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PubMed2003

Effects of remacemide in two models of genetically determined generalized epilepsy, the GAERS and the audiogenic Wistar AS.

The antiepileptic effects of remacemide were assessed in two models of genetically determined generalized epilepsy. The model of non-convulsive epilepsy used was a model of absence seizures, the GAERS (genetic absence epilepsy rats from Strasbourg), and the model of convulsive seizures was an audiogenic rat model, the Wistar AS. In the eight GAERS studied, the three doses of remacemide (20, 40, and 80 mg/kg) dose-dependently reduced the expression of spike-and-wave discharges (SWDs) that had almost totally disappeared at the highest dose used, 80 mg/kg. However, at the latter dose, the effect of remacemide may be partly due to a change in the vigilance level of the animals. In the Wistar AS, the dose of 20 mg/kg prolonged by twofold the latencies to wild running and tonic seizures, and prevented their expression in one rat out of the eight studied. At 40 mg/kg, the expression of wild running and tonic seizures was inhibited in seven and maintained in one of the eight rats studied. The present results support the effects of remacemide in tonic/clonic seizure, which was the first target of the drug, and confirm the effect of the anticonvulsant on absence seizures.

Acetamides↗
PubMed2005

Seizure-related factors and non-verbal intelligence in children with epilepsy. A population-based study from Western Norway.

PURPOSE: To study the relationship between seizure-related factors, non-verbal intelligence, and socio-economic status (SES) in a population-based sample of children with epilepsy. METHODS: The latest ILAE International classifications of epileptic seizures and syndromes were used to classify seizure types and epileptic syndromes in all 6-12 year old children (N=198) with epilepsy in Hordaland County, Norway. The children had neuropediatric and EEG examinations. Of the 198 patients, demographic characteristics were collected on 183 who participated in psychological studies including Raven matrices. 126 healthy controls underwent the same testing. Severe non-verbal problems (SNVP) were defined as a Raven score at or <10th percentile. RESULTS: Children with epilepsy were highly over-represented in the lowest Raven percentile group, whereas controls were highly over-represented in the higher percentile groups. SNVP were present in 43% of children with epilepsy and 3% of controls. These problems were especially common in children with remote symptomatic epilepsy aetiology, undetermined epilepsy syndromes, myoclonic seizures, early seizure debut, high seizure frequency and in children with polytherapy. Seizure-related characteristics that were not usually associated with SNVP were idiopathic epilepsies, localization related (LR) cryptogenic epilepsies, absence and simple partial seizures, and a late debut of epilepsy. Adjusting for socio-economic status factors did not significantly change results. CONCLUSIONS: In childhood epilepsy various seizure-related factors, but not SES factors, were associated with the presence or absence of SNVP. Such deficits may be especially common in children with remote symptomatic epilepsy aetiology and in complex and therapy resistant epilepsies. Low frequencies of SNVP may be found in children with idiopathic and LR cryptogenic epilepsy syndromes, simple partial or absence seizures and a late epilepsy debut. Our study contributes to an overall picture of cognitive function and its relation to central seizure characteristics in a childhood epilepsy population and can be useful for the follow-up team in developing therapy strategies that meet the individual needs of the child with epilepsy.

Adolescent↗
PubMed1986

The long-term course of primary generalized epilepsy with persisting absences.

The long-term course of primary generalized epilepsy with absences persisting after the age of 30 to 61 years was studied in 26 patients, each followed clinically and by EEG for 20 to 37 years. Whether treated or not, absences became less frequent, but only rarely ceased, and 92% of patients with persisting absences eventually developed generalized convulsions. EEG background activity did not deteriorate, and the classic spike and wave complexes remained typical in 84% of patients. In 36% of cases, almost all of them women, psychomotor slowing was observed, which did not affect job performance. It was not related solely to duration or severity of epilepsy, or to antiepileptic drugs, and some hormonal mechanism may be partly responsible.

Adult↗
PubMed2001

Effects of high-affinity GABAB receptor antagonists on active and passive avoidance responding in rodents with gamma-hydroxybutyrolactone-induced absence syndrome.

RATIONALE: Absence seizures in man are behaviourally manifested as arrest and mild jerks mainly of facial muscles, associated in the electroencephalogram with synchronous spike and wave discharges. Gamma-hydroxybutyrolactone (GHBL) administration is currently used as an experimental model of absence seizures in rats and mice. OBJECTIVE: The aim of the present study was to examine the effects of three potent gamma-aminobutyric acid (GABA)B receptor antagonists CGP55845A, CGP62349 and CGP71982 (0.01 mg/kg) on the development of GHBL-induced absence epilepsy and in learning paradigms of active and passive avoidance tests in GHBL-treated mice and rats. METHODS: After 4 weeks of development of the absence syndrome, active and passive avoidance tests with negative reinforcement were performed. In both animal species, the absence syndrome was observed after 3 weeks of treatment in the saline group. RESULTS: The GABAB receptor antagonists CGP55845A and CGP62349 appeared to suppress the development of the absence syndrome to a greater degree in mice than in rats. CGP71982 suppressed it later than the other two antagonists (fifth week). In an active avoidance test in GHBL-treated mice, the GABAB antagonists had different effects - CGP62349 improved learning and memory retention to a greater extent than CGP55845A, whilst CGP71982 had no influence on it. In a passive avoidance test in GHBL-treated mice, the GABAB antagonists also had different effects - CGP71982 improved both learning and memory retrieval, whereas CGP55845A and CGP62349 had no effect. In the active avoidance test in GHBL-treated rats, the GABAB antagonist CGP55845A improved learning, whereas the other two, CGP62349 and CGP71982, had no effect. In the passive avoidance test the GHBL-treated rats showed an improvement in short memory retrieval. CGP55845A and CGP71982 improved this further, whilst CGP62349 had no effect. CONCLUSIONS: GHBL appeared to influence mice and rats in a different manner - rats learned the active avoidance task better than the GHBL-treated mice. The present study confirms previous data that GABAB antagonists suppress absence behaviour.

Animals↗
PubMed1992

Myoclonic-astatic epilepsy.

Myoclonic-astatic epilepsy (MAE) belongs to the group of epilepsies with primarily generalized seizures as absence epilepsies, and juvenile myoclonic epilepsy, as well as infantile and juvenile idiopathic epilepsy with generalized tonic-clonic seizures. Like these types of epilepsy, MAE is polygenically determined with little non-genetic variability. The disease is characterized by the following criteria: genetic predisposition (high incidence of seizures and/or genetic EEG patterns in relatives); mostly normal development and no neurological deficits before onset; primarily generalized myoclonic, astatic or myoclonic-astatic seizures, short absences and mostly generalized tonic-clonic seizures; no tonic seizures or tonic drop attacks during daytime (except for some rare cases with a most unfavourable course); generalized EEG patterns (spikes and waves, photosensitivity, 4-7/sec rhythms), no multifocal EEG abnormalities (but often pseudofoci). There is a partial overlap with other 'syndromes', such as benign and severe myoclonic epilepsy in infants (Dravet et al., 1985a, b), myoclonic epilepsy of infancy and early childhood (Aicardi and others). In differential diagnosis the Lennox-Gastaut syndrome in its stricter sense has to be considered, and also atypical benign partial epilepsy or pseudo-Lennox syndrome. Discussion is presented of possible pitfalls in the classical syndromic approach to classifying epilepsies of early childhood, and of the advantages of a neurobiological view for understanding the immense variability of clinical manifestations of epilepsy.

Brain Mapping↗
PubMed2003

Cellular interactions in the rat somatosensory thalamocortical system during normal and epileptic 5-9 Hz oscillations.

In Genetic Absence Epilepsy Rats from Strasbourg (GAERS), generalized spike-and-wave (SW) discharges (5-9 SW s(-1)) develop during quiet immobile wakefulness from a natural, medium-voltage, 5-9 Hz rhythm. This study examines the spatio-temporal dynamics of cellular interactions in the somatosensory thalamocortical system underlying the generation of normal and epileptic 5-9 Hz oscillations. Paired single-unit and multi-unit recordings between the principal elements of this circuit and intracellular recordings of thalamic, relay and reticular, neurones were conducted in neuroleptanalgesied GAERS and control, non-epileptic, rats. The identity of the recorded neurones was established following juxtacellular or intracellular marking. At least six major findings have emerged from this study. (1) In GAERS, generalized spike-and-wave discharges were correlated with synchronous rhythmic firings in related thalamic relay and reticular neurones. (2) Usually, corticothalamic discharges phase-led related relay and reticular firings. (3) A depolarizing wave emerging from a barrage of EPSPs was the cause of both relay and reticular discharges. (4) In some relay cells, which had a relatively high membrane input resistance, the depolarizing wave had the shape of a ramp, which could trigger a low-threshold Ca2+ spike. (5) In reticular cells, the EPSP barrage could further trigger voltage-dependent depolarizations. (6) The epilepsy-related thalamic, relay and reticular, intracellular activities were similar to the normal-related thalamic activities. Overall, these findings strongly suggest that, during absence seizures, corticothalamic neurones play a primary role in the synchronized excitation of thalamic relay and reticular neurones. The present study further suggests that absence-related spike-and-wave discharges correspond to hypersynchronous wake-related physiological oscillations.

Animals↗
PubMed2001

Idiopathic generalised epilepsy with phantom absences and absence status in a child.

A syndrome of idiopathic generalised epilepsy with phantom absences of undetermined onset has been recently described. This syndrome clinically becomes apparent in adulthood with generalised tonic clonic seizures and frequently absence status epilepticus. We report an 11 year-old normal girl with frequent episodes of absence status and no other overt clinical manifestations. However, appropriate video-EEG recordings documented that she had frequent absence seizures that were so mild as to escape recognition by her and the parents. These consisted of mild impairment of cognition and eyelid fluttering during brief generalised discharges of spike/multiple spike and slow waves. No further seizures occurred and the EEG normalised after appropriate drug treatment. Thus, it appears that this syndrome of phantom absences and absence status may start much earlier, in late childhood. Appropriate video-EEG documentation is needed for the recognition of these patients that may be more common than it appears from the few published cases (with Video).

Brain↗
PubMed2000

[Lamotrigine therapy in children. Retrospective study of 32 children].

BACKGROUND: Lamotrigine is one of the new anti-epileptic drugs, which is a phenyltriazine derivative. It is considered to act via an inhibitory effect on voltage-sensitive sodium channels and to have no GABAergic action. PATIENTS AND METHOD: We studied its efficiency in 32 children with refractory epilepsy after a treatment of at least one year with other anti-epileptic drugs. We then compared our results with other publications. RESULTS: Good efficiency (at least 50% reduction of crises) has been demonstrated for lamotrigine in children with generalized epilepsy (62.5% good results), particularly with absence epilepsy and Lennox-Gastaut syndrome. Results are encouraging for our few patients with epilepsy with continuous spike waves during slow-wave sleep. On the other hand, more precise indications are needed in partial epilepsy. CONCLUSION: Seizure control was generally maintained during one year of lamotrigine treatment. Association to sodium valproate is relevant for most of the authors. Adverse effects are uncommon, and we did not observe any skin rash. Lastly, improvement of behaviour and cognitive functions represents another important benefit of lamotrigine.

Adolescent↗
PubMed2000

Gray matter heterotopia.

Gray matter heterotopia are common malformations of cortical development. From a clinical perspective, affected patients are best divided into three groups: subependymal, subcortical, and band heterotopia (also called double cortex). Symptomatic women with subependymal heterotopia typically present with partial epilepsy during the second decade of life; development and neurologic examinations up to that point are typically normal. Symptoms in men with subependymal heterotopia vary, depending on whether they have the X-linked or autosomal form. Men with the X-linked form more commonly have associated CNS and visceral anomalies; their development is typically abnormal. Symptomatic men with the autosomal variety have clinical courses similar to symptomatic women. Both men and women with subcortical heterotopia typically have congenital fixed neurologic deficits and develop partial epilepsy during the second half of the first decade of life. The more extensive the subcortical heterotopia, the greater the deficit; bilateral heterotopia are almost invariably associated with severe developmental delay or mental retardation. In general, band heterotopia are seen exclusively in women; men with a mutation of the related gene (called XLIS or DCX) usually die in utero or have a much more severe brain anomaly. Symptoms in affected women vary from normal to severe developmental delay or mental retardation; the severity of the syndrome is related to the thickness of the band of arrested neurons. Nearly all affected patients that come to medical attention have epilepsy, with partial complex and atypical absence epilepsy being the most common syndromes. Some of the more severely affected patients develop attacks.

Brain↗
PubMed1997

Linkage analysis between idiopathic generalized epilepsies and the GABA(A) receptor alpha5, beta3 and gamma3 subunit gene cluster on chromosome 15.

INTRODUCTION: We tested the hypothesis that genetic variants within the GABA(A) alpha5, beta3 and gamma3 subunit gene cluster on chromosome 15q11-q13 confer genetic susceptibility to common subtypes of idiopathic generalized epilepsy (IGE). MATERIAL AND METHODS: Ninety-four families were selected from IGE patients with either juvenile myoclonic epilepsy (JME), juvenile (JAE) or childhood absence epilepsy (CAE). Cosegregation was tested between dinucleotide polymorphisms associated with the human GABA(A) alpha5, beta3 and gamma3 subunit gene cluster and three different IGE trait models. RESULTS: Evidence against linkage to the GABA(A) alpha5, beta3 and gamma3 subunit gene cluster was found in the entire family set and subsets selected from either CAE or JAE. In 61 families of JME patients, a maximum lod score (Zmax=1.40 at Theta(max)=0.00) was obtained for a broad IGE spectrum ("idiopathic" generalized seizure or generalized spike and wave discharges in the electroencephalogram) assuming genetic heterogeneity (alpha=0.37; P=0.06) and an autosomal recessive mode of inheritance. CONCLUSION: The possible hint of linkage in families of JME patients emphasizes the need for further studies to determine whether a recessively inherited gene variant within the GABA(A) alpha5, beta3 and gamma3 subunit gene cluster contributes to the pathogenesis of "idiopathic" generalized seizures and associated EEG abnormalities in a proportion of families.

Chromosomes, Human, Pair 15↗
PubMed1997

Increased excitability and inward rectification in layer V cortical pyramidal neurons in the epileptic mutant mouse Stargazer.

The excitability of layer V cortical pyramidal neurons was studied in vitro in the single-locus mutant mouse stargazer (stg), a genetic model of spike wave epilepsy. Field recordings in neocortical slices from mutant mice bathed in artificial cerebrospinal fluid revealed spontaneous synchronous network discharges that were never present in wild-type slices. Intracellular and whole cell recordings from stg/stg neurons in deep layers showed spontaneous giant depolarizing excitatory post-synaptic potentials generating bursts of action potentials, and a 78% reduction in the afterburst hyperpolarization. Whole cell recordings revealed gene-linked differences in active membrane properties in two types of regular spiking neurons. Single action potential rise and decay times were reduced, and the rheobase current was decreased by 68% in mutant cells. Plots of spike frequency-current relationships revealed that the gain of this relation was augmented by 29% in the mutant. Comparisons of visually identified pyramidal neurons firing properties in both genotypes revealed no difference in single action potential afterhyperpolarization. Voltage-clamp recordings showed an approximately threefold amplitude increase in a cesium-sensitive inward rectifier. No cell density or soma size differences were observed in the layer V pyramidal neuron population between the two genotypes. These results demonstrate an autonomous increase in cortical network excitability in a genetic epilepsy model. This defect could lower the threshold for aberrant thalamocortical spike wave oscillations in vivo, and may contribute to the mechanism of one form of inherited absence epilepsy.

Action Potentials↗
PubMed1999

Childhood-onset epilepsy with and without preceding febrile seizures.

OBJECTIVE: To identify characteristics in children with epilepsy that differ between those who did versus did not have a history of preceding febrile seizures. BACKGROUND: Febrile seizures precede epilepsy in 10 to 15% of children. Little is known about the specific types of epilepsy associated with febrile seizures. METHODS: In a community-based, prospectively identified cohort of children, the association between prior febrile seizures and characteristics of the children's epilepsy (seizure type, epilepsy syndrome, age at onset, underlying etiology, family history) were examined for 524 of the children who were aged > or =1 year at onset of epilepsy. RESULTS: Seventy-three (13.9%) had febrile seizures. Children with febrile seizures were more likely to have a first-degree or a second-higher-degree relative with febrile seizures and less likely to have childhood absence epilepsy and absence seizures compared with children without febrile seizures. This was especially true for simple febrile seizures. There was no specific association with localization-related forms of epilepsy. Complex, but not simple, febrile seizures were associated with younger age at onset of epilepsy. There was no evidence that focal or prolonged febrile seizures were associated with localization-related epilepsy or temporal lobe epilepsy per se. Of the three children whose initial MRIs demonstrated hippocampal atrophy, none had a history of febrile seizures. CONCLUSIONS: At the time of diagnosis, febrile seizures are not specifically related to temporal lobe epilepsy or localization-related epilepsy in general. A genetic component for febrile seizures is suggested by its positive associations with family history, especially for simple febrile seizures. Complex febrile seizures represent an underlying age-dependent susceptibility.

Age of Onset↗
PubMed1994

Interactions between NMDA and nonNMDA receptors in nonconvulsive epilepsy in the WAG/Rij inbred strain.

The interaction between NMDA and nonNMDA receptors was studied in nonconvulsive epilepsy in WAG/Rij rats. Compounds acting on NMDA (NMDA, APH) and nonNMDA (AMPA, GDEE, kainic acid, kynurenic acid) receptors were coinjected intracerebroventricularly. The WAG/Rij rat strain may be an animal model for human nonconvulsive absence epilepsy. The effects on the epilepsy, EEG and behaviour were measured. It appeared that the epilepsy increase, induced by the nonNMDA receptor agonist AMPA, and in a less obvious way, kainic acid, was blocked by the NMDA receptor antagonist APH. The effects of NMDA were completely blocked by the nonNMDA receptor antagonists GDEE and kynurenic acid. These results suggest that there is an interaction between NMDA and nonNMDA receptors. It might be that nonNMDAergic compounds act via activation or inactivation of NMDA receptors and that this latter receptor subtype is the trigger for an epileptic seizure.

Animals↗
PubMed2005

[A course of idiopathic generalized epilepsy in adult and elderly patients].

Thirty-six patients with idiopathic generalized epilepsy (IGE) aged 35-67 years (mean age 44.4 +/- 10.6 years, 14 male, 22 female) have been studied. Ten of them were over 50 years, 8 had a diagnosis of juvenile absence epilepsy (JAE); 12--juvenile myoclonic epilepsy (JME) and 16--awakening epilepsy (AE), IGE with isolated generalized tonic-clonic seizures. The control group included 80 patients with IGE (22 male, 58 female aged 15-34 years, mean age 20.5 +/- 4.3 years), 29 of them being affected with JAE, 28--JME, 23--AE. Elderly patients with IGE experienced difficulties in the control over absences, myoclonic seizures and generalized seizures. In this group, the seizures-free cases were rare. The results suggest worse clinical prognosis of IGE for elderly patients as compared with young ones.

Adolescent↗
PubMed2002

Prolactin-releasing peptide (PrRP) promotes awakening and suppresses absence seizures.

Prolactin releasing peptide (PrRP) is a recently identified neuropeptide that stimulates prolactin release from pituitary cells. The presence of its receptor outside the hypothalamic-pituitary axis suggests that it may have other functions. We present here evidence that PrRP can modulate the activity of the reticular thalamic nucleus, a brain region with prominent PrRP receptor expression that is critical for sleep regulation and the formation of non-convulsive absence seizures. Intracerebroventricular injection of PrRP (1-10 nmol) into sleeping animals significantly suppresses sleep oscillations and promotes rapid and prolonged awakening. Higher concentrations of PrRP (10-100 nmol) similarly suppress spike wave discharges seen during absence seizures in genetic absence epilepsy rats from Strasbourg, an animal model for this disorder. In concordance with these findings, PrRP suppressed evoked oscillatory burst activity in reticular thalamic slices in vitro. These results indicate that PrRP modulates reticular thalamic function and that activation of its receptor provides a new target for therapies directed at sleep disorders and absence seizures.

Action Potentials↗
PubMedDate not supplied

Lamotrigine in treatment of 120 children with epilepsy.

One hundred twenty children aged 10 months to 16 years 9 months were included in three studies with lamotrigine (LTG): a single-blind study (n = 60), a pharmacokinetic study (n = 23), and a compassionate group (n = 37). At 3 months, 11 patients had become seizure-free and 34 had > 50% decrease in seizure frequency. The best results involved absence epilepsy, Lennox-Gastaut syndrome (LGS), and other symptomatic generalized epilepsy. Forty-two patients were followed > 1 year, 22 for a mean of 2.2 years, and there was no significant increase in seizure frequency as compared with 3-month follow-up. Fourteen patients became seizure-free for > 6 months; all except 1 had generalized epilepsy. For 12 patients, treatment could be reduced to monotherapy, but for those with valproate (VPA) comedication LTG dosage had to be increased; 25% of patients with VPA monotherapy exhibited skin rash, appearing 3-18 days after starting LTG. For 4 patients, LTG could be reintroduced after VPA was withdrawn. Ten patients had ataxia and/or drowsiness and 2 had vomiting. For all other patients, tolerance was excellent.

Adolescent↗
PubMed2004

Synaptology of the rostral reticular thalamic nucleus of absence epileptic WAG/Rij rats.

The adult WAG/Rij rat is a well-established animal model for human absence epilepsy characterized by the presence of spike-wave discharges (SWDs). The pacemaking activity of the rostral reticular thalamic nucleus (rRTN) has been demonstrated to be essential for SWD maintenance. We investigated if SWD maintenance can be related to the synaptic organization of the rRTN, by studying the ultrastructure of the rRTN of absence epileptic WAG/Rij rats in comparison with that of non-epileptic, age-matched ACI control rats. In WAG/Rij rats, D-, L- and F-type terminals constitute the synaptic organization of the rRTN. D-type synapses, especially axo-dendritic ones, occur frequently. L- and F-type terminals are common but less frequent than D-type terminals. Semi-quantitative observations indicate that all terminal types are present on different parts of the postsynaptic neuron, but in different numbers: they are frequent on dendrites, common on somata and axons, and occur occasionally on dendritic spines. In addition, occasionally an F-type terminal was observed on the axon hillock. The three terminal types are also involved in multiple synaptic configurations, convergent as well as divergent, with dendrites, somata, axon hillocks and axons as postsynaptic structures. Convergent synaptic configurations outnumber divergent ones. The synaptic organization of the rRTN of the non-epileptic ACI rat appears to be very similar to that of the epileptic WAG/Rij rat. This indicates that SWD maintenance in the WAG/Rij rat does not depend on a different synaptic organization of the rRTN.

Animals↗
PubMed2003

Levetiracetam: preliminary efficacy in generalized seizures.

Levetiracetam is a novel antiepileptic drug (AED) with proven efficacy against partial seizures, but there is limited information about its effectiveness against generalized seizures. In animal models, levetiracetam protects against seizures in audiogenic susceptible rodents, and it is effective in the Genetic Absence Epilepsy Rat from Strasbourg, a model of absence seizures. In these models, levetiracetam has a therapeutic index that is higher than those of other AEDs. A number of small open-label studies suggest that levetiracetam reduces seizure frequency in patients with generalized seizures, including primarily generalized seizures and myoclonic seizures. Case reports provide additional information regarding the potential efficacy of levetiracetam in postanoxic, post-encephalitic and progressive myoclonus. Although random-ized controlled studies of patients with generalized seizures have not yet been conducted, on the basis of available information, levetiracetam may be prom-ising in the treatment of generalized seizures.

Animals↗