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PubMed2001

Age dependent changes in some immune system parameters and GFAP immunoreactivity in genetically absence epileptic rats.

The present study evaluated the contribution of some peripheral immunological parameters and GFAP immunoreactivity at different ontogenic stages of non convulsive absence epilepsy in WAG/Rij rats. For this, 2- and 6-month-old WAG/Rij rats, and the aged-matched control Wistar-albino rats were used. After collecting blood samples from all rats, the CD3 + (T cells), CD4 + (T helper), CD8 + (T cytotoxic), CD19 + (B cells) and CD25 + (IL-2 receptor, active T cell) cell ratios were determined by indirect immunofluorescence method and, serum IgG, IgA, IgM levels were evaluated by using rat radial immunodiffusion plates. After decapitation, brains were dissected and, GFAP staining was evaluated in the areas of caudate nucleus, thalamus, hippocampus, amygdala and cerebellum by immunohistochemistry. CD3 + cells and IgM levels increased with age in WAG/Rij rats. However, GFAP + astrocytes were decreased with age in caudate nucleus, thalamus, amygdala, and cerebellum of WAG/Rij rats. In the genetically absence epileptic rats, the humoral immunity was found to be affected more and activated by age. Additionally, astrocytes in thalamus and caudate nucleus that are the most important areas in the pathogenesis of absence epilepsy, were found to be decreased with age in WAG/Rij rats. From the results, it can be concluded that peripheral immunological parameters together with astrocytic activity may participate in the etiopathogenesis of absence epilepsy.

Age Factors↗
PubMed1999

Association analysis of a regulatory promoter polymorphism of the PAX-6 gene with idiopathic generalized epilepsy.

The PAX-6 gene is a member of the paired-box-containing (PAX) gene family, encoding a transcriptional activator, that plays an important role in the development of the central nervous system. The present association study tested the hypothesis that length variation of a novel regulatory dinucleotide repeat polymorphism in the promoter region of the PAX-6 gene (PAX-6 gene-linked polymorphic region, PAX-6LPR) confers susceptibility to the epileptogenesis of common subtypes of idiopathic generalized epilepsy (IGE). The repeat length of the regulatory dinucleotide repeat polymorphism was assessed in 354 German control subjects and 125 German IGE patients, comprising 70 patients with juvenile myoclonic epilepsy (JME) and 55 patients with an idiopathic absence epilepsy (IAE). The allelic distribution of the PAX-6LPR did not deviate significantly between the controls and the IGE patients (Wilcoxon Rank-Sum test: P > 0.76), or both subgroups of either JME patients (P > 0.78) or IAE patients (P > 0.87). Our results do not provide evidence that length variation of the polymorphic dinucleotide sequence in the PAX-6LPR contributes a frequent and relevant effect to the pathogenesis of common subtypes of IGE.

Alleles↗
PubMed2004

Worsening of seizures by oxcarbazepine in juvenile idiopathic generalized epilepsies.

PURPOSE: Several studies have shown that carbamazepine (CBZ) may aggravate idiopathic generalized epilepsy (IGE). Oxcarbazepine (OXC) is a new drug chemically related to CBZ. We report six cases of juvenile IGE with a clear aggravation by OXC. METHODS: We retrospectively studied all patients with IGE first referred to our epilepsy department between January 2001 and June 2003 and treated with OXC. RESULTS: During this period, six patients were identified. All had an aggravation of their epilepsy in both clinical and EEG activities. OXC had been used because of an incorrect diagnosis of focal epilepsy or generalized tonic-clonic seizures (GTCSs) of undetermined origin (no syndromic classification of the epilepsy). Before OXC, only one patient had experienced a worsening of seizures with an inadequate drug (CBZ). Four had juvenile myoclonic epilepsy, one had juvenile absence epilepsy, and one had IGE that could not be classified into a precise syndrome. OXC (dosage range, 300-1,200 mg/day) was used in monotherapy in all of them except for one patient. Aggravation consisted of a clear aggravation of myoclonic jerks (five cases) or de novo myoclonic jerks (one case). Three patients had exacerbation of absence seizures. One patient had worsened dramatically and had absence status, and one had de novo absences after OXC treatment. The effects of OXC on GTCSs were less dramatic, with no worsening in frequency in three and a slight increase in three. CONCLUSIONS: OXC can be added to the list of antiepileptic drugs that can exacerbate myoclonic and absence seizures in IGE.

Acute Disease↗
PubMed2005

Amino acid levels in some lethargic mouse brain areas before and after pentylenetetrazole kindling.

Genetic animal models have contributed significantly to our understanding of epilepsy causes. Lethargic mice are considered a valid model of absence epilepsy, which have been shown to possess behavioral, electrographic and pharmacological profiles similar to those of humans with absence epilepsies. Single gene mutations that comprise the beta4 subunit of voltage-sensitive Ca2+ channels underlie the spontaneous discharges of the absence, non-convulsive seizures of lethargic mice. There are no available data concerning how the mutant channels actually behave at terminals in response to chemical activation by subconvulsant stimulation with pentylenetetrazole. In this study, we found no significant difference in the convulsive dose 50 between lethargic and control mice. Lethargic mice showed a more rapid development of kindling to pentylenetetrazole than control animals. No significant differences were observed between the groups of mice rechallenged with pentylenetetrazole 30 or 60 days after the end of the chronic treatment. Marked differences in brain amino acid levels were found between the two strains of mice in basal conditions and after kindling. In conclusion, our results indicate that lethargic mice show a range of biochemical and behavioral changes, correlated in particular with a higher susceptibility to develop kindled seizures.

Amino Acids↗
PubMed1989

[A case of epilepsy with myoclonoic absences].

A case of epilepsy with myoclonic absences is reported. A boy, 3 years and 8 months old, had the first attack at the age of 1 year and 8 months. He was mentally retarded, but had no evidence of organic brain damages. He had been said to have "absence" at another hospital for 2 years until he was referred to our hospital. The attack was characterized clinically by sudden loss of consciousness accompanied with rhythmical massive myoclonias. The ictal EEGs showed synchronous diffuse 3 c/s spike-wave discharges. There was a strict and constant relation between spike-wave discharges and the myoclonia. The polygraphy recording (EEG and EMG of various muscles) was very helpful for the diagnosis of epilepsy with myoclonic absences. We think that epilepsy with myoclonic absences should be considered in any case of "absence" with concomitant 3 c/s spike-wave discharges which is resistant to appropriate treatment, or is accompanied with mental retardation.

Child, Preschool↗
PubMed1994

Opiate receptors in idiopathic generalised epilepsy measured with [11C]diprenorphine and positron emission tomography.

The neurochemical basis of absence seizures is uncertain. A previous PET study has provided evidence for release of endogenous opioids from cerebral cortex at the time of absence seizures, but it is has not yet been established whether there is an abnormality of opiate receptor numbers interictally. In the present study, the non-specific opiate receptor ligand, [11C]diprenorphine, was used to measure cerebral opiate receptors interictally in patients with childhood and juvenile absence epilepsy. Eight patients and eight normal controls had a single scan after a high specific activity injection of [11C]diprenorphine. The cerebral volume of distribution (Vd) of [11C]diprenorphine relative to plasma was calculated on a pixel-by-pixel basis. There were no significant differences in [11C]diprenorphine Vd between patients and control subjects in either cortex or thalamus, structures thought to be involved in the pathogenesis of absence seizures. The results suggest that there is no overall abnormality of opioid receptors in patients with childhood and juvenile absence epilepsy. Studies with specific ligands may provide information about the different receptor subtypes.

Adult↗
PubMed2006

A gamma 2(R43Q) mutation, linked to epilepsy in humans, alters GABAA receptor assembly and modifies subunit composition on the cell surface.

Genetic defects leading to epilepsy have been identified in gamma2 GABA(A) receptor subunit. A gamma2(R43Q) substitution is linked to childhood absence epilepsy and febrile seizure, and a gamma2(K289M) mutation is associated with generalized epilepsy with febrile seizures plus. To understand the effect of these mutations, surface targeting of GABA(A) receptors was analyzed by subunit-specific immunofluorescent labeling of living cells. We first transfected hippocampal neurons in culture with recombinant gamma2 constructs and showed that the gamma 2(R43Q) mutation prevented surface expression of the subunit, unlike gamma2(K289M) substitution. Several gamma2-subunit constructs, bearing point mutations within the Arg-43 domain, were expressed in COS-7 cells with alpha3- and beta3-subunits. R43Q and R43A substitutions dramatically reduced surface expression of the gamma2-subunit, whereas R43K, P44A, and D39A substitutions had a lesser, but still significant, impact and K289M substitution had no effect. Whereas the mutant gamma2(R43Q) was retained within intracellular compartments, alphabeta complexes were still targeted at the cell membrane. Coimmunoprecipitation experiments showed that gamma2(R43Q) was able to associate with alpha3- or beta3-subunits, although the stoichiometry of the complex with alpha3 was altered. Our data show that gamma2(R43Q) is not a dominant negative and that the mutation leads to a modification of GABA(A) receptor subunit composition on the cell surface that impairs the synaptic targeting in neurons. This study reveals an involvement of the gamma2-Arg-43 domain in the control of receptor assembly that may be relevant to the effect of the heterozygous gamma2(R43Q) mutation leading to childhood absence epilepsy and febrile seizure.

Amino Acid Substitution↗
PubMedDate not supplied

Carbamazepine-exacerbated epilepsy in children and adolescents.

Forty-nine children and adolescents whose seizures reportedly worsened while receiving carbamazepine (CBZ) were studied retrospectively. Twenty-six patients met criteria for excellent documentation of carbamazepine-exacerbated seizures. Four epileptic syndromes were particularly affected: childhood absence epilepsy; focal symptomatic, frontal lobe epilepsy; Lennox-Gastaut syndrome; and severe myoclonic epilepsy of infancy. Eight of the 26 patients developed new-onset absence seizures and three patients with established absence epilepsy experienced absence status. Other seizure types, including atonic, tonic-clonic, and myoclonic, developed in eight patients treated with CBZ, and new generalized spike-and-wave discharges were observed in electroencephalograms of nine patients. CBZ is a widely used, effective antiepileptic drug, particularly for partial or partial complex seizures; however, if uncontrolled, generalized seizures occur after CBZ is prescribed for children or adolescents with absence or mixed seizures, a trial of CBZ discontinuation is warranted. The data reported here do not permit calculation of the incidence of this phenomenon.

Adolescent↗
PubMed1999

Primary ciliary dyskinesia syndrome and primary generalised epilepsy.

A child with primary ciliary dyskinesia syndrome (PCDS) developed primary generalised epilepsy (PGE). The PGE had characteristics of both childhood absence epilepsy (CAE) and juvenile myoclonic epilepsy (JME). The association of PCDS and PGE has not previously been recorded.

Adult↗
PubMed2006

[Typical absence seizure: epidemiological and clinical characteristics and outcome].

OBJECTIVE: To analyze the epidemiological and clinical characteristics and outcome of absence epilepsy in the pediatric age group with the aim of facilitating its diagnosis in clinical practice. PATIENTS AND METHODS: Information on epidemiological and clinical characteristics, complementary investigations, and outcome was collected from the medical records of 51 children with absence epilepsy. The criteria defined by the International League Against Epilepsy (ILAE) were used in the diagnosis. RESULTS: Fifty-one percent of the patients had simple absence seizures and 49% had complex absence seizures. A total of 70.6% of the patients were school-aged children and the prevalence was greater among girls (72.5%). The mean age at onset was 7.5 +/- 2.7 years. In 80%, there were multiple seizures per day with a mean duration of 12 seconds. School performance was impaired in 19.6%. Ictal electroencephalogram showed generalized 3 Hz spike and slow wave complexes in 84.3%. Hyperventilation was positive in 98%, and intermittent photic stimulation was positive in 15.7%. The seizures were controlled by sodium valproate (mean dosage: 26 mg/kg/day) in 84.3% of the patients. In 43 patients antiepileptic drugs were withdrawn (mean duration: 3.3 +/- 0.6 years) but 3 patients relapsed. CONCLUSIONS: Typical absences are a common type of epilepsy in the pediatric age group and generally begin in school-aged children. Absences may be difficult to detect and can impair learning. Treatment response is excellent. Nevertheless, because absences may be the first manifestation of severe forms of epilepsy syndromes, strict follow-up of these patients is essential.

Child↗
PubMedDate not supplied

[The cortico-thalamic theory for generalised spike-wave discharges].

The origin of generalized absence epilepsy is still not known. In the last century, four theories have dominated the debate about the origin of the bilateral synchronous generalized spike-wave discharges associated with absence seizures: the "centrencephalic" theory [Penfield and Jasper], the "cortical" [Bancaud, Niedermeyer, Luders], the "cortico-reticular" theory [Gloor, Kostop[oulos, Avoli] and the "thalamic clock" theory [Buzsaki]. There is now some evidence that absence epilepsy, as studied in the WAG/Rij model, is a corticothalamic type of epilepsy. A new hypothesis is proposed which suggests that a cortical focus in the somatosensory cortex is driving the widespread corticothalamic networks during spontaneous absence seizures. This modern theory was given the name "hot spot' theory" [Meeren et al., 2002]. According to the present view three brain structures are critically involved and their integrity seems a minimal and sufficient condition for the occurrence of spike-wave discharges. Firstly, the reticular thalamic nucleus is involved and most likely its rostral pole. Secondly, the thalamocortical relay cells in the ventrobasal complex play a role and, thirdly and most importantly, the cerebral cortex with its epileptic zone. The zone in which the epileptic focus seems to be localised is located on the somato-sensory cortex, and more precisely in the area on which the peri-oral region including the upper lip, projects.

Animals↗
PubMedDate not supplied

[Idiopathic generalized epileptic syndromes of children].

INTRODUCTION: The idiopathic generalized epilepsies of children form a neurobiological continuum which starts during the first years of life, until adolescence. In this group, infantile absence epilepsy may be considered to be the maximum expression of the idiopathic generalized epilepsies in this age group. Infantile absences have seen studied in animal models, in humans and genetically. DEVELOPMENT: We analyze the clinical and encephalographic characteristics of infantile absence epilepsies together with their prognosis and epidemiology. We also consider the palpebral myoclonias with absences and absences with perioral myoclonias. The generalized tonic-clonic seizures of childhood form an ill-defined epileptic syndrome, with very heterogeneous clinical and electroencephalographic characteristics. CONCLUSION: It seem important to be able to establish the precise diagnosis in these syndromes, since correct treatment depends on it.

Adolescent↗
PubMed1988

[Epilepsies in puberty and adolescence. Follow-up and drug therapy].

1. Puberty and adolescence mainly can have a bad effect on idiopathic generalized epilepsies. This can show up in the first onset of seizures in adolescence, e.g. as a form of idiopathic grand mal on awakening, juvenile absence epilepsy or juvenile myoclonic epilepsy (impulsive petit mal). Also, already diagnosed absence epilepsy can become worse, e.g. by recurring absence seizures or grand mal seizures or the new onset of grand mal on awakening. 2. Exogenous factors, like changing the time of sleeping and waking, lack of sleep and the abuse of alcohol, play an important role in these types of epilepsy. Cutting out these factors is just as important as the consequent drug treatment on a longterm basis. 3. Drug treatment of idiopathic generalized epilepsy will be done with valproate, barbiturates and ethosuximide. Regarding fatal complications of liver function, which are more frequent than previously thought of, valproate can be recommended as a drug of first choice, especially in early childhood and when a combination of drugs is used. 4. A very good effect of adolescence is seen in children with benign idiopathic focal epilepsy with a centro-temporal spike focus. Antiepileptic treatment with carbamazepine as an agent of first choice can be done less vigorously. 5. Menstruation usually only modifies but does not worsen the natural course of epilepsy. There is still no real therapeutical plan for this rare form of epilepsy. 6. It cannot be a general rule, not to change current medical treatment before or during puberty in order to avoid any worsening of seizures. A decision always has to be made regarding the form of epilepsy and the individual situation, which has to be discussed with the patient and perhaps his family.

Adolescent↗
PubMed2001

Epileptic seizures and sleep-wake rhythm.

The subjects were 25 children, including West syndrome, Lennox-Gastaut syndrome, childhood absence epilepsy (CAE) and localization-related epilepsies. Clinical seizures occurred only during waking state in 14 patients (including the cases of West syndrome, CAE and epilepsy with myoclonic absences (EMA)), only during sleeping state (especially during non-REM sleep in five patients, including the case of benign epilepsy with centrotemporal spike), and diffusely during waking and sleeping states in six patients (including the case of early infantile epileptic encephalopathy with suppression burst). These three types were observed in the cases of Lennox-Gastaut syndrome and localization-related epilepsies. Subclinical ictal discharges occurred during REM sleep in West syndrome, and during REM and non-REM sleep especially during non-REM sleep in CAE and EMA.

Brain↗
PubMed1990

Mapping of spontaneous spike and wave discharges in Wistar rats with genetic generalized non-convulsive epilepsy.

Electrical activity was recorded in different parts of the brain in Wistar rats from a strain with genetic generalized non-convulsive epilepsy (GNCE or absence epilepsy). Movable bipolar electrodes were lowered stereotaxically by 1 mm steps into the brain in immobilized animals. Spontaneous spike and wave discharges (SWD) of the largest amplitude were recorded in the cortex and in lateral nuclei of the thalamus where they appeared occasionally to precede. Smaller amplitude SWD were recorded in the striatum, hypothalamus, tegmentum and substantia nigra. No SWD were recorded in limbic structures. Partial limbic seizures induced by the introduction of the electrode did not interfere with occurrence of cortical SWD. These results confirm the primacy of thalamocortical involvement in SWD of GNCE. The absence of spread to limbic structures and the implication of a precisely limited substrate in GNCE accounts for the clinical and pharmacological specificity of this particular kind of epilepsy.

Animals↗
PubMed1994

The effects of chronic treatment with a calcium channel antagonist on two types of generalized epilepsies in rats.

Although calcium antagonists possess antiepileptic properties in various models of epilepsy, their role after chronic administration and in models for generalized absence epilepsy has not been studied. Twenty-four male Wistar rats, aged 84-94 weeks, were chronically provided with EEG electrodes. Two groups received dietary nimodipine (860 ppm) for 14 and 21 weeks, respectively, while a control group received the same rat chow without nimodipine. The EEG was recorded for 3 h to establish the effects of nimodipine on spike-wave discharges. Next, 50 mg/kg pentylenetetrazol (PTZ) was injected to establish the effects on convulsive epilepsy, and the EEG was recorded for 30 min. All animals had spontaneous spike-wave discharges (SWD), but there were no differences between the three groups. However, chronic nimodipine treatment had a significant effect on PTZ-induced seizures: the group that had been treated with nimodipine for 21 weeks showed significantly more and longer-lasting seizures than the control group. The facilitating effects of chronically administered of nimodipine on PTZ-induced seizures are striking and opposite to those reported in the literature. In a second study, nimodipine was administered acutely, but no effects of nimodipine on PTZ-induced epilepsy could be detected. It can be concluded that chronic dietary administration of a calcium antagonist induces different effects on PTZ-induced seizures than acute administration in aged Wistar rats with spontaneous occurring SWD.

Animals↗
PubMed2000

The role of the thalamus in vigilance and epileptogenic mechanisms.

OBJECTIVES: The most relevant results of studies on the anatomo-physiological substrate of the thalamic rhythmogenic mechanisms responsible for sleep spindles and spike-wave discharges are reviewed. METHODS: The reviewed experiments have been carried out in cats, rodents and other mammals with either in vivo or in vitro electrophysiological recording. RESULTS: The rhythmic bilateral and synchronous EEG activities underlying sleep spindles and spike-wave discharges have been found to be correlated with oscillatory patterns involving mutually interconnected cortical and thalamic neurons. These rhythmic patterns are generated in thalamic neurons when the membrane potential, which is modulated by aminergic and cholinergic systems, is set to a level where the low threshold calcium current is de-inactivated. The pacemaker structure responsible for the initiation of the thalamo-cortical oscillatory activities has been identified as the reticular thalamic nucleus, a GABAergic structure projecting exclusively to the other thalamic nuclei. Experiments carried out in GAERS (genetic absence epilepsy rat from Strasbourg) demonstrated in this rat model of inherited absence epilepsy an enhancement of the pacemaker properties of the thalamic nucleus, due to a genetically determined increase in the low threshold calcium current, which is responsible for the pathological synchronization underlying spike-wave discharges. CONCLUSIONS: Recent experiments confirm the longstanding hypothesis that spindles and spike-wave discharges share common mechanisms involving thalamo-cortical circuitry. Due to its unusual anatomic and functional organization the nucleus reticularis thalami plays a crucial role as pacemaker of these rhythmic EEG activities.

Animals↗
PubMed2001

Genome scan of idiopathic generalized epilepsy: evidence for major susceptibility gene and modifying genes influencing the seizure type.

Idiopathic generalized epilepsy (IGE) is a common, complex disease with an almost exclusively genetic etiology but with variable phenotypes. Clinically, IGE can be divided into different syndromes. Varying lines of evidence point to the involvement of several interacting genes in the etiology of IGE. We performed a genome scan in 91 families ascertained through a proband with adolescent-onset IGE. The IGEs included juvenile myoclonic epilepsy (JME), juvenile absence epilepsy (JAE), and epilepsy with generalized tonic clonic seizures (EGTCS). Our linkage results support an oligogenic model for IGE, with strong evidence for a locus common to most IGEs on chromosome 18 (lod score 4.4/5.2 multipoint/two-point) and other loci that may influence specific seizure phenotypes for different IGEs: a previously identified locus on chromosome 6 for JME (lod score 2.5/4.2), a locus on chromosome 8 influencing non-JME forms of IGE (lod score 3.8/2.5), and, more tentatively, two newly discovered loci for absence seizures on chromosome 5 (lod scores 3.8/2.8 and 3.4/1.9). Our data also suggest that the genetic classification of different forms of IGE is likely to cut across the clinical classification of these subforms of IGE. We hypothesize that interactions of different combinations of these loci produce the related heterogeneous phenotypes seen in IGE families.

Adolescent↗