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PubMed1994

Childhood absence epilepsy.

BACKGROUND: Childhood absence epilepsy (CAE) is a relatively rare form of idiopathic generalized epilepsy, occurring in previously normal children with a strong genetic predisposition. The annual incidence of CAE has been estimated at 6.3/100,000 to 8/100,000 children aged 0-15 years. METHODS: Medical and electroencephalographic records of 50 Chinese children with CAE were reviewed. RESULTS: There were 22 males and 28 females. The age of onset ranged from 3 to 12 years with a mean of 6.9 +/- 2.4 years. Six children (12%) had positive familial epileptic history and 11 patients (22%) had a past history of febrile convulsion. Electroencephalographically, there were posterior delta rhythm (6/50), frontocentral (1/50), and centrotemporal (1/50) spikes in addition to the characteristic 3 Hz spike and wave complex. All patients received regular or irregular treatment with valproate. Sixteen patients (32%) evolved to generalized tonic-clonic seizure (GTCS) with a mean of 2.1 +/- 1.6 years of lag from stopping valproate. The patients with GTCS had significant late onset of age, a longer active period, and longer treatment duration than those without GTCS (p < 0.01). There were significantly more patients with irregular treatment evolving to GTCS than those with regular treatment (p < 0.01). None of the patients with posterior delta rhythm evolved to GTCS. CONCLUSIONS: Regular treatment with valproate is the modality of choice in the management of CAE. Posterior delta rhythm seems to be a good prognostic factor electroencephalographically.

Child↗

PubMed1999

Epileptiform activity induced by 4-aminopyridine in entorhinal cortex hippocampal slices of rats with a genetically determined absence epilepsy (GAERS).

Patients with absence epilepsy frequently develop convulsions later in life. We were therefore interested whether tissue from rats with a genetic absence epilepsy is more prone to seizure generation than normal animals. We compared the epileptiform activities induced by 4-aminopyridine (4-AP) induced in hippocampal-entorhinal cortex slices from genetic absence epilepsy rats of Strasbourg (GAERS, age 6 months) in which absence seizures have been present for about 4 months and from control non epileptic rats (NE). 4-AP induced short recurrent discharges in area CA1 of rat hippocampus, seizure-like events and interictal discharges in the entorhinal cortex. The various epileptiform discharges did not differ between the two strains in amplitude, duration and frequency. However, the latency for induction of different epileptiform activities by 50 microM 4-AP was significantly shorter in GAERS (about 16 min) than in NE rats (about 25 min). We also analysed differences in evoked field potentials (fp) in hippocampal area CA1 before, during and after application of 4-AP. Before application of 4-AP, responses to stimulation of Schaffer collateral were smaller in GAERS than in NE rats. Paired pulse potentiation was significantly larger in GAERS than in NE rats. 4-AP in the bath augmented the size of the evoked field potentials and this increase was larger in GAERS than in NE rats. Our findings show a greater excitability of hippocampal area CA1 in GAERS rats and a greater ability to develop 4-AP-induced epileptiform activity in combined hippocampal-enthorhinal cortex slices in GAERS than in NE rats.

4-Aminopyridine↗

PubMed1998

Adaptive changes in the pharmacodynamics of midazolam in different experimental models of epilepsy: kindling, cortical stimulation and genetic absence epilepsy.

1. The objective of this investigation was to determine quantitatively whether experimental epilepsy is associated with a change in the pharmacodynamics of benzodiazepines in vivo. For that purpose the pharmacodynamics of midazolam were quantified by an integrated pharmacokinetic-pharmacodynamic approach in three different models of experimental epilepsy: amygdala kindling, cortical stimulation and genetic absence epilepsy. 2. The time course of the EEG effect was determined in conjunction with the decline of drug concentrations after intravenous administration of 10 mg kg(-1) midazolam. The pharmacokinetics of midazolam were most adequately described by a bi-exponential equation. No influence of epilepsy on the pharmacokinetics of midazolam was observed. 3. The increase in beta activity (11.5-30 Hz) of the EEG as derived by Fast Fourier Transformation analysis was used as pharmacodynamic endpoint. For each individual rat the increase in beta activity was directly related to the concentration in blood on the basis of the sigmoidal Emax pharmacodynamic model. In all three models a significant reduction in the maximal effect was observed, in amygdala kindling 28%, in the cortical stimulation model 49% and in genetic absence epilepsy 37%. No differences in the other pharmacodynamic parameters, E0 EC50,u and Hill factor, were observed. 4. It is inferred that in three different models of epilepsy there is a similar change in GABAergic functioning which is associated with a significant reduction in the intrinsic activity of midazolam in vivo. These models provide therefore a useful basis for further studies on the mechanism of epilepsy-induced changes in pharmacodynamics of anti-epileptic drugs.

Amygdala↗

PubMed1994

Absence epilepsy of early childhood--genetic aspects.

Clinical and EEG family data of 140 cases with early childhood epilepsy with absences are presented. The aim of the study was to evaluate, whether the occurrence of generalized tonic clonic seizures (GTCS) as a presenting symptom might correlate with family data, i.e. whether there are indications of heterogeneity. One hundred and forty cases were selected from the epilepsy family data base of the Neuropaediatric Department. The selection parameter was epilepsy with absences manifesting between the 1st and 5th year of age. The incidence of seizures was evaluated in siblings, parents and parents' siblings. EEG records were available from 103 parents and 106 siblings. The analysis supports the assumption of heterogeneity within early childhood absence epilepsy. Parents and their sibs of cases manifesting with GTCS had seizures twice as often than parents and their sibs in the non-GTCS group. In the affected relatives of the GTCS group early onset GTCS prevailed, whereas in the relatives of the non-GTCS group absences were found more frequently. The EEG of relatives showed elevated incidences of spikes and waves and photosensitivity in both groups, indicating common genetic factors. In parents of the non-GTCS group, however, EEG pathology was significantly more frequent than in parents of the GTCS group. Comparing EEG pathology in parents with seizure risk in siblings, evidence for maternal preponderance in transmission of the seizure liability was found. Mothers' EEG seems to be the best predictor of the seizure risk in probands' siblings.(ABSTRACT TRUNCATED AT 250 WORDS)

Age of Onset↗

PubMed1998

Epileptiform activity and changes in field potential responses induced by low [Mg2+]0 in a genetic rat model of absence epilepsy.

The genetic absence epilepsy rats of Strasbourg (GAERS) display alterations in cortical synaptic transmission possibly facilitating the generation of ictaform activity and the late development into convulsive epilepsy. We studied low Mg2+-induced epileptiform activities and their long term effects on field potentials (fp) evoked by paired pulse stimulation in hippocampal area CA1 (CA1), medial entorhinal cortex (EC) and frontal cortex (FC) in in-vitro-slice preparations from GAERS and control (NE) adult rats (6 months). Omitting Mg2+-ions from artificial cerebrospinal fluid (ACSF) caused recurrent short discharges (in CA1) and seizure-like events (in EC) in both GAERS and NE rats. Latency to onset of activity as well as discharge pattern, frequency and amplitude of such events did not differ between the two strains, neither in CA1 nor in EC. In the FC, however, epileptiform events occurred in NE rats, but not in GAERS. Field potentials in normal ACSF were similar in both strains in CA1 and FC, while they were smaller in the EC of GAERS. Low [Mg2+]0 caused long-term changes of fp only in area CA1 where the population spikes were depressed in GAERS and increased in NE rats. We concluded that susceptibility to low [Mg2+]0-induced epileptic activity in EC and hippocampal area CA1 is not higher in GAERS than in NE adult rats. However, some properties like synaptic coupling in EC and long-term changes in synaptic efficacy induced by epileptiform activity in CA1 differ from that in NE rats. Whether the particularities in GAERS may be related to kindling by absence epileptic activities will be studied in further experiments.

Animals↗

PubMed1985

Longterm follow-up of childhood epilepsy with absences. I. Epilepsy with absences at onset.

The purpose of the follow-up study was to determine whether modern therapy with ethosuximide and/or valproate with/without phenobarbitone and its derivatives improves the longterm prognosis of absence epilepsy as compared to formerly used treatments. The patient population consisted of 194 cases (88 boys, 106 girls) with spike wave epilepsy starting with absences. In each case the diagnosis was confirmed by clinical observation and the typical EEG pattern. Only those patients were included who could be followed beyond the eighteenth year of life (up to age 45). The sample includes also older patients diagnosed during the fifties, before the present standard therapy was available. Because of the heterogeneity of the material and its selection, the data obtained are not suited to make a general statement about the ultimate prognosis of absences. The results demonstrate the effectiveness of regularly applied modern treatment. 72 out of 194 patients (37%) manifested generalized tonic clonic seizures (gtcs) during the course: 20 of these patients showed only incidental generalized tonic clonic seizures, which were not dependent on therapy. In 52 cases gtcs appeared without relation to precipitating factors. None of these patients received regular standard therapy before onset of gtcs. In 31 cases absence statuses were observed. These patients did not have an unfavourable outcome provided the standard therapy was instituted early and consequently. A change from absence epilepsy into an epilepsy with complex partial seizures sensu strictiori could not be observed. At final investigation 42 of 194 patients still had seizures: 7 with absences, 35 with grand mal with or without absences.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

[Electro-clinical concordance for childhood absence epilepsy in monozygotic twins].

INTRODUCTION AND OBJECTIVE: The objective of the study was to analyze the EEG tracings during the seizures of two monozygotic twins, shown on molecular analysis, diagnosed as having infantile epilepsy with absences. The recordings are particularly interesting since the genotypes of the patients are identical. This allowed comparison between the similarities and differences in discharges so that they could be better defined. RESULTS: The 3 Hz spike and wave complexes were the same as the classical descriptions in typical absences. No 'W' spike and wave complexes morphology, discharge fragmentation or light induction of the discharges were observed. There was some differences in the duration of absences, which were much shorter in one twin girl. The duration of the seizures was variable, and sometimes similar to that described as characteristic in other types of generalized idiopathic epilepsies with absences. It would seem therefore that the duration of the seizure is not a criterion for differentiation between the different types of generalized idiopathic epilepsies. CONCLUSION: Concordance, both clinical and of seizure EEG recordings in our patients confirmed that there is a specific electroclinical phenotype in infantile epilepsy with absences, although individual variations may also occur.

Child↗

PubMed2001

Prognostic significance of failure of the initial antiepileptic drug in children with absence epilepsy.

PURPOSE: In children with childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE), to determine the impact of failure of initial antiepileptic drug (AED) for lack of efficacy in eventual seizure control and long-term remission of epilepsy. METHODS: Centralized EEG records for the province of Nova Scotia allowed identification of all children seen with CAE or JAE between 1977 and 1985. Information regarding success or failure of initial AED in fully controlling seizures and long-term seizure control and remission of epilepsy was collected by patient questionnaire and chart review. RESULTS: Eighty-six of 92 eligible patients were followed up (75 CAE, 11 JAE). Initial AED treatment was successful in 52 (60%) of 86. Success tended to be greater for valproate (VPA) than for other AEDs (p = 0.07), and lower if generalized tonic-clonic or myoclonic seizures coexisted (p < 0.004 and p < 0.03). Terminal remission was more likely if the initial AED was successful than if it had failed (69% vs. 41%; p < 0.02). Compared with those in whom the initial AED was successful, subjects whose initial AED had failed were more likely to progress to juvenile myoclonic epilepsy (JME) at last follow-up (32% vs. 10%; p < 0.02) and to develop intractable epilepsy (17% vs. 2%; p < 0.04). CONCLUSIONS: Initial AED was successful in 60% of children with AE. If the first AED failed, the outcome was less favorable, with a lower rate of terminal remission and a higher rate of progression to JME and intractable epilepsy.

Adolescent↗

PubMed2002

Resistance to propagation of amygdaloid kindling seizures in rats with genetic absence epilepsy.

PURPOSE: The existence of absence epilepsy and temporal partial seizure pattern in the same patient is an uncommon state. In the present study, we aimed to evaluate whether the process of kindling as a model of complex partial seizures with secondary generalization is altered in rats with genetic absence epilepsy. METHODS: Six- to 12-month-old nonepileptic control Wistar rats and genetic absence epileptic rats from Strasbourg (GAERS) were used in the experiments. One week before the experiments, bilateral stimulation and recording electrodes were implanted stereotaxically into the basolateral amygdala and cortex, respectively. Animals were stimulated at their afterdischarge threshold current twice daily for the process of kindling and accepted as fully kindled after the occurrence of five grade 5 seizures. Bilateral EEGs from amygdala and cortex were recorded continuously during 20 min before and 40 min after each stimulus. RESULTS: All control Wistar rats were fully kindled after stimulus 12 to 15. Although the maximal number of stimulations had been applied, GAERS remained at stage 2, and no motor seizures were observed. The afterdischarge duration in bilateral amygdala and the cortex after the kindling stimulus was shorter in GAERS when compared with control rats. CONCLUSIONS: Occurrence of only grade 2 seizures and no observation of grade 3-5 seizures in GAERS with the maximal number of stimulations would suggest that the generalized absence seizures may be the reason of the resistance in the secondary generalization of limbic seizures during amygdala kindling.

Amygdala↗

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↗

PubMed2001

Neuropsychological assessment in children with absence epilepsy.

OBJECTIVE: To define cognitive deficits in children with absence epilepsy. BACKGROUND: Cognitive deficits have often been reported in children with epilepsy, but have rarely been characterized in patients with a specific epileptic syndrome. METHODS: Detailed neuropsychological testing was carried out on 16 right-handed children with absence epilepsy with similar clinical and EEG findings, and the findings were compared to 16 well-matched right-handed children without absence epilepsy. RESULTS: The authors found lower scores of measures of general cognitive functioning and visuospatial skills in patients with absence epilepsy, as compared to controls. Memory disturbances were also detected in absence epilepsy patients, with selective involvement of nonverbal memory and delayed recall. In contrast, verbal memory and language skills were relatively preserved. Patients whose seizures began at an earlier age seemed to have more severe cognitive deficits. CONCLUSION: Language skills tend to be relatively well preserved in children with generalized epilepsy, with more dysfunction seen in global terms rather than specific lateralizing deficits. Patients with absence epilepsy seem to show a similar neurocognitive profile that may be a reflection of the underlying epilepsy syndrome.

Adolescent↗

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↗

PubMed2001

Contribution of intralaminar thalamic nuclei to spike-and-wave-discharges during spontaneous seizures in a genetic rat model of absence epilepsy.

In an epileptic rat model of generalized absence epilepsies, the genetic absence epilepsy rats from Strasbourg (GAERS), simultaneous recordings of bilateral epidural electroencephalogram (EEG) of the prefrontal cortex and unit activity of neurons in the intralaminar centrolateral (CL) and paracentral thalamic nucleus (PC) were performed under neurolept-anaesthesia (fentanyl-dehydrobenzperidol analgesia). Spike-and-wave (SW) seizures in these rats are characterized by generalized 7-10 Hz spike-and-wave discharges (SWDs) on the EEG. All neurons recorded in intralaminar thalamic nuclei during spontaneous SWDs showed high-frequency (average 368 Hz, range 200-500 Hz), burst-like activity, which occurred in a highly synchronized fashion with every SWD or with alternating SWD-complexes. Burst discharges in intralaminar neurons were delayed by 13.1 ms (CL) and 12.7 ms (PC), with respect to the spike component of a given SWD on the EEG, whereas burst discharges in the ventrobasal thalamus (VB) and in the rostral nucleus reticularis thalami (rRT) preceded the spike component by 17.8 ms and 8.3 ms, respectively. The onset of SWDs on the EEG was preceded by a tonic firing pattern (20-50 Hz) in about one third of CL and PC neurons. Microiontophoretic application of the gamma-aminobutyric acid (GABA)A receptor antagonist bicuculline aggravated, whereas, the glutamate receptor antagonists DNQX and APV dampened, SWD-related discharges in PC and CL; the GABAB receptor antagonist CGP 35347 had no measurable effect. These data indicate that intrathalamic nuclei are recruited rhythmically during SWDs, through mechanisms that seem to rely on a delayed glutamatergic excitation modulated by GABAergic influences, rather than a GABA-mediated rebound burst activity typical of relay cells. The finding of a temporal delay of SWD-related activity in intrathalamic, compared with "specific" thalamic relay nuclei, does not support the notion of a leading or pacemaker role in SWD generation. It is, however, rather suggestive of a function of intrathalamic neurons during synchronization and maintenance of neuronal oscillations, and these intrathalamic neurons may be recruited through glutamatergic corticofugal inputs.

Action Potentials↗

PubMed2001

Absence epilepsy with fast rhythmic discharges during sleep: an intermediary form of generalized epilepsy?

PURPOSE: To describe a particular form of absence epilepsy (AE) characterized by an atypical EEG pattern (fast rhythmic discharges) during sleep and an unfavorable course with the persistence of seizures at a late age and drug resistance. METHODS: We reviewed the medical files of 31 patients diagnosed with AE at our institution been 1995 and 1999 for whom an EEG during sleep had been recorded. Patients with fast rhythmic discharges during sleep were selected for the study. RESULTS: Five patients showed the usual criteria of childhood absence epilepsy (CAE) or juvenile absence epilepsy (JAE), but with fast discharges of rhythmic spikes (10-15 Hz) during sleep. such as those typically observed in Lennox-Gastaut syndrome. Four patients were of adult age at the time of the last examination. Intellectual capacities were "borderline" in each case, with visible social and learning handicaps. Absences were the initial seizure event in all patients, but four patients developed generalized tonic-clonic seizures during the course of the disease. Treatment using a combination of antiabsence drugs such as valproate and lamotrigine led to only marginal improvement. CONCLUSIONS: These findings illustrate the utility of sleep EEG in detecting the fast rhythmic discharges that are markers of drug resistance in AE and suggest the existence of transitional forms of AE that are intermediate between idiopathic and cryptogenic/symptomatic generalized epilepsies.

Adult↗

PubMed1995

Absence epilepsies.

Individuals fulfilling diagnostic criteria for childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE) were selected from a large group of patients who were born between 1945 and 1973 and had presented with absence seizures (AS). Updated data allowed an analysis of 52 patients with CAE and of 62 patients with JAE age > or = 20 years. In CAE, complete control was achieved in 90% of patients (95%, AS only; 77%, AS + generalized tonic-clonic seizures, GTCS). Only 16% of patients with an onset < 9 years had developed GTCS. In JAE, complete control was achieved in 37% of patients (47%, AS; 37%, GTCS). These figures support the validity of the International Classification of Epilepsy (ICE). Stricter diagnostic criteria are discussed.

Adult↗

PubMed2002

Decreased expression of glutamate transporters in genetic absence epilepsy rats before seizure occurrence.

In absence epilepsy, epileptogenic processes are suspected of involving an imbalance between GABAergic inhibition and glutamatergic excitation. Here, we describe alteration of the expression of glutamate transporters in rats with genetic absence (the Genetic Absence Epilepsy Rats from Strasbourg: GAERS). In these rats, epileptic discharges, recorded in the thalamo-cortical network, appear around 40 days after birth. In adult rats no alteration of the protein expression of the glutamate transporters was observed. In 30-day-old GAERS protein levels (quantified by western blot) were lower in the cortex by 21% and 35% for the glial transporters GLT1 and GLAST, respectively, and by 32% for the neuronal transporter EAAC1 in the thalamus compared to control rats. In addition, the expression and activity of GLAST were decreased by 50% in newborn GAERS cortical astrocytes grown in primary culture. The lack of modification of the protein levels of glutamatergic transporters in adult epileptic GAERS, in spite of mRNA variations (quantified by RT-PCR), suggests that they are not involved in the pathogeny of spike-and-wave discharges. In contrast, the alteration of glutamate transporter expression, observed before the establishment of epileptic discharges, could reflect an abnormal maturation of the glutamatergic neurone-glia circuitry.

Aging↗

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↗

PubMed1999

Exclusion of the JRK/JH8 gene as a candidate for human childhood absence epilepsy mapped on 8q24.

Childhood absence epilepsy (CAE), one of the most common epilepsies in children, is genetically and phenotypically heterogeneous. One of the genes responsible for human CAE associated with tonic-clonic seizures has been mapped to chromosome band 8q24 by genetic linkage analysis and is termed ECA1. Recently, we isolated and mapped the JRK/JH8 gene, a human homologue of the mouse epilepsy gene, jerky, on 8q24. The epilepsy phenotype of the mice with inactivated jerky gene as well as its chromosomal localization proposed JRK/JH8 as a prominent candidate for the CAE gene. To confirm whether the JRK/JH8 gene is responsible for ECA1, we performed mutational analyses in the coding region of JRK/JH8 in two CAE families mapped on 8q24, using heteroduplex and direct sequencing methods. We identified seven nucleotide changes, two of which lead to amino acid substitutions. However, these changes did not co-segregate with the disease phenotype. In addition, we redefined the location of JRK/JH8 to be more than 4 Mb distant from D8S502 and ECA1. Thus, negative results of mutation analyses and detailed physical mapping exclude JRK/JH8 as the ECA1 gene.

Animals↗