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PubMed1992

The tottering mouse: a critical review of its usefulness in the study of the neuronal mechanisms underlying epilepsy.

The tottering mouse resulted from a recessively inherited, autosomal, single-locus mutation which produces a very characteristic neurological and cellular phenotype. Almost simultaneously and late in the development of this mutant appears a triad of symptoms: frequent episodes of absence seizures with spike-and-wave discharges; more rarely occurring episodes of focal motor seizures; and ataxia. Electrographic, behavioural and pharmacological similarities to absence epilepsy in man make the tottering mouse a useful animal model for testing new anti-absence drugs. It also affords a unique opportunity to study the effects of multiple alleles on epileptic behaviour. The neuronal mechanisms underlying the generation of absence seizures in this mutant are apparently a combination of a generalized noradrenergic hyperactivity in the brain and some gene-linked, but unknown, conditions prevailing in an earlier phase of development at specific brain areas which induce the generalized forebrain hyper-innervation by locus coeruleus terminals. Several biochemically, microscopically and electrophysiologically identified cellular differences between normal and tottering mice are potential aspects of this primary developmental defect. Research into these gene-linked neuronal characteristics co-inherited with seizures in this mutant makes the tottering mouse a powerful tool in the study of cellular mechanisms underlying genetically determined factors in epileptogenesis.

Action Potentials↗
PubMedDate not supplied

Memory function in childhood epilepsy syndromes.

OBJECTIVE: Children with epilepsy are at risk of specific cognitive deficits. We aimed to compare and characterize the memory function of children with childhood absence epilepsy (CAE), frontal lobe epilepsy (FLE) and temporal lobe epilepsy (TLE). METHODS: Epilepsy syndrome was identified by clinical data, seizure semiology, interictal and ictal electroencephalogram (EEG). Seventy children aged 6-18 years with CAE, FLE or TLE had neuropsychological assessment including memory function. After adjusting for epilepsy variables, neuropsychological results of the syndrome groups and normative data were compared. RESULTS: Children from all three syndrome groups were at risk of memory difficulties. The duration of epilepsy correlated negatively with memory function. Children with TLE had the worst memory function, significantly lower in verbal memory tasks than children with CAE (P = 0.02) and children with FLE (P = 0.01). The performance of children with TLE was significantly below the normed mean across all verbal and most visual tasks. Compared to the normed means, children with FLE had results that were statistically lower in some verbal and visual tasks, and children with CAE were lower in two visual tasks only. CONCLUSIONS: This study demonstrates memory dysfunction in three common childhood epilepsy syndromes. Children with TLE had the greatest impairment, children with FLE had memory difficulties not previously reported, and children with CAE had subtle memory deficits. Qualitative differences were also evident. Longer duration of intractable epilepsy was associated with reduced memory ability. Memory function and its potential impact on academic achievement are vital considerations when managing children with epilepsy.

Adolescent↗
PubMedDate not supplied

Concordance of clinical forms of epilepsy in families with several affected members. Italian League Against Epilepsy Genetic Collaborative Group.

Evidence for genetic heterogeneity in epilepsy is strong. We evaluated the concordance of clinical forms in the same family in a series of families with several cases of idiopathic epilepsy, collected as part of the Study on the Genetics of Epilepsy of the Italian League against Epilepsy (LICE). The studied families had at least three members affected by an idiopathic form of epilepsy in one or more generations. Seventy-four families (with a total of 296 affected members) have been analyzed; two families had cases with benign neonatal familial convulsions (BNFC); in 25% of the remaining families all members were affected by the same clinical form, 13.9% had a prevalent clinical form with only one affected member with a different seizure type, 36.1% had two clinical forms, and 25% had three forms of epilepsy in the same family. There are no clinical differences in the form of epilepsy between the families concordant for one clinical form and families with two or three clinical forms of idiopathic epilepsies. The distribution of the clinical form in the affected relatives in our families showed the higher concordance with the proband in febrile convulsions (FC, 70.8%) and in epilepsy with generalized tonic-clonic seizures (EGTC, 63.0%). FC and EGTC were highly diffused in the affected relatives in the families with other forms of idiopathic epilepsy, above all in the more distantly related affected family members. In our families we observed a rare associated between childhood absence epilepsy (CAE) and juvenile myoclonic epilepsy (JME).(ABSTRACT TRUNCATED AT 250 WORDS)

Epilepsy↗
PubMed2006

Coexisting muscular dystrophies and epilepsy in children.

Muscular dystrophies are composed of a variety of genetic muscle disorders linked to different chromosomes and loci and associated with different gene mutations that lead to progressive muscle atrophy and weakness. Fukuyama congenital muscular dystrophy is frequently associated with partial and generalized epilepsy and congenital brain anomalies, including cobblestone complex and other neuronal migration defects. We report generalized convulsive epilepsy in a boy with normal brain magnetic resonance imaging and Duchenne muscular dystrophy with deletion of dystrophin gene, and we report absence epilepsy with normal brain magnetic resonance imaging in another boy with limb girdle muscular dystrophy with partial calpain deficiency. We, therefore, review coexisting muscular dystrophies and epilepsy in children. In addition to Fukuyama congenital muscular dystrophy, partial or generalized epilepsy has also been reported in the following types of muscular dystrophies, including Duchenne/Becker dystrophy, facioscapulohumeral dystrophy, congenital muscular dystrophy with partial and complete deficiency of laminin alpha2 (merosin) chain, and limb girdle muscular dystrophy with partial calpain deficiency.

Brain↗
PubMedDate not supplied

[Idiopathic epilepsies: some therapeutic aspects].

AIMS: The purpose of this study was to determine the therapeutic approach to be used in localisation-related and generalised epilepsies and idiopathic epileptic syndromes. DEVELOPMENT: Recent literature on the subject was reviewed, as were the records on a total of 118 patients from two paediatric neurology units between the years 2000 and 2003. With regard to the localisation-related cases, the following recommendations are made: 1. Treatment with monotherapy; 2. Low doses, since any antiepileptic drug can make epilepsy worse, and more so in the case of RBEI; 3. If the seizures get worse with treatment, the doses must be reduced instead of increased; 4) Carbamazepine (CBZ) and oxcarbazepine (OXC) are first choice drugs; clobazam (CLB) is indicated in OBEI and in some atypical BPEI, in which steroids in monotherapy can occasionally prove useful; valproate (VPA) is an alternative for cases of intolerance and exacerbation, and 5. Two-year treatment and electroencephalogram (EEG) monitoring for exacerbation. As regards idiopathic generalised epilepsies: 1. VPA in monotherapy is recommended in all the forms, 48% were controlled; 18% were controlled with VPA + lamotrigine (LTG); 2. Childhood absence epilepsy is controlled up to 50% with VPA and 85% with VPA + ethosuximide (ESM); 3. LTG, CLB, topiramate (TPM) and Rivotril (CLN) are alternatives to be considered in all types of epilepsies and syndromes that are resistant to medication, and 4. In GCTS, VPA should be chosen in low doses in juvenile myoclonic epilepsy of Janz.

Anticonvulsants↗
PubMed1999

Coexistence of temporal lobe and idiopathic generalized epilepsies.

OBJECTIVE: To assess the interrelation of idiopathic generalized epilepsy (IGE) and temporal lobe epilepsy (TLE) when they coexist in the same patient. METHODS: The authors reviewed the electroclinical features of 350 consecutive patients who had temporal resection between 1975 and 1997 at the Maudsley and King's College Hospitals, London. RESULTS: Two patients had the unusual combination of TLE and IGE (0.57%). In the first, the clinical onset of juvenile myoclonic epilepsy followed the surgical resolution of his partial seizures but had been heralded for at least 5 years by subclinical spontaneous and photically induced generalized spike-wave discharges. In the second, TLE and juvenile absence epilepsy had a long parallel course before surgery. After surgery he had no further partial seizures. CONCLUSION: These cases suggest that when an idiopathic absence or myoclonic syndrome manifests in a patient with symptomatic TLE, the phenotype may not be a merged syndrome. Rather, the two conditions can retain their inherent electroclinical profile, responsiveness to treatment, and prognosis.

Adult↗
PubMed1990

Involvement of NMDA receptors in non-convulsive epilepsy in WAG/Rij rats.

The involvement of the NMDA receptor in spontaneous non-convulsive epilepsy was studied by intracerebroventricular injections of APH and NMDA in WAG/Rij rats. The WAG/Rij rat strain is recognized as an animal model for human absence epilepsy. EEG registrations showed that APH (5 nmol/5 microliters; 25 nmol/5 microliters; 50 nmol/5 microliters) causes a dose-dependent decrease in the number and mean duration of the spike-wave discharges, while NMDA (50 pmol/5 microliters; 500 pmol/5 microliters; 5 nmol/5 microliters) induces a dose-dependent increase in the number. The effects of NMDA (5 nmol/5 microliters) can be blocked completely by APH (50 nmol/5 microliters). These results suggest an involvement of the NMDA receptor in experimental non-convulsive epilepsy, observed in the WAG/Rij model.

2-Amino-5-phosphonovalerate↗
PubMed2004

Mixed forms of epilepsy in a subpopulation of WAG/Rij rats.

Mixed forms of epilepsy in patients are often refractory. Therefore, animal models of comorbid convulsive and nonconvulsive seizure are needed for experimental research. Susceptibility to audiogenic convulsions was studied in a large group of young and adult WAG/Rij rats with inherited absence epilepsy. In 30% of adult rats, sound stimulation provoked audiogenic seizures of moderate intensity. The seizures had two excitation periods separated by a remarkably stable "arrest" of paroxysmal movements. Up to 20% of young WAG/Rij rats were also susceptible to audiogenic seizures, with a longer latency, lower intensity, and more simple seizure patterns. No difference in manifestations of spike-wave discharges was observed between the WAG/Rij rats with and without audiogenic seizures. This subpopulation of WAG/Rij rats genetically predisposed to absence and audiogenic seizures is proposed as an animal model suitable for investigation of basal mechanisms and pharmacological profiles of this mixed form of epilepsy.

Acoustic Stimulation↗
PubMed1996

[Treatment of epilepsy: where are we today?].

The modern treatment of epilepsy has improved considerably in all three pillars. More than a century has passed, however, since Sir Charles Locock introduced the bromides in 1857 and Sir Victor Horsely pioneered epilepsy surgery in 1886 (18). In drug therapy, the 'classic AED' of the last decades, i.e. phenobarbital (Hauptmann, 1912) and phenytoin (Putnam and Merrit, 1938) are being largely displaced by valproate (Meunir, 1963) and carbamazepine (Lorge, 1963). Only ethosuximide (Zimmermann, 1951) has continued to maintain its position in 3/s spikewave-absence epilepsy, in particular in the USA (28, 29). Although it is an excellent drug against absences, it has the unpleasant property that it may induce GM seizures and should therefore be combined with a so-called 'GM protector' (mostly phenobarbital). For this reason ethosuximide has been relegated to second place in Europe by valproate. Thus, the decision as to which AED should be employed at the outset has been simplified considerably: actually, with valproate as the drug of first choice, which displays a very broad spectrum of action, we are on the right track for virtually all forms of epilepsy, perhaps with the exception of focal epilepsy (11). Especially in the event of focal epilepsy of temporal origin we employ carbamazepine as the preparation of first choice. In some countries (Denmark), because of the less severe side effects, oxcarbazepine is already preferred (Mogens Dam, personal communication). Considerable experience and knowledge are still required, however, when resistance has developed to traditionally applied classic monotherapy. Here, the range of further treatment can also be greatly extended by the availability of the 'new AED'. A generally accepted protocol for the replacement of one preparation with another first- or second-choice drug and, above all, for the 'right' combination with third-choice preparations can as yet not be compiled. What we need here is the expert epileptologist who has experience with 'theoretically useful' combinations and has an insight into the interactions occurring with such combinations. For several specific epileptic syndromes the 'Königsteiner Working Group of German-Speaking Epileptologists' has given clear and binding recommendations for AED therapy (e.g. for benign juvenile myoclonic epilepsy--Janz syndrome). This working group has also made recommendations for the necessary clinical and laboratory controls in AED therapy with potentially severe side effects (e.g. valproate therapy in high-risk children), which were published and/or are being published and discussed in the 'Epilepsie-Blätter' of the German League against Epilepsy (4). Despite all advances in drug therapy, the number of epilepsy patients not satisfactorily treatable with drug therapy has not been dramatically reduced statistically, so that the other two pillars of epilepsy therapy, i.e. epileptic surgery and behavioural therapy, continue to be very important.

Anticonvulsants↗
PubMed2003

Epilepsy in offspring of whom both parents have idiopathic generalized epilepsy: biparental inheritance.

BACKGROUND: Little is known about offspring of parents who both have idiopathic generalized epilepsy (IGE). This is of importance for understanding the complex genetic architecture of IGE. METHODS: Families in whom both parents had proven IGE were ascertained through a multiplex families database. Clinical information including EEG recordings and detailed pedigrees was obtained. RESULTS: In family I, the mother had juvenile myoclonic epilepsy (JME), and the father had IGE. One daughter had Lennox-Gastaut syndrome, and the other had unclassified epilepsy. In family II, the mother had JME, and the father had IGE. Two of three sons had an identical clinical picture of clinical picture of childhood absence epilepsy (CAE), but with fast polyspike-wave discharges on EEG. CONCLUSIONS: The clinical phenotype of affected offspring suggested that their epilepsy could be due to the combination of a putative "double dose" of genes from both sides of the family. In such families, as epilepsy genes could be inherited from both parents, a high risk of epilepsy in the offspring could be expected.

Adult↗
PubMed1999

Localization of a gene for benign adult familial myoclonic epilepsy to chromosome 8q23.3-q24.1.

Benign adult familial myoclonic epilepsy is an autosomal dominant idiopathic epileptic syndrome characterized by adult-onset tremulous finger movement, myoclonus, epileptic seizures, and nonprogressive course. It was recently recognized in Japanese families. In this study, we report that the gene locus is assigned to the distal long arm of chromosome 8, by linkage analysis in a large Japanese kindred with a maximum two-point LOD score of 4.31 for D8S555 at recombination fraction of 0 (maximum multipoint LOD score of 5.42 for the interval between D8S555 and D8S1779). Analyses of recombinations place the locus within an 8-cM interval, between D8S1784 and D8S1694, in which three markers, D8S1830, D8S555, and D8S1779, show no recombination with the phenotypes. Although three other epilepsy-related loci on chromosome 8q have been recognized-one on chromosome 8q13-21 (familial febrile convulsion) and two others on chromosome 8q24 (KCNQ3 and childhood absence epilepsy)-the locus assigned here is distinct from these three epilepsy-related loci. This study establishes the presence of a new epilepsy-related locus on 8q23.3-q24.11.

Adolescent↗
PubMed2003

Dynamic GABA(A) receptor subtype-specific modulation of the synchrony and duration of thalamic oscillations.

Networks of interconnected inhibitory neurons, such as the thalamic reticular nucleus (TRN), often regulate neural oscillations. Thalamic circuits generate sleep spindles and may contribute to some forms of generalized absence epilepsy, yet the exact role of inhibitory connections within the TRN remains controversial. Here, by using mutant mice in which the thalamic effects of the anti-absence drug clonazepam (CZP) are restricted to either relay or reticular nuclei, we show that the enhancement of intra-TRN inhibition is both necessary and sufficient for CZP to suppress evoked oscillations in thalamic slices. Extracellular and intracellular recordings show that CZP specifically suppresses spikes that occur during bursts of synchronous firing, and this suppression grows over the course of an oscillation, ultimately shortening that oscillation. These results not only identify a particular anatomical and molecular target for anti-absence drug design, but also elucidate a specific dynamic mechanism by which inhibitory networks control neural oscillations.

Action Potentials↗
PubMed2005

Writing epilepsy: a neurophysiological, neuropsychological and neuroimaging study.

Writing epilepsy is a rare reflex syndrome in which seizures are triggered by writing. We describe a 33-year-old, right-handed man, with a history of juvenile absence epilepsy in remission and a family history of epilepsy, in whom myoclonic jerks precipitated exclusively by writing started at the age of 30. Intensive video/EEG monitoring during neuropsychological tests revealed, at about 1 minute after starting to write, a dystonic posture, followed by myoclonic jerks involving the right hand that shortly after became generalized. Concomitantly, the ictal EEG documented generalized hypersynchronous polyspike-wave discharges, maximal over the right parietocentral area. SPECT revealed an ictal hyperperfusion and interictal hypoperfusion over right parietofrontal regions, and fMRI showed extensive and intense left frontal, supplementary motor area activation, induced by writing. This case study provides some evidence supporting the hypothesis that the mechanism underlying writing-triggered seizures may be a generalized seizure process, with a focal cortical trigger zone, presumed to be the left frontal lobe as suggested by clinical and fMRI data. A relevant role played by the right hemisphere (right parietofrontal region) is postulated in the full-blown expression of reflex epileptogenesis, as supported by EEG and SPECT findings.

Adult↗
PubMed2002

Use of epileptic animals for adverse effect testing.

A crucial parameter deciding the clinical utility of new antiepileptic drugs (AEDs) is the therapeutic index expressing the margin between anticonvulsant and adverse effects. The latter is commonly quantified during preclinical testing in the rotarod test in normal, healthy rodents. However, the validity of using normal animals for adverse effect predictions in epilepsy patients is questionable. Limbic kindling of rodents induced by corneal kindling of mice and amygdala kindling of rats confirm that epileptic animals are more susceptible to the behavioral and cognitive alterations following acute administration of NMDA antagonists and certain established AEDs. This appears to represent a permanent reactivity specific for limbic kindling since it is absent in rats after chemical kindling with pentylenetetrazole. Animal species with inborn epilepsy, including audiogenic and photosensitive animals, are not revealing an enhanced susceptibility to the behavioral alterations induced by NMDA antagonists. In contrast, these induce severe adverse effects in genetic absence epilepsy rats where certain AEDs also are associated with a more marked deterioration of motor function than in normal animals. This appears in line with several complications with AED use in man being linked to an interaction with the dysfunction of the brain imposed by the epileptic condition. Thus, it is important to involve epileptic animals in preclinical adverse effect testing, in particular when evaluating new AED candidates with novel or unknown mechanisms. In that respect, limbic kindling appears to represent a sensitive and relevant approach.

Animals↗
PubMed2003

Chronic management of seizures in the syndromes of idiopathic generalized epilepsy.

As a group, idiopathic generalized epilepsies (IGEs) have the highest rates of complete seizure control with medication. However, there are little evidence-based data to guide drug choice for treatment. Examples of IGE include absence epilepsy, generalized tonic-clonic epilepsy, and juvenile myoclonic epilepsy. Generalized epilepsies seem to be particularly vulnerable to seizure aggravation, and medications that are primarily effective against partial seizures are more commonly involved in seizure aggravation than other medications. A review of current research has shown that only a few medications can control IGE without potentially causing seizure aggravation. Broad-spectrum antiepileptic drugs such as valproate (VPA), lamotrigine, and topiramate are extremely effective at controlling a variety of seizures without causing excessive seizure aggravation. Among these drugs, VPA has the longest clinical experience history and the largest body of published data.

Adult↗
PubMedDate not supplied

[Children with epilepsy - psychiatric and neuropsychological results in comparison to healthy children].

QUESTIONS: Do children with epilepsy exhibit psychiatric, intellectual or motoric symptoms compared to healthy children? How relevant is the type of epilepsy?. METHODS: Children with diagnosed epilepsy aged 6 - 15 years were investigated by means of an established neuropsychological test program. Under anticonvulsive therapy the children were free from epileptic seizures. Exclusion criteria were neurological diseases and mental retardation. A structured interview was performed and psychiatric symptoms were registered. Tests performed included non-verbal intelligence, general motor skills, concentration ability, speech, mathematics, and find motor skills. RESULTS: Altogether 102 children with epilepsy (absences N=27, grand-mal N=31, Rolandi N=17, symptomatic focal N=27) and a control group of healthy children of the same size were investigated. In children with epilepsy no psychiatric symptoms were observed. In all tests applied, children with epilepsy obtained poorer neuropsychological results than the healthy control group. Children with primarily generalised epilepsy exhibited markedly poorer results in data processing, speech, and fine motor skills as compared to the healthy group. Children with symptomatic focal epilepsy showed the poorest results with regard to all parameters tested. CONCLUSION: In the psychological test performed, children with epilepsy exhibited distinct differences compared to the control group, but no differences in the psychiatric evaluation.

Adolescent↗
PubMed2003

Mutations in CLCN2 encoding a voltage-gated chloride channel are associated with idiopathic generalized epilepsies.

Idiopathic generalized epilepsy (IGE) is an inherited neurological disorder affecting about 0.4% of the world's population. Mutations in ten genes causing distinct forms of idiopathic epilepsy have been identified so far, but the genetic basis of many IGE subtypes is still unknown. Here we report a gene associated with the four most common IGE subtypes: childhood and juvenile absence epilepsy (CAE and JAE), juvenile myoclonic epilepsy (JME), and epilepsy with grand mal seizures on awakening (EGMA; ref. 8). We identified three different heterozygous mutations in the chloride-channel gene CLCN2 in three unrelated families with IGE. These mutations result in (i) a premature stop codon (M200fsX231), (ii) an atypical splicing (del74-117) and (iii) a single amino-acid substitution (G715E). All mutations produce functional alterations that provide distinct explanations for their pathogenic phenotypes. M200fsX231 and del74-117 cause a loss of function of ClC-2 channels and are expected to lower the transmembrane chloride gradient essential for GABAergic inhibition. G715E alters voltage-dependent gating, which may cause membrane depolarization and hyperexcitability.

Adolescent↗