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

Classifying epilepsy pragmatically: Past, present, and future

The classification of epilepsy is essential for people with epilepsy and their families, healthcare providers, physicians and researchers. The International League Against Epilepsy proposed updated seizure and epilepsy classifications in 2017, while another four-dimensional epilepsy classification was updated in 2019. An Integrated Epilepsy Classification system was proposed in 2020. Existing classifications, however, lack consideration of important pragmatic factors relevant to the day-to-day life of people with epilepsy and stakeholders. Despite promising developments, consideration of comorbidities in brain development, genetic causes, and environmental triggers of epilepsy remains largely user-dependent in existing classifications. Demographics of epilepsy have changed over time, while existing classification schemes exhibit caveats. A pragmatic classification scheme should incorporate these factors to provide a nuanced classification. Validation across disparate contexts will ensure widespread applicability and ease of use. A team-based approach may simplify communication between healthcare personnel, while an individual-centred perspective may empower people with epilepsy. Together, incorporating these elements into a modern but pragmatic classification scheme may ensure optimal care for people with epilepsy by emphasising cohesiveness among its myriad users. Technological advancements such as 7T MRI, next-generation sequencing, and artificial intelligence may affect future classification efforts.

Clinical profile and treatment outcome of epilepsy syndromes in children: A hospital-based study in Eastern Nepal

Objective

It is often difficult to diagnose epilepsy syndromes in resource-limited settings. This study was aimed to investigate the prospect of ascertaining the diagnosis, clinical profile, and treatment outcomes of epilepsy syndromes (ESs) among children in a resource-limited setting.

Methods

This was a descriptive study done from 01/07/2009 to 15/06/2017 among children (1-17 years of age) with unprovoked seizures presenting to the pediatric neurology clinic of a university hospital in eastern Nepal. Diagnosis, classification, and treatment of seizures were based upon International League Against Epilepsy guidelines.

Results

Of 768 children with unprovoked seizures, 120 (15.6%) were diagnosed as ES. The age of onset of seizure was unique for each ES. Developmental delay and cerebral palsy were present in 47.5% and 28.3% children, respectively. Common ESs were West syndrome (WS)-26.7%, generalized tonic-clonic seizures alone (GTCSA)-21.7%, self-limited childhood epilepsy with centrotemporal spikes (SLCECTS)-12.5%, childhood absence epilepsy (CAE)-10.0%, Lennox-Gastaut syndrome (LGS)-10.0%, other developmental and epileptic encephalopathies (DEE)-5.8%, self-limited familial infantile epilepsy (SLFIE)-4.2%, and juvenile myoclonic epilepsy (JME)-3.3%. Among children with known outcomes (87/120), overall response to pharmacotherapy and to monotherapy was observed in 72.4% (63/87) and 57.5% (50/87) children, respectively. All children with GTCSA, SLFIE, genetic epilepsy with febrile seizure plus (GEFS+), CAE, SLCECTS, and JME responded to pharmacotherapy and they had normal computerized tomography scans of the brain. Seizures were largely pharmaco-resistant in progressive myoclonus epilepsy (PME)-100.0%, LGS-73.0%, WS-52.0%, and other DEEs-40%.

Significance

A reasonable proportion (15.6%) of unprovoked seizures could be classified into specific ES despite limited diagnostic resources. WS was the most common ES. GTCSA, SLCECTS, CAE, and LGS were other common ESs. GTCSA, SLFIE, CAE, SLCECTS, GEFS+, and JME were largely pharmaco-responsive. PME, WS, and LGS were relatively pharmaco-resistant. Electro-clinical diagnosis of certain ES avoids the necessity of neuroimaging.

Could the 2017 ILAE and the four-dimensional epilepsy classifications be merged to a new "Integrated Epilepsy Classification"?

Over the last few decades the ILAE classifications for seizures and epilepsies (ILAE-EC) have been updated repeatedly to reflect the substantial progress that has been made in diagnosis and understanding of the etiology of epilepsies and seizures and to correct some of the shortcomings of the terminology used by the original taxonomy from the 1980s. However, these proposals have not been universally accepted or used in routine clinical practice. During the same period, a separate classification known as the "Four-dimensional epilepsy classification" (4D-EC) was developed which includes a seizure classification based exclusively on ictal symptomatology, which has been tested and adapted over the years. The extensive arguments for and against these two classification systems made in the past have mainly focused on the shortcomings of each system, presuming that they are incompatible. As a further more detailed discussion of the differences seemed relatively unproductive, we here review and assess the concordance between these two approaches that has evolved over time, to consider whether a classification incorporating the best aspects of the two approaches is feasible. To facilitate further discussion in this direction we outline a concrete proposal showing how such a compromise could be accomplished, the "Integrated Epilepsy Classification". This consists of five categories derived to different degrees from both of the classification systems: 1) a "Headline" summarizing localization and etiology for the less specialized users, 2) "Seizure type(s)", 3) "Epilepsy type" (focal, generalized or unknown allowing to add the epilepsy syndrome if available), 4) "Etiology", and 5) "Comorbidities & patient preferences".

Evaluation of Seizure Etiology From Routine Testing to Genetic Evaluation

PURPOSE OF REVIEW

Recognizing the cause of a first seizure and identifying the etiology of epilepsy are essential for management. A systematic approach to patients who present with a first seizure helps distinguish between an acute symptomatic seizure, a provoked or unprovoked seizure, and potential mimickers. Routine testing with EEG and MRI may reveal a predisposition for further seizures and help to establish the underlying epilepsy syndrome. An acquired etiology can be identified in 30% of patients with established epilepsy. The remaining 70% of patients have a presumably genetic etiology. Particularly in patients with specific epilepsy syndromes or suspicion for an autosomal dominant inheritance, genetic testing and counseling should be considered.

RECENT FINDINGS

Neuroimaging, autoimmune antibodies, and genetic testing have revolutionized our ability to investigate the etiology of many epilepsies. The new epilepsy classification distinguishes structural, metabolic, genetic, infectious, and immune-mediated etiologies, which often help determine prognosis and treatment.

SUMMARY

There is growing acceptance and demystification of the term epilepsy as the most common cause for recurrent seizures. The new classification of epilepsy does not stop with the recognition of particular epilepsy syndromes but aims to determine the underlying etiology. This can lead to earlier recognition of surgical candidates, a better understanding of many of the genetic epilepsies, and medical treatments aimed at the underlying mechanism causing the disease.

Do neurologists around the world agree when diagnosing epilepsy? - Results of an international EpiNet study

OBJECTIVE

Previous studies have shown moderate agreement between physicians when diagnosing epilepsy, but have included small numbers. The EpiNet study group was established to undertake multicentre clinical trials in epilepsy. Before commencing trials, we wanted to determine levels of agreement between physicians from different countries and different health systems when diagnosing epilepsy, specific seizure types and etiologies.

METHODS

30 Case scenarios describing six children and 24 adults with paroxysmal events (21 epileptic seizures, nine non-epileptic attacks) were presented to physicians with an interest in epilepsy. Physicians were asked how likely was a diagnosis of epilepsy; if seizures were generalised or focal; and the likely etiology. For 23 cases, clinical information was presented in Step 1, and investigations in Step 2.

RESULTS

189 Participants from 36 countries completed the 30 cases. Levels of agreement were determined for 154 participants who provided details regarding their clinical experience. There was substantial agreement for diagnosis of epilepsy (kappa=0.61); agreement was fair to moderate for seizure type(s) (kappa=0.40) and etiology (kappa=0.41). For 23 cases with two steps, agreement increased from step 1 to step 2 for diagnosis of epilepsy (kappa 0.56-0.70), seizure type(s) (kappa 0.38-0.52), and etiology (kappa 0.38-0.47). Agreement was better for 53 epileptologists (diagnosis of epilepsy, kappa=0.66) than 56 neurologists with a special interest in epilepsy (kappa=0.58). Levels of agreement differed slightly between physicians practicing in different parts of the world, between child and adult neurologists, and according to one's experience with epilepsy.

CONCLUSION

Although there is substantial agreement when epileptologists diagnose epilepsy, there is less agreement for diagnoses of seizure types and etiology. Further education of physicians regarding semiology of different seizure types is required. Differences in approach to diagnosis, both between physicians and between countries, could impact negatively on clinical trials of anti-epileptic drugs.

The yield of video-EEG telemetry evaluation for non-surgical candidate children

BACKGROUND

Video EEG (VEEG) is performed for most pediatric patients in order to evaluate unclear paroxysmal events and improve our understanding of difficult to control epileptic patients.

PURPOSE

To characterize the video EEG studies on children who are not candidates for surgery in order to identify the parameters that affect results in level of improving the rate of acquisition, as well as improving the ability to expect the likelihood of epilepsy and of gathering new information as a result of the VEEG.

METHODS

Retrospective chart analysis of all consecutive patients who underwent VEEG in two VEEG monitoring units.

RESULTS

323 children of a mean age of 7 years (STD 4.73, range 0-17 years) were monitored for a mean duration of 2 days (STD 1.65, range 1-10 days). The main reasons for monitoring were: evaluation of unclear events (n = 234), evaluation of previously diagnosed epilepsy (n = 36) and confirmation of Electrical Status Epilepticus in Sleep (ESES) (n = 34). The main event types for evaluation were: staring episodes (n = 67), myoclonic jerks (n = 35) and abnormal eye movement (n = 22). Suspected events were captured in 70% of the patients. There was a positive correlation between acquisition of suspected events and each of the following: duration of the monitoring, the frequency of investigated events per history, the type of investigated events. A prior interictal epileptic activity on routine EEG was a positive predictor of an event to be epileptic (p = 0.003). Amongst the group of known epileptic patients, VEEG had role in changing diagnosis in 53% of patients. Many of them had focal interictal epileptiform activity in their routine EEG.

CONCLUSIONS

Selecting patients with frequent events and longer monitoring periods increase the yield of VEEG. Looking carefully into clinical characteristics of the patient prior to VEEG can clarify diagnosis therefore render the VEEG test superfluous to subgroups of patients. Prior routine epileptic EEG, coexistence of other seizure types, behaviors accompanying the investigated habitual behavior and abnormalities in other investigations (MRI, cognitive function and EEG) are the parameters that can predict diagnosis of epilepsy. Precise diagnosis in known epileptic patients as a result of VEEG is more likely for those with focal interictal epileptiform discharges in routine EEG.

Prognostic factors for outcome in pediatric probable lesional frontal lobe epilepsy with an unknown cause (cryptogenic)

The outcomes of children with cryptogenic seizures most probably arising from the frontal lobe are difficult to predict. We retrospectively collected data on 865 pediatric patients with epilepsy. In 78 patients with cryptogenic frontal lobe epilepsy, the age at first seizure was inversely correlated with the outcome, including the degree of intellectual disability/developmental delay (P = .002) and seizure frequency (P = .02) after adequate treatment. Intellectual disability was more prevalent in children with a first seizure at 0 to 3 years old (P = .002), and seizures were more frequent in those with a first seizure at 0 to 6 years old than at 7 to 16 years old (P = .026). For pediatric cryptogenic frontal lobe epilepsy, the age at first seizure is important and inversely correlated with outcome, including seizure frequency and intellectual disability.

State of the Art Approach to the Classification of Epileptic Seizures and Epilepsies

In the light of the latest knowledge acquired from clinical and laboratory research dealing with genetic, molecular biology and neuroimaging, existing classifications were successively revised by the International League Against Epilepsy (ILAE) in 2001, 2006, and 2010. In the latest classification established in 2010, proposals articulated radical changes in terms of concepts and definitions of the previously published classifications and put forward new classifications for epileptic seizures, epilepsies and electroclinical syndromes. This review refers to the changes of the new classification with their reasons and criticisms.

Pediatric focal epilepsy syndromes

Benign epilepsy with centrotemporal spikes, early-onset childhood occipital epilepsy (Panayiotopoulos syndrome [PS]) and late-onset childhood occipital epilepsy (Gastaut type [LOCE-G]) are the principal pediatric focal epilepsy syndromes. They share major common characteristics: the appearance and resolution of electroclinical features are age related, there is a strong genetic predisposition, the clinical course is often mild with infrequent and easy to control seizures, interictal epileptiform activity is disproportionately abundant when compared with the clinical correlate, and tends to potentiate and generalize during sleep. In this review, we outline the relevant pathophysiology underlying this electroclinical spectrum. Then, the initial description of individual syndromes is followed by a summary of overlapping features and intermediate presentations that question the boundaries between these entities and provide the basis for the concept of a childhood seizure susceptibility syndrome. Additionally, we outline the main features of the related epileptic encephalopathies. An outlook on potential future lines of research completes this review.

Continuous spike and waves during sleep and electrical status epilepticus in sleep

Continuous spike and waves during sleep is an age-related epileptic encephalopathy that presents with neurocognitive regression, seizures, and an EEG pattern of electrical status epilepticus during sleep. Patients usually present around 5 years of age with infrequent nocturnal unilateral motor seizures that progress within 1 to 2 years to a severe epileptic encephalopathy with frequent seizures of different types, marked neurocognitive regression, and an almost continuous spike-wave EEG pattern during slow-wave sleep. The pathophysiology of continuous spike and waves during sleep is not completely understood, but the corticothalamic neuronal network involved in physiologic oscillating patterns of sleep is thought to be switched into a pathologic discharging mode. Early developmental injury and/or genetic predisposition may play a role in the potentiation of age-related hyperexcitability in the immature brain. A better understanding of the mechanisms leading to electrical status epilepticus during sleep may provide additional therapeutic targets that can improve the outcome of seizures, EEG pattern, and cognitive development in patients with continuous spike and waves during sleep.

Localization of pediatric seizure semiology

OBJECTIVE

The aim of this study was to evaluate the relationship between semiology of seizures in children and adolescents to the corresponding EEG localization.

METHODS

Charts of 225 consecutive pediatric epilepsy patients undergoing Video-EEG monitoring (VEM) over 2 years were reviewed. Seizure semiology recorded during VEM was classified according to ILAE seizure semiology terminology and EEG localization, and analyzed based on onset as defined by the EEG data (generalized, frontal, temporal, parietal, occipital or multilobar).

RESULTS

A total of 1008 seizures were analyzed in 225 children (mean age 8.5 years, range 0-20), with 50% boys. Auras and seizures with automatisms arose predominantly from the temporal lobes (p<0.001). Tonic, clonic and tonic-clonic seizures had most commonly generalized onset (p<0.001). Hypomotor seizures were most frequently seen from the frontal lobes (p<0.001). Hypermotor seizures had most commonly temporal lobe or multiple lobe onset (p<0.001 and p<0.05 respectively). Atonic, myoclonic seizures and epileptic spasms had almost exclusively a generalized onset (p<0.001).

CONCLUSIONS

Different seizure semiologies relate to specific brain regions, with overlap between focal and generalized semiological seizure types, as identified electrographically.

SIGNIFICANCE

Semiology of seizures can provide important information for epilepsy localization, and should not be overlooked, especially in patients undergoing pre-surgical evaluation. Separation of clinical seizure description and EEG findings may be useful, in particular when only incomplete information is available. i.e. during the first office visit.

The prevalence and management of epilepsy in secondary school pupils with and without special educational needs

OBJECTIVES

The objectives of this paper were to (i) determine the prevalence of epilepsy (including the various epilepsies and epilepsy syndromes) in a secondary school population; and (ii) compare the management of epilepsy between secondary school pupils with and without special educational needs.

METHODS

Retrospective observational study of a 250, 000 population (West Cheshire Health District). Pupils attending secondary school with epilepsy over a 1-year period were identified from the local Child Health Computer, school nurse and DGH records. Health records were examined to determine the prevalence, characteristics and management of the epilepsy, and the presence of any special educational needs, other learning difficulties or physical disability.

RESULTS

The prevalence of epilepsy was 4.1 per 1000, being 10 times higher among adolescents who had special educational needs. Pupils with epilepsy and special educational needs had more poorly controlled epilepsy, but did not have a higher number of focal seizures nor were they taking a greater number of anti-epileptic drugs. A physical disability occurred five times more often in those with special educational needs and epilepsy. While epilepsy in pupils at mainstream school without special educational needs was better controlled, one-fifth of these subjects had poorly controlled epilepsy and a few also had physical disabilities.

CONCLUSIONS

Epilepsy is more challenging to control in adolescents with special educational needs attending special schools. However, some pupils in mainstream secondary schools had poorly controlled epilepsy even when they did not have recognized special educational needs. Health and education professionals working across the range of secondary school environments need to be able to support pupils with challenging epilepsy, many of whom will also have special educational needs and some a physical disability, as an increasing number of adolescents with these difficulties are being placed in mainstream schools.

Computer modelling of epilepsy

Epilepsy is a complex set of disorders that can involve many areas of the cortex, as well as underlying deep-brain systems. The myriad manifestations of seizures, which can be as varied as déjà vu and olfactory hallucination, can therefore give researchers insights into regional functions and relations. Epilepsy is also complex genetically and pathophysiologically: it involves microscopic (on the scale of ion channels and synaptic proteins), macroscopic (on the scale of brain trauma and rewiring) and intermediate changes in a complex interplay of causality. It has long been recognized that computer modelling will be required to disentangle causality, to better understand seizure spread and to understand and eventually predict treatment efficacy. Over the past few years, substantial progress has been made in modelling epilepsy at levels ranging from the molecular to the socioeconomic. We review these efforts and connect them to the medical goals of understanding and treating the disorder.

Etiology and management of refractory epilepsies

The epilepsies are an important, common and diverse group of symptom complexes characterized by recurrent spontaneous seizures. Although many patients with epilepsy have their seizures controlled effectively by antiepileptic drugs (AEDs), about one-third of patients continue to have seizures, despite trying a range of AEDs. Such patients bear the heaviest burden of epilepsy, with increased morbidity and risk of premature mortality. Our current understanding of the refractory epilepsies--the most common of which are focal--is limited; even their definition is problematic. Standard treatments for refractory epilepsies include optimization of existing AED regimens, trials of further AEDs, and, for some patients, therapeutic resective neurosurgery. Recent basic research has explored possible underlying causes of refractory epilepsy, and two main hypotheses have emerged to account for the failure of AED treatment. According to one hypothesis, AEDs might fail because of alterations in the properties of their usual targets. Alternatively, they might fail because multidrug transporter mechanisms limit concentrations of the drugs at their targets. The refractory epilepsies can be viewed as offering remarkable insights into biological processes in the epilepsies, and their effective treatment remains an important aim; treatment would potentially bring much-needed relief to hundreds of thousands of patients across the world.

The validity of a separate classification of cryptogenic localization related epilepsy amongst childhood epilepsies

INTRODUCTION

One-third of children with epilepsy are classified as having a cryptogenic localization related epilepsy (CLRE). In cohort studies CLRE is often grouped together with either symptomatic localization related epilepsy (SLRE) or idiopathic generalized epilepsy (IGE). Therefore, this categorization is not specific enough and will not lead to prognostic or treatment information. We objectified the classification differences between these categories.

METHODS

A total of 114 children admitted to our epilepsy centre underwent a standardized clinical analysis, which yielded age at onset, duration of the epilepsy, seizure frequency, seizure type, percentage of interictal epileptiform activity on EEG (IEA), type of treatment, and full scale IQ. These variables are regarded the characteristics of the epilepsy, and used in a discriminant function analysis.

RESULTS

IEA was found to be the only variable to distinguish between groups of epilepsy. SLRE could easily be distinguished significantly from IGE and CLRE, while the latter two did not differ significantly. Discriminant function analysis combined the variables into two functions, applicable to classify the children. By applying this statistical analysis method, the groups clinically classified as SLRE and IGE were mostly classified as SLRE (71.4%) and IGE (57.9%). However, CLRE appeared difficult to classify (49.2%), and most children were classified as either SLRE (19%) or IGE (31.7%).

CONCLUSION

The current opinion that CLRE is 'probably symptomatic' cannot be confirmed in all cases in this study. It is most likely that the current CLRE population consists of both children with eventually SLRE, as well as yet to be described syndromes to be classified as idiopathic epilepsies. We emphasize the need for separate studies regarding children with 'probably symptomatic' (cryptogenic) localization related epilepsy, as this will maximally help children, caretakers and treating physicians to achieve the best possible outcome.

Does SISCOM Contribute to Favorable Seizure Outcome after Epilepsy Surgery?

PURPOSE

To assess the additional value of subtraction ictal single-photon emission computed tomography (SPECT) coregistered to MRI (SISCOM) for localization of the epileptogenic zone in patients with drug-resistant epilepsy scheduled for invasive video-EEG (VEEG) before epilepsy surgery by a descriptive study from clinical practice.

METHODS

Forty-nine consecutive epilepsy patients between January 2000 and March 2006 were included. Thirty-six of the 49 patients were offered surgery, and 34 underwent resective surgery during the study period. Localizing and outcome data are presented from 31 patients with a follow-up period of >or=12 months. Successful ictal SPECT was performed in 26 patients, and SISCOM showed significant hyperperfusions with 3.5 SD above reference. Twenty patients had SISCOM-guided electrode placement, invasive monitoring, and 1-year postsurgical follow-up data. Two independent epileptologists evaluated whether SISCOM results (a) altered the hypothesis and extended the strategy for electrode placement at invasive recording, or (b) were confirmatory of other localizing data and did not alter the strategy. We defined that SISCOM had an impact on seizure outcome if the seizure-onset zone was seen in electrodes overlying a brain region with a significant hyperperfusion. When SISCOM was concordant with ictal onset in the extended electrodes, SISCOM was considered a prerequisite for the outcome at postoperative follow-up.

RESULTS

SISCOM findings altered and extended the strategy for electrode placement at invasive recording in 15 patients (group A). SISCOM was a prerequisite for seizure outcome in all six patients with favorable outcomes. Nine patients had poor results from surgery in this group; SISCOM was concordant with invasive VEEG in six patients, and discordant with invasive VEEG in three patients. SISCOM findings were confirmatory with other localizing data and did not alter the strategy at invasive recording in five patients (group B). Two patients had favorable surgical outcomes. In this group, three patients had poor results; SISCOM and other localizing findings were concordant with invasive VEEG in one patient and discordant with invasive VEEG in two patients.

CONCLUSIONS

SISCOM is valuable for the identification of the epileptogenic zone in patients with drug-resistant epilepsy scheduled for invasive VEEG. SISCOM analysis was either a prerequisite for favorable result or concordant with other localizing methods in all patients with favorable seizure outcome at 1 year of follow-up [40%; confidence interval (CI), 19-64).

Vorschlag für eine neue patientenorientierte Epilepsieklassifikation

The recent proposal by the ILAE Task Force for Epilepsy Classification is a multiaxial, syndrome-oriented approach. Epilepsy syndromes--at least as defined by the ILAE Task Force--group patients according to multiple, usually poorly defined parameters. As a result, these syndromes frequently show significant overlap and may change with patient age. We propose a five-dimensional and patient-oriented approach to epilepsy classification. This approach shifts away from syndrome orientation, using independent criteria in each of the five dimensions similarly to the diagnostic process in general neurology. The main dimensions of this new classification consist of (1) localizing the epileptogenic zone, (2) semiology of the seizure, (3) etiology, (4) seizure frequency, and (5) related medical conditions. These dimensions characterize all information necessary for patient management, are independent parameters, and include information more pertinent than the ILAE axes with regard to patient management. All cases can be classified according to this five-dimensional system, even at initial encounter when no detailed test results are available. Information from clinical tests such as MRI and EEG are translated into the best possible working hypothesis at the time of classification, allowing increased precision of the classification as additional information becomes available.

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.

ILAE classification of epilepsy syndromes

The efforts of the International League against Epilepsy (ILAE) to devise classifications of the epilepsies has greatly improved communication among epileptologists and influenced both basic and clinical research. Several classifications have been proposed since 1970; the most recent classification of epilepsy syndromes and epilepsies was published in 1989. Since 1997, the ILAE Task Force on Classification and Terminology has been evaluating this classification and some modifications have been recommended. Although the 1989 classification can be criticized and needs to be updated, it has been widely accepted and is universally employed. Consequently, the Task Force has agreed not to propose a replacement until a clearly better classification can be created.

Classification of partial seizure symptoms in genetic studies of the epilepsies

OBJECTIVES

To develop standardized definitions for classification of partial seizure symptoms for use in genetic research on the epilepsies, and evaluate inter-rater reliability of classifications based on these definitions.

METHODS

The authors developed the Partial Seizure Symptom Definitions (PSSD), which include standardized definitions of 41 partial seizure symptoms within the sensory, autonomic, aphasic, psychic, and motor categories. Based on these definitions, two epileptologists independently classified partial seizures in 75 individuals from 34 families selected because one person had ictal auditory symptoms or aphasia. The data used for classification consisted of standardized diagnostic interviews with subjects and family informants, and medical records obtained from treating neurologists. Agreement was assessed by kappa.

RESULTS

Agreement between the two neurologists using the PSSD was "substantial" or "almost perfect" for most symptom categories.

CONCLUSIONS

Use of standardized definitions for classification of partial seizure symptoms such as those in the Partial Seizure Symptom Definitions should improve reliability and accuracy in future genetic studies of the epilepsies.

Cryptogenic localization-related epilepsy with childhood onset: The problem of definition and prognosis

BACKGROUND

Up to one-third of children with epilepsy are diagnosed with cryptogenic localization-related epilepsy (CLRE). CLRE is a large nonspecific category within the ILAE classification. For this population no unequivocal prognosis exists.

METHODS

Twenty-five articles describing aspects of CLRE were included in this review.

RESULTS

As a result of the progress in epilepsy research, as well as more advanced investigation in individual cases, the population with CLRE constantly changes. Also, disagreement on interpretation of the classification has resulted in striking differences between the populations described. High remission rates are reported, but relapse occurs frequently, leaving the long-term prognosis unforeseeable. This is reflected in academic and psychosocial prognosis, which is described to be problematic in CLRE specifically. Possible prognostic factors of CLRE in children have been identified: age at onset, seizure semiology, seizure frequency, intractability, interictal epileptiform activity on EEG, and premorbid IQ. These factors are explored to define subgroups within the CLRE population.

DISCUSSION

Prospective studies on well-defined CLRE cohorts are needed to identify factors that distinguish various prognostic subgroups. Specific attention should be focused on course of the epilepsy, scholastic achievement, and psychosocial outcome.

Withdrawal of antiepileptic drugs in adult patients free of seizures for 4 years: a prospective study

We aimed to assess the relapse rate of epilepsy, prospectively attributable to antiepileptic drug (AED) withdrawal in seizure-free patients and to determine the risk factors for seizure recurrence. Seventy-nine patients with epilepsy who were seizure-free for at least 4 years were enrolled into the study. The AEDs were tapered by one-sixth every 2 months. The EEG and clinical examination were performed at the beginning; at each visit during discontinuation and 2, 6, 12, 24, and 36 months after the complete drug withdrawal. For each patient, records were obtained of the main demographic and clinical variables. A total of 49 patients completed the discontinuation programme. Twenty-eight patients (57%) relapsed while 21 of those (42.8%) did not suffer a relapse at the end of the study period. In patients discontinuing treatment, the probability of relapse was 21.4% during the tapering period (especially in the last months), 28.6% at 1 month, 14.3% at 3 months, 3.6% at 6 months, 7.1% at 12 months, 17.8% at 24 months, and 7.1% at 36 months. The age at onset of epilepsy and the duration of active disease were found to affect the risk of relapse. Although drug withdrawal could be considered in adult patients free of seizures for 4 years, the final decision should be tailored to the patient's clinical, emotional, and socio-cultural profile.

Diagnoses made in a secondary care "fits, faints, and funny turns" clinic

AIMS

To investigate the diagnoses made for children referred to a "fits, faints, and funny turns" clinic.

METHODS

Prospective study of 380 children referred to a dedicated secondary care clinic over an eight year period.

RESULTS

Twenty three per cent of children were given a final diagnosis of one of the childhood epilepsies, with 48% of these having a specific epilepsy syndrome. Syncope was the commonest cause of a non-epileptic event (syncope and reflex anoxic seizures comprised 100/238, 42%) but there were a wide variety of other causes. Fifty three events (14%) were unclassified and managed without a diagnostic label or treatment.

CONCLUSIONS

In children with funny turns referred to secondary care, the diagnostic possibilities are numerous; among non-epileptic events, syncopes predominate. The majority do not have epilepsy. Unclassifiable events with no clear epileptic or non-epileptic cause are common and can be safely managed expectantly.

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).

Incidence of unprovoked seizures and epilepsy in Iceland and assessment of the epilepsy syndrome classification: a prospective study

BACKGROUND

No population-based incidence studies of epilepsy have studied syndrome classification from the outset. We prospectively studied the incidence of a single unprovoked seizure and epilepsy in the population of Iceland, and applied the syndrome classification endorsed by the International League Against Epilepsy to this population.

METHODS

We used a nationwide surveillance system to prospectively identify all residents of Iceland who presented with a first diagnosis of a single unprovoked seizure or epilepsy between December 1995 and February 1999. All cases were classified by seizure type, cause or risk factors, and epilepsy syndrome.

RESULTS

The mean annual incidence of first unprovoked seizures was 56.8 per 100,000 person-years, 23.5 per 100,000 person-years for single unprovoked seizures, and 33.3 per 100,000 person-years for epilepsy (recurrent unprovoked seizures). Incidence was similar in males and females. Partial seizures occurred in 40% and a putative cause was identified in 33%. Age-specific incidence was highest in the first year of life (130 per 100,000 person-years) and in those 65 years and older (110.5 per 100,000 person-years). Using strict diagnostic criteria for epilepsy syndromes, 58% of cases fell into non-informative categories. Idiopathic epilepsy syndromes were identified in 14% of all cases.

INTERPRETATION

Findings are consistent with incidence studies from developed countries. Although the epilepsy syndrome classification might be useful in tertiary epilepsy centers, it has limited practicality in population studies and for use by general neurologists.

Lateralizing signs during seizures in focal epilepsy

This article reviews lateralizing semiological signs during epileptic seizures with respect to prediction of the side of the epileptogenic zone and, therefore, presurgical diagnostic value. The lateralizing significance of semiological signs and symptoms can frequently be concluded from knowledge of the cortical representation. Visual, auditory, painful, and autonomic auras, as well as ictal motor manifestations, e.g., version, clonic and tonic activity, unilateral epileptic spasms, dystonic posturing and unilateral automatisms, automatisms with preserved responsiveness, ictal spitting and vomiting, emotional facial asymmetry, unilateral eye blinking, ictal nystagmus, and akinesia, have been shown to have lateralizing value. Furthermore, ictal language manifestations and postictal features, such as Todd's palsy, postictal aphasia, postictal nosewiping, postictal memory dysfunction, as well as peri-ictal water drinking, peri-ictal headache, and ipsilateral tongue biting, are reviewed. Knowledge and recognition of semiological lateralizing signs during seizures is an important component of the presurgical evaluation of epilepsy surgery candidates and adds further information to video/EEG monitoring, neuroimaging, functional mapping, and neuropsychological evaluation.

The diagnostic value of initial video-EEG monitoring in children—Review of 1000 cases

OBJECTIVE

We retrospectively reviewed the clinical utility of initial video-EEG monitoring in a series of 1000 children suspected of epileptic disorders.

METHODS

The ages of patients (523 boys and 477 girls) ranged from 1 month to 17 years (median age: 7 years). The mean length of stay was 1.5 days (range: 1-10 days). Outcomes were classified as: 'useful-epileptic' (successful classification of epilepsy), 'useful-nonepileptic' (demonstration of nonepileptic habitual events), 'uneventful' (normal EEG without habitual events captured), and 'inconclusive' (inability to clarify the nature of habitual events with abnormal interictal EEG findings).

RESULTS

A total of 315 studies were considered 'useful-epileptic'; 219 'useful-nonepileptic'; 224 'uneventful'; 242 'inconclusive'. Longer monitoring was associated with higher rate of a study classified as 'useful-epileptic' in all age groups (Chi square test: p<0.001). In addition, longer monitoring was associated with lower rate of a study classified as 'inconclusive' in adolescences (p<0.001). Approximately half of the children with successful classification of epilepsy were assigned a specific diagnosis of epilepsy syndrome according to the International League Against Epilepsy (ILAE) classification. We found only 22 children with ictal EEG showing a seizure onset purely originating from a unilateral temporal region.

CONCLUSION

Video-EEG monitoring may fail to capture habitual episodes. To maximize the utility of studies in the future, a video-EEG monitoring longer than 3 days should be considered in selected children such as adolescences with habitual events occurring on a less than daily basis. We recognize a reasonable clinical utility of the current ILAE classification in the present study. It may not be common to identify children with pure unilateral temporal lobe epilepsy solely based on video-EEG monitoring.