Defining the phenotype of FHF1 developmental and epileptic encephalopathy

Fibroblast growth-factor homologous factor (FHF1) gene variants have recently been associated with developmental and epileptic encephalopathy (DEE). FHF1 encodes a cytosolic protein that modulates neuronal sodium channel gating. We aim to refine the electroclinical phenotypic spectrum of patients with pathogenic FHF1 variants. We retrospectively collected clinical, genetic, neurophysiologic, and neuroimaging data of 17 patients with FHF1-DEE. Sixteen patients had recurrent heterozygous FHF1 missense variants: 14 had the recurrent p.Arg114His variant and two had a novel likely pathogenic variant p.Gly112Ser. The p.Arg114His variant is associated with an earlier onset and more severe phenotype. One patient carried a chromosomal microduplication involving FHF1. Twelve patients carried a de novo variant, five (29.5%) inherited from parents with gonadic or somatic mosaicism. Seizure onset was between 1 day and 41 months; in 76.5% it was within 30 days. Tonic seizures were the most frequent seizure type. Twelve patients (70.6%) had drug-resistant epilepsy, 14 (82.3%) intellectual disability, and 11 (64.7%) behavioral disturbances. Brain magnetic resonance imaging (MRI) showed mild cerebral and/or cerebellar atrophy in nine patients (52.9%). Overall, our findings expand and refine the clinical, EEG, and imaging phenotype of patients with FHF1-DEE, which is characterized by early onset epilepsy with tonic seizures, associated with moderate to severe ID and psychiatric features.     

Targeted gene panel sequencing in early infantile onset developmental and epileptic encephalopathy

BackgroundEarly-onset developmental and epileptic encephalopathy (DEE) is characterized by repeated seizures beginning within 3 months of birth and severe interictal epileptiform discharge, including burst suppression. This study assessed the utility of targeted gene panel sequencing in the genetic diagnosis of this disease.Materials and methodsTargeted gene panel sequencing was performed in 150 early infantile-onset DEE patients (≤3 months of age), and we extensively reviewed their clinical characteristics, including therapeutic efficacy, according to genotype.ResultsOf the early infantile-onset DEE patients, 70 were neonatal-onset DEE and the other 80 patients began experiencing seizures from 1 to 3 months after birth. There were 11 different pathogenic or likely pathogenic variants among 34.7% (52/150) of patients with early infantile-onset DEE, in whom KCNQ2, STXBP1, CDKL5, and SCN1A were the major pathogenic variants. Among the neonatal-onset DEE patients, pathological genes were identified in 42.9% (30/70), indicating a significantly higher diagnostic yield than in 27.5% (22/80) of patients who experienced seizure onset 1 to 3 months after birth (p = 0.048). Among the neonatal-onset DEE group, variants in KCNQ2, STXBP1, and CDKL5 were detected at high frequencies, accounting for 66.7% (20/30) of the pathogenic or likely pathogenic variants found in this study.ConclusionTargeted gene panel sequencing demonstrated a high yield of pathogenic variants in the diagnosis of early-onset epileptic encephalopathy, especially in those with neonatal-onset DEE. Early diagnosis of early-onset epileptic encephalopathy may improve the prognosis of patients by earlier selection of appropriate treatment based on pathogenic variant.     

Neonatal developmental and epileptic encephalopathy with movement disorders and arthrogryposis: A case report with a novel missense variant of SCN1A

Variants of SCN1A represent the archetypal channelopathy associated with several epilepsy syndromes. The clinical phenotypes have recently expanded from Dravet syndrome.Case reportWe present a female patient with the de novo SCN1A missense variant, c.5340G > A (p. Met1780Ile). The patient had various clinical features with neonatal onset SCN1A epileptic encephalopathy, arthrogryposis multiplex congenita, thoracic hypoplasia, thoracic scoliosis, and hyperekplexia.ConclusionOur findings are compatible with neonatal developmental and epileptic encephalopathy with movement disorders and arthrogryposis; the most severe phenotype probably caused by gain-of-function variant of SCN1A. The efficacy of sodium channel blocker was also discussed. Further exploration of the phenotype–genotype relationship of SCN1A variants may lead to better pharmacological treatments and family guidance.     

Biallelic SZT2 variants in a child with developmental and epileptic encephalopathy

Developmental and epileptic encephalopathy is a group of conditions characterized by the co‐occurrence of epilepsy and intellectual disability, in which there is additional developmental impairment independent of epileptic activity. Biallelic variants of SZT2, a known seizure threshold regulator gene, have been linked to a wide spectrum of clinical features, ranging from severe intellectual disability with refractory seizures to mild intellectual disability without seizures. Here, we describe a child with developmental and epileptic encephalopathy whose genetic testing led to the identification of novel biallelic variants of SZT2, a paternally inherited c.2798C>T, p.(Ser933Phe) variant and a maternally inherited c.4549C>T, p.(Arg1517Trp) variant. Our patient showed common clinical and radiographic features among patients with SZT2‐related encephalopathy. However, neonatal‐onset seizures and suppression‐burst EEG activity, not previously associated with SZT2‐related encephalopathy, were observed in this case. Although the seizures were controlled with carbamazepine, the developmental consequences remained profound, suggesting that the developmental impairments might be attributed to a direct effect of the SZT2 variants rather than the epileptic activity. We propose that SZT2 variants should be regarded among those that are believed to cause neonatal‐onset developmental and epileptic encephalopathy with a suppression‐burst pattern on EEG.     

FBXO28 causes developmental and epileptic encephalopathy with profound intellectual disability

Chromosome 1q41‐q42 deletion syndrome is a rare cause of intellectual disability, seizures, dysmorphology, and multiple anomalies. Two genes in the 1q41‐q42 microdeletion, WDR26 and FBXO28, have been implicated in monogenic disease. Patients with WDR26 encephalopathy overlap clinically with those with 1q41‐q42 deletion syndrome, whereas only one patient with FBXO28 encephalopathy has been described. Seizures are a prominent feature of 1q41‐q42 deletion syndrome; therefore, we hypothesized that pathogenic FBXO28 variants cause developmental and epileptic encephalopathies (DEEs). We describe nine new patients with FBXO28 pathogenic variants (four missense, including one recurrent, three nonsense, and one frameshift) and analyze all 10 known cases to delineate the phenotypic spectrum. All patients had epilepsy and 9 of 10 had DEE, including infantile spasms (3) and a progressive myoclonic epilepsy (1). Median age at seizure onset was 22.5 months (range 8 months to 5 years). Nine of 10 patients had intellectual disability, which was profound in six of nine and severe in three of nine. Movement disorders occurred in eight of 10 patients, six of 10 had hypotonia, four of 10 had acquired microcephaly, and five of 10 had dysmorphic features, albeit different to those typically seen in 1q41‐q42 deletion syndrome and WDR26 encephalopathy. We distinguish FBXO28 encephalopathy from both of these disorders with more severe intellectual impairment, drug‐resistant epilepsy, and hyperkinetic movement disorders.     

胼胝体全段一期切开治疗癫疒间性脑病

目的探索胼胝体全段一期切开的安全性,观察该术式治疗癫疒间性脑病的有效性。方法回顾性分析我科手术治疗的37例癫疒间性脑病的临床资料。经临床症状学、神经电生理学、神经影像和神经心理学综合评估后,于全麻下额部切口、经前纵裂入路显微镜下一期切开胼胝体全段。依Engel分级标准评判手术效果。结果随访18～34个月,Engel-Ⅰ级3例,Engel-Ⅱ级25例,Engel-Ⅲ级7例,Engel-Ⅳ级2例,手术总有效率达75.7%。跌倒发作、强直发作、痉挛发作和强直-阵挛发作的有效率分别为86.2%、77.5%、61.6%和40.8%。14例患者出现不同程度的手术后并发症,缄默11例、轻偏瘫7例、颅内感染1例。其中13例患者分别在出院时和出院后1月内痊愈,1例患者仍遗留轻偏瘫。结论胼胝体全段一期切开安全、微创,无新发并发症;它能有效减少癫疒间性脑病的癫疒间发作频率、减轻发作程度。     

Neurochemistry evaluated by MR spectroscopy in a patient with SPTAN1-related developmental and epileptic encephalopathy

BackgroundMutation of the SPTAN1 gene, which encodes α-fodrin (non-erythrocyte α-II spectrin), is one of the causes of developmental and epileptic encephalopathies (DEEs). SPTAN1-related DEE is radiologically characterized by cerebral atrophy, especially due to white matter volume reduction, hypomyelination, pontocerebellar hypoplasia, and a thin corpus callosum, however, no neurochemical analysis has been reported.Case reportA Japanese infant female presented with severe psychomotor delay, tonic spasms, and visual impairment. Whole-exome sequencing revealed a de novo variant of the SPTAN1 gene, leading to a diagnosis of SPTAN1-related DEE. MR spectroscopy at ages 5 months, 11 months, and 1 year and 4 months revealed decreased N-acetylaspartate and choline-containing compounds, and increased glutamate or glutamine.ConclusionThe decreased concentrations of N-acetylaspartate and choline-containing compounds may have resulted from neuroaxonal network dysfunction and hypomyelination, respectively. The increased glutamate or glutamine may have reflected a disrupted glutamate-glutamine cycle caused by dysfunction of exocytosis, in which α-fodrin plays an important role. MR spectroscopy revealed neurochemical derangement in SPTAN1-related DEE, which may be a possible pathomechanism and will be useful for its diagnosis.     

Neonatal tremor episodes and hyperekplexia‐like presentation at onset in a child with SCN8A developmental and epileptic encephalopathy

SCN8A encephalopathy is a newly defined epileptic encephalopathy caused by de novo mutations of the SCN8A gene. We report herein a four‐year‐old boy presenting with severe non‐epileptic abnormal movements, of possibly antenatal onset, progressively associated with pharmacoresistant epilepsy and regression, associated with a de novo heterozygous missense mutation of SCN8A. This case shows that paroxysmal non‐epileptic episodes of severe tremor and hyperekplexia‐like startles and a striking vegetative component can be the first early symptoms of severe SCN8A developmental and epileptic encephalopathy. Clinicians should be aware of these symptoms in order to avoid misdiagnosis and ensure early appropriate therapeutic management. [Published with video sequences on www.epilepticdisorders.com ].     

Developmental and epileptic encephalopathies: recognition and approaches to care

The term “developmental and epileptic encephalopathy” (DEE) refers to when cognitive functions are influenced by both seizure and interictal epileptiform activity and the neurobiological process behind the epilepsy. Many DEEs are related to gene variants and the onset is typically during early childhood. In this setting, neurocognition, whilst not improved by seizure control, may benefit from some precision therapies. In patients with non‐progressive diseases with cognitive impairment and co‐existing epilepsy, in whom the epileptiform activity does not affect or has minimal effect on function, the term “developmental encephalopathy” (DE) can be used. In contrast, for those patients with direct impact on cognition due to epileptic or epileptiform activity, the term “epileptic encephalopathy” (EE) is preferred, as most can revert to their normal or near normal baseline cognitive state with appropriate intervention. These children need aggressive treatment. Clinicians must tailor care towards individual needs and realistic expectations for each affected person; those with DE are unlikely to gain from aggressive antiseizure medication whilst those with EE will gain. Patients with DEE might benefit from a precision medicine approach in order to reduce the overall burden of epilepsy.     

Measurable outcomes for pediatric epileptic encephalopathy: a single‐center experience with corticosteroid therapy

Objective: Corticosteroids are commonly used to treat refractory epilepsy in children, but the heterogeneity of the population and lack of standardized outcome measures have limited understanding of their effectiveness. We conducted a single‐center study of corticosteroids for epileptic encephalopathy to (a) identify domains for measurement and estimate potential effect sizes, (b) characterize heterogeneity, and (c) identify outcomes that may need better tools for measurement. Methods: In this retrospective single‐center cohort study, children with epileptic encephalopathy (excluding infantile spasms) were treated with a standardized course of oral dexamethasone or IV methylprednisolone. Long‐term video electroencephalography (EEG) was assessed via novel ordinal scales for five features: seizure semiology/burden, epileptiform activity, slowing, organization, and sleep architecture. We abstracted parental assessment of functional domains (i.e., cognition) from the medical records. Pre‐treatment and post‐treatment EEG features, functional domains, and treatment regimens were compared. Results: Thirty‐five children with refractory epilepsy were included. Overall, 16/35 (46%) of individuals had a >50% reduction in seizure frequency from the pre‐treatment EEG to the initial post‐treatment EEG. In particular, tonic seizures (in a subset of 23 children) were reduced (24‐hour tonic seizure count pre‐treatment was 8 [4‐13] and 3 [1‐5] post‐treatment EEG#1, p=0.04). For follow‐up post‐treatment EEGs, there was: (1) better formation of sleep spindles (37% normal pre‐treatment to 63% normal post‐treatment; p=0.04); and (2) improvement in parental reported cognition (in 43%). Improved cognition was the only outcome that differed between the dexamethasone and methylprednisolone treated groups (58% for dexamethasone [n=11/19] vs. 25% for methylprednisolone [n=4/16]; p=0.03). Significance: Large studies should be powered to detect reductions in seizures (particularly tonic as we identified a 2.6‐fold reduction), improved EEG organization, and improved sleep architecture (21 percentage points). Cognitive improvements following steroid treatment, reported by parents, should be quantified and fully characterized in future work.     

ATP1A3-related early childhood onset developmental and epileptic encephalopathy responding to corpus callosotomy: A case report

BackgroundVarious ATP1A3 variant-related diseases have been reported, including alternating hemiplegia of childhood; rapid-onset dystonia–parkinsonism; and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss syndrome. Moreover, a few cases of developmental and epileptic encephalopathy (DEE) with none of these symptoms have been reported. Here, we present a case of DEE with early childhood onset caused by an ATP1A3 variant that was effectively treated using corpus callosotomy (CC).Case presentationAt the age of 3 years, the patient developed epileptic spasms, complicated by generalized and focal aware tonic seizures. Based on the seizure type and electroencephalographic findings showing a generalized spike and waves as well as interictal left frontal-dominant spikes, combined generalized and focal epilepsy was diagnosed. Whole-exome sequencing revealed a de novo missense variant in ATP1A3 (c.2888G > A, p.Gly963Asp), which was classified as likely pathogenic. At the age of 5 years, CC for generalized tonic seizures resulted in seizure-freedom using two anti-seizure medications. Subsequently, the patient achieved better verbal development.Discussion and conclusionEarly childhood onset DEE has not been reported in patients with ATP1A3 variants. Moreover, CC was extremely effective in our case. Although more research is needed to determine the etiology of epilepsy caused by the ATP1A3 variant, the clinical course of DEE caused by the ATP1A3 variant is diverse and its prognosis may be improved in early childhood onset cases using aggressive control of epilepsy, such as CC.     

Pointed rhythmic theta waves: a unique EEG pattern in KCNQ2‐related neonatal epileptic encephalopathy

We report the case of an infant with KCNQ2‐related neonatal epileptic encephalopathy presenting with intractable seizures beginning on the second day of life, which were resistant to multiple antiepileptic drugs. Continuous EEG recordings starting on the sixth day of life demonstrated a unique pattern of inter‐and postictal focal rhythmic pointed theta waves of lambdoid morphology in the immediate postictal period, localizing to the side of the antecedent seizure. Interictal EEG exhibited discontinuous background, including patterns of burst suppression and multifocal discharges, predominantly in the centrotemporal regions, which were aggravated during sleep. MRI demonstrated T1 signal abnormalities in the basal ganglia, bilaterally. Genetic testing revealed a de novo missense mutation in KCNQ2 at position c.545 T>G, encoding a previously unreported substitution (p.Val182Gly). Seizure control was achieved immediately after starting a lidocaine infusion at age 4 weeks. The patient remained largely seizure‐free following add‐on oral carbamazepine for maintenance therapy and weaning off lidocaine. This is the first report of a patient with KCNQ2‐related neonatal epileptic encephalopathy and therapy‐refractory seizures aborted by lidocaine, demonstrating a unique EEG pattern of inter‐ and postictal focal rhythmic pointed theta waves. Whether this pattern could be an early EEG marker for this disorder remains to be confirmed. [Published with video sequences on www.epilepticdisorders.com ]     

Infantile epileptic encephalopathy with a hyperkinetic movement disorder and hand stereotypies associated with a novel SCN1A mutation

We report a female patient who presented with intractable epileptic seizures, profound developmental delay since early infancy, and hyperkinetic movements with hand stereotypies. The patient initially developed focal seizures with multiple foci at 3 months of age. Thereafter, the seizures evolved to frequent episodes of hyperthermia‐induced status epilepticus. A novel de novo SCN1A mutation was identified by whole‐exome sequence analysis. This case demonstrates that SCN1A mutations may cause movement disorders as an atypical phenotype and the case history of this patient may expand our understanding of the clinical spectrum of SCN1A‐associated epileptic encephalopathy. [Published with video sequences]     

Efficacy of ketogenic diet in severe refractory status epilepticus initiating fever induced refractory epileptic encephalopathy in school age children (FIRES)

Purpose: Fever induced refractory epileptic encephalopathy in school age children (FIRES) is a devastating condition initiated by prolonged perisylvian refractory status epilepticus (SE) triggered by fever of unknown cause. SE may last more than 1 month, and this condition may evolve into pharmacoresistant epilepsy associated with severe cognitive impairment. We aimed to report the effect of ketogenic diet (KD) in this condition. Methods: Over the last 12 years we collected data of nine patients with FIRES who received a 4:1 ratio of fat to combined protein and carbohydrate KD. They presented with SE refractory to conventional antiepileptic treatment. Results: In seven patients, KD was efficacious within 2–4 days (mean 2 days) following the onset of ketonuria and 4–6 days (mean 4.8 days) following the onset of the diet. In one responder, early disruption of the diet was followed by relapse of intractable SE, and the patient died. Epilepsy affected the other six responders within a few months. Discussion: KD may be an alternative therapy for refractory SE in FIRES and might be proposed in other types of refractory SE in childhood.     

Clinical evolution and epilepsy outcome in three patients with CDKL5‐related developmental encephalopathy

Aims. To further characterise CDKL5‐related disorder, previously classified as an early‐onset seizure variant of Rett syndrome, which is currently considered a specific and independent early‐infantile epileptic encephalopathy. Methods. We describe the epileptic phenotype and neurocognitive development in three girls with CDKL5 mutations showing severe neurodevelopmental impairment, with different epileptic phenotypes and severity. Results. The patients differed regarding age at epilepsy onset, seizure frequency, duration of “honeymoon periods”, as well as EEG features. The “honeymoon period”, defined as a seizure‐free period longer than two months, represented, in our case series, a good indicator of the epilepsy outcome, but not of the severity of developmental impairment. However, even during the “honeymoon period”, the interictal EEG showed epileptiform abnormalities, slowing, or a disappearance of physiological pattern. The natural history of CDKL5 disorder was compared between the three girls, focusing on the relationship between electroclinical features and neurological development. Conclusion. Our findings suggest that CDKL5 mutations likely play a direct role in psychomotor development, whereas epilepsy is one of the clinical features associated with this complex disorder.     

Two types of early epileptic encephalopathy in a Pitt-Hopkins syndrome patient with a novel TCF4 mutation

IntroductionPitt-Hopkins syndrome (PTHS) is a neurodevelopmental disorder caused by mutations in TCF4. Seizures have been found to vary among patients with PTHS. We report the case of a PTHS patient with a novel missense mutation in the gene TCF4, presenting with two types of early epileptic encephalopathy.Case reportThe patient was a Japanese boy. His first seizure was reported at 17 days of age, with twitching of the left eyelid and tonic-clonic seizures on either side of his body. An ictal electroencephalogram (EEG) showed epileptic discharges arising independently from both hemispheres, occasionally resembling migrating partial seizures of infancy (MPSI) that migrated from one side to the other. Brain magnetic resonance imaging revealed agenesis of the corpus callosum. His facial characteristics included a distinctive upper lip and thickened helices. His seizures were refractory, and psychomotor development was severely delayed. At the age of 10 months, he developed West syndrome with spasms and hypsarrhythmia. After being prescribed topiramate (TPM), his seizures and EEG abnormalities dramatically improved. Also, psychomotor development progressed. Whole-exome sequencing revealed a novel de novo missense mutation in exon 18 (NM_001083962.2:c.1718A > T, p.(Asn573Ile)), corresponding to the basic region of the basic helix-loop-helix domain, which may be a causative gene for epileptic encephalopathy.ConclusionsTo our knowledge, this is the first report of a patient with PTHS treated with TPM, who presented with both MPSI as well as West syndrome. This may help provide new insights regarding the phenotypes caused by mutations in TCF4.