multivariable analysis showed that injectables were associated with 12-fold increased risk of clinical relapse (adjusted hazard ratio [HR] = 12.12, 95% CI = 1.64-89.87, p = 0.015) and a 2-fold increased risk of new radiologic activity (adjusted HR = 2.78, 95% CI = 1.08-7.13, p = 0.034) compared with newer DMTs. At 2 years from treatment initiation, 38/103 (37%) patients had MRI activity in the absence of clinical relapses. The EDSS score did not change during the follow-up, and only 2 patients had cognitive impairment. CONCLUSION: Newer DMTs were associated with a lower risk of clinical and radiologic relapses in patients compared with injectables. Our study adds weight to the argument for an imminent shift in practice toward the use of newer, more efficacious DMTs in the first instance. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that newer DMTs (oral or infusions) are superior to injectables (interferon beta/glatiramer acetate) in reducing both clinical relapses and radiologic activity in children with RRMS.

Two Paediatric Patients with Encephalopathy and Concurrent COVID-19 Infection: Two Sides of the Same Coin?

There is increasing evidence that SARS-CoV-2 has neurotropic potential. We report on two paediatric patients who presented with encephalopathy during COVID-19 illness. Both patients had ADEM-like changes in their neuroimaging, negative SARS-CoV-2 RNA PCR in CSF, and paucity of PIMS-TS laboratory findings. However, the first patient was positive for serum MOG antibodies with normal CSF analysis, and the second had negative MOG antibodies but showed significant CSF lymphocytic pleocytosis. We concluded that the first case was a typical case of demyelination, which could have been triggered by different cofactors. In the second case, however, we postulated that the encephalopathic process was triggered by SARS-CoV-2, as no other cause was identified. With these two contrasting cases, we provide evidence that SARS-CoV-2-associated encephalitis can show ADEM-like changes, which can present during the postinfectious phase of COVID-19 illness. As ADEM is a relatively common type of postinfectious encephalitis in children, the distinguishing line between the two conditions of encephalitis and ADEM can be relatively fine. The development of more reliable diagnostic tools (e.g., anti-SARS-CoV-2 antibodies in CSF) might play an assisting role in the differentiation of these encephalopathic processes.

Electroclinical features of MEF2C haploinsufficiency-related epilepsy: A multicenter European study.

PURPOSE: Epilepsy is a main manifestation in the autosomal dominant mental retardation syndrome caused by heterozygous variants in MEF2C. We aimed to delineate the electro-clinical features and refine the genotype-phenotype correlations in patients with MEF2C haploinsufficiency. METHODS: We thoroughly investigated 25 patients with genetically confirmed MEF2C-syndrome across 12 different European Genetics and Epilepsy Centers, focusing on the epileptic phenotype. Clinical features (seizure types, onset, evolution, and response to therapy), EEG recordings during waking/sleep, and neuroimaging findings were analyzed. We also performed a detailed literature review using the terms "MEF2C", "seizures", and "epilepsy". RESULTS: Epilepsy was diagnosed in 19 out of 25 (~80%) subjects, with age at onset <30 months. Ten individuals (40%) presented with febrile seizures and myoclonic seizures occurred in ~50% of patients. Epileptiform abnormalities were observed in 20/25 patients (80%) and hypoplasia/partial agenesis of the corpus callosum was detected in 12/25 patients (~50%). Nine patients harbored a 5q14.3 deletion encompassing MEF2C and at least one other gene. In 7 out of 10 patients with myoclonic seizures, MIR9-2 and LINC00461 were also deleted, whereas ADGRV1 was involved in 3/4 patients with spasms. CONCLUSION: The epileptic phenotype of MEF2C-syndrome is variable. Febrile and myoclonic seizures are the most frequent, usually associated with a slowing of the background activity and irregular diffuse discharges of frontally dominant, symmetric or asymmetric, slow theta waves with interposed spike-and-waves complexes. The haploinsufficiency of ADGRV1, MIR9-2, and LINC00461 likely contributes to myoclonic seizures and spasms in patients with MEF2C syndrome.

Neuroimaging manifestations in children with SARS-CoV-2 infection: a multinational, multicentre collaborative study.

BACKGROUND: The CNS manifestations of COVID-19 in children have primarily been described in case reports, which limit the ability to appreciate the full spectrum of the disease in paediatric patients. We aimed to identify enough cases that could be evaluated in aggregate to better understand the neuroimaging manifestations of COVID-19 in the paediatric population. METHODS: An international call for cases of children with encephalopathy related to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and abnormal neuroimaging findings was made. Clinical history and associated plasma and cerebrospinal fluid data were requested. These data were reviewed by a central neuroradiology panel, a child neurologist, and a paediatric infectious diseases expert. The children were categorised on the basis of their time of probable exposure to SARS-CoV-2. In addition, cases were excluded when a direct link to SARS-CoV-2 infection could not be established or an established alternate diagnostic cause could be hypothesised. The accepted referral centre imaging data, from ten countries, were remotely reviewed by a central panel of five paediatric neuroradiologists and a consensus opinion obtained on the imaging findings. FINDINGS: 38 children with neurological disease related to SARS-CoV-2 infection were identified from France (n=13), the UK (n=8), the USA (n=5), Brazil (n=4), Argentina (n=4), India (n=2), Peru (n=1), and Saudi Arabia (n=1). Recurring patterns of disease were identified, with neuroimaging abnormalities ranging from mild to severe. The most common imaging patterns were postinfectious immune-mediated acute disseminated encephalomyelitis-like changes of the brain (16 patients), myelitis (eight patients), and neural enhancement (13 patients). Cranial nerve enhancement could occur in the absence of corresponding neurological symptoms. Splenial lesions (seven patients) and myositis (four patients) were predominantly observed in children with multisystem inflammatory syndrome. Cerebrovascular complications in children were less common than in adults. Significant pre-existing conditions were absent and most children had favourable outcomes. However, fatal atypical CNS co-infections developed in four previously healthy children infected with SARS-CoV-2. INTERPRETATION: Acute-phase and delayed-phase SARS-CoV-2-related CNS abnormalities are seen in children. Recurring patterns of disease and atypical neuroimaging manifestations can be found and should be recognised being as potentially due to SARS-CoV-2 infection as an underlying aetiological factor. Studies of paediatric specific cohorts are needed to better understand the effects of SARS-CoV-2 infection on the CNS at presentation and on long-term follow-up in children. FUNDING: American Society of Pediatric Neuroradiology, University of Manchester (Manchester, UK). VIDEO ABSTRACT.

T2-highlighted U-fibres and rapid parenchymal volume loss in AESD: An under-recognised subtype of paediatric acute encephalopathy syndromes.

Acute Encephalopathy with Reduced Subcortical Diffusion or AED is a unique subtype of acute paediatric encephalopathy which presents with altered mental status, prolonged seizures and developing characteristic radiological signal changes within the subcortical white matter. Reports of such cases have mainly been from Japan (Takanashi, 2009) and this radiological finding has been recognised as a novel feature of AED. We present three paediatric cases from a tertiary paediatric neurosciences centre in Manchester (Royal Manchester Children's hospital) with characteristic subcortical signal change, and furthermore, follow up imaging which in all 3 patients demonstrated a varying degree of cerebral atrophy. We recommend that children presenting with prolonged seizures should be considered for MR imaging ideally after 48hours if clinically stable, and early MR imaging follow-up (at 2-3 months) be performed routinely in patients with AED to assess for presence and degree of parenchymal volume loss for prognostication and to start neuroprotective therapy.

Fifteen-minute consultation: A practical approach to developmental regression in children.

Developmental regression is an important red flag in any child's developmental performance and should be recognised promptly. It is the loss of previously acquired skills and can affect any sphere of childhood development. Presentation and underlying causes are heterogeneous in nature, in turn presenting many clinical challenges. While broad, the causes of regression can be categorised based on clinical findings, so that investigation and management options can be tailored appropriately. It is extremely important to try and make a definitive diagnosis if possible. This allows appropriate initiation of treatment for potentially reversible causes and for specific therapies, which may alter disease progression and improve quality of life in some cases. This article outlines a systematic approach to the evaluation of a child with suspected regression, covering the nature of presentation, key differential diagnoses, first-line investigations and management.

Retrospective natural history of thymidine kinase 2 deficiency.

BACKGROUND: Thymine kinase 2 (TK2) is a mitochondrial matrix protein encoded in nuclear DNA and phosphorylates the pyrimidine nucleosides: thymidine and deoxycytidine. Autosomal recessive TK2 mutations cause a spectrum of disease from infantile onset to adult onset manifesting primarily as myopathy. OBJECTIVE: To perform a retrospective natural history study of a large cohort of patients with TK2 deficiency. METHODS: The study was conducted by 42 investigators across 31 academic medical centres. RESULTS: We identified 92 patients with genetically confirmed diagnoses of TK2 deficiency: 67 from literature review and 25 unreported cases. Based on clinical and molecular genetics findings, we recognised three phenotypes with divergent survival: (1) infantile-onset myopathy (42.4%) with severe mitochondrial DNA (mtDNA) depletion, frequent neurological involvement and rapid progression to early mortality (median post-onset survival (POS) 1.00, CI 0.58 to 2.33 years); (2) childhood-onset myopathy (40.2%) with mtDNA depletion, moderate-to-severe progression of generalised weakness and median POS at least 13 years; and (3) late-onset myopathy (17.4%) with mild limb weakness at onset and slow progression to respiratory insufficiency with median POS of 23 years. Ophthalmoparesis and facial weakness are frequent in adults. Muscle biopsies show multiple mtDNA deletions often with mtDNA depletion. CONCLUSIONS: In TK2 deficiency, age at onset, rate of weakness progression and POS are important variables that define three clinical subtypes. Nervous system involvement often complicates the clinical course of the infantile-onset form while extraocular muscle and facial involvement are characteristic of the late-onset form. Our observations provide essential information for planning future clinical trials in this disorder.

The Genetics of Febrile Seizures.

Investigators from Virginia Commonwealth University, Norwegian Center for Epilepsy and University of Southern Denmark carried out twin studies to analyse the genetic influence of developing epilepsy after febrile seizures.