Intermittent esotropia as equivalent of absence in epilepsy.
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Anticonvulsants↗
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[Incidence of epilepsy and epileptic syndromes in children in the province of Albacete].
OBJECTIVE: The purpose of this study was to determine the incidence rate and the relative frequency of epilepsy and epileptic syndromes during childhood in the province of Albacete. PATIENTS AND METHODS: Patients with childhood epilepsy living in the area have been diagnosed in the Neuropediatric Unit at the General Hospital of Albacete. We included patients under 11 years of age with unprovoked recurring epileptic seizures whose first seizure happened between 1-1-1987 and 1-12-1991, excluding those who have only suffered from febrile seizures and other provoked epileptic seizures. RESULTS: In the five-year period of the study, 136 patients from a population of 60,000 children under 11 years of age suffered from epilepsy. The annual incidence rate of epilepsy at this age is 45 in 100,000. For those under 1 year it is 113, for those aged 1 to 5 it is 52, and for those between 6 and 10 years 30. The most common epileptic syndrome is benign childhood epilepsy with centrotemporal spikes (29%), followed by undefined generalized idiopathic epilepsy (16%), symptomatic partial epilepsy (15%) and childhood absence epilepsy (9%). CONCLUSIONS: The epilepsy incidence rates reported here are lower than those found in most studies. Nevertheless, these results agree with some more recent studies. Benign childhood epilepsy with centrotemporal spikes is the most frequent epileptic syndrome during childhood.
Age Distribution↗
Aicardi syndrome in a girl with mild developmental delay, absence of epilepsy and normal EEG.
We report a 6-year-old girl with corpus callosum agenesis and other cerebral malformations, scoliosis and hypopigmented chorioretinal lacunae in both fundi typical of Aicardi syndrome. She has never had epilepsy and the EEG has always been normal, observations not reported previously in Aicardi syndrome. She was mildly mentally retarded with a full scale IQ of 61. The patient exhibited an unusually mild Aicardi syndrome phenotype.
Agenesis of Corpus Callosum↗
Epilepsy with grand mal on awakening.
BACKGROUND: Epilepsy with grand mal (GMA) on awakening is a benign generalized idiopathic epilepsy, occurring around the time of puberty. There have been few reports regarding Chinese children with GMA, thus this analysis of fourteen Chinese children with GMA who have been encountered in the past 10 years. METHODS: The medical and electroencephalographic (EEC) records of 14 Chinese children with GMA, 7 males and 7 females, were investigated retrospectively. RESULTS: The age of onset ranged from 9 to 15 years with a mean of 12 +/- 1.6 years. Six patients had previous history of febrile convulsion; four and three patients had positive family history for epilepsy and febrile convulsion, respectively. All patients had generalized tonic-clonic seizures on awakening and three of them had concomitant myoclonic jerks. The precipitating factors were sleep withdrawal (9), photostimulation (4), hyperventilation (3), fevers (2), and menstruation (2). The first EEG findings included 3-4 Hz generalized spike-wave complex (8/14), photostimulation activated (4/14), and hyperventilation activated (3/14). Valproate had been regularly administered orally for a duration of 1 to 8 years with a mean of 3.8 +/- 2.0 years up to time of study. Six (75%) out of eight patients relapsed about 6 months to 1 years after discontinuation of anticonvulsant. CONCLUSION: GMA may have some clinical relationship with other idiopathic generalized epilepsies, such as childhood absence epilepsy and juvenile myoclonic epilepsy. High-percentage relapse after drug discontinuation may be the rule for GMA patients, so long-term use of anticonvulsants may be needed.
Adolescent↗
Carbamazepine efficacy and utilization in children.
Carbamazepine is effective for preventing partial and generalized tonic-clonic seizures in children. Although absence epilepsies are more common in children than adults, an estimated 80% of children with epilepsy have seizure types or epilepsies that are potentially responsive to carbamazepine. The differential diagnosis of ictal staring is an especially important issue in children because absence and atypical absence seizures are more prevalent in children than adults. Age-related pharmaco-kinetic differences and drug interactions are major considerations in children. On average, children have higher clearance rates of carbamazepine, shorter half-lives, and higher ratios of carbamazepine-10, 11-epoxide to carbamazepine than adults. In addition, children with severe epilepsy are more likely to require multiple-drug therapy, which can lead to complex drug interactions. When carbamazepine is administered along with valproate, drug protein binding interactions can cause intermittent side effects.
Carbamazepine↗
Epileptic syndromes in childhood: clinical features, outcomes, and treatment.
We reviewed the clinical features, outcome, and treatment of many of the epileptic syndromes that begin in the childhood from 2 to 12 years of age, using a review of the literature and personal experience, with most references to authoritative texts. The developmental tasks of childhood are centered on refinement of motor skills and development of complex intellectual and social skills. The childhood onset epilepsies can be divided into benign, intermediate, and catastrophic based on their impact on childhood development. The clearest benign epilepsy is benign rolandic epilepsy, which often does not require medication treatment. The definition of benign occipital epilepsy is still often vague. In the intermediate category, childhood absence epilepsy often has associated learning disorders and a poor social outcome. About 50% of children with cryptogenic partial seizures have a very benign course, even though their epilepsy syndrome is not well defined. Generalized epilepsy with febrile seizures plus (GEFS+) has a dominant inheritance with a defined defect in cerebral sodium channels, but varies considerably in severity within affected members of the same kindred. The catastrophic epilepsies in childhood all have an inconsistent response to AED treatment and include continuous spike-wave in slow sleep (with variable severity), Landau-Kleffner syndrome (with a confusing overlap with autistic regression), the Lennox Gastaut syndrome (with broad defining features), and myoclonic-astatic epilepsy (with important overlaps with Lennox-Gastaut). Many of the epilepsies that begin in childhood are benign. Others interfere seriously with cognitive and social development.
Adolescent↗
Nucleus-specific abnormalities of GABAergic synaptic transmission in a genetic model of absence seizures.
Human and experimental studies indicate that molecular genetic changes in GABA(A) receptors may underlie the expression of spike-and-waves discharges (SWDs) occurring during absence seizures. However, the full spectrum of the genetic defects underlying these seizures has only been partially elucidated, the expression and functional profiles of putative abnormal protein(s) within the thalamocortical network are undefined, and the pathophysiological mechanism(s) by which these proteins would lead to absence paroxysms are poorly understood. Here we investigated GABA(A) inhibitory postsynaptic currents (IPSCs) in key thalamocortical areas, i.e., the somatosensory cortex, ventrobasal thalamus (VB) and nucleus reticularis thalami (NRT), in preseizure genetic absence epilepsy rats from Strasbourg (GAERS), a well-established genetic model of typical absence seizures that shows no additional neurological abnormalities, and compared their properties to age-matched non-epileptic controls (NECs). Miniature GABA(A) IPSCs of VB and cortical layers II/III neurons were similar in GAERS and NEC, whereas in GAERS NRT neurons they had 25% larger amplitude, 40% faster decay. In addition, baclofen was significantly less effective in decreasing the frequency of NRT mIPSCs in GAERS than in NEC, whereas no difference was observed for cortical and VB mIPSCS between the two strains. Paired-pulse depression was 45% smaller in GAERS NRT, but not in VB, and was insensitive to GABA(B) antagonists. These results point to subtle, nucleus-specific, GABA(A) receptor abnormalities underlying SWDs of typical absence seizures rather than a full block of these receptors across the whole thalamocortical network, and their occurrence prior to seizure onset suggests that they might be of epileptogenic significance.
6-Cyano-7-nitroquinoxaline-2,3-dione↗
[Role of physiopathological hypotheses in therapeutic choice in epilepsy in children].
Choosing an anti-epileptic treatment is different in adults and in children. In children, it depends upon epilepsy syndromes and pathophysiological hypotheses may be helpful. In childhood absence epilepsy, vigabatrin is contraindicated because it induces worsening of absences by increasing the gabaergic inhibition, in children as in animal models. In infantile epilepsies, cerebral development is to be taken into account since functional maturation is still incomplete during the first years of life. In immature brain, focal epileptic discharges tend to generalize. Thus, in infantile spasms, seizures and EEG abnormalities are generalized although there can be a focal lesion. Such a diffuse hyperexcitability is resistant to antiepileptic drugs except to steroids, which decrease the brain level activity. When hyperexcitability is not so marked (spasms without hypsarrhythmia), vigabatrin has the best efficiency, as in spasms due to tuberous sclerosis that are controlled in more than 80 p. 100 of the cases by this drug. Persisting spasms are deleterious for cortical maturation and further cognitive development. Seizures of the first year of life could therefore considered as an emergency to treat, eventually by surgery in cases of focal or hemispheric malformation, before the development become impossible due to the epileptic phenomenon.
Age Factors↗
A population based study of epilepsy in children from a Swedish county.
BACKGROUND: Epidemiological studies of childhood epilepsy are of importance to compare incidence and prevalence rates, age distribution, inheritance, seizure types, epilepsy syndromes and treatment strategies. AIM: To perform an epidemiological study on children with epilepsy in a Swedish county using current ILAE classifications and a recent proposal. METHODS: A population-based study was performed using the hospital data register to select children aged 1 month to 16 years with the diagnosis 'convulsions' or 'epilepsy' recognized between January 1996 and December 2000. Only patients with active epilepsy were included. RESULTS: Two hundred and five children met the study criteria on the prevalence day 31st December, 2000. The total prevalence rate was 3.4/1,000 with a peak prevalence in the age group 8-11 years. The incidence year 2000 was 40/100,000. Additional neuroimpairments were registered in 47.3%. A majority of the patients, 54.0%, had focal or focal plus secondarily generalized seizures. A named syndrome could be diagnosed in 49.4%. The most common syndrome was rolandic epilepsy occurring in 17.0%. Childhood absence epilepsy occurred in 5.9%. Different disorders associated with epilepsy were found in 31.7%. The most common associated phenomenon was malformation of cortical development. Antiepileptic drug treatment was used in 81.0%, the most common first choice being valproate. CONCLUSIONS: The prevalence and incidence rates in this strictly delineated study are lower than those found in other epidemiological studies. Together with many divergences between reported studies concerning frequencies of different items, the results apparently depend on design, e.g. differences in age groups included, inclusion criteria used, and general methodology.
Adolescent↗
Classifications of epileptic syndromes: advantages and limitations for evaluation of childhood epileptic syndromes in clinical practice.
The advantages and limitations of the two most recent International League Against Epilepsy classifications of the epilepsies and epileptic syndromes have been assessed after examining the clinical records of 645 consecutive outpatients aged 1 month to 15 years followed at the Children's Epilepsy Center of the University of Milan, Italy, from 1977 through 1985. The percentage of cases that could be classified according to the 1970 and 1985 proposals for classification were 94.1 and 98.1%, respectively. According to the 1985 proposal, partial epilepsies (PE) and generalized epilepsies (GE) were almost equally represented (45.0 vs. 47.2%). Among PE, symptomatic epilepsies were the commonest variety. In the group of GE, idiopathic and/or symptomatic epilepsies were most common. Childhood absence epilepsy was the largest subgroup among idiopathic GE. Newly diagnosed patients, a less biased sample of the epileptic population represented 38.9% of the entire sample, and a proper classification was possible in 96% of cases. Idiopathic epilepsies were about twice as frequent and idiopathic and/or symptomatic GE less frequent in newly diagnosed patients when compared with the remainder. Marked differences in the frequency of the epilepsies were found in comparison with other reports in the literature which used the 1970 classification. This finding probably depends on different diagnostic assessment, selection bias, and different geographic and ethnic components, but it can also reflect the variable interpretation of the clinical and EEG features of a patient with epilepsy in the light of the artifactual categories of the classification.
Adolescent↗
Valproate as a mainstay of therapy for pediatric epilepsy.
This article reviews relevant pharmacologic and clinical information gathered for valproate since it was introduced into clinical practice 37 years ago and the application of this information for the treatment of childhood epilepsy. Valproate is available for oral and parenteral use. Oral forms are almost completely bioavailable but the rate of absorption varies between formulations. The Chrono tablet formulation has not been adapted for children aged <6 years, in whom the oral solution or syrup, requiring two or three daily administrations, has been used until recently. A new formulation specifically adapted for children, Chronosphere, administrated once or twice daily, is a modified-release formulation of valproate that minimizes fluctuations in serum drug concentrations during a dosage interval. Plasma protein binding is 80-94% and tends to decrease with increasing drug concentration. Valproate elimination is markedly decreased in newborns compared with older children and adults. Elimination by glucuronidation only becomes fully effective by the age of 3-4 years. In children aged 2-10 years receiving valproate, plasma clearances are 50% higher than those in adults. Over the age of 10 years, pharmacokinetic parameters approximate those of adults. Valproate can increase plasma concentrations of concomitant drugs, such as phenobarbital and lamotrigine, by inhibiting their metabolism. As a result of its broad spectrum of efficacy in a wide range of seizure types and epilepsy syndromes, valproate is a drug of choice for children with newly diagnosed epilepsy (focal or generalized), idiopathic generalized epilepsy, epilepsies with prominent myoclonic seizures or with multiple seizure types, and photosensitive epilepsies. In the group of cognitive epilepsies, in which severe spike and wave discharges are accompanied by cognitive deterioration, valproate, ethosuximide, or both should be tested before using corticosteroids. In comparative trials with carbamazepine, phenytoin, and phenobarbital in focal epilepsy and with ethosuximide in absence epilepsy, valproate was as effective and showed a favorable tolerability profile, with minimal adverse cognitive and CNS effects. The low potential for paradoxical seizure aggravation and the long-term efficacy of the drug are additional important factors that contribute to its excellent profile. Intravenous valproate may be effective for the treatment of convulsive and non-convulsive status epilepticus that is refractory to conventional drugs. In infants, potential benefits should be carefully weighed against the risk of liver toxicity. Gastrointestinal intolerance is a relatively frequent, dose-related adverse effect of the drug in children. Bodyweight increase and tremor may be observed in older children and adolescents. Despite the challenge of newer drugs, valproate remains a gold standard antiepileptic drug for the treatment of children.
Anticonvulsants↗
[Epilepsy and the brain's morphological-functional organization].
The article summarized the results of long-term studies of the author with using experimental methods--creation of penicillin and aluminium epileptogenic foci, orbito-frontal cortex stimulation and elimination, and clinical investigation of epileptic status, prefrontal epilepsy, absence EEG activity, symptomatic rolandic epilepsy, childhood epilepsy. Based on the results obtained, the author formulates the conceptions on (1) the key role of prefrontal cortex in the antiepileptic defense system and motor activity control, (2) the role of slow activity in antiepileptogenesis, (3) the age-dependent rhythmic possibilities of children's brain, which determined age-dependent epilepsy types, (4) the complexity of between-hemispheric interactions in this disease.
Brain↗
["De novo" non-convulsive status epilepticus in adults and in the elderly].
There is a growing number of publications in the recent literature reporting the incidence of non-convulsive status epilepticus in the elderly, including both absence epilepsy and partial epileptic seizures. Absence status epilepticus creates a diagnostic problem because of its clinical features: confusion ranging from slight disorientation to stupor. Duration of such states may vary from one hour to a few weeks, with fluctuations and epileptic features in EEG recording (a typical pattern of spikes-slow waves, 3 Hz frequency, symmetrical and synchronical) that disappear after an intravenous injection of benzodiazepines. Absence status epilepticus can be evoked by toxic, metabolic or pharmacological factors as well as by convulsive epileptic seizures. Besides absence epileptic states of middle-cerebral origin there is a rising concern about absence status resulting from simple or complex partial seizures. Generalized non-convulsive status epilepticus following either simple partial or simple complex seizures is characterized by the presence of various focal signs associated with confusion, stupor or coma. The latter may be masking the clinical picture of an underlying cerebral pathology (e.g. brain tumor, hemorrhage, etc.), and epileptic changes can be seen in EEG recording only. Absence status epilepticus can occur in various forms of brain pathology, including stroke, brain tumors, traumatic lesions and other conditions, as well as in systemic diseases affecting the central nervous system function. Therefore, the authors emphasize the importance of electroencephalography in severely ill and unconscious patients, as well as the role of proper anti-epileptic treatment, as this may improve the outcome.
Adult↗
Activity of thalamic reticular neurons during spontaneous genetically determined spike and wave discharges.
This study reports the first intracellular recordings obtained during spontaneous, genetically determined spike and wave discharges (SWDs) in nucleus reticularis thalami (NRT) neurons from the genetic absence epilepsy rats from Strasbourg (GAERS), a model that closely reproduces the typical features of childhood absence seizures. A SWD started with a large hyperpolarization, which was independent of the preceding firing, and decreased in amplitude but did not reverse in polarity up to potentials >/= -90 mV. This hyperpolarization and the slowly decaying depolarization that terminated a SWD were unaffected by recording with KCl-filled electrodes. The prolonged (up to 15 action potentials), high-frequency bursts present during SWDs were tightly synchronized between adjacent neurons, correlated with the EEG spike component, and generated by a low-threshold Ca(2+) potential, which, in turn, was brought about by the summation of high-frequency, small-amplitude depolarizing potentials. Fast hyperpolarizing IPSPs were not detected either during or in the absence of SWDs. Recordings with KCl-filled electrodes, however, showed a more depolarized resting membrane potential and a higher background firing, whereas the SWD-associated bursts had a longer latency to the EEG spike and a lower intraburst frequency. This novel finding demonstrates that spontaneous genetically determined SWDs occur in the presence of intra-NRT lateral inhibition. The unmasking of these properties in the GAERS NRT confirms their unique association with spontaneous genetically determined SWDs and thus their likely involvement in the pathophysiological processes of the human condition.
Action Potentials↗
Voxel-based morphometry in patients with idiopathic generalized epilepsies.
Idiopathic generalized epilepsies (IGE) are a group of frequent age-related epilepsy syndromes. IGE are clinically characterized by generalized tonic-clonic, myoclonic and absence seizures. According to predominant seizure type and age of onset, IGE are divided in subsyndromes: childhood absence and juvenile absence epilepsy (AE), juvenile myoclonic epilepsy (JME) and generalized tonic-clonic seizures on awakening (GTCS). The limits between these subsyndromes are not well defined, supporting the existence of only one major syndrome. Visual assessment of routine magnetic resonance imaging (MRI) in patients with IGE is normal. MRI voxel-based morphometry (VBM) uses automatically segmented gray and white matter for comparisons, eliminating the investigator bias. We used VBM to study 120 individuals (47 controls, 44 with JME, 24 with AE and 15 with GTCS) to investigate the presence of subtle structural abnormalities in IGE subsyndromes. VBM was performed searching for abnormalities on gray matter concentration (GMC) between patients groups and controls. Compared to controls, JME presented increased GMC in frontobasal region and AE showed increased GMC in the superior mesiofrontal region. The GTCS group did not differ from controls. There were no areas of reduced GMC with the statistical level selected. Region of interest analysis showed increased GMC in the anterior portion of the thalamus in patients with absence seizures. Our results support subtle GMC abnormalities in patients with JME and AE when compared to controls. These findings suggest the existence of different patterns of cortical abnormalities in IGE subsyndromes.
Adolescent↗
Basic mechanisms of generalized absence seizures.
Generalized absence seizures are neurophysiologically, pharmacologically, and developmentally unique and comprise the primary seizure type in a number of different absence epilepsy syndromes. Over the last 10 years, the availability of a number of animal models of generalized absence seizures and of sophisticated in vitro electrophysiological techniques that allow investigation of cortical and thalamic networks has begun to shed light on the pathogenesis of this disorder. The basic underlying mechanism appears to involve thalamocortical circuitry and the generation of abnormal oscillatory rhythms from that particular neuronal network. Biochemical mechanisms operative within thalamocortical circuitry during this neuronal oscillation seem to entail phase-locked gamma-aminobutyric acid (GABA)B-mediated inhibition alternating with glutamate-mediated excitation. The basic cellular mechanism operative within this tension between excitation and inhibition appears to involve the T-type calcium current. Local circuitry within the thalamus may influence these oscillatory rhythms by GABAA-mediated inhibition. Pharmacological factors at play external to thalamocortical circuitry include cholinergic, dopaminergic, and noradrenergic mechanisms. Pathways that utilize these various neurotransmitters project onto the thalamus and/or cortex from sites distant to those structures and may modulate the process either up or down. Perturbation of one or more of these neuronal networks may lead to abnormal neuronal oscillatory rhythms within thalamocortical circuitry, with a resultant generation of bilaterally synchronous spike wave discharges that characterize generalized absence seizures. Our increasing understanding of the basic mechanisms that underlie generalized absence seizures promises to allow, for the first time, a rational design of drug treatment for a seizure disorder based on the pathogenesis of that disorder.
Animals↗
Will a critical level of hyperventilation-induced hypocapnia always induce an absence seizure?
We wished to determine if the degree of hypocapnia correlates with increased frequency of absence seizures and if there is a critical pCO2 at which absence seizures are reliably provoked. Twelve untreated children with newly diagnosed absence epilepsy were continuously monitored by EEG and end-expiratory CO2 recording during quiet respiration and hyperventilation (to absence seizure or exhaustion) while breathing four gas mixtures: (a) room air, (b) 100% O2, (c) 4% CO2 in room air, or (d) 4% CO2 + 96% O2). In quiet respiration, a reduction in number of spike and wave bursts and total seconds of spike and wave was noted in children breathing supplemental CO2 (gases c and d vs. gases a and b), p < 0.05. Supplemental O2 had no effect. Eight subjects had absence seizures elicited with each trial of hyperventilation. All subjects had their own critical pCO2, ranging from 19 to 28 mmHg. Three children had no seizures, two despite hypocapnia to pCO2 of 19 and 21 and 1 who achieved a pCO2 of only 25. In 1, absence seizures were provoked in only six of nine hyperventilation trials to pCO2 of 17-23. In 67% of subjects, absence seizures were reliably provoked by hypocapnia. Critical pCO2 varied among children with absence. Determination of whether variation in sensitivity to hypocapnia may be helpful in determining response to antiepileptic drugs (AEDs) or remission of seizures will require further study.
Air↗
Starting and stopping mechanisms of absence epileptic seizures are revealed by hazard functions.
We show that the hazard function provides useful information about the starting and the stopping mechanisms of absence epileptic seizures. The hazard function quantifies changes in the probability that an event (respectively, the starting and the stopping of a seizure) occurs in some small time interval given that it has not occurred yet. It informs us about changes in the concentration of endogenous substances that modulate the neuronal signalling properties of (parts of) the brain. In a pharmacological experiment, we used the hazard function to study the effect of a GABA-transaminase inhibitor (vigabatrin) on the starting and the stopping mechanisms of absence epileptic seizures in a genetic rat model of absence epilepsy (the WAG/Rij rat). This experiment showed that a high GABA level changed the stopping mechanism of the absence epileptic seizures, creating much better conditions for very long seizures to develop. With respect to the starting mechanism, it was found that both with a high and a low GABA level, there was evidence for a recovery mechanism that decreases the probability that a new seizure starts. Initially, this probability is larger with a high GABA level, but gradually it converges to the same constant baseline probability as in the condition with a low GABA level.
Algorithms↗