Treatment of Infantile Spasm Syndrome: Update from the Interdisciplinary Guideline Committee Coordinated by the German-Speaking Society of Neuropediatrics.

OBJECTIVES: The manuscript serves as an update on the current management practices for infantile spasm syndrome (ISS). It includes a detailed summary of the level of current evidence of different treatment options for ISS and gives recommendations for the treatment and care of patients with ISS. METHODS: A literature search was performed using the Cochrane and Medline Databases (2014 to July 2020). All studies were objectively rated using the Scottish Intercollegiate Guidelines Network. For recommendations, the evidence from these studies was combined with the evidence from studies used in the 2014 guideline. RECOMMENDATIONS: If ISS is suspected, electroencephalography (EEG) should be performed within a few days and, if confirmed, treatment should be initiated immediately. Response to first-line treatment should be evaluated clinically and electroencephalographically after 14 days. The preferred first-line treatment for ISS consists of either hormone-based monotherapy (AdrenoCorticoTropic Hormone [ACTH] or prednisolone) or a combination of hormone and vigabatrin. Children with tuberous sclerosis complex and those with contraindications against hormone treatment should be treated with vigabatrin. If first-line drugs are ineffective, second-line treatment options such as ketogenic dietary therapies, sulthiame, topiramate, valproate, zonisamide, or benzodiazepines should be considered. Children refractory to drug therapy should be evaluated early for epilepsy surgery, especially if focal brain lesions are present. Parents should be informed about the disease, the efficacy and adverse effects of the medication, and support options for the family. Regular follow-up controls are recommended.

Consensus statements on the information to deliver after a febrile seizure.

Febrile seizures (FS) are usually self-limiting and cause no morbidity. Nevertheless they represent very traumatic events for families. There is a need to identify key messages that reassure carers and help to prevent inappropriate, anxiety-driven behaviors associated with "fever phobia." No recommendations have been proposed to date regarding the content of such messages. Using a Delphi process, we have established a consensus regarding the information to be shared with families following a FS. Twenty physicians (child neurologists and pediatricians) from five European countries participated in a three-step Delphi process between May 2018 and October 2019. In the first step, each expert was asked to give 10 to 15 free statements about FS. In the second and third steps, statements were scored and selected according to the expert ranking of importance. A list of key messages for families has emerged from this process, which offer reassurance about FS based on epidemiology, underlying mechanisms, and the emergency management of FS should they recur. Interestingly, there was a high level of agreement between child neurologists and general pediatricians.Conclusion: We propose key messages to be communicated with families in the post-FS clinic setting. What is Known: • Febrile seizures (FS) are traumatic events for families. • No guidelines exist on what information to share with parents following a FS. What is New: • A Delphi process involving child neurologists and pediatricians provides consensual statement about information to deliver after a febrile seizure. • We propose key messages to be communicated with families in the post-FS clinic setting.

Complex care of individuals with multiple sulfatase deficiency: Clinical cases and consensus statement.

Multiple sulfatase deficiency (MSD) is an ultra-rare neurodegenerative disorder that results in defective sulfatase post-translational modification. Sulfatases in the body are activated by a unique protein, formylglycine-generating enzyme (FGE) that is encoded by SUMF1. When FGE is absent or insufficient, all 17 known human sulfatases are affected, including the enzymes associated with metachromatic leukodystrophy (MLD), several mucopolysaccharidoses (MPS II, IIIA, IIID, IVA, VI), chondrodysplasia punctata, and X-linked ichthyosis. As such, individuals demonstrate a complex and severe clinical phenotype that has not been fully characterized to date. In this report, we describe two individuals with distinct clinical presentations of MSD. Also, we detail a comprehensive systems-based approach to the management of individuals with MSD, from the initial diagnostic evaluation to unique multisystem issues and potential management options. As there have been no natural history studies to date, the recommendations within this report are based on published studies and consensus opinion and underscore the need for future research on evidence-based outcomes to improve management of children with MSD.

Genetic and phenotypic heterogeneity suggest therapeutic implications in SCN2A-related disorders.

Mutations in SCN2A, a gene encoding the voltage-gated sodium channel Nav1.2, have been associated with a spectrum of epilepsies and neurodevelopmental disorders. Here, we report the phenotypes of 71 patients and review 130 previously reported patients. We found that (i) encephalopathies with infantile/childhood onset epilepsies (≥3 months of age) occur almost as often as those with an early infantile onset (<3 months), and are thus more frequent than previously reported; (ii) distinct phenotypes can be seen within the late onset group, including myoclonic-atonic epilepsy (two patients), Lennox-Gastaut not emerging from West syndrome (two patients), and focal epilepsies with an electrical status epilepticus during slow sleep-like EEG pattern (six patients); and (iii) West syndrome constitutes a common phenotype with a major recurring mutation (p.Arg853Gln: two new and four previously reported children). Other known phenotypes include Ohtahara syndrome, epilepsy of infancy with migrating focal seizures, and intellectual disability or autism without epilepsy. To assess the response to antiepileptic therapy, we retrospectively reviewed the treatment regimen and the course of the epilepsy in 66 patients for which well-documented medical information was available. We find that the use of sodium channel blockers was often associated with clinically relevant seizure reduction or seizure freedom in children with early infantile epilepsies (<3 months), whereas other antiepileptic drugs were less effective. In contrast, sodium channel blockers were rarely effective in epilepsies with later onset (≥3 months) and sometimes induced seizure worsening. Regarding the genetic findings, truncating mutations were exclusively seen in patients with late onset epilepsies and lack of response to sodium channel blockers. Functional characterization of four selected missense mutations using whole cell patch-clamping in tsA201 cells-together with data from the literature-suggest that mutations associated with early infantile epilepsy result in increased sodium channel activity with gain-of-function, characterized by slowing of fast inactivation, acceleration of its recovery or increased persistent sodium current. Further, a good response to sodium channel blockers clinically was found to be associated with a relatively small gain-of-function. In contrast, mutations in patients with late-onset forms and an insufficient response to sodium channel blockers were associated with loss-of-function effects, including a depolarizing shift of voltage-dependent activation or a hyperpolarizing shift of channel availability (steady-state inactivation). Our clinical and experimental data suggest a correlation between age at disease onset, response to sodium channel blockers and the functional properties of mutations in children with SCN2A-related epilepsy.

Severe Hypertriglyceridemia in Glut1D on Ketogenic Diet.

High-fat ketogenic diets are the only treatment available for Glut1 deficiency (Glut1D). Here, we describe an 8-year-old girl with classical Glut1D responsive to a 3:1 ketogenic diet and ethosuximide. After 3 years on the diet a gradual increase of blood lipids was followed by rapid, severe asymptomatic hypertriglyceridemia (1,910 mg/dL). Serum lipid apheresis was required to determine liver, renal, and pancreatic function. A combination of medium chain triglyceride-oil and a reduction of the ketogenic diet to 1:1 ratio normalized triglyceride levels within days but triggered severe myoclonic seizures requiring comedication with sultiam. Severe hypertriglyceridemia in children with Glut1D on ketogenic diets may be underdiagnosed and harmful. In contrast to congenital hypertriglyceridemias, children with Glut1D may be treated effectively by dietary adjustments alone.

Mutations in the gene encoding the 3'-5' DNA exonuclease TREX1 cause Aicardi-Goutières syndrome at the AGS1 locus.

Aicardi-Goutières syndrome (AGS) presents as a severe neurological brain disease and is a genetic mimic of the sequelae of transplacentally acquired viral infection. Evidence exists for a perturbation of innate immunity as a primary pathogenic event in the disease phenotype. Here, we show that TREX1, encoding the major mammalian 3' --> 5' DNA exonuclease, is the AGS1 gene, and AGS-causing mutations result in abrogation of TREX1 enzyme activity. Similar loss of function in the Trex1(-/-) mouse leads to an inflammatory phenotype. Our findings suggest an unanticipated role for TREX1 in processing or clearing anomalous DNA structures, failure of which results in the triggering of an abnormal innate immune response.

Mutations in genes encoding ribonuclease H2 subunits cause Aicardi-Goutières syndrome and mimic congenital viral brain infection.

Aicardi-Goutières syndrome (AGS) is an autosomal recessive neurological disorder, the clinical and immunological features of which parallel those of congenital viral infection. Here we define the composition of the human ribonuclease H2 enzyme complex and show that AGS can result from mutations in the genes encoding any one of its three subunits. Our findings demonstrate a role for ribonuclease H in human neurological disease and suggest an unanticipated relationship between ribonuclease H2 and the antiviral immune response that warrants further investigation.

Exome sequencing identifies a de novo SCN2A mutation in a patient with intractable seizures, severe intellectual disability, optic atrophy, muscular hypotonia, and brain abnormalities.

Epilepsy is a phenotypically and genetically highly heterogeneous disorder with >200 genes linked to inherited forms of the disease. To identify the underlying genetic cause in a patient with intractable seizures, optic atrophy, severe intellectual disability (ID), brain abnormalities, and muscular hypotonia, we performed exome sequencing in a 5-year-old girl and her unaffected parents. In the patient, we detected a novel, de novo missense mutation in the SCN2A (c.5645G>T; p.R1882L) gene encoding the αII -subunit of the voltage-gated sodium channel Nav 1.2. A literature review revealed 33 different SCN2A mutations in 14 families with benign forms of epilepsy and in 21 cases with severe phenotypes. Although almost all benign mutations were inherited, the majority of severe mutations occurred de novo. Of interest, de novo SCN2A mutations have also been reported in five patients without seizures but with ID (n = 3) and/or autism (n = 3). In the present study, we successfully used exome sequencing to detect a de novo mutation in a genetically heterogeneous disorder with epilepsy and ID. Using this approach, we expand the phenotypic spectrum of SCN2A mutations. Our own and literature data indicate that SCN2A-linked severe phenotypes are more likely to be caused by de novo mutations. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.

Diagnosis and treatment of growth hormone deficiency in children on the ketogenic diet: A case series.

The ketogenic diet (KD) can have a negative impact on the linear growth and body composition of children. The aims of this study were to review two centers' experience with children who developed height deceleration on the KD and determine if the height deceleration was secondary to growth hormone deficiency (GHD), and if growth hormone therapy (GHT) would be effective and safe (not altering ketosis or seizure frequency). Retrospective chart reviews were performed on patients with KD referred to Endocrinology between 2013 and 2018. Seventeen children were identified. Data reviewed included: demographics, growth velocity, KD ratio, protein/calorie intake, lab results, GH dosage, Tanner stage, and seizure frequency, and endocrine recommendations. Descriptive statistics were performed. Of the 17 children referred to the Endocrine Division, seven children were growth hormone deficient and began GHT. Data were provided for six patients (2 males, 4 females; age 2-7 years at the start of KD) on the KD for >6 years and on GHT for >4 years. Growth for all patients stabilized or increased. IGF-1 z-scores normalized. GHT did not affect seizure frequency or ketosis. GHT in those with GHD can be an appropriate option allowing better growth while still maintaining ketogenic therapy and seizure control. PLAIN LANGUAGE SUMMARY: The KD can be an effective treatment for difficult-to-control epilepsy and some disorders of carbohydrate metabolism. The KD can adversely affect the linear growth (height) of children. This case series reviewed six patients who had slow linear growth. It was found that all six children had growth hormone deficiency, grew better with growth hormone treatments, and that their seizures and ketone levels were not affected.

Distinct neurodevelopmental and epileptic phenotypes associated with gain- and loss-of-function GABRB2 variants.

BACKGROUND: Variants in GABRB2, encoding the ß2 subunit of the γ-aminobutyric acid type A (GABAA) receptor, can result in a diverse range of conditions, ranging from febrile seizures to severe developmental and epileptic encephalopathies. However, the mechanisms underlying the risk of developing milder vs more severe forms of disorder remain unclear. In this study, we conducted a comprehensive genotype-phenotype correlation analysis in a cohort of individuals with GABRB2 variants. METHODS: Genetic and electroclinical data of 42 individuals harbouring 26 different GABRB2 variants were collected and accompanied by electrophysiological analysis of the effects of the variants on receptor function. FINDINGS: Electrophysiological assessments of α1ß2γ2 receptors revealed that 25/26 variants caused dysfunction to core receptor properties such as GABA sensitivity. Of these, 17 resulted in gain-of-function (GOF) while eight yielded loss-of-function traits (LOF). Genotype-phenotype correlation analysis revealed that individuals harbouring GOF variants suffered from severe developmental delay/intellectual disability (DD/ID, 74%), movement disorders such as dystonia or dyskinesia (59%), microcephaly (50%) and high risk of early mortality (26%). Conversely, LOF variants were associated with milder disease manifestations. Individuals with these variants typically exhibited fever-triggered seizures (92%), milder degrees of DD/ID (85%), and maintained ambulatory function (85%). Notably, severe movement disorders or microcephaly were not reported in individuals with loss-of-function variants. INTERPRETATION: The data reveals that genetic variants in GABRB2 can lead to both gain and loss-of-function, and this divergence is correlated with distinct disease manifestations. Utilising this information, we constructed a diagnostic flowchart that aids in predicting the pathogenicity of recently identified variants by considering clinical phenotypes. FUNDING: This work was funded by the Australian National Health & Medical Research Council, the Novo Nordisk Foundation and The Lundbeck Foundation.

Mutations in SLC20A2 are a major cause of familial idiopathic basal ganglia calcification.

Familial idiopathic basal ganglia calcification (IBGC) or Fahr's disease is a rare neurodegenerative disorder characterized by calcium deposits in the basal ganglia and other brain regions, which is associated with neuropsychiatric and motor symptoms. Familial IBGC is genetically heterogeneous and typically transmitted in an autosomal dominant fashion. We performed a mutational analysis of SLC20A2, the first gene found to cause IBGC, to assess its genetic contribution to familial IBGC. We recruited 218 subjects from 29 IBGC-affected families of varied ancestry and collected medical history, neurological exam, and head CT scans to characterize each patient's disease status. We screened our patient cohort for mutations in SLC20A2. Twelve novel (nonsense, deletions, missense, and splice site) potentially pathogenic variants, one synonymous variant, and one previously reported mutation were identified in 13 families. Variants predicted to be deleterious cosegregated with disease in five families. Three families showed nonsegregation with clinical disease of such variants, but retrospective review of clinical and neuroimaging data strongly suggested previous misclassification. Overall, mutations in SLC20A2 account for as many as 41% of our familial IBGC cases. Our screen in a large series expands the catalog of SLC20A2 mutations identified to date and demonstrates that mutations in SLC20A2 are a major cause of familial IBGC. Non-perfect segregation patterns of predicted deleterious variants highlight the challenges of phenotypic assessment in this condition with highly variable clinical presentation.

Absence of SLC2A1 mutations does not exclude Glut1 deficiency syndrome.

Increasingly, the absence of SLC2A1 mutations causes pediatricians to abandon the diagnosis of Glut1 deficiency. For several reasons this is not justified. Potential disease mechanisms in SLC2A1-negative Glut1 deficiency are discussed.

Timing of Ketogenic Dietary Therapy (KDT) Introduction and Its Impact on Cognitive Profiles in Children with Glut1-DS-A Preliminary Study.

The aim of this research was to characterize cognitive abilities in patients with Glut1-Deficiency syndrome (Glut1DS) following ketogenic diet therapy (KDT). METHODS: The cognitive profiles of eight children were assessed using the Wechsler Intelligence Scale (WISC-IV). The effect of ketogenic diet therapy (KDT) on individual subareas of intelligence was analyzed considering the potential influence of speech motor impairments. RESULTS: Patients with Glut1DS showed a wide range of cognitive performance levels. Some participants showed statistically and clinically significant discrepancies between individual subdomains of intelligence. Both variables, KDT initiation as well as duration, had a positive effect on the overall IQ score. Significant correlations were partially found between the time of KDT initiation and the level of IQ scores, depending on the presence of expressive language test demands of the respective subtests of the WISC-IV. Accordingly, the participants benefited les in the linguistic cognitive domain. The discrepancies in cognitive performance profiles of patients with Glut1DS can be attributed to the possibility of a negative distortion of the results due to the influence of speech motor impairments. CONCLUSIONS: The individual access skills of test persons should be more strongly considered in test procedures for the assessment of intelligence to reduce the negative influence of motor deficits on test performance. Specific characterization and systematization of the speech disorder are indispensable for determining the severity of speech motor impairment in Glut1DS. Therefore, a stronger focus on dysarthria during diagnosis and therapy is necessary.

Unusual sensitivity to steroid treatment in intractable childhood epilepsy suggests GLUT1 deficiency syndrome.

Glucose transporter 1 (GLUT1) deficiency syndrome (DS) results from impaired glucose transport into brain. We describe the case of an 8-year-old girl with early-onset myoclonic epilepsy unresponsive to eight anticonvulsants. Oral steroid treatment achieved dramatic seizure control at the expense of Cushing syndrome and progressive fatty liver disease. Steroid withdrawal resulted in severe seizure exacerbation but was eventually enforced for lumbar puncture. GLUT1DS was diagnosed by hypoglycorrhachia and a heterozygous SLC2A1 mutation (Arg400His). A ketogenic diet resulted in effective seizure control. Steroids in GLUT1DS are unusual and unreported. Here a remarkable immediate and effective seizure control and a dose-independent unsuccessful steroid withdrawal indicated a potential GLUT1 sensitivity to steroids. We review the literature on GLUT1/steroid interactions and propose that unusual steroid sensitivity in intractable childhood epilepsy might be indicative for GLUT1DS.

Refractory absence epilepsy associated with GLUT-1 deficiency syndrome.

GLUT-1 deficiency syndrome (GLUT-1 DS) is a disorder of cerebral glucose transport associated with early infantile epilepsy and microcephaly. We report two boys who presented with refractory absence epilepsy associated with hypoglycorrhachia, both of whom have genetically confirmed GLUT-1 DS. We propose that these children serve to expand the phenotype of GLUT-1 DS and suggest that this condition should be considered as a cause of refractory absence seizures in childhood.

Glucose transporter-1 deficiency syndrome: the expanding clinical and genetic spectrum of a treatable disorder.

Glucose transporter-1 deficiency syndrome is caused by mutations in the SLC2A1 gene in the majority of patients and results in impaired glucose transport into the brain. From 2004-2008, 132 requests for mutational analysis of the SLC2A1 gene were studied by automated Sanger sequencing and multiplex ligation-dependent probe amplification. Mutations in the SLC2A1 gene were detected in 54 patients (41%) and subsequently in three clinically affected family members. In these 57 patients we identified 49 different mutations, including six multiple exon deletions, six known mutations and 37 novel mutations (13 missense, five nonsense, 13 frame shift, four splice site and two translation initiation mutations). Clinical data were retrospectively collected from referring physicians by means of a questionnaire. Three different phenotypes were recognized: (i) the classical phenotype (84%), subdivided into early-onset (<2 years) (65%) and late-onset (18%); (ii) a non-classical phenotype, with mental retardation and movement disorder, without epilepsy (15%); and (iii) one adult case of glucose transporter-1 deficiency syndrome with minimal symptoms. Recognizing glucose transporter-1 deficiency syndrome is important, since a ketogenic diet was effective in most of the patients with epilepsy (86%) and also reduced movement disorders in 48% of the patients with a classical phenotype and 71% of the patients with a non-classical phenotype. The average delay in diagnosing classical glucose transporter-1 deficiency syndrome was 6.6 years (range 1 month-16 years). Cerebrospinal fluid glucose was below 2.5 mmol/l (range 0.9-2.4 mmol/l) in all patients and cerebrospinal fluid : blood glucose ratio was below 0.50 in all but one patient (range 0.19-0.52). Cerebrospinal fluid lactate was low to normal in all patients. Our relatively large series of 57 patients with glucose transporter-1 deficiency syndrome allowed us to identify correlations between genotype, phenotype and biochemical data. Type of mutation was related to the severity of mental retardation and the presence of complex movement disorders. Cerebrospinal fluid : blood glucose ratio was related to type of mutation and phenotype. In conclusion, a substantial number of the patients with glucose transporter-1 deficiency syndrome do not have epilepsy. Our study demonstrates that a lumbar puncture provides the diagnostic clue to glucose transporter-1 deficiency syndrome and can thereby dramatically reduce diagnostic delay to allow early start of the ketogenic diet.

Video/EEG recording of myoclonic absences in GLUT1 deficiency syndrome with a hot-spot R126C mutation in the SLC2A1 gene.

Glucose transporter type 1 deficiency syndrome (GLUT1DS) is an inborn error of brain energy metabolism characterized by impaired glucose transport into the brain. A classic phenotype comprising epilepsy, mental retardation, an often paroxysmal disorder, and several subtypes has been described. Although typical absences are frequent in GLUT1DS, myoclonic absence seizures are rarely reported. Here we describe a novel Turkish patient with a hot-spot mutation (R126C) in the SLC2A1 gene who presented with unusual myoclonic absence epilepsy and paroxysmal shivering. The case is discussed in view of eight other cases carrying the R126C mutation.

Glucose transporter type 1 deficiency syndrome with carbohydrate-responsive symptoms but without epilepsy.

Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is caused by a defect in glucose transport across the blood-brain barrier. The main symptoms are epilepsy, developmental delay, movement disorders, and deceleration of head circumference. A ketogenic diet has been shown to be effective in controlling epilepsy in GLUT1-DS. We report a female child (3 y 4 mo) who presented with delayed psychomotor development and frequent episodes of staggering, impaired vigilance, and vomiting that resolved promptly after food intake. Electroencephalography was normal. The cerebrospinal fluid-blood glucose ratio was 0.42 (normal ≥ 0.45). GLUT1-DS was confirmed by molecular genetic testing, which showed a novel de novo heterozygous mutation in the SLC2A1 gene (c.497_499delTCG, p.VAL166del). Before starting a ketogenic diet, the child's cognitive development was tested using the Snijders-Oomen Non-Verbal Intelligence Test, which revealed a heterogeneous intelligence profile with deficits in her visuomotor skills and spatial awareness. Her motor development was delayed. Three months after introducing a ketogenic diet, she showed marked improvement in speech and motor development, as tested by the Movement Assessment Battery for Children (manual dexterity 16th centile, ball skills 1st centile, static and dynamic balance 5th centile). This case demonstrates that GLUT1-DS should be investigated in individuals with unexplained developmental delay. Epilepsy is not a mandatory symptom. The ketogenic diet is also beneficial for non-epileptic symptoms in GLUT1-DS.

Glut1 Deficiency Syndrome (Glut1DS): State of the art in 2020 and recommendations of the international Glut1DS study group.

Glut1 deficiency syndrome (Glut1DS) is a brain energy failure syndrome caused by impaired glucose transport across brain tissue barriers. Glucose diffusion across tissue barriers is facilitated by a family of proteins including glucose transporter type 1 (Glut1). Patients are treated effectively with ketogenic diet therapies (KDT) that provide a supplemental fuel, namely ketone bodies, for brain energy metabolism. The increasing complexity of Glut1DS, since its original description in 1991, now demands an international consensus statement regarding diagnosis and treatment. International experts (n = 23) developed a consensus statement utilizing their collective professional experience, responses to a standardized questionnaire, and serial discussions of wide-ranging issues related to Glut1DS. Key clinical features signaling the onset of Glut1DS are eye-head movement abnormalities, seizures, neurodevelopmental impairment, deceleration of head growth, and movement disorders. Diagnosis is confirmed by the presence of these clinical signs, hypoglycorrhachia documented by lumbar puncture, and genetic analysis showing pathogenic SLC2A1 variants. KDT represent standard choices with Glut1DS-specific recommendations regarding duration, composition, and management. Ongoing research has identified future interventions to restore Glut1 protein content and function. Clinical manifestations are influenced by patient age, genetic complexity, and novel therapeutic interventions. All clinical phenotypes will benefit from a better understanding of Glut1DS natural history throughout the life cycle and from improved guidelines facilitating early diagnosis and prompt treatment. Often, the presenting seizures are treated initially with antiseizure drugs before the cause of the epilepsy is ascertained and appropriate KDT are initiated. Initial drug treatment fails to treat the underlying metabolic disturbance during early brain development, contributing to the long-term disease burden. Impaired development of the brain microvasculature is one such complication of delayed Glut1DS treatment in the postnatal period. This international consensus statement should facilitate prompt diagnosis and guide best standard of care for Glut1DS throughout the life cycle.