Idiopathic Generalized Epilepsy with Absences: Syndrome Classification

In a cohort of 275 Caucasians with a broad IGE phenotype, patients with absences were classified. Criteria of the 1989 Commission on Classification of the International League Against Epilepsy for Childhood Absence Epilepsy (CAE 1989 criteria) were compared with the stricter criteria of the ILAE Task Force for Classification and Terminology (CAE 2005 criteria). Among the 129 patients with absences without significant myoclonus, 50 had juvenile absence epilepsy 44 had CAE according to the CAE 1989 criteria and only 30 had CAE according to the CAE 2005 criteria. We found a significantly better outcome in patients considered as CAE by the CAE 2005 criteria, compared with those excluded. Strict criteria for classification of absence syndromes leave many patients unclassified. However, diagnostic criteria used to classify CAE patients have prognostic significance. We propose that patients are classified as having benign CAE or as having CAE with the adverse prognostic factors indicated.

Familial generalized epilepsy in Bulgarian Roma

AIMS

Gypsy communities constitute cultural and frequently inbred genetic isolates. Several genetic neurological disorders have been identified in these communities. Epilepsy appears as a fairly frequent medical condition among Bulgarian Gypsies, and many patients can be related to large pedigrees that may then be studied by conventional genetic linkage analyses.

PATIENTS AND METHODS

We identified two large Wallachian Gypsy families from the Plovdiv and Varna regions of Bulgaria, with detailed clinical questionnaires and examination, and EEG recordings for many. Genetic linkage analysis was performed using microsatellite markers spaced across the human genome.

RESULTS

Although phenotypes were not always easy to identify, epilepsy appears in both families as a dominant, or pseudo-dominant trait, with the characteristics of idiopathic generalized epilepsy with onset at various ages, with infrequent, generalized tonic-clonic seizures, some associated with fever in childhood, but without sensitivity to fever in later life. While few markers yielded LOD scores > 2, no locus showed significant linkage, assuming autosomal dominant or recessive modes of inheritance.

CONCLUSION

Idiopathic generalized epilepsy, with a marked familial character, has not been reported to date in Bulgarian Gypsies. Both pedigrees studied here present with an identifiable epilepsy type inherited as a Mendelian trait. Despite the current lack of significant linkage, these families may constitute interesting ground for further genetic studies, on condition that more patients and families can be recruited. [Published with supplemental data on DVD].

Long-term Prognosis for Symptomatic (Secondarily) Generalized Epilepsies: A Population-based Study

PURPOSE

To describe the long-term outcome of childhood-onset secondarily generalized epilepsies (SGEs).

METHODS

Children were identified from the Nova Scotia population-based epilepsy study (n=692). Onset of epilepsy was between 1977 and 1985, and follow-up was mainly in 2003. SGE was defined as having a mixture of more than one generalized seizure types including myoclonus, akinetic/atonic, tonic, or atypical absence, plus an interictal EEG with generalized spike-wave (irregular or slow) and/or multifocal spikes.

RESULTS

SGE was identified in 80 children, 11.6% (80 of 692) of all childhood epilepsy. Forty percent did not fit into a currently accepted syndrome (such as Lennox-Gastaut, myoclonic-astatic or West). Seizure onset was in the first year of life in 60%, with only 9% later free of intellectual or physical handicap. Sixty-five percent (11 of 17) with Lennox-Gastaut had preceding West syndrome. During a median follow-up of 20 years, mortality was 24% (n=19), and 53% (n=42) had persistently intractable seizures. Surprisingly, 22 (28%) had >or=5 years of terminal remission (West, 31%, 10 of 32; Lennox-Gastaut, 0, none of four; myoclonic-astatic, 56%, five of nine; undefined, 31%, 10 of 32). At the end of follow-up, nearly 90% of patients fell into one of three outcome categories: death, 19 (24%); alive with intractable epilepsy, 31 (39%); or in remission for >or=5 years, 21 (26%).

CONCLUSIONS

Many children with SGE have ill-defined epilepsy syndromes. SGE is characterized by early age at onset, high rates of handicap, intractability, and death, although one third achieve complete seizure control with a long terminal remission.

Executive functioning in childhood epilepsy: parent-report and cognitive assessment

There is considerable interest in the assessment of executive function (EF) in pediatric clinical populations but only a few well-standardized measures exist. We examined EF in 53 children aged 8 to 18 years with recent onset epilepsy (31 males, 22 females) and 50 control children (23 males, 27 females) using the Behavior Rating Inventory of Executive Function (BRIEF) and the Delis-Kaplan Executive Function System (D-KEFS). Thirty children had localization-related epilepsy and 23 had idiopathic generalized epilepsy; average duration of 10 months (SD 4y 1mo) and onset age of 11 years 6 months (SD 3y 6mo). The study sample was characterized by good seizure control, with 40 participants taking one antiepileptic drug (AED), one taking two AEDs, and 12 not treated pharmacologically. Children with epilepsy showed greater executive difficulties on both measures than children in the control group. The BRIEF and D-KEFS were significantly correlated, and an 'at-risk' group identified from the BRIEF was more significantly impaired on the D-KEFS than a 'low risk' group. The BRIEF was also a better predictor of performance on the D-KEFS than the Child Behavior Checklist. These findings indicate that children with recent onset epilepsy show significant difficulties in E F, and demonstrate the utility of parent ratings (BRIEF) in the assessment of EF.

"Tonic-absence seizures": an unusual seizure phenotype, but not necessarily in that order

Video telemetry in a 15-year-old boy with moderate learning difficulties revealed episodes of staring and cessation of activity, followed by sudden stiffening of the body for several seconds, abduction of the arms and a brief vocal utterance ("ugh"). Each episode lasts around 30 seconds, 3-4 times/day despite treatment. The EEG showed generalized 3-4Hz spike-wave discharges during the "absence" period followed immediately by a run of fast polyspikes typical of a tonic seizure, terminating in a run of 1-2 Hz sharp-slow wave complexes. Although tonic-absence seizures have been reported rarely, the clinical sequence appears to be reversed in this patient, with the occurrence of "absence-tonic" attacks. We present video documentation of such attacks and discuss their nosology.[Published with video sequences].

A study of idiopathic generalised epilepsy in an Irish population

Idiopathic generalised epilepsy (IGE) is subdivided into syndromes based on clinical and EEG features.

PURPOSE

The aim of this study was to characterise all cases of IGE with supportive EEG abnormalities in terms of gender differences, seizure types reported, IGE syndromes, family history of epilepsy and EEG findings. We also calculated the limited duration prevalence of IGE in our cohort.

METHODS

Data on abnormal EEGs were collected retrospectively from two EEG databases at two tertiary referral centres for neurology. Clinical information was obtained from EEG request forms, standardised EEG questionnaires and medical notes of patients.

RESULTS

two hundred twenty-three patients met our inclusion criteria, 89 (39.9%) male and 134 (60.1%) females. Tonic clonic seizures were the most common seizure type reported, 162 (72.65%) having a generalised tonic clonic seizure (GTCS) at some time. IGE with GTCS only (EGTCSA) was the most common syndrome in our cohort being present in 94 patients (34 male, 60 female), with 42 (15 male, 27 female) patients diagnosed with Juvenile myoclonic epilepsy (JME), 23 (9 male, 14 female) with Juvenile absence epilepsy (JAE) and 20 (9 male, 11 female) with childhood absence epilepsy (CAE). EEG studies in all patients showed generalised epileptiform activity.

CONCLUSIONS

More women than men were diagnosed with generalised epilepsy. Tonic clonic seizures were the most common seizure type reported. EGTCSA was the most frequent syndrome seen. Gender differences were evident for JAE and JME as previously reported and for EGTCSA, which was not reported to date, and reached statistical significance for EGTCA and JME.

Auras are frequent in idiopathic generalized epilepsy

The occurrence of an aura is often considered evidence of a partial rather than an idiopathic generalized epilepsy syndrome. The authors examined this hypothesis by prospectively recording reports of auras by patients being admitted for video-EEG monitoring. Auras were equally common (70%) among patients with idiopathic generalized epilepsy as they were among those with localization-related epilepsy. Presence of an aura is not a reliable indicator of localization-related epilepsy.

Prevalence of Epilepsy in a Rural District of Central Lao PDR

PURPOSE

To assess the prevalence of epilepsy in a rural district of Lao PDR and to describe the clinical and epidemiological profile of the disease.

METHODS

Door-to-door screening was performed on the entire population of 8 randomly selected villages in the Hinheub district, using an internationally validated and standardized questionnaire. Additional passive case detection was performed through village key informants. Suspected epilepsy patients identified by the questionnaire were revisited and examined by an experienced neurologist on two follow-up visits. The confirmation of epilepsy was based only on an in-depth clinical examination. Electroencephalograms were performed at the district health care center.

RESULTS

In the 8 villages, 277 suspected cases of epilepsy were identified among 4,310 interviewed subjects; 194 of whom (70%) underwent a clinical examination by a neurologist during the first visit while 65 of 83 remaining suspected cases were seen on the second confirmation visit. Twenty-seven persons with epilepsy were identified. Six additional patients were diagnosed in 219 self-referred subjects. An overall prevalence of 7.7 cases of epilepsy per thousand inhabitants was calculated (95% CI 5.3-10.7). Generalized epilepsy (21 cases, 63.6%) was commoner than partial epilepsy (9 cases, 27.3%). The remaining 3 cases (9.1%) were not-classifiable as either generalized or partial. EEG abnormal findings were found in 12 of the 24 patients (50.0%) who had an EEG registration.

CONCLUSIONS

This is the first study in Lao PDR to estimate the prevalence of epilepsy. Compared to Western countries it shows a pattern towards a higher prevalence.

Language-induced Epilepsy, Acquired Stuttering, and Idiopathic Generalized Epilepsy: Phenotypic Study of One Family

PURPOSE

Language-induced epilepsy involves seizure precipitation by speaking, reading, and writing. Seizures are similar to those of reading epilepsy (RE). The nosologic position of language-induced epilepsy is not clear. We performed a clinical and neurophysiological study in a multigenerational family with the association of idiopathic generalized epilepsy (IGE) with ictal stuttering as a manifestation of reflex language-induced epilepsy.

METHODS

Nine members on three generations were studied. All patients underwent video-polygraphic EEG recordings (awake and during sleep). A standardized protocol was applied to test the effect of language and non-language-related tasks.

RESULTS

Six patients presented language-induced jaw jerking that mimicked stuttering and corresponded to focal myoclonus involving facial muscles. This was associated with an IGE phenotype in four of these patients. Focal EEG spikes were found in all six patients by visual analysis and/or back-averaging techniques. The focal spikes were either asymptomatic (when followed by a slow wave) or symptomatic of facial myoclonia (when isolated). Levetiracetam, used as add-on or monotherapy in four patients, suppressed ictal stuttering. One additional case only had a phenotype of IGE without focal features.

CONCLUSIONS

This family study demonstrates the phenotypic heterogeneity of the association of IGE phenotype with ictal stuttering (language-related reflex seizure). Our data suggest that this particular form of reflex epilepsy related to language has more similarities with generalized epilepsies than with focal ones. Neurophysiological investigations should be performed more systematically in patients with acquired stuttering, especially if there is family history of IGE.

Epilepsy and obstructive sleep apnea

A few publications documented the coexistence of epilepsy and obstructive sleep apnea (OSA). The extent, nature, and clinical relevance of this association remain poorly understood. We retrospectively reviewed the database of our sleep center to identify patients with both sleep apnea and epilepsy. Characteristics of epilepsy, sleep history, presence of excessive daytime sleepiness [Epworth Sleepiness Scale (ESS)] and polysomnographic data were assessed. The effect of continuous positive airway pressure (CPAP) on seizure reduction was prospectively analyzed after a median interval of 26 months (range: 2-116 months) from the diagnosis of OSA. OSA was found in 29 epilepsy patients (25 men and 4 women) with a median age of 56 years (range: 37-79). The median apnea hypopnea index was 33 (range: 10-85), the oxygen desaturation index was 12 (range 0-92), and 52% of the patients had an ESS score >10. In 27 patients, epilepsy appeared 1 month to 44 years prior to the diagnosis of OSA. In 21 patients, the appearance of OSA symptoms coincided with a clear increase in seizure frequency or the first appearance of a status epilepticus. Treatment with CPAP was continued with good compliance in 12 patients and led to a significant reduction of both ESS scores and seizure frequency in 4 patients. Our data suggest the importance of considering diagnosis and treatment of OSA in epilepsy patients with poor seizure control and/or reappearance of seizures after a seizure-free interval.

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).

Clinical and electroencephalographic study of first-degree relatives and probands with juvenile myoclonic epilepsy

PURPOSE

Juvenile myoclonic epilepsy (JME) is a common, well-defined epileptic syndrome. This study aims to examine the clinical and EEG features of probands with JME and to identify the incidence of different types of idiopathic generalized epilepsies (IGEs) and IGE trait in first-degree relatives.

METHODS

Clinical and EEG data were collected from 132 first-degree relatives and 31 probands with JME. The data were analyzed using descriptive statistics, chi-square test, t-test and ANOVA.

RESULTS

All probands had a history of generalized tonic clonic seizures (GTCS) and myoclonic jerks; 25.8% had a history of absence seizures. Family history of epilepsy was noted in 42% and epilepsy in first-degree relatives was reported in 38.7%. We found JME in 44% of the symptomatic first-degree relatives. The incidence of epilepsy was higher in siblings (19%) than in offspring (8%) or parents (4%), the difference between the groups being significant (p < 0.05). IGE trait was noted in 6% of the asymptomatic first-degree relatives. Finally, IGE features were found in 61%. Subjects with IGE features were younger (mean age 19.6 years) than those without IGE features (mean age 32.4 years) and the difference between the groups was significant.

CONCLUSION

The incidence of different kinds of IGEs and typical EEG trait is high in first-degree relatives of JME probands. IGE features were noted in 61% of the families. JME is the most common type of IGE and IGE features were found to be more frequent among siblings than parents. These findings confirm familial susceptibility to IGE.

Prevalence of active epilepsy in a rural area in South Tanzania: a door-to-door survey

OBJECTIVE

A door-to-door survey was carried out to assess the prevalence of active epilepsy in the rural population within the catchment area of the Mnero Diocesan Hospital in Southern Tanzania.

METHODS

A total of 4,905 individuals living in 1,047 households were enrolled in a study, consisting of a screening dialogue with a representative family member followed by a face-to-face interview with the affected subject. The diagnosis of epilepsy followed clinical guidelines proposed by the International League Against Epilepsy (ILAE).

RESULTS

We detected 42 cases (21 males and 21 females) of active epilepsy (8.6/1,000; 95% CI: 6.0/1,000-11.1/1,000; age-adjusted prevalence ratio: 7.4/1,000). Thirty of them met the case definitions of generalized seizures, whereas 12 patients reported partial seizures. The peak prevalence was found in both sexes in the second decade of life (f: 16.9/1,000; m: 15.8/1,000; t: 16.4/1,000), with a second peak in the group aged 30-39 years (f: 10.4/1,000; m: 8.8/1,000; t: 9.7/1,000). Eleven patients (26.2%) were classified as "strongly suspected of symptomatic" epilepsy, the remaining 31 patients (73.8%) as possibly being idiopathic, symptomatic, or cryptogenic epilepsy cases.

DISCUSSION

This study provides baseline data about the active epilepsy prevalence in a rural African population. Compared to western countries, our study confirmed a pattern toward higher prevalence of epilepsy in tropical countries. As shown in previous studies, we observed a higher prevalence of epilepsy in children and adolescents, followed by a steady decline with increasing age. Reasons for this type of frequency could be ascribed to malnutrition, trauma, genetic conditions, antenatal and prenatal care, diseases resulting in febrile convulsions, cerebral infections and may even result in death in specifically diseased individuals.

Familial clustering of seizure types within the idiopathic generalized epilepsies

OBJECTIVE

To examine the genetic relationships among epilepsies with different seizure types--myoclonic, absence, and generalized tonic-clonic--within the idiopathic generalized epilepsies (IGEs).

BACKGROUND

Careful phenotype definition in the epilepsies may allow division into groups that share susceptibility genes. Examination of seizure type, a phenotypic characteristic less complex than IGE syndrome, may help to define more homogeneous subgroups.

METHODS

Using the approach that found evidence of distinct genetic effects on myoclonic vs absence seizures in families from the Epilepsy Family Study of Columbia University, the authors examined an independent sample of families from Australia and Israel. They also examined the familial clustering of generalized tonic-clonic seizures (GTCs) within the IGEs in two combined data sets. Families were defined as concordant if all affected members had the same type of seizure or IGE syndrome, as appropriate for the analysis performed.

RESULTS

The proportion of families concordant for myoclonic vs absence seizures was greater than expected by chance in the Australian families. In addition, GTCs clustered in families with IGEs to a degree greater than expected by chance.

CONCLUSIONS

These results provide additional evidence for distinct genetic effects on myoclonic vs absence seizures in an independent set of families and suggest that there is a genetic influence on the occurrence of generalized tonic-clonic seizures within the idiopathic generalized epilepsies.

A case of extended spectrum GEFS+

A 10-year-old boy developed febrile convulsions at age 2 years, and multiple types of nonfebrile generalized seizures over the ensuing months and years. Gestation, birth, and early development were normal, as were initial EEG and brain imaging studies. By age 5 years, he had developed behavioral difficulties, and the EEG demonstrated both interictal and ictal generalized epileptiform patterns, as well as mild background slowing. Seizures were poorly controlled with multiple medication trials. There was a strong family history of clinically benign febrile seizures in the maternal lineage. Genetic analysis revealed a novel mutation in the voltage-gated neuronal sodium channel SCN1A. This patient's relatively malignant clinical course is consistent with "extended spectrum" generalized epilepsy with febrile seizures plus (GEFS+), and along with the family history illustrates the phenotypic variability of this disease.

Neonatal epilepsy syndromes and GEFS+: mechanistic considerations

Genetic analyses of familial epilepsies over the past decade have identified mutations in several different ion channel genes that result in neonatal or early-onset seizure disorders, including benign familial neonatal convulsions (BFNC), generalized epilepsy with febrile seizures plus (GEFS+), and severe myoclonic epilepsy of infancy (SMEI). These genes encode voltage-gated Na+ channel subunits (SCN1A, SCN2A, SCN1B), voltage-gated K+ channel subunits (KCNQ2, KCNQ3), and a ligand-gated neurotransmitter receptor subunit (GABRG2). While the opportunity to genotype patients for mutations in these genes can have an immediate and significant impact on our ability to diagnose and provide genetic counseling to patients, the ultimate goal is to use this molecular knowledge to develop effective treatments and cures for each disorder. This will necessitate elucidation of the molecular, cellular, and network mechanisms that translate ion channel defects into specific epilepsy phenotypes. The functional analysis of epileptogenic channel mutations in vitro and in vivo has already provided a vast amount of raw biophysical data, but attempts to interpret these data to explain clinical phenotypes so far appear to raise as many questions as they answer. Nevertheless, patterns are beginning to emerge from these early studies that will help define the full scope of the challenges ahead while simultaneously providing the foundation of future efforts to overcome them. Here, I discuss some of the potential mechanisms that have been uncovered recently linking mutant ion channel genes to neonatal epilepsy syndromes and GEFS+.

Seizures of idiopathic generalized epilepsies

Idiopathic generalized epilepsies (IGEs) comprise at least 40% of epilepsies in the United States, 20% in Mexico, and 8% in Central America. Here, we review seizure phenotypes across IGE syndromes, their response to treatment and advances in molecular genetics that influence nosology. Our review included the Medline database from 1945 to 2005 and our prospectively collected Genetic Epilepsy Studies (GENESS) Consortium database. Generalized seizures occur with different and similar semiologies, frequencies, and patterns, ages at onset, and outcomes in different IGEs, suggesting common neuroanatomical pathways for seizure phenotypes. However, the same seizure phenotypes respond differently to the same treatments in different IGEs, suggesting different molecular defects across syndromes. De novo mutations in SCN1A in sporadic Dravet syndrome and germline mutations in SCN1A, SCN1B, and SCN2A in generalized epilepsies with febrile seizures plus have unraveled the heterogenous myoclonic epilepsies of infancy and early childhood. Mutations in GABRA1, GABRG2, and GABRB3 are associated with absence seizures, while mutations in CLCN2 and myoclonin/EFHC1 substantiate juvenile myoclonic epilepsy as a clinical entity. Refined understanding of seizure phenotypes, their semiology, frequencies, and patterns together with the identification of molecular lesions in IGEs continue to accelerate the development of molecular epileptology.

Syndromes of idiopathic generalized epilepsies not recognized by the International League Against Epilepsy

This chapter assesses probable epileptic syndromes within the idiopathic generalized epilepsies (IGE) that have not yet been recognized by the International League Against Epilepsy (ILAE). Jeavons syndrome, a purely reflex IGE that predominantly manifests with eyelid myoclonia and electroencephalogram (EEG) abnormalities on eye closure, is the most distinct and undisputed of the syndromes. Another is autosomal-dominant cortical tremor, myoclonus, and epilepsy, a purely monogenic disorder that has been documented in numerous reports, mainly from Japan and Italy. Perioral myclonia with absences is certainly a seizure type that may constitute an IGE syndrome when it is associated with a number of other clinical and EEG manifestations. Similarly, many patients suffer for years from phantom absences, a type of mild absence, before a first generalized tonic-clonic seizure that usually occurs in adulthood. Both perioral myoclonia with absences and phantom absences are clinically significant because they are probably lifelong and are associated with a very high incidence (around 50%) of absence status epilepticus that may escape diagnosis and appropriate treatment. The position of early childhood IGE, which manifests mainly with typical absence seizures that are distinctly different from childhood absence epilepsy and other recognized IGE syndromes, is less clear. The prevalence of these syndromes is significant. Their identification allows better clinical management and is important for genetic research and counselling. In addition, their recognition permits application of exclusion criteria for a more purified definition and a better understanding of the true boundaries of the other IGE syndromes already accepted by the ILAE.

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.

Nonepileptic disorders imitating generalized idiopathic epilepsies

Differential diagnosis between epileptic and nonepileptic paroxysmal disorders is fundamental not only to allow correct management of patients but also to avoid the burden of unnecessary antiepileptic medication. The focus of this chapter is limited to imitators of idiopathic generalized epilepsies (IGE) which are expressed through myoclonic, tonic-clonic, tonic, atonic, and absence seizures. Apparent losses of consciousness and drop attacks also have to be considered. Benign myoclonus of early infancy is the main nonepileptic disorder in the differential diagnosis of infantile spasms, but is not dealt with here because West syndrome is not an IGE. Hyperekplexia, metabolic disorders, hypnagogic myoclonus, and disturbed responsiveness caused by the use of drugs are listed in Table 1. Other conditions that may imitate more focal epileptic seizures are omitted. Benign neonatal sleep myoclonus, apnea and apparent life-threatening events in infants, cyanotic and pallid breath-holding spells, syncope, staring spells, psychogenic seizures, hyperventilation syndrome, and narcolepsy have been selected based on frequency or difficulties in differential diagnosis with the intention to cover the most conspicuous imitators of IGE in different ages.

Photosensitivity in Idiopathic Generalized Epilepsies

Photosensitivity is an abnormal visual sensitivity of the brain in reaction to flickering light sources or patterns and is expressed in the electroencephalogram as generalized spike-and-wave discharge and in more susceptible individuals as clinical seizures. The most common types of seizures are generalized tonic-clonic, followed by myoclonic and absence. The photosensitive epilepsies are classified as pure photosensitive, where seizures occur only with the flickering light source/pattern or during intermittent photic stimulation (IPS) in the laboratory, and epilepsy with photosensitivity, where spontaneous seizures also occur. Positive response to IPS in idiopathic epilepsy syndromes, which are included in the International Classification or are in development, is reported to range from 7.5% in juvenile absence epilepsy to 100% in pure photosensitive epilepsy. The treatment of photosensitivity and pure photosensitive epilepsy with rare seizures includes general and specific protective measures. For most patients, however, combination treatment with antiepileptic drugs is necessary. Valproic acid monotherapy has a success rate of 73-86%. Levetiracetam appears to be a new alternative therapeutic option. Clobazam, lamotrigine, ethosuximide, and topiramate also have been recommended as second-choice therapies.