De Novo VPS4A Mutations Cause Multisystem Disease with Abnormal Neurodevelopment.

The endosomal sorting complexes required for transport (ESCRTs) are essential for multiple membrane modeling and membrane-independent cellular processes. Here we describe six unrelated individuals with de novo missense variants affecting the ATPase domain of VPS4A, a critical enzyme regulating ESCRT function. Probands had structural brain abnormalities, severe neurodevelopmental delay, cataracts, growth impairment, and anemia. In cultured cells, overexpression of VPS4A mutants caused enlarged endosomal vacuoles resembling those induced by expression of known dominant-negative ATPase-defective forms of VPS4A. Proband-derived fibroblasts had enlarged endosomal structures with abnormal accumulation of the ESCRT protein IST1 on the limiting membrane. VPS4A function was also required for normal endosomal morphology and IST1 localization in iPSC-derived human neurons. Mutations affected other ESCRT-dependent cellular processes, including regulation of centrosome number, primary cilium morphology, nuclear membrane morphology, chromosome segregation, mitotic spindle formation, and cell cycle progression. We thus characterize a distinct multisystem disorder caused by mutations affecting VPS4A and demonstrate that its normal function is required for multiple human developmental and cellular processes.

Brain monoamine vesicular transport disease caused by homozygous SLC18A2 variants: A study in 42 affected individuals.

PURPOSE: Brain monoamine vesicular transport disease is an infantile-onset movement disorder that mimics cerebral palsy. In 2013, the homozygous SLC18A2 variant, p.Pro387Leu, was first reported as a cause of this rare disorder, and dopamine agonists were efficient for treating affected individuals from a single large family. To date, only 6 variants have been reported. In this study, we evaluated genotype-phenotype correlations in individuals with biallelic SLC18A2 variants. METHODS: A total of 42 affected individuals with homozygous SLC18A2 variant alleles were identified. We evaluated genotype-phenotype correlations and the missense variants in the affected individuals based on the structural modeling of rat VMAT2 encoded by Slc18a2, with cytoplasm- and lumen-facing conformations. A Caenorhabditis elegans model was created for functional studies. RESULTS: A total of 19 homozygous SLC18A2 variants, including 3 recurrent variants, were identified using exome sequencing. The affected individuals typically showed global developmental delay, hypotonia, dystonia, oculogyric crisis, and autonomic nervous system involvement (temperature dysregulation/sweating, hypersalivation, and gastrointestinal dysmotility). Among the 58 affected individuals described to date, 16 (28%) died before the age of 13 years. Of the 17 patients with p.Pro237His, 9 died, whereas all 14 patients with p.Pro387Leu survived. Although a dopamine agonist mildly improved the disease symptoms in 18 of 21 patients (86%), some affected individuals with p.Ile43Phe and p.Pro387Leu showed milder phenotypes and presented prolonged survival even without treatment. The C. elegans model showed behavioral abnormalities. CONCLUSION: These data expand the phenotypic and genotypic spectra of SLC18A2-related disorders.

How to use lumbar puncture manometry in children.

Measurement of cerebrospinal fluid pressure through lumbar puncture (LP) manometry is an essential practical skill all paediatricians should possess competency in. The ability to perform manometry is crucial in the diagnosis of idiopathic intracranial hypertension and can provide critical information on raised (or lowered) intracranial pressure in other clinical scenarios. Practitioners should be familiar with the procedure and in particular with equipment available to them locally. In this article, we will describe an approach to LP manometry. The online supplemental material includes an instructional video as well as supporting practical information.

Cerebrospinal fluid dynamics in pediatric pseudotumor cerebri syndrome.

PURPOSE: There is a growing body of evidence highlighting the importance of comprehensive intracranial pressure (ICP) values in pseudotumor cerebri syndrome (PTCS). Due to the highly dynamic nature of ICP, several methods of ICP monitoring have been established, including the CSF infusion study. We have performed a retrospective review of the CSF dynamics measurements for all pediatric patients investigated for PTCS in our center and examined their diagnostic value compared with clinical classification. METHODS: We retrospectively recruited 31 patients under 16 years of age investigated for PTCS by CSF infusion test. We used the clinically provided Friedman classification 13/31 patients with definite PTCS (group A), 13/31 with probable PTCS (group B), and 5/31 not PTCS (group C), to compare CSF dynamics in the 3 groups. RESULTS: CSF pressure (CSFp) was significantly increased in group A (29.18 ± 7.72 mmHg) compared with B (15.31 ± 3.47 mmHg; p = 1.644e-05) and C (17.51 ± 5.87; p = 0.01368). The amplitude (AMP) was higher in the definite (2.18 ± 2.06 mmHg) than in group B (0.68 ± 0.37; p = 0.01382). There was no in either CSFp or AMP between groups B and C. No lower breakpoint of the AMP-P line was observed in group A but was present in 2/13 and 2/5 patients in groups B and C. In group A, sagittal sinus pressure (SSp) and elasticity were the only parameters above threshold (p = 4.2e-06 and p = 0.001953, respectively), In group B, only the elasticity was significantly higher than the threshold (p = 004257). Group C did not have any of the parameters raised. The AUC of CSFp, elasticity, and SSp for the 3 groups was 93.8% (84.8-100% CI). CONCLUSIONS: Monitoring of CSFp and its dynamics, besides providing a more precise methodology for measuring CSFp, could yield information on the dynamic parameters of CSFp that cannot be derived from CSFp as a number, accurately differentiating between the clinically and radiologically derived entities of PTCS.

Correlation between the total number of features of paediatric pseudotumour cerebri syndrome and cerebrospinal fluid pressure.

PURPOSE: Accurate diagnosis of pseudotumour cerebri syndrome (PTCS) in children is challenging. We aimed to see if the clinical and radiological assessment that is carried out before lumbar puncture could predict subsequently recorded CSF pressures, and thus whether it could be used to increase diagnostic certainty of paediatric PTCS. METHODS: We used internationally recognised diagnostic criteria to derive a list of clinical, brain neuroimaging and venography features that were accepted to be associated with a diagnosis of PTCS. We performed a retrospective cohort study of children referred to our centre with suspected PTCS, identifying the presence or absence of those features for each child at initial presentation. The sum total scores of the features that were present were correlated with the child's recorded CSF pressure. RESULTS: The sum total scores were significantly positively correlated with recorded CSF pressures. The positive correlation was seen when clinical and brain neuroimaging features were included alone, and the correlation was slightly stronger when venography features were included in addition. CONCLUSION: Calculating the sum total of clinical, brain neuroimaging and venography features (where venography is performed) present at initial presentation can help in the management of children under investigation for PTCS. Children with high scores are more likely to have severely raised CSF pressures and thus may warrant more urgent LP investigations. By contrast, in children with subtle abnormalities in optic disc appearance such that disc oedema cannot be ruled out, a low score may add further reassurance and less urgency to proceed to LP.

Coupling of CSF and sagittal sinus pressure in adult patients with pseudotumour cerebri.

OBJECTIVE: Pseudotumour cerebri syndrome (PTCS including idiopathic intracranial hypertension) is characterised by the symptoms and signs of raised cerebrospinal fluid pressure (CSFp) in the absence of ventricular dilatation or an intracranial mass lesion. Its aetiology is unknown in the majority of cases but there is much evidence for impaired CSF absorption. Traditionally, sagittal sinus pressure has been considered to be independent of CSF pressure in adults. However, the discovery of stenoses of intracranial venous sinuses and introduction of venous sinus stenting has highlighted the importance of the venous drainage in PTCS. In this study, we have explored the relationship between CSFp and SSp before and during a CSF infusion test and during CSF drainage. MATERIALS AND METHODS: Ten patients (9 females:1 male) with PTCS underwent infusion studies in parallel with direct retrograde cerebral venography. Both SSp and CSFp were recorded at a baseline and during CSFp elevation in a course of a CSF infusion test. The drainage of CSF after the CSF infusion was performed in 7 patients. In 5 cases, jugular venous pressure was also measured. RESULTS: CSFp and SSp including their amplitudes correlated significantly and strongly both at baseline (R = 0.96; p = 0.001) and during infusion (R = 0.92; p = 0.0026). During drainage, this correlation was maintained until SSp reached a stable value, whereas CSFp continued to decrease. CONCLUSIONS: In this series of ten patients with PTCS, CSFp and SSp were coupled, both at baseline and during infusion. The implications of such coupling for the calculation of CSF outflow resistance are discussed.

Idiopathic intracranial hypertension in childhood: pitfalls in diagnosis.

AIM: Idiopathic intracranial hypertension (IIH) is prone to misdiagnosis. Our aim was to identify the reasons for this in children in our region referred for suspected IIH. METHOD: We reviewed the records of all children referred with symptoms and/or signs consistent with raised intracranial pressure (ICP) and normal magnetic resonance imaging of the brain to our tertiary neurology unit over 4 years. IIH was confirmed after expert ophthalmology including ultrasound/tomography and advanced cerebrospinal fluid (CSF) pressure studies. RESULTS: Of 15 children (six males, nine females; median age 12y, range 3-15y), six (five females, one male) were confirmed to have IIH. All weighed above the 91st centile and were over 10 years old. Four of the six had raised ICP secondary to other causes. Four had been misdiagnosed locally with papilloedema, three had drusen, and one had 'crowded discs'. Two had raised CSF pressures on standard lumbar puncture, but 20-minute steady state and infusion studies were normal, with symptoms settling after therapy was withdrawn. INTERPRETATION: Misdiagnosis of IIH was frequent, but could be reduced by (1) expert ophthalmological fundoscopy, orbital ultrasound, and optical coherence tomography; (2) expert neuroradiology; and (3) assessment of steady state CSF pressure rather than standard opening pressure in centimetres of water.

Consensus recommendations for the assessment and management of idiopathic intracranial hypertension in children and young people.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is a potentially disabling condition. There is a lack of evidence and national guidance on how to diagnose and treat paediatric IIH, leading to variation in clinical practice. We conducted a national Delphi consensus via the Children's Headache Network to propose a best-practice diagnostic and therapeutic pathway. METHODS: The Delphi process was selected as the most appropriate methodology for examining current opinion among experts in the UK. 104 questions were considered by 66 healthcare professionals, addressing important aspects of IIH care: assessment, diagnosis, treatment, follow-up and surveillance. General paediatricians, paediatric neurologists, ophthalmologists, opticians, neuroradiologists and neurosurgeons with a clinical interest or experience in IIH, were invited to take part. RESULTS: The Delphi process consisted of three rounds comprising 104 questions (round 1, 67; round 2, 24; round 3 (ophthalmological), 13) and was completed between March 2019 and August 2021. There were 54 and 65 responders in the first and second rounds, respectively. The Delphi was endorsed by the Royal College of Ophthalmologists, which engaged 59 ophthalmologists for round 3. CONCLUSIONS: This UK-based Delphi consensus process reached agreement for the management of paediatric IIH and has been endorsed by the Children's Headache Network and more broadly, the British Paediatric Neurology Association. It provides a basis for a pragmatic clinical approach. The recommendations will help to improve clinical care while minimising under and over diagnosis.

CIAO1 loss of function causes a neuromuscular disorder with compromise of nucleocytoplasmic Fe-S enzymes.

Cytoplasmic and nuclear iron-sulfur (Fe-S) enzymes that are essential for genome maintenance and replication depend on the cytoplasmic Fe-S assembly (CIA) machinery for cluster acquisition. The core of the CIA machinery consists of a complex of CIAO1, MMS19 and FAM96B. The physiological consequences of loss of function in the components of the CIA pathway have thus far remained uncharacterized. Our study revealed that patients with biallelic loss of function in CIAO1 developed proximal and axial muscle weakness, fluctuating creatine kinase elevation, and respiratory insufficiency. In addition, they presented with CNS symptoms including learning difficulties and neurobehavioral comorbidities, along with iron deposition in deep brain nuclei, mild normocytic to macrocytic anemia, and gastrointestinal symptoms. Mutational analysis revealed reduced stability of the variants compared with WT CIAO1. Functional assays demonstrated failure of the variants identified in patients to recruit Fe-S recipient proteins, resulting in compromised activities of DNA helicases, polymerases, and repair enzymes that rely on the CIA complex to acquire their Fe-S cofactors. Lentivirus-mediated restoration of CIAO1 expression reversed all patient-derived cellular abnormalities. Our study identifies CIAO1 as a human disease gene and provides insights into the broader implications of the cytosolic Fe-S assembly pathway in human health and disease.

Loss of Function of the Cytoplasmic Fe-S Assembly Protein CIAO1 Causes a Neuromuscular Disorder with Compromise of Nucleocytoplasmic Fe-S Enzymes.

Cytoplasmic and nuclear iron-sulfur enzymes that are essential for genome maintenance and replication depend on the cytoplasmic iron-sulfur assembly (CIA) machinery for cluster acquisition. Here we report that patients with biallelic loss of function in CIAO1 , a key CIA component, develop proximal and axial muscle weakness, fluctuating creatine kinase elevation and respiratory insufficiency. In addition, they present with CNS symptoms including learning difficulties and neurobehavioral comorbidities, along with iron deposition in deep brain nuclei, macrocytic anemia and gastrointestinal symptoms. Mutational analysis and functional assays revealed reduced stability of the variants compared to wild-type CIAO1. Loss of CIAO1 impaired DNA helicases, polymerases and repair enzymes which rely on the CIA complex to acquire their Fe-S cofactors, with lentiviral restoration reversing all patient-derived cellular abnormalities. Our study identifies CIAO1 as a novel human disease gene and provides insights into the broader implications of the iron-sulfur assembly pathway in human health and disease.

Molecular and neurological features of MELAS syndrome in paediatric patients: A case series and review of the literature.

BACKGROUND: Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is one of the most well-known mitochondrial diseases, with most cases attributed to m.3243A>G. MELAS syndrome patients typically present in the first two decades of life with a broad, multi-systemic phenotype that predominantly features neurological manifestations--stroke-like episodes. However, marked phenotypic variability has been observed among paediatric patients, creating a clinical challenge and delaying diagnoses. METHODS: A literature review of paediatric MELAS syndrome patients and a retrospective analysis in a UK tertiary paediatric neurology centre were performed. RESULTS: Three children were included in this case series. All patients presented with seizures and had MRI changes not confined to a single vascular territory. Blood heteroplasmy varied considerably, and one patient required a muscle biopsy. Based on a literature review of 114 patients, the mean age of presentation is 8.1 years and seizures are the most prevalent manifestation of stroke-like episodes. Heteroplasmy is higher in a tissue other than blood in most cases. CONCLUSION: The threshold for investigating MELAS syndrome in children with suspicious neurological symptoms should be low. If blood m.3243A>G analysis is negative, yet clinical suspicion remains high, invasive testing or further interrogation of the mitochondrial genome should be considered.

Clinical features, investigations, and outcomes of pediatric limbic encephalitis: A multicenter study.

OBJECTIVES: To describe the clinical presentation, investigations, management, and disease course in pediatric autoimmune limbic encephalitis (LE). METHODS: In this retrospective observational study, from the UK Childhood Neuroinflammatory Disease network, we identified children from six tertiary centers with LE <18 years old between 2008 and 2021. Clinical and paraclinical data were retrieved from medical records. RESULTS: Twenty-five children fulfilling LE criteria were identified, with median age of 11 years (IQR 8, 14) and median follow-up of 24 months (IQR 18, 48). All children presented with seizures; 15/25 (60%) were admitted to intensive care. Neuroimaging demonstrated asymmetric mesial temporal changes in 8/25 (32%), and extra-limbic changes with claustrum involvement in 9/25 (38%). None were positive for LGI1/CASPR2 antibodies (Abs), 2/25 were positive for serum anti-NMDAR Abs, and 2/15 positive for anti-Hu Abs; one died from relapsing neuroblastoma. Two children had serum and CSF anti-GAD antibodies. Initial immune therapy included steroids in 23/25 (92%), intravenous immunoglobulin (IVIg) in 14/25 (56%), and plasma exchange in 7/25 (28%). The commonest second-line treatment was rituximab in 15/25 (60%). Median duration of hospital admission was 21 days (IQR 11, 30). At last follow-up, 13/25 (52%) had refractory seizures and 16/25 (64%) had memory impairment. Six children (24%) had modified Rankin Scale (mRS) scores ≥3. There was no significant difference in mRS, or long-term cognitive and epilepsy outcomes in those who received rituximab versus those who did not. INTERPRETATION: A diagnosis of autoimmune LE was associated with significant morbidity and adverse outcomes in this pediatric cohort.

The clinical presentation of mitochondrial diseases in children with progressive intellectual and neurological deterioration: a national, prospective, population-based study.

AIM: Our aim was to study the clinical presentation, mode of diagnosis, and epidemiology of mitochondrial disorders in children from the UK who have progressive intellectual and neurological deterioration (PIND). METHOD: Since April 1997, we have identified patients aged 16 years or younger with suspected PIND through the monthly notification card sent to all UK consultant paediatricians by the British Paediatric Surveillance Unit. Clinical details obtained from reporting paediatricians are classified by an Expert Group. RESULTS: By July 2008, 2493 cases of PIND had been reported, among which there were 112 children (69 males, 43 females) with mitochondrial diseases presenting between birth and 14 years 7 months (median 12mo), divided into 13 subgroups. In some instances, clinical features were characteristic of mitochondrial disease, but many children presented non-specifically with combinations of developmental delay, hypotonia, failure to thrive, and seizures; 16 children had multisystem disease at presentation. Mortality was high: 40 children had died. Blood and/or cerebrospinal fluid lactate measurements were abnormal in 87 children, and 47 of 78 brain magnetic resonance images showed increased basal ganglia signal. Definite diagnoses were usually made by muscle enzyme or genetic studies. INTERPRETATION: This is a unique population-based study of the mitochondrial disorders that cause childhood neurodegenerative disease. It provides detailed information about the clinical presentation and investigation of these complex cases.

Epilepsy and Electroencephalographic Abnormalities in SATB2-Associated Syndrome.

BACKGROUND: Seizures are an under-reported feature of the SATB2-associated syndrome phenotype. We describe the electroencephalographic findings and seizure semiology and treatment in a population of individuals with SATB2-associated syndrome. METHODS: We performed a retrospective review of 101 individuals with SATB2-associated syndrome who were reported to have had a previous electroencephalographic study to identify those who had at least one reported abnormal result. For completeness, a supplemental survey was distributed to the caregivers and input from the treating neurologist was obtained whenever possible. RESULTS: Forty-one subjects were identified as having at least one prior abnormal electroencephalography. Thirty-eight individuals (93%) had epileptiform discharges, 28 (74%) with central localization. Sleep stages were included as part of the electroencephalographies performed in 31 individuals (76%), and epileptiform activity was recorded during sleep in all instances (100%). Definite clinical seizures were diagnosed in 17 individuals (42%) with a mean age of onset of 3.2 years (four months to six years), and focal seizures were the most common type of seizure observed (42%). Six subjects with definite clinical seizures needed polytherapy (35%). Delayed myelination and/or abnormal white matter hyperintensities were seen on neuroimaging in 19 individuals (61%). CONCLUSIONS: Epileptiform abnormalities are commonly seen in individuals with SATB2-associated syndrome. A baseline electroencephalography that preferably includes sleep stages is recommended during the initial evaluation of all individuals with SATB2-associated syndrome, regardless of clinical suspicion of epilepsy.

Neuropathologic Characterization of Pontocerebellar Hypoplasia Type 6 Associated With Cardiomyopathy and Hydrops Fetalis and Severe Multisystem Respiratory Chain Deficiency due to Novel RARS2 Mutations.

Autosomal recessive mutations in the RARS2 gene encoding the mitochondrial arginyl-transfer RNA synthetase cause infantile-onset myoencephalopathy pontocerebellar hypoplasia type 6 (PCH6). We describe 2 sisters with novel compound heterozygous RARS2 mutations who presented perinatally with neurologic features typical of PCH6 but with additional features including cardiomyopathy, hydrops, and pulmonary hypoplasia and who died at 1 day and 14 days of age. Magnetic resonance imaging findings included marked cerebellar hypoplasia, gyral immaturity, punctate lesions in cerebral white matter, and unfused deep cerebral grey matter. Enzyme histochemistry of postmortem tissues revealed a near-global cytochrome c oxidase-deficiency; assessment of respiratory chain enzyme activities confirmed severe deficiencies involving complexes I, III, and IV. Molecular genetic studies revealed 2 RARS2 gene mutations: a c.1A>G, p.? variant predicted to abolish the initiator methionine, and a deep intronic c.613-3927C>T variant causing skipping of exons 6-8 in the mature RARS2 transcript. Neuropathologic investigation included low brain weights, small brainstem and cerebellum, deep cerebral white matter pathology, pontine nucleus neuron loss (in 1 sibling), and peripheral nerve pathology. Mitochondrial respiratory chain immunohistochemistry in brain tissues confirmed an absence of complexes I and IV immunoreactivity with sparing of mitochondrial numbers. These cases expand the clinical spectrum of RARS2 mutations, including antenatal features and widespread mitochondrial respiratory chain deficiencies in postmortem brain tissues.

Abnormal cerebrospinal fluid biochemistry in biotinidase deficiency causing diagnostic conundrum.

Biotinidase deficiency is a treatable cause of infantile epilepsy and the presentation can be nonspecific. The seizures are difficult to differentiate from other causes of epileptic encephalopathy, which generally have a poor prognosis. We report 2 infants who presented with seizures, and whose low cerebrospinal fluid glucose and high cerebrospinal lactate caused a diagnostic dilemma. Subsequent urine organic acids pointed to the correct diagnosis and avoided invasive investigation. The children had a good clinical outcome with resolution of their seizures on biotin treatment.

Successful treatment of two paediatric cases of anti-NMDA receptor encephalitis with cyclophosphamide: the need for early aggressive immunotherapy in tumour negative paediatric patients.

We describe the clinical course and treatment of three unrelated female patients ranging in age from 27 months to 14 years with anti-NMDA receptor encephalitis. The third case is reported as an addendum to the paper. None of the cases were paraneoplastic. All received initial immunotherapy consisting of steroids and IVIg, and two of them received 3 and 8 plasma exchanges respectively, without consistent or sustained clinical improvement. All three girls were then treated with monthly cycles of Cyclophosphamide. All had resolution of their movement disorder and a dramatic and sustained clinical improvement of their other symptoms in the domains of cognition, language and behaviour. The clinical improvement began after the first cycle in two and the second cycle in the third and continued with the subsequent cycles. None developed side-effects of treatment. In light of the recent review of the condition and our own clinical experience in the paediatric age group, we propose that second line immunotherapy should be considered early after failure of first line immunotherapy.