Takashi Shibata

A study on spike focus dependence of high-frequency activity in idiopathic focal epilepsy in childhood

Spike foci in benign epilepsy with centrotemporal spikes (BECTS) are related to seizure semiologies, but this relationship is inconspicuous in Panayiotopoulos syndrome (PS). We analyzed spike‐associated high‐frequency activity (HFA) and its relationship to spike foci in the electroencephalograms (EEGs) of patients with BECTS and PS in order to elucidate the pathophysiology of these epileptic syndromes.

Phenotypic Variability in Childhood of Skeletal Muscle Sodium Channelopathies

BACKGROUNDnMutations of the SCN4A gene cause several skeletal muscle channelopathies and overlapping forms of these disorders. However, the variability of the clinical presentation in childhood is confusing and not fully understood among pediatric neurologists.nnnPATIENTSnWe found three different mutations (p.V445M, p.I693L, and a novel mutation, p.V1149L) in SCN4A but not in the CLCN1 gene. The patient with p.V445M showed the clinical phenotype of sodium channel myotonia, but her clear symptoms did not appear until 11 years of age. Her younger sister and mother, who have the same mutation, displayed marked intrafamilial phenotypic heterogeneity from mild to severe painful myotonia with persistent weakness. The patient with p.I693L exhibited various symptoms that evolved with age, including apneic episodes, tonic muscular contractions during sleep, fluctuating severe episodic myotonia, and finally episodic paralyses. The patient with the novel p.V1149L mutation exhibited episodic paralyses starting at 3 years of age, and myotonic discharges were detected at 11 years of age for the first time.nnnCONCLUSIONnThe present cohort reveals the complexity, variability, and overlapping nature of the clinical features of skeletal muscle sodium channelopathies. These are basically treatable disorders, so it is essential to consider genetic testing before the full development of a patients condition.

Novel PLA2G6 mutations associated with an exonic deletion due to non-allelic homologous recombination in a patient with infantile neuroaxonal dystrophy

Novel PLA2G6 mutations associated with p.Asp283Asn and a unique intragenic deletion of exons 4 and 5 due to non-allelic homologous recombination were identified in a Japanese female patient with typical infantile neuroaxonal dystrophy. The patient showed progressive tetraplegia beginning at 9 months. An electroencephalogram showed a diffuse increase in fast waves, and brain magnetic resonance imaging showed progressive brain atrophy and T2 hypointensity in the globus pallidus.

Idiopathic focal epilepsies: The lost tribe

The term idiopathic focal epilepsies of childhood (IFE) is not formally recognised by the ILAE in its 2010 revision (Berg et al., 2010), nor are its members and boundaries precisely delineated. The IFEs are amongst the most commonly encountered epilepsy syndromes affecting children. They are fascinating disorders that hold many treats for both clinicians and researchers. For example, the IFEs pose many of the most interesting questions central to epileptology: how are functional brain networks involved in the manifestation of epilepsy? What are the shared mechanisms of comorbidity between epilepsy and neurodevelopmental disorders? How do focal EEG discharges impact cognitive functioning? What explains the age-related expression of these syndromes? Why are EEG discharges and seizures so tightly locked to slow-wave sleep? In the last few decades, the clinical symptomatology and the respective courses of many IFEs have been described, although they are still not widely appreciated beyond the specialist community. Most neurologists would recognise the core syndromes of IFE to comprise: benign epilepsy of childhood with centro-temporal spikes or Rolandic epilepsy (BECTS/RE); Panayiotopoulos syndrome; and the idiopathic occipital epilepsies (Gastaut and photosensitive types). The Landau-Kleffner syndrome and the related (idiopathic) epilepsy with continuous spikes and waves in sleep (CSWS or ESES) are also often included, both as a consequence of the shared morphology of the interictal discharges and their potential evolution from core syndromes, for example, CSWS from BECTS. Atypical benign focal epilepsy of childhood also has shared electro-clinical features warranting inclusion. In addition, a number of less well-defined syndromes of IFE have been proposed, including benign childhood seizures with affective symptoms, benign childhood epilepsy with parietal spikes, benign childhood seizures with frontal or midline spikes, and benign focal seizures of adolescence. The term benign is often used in connection with the IFEs and is increasingly being challenged. Certainly most of these disorders are not associated with the devastating cognitive and behavioural problems seen with early childhood epileptic encephalopathies, such as West or Dravet syndromes. However, it is clear that specific, and sometimes persistent, neuropsychological deficits in attention, language and literacy accompany many of the IFEs that, when multiplied by the large numbers affected, make up a significant public health problem. Understanding the nature, distribution, evolution, risk and management of these is an important area of current research. A corollary to such questions regarding comorbidities is the role of focal interictal spikes and their enduring impact on cognitive functioning. What explains the paradox that epilepsies characterised by abundant interictal epileptiform abnormalities are often associated with very few clinical seizures? This is an exciting area in both clinical and experimental arenas and will eventually have important implications for clinical management of the whole child, taking into account not just seizures, but also adaptive functioning and quality of life. For several decades, we have accepted an evidence-free approach to using or not using antiepileptic drugs in IFEs. There is huge international variation and only a handful of studies examining neurocognitive outcomes. Clearly, this is a situation ready for an overhaul in practice. Fundamental to understanding treatment is knowledge of aetiology. In recent years, there have been several significant discoveries in IFEs from studies of copy number variation, exome sequencing, and linkage that prompt reconsideration of the unknown cause classification and strongly suggest a genetic aetiology. The IFE are strongly age-related, both with regards to age of seizure onset and remission. Does this time window solely relate to a similar age-related gene expression, or are there epigenetic factors involved that might also explain low observed twin concordance? The genetic (and epigenetic) models for different IFEs, their comorbidities, and their similarities to other neurodevelopmental disorders deserve investigation in the coming years. In so doing, we will probably learn much about normal brain functioning. This is because these disorders, perhaps more than any other human brain disease, are disorders of functional brain systems (even though these functional networks may not yet be fully defined). In June 2012, an international group of clinical and basic science researchers met in London under the auspices of the Waterloo Foundation to discuss and debate these issues in relation to IFEs. This Waterloo Foundation Symposium on the Idiopathic Focal Epilepsies: Phenotype to Genotype witnessed presentations that explored the clinical phenomenology, phenotypes and endophenotypes, and genetic approaches to investigation of these disorders. In parallel, the impact of these epilepsies on children and their families was reviewed. The papers in this supplement are based upon these presentations. They represent an updated state-of-the-art thinking on the topics explored. The symposium led to the formation of international working groups under the umbrella of Lukes Idiopathic Focal Epilepsy Project to investigate various aspects of the idiopathic focal epilepsies including: semiology and classification, genetics, cognition, sleep, high-frequency oscillations, and parental resources (see www.childhood-epilepsy.org). The next sponsored international workshop, in June 2014, was on randomised controlled trials in IFEs and overnight learning outcome measures.

Efficacy of topiramate for intractable childhood generalized epilepsy with epileptic spasms: With special reference to electroencephalographic changes

PURPOSEnEpileptic spasms (ES) beyond infancy are a highly refractory type of seizures that require the development of an effective treatment. We therefore studied the efficacy and safety of topiramate (TPM), which is a drug that is indicated to be effective for intractable childhood epilepsy, for ES.nnnMETHODSnOut of 58 children with ES, we enrolled 33 patients treated with TPM at ≤ 12 years of age. The administration of TPM was limited to cases of epilepsies that were resistant to any other potent treatment. We retrospectively investigated the efficacy of TPM for seizures and changes in electroencephalogram (EEG) findings.nnnRESULTSnThe median age at the start of TPM treatment was 5 years, 8 months. All patients had ES and 28 also had tonic seizures. As for the efficacy of TPM for all seizures, five patients became seizure-free and two had a ≥ 50% reduction in seizures. Seizure aggravation was observed in six patients. Of 29 patients whose EEG findings were compared before and during TPM treatment, nine showed EEG improvement with reduced epileptic discharges. Adverse effects were observed in 13 patients and included somnolence, anorexia, and irritability. In general, TPM was well tolerated.nnnCONCLUSIONSnTPM can be effective at suppressing very intractable ES in a proportion of patients who do not respond to any other treatment. The efficacy of TPM may be predictable based on EEG changes observed early in the course of treatment. TPM is promising for the treatment of extremely intractable childhood epilepsy and it has largely tolerable adverse effects.

Loss-of-function and gain-of-function mutations in PPP3CA cause two distinct disorders

Calcineurin is a calcium (Ca2+)/calmodulin-regulated protein phosphatase that mediates Ca2+-dependent signal transduction. Here, we report six heterozygous mutations in a gene encoding the alpha isoform of the calcineurin catalytic subunit (PPP3CA). Notably, mutations were observed in different functional domains: in addition to three catalytic domain mutations, two missense mutations were found in the auto-inhibitory (AI) domain. One additional frameshift insertion that caused premature termination was also identified. Detailed clinical evaluation of the six individuals revealed clinically unexpected consequences of the PPP3CA mutations. First, the catalytic domain mutations and frameshift mutation were consistently found in patients with nonsyndromic early onset epileptic encephalopathy. In contrast, the AI domain mutations were associated with multiple congenital abnormalities including craniofacial dysmorphism, arthrogryposis and short stature. In addition, one individual showed severe skeletal developmental defects, namely, severe craniosynostosis and gracile bones (severe bone slenderness and perinatal fractures). Using a yeast model system, we showed that the catalytic and AI domain mutations visibly result in decreased and increased calcineurin signaling, respectively. These findings indicate that different functional effects of PPP3CA mutations are associated with two distinct disorders and suggest that functional approaches using a simple cellular system provide a tool for resolving complex genotype-phenotype correlations.

Another Case of Glucose Transporter 1 Deficiency Syndrome with Periventricular Calcification, Cataracts, Hemolysis, and Pseudohyperkalemia

Glucose transporter 1 (GLUT1) deficiency syndrome (GLUT1DS) is a disorder resulting from shortage of energy in the brain caused by reduced GLUT1 activity. Its common clinical symptoms include seizures, microcephaly, intellectual disability, abnormal ocular movements, ataxia, and dystonia. We report a case of GLUT1DS with unusual symptoms, including periventricular calcification. The patient is a Japanese girl, whose seizures had always evolved into status epilepticus since she was 4 months old. She also had cataracts and horizontal nystagmus. Neuroimaging studies showed periventricular calcification and brain atrophy. Laboratory data revealed pseudohyperkalemia, reticulocyte increase, and hypoglycorrhachia. A mutation of c1306_1308delATC (p.Ile436del) was identified in the SLC2A1 gene, and she was thus diagnosed with GLUT1DS. A case with the identical SLC2A1 gene mutation and similar clinical findings was previously reported by Bawazir et al (2012). The leak of monovalent cations through the red cell membrane causes hemolysis in such patients, and a similar phenomenon may occur at the blood–brain barrier and the lens epithelium. After commencing ketogenic diet therapy, the electroencephalogram (EEG) abnormalities improved markedly and the patients development advanced. Clinicians should be aware of atypical GLUT1DS.

Measurement of pyridoxal 5′-phosphate, pyridoxal, and 4-pyridoxic acid in the cerebrospinal fluid of children

BACKGROUNDnWe quantified pyridoxal 5-phosphate (PLP), pyridoxal (PL), and 4-pyridoxic acid (PA) in the cerebrospinal fluid (CSF) of children and to investigate the effect of age, sex, epilepsy, and anti-epileptic drug (AED) therapy on these vitamers.nnnMETHODSnCSF samples prospectively collected from 116 pediatric patients were analyzed. PLP, PL, and PA were measured using high-performance liquid chromatography with fluorescence detection, using pre-column derivatization by semicarbazide. Effects of age, sex, epilepsy, and AEDs on these vitamers and the PLP/PL ratio were evaluated using multiple linear regression models.nnnRESULTSnThe PLP, PL, and PA concentrations were correlated negatively with age and the PLP/PL ratio was correlated positively with age. Multiple regression analysis revealed that the presence of epilepsy was associated with lower PLP concentrations and PLP/PL ratios but sex and AED therapy had no influence on these values. The observed ranges of these vitamers in epileptic and non-epileptic patients were demonstrated.nnnCONCLUSIONSnWe showed the age dependence of PLP and PL in CSF from pediatric patients. Epileptic patients had lower PLP concentrations and PLP/PL ratios than non-epileptic patients, but it is unknown whether this is the cause, or a result, of epilepsy.

Simultaneous measurement of monoamine metabolites and 5-methyltetrahydrofolate in the cerebrospinal fluid of children

BACKGROUNDnWe describe a new method for simultaneous measurement of monoamine metabolites (3-O-methyldopa [3-OMD], 3-methoxy-4-hydroxyphenylethyleneglycol [MHPG], 5-hydroxyindoleacetic acid [5-HIAA], and homovanillic acid [HVA]) and 5-methyltetrahydrofolate (5-MTHF) and its use on cerebrospinal fluid (CSF) samples from pediatric patients.nnnMETHODSnMonoamine metabolites and 5-MTHF were measured by high-performance liquid chromatography with fluorescence detection. CSF samples were prospectively collected from children according to a standardized collection protocol in which the first 1-ml fraction was used for analysis.nnnRESULTSnMonoamine metabolites and 5-MTHF were separated within 10min. They showed linearity from the limit of detection to 1024nmol/l. The limit of quantification of each metabolite was sufficiently low for the CSF sample assay. In 42 CSF samples after excluding cases with possibly altered neurotransmitter profiles, the concentrations of 3-OMD, MHPG, 5-HIAA, HVA, and 5-MTHF showed significant age dependence and their ranges were comparable with the reference values in the literature. The metabolite profiles of aromatic l-amino acid decarboxylase deficiency, Segawa disease, and folate receptor α defect by this method were compatible with those in the literature.nnnCONCLUSIONSnThis method is a simple means of measuring CSF monoamine metabolites and 5-MTHF, and is especially useful for laboratories not equipped with electrochemical detectors.

Clinical implications of preceding positive spikes in patients with benign partial epilepsy and febrile seizures

PURPOSEnTo clarify the clinical implications of the preceding positive spikes (PPSs) observed primarily in rolandic spikes, we analyzed PPSs in the rolandic and occipital spikes observed in the electroencephalograms (EEGs) of patients with two types of benign partial epilepsies (benign childhood epilepsy with centro-temporal spikes [BECT] and Panayiotopoulos syndrome [PS]) and febrile seizures (FS).nnnSUBJECTS AND METHODSnWe identified patients from our outpatient EEG database that were seen between 2006 and 2008 that had BECT, PS, and FS with rolandic or occipital spikes. We generated an averaged spike for each patient from the rolandic and occipital spikes that were detected using an automatic spike detection and clustering system. We compared the presence rate of the averaged spikes with the PPS among the three groups (BECT vs. PS vs. FS) using sequential mapping.nnnRESULTSnWe identified 25 BECT, 18 PS, and 15 FS patients with rolandic spikes. Fifteen BECT and nine PS patients exhibited a PPS in their averaged rolandic spikes, whereas only four FS patients did. Three of these four FS patients later developed afebrile seizures, and one of them was diagnosed as having PS. We analyzed eight PS and six FS patients with occipital spikes. Five PS patients exhibited a PPS in their averaged occipital spikes, whereas only one FS patient did. This FS patient later developed prolonged autonomic febrile seizures.nnnCONCLUSIONnPPSs are observed not only in rolandic spikes associated with BECT that is related strictly to sylvian seizures, but also in rolandic and occipital spikes associated with PS. Although PPSs are rare in such spikes observed in FS, patients with FS and PPSs may have an increased risk of developing afebrile seizures or prolonged autonomic febrile seizures. Further studies are warranted to determine the diagnostic utility of PPSs as a marker of the future development of epilepsy when they are observed in FS patients.