Neuroepidemiological study of childhood epilepsy by application of international classification of epilepsies and epileptic syndromes (ILAE, 1989)

Febrile Seizure in Children Attending a Tertiary Care Centre in Western Nepal: A Descriptive Cross-sectional Study

Introduction:

Understanding a child with any episode of febrile seizure is important so that special attention could be given. The objective of this study was to find the prevalence of febrile seizure in children attending a tertiary centre in western Nepal.

Methods:

A descriptive cross-sectional study was performed in a tertiary care centre at the department of Pediatrics after taking approval from the Institutional Review Committee. Study was conducted among the children presented with febrile seizure from 18th October 2017 to 12th April 2020. Patient files were retrospectively reviewed. Convenience sampling method was used. Data and descriptive analysis were done using Statistical Package for the Social Sciences version 25. Point estimate at 95% Confidence Interval was calculated along with frequency and percentage for binary data.

Results:

Of the total 4701 admitted children during a study period, 217 (4.61%) (3.41-5.81 at 95% Confidence Interval) children had febrile seizure. Out of them, 154 (70.9%) male and 63 (29.1%) female with 168 (77.4%) simple and 49 (22.6%) complex febrile seizure. The mean age of presentation was at 23.2±13.61 months whereas mean age for male and female were 22.99±13.86 months and 23.73±13.09 months respectively. Recurrent febrile seizure noted in 68 (31.3%) children and fever in half the cases 110 (50.7%) was caused by Upper Respiratory Tract Infection.

Conclusions:

Simple febrile seizure was more common and the peak age of presentation was in the second year of life and more commonly in male. One third of febrile seizures were recurrent and half the children had upper respiratory tract infection as the most common etiology of fever.

Seizures in Mouse Models of Rare Neurodevelopmental Disorders

Genetic neurodevelopmental disorders - that often include epilepsy as part of their phenotype - are a heterogeneous and clinically challenging spectrum of disorders in children. Although seizures often contribute significantly to morbidity in these affected populations, the mechanisms of epileptogenesis in these conditions remain poorly understood. Different model systems have been developed to aid in unraveling these mechanisms, which include a number of specific mutant mouse lines which genocopy specific general types of mutations present in patients. These mouse models have not only allowed for assessments of behavioral and electrographic seizure phenotypes to be ascertained, but also have allowed effects on the neurodevelopmental alterations and cognitive impairments associated with these disorders to be examined. In addition, these models play a role in advancing our understanding of these epileptic processes and developing preclinical therapeutics. The concordance of seizure phenotypes - in a select group of rare, genetic, neurodevelopmental disorders and epileptic encephalopathies - found between human patients and their model counterparts will be summarized. This review aims to assess whether models of Rett syndrome, CDKL5 deficiency disorder, Fragile-X syndrome, Dravet syndrome, and Ohtahara syndrome phenocopy the seizures seen in human patients.

Descriptive study of symptomatic epilepsy by age of onset in patients with a 3-year follow-up at the Neuropaediatric Department of a reference centre

OBJECTIVE

We conducted a descriptive study of symptomatic epilepsy by age at onset in a cohort of patients who were followed up at a neuropaediatric department of a reference hospital over a 3-year period PATIENTS AND METHODS: We included all children with epilepsy who were followed up from January 1, 2008 to December 31, 2010 RESULTS: Of the 4595 children seen during the study period, 605 (13.17%) were diagnosed with epilepsy; 277 (45.79%) of these had symptomatic epilepsy. Symptomatic epilepsy accounted for 67.72% and 61.39% of all epilepsies starting before one year of age, or between the ages of one and 3, respectively. The aetiologies of symptomatic epilepsy in our sample were: prenatal encephalopathies (24.46% of all epileptic patients), perinatal encephalopathies (9.26%), post-natal encephalopathies (3.14%), metabolic and degenerative encephalopathies (1.98%), mesial temporal sclerosis (1.32%), neurocutaneous syndromes (2.64%), vascular malformations (0.17%), cavernomas (0.17%), and intracranial tumours (2.48%). In some aetiologies, seizures begin before the age of one; these include Down syndrome, genetic lissencephaly, congenital cytomegalovirus infection, hypoxic-ischaemic encephalopathy, metabolic encephalopathies, and tuberous sclerosis.

CONCLUSIONS

The lack of a universally accepted classification of epileptic syndromes makes it difficult to compare series from different studies. We suggest that all epilepsies are symptomatic because they have a cause, whether genetic or acquired. The age of onset may point to specific aetiologies. Classifying epilepsy by aetiology might be a useful approach. We could establish 2 groups: a large group including epileptic syndromes with known aetiologies or associated with genetic syndromes which are very likely to cause epilepsy, and another group including epileptic syndromes with no known cause. Thanks to the advances in neuroimaging and genetics, the latter group is expected to become increasingly smaller.

Epidemiology of epilepsy

Epilepsy is a burden affecting no fewer than 50 million patients worldwide. It is a heterogeneous group of disorders comprising both common and very rare forms, thus rendering its epidemiological investigations rather difficult. Moreover, making an epilepsy diagnosis per se can be challenging due to an evolving system of classification, and its dependency on local habits and culture. Any attempt at meta-analyses must consider such biases when pooling data from different centers and countries. Differentiating a contextual seizure from chronic epilepsy is every epileptologist's daily mission, yet it is also crucial for achieving a proper estimation of the epidemiology of epilepsy. Our present objective was to provide an overview of the epidemiology of both syndromic and non-syndromic epilepsy. Most epileptic syndromes tend to be rare and, thus, the feasibility of epidemiological quantification in populations is also addressed. Regarding its prevalence and cost, epilepsy deserves greater attention than it generally receives, as it appears to continue to be a condition under persistent taboos.

Epilepsy surgery for early infantile epileptic encephalopathy (ohtahara syndrome)

Early infantile epileptic encephalopathy or Ohtahara syndrome is the earliest form of the age-dependent epileptic encephalopathies. Its manifestations include tonic spasms, focal motor seizures, suppression burst pattern, pharmaco-resistance, and dismal prognosis. The purpose of this study was to evaluate the effectiveness of epilepsy surgery in selected infants. We identified 11 patients, 9 from the literature and 2 from our institution that fulfilled diagnostic criteria of Ohtahara syndrome and had undergone epilepsy surgery in infancy. Seven of the 11 infants have remained seizure free (Engel class IA) and four are reportedly having rare to infrequent seizures (Engel class IIB). All patients experienced "catch up" development. In contrast to Ohtahara's15 pharmacotherapy managed patients, who had a mortality rate of approximately fifty percent, and those that survived continued to have seizures and were severely impaired, the outcome of selected surgically managed patients is much more favorable.

Epileptic encephalopathies in adults and childhood

Epileptic encephalopathies are motor-mental retardations or cognitive disorders secondary to epileptic seizures or epileptiform activities. Encephalopaties due to brain damage, medications, or systemic diseases are generally not in the scope of this definition, but they may rarely accompany the condition. Appropriate differential diagnosis of epileptic seizures as well as subclinical electroencephalographic discharges are crucial for management of seizures and epileptiform discharges and relative regression of cognitive deterioration in long-term followup. Proper antiepileptic drug, hormonal treatment, or i.v. immunoglobulin choice play major role in prognosis. In this paper, we evaluated the current treatment approaches by reviewing clinical electrophysiological characteristics of epileptic encephalopathies.

Ohtahara syndrome with emphasis on recent genetic discovery

Ohtahara syndrome or Early Infantile Epileptic Encephalopathy (EIEE) with Suppression-Burst, is the most severe and the earliest developing age-related epileptic encephalopathy. Clinically, the syndrome is characterized by early onset tonic spasms associated with a severe and continuous pattern of burst activity. It is a debilitating and early progressive neurological disorder, resulting in intractable seizures and severe mental retardation. Specific mutations in at least four genes (whose protein products are essential in lower brain's neuronal and interneuronal functions, including mitochondrial respiratory chains have been identified in unrelated individuals with EIEE and include: (a) the ARX (aristaless-related) homeobox gene at Xp22.13 (EIEE-1 variant); (b) the CDKL5 (SYK9) gene at Xp22 (EIEE-2 variant); (c) the SLC25A22 (GC1) gene at 11p15.5 (EIEE-3 variant); and (d) the Stxbp1 (MUNC18-1) gene at 9q34-1 (EIEE-4 variant). A yet unresolved issue involves the relationship between early myoclonic encephalopathy (EME-ErbB4 mutations) versus the EIEE spectrum of disorders.

Clinical characteristics and use of antiepileptic drugs among adolescents with uncomplicated epilepsy at a referral center in Novi Sad, Serbia

The study aimed to investigate the type and etiology of epileptic seizures and the use of antiepileptic drugs for the treatment of various forms of epileptic seizures among adolescents with active but uncomplicated epilepsy at a tertiary referral center in Novi Sad, Serbia. The study design was cross sectional. Data were obtained from patients and medical records. A total of 103 adolescents (39 males and 64 females) with active but uncomplicated epilepsy were included. Patients with primary generalized seizures had significantly better control of epilepsy than those with partial seizures with or without secondary generalization. A total of 80 (77.7%) adolescents had no known underlying etiology based on initial diagnosis and evaluation. All adolescents were classified into known idiopathic syndromes (54.4%), non-classifiable cryptogenic etiology (23.3%), and secondary epilepsy attributed to MRI-identified lesions (22.3%). Eighty-eight percent of adolescents were taking monotherapy and 64.8% of these were taking valproate. New antiepileptic drugs (AEDs), topiramate and lamotrigine, the only drugs available free of charge at the Serbian market, were used in 19.4% of patients. A total of 57.3% adolescents were seizure-free, 24.2% had occasional seizures, and 18.5% had seizures despite AED treatment.

"Epileptic encephalopathy" of infancy and childhood: electro-clinical pictures and recent understandings

There is growing interest in the diagnosis of cognitive impairment among children with epilepsy. It is well known that status of seizures control has to be carefully investigated because it can be sufficient "per se" to cause progressive mental deterioration conditions. Subclinical electroencephalographic discharges may have subtle effects on cognition, learning and sleep patterns, even in the absence of clinical or sub-clinical seizures. In this respect, electroencephalographic monitoring (long-term and nocturnal recording) and in particular an all night video-polysomnography (V-NPSG) record can be crucial to detect the presence of unrecognized seizures and/or an inter-ictal nocturnal EEG discharge increasing. Epileptic encephalopathies (EE) are a group of conditions in which the higher cognitive functions are deteriorate as a consequence of epileptic activity, which, in fact, consists of frequent seizures and/or florid and prolonged interictal paroxysmal discharges, focal or generalized. AEDs represent the first line in opposing the burden of both, the poor seizures control and the poor interictal discharges control, in the cognitive deterioration of EE affected children. Thus, to improve the long-term cognitive/behavioural prognosis in these refractory epileptic children, it should be taken into account both a good seizures control and a strict sleep control, choosing carefully antiepileptic drugs which are able to control not only seizures clinically recognizable but even the EEG discharges onset and its increasing and spreading during sleep. Here, we review the efficacy and safety of the newer AEDs that, to date, are used in the treatment of EE in infancy and childhood.

An Epidemiological Study of Children with Status Epilepticus in Okayama, Japan

BACKGROUND

The incidence of status epilepticus (SE) in Asian children, including Japanese, has not been reported.

METHODS

In 2003, we performed an epidemiological study of SE on Japanese children (31 days or older to <15 years of age) in Okayama City by ascertaining all lifetime first episodes of SE.

RESULTS

Thirty-seven patients (22 males and 15 females) were identified. The annual incidence of SE was 38.8 per 100,000 population (95% CI: 24.5-49.5). Febrile SE in the absence of CNS infection accounted for 17. Acute symptomatic etiologies other than febrile SE were observed in eight patients, including three cases of influenza encephalitis/encephalopathy. Five were classified as remote symptomatic and the remaining seven as cryptogenic. The highest incidence (155.1/100,000) was seen in the age range of 31 days or older to <1 year, followed by 101.5/100,000 in the age range of one year, and the incidence decreased after eight years. In 26 of the 37 patients, SE was their first seizure. As for seizure types, 32 had convulsive SE, including tonic status in one. Five others showed nonconvulsive SE, including complex partial SE in four and absence status in one. No one died of SE. Two patients who brought on SE because of influenza encephalitis/encephalopathy suffered from motor disturbance with or without mental disturbance after SE.

CONCLUSIONS

The incidence of SE tended to be higher in Japanese children than reported in Caucasians. The Japanese had an age-specific incidence pattern similar to that of Caucasians.

A population-based survey of childhood epilepsy in Okayama Prefecture, Japan: reclassification by a newly proposed diagnostic scheme of epilepsies in 2001

The purpose of this study is to clarify the usefulness and problems of the newly proposed classification of epilepsies (International League Against Epilepsy: ILAE, 2001) in the epidemiological studies of epilepsy. We previously conducted an epidemiological study in Okayama Prefecture, Japan, in 1999, using the ILAE 1989 classification. Among 250,997 children under 13 years of age, 2220 epileptic patients were ascertained. In this study, we reclassified them according to the ILAE 2001 classification, focusing on axes 2 (seizure types) and 3 (syndromes). We were able to classify 1803 (95.0%) seizure types out of 1899 with detailed clinical information. In focal seizures, the most common were secondarily generalized seizures (88.6%), which generally do not represent a unique anatomic substrate. In generalized seizures, topic-clonic seizures (40.7%) and spasms (21.0%) were the most common. We identified only 269 (12.1%) patients with specific epilepsy syndromes out of the 2220. We classified 1761 patients without specific syndromic diagnoses only by axis 2, but the new concept of epileptic seizure types, representing a unique pathophysiologic mechanism and anatomic substrate, was not very meaningful in most cases, even in those with focal seizures.

Prevalence of Childhood Epilepsy and Distribution of Epileptic Syndromes: A Population-based Survey in Okayama, Japan

PURPOSE

A population-based survey childhood epilepsy was undertaken in Okayama Prefecture, Japan, to determine the prevalence rate and the distribution of epilepsies and epileptic syndromes according to the International Classification (ILAE, 1989).

METHODS

Information on patients younger than 13 years with active epilepsy was collected from medical records. Patients diagnosed with epilepsy according to clinical and EEG findings were put on the list even if those patients had had a single seizure or seizures occurring during febrile episodes.

RESULTS

In total, 2,220 cases were identified from a background population of 250,997. The prevalence rate was 8.8 per 1,000. If we exclude patients who had experienced a single seizure or seizures occurring during febrile episodes to compare our results with previous reports, the prevalence rate was 5.3 per 1,000. Of the 2,220 cases, 2,030 (91.4%) were classified into three major categories by ILAE classification. They consisted of 1,556 (76.7%) with localization-related epilepsy, 453 (22.3%) with generalized epilepsy, and 21 (1.0%) with undetermined epilepsy. Of the 2,030 cases, 309 (15.2%) were classified into epileptic syndrome categories, and 84.8% of the total were nonspecific types of epilepsy.

CONCLUSIONS

The prevalence rate of childhood epilepsy was distributed from 5.3 to 8.8 per 1,000. The appearance rate of various types of epileptic syndromes was low. Most cases could not be classified into the detailed categories of the International Classification (ILAE, 1989).

Epilepsy in Colombia: Epidemiologic Profile and Classification of Epileptic Seizures and Syndromes

PURPOSE

A national study was performed in Colombia to determine the general and regional prevalence of epilepsy, clinical profiles, seizure types, and clinical syndromes.

METHODS

Based on the National Epidemiological Study of Neurological Diseases (EPINEURO), we evaluated and followed up for 1 year all the subjects with epilepsy from the National Sample. Clinical profiles were further assessed. Seizure types and epilepsy syndromes were established according to the international classifications.

RESULTS

General prevalence was found to be 11.3 per 1,000, with little variation among regions, except the eastern region, where prevalence was 23 per 1,000; prevalence for active epilepsy was 10.1 per 1,000. Women have a slightly greater (not statistically significant) risk. Most seizures are focal (partial), frequently with secondary generalization. The most frequent epilepsy syndrome encountered was partial symptomatic/cryptogenic (80%). Epilepsy onset in Colombia occurs most frequently in childhood.

CONCLUSIONS

Prevalence rates of epilepsy in Colombia are similar to those reported in nations with comparable developmental status and have diminished over time. The study presents the distribution of seizures and syndromes. The most frequent types are focal syndromes.

Epidemiology of idiopathic generalized epilepsies

Idiopathic generalized epilepsies (IGEs) are a relatively new category of disorders defined by strict clinical and electroencephalogram (EEG) features proposed by the International League Against Epilepsy (ILAE) classification of epileptic syndromes. IGEs are usually easy to diagnose when clinical and EEG data are collected, but epilepsy is not synonymous with epileptic syndrome. So far, IGEs are studied in the large group of epilepsies of undetermined or unknown etiology although the genetic origin is now largely accepted. ILAE-proposed criteria are helpful in the clinical and therapeutic management of IGEs, but many epidemiologic studies still confuse the cryptogenic and idiopathic groups. Some syndromes in childhood, which are completely described by strict electroclinical criteria such as the absence epilepsies, juvenile myoclonic epilepsies, are usually included and analyzed in epidemiologic studies; however, other epileptic syndromes observed in infancy, such as benign familial neonatal seizures and benign myoclonic epilepsy in infancy, are quite rare and are usually excluded from epidemiologic surveys because they are difficult to describe completely in electro-clinical terms. Another strong limitation in the study of epidemiology of IGEs is the lack of EEG data, either because EEG is not available or the routine EEG is normal. This is particularly relevant in the inclusion of patients with only tonic-clonic seizures. IGEs encompass several different syndromes, and a few patients shift from one phenotype to another. The overlapping of some syndromes during infancy and adolescence increased the difficulty to individualize strictly the correct syndrome. Many discrepancies can be observed in the distribution of the different syndromes included in the group of IGEs, because the strict criteria for classifying these syndromes proposed by the ILAE are often not respected. With this understanding, the general frequency of IGEs can be assessed at 15-20% of all epilepsies. The frequency and the distribution of incidence and prevalence of the different syndromes are tentatively reported and discussed. When the term idiopathic is used following the restrictive ILAE criteria, the mortality data concerning patients with idiopathic epilepsies do not show an increased standardized mortality ratio.

Specific Epileptic Syndromes Are Rare Even in Tertiary Epilepsy Centers: A Patient‐oriented Approach to Epilepsy Classification

PURPOSE

To assess the practicability and reliability of a five-dimensional patient-oriented epilepsy classification and to compare it with the International League Against Epilepsy (ILAE) classification of epilepsy and epileptic syndromes. The dimensions consist of the epileptogenic zone, semiologic seizure type(s), etiology, related medical conditions, and seizure frequency.

METHODS

The 185 epilepsy patients (94 adults, 91 children, aged 18 years or younger) were randomly selected from the database of a tertiary epilepsy center and the general neurological department of a metropolitan hospital (28 adults). The charts were reviewed independently by two investigators and classified according to both the ILAE and the patient-oriented classification. Interrater reliability was assessed, and a final consensus among all investigators was established.

RESULTS

Only four (4%) adults and 19 (21%) children were diagnosed with a specific epilepsy syndrome of the ILAE classification. All other patients were in unspecific categories. The patient-oriented classification revealed that 64 adults and 56 children had focal epilepsy. In an additional 34 adults and 45 children, the epileptogenic zone could be localized to a certain brain region, and in 14 adults and five children, the epileptogenic zone could be lateralized. Fourteen adults and 21 children had generalized epilepsy. In 16 adults and 14 children, it remained unclear whether the epilepsy was focal or generalized. Generalized simple motor seizures were found in 66 adults and 52 children, representing the most frequent seizure type. Etiology could be determined in 40 adults and 45 children. Hippocampal sclerosis was the most frequent etiology in adults (10%), and cortical dysplasia (9%), in children. Seven adults and 31 children had at least daily seizures. Seventeen adults and 26 children had rare or no seizures at their last documented contact. The most frequent related medical conditions were psychiatric disorders and mental retardation. Interrater agreement was high (kappa values of 0.8 to 0.9) for both the patient-oriented and the ILAE classification.

CONCLUSIONS

Specific epilepsy syndromes included in the current ILAE classification are rare even in a tertiary epilepsy center. Most patients are included in unspecific categories that provide only incomplete information. In contrast, all of the patients could be classified by the five-dimensional patient-oriented classification, providing all essential information for the management of the patients with a high degree of interrater reliability.

Prognosis after withdrawal of antiepileptic drugs in childhood-onset cryptogenic localization-related epilepsies

The purpose of this study was to clarify the risk factors of relapse following discontinuation of AEDs in patients with childhood-onset cryptogenic localization-related epilepsies. The subjects were 82 patients who fulfilled the following criteria: (1) age at first visit of less than 15 years, (2) follow-up period of more than 5 years, (3) suffering from cryptogenic localization-related epilepsies, and (4) the patient underwent AED withdrawal during the follow-up period. As a basic principle, we decided to start withdrawing AEDs when both of the following two conditions were met: (1) the patient had a seizure-free period of 3 years or more, and (2) there were no epileptic discharges on EEGs just prior to the start of withdrawal. Seizures recurred in eight of the 82 patients (9.8%). Univariate analysis revealed that the following factors were correlated with higher rates of seizure relapse: 6 years of age or higher at onset of epilepsy; 15 years of age or higher at the start of AED withdrawal; 5 years or more from the start of AED treatment to seizure control; five or more seizures before seizure control; and two or more AEDs administered before seizure control. Among these risk factors, 6 years of age or higher at onset and 5 years or more from the start of AED treatment to seizure control were determined by multivariate analysis to be independent risk factors for relapse. Thus, we conclude that the physician should be more careful in discontinuing AEDs in these higher-risk patients groups, and more generous in discontinuing AEDs in lower-risk groups.

Epileptic Encephalopathies in Early Infancy With Suppression-Burst

Early infantile epileptic encephalopathy with suppression-burst, or Ohtahara syndrome (OS), and early myoclonic encephalopathy (EME) are epileptic encephalopathies with onset of frequent seizures in the neonatal and early infancy period and with a characteristic EEG pattern, namely, suppression-burst, in which higher-voltage bursts of slow waves mixed with multifocal spikes alternate with isoelectric suppression phase. Their nosologic independence is now widely accepted, although some controversy initially occurred because of their common characteristics such as age of onset, EEG features, seizure intractability, and poor prognosis. Major differences between the two syndromes include (1) tonic spasms in OS versus partial seizures and erratic myoclonias in EME, (2) continuous suppression-burst pattern in both waking and sleeping states in OS versus this EEG pattern almost limited to sleep in EME, and (3) static structural brain damage in OS versus genetic or metabolic disorders in EME. The most important differentiating point is their evolutional pattern with age, which may reflect their pathophysiologic difference. Ohtahara syndrome evolves to West syndrome and further to Lennox-Gastaut syndrome with age, but EME demonstrates no unique evolution; namely, it continues as such for a long time or changes into partial epilepsy or severe epilepsy with multiple independent spike foci.

Syndromic diagnosis at the epilepsy clinic: role of MRI in lobar epilepsies

PURPOSE

Magnetic resonance imaging (MRI) is an essential diagnostic tool for the management of epilepsy at modern epilepsy clinics. This study was conducted to incorporate MRI features into the international classification of epilepsies and epilepsy syndromes (ICEES) proposed by the International League Against Epilepsy (ILAE).

METHODS

Three hundred consecutive patients newly registered in the Yonsei Epilepsy Clinic underwent stepwise classifications based on clinical features, clinical EEG, and clinical EEG-MRI correlations. The patients were required to have epilepsy and have undergone both EEG and MRI for inclusion in the study. Interictal epileptiform discharges (IEDs) in the EEG were divided into lobar, multilobar, and generalized. MRI lesions were divided into lobar and multilobar lesions. Lobar epilepsies (LEs) were divided into temporal, frontal, parietal, occipital, rolandic, temporoparietooccipital junctional, multilobar, and nonlocalized LEs.

RESULTS

Two hundred forty-nine patients satisfied the inclusion criteria. In the first-step diagnosis, 190 patients were classified as having localization-related epilepsy; 24 patients, generalized epilepsy; 34 patients, undetermined epilepsy; and one patient, a special syndrome. EEG revealed IEDs in 124 (50%) patients, and the second-step diagnosis changed the diagnostic categories of 79 (32%) patients. MRI detected lesions in 106 (43%) patients, and the third-step diagnosis changed the diagnostic categories of 30 (12%) patients. The nonspecific diagnostic categories of ICEES decreased from 49% to 37% and then to 29%, as diagnosis progressed from steps one to three. In cases of LE, MRI was superior to EEG in its clinical correlation. Additionally, the diagnostic precision in temporal lobe epilepsy was far better than that for other LEs.

CONCLUSIONS

The impact of MRI on ICEES was only modest in terms of changing diagnostic categories, although MRI provided a structural substrate for epilepsy in 38% of patients with negative EEGs. In LE, MRI was as sensitive as EEG, and its clinical correlation was superior to that of EEG, which strongly supports the rationale of incorporating MRI into ICEES.

Early-infantile epileptic encephalopathy with suppression-bursts, Ohtahara syndrome; its overview referring to our 16 cases

Ohtahara syndrome (OS) is characterized by frequent tonic spasms, with or without clustering, of early onset within a few months of life, and a suppression-burst (S-B) pattern in electroencephalography (EEG). Tonic spasms occur in not only waking but also sleeping state in most cases. Partial seizures are observed in about one-third of cases. Brain imagings reveal structural abnormalities including malformations, notably asymmetric lesions in most cases.S-B pattern is persistently observed regardless of circadian cycle. Bursts of 1-3s duration alternate with nearly flat suppression phase of 2-5s at an approximately regular rate; 5-10s of burst-burst interval. Some asymmetry in S-B is noted in about two-thirds of cases. Ictal EEG of tonic spasms shows principally desynchronization with or without initial rapid activity. Tonic spasms appear concomitant with bursts. Characteristic age-dependent evolution from OS to West syndrome (WS) in many cases, and further from WS to Lennox-Gastaut syndrome (LGS) in some, proceed concomitantly with EEG transition from S-B to hypsarrhythmia at around age 3-6 months, and further from hypsarrhythmia to diffuse slow spike-waves at around age 1. Under the inclusive concept of the age-dependent epileptic encephalopathy, OS, WS, and LGS have common characteristics such as age preference, frequent minor generalized seizures, and continuous massive epileptic EEG abnormality. Mutual transition suggests the same pathophysiology among three syndromes and the age factor should be considered as the common denominator responsible for the manifestation of each of their own specific clinico-electrical features. Namely, these syndromes may be the age-specific epileptic reaction to various non-specific exogenous brain insults, acting at the specific developmental stages.

Incidence of epilepsies and epileptic syndromes in children and adolescents: a population-based prospective study in Germany

PURPOSE

To estimate the incidence rate of epilepsies and epileptic syndromes in German children and adolescents aged 1 month to <15 years, and to provide data on their classification.

METHODS

A population-based prospective study was performed between July 1, 1999, and June 30, 2000. All children aged 1 month to <15 years with a newly diagnosed epilepsy or epileptic syndrome were recorded by private pediatricians, EEG laboratories, and the two University Children's Hospitals in the neighboring cities of Heidelberg and Mannheim. The diagnoses were classified according to the International Classification of Epilepsies and Epileptic Syndromes of the International League Against Epilepsy (ILAE).

RESULTS

The total age-adjusted annual incidence rate was 60/100,000 (95% confidence interval, 42-84), with the highest incidence in the first year of life (146/100,000). Focal epilepsies or epileptic syndromes (58%; incidence rate, 35/100,000) were more common than were generalized ones (39%; incidence rate, 24/100,000), and 3% (incidence rate, 2/100,000) of the epilepsies or epileptic syndromes were undetermined. The rate of idiopathic (47%; incidence rate, 29/100,000) and symptomatic or cryptogenic epilepsies (50%; incidence rate, 30/100,000) was equal. No significant difference in incidence between boys and girls was found.

CONCLUSIONS

Incidence rates for epilepsy in German children aged 1 month to <15 years are about equal to those of other countries in Europe and North America. In accordance with studies from the United States and from many European countries, incidence was highest in the first year of life, and no difference in the incidence between girls and boys was found. In Germany as throughout Europe, idiopathic generalized epileptic syndromes are more often diagnosed than in the United States.

Long-wavelength red light emission from TV and photosensitive siezures

PURPOSE

We investigated a role of long-wavelength red light emission from TV in the induction of photosensitive seizures by an animated TV program called "Pocket Monsters".

METHODS

The luminance energy of recorded color bar was measured by a spectroradiometer in cathode-ray tubes (CRTs) of photosensitive patients with and without seizures on the program (induced patients and photosensitive controls).

RESULTS

The mean ratio of long-wavelength red light to total visible range was significantly higher in the CRTs of induced patients than in the CRTs of photosensitive controls. The ratio of luminance energy between at turn-on and at 60 min after turn-on of the CRTs indicated that luminance energy in long-wavelength red range from the CRTs of induced patients increased significantly after turn-on of CRTs.

CONCLUSIONS

High amounts of long-wavelength red light emitted from CRTs might play an important role in induction of photosensitive seizures in "Pokemon" incident.

Classification of epilepsy syndromes and role of genetic factors

In this report the types of epilepsy syndromes seen in children in a tertiary referral center in Beirut, Lebanon were studied and the importance of consanguinity and family history in the occurrence of these syndromes was investigated. Records of 230 pediatric patients evaluated during a 1-year period with the diagnosis of single seizure, febrile seizure, or epilepsy were reviewed. Each patient was classified according to the International League Against Epilepsy classification. The occurrence of consanguinity, of family history of febrile seizures or epilepsy, and of other variables was noted. Thirty-six percent of patients were diagnosed with localization-related epilepsy, 21.7% with generalized epilepsy, 11.7% with undetermined generalized or focal, and 24.3% with special syndromes. Twelve percent of patients were diagnosed with idiopathic, 15.1% with symptomatic, and 30.3% with cryptogenic epilepsies. Consanguinity was more common in patients with symptomatic and cryptogenic epilepsies than in patients with idiopathic epilepsies or with incidental seizures (P < 0.05). Family history of epilepsy was more common in patients with symptomatic, cryptogenic, and idiopathic epilepsies than in patients with incidental seizures (P < 0.05). Family history of febrile seizures but not consanguinity was more common in patients with febrile seizures (P < 0.05). We conclude that genetic factors are important not only in idiopathic epilepsies and febrile seizures but also in cryptogenic and symptomatic epilepsies.

The international classification of the epilepsies and epileptic syndromes. An algorithm for its use in clinical practice

An algorithm has been structured as a guided reading of the international league against epilepsy (ILAE) syndromic classification to be used in clinical practice by less experienced physicians in newly diagnosed patients. The algorithm followed the original structure of the classification, which identifies major syndromic groups, subgroups, and specific syndromes. Validation required two raters, a resident and a board-certified neurologist, to apply the algorithm with different techniques (direct or recorded interview, medical record consultation) to 19 children and 18 adults with epilepsy with information available at the time of diagnosis. The two raters' diagnoses were compared with those of the caring physicians, and cases where disagreement arose were discussed in conference to achieve consensus. The kappa statistic was used as a measure of inter-rater agreement. Caring physicians and both raters agreed in 51% of cases. Substantial agreement (kappa = 0.75) was obtained between the resident and the neurologist on major diagnostic groups and subgroups, mostly in adults. Agreement with the caring physician was slightly more satisfactory for the resident (kappa=0.67) than for the neurologist (kappa = 0.60). Agreement was better with direct or indirect interview than with record consultation, and improved further after discussion. Agreement was obtained after discussion in 32% of cases, in some of which the caring physician agreed on the resident's diagnosis. Agreement was less satisfactory for specific syndromes. On this basis, an algorithm of the ILAE classification is a fairly reliable instrument only for making a broad syndromic classification of epilepsy at the time of diagnosis. The limits of the algorithm tend mostly to reflect the intrinsic limitations of the classification itself.

Prevalence, classification, and severity of epilepsy in children in western Norway

PURPOSE

To determine prevalence of active epilepsy in school children in a defined area and assess the usefulness of International League Against Epilepsy classification of seizures and epileptic syndromes, with special emphasis on frequency, additional handicaps, and therapeutic problems of severe cases.

METHODS

The latest International League Against Epilepsy International Classification of Epileptic Seizures (ICES, 1981) and Epilepsies and Epileptic Syndromes (ICE, 1989) were used for determination of prevalence rates, seizure types, epilepsies and epileptic syndromes, and additional neurological deficits in all 6-to 12-year-old children with epilepsy in a Norwegian county. Children had neuropediatric and EEG examination, intelligence evaluation, and, when necessary, additional investigations.

RESULTS

Prevalence of active epilepsy on January 1, 1995, was 5.1 per 1,000. Main seizure type and epilepsy syndrome could be classified in 98% and 90% of patients, respectively. Seizure types/epileptic syndromes were more often partial/localization related than generalized. Among generalized epilepsies, idiopathic forms were more frequent in girls, and cryptogenic and symptomatic forms more frequent in boys. Epileptogenic EEG activity was most often generalized or localized to one or two areas of the brain and was never found in 14% of patients. Symptomatic etiology was found in 46% of all children and in 81% of therapy-resistant cases, respectively. Over the years, 11% of children had never used antiepileptic drugs (AED), 62% had tried one or two AEDs, and 26% had tried from three to 15 AEDs. Twenty-five percent of children were without present AED treatment. Complementary/alternative medicine had been tried by 12% of children.

CONCLUSIONS

Although most epilepsies could be classified, the number of cases in non-specific categories was relatively high. Symptomatic etiology was frequent, especially in therapy-resistant cases. Multidisciplinary therapeutic and habilitation approaches are often needed in childhood epilepsy.

Epidemiology of temporal lobe epilepsy

To fulfill its task of informed clinical decision making and resource allocation, epidemiological studies in epilepsy must adhere to a series of methodological standards. These are reviewed. Because seizure and epilepsy classification systems may be viewed as extensions of the diagnosis, they have direct implications in the acquisition and interpretation of epidemiologic data. The International League Against Epilepsy (ILAE) classification systems are analyzed in this light. Finally, the lack of Canadian epidemiological studies is addressed, and the relevance and potential of Canadian epidemiological data in epilepsy is discussed.

Generalized spike-and-wave patterns in children: clinical correlates

All electroencephalograms performed in our institution between 1980 and 1990 were reviewed. The clinical characteristics of children with epilepsy and generalized spike-and-wave (SW) patterns were analyzed. The SW patterns were classified according to their frequency. Electroencephalograms of 154 children with epilepsy revealed SW patterns. Absence seizures were the most common first seizure, but partial seizures were frequent. More than 40% had several types of seizures. Sixty percent of the epileptic syndromes were generalized, but almost 25% were partial. The typical SW pattern was associated with absence seizures, a normal examination and computed tomographic scan, idiopathic generalized epilepsies, monotherapy, freedom from seizures, and lack of recurrence. The slow SW pattern was associated with West syndrome; a younger age at seizure onset; atonic, myoclonic, tonic, and partial simple seizures; an abnormal examination and computed tomographic scan; cryptogenic or symptomatic generalized epilepsy or symptomatic partial epilepsy; polytherapy; and poor seizure control. The fast SW pattern was associated with secondary generalized, partial, tonic-clonic, and complex partial seizures; a normal computed tomographic scan; cryptogenic partial epilepsy; isolated seizures; and seizure recurrence. Epilepsy with a typical SW pattern should be considered benign, epilepsy with a slow SW pattern malignant, and epilepsy with a fast SW pattern treacherous.

Incidence of epileptic syndromes in Rochester, Minnesota: 1980-1984

PURPOSE

To determine the incidence and the distribution of epileptic syndromes in a well-defined population.

METHODS

By using the records-linkage system of the Rochester Epidemiology Project, we screened all the residents of Rochester, Minnesota, who received a diagnosis of seizures, convulsions, or epilepsy from 1980 through 1984. One hundred fifty-seven residents with incident epilepsy (recurrent unprovoked seizures) were classified by using the International League Against Epilepsy (ILAE) Classification of the Epilepsies and Epileptic Syndromes. Residents with special syndromes were excluded. With a pretested algorithm, patients were classified at three levels of specification: major syndromic groups (e.g., localization-related syndromes), syndromic subgroups (e.g., idiopathic epilepsy with age-related onset), and whenever possible, individual syndromes.

RESULTS

All but one patient were classified into major syndromic groups and subgroups. The annual age-adjusted incidence per 100,000 population was 52.3 cases (34.9 for localization-related epilepsies; 7.7 for generalized epilepsies; 9.7 for undetermined epilepsies). Incidence was 0.2 for idiopathic, 17.2 for cryptogenic, 17.5 for symptomatic localization-related epilepsies, 3.7 for idiopathic, 1.7 for symptomatic or cryptogenic (age-related), and 2.3 for symptomatic (non age-related) generalized epilepsies.

CONCLUSIONS

With the exception of idiopathic epilepsies, the incidence of the major syndromic categories in our study was higher than that provided by previous population-based studies.

Prevalence of childhood epilepsy in Estonia

PURPOSE

To establish the prevalence rate (PR) and main characteristics of childhood epilepsy in Estonia.

METHODS

We performed a population-based case ascertainment of all the possible sources of medical care in seven counties of Estonia from January 1995 to December 1997. Only cases of patients from 1 month to 19 years of age with active epilepsy (i.e., at least one seizure during the last 5 years, regardless of treatment) were included. All patients were examined by a pediatric neurologist.

RESULTS

Five hundred sixty cases met the study criteria on the prevalence day, December 31, 1997. The total PR was 3.6 per 1,000 population (boy/girl ratio, 1.2:1.0). The PR was the highest-4.3 per 1,000-in the 5-to-9-year-old age group. The prevalence declined markedly in children age 14 years and on. The correlation between age and PR was negative (-0.542, p < 0.0001) by regression analyses. The most frequent seizure types in the total group were primarily generalized seizures-PR 2. 1/1,000 [rate ratio (RR) 1.4, 95% confidence interval (CI) 1.2, 1.6]. The predominance of generalized seizures was significant in those younger than 10 years. In 14.8% of cases, there was a history of epilepsy among first- and second-degree relatives. Benign rolandic epilepsy-PR 0.2/1,000-was the most frequent among idiopathic syndromes, and Lennox-Gastaut syndrome-PR 0.08/1,000-was the most frequent among cryptogenic ones. Perinatal factors-PR 0.8/1,000 were the most frequently found cause of epilepsy. In 304 cases (54.2%), additional medical problems existed.

CONCLUSIONS

The prevalence of childhood epilepsy was comparable with that found in developed countries. Generalized seizures predominated, and the main cause was perinatal factors.

Is the International League against Epilepsy classification of epileptic syndromes applicable to children in Estonia?

The concept of the epileptic syndrome has had a practical and research impact on the management of patients with epilepsy. The aim of the present study was to verify the applicability of the International Classification of Epilepsies and Epileptic Syndromes in children and adolescents in Estonia. A population-based study was performed between January 1995 and December 1997 in seven counties. Only cases involving children between the ages of 1 month and 19 years with at least two unprovoked seizures were included. In all, 560 children and adolescents were referred to the Children's Hospital of the University of Tartu. A syndrome diagnosis was made in 550 (98.2%) cases: (49.4%) were localization-related (6.4% idiopathic, 18.9% symptomatic, 24.1% cryptogenic). Benign childhood epilepsy with centrotemporal spikes was present in 33 (5.9%) and childhood epilepsy with occipital paroxysms in three (0.5%); 48.4% were generalized (28.8% idiopathic, 5.7% cryptogenic or symptomatic, 14% symptomatic). Childhood absence epilepsy was present in 6.4%, juvenile absence in 2.0%, juvenile myoclonic in 0.7% and epilepsy with generalized tonic-clonic seizures on awakening in 17.7%. West syndrome was diagnosed in 1.4%, Lennox-Gastaut syndrome in 2.9% of the cases. In 0.4% of the cases it was undetermined whether seizures were focal or generalized. In 8.8% of the cases there were atypical features so they were classified as 'other symptomatic generalized epileptic syndromes not defined above' and 1.8% of the cases were unclassified. Specific neurological diseases were diagnosed in 5.0% of cases. Thus, the International Classification of Epilepsies and Epileptic Syndromes was very applicable to children and adolescents in Estonia.

The syndromic classification of the International League Against Epilepsy: a hospital-based study from South India

PURPOSE

To determine the distribution of various epilepsies and epileptic syndromes in the epileptic population treated in a university hospital in a developing country.

METHODS

Data concerning 2,531 patients with epilepsy seen between January 1989 and June 1994 were analyzed using the International League Against Epilepsy (ILAE) classification.

RESULTS

Of 2,531 cases, 48% fell into ILAE categories 1.3, 3.2, or 4.1 (cryptogenic, without unequivocal generalized or focal seizures; or situation-related seizures, respectively). Localization-related epilepsies (LREs) and epileptic syndromes (1.1, 1.2, 1.3) were found in 1,591 (62.9%) patients; of these patients, symptomatic localization-related epilepsies totaled 62.7%. and idiopathic localization-related epilepsies accounted for only 0.7%. Juvenile myoclonic epilepsy was the most common type of idiopathic generalized epilepsy (IGE), comprising 4.9% of the total study population and 7.7% of patients registered in the epilepsy clinic. A combination of childhood and juvenile absence epilepsies were found in only 0.4% of the total study population. Single computed tomography (CT) enhancing lesion (SCTEL) and focal cerebral calcification (FCC) accounted for 22% of the etiologic factors for localization-related epilepsies. Neurologic deficits were found in 9.5% of patients with SCTEL; none were found with FCC. None of the patients with these lesions had any history of antecedent events that suggested CNS involvement. In patients with localization-related epilepsies with unremarkable clinical data, the proportion of CT scans showing SCTELs was 39 (95% confidence interval [CI], 0.35-0.43) and 0.18 (95% CI, 15-0.21) for FCCs. The proportion for both lesions together was 0.57 (95% CI, 0.53-0.61). Seizures did not recur once the lesion resolved in patients with SCTELs. In patients with FCCs, seizure remission was 71.5% (95% CI, 53.7-85.4) at 3 years.

CONCLUSIONS

This study illustrates the rarity in one patient population of some of the syndromes and categories described in the ILAE classification. Childhood and juvenile absence epilepsies together formed a small proportion. SCTEL and FCC were important etiologic factors for localization related epilepsies. The epilepsy associated with SCTEL was a form of benign epilepsy; epilepsy associated with FCC had remission rates similar to other remote symptomatic epilepsies. Without neuroimaging evidence, these 2 lesions would have been missed and the patients might have been grouped under cryptogenic localization related epilepsy. For this reason, we emphasize the need for neuroimaging in patients with localization related epilepsies with unremarkable clinical findings, before classification into the cryptogenic category. In the absence of neuroimaging, such patients should be classified as "probably cryptogenic."

Lamotrigine in absence and primary generalized epilepsies

Although lamotrigine has been approved in the United States as adjunctive therapy for partial seizures in patients older than 12 years, there is increasing evidence that it is just as effective, if not more effective, in the treatment of generalized seizures. A large number of open-label studies and some single-blind data, all using lamotrigine as add-on therapy in patients with previously refractory generalized seizures, are available. Controlled studies, some on newly diagnosed, previously untreated patients with generalized seizures are ongoing. Investigations have demonstrated that patients with the following generalized seizure types improve with lamotrigine add-on therapy: Typical and atypical absence, atonic, generalized tonic-clonic, myoclonic, and clonic seizures. Response rates, defined as the percentage of patients with better than 50% reduction in seizure frequency, have been, depending on seizure type, in the range of 30% to 56%, with 0 to 33% of the patients becoming seizure free. The best responses have been noted in typical and atypical absences, and atonic seizures. Children and adults appear to have comparable responses. In addition, add-on studies in patients with specific, previously refractory, epilepsy syndromes have demonstrated that the best improvement in seizure control occurs in patients with petit mal epilepsy, "other symptomatic" generalized epilepsies, and in Lennox-Gastaut syndrome, followed by patients with other myoclonic epilepsies, myoclonic absence and West syndrome. Many previously refractory patients are able to achieve lamotrigine monotherapy. However, patients with nonprogressive myoclonic epilepsy have little, if any, response. Early data from ambulatory encephalographic (EEG) recordings in patients with previously refractory absence seizures, and from controlled studies on patients with newly diagnosed typical absence seizures, appear to confirm the efficacy of lamotrigine in those patients. Controlled studies are ongoing in patients with absence seizures, in patients with generalized tonic-clonic seizures, and in patients with Lennox-Gastaut syndrome. Dosing in generalized seizures is similar to that for partial seizures. Because of the shorter half-life of lamotrigine in children, as compared to adults, higher (mg/kg) doses are often needed in young patients. We conclude that lamotrigine is a promising drug for absence and primary generalized seizures in both children and adults.

Prevalence of childhood epilepsy in Kaunas, Lithuania

The prevalence of epilepsy in children aged 0-15 years of Kaunas city, Lithuania, was evaluated on 1 January 1995. Multiple sources for case identification were used, i.e. medical records at the university hospital, regional outpatient clinics and consultation centres, institutions, schools and kindergartens for the handicapped. Active epilepsy was defined as two or more unprovoked epileptic seizures with at least one seizure occurring within the previous 5 years, regardless of the antiepileptic drug treatment. Prevalence was found to be 4.25 (3.42, if age-standardized) in 1000. The highest rate was found in the 10-14 years age group. The male/female ratio was 1.29. No possible causes could be determined in 60.3% of cases. Congenital causes were diagnosed in 18.8% of cases, perinatal causes in 15.3%, traumatic causes in 2.6% and neuroinfectious causes in 2.4%. Classification of epilepsies and epileptic syndromes [Commission on Classification and Prognosis of the International League Against Epilepsy. Proposal for revised classification of epilepsies and epileptic syndromes. Epilepsia 1989; 30:389-399] revealed that 50% of cases were localization-related epilepsies, 29.9% were generalized epilepsies, 15.9% were undetermined whether partial or generalized and 4.2% were unclassifiable. Rates for idiopathic, symptomatic and cryptogenic cases are presented.

ILAE classification of epilepsies: its applicability and practical value of different diagnostic categories. Osservatorio Regionale per L'Epilessia (OREp), Lombardy

PURPOSE

The study was aimed at verifying the applicability of the ILAE classification and the appropriateness of the different diagnostic categories in a large series of patients with epilepsy observed by epilepsy centers.

METHODS

Data concerning 10,342 patients observed by a network of 14 epilepsy centers in the Lombardy region between June 1990 and June 1994 were collected by using a simple standard form and stored in a PC database.

RESULTS

The diagnosis of epilepsy was assessed in 8,570 patients; the remaining 1,772 cases were excluded from the analysis as being affected by nonepileptic ictal events or by isolated or situation-related seizures, including febrile and neonatal convulsions. A definite syndromic diagnosis, according to the ILAE Classification criteria, was made in 7,332 (85.5%) of 8,570 cases. Atypical features were found in 995 (11.6%) cases, who were therefore classified as uncertain; 198 (2.3%) cases remained unclassified; and in the remaining 45 patients, the diagnosis was not properly codified. The seizure-control profile was found to be highly related to the syndromic diagnosis. The highest percentage of drug-resistant cases was found among patients with generalized symptomatic or cryptogenic syndromes (32.3%) and among cases with partial symptomatic epilepsy (19.8%), whereas virtually no drug-resistant cases were found among patients with idiopathic epilepsies.

CONCLUSIONS

The ILAE classification was found satisfactory in the large majority of cases observed at tertiary centers; however, the appropriateness of its various items in identifying homogeneous subpopulations was uneven, being maximal for those syndromes defined by highly consistent electroclinical pictures. An early identification of the characteristic pictures of distinct epileptic syndromes appears to be a valuable prerequisite for diagnostic and therapeutic approaches.

The I.L.A.E. classification of the epilepsies applied retrospectively to 1902 patients

The I.L.A.E. classification of the epilepsies and epileptic syndromes was applied retrospectively to the epileptic seizure disorders of 1902 consecutive patients collected from a neurological consultant practice over a 30 year period. There were 265 patients with only a solitary seizure when they presented. These 265 included fewer instances of generalized epilepsies (14.0% versus 28.5%) and more instances of epilepsies of undetermined type (35.1% versus 20.4%) than the remaining 1637 patients. It was possible to categorize the epilepsy or epileptic syndrome present in 77.6% of all cases. The remainder could not be classified on the evidence available and thus fell into the I.L.A.E. classification's category of "epilepsies and syndromes undetermined whether focal or generalized'. The number of cases of such epilepsy of undetermined type decreased with increasing number of occasions on which patients were seen. Allowing for the effects of factors such as different age distributions in the various published series (in most series generalized epilepsies were more common in children), the distribution of epilepsies and epileptic syndromes diagnosed retrospectively in the present series was quite consonant with the data reported in the literature from contemporaneous series. In the various published series there were notable differences in the proportions of subjects allocated to the category of 'epilepsies and syndromes undetermined whether focal or generalized'. This raises the possibility that the categorizers' degrees of diagnostic confidence may have had appreciable effects on the reported distributions of epileptic syndromes in the different series. Some consensus regarding the degree of diagnostic probability acceptable for assigning a patient to a particular epileptic syndrome might yield more uniform outcomes from future epilepsy classificational attempts.