Whole exome sequencing and co-expression analysis identify an SCN1A variant that modifies pathogenicity in a family with genetic epilepsy and febrile seizures plus.

OBJECTIVE: Family members carrying the same SCN1A variant often exhibit differences in the clinical severity of epilepsy. This variable expressivity suggests that other factors aside from the primary sodium channel variant influence the clinical manifestation. However, identifying such factors has proven challenging in humans. METHODS: We perform whole exome sequencing (WES) in a large family in which an SCN1A variant (p.K1372E) is segregating that is associated with a broad spectrum of phenotypes ranging from lack of epilepsy, to febrile seizures and absence seizures, to Dravet syndrome. We assessed the hypothesis that the severity of the SCN1A-related phenotype was affected by alternate alleles at a modifier locus (or loci). RESULTS: One of our top candidates identified by WES was a second variant in the SCN1A gene (p.L375S) that was shared exclusively by unaffected carriers of the K1372E allele. To test the hypothesized that L375S variant nullifies the loss-of-function effect of K1372E, we transiently expressed Nav1.1 carrying the two variants in HEK293T cells and compared their biophysical properties with the wild-type (WT) variant, and then co-expressed WT with K1372E or L375S with K1372E in equal quantity and tested the functional consequence. The data demonstrated that co-expression of the L375S and K1372E alleles reversed the loss-of-function property brought by the K1372E variant, whereas WT-K1372E co-expression remained partial loss-of-function. SIGNIFICANCE: These results support the hypothesis that L375S counteracts the loss-of-function effect of K1372E such that individuals carrying both alleles in trans do not present epilepsy-related symptoms. We demonstrate that monogenic epilepsies with wide expressivity can be modified by additional variants in the disease gene, providing a novel framework for the gene-phenotype relationship in genetic epilepsies.

Widespread cortical dyslamination in epilepsy patients with malformations of cortical development.

PURPOSE: Recent research in epilepsy patients confirms our understanding of epilepsy as a network disorder with widespread cortical compromise. Here, we aimed to investigate the neocortical laminar architecture in patients with focal cortical dysplasia (FCD) and periventricular nodular heterotopia (PNH) using clinically feasible 3 T MRI. METHODS: Eighteen epilepsy patients (FCD and PNH groups; n = 9 each) and age-matched healthy controls (n = 9) underwent T1 relaxation 3 T MRI, from which component probability T1 maps were utilized to extract sub-voxel composition of 6 T1 cortical layers. Seventy-eight cortical areas of the automated anatomical labeling atlas were divided into 1000 equal-volume sub-areas for better detection of cortical abnormalities, and logistic regressions were performed to compare FCD/PNH patients with healthy controls with the T1 layers composing each sub-area as regressors. Statistical significance (p < 0.05) was determined by a likelihood-ratio test with correction for false discovery rate using Benjamini-Hochberg method. RESULTS: Widespread cortical abnormalities were observed in the patient groups. Out of 1000 sub-areas, 291 and 256 bilateral hemispheric cortical sub-areas were found to predict FCD and PNH, respectively. For each of these sub-areas, we were able to identify the T1 layer, which contributed the most to the prediction. CONCLUSION: Our results reveal widespread cortical abnormalities in epilepsy patients with FCD and PNH, which may have a role in epileptogenesis, and likely related to recent studies showing widespread structural (e.g., cortical thinning) and diffusion abnormalities in various human epilepsy populations. Our study provides quantitative information of cortical laminar architecture in epilepsy patients that can be further targeted for study in functional and neuropathological studies.

Evolution of EEG Findings in Pontocerebellar Hypoplasia Type 2A: Normal EEG in the First Few Months followed by Abnormal Tracing over the Years.

Pontocerebellar hypoplasia (PCH) is an autosomal recessive neurodevelopmental and neurodegenerative disorder characterized by cerebellar and pontine hypoplasia, progressive microcephaly, and developmental delay. Ten types of PCH have been described; PCH type 2A (PCH2A) due to a mutation in TSEN54 is the most frequent. Seizures have been reported in the large majority of patients. The probability of epilepsy developing increases with age, along with difficulties in differentiating seizures from dyskinetic movements. The aim of the present report was to describe the clinical symptoms and electroencephalogram (EEG) changes over time in three patients of Israeli Arab origin with PCH2A. All three, including two siblings and their first cousin, were homozygous for the TSEN54 p.A304S mutation. The patients demonstrated profound psychomotor retardation, severe spasticity and contractures, choreoathetoid movements, and seizures. The magnetic resonance imaging (MRI) scans and EEGs were reviewed by an experienced neuroradiologist and epileptologist, respectively. The MRI scans revealed a dragonfly-like cerebellar pattern in all patients. Despite the normal early EEG findings, all patients had characteristic features of epilepsy, with tonic seizures starting in the first days to months followed by focal to bilateral tonic-clonic seizures in early childhood which continued to adolescence. In conclusion, patients with PCH2A due to the missense mutation p.A304S in TSEN54 exhibit profound psychomotor delay, movement disorders, and intractable epilepsy. An evolution of EEG abnormalities and seizure semiology occurs over time. Similar to several other genetic epileptic encephalopathies, the normal early EEG tracing does not rule out the later occurrence of epilepsy.

Dual array EEG-fMRI: An approach for motion artifact suppression in EEG recorded simultaneously with fMRI.

OBJECTIVE: Although simultaneous recording of EEG and MRI has gained increasing popularity in recent years, the extent of its clinical use remains limited by various technical challenges. Motion interference is one of the major challenges in EEG-fMRI. Here we present an approach which reduces its impact with the aid of an MR compatible dual-array EEG (daEEG) in which the EEG itself is used both as a brain signal recorder and a motion sensor. METHODS: We implemented two arrays of EEG electrodes organized into two sets of nearly orthogonally intersecting wire bundles. The EEG was recorded using referential amplifiers inside a 3T MR-scanner. Virtual bipolar measurements were taken both along bundles (creating a small wire loop and therefore minimizing artifact) and across bundles (creating a large wire loop and therefore maximizing artifact). Independent component analysis (ICA) was applied. The resulting ICA components were classified into brain signal and noise using three criteria: 1) degree of two-dimensional spatial correlation between ICA coefficients along bundles and across bundles; 2) amplitude along bundles vs. across bundles; 3) correlation with ECG. The components which passed the criteria set were transformed back to the channel space. Motion artifact suppression and the ability to detect interictal epileptic spikes following daEEG and Optimal Basis Set (OBS) procedures were compared in 10 patients with epilepsy. RESULTS: The SNR achieved by daEEG was 11.05±3.10 and by OBS was 8.25±1.01 (p<0.00001). In 9 of 10 patients, more spikes were detected after daEEG than after OBS (p<0.05). SIGNIFICANCE: daEEG improves signal quality in EEG-fMRI recordings, expanding its clinical and research potential.

Sensitivity and specificity of seizure-onset zone estimation by ictal magnetoencephalography.

PURPOSE: Ictal video-electroencephalography (EEG) is commonly used to establish ictal onset-zone location. Recently software development has enabled systematic studies of ictal magnetoencephalography (MEG). In this article, we evaluate the ability of ictal MEG signals to localize the seizure-onset zone. METHODS: Twenty-six patients underwent ictal MEG and epilepsy surgery. Prediction of seizure-onset zone by ictal and interictal MEG was retrospectively compared with ictal-onset area found by intracranial EEG in 12 patients. The specificity and sensitivity of the prediction were calculated at hemisphere-lobe (HL) and at hemisphere-lobe-surface (HLS) levels. KEY FINDINGS: The sensitivity of ictal MEG source localization was 0.958 on HL and 0.706 on HLS levels, and its specificity was 0.900 on HL and 0.731 on HLS levels. The interictal MEG dipole cluster, defined as >10 dipoles on one lobar surface, had sensitivity of 0.400 and specificity of 0.769. Ictal MEG was equally sensitive and specific on dorsolateral and nondorsolateral neocortical surfaces up to a depth of 4 cm from the scalp. SIGNIFICANCE: Sources of ictal-onset MEG signals and interictal dipole clusters are essentially equally specific in estimation of the ictal-onset zone on lobar surface resolution, but ictal MEG is more sensitive. On the lobe resolution, ictal MEG estimates ictal-onset zone with high sensitivity and specificity.

Absence seizure provocation during routine EEG: Does position of the child during hyperventilation affect the diagnostic yield?

PURPOSE: When performed correctly, hyperventilation (HV) for three minutes provokes absence seizures in virtually all children, a finding suggestive of a diagnosis of childhood absence epilepsy (CAE). Interestingly, some children experience absence seizures while performing HV in the office yet do not experience absences during HV on subsequent routine EEG. In most instances, HV during routine EEG is performed in the supine position, while in the office HV is done with the child sitting-up. Therefore, we hypothesized that the position in which HV is performed may influence its yield in provoking absence seizures. METHODS: We conducted a randomized multi-center controlled trial among children (4-10 years old) with suspected CAE. During a routine EEG, children were asked to perform HV twice, in the supine and sitting positions. RESULTS: Twenty children (four males) diagnosed with CAE were included in the analysis. Seventeen of the 20 patients experienced absence seizures while sitting and 13 experienced seizures during supine HV (p = 0.031). All patients that had absence seizures during supine HV also had seizures during sitting HV. Among patients with absences in both positions, seizure duration was significantly shorter during sitting HV (mean 8.69 seconds) than during supine HV (mean 12 seconds) (p = 0.042). An opposite tendency was seen in the younger age group (4-7 years), with shorter seizures in the supine HV group (5.6 seconds supine, 7.57 seconds sitting, p = 0.019). CONCLUSIONS: HV in the sitting position may increase the yield of provoking absence seizures during routine EEGs, thereby improving its sensitivity in the diagnosis of CAE.

Hyperventilation during routine electroencephalography: are three minutes really necessary?

OBJECTIVE: Hyperventilation induces absence seizures in children with absence epilepsy, and routine electroencephalography studies include three minutes of hyperventilation. We studied the duration of hyperventilation required to provoke a first absence seizure to determine whether three minutes of the procedure are indeed necessary. METHODS: Electroencephalography records of children who experienced absence seizures during hyperventilation were reviewed. The time from hyperventilation onset to a first and further seizure(s) was measured, and the occurrence of absences during the posthyperventilation phase was also noted. RESULTS: Sixty-two studies were evaluated. Mean time from hyperventilation onset to a first absence was 52 seconds (median 32 seconds). The vast majority (85.5%) had an absence within 90 seconds. Most (68%) children sustained a single event. All eight children with posthyperventilation seizures had experienced at least one event during hyperventilation. CONCLUSIONS: Our findings suggest that current guidelines for routine pediatric electroencephalography recording requiring three minutes of hyperventilation may not be clinically necessary. We found that the vast majority of children referred for suspected absence seizures experience a seizure less than 90 seconds after hyperventilation onset, and even more so by 120 seconds. Hence, a larger prospective study is warranted to establish more accurate hyperventilation duration parameters. We also suggest that once an absence seizure has been recorded at any time during hyperventilation, this procedure could be stopped, thus reducing the amount of discomfort for the child.

Lethal neonatal rigidity and multifocal seizure syndrome--report of another family with a BRAT1 mutation.

We describe two siblings born to consanguineous Arab-Muslim parents who presented in early infancy with myoclonic seizures, hypertonia and contractures, arrested head growth, inability to swallow, and bouts of apnea-bradycardia, culminating in cardiac arrest and death. Whole-genome sequencing yielded a c.1173delG mutation in the BRAT1 gene. Three recent reports identified mutations in the same gene in three infants from three Amish sibships, one Mexican neonate and two Japanese siblings with similar clinical manifestations. The authors speculated that the destabilization of the encoded protein may underlie the catastrophic epilepsy and corticobasal neuronal degeneration. We suggest that BRAT1 be added to the growing list of genes that are related to severe early infantile (neonatal) epileptic encephalopathy.

Clinical experience with open-label topiramate use in infants younger than 2 years of age.

To assess the efficacy, safety, and tolerability of topiramate in infants younger than 24 months of age, we conducted an open-label, multicenter chart review study of infants who received topiramate. Twenty-eight patients were evaluated. All had refractory epilepsy. The mean age of seizure onset was 3.8 months (range 0-10 months). Refractory infantile spasms were the most common epilepsy syndrome. Among infants without infantile spasms, complex partial seizures were the prominent seizure type in eight, followed by simple partial seizures in six. Topiramate was prescribed as add-on therapy in 25 cases and a s monotherapy in 3 cases. Seven of the eight infantile spasms cases improved on topiramate therapy, attaining topiramate monotherapy in three infants. Half of the infants with other seizure types responded to topiramate. The average treatment duration among topiramate responders was 11 months. Topiramate was prescribed after a mean of 3.3 antiepilepsy drugs had been used in these infants. In no case was topiramate the first prescribed antiepilepsy drug. Adverse effects occurred only in five patients, leading to topiramate discontinuation in two patients. Topiramate was efficacious and well tolerated in infants younger than 24 months of age with refractory epilepsy. Prospective data are needed to corroborate this observation.

Epilepsy associated with pediatric brain tumors: the neuro-oncologic perspective.

The aim of the study was to correlate the onset of epilepsy with the disease stage in children with brain tumors through treatment and follow-up in the oncologic department. The study sample consisted of a heterogenous group of 219 children who were aged 6 months to 11 years, manifested brain tumors, and had been treated and monitored in the Department of Pediatric Oncology of the Schneider Children's Medical Center of Israel since 1991. The overall rate of epilepsy was 14.6%, which rose to 38% in those with cortical tumors. Two major causes of epilepsy were evident: tumor-related and treatment-related. The first group could be further divided into epilepsy starting at or before diagnosis of brain tumor, epilepsy associated with tumor progression, and epilepsy starting at end-stage disease. The second group could be divided into epilepsy caused by radiation damage to the brain and epilepsy related to another postoperative state. The data emphasize the significance of striving for complete tumor resection and the potential damage from the use of radiotherapy to the brain. The authors suggest that a change in local neurotransmitter balance may be the mechanism underlying tumor-related epilepsy.

Two siblings with early infantile myoclonic encephalopathy due to mutation in the gene encoding mitochondrial glutamate/H+ symporter SLC25A22.

AIM: To characterize a new subset of early myoclonic encephalopathy usually associated with metabolic etiologies with a new genetic entity. METHODS: We describe two siblings with early myoclonic encephalopathy born to consanguineous parents of Arab Muslim origin from Israel. We used homozygosity mapping and candidate gene sequencing to reveal the genetic basis of the myoclonic syndrome. RESULTS: We found a rare missense mutation in the gene encoding one of the two mitochondrial glutamate/H symporters, SLC25A22. The phenotype of early myoclonic encephalopathy was first linked to the same mutation in 2005 in patients of the same ethnicity as our family. CONCLUSIONS: Owing to the devastating nature of this encephalopathy, we focus attention on its clinical history, epileptic semiology, distinct electroencephalography features, and genetic basis. We provide the evidence that an integrated diagnostic strategy combining homozygosity mapping with candidate gene sequencing is efficient in consanguineous families with highly heterogeneous autosomal recessive diseases.

Immunoglobulin treatment for severe childhood epilepsy.

We have used intravenous immunoglobulin to treat pediatric patients with various severe epileptic conditions. This retrospective, multicenter study comprised 64 consecutive patients treated with immunoglobulins for either epileptic encephalopathy or refractory epilepsy. The rate of full or partial improvement according to specific syndrome involved three of four patients with idiopathic West syndrome, six of 12 patients with electrical status epilepticus in sleep, eight of 19 patients with an undefined syndrome, one of three patients with Landau-Kleffner syndrome, and one of two patients with Rasmussen encephalitis. Intravenous immunoglobulins were ineffective in 10 patients with symptomatic West syndrome, nine with febrile infection-related status epilepticus, three with myoclonic astatic epilepsy, and two with Lennox-Gastaut syndrome. Nine patients (14%) demonstrated complete resolution, and 10 (15.6%) exhibited partial improvement. Of these 19 responders (29.7%), eight relapsed. Although intravenous immunoglobulin is not suitable for all cases of epilepsy, it may prove efficacious for specific epileptic syndromes, mainly idiopathic West syndrome and electrical status epilepticus during sleep.