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At least 19 recordsLinked to original sources
PubMed1990

Gene mapping in the idiopathic generalized epilepsies: juvenile myoclonic epilepsy, childhood absence epilepsy, epilepsy with grand mal seizures, and early childhood myoclonic epilepsy.

Idiopathic generalized epilepsies, i.e., juvenile myoclonic epilepsy (JME), childhood absence epilepsy, and epilepsy with grand mal [generalized tonic-clonic seizures (GTCS)], are the most common genetic epilepsies. Linkage studies using Bf, HLA serologic, and DNA markers by three independent investigators, one from Los Angeles and two from Berlin, have localized the JME locus to the short arm of chromosome 6 (6p). Because members of the same JME family have the same JME phenotype of childhood absence epilepsy, epilepsy with grand mal (GTCS) seizures, or early childhood myoclonic epilepsy (ECME), our observations give evidence for a single-locus etiology in 6p for JME and for at least some of the childhood absence seizures, epilepsy with grand mal (GTCS) seizures, and ECME. Studies should now address whether locus heterogeneity exists within childhood absence epilepsy, epilepsy with grand mal (GTCS) seizures, or ECME. Markers linked to JME (Bf, HLA serologic, and DNA markers in the DQ region) can be used to resolve etiologic heterogeneity. Using such markers, both linked and unlinked forms of phenotypes that are clinically indistinguishable may be detected and provide evidence for etiologic heterogeneity. Studies should also concentrate on narrowing the JME locus to 2 to 3 cm by screening families with recombinant events using RFLPs, candidate genes, and new expressed sequences on chromosome 6.

Adolescent↗
PubMed1991

Epidemiology of absence epilepsy. II. Typical absences in children with encephalopathies.

A population-based study of absence epilepsy in Swedish children, aged 0-15 years, comprised cases selected on the basis of EEG criteria. Absence epilepsy was found in 119 of the 134 children with 3 Hz spike-and-wave discharges, and 12 of these 119 (10.1%) had typical absences in addition to other generalized seizures and slow irregular spike-and-wave activity on the EEG. The mean annual incidence of this type of absence epilepsy was 0.7/100,000. The median age at onset of absences was 6 years. Eight of the 12 patients had neurological abnormalities and/or severe mental retardation. The patients constitute a heterogeneous group of encephalopathies. They may have a genetic predisposition for absence epilepsy, causing it to appear during the course of a more severe, encephalopathy related, type of epilepsy.

Adolescent↗
PubMed1991

Epidemiology of absence epilepsy. III. Clinical aspects.

Absence epilepsy was studied in a Swedish population, aged 0-15 years, in 1978-1982. Cases were selected by electroencephalographic criteria. In the 134 children with 3 Hz spike-and-wave discharges, 97 (72.4%) had absences alone or in combination with generalized tonic-clonic seizures (grand mal): 56 had absences alone, 31 absences followed by grand mal, and 10 started with initial grand mal. Two distinct groups could be discerned: 1) childhood absence epilepsy: onset before the age of 12, with a quick response to therapy, little or no risk of grand mal, and a high remission rate; 2) juvenile absence epilepsy: onset at the age of 12 or later, a very high risk of grand mal, and usually a good response to therapy, but a high risk of relapses at withdrawal. This classification of absence epilepsy into subgroups may be useful for prognostic guidelines.

Adolescent↗
PubMed1991

Are rats with genetic absence epilepsy behaviorally impaired?

Absence seizures in humans are characterized by unresponsiveness to external stimuli and inactivity. However, in typical generalized non-convulsive epilepsy in children, intellectual capacities are considered to be normal. Wistar rats from an inbred strain with spontaneous absence-like seizures were compared with rats from the outbred control strain in various behavioral tasks in order to detect possible impairments related either to the absence epilepsy or to occurrence of spike and wave discharges (SWD). Spontaneous circadian locomotion, exploratory activity in an open field, social interactions with an unfamiliar conspecific and mouse killing behavior were similar in both strains. Avoidance learning in a shuttle box or food reinforced learning in a Skinner test were unimpaired or even improved in epileptic rats. During performance of a learned task either in the Skinner box or in a conditioned sound-bar pressing task, SWD were suppressed in epileptic rats as long as they were working for reinforcement. SWD reappeared when the motivation to perform the task had declined: unresponsiveness to a conditioned stimulus was then observed during SWD. These data are in agreement with observations commonly described in children with typical genetic absence epilepsy.

Aggression↗
PubMed1992

Cortical and thalamic lesions in rats with genetic absence epilepsy.

In generalized, non-convulsive, absence epilepsy, spike-and-wave discharges (SWD) are recorded in both the cortex and the thalamus. The effect of various cortical and thalamic lesions on the occurrence of spontaneous SWD was examined in rats from a strain with genetic absence epilepsy. Cortical ablations suppressed SWD recorded in the thalamus. KCl induced unilateral cortical spreading depression and transiently suppressed SWD in the ipsilateral cortex and thalamus; SWD recovered simultaneously in both structures. Bilateral thalamic lesions of the anterior nuclei, the ventromedial nuclei, the posterior area, or lesion of the midline nuclei did not suppress cortical SWD. However, large lesions of the lateral thalamus, including the specific relay and reticular nuclei, definitely suppressed ipsilateral SWD, and pentylenetetrazol, THIP or gammabutyrolactone failed to restore the cortical SWD. These results demonstrate that the neocortex and the specific thalamic nuclei are both necessarily involved in the generation of SWD in absence epilepsy.

Action Potentials↗
PubMed1991

Circadian rhythm of regular spike-wave discharges in childhood absence epilepsy.

Four girls with childhood absence epilepsy with several seizures every day were investigated using an ambulatory cassette EEG. Recordings were started at about 6 pm, and were run continuously for about 22 hours. We studied only the regular and symmetrical 3 Hz spike-wave discharges of at least 5 seconds duration, which are quite similar to or identical with those found in the clinical seizures. Regular spike-wave discharges occurred frequently during wakefulness in 2 cases and during sleep in the other 2 cases: in the latter, they occurred rarely during wakefulness. During wakefulness, we did not find a special time zone in which regular spike-wave discharges were facilitated; during nocturnal sleep, however, they were concentrated in the last third. The rate of regular spike-wave discharges per hour was the highest during stage 1, low during stages 2 and REM, and zero during stage 3 + 4. Average duration of regular spike-wave discharges was the longest during wakefulness in most cases, and shortest during stage 2 in all the cases.

Child↗
PubMed1991

Anticonvulsant and sleep-waking influences of riluzole in a rat model of absence epilepsy.

Six WAG/Rij rats, an animal model of human absence epilepsy, were injected intraperitoneally with riluzole. At 4 mg/kg, riluzole decreased the number, mean duration and spike-frequency of the spontaneously occurring discharges for 3 h. Riluzole also increased slow wave sleep at the expense of waking. As riluzole at 3 mg/kg decreased the number and spike-frequency of the discharges without inducing a sedative effect, this compound could be of therapeutic interest in human absence epilepsy.

Animals↗
PubMed1992

Genetic absence epilepsy in rats from Strasbourg--a review.

We have selected a strain of rats and designated it the Genetic Absence Epilepsy Rat from Strasbourg (GAERS). In this strain, 100% of the animals present recurrent generalized non-convulsive seizures characterized by bilateral and synchronous spike-and-wave discharges accompanied with behavioural arrest, staring and sometimes twitching of the vibrissae. Spontaneous SWD (7-11 cps, 300-1,000 microV, 0.5-75 sec) start and end abruptly on a normal background EEG. They usually occur at a mean frequency of 1.5 per min when the animals are in a state of quiet wakefulness. Drugs effective against absence seizures in humans (ethosuccimide, trimethadione, valproate, benzodiazepines) suppress the SWD dose-dependently, whereas drugs specific for convulsive or focal seizures (carbamazepine, phenytoin) are ineffective. SWD are increased by epileptogenic drugs inducing petit mal-like seizures, such as pentylenetetrazol, gamma-hydroxybutyrate, THIP and penicillin. Depth EEG recordings and lesion experiments show that SWD in GAERs depend on cortical and thalamic structures with a possible rhythmic triggering by the lateral thalamus. Most neurotransmitters are involved in the control of SWD (dopamine, noradrenaline, NMDA, acetylcholine), but GABA and gamma-hydroxybutyrate (GHB) seem to play a critical role. SWD are genetically determined with an autosomal dominant inheritance. The variable expression of SWD in offsprings from GAERS x control reciprocal crosses may be due to the existence of multiple genes. Neurophysiological, behavioural, pharmacological and genetic studies demonstrate that spontaneous SWD in GAERS fulfill all the requirements for an experimental model of absence epilepsy. As the mechanisms underlying absence epilepsy in humans are still unknown, the analysis of the genetic thalamocortical dysfunction in GAERS may be fruitful in investigations of the pathogenesis of generalized non-convulsive seizures.

Action Potentials↗
PubMed1992

Effect of add-on amantadine therapy for refractory absence epilepsy.

Amantadine hydrochloride was administered as an add-on drug to four children with refractory absence epilepsy, resulting in complete resolution of absence episodes within 1 week. All patients remained free of symptoms for 27 to 36 months without adverse effects related to this drug. An attempt to discontinue the use of this medication in three children resulted in a prompt relapse. The suggestion that amantadine may be an effective drug in the treatment of refractory absence epilepsy, should be tested in a double-blind, controlled study.

Amantadine↗
PubMed1992

Genetic models of absence epilepsy, with emphasis on the WAG/Rij strain of rats.

In this review, the main characteristics of genetic models of absence epilepsy, in particular with respect to WAG/Rij rats, are presented. Genetic models are important and relevant, since evidence exists that these models mimic spontaneously occurring human epilepsy more than models in which epilepsy is artificially induced. Genetic models can be divided into models in which seizures are elicited and into those in which epilepsy appears without any sensory stimulation. The majority of genetic models show that absence type of epilepsy; during the last few years, we and others have noticed that rats of various strains exhibit spontaneously occurring spike-wave discharges in the EEG. Among the strains highly affected is the WAG/Rij strain, which is a fully inbred strain. Individuals are homozygous and because of this property, genetic studies are meaningful. Electrophysiological studies have indicated that abnormal discharges in the cortical EEG are generalized and that the hippocampus is not involved. Parts of the thalamus, together with the thalamic reticular nucleus, apparently act as a pacemaker for the abnormal discharges. There is a circadian modulation in the number of spike-wave discharges. Discharges mainly occur during intermediate levels of vigilance such as passive wakefulness and light slow-wave sleep and at transitions of sleep states. Pharmacological studies with clinically effective antiepileptic drugs have shown a close agreement in seizure response between man and rat. Studies with new compounds have emphasized the role of the GABAergic and glutamatergic system in this type of epilepsy. Particularly striking is the role of the GABAergic system. GABA agonists enhance and GABA antagonists reduce the occurrence of spike-wave discharges, which deviates from the effects of GABAergic drugs in non-convulsive epilepsy. Even more striking is the role of the benzodiazepines, generally seen as GABA agonists; these drugs do not act as such in absence epilepsy since they reduce spike-wave discharges. Also good evidence for an involvement of other neurotransmitters such as noradrenaline, dopamine and opioid peptides exists in absence epilepsy. Genetic data obtained from the WAG/Rij model for absence epilepsy show a relatively simple pattern of inheritance with one gene determining whether an individual is epileptic or not, and with other genes regulating the number and duration of seizures. This is in good agreement with the more restricted human data. Cognitive studies have shown two important features of epilepsy in the WAG/Rij strain: modulation of the number of spike-wave discharges by mental or physical activity and on the other hand, the disruption of cognitive activity by spike-wave discharges.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Genetics of absence epilepsy in rats.

All rats of the WAG inbred strain show electrophysiological and behavioral phenomena reminiscent of human absence epilepsy. To study the genetic architecture of this kind of epilepsy, WAG rats were cross bred with inbred ACI rats which show no signs of epilepsy. Number and duration of spike-wave discharges per hour were determined from 24-h recordings of cortical EEG in parental strains and reciprocal F1 hybrids. All hybrids showed spike-wave discharges, indicating complete dominance for occurrence, but different genetic backgrounds were suggested for number and duration of the phenomena. These results imply that more than one gene is involved in absence epilepsy. Some genes determine the occurrence, while others may manipulate the actual number and duration of the epileptic phenomena.

Animals↗
PubMed1991

Absence epilepsy and the level of vigilance in rats of the WAG/Rij strain.

In man, a relationship exists between sleep-wake states and absence epilepsy. During wakefulness, spike-wave discharges predominantly occur when the level of vigilance is not high, while during sleep they have a preference to occur during slow-wave sleep. During this latter type of sleep, spike-wave discharges prevail in periods where slow-wave sleep is light. In a series of experiments, the WAG/Rij rat model for absence epilepsy was characterized with respect to the relationships between the level of vigilance, sleep-wake states and the occurrence of spike-wave discharges. In the first experiment, continuous recordings were made for a period of 48 h and a clear circadian rhythm was established for the number of spike-wave discharges. A maximum appeared during the middle of the dark period of the rat, whereas a minimum was detected directly after the onset of the light period, the time period during which deep slow-wave sleep predominates. The relationship of spike-wave discharges with states of vigilance was elaborated in a second study. Spike-wave discharges were mainly found during light slow-wave sleep, during passive wakefulness and in transition phases from sleep to wakefulness. During REM sleep no spike-wave discharges were found. In the last three experiments, the level of alertness was enhanced by various procedures as photostimulation, a learning task and deprivation of REM sleep. In all cases, an increase of alertness decreased the amount of epilepsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Physical exercise and voluntary hyperventilation in childhood absence epilepsy.

The aim of this study was to compare the effects of a physical exercise test and of voluntary hyperventilation between controls and children with absence epilepsy. Eighteen children (6 controls and 12 epileptics) were studied during rest (R), a maximal physical exercise test (15 min; PE), recovery (REC) and voluntary hyperventilation (3 min; VHPV). EEG and ECG were recorded during the experiment; respiratory parameters were measured to quantify PE; plasma levels of pH, lactate, pyruvate, glucose and antiepileptic drugs were determined. A decrease in the number of absences was observed during PE whereas an increase was observed during VHPV. We found significant positive correlations between the number of children with absences, the total number of absences for each state, frequency of absences per minute and the corresponding mean plasma pH, which demonstrate that the lower the pH is, the fewer absences occur. On the other hand, there was no relationship between the number of absences and the values of other parameters. Relations between variations of the plasma value of the pH, and thus the probable cerebral value of pH, and neuronal excitability are discussed. Our results indicate that children who suffer absence epilepsy should not be discouraged from sport practice.

Adolescent↗
PubMed1990

Pseudoseizures caused by hyperventilation resembling absence epilepsy.

During the 4-year period, 1982-1986, 18 patients presented to the Children's Hospital, Camperdown, Sydney, with the following features: (1) Recurrent "absences" clinically indistinguishable from childhood absence epilepsy, (2) Normal clinical examination, (3) Electroencephalogram (EEG) demonstrating normal waking background and sleep activity. On hyperventilation, "absences" occurred, characterized on EEG by a marked build-up of paroxysmal slow-wave activity unassociated with evidence of epileptic activity. We designate these attacks "pseudoseizures caused by hyperventilation resembling absence epilepsy." Individual cases demonstrated a variety of other symptoms consistent with the hyperventilation syndrome. There was an identifiable environmental stress in 13 of the 18 cases. Follow-up of 13 patients after a mean period of 20 months revealed that only two children continued to have occasional absences, associated with a clear history of breathing up when upset. Treatment did not influence outcome. On repeat hyperventilation with EEG and respiratory monitoring, five of the 13 had pseudoseizures. There was no indication that susceptibility to these episodes was associated with an abnormal CO2 response. It is postulated that the occurrence of pseudoseizures is related to cerebrovascular immaturity and an excessive vasoconstrictor response to a given level of CO2.

Adolescent↗