The landscape of drug resistant absence seizures in adolescents and adults: Pathophysiology, electroclinical spectrum and treatment options

The persistence of typical absence seizures (AS) in adolescence and adulthood may reduce the quality of life of patients with genetic generalized epilepsies (GGEs). The prevalence of drug resistant AS is probably underestimated in this patient population, and treatment options are relatively scarce. Similarly, atypical absence seizures in developmental and epileptic encephalopathies (DEEs) may be unrecognized, and often persist into adulthood despite improvement of more severe seizures. These two seemingly distant conditions, represented by typical AS in GGE and atypical AS in DEE, share at least partially overlapping pathophysiological and genetic mechanisms, which may be the target of drug and neurostimulation therapies. In addition, some patients with drug-resistant typical AS may present electroclinical features that lie in between the two extremes represented by these generalized forms of epilepsy.

Lack of causal association between epilepsy and dementia: A Mendelian randomization analysis

OBJECTIVE

Epidemiological studies have reported an association between epilepsy and dementia. However, the causal relationship between epilepsy and the risk of dementia is not clear. We aimed to inspect the causal effect of epilepsy on memory loss and dementia.

METHODS

We analyzed summary data of epilepsy, memory loss, and dementia from the genome-wide association study (GWAS) using the two-sample Mendelian randomization (MR) method. We used the estimated odds ratio of memory loss and dementia associated with each of the genetically defined traits to infer evidence for a causal relationship with the following exposures: all epilepsy, focal epilepsy (including focal epilepsy with hippocampal sclerosis, lesion-negative focal epilepsy, and focal epilepsy with other lesions), and genetic generalized epilepsy (including childhood absence epilepsy, generalized tonic-clonic seizures alone, Juvenile absence epilepsy, and Juvenile myoclonic epilepsy).

RESULTS

According to the result of MR using the inverse variance weighted method (IVW), we found that genetically predicted epilepsy did not causally increase the risk of memory loss and dementia (p > 0.05). Results of the MR-Egger and weighted median method were consistent with the IVW method.

CONCLUSIONS

No evidence has been found to support the notion that epilepsy can result in memory loss and dementia. The associations observed in epidemiological studies could be attributed, in part, to confounding or nongenetic determinants.

Childhood Absence Epilepsy- Electroclinical Profile and Prevalence of Attention-Deficit/Hyperactivity Disorder Among a Cohort of 47 Children

BACKGROUND

We aimed to find the proportion of attention-deficit/hyperactivity disorder (ADHD) among children with childhood absence epilepsy (CAE) and to describe their electroclinical features.

METHODS

Video electroencephalography (EEG) was performed on 47 children who fulfilled International League Against Epilepsy criteria for CAE. These children were also assessed for the presence of ADHD.

RESULTS

Of the 47 children, 27 (57%) met criteria for the diagnosis of ADHD. Majority (74%) of them had inattentive type of ADHD. Age at onset of absences ranged from three to 12 years (mean 7.2 ± 2.47). We analyzed 219 seizures (154 electroclinical and 65 electrographic). The average seizure duration was 7.1 seconds (range 1 to 38 [S.D. 5.81]). Of the 154 clinical absences, ictal discharges were less than or equal to two seconds in nine of 154 (5.8%); greater than two to less than or equal to four seconds in 33 of 154 (21.4%), and longer than 20 seconds in 11 of 154 (7%). The longest duration of ictal discharge recorded was 38 seconds, and the shortest duration was one second. The onset of ictal discharge had a "lead in" focus in 81% (177 of 219).

CONCLUSIONS

The proportion of ADHD among children with CAE is high. A "lead in" focus of the generalized ictal discharges was observed frequently, lending support to the theory that the origin of seizure discharges in CAE is indeed cortical. The shortest ictal discharge recorded was one second.

[Scientific evidence on treatment and prognosis of childhood absence epilepsy]

Until now, ethosuximide (ESM), sodium valproate (VPA) and lamotrigine have been considered the drugs of choice in the management of childhood absence epilepsy, and there has been no high-validated evidence to distinguish their effects. New research shows, however, that while VPA and ESM are equally effective, ESM is the best tolerated of the two drugs, when considering cognitive adverse effects. This is of major importance, as cognitive comorbidities can be dire in childhood absence epilepsy, possibly affecting the psychosocial prognosis of the patients. More research is needed in this area.

[A descriptive study of non-symptomatic epilepsy according to age at onset at a Neuropediatric Section of regional reference]

AIM

A descriptive study of non-symptomatic epilepsy (idiopathic and cryptogenic), according to age at onset, monitored at a Neuropediatric Section of regional reference over a period of three years.

PATIENTS AND METHODS

A review of neuropediatric database medical records of children with non-symptomatic epilepsy supervised from Jan 1, 2008 till December 31, 2010.

RESULTS

Of the 4595 children attended during the period, 605 were diagnosed with epilepsy (13.17%): 156 (25.79%) idiopathic epilepsies and 172 (28.43%) cryptogenic epilepsies. The average age at onset of the total was 4.78 years: 6.31 years in idiopathic epilepsies and 5.43 years in cryptogenic epilepsies. 26.12% of all the epilepsies began in the first year of life. Idiopathic epilepsy predominates in the startup group of 6-10 years and cryptogenic epilepsy in 3-6 years. Absence epilepsy and benign childhood epilepsy with centro-temporal spikes are the idiopathic epileptic syndromes most prevalent.

CONCLUSIONS

Many differences exist among published epidemiological data on childhood epilepsy due to the difficulty of a syndromic diagnosis in children, caused by clinical and electroencephalographic variability. The absence of a universally accepted classification of epileptic syndromes makes it difficult to compare publications. All epilepsies are symptomatic as they have a cause, whether it be genetic or acquired. A useful classification would be etiological, with two groups: one large with established etiology or very likely genetic syndromes and another with no established cause. The age at onset indicates specific etiologies.

Quality of life in adolescent absence epilepsy at Queen Sirikit National Institute of Child Health

OBJECTIVE

To compare the QoL between adolescents with absence epilepsy and the other types of epilepsies.

MATERIAL AND METHOD

A prospective cohort study was conducted in adolescents aged 10-18 years that have been diagnosed with epilepsy at QSNICH between 2000 and 2012. The QoL was assessed using the QoLIE-AD-48, Thai version.

RESULTS

Seventy-three adolescents were included in this study, of which 27 had absence epilepsy. The mean total QoLIE-AD-48 score was 63.94 (17.14). The absence group had a mean score of 74.45 (9.83), while the non-absence group had a score of 57.78 (17.57), p-value < 0.001.

CONCLUSION

The QoL of adolescents with inactive absence epilepsy was significantly higher than those suffering with other types of epilepsy. The QoL in this study was similar to prior studies.

Current advances in childhood absence epilepsy

BACKGROUND

Childhood absence epilepsy is an age-dependent, idiopathic, generalized epilepsy with a characteristic seizure appearance. The disorder is likely to be multifactorial, resulting from interactions between genetic and acquired factors, but the debate is still open. We review recent studies on different aspects of childhood absence epilepsy and also to describe new concepts.

METHODS

Data for this review were identified using Medline and PubMed survey to locate studies dealing with childhood absence epilepsy. Searches included articles published between 1924 and 2013.

RESULTS

The diagnosis comprises predominant and associated seizure types associated with other clinical and electroencephalographic characteristics. Many studies have challenged the prevailing concepts, particularly with respect to the pathophysiological mechanisms underlying the electroencephalographic seizure discharges. Childhood absence epilepsy fits the definition of system epilepsy as a condition resulting from the persisting susceptibility of the thalamocortical system as a whole to generate seizures. This syndrome, if properly defined using strict diagnostic criteria, has a good prognosis. In some cases, it may affect multiple cognitive functions determining risk for academic and functional difficulties; the detection of children at risk allows tailored interventions. Childhood absence epilepsy is usually treated with ethosuximide, valproate, lamotrigine, or levetiracetam, but the most efficacious and tolerable initial empirical treatment has not been well defined.

CONCLUSIONS

We review recent studies and new concepts on the electroclinical features and pathophysiological findings of childhood absence epilepsy in order to highlight areas of consensus as well as areas of uncertainty that indicate directions for future research.

The role of SLC2A1 in early onset and childhood absence epilepsies

Early Onset Absence Epilepsy constitutes an Idiopathic Generalized Epilepsy with absences starting before the age of four years. Mutations in SLC2A1, encoding the glucose transporter, account for approximately 10% of EOAE cases. The role of SLC2A1 mutations in absence epilepsies with a later onset has not been assessed. We found two mutation carriers in 26 EOAE patients, while no mutations were found in 124 probands affected by CAE or JAE.

[Atypical absences: prevalence, electroclinical and neuroimaging characteristics]

The study included 1261 patients with different forms of epilepsy. Ages at onset of disease varied from the first days of life to 18 years old. Absence seizures were identified in 231 (18.3%) patients, atypical absences (AA) in 129 (10.2%) of patients, with the frequency of absence seizures 55.8% in the total group. Patients with AA had different forms of epilepsy with the prevalence of cryptogenic/symptomatic forms with the phenomenon of secondary bilateral synchronization in the EEG. If epilepsy manifested itself at the age above 12 years old, AA were not noted. The study demonstrated the relevance of using video-EEG monitoring for diagnosis of epilepsy with AA. The antiepileptic treatment was effective in 53.5% of patients.

Early-onset pure absence epilepsy: a distinct epileptic syndrome

Early-onset pure absence epilepsy has not yet considered in the International League Against Epilepsy classification, but several reports have supported its existence as a distinct epileptic syndrome primarily manifesting with typical absences in early childhood. This review summarizes the current understanding on this epilepsy.

CONCLUSIONS

  Early-onset pure absence epilepsy is a distinct epilepsy characterized by absences starting from a few months to 4 years of age, normal early psychomotor development, good antiepileptic drug seizure control and normal intellectual outcome.

Long term outcome in children affected by absence epilepsy with onset before the age of three years

OBJECTIVE

The goal of this study was to define the long-term outcome of absence epilepsy presenting before the age of 3 years.

METHODS

We retrospectively studied the medical records of 40 children from eight neuropediatric centers in Italy with respect to the personal and family histories of epilepsy or febrile seizures, time of follow-up, cognitive functions, treatment, and outcome.

RESULTS

Forty patients were enrolled in this study. They all fulfilled the criteria for absence epilepsy with 3-Hz spike-wave complexes on the EEG, normal neurological examination, and no other seizures types. Seizure onset occurred between 24.1 and 36.0 months. There was a family history of epilepsy in 28%, and of febrile seizures in 13%. Thirty-three patients were treated with valproic acid (VPA), mostly used in monotherapy (26 patients) or in association with ethosuximide. At final follow-up, 33 patients were seizure free and 29 had normal EEGs. Thirty-four patients had a normal intelligence quotient (IQ), whereas 6 had a decreased IQ, mainly associated with poor control of seizures.

CONCLUSION

In our series, absence seizures presenting before the age of 3 appeared to have quite a good long-term clinical prognosis; the neuropsychological outcome was comparable to that of childhood epilepsy presenting after 3 years of age.

Focal clinical and electroencephalographic features in patients with juvenile myoclonic epilepsy

OBJECTIVE

To identify prevalence and factors associated with occurrence of focal clinical and electroencephalogram (EEG) abnormalities in patients with juvenile myoclonic epilepsy (JME).

MATERIALS AND METHODS

Clinical asymmetries in the seizures and focal EEG abnormalities were analyzed in 266 patients with JME.

RESULTS

All the patients had myoclonic jerks (MJ) and generalized tonic-clonic seizures (GTCS); 56 (21%) had absence seizures. Asymmetry in clinical seizures was reported in 45 (16.9%) and focal EEG abnormalities were noted in 92 (45.5%) patients. Amplitude asymmetry or focal onset of generalized discharges was noted in 41 (44.6%) and independent focal EEG abnormalities in 30 (32.6%) patients. A statistically significant association was seen with the presence of GTCS and MJ (P = 0.007), a family history of epilepsy (P = 0.001) and drug resistance (P = 0.04) and the occurrence of focal EEG abnormalities.

CONCLUSION

Patients with JME showed focal clinical and EEG features. These features should not be misinterpreted as indicative of partial epilepsy.

[Intellectual, psychomotor and speech development of children born to mothers with epilepsy]

Intellectual, psychomotor and speech development of 50 children born to mothers with epilepsy were studied. The sample has been stratified into 2 subgroups: children aged from 6 months to 4 years and children aged from 4 to 16 years. This group included 4 (8%) children with children absence epilepsy, juvenile myoclonic and unclassified epilepsy; one patient had a diagnosis of epileptic encephalopathy without epileptic seizures. Video-EEG monitoring revealed the epileptiform activity on EEG in 9 (18%) children from subgroup 2, four of them suffered from epilepsy. The subclinical epileptiform activity on EEG was observed in 5 (10%) children. The Wechsler test showed that general IQ scores were low (<95%) in 4 (20%) children of this subgroup. No significant difference was found in the performance on the Bayley-III scales between children from subgroup 1 and children born to healthy mothers (controls) though the scores on the fine motor scale and speech development scale were lower in 3 (10%) and 5 (16%) children of the index group, respectively.

[Epilepsy in a cohort of Senegalese children]

Epilepsy is a significant health public problem in Senegal with an estimated prevalence of 8 to 14%. The aim of this study was to determine the clinical and electroencephalographic features of epilepsy in a cohort of Senegalese infants, search for etiological factors and determine the impact of disease on school life. This retrospective study concerned 459 children who attended the neurological outpatients clinic at the Fann hospital, Dakar, Senegal, between July 2003 and December 2006. All were aged under 19 years. Among the 135 children with idiopathic epilepsy, 23.7% had parental consanguinity and 37.77 % familial epilepsy. Rolandic epilepsy and epilepsy with absences were more frequent but several infants with idiopathic epilepsy were not classified. Non-idiopathic epilepsy was noted in 312 children. In this group, estimates of parental consanguinity and familial epilepsy were of 21.79 and 17.94%, respectively. Etiological factors were predominantly pregnancy and birth abnormalities (28.84%) and central nervous system infection (20.19%). Twelve children had febrile seizures. Of patients with idiopathic epilepsy, 65.18% were attending school versus only 9.29 with non-idiopathic epilepsy.

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.

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.

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.

"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].

Outcome of children with juvenile absence epilepsy

The incidence and natural history of childhood absence epilepsy are well documented, but those of juvenile absence epilepsy are poorly delineated. We conducted a retrospective chart study to evaluate the incidence and outcome of patients with juvenile absence epilepsy by retrieving the medical records of consecutive patients with juvenile absence epilepsy who were evaluated in three pediatric neurology outpatient clinics in Israel. Inclusion criteria included the onset of epilepsy after the age of 10 years and follow-up until at least 15 years of age. The patients with an electroencephalogram (EEG) suggestive of myoclonic epilepsy (polyspike and wave) were excluded from the study. Seventeen patients (10 female and 7 male) fulfilled the inclusion criteria for juvenile absence epilepsy. They presented with epilepsy at a mean age of 11.94 years (range 10-16.5 years). The mean duration of follow-up was 6.05 years (range 2-12 years). Five patients (29.4%) had a family history of epilepsy. All 17 patients had a normal neurodevelopmental status. Eight patients (47%) experienced generalized tonic-clonic seizures. At follow-up, eight patients (43.7%) were seizure free. Only three (37.5%) of the patients who experienced generalized tonic-clonic seizures were seizure free during follow-up compared with five (55.5%) patients without generalized tonic-clonic seizures. Our results indicate that the outcome of patients with juvenile absence epilepsy is less favorable than children with childhood absence epilepsy and that the presence of generalized tonic-clonic seizures is a predictor for poorer outcome.

[Typical absence seizure: epidemiological and clinical characteristics and outcome]

OBJECTIVE

To analyze the epidemiological and clinical characteristics and outcome of absence epilepsy in the pediatric age group with the aim of facilitating its diagnosis in clinical practice.

PATIENTS AND METHODS

Information on epidemiological and clinical characteristics, complementary investigations, and outcome was collected from the medical records of 51 children with absence epilepsy. The criteria defined by the International League Against Epilepsy (ILAE) were used in the diagnosis.

RESULTS

Fifty-one percent of the patients had simple absence seizures and 49% had complex absence seizures. A total of 70.6% of the patients were school-aged children and the prevalence was greater among girls (72.5%). The mean age at onset was 7.5 +/- 2.7 years. In 80%, there were multiple seizures per day with a mean duration of 12 seconds. School performance was impaired in 19.6%. Ictal electroencephalogram showed generalized 3 Hz spike and slow wave complexes in 84.3%. Hyperventilation was positive in 98%, and intermittent photic stimulation was positive in 15.7%. The seizures were controlled by sodium valproate (mean dosage: 26 mg/kg/day) in 84.3% of the patients. In 43 patients antiepileptic drugs were withdrawn (mean duration: 3.3 +/- 0.6 years) but 3 patients relapsed.

CONCLUSIONS

Typical absences are a common type of epilepsy in the pediatric age group and generally begin in school-aged children. Absences may be difficult to detect and can impair learning. Treatment response is excellent. Nevertheless, because absences may be the first manifestation of severe forms of epilepsy syndromes, strict follow-up of these patients is essential.

[Neuropsychiatric aspects of diagnostics of nonepileptic seizures]

The outcome of nonepileptic seizures (NES) is usually poor. The early recognition suggests better prognosis. This study is undertaken to examine the value of neuropsychiatric method for making accurate diagnosis of the psychiatric disorder that underlies psychogenic NES. Multidisciplinary approach to clinical assessment of such patients with chronic or resistant course of seizure disorder was used. Out of 6 patients, who went through the neuropsychiatric evaluation, two were admitted with a diagnosis of status epilepticus, three--with acute episodes of repetitive seizures and one--with diagnoses of bettolepsy. The results demonstrated that in four cases seizures were the manifestation of dissociative disorder (F 44), in one--of somatic form autonomic dysfunction (F 45.3) and the last patient had delirium due to epilepsy. All of the four patients with the past history of epilepsy were treated with antiepileptic drugs (AED). In two cases diagnosis of epilepsy and AED therapy were withdrawn. In the remaining cases we supposed the coexistence of epilepsy and NES. Our data suggests that incorporating of neuropsychiatric methods into the diagnostic battery for people with suspected and/or intractable epilepsy help in distinguishing NES and epilepsy as well as in revealing the underlying psychic disorder, which leads to formulation specific treatment program.

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.

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.

Childhood Absence Epilepsy: Evolution and Prognostic Factors

PURPOSE

To evaluate how diagnostic criteria influence remission rates for patients with childhood absence epilepsy (CAE) and to assess clinical and EEG parameters as predictors of outcome.

METHODS

One hundred nineteen patients were diagnosed with CAE, according to International League Against Epilepsy (ILAE) classification criteria. They were subsequently evaluated according to stricter diagnostic criteria. Sixty-two subjects fulfilled these criteria as group 2; 57 did not and constituted group 1. Diagnostic parameters that prevented patients of group 1 from entering group 2, and variables such as sex, familial history of generalized epilepsy, and personal history of febrile convulsions also were tested as prognostic factors for terminal remission.

RESULTS

Compared with those in group 1, patients of group 2 had significantly higher rates of seizure control (95% vs. 77%), higher rates of terminal remission (82% vs. 51%), fewer generalized tonic-clonic seizures (8% vs. 30%), and shorter mean periods of treatment (2.2 vs. 3.8 years). Significantly fewer patients were receiving polytherapy in group 2 than in group 1 (11% vs. 47%), and fewer patients had seizure relapses at antiepileptic drug discontinuation (0 vs. 22%).

CONCLUSIONS

Remission rates of patients with CAE are greatly influenced by the classification criteria used for selection. Stricter diagnostic criteria allow the definition of a homogeneous group of patients with excellent prognosis. Factors predicting unfavorable prognosis were generalized tonic-clonic seizures in the active stage of absences, myoclonic jerks, eyelid myoclonia or perioral myoclonia, and EEG features atypical for CAE.

Absenzen als Differenzialdiagnose bei Kindern mit Aufmerksamkeitsdefizit-Syndrom

OBJECTIVES

Absences are regarded as one of the most important differential diagnosis of attention and resulting school-problems. Attention deficit-symptoms might develop through absences, even though there is no diagnosis of attention-deficit/ hyperactivity disorder or attention-deficit disorder (ADHD or ADD). Routine EEG-wavings are made, in order to exclude epilepsy as a reason for attention-deficits.

METHODS

In this paper the EEGs of 8 132 male and female children and adolescents from two hospitals for child and adolescent psychiatry were analyzed retrospectively. The aim of the study was to assess how many patients with absences do occur and whether they do present a specific psychopathology.

RESULTS

In summary for the first time diagnosed absences occurred in 0.44 % (N = 12) of the patients in the first centre and in none of the patients in the second centre. The average age was 9.5 years. 50 % of the patients were diagnosed with ADHD. A specific psychopathology of the patients was not found.

CONCLUSIONS

There is a minimal occurrence of absences in child and adolescent patients. Therefore it is not a main differential diagnosis, that has to be considered in children with attention-deficit problems. Due to the late age at the time of diagnosis and the possible good treatability with antiepileptics, it is nevertheless important to regard absences as a rare differential diagnosis.

Depression and Anxiety Disorders in Pediatric Epilepsy

PURPOSE

This study examined affective disorders, anxiety disorders, and suicidality in children with epilepsy and their association with seizure-related, cognitive, linguistic, family history, social competence, and demographic variables.

METHODS

A structured psychiatric interview, mood self-report scales, as well as cognitive and language testing were administered to 100 children with complex partial seizures (CPSs), 71 children with childhood absence epilepsy (CAE), and 93 normal children, aged 5 to 16 years. Parents provided behavioral information on each child through a structured psychiatric interview and behavior checklist.

RESULTS

Significantly more patients had affective and anxiety disorder diagnoses (33%) as well as suicidal ideation (20%) than did the normal group, but none had made a suicide attempt. Anxiety disorder was the most frequent diagnosis among the patients with a diagnosis of affective or anxiety disorders, and combined affective/anxiety and disruptive disorder diagnoses, in those with suicidal ideation. Only 33% received some form of mental health service. Age, verbal IQ, school problems, and seizure type were related to the presence of a diagnosis of affective or anxiety disorder, and duration of illness, to suicidal ideation.

CONCLUSIONS

These findings together with the high rate of unmet mental health underscore the importance of early detection and treatment of anxiety disorders and suicidal ideation children with CPSs and CAE.

A deletion in SCN1B is associated with febrile seizures and early-onset absence epilepsy

Generalized epilepsy with febrile seizures plus (GEFS+) is a clinically and genetically heterogeneous syndrome with childhood onset, characterized by febrile seizures (FS) and a variety of afebrile epileptic seizure types. The authors performed a mutational analysis of SCN1B on 74 unrelated probands with GEFS+, FS, or FS plus (FS+). In a family with FS+ and early-onset absence epilepsy, a mutation was identified that predicts a deletion of five amino acids in the extracellular immunoglobulin-like domain of SCN1B and potential loss of function. SCN1B mutations are associated with GEFS+ and may have a role in the elicitation of absence seizures.

Acute management of seizures in the syndromes of idiopathic generalized epilepsies

Three of the seizure types (myoclonic, absence, and generalized tonic-clonic) and syndromes associated with idiopathic generalized or genetic epilepsies can present an acute status epilepticus picture that requires acute therapy. These are not the usual seizures observed in status epilepticus because most of these patients have secondary generalized or symptomatic generalized convulsive seizures. In this review, I discuss the unique presentation and treatment options for the acute management of seizures in the syndromes of idiopathic generalized epilepsy (IGE), with special emphasis on the seizures of status epilepticus, which persist over time or occur in a series without recovery of consciousness.

The gene encoding GABBR1 is not associated with childhood absence epilepsy in the Chinese Han population

Childhood absence epilepsy (CAE) is considered to be a genetic disease, but the genes responsible for it have not yet been identified. To investigate whether or not the GABBR1 gene is a susceptibility gene for CAE in the Chinese Han population, we systematically screened all the 22 exons and nearby intron regions of the gene and found 12 single nucleotide polymorphisms (SNPs). Using four SNPs as markers, we conducted a case-control study in 96 CAE patients and 96 normal controls. There were no significant discrepancies between the cases and controls in allele and phenotype frequencies of the four SNPs. There were still no significant differences in haplotype distributions between the cases and controls. We postulate that the GABBR1 gene might not be a susceptibility gene for CAE at least in the Chinese population.

Behavioral disorders in pediatric epilepsy: unmet psychiatric need

PURPOSE

This study examined the relation between psychiatric diagnosis and mental health services in children with epilepsy and the associated demographic, cognitive, linguistic, behavioral, and seizure-related variables.

METHODS

The Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS), the Child Behavior Checklist, the Test of Language Development, and the Wechsler Intelligence Scale for Children-Revised (WISC-R) were administered to 114 children, aged 5 to 16 years, with either complex partial seizures (CPS) or primary generalized with absence (PGE, petit mal). A Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) diagnosis and information regarding mental health services were derived from the K-SADS.

RESULTS

Although approximately 60% of the subjects had a DSM-IV psychiatric diagnosis, >60% received no mental health treatment. Absence of mental health care was associated with younger age, less parental education, limited number of antiepileptic drugs (AEDs; i.e., one or none), and higher verbal IQ. In addition, children with PGE and a single psychiatric diagnosis were less likely to have a history of mental health treatment.

CONCLUSIONS

This is the first study to demonstrate unmet mental health need in a large sample of children with CPS and PGE. The study's findings suggest that parents and clinicians should be aware of the mental health needs of children with epilepsy, particularly if they have one or more of the identified risk factors.

Tonic-absence seizures: an underrecognized seizure type

PURPOSE

The individual electroclinical patterns--tonic seizures with generalized paroxysmal fast activity (GPFA, activity >13 Hz), and absence seizures with generalized slow spike-and-wave activity (GSS&W, <3 Hz)--have been extensively described in the literature. However, only passing reference was made to the pattern of GPFA followed by GSS&W. In addition, these descriptions were formulated in the pre-EMU (Epilepsy Monitoring Unit) era, without benefit of video/clinical correlation. We now characterize this underrecognized seizure type.

METHODS

We retrospectively reviewed the data from eight patients with seizures that demonstrated this stereotyped EEG and clinical pattern.

RESULTS

We identified eight patients (six female patients; age 6-29 years; age at seizure onset, neonate to 10 years) who were evaluated at the Columbia University Epilepsy Monitoring Units between 1993 and 2002. All eight had an International League Against Epilepsy (ILAE) diagnosis of symptomatic generalized epilepsy, with six of eight manifesting multiple seizure types, six of eight with mild static encephalopathy, and two with normal cognition. A total of 29 seizures of this pattern was recorded; 26 of 29 seizures demonstrated GPFA (frequency between 14 and 30 Hz, lasting 2-8 s) followed by GSS&W (frequency range between 1 and 2 Hz, lasting 3-50 s). The predominant clinical correlate was bilateral tonic activity followed by a period of inattentiveness. In general, these seizures were differentiated from the patient's typical tonic seizures by this protracted period of impaired attentiveness.

CONCLUSIONS

We describe a heretofore underrecognized and poorly characterized seizure type in patients with symptomatic generalized epilepsy, which we have termed tonic-absence seizures. Clinically and electrographically, this consists of a tonic seizure with GPFA followed by an absence seizure with GSS&W.

Early-onset absence epilepsy and paroxysmal dyskinesia

PURPOSE

To report on the association of childhood absence epilepsy and paroxysmal dyskinesia (PD).

METHODS

We describe six patients aged 6 to 27 years (mean, 14 years) who were identified in five centers participating in a European study group. Patients had been followed up clinically from the first symptoms and had been studied with video-EEG recordings of absence seizures, videotaping of dyskinetic attacks, and brain magnetic resonance imaging (MRI).

RESULTS

Four patients were sporadic, and two were siblings. Age at onset of absence seizures was unusually early (range, 3 months to 3 years 6 months; mean, 16 months), with four children having their first episodes within the first year of life, and the remaining two by age 3 years 6 months. Resistance to multiple appropriate drugs was seen in five children, in four of whom absences improved remarkably when ethosuximide was added. Absences remitted between age 8 and 13 years in the three patients in whom follow-up was long enough. Different types of PD were seen including paroxysmal kinesigenic dyskinesia (one patient), paroxysmal exercise-induced dystonia (three patients), and paroxysmal tonic upgaze (two siblings). In most patients, PD appeared at a later age than, co-occurred with, and outlasted absence seizures. Only in the two siblings with tonic upgaze, dyskinetic attacks had an earlier onset. PD improved with increasing age and did not usually produce severe disability.

CONCLUSIONS

There is a widening spectrum of epilepsy and PD syndromes, within which epilepsy has the characteristics of the common idiopathic syndromes, with some atypical features.

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

PURPOSE

The existence of absence epilepsy and temporal partial seizure pattern in the same patient is an uncommon state. In the present study, we aimed to evaluate whether the process of kindling as a model of complex partial seizures with secondary generalization is altered in rats with genetic absence epilepsy.

METHODS

Six- to 12-month-old nonepileptic control Wistar rats and genetic absence epileptic rats from Strasbourg (GAERS) were used in the experiments. One week before the experiments, bilateral stimulation and recording electrodes were implanted stereotaxically into the basolateral amygdala and cortex, respectively. Animals were stimulated at their afterdischarge threshold current twice daily for the process of kindling and accepted as fully kindled after the occurrence of five grade 5 seizures. Bilateral EEGs from amygdala and cortex were recorded continuously during 20 min before and 40 min after each stimulus.

RESULTS

All control Wistar rats were fully kindled after stimulus 12 to 15. Although the maximal number of stimulations had been applied, GAERS remained at stage 2, and no motor seizures were observed. The afterdischarge duration in bilateral amygdala and the cortex after the kindling stimulus was shorter in GAERS when compared with control rats.

CONCLUSIONS

Occurrence of only grade 2 seizures and no observation of grade 3-5 seizures in GAERS with the maximal number of stimulations would suggest that the generalized absence seizures may be the reason of the resistance in the secondary generalization of limbic seizures during amygdala kindling.

Childhood absence epilepsy: genes, channels, neurons and networks

Childhood absence epilepsy is an idiopathic, generalized non-convulsive epilepsy with a multifactorial genetic aetiology. Molecular-genetic analyses of affected human families and experimental models, together with neurobiological investigations, have led to important breakthroughs in the identification of candidate genes and loci, and potential pathophysiological mechanisms for this type of epilepsy. Here, we review these results, and compare the human and experimental phenotypes that have been investigated. Continuing efforts and comparisons of this type will help us to elucidate the multigenetic traits and pathophysiology of this form of generalized epilepsy.

Genetic predisposition to severe myoclonic epilepsy in infancy

PURPOSE

To address genetic predisposition to febrile convulsions (FCs) and epilepsy as an etiologic background of severe myoclonic epilepsy in infancy (SMEI).

METHODS

Familial antecedents of epilepsy and FCs were analyzed in four groups of patients with SMEI (65 cases), FCs (57 cases), childhood absences (67 cases), and a control group of patients with no neurologic problems (64 cases).

RESULTS

Patients with SMEI and those with FCs had significantly increased incidence of FCs in their relatives compared with those with absence epilepsy and with the control group. The incidence of epilepsy in relatives of patients with SMEI and absence epilepsy was increased compared with that in the control group and reached statistical significance. Epilepsy in relatives with SMEI had the characteristics of idiopathic generalized epilepsy.

CONCLUSIONS

A genetic predisposition could determine three types of epileptic syndromes: FCs, idiopathic generalized epilepsy, and SMEI.

[Idiopathic absence epilepsy]

The International Classification of Epilepsies and Epileptic Syndromes distinguishes four types of idiopathic generalized epilepsies with typical absences: childhood absence epilepsy (CAE), juvenile absence epilepsy (JAE), juvenile myoclonic epilepsy (JME) and epilepsy with generalized grand mal on awakening (EGMA). It is essential in any case when sizures occur to classify the type of epileptic syndrome in order to make prognosis and to choose correct treatment. But it is not always possible to establish diagnosis at the beginning of the disease. Often prolonged observation of the patient and evolution of clinical and EEG features lead to define the epileptic syndrome. The aim of the work was to define the type and frequency of epileptic syndromes and their long-term observation in patients with absences occurred as the first (or the only) type of seizures.

SUBJECTS AND METHODS

31 patients who experienced absences as the first (or the only) type of seizures were selected from the group of 600 subjects suffered from epilepsy admitted to the Neuropediatric Department of the National Research Institute of Mother and Child between 1987 and 1998. Epileptic Syndromes were classified according to the International Classification.

RESULTS

There were 31 (5.2%) patients (18 girls and 13 boys) with absences accurred as the first (or the only) type of seizures. The age of the onset of seizures was between 2.5 to 13.5 years (mean 9.3). Seven of them had also tonic-clonic seizures in the course of the observation. They were followed-up for 3 to 9 years (mean 9.2) till the age of 7 to 25 years (mean 18.5). Two epileptic syndromes were established according to the International Classification:--childhood absence epilepsy (CAE) in 27 (4.5%) patients;--juvenile absence epilepsy (JAE) in 4 (0.7%) patients. No one patient showed evolution of disease towards neither juvenile myoclonic epilepsy nor epilepsy with generalized grand mal on awakening during follow-up.

CONCLUSIONS

5.2% of all subjects were patients with idiopathic epilepsies who experienced absences as a first (or the only) type of seizures when absences occur one should consider first of all childhood absence epilepsy and juvenile absence epilepsy. Recognition of juvenile myoclonic epilepsy and epilepsy with generalized grand mal on awakening is less probable.

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

INTRODUCTION AND OBJECTIVE

The objective of the study was to analyze the EEG tracings during the seizures of two monozygotic twins, shown on molecular analysis, diagnosed as having infantile epilepsy with absences. The recordings are particularly interesting since the genotypes of the patients are identical. This allowed comparison between the similarities and differences in discharges so that they could be better defined.

RESULTS

The 3 Hz spike and wave complexes were the same as the classical descriptions in typical absences. No 'W' spike and wave complexes morphology, discharge fragmentation or light induction of the discharges were observed. There was some differences in the duration of absences, which were much shorter in one twin girl. The duration of the seizures was variable, and sometimes similar to that described as characteristic in other types of generalized idiopathic epilepsies with absences. It would seem therefore that the duration of the seizure is not a criterion for differentiation between the different types of generalized idiopathic epilepsies.

CONCLUSION

Concordance, both clinical and of seizure EEG recordings in our patients confirmed that there is a specific electroclinical phenotype in infantile epilepsy with absences, although individual variations may also occur.

No, some types of nonconvulsive status epilepticus cause little permanent neurologic sequelae (or: "the cure may be worse than the disease")

Nonconvulsive status epilepticus (NCSE) is characterized by a cognitive or behavioral change which lasts for at least 30 minutes, with EEG evidence of seizures. Although there is little argument that generalized nonconvulsive status epilepticus (GNSE) does not cause lasting deficits, there is still debate regarding the morbidity of complex partial status epilepticus (CPSE). Because the EEG is used for diagnosis, a strong argument can be made that NCSE is significantly under-recognized and diagnosed. Furthermore, since the documented cases of permanent neurologic sequelae are few, the potential permanent morbidity from CPSE may be significantly exaggerated. The literature indicates that comatose patients have a poor prognosis largely as a result of comorbid conditions and coma, whereas lightly obtunded or slightly confused patients with NCSE have little or no sequelae. Patients with NCSE may suffer (hypotension and respiratory suppression) from iatrogenic 'aggressive' treatment with intravenous anti-epileptic drugs (IV-AEDs), and the findings in the literature indicate that subjects treated with benzodiazepines may have a worse prognosis. The clinician must balance the potential but rare neurologic morbidity associated with NCSE against the not infrequent morbidity caused by IV-AEDs. Better stratification of the level of consciousness and comorbid conditions is needed when evaluating outcomes so as to clearly distinguish among the deficits due to: comorbid conditions; the effects of treatment and the effects of status epilepticus (SE) proper.

Absence seizures with evolution into generalized tonic-clonic activity: clinical and EEG features

PURPOSE

To report the clinical and electrographic features of absence seizures evolving into generalized tonic-clonic (GTC) activity in six patients with idiopathic generalized epilepsy.

METHODS

All patients were referred for evaluation of refractory seizures and underwent video-EEG monitoring after discontinuation of their antiepileptic drugs (AEDs). We analyzed the video-EEG recordings for seizure semiology as well as ictal and interictal activity. We also reviewed the initial clinical data in all patients.

RESULTS

All patients were women, with a mean age of 27 years (range, 14-43 years). The mean age at seizure onset was 12 years (range, 5-15 years). Family history was positive for epilepsy in four patients. All patients had recorded seizures with an onset that was characteristic of generalized absence clinically and electrographically, with evolution into GTC activity. The EEG onset was with generalized 2.5-to 5-Hz spike-and-wave discharges, with evolution into faster rhythmic activity. Interictal EEG recordings showed generalized 2-to 5-Hz spike-and-wave discharges. All had normal background activity. All patients were treated with divalproex monotherapy. Five patients have been seizure free, and one had a single breakthrough GTC seizure during a follow-up period of 12-36 months.

CONCLUSIONS

GTC activity may evolve from typical absence seizures. This seizure type should be included in the International Classification of Seizures. Its recognition and distinction from complex partial seizures with secondary generalization are important for appropriate therapy.

Nonconvulsive status epilepticus in childhood localization-related epilepsy

PURPOSE

To report on three children with localization-related epilepsy who exhibited minor seizures (atypical absences, brief atonic, and myoclonic) and nonconvulsive status epilepticus (NCSE) consisting of these minor seizures, and to elucidate their significance.

METHODS

We studied the electroclinical characteristics of these children. Ictal electroencephalograms (EEGs) of NCSE were evaluated by using simultaneous video-EEG-electromyogram (EMG) polygraphic recordings.

RESULTS

All patients began to have partial seizures between the ages of 6 months and 2 years 7 months, with minor seizures appearing later, between the ages of 1 year 11 months and 6 years 6 months. These minor seizures evolved into NCSE. Complex partial seizures remained after suppression of the minor seizures. Interictal EEGs taken when the minor seizures appeared showed excessive diffuse epileptic discharges in addition to multifocal spike-waves. Before and after suppression of the minor seizures, focal epileptic discharges predominated on the EEGs. On ictal EEGs of brief atonic and myoclonic seizures, diffuse spike-wave and polyspike-wave bursts were detected. Ictal EEGs of the atypical absences revealed diffuse spike-wave bursts mixed with irregular high-voltage slow waves, often interspersed with brief atonic and myoclonic seizures. When atypical absences lasted for a long time, patients manifested NCSE. Polytherapy might be related to the occurrence of minor seizures and NCSE, because all patients were treated with polytherapy at their appearance, and simplification of antiepileptic drug (AED) therapy seemed to be effective.

CONCLUSIONS

We concluded that this NCSE is a type of atypical absence status which is an age-dependent, transient, electroclinical condition. The mechanism of occurrence of these minor seizures might be related to secondary bilateral synchrony.

Non-epileptic attack disorder (NEAD): a comprehensive review

Non-epileptic attack disorder (NEAD) represents a well-recognized clinical problem with a reported incidence among individuals with a diagnosis of intractable epilepsy as high as 36%. A failure to identify this disorder may lead to certain risks for the patient including polypharmacy, anticonvulsant toxicity, hazardous intervention, social and economic demands and a lack of recognition or neglect of any underlying psychological distress. This review provides a description of NEAD in an historic and societal context and discusses the variety of terminology which has been applied to this psychophysiological phenomenon. Epidemiology and associated methodological limitations; and diagnostic and classification issues related to NEAD in comparison to epilepsy are considered. The problems of failure to recognize NEAD in comparison to epilepsy are considered. The problems of failure to recognize NEAD are outlined, and theoretical and empirical aetiological issues are discussed.

Typical absence status in adults: diagnostic and syndromic considerations

PURPOSE

To study the electroclinical features of typical absence status (TAS) in adults with syndromes of idiopathic generalized epilepsies (IGEs).

METHODS

Twenty-one patients with one or more spells of TAS were identified among 136 consecutive adult patients with IGEs. All patients with TAS had comprehensive electroclinical investigations and EEG or video-EEG recorded absences.

RESULTS

TAS occurred in 24.4% of 86 patients who had IGEs with typical absences alone or in combination with other seizures presisting in adult life. The prevalence of TAS appeared to be syndrome related, ranging from as high as 57.1% in perioral myoclonia with absences and 46.2% in "phantom" absences with GTCS to as low as 6.7% in juvenile myoclonic epilepsy. A varying degree of impairment of cognition was the cardinal clinical symptom shared in all TAS, but corresponding syndromes of IGE were often betrayed by other symptoms such as eyelid or perioral myoclonia. In phantom absences with GTCS, TAS was more numerous (p < or = 0.05) and more frequently the first overt seizure type (p = 0.006) than in any other IGE. Only in the syndrome of eyelid myoclonia with absences, TAS was always situation related, mainly as a result of antiepileptic drug discontinuation.

CONCLUSIONS

The clinical EEG semiology and prevalence of TAS appear to be syndrome related with the highest prevalence in the syndromes of perioral myoclonia with absences and phantom absences with GTCS (p = 0.0024).

Myoclonic absence-like seizures and chromosome abnormality syndromes

PURPOSE

We explored the relationship between myoclonic absence seizures (MAS) and underlying chromosome disorders.

METHODS

Among 14 patients with MAS observed in three centers, 5 had typical cryptogenic myoclonic absence epilepsy (MAE), 2 had MAS associated with other seizure types (1 with signs of a neuronal migration abnormality and 1 with signs of a metabolic disorder), and 7 had MAS, with or without other seizure types, complicating a chromosome abnormality syndrome-2 with trisomy 12p, 4 with Angelman syndrome, and 1 with inv dup (15).

RESULTS

In the 7 patients with chromosomopathy, MAS appeared at a mean age of 2.9 years (range 4 months to 6 years 6 months), had a duration of 4-20 s, and were accompanied by reduced awareness and rhythmic myoclonic jerks involving proximal limb muscles. Ictal EEG showed 2- to 3-Hz generalized spike-and-wave discharges.

CONCLUSIONS

In these patients, MAS differed slightly from those of typical MAE: age of onset was earlier, absences were of shorter duration, and no clear increase in muscular tone was noted. Abnormal expression of genes codifying for the subfamily of K+ channels and for gamma-aminobutyric acid-3 subunit receptors (GABRB3), both located in the chromosome segments involved in the chromosomopathies presented by our patients, could be responsible for the same generalized seizure type. Chromosome analysis should be performed in patients with mental retardation and MAS, especially when the ictal pattern does not completely overlap that observed in MAE.

Clinical observations of juvenile myoclonic epilepsy in 131 patients: a study in South India

We studied clinical features of 131 patients with juvenile myoclonic epilepsy (JME). The prevalence was 7.7% among the epileptic patients registered. The mean age at onset was 13.37+/-4.93 years and the diagnosis was established at a mean age of 19.53+/-7.85 years. Absence seizures were reported by 27 (20.6%) patients, myoclonic jerks by 131 (100%) and generalized tonic-clonic seizures (GTCS) by 111 (84.7%). The triad of absence seizures, myoclonic jerks and GTCS was noted in 23 (17.5%) patients, 88 (67.2%) had myoclonic jerks and GTCS, 4 (3%) had absence seizures and myoclonic jerks and 16 (12.2%) had only myoclonic jerks. Early onset absences were seen in 21 (16%) patients and the onset was late in 6 (4.6%). Absences antedated other types of seizures in all the patients. Myoclonic jerks were predominantly unilateral or had unilateral onset in 22 (16.8%). In 17 (13%) patients GTCS antedated myoclonic jerks. Myoclonic jerks had characteristic circadian distribution in 112 (85.5%) patients. On awakening GTCS occurred in 87 (78.4%) patients and in 4 (3.6%) patients they were purely nocturnal. Sleep deprivation was the most important precipitating factor (54.2%). Initial electroencephalogram (EEG) showed classical generalized spike or multiple-spike slow-wave paroxysms in 81% of records. Focal EEG abnormalities were noted in 20.6% of records. The most common focal abnormality was voltage asymmetry. A family history of epilepsy was noted in 31 (23.6%) probands. Diagnosis of JME was made in all the cases in the clinic. The factors responsible for delay in diagnosis of the 36 patients seen by neurologists included failure to ask or interpret the history which was otherwise suggestive of myoclonic jerks in all 36 (100%) cases, the type of seizure for which the patients sought medical attention, and misinterpretation of EEGs in 28 patients. Diagnosis of partial epilepsy was made in seven patients. The factors responsible for such diagnoses were, unilateral jerks in one patient, unilateral jerks and absence seizures in three patients and focal EEG abnormalities in three patients.

Long-term studies on patients with absence and bilateral spike-wave complexes: 430 patients, up to 52 years follow-up

This study involved long-term changes, up to 52 yrs, in 430 patients with absence (A) attacks and bilateral spike and wave complexes (BSW). Nearly 2/3 had additional GTC attacks and only about 1/4 had A alone. Atonic attacks (7%), complex partial (CP) (4%) and other types of seizures also occurred in the group. Distinctive features of the GTC group were diffuse slow waves and 6/sec spike and wave complexes, and of the A alone were BSW as the only abnormality and later normal records. For CP or focal motor (FM) attacks, nearly all had focal spikes and these seizures appeared between 15-25 yrs of age. The background alpha rhythm with increasing age showed more rhythmicity, but lower amplitudes in all of these patients. Onset age was an important factor in that the highest peak was at 6 yrs, mainly from those with A only and a minor peak appeared at 13-14 yrs, mainly from the patients with GTC seizures. One major difference between the group with A alone and those with GTC attacks was that normal records developing with A alone usually remained normal, while those with GTC attacks usually became abnormal again. The 6/sec spike and wave complexes usually appeared after the onset of GTC attacks, often at 18-19 yrs of age. Diffuse slowing usually appeared after GTC attacks at around 16 yrs after the onset of these seizures. Possible forerunners of BSW were multifocal spikes at < 4 yrs of age, occipital or temporal spikes at 5-16 yrs and temporal spikes after 16 yrs of age. CP seizures could be predicted from the EEG by focal spikes, especially on the temporal lobe, appearing over long periods of time in records with an inconsistent BSW. Patients with A extending into adulthood were distinctive by a later onset of A and a history of GTC attacks. In general, more females were seen in this study but there were more males with A alone and more developed a normal record. Females often had a later onset of A, with GTC attacks, and the older the patient in this study the more likely the patient was female. Evidence is seen in this study for prediction of (1) future BSW by different types of focal spikes at different ages, (2) CP (or FM) seizures by focal spikes and an inconsistent BSW, (3) GTC seizures by onset age, female sex, and EEG reverting to an abnormal record after normalizing, (4) A attacks alone by onset age, male sex and finally a normalized EEG, and (5) GTC or myoclonic attacks by the presence of BSW as the only abnormality.

Allelic association of juvenile absence epilepsy with a GluR5 kainate receptor gene (GRIK1) polymorphism

Juvenile absence epilepsy (JAE) is a common subtype of idiopathic generalized epilepsy (IGE). Hereditary factors play a major role in its etiology. The important function of glutamate receptors (GluRs) in excitatory neurotransmission, synaptic plasticity, and neurodevelopment suggests their involvement in epileptogenesis. A tetranucleotide repeat polymorphism in the non-coding region of the kainate-selective GluR5 receptor gene (GRIK1) on chromosome 21q22.1 provides the tool to investigate this candidate gene. The present association and linkage study tested the hypothesis that allelic variants of GRIK1 confer genetic susceptibility to the pathogenesis of JAE. Our family-based association analysis using the haplotype-based haplotype relative risk statistic revealed an association of JAE with the nine-repeat containing allele of the GRIK1 tetranucleotide polymorphism (chi2 = 8.31, df = 1, P = 0.004). Supportive evidence for linkage to a JAE related IGE spectrum (Zmax = 1.67 at GRIK1) under an autosomal dominant mode of inheritance and significant allele sharing (P < 0.05) among the affected family members suggest that allelic variants of GRIK1 contribute a major genetic determinant to the pathogenesis of JAE-related phenotypes.